Recent zbMATH articles in MSC 90B https://www.zbmath.org/atom/cc/90B 2021-04-16T16:22:00+00:00 Werkzeug Bandwidth allocation and resource adjustment for stability enhancement in complex networks. https://www.zbmath.org/1456.90170 2021-04-16T16:22:00+00:00 "Tsang, K. Y. Henry" https://www.zbmath.org/authors/?q=ai:henry-tsang.k-y "Wong, K. Y. Michael" https://www.zbmath.org/authors/?q=ai:wong.kwok-yee-michael Fatigue effect on phase transition of Pedestrian movement: experiment and simulation study. https://www.zbmath.org/1456.82372 2021-04-16T16:22:00+00:00 "Luo, Lin" https://www.zbmath.org/authors/?q=ai:luo.lin "Fu, Zhijian" https://www.zbmath.org/authors/?q=ai:fu.zhijian "Zhou, Xiaodong" https://www.zbmath.org/authors/?q=ai:zhou.xiaodong "Zhu, Kongjin" https://www.zbmath.org/authors/?q=ai:zhu.kongjin "Yang, Hongtai" https://www.zbmath.org/authors/?q=ai:yang.hongtai "Yang, Lizhong" https://www.zbmath.org/authors/?q=ai:yang.lizhong Supply chain intelligence. Application and optimization. https://www.zbmath.org/1456.90031 2021-04-16T16:22:00+00:00 "Kumar, Kaushik (ed.)" https://www.zbmath.org/authors/?q=ai:kumar.kaushik "Davim, J. Paulo (ed.)" https://www.zbmath.org/authors/?q=ai:davim.j-paulo Publisher's description: The book provides an introduction to logistics and supply chain management and the application of evolutionary computation, focusing on specific fields related to supply chain issues, from strategic sourcing decisions, and production planning and control to inventory to logistics and its application using evolutionary / heuristics techniques. Bridging the gap between management research, decision-making and computer analysis, this interdisciplinary book features state-of-the-art descriptions of the corresponding problems and advanced methods for solving them. The articles of this volume will be reviewed individually. Transportation-inventory model for electronic markets under time varying demand, retailer's incentives and product exchange scheme. https://www.zbmath.org/1456.90013 2021-04-16T16:22:00+00:00 "Mukhopadhyay, Arindum" https://www.zbmath.org/authors/?q=ai:mukhopadhyay.arindum Summary: Exchange offers are popular in many businesses to attract new customers. Availability of novel varieties, stiff competition, and regulatory restriction of discarding old products enhances to facilitate such offers in the market. Although, the reduction of out-of-pocket expenses to the customers helps to increase the sale of products; it also elevates the decision problem for managing the inventories of the exchanged products for the retailers. In view of this, the present article addresses inventory decision modeling in a system where a customer can buy products from the electronic-market retailer either by paying the full price or getting some price-discount for exchanging old products. Retailer bears transportation costs for the new and exchanged products. Four models are formulated and numerical examples are presented. Sensitivity analysis is also performed to understand the effect of various parameters in the models. For the entire collection see [Zbl 1452.90002]. A fuzzy two-echelon supply chain model for deteriorating items with time varying holding cost involving lead time as a decision variable. https://www.zbmath.org/1456.90019 2021-04-16T16:22:00+00:00 "Shee, Srabani" https://www.zbmath.org/authors/?q=ai:shee.srabani "Chakrabarti, Tripti" https://www.zbmath.org/authors/?q=ai:chakrabarti.tripti Summary: In this paper, we have developed a two-stage supply chain production-inventory model for deteriorating product with time-dependent demand under fuzzy environment. Here we describe an EOQ model with changeable lead time and time-dependent holding cost. This situation is very common in the market, once an enterprise has some key technology or product that others have not, as a supplier, it can decide the prices and lead time of the technology or product to the buyers or retailers according to its need. Then the retailer determines his optimal order strategy, i.e., decides on the quantity of products to order from the suppliers. Under this circumstance, the problem that lead time, as a controllable variable of the supplier, and how it affects the cost to the supplier, retailer and whole supply chain is very important to the supplier and retailer because double-win benefits is a base of existence for the supply chain. In reality it is seen that we cannot define all parameters precisely due to imprecision or uncertainty in the environment. So we have defined the inventory parameters, such as set up cost, stock-out cost, and deterioration cost as triangular fuzzy numbers. The signed distance method and graded mean integration method have been used for defuzzification. To illustrate the proposed model a numerical example and sensitivity analysis with respect to different associated parameters has been presented. For the entire collection see [Zbl 1452.90002]. Fuzzy based inventory model with credit financing under learning process. https://www.zbmath.org/1456.90010 2021-04-16T16:22:00+00:00 "Jayaswal, Mahesh Kumar" https://www.zbmath.org/authors/?q=ai:jayaswal.mahesh-kumar "Sangal, Isha" https://www.zbmath.org/authors/?q=ai:sangal.isha "Mittal, Mandeep" https://www.zbmath.org/authors/?q=ai:mittal.mandeep Summary: Whilst business dealings, the cost of items is a vital consideration for the buyer in order to purchase goods as well as to minimize the items' cost. For the accomplishment of the same, the buyer performs a new task after a fluent repetition over daily dealing of goods and this new task is entitled as learning. Nowadays, learning's awareness is increasing across various disciplines because learning effect has a direct impact on the calculation of profit or loss and it is a promotional deemed effective tool for inventory management. The supplier wants an appreciable coordination with the buyers and analyzes with full detail, the concerned cost and the demand parameters as to how suitable the demand and the respective costs should be for the buyer. Fuzzy analysis is a good tool for examining the performance as well as the output of imprecise parameters involved in the business procedure. In this paper, we are assuming the holding costs to be partially constant and reduced per shipment, owing to the learning effects for finding an optimal cycle time and optimal average cost using the notion of learning effect with trade credit financing for EOQ under the fuzzy environment. The selling price, demand rate, and ordering cost per unit have been assumed to be imprecise in nature. In addition, these entities are also called fuzzy triangular numbers. The total optimal cost in fuzzy environment is de-fuzzified with the help of the centroid method. Toward the conclusion of this paper, some numerical examples as well as sensitivity analysis have been illustrated to verify this model. For the entire collection see [Zbl 1452.90002]. EOQ model under discounted partial advance -- partial trade credit policy with price-dependent demand. https://www.zbmath.org/1456.90006 2021-04-16T16:22:00+00:00 "Agrawal, Swati" https://www.zbmath.org/authors/?q=ai:agrawal.swati "Gupta, Rajesh" https://www.zbmath.org/authors/?q=ai:gupta.rajesh-kumar "Banerjee, Snigdha" https://www.zbmath.org/authors/?q=ai:banerjee.snigdha Summary: The aim of this article is to investigate an inventory model with discounted partial advance payment in a single supplier-single retailer supply chain in the presence of credit period when the demand rate is price sensitive. The lengths of the credit period, advance period, as well as rate of discount on advance payment, are specified by the supplier. Conditions for unique optimal values of the decision variables, namely, the retailer's selling price and cycle length are obtained. Optimal values of the decision variables are determined iteratively. An algorithm is developed and a numerical example is presented to demonstrate the solution algorithm. Sensitivity analysis is conducted. It is observed that optimal cycle time is affected by the two interest rates. Optimal net profit is affected by the demand rate and the discount factor. Both, the optimal cycle time, as well as the optimal net profit is affected by the supplier's selling price and the proportion of units for which the advance payment is made. Optimal retailer's selling price is significantly affected by the discount factor, supplier's selling price, price elasticity of the demand function as well as the proportion of units for which advance payment is made. We also observe that the retailer's net profit does not decrease significantly on increasing the advance period. For the entire collection see [Zbl 1452.90002]. Non-instantaneous deteriorating model for stock-dependent demand with time-varying holding cost and random decay start time. https://www.zbmath.org/1456.90009 2021-04-16T16:22:00+00:00 "Duari, Nirmal Kumar" https://www.zbmath.org/authors/?q=ai:duari.nirmal-kumar "Varghese, Jobin George" https://www.zbmath.org/authors/?q=ai:varghese.jobin-george Summary: In this study, we have considered an inventory model of non-instantaneous deteriorating items with stock-dependent demand. Shortages are allowed and fully backlogged. Holding cost is not always fixed; it may depend occasionally on time. That is why we have considered holding cost as constant as well as time-dependent in the model. Also, the effect of decay start time has been considered and they are random. We categorize the model into three cases. In the Cases I and II, we consider fixed decay start time with constant and time-varying holding cost, respectively. The random decay start time has been considered in the last case. Mathematical models have been derived to determine optimal-order quantity that minimizes the total cost. Optimal solution has been illustrated with numerical examples and along with that sensitivity analysis of parameters has been carried out. For the entire collection see [Zbl 1452.90002]. Imperfect quality item inventory models considering carbon emissions. https://www.zbmath.org/1456.90021 2021-04-16T16:22:00+00:00 "Wee, Hui-Ming" https://www.zbmath.org/authors/?q=ai:wee.huiming|wee.hui-ming "Daryanto, Yosef" https://www.zbmath.org/authors/?q=ai:daryanto.yosef Summary: Research on inventory models with environmental consideration has recently become a popular research stream. The amount of energy consumption and greenhouse gas emissions is influenced by inventory decisions such as delivery quantity and delivery frequencies. This chapter focuses on a supply chain system which contains a percentage of imperfect quality items in its delivered lot; we also consider carbon emission costs under a carbon tax policy. Processing the defective items, which increases carbon emission, affects supply chain decisions. We present two economic order quantity models considering carbon emission and defective items with different shortage conditions. We then study low-carbon two-echelon supply chain inventory model considering supply chain integration and imperfect quality items. Numerical examples are provided to illustrate how these models can be applied in practice. Sensitivity analysis is performed to gain more insight on changing parameters in the numerical studies. For the entire collection see [Zbl 1452.90002]. An economic order quantity (EOQ) inventory model for a deteriorating item with interval-valued inventory costs, price-dependent demand, two-level credit policy, and shortages. https://www.zbmath.org/1456.90018 2021-04-16T16:22:00+00:00 "Shaikh, Ali Akbar" https://www.zbmath.org/authors/?q=ai:shaikh.ali-akbar "Tiwari, Sunil" https://www.zbmath.org/authors/?q=ai:tiwari.sunil "Cárdenas-Barrón, Leopoldo Eduardo" https://www.zbmath.org/authors/?q=ai:cardenas-barron.leopoldo-eduardo Summary: In today's competitive environment, every leading organization wishes to improve the pricing strategies in order to increase revenue, credit policy is one of the best tools of it. This research work develops an economic order quantity (EOQ) inventory model for a deteriorating item that considers interval-valued inventory costs, price dependent demand, two-level credit policy, and shortages. Due to high and uncertainty in demand, sometimes organizations have to face the situation of stock out. So, keeping this scenario in mind, this work considers the situation of partially backlogging. Here, it is developed an EOQ inventory model by considering a non-linear interval-valued constrained optimization problem. Two types of particle swarm optimization (PSO) algorithm are used to resolve it, and then the results are compared. Sensitivity analysis is done in order to investigate the impact of key parameters on decision-making. Finally, conclusions along with some managerial insights are given. For the entire collection see [Zbl 1452.90002]. Economic production quantity (EPQ) inventory model for a deteriorating item with a two-level trade credit policy and allowable shortages. https://www.zbmath.org/1456.90017 2021-04-16T16:22:00+00:00 "Shaikh, Ali Akbar" https://www.zbmath.org/authors/?q=ai:shaikh.ali-akbar "Cárdenas-Barrón, Leopoldo Eduardo" https://www.zbmath.org/authors/?q=ai:cardenas-barron.leopoldo-eduardo "Tiwari, Sunil" https://www.zbmath.org/authors/?q=ai:tiwari.sunil Summary: This research work derives an economic production quantity (EPQ) model, and in order to make it a bit close to reality, the stockout is allowed, and this is completely backordered. In addition to this feature, it is incorporated a two-level credit scheme when both supplier and retailer are giving a delay in payment to their respective customers with the aim of enhancing the sales. The inventory model is modeled as a constrained nonlinear optimization problem, and this is resolved by the generalized reduced gradient method (GRG). Moreover, to exemplify and certify the inventory model, five instances are given and solved. Finally, a sensitivity analysis is made for studying the influence of variations of input parameters, modifying one parameter and maintaining the others at their initial input values. For the entire collection see [Zbl 1452.90002]. Approximability of the dispersed $$\vec{p}$$-neighbor $$k$$-supplier problem. https://www.zbmath.org/1456.90058 2021-04-16T16:22:00+00:00 "van Ee, Martijn" https://www.zbmath.org/authors/?q=ai:van-ee.martijn Summary: We consider the dispersed $$\overrightarrow{p}$$-neighbor $$k$$-supplier problem. In the classical $$k$$-supplier problem, we have to select $$k$$ suppliers in a metric space such that the maximum distance between a customer and its closest supplier is minimized. Here, we generalize this problem to the case where each customer possibly needs service from more than one supplier. Moreover, the selected suppliers should not be too close to each other, i.e., they need to be dispersed. For the classical $$k$$-supplier problem, and its special case the $$k$$-center problem, there is a 3- and a 2-approximation respectively. We show that these guarantees can also be given in the case when customers need service from multiple suppliers, without imposing dispersion constraints. If we generalize the problem to the dispersed case, without imposing neighboring constraints, we get inapproximability results depending on the measure of dispersion. We also show (almost) matching upper bounds. Finally, we show that adding both the neighbor requirement and the dispersion requirement leads to an inapproximable problem. The multi-spreader crane scheduling problem: partitions and supersequences. https://www.zbmath.org/1456.90068 2021-04-16T16:22:00+00:00 "Cheng, Christine T." https://www.zbmath.org/authors/?q=ai:cheng.christine-t "Petering, Matthew E. H." https://www.zbmath.org/authors/?q=ai:petering.matthew-e-h "Wu, Yong" https://www.zbmath.org/authors/?q=ai:wu.yong Summary: In the Multi-Spreader Crane Scheduling Problem (MSCSP), containers with identical dimensions but variable weights are arranged along a grid. A multi-spreader crane is used to lift all the containers. The crane has $$m > 1$$ modes. When it is in the $$p$$ th mode, the crane can remove $$p$$ adjacent containers along the same row at the same time as long as the total weight of the containers does not exceed the loading capacity $$\kappa_p$$. Such a lift takes $$h_p$$ minutes. It also takes $$c_{p , q}$$ minutes for the crane to switch from mode $$p$$ to $$q$$ when $$p \neq q$$. The goal is to find a crane lift sequence so that the total time it takes to lift all the containers is minimized. This paper investigates the computational complexity of MSCSP. First, we establish a connection between greedy crane lift sequences and supersequences. We then prove that MSCSP is NP-hard when the crane has three or more modes by a reduction from a version of the Shortest Common Supersequence problem. Lastly, we investigate two problems that arise naturally when heuristics are used to solve MSCSP. We show that one can be solved using dynamic programming while the other remains computationally hard. We also provide an approximation algorithm that behaves nicely when the changeover times are not much larger than the lifting times of the crane. A two-stage DEA model with partial impacts between inputs and outputs: application in refinery industries. https://www.zbmath.org/1456.90103 2021-04-16T16:22:00+00:00 "Nemati, Mohammad" https://www.zbmath.org/authors/?q=ai:nemati.mohammad "Kazemi Matin, Reza" https://www.zbmath.org/authors/?q=ai:kazemi-matin.reza "Toloo, Mehdi" https://www.zbmath.org/authors/?q=ai:toloo.mehdi Summary: Conventional data envelopment analysis (DEA) methods are useful for estimating the performance measure of decision making units (DMUs) that each DMU uses multiple inputs to produce multiple outputs without considering any partial impacts between inputs and outputs. Nevertheless, there are some real-world situations where DMUs may possess several production lines with a two-stage network structure that each production line use inputs according to their needs. The current paper extends the recent work by \textit{J. Ma} [A two-stage DEA model considering shared inputs and free intermediate measures'', Expert Syst. Appl. 42, No. 9, 4339--4347 (2015; \url{doi:10.1016/j.eswa.2015.01.040})] to consider partial impact between inputs and outputs for two-stage network production systems. Toward this end, we consider several input-output bundles in each stage for production lines. We formulate a couple of new mathematical programming models in the DEA framework with the aim of considering partial impact between inputs and outputs for calculating aggregate, overall, and subunit efficiencies along with resource usage by production lines for a two-stage production system Finally, an application in refinery industries is provided as an example to illustrate the potential application of the proposed method. Generalized $$k$$-core pruning process on directed networks. https://www.zbmath.org/1456.05163 2021-04-16T16:22:00+00:00 "Zhao, Jin-Hua" https://www.zbmath.org/authors/?q=ai:zhao.jinhua Relevance and importance preferential attachment. https://www.zbmath.org/1456.68131 2021-04-16T16:22:00+00:00 "Lim, Chjan" https://www.zbmath.org/authors/?q=ai:lim.chjan-c "Zhang, Weituo" https://www.zbmath.org/authors/?q=ai:zhang.weituo Summary: Relevance and importance are the main factors when humans build network connections. We propose an evolutionary network model based on preferential attachment (PA) considering these factors. We analyze and compute several important features of the network class generated by this algorithm, including scale-free degree distribution, high clustering coefficient, small-world property and core-periphery