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Silvén, Olli; Rintaluoma, Tero
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2 Citations
Summary. High-end mobile communication devices integrate video cameras, color displays, high-speed data modems, net browsers, media players, and phones into small battery-powered packages. The physical size limits the heat dissipation, while the battery capacity needs to be used conservatively to provide for satisfactory untethered active use time. Together with the required versatile capabilities of the devices, the physical size and battery capacity are essential constraints that must be taken into account from hardware to application software design. In video decoding additional constraints come from the need to support multiple digital video coding standards, and the platform-oriented design regimes of the device manufacturers. Along these lines, we consider the implementations of video capabilities for mobile devices in a top-down manner starting from typical applications, progressing to energy efficiency analysis via device architectures to codec implementations, and software platforms.
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Komulainen, Petri; Tölli, Antti; Latva-aho, Matti; Juntti, Markku
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3 Citations
This paper proposes practical coordinated linear transmit-receive processing schemes for the uplink (UL) of multiuser multiple-input multiple-output (MIMO) systems in the time division duplex (TDD) mode. The base station (BS) computes the transmission parameters in a centralized manner and employs downlink (DL) pilot signals to convey the information of the beam selection and beamformers to be used by the terminals. When coexisting with the DL transmit-receive zero forcing, the precoded DL demodulation pilots can be reused for UL beam allocation so that no additional pilot overhead is required. Furthermore, the locally available channel state information (CSI) of the effective MIMO channel is sufficient for the terminals to perform transmit power and rate allocation independently. In order to reduce the UL pilot overhead as well, we propose reusing the precoded UL demodulation pilots in turn for partial CSI sounding. The achievable sum rate of the system is evaluated in time-varying fading channels and with channel estimation. According to the results, the proposed UL transmission strategy provides increased rates compared to single-user MIMO transmission combined with user selection as well as to UL antenna selection transmission, without being sensitive to CSI uncertainty.
Väyrynen, Seppo; Häkkinen, Kari; Niskanen, Toivo
If we think about an ideal contemporary approach to occupational safety and health management (OSHM), we can model it, for instance, with three cornerstones: legislation, standards and good practices.
Alves, Hirley; Brante, Glauber; Souza, Richard Demo; Rebelatto, João Luiz
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1 Citations
In this paper we investigate the combination of rate and power allocation techniques in an orthogonal cooperative scheme using infra-structured (fixed) relays, under the incremental decode-and-forward protocol. We consider realistic large scale and small scale path loss models, taking into account the antennas heights and the presence or not of line-of-sight. Results demonstrate that the throughput performance can be significantly increased in the low signal-to-noise ratio (SNR) region due to rate allocation (RA), and in the high SNR region due to power allocation (PA). In addition, we present an energy efficiency analysis which shows that RA is much more efficient than PA over the whole SNR range.
Koskimäki, Heli; Juutilainen, Ilmari; Laurinen, Perttu; Röning, Juha
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When new data are obtained or simply when time goes by, the prediction accuracy of models in use may decrease. However, the question is when prediction accuracy has dropped to a level where the model can be considered out of date and in need of updating. This article describes a method that was developed for detecting the need for a model update. The method was applied in the steel industry, and the models whose need of updating is under study are two regression models, a property model and a deviation model, developed to facilitate planning of optimal process settings by predicting the yield strength of steel plates beforehand. To decide on the need for updating, information from similar past cases was utilized by introducing a limit called an exception limit for both models. The limits were used to indicate when a new observation was from an area of the model input space where the results of the models are exceptional. Moreover, an additional limit was formed to indicate when too many exceedings of the exception limit have occurred within a certain time scale. These two limits were then used to decide when to update the model.
Mohd Izhar, Mohd Azri; Fisal, Norsheila; Zhou, Xiaobo; Anwar, Khoirul; Matsumoto, Tad
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This article proposes a joint source-channel coding technique for two-dimensional (2D) binary Markov sources by using concatenated turbo block codes composed of two Bose, Chaudhuri, Hocquenghem (BCH) codes, of which output is followed by a rate-1 recursive systematic convolutional code. The source correlation of all rows and columns of the 2D source is well exploited by using a modified Bahl–Cocke–Jelinek–Raviv (BCJR) algorithm for the decoding of the BCH codes. Simulation results show that the proposed technique outperforms in terms of bit error rate the codes that exploits one-dimensional (1D) source correlation using the modified BCJR algorithm, and obviously the conventional system without source correlation exploitation. In order to further improve the performance, this article aims to make fine-tuning of the code parameters, given the source correlation property, that can achieve performance even closer to the theoretical limit than without the fine-tuning. Finally, results of image transmission simulations using two images, one having strong and the other weak 2D correlation, are presented to demonstrate the effectiveness of our proposed technique.
Huttunen, P.; Hänninen, O.; Myllylä, R.
Humans seem to sense weak radio waves and they can affect to spontaneous hand movements of test subjects. The aim of the present study was to clarify the responses in humans when crossing the standing waves caused by reflection of frequency modulated (FM)-radio and TV signals. Seven test subjects walked one at a time along a line between two rural houses, which were located close to each other at 5 km distance from the radio mast. The unconscious hand movements were recorded. The waves passed the first house and reflected from the brick wall of the second house, forming a set of standing waves between the houses. Clear reproducible reflexive hand movements took place when the person crossed the maximums of the standing waves generated by video and voice transmitting signals of analogy TV (p=0.001). In conclusion sensitive human seems to sense the standing waves of the TV signals near 190 MHz frequency.
Neitola, M.; Rahkonen, T.
A prototype analog correlator structure suitable for a WCDMA receiver was implemented. The advantages of this correlator are low power consumption compared to a digital correlator and small chip area. The target is to use such correlator as parallel correlators (fingers) of a RAKE receiver. The analog baseband correlator utilizes passive MOS-multipliers, a first-order low-pass continuous-time oversampling sigma–delta analog-to-digital converter and a second-order sinc type of decimation filter (for both I and Q input paths). The modulator sampling rate is twice the chip rate with oversampling ratios of 8–512 depending of the PN code length. The circuit was implemented in 0.8 μm CMOS-technology with a supply voltage of 2.8 V. The layout size is 345 μm×686 μm and the current drain is approximately 370 μA.
Louhisalmi, Y.; Leinonen, T.
Robotic theory, components and constructions have been studied and applied for neurosurgical instrumentation to improve the treatment accuracy and to cut the operation length. A passive six-jointed censored arm was developed for localization of neurosurgical targets. The arm was moved by the human hand. This experience promotes now the development of an active arm that moves also itself. In this paper three topics of this research are presented with preliminary results; tasks for the active arm, configuration of its linkage and the actuator-sensor construction.
Hänninen, Tuomo; Janhunen, Janne; Juntti, Markku
We summarize our recent state-of-the-art programmable and reconfigurable detector and QR decomposition (QRD) implementations targeting 3G long term evolution (LTE) downlink and uplink requirements. The downlink transmission is based on the orthogonal frequency division multiplexing, whereas the uplink transmission uses a single-carrier frequency-division multiple access. The downlink implementations are based on the programmable transport triggered architecture (TTA) which provides a flexible and energy efficient architecture template. In TTA detector implementation, the LTE detection rate requirements up to 20 MHz bandwidth and 4 × 4 antenna system with 64-QAM, are achieved by using 1–6 programmable cores in parallel. Each core runs at 277 MHz clock frequency and consumes 55.5–64.0 mW depending on the detector configuration. The downlink detector is based on the selective spanning with fast enumeration algorithm. The uplink field-programmable gate array (FPGA) detector implementation is targeted for 4 × 4 antenna system and 64-QAM achieving a detection rate requirement for 20 MHz bandwidth. The used FPGA board for uplink implementation is Xilinx Virtex-6 and the implementation has been carried out using Xilinx Vivado high level synthesis tool. Two different detector architectures are implemented. The first one achieves the detection rate requirement with a single processing block running at 231 MHz and the latter one with four blocks in parallel, each running at 247 MHz. The implemented detector is based on the K-best algorithm. A multiple-input multiple-output receiver requires QRD to produce valid inputs for the detector. In addition to detector implementations, QRD is also implemented on both TTA and FPGA. Modified Gram–Schmidt algorithm is used in both QRD implementations.
Kozmin, Kirill; Johansson, Jonny; Kostamovaara, Juha
10 Citations
This paper presents the design of a continuous time voltage comparator with low propagation delay dispersion. The comparator is intended to be used as a building block for a level-crossing AD converter: a type of AD converter where the sampling moments are triggered when an input signal crosses predetermined threshold levels. This type of system sets very high demands on the time measurement and the comparator to achieve the desired performance. The comparator design is based on several techniques to minimize the comparator propagation delay dispersion. The comparator has been implemented in a 0.35 μm BiCMOS process. Measured results show good agreement with simulations. The slew rate related propagation delay dispersion is measured to 90 ps for an input frequency range from 3 to 10 MHz and amplitudes from 200 mV to 1.65 V. The comparator static power consumption is 9 mW.
Baştuǧ, Ejder; Bennis, Mehdi; Kountouris, Marios; Debbah, Mérouane
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7 Citations
We consider a network model where small base stations (SBSs) have caching capabilities as a means to alleviate the backhaul load and satisfy users' demand. The SBSs are stochastically distributed over the plane according to a Poisson point process (PPP) and serve their users either (i) by bringing the content from the Internet through a finite rate backhaul or (ii) by serving them from the local caches. We derive closed-form expressions for the outage probability and the average delivery rate as a function of the signal-to-interference-plus-noise ratio (SINR), SBS density, target file bitrate, storage size, file length, and file popularity. We then analyze the impact of key operating parameters on the system performance. It is shown that a certain outage probability can be achieved either by increasing the number of base stations or the total storage size. Our results and analysis provide key insights into the deployment of cache-enabled small cell networks (SCNs), which are seen as a promising solution for future heterogeneous cellular networks.
Hintsala, H.; Bliznakova, K.; Pallikarakis, N.; Jämsä, T.
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The main goal of this study is to create a methodology for simulation of irregular solid breast lesions. Three-dimensional models are generated with random walk methods and afterwards processed with different techniques to smooth their appearance. Improved models of irregular lesions have been evaluated in the particular application of mammography.
