Wireless communication systems employ Multiple Input Multiple Output (MIMO) transmission and reception schemes to increase performance and the data rate of the system. A new approach for an SM-MIMO decoder that operates on the received symbols in parallel is presented. The new approach performs two different QR decompositions of the estimated channel matrix and produces two triangular matrices; one is right triangular and the other is left triangular. The modified systems of equations are processed in parallel. After each M-algorithm process has processed half of the total number of stages, total search space for the globally optimal transmitted symbol vector is reduced significantly. Finally, cumulative distance metrics are computed for the symbol sequences in the reduced search space and a global minimum is determined for the estimated transmitted symbol vector. This approach offers faster processing of the SM-MIMO signals and reduced distance metric computations and search operations.

Field of the Invention
The present invention relates generally to wireless communication systems and, more particularly, to methods and receiver architectures for decoding spatially multiplexed signals used in Multiple Input Multiple Output (MIMO) wireless communication systems.
Description of Related Art
Typically, as shown in FIG. 1, a wireless communication system comprises elements such as client terminals or mobile stations and base stations. Other network devices may also be employed, such as a mobile switching center (not shown). As illustrated, the communication path from the base station (BS) to the client terminal or mobile station (MS) is referred to herein as a downlink (DL) direction, and the communication path from the client terminal to the base station is referred to herein as an uplink (UL) direction. In some wireless communication systems, the MS communicates with the BS in both the DL and UL directions. For instance, such communication is carried out in cellular telephone systems. In other wireless communication systems, the client terminal communicates with the base stations in only one direction, usually the DL. Such DL communication may occur in applications such as paging.
As shown in FIG. 2, client terminal/MS 12 typically contains a baseband subsystem 16 and a radio frequency (RF) subsystem 18. Memory 20, such as an external memory, is shown connected to the baseband subsystem 16. The baseband subsystem 16 normally includes a micro controller unit (MCU) 22, a signal processing unit (SPU) 24, data converters 26, peripherals 28, power management 30, and memory 32 as shown in FIG. 3. The SPU 24 may be a digital signal processor (DSP), hardware (HW) accelerators, co-processors or a combination of the above. Normally the overall control of the baseband subsystem 16 is performed by software running on the MCU 22 and the processing of signals is done by the SPU 24.
Analog to digital converters (ADCs) convert a received analog signals into digital for the baseband system to process them. Similarly, digital to analog converters (DACs) convert the processed baseband digital signals into analog for transmission. The ADCs and DACs are collectively referred to herein as "data converters" 26. The data converters 26 can either be part of the baseband subsystem 16 or the RF subsystem 18. Depending on the location of the data converters 26, the interface between the two subsystems will be different. The location of the data converters 26 does not alter the overall function of the client terminal.
An RF subsystem 18 normally includes a receiver section and a transmitter section. An RF subsystem 18 for a time division duplex (TDD) communication system is shown in FIG. 4. The receiver section normally may include one or more receivers. The receiver 34 performs the task of converting the signal from RF to baseband. Each receiver may include mixers 36, filters 38, low noise amplifiers (LNAs) 40 and variable gain amplifiers (VGAs) 42. The transmitter section may include one or more transmitters. The transmitter 44 performs the task of converting the baseband signal up to the RF. Each transmitter may include mixers 46, filters 48, and gain control stage 50. In some architectures of the RF subsystem, some of the components may be shared between the receiver section and the transmitter section. As shown, the receiver section 34 and the transmitter section 44 are coupled to an antenna 54 via a transmit/receive switch 56. Synthesizer 58 is also shown as coupling to the receiver section 34 and the transmitter section 44.
The input of each receiver is normally coupled with an antenna and the output of the receiver is normally coupled with ADC. The antenna, receiver, ADC and other related components are collectively referred herein as "receive chain." FIG. 5 illustrates the elements of a receive chain.
The input of each transmitter is normally coupled with DAC and the output of the transmitter is normally coupled with an antenna through a Power Amplifier (PA) which performs power amplification of the transmit signal. The antenna, PA, transmitter, DAC and other related components are collectively referred herein as "transmit chain." FIG. 6 illustrates the elements of a transmit chain.
Multiple transmit and/or receive chains are commonly used in many wireless communication systems for different purposes. Multiple transmit and/or receive chains in wireless communication systems offer spatial dimension that can be exploited in the design of a wireless communication system. Communication systems with multiple transmit and/or receive chains offer improved performance. The performance improvement can be in terms of better coverage, higher data rates, reduced SNR requirements, multiplexing of multiple users on the same channel at the same time, or some combination of the above. Different techniques using multiple receive and/or transmit chains are often referred to with different names such as diversity combining (maximum ratio combining, equal gain combining, selection combining, etc.), space-time coding (STC) or space-time block coding (STBC), spatial multiplexing (SM), beamforming and multiple input multiple output (MIMO). Normally wireless communication systems with multiple transmit chains at the transmit entity and multiple receive chains at the receive entity are referred as MIMO systems. As discussed in detail below, aspects of the invention described in this disclosure applies to the Spatial Multiplexing MIMO system i.e. a wireless communication system that uses Spatial Multiplexing technique using multiple transmit chains at the transmit entity and multiple receive chains at the receive entity.
In Spatial Multiplexing (SM), a high data rate signal is split into multiple lower data rate streams and each lower data rate stream may be transmitted from a different transmit antenna on the same frequency at the same time. Alternatively, data from two different users or applications may be transmitted from different transmit antennas on the same frequency at the same time. If signals from different transmit antennas arrive at the receiver antennas through sufficiently different spatial propagation paths, the receiver may be able to separate these streams of data, creating "parallel channels" on the same frequency at the same time. SM is a powerful technique for increasing channel capacity at higher Signal to Noise Ratio (SNR). The maximum number of spatially multiplexed data streams is limited by the minimum of the number of antennas at the transmit entity and the number of antennas at the receive entity. For example, if the number of transmit antennas at the transmit entity is four and the number of receive antennas at the receive entity is two, the maximum number of spatially separable data streams is two.
FIG. 7 illustrates an example of an SM-MIMO wireless communication system with four transmit chains at the transmit entity, for example the base station, and four receive chains at the receive entity, for example the client terminal.
The signal from a transmit chain arrives at all four receive chains through different propagation paths as shown in the FIG. 7. The receive signal at each receive chains may be a combination of signals transmitted from all four transmit chains and the noise as shown in FIG. 7.
The following notation is used in describing various signals in the remainder of the present invention. A subscript to a signal name denotes transmit or receive chain number to which the signal is associated. When there are two subscripts to a signal name, the first subscript refers to the transmit chain and the second subscript refers to the receive chain to which the signal is associated. Let Nt denote the number of transmit chains and Nr denote the number of receive chains. For SM the number of parallel data streams that can be supported is equal to the minimum of the number of transmit antennas Nt and the number of receive antennas Nr. Normally a wireless communication system with Nt transmit chains at the transmit entity and Nr receive chains at the receive entity is referred as Nt×Nr MIMO communication system.
Wireless communication systems use different modulation techniques such as Quadrature Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (QAM), 64-QAM, etc. FIG. 8 illustrates a 16-QAM constellation and FIG. 9 illustrates a 64-QAM constellation. The set of all symbols in a given modulation technique is referred as constellation or alphabet. Let the total number of symbols in a constellation be denoted by L and the set of all symbols ak of a constellation be denoted by A={ak, ∀ k=0, 1, 2, . . . , L−1}. At a given instant, one symbol that represents the input data at the modulator is selected from the constellation for transmission.
Let the transmitted symbol at a given instant of time from the ith transmit chain be denoted by si for i=0, 1, . . . , (Nt−1). Let the received symbol at a given instant of time at the jth receive chain be denoted by xj for j=0, 1, . . . ,(Nr−1). Let the noise at a given instant of time at the jth receive chain be denoted by nj for j=0, 1, . . . , (Nr−1). The symbols si used for transmission may be one of the symbols from the constellation of a selected modulation technique at the transmit entity.
