A layer composite of plastic material forms a retroreflector and includes at least one transparent structure layer, a protective layer and a reflection layer enclosed at the common interface between the structure layer and the protection layer. A relief structure formed by substantially identically shaped three-dimensional structure elements is formed in the reflection layer. At their base surfaces the structure elements are of lateral dimensions in the range of between 1 μm and 100 μm. The structure elements have side faces which are covered by the reflection layer and which include an angle of inclination of 45°, with a free surface of the layer composite. The relief structure is additively superimposed with a microstructure in at least one surface element. The microstructure has a preferred direction and influences the quality of the reflection action of the layer composite. The retroreflector is suitable for the production of machine-readable optical markings.

Retroreflectors are used as reflective devices for marking articles and persons, the surface or clothing respectively of which greatly absorbs light and is therefore difficult to see in the dark, for example at night, even when strong lighting is involved. The retroreflectors are provided with reflective surfaces which are enclosed in a layer composite and are applied by means of adhesive for example to predetermined surfaces. In that way retroreflectors enhance the visibility of for example building barriers, optical markings, bicycles, motor vehicles and so forth.
Reference is made in this respect to U.S. Pat. No. 3,712,706 disclosing a retroreflector in which a relief structure is composed of reflective tetrahedron elements in the form of corner cubes. Production of the relief structure with the periodically arranged tetrahedron elements is effected by cutting three sets of parallel, V-shaped grooves into the surface of a metal master plate, by means of a diamond tool. The three sets with the parallel, V-shaped grooves intersect at predetermined angles in such a way that the surface of the metal master plate has the relief structure formed from the periodically arranged tetrahedron elements. Retroreflectors of that kind reflect incident light in a narrow spatial angle centered around the direction of the incident light. An increase in the angle of the reflected light is effected by diffraction of the light at the relief structure.
WO 00/43813 describes a retroreflector which in substance corresponds to U.S. Pat. No. 3,712,706 as just discussed above. Chips or small portions of such retroreflectors can be added as a pigment to a lacquer. An article which is coated with such a lacquer has a strongly reflective surface.
U.S. Pat. No. 1,671,086 provides the teaching of not excessively polishing the reflective surfaces of the retroreflector with the typical cube edge, so that the reflected light can be scattered at the minor irregularities in the reflective surfaces of the retroreflector. The parallel light beam which is incident on the retroreflector is reflected and is returned in a cone with the incident light beam as the axis in a symmetrical condition in expanding relationship back to the light source.
Attention may be directed here to DE 44 29 683 C1 describing a triple reflector which is a body formed from structure elements, each of which is of a shape delimited by three reflective square faces. The three faces form a surface which corresponds to the cube surface which is visible in the direction of the cube diagonals. The three faces of each structure element can be slightly curved inwardly in the manner of a hollow mirror and may have a grooving so that the triple reflector reflects the incident parallel light beam back to the light source in divergent relationship.
Reference may also be made to U.S. Pat. No. 4,588,258 and U.S. Pat. No. 4,938,563 in which shaping the relief structure of a retroreflector in a flexible film material, by virtue of the small thickness of material involved, necessarily results in microscopically small lateral dimensions of the elements of the relief structure and consequently affords strong light diffraction effects. Minor asymmetries in the relief structure, which incline the axes of the tetrahedron elements through a few degrees of angle out of the normal direction, reduce the scatter of the reflected light. U.S. Pat. No. 4,938,563 more specifically refers to the possibility of influencing divergence or scatter of the reflected light by suitably arranging the tetrahedron elements, of differing asymmetrical nature, within the relief structure.
DE 696 19 691 T2 provides that the retroreflectors can be improved by a diffraction structure which is superimposed on the relief structure and which imparts to the reflected light a color which is dependent on the spatial frequency of the diffraction structure, without the use of colored pigments.
A summary of materials which are suitable for the production of layer composite material for retroreflectors is to be found in U.S. Pat. No. 4,856,857.
It will be appreciated that retroreflectors are readily commercially available. An aspect in common to such retroreflectors is that it is not possible to derive any conclusions about the orientation of the retroreflector from the reflected light.


A method of constructing an electronic circuit assembly comprises forming a circuit board having first and second sets of circuit layers and an internal optically transmissive layer, sandwiched between the first and second sets of circuit layers. Holes are formed through the first set of circuit layers by excimer laser drilling, the holes extending as far as the optically transmissive layer without passing through that layer. Electronic devices are mounted on the circuit board over said holes, at least some of the devices including optical receiver and/or transmitter means for receiving/transmitting optical signals from/to the optically transmissive layer. An optical fibre is coupled to the optically transmissive layer. The optically transmissive layer thus acts as a bus interconnecting the devices.

This invention relates to electronic circuit assemblies.
It is well known to transmit data signals by way of optical fibres. Optical transmission has the advantage of high bandwidth and high clock rates, while providing electrical isolation between transmitter and receiver.
Conventionally, when optical data is received by a circuit assembly, it is converted into electrical signals, and these electrical signals are then routed by way of printed circuit tracks to individual devices (chips) in the assembly. Because the clock rate of the optical data is very high, it is usually necessary to provide a serial/parallel conversion, to reduce the clock rate of the electrical signals.
The object of the invention is to provide an improved electronic circuit assembly in which optical signals are handled in a novel and more efficient manner.

Electronic circuit board with internal optically transmissive layer forming optical bus


A machine for processing continuous glucose monitoring data and issuing an alert if hypoglycemia is imminent has three modules: (a) a pre-processing module that receives and modulates continuous glucose monitoring data by reducing noise and adjusting for missed data points and shifts due to calibration; (b) a core algorithm module that receives data from the pre-processing module and calculates a rate of change to make a hypoglycemia prediction, and determine if hypoglycemia is imminent; and (c) an alarm mode module that receives data from the core algorithm and issues an audio or visual alert or warning message or a negative feedback signal to an insulin delivery device if hypoglycemia is imminent.

Diabetes is a chronic disease only controlled by constant vigilance. Chronic elevations, and likely fluctuations, of the blood glucose may result in long term complications (blindness, kidney failure, heart disease, and lower extremity amputations). Perversely, attempts at normalizing glucose concentrations also increases the risk of serious health issues related to hypoglycemia. Despite the use of insulin infusion pumps and programs that promote intensive diabetes management, the average Alc (an indicator of long-term blood glucose control) reported by major diabetes treatment centers remains higher than 8%, well above the recommended goal of 6.5-7%. Many factors contribute to this failure:    1) the difficulties in correctly estimating the amount of carbohydrates in a meal,    2) missed meal boluses, and    3) anxiety about anticipated hypoglycemia, resulting in patients giving themselves less insulin, especially overnight.
It has always been difficult to achieve compliance with complicated medical regimens, such as the administration of insulin three or more times a day. As long as diabetes treatment demands constant direct intervention, the vast majority of people with diabetes will not meet treatment goals. An expanding area of research addressing diabetes is working on developing automated closed loop systems that integrates glucose readings and insulin delivery without the on-going active intervention of the patient—an "artificial pancreas".
We have developed an automated closed-loop system that contains a subcutaneous continuous glucose monitor and a subcutaneous insulin delivery pump for type 1 diabetes patients. These two components are connected by a control algorithm using data from the glucose sensor to determine the appropriate insulin delivery. We use a health monitoring system (HMS) algorithm that adds an independent safety layer to the overall system. The HMS analyzes CGM data and CGM trends in anticipation of impending hypoglycemia. The HMS issues electronic, visual and/or audio alerts in response to impending hypoglycemia (e.g. within 15 minutes), such as on the AP device screen, with a request for the investigator to intervene and treat the subject, e.g. with 16 g carbohydrate. A secondary alert may be sent as a text message, such as to the clinical team, that hypoglycemia is predicted and may also suggest taking outside action, such as eating carbohydrates, in order to prevent hypoglycemia.

The Regents of the University of California


A system for controllably positioning printed circuit boards or the like for the automatic drilling of holes therein. A plurality of individual work positions is provided, together with corresponding work carrier plates having individual or groups of circuit boards affixed thereto. Each work position includes a work table, a drilling machine with associated control equipment, a carrier plate for the circuit boards, and means for supporting the carrier plate and circuit boards above the work table with minimal resistance to lateral movement of the carrier plate and boards. The carrier plates are tied to a central drive system controlled by an automatic control unit in a manner which rigidly maintains close tolerances to lateral movement while permitting vertical displacement relative to the work tables. A master table is included for the drilling of a master template and to prevent displacement errors in the holes to be drilled. The drilling machines employed in the system may be independently activated in accordance with the quantity of production and the number of work positions needed in any given hole drilling operation and incorporate various interlocked fail-safe mechanism, some of which are individually adjustable, to simplify the construction and operation of the system while insuring coordinated control of the plurality of drilling machines.