structure. We then compare this model with other network models and empirical data such as intercity road transportation and air traffic networks. On a multiserver queueing system with customers' impatience until the end of service under single and multiple-vacation policies. https://www.zbmath.org/1456.60243 2021-04-16T16:22:00+00:00 "Kadi, Mokhtar" https://www.zbmath.org/authors/?q=ai:kadi.mokhtar "Bouchentouf, Amina Angelika" https://www.zbmath.org/authors/?q=ai:bouchentouf.amina-angelika "Yahiaoui, Lahcene" https://www.zbmath.org/authors/?q=ai:yahiaoui.lahcene Summary: This paper deals with a multiserver queueing system with Bernoulli feedback and impatient customers (balking and reneging) under synchronous multiple and single vacation policies. Reneged customers may be retained in the system. Using probability generating functions (PGFs) technique, we formally obtain the steady-state solution of the proposed queueing system. Further, important performance measures and cost model are derived. Finally, numerical examples are presented. Closed loop supply chain mathematical modeling considering lean agile resilient and green strategies. https://www.zbmath.org/1456.90012 2021-04-16T16:22:00+00:00 "Mohammadzadeh, Masoud" https://www.zbmath.org/authors/?q=ai:mohammadzadeh.masoud "Sobhanallahi, Mohammadali" https://www.zbmath.org/authors/?q=ai:sobhanallahi.mohammadali "Khamseh, Alireza Arshadi" https://www.zbmath.org/authors/?q=ai:arshadi-khamseh.alireza Summary: The supply chain management is planning, implementation and effective control of supply chain operations considered as a key factor for the competitiveness of the organizations. To make these targets, four management strategies of lean, agile, resilient and green have been separately proposed. Recently, studies have been performed with a consideration of these four strategies simultaneously named LARG (Lean, Agile, Resilient and Green). However, due to the novelty of this subject, the mathematical modeling of SCND (Supply Chain Network Design) has not been addressed in LARG strategy. SCND is one of the most essential parts of supply chain management that strategic decisions of it have heavily effects in both overall and partial applicability of the supply chain. The goal of this paper is to design a closed loop supply chain network considering LARG strategy using multi-objective modeling with uncertain demand. The objective functions are total profit, customer satisfaction and total pollution. The model is formulated to determine which facility sites should be selected (strategic decisions), and find out the optimal number of parts and products in the network (tactical decisions). Finally, a real industrial case study is provided to illustrate the performance and applicability of the LARG strategy in SCND in practice. Motif formation and industry specific topologies in the Japanese business firm network. https://www.zbmath.org/1456.91063 2021-04-16T16:22:00+00:00 "Maluck, Julian" https://www.zbmath.org/authors/?q=ai:maluck.julian "Donner, Reik V." https://www.zbmath.org/authors/?q=ai:donner.reik-v "Takayasu, Hideki" https://www.zbmath.org/authors/?q=ai:takayasu.hideki "Takayasu, Misako" https://www.zbmath.org/authors/?q=ai:takayasu.misako Study on the collision dynamics and the transmission pattern between pedestrians along the queue. https://www.zbmath.org/1456.90051 2021-04-16T16:22:00+00:00 "Wang, Chongyang" https://www.zbmath.org/authors/?q=ai:wang.chongyang.1 "Weng, Wenguo" https://www.zbmath.org/authors/?q=ai:weng.wenguo On the formation of structure in growing networks. https://www.zbmath.org/1456.90035 2021-04-16T16:22:00+00:00 "Moriano, P." https://www.zbmath.org/authors/?q=ai:moriano.p "Finke, J." https://www.zbmath.org/authors/?q=ai:finke.juergen|finke.jorge Understanding the single-file dynamics of bicycle traffic from the perspective of car-following models. https://www.zbmath.org/1456.90052 2021-04-16T16:22:00+00:00 "Xue, Shuqi" https://www.zbmath.org/authors/?q=ai:xue.shuqi "Feliciani, Claudio" https://www.zbmath.org/authors/?q=ai:feliciani.claudio "Shi, Xiaomeng" https://www.zbmath.org/authors/?q=ai:shi.xiaomeng "Jiang, Rui" https://www.zbmath.org/authors/?q=ai:jiang.rui Locating a discrete subtree of minimum variance on trees: new strategies to tackle a very hard problem. https://www.zbmath.org/1456.90100 2021-04-16T16:22:00+00:00 "Puerto, Justo" https://www.zbmath.org/authors/?q=ai:puerto.justo "Ricca, Federica" https://www.zbmath.org/authors/?q=ai:ricca.federica "Scozzari, Andrea" https://www.zbmath.org/authors/?q=ai:scozzari.andrea Summary: In this paper we study the problem of finding a discrete subtree of minimum variance with bounded size of a given tree. We show that the problem is NP-hard on very simple trees and it remains difficult even if we consider the Mean Absolute Deviation criterion on star graphs. Referring to the variance criterion, we first propose a reformulation of the problem as an Integer Quadratic Program that, however, does not have particular structural properties that may help in finding good lower bounds on the optimal value of the problem. Then, basing on recent results on conic optimization, we investigate alternative reformulations of the problem in order to obtain some lower bounds. In particular, we exploit a continuous linear, conic, reformulation of the problem and show that this is, in fact, an exact linear reformulation of the Integer Quadratic Program. Alternatively, by referring to the upper envelope approach, we show how to obtain a lower bound for the optimal objective function value of our discrete tree-shaped facility location problem in pseudo-polynomial time. Optimal weighted coefficient for heterogeneous epidemic spreading networks. https://www.zbmath.org/1456.92130 2021-04-16T16:22:00+00:00 "An, Xuming" https://www.zbmath.org/authors/?q=ai:an.xuming "Ding, Li" https://www.zbmath.org/authors/?q=ai:ding.li "Hu, Ping" https://www.zbmath.org/authors/?q=ai:hu.ping "Yu, Yi" https://www.zbmath.org/authors/?q=ai:yu.yi Dynamic models of environmental data envelopment analysis with stock and flow variables. https://www.zbmath.org/1456.90091 2021-04-16T16:22:00+00:00 "Ratner, S. V." https://www.zbmath.org/authors/?q=ai:ratner.s-v Summary: The paper devoted to the elaboration of methodological approach to the solution of dynamic problems of Environmental Data Envelopment Analysis for production facilities, whose activities are characterized by a set of variables of two different types -- stock variables and flow variables. The limitations that are additionally imposed on the Production Possibility Set are studied. A task is set for assessing the comparative effectiveness of regional systems of environmental management that operate at a certain time interval. A computational example is given for assessing the comparative effectiveness of environmental management systems in the regions of the Central Federal District in the period from 2010 to 2014. The possibilities of using the developed method in practice are discussed. Piecewise deterministic Markov processes driven by scalar conservation laws. https://www.zbmath.org/1456.60187 2021-04-16T16:22:00+00:00 "Knapp, Stephan" https://www.zbmath.org/authors/?q=ai:knapp.stephan Summary: We investigate piecewise deterministic Markov processes (PDMP), where the deterministic dynamics follows a scalar conservation law and random jumps in the system are characterized by changes in the flux function. We show under which assumptions we can guarantee the existence of a PDMP and conclude bounded variation estimates for sample paths. Finally, we apply this dynamics to a production and traffic model and use this framework to incorporate the well-known scattering of flux functions observed in data sets. For the entire collection see [Zbl 1453.35003]. Hierarchical clustering with optimal transport. https://www.zbmath.org/1456.62117 2021-04-16T16:22:00+00:00 "Chakraborty, Saptarshi" https://www.zbmath.org/authors/?q=ai:chakraborty.saptarshi "Paul, Debolina" https://www.zbmath.org/authors/?q=ai:paul.debolina "Das, Swagatam" https://www.zbmath.org/authors/?q=ai:das.swagatam Summary: Optimal Transport (OT) distances result in a powerful technique to compare the probability distributions. Defining a similarity measure between clusters has been an open problem in Statistics. This paper introduces a hierarchical clustering algorithm using the OT based distance measures and analyzes the performance of the proposed algorithm on standard datasets with respect to the existing and popular hierarchical clustering methods. Grad's moment method for Vehicular traffic. https://www.zbmath.org/1456.82822 2021-04-16T16:22:00+00:00 "Laibida, A. jun." https://www.zbmath.org/authors/?q=ai:laibida.a-jun "Marques, W. jun." https://www.zbmath.org/authors/?q=ai:marques.wilson-jun Directional distance functions in DEA with optimal endogenous directions. https://www.zbmath.org/1456.90090 2021-04-16T16:22:00+00:00 "Petersen, Niels Christian" https://www.zbmath.org/authors/?q=ai:petersen.niels-christian Summary: This paper is concerned with optimal directions in the directional distance function in data envelopment analysis. It is shown that the vector pointing in the direction that minimizes the Euclidean distance between the input-output vector $$(X_o, Y_o)$$ and the efficient frontier, the input isoquant reflecting output $$Y_o$$, or the output isoquant reflecting input $$X_o$$ is optimal, because the corresponding vector of virtual multipliers defines the relative prices that maximize profit, cost, or revenue efficiency. The associated efficiency indicator is a value measure of technical efficiency in difference form with the Euclidean distance between $$(X_o, Y_o)$$ and the efficient frontier, the $$Y_o$$ input isoquant, or the $$X_o$$ output isoquant as an equivalent directional distance quantity indicator. A linear combinatorial optimization program for computing the relevant value indicators of technical efficiency in multiplier space or the equivalent quantity indicators in terms of the relevant Euclidean distances is developed. A nonlinear and nonconvex optimization model for an estimation of the relevant value indicator of efficiency in multiplier space is also developed. Preliminary computational results are reported. A stochastic optimization model for oil refining industry planning. https://www.zbmath.org/1456.90109 2021-04-16T16:22:00+00:00 "Ba-Shammakh, M." https://www.zbmath.org/authors/?q=ai:ba-shammakh.m Summary: Stochastic optimization modeling approach is a useful tool to address different scenarios with different probabilities. The approach can be applied into different chemical related processes such as refining or petrochemical related industries. The petroleum refining industry is sharing a major role in the worldwide energy and the global market. Refining industry faces serious changes in the products daily demand, properties and the crude oil cost which result in difficulty in taking immediate decisions. Therefore, the use of stochastic optimization models becomes more effective and useful for decision making purpose. In this research, a general stochastic optimization model for the refinery operational planning was developed to help decision makers in making appropriate immediate decisions for higher profitability. This is achieved by knowing the best option for each scenario if prices go up or down as an example. The stochastic model gives the highest profit when the demand and final products price increases (scenario 1). On a retrial production inventory system with vacation and multiple servers. https://www.zbmath.org/1456.60242 2021-04-16T16:22:00+00:00 "Jose, K. P." https://www.zbmath.org/authors/?q=ai:jose.k-p "Beena, P." https://www.zbmath.org/authors/?q=ai:beena.p Summary: In this paper, the model of a production inventory system with heterogeneous servers, the vacation of one of the servers (vacationing server), and retrial customers is considered. The customers reach the system each demanding exactly one unit of the item, according to a Poisson process. Service times and lead time are independent and follow exponential distributions. A single unit of the item is produced at a time according to (s, S) policy. It is assumed that when the inventory level reaches zero or when the orbit is empty or both, one of the servers (server 2) takes multiple, exponentially distributed vacation time. At the end of the vacation, that server immediately takes another vacation, if he/she finds empty stock or empty orbit or both. During the stock out period or server busy period or vacation period, the demands that arrive enter into the orbit of infinite size. If a customer finds both the servers busy or server 1 busy and server 2 in vacation or inventory level is zero, in accordance with Bernoulli trials may wait in the orbit or leave forever. When either the customer in the orbit cannot make an attempt due to the busy servers or inventory level zero, he/she under Bernoulli trials may come back to the orbit or leave the orbit. The rate of retrial customers from orbit is linear. The production process is switched on when the inventory level reaches to s, and similarly when the level of inventory reaches back to S the production process is switched off. The production process releases items that have inter arrival times that are exponentially distributed. Ergodicity condition is obtained and matrix analytic method is used to calculate the steady-state probabilities of the constructed 4D Markov chain. Minimum expected total cost per unit time and many significant system performance measures are obtained. Sensitivity analysis is relevant to check various performance measures that is highly applicable in the realistic situation and it also provides managerial insights. A Geo/Geo/1 inventory priority queue with self induced interruption. https://www.zbmath.org/1456.90007 2021-04-16T16:22:00+00:00 "Anilkumar, M. P." https://www.zbmath.org/authors/?q=ai:anilkumar.m-p "Jose, K. P." https://www.zbmath.org/authors/?q=ai:jose.k-p Summary: This paper considers discrete time $$(s, S)$$ inventory Geo/Geo/1 priority queue formed by the customers' induced interruption during service. An arriving customer enters into a high priority queue of infinite capacity. During his/her service, the service may be interrupted due to own reasons with some probability. The interrupted customer is moved to a lower priority queue of infinite capacity. An item in the inventory is supplied whenever a customer leaves from high priority queue after interrupting/completing the service. The customer in the lower priority queue is served according to preemptive priority discipline. Inter-arrival time, service time and lead time are considered to be geometrically distributed. We use the matrix analytic method to analyse the model. The necessary and sufficient condition for the stability of the system is obtained. The marginal distributions of both higher and lower priority queue lengths are studied. Numerical experiments are incorporated to draw special attention to the importance of the model. Link prediction in scale-free networks using a partial observation. https://www.zbmath.org/1456.90037 2021-04-16T16:22:00+00:00 "Yu, Xuecheng" https://www.zbmath.org/authors/?q=ai:yu.xuecheng "Li, Rui" https://www.zbmath.org/authors/?q=ai:li.rui.4|li.rui.3|li.rui.1|li.rui.2|li.rui "Chu, Tianguang" https://www.zbmath.org/authors/?q=ai:chu.tianguang Two-way communication orbit queues with server vacation. https://www.zbmath.org/1456.60239 2021-04-16T16:22:00+00:00 "Dey, Sweta" https://www.zbmath.org/authors/?q=ai:dey.sweta "Deepak, T. G." https://www.zbmath.org/authors/?q=ai:deepak.t-g Summary: We consider a single server retrial model with two streams of calls namely, incoming and outgoing calls. Each stream consists of multiple classes of calls. As part of the internal work load, presence of outgoing calls are always assumed in the system. Arrival of incoming calls obey the Poisson law. Upon seeing a busy server at its arrival epoch, an incoming call will be directed to an orbit according to the class it belongs to and tries to get an idle sever in gap of exponential amount of time with class dependent mean. Similar kind of attempt is being made by the outgoing calls also to reach an idle server. Once the sever becomes idle, if neither an incoming nor an outgoing call turns up for an exponential amount of time, the server goes for vacation and the vacation time is assumed to be exponential. Within each stream, service times of multiple classes of calls are assumed to be independent exponential with class dependent means. Matrix Analytic Method and regenerative approach are used to derive the explicit form of the steady state probabilities. Many performance measures are computed to analyse the system performance. Reliability analysis of multi-state two-dimensional system by universal generating function. https://www.zbmath.org/1456.60236 2021-04-16T16:22:00+00:00 "Meenakshi, K." https://www.zbmath.org/authors/?q=ai:meenakshi.k-n "Singh, S. B." https://www.zbmath.org/authors/?q=ai:singh.suresh-b|singh.saket-bihari|singh.suraj-bhan Summary: In this paper, two dimensional multi-state non-repairable systems having $$m$$ rows and $$n$$ columns have been studied. Markov stochastic process has been applied for obtaining probabilities of the components. Reliability metrics such as reliability, mean time to failure and sensitivity analysis of the target system with the application of universal generating function are evaluated. Finally, the developed model is demonstrated with the help of a numerical example. For the entire collection see [Zbl 1446.65004]. Coexistence of opposite opinions in a network with communities. https://www.zbmath.org/1456.91098 2021-04-16T16:22:00+00:00 "Lambiotte, R." https://www.zbmath.org/authors/?q=ai:lambiotte.renaud "Ausloos, M." https://www.zbmath.org/authors/?q=ai:ausloos.marcel-r Transient analysis of a Markov queueing model with feedback, discouragement and disaster. https://www.zbmath.org/1456.60241 2021-04-16T16:22:00+00:00 "Jain, Madhu" https://www.zbmath.org/authors/?q=ai:jain.madhu "Singh, Mayank" https://www.zbmath.org/authors/?q=ai:singh.mayank Summary: The transient model for a Markovian feedback queue with system disaster and customer impatient has been investigated. After service completion, dissatisfied customers can feedback to the system to get another service. During the service, the system may suffer disaster failure and consequently lose all the customers present in the system. After the occurrence of a disaster, the system immediately goes under the repair process. During the repair, the newly arriving customers may get discouraged and balk without joining the queue. Upon arrival in the down state of the system, the arriving customers activate their individual timer. A customer waiting in the queue departs and never comes back if the timer run out before the system gets repaired. The time-dependent system size distribution is formulated analytically by applying the techniques of probability generating function along with continued fractions. The computational results are presented in graphical and tabular form to examine the variation of system descriptors on various performance indices. Optimal scheduling of passenger air transportation in regional network. https://www.zbmath.org/1456.90024 2021-04-16T16:22:00+00:00 "Bogdanov, I. P." https://www.zbmath.org/authors/?q=ai:bogdanov.i-p Summary: This paper deals with the problem of air passenger transportation optimal planning. The aim is to minimize renting and operational costs, taking into account heterogeneous fleet, feasibility of multiple visits to the same location, restrictions on the set of available airways, etc. Two multi-index formalizations -- as a binary linear programming problem and as a mixed-integer linear programming problem (depending on the consideration of time windows for takeoffs and landings) -- are presented for the regarded task. In the future constructed analytical model can become the basis for the development of the globally optimal schedules approximation algorithms. Traffic model by braking capability and response time. https://www.zbmath.org/1456.90047 2021-04-16T16:22:00+00:00 "Lee, Hyun Keun" https://www.zbmath.org/authors/?q=ai:lee.hyun-keun "Kim, Jeenu" https://www.zbmath.org/authors/?q=ai:kim.jeenu "Kim, Youngho" https://www.zbmath.org/authors/?q=ai:kim.youngho|kim.youngho.1 "Lee, Choong-Ki" https://www.zbmath.org/authors/?q=ai:lee.choong-ki Bounds on optimal transport maps onto log-concave measures. https://www.zbmath.org/1456.49036 2021-04-16T16:22:00+00:00 "Colombo, Maria" https://www.zbmath.org/authors/?q=ai:colombo.maria "Fathi, Max" https://www.zbmath.org/authors/?q=ai:fathi.max In this paper the authors provide quantitative bounds on the regularity of transport maps sending a standard Gaussian distribution onto a $$\log$$-concave probability measures on $$\mathbb{R}^d$$. Caffarelli contraction theorem states that, when the target measure $$\mu$$ is uniformly $$\log$$-concave, i.e. $$\mu=e^{-V} \mathrm{d} x$$ with $$D^2V \ge \alpha$$, the optimal transport map is $$\alpha^{-1/2}$$-Lipschitz continuous. It is thus evident that such regularity degenerates if $$\mu$$ is only $$\log$$-concave, i.e. $$\mu=e^{-V} \mathrm{d} x$$ with $$D^2V \ge 0$$ only. The first main result deals with this case: the authors prove the quadratic growth at infinity, i.e. Theorem. Let $$\mu$$ be a centered, isotropic, $$\log$$-concave probability measure on $$\mathbb{R}^d$$. Then there exists a universal numerical constant $$C$$ such that the Brenier map sending the standard Gaussiandistribution onto $$\mu$$ satisfies $|T(x)| \le C(d+|x|^2).