This book proposes a movement towards collaborative and shared leadership approaches. It views OSH and performance excellence as entailing a broader examination of leadership relationships and practices. The complexity of leadership is explored through the impact that contexts (e.g. national and organizational culture) may have on leaders. Different views on bottom-up and top-down processes are integrated.
Lee, Young-Dong; Lee, Dae-Seok; Walia, Gaurav; Myllylae, Risto; Chung, Wan-Young
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Query based duplex vital signal monitoring system using wireless sensor network for Ubiquitous Healthcare was designed and tested. In this system, a wireless sensor network node attached on the human body provides sensor signal of an ECG (Electrocardiogram) and body temperature from multiple patients using wireless sensor network technology. A mote-based 3-lead ECG and body temperature monitoring system operating in wireless sensor network nodes was developed. The signal from sensors first is amplified with low noise instrument amplifier, and output of which is then fed to data acquisition board for connectivity to the sensor node. Vital signal from multiple patients can be relayed using an adaptive, multi-hop routing scheme to a wired base-station. The sampled signal will be filled in the form of packets for transmission using Zigbee compatible IEEE 802.15.4 standard wireless communication. The patients will be identified by the unique id assigned to the each mote. Among various existing routing protocols, presently simple variant of DSDV algorithm with a single destination node (the base-station) has being used for routing and transmission. Each mote in network simultaneously acts as transmitter, receiver and a router.
Kursu, Olli; Vähäsöyrinki, Mikko; Rahkonen, Timo
Here we present a low-power 16 channel neural signal measurement and stimulation system. The gain and high-pass corner frequency are programmable from 100 to 5000 and from 0.5 to 900 Hz, respectively. All channels can also be configured as outputs to
electrically stimulate neurons by bipolar current pulses. The amplifying stage consists of 16 pre-amplifiers, a multiplexer and two broadband post-amplifiers. The measured signal is digitized with a 10-bit SAR A/D converter. The circuit contains a control logic for buffering the measured results and sending them into an SPI bus that is used to stream the data to a PC at 3.5 Mbps. The logic can also control the circuit's bias currents, high-pass corner frequency, post-amplifier gains and stimulation current strengths. The mixed-signal circuit is manufactured with a low-cost 0.35 µm 4M2P IC process. The circuit consumes 1.29–1.59 mW power, depending on the amplifying gain.
Tervo, Valtteri; Matsumoto, Tad; Lu, Pen-Shun
In this paper, we propose a technique for coding the data from multiple correlated binary sources, with the aim of providing an alternative solution to the correlated source compression problem. Using non-systematic repeat-accumulate based codes, it is possible to achieve compression which is close to the Slepian–Wolf bound without relying on massive puncturing. With the technique proposed in this paper, instead of puncturing, compression is achieved by increasing check node degrees. Hence, the code rate can be more flexibly adjusted with the proposed technique in comparison with the puncturing-based schemes. Furthermore, the technique is applied to distributed joint source-channel coding (DJSCC). It is shown that in many cases tested, the proposed scheme can achieve mutual information very close to one with the lower signal-to-noise power ratio than turbo and low density generator matrix based DJSCC in additive white Gaussian noise channel. The convergence property of the system is also evaluated via the extrinsic information transfer analysis.
Fukawa, Kisho; Ormsub, Soulisak; Tölli, Antti; Anwar, Khoirul; Matsumoto, Tad
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This article proposes a novel design framework, EXIT-constrained binary switching algorithm (EBSA), for achieving near Shannon limit performance with single parity check and irregular repetition coded bit interleaved coded modulation and iterative detection with extended mapping (SI-BICM-ID-EM). EBSA is composed of node degree allocation optimization using linear programming (LP) and labeling optimization based on adaptive binary switching algorithm jointly. This technique achieves exact matching between the Demapper (Dem) and decoder's extrinsic information transfer (EXIT) curves while the convergence tunnel opens until the desired mutual information (MI) point. Moreover, this article proposes a combined use of SI-BICM-ID-EM with Doped-ACCumulator (D-ACC) and modulation doping (MD) to further improve the performance. In fact, the use of D-ACC and SI-BICM-ID (noted as DSI-BICM-ID-EM) enables the right-most point of the EXIT curve of the combined demapper and D-ACC decoder (Ddacc), denoted as DemDdacc, to reach a point very close to the (1.0, 1.0) MI point. Furthermore, MD provides us with additional degree-of-freedom in "bending" the shape of the demapper EXIT curve by choosing the mixing ratio of modulation formats, and hence the left most point of the demapper EXIT curve can flexibly be lifted up/pushed down with MD aided DSI-BICM-ID-EM (referred to as MDSI-BICM-ID-EM). Results of the simulations show that near-Shannon limit performance can be achieved with the proposed technique; with a parameter set obtained by EBSA for MDSI-BICM-ID-EM, the threshold signal-to-noise power ratio (SNR) is only roughly 0.5 dB away from the Shannon limit, for which the required computational complexity per iteration is at the same order as a Turbo code with only memory-2 convolutional constituent codes.
Hooli, Kari; Juntti, Markku; Heikkilä, Markku J.; Komulainen, Petri; Latva-aho, Matti; Lilleberg, Jorma
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52 Citations
The most important third generation (3G) cellular communications standard is based on wideband CDMA (WCDMA). Receivers based on TDMA style channel equalization at the chip level have been proposed for a WCDMA downlink employing long spreading sequences to ensure adequate performance even with a high number of active users. These receivers equalize the channel prior to despreading, thus restoring the orthogonality of users and resulting in multiple-access interference (MAI) suppression. In this paper, an overview of chip-level channel equalizers is delivered with special attention to adaptation methods suitable for the WCDMA downlink. Numerical examples on the equalizers′ performance are given in Rayleigh fading frequency-selective channels.
Lizarraga-Morales, Rocio A; Guo, Yimo; Zhao, Guoying; Pietikäinen, Matti; Sanchez-Yanez, Raul E
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In this paper, we study the use of local spatiotemporal patterns in a non-parametric dynamic texture synthesis method. Given a finite sample video of a texture in motion, dynamic texture synthesis may create a new video sequence, perceptually similar to the input, with an enlarged frame size and longer duration. In general, non-parametric techniques select and copy regions from the input sample to serve as building blocks by pasting them together one at a time onto the outcome. In order to minimize possible discontinuities between adjacent blocks, the proper representation and selection of such pieces become key issues. In previous synthesis methods, the block description has been based only on the intensities of pixels, ignoring the texture structure and dynamics. Furthermore, a seam optimization between neighboring blocks has been a fundamental step in order to avoid discontinuities. In our synthesis approach, we propose to use local spatiotemporal cues extracted with the local binary pattern from three orthogonal plane (LBP-TOP) operator, which allows us to include in the video characterization the appearance and motion of the dynamic texture. This improved representation leads us to a better fitting and matching between adjacent blocks, and therefore, the spatial similarity, temporal behavior, and continuity of the input can be successfully preserved. Moreover, the proposed method simplifies other approximations since no additional seam optimization is needed to get smooth transitions between video blocks. The experiments show that the use of the LBP-TOP representation outperforms other methods, without generating visible discontinuities or annoying artifacts. The results are evaluated using a double-stimulus continuous quality scale methodology, which is reproducible and objective. We also introduce results for the use of our method in video completion tasks. Additionally, we hereby present that the proposed technique is easily extendable to achieve the synthesis in both spatial and temporal domains.
Jeyhani, Vala; Vuorinen, Tiina; Noponen, Kai; Mäntysalo, Matti; Vehkaoja, Antti
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Electrical impedance pneumography signal is a valuable tool in qualifying better the person's health condition. It can be used in monitoring of respiration rate, rhythm and tidal volume. Impedance pneumography has also the potential in ambulatory physiological monitoring systems that are increasingly often implemented using plaster-like on-body devices. In such cases, the area of electrode substrate may be limited and therefore, the electrode configuration, which is able to provide both a clinically valuable electrocardiogram signal and accurate pulmonary information, is an issue. EAS is a useful small area electrode configuration that can be used for electrocardiogram measurements. In this work, different two-electrode bipolar pairs of EAS system are tested for impedance pneumography measurements. Two additional electrodes are also considered in these tests. Our results show that the electrode pair S-A provides the most accurate respiration cycle length and is least affected by movement artifact. Additionally, the results show that this electrode pair produces the signals with highest amplitude.
de Lima, Carlos H M; Bennis, Mehdi; Latva-aho, Matti
In this contribution, we investigate the concept of time division duplexing (TDD) mode as an alternative to underlay short-range femtocells on the uplink of legacy macrocell deployments. To mitigate the resulting co-channel interference, the underlaid femtocell tier uses a distributed mechanism which is based on regular busy tones and relies on minimal signaling exchange. Stochastic geometry is used to model practical scenarios by capturing network dynamics and channel variations. The impact of the fading correlation on the performance of the coordination mechanism is examined as well. Higher-order statistics through the cumulants concept are used to recover the distribution of the co-channel interference and evaluate the system performance in terms of the outage probability and average channel capacity. We observe that our analytical framework matches well with numerical results obtained using Monte Carlo simulations. In contrast to the uncoordinated frequency division duplexing mode, the coordinated TDD-underlay solution shows a reduction in the outage probability of nearly 80%, while the average spectral efficiency increases by approximately 90% in high loads.
Koskela, Timo; Vatjus-Anttila, Jarkko
3D Internet technologies are becoming essential enablers in many application areas including games, education, collaboration, navigation and social networking. The use of 3D Internet applications with mobile devices provides location-independent access and richer use context, but also performance issues. Therefore, one of the important challenges facing 3D Internet applications is the deployment of 3D graphics on mobile devices. In this article, we present an extensive survey on optimization techniques for 3D graphics deployment on mobile devices and qualitatively analyze the applicability of each technique from the standpoints of visual quality, performance and energy consumption. The analysis focuses on optimization techniques related to data-driven 3D graphics deployment, because it supports off-line use, multi-user interaction, user-created 3D graphics and creation of arbitrary 3D graphics. The outcome of the analysis facilitates the development and deployment of 3D Internet applications on mobile devices and provides guidelines for future research.