1. Field of the Invention
This invention relates to a system for automatically positioning a workpiece in a machining operation at a succession of coordinate points in an X-Y coordinate plane and, more particularly, to a system for automatically positioning a plurality of printed circuit boards and drilling holes therein under the control of an automatic control unit.
2. Description of the Prior Art
Printed circuit boards are widely used in the electronics field and in related technologies. Such printed circuit boards are typically laminated of at least a substrate layer and one or more layers of copper. The boards are customarily drilled with holes for the insertion of various electrical components to be mounted on the boards. The holes must be drilled, not punched, in a controlled fashion to limit damage to the areas surrounding the holes and to avoid smearing between layers. Each circuit board with typically have a relatively large number of holes to be drilled through it.
It will therefore be recognized that the drilling of holes in printed circuits is a tedious and time-consuming task. Various systems have been devised in order to automate the procedure. A plurality of boards may be mounted in a single work station for drilling simultaneously. Numerically controlled drill-positioning systems are in present use commercially, employing a tape-driven control unit in conjunction with a movable drill head which repeats the drilling operation at the various positions to which it is directed by the control unit. The tape fed into the control unit contains the program indicating the number and position of holes to be drilled in the circuit board. However, such a system is necessarily restrictive in the number of circuit boards which can be processed in a given time period since for quality production only a few boards can be stacked together for simultaneous drilling. The use of a control unit for each station increases the cost of the drilling system, and the mechanism for positioning the drill is not only expensive to provide on a per-unit basis but is complex and prone to breakdown.
Other types of automatic positioning systems for the automatic drilling of holes in printed circuit boards which eliminate the need for control by a tape driven control unit are known. An example of such a system which uses a master template and a photocell, hole-location system is disclosed in the Marantette et al U.S. Pat. No. 3,532,893. However, while eliminating the need for the expensive and complex tape-driven control unit of the first type of system described hereinabove, systems of this type depend upon a plurality of servo devices for positioning the boards at the respective work positions, thus necessarily introducing a factor of cost from the replication of such items at multiple work positions. Moreover, such systems are subject to their own position error problems, particularly the photo detection systems which rely on a null signal for determining the selected position for drilling.
A system is desired which is responsive to an automatic control unit driven by a paper tape or the like so as to develop the precision in position location which is possible from the use of stepping motors but without the associated cost which is necessarily involved where such a control unit is required for each hole drilling machine. If a plurality of hole drilling machines could be controlled from a single control unit with the precision which is required in such an operation, the cost per work position could be reduced by spreading the control unit cast over the number of work positions employed, thus reducing the cost of drilling the holes, and the rate of production of drilling circuit boards could be increased, since more circuit boards would be drilled at the same time. I have devised such a system.

Hole drilling machine and work positioning system


Exemplary embodiments of the present disclosure are directed towards a system and method for processing virtual objects in a computing environment. The method includes hiding a plurality of virtual objects at a plurality of user navigating virtual locations. The hided plurality of virtual objects is dynamically generated in response to the plurality of user navigating virtual locations associated with a plurality corresponding real-time locations. The method includes collecting the dynamically generated plurality of virtual objects by a user and dynamically generates the plurality of virtual objects at the plurality of user navigating virtual locations. The user enabled to use a plurality of virtual game objects for collecting the plurality of dynamically generated virtual objects within the plurality of user navigating virtual locations. The method further includes offering a plurality of virtual rewards to the user based on the collection of plurality of virtual objects within the plurality of user navigating virtual locations and the offer plurality of virtual rewards configured to be processed for participating in an uber hunt. The method further includes solving a plurality of interactive queries by using the plurality of virtual rewards for participating in the uber hunt. An uber virtual object in the uber hunt configured to provide a higher level reward to the user once the uber virtual object collected.

Computer-based and/or electronic gaming systems provide a shared virtual environment for many users to interact in a virtual world. The users can interact in the virtual environment and achieve various game objectives. Virtual treasure hunts are a well-known form of entertainment enjoyed by users of all ages. In a typical virtual treasure hunt game a player or players follow a series of clues that lead them to the treasures. A player's general location is verified by determining which page-base station is receiving the player's pager signal and the subsequent clues given only when the player is in the correct general location. However, many drawbacks of using means to determine the location, including inaccuracy and the requirement that the game be played on a scale of sufficient size such that players travel to differing base station coverage areas.
Accordingly, there is need to provide the players with more dynamic and engaging means beyond those conventionally available and allow interactions between the players and the map-based game board.
In the light of aforementioned discussion there exists a need for certain systems with novel methodologies that would overcome or ameliorate the above mentioned disadvantages.

System and method for processing virtual objects in a computing environment


The present invention relates to a process for co-gasification of two or more carbonaceous feedstock, said process comprising combusting a first carbonaceous feedstock having high calorific value with low ash and high hydrogen content, to produce a heated effluent; carrying the heated effluent to second reactor where the heated effluent reacts with a second carbonaceous feedstock, having low calorific value with high ash and low hydrogen content, to produce synthesis gas. The present invention also relates to an apparatus for co-gasification of two or more carbonaceous feedstock, comprising a first reactor (3), having a first feedstock inlet port (1), a oxygen or air inlet port (2), a steam inlet port (9), a ash removal port (7), and a solid recycle port (6); a first cyclone separator (5) connected to the first reactor (3) through a first cyclone separator inlet port (4); a second reactor (16), having a second feedstock inlet port (10), and a ash removal port (15), the second reactor is connected to the first cyclone separator (5) through a gaseous inlet port (8); and a second cyclone separator (12), having a fine particles removal port (13), and an effluent port (14), wherein the second cyclone separator is connected to the second reactor through a second cyclone separator inlet port (11).

Gasification is a partial oxidation process wherein carbon feedstock are converted into CO and H2 (often known as synthesis gas) in presence of steam and oxygen. These reactions occur typically above 800 degree C. High reaction temperatures and steam partial pressures are often preferred for maximizing H2 production. Currently there are three major types of gasification systems. These are Entrained bed, fluidized bed and Moving bed gasifiers. The entrained bed system operates at temperatures above 1250 degree C., while in fluid bed and moving bed gasifiers the temperatures are normally below 1100 degree C. Accordingly, the solids residence time is much higher in these systems.
Though all gasification systems convert solid carbonaceous material into gaseous form, choosing gasifier configuration based on the properties of feedstock can result in improved operational performance and higher conversion efficiency. For example, high ash coals are often advantageously gasified in moving bed systems to achieve higher cold gas efficiencies. Similarly, petroleum coke is typically gasified in entrained beds to overcome the reactivity issues at low temperatures. Also the size of the particles used in these gasifiers differs significantly to suit the flow pattern and operating conditions employed in the gasifier. Similarly in entrained bed gasifiers the temperatures are typically maintained above the ash fusion temperatures. Therefore physical properties like grindability index, ash melting temperatures etc play important role in deciding optimal gasifier choice.
The syn gas quality and its calorific value are the vital issues of gasification, which is mainly governed by the type of feedstock used and operating conditions employed. Since feedstock plays an important role, several studies focused on co-processing of coal, pet coke, biomass, heavy liquids etc. However, co processing two or more types of feedstocks in a single gasifier configuration can be inefficient compared to co processing in multi stage gasifier configuration as single system can not exploit all the beneficial characteristics of the feed.
The idea of gasifying carbonaceous material in different stages has been reported in many patents and patent applications. However, most of these technologies utilize two stage systems for increasing the carbon conversion by converting the unconverted carbon of first stage in the second stage or emphasize on effectively removing tar from gasification system. U.S. Pat. No. 7,740,672, discloses a two stage gasifier wherein the two stages of the gasifier are connected to a cyclone separator in between and the cold gas efficiency of the effluent gases is expected to be around 90%.
U.S. Pat. No. 4,872,886 discloses a two stage gasification process where a part of the coal feed is reacted in the presence of steam and in an oxygen rich environment to produce syngas at a very high temperature. This hot syngas is then contacted with a second part of coal slurry where further gasification reaction takes place. Unconverted coal is recycled back to the first stage for combustion. By doing this high calorific value syngas is generated with minimum energy loss. This increases the overall efficiency of the process. But this process only discloses the gasification of a single feedstock in two stages. In second stage the unconverted feedstock get reacted with the syn gas produced in the first stage to give synthesis gas.
U.S. Pat. No. 7,503,945 describes a two stage gasification process wherein the solid effluents coming out of the first stage gasifier are combusted in an ash reactor. The hot gases coming out of the ash reactor is fed to a cyclone separator wherein sufficient amount of ash particles are allowed to pass along with gas effluent which in turn mixes with the gaseous effluent of the first stage. By doing this tar coming out of the first stage is being picked up by ash and taken to the ash reactor.
The idea of supplying the heat for carrying out endothermic gasification reaction using the sensible heat of steam has been disclosed in WO2009145724. This application discloses a two step gasification process for converting carbonaceous feedstock into gaseous syngas by supplying sensible heat from external sources.
None of these two stage processes discuss the preferential combustion in case of co-gasification of two or more carbonaceous feedstocks. United States patent application 2010/146856 suggests carrying out gasification in two zones through preferential gasification of high calorific material in zone 1 and low calorific material in zone 2. However, this invention does not teach any optimum scheme for reduced oxygen consumption while handling feedstock with differing ash, hydrogen and calorific content. Hydrogen rich feedstocks such as methane, petroleum residue consume less oxygen and release higher amount of gasification reactants such as H2O and CO2. The feedstock that are rich in hydrogen are high in H/C ratio, hence produces more stoichiometric H2O during combustion than hydrogen lean feedstock. As the kinetics of steam gasification are much faster than the CO2 gasification, preferential combustion of high hydrogen content feeds enables faster kinetic environment for carbon conversion. Further, if the oxygen supply is limited to the extent of gasification conditions, the calorific content of the fuel is not fully available for driving the endothermic gasification reactions. This is because under high temperature conditions both CO and CO2 are produced leading to less enthalpy release as energy is locked in the form of CO and H2. H2 is produced from CO and H2O through shift reaction. As a result the mixed temperatures achieved while co-gasification are lower. Therefore stoichiometric gasification of high calorific value fuel is not optimal for creating high temperature, steam rich gasification environment.
Ash content in the feed consumes significant energy which is often wasted in the form of heat of fusion or sensible heat. This is more so when combustion is carried out in a separate reactor where the scope for sensible heat transfer from ash is limited. In contrast, when low ash feedstocks are burnt the temperature rise is much higher due to absence of high ash levels. As a result all the energy can be efficiently captured in the form of high enthalpy stream mainly consisting of H2O and CO2.
Further, the advantages of segregated treatment are not fully exploited as these feedstocks are completely mixed in a single reactor system.
To improve the system further, the present invention includes preferential combustion of a carbonaceous material which has higher calorific content preferably higher hydrogen and low ash content calorific value in a reactor and transferring this energy using steam for driving the gasification of lower calorific value ash rich and hydrogen lean carbonaceous feed in a separate reactor. More particularly, the present invention relates to a two stage gasification system and process for simultaneous or co-gasification of two or more carbonaceous feedstock.