$ If instead we assume that $$\mu$$ is centered and satisfies a Gaussian concentration property with constant $$\beta$$, then $|T(x)| \le 12\beta^{-1/2}(17d+|x|^2)^{1/2}.$ As the authors noted, the left hand side behaves like $$d^{1/2}$$, while the right hand side scales like $$d$$, thus the above estimates are a bit off-average. The second result proves some a priori regularity estimates on derivatives of $$T$$. The strategy is to revisit Kolesnikov's proof of Sobolev estimates in the uniformly $$\log$$-concave case, to allow for non-uniform lower bounds on the Hessian of the potential. More precisely, the authors obtain the following bound: Theorem. Let $$T = \nabla\varphi$$ be the Brenier map sending the standard Gaussian measure onto $$\mu = e^{-V} \mathrm{d} x$$. Assume that $$\mu$$ is centered, isotropic, and that for all $$x\in \mathbb{R}^d$$ $c_1 Id \ge D^2 V(x) \ge \frac{c_2}{d+|x|}Id$ for some $$c_1,c_2>0$$. Then $\Big\| \frac{\partial_{ee}^2\varphi}{\sqrt{d+|x|^2}} \Big\|_{p+2,\gamma} \le \frac{C}{c_2} \Big(1+p\frac{\sqrt{c_1}}{4\sqrt{d}}\Big).$ That is, the authors obtain a bound of the form $\partial_{ee}^2\varphi \le Cr \sqrt{d+|x|^2}$ on the complement of a set with very small Gaussian measure. Finally, in the spirit of the Caffarelli contraction theorem, the authors obtain a bound on the growth of the eigenvalues in $$L^\infty$$: Theorem. Let $$T = \nabla\varphi$$ be the Brenier map sending the standard Gaussian measure onto $$\mu = e^{-V} \mathrm{d} x$$. Assume that $$\mu$$ is centered, isotropic, and that for all $$x\in \mathbb{R}^d$$ $c_1 Id \ge D^2 V(x) \ge \frac{c_2}{d+|x|}Id$ for some $$c_1,c_2>0$$. Then $\|\nabla T(x)\|_{op} \le \max\Big(C\frac{c_1^2}{c_2^2},1\Big)(d+|x|^2)^2.$ If moreover $c_3\ge |\nabla V(x)|,$ then $\|\nabla T(x)\|_{op} \le \max\Big(C\frac{c_1^2}{c_2^2},1\Big)(d^{4/3}+|x|^2).$ Reviewer: Xin Yang Lu (Thunder Bay) An aspect of bilevel fixed charge fractional transportation problem. https://www.zbmath.org/1456.90030 2021-04-16T16:22:00+00:00 "Kaushal, Bindu" https://www.zbmath.org/authors/?q=ai:kaushal.bindu "Arora, Ritu" https://www.zbmath.org/authors/?q=ai:arora.ritu "Arora, Shalini" https://www.zbmath.org/authors/?q=ai:arora.shalini Summary: Bilevel Programming Problem (BLPP) is a hierarchical optimization problem. Here, the constraint set of the upper level problem, called the leader, is ascertained by the lower level problem, called the follower. In this paper, a BLPP is considered where the leader's problem is a fractional transportation problem and the follower's problem is a fixed charge transportation problem. Hence, a bilevel fixed charge fractional transportation problem (BLFCFTP) is formulated. The problem is also explained through graphical representation. The problem comes from a food chain industry which is utilizing its used vegetable cooking oil for the production of biodiesel. The mathematical model of the problem is presented and is also explained through graphical representation. The problem pertains to a food chain industry wherein the used vegetable cooking oil is utilized for the production of biodiesel. Another example quotes Indore city where waste is converted into bio-CNG which is used to run public transport. The managerial importance of the work is that it will promote a sustainable and environment friendly practice. This will result in reduction of waste and check environmental pollution. An algorithm to solve BLFCFTP is developed. The examples explaining the algorithm are exhibited by a viable situation. These examples are subsequently deciphered in MATLAB. System reliability assessment through $$p$$ minimal paths in stochastic case with backup-routing. https://www.zbmath.org/1456.90062 2021-04-16T16:22:00+00:00 "Lin, Yi-Kuei" https://www.zbmath.org/authors/?q=ai:lin.yi-kuei Summary: For a stochastic-flow network in which each arc has several possible capacities, we assess the probability that a given amount of data are sent through $$p$$ $$(p\geq 2)$$ minimal paths simultaneously subject to time threshold. Such a probability is named the system reliability. Without knowing all minimal paths, a solution procedure is first proposed to calculate it. Furthermore, the backup-routing is established in advance to declare the first and the second priority $$p$$ minimal paths in order to enhance the system reliability. Subsequently, the system reliability according to the backup-routing can be computed easily. TOPSIS approach to multi-objective emergency service facility location selection problem under $$q$$-rung orthopair fuzzy information. https://www.zbmath.org/1456.90093 2021-04-16T16:22:00+00:00 "Sirbiladze, Gia" https://www.zbmath.org/authors/?q=ai:sirbiladze.gia "Sikharulidze, Anna" https://www.zbmath.org/authors/?q=ai:sikharulidze.anna "Matsaberidze, Bidzina" https://www.zbmath.org/authors/?q=ai:matsaberidze.bidzina "Khutsishvili, Irina" https://www.zbmath.org/authors/?q=ai:khutsishvili.irina "Ghvaberidze, Bezhan" https://www.zbmath.org/authors/?q=ai:ghvaberidze.bezhan Summary: A new model based onq-rung orthopair fuzzy sets ($$q$$-ROFS) has been presented to manage the uncertainty in real-world multi-criteria decision-making problems. $$q$$-ROFS has much stronger ability than Pythagorean fuzzy set (PFS) or intuitionistic fuzzy set (IFS) to model such uncertainty. A $$q$$-rung orthopair fuzzy TOPSIS approach for formation and representing experts knowledge on the parameters of emergency service facility location planning is developed. In this approach, we propose a score function based on the comparison method to identify the $$q$$-rung orthopair fuzzy positive ideal solution and the $$q$$-rung orthopair fuzzy negative ideal solution. Based on the constructed fuzzy TOPSIS aggregation, a new objective function is formulated. The constructed criterion maximizes service centers' selection index. This criterion together with the second criterion -- minimization of a number of selected centers creates the multi-objective facility location set covering problem. The approach is illustrated by the simulation example of emergency service facility location planning for a city in Georgia. More exactly, the example looks into the problem of planning fire stations locations to serve emergency situations in specific demand points critical infrastructure objects. Analyzing the models of systems with heterogeneous servers. https://www.zbmath.org/1456.60245 2021-04-16T16:22:00+00:00 "Melikov, A. Z." https://www.zbmath.org/authors/?q=ai:melikov.agassi-z "Ponomarenko, L. A." https://www.zbmath.org/authors/?q=ai:ponomarenko.leonid-a "Mekhbaliyeva, E. V." https://www.zbmath.org/authors/?q=ai:mekhbalyeva.e-v Summary: The mathematical model of a queueing system with heterogeneous servers, without queues, and with two types of requests is investigated. High-priority requests are processed in fast servers while low-priority calls are processed in slow servers. If all servers in some group are busy, then reassigning of requests to another group is allowed. Reassigning is based on random schemes and reassignment probability depends on the number of busy servers in appropriate group. Exact and approximate methods are developed for the analysis of characteristics of the system. Explicit approximate formulas to calculate the approximate values of characteristics are proposed. Random degree -- degree correlated networks. https://www.zbmath.org/1456.05159 2021-04-16T16:22:00+00:00 "Ramos, Marlon" https://www.zbmath.org/authors/?q=ai:ramos.marlon "Anteneodo, Celia" https://www.zbmath.org/authors/?q=ai:anteneodo.celia Measurement of network complexity and capability in command and control system. https://www.zbmath.org/1456.90036 2021-04-16T16:22:00+00:00 "Song, Xiao" https://www.zbmath.org/authors/?q=ai:song.xiao "Zhang, Shaoyun" https://www.zbmath.org/authors/?q=ai:zhang.shaoyun "Shi, Xuecheng" https://www.zbmath.org/authors/?q=ai:shi.xuecheng Summary: A concept of complexity of the Command and Control (C2) information system is introduced and an innovative approach of measuring network complexity is proposed compared with traditional network complexity computation methods. Complexity measurements, including connectivity, collaboration and redundancy, are proposed and computed. Then the complexity-based capability is discussed and studied. Finally, two case studies of an anti-aircraft defence C2 network and partial tank division network are carried out to illustrate the computation processes of the proposed network complexity and capability. Zero-point maximum allocation method for solving intuitionistic fuzzy transportation problem. https://www.zbmath.org/1456.90029 2021-04-16T16:22:00+00:00 "Kamini" https://www.zbmath.org/authors/?q=ai:kamini. "Sharma, M. K." https://www.zbmath.org/authors/?q=ai:sharma.mukesh-kumar|sharma.mahesh-k|sharma.mukesh-kr|sharma.manoj-kumar Summary: Transportation problems (TP) can be solved by various methods when the parameters are in crisp nature. But when the parameters are vague in nature or have imperfect knowledge or have partial information then we have to use the fuzzy optimization. Sujatha et al. [Solving fuzzy transportation problem (FTP) using zero point maximum allocation method] proposed the procedure for fuzzy transportation problem (FTP) with parameters are in the form of trapezoidal fuzzy numbers. But fuzzy logic is not adequate to describe all the characteristics of the system. To describe all the properties of the system, we have to consider the membership as well as the non-membership including the hesitation part. In the present research paper, we have proposed the solution of the transportation problem (TP) in the form of intuitionistic fuzzy logic by using zero point maximum allocation method. By using this technique, we can observe that the method applied to solve the fuzzy transportation problem (FTP) gives the most suitable optimal solution. A numerical example has also been given to elaborate this technique to solve the intuitionistic fuzzy transportation problem (IFTP). Competitive allocation of resources on a network: an agent-based model of air companies competing for the best routes. https://www.zbmath.org/1456.90044 2021-04-16T16:22:00+00:00 "Gurtner, Gérald" https://www.zbmath.org/authors/?q=ai:gurtner.gerald "Valori, Luca" https://www.zbmath.org/authors/?q=ai:valori.luca "Lillo, Fabrizio" https://www.zbmath.org/authors/?q=ai:lillo.fabrizio A slow-to-start traffic model related to a M/M/1 queue. https://www.zbmath.org/1456.90054 2021-04-16T16:22:00+00:00 "Cáceres, Fredy Castellares" https://www.zbmath.org/authors/?q=ai:caceres.fredy-castellares "Ferrari, Pablo A." https://www.zbmath.org/authors/?q=ai:ferrari.pablo-augusto "Pechersky, Eugene" https://www.zbmath.org/authors/?q=ai:pechersky.eugene-a A potential field approach to the modeling of route choice in Pedestrian evacuation. https://www.zbmath.org/1456.90043 2021-04-16T16:22:00+00:00 "Guo, Ren-Yong" https://www.zbmath.org/authors/?q=ai:guo.renyong "Huang, Hai-Jun" https://www.zbmath.org/authors/?q=ai:huang.haijun "Wong, S. C." https://www.zbmath.org/authors/?q=ai:wong.sze-chun|wong.soo-chen|wong.shwin-chung|wong.siu-chung On the reproducibility of spatiotemporal traffic dynamics with microscopic traffic models. https://www.zbmath.org/1456.90046 2021-04-16T16:22:00+00:00 "Knorr, Florian" https://www.zbmath.org/authors/?q=ai:knorr.florian "Schreckenberg, Michael" https://www.zbmath.org/authors/?q=ai:schreckenberg.michael Some more average distance results. https://www.zbmath.org/1456.90026 2021-04-16T16:22:00+00:00 "Hale, Trevor S." https://www.zbmath.org/authors/?q=ai:hale.trevor-s "Lutz, Heather S." https://www.zbmath.org/authors/?q=ai:lutz.heather-s "Huq, Faizul" https://www.zbmath.org/authors/?q=ai:huq.faizul Summary: The purpose of this study is to present a taxonomy of expected distance functions (EDFs). An EDF is the expected (where expected is used in the strict probabilistic sense) distance formula for a given metric between two algebraically defined regions (e.g., the expected Euclidean distance between a semi-circle of radius $$r$$ centred at $$(x_{1}, y_{1})$$ that has a known bivariate probability density function in $$r$$ and $$\theta$$ and a line segment beginning at $$(x_{2}, y_{2})$$ and ending at $$(x_{3}, y_{3})$$ that has a known probability density function along its length). A modest library of EDFs for various metrics (rectilinear, Euclidean, Tchebychev, etc.) between pairs of common geometric shapes (e.g., lines, semi-circles, rectangles, etc.) is presented. The taxonomy of EDFs contained herein is by no means meant to be an exhaustive list. Indeed, it is limited in scope to those considered to be of practical importance to geographic information, transportation science, and mathematical modelling professionals. A new three-step cellular automaton model considering a realistic driving decision. https://www.zbmath.org/1456.90050 2021-04-16T16:22:00+00:00 "Shang, Hua-Yan" https://www.zbmath.org/authors/?q=ai:shang.hua-yan "Peng, Yu" https://www.zbmath.org/authors/?q=ai:peng.yu Analyzing data through probabilistic modeling in statistics. https://www.zbmath.org/1456.62004 2021-04-16T16:22:00+00:00 "Jakóbczak, Dariusz Jacek (ed.)" https://www.zbmath.org/authors/?q=ai:jakobczak.dariusz-jacek Publisher's description: Probabilistic modeling represents a subject arising in many branches of mathematics, economics, and computer science. Such modeling connects pure mathematics with applied sciences. Similarly, data analyzing and statistics are situated on the border between pure mathematics and applied sciences. Therefore, when probabilistic modeling meets statistics, it is a very interesting occasion that has gained much research recently. With the increase of these technologies in life and work, it has become somewhat essential in the workplace to have planning, timetabling, scheduling, decision making, optimization, simulation, data analysis, and risk analysis and process modeling. However, there are still many difficulties and challenges that arrive in these sectors during the process of planning or decision making. There continues to be the need for more research on the impact of such probabilistic modeling with other approaches. Analyzing Data Through Probabilistic Modeling in Statistics is an essential reference source that builds on the available literature in the field of probabilistic modeling, statistics, operational research, planning and scheduling, data extrapolation in decision making, probabilistic interpolation and extrapolation in simulation, stochastic processes, and decision analysis. This text will provide the resources necessary for economics and management sciences and for mathematics and computer sciences. This book is ideal for interested technology developers, decision makers, mathematicians, statisticians and practitioners, stakeholders, researchers, academicians, and students looking to further their research exposure to pertinent topics in operations research and probabilistic modeling. The articles of this volume will not be indexed individually. Supervisory control and scheduling of resource allocation systems. Reachability graph perspective. https://www.zbmath.org/1456.93001 2021-04-16T16:22:00+00:00 "Huang, Bo" https://www.zbmath.org/authors/?q=ai:huang.bo "Zhou, MengChu" https://www.zbmath.org/authors/?q=ai:zhou.mengchu Publisher's description: The book offers an important guide to Petri net (PN) models and methods for supervisory control and system scheduling of resource allocation systems (RASs). Resource allocation systems are common in automated manufacturing systems, project management systems, cloud data centers, and software engineering systems. The authors -- two experts on the topic -- present a definition, techniques, models, and state-of-the art applications of supervisory control and scheduling problems. The book introduces the basic concepts and research background on resource allocation systems and Petri nets. The authors then focus on the deadlock-free supervisor synthesis for RASs using Petri nets. The book also investigates the heuristic scheduling of RASs based on timed Petri nets. Conclusions and open problems are provided in the last section of the book. This important book: \begin {itemize} \item Includes multiple methods for supervisory control and scheduling with reachability graphs, and provides illustrative examples \item Reveals how to accelerate the supervisory controller design and system scheduling of RASs based on PN reachability graphs, with optimal or near-optimal results \item Highlights both solution quality and computational speed in RAS deadlock handling and system scheduling \end {itemize} Written for researchers, engineers, scientists, and professionals in system planning and control, engineering, operation, and management, the book provides an essential guide to the supervisory control and scheduling of resource allocation systems (RASs) using Petri net reachability graphs, which allow for multiple resource acquisitions and flexible routings. Effects of system parameters on the optimal cost and policy in a class of multidimensional queueing control problems. https://www.zbmath.org/1456.90059 2021-04-16T16:22:00+00:00 "Vercraene, Samuel" https://www.zbmath.org/authors/?q=ai:vercraene.samuel "Gayon, Jean-Philippe" https://www.zbmath.org/authors/?q=ai:gayon.jean-philippe "Karaesmen, Fikri" https://www.zbmath.org/authors/?q=ai:karaesmen.fikri Summary: We consider a class of Markov Decision Processes frequently employed to model queueing and inventory control problems. For these problems, we explore how changes in different system input parameters (transition rates, costs, discount rates