Phan, Vinh V.; Glisic, Savo
This paper presents an analysis of implementation losses in feedback channel state information (FCSI) based MAC protocols for the up-link (UL) of a centralized asynchronous CDMA packet radio system. Such protocol can be used in different segments (or domains) of the future wireless IP networks including WCDMA cellular networks, wireless LANs and Ad Hoc networks. The motivation behind these protocols is to control the channel access by statically or dynamically changing packet transmission permission probability (TPP), also referred to as persistence probability, depending on FCSI. This is supposed to keep the UL load under a certain threshold depending on the QoS requirements. As the main contribution of this paper, effects of the feedback delay, access delay, and imperfect channel sensing are taken into account simultaneously in the analysis. These effects are referred to as imperfections. For performance analysis the system sensitivity functions are introduced. These functions represent the relative performance losses due to the imperfections, which are also referred to as implementation losses. The tradeoff between throughput, outage probability and packet delay in the presence of imperfections is discussed based on numerical results for a number of queuing system models.
Macagnano, Davide; Destino, Giuseppe; Abreu, Giuseppe
This tutorial offers a comprehensive view of technological solutions and theoretical fundamentals of localization and tracking (LT) systems for wireless networks. We start with a brief classification of the most common types of LT systems, e.g. active versus passive technologies, centralized versus distributed solutions and so forth. To continue, we categorize the LT techniques based on the elementary types of position-related information, namely, connectivity, angle, distance and power-profile. The attention is then turned to the difference between active and passive LT systems, highlighting the evolution of the localization techniques. Motivated by the interests of industry and academia on distance-based active localization system, a deep review of the most common algorithms used in these systems is provided. Non-Bayesian and Bayesian techniques will be tackled and compared with numerical simulations. To list some of the proposed approaches, we mention the multidimensional scaling (MDS), the semidefinite programming (SDP) and the Kalman filter (KF) methods. To conclude the tutorial, we address the fundamental limits of the accuracy of range-based positioning. Based on the unifying framework proposed by Abel, we derive the closed-form expressions for the Cramér–Rao lower bound (CRLB), the Battacharyya Bound (BB), the Hammersley–Chapmann–Robbins Bound (HCRB) and the Abel Hybrid Bound (AHB) in a source localization scenario. We show a comparison of the aforementioned bounds with respect to a Maximum-Likelihood estimator and explore the difference between random and regular (equi-spaced anchors) network topologies. Finally, extensions to cooperative scenarios are also discussed in connection with the concept of information-coupling existing in multitarget networks.
Nazarov, S. A.; Ruotsalainen, K. M.
Trapped modes in the linearized water wave problem are localized free oscillations in an unbounded fluid with a free surface. For sometime, it has been known that certain structures, fixed or freely floating, can support such modes. In this paper, we consider the problem on a channel, which consists of a finite part and two cylindrical outlets into infinity. The finite (bounded) part may contain some submerged and/or surface-piercing bodies. Since the ordinary scattering matrix can by no means contribute any information on trapped modes, we introduce the fictitious scattering operator and present a criterion for the existence of trapped modes. The criterion states that the number of trapped modes is the difference of the multiplicities of the eigenvalue 1 of the fictitious scattering operator and the eigenvalue −i of the scattering matrix.
Yliniemi, Juho; Tiainen, Minna; Illikainen, Mirja
The fluidized-bed combustion (FBC) is an environmentally-friendly way to combust biomass and waste materials. However, as a side-product large amount of ash is created which is difficult to utilize due to its low reactivity and high heavy metal content. Instead, most of the ash ends up in landfills so novel utilization methods are needed. In this study lightweight aggregates (LWAs) were produced from recovered fuel-biofuel fly ash taken from a F boiler by granulating the fly ash with sodium silicate in a high-shear granulator. Blast furnace slag and metakaolin were studied as co-binders. Physical, chemical, and microstructural characterization was conducted for the precursors and LWAs. The crushing strength varied between 4.6 and 14.6 MPa. Addition of co-binders increased strength and produced denser structure. The loose bulk density was <1.08 g/cm3 and dry particle density was <1.77 g/cm3 for all prepared granules so they met the definition of lightweight aggregate in standard SFS-EN 13055-1. LWAs contained X-ray-amorphous material, indicating the formation of aluminosilicates and some crystalline phases, which were derived from the fly ash. This study presents a method of producing LWAs from fly ash that have physical properties comparable to LWAs manufactured by conventional methods without the need for high-temperature sintering or the usage of cement.
Pitkäaho, Tomi; Naughton, Thomas J.
Speckle is caused by the illumination of an optically rough surface by coherent light [1] which can cause problems in digital holography. Speckle in a reconstruction reduces visibility of details and may impede important measurements of an object. Speckle can be reduced by capturing multiple holograms and summing the reconstructed intensities [2-4]. Digital signal processing methods, which are applied after capture, have also been proposed [5–8].
Kohno, Ryuji; Latvaho, Matti; Prasad, Neeli Rashmi; Rodrigues, António
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Ekman, R.; Hagström, M.; Hallio, J.; Auranen, J.; Hänninen, O.; Huttunen, P.
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Users may feel stings and pain in their fingers when typing on their personal computers and notebooks and report that some of them are significantly worse than others, which they cannot use for long. The aim of this study was to clarify if the low frequency electric field (LFEF) voltages measured above keyboards differed and if the user reported symptoms correlate with the fields released by the devices. Nine PCs were analyzed. The results indicate that the LFEFs vary greatly. If the power supply lacks the connection to earth, the LFEF are several times greater than if the computer had earth connection. Also sensed symptoms were worse. In conclusion, the PC connection to earth is essential, but also other parts of the electromagnetic spectrum which the computers release may need attention as these parts seem to vary again significantly.
Koskimäki, Heli; Huikari, Ville; Siirtola, Pekka; Röning, Juha
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In this study an approach to an imperceptible and reliable worker monitoring system for industrial assembly lines is presented. A single wrist-worn inertial measurement unit is attached to the active wrist of the worker and by using acceleration and angular speed information, the behavior of the worker is recognized. The recognition is done in two steps. First the data are divided into 2-s intervals in which the performed activity is recognized using a knn classifier so that the system is usable online. In the second step, a state machine is used to recognize the completed tasks by searching for continuous, unvarying activity chains. The approach was developed as user-independent, although it can be easily adapted to a user-dependent case. By using the approach, behavior was recognized correctly and, on average, the correct beginning and ending moments of the behavior were missed by only 1 s. Thus a reliable monitoring system can be developed for industrial assembly lines. This work was supported by the EU 6th Framework Program Project XPRESS.
Ionescu, Theodor; Bögelsack, Gerhard; Leinonen, Tatu
The paper deals with the historical and methodological aspects of the MMS terminology work done within IFToMM for over 32 years. It provides an overview beginning with the early days, pinpointing the past and present achievements and sugges ting tasks for the future.
Liukkonen, Tapani N.
Business process development aims to improve the efficiency of the organisations, and to adapt them to the changing operational environment. To improve the results of this work, we describe a novel way to combine gaming with business process simulation tools to achieve better collaboration between the busi ness process experts and the workers participating in the business process deve lopment efforts. To achieve this goal our game tries to include the workers to the development process. This way the tacit knowledge about the work processes possessed by them could be used to tailor the new processes. In this paper we will introduce the topics of business process management and games to the readers, after which we sketch the outlines of our design. Our own game-like tool is intro duced by laying down the basic architecture of our game-like tool design from a high-level view, and by explaining the role of the different building blocks. After these explanations we compare our tool with the existing tools and criteria's deri ved from them. Our tool has great potential at presenting the complex simulation to the workers in a form that does not require special training or previous know ledge. We have strong confidence on our tool, and believe that it would have an impact on bringing the business process modelling and simulation closer to the workers in the organisations using it.
Leiviskä, K.; Uronen, P.
In der Entwicklung der Automation bei der Zellstoff - und Papierindustrie kann man drei Generationen der Informations — und Steuerungssysteme sehen; die Systeme mit zentralisierten Computern in den 60'n, die sogenannten gepackten Systeme danach und jetzt regieren,die microrechnerbasierten distributierten Systeme mit dem Thema: zentralisierte Überwachung, distributierte Regelung. Diese neueste Entwicklungsphase hat auch die hierarchischstrukturierte Mi 11-widesysteme verwirklicht. Diese Entwicklungstendenzen mit noch existierenden Problemen und mögliche Lösungen werden in diesem Vortrag detailliert diskutiert.
Mucchi, Lorenzo; Staderini, Claudia; Ylitalo, Juha; Kyösti, Pekka
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4 Citations
The third generation partnership Project's (3GPP) spatial channel model (SCM) is a stochastic channel model for MIMO systems. Due to fixed subpath power levels and angular directions, the SCM model does not show the degree of variation which is encountered in real channels. In this paper, we propose a modified SCM model which has random subpath powers and directions and still produces Laplace shape angular power spectrum. Simulation results on outage MIMO capacity with basic and modified SCM models show that the modified SCM model gives constantly smaller capacity values. Accordingly, it seems that the basic SCM gives too small correlation between MIMO antennas. Moreover, the variance in capacity values is larger using the proposed SCM model. Simulation results were supported by the outage capacity results from a measurement campaign conducted in the city centre of Oulu, Finland.
Drajic, Dejan; Hooli, Kari; Juntti, Markku
In this paper, the performance of turbo coding in WCDMA downlink is considered in conjunction with receivers using two adaptive channel equalizers. Bit error and frame error rates are compared to the performance of the conventional Rake receiver. Special consideration is given to the cases with two receive antennas, the efficiency of the channel interleaver, the number of iterations in decoding, the performance with various numbers of users, the influence of mobile receiver velocity as well as to the effect of power control. The simulation results show that turbo coding, combined with power control and channel equalizers is a very efficient way to implement reliable data transmissions in WCDMA downlink. The results in the paper also verify that the adaptive channel equalizers is a very promising technique to improve the receiver performance and increase the user capacity.
Glisic, Savo G.; Leppänen, Pentti A.