Process for co-gasification of two or more carbonaceous feedstocks and apparatus thereof


A continuous loop roll towel dispenser actuated by pulling on the loop of toweling with the hands is shown in which the next user can dispense a fresh segment of towel without contacting the used towel portion.

This invention relates to roll web dispensers and more particularly to continuous roll towel dispensers in which a portion of the dispensed web is grasped by the hands of the user to actuate the dispensing of a clean unused length of web material.
Continuous roll towel dispensers in which a loop of towel material is fed out of a slot adjacent the front bottom edge of the dispenser and returned into the dispenser through a rear slot have been known for many years. Generally the user of these devices would grasp the edges of the front of the loop adjacent the top of the loop as it exits the dispenser slot and pull down to dispense a clean unused portion of towel. Depending on the extent of usage of the exposed loop by the prior user a person grasping the towel edges to dispense a clean portion may contact the used portion of the towel with the undesired effect of possible contamination from the prior user.
Over the years various attempts have been made to present to a subsequent user a clean portion of towel to be grasped for the purpose of dispensing a full length of clean unused towel. These have involved sophisticated powered devices, time delay releases, retracter mechanisms and the like which sometimes malfunction. U.S. Pat. No. 5,820,231 shows a dispenser of this type in which the used towel is retracted into the dispenser housing and a blister like downward protrusion of the cabinet is used to hold the edges of a clean portion of towel away from the cabinet bottom so the next user may grasp clean towel to pull out a length sufficient to dry the hands. This is an expensive and complicated way to try and ensure the next user does not grasp used towel to dispense a clean portion. None of the prior art has successfully addressed this problem in a simple and economical fashion.
Accordingly it an object of the present invention to provide a simple effective presentation of clean unused towel to a new user for actuation of the dispenser by pulling down on the towel loop with out having to use previously used towel.
It is another object of the invention to prevent ordinary use of a portion of the clean unused towel dispensed by a user for the next user to grasp to dispense another unused length of towel.
It is yet another object of the invention to prevent contact with the used towel and surfaces touched thereby by a user triggering the dispensing of a clean unused towel segment.
It is a further object of the present invention to provide a shield adjacent the clean towel dispensing slot to inhibit hand contact with the extreme upper portion of dispensed towel.
It is a still further object of the invention to provide a shield with apertures at the edges of the dispensed towel web to allow a subsequent user to grasp clean unused towel.
These and other and further objects are achieved in an embodiment of the invention in which a tab is extended downwardly from the front edge of the clean towel dispensing slot a distance sufficient to provide a clean segment of towel for a subsequent user to grasp through apertures at the ends thereof to dispense a new length of unused towel without having to contact the used towel.


A glass-plastic laminated lens blank, and a molding assembly for providing such a blank by direct casting, are described, wherein the incidence of blank shaling fracture is reduced by an edge configuration which transfers the high bond stress present in the laminate from the flawed edge of the glass core to a point in the core interior which is flaw-free.

The present invention is in the field of glass-plastic composites, and particularly relates to glass-plastic laminated blanks for optical and ophthalmic lenses which resist shaling fracture during lamination and finishing processes.
It has been proposed to provide laminated articles comprising glass and plastic layers which could combine the desirable properties of both plastics and glasses, e.g., the lightweight and toughness of plastics and the scratch resistance or light-responsive characteristics of glasses. For example, German Auslegeschrift No. 1,284,588 by Gliemeroth describes laminated articles comprising plastic and photochromic glass layers which could be used to provide glass-plastic laminated lenses exhibiting photochromic properties.
A particularly desirable glass-plastic laminate for optical and ophthalmic applications is a laminate comprising a thin sheet glass core element composed, for example, of photochromic glass, which is positioned between two relatively thick plastic surface layers which are bonded to the front and back surfaces of the glass core and substantially cover the front and back surfaces thereof. Such a laminate combines the very desirable properties of photochromic behavior and light weight. These laminates may be produced by the high-temperature lamination of the glass and plastic components using preformed plastic and glass sheet or by directly casting plastic resins against the glass core and curing to form the covering surface layers. The copending, commonly assigned application of S. T. Gulati et al., Ser. No. 018,107, filed Mar. 7, 1979, describes direct-cast laminated glass-plastic lenses.
One problem which has been encountered in the manufacture of laminated glass-plastic lens blanks by these processes has been the shaling fracture of the glass core which can occur as the laminated lens blank is cooled to room temperature after processing, or as it is subsequently handled and finished. The opposing plastic front and back surface layer elements, to which the glass core is strongly bonded, exhibit substantial shrinkage with respect to the glass as the laminate is cooled to room temperature following processing. This shrinkage exerts considerable tensile stress on the core, referred to as bond stress because it is in a direction normal to the glass-plastic bonding plane at the outer circumferential edge of the glass core. In the presence of this stress, midplane or shaling fracture of the glass core can be initiated by any surface defect present on the core edge. The end result is separation of the lens blank into the two plastic surface layers, each retaining a portion of the glass core layer bonded thereto.
It is a principal object of the present invention to provide a novel configuration for a laminated glass-plastic lens blank comprising a thin glass core, which lens blank exhibits improved resistance to shaling fracture of the glass core during manufacture and subsequent handling of the lens blank.
Other objects and advantages of the invention will become apparent from the following description thereof.

Composite glass-plastic lens blanks resistant to shaling fracture


A method for spectrum recovery in spectral decoding of an audio signal, comprises obtaining of an initial set of spectral coefficients representing the audio signal, and determining a transition frequency. The transition frequency is adapted to a spectral content of the audio signal. Spectral holes in the initial set of spectral coefficients below the transition frequency are noise filled and the initial set of spectral coefficients are bandwidth extended above the transition frequency. Decoders and encoders being arranged for performing part of or the entire method are also illustrated.