etc.) affect the optimal cost and the optimal policy when the state space of the problem is multidimensional. To address a large class of problems, we introduce two generic dynamic programming operators to model different types of controlled events. For these operators, we derive sufficient conditions to propagate monotonicity and supermodularity properties of the value function. These properties allow to predict how changes in system input parameters affect the optimal cost and policy. Finally, we explore the case when several parameters are changed at the same time. The online appendix is available at \url{https://doi.org/10.1287/opre.2017.1600}. Cross-layer modeling and optimization of multi-channel cognitive radio networks under imperfect channel sensing. https://www.zbmath.org/1456.94005 2021-04-16T16:22:00+00:00 "Kim, Jae Deok" https://www.zbmath.org/authors/?q=ai:kim.jaedeok "Hwang, Ganguk" https://www.zbmath.org/authors/?q=ai:hwang.ganguk Summary: In this paper, we consider a multi-channel cognitive radio network with multiple secondary users (SUs) and analyze the performance of users in the network. We assume primary users (PUs) adopt the automatic repeat request (ARQ) protocol at the medium access control layer. We have two main goals. Our first goal is to develop a cross-layer performance model of the cognitive radio network by considering the retransmission characteristics of the ARQ protocol and the interference between PUs and SUs due to imperfect channel sensing. Using the cross-layer performance model we analyze the throughput performance of SUs and the delay performance of PUs. Our second goal is to propose an optimal channel sensing method that maximizes the throughput performance of SUs while a given delay requirement of PUs is guaranteed. To this end, using our cross-layer performance model, we formulate an optimization problem and solve it to get an optimal channel sensing method that satisfies the design objectives. Numerical and simulation results are provided to validate our analysis and to investigate the performance of the optimal channel sensing method. Alternative formulations for the obnoxious $$p$$-median problem. https://www.zbmath.org/1456.90099 2021-04-16T16:22:00+00:00 "Lin, Chang-Chun" https://www.zbmath.org/authors/?q=ai:lin.chang-chun "Chiang, Yen-I" https://www.zbmath.org/authors/?q=ai:chiang.yen-i Summary: The problem of locating obnoxious facilities has gained attention, as do environmental issues. Particularly, in view of the impacts of facilities on their clients, textit{M. Labbé} et al. [Obnoxious $$p$$-median problems: valid inequalities and a branch-and-cut approach'', The OR Peripatetic Post-Graduate Programme: The OR Peripatetic Post-Graduate Programme Paris, 26--29 (2001; \url{https://pdfs.semanticscholar.org/2b02/b79302fd8003cb838999a7df73b8a7b5d73a.pdf})] formulated a model, called the obnoxious $$p$$-median problem, to locate obnoxious facilities away from the clients. However, this model is a difficult 0-1 programming problem, involving a large number of 0-1 variables. Actually, many of the 0-1 variables can be relieved in some alternative formulations. This paper presents three alternative formulations for the obnoxious $$p$$-median problem. Numerical examples show that the formulation based on distance-sorting appeared to be the most efficient one. A heterogeneous QUALIFLEX method with criteria interaction for multi-criteria group decision making. https://www.zbmath.org/1456.90086 2021-04-16T16:22:00+00:00 "Liang, Yingying" https://www.zbmath.org/authors/?q=ai:liang.yingying "Qin, Jindong" https://www.zbmath.org/authors/?q=ai:qin.jindong "Martínez, Luis" https://www.zbmath.org/authors/?q=ai:martinez.luis-manuel|martinez.luis-a "Liu, Jun" https://www.zbmath.org/authors/?q=ai:liu.jun.3|liu.jun.1|liu.jun|liu.jun.5|liu.jun.4|liu.jun.2 Summary: Green supplier selection complexity involves such problems which usually need to offer the management of dependencies among criteria in the selection process. Meanwhile, heterogeneous contexts are adopted based on different criteria, which drives to propose a novel multi-criteria group decision making (MCGDM) method. To solve this problem, this paper proposes a new MCGDM approach for heterogeneous information and dependent criteria based on the QUALItative FLEXible (QUALIFLEX) method and Choquet integral. For managing dependency among criteria, a new graphical representation of criteria interaction is presented and the identification of fuzzy measure is then obtained considering group consensus reaching. The multi-criteria heterogeneous QUALIFLEX method with regard to dependency of criteria is finally applied to a green supplier selection problem and a comparative analysis is performed to illustrate its feasibility and effectiveness. Scheduling jobs with a V-shaped time-dependent processing time. https://www.zbmath.org/1456.90078 2021-04-16T16:22:00+00:00 "Sedding, Helmut A." https://www.zbmath.org/authors/?q=ai:sedding.helmut-a Summary: In the field of time-dependent scheduling, a job's processing time is specified by a function of its start time. While monotonic processing time functions are well-known in the literature, this paper introduces non-monotonic functions with a convex, piecewise-linear V-shape similar to the absolute value function. They are minimum at an ideal start time, which is the same for all given jobs. Then, the processing time equals the job's basic processing time. Earlier or later, it increases linearly with slopes that can be asymmetric and job-specific. The objective is to sequence the given jobs on a single machine and minimize the makespan. This is motivated by production planning of moving car assembly lines, in particular, to sequence a worker's assembly operations such that the time-dependent walking times to gather materials from the line-side is minimized. This paper characterizes the problem's computational complexity in several angles. NP-hardness is observed even if the two slopes are the same for all jobs. A fully polynomial time approximation scheme is devised for the more generic case of agreeable ratios of basic processing time and slopes. In the most generic case with job-specific slopes, several polynomial cases are identified. On the complexity of constructing a minmax regret solution for the two-machine flow shop problem under the interval uncertainty. https://www.zbmath.org/1456.90079 2021-04-16T16:22:00+00:00 "Shafransky, Yakov" https://www.zbmath.org/authors/?q=ai:shafransky.yakov-m "Shinkarevich, Viktor" https://www.zbmath.org/authors/?q=ai:shinkarevich.viktor Summary: We prove the NP-hardness of constructing a minmax regret solution for the two-machine flow shop problem under the interval uncertainty of the job processing times. The problem complexity status has been an open question for over the past 20 years. We establish the NP-hardness of this problem using a so-called alternative scheme for proving the NP-hardness of optimization problems. Also, we show that the problem is non-approximable in polynomial time. New results for an open time-dependent scheduling problem. https://www.zbmath.org/1456.90070 2021-04-16T16:22:00+00:00 "Gawiejnowicz, Stanisław" https://www.zbmath.org/authors/?q=ai:gawiejnowicz.stanislaw "Kurc, Wiesław" https://www.zbmath.org/authors/?q=ai:kurc.wieslaw Summary: We present several new results for a single machine time-dependent scheduling problem of minimizing the total completion time of a set of linearly deteriorating jobs with unit basic processing times. First, we show new properties of cyclic transformations of V-shaped sequences for this problem. Next, applying the results, we prove a new necessary condition of schedule optimality for the considered problem, which decreases the previous bound on the cardinality of the set containing all possible optimal schedules by a multiplicative factor which is at most proportional to the reciprocal of the square root of the number of jobs. Finally, we compare the strength of the new and the previous necessary conditions by estimation of the numbers of schedules satisfying the respective conditions. Approximation algorithms for energy-efficient scheduling of parallel jobs. https://www.zbmath.org/1456.90072 2021-04-16T16:22:00+00:00 "Kononov, Alexander" https://www.zbmath.org/authors/?q=ai:kononov.aleksandr "Kovalenko, Yulia" https://www.zbmath.org/authors/?q=ai:kovalenko.yulia-viktorovna Summary: In this paper, we consider the homogeneous scheduling on speed-scalable processors, where the energy consumption is minimized. While most previous works have studied single-processor jobs, we focus on rigid parallel jobs, using more than one processor at the same time. Each job is specified by release date, deadline, processing volume and the number of required processors. Firstly, we develop constant-factor approximation algorithms for such interesting cases as agreeable jobs without migration and preemptive instances. Next, we propose a configuration linear program, which allows us to obtain an almost exact'' solution for the preemptive setting. Finally, in the case of non-preemptive agreeable jobs with unit-work operations, we present a three-approximation algorithm by generalization of the known exact algorithm for single-processor jobs. Scheduling in data gathering networks with background communications. https://www.zbmath.org/1456.90066 2021-04-16T16:22:00+00:00 "Berlińska, Joanna" https://www.zbmath.org/authors/?q=ai:berlinska.joanna Summary: In this work, we study scheduling in star data gathering networks with background communications. The worker nodes of the network hold datasets that have to be transferred directly to the base station. The communication speed of each link changes with time, due to other applications using the network, independently of the speeds of other links. Our goal is to gather all data within the minimum time. We show that while the preemptive version of this problem can be solved in polynomial time, the non-preemptive variant is strongly NP-hard. We propose for it an exact exponential algorithm based on dynamic programming, several polynomial time heuristics and local search algorithms. Theoretical performance guarantees and the existence of dominance relations between the heuristics are studied. The performance of the proposed algorithms is also tested in a series of computational experiments. Refined conditions for V-shaped optimal sequencing on a single machine to minimize total completion time under combined effects. https://www.zbmath.org/1456.90080 2021-04-16T16:22:00+00:00 "Soper, Alan J." https://www.zbmath.org/authors/?q=ai:soper.alan-j "Strusevich, Vitaly A." https://www.zbmath.org/authors/?q=ai:strusevich.vitaly-a Summary: We address single-machine scheduling problems for which the actual processing times of jobs are subject to various effects, including a positional effect, a cumulative effect and their combination. We review the known results on the problems to minimize the makespan, the sum of the completion times and their combinations and identify the problems for which an optimal sequence cannot be found by simple priority rules such as Shortest Processing Time (SPT) and/or Longest Processing Time (LPT). Typically, these are problems to minimize the sum of the completion times under a deterioration effect, and we verify under which conditions for these problems an optimal permutation is V-shaped (an LPT subsequence followed by an SPT subsequence). We demonstrate that previously used techniques for proving that an optimal sequence is V-shaped are not properly justified. We use the corrected method to describe a wide range of problems with a pure positional effect and a combination of a cumulative effect with a positional effect for which an optimal sequence is V-shaped. On the other hand, we show that even the refined approach has its limitations. Flowshop scheduling with learning effect and job rejection. https://www.zbmath.org/1456.90076 2021-04-16T16:22:00+00:00 "Mor, Baruch" https://www.zbmath.org/authors/?q=ai:mor.baruch "Mosheiov, Gur" https://www.zbmath.org/authors/?q=ai:mosheiov.gur "Shapira, Dana" https://www.zbmath.org/authors/?q=ai:shapira.dana Summary: We study scheduling problems on a proportionate flowshop. Three objective functions are considered: minimum makespan, minimum total completion time, and minimum total load. We consider a learning process; thus, the processing time of a job processed later in sequence is reduced. The scheduler has the option of job rejection; i.e., only a subset of the jobs are processed and the rejected jobs are penalized. An upper bound on the total permitted rejection cost is assumed. Since the single-machine versions of these problems were shown to be \textit{NP}-hard, we focus on the introduction of pseudopolynomial dynamic programming algorithms, indicating that the problems are \textit{NP}-hard in the ordinary sense. We provide an extensive numerical study verifying that the proposed solution algorithms are very efficient and instances containing up to 80 jobs are solved in no more than 5 ms. Scheduling two projects with controllable processing times in a single-machine environment. https://www.zbmath.org/1456.90069 2021-04-16T16:22:00+00:00 "Choi, Byung-Cheon" https://www.zbmath.org/authors/?q=ai:choi.byung-cheon "Park, Myoung-Ju" https://www.zbmath.org/authors/?q=ai:park.myoung-ju Summary: We consider two single-machine scheduling problems in which two competing projects share one common resource. Each project has multiple interim assessments, and its own jobs are ordered completely. A tardy job incurs a tardiness penalty cost which can be avoided by compressing some jobs, which requires an additional cost. The performance measure of each project is the total tardiness penalty cost plus the total compression cost. The first problem minimizes the weighted sum of the performance measures of two projects, and the second problem minimizes the performance measure of one project with a constraint on that of the other. We show that the first problem is solvable in strongly polynomial time and the second is weakly NP-hard. Furthermore, we analyze how the computational complexity of each problem changes if the number of projects is more than two. Serial-batching scheduling with two agents to minimize makespan and maximum cost. https://www.zbmath.org/1456.90071 2021-04-16T16:22:00+00:00 "He, Cheng" https://www.zbmath.org/authors/?q=ai:he.cheng.1 "Xu, Chunqi" https://www.zbmath.org/authors/?q=ai:xu.chunqi "Lin, Hao" https://www.zbmath.org/authors/?q=ai:lin.hao Summary: This paper considers three serial-batching scheduling problems with two agents to minimize the makespan of agent $$A$$ and maximum cost (or maximum lateness) of agent $$B$$ simultaneously. In these two-agent scheduling problems, jobs of different agents cannot be processed in a common batch, and the cost function of an agent depends only on its jobs. For each problem, we present a polynomial-time algorithm which can find all Pareto optimal solutions. Dynamic speed scaling minimizing expected energy consumption for real-time tasks. https://www.zbmath.org/1456.90172 2021-04-16T16:22:00+00:00 "Gaujal, Bruno" https://www.zbmath.org/authors/?q=ai:gaujal.bruno "Girault, Alain" https://www.zbmath.org/authors/?q=ai:girault.alain "Plassart, Stephan" https://www.zbmath.org/authors/?q=ai:plassart.stephan Summary: This paper proposes a discrete time Markov decision process approach to compute the optimal on-line speed scaling policy to minimize the energy consumption of a single processor executing a finite or infinite set of jobs with real-time constraints. We provide several qualitative properties of the optimal policy: monotonicity with respect to the jobs parameters, comparison with on-line deterministic algorithms. Numerical experiments in several scenarios show that our proposition performs well when compared with off-line optimal solutions and out-performs on-line solutions oblivious to statistical information on the jobs. Near-linear-time approximation algorithms for scheduling a batch-processing machine with setups and job rejection. https://www.zbmath.org/1456.90077 2021-04-16T16:22:00+00:00 "Ou, Jinwen" https://www.zbmath.org/authors/?q=ai:ou.jinwen Summary: In this paper we study a single batch-processing machine scheduling model. In our model, a set of jobs having different release dates needs to be scheduled onto a single machine that can process a batch of jobs simultaneously at a time. Each batch incurs a fixed setup time and a fixed setup cost. The decision maker may reject some of the jobs by paying penalty cost so as to achieve a tight makespan, but the total rejection penalty cost is required to be no greater than a given value. Our model extends several existing batch-processing machine scheduling models in the literature. We present efficient approximation algorithms with near-linear-time complexities. The ordered $$k$$-median problem: surrogate models and approximation algorithms. https://www.zbmath.org/1456.68229 2021-04-16T16:22:00+00:00 "Aouad, Ali" https://www.zbmath.org/authors/?q=ai:aouad.ali "Segev, Danny" https://www.zbmath.org/authors/?q=ai:segev.danny For the first time a provably-good polynomial approximation algorithm is presented for the following metric discrete convex ordered $$k$$-median problem: on a metric $$n$$-point space find a $$k$$-subset which minimizes the (nonincreasingly) weighted sum of all nonincreasingly reordered point-to-subset closest distances. Given some desired approximation level $$\epsilon$$, the approach is roughly as follows. Under a polynomial number of hypotheses, to be tested a posteriori each in turn, surrogate objectives of standard unordered $$k$$-median type are constructed having proven approximate optimal value. In the case of a general metric these surrogate objectives are further smoothed, on which a single-swap local search method is applied, yielding a solution proved to be within a $$O(\log n)$$ factor of the original optimal value. For a tree metric, a binary edge-weighted tree representation allows for a dynamic programming approach to solve the surrogate to optimality, which is proved to yield a factor $$2+\epsilon$$ optimal solution to the original problem. The construction of tree metrics whose surrogates have an optimality gap of $$2-O(\epsilon)$$ shows this latter is essentially tight. Reviewer: Frank Plastria (Brussels) Approximation algorithms for some position-dependent scheduling problems. https://www.zbmath.org/1456.90082 2021-04-16T16:22:00+00:00 "Yang, Liya" https://www.zbmath.org/authors/?q=ai:yang.liya "Lu, Xiwen" https://www.zbmath.org/authors/?q=ai:lu.xiwen Summary: The general position-dependent scheduling problems are studied in this paper. A 2-approximation algorithm is proposed for the learning scheduling problem on a single machine with release time to minimize the makespan. To minimize the total completion time on a single machine with release time and learning effect, we design a 2-approximation algorithm and a $$P T A S$$. Moreover, for the deteriorating scheduling problem to minimize the makespan on parallel machines, a 2-approximation algorithm is provided. Tropical Kirchhoff's formula and postoptimality in matroid optimization. https://www.zbmath.org/1456.90033 2021-04-16T16:22:00+00:00 "Jukna, Stasys" https://www.zbmath.org/authors/?q=ai:yukna.stasys-p "Seiwert, Hannes" https://www.zbmath.org/authors/?q=ai:seiwert.hannes Summary: Given an assignment of real weights to the ground elements of a matroid, the min-max weight of a ground element $$e$$ is the minimum, over all circuits containing $$e$$, of the maximum weight of an element in that circuit with the element $$e$$ removed. We use this concept to answer the following structural questions for the minimum weight basis problem. Which elements are persistent under a given weighting (belong to all or to none of the optimal bases)? What changes of the weights are allowed while preserving optimality of optimal bases? How does the minimum weight of a basis change when the weight of a single ground element is changed, or when a ground element is contracted or deleted? Our answer to this latter question gives the tropical $$( \min , + , - )$$ analogue of Kirchhoff's arithmetic $$( + , \times , \slash )$$ effective conductance formula for electrical networks. Constructing analytically tractable ensembles of stochastic covariances with an application to financial data. https://www.zbmath.org/1456.60023 2021-04-16T16:22:00+00:00 "Meudt, Frederik" https://www.zbmath.org/authors/?q=ai:meudt.frederik "Theissen, Martin" https://www.zbmath.org/authors/?q=ai:theissen.martin "Schäfer, Rudi" https://www.zbmath.org/authors/?q=ai:schafer.rudi "Guhr, Thomas" https://www.zbmath.org/authors/?q=ai:guhr.thomas Improving the productivity of the copper mining process in the Chilean copper industry. https://www.zbmath.org/1456.90084 2021-04-16T16:22:00+00:00 "Derpich, Ivan" https://www.zbmath.org/authors/?q=ai:derpich.ivan "Munoz, Nicole" https://www.zbmath.org/authors/?q=ai:munoz.nicole "Espinoza, Andrea" https://www.zbmath.org/authors/?q=ai:espinoza.andrea Summary: This paper presents a linear programming model used for decision making in the mining process of copper concentration from sulphide minerals. The developed model enables the decision maker to select the types of ore to be used in the mix to maximize the metallurgical recovery and the copper grade at the end of the process. The model is of the mixture model of minerals with added economic variables such as processing costs, electric power and others. The process has four sub-processes that are crushing the ore, crushing the crushed ore, flotation of the ground ore to obtain copper concentrate and drying, in which the water is extracted. The model uses a set of variables whose size varies according to the number of lots of minerals and the number of planning days considered. The model may be considered a considerable problem when a long period of time is planned, but has only been implemented with 3.000 variables and 2.000 constraints. The developed model is being implemented in the National mining company, which buys ore from small producers to produce copper concentrate and then melt and refine it to obtain high grade copper. The generated model produces savings of the order of thousand dollars per day, when compared to the current methods of allocating minerals, which represents millions of dollars per year. It also produces a benefit due to the fact that lower operating costs are obtained, with estimate savings of the order of 5\% of the current cost. Optimum cost analysis for an $$Geo/Geo/c/N$$ feedback queue under synchronous working vacations and impatient customers. https://www.zbmath.org/1456.90060 2021-04-16T16:22:00+00:00 "Yahiaoui, Lahcene" https://www.zbmath.org/authors/?q=ai:yahiaoui.lahcene "Bouchentouf, Amina Angelika" https://www.zbmath.org/authors/?q=ai:bouchentouf.amina-angelika "Kadi, Mokhtar" https://www.zbmath.org/authors/?q=ai:kadi.mokhtar Summary: This paper concerns the cost optimisation analysis of a discrete-time finite-capacity multiserver queueing system with Bernoulli feedback, synchronous multiple and single working vacations, balking, and reneging during both busy and working vacation periods. A reneged customer can be retained in the system by employing certain persuasive mechanism for completion of service. Using recursive method, the explicit expressions for the stationary state probabilities are obtained. Various system performance measures are presented. Further, a cost model is formulated. Then, the optimization of the model is carried out using quadratic fit search method (QFSM). Finally, the impact of various system parameters on the performance measures of the queueing system is shown numerically. An inventory planning problem for time-varying linear demand and parabolic holding cost with salvage value. https://www.zbmath.org/1456.90011 2021-04-16T16:22:00+00:00 "Kumar, Pavan" https://www.zbmath.org/authors/?q=ai:kumar.pavan Summary: In this manuscript, a model is proposed for the inventory planning problem with items which deteriorate linearly with respect to time. The concept of salvage value for deteriorated items is considered and incorporated in this model. The solution procedure of proposed optimization model is illustrated by a couple of numerical examples. A convexity check of the average total cost function is performed by plotting a two dimensional graph. The sensitivity test of the proposed model is performed to study the effect of changing the least as well as the most sensitive parameters in the proposed optimization model. Some graphical representations are constructed to discuss the outcomes and results so obtained for a choice of various parameters. Optimization of a perishable inventory system with both stochastic demand and supply: comparison of two scenario approaches. https://www.zbmath.org/1456.90015 2021-04-16T16:22:00+00:00 "Nguyen, Duc Huy" https://www.zbmath.org/authors/?q=ai:nguyen.duc-huy-t "Chen, Haoxun" https://www.zbmath.org/authors/?q=ai:chen.haoxun Summary: In this paper, we study a multi-period inventory model for a perishable product with both stochastic supply and demand in a rolling horizon framework. The product has a fixed shelf life such as fresh products, blood cells, chemicals, drugs and other pharmaceutical products. The objective is to minimize the expected total cost composed of ordering, purchasing, holding, shortage and waste costs. We focus on finding a high-quality solution close to the optimal solution of the model that provides decision support for decision-makers. We propose a stochastic programming model and transform it into MILP model based on Conditional Scenarios (CS) approach to reduce the computational burden. By comparing with the Sample Average Approximation (SAA) method in a numerical study, we show that our method works efficiently. Modified Cramer-Lundberg models with on/off control and hyperexponential distribution of demands purchases values. https://www.zbmath.org/1456.90014 2021-04-16T16:22:00+00:00 "Nazarov, Anatoly" https://www.zbmath.org/authors/?q=ai:nazarov.anatoly-a "Broner, Valentina" https://www.zbmath.org/authors/?q=ai:broner.valentina Summary: The paper contains research of modified Cramer-Lundberg models of inventory management with On/Off control and hyperexponential distribution of demands purchases values. In first model we assume that input product flow has piecewise-constant rate, which depends on some threshold value, the random part of demand is modeled as Poisson process with constant intensity. Hereby system control is to switch the rate of the input product flow if the stock level in the system is more than threshold. Second model is investigated under following conditions: the rate of input product flow is a constant, the random part of demand is modeled as Poisson process with piecewise-constant intensity. In this case the idea of control the system is similar to the first model. We find explicit expressions for the stationary distribution of the inventory level for each models. The results are discussed with illustrative numerical example. For the entire collection see [Zbl 1393.68018]. Group efficiency analysis in decision processes: a data envelopment analysis approach group efficiency analysis in decision processes. https://www.zbmath.org/1456.90085 2021-04-16T16:22:00+00:00 "Hekmatnia, Mohsen" https://www.zbmath.org/authors/?q=ai:hekmatnia.mohsen "Amirteimoori, Alireza" https://www.zbmath.org/authors/?q=ai:amirteimoori.alireza "Kordrostami, Sohrab" https://www.zbmath.org/authors/?q=ai:kordrostami.sohrab Summary: Data envelopment analysis (DEA) is a powerful mathematical programming methodology for evaluating the relative efficiency of decision-making units (DMUs) with multiple outputs and multiple inputs. In the classic DEA, it has been implicitly assumed that all DMUs perform in a unique technology set and the traditional DEA cannot measure the relative performances of DMUs with dissimilar classes. In other words, if we have different groups of DMUs, the traditional DEA models cannot be applied to evaluate such cases. In this paper, it has been assumed that the DMUs do business in different groups. We are interested to evaluate the members of the groups. The main aim of this paper is proposing a DEA-based methodology to estimate the technical efficiency of DMUs along with different groups with different technologies. The proposed method is illustrated by an empirical example on banking industry. Communication cliques in mobile phone calling networks. https://www.zbmath.org/1456.90039 2021-04-16T16:22:00+00:00 "Li, Ming-Xia" https://www.zbmath.org/authors/?q=ai:li.mingxia "Xie, Wen-Jie" https://www.zbmath.org/authors/?q=ai:xie.wenjie "Jiang, Zhi-Qiang" https://www.zbmath.org/authors/?q=ai:jiang.zhiqiang "Zhou, Wei-Xing" https://www.zbmath.org/authors/?q=ai:zhou.weixing Optimal time-abstract schedulers for CTMDPs and Markov games. https://www.zbmath.org/1456.90174 2021-04-16T16:22:00+00:00 "Rabe, Markus" https://www.zbmath.org/authors/?q=ai:rabe.markus-n "Schewe, Sven" https://www.zbmath.org/authors/?q=ai:schewe.sven Summary: We study time-bounded reachability in continuous-time Markov decision processes for time-abstract scheduler classes. Such reachability problems play a paramount role in dependability analysis and the modelling of manufacturing and queueing systems. Consequently, their analysis has been studied intensively, and techniques for the approximation of optimal control are well understood. From a mathematical point of view, however, the question of approximation is secondary compared to the fundamental question whether or not optimal control exists. We demonstrate the existence of optimal schedulers for the time-abstract scheduler classes for all CTMDPs. Our proof is constructive: We show how to compute optimal time-abstract strategies with finite memory. It turns out that these optimal schedulers have an amazingly simple structure -- they converge to an easy-to-compute memoryless scheduling policy after a finite number of steps. Finally, we show that our argument can easily be lifted to Markov games: We show that both players have a likewise simple optimal strategy in these more general structures. For the entire collection see [Zbl 1415.68021]. Methodology for constructing a project management information system based on the enterprise application integration. https://www.zbmath.org/1456.90094 2021-04-16T16:22:00+00:00 "Tulupov, M. A." https://www.zbmath.org/authors/?q=ai:tulupov.m-a Summary: A review of the interrelated business and IT aspects of constructing a project management information system based on the enterprise application integration (EAI), such as ERP and software, is performed. Methodologies for constructing PMIS are practically absent in the scientific literature. A theoretical methodology is proposed that is developed based on the analysis of scientific literature related to the problem and similar EAI methodologies used for enterprise integration. Multiattribute group decision making based on intuitionistic fuzzy partitioned Maclaurin symmetric mean operators. https://www.zbmath.org/1456.90088 2021-04-16T16:22:00+00:00 "Liu, Peide" https://www.zbmath.org/authors/?q=ai:liu.peide.1|liu.peide "Chen, Shyi-Ming" https://www.zbmath.org/authors/?q=ai:chen.shyiming "Wang, Yumei" https://www.zbmath.org/authors/?q=ai:wang.yumei Summary: In this paper, we propose a new multiattribute group decision making (MAGDM) method based on the proposed weighted partitioned Maclaurin symmetric mean (IFWPMSM) operators for intuitionistic fuzzy numbers (IFNs). Firstly, motivated by the partitioned Bonferroni mean (PBM) and the Maclaurin symmetric mean (MSM), we present the partitioned MSM (PMSM) operator considering the hypothesis that all attributes can be cut into some groups, where the attributes in the same group are relevant to other multiple attributes of the same group, but the attributes in different groups are irrelevant. Then, we present its characteristics and some special cases. Then, we generalize the PMSM operator to propose the intuitionistic fuzzy PMSM (IFPMSM) operator for IFNs and its weighted form (IFWPMSM) for IFNs. Then, we present several characteristics and special examples of the presented IFPMSM operator and the proposed IFWPMSM operator. Finally, we propose a new MAGDM method based on the proposed IFWPMSM operator and make a comparison with the existing approaches to interpret the usability and the validity of the proposed method. Integrated production and distribution scheduling problems related with fixed delivery departure dates and number of late orders. https://www.zbmath.org/1456.90073 2021-04-16T16:22:00+00:00 "Li, Shanlin" https://www.zbmath.org/authors/?q=ai:li.shanlin "Li, Maoqin" https://www.zbmath.org/authors/?q=ai:li.maoqin Summary: We consider an integrated production and distribution scheduling problem faced by a typical make-to-order manufacturer which relies on a third-party logistics provider for finished product delivery to customers. In the beginning of a planning horizon, the manufacturer has received a set of orders to be processed on a single production line. Completed orders are delivered to customers by a finite number of vehicles (e.g. trucks, air freight containers on specific air flights) provided by the 3PL company which follows a fixed daily or weekly shipping schedule such that the vehicles have fixed departure dates which are not part of the decisions. The problem is to find a feasible schedule that minimizes one of the following objective functions: (1) the number of late orders, (2) the number of vehicles used subject to the condition that the number of late orders is minimum. We show that both problems are solvable in polynomial time. The extension of rank ordering criteria wighting methods in fuzzy environment. https://www.zbmath.org/1456.90092 2021-04-16T16:22:00+00:00 "Roszkowska, Ewa" https://www.zbmath.org/authors/?q=ai:roszkowska.ewa Summary: Weight elicitation is an important part of multi-criteria decision analysis. In real-life decision-making problems precise information is seldom available, and providing weights is often cognitively demanding as well as very time- and effort-consuming. The judgment of decision-makers (DMs) depends on their knowledge, skills, experience, personality, and available information. One of the weights determination approaches is ranking the criteria and converting the resulting ranking into numerical values. The best known and most widely used are rank sum, rank reciprocal and centroid weights techniques. The goal of this paper is to extend rank ordering criteria weighting methods for imprecise data, especially fuzzy data. Since human judgments, including preferences, are often vague and cannot be expressed by exact numerical values, the application of fuzzy concepts in elicitation weights is deemed relevant. The methods built on the ideas of rank order techniques take into account imprecise information about rank. The fuzzy rank sum, fuzzy rank reciprocal, and fuzzy centroid weights techniques are proposed. The weights obtained for each criterion are triangular fuzzy numbers. The proposed fuzzy rank ordering criteria weighting methods can be easily implemented into decision support systems. Numerical examples are provided to illustrate the practicality and validity of the proposed methods. Personalisation of production in the era of Industry 4.0 as a challenge for inventory managment in small and medium-sized production enterprises. https://www.zbmath.org/1456.90064 2021-04-16T16:22:00+00:00 "Grabowska, Sandra" https://www.zbmath.org/authors/?q=ai:grabowska.sandra Summary: Industry 4.0 is the result of the development of cyber-physical generation systems as a part of the fourth industrial revolution. Industry 4.0 sets new areas for change in the sphere of production and management but also influences various aspects of society. Industry 4.0 is focused on continuous improvement of production processes. This is a turnaround in the production control methodology, as the growing expectations of customers in the modern market cause, along with the increase in production efficiency, customisation of the product. In this trend, the customer decides about the product, personalising it as much as possible and in the best possible way. These are new challenges in the field of inventory management. The article aims to present a method of calculating the optimal amount of the cost of a rotating stock in a production enterprise with an unevenly distributed demand, which is the case with personalised orders. Modelling large timescale and small timescale service variability. https://www.zbmath.org/1456.60246 2021-04-16T16:22:00+00:00 "Gribaudo, Marco" https://www.zbmath.org/authors/?q=ai:gribaudo.marco "Horváth, Illés" https://www.zbmath.org/authors/?q=ai:horvath.illes "Manini, Daniele" https://www.zbmath.org/authors/?q=ai:manini.daniele "Telek, Miklós" https://www.zbmath.org/authors/?q=ai:telek.miklos Summary: The performance of service units may depend on various randomly changing environmental effects. It is quite often the case that these effects vary on different timescales. In this paper, we consider small and large scale (short and long term) service variability, where the short term variability affects the instantaneous service speed of the service unit and a modulating background Markov chain characterizes the long term effect. The main modelling challenge in this work is that the considered small and long term variation results in randomness along different axes: short term variability along the time axis and long term variability along the work axis. We present a simulation approach and an explicit analytic formula for the service time distribution in the double transform domain that allows for the efficient computation of service time moments. Finally, we compare the simulation results with analytic ones. Minimizing the sum of distances to a server in a constraint network. https://www.zbmath.org/1456.68221 2021-04-16T16:22:00+00:00 "Carmi, Paz" https://www.zbmath.org/authors/?q=ai:carmi.paz "Chaitman-Yerushalmi, Lilach" https://www.zbmath.org/authors/?q=ai:chaitman-yerushalmi.lilach "Ozeri, Bat-Chen" https://www.zbmath.org/authors/?q=ai:ozeri.bat-chen Summary: This paper deals with constructing centralized geometric network that represents a set of clients that need to be connected to a server. We consider the problem of minimizing the sum of the shortest paths from the clients to the server in the network, subject to some constraints. We refer to this summation as the network \textit{cost}. The motivation for this work was derived from the combination of centralized communication network and geometric sink spanner. Formally, given a set $$V$$ of points (representing clients) in the plane, a special point $$q \in V$$ (representing a server), a real number $$w > 0$$ (the network weight bound), and an integer $$h \geq 1$$ (the hop bound), the goal is to construct a directed network $$G = (V, E)$$ of minimum cost, such that there is a directed path from every point in $$V$$ to $$q$$ with at most $$h$$ hops, and $$\sum_{(v, u) \in E} | v u | \leq w$$, where $$| v u |$$ denotes the Euclidean distance between $$v$$ and $$u$$. In this paper we start by establishing a