The signal from one transmit antenna arrives at all the receive antennas through different propagation paths. When the physical distances between the antennas are sufficiently large relative to the wavelength of the radio frequency (RF) being used by the wireless communication system, the signals in different paths may undergo independent or mostly uncorrelated propagation. In practice, the propagation paths may not necessarily be completely independent but the correlation among various paths may generally be low when the antennas are sufficiently far apart. A Spatial Multiplexing decoder may be able to separate the spatially multiplexed data streams as long as correlation among different propagation paths is small.
Let channel conditions between transmit antenna i and receive antenna j be denoted by hi,j, for i=0, 1, . . . , (Nt−1) and j=0, 1, . . . , (Nr−1).
Mathematically, the relationship between the transmitted symbols, the channel conditions, the noise and the received symbols can be expressed as follows for the case of a wireless communication system with four transmit chains and four receive chains:x0=h0,0s0+h1,0s1+h2,0s2+h3,0s3+n0  (1)x1=h0,1s0+h1,1s1+h2,1s2+h3,1s3+n1  (2)x2=h0,2s0+h1,2s1+h2,2s2+h3,2s3+n2  (3)x3=h0,3s0+h1,3s1+h2,3s2+h3,3s3+n3  (4)In matrix notation, for the case of Nt transmit chains and Nr receive chains
                    s        =                              [                                          s                0                            ,                              s                1                            ,              …                                                                        ,                              s                                                      N                    t                                    -                  1                                                      ]                    T                                    (        5        )                                x        =                              [                                          x                0                            ,                              x                1                            ,              …                                                                        ,                              x                                                      N                    r                                    -                  1                                                      ]                    T                                    (        6        )                                n        =                              [                                          n                0                            ,                              n                1                            ,              …                                                                        ,                              n                                                      N                    r                                    -                  1                                                      ]                    T                                    (        7        )                                H        =                  [                                                                      h                                      0                    ,                    0                                                                                h                                      1                    ,                    0                                                                                h                                                                                N                        t                                            -                      1                                        ,                    0                                                                                ⋯                                                                                h                                      0                    ,                    1                                                                                h                                      1                    ,                    1                                                                                h                                                                                N                        t                                            -                      1                                        ,                    1                                                                                ⋮                                                                                ⋱                                            ⋮                                                                                h                                      0                    ,                                                                  N                        r                                            -                      1                                                                                h                                      1                    ,                                                                  N                        r                                            -                      1                                                                                …                                                              h                                                                                N                        t                                            -                      1                                        ,                                                                  N                        r                                            -                      1                                                                                ]                                    (        8        )                                x        =                  Hs          +          n                                    (        9        )
In EQ. (9) s is the transmitted symbols vector, H is the channel matrix, n is noise vector and x is the received signal vector.
Normally, the receiver of the wireless communication system needs to estimate the channel conditions to process the received signals. Wireless communication systems use different techniques to enable the receiver to obtain estimates of channel conditions for different propagation paths between transmit and receive antenna pairs. Some techniques include embedding pilot symbols and/or training symbols along with the data symbols. Receivers normally use the embedded pilot symbols and/or training symbols to estimate the channel conditions. Some receivers may also use the previously decoded data symbols to estimate the channel conditions in addition to the pilot symbols and/or training symbols. In general, a receiver may employ combination of some or all of the available information to estimate the channel conditions. The receiver may use any of the algorithms available in the existing literature to estimate the channel conditions. It is understood that the receiver obtains the required estimates of the channel conditions through techniques known in literature or through some other techniques. Let the estimated channel conditions between transmit antenna i and receive antenna j is denoted by ĥi,j, for i=0, 1, . . . , (Nt−1) and j=0, 1, . . . , (Nr−1) and Ĥ denotes the matrix of estimated channel conditions.
At the receive entity, the received symbols vector x is known. The channel conditions matrix H may be approximated by the estimated channel conditions matrix Ĥ. Based on these two known matrices, the transmitted symbols vector s may be estimated as ŝ by solving the linear system of equations in EQ. 9.
The system of equations represented by EQ. 9 needs to be solved at a rate proportional to the data rate of the wireless communication system. Normally SM-MIMO is used to achieve high data rate in wireless communication systems. Hence the system of equations represented in EQ. 9 needs to be solved at a faster rate. For example, in a broadband wireless communication system that offers data rate of 16 megabits per second over the air using 4×4 SM-MIMO with 16-QAM modulation, EQ. 9 needs to be solved about one million times per second. Therefore, in general the complexity of the SM decoder is high. Further, the complexity of SM decoder normally grows exponentially as a function of the number of transmit chains and receive chains. Therefore, it is crucial to solve the system of equations represented by EQ. 9 in an efficient manner so that the wireless communication system can operate in real time with less processing resources and consumes less power.
There are different optimal and sub-optimal decoders described in the literature to solve the system of equations represented by EQ. 9. The Maximum Likelihood Decoder (MLD) is an optimal decoder for SM. Although MLD provides, theoretically, a best achievable decoding performance, its complexity and processing requirements are normally very high even for the common MIMO wireless communication systems such as 2×2 or 4×4 SM-MIMO with 16-QAM or 64-QAM.
QR Decomposition (QRD) in conjunction with M-algorithm, referred as QRD-M decoder and also called QRD-M method, is one of the commonly used sub-optimal SM decoders. A QRD-M sub-optimal SM decoder provides decoding performance close to that of the optimal SM decoder such as MLD, but requires reduced complexity and processing requirements. The reduced complexity and reduced processing requirements of QRD-M sub-optimal SM decoder makes it better suited for practical implementation. The QRD-M decoder used for SM is referred herein as QRD-M SM decoder.