Taskila, Sanna; Särkelä, Riikka; Tanskanen, Juha
Peat is commonly known as a biofuel but it also has other more or less traditional uses, for example in folk medicine, building materials, or preservation of foods. Several studies suggest that the main composers of peat lands, Sphagnum mosses, may also have potential for a variety of other value-added products. Typically, those are related to the antibacterial and other preservative properties of Sphagnum, or to their high water adsorption ability. Molecular level applications, however, are still rarely reported. This might owe to the complex chemistry of Sphagnum and lacking cost-efficient technologies for the isolation of components of interest. In this literature survey, the structural and chemical properties of Sphagnum are reviewed together with their suggested uses. This is expected to facilitate new efforts to find commercially feasible applications for these extraordinary plants.
Häkkinen, Juha; Rahkonen, Timo; Kostamovaara, Juha
A variable gain amplifier with linear gain control has been implemented in a commercially available 8 GHz 1.2 µm BiCMOS process. The gain adjustment linearization is based on forcing a linearly controllable current through diode-connected transistors, thus generating an internal logarithmic control voltage for the Gilbert-type variable gain cell. A Cherry-Hopper type gain stage is used to provide most of the available gain. Thus, the maximum differential gain is 10 dB with over 1 GHz bandwidth and −6.9 dBm input −-1 dB compression power. Gain adjustment range of 50 dB at 200 MHz and 38 dB at 960 MHz is reported. The chip area is 1.15 × 2.15 mm and it consumes 40 mA from a 5 V supply.
Latva-aho, Matti; Lilleberg, Jorma
16 Citations
Parallel interference cancellation (PIC) based channel parameter estimators for frequency selective fading channels are proposed for the uplink in code-division multiple-access (CDMA) mobile communication systems. The performance of PIC based algorithms depends heavily on the quality of the multiple-access interference estimates, which can be improved by using adaptive channel estimation filters. The performance of two adaptive complex channel coefficient estimation filters has been verified in a fading channel by computer simulations. According to the results, the PIC based adaptive channel estimators outperform clearly conventional, successive interference cancellation, and decorrelation based adaptive channel estimators. The PIC method is also used in delay tracking. By using the principles of sample-correlate-choose-largest (SCCL) delay trackers, a robust algorithm for multiuser delay tracking in fading channels is obtained.
Suikkanen, Essi; Juntti, Markku
Requirements for higher data rates and lower power consumption set new challenges for hardware implementation of multiple-input multiple-output orthogonal frequency division multiplexing receivers. Simple detectors have the advantage of low complexity and power consumption, but they cannot offer as good performance as more complex detectors. Therefore, it would be beneficial to be able to adapt the detector algorithm to suit the channel conditions to minimize the receiver processing power consumption while satisfying the quality of service requirements. At low signal-to-noise ratio and/or low rank channel, more power and computation resources could be used for detection in order to guarantee reliable communication, while in good conditions, a simple and less power consuming detector could be used. In this paper, we compare the performance of different detection algorithms. The performance results are based on simulations in a long term evolution system where precoding and hybrid automatic repeat request are used. The effect of channel estimation on the performance is shown. Theoretical complexities of the detectors as numbers of arithmetic operations are presented. Also hardware implementation results based on the existing literature are included in the comparison. We discuss when it would be beneficial to use a complex detector and when a simple one would be sufficient and what kind of impact the channel estimation has on the choice of the detector.
Kela, Lari
5 Citations
An adjustable Helmholtz resonator in hydraulics is studied because of obvious lack of studies in the field. First the theory of a Helmholtz resonator is reviewed by examining older studies on the subject. Most of the previous studies have covered Helmholtz resonators in acoustics, but the same basic theory can be applied to hydraulics. After the theory review the test equipment and measurement methods are presented and some results are calculated analytically using the classical model and a modified model that takes the effect of spring mass into consideration. The spring mass is taken into account because the density of hydraulic oil is over 700 times greater than the density of air. In the last section the results of the calculations and measurements are discussed, and it is noted that the results of the experiments agree better with the modified model of classical Helmholtz theory. Some explanations for residual discrepancies are given but also some remarks are presented.
Mäntyjärvi, K.; Väisänen, A.; Karjalainen, J. A.
In this work, the influence of the cutting method on ultra-high-strength (UHS) steels and work hardened austenite stainless steel with regard to static and fatigue stress conditions was studied. In the experimental tests, tensile test bars and fatigue test bars were made using milling and two-laser cutting (CO2 and Yb:YAG) as well as water jet cutting. The following examinations were performed and related results reported: cutting, measurement of surface roughness, hardness test, micro-structure analyses and the measurement of the heat-effect zone. Specimen strength was tested using a standard tensile test and a fatigue resistance under reversed bending stress test. In the bending fatigue test lowest values were found in the laser cut samples, whereas milled edges gave clearly the best values.
Yrjämä-Huikuri, Liisa; Väyrynen, Seppo
This chapter presents a new kind of comprehensive data on all injurious accidents (10 years timespan) involving employees (N = 13,000) of two large workplaces in Finland. The main aim of this study was to clarify and assess the significance of risks among employees in different lost-time injury (LTI) accident categories, which were accidents at work, at home and during leisure time as well as when commuting to/from the job. Therefore, it was possible to reveal the total risk based on both frequency and absence time figures related to accidents. As far as the studied cases (a metal processing mill and a municipality) are concerned, home and leisure-time accidents appeared to be the most numerous category. Preliminary analysis of the metal processing case seemed to show that blue-collar employees have more numerous accidents of leisure in the same way they do have more numerous accidents at workplace, compared with white-collar employees.
Palojärvi, Pasi; Ruotsalainen, Tarmo; Kostamovaara, Juha
This paper describes simulation of theoperation of integrated high-speed
photodiodes and verification of the results bymeans of measurements performed with two typesof photodiode, one implemented in a standard 0.8μm CMOS process and the other in a standard1.2 μm BiCMOS process. The measured rise timesand responsivities of the photodiodes were <5ns and 0.28 A/W in the CMOS process and 30 ns and0.31 A/W in the BiCMOS process. Furthermore, thesuitability of the photodiode for 3D vision wasinvestigated by designing an array ofphotodetectors and measuring the isolationbetween the detector blocks. The results confirmthat the photodetectors and receiver for a pulsedlaser rangefinder can be implemented on the samechip in a standard process without any processmodifications.
Codreanu, Marian; Latva-Aho, Matti
In this paper the standard space time block coding, the selection diversity space time block coding and eigen-beamforming techniques are compared in a block fading scenario taking account the channel estimation errors at the transmitter side. The comparison criterion is the signal to noise ratio obtained to the receiver at the output of the antenna combiner. The channel is assumed to be perfectly known at the receiver side and partially known at the transmitter side. A downlink scenario based on OFDM modulation is assumed. We are focusing on a time division duplex link, where the channel at the transmitter side can be estimated based on incoming signal. In order to compare these strategies a simple and robust list square channel estimator was introduced at transmitter side and the estimated channel was used to compute the beamformer vector and for antenna selection. The simulation results show that the eigen-beamforming strategy provide the best performance even under high channel estimation errors and even in a case of independent antenna fading.
Iinatti, J.; Leppänen, P.
The theoretical analysis and simulation of the performance of a matched filter code acquisition structure with a median filter as the aiding device to cancel CW jamming in the AWGN channel is described. Both coherent and noncoherent structures are considered. As performance measures, the probability of detection and of a false alarm and mean acquisition times are used. Two kinds of analysis for coherent acquisition structure are presented. At first, the approximation for the pdf of the input signal to the comparator is used. Next, the probabilities are calculated directly. This is called the direct form. For the analysis of noncoherent acquisition, the pdf approximation of the coherent case is used. The performance of the median filter structure is compared to the performance of a simple linear interference cancellation method. The effect of CW jamming can be eliminated by both methods. Fixed thresholds of the comparator and the constant false alarm probability (CFAR) criteria are used. It is concluded that the median filter has a better performance, especially when fixed thresholds are used.
Boavida, Fernando; Kliem, Andreas; Renner, Thomas; Riekki, Jukka; Jouvray, Christophe; Jacovi, Michal; Ivanov, Stepan; Guadagni, Fiorella; Gil, Paulo; Triviño, Alicia
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Technology now offers the possibility of delivering a vast range of low-cost people-centric services to citizens. Internet of Things (IoT) supporting technologies are becoming robust, viable and cheaper. Mobile phones are increasingly more powerful and disseminated. On the other hand, social networks and virtual worlds are experiencing an exploding popularity and have millions of users. These low-cost technologies can now be used to create an Internet of People (IoP), a dynamically configurable integration platform of connected smart objects that allows enhanced, people-centric applications. As opposed to things-centric ones, IoP combines the real, sensory world with the virtual world for the benefit of people while it also enables the development of sensing applications in contexts such as e-health, sustainable mobility, social networks enhancement or fulfilling people's special needs. This paper identifies the main challenges, a possible approach, and key enabling technologies for a people-centric society based on the Internet of Things.
Su, Xiang; Fucci, Davide; Riekki, Jukka
In this paper, we present a two-layer inference framework to enable Semantic Web technology-based intelligent functionalities in ambient environments.The basic idea is that the low level inference is performed on themobile devices capable of utilizing ontology, and only the high level inference is performed at the server side. This paper presents the design of this framework and illustrates its usability by a use case. The framework fully utilizes the computing capabilities of devices in the system and this way minimizes the communication among devices.
Shah, Raza Ali; Rajatheva, Nandana; Ji, Yusheng
Subcarrier mapping (SCM) is considered to be crucial for capacity-maximization in an orthogonal frequency division multiplexing (OFDM) relaying network. Although SCM in an OFDM system has been investigated extensively, nevertheless, the outage probability and outage capacity analysis of the system is not yet available in the literature. This paper presents the outage analysis of a dual-hop OFDM relay system with ordered subcarrier paring schemes, i.e., worst-to-best (WTB) SCM and best-to-best (BTB) SCM. Accurate close-form expressions are derived for end-to-end outage while considering a dual-hop fixed gain amplify-and-forward (AF) relaying system with Rayleigh fading channel model. The first and second moments of end-to-end signal-to-noise ratio (SNR) and capacity are derived for WTB SCM and BTB SCM schemes while approximating the probability distribution function (PDF) of total capacity of each subcarrier pair by Gaussian distribution. The outage performances of these schemes are compared with balanced links, i.e., when the SNR is same for both hops, as well as unbalanced links, i.e., when the SNR of the second hop is one half of the SNR of the first hop. The numerical results validate the analysis in Rayleigh fading channel.