connection between the considered problem and geometric sink spanner network. Then, we present our main result, a bi-criteria approximation algorithm, that approximates both the weight and the \textit{cost} of the network with respect to an optimal network, in $$(| V | / \varepsilon)^{O(h / \varepsilon)}$$. More precisely, we construct a network such that its \textit{cost} (i.e., sum of the shortest paths from every $$v \in V$$ to $$q)$$ is at most $$(1 + h \varepsilon)$$ times the \textit{cost} of an optimal network and its weight (i.e., $$\sum_{(v, u) \in E} | v u |)$$ is at most $$(1 + \varepsilon) \cdot w$$, for any $$\varepsilon > 0$$. Trade-offs analysis of sustainability dimensions using integer-valued DEA. https://www.zbmath.org/1456.90089 2021-04-16T16:22:00+00:00 "Noveiri, Monireh Jahani Sayyad" https://www.zbmath.org/authors/?q=ai:noveiri.monireh-jahani-sayyad "Kordrostami, Sohrab" https://www.zbmath.org/authors/?q=ai:kordrostami.sohrab Summary: Conducting an in-depth exploration of trade-offs between sustainability aspects is a notable matter of taking decisions. Furthermore, there are many real world investigations that trade-offs and sustainability should be dealt with in the presence of desirable and undesirable materials while some of them accept integer amounts. Therefore, this study addresses trade-offs of sustainability dimensions when undesirable and integer-valued measures are presented. For this purpose, approaches based upon data envelopment analysis (DEA) are proposed. To explain, DEA models are introduced to calculate individual and group marginal rates of substitution and also directional marginal rates of substitution when integer and undesirable variables are observed. These procedures are applied to calculate trade-offs between different sustainability dimensions, including economic, environmental and social ones. The applications of ports and industrial parks are provided to clarify the approaches appeared in this study. The results derived from the proposed strategies show the usefulness and validity of them. Export and total factor productivity of EU new member states. https://www.zbmath.org/1456.90065 2021-04-16T16:22:00+00:00 "Jakšić, Saša" https://www.zbmath.org/authors/?q=ai:jaksic.sasa "Erjavec, Nataša" https://www.zbmath.org/authors/?q=ai:erjavec.natasa "Cota, Boris" https://www.zbmath.org/authors/?q=ai:cota.boris Summary: The common denominator of the European Union's (EU) strategic long-run documents is the role of total factor productivity in fostering future growth and competitiveness. Hence, this article analyses the impact of total factor productivity on export competitiveness in EU new member states (NMS). As opposed to the stagnation of the growth of total factor productivity in the advanced economies, EU NMS exhibited stronger growth that was interrupted due to the 2008 economic and financial crisis. After the crisis, the growth continued but it was not as strong as before. The results of the empirical analysis confirm the vital role of total factor productivity for the export competitiveness of the EU NMS. However, the results also point to the fact that the impact of total factor productivity on export competitiveness is not that beneficial in the countries where the value of total factor productivity has not returned to the pre-crisis level. Discrete self-organizing migration algorithm and $$p$$-location problems. https://www.zbmath.org/1456.90098 2021-04-16T16:22:00+00:00 "Janáček, Jaroslav" https://www.zbmath.org/authors/?q=ai:janacek.jaroslav "Kvet, Marek" https://www.zbmath.org/authors/?q=ai:kvet.marek Summary: Mathematical modelling, and integer programming generally, has many practical applications in different areas of human life. Effective and fast solving approaches for various optimization problems play an important role in the decision-making process and therefore, big attention is paid to the development of many exact and approximate algorithms. This paper deals only with a special class of location problems in which given number of facilities are to be chosen to minimize the objective function value. Since the exact methods are not suitable for their unpredictable computational time or memory demands, we focus here on possible usage of a special type of a particle swarm optimization algorithm transformed by discretization and meme usage into so-called discrete self-organizing migrating algorithm. In the paper, there is confirmed that it is possible to suggest a sophisticated heuristic for zero-one programming problem, which can produce near-to-optimal solution in much smaller time than the time demanded by exact methods. We introduce a special adaptation of the discrete self-organizing migration algorithm to the $$p$$-location problem making use of the path-relinking method. In the theoretical part of this paper, we introduce several strategies of the migration process. To verify their features and effectiveness, a computational study with real-sized benchmarks was performed. The main goal of the experiments was to find the most efficient version of the suggested solving tool. Solving the four index fully fuzzy transportation problem. https://www.zbmath.org/1456.90027 2021-04-16T16:22:00+00:00 "Hedid, Manal" https://www.zbmath.org/authors/?q=ai:hedid.manal "Zitouni, Rachid" https://www.zbmath.org/authors/?q=ai:zitouni.rachid Summary: In this paper, we will solve the four index fully fuzzy transportation problem $$(FFTP_4)$$ with some adapted classical methods. All problem's data will be presented as fuzzy numbers. In order to defuzificate these data, we will use the ranking function procedure. Our method to solve the $$FFTP_4$$ composed of two phases; in the first one, we will use an adaptation of well-known algorithms to find an initial feasible solution, which are the least cost, Russell's approximation and Vogel's approximation methods. In the second phase, we will test the optimality of the initial solution, if it is not optimal, we will improve it. A numerical analysis of the proposed methods is performed by solving different examples of different sizes; it is determined that they are stable, robust, and efficient. A proper comparative study between the adapted methods identifies the suitable method for solving $$FFTP_4$$. Designing continuous delay feedback control for lattice hydrodynamic model under cyber-attacks and connected vehicle environment. https://www.zbmath.org/1456.82635 2021-04-16T16:22:00+00:00 "Zhai, Cong" https://www.zbmath.org/authors/?q=ai:zhai.cong "Wu, Weitiao" https://www.zbmath.org/authors/?q=ai:wu.weitiao Summary: The rapid adoption of sensors has improved the communication capacity of vehicles, while connected vehicles are expected to become commercially available in the near future. In a connected vehicle environment, the dynamic continuous kinetic information on roadway could be readily available through sensors and internet of vehicular technologies. Nevertheless, in practice the vehicular networks may suffer from cyber-attacks, such that the perceived traffic data can deviate from the actual situation. Such potential risks may greatly worsen traffic condition. There is increasing need for developing a framework to control traffic flow effectively using continuous traffic information under cyber-attacks and connected vehicle environment. In this study, we propose an extended lattice model incorporating not only multiple connected vehicles but also the continuous delay feedback control signals. The stability condition is obtained based on the Hurwitz criteria and the $$H_\infty$$- norm. We further devise a continuous delay feedback controller to regularize the propagation of the enhanced lattice model in the case when the stability condition is not satisfied. The Bode-plot of transfer function shows that the stability region enhances with the continuous delayed feedback controller. We study how far ahead information about the downstream lattices should be integrated into the control process. Results show that the continuous traffic information and the controller contribute to mitigating traffic jam. Transshipment model considering environmental cost using mixed integer linear programming: beef distribution problem. https://www.zbmath.org/1456.90028 2021-04-16T16:22:00+00:00 "Januardi, Januardi" https://www.zbmath.org/authors/?q=ai:januardi.januardi "Ramdhani, Zakia Puspa" https://www.zbmath.org/authors/?q=ai:ramdhani.zakia-puspa "Harnaningrum, Rizky Novera" https://www.zbmath.org/authors/?q=ai:harnaningrum.rizky-novera Summary: The operational research paper in the transportation model nowadays is heading to the environmental issue. One of the famous operational research models is transshipment. Transshipment is an expanded model of transportation, in each distribution center between the start to the destination point. In this research, the transshipment model is integrated into an environmental function. The challenge is to find the right shipment of each route from the start, distribution, and destination point considering the transportation cost and carbon emission. This research proposed a transshipment model by minimizing transportation and carbon emission cost using mixed-integer linear programming for model formulation. The solution searching used branch and bound method. This research analyzed the environmental objective function and constrain effect in the transshipment model. The model was tested in a beef distribution case study in Bogor, Indonesia that has eight source points, three distribution centers, and six destination points. The model was experimented using carbon emission limitation scenarios. The optimum result in source allocation, distribution and destination were different between the two scenarios. The carbon emission limitation affected carbon emission production and total cost. Inhomogeneous percolation models for spreading phenomena in random graphs. https://www.zbmath.org/1456.82459 2021-04-16T16:22:00+00:00 "Dall'Asta, Luca" https://www.zbmath.org/authors/?q=ai:dallasta.luca Perceptionization of $$FM/FD/1$$ queuing model under various fuzzy numbers. https://www.zbmath.org/1456.90056 2021-04-16T16:22:00+00:00 "Karupothu, Usha Prameela" https://www.zbmath.org/authors/?q=ai:karupothu.usha-prameela "Kumar, Pavan" https://www.zbmath.org/authors/?q=ai:kumar.pavan Summary: We present an $$FM/FD/1$$ queuing model with unbounded limit under different fuzzy numbers. The arrival (landing) rate and service (administration) rate are thought to be fuzzy numbers such as triangular, trapezoidal and pentagonal fuzzy numbers. Because random event can only be observed in an uncertain manner, the fuzzy result of an uncertainty mapping is a fuzzy random variable. Consequently, it is conceivable to characterize the specific connection between randomness and fuzziness. The execution proportions of this lining miniature are fuzzified after that examined by utilizing $$\alpha$$-cut estimations and DSW algorithm (Dong, Shah and Wong). Relating to different fuzzy numbers, the numerical precedents are delinated to test the attainability of this model (miniature). A comparative illustration corresponding to each fuzzy number is accomplished for various estimations of $$\alpha$$. The residual time approach for $$(Q, r)$$ model under perishability, general lead times, and lost sales. https://www.zbmath.org/1456.90008 2021-04-16T16:22:00+00:00 "Barron, Yonit" https://www.zbmath.org/authors/?q=ai:barron.yonit "Baron, Opher" https://www.zbmath.org/authors/?q=ai:baron.opher Summary: We consider a $$(Q, r)$$ perishable inventory system with state-dependent compound Poisson demands with a random batch size, general lead times, exponential shelf times, and lost sales. We assume $$r < Q$$ and analyze the system using an embedded Markov process at the replenishment points. Using the queueing and Markov chain decomposition approach, we characterize the distribution of the residual lead time and derive the stationary distribution of the inventory level. We construct closed-form expressions for the expected total long-run average cost function. The closed form allows us to efficiently obtain, numerically, the optimal $$Q$$ and $$r$$ parameters. Numerical study provides several guidelines for the optimal control. For example, we show that approximating the lead time distribution by an exponential one only works when the optimal reorder point of the approximation is very small; in other cases the usage of the exact distribution can lead to substantial cost savings (up to 14\%). We further provide intuition insight on the optimal controls and how they depend on different factors, e.g., the lead time variability, and the demand features (arrival rate, size and variability). A supply chain model under return policy considering refurbishment, learning effect and inspection error. https://www.zbmath.org/1456.90016 2021-04-16T16:22:00+00:00 "Saha, Sujata" https://www.zbmath.org/authors/?q=ai:saha.sujata "Chakrabarti, Tripti" https://www.zbmath.org/authors/?q=ai:chakrabarti.tripti Summary: This article presents a three-echelon supply chain model consisting of a supplier, manufacturer, and a retailer, considering the return contract between the manufacturer and the retailer. Here, the manufacturer has two adjacent production units -- the main production unit and a refurbishment unit. The main production unit of the manufacturer is imperfect, which produces an admixture of perfect and defective items. He inspects all the products immediately after production and sells good quality items to the retailer. The retailer receives a proportion of faulty products from him due to his erroneous inspection process, which he returns after inspection. The manufacturer sends all the defective products received from the retailer and the main production unit to the refurbishment unit for reworking. Moreover, the learning effect of the employees on the production cost is considered. Under these circumstances, the cost functions of each of the supply chain players have been derived. Finally, the applicability of the proposed model has been shown using a numerical example. The sensitivity analysis has been presented to study the effect of the parameters on the optimum decision variables. A conservative index heuristic for routing problems with multiple heterogeneous service facilities. https://www.zbmath.org/1456.90057 2021-04-16T16:22:00+00:00 "Shone, Rob" https://www.zbmath.org/authors/?q=ai:shone.rob "Knight, Vincent A." https://www.zbmath.org/authors/?q=ai:knight.vincent-a "Harper, Paul R." https://www.zbmath.org/authors/?q=ai:harper.paul-r Summary: We consider a queueing system with $$N$$ heterogeneous service facilities, in which admission and routing decisions are made when customers arrive and the objective is to maximize long-run average net rewards. For this type of problem, it is well-known that structural properties of optimal policies are difficult to prove in general and dynamic programming methods are computationally infeasible unless $$N$$ is small. In the absence of an optimal policy to refer to, the Whittle index heuristic (originating from the literature on multi-armed bandit problems) is one approach which might be used for decision-making. After establishing the required indexability property, we show that the Whittle heuristic possesses certain structural properties which do not extend to optimal policies, except in some special cases. We also present results from numerical experiments which demonstrate that, in addition to being consistently strong over all parameter sets, the Whittle heuristic tends to be more robust than other heuristics with respect to the number of service facilities and the amount of heterogeneity between the facilities. On impatience in Markovian $$M/M/1/N/DWV$$ queue with vacation interruption. https://www.zbmath.org/1456.90053 2021-04-16T16:22:00+00:00 "Bouchentouf, Amina Angelika" https://www.zbmath.org/authors/?q=ai:bouchentouf.amina-angelika "Guendouzi, Abdelhak" https://www.zbmath.org/authors/?q=ai:guendouzi.abdelhak "Majid, Shakir" https://www.zbmath.org/authors/?q=ai:majid.shakir Summary: The aim of this paper is to establish a cost optimization analysis for an $$M/M/1/N$$ queuing system with differentiated working vacations, Bernoulli schedule vacation interruption, balking and reneging. Once the system is empty, the server waits a random amount of time before he goes on working vacation during which service is provided with a lower rate. At the instant of the service achievement in the vacation period, if there are customers in the system at that time, the vacation is interrupted and the server returns to the regular busy period with probability $$\beta'$$ or continues the vacation with probability $$1 - \beta'$$. Once the working vacation is ended. The server returns to the normal busy period. If there are still no customers in the system, the server can take another working vacation of shorter duration. During working vacation periods, arriving customers become impatient with an individual timer which is exponentially distributed. Explicit expressions for the steady-state system size probabilities are derived using recursive technique. Further, interesting performance measures are explicitly obtained. Then, we construct a cost model in order to determine the optimal values of service rates, simultaneously, to minimize the total expected cost per unit time by using a quadratic fit search method (QFSM). Finally, numerical illustrations are added to validate the theoretical results. Exclusion in a priority queue. https://www.zbmath.org/1456.90055 2021-04-16T16:22:00+00:00 "de Gier, Jan" https://www.zbmath.org/authors/?q=ai:de-gier.jan "Finn, Caley" https://www.zbmath.org/authors/?q=ai:finn.caley Flow of pedestrians through narrow doors with different competitiveness. https://www.zbmath.org/1456.90042 2021-04-16T16:22:00+00:00 "Garcimartín, A." https://www.zbmath.org/authors/?q=ai:garcimartin.angel "Parisi, D. R." https://www.zbmath.org/authors/?q=ai:parisi.daniel-r "Pastor, J. M." https://www.zbmath.org/authors/?q=ai:pastor.j-martin "Martín-Gómez, C." https://www.zbmath.org/authors/?q=ai:martin-gomez.c "Zuriguel, I." https://www.zbmath.org/authors/?q=ai:zuriguel.iker Shortest node-disjoint paths on random graphs. https://www.zbmath.org/1456.05143 2021-04-16T16:22:00+00:00 "De Bacco C.," https://www.zbmath.org/authors/?q=ai:de-bacco-c. "Franz, S." https://www.zbmath.org/authors/?q=ai:franz.stephan|franz.silvio|franz.stefan|franz.sebastian "Saad, D." https://www.zbmath.org/authors/?q=ai:saad.david "Yeung, C. H." https://www.zbmath.org/authors/?q=ai:yeung.chi-ho A max-plus algebra approach for generating non-delay schedule. https://www.zbmath.org/1456.90083 2021-04-16T16:22:00+00:00 "Žužek, Tena" https://www.zbmath.org/authors/?q=ai:zuzek.tena "Peperko, Aljoša" https://www.zbmath.org/authors/?q=ai:peperko.aljosa "Kušar, Janez" https://www.zbmath.org/authors/?q=ai:kusar.janez Summary: Max-plus algebra is one of the promising mathematical approaches, that can be used for scheduling operations. It was already applied for Johnson's algorithm and cyclic job shop problem. In this article, max-plus algebra is used for generating non-delay schedule. When using non-delay schedule approach, in each stage, task with earliest possible start is scheduled. If there is more than one task eligible for scheduling, we apply the priority (dispatching) rule, and in case of another tie, the tie-breaking rule is applied. We present simple step-by-step procedure for generating matrices of starting and finishing times of operations, using Max-plus algebra. We apply LRPT (Longest Remaining Processing Time) as priority rule and SPT (Shortest Processing