When audio signals are to be stored and/or transmitted, a standard approach today is to code the audio signals into a digital representation according to different schemes. In order to save storage and/or transmission capacity, it is a general wish to reduce the size of the digital representation needed to allow reconstruction of the audio signals with sufficient quality. The trade-off between size of the coded signal and signal quality depends on the actual application.
Transform based audio coders compress audio signals by quantizing the transform coefficients. For enabling low bitrates, quantizers might concentrate the available bits on the most energetic and perceptually relevant coefficients and transmit only those, leaving "spectral holes" of unquantized coefficients in the frequency spectrum.
The so-called SBR (Spectral Band Replication) technology, see e.g. 3GPP TS 26.404 V6.0.0 (2004-09), "Enhanced aacPlus general audio codec-encoder SBR part (Release 6)", 2004 [1], closes the gap between the band-limited signal of a conventional perceptual coder and the audible bandwidth of approximately 15 kHz. The general idea behind SBR is to recreate the missing high frequency contents of a decoded signal in a perceptually accurate manner. The frequencies above 15 kHz are less important from a psychoacoustic point of view, but may also be reconstructed. However, SBR cannot be used as a standalone codec. It always operates, in conjunction with a conventional waveform codec, a so-called core codec. The core codec is responsible for transmitting the lower part of the original spectrum while the SBR-decoder, which is mainly a post-process to the conventional waveform decoder, reconstructs the non-transmitted frequency range. The spectral values of the high band are not transmitted directly as in conventional codecs. The combined system offers a coding gain superior to the gain of the core codec alone.
The SBR methodology relies on the definition of a fixed transition frequency between a low band, encoded perceptually relevant low frequencies, and a high band, not encoded less relevant high frequencies. However, in practice, this transition frequency relies on the audio content of the original signal. In other words, from one signal to another, the appropriate transition frequency can vary a lot. This is for instance the case when comparing clean speech and full-band music signals.
The "spectral holes" of the decoded spectrum can be divided in two kinds. The first one is small holes at lower frequencies due to the effect of instantaneous masking, see e.g. J. D. Johnston, "Estimation of Perceptual Entropy Using Noise Masking Criteria", Proc. ICASSP, pp. 2524-2527, May 1988[2]. The second one is larger holes at high frequencies resulting from the saturation by the absolute threshold of hearing and the addition of masking [2]. The SBR mainly concerns the second kind.
Moreover, a typical audio codec based on such method which aims at filling the "spectral hole", i.e. not encoded coefficients, for the high frequencies, i.e. the second kind of "spectral holes", should preferably be able to fill the spectral holes over the whole spectrum. Indeed, even if a SBR codec is able to deliver a full bandwidth audio signal, the reconstructed high frequencies will not mask the annoying artifacts introduced by the coding, i.e. quantization, of the low band, i.e. the perceptually relevant low frequencies.

Adaptive transition frequency between noise fill and bandwidth extension


A method and circuit for implementing a level shifter with built-in-logic function for reduced delay. The circuit including at least one set of inputs from a first power supply domain. The circuit further including at least two cross coupled field effect transistors (FETs) connected to a second power supply domain. The circuit further including a true logic gate connected to the first power supply domain and the at least two cross coupled FETs. The true logic gate being configured to generate a logic function based on the at least one set of inputs. The circuit further including a complementary logic gate connected to the first power supply domain and the at least two cross coupled FETs. The complementary logic gate being configured to generate a complement of the logic function based on the at least one set of inputs.

In a multi-voltage system, integration of more than one type of integrated circuit (IC) in a functional system is common. Consequently, there is a necessity for a level shifter circuit that is configured to shift the voltage level at the output of one IC to the voltage level at the input of another IC. For example, the output of an IC that operates at a higher voltage level may be provided to another IC that operates at a lower voltage level. In this instance, the voltage needs to be ramped down to a lower level. Similarly, when the output of an IC that operates at a lower voltage level is input to an IC that has a higher operating voltage, the voltage needs to be ramped up.
A limitation of a conventional level shifter with embedded logic is that the level shifter and corresponding logic are typically designed between the multi-voltage ICs in a cascading relationship such that there is unnecessary delay added to the ICs. For example, conventionally a first supply voltage domain is input into a level shifter from a first IC, the level shifter outputs a second supply voltage domain different from the first supply voltage domain, the second supply voltage domain may be input into the logic (e.g., true logic) as a signal, and subsequently the logic acquires a function based on the input second supply voltage domain, which is input into a second IC. Thus, there is unnecessary delay added to the IC because initially the level shifter is configured to ramp up or down the first supply voltage domain to the second supply voltage domain (e.g., introducing a first delay), and subsequently, the logic is configured to acquire a function using the second supply voltage domain provided by the level shifter (e.g., introducing a second delay).
In view of the foregoing, there is a need for a level shifter circuit that supports a voltage level shifting function as well as a built-in-logic function without leading to extra delay in the ICs in comparison to a cascaded system. Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.

Level shifter with built-in logic function for reduced delay

International Business Machines Corporation


A digital subscriber loop interface unit, connected to a digital subscriber loop, includes an echo canceler for carrying out a echo canceling operation, a decision feedback equalizer for carrying out an equalizing operation, and a transversal filter, provided in at least one of the echo canceler and the decision feedback equalizer, in which a plurality of taps among all taps are grouped into groups, each group including a predetermined number of taps continuously arranged, a single tap coefficient being assigned to the taps in each group. A digital subscriber loop interface unit may include an echo canceler for carrying out a echo canceling operation by using a value obtained by adding +1 to a symbol value represented by a 2B1Q code. Further, the echo canceler may have a jitter echo canceler in which a convolution operation is carried out by using a value obtained by adding +1 to a symbol value represented by the 2B1Q code, the tap coefficient used in the convolution operation is changed in accordance with a time elapsing from occurrence of the jitter. Furthermore, a digital subscriber loop interface unit may have a low-pass filter in which a filter coefficient is changed based on whether the decision feedback equalizer is in or after a pull-in step.