Haapola, Jussi; Shelby, Zach; Pomalaza-Ráez, Carlos; Mähönen, Petri
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13 Citations
We present an energy analysis technique applicable to medium access control (MAC) and multihop communications. Furthermore, the technique's application gives insight on using multihop forwarding instead of single-hop communications. Using the technique, we perform an energy analysis of carrier-sense-multiple-access (CSMA-) based MAC protocols with sleeping schemes. Power constraints set by battery operation raise energy efficiency as the prime factor for wireless sensor networks. A detailed energy expenditure analysis of the physical, the link, and the network layers together can provide a basis for developing new energy-efficient wireless sensor networks. The presented technique provides a set of analytical tools for accomplishing this. With those tools, the energy impact of radio, MAC, and topology parameters on the network can be investigated. From the analysis, we extract key parameters of selected MAC protocols and show that some traditional mechanisms, such as binary exponential backoff, have inherent problems.
Simsek, Meryem; Bennis, Mehdi; Guvenc, Ismail
8 Citations
Heterogeneous networks (HetNets) are expected to be a key feature of long-term evolution (LTE)-advanced networks and beyond and are essential for providing ubiquitous broadband user throughput. However, due to different coverage ranges of base stations (BSs) in HetNets, the handover performance of a user equipment (UE) may be significantly degraded, especially in scenarios where high-velocity UE traverse through small cells. In this article, we propose a context-aware mobility management (MM) procedure for small cell networks, which uses reinforcement learning techniques and inter-cell coordination for improving the handover and throughput performance of UE. In particular, the BSs jointly learn their long-term traffic loads and optimal cell range expansion and schedule their UE based on their velocities and historical data rates that are exchanged among the tiers. The proposed approach is shown not only to outperform the classical MM in terms of throughput but also to enable better fairness. Using the proposed learning-based MM approaches, the UE throughput is shown to improve by 80% on the average, while the handover failure probability is shown to reduce up to a factor of three.
Rahman, M.; Heikkala, J.; Lappalainen, K.
For higher productivity and product quality, it is necessary to know the accuracy of machine tools so that defective parts are not manufactured. Angular and positioning errors are quite common problems in machine tools. The origins of these errors are kinematic parameter deviations resulting from manufacturing errors, assembly errors or quasistatic errors. By static measurements such as laser interferometer, linear comparator (Heidenhain VM182), electronic inclinometers (Wyler Leveltronic) and dynamic measurements (Double Ball Bar, DBB) different kinds of error origin information of the machine tools can be obtained. It is possible to convert the measurement results of one method to another with certain degree of accuracy. This helps to justify the correctness of the measurement method and locate the error origins more precisely. This study shows a mapping between static and dynamic measurements of machine tools by calculating tool tip errors using different devices as mentioned above. For static measurements the laser interferometer, VM 182 and Leveltronic measuring systems and for dynamic measurements the DBB has been used in this study. Theoretical trace for DBB is obtained based on roll, pitch, yaws and positioning errors found by laser, VM182 and Leveltronic measurements. These traces are compared and simulated with the trace obtained by DBB.
Seppänen, Tiina M; Alho, Olli-Pekka; Seppänen, Tapio
Respiratory effort belt measurement is a widely used method to monitor respiration. Signal waveforms of respiratory volume and flow may indicate pathological signs of several diseases and, thus, it would be highly desirable to predict them accurately. Calibrated effort belts are sufficiently accurate for estimating respiratory rate, but the respiratory volume and flow prediction accuracies degrade considerably with changes in the subject's body position and breathing style.
An improved calibration method of respiratory effort belts is presented in this paper. It is based on an optimally trained FIR (Finite Impulse Response) filter bank constructed as a MISO system (Multiple-Input Single-Output) between respiratory effort belt signals and the spirometer in order to reduce waveform errors. Ten healthy adult volunteers were recruited. Breathing was varied between the following styles: metronome-guided controlled breathing rate of 0.1 Hz, 0.15 Hz, 0.25 Hz and 0.33 Hz, and a free rate that was felt normal by each subject. Body position was varied between supine, sitting and standing. The proposed calibration method was tested against these variations and compared with the state-of-the-art methods from the literature.
Relative waveform error decreased 60-70% when predicting airflow under changing breathing styles. The coefficient of determination R2 varied between 0.88-0.95 and 0.65-0.79 with the proposed and the standard method, respectively. Standard deviation of respiratory volume error decreased even 80%. The proposed method outperformed other methods.
Results show that not only the respiratory volume can be computed more precisely from the predicted airflow, but also the flow waveforms are very accurate with the proposed method. The method is robust to breathing style changes and body position changes improving greatly the accuracy of the calibration of respiratory effort belts over the standard method. The enhanced accuracy of the belt calibration offers interesting opportunities, e.g. in pulmonary and critical care medicine when objective measurements are required.
de Abreu, Giuseppe Thadeu Freitas; Mitchell, Craig John; Kohno, Ryuji
The design of a class of jitter-robust, Hermite polynomial-based, orthogonal pulses for ultra-wideband impulse radio (UWB-IR) communications systems is presented. A unified and exact closed-form expression of the auto- and cross-correlation functions of Hermite pulses is provided. Under the assumption that jitter values are sufficiently smaller than pulse widths, this formula is used to decompose jitter-shifted pulses over an orthonormal basis of the Hermite space. For any given jitter probability density function (pdf), the decomposition yields an equivalent distribution of
matrices which simplifies the convolutional jitter channel model onto a multiplicative matrix model. The design of jitter-robust orthogonal pulses is then transformed into a generalized eigendecomposition problem whose solution is obtained with a Jacobi-like simultaneous diagonalization algorithm applied over a subset of samples of the channel matrix distribution. Examples of the waveforms obtained with the proposed design and their improved auto- and cross-correlation functions are given. Simulation results are presented, which demonstrate the superior performance of a pulse-shape modulated (PSM-) UWB-IR system using the proposed pulses, over the same system using conventional orthogonal Hermite pulses, in jitter channels with additive white Gaussian noise (AWGN).
Pirinen, Pekka
6 Citations
Generic ultra-wideband (UWB) spread-spectrum system performance is evaluated in centralized and distributed spatial topologies comprising square-shaped indoor cells. Statistical distributions for link distances in single-cell and multicell configurations are derived. Cochannel-interference-induced outage probability is used as a performance measure. The probability of outage varies depending on the spatial distribution statistics of users (link distances), propagation characteristics, user activities, and receiver settings. Lognormal fading in each channel path is incorporated in the model, where power sums of multiple lognormal signal components are approximated by a Fenton-Wilkinson approach. Outage performance of different spatial configurations is outlined numerically. Numerical results show the strong dependence of outage probability on the link distance distributions, number of rake fingers, and path losses.
An integrated I/Q modulator has been implemented in a commercially available 8 GHz 1.2 μm double metal double poly BiCMOS process. The circuit converts baseband signals from 60 kHz to 500 kHz directly to a carrier frequency which can be selected between 925 MHz and 960 MHz. It has an internal 90° phase shifter for the LO signal, the phase shift of which can be adjusted automatically using a control signal generated inside the circuit. The size of the circuit is 2.9 mm×2.9 mm and it consumes about 50 mA. Measurements suggest that the specified LO suppression and image rejection of 35 dBc can be achieved under optimal operating conditions.
Anwar, Khoirul; Matsumoto, Tad
This paper proposes a novel time-concatenated turbo equalization technique, chained turbo equalization (CHATUE), that allows block transmission systems to eliminate the guard interval (GI), while achieving excellent performance. The proposed CHATUE algorithm connects turbo equalizers neighboring in time, so that they exchange information about their inter-block-interference components in the form of a posteriori log-likelihood ratio. The latest version of the low complexity sub-optimal turbo equalization technique for block-wise single carrier transmission, frequency domain soft cancellation and minimum mean squared error, is fully exploited in developing the CHATUE algorithm. Results of extrinsic information transfer chart analysis as well as a series of bit-error rate (BER) simulations show that excellent performances can be achieved without imposing heavy computational burden in multipath-rich (quasi-static) block Rayleigh fading channels. It is shown that, if the information bit-rate is kept identical (because it may be unpreferable for the industry to change the frame structure), the CHATUE algorithm achieves lower BER than that with block transmission with GI, because lower rate (strong) code for error protection can be used by utilizing the time-duration made available by eliminating the GI. In addition, by combining the proposed structure with a simple rate-1 doped accumulator, further BER improvement exhibiting clear turbo cliff can be achieved. A sister paper (a Part-2 paper) applies the proposed CHATUE algorithm to single carrier frequency division multiple access systems Hui et al. (Wirel Pers Commun, 2011).
Nissinen, Ilkka; Kostamovaara, Juha
The noise and jitter characteristics of an on-chip voltage reference-locked ring oscillator used in the time-to-digital converter (TDC) of the integrated receiver of a pulsed time-of-flight laser rangefinder are presented. The frequency of the ring oscillator, 683 MHz, was locked to the on-chip voltage reference by means of a frequency-to-voltage converter, resulting in better than 90 ppm/°C stability. The noise and jitter transfer characteristics of the loop were derived, and simulations were performed to see the effects of different noise types (white and 1/f noise) on the cumulative jitter of the locked ring oscillator. Finally, these results were verified by jitter measurements performed using an integrated time-to-digital converter (TDC) fabricated on the same die (0.18 μm CMOS process). The cumulative jitter of the on-chip reference-locked ring oscillator was less than 30 ps (sigma value) over a time range of 70 ns, which made it possible to use this oscillator as the heart of a TDC when aiming at centimetre-level precision (1 cm = 67 ps) in laser ranging.