Dual QR decomposition decoder for spatially multiplexed MIMO signals


Systems, methods and apparatus are provided through which in some embodiments an informal specification is translated without human intervention into a formal specification. In some embodiments the formal specification is a process-based specification. In some embodiments, the formal specification is translated into a high-level computer programming language which is further compiled into a set of executable computer instructions.

Requirements-Based Programming (RBP) has been advocated as a viable means of developing complex, evolving systems. In RBP, requirements can be systematically transformed into executable computer instructions. An implementation of RBP provides a way to generate executable computer instructions from requirements with neither the time involved in manually writing the executable computer instructions, nor the mistakes regarded (generally speaking) as unavoidable in manually writing the executable computer instructions.
Complex systems in general cannot attain high dependability without addressing the crucial remaining open issues of software dependability. The need for ultrahigh dependability systems increases continually, along with a correspondingly increasing need to ensure correctness in system development. Correctness exists where the implemented system is equivalent to the requirements, and where this equivalence can be proved mathematically.
Development of a system that will have a high level of reliability requires the developer to represent the system as a formal model that can be proven to be correct.
Conventional system development tools and methods that are based on formal models provide neither automated generation of the models from requirements nor automated proof of correctness of the models. Conventional system development tools and methods provide no automated, generally applicable way to produce a system—or even a procedure—that is a provably correct implementation of the customer's requirements. Furthermore, requirements engineering as a discipline has yet to produce an automated, mathematics-based process for requirements validation. Automatic code generation from requirements has been the ultimate objective of software engineering almost since the advent of high-level programming languages, and calls for capability of "requirements-based programming" have become strong.
Several tools and products exist in the marketplace today for automatic code generation from a given model; however, these tools and products typically generate code, portions of which are never executed, or portions of which cannot be justified from either the requirements or the model. Moreover, existing tools do not and cannot overcome the fundamental inadequacy of all currently available automated development approaches, which is that they include no way to establish a provable equivalence between the requirements stated at the outset and either the model or the code they generate.
In particular, one tool for deriving executable code from informal notations requires translating the informal specifications into traces, and then using an automated theorem prover to infer an equivalent process-based description. Traces are sequences of events that have occurred in a particular ordering up to a particular point in time. Inferring an equivalent process based specification from the traces requires large computational facilities, sometimes even as large as a supercomputer.
Traditional approaches to automatic code generation, including those embodied in commercial products such as Matlab®, in system development toolsets such as the B-Toolkit® or the VDM++® toolkit, or in academic research projects, presuppose the existence of an explicit (formal) model of reality that can be used as the basis for subsequent code generation. However, these traditional approaches not only depend on other ways to provide the explicit formal model, but also include no facility to ascertain or establish that the model corresponds to the customer's requirements. While such an approach is reasonable, the advantages and disadvantages of the various modeling approaches used in computing are well known, and certain models can serve well to highlight certain issues while suppressing other, less-relevant details. The converse is also true. Certain models of reality, while successfully detailing many of the issues of interest to developers, can fail to capture some important issues, or perhaps even the most important issues. Existing reverse-engineering approaches suffer from a similar plight. In typical approaches, a model is extracted from an existing system and is then represented in various ways, for example as a digraph. The re-engineering process then involves using the resulting representation as the basis for code generation, as indicated above.
The model on which automatic code generation is based is referred to as a design, or more correctly, a design specification. There is typically a mismatch between this design specification and the implementation (sometimes termed the "specification-implementation gap") in that the process of going from a suitable design to an implementation involves many practical decisions that must be made by the automated tool used for code generation without any clear-cut justifications other than the predetermined implementation decisions of the tool designers. Further, there is a more problematic "gap," termed the "analysis-specification gap," that emphasizes the problem of capturing requirements and adequately representing them in a specification that is clear, concise, and complete. This specification must be formal, or proof of correctness is impossible.
Unfortunately, many software system designers are reluctant to embrace formal specification techniques, believing the formal specification techniques to be difficult to use and apply, despite many industrial success stories. While software system designers are happy to write descriptions as natural language scenarios, or even using semi-formal notations such as unified modeling language (UML) use cases, the software system designers are reticent to undertake formal specification. However, absent a formal specification of the system under consideration, there is no possibility of determining any acceptable level of confidence in the correctness of an implementation. More importantly, formal specification must be ensured to have fully, completely, and consistently captured the prescribed requirements. System requirements cannot be expected to be perfect, complete, and consistent from the outset, which is why it is even more important to have a formal specification. Such a formal specification can highlight errors, omissions, and conflicts. The formal specification must also reflect changes and updates from system maintenance, as well as changes and compromises in requirements, so that it remains an accurate representation of the system throughout the life cycle of a system.
Requirements typically evolve during the life cycle of a system, Manual change to the system creates a risk of introducing new errors and necessitates retesting and revalidation, which can greatly increase the cost of the system. Often, needed changes are not made due to the cost of making consequential changes in the rest of the system. Sometimes changes are simply made in the code and not reflected in the specification or design due to the cost or due to the fact that those who generated the original specification or design are no longer available.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an automated, generally applicable approach to produce a system that is a provably correct implementation of an informal design specification that does not require use of a theorem-prover. There is a further need for a convenient way of generating a new system when system requirements change. There is also a need for an automated, mathematics-based process for requirements validation that does not require large computational facilities.

Systems, methods and apparatus for implementation of formal specifications derived from informal requirements

The United States of America as represented by the Administrator of the National Aeronautics and Space Administration


A hydraulic continuously variable transmission has a variable displacement type first hydraulic system having a first plunger and a plunger abutting section which actuates the first plunger, and a second hydraulic system having a second plunger and provided with an output rotary section which rotates with abutment on the second plunger. A cylinder block rotates about an axis and has a first plunger hole and a second plunger hole which respectively retain the first and second plungers. A hydraulic closing circuit connects the first and second plunger holes and circulates a working oil between the first and second plunger holes. The continuously variable transmission has a distributing valve for controlling circulation of the working oil in the hydraulic closing circuit, a valve hole, formed in the cylinder block, for retaining the distributing valve, and a shaft which penetrates the cylinder block. The shaft and the cylinder block rotate synchronously and the output rotary section is rotatably supported around the shaft. The valve hole is formed in parallel to the shaft, and restriction means is arranged inclined with respect to the shaft and rotates in synchronism with the cylinder block to reciprocate the distributing valve with the distributing valve being restricted.

There is known a conventional hydraulic continuously variable transmission equipped with a first hydraulic system which discharges and intakes a working oil by reciprocation of a plurality of plungers and a second hydraulic system having an output rotary section which acquires output rotation with abutment on a plurality of plungers. The first and second hydraulic systems of such a hydraulic continuously variable transmission share a cylinder block and the same cylinder block rotates about its longitudinal axis.
The cylinder block is provided with a plurality of first plunger chambers in which a plurality of first plungers in the first hydraulic system are retained, a plurality of second plunger chambers in which a plurality of second plungers in the second hydraulic system are retained, and a hydraulic closing circuit for circulating a working oil between the first and second plunger chambers. The reciprocation of a plurality of distributing valves provided on the cylinder block circulates the working oil between the first and second plunger chambers.
In such a hydraulic continuously variable transmission, conventionally, each distributing valve is arranged in parallel to the axis of the cylinder block and the distal end of the distributing valve is made to abut on a swash plate in order to impart axial reciprocation to each distributing valve.
According to the prior art, as the distal end of the distributing valve is made to abut on the swash plate, the distributing valve reciprocates in the axial direction while each distributing valve makes one turn around the axis of the cylinder block. In such a structure, each distributing valve is pressed against the swash plate, and pressing means, such as a spring, is needed.
Further, as shown in FIG. 21, a cylinder block 311 in the conventional continuously variable transmission is provided with a plurality of plunger holes 312 and valve holes 313 which constitute a hydraulic closing circuit. Plungers 314 and selector valves 315 for causing the working oil to produce a predetermined flow operation in the hydraulic closing circuit are respectively disposed in the plunger holes 312 and the valve holes 313. The plunger holes 312 and the valve holes 313 are laid out around the longitudinal axis of the cylinder block 311 and communicate with one another via a fluid passage 317. First and second hydraulic chambers 318 and 319, formed in a ring shape around the longitudinal axis of the cylinder block 311, are provided side-by-side in the axial direction of the cylinder block 311 and communicate with all the valve holes 313 provided in the cylinder block 311.
The selector valve 315 has first to third land portions 316a to 316c formed with approximately the same diameter as the diameter of the valve hole 313, and is formed into the shape of a spool. As the selector valve 315 reciprocates in the valve hole 313, the fluid passage is changed over in such a way that the working oil flows to the fluid passage 317 (plunger hole 312) and either the first or second hydraulic chamber 318, 319.
Since the fluid passage for the working oil is changed over by reciprocation of the selector valve 315 in the conventional apparatus, there is a position where the working oil is not exchanged between the fluid passage 317 and the valve hole 313 (i.e., the first and second hydraulic chambers 318 and 319) during reciprocation of the selector valve 315. The position of the selector valve 315 at this time is called a seal position. When the selector valve 315 is positioned at the seal position, as shown in FIG. 21, a port 320 which is the merging section of the fluid passage 317 and the valve hole 313 is closed by the second land portion 316b of the selector valve 315. As a result, the exchange of the working oil between the fluid passage 317 and the valve hole 313 (first and second hydraulic chambers 318 and 319) does not take place.
In the case structure where the port 320 is closed merely by the second land portion 316b at the time the selector valve 315 is positioned at the seal position, however, pressure is applied intensively to a part of the outer surface of the second land portion 316b by the working oil staying in the fluid passage 317. As a result, the reciprocation of the selector valve 315 may not be carried out smoothly in the valve hole 313.
As shown in FIG. 22, therefore, one may think of a structure in which a diameter-widened portion 321 is formed by widening the portion of the valve hole 313 that corresponds to the port 320, and the diameter-widened portion 321 is caused to face the second land portion 316b at the time the selector valve 315 is positioned at the seal position. This permits the working oil to stay over the peripheral surface of the second land portion 316b even when the working oil is exchanged between the fluid passage 317 and the valve hole 313 (first and second hydraulic chambers 318 and 319). As a result, the reciprocation of the selector valve 315 is performed smoothly without intensive application of pressure to a part of the outer surface of the second land portion 316b by the working oil remaining in the fluid passage 317.
However, the diameter-widened portion 321 is formed at that portion of the valve hole 313 that corresponds to the port 320 located in the lengthwise middle portion thereof. In the fabrication process for the cylinder block 311, therefore, the following problem arises at the time of forming the diameter-widened portion 321 of the valve hole 313. That is, normally, the valve hole 313 is formed by boring a hole with a predetermined diameter by a drill or the like first, then cutting work is performed on the diameter-widened portion 321. At this time, to form the diameter-widened portion 321, a thin tool with an L shape, for example, should be used and should be inserted through the opening of the valve hole 313 for the cutting work. This requires very difficult work in forming the diameter-widened portion 321 and leads to the problem of an increased number of working steps.
The present invention has been devised in consideration of the above-described situations, and aims at providing a hydraulic continuously variable transmission and a power transmission apparatus which can simplify the structure for reciprocating each distributing valve and forming a valve hole simply and easily.