(1) Field of the Invention
The present invention generally relates to a digital subscriber loop interface unit, and more particularly to a digital subscriber loop interface transmitting and receiving information represented by the 2B1Q codes.
(2) Description of the Related Art
In a case where a digital subscriber loop interface unit transmits digital signals represented by the 2B1Q codes using a twisted pair cable like an existing telephone subscriber loop, each transmission path code symbol is one of four values +3, +1, -1, and -3. In addition, for example, a baud rate of 80 kHz is selected as the transmission rate. In such a digital subscriber loop interface unit using the 2B1Q codes, it is required to effectively carry out an echo canceling process and an equalizing process for the input signals.
A conventional digital subscriber loop interface unit using the 2B1Q codes are formed, for example, as shown in FIG. 1. Referring to FIG. 1, the digital subscriber loop interface unit has a hybrid circuit (HYB) 102 connected to a subscriber loop 101, an analog-to-digital converter (A/D) 103, a high pass filter (HPF) 104, an AGC amplifier (AGC) 105, a low pass filter (LPF) 106, a decision feedback equalizer 109. The decision feedback equalizer 109 is formed of a discriminator (DEC) 107 and a transversal equalizer (EQL) 108. The digital subscriber also has a driver (DV) 110, an echo canceler 111 and a digital-to-analog converter (D/A) 115. The echo canceler 111 has a linear echo canceler (LEC) 112, a non-linear echo canceler (NEC) 113 and a jitter echo canceler (JEC) 114.
A transmission signal S(n) is converted, by the digital-to-analog converter 115, into an analog signal having an amplitude which is one of values .+-.3 and .+-.1. The analog signal is supplied from the driver 110 to the subscriber loop 101 via the hybrid circuit 102. A received signal from the subscriber loop 101 is supplied to the analog-to-digital converter 103 via the hybrid circuit 102 so as to be converted into a digital signal in accordance with, for example, an over-sampling analog-to-digital converting technique in the analog-to-digital converter 103. The wave-shaping and the elimination of low-frequency components are then carried out by the high pass filter 104.
Echo components of the received signal is removed from the received signal by the echo canceler 111. The received signal is amplified by the AGC amplifier 105 so as to have a predetermined level and is supplied to the decision feedback equalizer (DFE) 109 via the low pass filter 106. The decision feedback equalizer (DFE) 102 removes inter-symbol interference from the received signal so that data is reproduced.
In a case where the AMI (Alternate Mark Inversion) codes which do not includes DC components are used as transmission codes, even if the hybrid circuit 102 is formed of a hybrid transformer cutting off the DC components, wave form distortion does not occur. On the other hand, in a case where the 2B1Q codes including DC components, if the DC component is cut of the by the hybrid transformer of the hybrid circuit 102, the wave form distortion occurs. As a result, an impulse response shows a characteristic having a long tail. Thus, it is required to increase the number of taps of each of transversal filters in the echo canceler 111 and the decision feedback equalizer 109. In the transversal filter having a large number of taps, the size thereof is large and a large amount of processing is needed so that the dissipation power is increased.
To reduce a degree of the long tail in the impulse response, it is thinkable that the inductance of the hybrid transformer is increased so that the attenuation of the low frequency components is as smaller as possible. However, the hybrid transformer is made larger, so that problems of the cost and volume occur.
Thus, as shown in FIG. 2, it has been known that a primary recursive filter (an IIR filter (Infinite Impulse Response filter)) 121 is added to the transversal filter. Referring to FIG. 2, the transversal filter has a plurality of delay elements (D), multipliers (.times.) and an adder (.SIGMA.) 120. Each of the delay elements (D) delays an input signal by a delay time corresponding to the baud rate. The primary recursive filter 121 has a adder (+), a multiplier (.times.) and a delay element (D). At respective taps each of which is between adjacent delay elements (D), symbols P(n)-P(n-M-1) sampled at sampling times n-(n-M-1) are obtained. The respective taps are connected to the multipliers (.times.), so that the multipliers (.times.) respectively multiplies the symbols P(n)-P(n-M) by tap coefficients CE.sub.1 -CE.sub.M. Multiplying signals output from the multipliers (.times.) are supplied to the adder (.SIGMA.) 120 and added to each other. The symbol P(n-M-1) sampled at the sampling time (n-M-1) and a tap coefficient CE.sub.M+1 are multiplied by the multiplier (.times.), and the multiplying signal is supplied to the primary recursive filter 121. An output signal of the primary recursive filter 121 is added to an adding output signal from the adder (.SIGMA.) 120 by an adder (+). A adding result at the adder (+) is obtained as an equalizing output signal y(n). The tap coefficient CE.sub.M+1 and an attenuation factor are supplied, as parameters, to the primary recursive filter 121. The attenuation factor corresponding to the long tail of the impulse response is equal to or greater than 0.95 and is less than 1.
FIG. 3 shows a unit in which an updating circuit for updating the tap coefficients to be supplied to the transversal filter is added to the circuit shown in FIG. 2. In FIG. 3, those parts which are the same those shown in FIG. 2 are given the same reference numbers. Referring to FIG. 3, an equalizing error signal k.multidot.e(n), obtained by multiplying an error signal e(n) at a sampling time n and a step size k, is supplied to the transversal filter. The symbol P(n) of the received signal at the sampling time n is successively delayed by the delay elements (D) serially connected to each other. The output signals at the respective taps each of which is between adjacent delay elements (D) are multiplied by the equalizing error signal k.multidot.e(n). Each of the multiplying signals is added to a tap coefficient delayed by one period of sampling time, and the adding result is multiplied, one of tap coefficient CE.sub.1 -CE.sub.M+1, by the signal at each tap.
FIG. 4 shows an impulse response of the received signal. In FIG. 4, the axis of ordinate represents an amplitude and the axis of abscissa represents a baud rate time. In addition, a continuous line represents an impulse response in a case where the hybrid transformer has a large inductance, and a dotted line represents an impulse response in a case where the hybrid transformer has a small inductance. Since the hybrid transformer cuts off DC components, the tail of the impulse response generally becomes long. For example, in the case where the hybrid transformer has a large inductance, as indicated by the continuous line, the impulse response proceeds to an attenuation characteristic from a time corresponding to about eighteen taps. On the other hand, in the case where the hybrid transformer has a small inductance, as indicated by the dotted line, the impulse response proceeds to an attenuation characteristic from a time corresponding to about thirty taps.
Referring to the impulse responses indicated by the continuous line and the dotted line in FIG. 4, in the case where the hybrid transformer has the small inductance, the time from which the impulse response proceeds to the attenuation characteristic is delayed in comparison with in the case where the hybrid transformer has the large inductance. As a result, the tail of the impulse response in the case where the hybrid transformer has the small inductance is longer than the tail of the impulse response in the case where the hybrid transformer has the large inductance. In addition, the primary recursive filter 121 acts on a region in which the impulse response is exponentially attenuated. Thus, in the case the hybrid transformer having the small inductance is used, the number of taps located previous to the primary recursive filter 121 must be greater than the number of taps in the case where the hybrid transformer having the large inductance is used.
FIG. 5 shows essential parts of a conventional decision feedback equalizer. Referring to FIG. 5, the decision feedback equalizer has a plurality of delay elements (D), an adder (.SIGMA.) 130, a discriminator 131, adders (+) and multipliers (.times.). Each of the delay elements (D) delays an input signal by a delay time corresponding to the baud rate. When a received signal x(n) is supplied to the decision feedback equalizer, the decision feedback equalizer outputs a received symbol P(n). An equalizing error signal e(n) is generated and the a feedback error signal k.multidot.e(n) is made by using the equalizing error signal e(n).
Received symbols P(n-1)-P(n-N) are respectively multiplied by tap coefficients Cd.sub.1 -Cd.sub.N, and the multiplying signals are added to each other by the adder 130. The adding result is output as an equaling signal y(n) from the adder 130. The equalizing signal y(n) is subtracted from the received signal x(n) so that the received signal x(n) is equalized. The equalized signal is supplied to the discriminator 131, and the discriminating result obtained by the discriminator 131 is used as the received symbol P(n). The decision feedback equalizer is applicable to various types of transmission apparatuses other than the digital subscriber loop interface unit.
In the decision feedback equalizer, a symbol value (A) is multiplied by a tap coefficient (B), and a number (C) is added to the multiplying result. In this case, one of values .+-.3 and .+-.1 is multiplied, as the symbol value (A), by the tap coefficient. Thus, the above calculating process can be carried out by using a 3-inputs adder and a shifter. In addition, it has been known that, in processes in a high pass filter and a low pass filter, a received signal having a plurality of bits and a filter coefficient are multiplied by each other using a shifting process in which the filter coefficient represented by an exponent of "2" is shifted.
In the decision feedback equalizer and the echo canceler in the digital subscriber loop interface unit, the total number of taps is fifty or more. A multiplying process and an adding process must be performed for each tap. Thus, the large number of processes is needed. To simplify processes, the following technique has been proposed (e.g. U.S. Pat. No. 4,926,472).
"+1" is added to each of four kinds of symbol values .+-.3 and .+-.1 of the 2B1Q code so that new four kinds of symbol values 4, 2, 0 and -2 (2.sup.2, 2.sup.1, 0, -2.sup.1) are obtained. According to a set of the new four kinds of symbol values, a process for each tap can be performed by using a 2-inputs adder and a shifter. A set of these new symbol values are referred to, for example, as a "symbol value +1".
Essential parts of a conventional decision feedback equalizer using the "symbol value +1" are shown in FIG. 6. In FIG. 6, those parts which are the same as those shown in FIG. 5 are given the same reference numbers. Referring to FIG. 6, "1" is added to a received symbol P(n) which is discriminated by the discriminator 131 so that the symbol values .+-.3 and .+-.1 of the 2B1Q code is converted into symbol values 4, 2, 0 and -2. A DC (direct-current) correction part 132 corrects a difference between results of operations using the symbol values 4, 2, 0, and -2 obtained by adding +1 to the original symbol values .+-.3 and .+-.1 of the 2B1Q code and results of operations using the original symbol values of the 2B1Q, the operations including a convolution operation and an updating operation of the tap coefficients.
When a j-th tap coefficient, an equalizing error signal and a symbol value at a sampling time n are respectively represented by Cd.sub.j (n), e(n) and P(n), the j-th tap coefficient Cd.sub.j (n+1) at a sampling time (n+1) is represented as follows. EQU Cd.sub.j (n+1)=Cd.sub.j (n)+k.multidot.e(n).multidot.[P(n-j)+1](1)
In addition, the relationship between a tap coefficient Dd(n) at the sampling time n and a tap coefficient Dd(n+1) at the sampling time (n+1), in the DC correction part 132, is represented as follows. EQU Dd(n+1)=Dd(n)+k.multidot.e(n) (2)
FIG. 7 shows a conventional jitter echo canceler in a case where the high pass filter has three taps. Referring to FIG. 7, the jitter echo canceler has an adder (.SIGMA.) 140, switches 141.sub.1 -141.sub.M, delay elements (D) and multipliers (.times.). The symbol P(n) and tap coefficients CJ.sub.11 -CJ.sub.M3 are supplied to this jitter echo canceler.
When insertion or deletion of pulses is performed to obtain a phase locked state in a DPLL (digital phase lock loop), received sampling point is varied. After this, an echo wave form is distorted for a while. To deal with the distortion of the echo wave form, the jitter echo canceler is provided in the digital subscriber loop interface unit. After jitter occurs to cancel the distortion of the echo wave form caused by the variation of sampling points, the convolution operation is performed using all the taps. After this, the switches 141.sub.1 -141.sub.M are controlled so that the number of taps applied to the convolution operation is decreased one by one. That is, the echo of a transmission code output before the jitter occurs is returned after the jitter has occurred (after the sampling time is changed), and the value of the echo differs from the value of the echo obtained in a case of no jitter since the sampling time is changed. To correct this difference, the jitter echo canceler is operated in addition to the linear echo canceler and the non-linear echo canceler.
Then, after the jitter has occurred, the transmission signal is transmitted in synchronism with new sampling times, so that the echo of the transmission signal output after the jitter has occurred is corrected by only the linear echo canceler and the non-linear echo canceler.
The output of the jitter echo canceler is a function of the transmission code S(n), and the impulse response is at an approximately constant value after I periods have elapsed from a time at which the jitter has occurred. The output of the jitter echo canceler is obtained by carrying out the convolution operation until the variation of the amplitude cased by changing the sampling time is out for M periods. That is, the output y(I) obtained after the I periods had elapsed from the time at which the jitter has occurred is represented as follows. EQU y(I)=[.SIGMA..sub.j=I.sup.M {CJ.sub.Ij .multidot.S(I-j)}].multidot.jdr(3)
In the above equation, .SIGMA..sub.j =I.sup.M means an adding operation from j=I to j=M, that is, indicates the convolution operation. The number I of periods falls within a rage 1-M (1, 2, . . . , and M), and "jdr" represents a direction of the jitter and has 1 or-1. The value of the "jdr" is determined as 1 or -1 based on whether, in the DPLL circuit (not shown in figures), the pulse insertion is performed to advance the sampling phase or the pulse deletion is performed to delay the sampling phase. S(I-j) represents the transmission code as a function of the number I of periods which have elapsed, and S(1) represents the transmission code immediately after the jitter has occurred.