Time) as tie-breaking rule. Strategyproof auction mechanisms for network procurement. https://www.zbmath.org/1456.90096 2021-04-16T16:22:00+00:00 "Bichler, Martin" https://www.zbmath.org/authors/?q=ai:bichler.martin "Hao, Zhen" https://www.zbmath.org/authors/?q=ai:hao.zhen "Littmann, Richard" https://www.zbmath.org/authors/?q=ai:littmann.richard "Waldherr, Stefan" https://www.zbmath.org/authors/?q=ai:waldherr.stefan Summary: Deferred-acceptance auctions can be seen as heuristic algorithms to solve $${{\mathcal{N}}}{{\mathcal{P}}}$$-hard allocation problems. Such auctions have been used in the context of the Incentive Auction by the US Federal Communications Commission in 2017, and they have remarkable incentive properties. Besides being strategyproof, they also prevent collusion among participants. Unfortunately, the worst-case approximation ratio of these algorithms is very low in general, but it was observed that they lead to near-optimal solutions in experiments on the specific allocation problem of the Incentive Auction. In this work, which is inspired by the telecommunications industry, we focus on a strategic version of the minimum Steiner tree problem, where the edges are owned by bidders with private costs. We design several deferred-acceptance auctions (DAAs) and compare their performance to the Vickrey-Clarke-Groves (VCG) mechanism as well as several other approximation mechanisms. We observe that, even for medium-sized inputs, the VCG mechanisms experiences impractical runtimes and that the DAAs match the approximation ratios of even the best strategy-proof mechanisms in the average case. We thus provide another example of an important practical mechanism design problem, where empirics suggest that carefully designed deferred-acceptance auctions with their superior incentive properties need not come at a cost in terms of allocative efficiency. Our experiments provide insights into the trade-off between solution quality and runtime and into the additional premium to be paid in DAAs to gain weak group-strategyproofness rather than just strategyproofness. Modeling and dynamic analysis of knowledge transmission process: a model considering individual perception of knowledge value. https://www.zbmath.org/1456.90034 2021-04-16T16:22:00+00:00 "Liao, Shi-Gen" https://www.zbmath.org/authors/?q=ai:liao.shi-gen "Yi, Shu-Ping" https://www.zbmath.org/authors/?q=ai:yi.shuping Summary: The value of knowledge is explicit and positive. When individuals perceive knowledge value, knowledge receiver can actively acquire knowledge from individuals and static knowledge sources, while knowledge owner has the tendency to transmit the information about knowledge. Considering these individual behaviors, this paper establishes a network-based knowledge infection model. Specifically, the model attempts to incorporate static resources and information dissemination into the individual interaction of knowledge infection, and regards information dissemination as the intermediary of individual behavior affected by social environment. The basic regeneration number, equilibrium points and global stability rules of the model are analyzed theoretically. Theoretical analysis show that the active condition of knowledge transmission is $$R_0>1$$, while if $$R_0<1$$ knowledge in system will eventually die out. Numerical simulations verify the theoretical analysis results, and further investigate the influence of model parameters on the knowledge transmission process. The simulation results show that information dissemination and static resources should be paid attention to in the process of knowledge dissemination. Our model has an observable feature that knowledge transmission can take off without the initiation of individual spreaders. Switching strategies to optimize search. https://www.zbmath.org/1456.91035 2021-04-16T16:22:00+00:00 "Shlesinger, Michael F." https://www.zbmath.org/authors/?q=ai:shlesinger.michael-f Exact and heuristic solutions of a discrete competitive location model with Pareto-Huff customer choice rule. https://www.zbmath.org/1456.90097 2021-04-16T16:22:00+00:00 "Fernández, Pascual" https://www.zbmath.org/authors/?q=ai:fernandez.pascual "Pelegrín, Blas" https://www.zbmath.org/authors/?q=ai:pelegrin.blas "Lančinskas, Algirdas" https://www.zbmath.org/authors/?q=ai:lancinskas.algirdas "Žilinskas, Julius" https://www.zbmath.org/authors/?q=ai:zilinskas.julius Summary: An entering firm wants to compete for market share of an area by opening some new facilities selected among a finite set of potential locations (discrete space). Customers are spatially separated and there already are other firms operating in that area. In this paper, we use a variant of the well known Huff (proportional) customer choice rule, the so called Pareto-Huff, which have had little attention on the literature because of its nonlinear formulation. This untested rule considers that customers split their demand among the facilities that are Pareto optimal with respect to quality (to be maximized) and distance (to be minimized), proportionally to their attractions, i.e., a distant facility will capture demand of a customer only if it has higher quality than any other closer facility. A first formulation as a nonlinear programming problem is proposed, and then an equivalent formulation as a linear programming problem is presented, which allows us to obtain exact solutions for medium size problems. For large size problems, a heuristic procedure is also proposed to obtain the best approximate solutions. Its performance is checked for small size problems and its solutions are compared with the optimal solutions given by a standard optimizer, Xpress, using real geographical coordinates and population data of municipalities in Spain. Analysis of MAP/PH(1), PH(2)/2 queue with Bernoulli schedule vacation, Bernoulli feedback and renege of customers. https://www.zbmath.org/1456.60237 2021-04-16T16:22:00+00:00 "Ayyappan, G." https://www.zbmath.org/authors/?q=ai:ayyappan.govindasamy "Gowthami, R." https://www.zbmath.org/authors/?q=ai:gowthami.r Summary: A classical queueing model with two servers in which the inter arrival times follow Markovian arrival process, the service times are phase type distributed and the remaining random variables are exponentially distributed is studied in this paper. The resulting QBD process is investigated in the steady state by employing matrix-analytic method. We have also done the busy period analysis of our model and discussed about the waiting time distribution for our system. Some of the performance measures are provided. Finally, a few numerical and graphical examples are given. Production and transportation integration for commit-to-delivery mode with general shipping costs. https://www.zbmath.org/1456.90032 2021-04-16T16:22:00+00:00 "Li, Feng" https://www.zbmath.org/authors/?q=ai:li.feng.2|li.feng.1|li.feng "Xu, Zhou" https://www.zbmath.org/authors/?q=ai:xu.zhou "Chen, Zhi-Long" https://www.zbmath.org/authors/?q=ai:chen.zhi-long Summary: We study an integrated production and transportation problem for a make-to-order manufacturing company that operates under the commit-to-delivery mode and uses third-party logistics service providers to deliver products to customers on or before certain committed delivery dates. Such third-party logistics service providers often provide various shipping modes with quantity discounts and different guaranteed shipping times. As a result, the company's shipping costs need to be represented by general shipping cost functions that are typically nondecreasing, subadditive, and piecewise linear with shipping quantities, and nonincreasing with guaranteed shipping times. To the best of our knowledge, this paper is the first attempt to solve such an integrated production and transportation problem for the commit-to-delivery mode with general shipping costs. We prove that with general shipping costs, the problem is strongly $$\mathcal{N} \mathcal{P}$$-hard when the planning horizon consists of an arbitrary number of days. For the two-day problem, we show that it is ordinarily $$\mathcal{N} \mathcal{P}$$-hard, but is unlikely to have a fully polynomial time approximation scheme (FPTAS) unless $$\mathcal{N} \mathcal{P} = \mathcal{P}$$. Interestingly, we find that when the unit inventory holding cost is relatively small, which is often true in practice, there exists an FPTAS for the two-day problem, the development of which hinges on a newly discovered property for minimizing the sum of two general piecewise linear functions. For the multiday problem, we develop a heuristic algorithm based on column generation, which novelly uses a dynamic program for a variant of the problem with a single customer. Results from computational experiments demonstrate that the heuristic algorithm can find near-optimal solutions with optimality gaps less than 1\% in a short running time. The online appendices are available at \url{https://doi.org/10.1287/ijoc.2019.0935}. Understanding and predicting users' rating behavior: a cognitive perspective. https://www.zbmath.org/1456.90087 2021-04-16T16:22:00+00:00 "Li, Qiudan" https://www.zbmath.org/authors/?q=ai:li.qiudan "Zeng, Daniel Dajun" https://www.zbmath.org/authors/?q=ai:zeng.daniel-dajun "Xu, David Jingjun" https://www.zbmath.org/authors/?q=ai:xu.david-jingjun "Liu, Ruoran" https://www.zbmath.org/authors/?q=ai:liu.ruoran "Yao, Riheng" https://www.zbmath.org/authors/?q=ai:yao.riheng Summary: Online reviews are playing an increasingly important role in understanding and predicting users' rating behavior, which brings great opportunities for users and organizations to make better decisions. In recent years, rating prediction has become a research hotspot. Existing research primarily focuses on generating content representation based on context information and using the overall rating score to optimize the semantics of the content, which largely ignores aspect ratings reflecting users' feelings about more specific attributes of a product and semantic associations among aspect ratings, words, and sentences. Cognitive theory research has shown that users evaluate and rate products following the part-whole pattern; namely, they use aspect ratings to explicitly express sentiments toward aspect attributes of products and then describe those attributes in detail through the corresponding opinion words and sentences. In this paper, we develop a deep learning-based method for understanding and predicting users' rating behavior, which adopts the hierarchical attention mechanism to unify the explicit aspect ratings and review contents. We conducted experiments using data collected from two real-world review sites and found that our proposed approach significantly outperforms existing methods. Experiments also show that the performance advantage of the proposed approach mainly comes from the high-quality representation of review content and the effective integration of aspect ratings. A user study empirically shows that aspect ratings influence users' perceived review helpfulness and reduce users' cognitive effort in understanding the overall score given for a product. The research contributes to the rating behavior analysis literature and has significant practical implications. The online supplement, which includes the code and data used for this paper, is available at \url{https://doi.org/10.1287/ijoc.2019.0919}. Communication-constrained expansion planning for resilient distribution systems. https://www.zbmath.org/1456.90038 2021-04-16T16:22:00+00:00 "Byeon, Geunyeong" https://www.zbmath.org/authors/?q=ai:byeon.geunyeong "Van Hentenryck, Pascal" https://www.zbmath.org/authors/?q=ai:van-hentenryck.pascal "Bent, Russell" https://www.zbmath.org/authors/?q=ai:bent.russell-w "Nagarajan, Harsha" https://www.zbmath.org/authors/?q=ai:nagarajan.harsha Summary: Distributed generation and remotely controlled switches have emerged as important technologies to improve the resiliency of distribution grids against extreme weather-related disturbances. Therefore it becomes important to study how best to place them on the grid in order to meet a resiliency criteria, while minimizing costs and capturing their dependencies on the associated communication systems that sustain their distributed operations. This paper introduces the Optimal Resilient Design Problem for Distribution and Communication Systems (ORDPDC) to address this need. The ORDPDC is formulated as a two-stage stochastic mixed-integer program that captures the physical laws of distribution systems, the communication connectivity of the smart grid components, and a set of scenarios that specifies which components are affected by potential disasters. The paper proposes an exact branch-and-price algorithm for the ORDPDC that features a strong lower bound and a variety of acceleration schemes to address degeneracy. The ORDPDC model and branch-and-price algorithm were evaluated on a variety of test cases with varying disaster intensities and network topologies. The results demonstrate the significant impact of the network topologies on the expansion plans and costs, as well as the computational benefits of the proposed approach. The optimal design of low-latency virtual backbones. https://www.zbmath.org/1456.90040 2021-04-16T16:22:00+00:00 "Validi, Hamidreza" https://www.zbmath.org/authors/?q=ai:validi.hamidreza "Buchanan, Austin" https://www.zbmath.org/authors/?q=ai:buchanan.austin Summary: Two nodes of a wireless network may not be able to communicate with each other directly, perhaps because of obstacles or insufficient signal strength. This necessitates the use of intermediate nodes to relay information. Often, one designates a (preferably small) subset of them to relay these messages (i.e., to serve as a virtual backbone for the wireless network), which can be seen as a connected dominating set (CDS) of the associated graph. Ideally, these communication paths should be short, leading to the notion of a latency-constrained CDS. In this paper, we point out several shortcomings of a previously studied formalization of a latency-constrained CDS and propose an alternative one. We introduce an integer programming formulation for the problem that has a variable for each node and imposes the latency constraints via an exponential number of cut-like inequalities. Two nice properties of this formulation are that (1) it applies when distances are hop-based and when they are weighted and (2) it easily generalizes to ensure fault tolerance. We provide a branch-and-cut implementation of this formulation and compare it with a new polynomial-size formulation. Computational experiments demonstrate the superiority of the cut-like formulation. We also study related questions from computational complexity, such as approximation hardness, and answer an open problem regarding the fault diameter of graphs. The online supplement is available at \url{https://doi.org/10.1287/ijoc.2019.0914}. Social behavior for autonomous vehicles. https://www.zbmath.org/1456.90049 2021-04-16T16:22:00+00:00 "Schwarting, Wilko" https://www.zbmath.org/authors/?q=ai:schwarting.wilko "Pierson, Alyssa" https://www.zbmath.org/authors/?q=ai:pierson.alyssa "Alonso-Mora, Javier" https://www.zbmath.org/authors/?q=ai:alonso-mora.javier "Karaman, Sertac" https://www.zbmath.org/authors/?q=ai:karaman.sertac "Rus, Daniela" https://www.zbmath.org/authors/?q=ai:rus.daniela Summary: Deployment of autonomous vehicles on public roads promises increased efficiency and safety. It requires understanding the intent of human drivers and adapting to their driving styles. Autonomous vehicles must also behave in safe and predictable ways without requiring explicit communication. We integrate tools from social psychology into autonomous-vehicle decision making to quantify and predict the social behavior of other drivers and to behave in a socially compliant way. A key component is Social Value Orientation (SVO), which quantifies the degree of an agent's selfishness or altruism, allowing us to better predict how the agent will interact and cooperate with others. We model interactions between agents as a best-response game wherein each agent negotiates to maximize their own utility. We solve the dynamic game by finding the Nash equilibrium, yielding an online method of predicting multiagent interactions given their SVOs. This approach allows autonomous vehicles to observe human drivers, estimate their SVOs, and generate an autonomous control policy in real time. We demonstrate the capabilities and performance of our algorithm in challenging traffic scenarios: merging lanes and unprotected left turns. We validate our results in simulation and on human driving data from the NGSIM dataset. Our results illustrate how the algorithm's behavior adapts to social preferences of other drivers. By incorporating SVO, we improve autonomous performance and reduce errors in human trajectory predictions by 25\%. Model-checking precision agriculture logistics: the case of the differential harvest. https://www.zbmath.org/1456.91067 2021-04-16T16:22:00+00:00 "Saddem-yagoubi, Rim" https://www.zbmath.org/authors/?q=ai:saddem-yagoubi.rim "Naud, Olivier" https://www.zbmath.org/authors/?q=ai:naud.olivier "Godary-dejean, Karen" https://www.zbmath.org/authors/?q=ai:godary-dejean.karen "Crestani, Didier" https://www.zbmath.org/authors/?q=ai:crestani.didier Summary: The development, in the last decades, of technologies for precision agriculture allows the acquisition of crop data with a high spatial resolution. This offers possibilities for innovative control and raises new logistics issues that may be solved using discrete event models. In vineyards, some technologies make it possible to define zones with different qualities of grapes and sort the grapes at harvest to make different vintages. In this context, the differential harvest problem (DHP) consists in finding a trajectory of the harvesting machine in the field in order to obtain at least a given quantity of higher quality grapes and minimising working time. In available literature, the DHP has been solved using constraint programming. In this paper, we investigate if it is possible to solve the DHP using the cost optimal reachability analysis feature of a model-checking tool such as UPPAAL-CORA. A model named DHP$$\_$$PTA has been designed based on the priced timed automata formalism and the UPPAAL-CORA tool. The method made it possible to obtain the optimal trajectory of a harvesting machine for a vine plot composed of up to 14 rows. The study is based on real vineyard data. This paper is an extended version of a communication presented at WODES 2018 [\textit{R. Saddem-Yagoubi} et al., New approach for differential harvest problem: the model checking way'', IFAC-PapersOnLine 51, No. 7, 57--63 (2018; \url{doi:10.1016/j.ifacol.2018.06.279})]. Predictive analytics with strategically missing data. https://www.zbmath.org/1456.90095 2021-04-16T16:22:00+00:00 "Zhang, Juheng" https://www.zbmath.org/authors/?q=ai:zhang.juheng "Liu, Xiaoping" https://www.zbmath.org/authors/?q=ai:liu.xiaoping "Li, Xiao-Bai" https://www.zbmath.org/authors/?q=ai:li.xiaobai Summary: We study strategically missing data problems in predictive analytics with regression. In many real-world situations, such as financial reporting, college admission, job application, and marketing advertisement, data providers often conceal certain information on purpose in order to gain a favorable outcome. It is important for the decision-maker to have a mechanism to deal with such strategic behaviors. We propose a novel approach to handle strategically missing data in regression prediction. The proposed method derives imputation values