Hydraulic continuously variable transmission and power transmission apparatus


A method for separating signal sources by use of physically unique dictionary elements. The method is particularly advantageous for separating cerebral from artifactual sources in electroencephalographic (EEG) recording, making use of dictionary element pattern recognition methods that are tuned to the unique physical properties of each source domain.

EEG ("electroencephalography") signal data are often obtained for the purpose of identifying where, in the brain, the sources of neuronal activity are located. The data are collected from a network of spaced-apart electrical sensors worn on the head surface, each sensor sensing the electrical potential produced at its particular location. The electrical potentials are resulting effects of the neuronal activity. It is desired to solve for the distribution of the sources.
The straightforward, "forward conduction" problem, is to solve for the electrical potentials knowing the sources. That is,
            [                                                  Φ              1                                                                          Φ              2                                                            ⋮                                                              Φ              Ne                                          ]        =                  [                                                            K                                  1                  ,                  1                                                                                K                                  1                  ,                  2                                                                    ⋯                                                      K                                  1                  ,                  Nd                                                                                K                                  2                  ,                  1                                                                                K                                  2                  ,                  2                                                                    ⋯                                                      K                                  2                  ,                  Nd                                                                                …                                                                                K                                  Ne                  ,                  1                                                                                K                                  Ne                  ,                  2                                                                    ⋯                                                      K                                  Ne                  ,                  Nd                                                                    ]                          [                                                            J                1                                                                                J                2                                                                                J                Nd                                                    ]                  or    ,                            Φ      =      KJ
where Φi is the measured electrical potential at a particular sensor "i" (i ranging from 1 to Ne); Jk is the neuronal activity of a particular source "k" (k ranging from 1 to Nd); and K is the "lead forward" matrix.
It is less straightforward to solve the "inverse problem," i.e., to solve for the source locations knowing the electrical potentials. Even if the matrix K is square, one cannot generally simply invert it to solve for J, because the sensor data are not independent. The data are generally insufficient to specify a unique solution, and the inverse problem is typically treated as an optimization problem, with the permitted solutions being subject to anatomical or other constraints.
It is particularly important for solving the inverse problem to ensure that the measured potentials result solely from the neuronal source activity. If the measured potentials have other causes, it is not possible to solve the inverse problem accurately, and the measured potentials typically do have other causes. For example, the electrical activity associated with blinking an eye will contribute to the measured electrical potentials. The sensors, particularly by virtue of the lead wires acting as antennas, will also pick up electrical noise from the environment. These and other additional sources of electrical potential generate "artifacts" in the measured signal.
A specific artifactual problem occurs when BEG is conducted during MRI, when the electrodes are disposed in a very strong magnetic field. A "ballistocardiographic" artifact (BCGa) results from pulsating blood flows in the arteries in the scalp causing electrode movement, which generates an electrical potential in the magnetic field that is of considerably larger magnitude than the electrical potential resulting from the neuronal sources.
The standard approach for removing artifacts produced by causes such as eye-blinks from EEG data is to use techniques like statistical decomposition, principle component analysis (PCA), or independent component analysis (ICA), to find components of the measured signal that are characteristic of such causes to identify components that are subtracted from the signal. Then, the source analysis (solving the inverse problem) is performed on the remaining signal.
These techniques are not completely effective and there remains a need for further improvement.

Method for separating signal sources by use of physically unique dictionary elements


A computerized system that will allow healthcare providers to access the commercial paper market by “selling” their patient claims to asset backed commercial paper conduits. The system generates the statistical information on the historic collection experience of the provider's claims required by both the rating agencies and the sponsors of the conduits. This statistical information has two pieces: the net collectible value matrix showing the percentage of the claim actually paid by individual payers; and a collection histogram showing the timing of the payers payments from the date of initial billing. The system also generates the accounting detail necessary for controlling and auditing the provider's participation in the commercial paper conduit program. The system tracks “periodic pools” of claims so as to be able to reconcile advances, collections, interest expense, third party fees and cash settlements between conduits and providers. This statistical information has two pieces: the net collectible value matrix showing both the percentage of the claim actually paid by individual payors and the standard deviation of this percentage; and a collection histogram showing the timing of the payors' payments from the date of initial billing.