The tap coefficient CJ.sub.Ij is represented as a function of the number I of periods, because the high pass filter formed of the transversal filter is provided at a front end of the jitter echo canceler. For example, in a case where the jitter occurs at a time n, the echo related to the transmission code previous to the P(n-1) is affected by changing the sampling time. However, even if the echo is related to the transmission code previous to P(n-1), signals which have been already stored in the delay elements in the high pass filter are not affected. Thus, until the signals are output from the high pass filter, the tap coefficients of the jitter echo canceler are not constant, and after this, the tap coefficients becomes constant. Thus, when representing the number of taps of the transversal filter forming the high pass filter as K, the tap coefficient CJ.sub.Ij is constant in a rage of I.gtoreq.K.
In an example of the conventional jitter echo canceler shown in FIG. 7, the number K of the taps of the high pass filter is set at 3. The switches 141.sub.1 -141.sub.M are switched as shown in FIG. 7 at a time corresponding to the period I=1. Thus, the tap coefficients CJ.sub.11 -Cj.sub.M1 are supplied to this jitter echo canceler. In the next period I=2, the tap coefficients CJ.sub.22 -CJ.sub.M2 are supplied thereto. In the period I=3, the tap coefficients CJ.sub.33 -CJ.sub.M3 are supplied thereto, and in the period I=4, the tap coefficients CJ.sub.43 -CJ.sub.M3 are supplied to this jitter echo canceler.
The updating equation, corresponding to the equation (3), for the tap coefficient is represented as follows. EQU CJ.sub.Ij (I+1)=CJ.sub.Ij (I)+k.multidot.e(n).multidot.S(I-j).multidot.jdr(4)
In a rage of I.gtoreq.K, EQU CJ.sub.Ij =CJ.sub.Kj ( 5)
stands, where K is the number of taps of the high pass filter.
In the digital subscriber loop interface unit shown in FIG. 1, the low pass filter 106 at the front end of the decision feedback equalizer 109 forms a wave of post-cursor portion after the main pulse. Hereinafter the low pass filter 106 is referred to as a post-cursor equalizer. The transfer function of this post-cursor equalizer can be represented by EQU 1/(1-a.multidot.z.sup.-). (6)
The filter coefficient a is equal to zero (a=0) when the cable length is minimum, and the filter coefficient a is equal to 0.75 (a=0.75) when the cable length is maximum.
It can be determined, based on the gain of the AGC amplifier 105, whether or not the cable length is large or small. When the cable length is large, the received signal is attenuated. Thus, the AGC amplifier 105 amplifies the received signal with a large gain. On the other hand, when the cable length is small, the received signal is not almost attenuated, so that the AGC amplifier 105 amplifies the received signal with a small gain. Thus, in accordance with the gain of the AGC amplifier 105, the filter coefficient a of the post-cursor equalizer is changed. In a case where the above post-cursor equalizer is used, there is a problem in that a pull-in time (a time required to obtain a signal converging on a stable state) in a case of using a long cable may be greater than that in a case of using a short cable. Because the gain of the AGC amplifier is large in use of the long cable as has been described above, noise components are also enlarged so that a noise error becomes large, the pull-in time may be large.
The problem of the long pull-in time may also depend on the difference between the main pulse forms in use of the long cable and in use of the short cable. the impulse response at the output of the low pass filter 106 is shown in FIG. 18. In the case where the length of the cable is large, the half width of the main pulse is greater than the baud rate period T, as shown in FIG. 18(a). On the other hand, in the case where the length of the cable is small, the half of the main pulse is less than the baud rate period T, as shown in FIG. 18(b). Due to changing the parameter a of the high pass filter 104, the half width of the main pulse can be close to th baud rate period T. However, the parameter of the high pass filter 104 is set at a value so that the whole post-cursor portion of the impulse response, rather than the width of the main pulse, has a pulse amplitude in post-cursor range as small as possible. Thus, when the length of the cable is large as has been described above, the half width of the main pulse in the impulse response is large.
The sampling phase is generally not constant at start of the pull-in operation, so that the optimum sampling phase is searched for by moving the sampling point in a time axis in the phase extracting circuit (not shown in figures). According to an algorithm of the decision feedback equalizer, the main-cursor (the main response) corresponds to an amplitude at a sampling time at which the maximum value is obtained among a plurality of sampling values sampled every baud rate period T. The pre-cursor corresponds to an amplitude at a time previous by T to the sampling time at which the main-cursor is obtained. The sampling phase corresponding to the pre-cursor is normally determined at zero. The post-cursor corresponds to an amplitude at each of times delaying from the main-cursor by nT where n represents positive integers. For example, in FIG. 8(a) and (b), the pre-cursor is zero and sampling points a1 and b1 delaying from the precursor by the period T is the optimum phases for the pull-in process.
The sampling points a1 and a3 are separated by the period T, and the amplitudes at the sampling points a1 and a3 are equal to each other. The sampling points b1 and b3 has the same relationships as the sampling points a1 and a3. In this case, if the pull-in process starts from a sampling phase which is prior to the optimum sampling points a1 and b1 and after the sampling points a2 and b2, a value at a sampling point further previous by the period T to each of the sampling points a2 and b2 is negative. Thus, a phase control is carried out so that the sampling phase is delayed. On the other hand, if the pull-in process starts from a sampling phase which is after the optimum sampling points a1 and b1 and prior to the sampling points a3 and b3, a value at a sampling point previous by the period T to each of the sampling points a3 and b3 is positive. Thus, a phase control is carried out so that the sampling phase advances. Thus, in both the case, the phase control is carried out so that the sampling phase is brought close to each of the optimum sampling points a1 and b1. However, in a case where the main pulse is wide, the difference between the amplitude at each of the sampling points a2 and a3 and the amplitude at the optimum sampling point a1 is small, so that both the amplitudes are large in a wide range. As a result, it is not clear which amplitude corresponds to the main response. Thus, the pull-in time is increased.
In a case shown in FIG. 8(b), the amplitude at each of the sampling points b2 and b3 is less than the amplitude at the optimum sampling point b1. If sampling points are slightly moved from the phases including the sampling points b2 and b3, the amplitude at one sampling point is much larger than the amplitude at another sampling point. As a result, it is clear which sampling point corresponds to the main pulse. Thus, the pull-in time can be short.
In concrete terms, in the case where the length of the cable is large, the frequency at which decision errors occur in initial step of the pull-in process in the decision feedback equalizer is lager than the frequency at which the decision errors occur in the case where the length of the cable is short. Thus, a long time is required to obtain right tap coefficients in the coefficient updating operation represented by the equation (1).
In the conventional digital subscriber loop interface unit formed as shown in FIG. 1, the 2B1Q code is used for the transmission of information. Since the hybrid circuit 102 is formed of the hybrid transformer, the transmission characteristic depends on the impedance of each of the hybrid transformers in both the transmitting side unit and the receiving side unit. Thus, even if the recursive filter is used, the number of taps of each of the echo canceler 111 and the decision feedback equalizer 109 must be twenty four or more. That is, the recursive filter is used only as aid.
In a subscriber side of the digital subscriber loop interface unit, after the pull-in process in the echo canceler 111 is completed by using the transmission signal to be transmitted to a destination, the taps of the echo canceler 111 are fixed. The pull-in process in the decision feedback equalizer 109 is then performed using the received signal. In the switching unit side, the transmission timing is fixed, so that the sampling phase must be synchronized with the timing of the received signal. Thus, the sneak time of the echo can not be fixed. As a result, in the pull-in process, the number of taps of both the echo canceler 111 and the decision feedback equalizer must be simultaneously updated.
In this case, if the tap coefficients are updated using the "symbol value +1" as the symbol in both the echo canceler 111 and the decision feedback equalizer 109, there is a case where the pull-in is incomplete. This is caused by using the same error in both the echo canceler 111 and the decision feedback equalizer 109. In general, each tap coefficient is calculated by based on the correlation between the symbol P(n-j) +1 and the error e(n) as indicated by the equation (1). In the echo canceler 111, the tap coefficients are obtained by using the transmission symbol, and in the decision feedback equalizer 109, the tap coefficients are obtained by using symbols reproduced from the received signals. That is, the tap coefficients are separately obtained in the echo canceler 111 and the decision feedback equalizer 109.
However, the value of the DC correction part indicated by the equation (2) depends on only the error e(n). When the pull-in processes in the echo canceler 111 and the decision feedback equalizer 109 are simultaneously performed using the same error e(n), the respective DC correction parts performs the same process. As a result, in the respective the echo canceler 111 and the decision feedback equalizer 109, the correction of DC components required by them are not always performed.
In addition, the echo canceler 111 has the non-linear echo canceler 113 which functions as the DC correction part. As a result, the echo canceler 111 may not be provided with the DC correction part. On the other hand, in the decision feedback equalizer 109, since the DC component are not ignored, the decision feedback equalizer 109 must be provided with the DC correction part for correcting the DC components.
As has been described above, in a case where both the echo canceler 111 and the decision feedback equalizer 109 carries out the convolution operation and the updating operation of the tap coefficient using the "symbol value +1", both the echo canceler 111 and the decision feedback equalizer 109 are in a state where there is substantially the DC correction part. Thus, in an initial state and/or in an step size, the tap coefficients are updated so that the non-linear echo canceler 113 corrects DC components which should be corrected by the DC correction part of the decision feedback equalizer 109. As a result, the tap coefficients reach limited value, and the non-linear echo canceler 113 can not perform the correction of non-linear components to be processed. In this case, the pull-in may be incomplete.
The tap coefficients of the transversal transformer of the decision feedback equalizer 109 correspond to the post-cursor portion of the impulse response, but the transversal transformer has no tap coefficients corresponding to the pre-cursor and the main-cursor. If the value of the DC correction part is limited to an item corresponding to the post-cursor (the value of the DC correction part is the sum of coefficients of only the post-cursor portion, and is close to "1" not close to zero.), the calculation of [(the value of the main-cursor).times.(the symbol value P(n)] must be performed when the error is calculated. As a result, the number of calculations can not be decreased.
If the term corresponding to the main-cursor is considered as the DC correction part, the value of the DC correction part is close to zero. In this case, the error e(n) is obtained in accordance with a calculation [(the main-cursor value Cd.sub.0).times.(the new symbol P(n)+1)]. As a result, the number of calculation is not increased. However, in this case, the control of the pull-in is complex. For example, before the pull-in of the tap coefficients in the decision feedback equalizer 109 is performed, the tap coefficient Cd.sub.0 corresponding to the main-cursor is calculated in a state where the tap coefficient corresponding to the post-cursor in the decision feedback equalizer 109 is maintained at zero. The AGC gain is then determined so that the calculated tap coefficient Cd.sub.0 falls within a predetermined range. If this AGC process is performed, since the coefficient value Cd.sub.0 corresponding to the main-cursor is not zero, the DC correction part can not be zero. The value of the DC correction part obtained when the AGC process is completed is approximately the same as the value of the main-cursor so as to be greatly different from zero. After this, the pull-in of the tap coefficient in the decision feedback equalizer 109 is performed. When the tap coefficient corresponding to the post-cursor is close to the final value, the DC correction part is gradually varied to a value close to zero.
As has been described above, the DC correction part in the decision feedback equalizer 109 has a large value once in the pull-in process, and is then varied so as to return to zero. Since the coefficient varies complexly as this, the step size must be filly controlled. As a result, the control is complex and the time required for the pull-in process is long.
Although the linear echo canceler 112 has about thirty taps, the jitter echo canceler 114 forming a part of the echo canceler 111 has the number of taps falling within 7-9. The convolution range is varied with elapsing time, so that the tap coefficients are not constant. Thus, even if the "symbol value +1" is applied to the jitter echo canceler 114, the DC correction part which is unchangeable with time can not respond to the "symbol value +1". That is, the "symbol value +1" can not be applied to the conventional jitter echo canceler 114.
The characteristics of the post-cursor equalizer (the low-pass filter 106) is selected so that the post-cursor portion of the impulse response, that is, the tail of the impulse response has a predetermined shape. Thus, if the cable is long, the emphasis of the high frequency components is insufficient so that the main pulse expands. As a result, the probability that an error occurs in the decision feedback equalizer 109 immediately after the pull-in process starts is increased, and the time required for the pull-in process is long.