Zhou, Hui; Anwar, Khoirul; Matsumoto, Tad
The primary objective of this paper is to apply the CHATUE algorithm, presented in the Part-1 paper of this article, to multi-user Single Carrier Frequency Division Multiple Access (SC-FDMA) Systems. The CHATUE algorithm connects turbo equalizers neighboring in time in the absence of Cyclic Prefix or Guard Interval, where the latest version of the reduced complexity equalization technique, Frequency Domain Soft Cancellation Minimum Mean Square Error turbo equalization is utilized not only to mitigate the inter-carrier interference but also to eliminate the inter-block interferences from the neighboring blocks. Furthermore, doped accumulator is combined with our proposed CHATUE-SC-FDMA system. Extrinsic Information Transfer analysis is used to demonstrate the improvement in convergence property as well as to analyze the bit error rate threshold. This paper provides in detail the time-concatenated turbo equalization algorithm for SC-FDMA, referred to as CHATUE-SC-FDMA, and evaluates its performances. When deriving the algorithm, we also propose, without imposing significant performance degradation, an approximation technique to eliminate the necessity of the covariance matrix inversion.
With digital holography one can record and reconstruct real world three-dimensional (3D) objects [1,2]. The recorded interference pattern includes information about both amplitude and phase of a wavefront reflected from or transmitted through the object. However, some of the hologram capture setups pose a problem for the reliable reconstruction of quantitative phase information. This can be because the twin image or noise corrupts the reconstructed phase. In such cases it is usual that only amplitude is reconstructed and used as the basis for metrology. A focus criterion is often applied to this reconstructed amplitude to extract depth information from the sensed 3D scene [3,4]. In this paper we present an alternative technique based on applying conventional computer stereo vision algorithms to amplitude reconstructions. We show the effectiveness of our technique using digital holograms of both macroscopic and microscopic real-world 3D objects. We discuss sensitivity to the depth of field of reconstructions, and which hologram capture setups are, and which are not, suitable for the technique.
Sorsa, Aki; Isokangas, Ari; Santa-aho, Suvi; Vippola, Minnamari; Lepistö, Toivo; Leiviskä, Kauko
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Residual stresses are quantitatively predicted based on the Barkhausen noise measurement with a partial least squares regression model. The measurements are taken from two sets of case-hardened samples. The benefits of using certain feature elimination strategies prior model identification are also studied. The elimination methods applied are correlation-based elimination, uninformative variable elimination and successive projections algorithm. The results show that the best predictions are usually obtained when the successive projections algorithm is applied. The prediction accuracy of the best models found shows that partial least squares models can be successfully used for prediction of material properties based on the Barkhausen noise measurement.
Boutellier, Jani; Silvén, Olli
Dataflow languages enable describing signal processing applications in a platform independent fashion, which makes them attractive in today's multiprocessing era. RVC-CAL is a dynamic dataflow language that enables describing complex data-dependent programs such as video decoders. To this date, design automation toolchains for RVC-CAL have enabled creating workstation software, dedicated hardware and embedded application specific multiprocessor implementations out of RVC-CAL programs. However, no solution has been presented for executing RVC-CAL applications on generic embedded multiprocessing platforms. This paper presents a dataflow-based multiprocessor communication model, an architecture prototype that uses it and an automated toolchain for instantiating such a platform and the software for it. The complexity of the platform increases linearly as the number of processors is increased. The experiments in this paper use several instances of the proposed platform, with different numbers of processors. An MPEG-4 video decoder is mapped to the platform and executed on it. Benchmarks are performed on an FPGA board.
Turunen, Hanna; Väyrynen, Seppo; Lehtinen, Ulla
This paper addresses health, safety, environment and quality (HSEQ) issues, specifically on the HSEQ Assessment Procedure (AP) of a Finnish industrial network. The need for and practical application possibilities of using the HSEQ AP in the management of a port is addressed in detail. The port is situated within the northern Barents Region. The study concentrates on the information acquired from previous implementations of this AP in the supply network of the paper, chemical and steel companies (process industry) and the existing criteria and practices of evaluations using this audit-style approach. The empirical interview part of this study was conducted mainly in Northern Finland. Some information and impressions on HSEQ were also gathered during a visit to Russia's Murmansk Commercial Seaport, in the largest part of the Barents Region. The paper has its document-based and interview-based parts. The former consists of a thorough review of scientific and industrial documents and the latter refers to hearing about HSEQ issues in the field from the interviewed representatives of a maritime company network (a case). The combination of these approaches provides us with recommendations and scenarios for further consideration.
Khan, Zaheer; Lehtomäki, Janne
In distributed multichannel cognitive radio (CR) networks, autonomous CRs face competition from one another to access the potentially available channels. Efficient resource allocation in such scenarios can be achieved by carrying out negotiation among distributed CRs via a coordinator (base station) or with the help of a common control channel. While the use of a coordinator or a common control channel simplifies the problem, it may create significant signaling overhead or potential contention under heavy load. Opportunistic channel selection strategies that require no centralized coordination among the autonomous CRs are surveyed in this paper and also novel results related to our own proposed
$$\gamma $$
-persistent adaptive strategy are provided. Unlike our previous work in Khan et al. (IEEE Trans Mob Comput 12(2): 2013), we evaluate the performance of the proposed
$$\gamma $$
-persistent strategy in terms of different performance metrics such as: (1) Average throughput of an individual CR; (2) Probability of finding a channel free in first step (given that the channel is free) for an autonomous CR; and (3) Average number of unsuccessful transmissions experienced by a CR. Using these performance metrics, we compare the performance of the proposed strategy with two other distributed strategies and also with a centralized strategy. We show that the proposed strategy allows the CRs to find a free channel with high probability in the first sensing step (given that the channel is free). This reduces the overhead of multiple sensing steps incurred by an autonomous CR. The reduced number of sensing steps required to find a channel free in turn improves throughput per time slot of a CR. Moreover, the proposed strategy reduces the likelihood of unsuccessful transmissions by CRs which in turn improves throughput and also reduces the transmission attempt costs of an autonomous CR.
Jämsä, T.; Pulkkinen, P.
The assessment of osteoporotic hip fracture risk is currently based primarily on bone mineral density (BMD) measurements using dual X-ray absorptiometry (DXA). However, a growing body of evidence indicates that the method is insufficient for the accurate individual risk assessment. DXA-based BMD can provide information on the amount of bone but does not elucidate bone structure, which is important for the mechanical strength of bone and, consequently, for the risk of fracture. In order to achieve more comprehensive assessment of fracture risk, recent efforts have been placed on imaging modalities, by which the bone structural changes could be observed. In this paper, we review our recent studies, in which improved prediction of hip fracture risk has been achieved using advanced imaging of proximal Femur structure.
Silven, Olli; Jyrkkä, Kari
Computing solutions used in mobile communications equipment are similar to those in personal and mainframe computers. The key differences between the implementations at chip level are the low leakage silicon technology and lower clock frequency used in mobile devices. The hardware and software architectures, including the operating system principles, are strikingly similar, although the mobile computing systems tend to rely more on hardware accelerators. As the performance expectations of mobile devices are increasing towards the personal computer level and beyond, power efficiency is becoming a major bottleneck. So far, the improvements of the silicon processes in mobile phones have been exploited by software designers to increase functionality and to cut development time, while usage times, and energy efficiency, have been kept at levels that satisfy the customers. Here we explain some of the observed developments and consider means of improving energy efficiency. We show that both processor and software architectures have a big impact on power consumption. Properly targeted research is needed to find the means to explicitly optimize system designs for energy efficiency, rather than maximize the nominal throughputs of the processor cores used.
Ying, X.; Koivukangas, J.; Alakuijala, J.; Oikarinen, J.; Louhisalmi, Y.
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Several methods were developed in order to improve reliability and robustness of a voice interface designed for a speech activated neurosurgical workstation that is a command-number-limited system but directly involved in nurosurgical operations. We chose a commercial voice recognizer and synthesizer as basic voice environment of the voice interface. A parallel connection grammar structure in the command recognition and a practical operation procedure oriented logical structure in the command understanding were designed to remove misrecognition and misunderstanding. In the voice recognizing process, by means of setting noise pits and dynamically adjusting tolerance level, the substitution errors caused by uncorrected voice commands and noises in operating room could be greatly reduced. To guarantee the high robust voice control, we employed real-time voice feedback to confirm the accepted commands. Our testing results showed that employing these methods greatly improved voice interface robustness.
Rahkonen, Timo; Repo, Heikki
In this paper, methods for analyzing the effects of small timing errors in D/A and time-interleaved A/D converters are studied. It is shown that timing skew and slew rate in D/A converters cause broadband spurious components, but the output spectrum can in most cases be calculated simply by averaging the errors over one sample period and using FFT at the original sample rate. Also the frequency-domain effects of mismatch in time-interleaved A/D converters can be constructed by calculating the mixing transfer functions caused by the time-varying gain and timing.
Rahkonen, Timo
Boutellier, Jani; Lucarz, Christophe; Gomez, Victor Martin; Mattavelli, Marco; Silvén, Olli
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The new Reconfigurable Video Coding (RVC) standard of MPEG marks a transition in the way video coding algorithms are specified. Imperative and monolithic reference software is replaced by a collection of interconnected, concurrent functional units (FUs) that are specified with the actor-oriented CAL language. Different connections between the FUs lead to different decoders: all previous standards (MPEG-2 MP, MPEG-4 SP, AVC, SVC, …) can be built with RVC FUs. The RVC standard does not specify a schedule or scheduling heuristic for running the decoder implementations consisting of FUs. Previous work has shown a way to produce efficient quasi-static schedules for CAL actor networks. This paper discusses the mapping of RVC FUs to multiprocessor systems, utilizing quasi-static scheduling. A design space exploration tool has been developed, that maps the FUs to a multiprocessor system in order to maximize the decoder throughput. Depending on the inter-processor communication cost, the tool points out different mappings of FUs to processing elements.
Tsumura, Shigehiko; Latva-Aho, Matti; Hara, Shinsuke
Multi-carrier code division multiple access (MC-CDMA) system, which is a combination of OFDM (Orthogonal Frequency Division Multiplexing) and CDMA, is robust to hostile mobile radio environments because the receiver can effectively combine all the received signal energy scattered in the frequency domain. Moreover, MC-CDMA system can establish a quasi-synchronous transmission due to the cyclic prefix, and easily employ a multi-user detection in an uplink channel. In a multiple-cell environment, the inter-cell interfering deteriorates the performance of the MC-CDMA multi-user detection.