Asset-backed commercial paper programs (also known as "conduits") take illiquid assets and bundle these assets into a segregated pool against which highly liquid money-market instruments can be issued. The cash collected on the underlying assets in the pool is the source of repayment of principal and interest on these instruments. In these programs, the underlying assets are the receivables of business entities and the market instrument that is issued is commercial paper. Asset-backed commercial paper programs use a financial "vehicle" called a special purpose entity (SPE) to issue commercial paper. The program provides a service basically similar to that offered by a factoring company (also known as a "factor"), in that the SPE finances the receivables of corporate clients. In other respects, however, the SPE differs from a factoring company. Typically, a factor assumes the role of a credit department for its clients to evaluate the credit-worthiness of the client's customers. While it finances a client's receivables by purchasing them, the SPE does not perform a credit evaluation of each obligor associated with the receivables in the pool as a factor would, but relies instead on an actuarial review of the past performance of the client's portfolio of receivables. With an SPE, the corporate client usually performs the servicing function, whereas in a factoring arrangement, the factor generally services the receivables. Asset-backed commercial paper programs are ongoing activities. The SPE continually purchases new receivables and usually "rolls over" the outstanding commercial paper.
FIG. 1 shows the structure and cash flows of a conventional prior art paper program 10. Prior to acquiring the receivables, the program sponsor 26 reviews the receivables. The review covers the credit origination standards of the company 14 originating the receivables and current and historical quality and performance of this portfolio. The asset backed commercial paper program uses an SPE 12 to acquire legal title to receivables directly from a company 14 participating in the program To obtain finding, the SPE 12 issues commercial paper to an investment bank 16. The investment bank 16 sells the commercial paper to investors 18. The commercial paper is ultimately repaid by the SPE 12 from the cash flow of the underlying pools of receivables. The rating agencies require that the entire amount of outstanding commercial paper be covered by liquidity and credit enhancements before the program can receive the highest investment rating. These enhancements are provided by credit enhancer 20 and liquidity provider 22. Employees of the investment banking firm 16 generally own the equity of the SPE. The owner 24 of the SPE 12 receives dividends. A program sponsor 26 such as a bank receives a fee.
Health care receivables differ in several important ways from other types of receivables that have been securitized to date. Health care providers, by delivering various forms of medical services, are the originators of health care receivables (also known as medical claims). The bill for the services rendered may be payable entirely by the patient, entirely by some form of insurance, or partially by the patient and partially by insurance. The insurance payors and the patient are the obligors on the receivable. The insured portion of a health care receivable may be payable by a government program (such as Medicare), a Blue Cross/Blue Shield insurance company, a private insurance company, or a Health Maintenance Organization (HMO).
Unlike most other types of receivables, the face amount of the medical claim may have limited relevance to the amount the health care provider can reasonably expect to collect. The reimbursement procedures for medical services are complicated. For example, Medicare might be willing to pay only a fraction of the amount billed based either on their system of diagnostic-related groups (DRGs), the use of a resource-based value scale (RBVs), or on allowable costs incurred. Similarly, Blue Cross/Blue Shield or a private insurance company might limit the amount paid to a percentage of the provider's fees and charges, or an estimate of the reasonable and customary charge for the procedure in the locality in which the medical service was rendered. Finally, an HMO may pay on a per diem rate or on a fixed-fee-per-person basis (capitated payment).
Claims paid by Medicare are also subject to the requirement that they are directly payable to the health care provider. A consequence of the direct payment requirement is that Medicare payments paid to a bankrupt provider/seller might be trapped by the Bankruptcy Code's automatic stay. This risk could be reduced in a commercial paper program by making the provider set up a "bankruptcy-remote" subsidiary through which all Medicare claims are billed. The conduit can then lend money to the bankruptcy-remote subsidiary and take a senior secured position against the subsidiary's assets.
As described below, the present invention provides an information system to facilitate securitization of medical receivables. The invention is applicable to other types of receivables as well.

System for invoice record management and asset-backed commercial paper program management


A laryngeal airway device, having an airway tube which has an internal passage in the airway tube wall for receiving a cuff inflation line, and a dome having an inlet and an outlet, where the dome is connected at its inlet with the distal end of the airway tube. The device also includes an annular spoon-shaped inflatable cuff connected with the periphery of the outlet of the dome; a cuff inflation line configured to be in fluid communication with the internal space of the cuff; and a multi-lobed aperture formed in the dome. The aperture is configured to be in fluid communication with the proximal end of the airway tube. The dome has protrusions forming the multi-lobed aperture, such that a flap is configured to prevent the obstruction of the aperture by a patient's epiglottis when the device is inserted into the patient.

The present invention relates to laryngeal airway devices. More specifically, the present invention relates to improved geometric and design configurations for laryngeal airway devices.
It is common practice to use an airway device known as a laryngeal mask for the administration of anesthetic and ventilation gases to a patient. These airways comprise a tube with an inflatable mask or cuff at one end, the tube being inserted in the patient's mouth so that one end is located in the hypopharynx and so that the mask forms a seal in this region with the surrounding tissue. Laryngeal masks are provided by many suppliers.
The laryngeal airway is a device that fills the gap between tracheal intubation and the use of a face mask. The laryngeal airway device is inserted blindly into the pharynx and forms a low pressure seal around the laryngeal inlet. It is minimally stimulating to the airway, thus avoiding the unwanted sympathetic stimulation associated with laryngoscopy. The laryngeal airway device provides a way of establishing an airway during anesthesia in both adults and children, and plays a useful role in management of the difficult airway.
As show in FIG. 1, a common laryngeal airway device is constructed of medical-grade silicone rubber with no latex in any part. This allows the laryngeal airway device to withstand repeated autoclaving. The device has a shaft or airway tube 1 ranging from 5.25 to 12 mm in internal diameter, depending on the size of the laryngeal airway device. The shaft is fused at an angle to a distal elliptical spoon-shaped mask 2 with an inflatable rim or cuff resembling a miniature face mask. The shaft opens into the concavity of the ellipse via an aperture having aperture bars 3 across the opening to prevent the epiglottis from falling back and blocking the lumen. Various different size laryngeal airway devices are available to accommodate different size patients, from neonates to adult patients.
When correctly positioned, the tip of the laryngeal airway device cuff lies at the base of the hypopharynx against the upper esophageal sphincter, the sides lie in the pyriform fossae, and the upper border of the mask lies at the base of the tongue, pushing it forward. The epiglottis often lies within the bowl of the laryngeal airway device, but the device functions satisfactorily with the epiglottis in the upright horizontal or downfolded position. When the cuff is around the opening to the larynx, a syringe connects to the valve 4 to inject air into the cuff via the inflation line 5 to inflate the cuff, such that no gap is present between the cuff and the larynx. The inflation line 5 meets the cuff 2 at an inflation line inlet 8, which inlet 8 is typically also the mold extraction point or orifice used during the forming of the cuff 2. An inflation line balloon 6 reflects the degree of inflation of the cuff. Typically, the airway tube includes a securely attached 15 mm connector 7 at its proximal end.
However existing laryngeal airway devices suffer from various shortcomings. For example, the aperture bars across the airway opening prevent the entry of other devices, such as bronchoscopes and/or endotracheal tubes into the airway passage. The spoon-shaped cuff is inflated at its proximal end by a separate inflation line. In some devices, the inflation line inlet at the proximal end of the cuff is also the same as the mold extraction orifice used to form the cuff, and protrudes away from the surface of the cuff, resulting in a nonsmooth external surface for the cuff. The separate inflation line needs to be carefully handled as the laryngeal airway device is inserted into a patient's airway. It has been reported by many that the cuff folds back on itself as the laryngeal airway device is being inserted. The folded cuff prevents the cuff from being properly inflated thus preventing effective placement of the device. In addition, the commonly placed 15 mm connector at the proximal end of the airway tube can also prevent the insertion of other devices into the airway tube.
There is therefore a need for an improved laryngeal airway device that does not suffer from these shortcomings.


Input light is split by an input-light splitter into first split light and second split light. A multiplex-interference portion performs multiplex interference of the first split light and the second split light to generate intensity-modulated light having a first wavelength. A phase modulation portion is fed with the intensity-modulated light and continuous wave light having a wavelength equal to a second wavelength, and performs cross-phase modulation of the continuous wave light in accordance with phase modulation of the input light.