The invention provides a polymer composition comprising from 50 wt % to 99.9 wt % polymer, from 0.1 wt % to 10 wt % nanocellulose as a first nucleating agent, and from 0.01 wt % to 5 wt % of a second nucleating agent. In some embodiments, the polymer is polylactide, the first nucleating agent is lignin-containing nanocellulose, and the second nucleating agent is a sulfur-containing, oxygenated aromatic molecule. The oxygenated aromatic molecule may be an aromatic sulfonic acid or salt, such as dimethyl 5-sulfoisophthalate. In other embodiments, the sulfur-containing, oxygenated aromatic molecule is lignosulfonic acid. Other variations provide a polymer composition comprising polymer, lignin-containing nanocellulose as a dispersing agent, and additives selected from nucleating agents, compatibilizers, plasticizers, fillers, antioxidants, colorants, or flame retardants. Other variations provide a polymer nucleating agent comprising lignin-containing nanocellulose and a sulfur-containing, oxygenated aromatic molecule. This may be a nucleating agent for polylactide, polycaprolactone, polyhydroxybutyrate, polyethylene, or polypropylene, for example.

Renewable bio-based polymers and composites derived from natural resources are generating_great interest due to depleting fossil fuel resources and the negative environmental impact of fossil fuel-based plastic products. Many bio-based polymers have been developed which show great potential for different applications; however, processing and_physical properties of these polymers are still not sufficient for many end-user applications. The poor processing and physical properties of these polymers can generally be attributed to low molecular weight, low crystallinity, and high moisture uptake. Improving the processability and physical properties of sustainable bio-based polymers is essential to make them suitable for different end-user applications. For example, polylactide is one of the most important bio-based polymers and it shows great potential in packaging, drug delivery, and biological scaffolds applications. However, the mechanical and processing properties of polylactide alone is not adequate for many of these applications. Crystallization increases the mechanical properties of the polymer.
Polylactide polymers (PLA, sometimes referred to as polylactic acid) are of increasing interest because they can be prepared from annually renewable resources such as corn sugars rather than oil or natural gas feedstocks. PLA resins are also capable of degrading rapidly under some composting conditions to regenerate carbon dioxide. The ability to compost these materials can provide more disposal options for these resins, compared to most other organic polymers. As a result, PLA resins are finding uses in a variety of packaging applications. These packaging applications include a variety of rigid and semi-rigid articles such as clamshell containers, deli and other food service trays and bottles. These packaging products are made mainly by extruding a sheet of the PLA resin and then thermoforming it.
PLA has certain characteristics which greatly affect how it is processed and the types of end-products that can be made from it. For example, the glass transition temperature (Tg) of PLA is only about 60° C., which is significantly lower than those of commonly available, high-volume polymers that have use temperatures such that during use they are in the glassy state. This low Tg means that parts made from PLA resins tend not to be very heat-resistant, as even moderately elevated temperatures are sufficient to induce a phase transition and soften the polymer.
One way to improve the heat resistance of a PLA resin is to partially crystallize it. A very significant improvement in heat resistance is seen when 20 J/g or more of crystallinity is induced in a PLA article. This can be done by annealing the part between the Tg and the crystalline melting temperature (Tm) of the resin. However, another characteristic of PLA resins is that under quiescent conditions they crystallize very slowly compared to most other common semi-crystalline polymers. This slow crystallization is a practical problem in many manufacturing processes, because the slow crystallization rates lead to very long cycle times. Equipment utilization is decreased and operating expenses are increased due to the slow crystallization rates.
Thermoforming is almost always limited to producing thin-wall articles that can be formed from a starting sheet material. Stretch blow molding processes are limited to producing certain types of hollow articles. In each case, thickness of the resulting parts is restricted. In addition, these processes are not amenable to forming complexly shaped parts.
Injection molding is a method in which thicker, more complex parts can be made. Injection molding starts with a molten polymer which is injected into the mold, and there is no simple way to stretch the polymer (to induce crystallization) within the mold in an injection molding process. Therefore, whereas crystallization is promoted by stretching the part to orient the polymer chains, crystallization must take place in an injection molding process without the benefit of stretching the part. In the injection molding process, quiescent crystallization dominates, rather than stress-induced crystallization.
Therefore, PLA resins have been injection molded, but with only limited ability to form parts which are stable at elevated temperatures. The conventional injection molding process for PLA uses a cold mold, which is at or below the glass transition temperature of the PLA resin. In order to produce reasonable cycle times, the polymer is quenched in the mold by rapidly cooling it to below its Tg, so it hardens enough to be demolded. Little crystallization can occur in this process, especially because of the inherently slow crystallization of PLA under quiescent conditions, and so the molded part is not very resistant to elevated temperatures.
If better heat resistance and mechanical properties are desired, it becomes necessary for the PLA resin to become more highly crystallized. This can be done on injection molded parts after they have been demolded, by conducting an annealing step during which the PLA resin is heated to about 70° C. to 130° C. for a period of time. This annealing step can cause the part to warp or shrink if the part is not constrained. In addition, this increases manufacturing costs substantially, and correspondingly higher equipment and energy costs are incurred. It is better to promote PLA crystallization while the part is still in the mold. This can be done by bringing the temperature of the part to 70° C. to 130° C. for a period of time before the part is demolded.
However, because PLA is inherently slow to quiescently crystallize, and because there is no possibility to stretch the polymer, it takes a long time for the part to develop the wanted crystallinity. Furthermore, the part tends to be softer at the higher temperatures needed to crystallize it within the mold, because it is kept above its Tg. This can make the part more difficult to eject, because of sticking to the mold and the possibility of distorting the part as it is removed. For these reasons, cycle times become very long in injection molding processes, if it is attempted to perform the crystallization step while the part is in the mold with conventional PLA molding compositions. PLA resins for injection molding processes generally have moderate molecular weights (such as a weight average molecular weight of 100,000 g/mol or less), to facilitate the process through a lower melt viscosity and faster crystallization rates. However, crystallization rates are still too slow to provide economically feasible cycle times.
A shorter cycle time is needed for the process to be economically viable. Various nucleating agents and plasticizers have been used in some processes, in order to increase the crystallization rate of PLA. Among these are materials such as talc, ethylene bis(stearamide), polyethylene glycol, acetyl-tributyl citrate, and tributyl citrate. These can provide various levels of improvement in manufacturing processes which require the polymer to be crystallized quiescently. However, these have not been found to reduce cycle times sufficiently, and manufacturing rates remain slow in an injection molding process. In general, these nucleating agents work for cold crystallization, in which the polymer and nucleating agent are heated to about 80-140° C. and the crystallization occurs in the solid state. It is only very rare that PLA crystalizes from the melt, even with nucleating agents.
Therefore, it is desirable to provide a PLA resin composition which can be processed rapidly in an injection molding process, to produce a crystalline or semi-crystalline molded product. Crystallization from the melt is important for injection molding, allowing short cycle times and no need to reheat the product for cold crystallization.
In addition to improved heat stability, PLA with higher crystallinity is expected to be less susceptible to hydrolytic degradation of the polymer and have better mechanical properties for some applications. It is especially desirable to provide bio-based nucleating agents for PLA.
Nucleation is important to a wide range of polymers, not just PLA. For example, nucleation is important in other biopolymers such as polycaprolactone (PCL) and polyhydroxybutyrate (PHB), among others, and non-biopolymers such as polyethylene (PE) and polypropylene (PP), among others.
Therefore, it is also desired to provide nucleating agents that are applicable across a range of polymers for which crystallization is beneficial.