In this paper, utilizing VISA (VIrtual Subcarrier Assignment), we propose an inter-cell interference suppression method for an MC-CDMA uplii with a multi-user detection, where the base station can easily spatially filter in only the signals from the own cell and spatially filter out the signal from the other cells.
Boutellier, Jani; Lucarz, Christophe; Lafond, Sébastien; Gomez, Victor Martin; Mattavelli, Marco
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The upcoming Reconfigurable Video Coding (RVC) standard from MPEG (ISO / IEC SC29WG11) defines a library of coding tools to specify existing or new compressed video formats and decoders. The coding tool library has been written in a dataflow/actor-oriented language named CAL. Each coding tool (actor) can be represented with an extended finite state machine and the data communication between the tools are described as dataflow graphs. This paper proposes an approach to model the CAL actor network with Parameterized Synchronous Data Flow and to derive a quasi-static multiprocessor execution schedule for the system. In addition to proposing a scheduling approach for RVC, an extension to the well-known permutation flow shop scheduling problem that enables rapid run-time scheduling of RVC tasks, is introduced.
Guo, Yimo; Zhao, Guoying; Pietikäinen, Matti
Textures, low-level image features around all of us, can be quantified in many ways. One of the most representative methods is the Local Binary Pattern (LBP) operator. In this chapter, two texture description methods inspired by LBP are presented. They are designed in unsupervised (i.e., class labels of texture images are not available) and supervised (i.e., class labels of texture images are available) manner, respectively. First, a linear configuration model is proposed to describe microscopic image structures in an unsupervised manner, which is subsequently combined together with LBPs. This descriptor, denoted as Local Configuration Pattern (LCP), is theoretically verified to be rotation invariant and able to provide discriminative complement to the conventional LBPs. Second, in the case that class labels of training images are available, a supervised model is developed to learn discriminative patterns, which formulates the image description as an integrated three-layered model to estimate optimal pattern subset of interest by simultaneously considering the robustness, discriminative power and representation capability of features. This model can be applied to many LBP variants, such as completed local binary pattern (CLBP) and local ternary pattern (LTP).
Schaberreiter, Thomas; Bouvry, Pascal; Röning, Juha; Khadraoui, Djamel
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Critical infrastructures (CIs) provide important services to society and economy, like electricity, or communication networks to enable telephone calls and internet access. CI services are expected to provide safety and security features like data Confidentiality and Integrity as well as to ensure service Availability (CIA). The complexity and interdependency of CI services makes it hard for CI providers to guarantee those features or even to be able to monitor the CIA risk by taking into account that an incident in one CI service can cascade to another CI service due to a dependency.
This work presents a tool implementing a previously published Bayesian network based CI risk model which attempts to address the challenges of interdependent CI risk monitoring. While Bayesian networks provide a great theoretical basis for CI risk monitoring, tool support to cover the challenges in this field is missing. The tool was implemented to provide visual guidance for domain experts to generate a CI risk model from real-world CIs and to simulate/emulate risk scenarios based on this model.
Petäjäjärvi, Juha ; Mikhaylov, Konstantin; Vuohtoniemi, Risto; Karvonen, Heikki; Iinatti, Jari
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By modulating the electric field induced to a human body, it is possible to transfer data wirelessly using the body as a transmission medium. This method is referred to as human body communication (HBC), which has multiple advantages in comparison with the traditional radio frequency (RF) communication. First, it alleviates the traffic load from the radio channels, which are becoming more and more congested, as the number of connected wireless devices increases rapidly. Second, HBC can potentially provide higher security than traditional RF communication since the electric field stays in the vicinity of a human body, which makes eavesdropping more challenging. Third, the attenuation in the HBC frequency band is lower than in bands used by the other radio technologies for wireless body area networks. To improve energy efficiency in HBC, one approach is to utilize a wake-up receiver (WUR). The WUR is continuously listening for a pre-defined wake-up signal, which activates the other electric circuitry (e.g., sensing, processing, and communication). The use of WURs can significantly reduce the energy consumption and increase the lifetime of the sensing applications. In this work, we propose a superregenerative WUR solution which employs self-quenching and loose synchronization method and operating at sufficiently low (1.25 kbps) data rate in order to obtain high sensitivity while keeping the energy consumption low. This enables to achieve sensitivity of −97 dBm for 10−3 bit error rate while consuming only 40 μW. The details of the design and the performance evaluation results of the proposed solution are in the paper. Also, the paper reports the results of the practical measurements characterizing the impact of the electrode location on the path loss in an HBC channel. The presented results show that the proposed system can potentially enable communication between two any points on the body with low transmit power.
Tujkovic, Djordje
Okun, Oleg; Pietikäinen, Matti
Many image segmentation algorithms are known, but often there is an inherent obstacle in the unbiased evaluation of segmentation quality: the absence or lack of a common objective representation for segmentation results. Such a representation, known as the ground truth, is a description of what one should obtain as the result of ideal segmentation, independently of the segmentation algorithm used. The creation of ground truth is a laborious process and therefore any degree of automation is always welcome. Document image analysis is one of the areas where ground truths are employed. In this paper, we describe an automated tool called GROTTO intended to generate ground truths for skewed document images, which can be used for the performance evaluation of page segmentation algorithms. Some of these algorithms are claimed to be insensitive to skew (tilt of text lines). However, this fact is usually supported only by a visual comparison of what one obtains and what one should obtain since ground truths are mostly available for upright images, that is, those without skew. As a result, the evaluation is both subjective; that is, prone to errors, and tedious. Our tool allows users to quickly and easily produce many sufficiently accurate ground truths that can be employed in practice and therefore it facilitates automatic performance evaluation. The main idea is to utilize the ground truths available for upright images and the concept of the representative square [9] in order to produce the ground truths for skewed images. The usefulness of our tool is demonstrated through a number of experiments with real-document images of complex layout.
Ma¨ntyniemi, Antti; Rahkonen, Timo; Kostamovaara, Juha
An integrated digital CMOS time-to-digital converter with sub-gate delay LSB width and 50 ps single-shot precision σ-value has been designed and implemented for a laser range-finding application. The measurement is based on a counter and a novel two-step parallel interpolation that uses only 32 delay elements to provide 128 LSBs in the interpolator within the reference clock cycle. The circuit was fabricated in the AMS 0.8 μm CMOS process and the current consumption of the circuit is <20 mA from a single +5 V supply.
Rahkonen, Timo; Eksyma, Harri; Mäntyniemi, Antti; Repo, Heikki
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A DDS type circuit structure for producing numericallyprogrammable square wave clock signal is presented. The high speed D/Aconverter needed in conventional DDS systems is replaced by an
tap delay line time domain interpolator thateffectively increases the sampling rate by a factor of
. Thus the circuit can be used up to full clock rate withoutimage filtering. A prototype IC with clock frequency of 30 MHz, 5 bitinterpolator and SFDR of −40 dBc up to 10 MHz and −33 dBcup to 15 MHz has been designed and tested.
Liu, Jing; Xiao, Yang; Ghaboosi, Kaveh; Deng, Hongmei; Zhang, Jingyuan
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Botnets become widespread in wired and wireless networks, whereas the relevant research is still in the initial stage. In this paper, a survey of botnets is provided. We first discuss fundamental concepts of botnets, including formation and exploitation, lifecycle, and two major kinds of topologies. Several related attacks, detection, tracing, and countermeasures, are then introduced, followed by recent research work and possible future challenges.
Mafra, Samuel Baraldi; Souza, Richard Demo; Rebelatto, João Luiz; Fernandez, Evelio MG; Alves, Hirley
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We introduce an overlay cooperative cognitive radio scheme, in which the secondary network transmits only during the retransmissions of the primary network. The secondary network makes use of multiple relays in order to increase its performance compared to a non-cooperative scenario. Moreover, the secondary operates without harming the performance of the primary network. Different cooperative protocols are employed and associated with hybrid automatic repeat request mechanisms. Our results show that the incremental decode-and-forward technique allows the secondary network to achieve the highest throughput among the considered methods, at the cost of a very small degradation in the performance of the primary network.
Okun, Oleg; Priisalu, Helen
Linear and unsupervised dimensionality reduction via matrix factorization with nonnegativity constraints is studied. Because of these constraints, it stands apart from other linear dimensionality reduction methods. Here we explore nonnegative matrix factorization in combination with three nearest-neighbor classifiers for protein fold recognition. Since typically matrix factorization is iteratively done, convergence, can be slow. To speed up convergence, we perform feature scaling (normalization) prior to the beginning of iterations. This results in a significantly (more than 11 times) faster algorithm. Justification of why it happens is provided. Another modification of the standard nonnegative matrix factorization algorithm is concerned with combining two known techniques for mapping unseen data. This operation is typically necessary before classifying the data in low-dimensional space. Combining two mapping techniques can yield better accuracy than using either technique alone. The gains, however, depend on the state of the random number generator used for initialization of iterations, a classifier, and its parameters. In particular, when employing the best out of three classifiers and reducing the original dimensionality by around 30%, these gains can reach more than 4%, compared to the classification in the original, high-dimensional space.
Vehkaperä, M.; Tujkovic, D.; Li, Z.; Juntti, M.
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Future wireless communication systems will require high data-rates in multiuser environments. Multicarrier code-division multiple-access (MC-CDMA) has emerged as an attractive technique for broadband communications, offering efficient utilization of bandwidth and robust performance in multipath channels. In this paper, coded downlink MC-CDMA is combined with the concept of LST architectures. Suboptimal receiver with soft co-antenna interference (CAI) cancellation is utilized and the performance of the system is evaluated in frequency-flat and frequency-selective fading channels. The results demonstrate that by using multiple-input multiple-output (MIMO) antenna system with coded LST transmission and iterative detection and decoding (IDD) at the receiver, the throughput and error rate performance can be significantly improved over the conventional single-input single-output (SISO) system.