1. Field of the Invention
The present invention generally relates to a wavelength converter; and more particularly, to an optical wavelength converter for phase-modulated light signals for use, for example, in coherent (interferability) optical communication or with an all-light cross connect.
2. Description of the Related Art
In recent years, developments are in progress for wavelength division multiplex (WDM) optical communication schemes in large-scale optical communication systems. In the optical communication systems, the network performance can be significantly improved by converting the wavelengths of signals at nodes of the network. Conventionally, as a wavelength conversion device of a practical phase modulation scheme, there is generally known a device using four-wave mixing. Specifically, various wavelength converters have been proposed, utilizing, for example, cross-gain modulation or cross-phase modulation of semiconductor laser amplifiers or utilizing four-wave mixing of lights (see, for example, Patent Reference Document 1).
FIG. 5 shows an overall constitution of a conventional wavelength converter. In the wavelength converter for an optical phase modulation communication using a four-wave mixing, input phase-modulated light having a wavelength λ1 is mixed by an optical coupler with continuous wave light (referred to as "CW light" or "pump light", hereinafter) having a wavelength λ3 generated by a laser diode (LD). Then, the mixed light is inputted to an optical medium such as a semiconductor optical amplifier (referred to as "SOA", hereinafter) having nonlinear optical effects. In the SOA, a phase-conjugate wave having a wavelength λ2 (=2λ3−λ1) is generated by the four-wave mixing. The phase-conjugate wave having a wavelength λ2 is symmetric to the wave of the wavelength λ1 with respect to the wavelength λ3 on a wavelength axis. The phase-conjugate wave is outputted through an optical filter to thereby obtain wavelength-converted light having a wavelength λ2 that has undergone the same phase modulation as that for the wavelength λ1.
In another conventional art of, for example, Patent Reference Document 2, there is disclosed a wavelength converter of an electro-absorption (EA) type. In this art, incident signal light and continuous wave (CW) probe light from a probe light source are inputted to an electro-absorption (EA) type modulator. The probe light outputted from the electro-absorption (EA) type modulator has a waveform incorporating the waveform of the incident signal light, and is fed to a subsequent stage by a circulator.
In still another conventional art of, for example, Patent Reference Document 3, there is disclosed a wavelength converter for intensity-modulated light signals. This wavelength converter has, for example, a waveguide for generating nonlinear refractive index variations, a delay interference circuit with two optical paths having different optical path lengths, and a CW light source, thereby achieving an simplified constitution and control with a stable operation.
In yet another conventional art of, for example, Patent Reference Document 4, there is disclosed a wavelength converter for intensity-modulation light signals. This wavelength converter includes a monolithically integrated delay loop located in a delay interference construction having only a SOA, using an asymmetric isolation coupler.
Patent Reference Documents referred to in the above are as follows:
Patent Reference Document 1: Japanese Patent Unexamined Laid-open Publication No. 10-78595 (Paragraphs 0017 to 0010; FIGS. 11 to 14)
Patent Reference Document 2: Japanese Patent Unexamined Laid-open Publication No. 2000-236302 (Paragraph 0030; FIG. 1)
Patent Reference Document 3: Japanese Patent Unexamined Laid-open Publication No. 10-301151 (Paragraphs 0015 to 0020; FIG. 1)
Patent Reference Document 4: Japanese Patent Unexamined Laid-open Publication No. 2002-40504 (Paragraphs 0008 to 0010; FIG. 1)
Nevertheless, however, the conventional wavelength converters use four-wave mixing, which is one type of nonlinear optical effects obtained by such as a SOA. Therefore, there arises a problem that the intensity of the obtained wavelength-converted light is low in comparison to that of the CW light of the wavelength λ3, and the conversion efficiency is low accordingly.
A relation as expressed by the equation given below exists between the individual wavelengths λ1, λ2, and λ3:λ2=2×λ3−λ1
Therefore, it is impossible to convert the input light to an arbitrary wavelength light, which arise a problem of increased restriction in wavelength.


When electric power is obtained from a thermoelectric element, a value of electric current is changed, and two combinations of the electric current value and a voltage value (i1, V1) and (i2 and V2) are obtained. An electric current value it at which the maximum electric power Wmax can be obtained is obtained using an electric current-voltage characteristic estimated based on the obtained two combinations of the electric current value and the voltage value. The electric current is controlled such that the value of the electric current becomes equal to the obtained value it when the electric power is obtained from the thermoelectric element. The value it is represented by an equation,it=(i2V1−i1V2)/2(V1−V2).

1. Field of the Invention
The invention relates to an electric power generating apparatus using a thermoelectric element. More particularly, the invention relates to control of generated electric power in an electric power converter in an electric power generating apparatus which is provided in an exhaust system of an automobile or the like, and which supplies electric power generated due to a temperature difference between exhaust gas and a cooling medium, using the electric power converter.
2. Description of the Related Art
A thermoelectric power generating apparatus is known, which recovers, as electric power, heat energy contained in exhaust gas discharged from a combustion device such as an engine of an automobile. In such a thermoelectric power generating apparatus, one end of a thermoelectric element is heated by exhaust gas, and the other end of the thermoelectric element is cooled by a cooling medium such as coolant, whereby electric power is generated in the thermoelectric element due to a temperature difference between the exhaust gas and the cooling medium. After the voltage of the generated electric power is increased and smoothed by the electric power converter, the electric power is supplied to a battery and the like.
Meanwhile, output electric power of the thermoelectric element varies depending on an electric current value when the output electric power is obtained. Further, this electric current-electric power (voltage) characteristic varies also depending on a temperature at each of both ends of the thermoelectric element. Accordingly, as disclosed in Japanese Patent Application Publication No. JP-A-6-22572, in order to efficiently obtain electric power when a condition on a high-temperature side of the thermoelectric element and a condition on a low-temperature side of the thermoelectric element change, for example, when electric power is generated using exhaust gas of an automobile, it is necessary to control electric current when the electric power is obtained according to the electric current-electric power (voltage) characteristic. In this technology, a temperature on the high-temperature side of the thermoelectric element and a temperature on the low-temperature side of the thermoelectric element are measured; an electric current value at which the output electric power becomes optimal is obtained based on an output characteristic of the thermoelectric element at the measured temperatures, the output characteristic being obtained in advance; and the electric current is controlled to become equal to the obtained electric current value when the electric power is obtained.
In order to closely attach temperature sensors on the high-temperature side and the low temperature side of the thermoelectric element, a fixing member such as a spacer is required. The fixing member and the temperature sensors serve as thermal resistance. As a result, the amount of heat transmitted in the thermoelectric element is decreased, and electric power generation efficiency is also reduced. Also, ordinarily, multiple thermoelectric elements are connected in order to increase the amount of generated electric power. However, since temperatures at both ends of the thermoelectric element vary with each thermoelectric element, it is difficult to detect overall tendency in the temperatures using the small number of temperature sensors. Meanwhile, if the number of the temperature sensors is increased, cost is increased, and the electric power generation efficiency is reduced. Therefore, increasing the number of the temperature sensors is also difficult. Also, in order to accurately detect a transient change in the temperatures, it is necessary to enhance responsiveness of the temperature sensors. Particularly when responsiveness of the temperature sensor on the high-temperature side is enhanced, the cost is increased.

Electric power generating apparatus and control method for electric power generating apparatus


A high-hat stand comprising a rod engaging a reset spring from above, and having a movable cymbal installed on top, a pedal connecting to the bottom end of said rod, and vertically moving said rod by an urging operation, a roller link on the bottom end of said rod, and supported in the middle so as to be vertically freely moving, rotors supported in a freely rotatable manner on both ends of said roller link, and a communicating member running over these rotors, and one end of which is connected to said pedal and the other end of which is connected to pedal frame.