of strategically missing data based on the Support Vector Regression models. It provides incentives for the data providers to disclose their true information. We show that with the proposed method imputation errors for the missing values are minimized under some reasonable conditions. An experimental study on real-world data demonstrates the effectiveness of the proposed approach. Data and the online appendix are available at \url{https://doi.org/10.1287/ijoc.2019.0947}. Local probabilities of randomly stopped sums of power-law lattice random variables. https://www.zbmath.org/1456.60101 2021-04-16T16:22:00+00:00 "Bloznelis, Mindaugas" https://www.zbmath.org/authors/?q=ai:bloznelis.mindaugas Summary: Let $$X_1$$ and $$N \geq 0$$ be integer-valued power-law random variables. For a randomly stopped sum $$S_N = X_1+\cdots+X_N$$ of independent and identically distributed copies of $$X_1$$, we establish a first-order asymptotics of the local probabilities $$\mathbf{P}(S_N = t)$$ as $$t \rightarrow + \infty$$. Using this result, we show the scaling $$k^{- \delta }$$, $$0 \leq \delta \leq 1$$, of the local clustering coefficient (of a randomly selected vertex of degree $$k)$$ in a power-law affiliation network. Role of the plurality rule in multiple choices. https://www.zbmath.org/1456.91093 2021-04-16T16:22:00+00:00 "Calvão, A. M." https://www.zbmath.org/authors/?q=ai:calvao.angelo-m "Ramos, M." https://www.zbmath.org/authors/?q=ai:ramos.marlon "Anteneodo, C." https://www.zbmath.org/authors/?q=ai:anteneodo.celia A hybrid DBH-VNS for high-end equipment production scheduling with machine failures and preventive maintenance activities. https://www.zbmath.org/1456.90074 2021-04-16T16:22:00+00:00 "Lu, Shaojun" https://www.zbmath.org/authors/?q=ai:lu.shaojun "Pei, Jun" https://www.zbmath.org/authors/?q=ai:pei.jun "Liu, Xinbao" https://www.zbmath.org/authors/?q=ai:liu.xinbao "Pardalos, Panos M." https://www.zbmath.org/authors/?q=ai:pardalos.panos-m Summary: The high-end equipment features with high value, complicated manufacturing process, and high status, and it thus brings a huge challenge to increase reliability, quality, and productivity during the production. In order to tackle this challenge and achieve automation, integration, and intelligence this paper proposes a hybrid metaheuristic for an integrated order scheduling and maintenance planning model with position-based processing time, parallel-batching processing, and multiple manufacturers. During the production, the continuous operation of the machine increases the probability of failure, and the repair work can eliminate the failure For each order, we derive some useful lemmas and develop an optimal algorithm to schedule jobs within it. Then, given the order assignment and sequence in the manufacturers, we propose a dynamic programing algorithm to make the decision on the maintenance planning. Subsequently, the investigated problem is proved to be NP-hard, thus, we propose a hybrid discrete black hole algorithm and variable neighborhood search (DBH-VNS) approach to solve the integrated problem. Some improvements are integrated into the proposed algorithm to obtain the competitive results, which include discrete encoding-based population updating scheme, the modified neighborhoods, and the VNS-based local search. Finally, we conduct computational experiments and the results demonstrate the effectiveness and validity of the proposed hybrid metaheuristic. Fault-free Hamiltonian cycle including given edges in folded hypercubes with faulty edges. https://www.zbmath.org/1456.05089 2021-04-16T16:22:00+00:00 "Cheng, Dongqin" https://www.zbmath.org/authors/?q=ai:cheng.dongqin Intermodality and rail transport: focus on port rail shunting operations. https://www.zbmath.org/1456.90022 2021-04-16T16:22:00+00:00 "Ambrosino, Daniela" https://www.zbmath.org/authors/?q=ai:ambrosino.daniela "Asta, Veronica" https://www.zbmath.org/authors/?q=ai:asta.veronica Summary: The presence of many actors interacting in the intermodal transport where rail modality is involved, causes some inefficiencies and some bottlenecks. These bottlenecks make the intermodal transport rigid and less fluid than the road transport. Operation research approaches can be useful as support for the decision makers in order to improve the process and to favour the development of rail transport. Thus, this work aims at describing the entire rail transport process within the intermodal transport in order to highlight the critical points that can be improved; in particular, both port rail shunting activities, and port rail terminal operations are discussed. A focus on a novel critical aspect never investigated before (at least for the author knowledge) is reported: the port rail shunting re-scheduling problem. A discussion on possible approaches for solving this problem is presented, together with a first approach based on a space-time network. For the entire collection see [Zbl 1452.90001]. The cumulative capacitated vehicle routing problem with profits under uncertainty. https://www.zbmath.org/1456.90025 2021-04-16T16:22:00+00:00 "Bruni, M. E." https://www.zbmath.org/authors/?q=ai:bruni.maria-elena "Nucamendi-Guillén, S." https://www.zbmath.org/authors/?q=ai:nucamendi-guillen.s "Khodaparasti, S." https://www.zbmath.org/authors/?q=ai:khodaparasti.s "Beraldi, P." https://www.zbmath.org/authors/?q=ai:beraldi.patrizia Summary: In this paper, we introduce the cumulative capacitated vehicle routing problem with profits and uncertain travel times. The aim is to visit a subset of customers maximizing the total collected revenue expressed as a decreasing function of the uncertain arrival times. The selective nature of the problem, the stochasticity of travel times, and the introduction of the capacity of vehicles make the problem quite challenging. We present a risk-averse approach leading to a non-linear mixed integer mathematical model. To solve the model, we develop a very fast and efficient metaheuristic designed to address the selective nature of the problem. The performance of the metaheuristic is shown by preliminary results obtained for two sets of benchmark instances. For the entire collection see [Zbl 1452.90001]. A new formulation of the single door truck scheduling problem. https://www.zbmath.org/1456.90075 2021-04-16T16:22:00+00:00 "Monaco, M. Flavia" https://www.zbmath.org/authors/?q=ai:monaco.maria-flavia "Sammarra, Marcello" https://www.zbmath.org/authors/?q=ai:sammarra.marcello Summary: In this paper we propose a new formulation for the truck scheduling problem at a cross-docking terminal with one inbound door and one outbound door. Through the computational experience, we show that the new formulation is more effective than a formulation from the literature. For the entire collection see [Zbl 1452.90001]. A traffic equilibrium nonlinear programming model for optimizing road maintenance investments. https://www.zbmath.org/1456.90063 2021-04-16T16:22:00+00:00 "Passacantando, Mauro" https://www.zbmath.org/authors/?q=ai:passacantando.mauro "Raciti, Fabio" https://www.zbmath.org/authors/?q=ai:raciti.fabio Summary: We consider a traffic network in which some of the roads need maintenance jobs. Due to budget constraints not all of the roads can be maintained and a central authority has to choose which of them are to be improved. We propose a nonlinear programming model where this choice is made according to its effects on the relative variation of the total cost, assuming that users behave according to Wardrop equilibrium principle. To assess the network improvement after maintenance we use the Bureau of Public Road link cost functions. For the entire collection see [Zbl 1452.90001]. Rolling-horizon heuristics for capacitated stochastic inventory problems with forecast updates. https://www.zbmath.org/1456.90020 2021-04-16T16:22:00+00:00 "Tresoldi, Emanuele" https://www.zbmath.org/authors/?q=ai:tresoldi.emanuele "Ceselli, Alberto" https://www.zbmath.org/authors/?q=ai:ceselli.alberto Summary: In this paper we propose a practical optimization approach based on the rolling-horizon paradigm to address general single-product periodic-review inventory control problems. Our framework supports many constraints and requirements that are found in real inventory problems and does not rely on any assumption on the statistical distribution of random variables. Ambiguous demand and costs, forecast updates, constant lead time, lost sales, flexible inventory capacity and product availability can all be taken into account. Three, increasingly sophisticated, solution methods are proposed and implemented within our optimization framework: a myopic policy, a linear programming model with risk penalization and a scenario-based stochastic programming model. The effectiveness of our approach is proved using a dataset of realistic instances. For the entire collection see [Zbl 1452.90001]. Heuristic data-driven feasibility on integrated planning and scheduling. https://www.zbmath.org/1456.90067 2021-04-16T16:22:00+00:00 "Casazza, Marco" https://www.zbmath.org/authors/?q=ai:casazza.marco "Ceselli, Alberto" https://www.zbmath.org/authors/?q=ai:ceselli.alberto Summary: We study the merging of data-driven approaches and mathematical programming formulations to solve an integrated planning and scheduling problem where jobs can be split in two separate tasks, one of them allowed to exceed its deadline at a price. Our study is driven by the increasing structural complexity of industrial scheduling problems that in some cases become too hard to be modeled as mathematical programs even by domain experts. We experiment on how to ensure the feasibility at a scheduling level by training a data-driven model, subsequently encoding it with a mathematical programming formulation, to be finally embedded in a planning model. Our experiments prove that our framework provides an effective heuristic approach, competing to exact formulations in terms of both accuracy and quality of the solutions, and it could be extended to those kind of problems where it is too hard to model the schedule feasibility. For the entire collection see [Zbl 1452.90001]. $$\mathrm{M}^p$$UFLP: universal facility location problem in the $$p$$-th power of metric space. https://www.zbmath.org/1456.90101 2021-04-16T16:22:00+00:00 "Xu, Yicheng" https://www.zbmath.org/authors/?q=ai:xu.yicheng "Xu, Dachuan" https://www.zbmath.org/authors/?q=ai:xu.dachuan "Zhang, Yong" https://www.zbmath.org/authors/?q=ai:zhang.yong.8 "Zou, Juan" https://www.zbmath.org/authors/?q=ai:zou.juan Summary: We propose and study the $$\mathrm{M}^p$$UFLP (universal facility location problem in the $$p$$-th power of metric space) in this paper, where the universal facility location problem (UFLP) extends several classical facility location problems like the uncapacitated facility location, hard-capacitated facility location, soft-capacitated facility location, incremental-cost facility location, concave-cost facility location, etc. In UFLP, a set of facilities, a set of clients, as well as the distances between them are given. Each facility has its specific cost function w.r.t. the amount of clients assigned to that facility. The goal is to assign the clients to facilities such that the sum of facility cost and service cost is minimized. In traditional facility location problems, the unit service cost is proportional to the distance between the client and its assigned facility and thus metric. However, in our work, this assumption is removed and a generalized version of universal facility location problem is proposed, which is the so-called $$\mathrm{M}^n$$ UFLP. When $$p = 2$$, it is also known as $$l_2^2$$ measure considered by \textit{K. Jain} and \textit{V. V. Vazirani} [J. ACM 48, No. 2, 274--296 (2001; Zbl 1138.90417)] and \textit{C. G. Fernandes} et al. [Math. Program. 153, No. 2 (A), 655--685 (2015; Zbl 1369.90143)]. Particularly in this case, we extend their work to include the aforementioned variants of facility location and a local search based $$(11.18 + \varepsilon)$$-approximation algorithm is proposed. Furthermore, the reanalysis of the proposed algorithm gives a $$p$$-related performance guarantee for general $$p$$. A MILP model for biological sample transportation in healthcare. https://www.zbmath.org/1456.90023 2021-04-16T16:22:00+00:00 "Benini, Mario" https://www.zbmath.org/authors/?q=ai:benini.mario "Detti, Paolo" https://www.zbmath.org/authors/?q=ai:detti.paolo "De Lara, Garazi Zabalo Manrique" https://www.zbmath.org/authors/?q=ai:zabalo-manrique-de-lara.garazi Summary: In this paper, a real-world transportation problem is addressed, concerning the collection and the transportation of blood and biological sample tubes from draw centers to a main hospital. Blood and other biological samples are collected in different centers during morning hours and have to be transported to the main hospital by a fleet of vehicles. Each sample has a given lifetime, i.e., a deadline. If a sample can not arrive to the hospital before the deadline either is discarded or a stabilization process must be carried out in dedicated centers. After stabilization, a sample can be delivered to the main hospital by a new deadline. A time-indexed Mixed Integer Linear Programming formulation of the problem is provided and tested on different instances generated from real-life data. For the entire collection see [Zbl 1452.90001]. Spatiotemporal evolution characteristics and phase diagrams of traffic dynamics at a crossroads. https://www.zbmath.org/1456.90048 2021-04-16T16:22:00+00:00 "Li, Qi-Lang" https://www.zbmath.org/authors/?q=ai:li.qi-lang "Jiang, Rui" https://www.zbmath.org/authors/?q=ai:jiang.rui "Ding, Zhong-Jun" https://www.zbmath.org/authors/?q=ai:ding.zhongjun "Wang, Bing-Hong" https://www.zbmath.org/authors/?q=ai:wang.binghong The maximum nearby flow problem. https://www.zbmath.org/1456.90102 2021-04-16T16:22:00+00:00 "Auricchio, Gennaro" https://www.zbmath.org/authors/?q=ai:auricchio.gennaro "Gualandi, Stefano" https://www.zbmath.org/authors/?q=ai:gualandi.stefano "Veneroni, Marco" https://www.zbmath.org/authors/?q=ai:veneroni.marco Summary: We present a new Linear Programming model that formulates the problem of computing the Kantorovich-Wasserstein distance associated with a truncated ground distance. The key idea of our model is to consider only the quantity of mass that is transported to nearby points and to ignore the quantity of mass that should be transported between faraway pairs of locations. The proposed model has a number of variables that depends on the threshold value used in the definition of the set of nearby points. Using a small threshold value, we can obtain a significant speedup. We use our model to numerically evaluate the percentage gap between the true Wasserstein distance and the truncated Wasserstein distance, using a set of standard grey scale images. For the entire collection see [Zbl 1452.90001]. Integrating ship movement scheduling and tug assignment within a canal harbor. https://www.zbmath.org/1456.90081 2021-04-16T16:22:00+00:00 "Tollo, Giacomo Di" https://www.zbmath.org/authors/?q=ai:di-tollo.giacomo "Pesenti, Raffaele" https://www.zbmath.org/authors/?q=ai:pesenti.raffaele "Petris, Matteo" https://www.zbmath.org/authors/?q=ai:petris.matteo Summary: In this paper we address the in-port ship scheduling and tug assignment problem. This problem aims to determine a schedule of ship movements, and their escorting tugs, within a canal harbor. We formulate the problem as a Boolean satisfiability problem. In particular, we deal with canal-harbors, as this kind of harbors present strict constraints, e.g., on safety distance. We consider the Port of Venice, a medium size Italian harbor, as a case study. For the entire collection see [Zbl 1452.90001]. On some properties of the mean inactivity time function. https://www.zbmath.org/1456.90061 2021-04-16T16:22:00+00:00 "Khan, Ruhul Ali" https://www.zbmath.org/authors/?q=ai:khan.ruhul-ali "Bhattacharyya, Dhrubasish" https://www.zbmath.org/authors/?q=ai:bhattacharyya.dhrubasish "Mitra, Murari" https://www.zbmath.org/authors/?q=ai:mitra.murari Summary: Different aspects of mean inactivity time (MIT) function such as properties, bounds and limiting behaviour are studied. We proceed to prove an important characterization theorem and also explore weak convergence issues. Finally, connections between MIT and reversed hazard rate functions are examined. Lagrangian discretization of crowd motion and linear diffusion. https://www.zbmath.org/1456.65137 2021-04-16T16:22:00+00:00 "Leclerc, Hugo" https://www.zbmath.org/authors/?q=ai:leclerc.hugo "Mérigot, Quentin" https://www.zbmath.org/authors/?q=ai:merigot.quentin "Santambrogio, Filippo" https://www.zbmath.org/authors/?q=ai:santambrogio.filippo "Stra, Federico" https://www.zbmath.org/authors/?q=ai:stra.federico An approximation scheme to solve evolution PDEs which have a gradient-flow structure is presented. The paper is organized as follows. Section 1 is an introduction. In Section 2 Lagrangian discretization of crowd motion is considered. The convergence of the discrete measures to a solution of the continuous PDE describing the crowd motion in dimension one is proved in this section. How a similar approach can be used to construct a Lagrangian discretization of a linear advection-diffusion equation is shown in Section 3. In Section 4 is proved that, for both the crowd motion and the linear diffusion discretizations, in one-dimension, there are bounds on the quantities which are relevant for the application of convergence theorems of the discrete schemes of sections 1 and 2. Computation of the Moreau-Yosida regularization, numerical experiments for crowd motion and for diffusion are given and discussed in Section 5. A numerical implementation in 2 dimensions to demonstrate the feasibility of the computations is also provided. Reviewer: Temur A. Jangveladze (Tbilisi) Traffic breakdown at a signal: classical theory versus the three-phase theory of city traffic. https://www.zbmath.org/1456.90045 2021-04-16T16:22:00+00:00 "Kerner, Boris S." https://www.zbmath.org/authors/?q=ai:kerner.boris-s "Klenov, Sergey L." https://www.zbmath.org/authors/?q=ai:klenov.sergey-l "Schreckenberg, Michael" https://www.zbmath.org/authors/?q=ai:schreckenberg.michael Revisiting multifractality of TCP traffic using multifractal detrended fluctuation analysis. https://www.zbmath.org/1456.90041 2021-04-16T16:22:00+00:00 "Xu, Youji" https://www.zbmath.org/authors/?q=ai:xu.youji "Feng, Huifang" https://www.zbmath.org/authors/?q=ai:feng.huifang
{"ft_lang_label":"__label__en","ft_lang_prob":0.84098965,"math_prob":0.7891079,"size":156147,"snap":"2021-04-2021-17","text_gpt3_token_len":36674,"char_repetition_ratio":0.22107299,"word_repetition_ratio":0.023535792,"special_character_ratio":0.2161745,"punctuation_ratio":0.18169075,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.96799004,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-04-23T18:14:01Z\",\"WARC-Record-ID\":\"<urn:uuid:0de3b5fa-4898-41b5-a298-6ccbf05fa7c3>\",\"Content-Length\":\"212413\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5e220a98-0d35-4bb3-843a-0ad3d4b8f593>\",\"WARC-Concurrent-To\":\"<urn:uuid:2f3714b6-fd49-45dc-afa6-92b38c1696b2>\",\"WARC-IP-Address\":\"141.66.194.3\",\"WARC-Target-URI\":\"https://www.zbmath.org/atom/cc/90B\",\"WARC-Payload-Digest\":\"sha1:ZULT64WU6SUUSF6ZUEGAE3YQ65DPVUTB\",\"WARC-Block-Digest\":\"sha1:CJAFJMIB3SEXK3UAZRIB5W46B6BPSPLH\",\"WARC-Identified-Payload-Type\":\"application/atom+xml\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-17/CC-MAIN-2021-17_segments_1618039596883.98_warc_CC-MAIN-20210423161713-20210423191713-00376.warc.gz\"}"}