Brandenburg, Axel; Käpylä, Petri J.; Mohammed, Amjed
Three-dimensional turbulence simulations are used to show that the turbulent root mean square velocity is an upper bound of the speed of turbulent diffusion. There is a close analogy to magnetic diffusion where the maximum diffusion speed is the speed of light. Mathematically, this is caused by the inclusion of the Faraday displacement current which ensures that causality is obeyed. In turbulent diffusion, a term similar to the displacement current emerges quite naturally when the minimal tau approximation is used. Simulations confirm the presence of such a term and give a quantitative measure of its relative importance.
Pylkkänen, J.
The efficient production should have short and precise lead times, small batch sizes and zero defects. The parts and subassemblies of a product are produced directly to the assembly section by means of just on time. High flexibility, availability and capability are required for and FMS an its subsystems. One important subsystem of an FMS, tool management system, is discussed in this paper.
Laitinen, Erkki; Lapin, Alexander
Iterative solution methods for a class of finite-dimensional constrained saddle point problems are developed. These problems arise if variational inequalities and minimization problems are solved with the help of mixed finite element statements involving primal and dual variables. In the paper, we suggest several new approaches to the construction of saddle point problems and present convergence results for the iteration methods. Numerical results confirm the theoretical analysis.
Joshi, Satya Krishna; Codreanu, Marian; Latva-aho, Matti
29 Citations
We provide distributed algorithms for the radio resource allocation problem in multicell downlink multi-input single-output systems. Specifically, the problems of (1) minimizing total transmit power subject to signal-to-interference-plus-noise ratio (SINR) constraints of each user and (2) SINR balancing subject to total transmit power constraints are considered. We propose a consensus-based distributed algorithm and the fast solution method via alternating the direction method of multipliers. First, we derive a distributed algorithm for minimization of total transmit power. Then, in conjunction with the bracketing method, a distributed algorithm for SINR balancing is derived. Numerical results show that the proposed distributed algorithms achieve the optimal centralized solution.
Hall, Ernest L.; Roning, Juha
Machine vision has moved from the research laboratory to the factoryfloor in the past five years. A new machine vision industry has emerged which has a several hundred million dollar per year market and tens of thousands of potential applications. Not only is 100% inspection becoming a reality but new concepts such as in-place inspection rather than post-process inspection are being used to improve product quality. Much of the reason for this phenomenal growth is due to the use of robust algorithms and innovative architectures in machine vision systems.
Chen, X. H.; Oksman, J.
The code sensingR3 code protocol designed for wireless data networks is proposed and its performance is analysed in this paper. The communication between two terminals is initiated by hand-shaking packets (the REQ and ACK packets), followed by data packet transmission. The destructive collisions among terminals are avoided by utilising busy code sensing and chip-rate division multiple access (CRDMA) techniques in transmissions of the REQ packet and the data packet (or ACK packet). A two-dimensional continuous-time Markov model is used to analyse the behaviour of the network. Analytical results are given which show that a remarkable improvement in throughput-delay performance can be achieved by the proposed protocol when compared to those for other reported protocols.
Määttä, Juho; Bräysy, Timo
Multiradio wireless mesh network (WMN) is a feasible choice for several applications, as routers with multiple network interface cards have become cheaper. Routing in any network has a great impact on the overall network performance, thus a routing protocol or algorithm for WMN should be carefully designed taking into account the specific characteristics of the network. In addition, in wireless networks, serious unfairness can occur between users if the issue is not addressed in the network protocols or algorithms. In this paper, we are proposing a novel centralized routing algorithm, called Subscriber Aware Fair Routing in WMN (SAFARI), for multiradio WMN that assures fairness, leads to a feasible scheduling, and does not collapse the aggregate network throughput with a strict fairness criterion. We show that our protocol is feasible and practical, and exhaustive simulations show that the performance is improved compared to traditional routing algorithms.
Zhou, Jiehan; Sun, Junzhao; Athukorala, Kumaripaba; Wijekoon, Dinesh; Ylianttila, Mika
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Pervasive Social Computing is a novel collective paradigm, derived from pervasive computing, social media, social networking, social signal processing, etc. This paper reviews Pervasive Social Computing as an integrated computing environment, which promises to augment five facets of human intelligence: physical environment awareness, behavior awareness, community awareness, interaction awareness, and content awareness. Reviews of related studies are given, and their generic architectures are designed. The resulting architecture for Pervasive Social Computing is presented. A prototype is developed and examined, in order to investigate the characteristics exhibited by Pervasive Social Computing.
Holm, Jana; Zinchenko, Ganna; Lassi, Ulla; Hernoux-Villière, Audrey; Kärkkäinen, Johanna
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The main goal of this research is the enzyme-catalyzed conversion of fibre sludge into reducing sugars, which can further be transformed into higher alcohol biofuels by fermentation. Enzymatic hydrolysis of 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) pretreated fibre sludge demonstrated that this cellulose-rich waste fraction can be successfully converted into reducing sugars. The organic material content of this fibre sludge was determined to be about 80 %. The relative yields of total reducing sugars (glucose) in this study were higher (maximum >95 %) compared with our earlier studies (34 %) of the same pretreatment procedure followed by acid hydrolysis and enzymatic hydrolysis. Due to the ionic liquid used in this study, we were able to recover 85 % (compared with 50 %) of the initial dry fibre sludge with [AMIM]Cl pretreatment.
Ou, Zhonghong; Harjula, Erkki; Koskela, Timo; Ylianttila, Mika
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Hierarchical Distributed Hash Table (DHT) architectures have been among the most interesting research topics since the birth of flat DHT architecture. However, most of the previous work has merely focused on the two-tier hierarchy. In this paper, we study and analyze General Truncated Pyramid Peer-to-Peer (GTPP) architecture, the generalized version of Partially Vertical Hierarchical Architecture (PV-HA). The idea is to study whether added tiers of hierarchy can provide added value in performance and functionality. Through mathematical analysis, we demonstrate performance results in comparison to flat architecture, which helps understanding the typical characteristics of hierarchical architectures. Firstly, GTPP has slightly higher expected lookup hop count, although it can be decreased with optimizing the sub-overlay setup. However, GTPP significantly decreases the expected lookup routing latency. Secondly, GTPP has clearer and more reasonable traffic distribution among all the peers from different tiers of sub-overlays, and can work with slightly lower maintenance traffic. Thirdly, our studies indicate that two to three tiers are most suitable in most cases for GTPP, considering all the parameters.
Korhonen, Esa; Kostamovaara, Juha
It has recently shown how a constant dc offset between two low-quality test signals can be used to test the integral nonlinearity (INL) of A/D converters (ADCs) without an accurate test stimulus, and how the same method can be used to test the INL of D/A converters (DACs) as well. We propose here an on-chip offset generator for producing the constant offset and analyse its limitations. Experimental tests on the 122 × 22 μm2 offset generator fabricated in 130 nm CMOS process show that it can be used to test the INL of 12-b DACs and ADCs. The generator is rail-to-rail capable so that almost the whole input/output range of converters can be tested. Moreover, if the proposed offset generator is used in a ratiometric test setup as proposed here as well, the influence of a reference voltage drift on measurement accuracy is cancelled out. Because of its small size, simple design, rail-to-rail capability and immunity to reference voltage changes, the proposed offset generator is well suited for built-in self-test usage.
Ruotsalainen, Tarmo; Kostamovaara, Juha; Rankinen, Riitta
A low-noise low-pass amplifier channel designed for telecommunications is described. The channel has an 80-kHz corner frequency and total dynamic range of 94 dB. To achieve the high dynamic range, the amplifier channel is constructed with a BiCMOS process and a relative high supply voltage of ±8V is used. To further increase the dynamic range, the baseband amplifier has two branches, a low gain (A = 29 dB) and a high gain (A = 73 dB) branch, comprising a common continuous-time preamplifier and separate antialias filters, switchedcapacitor filters, and postamplifiers. Differential signal processing is used to reduce the effect of common-mode disturbances.
Hannu, Jari; Saikkonen, Teuvo; Häkkinen, Juha; Karttunen, Juha; Moilanen, Markku
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Remote testing requires embedded test infrastructure, consisting of communication, test control and test access. This article presents an embedded test solution for a low-frequency audio board. Supporting analog testing, the solution consists of a measurement and calculation method for passive component characterization, analog test bus solution and an embedded test controller for controlling embedded tests and providing test stimuli. Moreover, the solution, which supports the presented test plan, was compared to a test plan supporting traditional testing. It was found that the embedded test solution provided a 29% test coverage of the audio board components and substituted flying probe testing included in the traditional test plan. Besides such benefits as improved fault diagnostics and lower manufacturing costs, the paper also discusses the drawbacks of the presented solution, including reduced measurement accuracy. This paper also presents a correction to a previously presented passive component measurement and calculation method.
Suliman, Isameldin M.; Lehtomäki, Janne; Umebayashi, Kenta
Spectrum sensing plays a significant role in enabling utilization of spectrum holes by unlicensed secondary users (SUs) in cognitive radio networks (CRNs). Most of the related work concerning spectrum sensing has focused on sensing carried out by incoming secondary users (SUs) aiming at locating spectrum opportunities. However, in order to appropriately protect returning licensed primary users (PUs), SUs should continuously perform spectrum sensing during their ongoing transmissions. An important issue associated with the continuous sensing is the false alarm rate (FAR), which is defined as the average number of false alarms per unit of time and can be modeled by a Poisson process with Poisson parameter λFAR. In this paper, we address this issue and develop a continuous time Markov chain (CTMC)-based analytical model to evaluate the effect of the false alarm rate on the performance of CRNs. A major feature of the proposed analytical framework is that it takes into account the effects of sensing errors by both incoming SUs looking for free channels to transmit on and the already transmitting SUs expecting the presence of returning PUs. The analytical model also examines the interference tolerance among PUs and SUs as well as the impact of SUs residual self-interference. The performance results show that high λFAR can severely degrade PUs performance and reduce the overall system resource utilization. However, with increasing PU interference tolerance, PUs performance improves as well. SU residual interference was found to decrease the detection probability resulting in a low PU performance. Extensive simulations validate the analytical model, demonstrating excellent agreement with the theoretical results.
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