1. Field of the Invention
The present invention relates to a high-hat stand, and in particular to a high-hat stand of superior performance and response characteristics.
This application is based on patent number Hei 9-164074 filed in Japan, the contents of which are incorporated herein by reference.
2. Description of Related Art
A high-hat stand is provided with a stand body, and a rod that extends through this stand body in a vertically freely moving manner, and engages with a reset spring in an upward direction. By pressing down a pedal positioned below the rod, the rod overcomes the tension of the reset spring, and can move down. Also, on the upper part of the stand body a stationary cymbal is installed, and on top of the rod a movable cymbal is installed. When performing, the performer steps down on the pedal, and the actuating rod is lowered, and the movable cymbal strikes the stationary cymbal.
The strength of the reset spring is very important in terms of improving the performance and response characteristics of the high-hat stand. That is, if the reset spring is too strong, the performer must push very hard on the pedal, making delicate operation of the pedal difficult. On the other hand, if the reset spring is too weak, the force of the performer's stepping on the pedal is light, and while delicate operation of the pedal is possible, the pedal return becomes slow, however, and quick pedal operation becomes difficult. Therefore, in order to improve the performance and response characteristics of the high-hat stand, it is necessary that the pedal can be stepped on lightly, but return quickly.
In order to resolve the above problem, a high-hat stand with a strong reset spring but a light pedal touch (Japanese Patent Application, First Publication, No. Hei 3-251895) is known. In this high-hat stand, as shown in FIG. 4, a wheel 3 used as a driving pulley is installed on the lower end of rod 1, and via the two chains wrapping around wheel 3, the rod 1 and the pedal 5 are connected The wheel 3 comprises two rotors 3A and 3B which rotate around a central shaft 2. The one end of chain 4A is connected to the large diameter rotor 3A, and the other end is attached to the pedal frame 6, while one end of the other chain 4B is connected to the small diameter rotor 3B, and the other end connected to the petal 5. In addition, reference numeral 7 is the reset spring of the rod 1, reference numeral 8A is the stationary cymbal, and reference numeral 8B is the moving cymbal.
In this high-hat stand, when the tensile force of the reset spring 7 is F, the urging force on the pedal 5 is P, the force required to move the rod 1 down is W (=F), and the operating distance for pedal 5 necessary to move the movable cymbal 8B down a certain distance (h) is H, the following relationship holds: EQU PH=Wh.
In addition, when the radius of the rotor 3B is X, and the radius of the rotor 3A is Y, the following relationships also hold: EQU H=h+X/Y.multidot.h=(1+X/Y)h, EQU h=Y/(X+Y)H, EQU P=Y/(X+Y)W,
and EQU W=(1+X/Y)P.
Therefore, when X:Y=1:2, EQU P=2/3 W,
and EQU H=3/2 h.
Additionally, when the end of the one chain 4B is connected to the rotor 3A, and the end of the other chain 4A is connected to the rotor 3B, and X:Y=2:1, then: EQU P=1/3 W,
and EQU H=3 h.
Therefore, in a high-hat stand, when using a reset spring 7 having an identical tensile strength F, the urging force P of the pedal 5 is made smaller than the force W (=F) necessary to move the rod 1 down, and the operation distance H of pedal 5 required to move the movable cymbal 8B down a certain distance becomes large.
However, in this high-hat cymbal, because two rotors 3A and 3B which differ in size and two chains 4A and 4B which differ in length are necessary, the types of parts become numerous, and the assembly of the parts is troublesome. In addition, in order to obtain the large urging force P, the radius Y of the rotor 3A is made large, and the gap between the rotor 3A and the pedal frame 6 becomes narrow. Therefore, in fact, the operating distance H of the pedal S cannot be made large.
In consideration of the above-described problems, it is the object of the present invention to provide a high-hat stand which can make the urging force of the pedal small without changing the tensile force of the reset spring, and furthermore, has a small number of parts, and a large pedal operating distance.


The present invention provides an ion beam processing technology for improving the precision in processing a section of a sample using an ion beam without making a processing time longer than a conventionally required processing time, and for shortening the time required for separating a micro test piece without breaking the sample or the time required for making preparations for the separation. An ion beam processing apparatus is structured so that an axis along which an ion beam is drawn out of an ion source and an ion beam irradiation axis along which the ion beam is irradiated to a sample mounted on a first sample stage will meet at an angle. Furthermore, the ion beam processing apparatus has a tilting ability to vary an angle of irradiation, at which the ion beam is irradiated to the sample, by rotating a second sample stage, on which a test piece extracted from the sample by performing ion beam processing is mounted, about the tilting axis of the second sample stage. The ion beam processing apparatus is structured so that a segment drawn by projecting the axis, along which the ion beam is drawn out of the ion source, on a plane perpendicular to the ion beam irradiation axis can be at least substantially parallel to a segment drawn by projecting the tilting axis of the second sample stage on the plane perpendicular to the ion beam irradiation axis.

The present invention relates to a manufacturing technology for electronic parts such as semiconductor devices. More particularly, the present invention is concerned with an ion beam processing technology for processing a section of a sample with an ion beam, or for processing a sample so as to separate a micro test piece from the sample or make preparations for the separation.
Manufacture of electronic parts such as semiconductor memories represented by a dynamic random access memory (DRAM), microprocessors, semiconductor devices including a semiconductor laser, and magnetic heads is requested to offer a high yield. This is because a decrease in the yield derived from production of a defective invites degradation of cost-effectiveness. Therefore, it is a critical problem how a defect or a foreign matter causing a defective or an imperfectly processed good is discovered in an early stage and what measures are taken. For example, at a site of manufacturing an electronic part, efforts are made to discover a defective by performing close inspection and to analyze the cause of occurrence of the defect. In an actual electronic part manufacturing process in which wafers are treated, a wafer that is being processed is inspected in order to track down the cause of an abnormality such as a defect in a circuit pattern or a foreign matter, and a countermeasure is discussed.
Normally, a scanning electron microscope (SEM) offering a high resolution is used to observe an abnormality in a sample. In recent years, a complex FIB-SEM machine that uses a focused ion beam (FIB) in combination with the SEM has been employed. In the FIB-SEM machine, the FIB is irradiated in order to form an angular hole in a desired region so that the section can be observed using the SEM.
For example, Japanese Patent Application Laid-Open No. 2002-150990 has proposed an apparatus that forms a rectangular hole near an abnormality in a sample using the FIB, observes the section of the rectangular hole using the SEM, and thus observes or analyzes a defect or a foreign matter.
Moreover, PCT International Publication WO99/05506 has proposed a technology for extracting a micro test piece, which is to be observed using a transmission electron microscope (TEM), from a bulk sample using the FIB and a probe.
Moreover, Japanese Patent Application Laid-Open No. 2000-156393 has proposed a technique of extracting a micro test piece to be inspected from a wafer without breaking the wafer, and returning the wafer, from which the micro test piece is extracted, to a production line. According to the technique, a progress in a machining process is monitored using a monitor, and a wafer is inspected or analyzed.
Moreover, Japanese Patent Application Laid-Open No. 7-320670 has proposed a technology for processing a sample, which is to be observed using the SEM, with an argon ion beam whose beam spot has a diameter of 0.1 μm and which is generated by a helicon wave ion source.


The invention relates to a device and a method for insulation monitoring including identification of a faulty outer conductor in a three-phase ungrounded power supply system.