Nanocellulose nucleating agents for crystallization of polylactides and other polymers

GranBio Intellectual Property Holdings, LLC


An apparatus and process for the efficient vermicomposting of organic containing wastes. A continuous thin layer of biomass is formed in which worms are established and encouraged to compost and migrate. The thinness of the biomass layer increases uniformity and allows for a higher rate of worm activity. By moving the biomass upon a conveying surface a continuous open system is created. New matter is introduced, digested and withdrawn while maintaining the active worms within a portion of the biomass. Spatial efficiency is provided by creating multiple beds in a stacked configuration.

The present invention pertains to vermiculture and vermicomposting. In particular, the present invention provides a high efficiency process and apparatus for vermiculture and vermicomposting utilizing thin beds. Worm culture, or vermiculture, can provide worms as a raw material for an animal feed ingredient, live worms for sport fishing, or for other product uses. Vermicomposting is the use of worms to break down waste materials such as livestock manures and municipal waste. Generally, worms consume inorganic and organic matter, digest and absorb largely organic matter, and pass the remainder back to the soil. As a result of their feeding behavior, worms aid in the breaking down of organic material within the material they consume. The activity of worms also ventilates the soil and promotes bacterial and other microbial decomposition processes.
Large scale vermiculture typically uses thick beds in which large quantities of organic material are worked by worms in a relatively stationary mode. Thick beds typically become stratified with regions of active worms and regions of compacted material. These compacted regions often "sour" due to anaerobic decomposition resulting in unattractive conditions for worm activity. This requires turning or "freshening" of the beds such as by introduction of bedding materials. Thick bed operation is also typically a batch process requiring manual loading of fresh biomass. After the organic material is substantially broken down, the worms and digested material must be separated and harvested.
A need exists for a method of vermicomposting which provides: 1) uniform composting with lower labor demands; 2) better control of environmental conditions; 3) consistent and higher rates of worm activity with higher composting rates; 4) easier separation of worms from digested matter; and 5) an overall more predictable worm production and vermicomposting system for steady streams of waste. The present invention provides a unique process for high efficiency vermiculture and vermicomposting.

High efficiency vermiculture process and apparatus


Systems and methods are presented for retrieving records from a database and presenting them to a user through a timely and efficient query restricting process. The query request is then modified through the use of a determined partitioning field and a modified query which partitions the field relative to a partitioning value. Records are retrieved from the database. A small set of records is presented to the user, as is a prompt to retrieve more records. An application which receives query requests determines: restricting fields, partition size and whether or not the partition is within a predetermined range. The application returns a data set and receives requests for more records. These systems and methods provide a storage efficient solution that is particularly useful for maintaining a time efficient user response for a dynamic database.

Often an organized collection of data, called a database, stores the most vital shared data accessed by computer users. The set of software that controls the organized data is called a Database Management System (DBMS). The DBMS allows data to be stored, organized, retrieved, manipulated, and reported. Many types of businesses use databases for data storage. Banks may store a record of all transactions for all account holders in a database. For instance, monthly statements of account holder transactions may be generated from data obtained from a database, listing transactions for each account holder. A library may store availability of books and the identity of a person who is checking out a number of books together with the titles checked out may be stored in a database. Hospitals may record in a database a variety of information related to patient care including, but not limited to, admission time, patient name, birth date, services performed, drugs administered, expected release date, orders and tasks.
A relational DBMS may be used as the database and represents data as being composed of a number of tables. Each table may include a number of rows and a number of columns. Rows are often referred to as records. Columns are sometimes referred to as attributes or fields. Tables as they are stored in the database may differ from tables that are generated and displayed as a collection of retrieved data. Thus it is possible to distinguish stored fields from displayed fields. In some instances displayed records are only a subset of available fields within a table. In other instances tables are joined together to display selected fields from two or more tables in one display.
Queries, or requests for information that satisfy certain specified criteria, are made of databases. Many popular systems use Structured Query Language (SQL) to form queries that are compatible with the DBMS. Different commercially available databases such as Microsoft SQL Server, Oracle, and DB2 may provide query language functions as part of a supported SQL. While the query as it is presented to the DBMS is typically compatible with the query language of the database vendor, the user software that generates the query spans a wide range of data uses, and so takes on many presentation forms. A user may write his own queries manually in SQL, or intermediate software may translate user indications of desired results into a SQL compatible query. This intermediate software may allow the unsophisticated user to form ad hoc queries or to request formatted reports that in turn get translated into one or more queries.
The trend toward less skilled users querying databases has increased as use of the Internet has proliferated in recent years. Processes that were once performed by skilled computer operators are routinely performed by a customer when a web form, which is displayed in a browser, is completed and returned. Data which is stored in a backend database server must make its way through a network of one or more intermediate servers to a client machine. Users make data requests at the client level and data is retrieved through a loop that extends to the database server.
Currently, any inefficiencies anywhere in the system when a query occurs causes delay to the end user. Users are typically not capable of understanding or mitigating poor responsiveness. Furthermore, many users require information that is current at the time data is requested by the client. For example, in a healthcare environment, medical records for patients must be provided in a timely and efficient manner to a user, such as a healthcare provider. It is unsafe in many settings, such as a healthcare environment, to provide old data, or to have an extended period with a caregiver waiting for the database to become available, finish the operation, or for data to be transferred.

This patent is subject to a terminal disclaimer.

Query restriction for timely and efficient paging