Electric installations having a high energy demand, such as a smelting or annealing furnace, other heating installations or deposition equipment from the chemical industry, often require special safety measures for limiting the effect of electric faults. This is founded in the necessity to prevent fires, explosions or chemical accidents. Additionally, the necessity of being able to continue operating electric installations over a certain period of time when an electric fault has arisen often exists in order to prevent a production stop or because a production process cannot be temporarily disrupted for operational or physical reasons.
Ideally, these objectives are attained by an ungrounded power supply system for supplying power, also referred to as an insulated power supply system or IT system for short (French: Isolé Terre—IT).
In this grid type, the secondary side of the inputting mains transformer or the current-generating generator does not have a direct connection to the ground potential, i.e. to ground. If a first insulation fault, such as a ground fault in a connected consumer or at an outer conductor itself, arises in the electric installation connected to the input location, a critical fault current does not flow yet and the installation can continue in operation in most instances—at least high-energy fault situations do not occur. Since a grounded grid has now been established by the first fault, a second insulation fault would have the same consequential effect as in a grounded power supply system (TN system, from French Terre Neutre). It is therefore imperative to identify the first fault and to remove it as quickly as possible, depending on the individual risk assessment of the installation, or to even immediately turn off the affected installation part if necessary.
For monitoring the insulation condition of the installation, installation monitoring devices are commonly used which comprise a pulse generator functioning as a measuring-voltage generator which superposes a measuring voltage on the grid. When an insulation fault arises, a measuring circuit is closed between a faulty outer conductor and ground, a measuring current proportional to the insulation fault flowing in said measuring circuit; said measuring current is detected as a measuring-voltage drop by means of a measuring device of the insulation monitoring device and is evaluated in an (insulation resistance) evaluation device of the insulation monitoring device so as to determine the insulation resistance.
Since high operating voltages are often used in electric installations requiring much energy for reducing the operating currents and thus also the cross sections of used conductors, insulation monitoring devices configured for these operating voltages are expensive or require sophisticated coupling devices.
Due to the measuring methods applied in the insulation monitoring devices, another disadvantage is that only one single (active) insulation monitoring device can be used for each IT system in order to keep the measuring processes from influencing each other. This insulation monitoring device then monitors the total insulation resistance of the installation.
To predictively plan maintenance activities, to implement repair works caused by insulation degradations or to selectively turn off installation parts—thus allowing a continued operation of the remaining installation—it is mandatory to be able to determine the location of the arisen insulation fault in the installation.
For this purpose an insulation fault location device is used according to the state of the art. This insulation fault location device comprises a test-current generator for generating a test current and a (test-current) evaluation device, which has measuring-current transformers connected thereto, in order to localize the faulty conductor outlet.
If a first insulation fault has been identified in the ungrounded power supply system by the insulation monitoring device, the insulation fault location is commenced by the test-current generator generating a test current which is supplied at a central location into the ungrounded power supply system between one or several active conductors and ground. A closed circuit is formed in which the test current flows from the test-current generator via the live active conductor(s), via the insulation fault and via a ground connection back to the test-current generator.
The fault location is localized by detecting the test current via the measuring-current transformers, which are each firmly assigned to a conductor section to be monitored.
The test current is detected as a residual current by all measuring-current transformers, which are in the test circuit (fault circuit), is evaluated in the evaluation device and displayed by the insulation fault location device. The fault location can be localized by the known assignment of the measuring-current transformer to the conductor branches.
In the previously described use of high mains voltages in power supply systems supplying consumers with a high energy demand, however, suitable test-current generators can only be obtained with much difficulty on the market or indeed it is difficult to construct a test-current generator configured for such high operating voltages as corresponding components resistant to voltage are highly priced.
Furthermore, the insulation strength of the components of the insulation fault location device, in particular of the measuring-current transformers, often poses a problem which can oppose an insulation fault location. Retrofitting existing installations can also be difficult since the installation space for corresponding so-called "split" current transformers which can be retrospectively installed often is not available. Using band transformers oftentimes is also not desired due to the limited precision and sensitivity. In addition, conventional insulation fault location systems work rather slowly. More than 10 seconds can pass until a fault is localized, a duration not nearly sufficient for the requirements for the abovementioned applications.
In particular in three-phase IT systems in which independently of each other only one of the other outer conductors of independent single-phase consumers having a high energy demand is connected to each phase, that is to each outer conductor, it is desired to selectively identify only the faulty outer conductor of the three-phase IT system affected by the fault in the fault instance and to disconnect it from the grid if required but to continue supplying the remaining consumers via the unaffected outer conductors.
Presently, it is presumed that the consumers connected to the respective phase can be modelled having mostly identical values with respect to their equivalent circuit diagram. A purely capacitive load is not admissible at an outer conductor and a purely inductive load is not admissible at another outer conductor in the scope of the invention since this constellation would strongly influence the phase angle.

Device and method for insulation monitoring including identification of a faulty outer conductor in a three-phase ungrounded power supply system

Abstract: The fundamental idea of the present invention rests upon determining the phase angle between the measured mains voltage and the measured neutral-point voltage when presuming only one measurement of the mains voltage to ground at one of the outer conductors and one measurement of the neutral-point voltage to ground. The value of the thus determined phase angle is in one of three angle ranges which each extend over 120 degrees and are to be assigned to one of the three outer conductors so that the faulty outer conductor is determined. The faulty outer conductor is thus detected by measuring only one mains voltage in conjunction with the measurement of the neutral-point voltage by evaluating the phase between the two measured voltage.


Interleukin-2 receptor derived from normal and malignant cells has been purified by use of various techniques including affinity chromatography in conjunction with a monoclonal antibody directed to the receptor. The purification process also includes reversed phased high performance liquid chromatography. By these techniques, interleukin-2 receptor has been purified to homogeneity. The high purification of the interleukin-2 receptor has made possible the sequencing of the amino acid residues at the N-terminal of this protein molecule. Double-stranded cDNA is prepared from polyadenylated RNA extracted from cell lines or other sources known to produce IL-2 receptor. The cDNA is inserted within a plasmid vector and then the recombinant plasmid employed to transform an appropriate host. Transformed hosts are identified and grouped into pools. Plasmid DNA prepared from these pools is hybridized with a labeled synthetic oligonucleotide probe corresponding to a portion of the amino acid sequence of the purified IL-2 receptor. The cDNA clone isolated with the probe is characterized by restriction enzyme mapping and sequenced by chain-termination method. The particular DNA clone that actually contains the gene coding for the functional IL-2 receptor is identified by expressing the clones in COS-7 monkey kidney cells and assaying for the expressed IL-2 receptor by its ability to bind IL-2 or a monoclonal antibody directed against the IL-2 receptor.

A large number of normal immune responses require the participation of T-cells. The proliferation of T-cells to sufficient numbers to assume an effective role in immune responses is controlled by the presence of interleukin-2 (hereinafter "IL-2"), Gillis and Smith, 28 Nature 154 (1977). Although the mechanism by which IL-2 controls the growth of T-cells is not fully understood, it is known that IL-2 acts on T-cells via a specific, high-affinity, plasma membrane receptor, i.e., IL-2 receptor. Also, in order to continue to divide, IL-2 dependent T-cells must express the IL-2 receptor and the IL-2 must bind to a portion of the IL-2 receptor, Robb et al., 154 J. Exp. Med. 1455 (1981). A more complete knowledge of the biochemistry of the IL-2 receptor would foster a better understanding of the interaction between IL-2 and T-cells. To date, this has been hampered, at least in part, by the unavailability of sufficient amounts of IL-2 receptor in purified form.
Leonard et al., 300 Nature (London) 267 (November 1982), reported employing a murine monoclonal antibody, designated as anti-Tac, to significantly block the binding of radiolabelled IL-2 to the human lymphoma T-cell line, HUT-102. This antibody resulted from the immunization of mice with long term cultures of human T-cells. The anti-Tac antibody was reported as binding both to a glyco-protein having a molecular weight of about 47,000-53,000 daltons and also to proteins having molecular weights of about 113,000 and 180,000 daltons. Leonard et al. hypothesized, but did not establish, that the cell surface determinant (i.e., the 47,000-53,000 molecular weight protein) to which the anti-Tac antibody bounded to was the IL-2 receptor.
Robb and Green, 158 J. Exp. Med. 1332 (1983), reported employing the anti-Tac antibody in conjunction with mitogen-activated normal lymphocytes to immunoprecipitate a protein having a molecular weight of about 52,000-57,000 daltons. They found that this same protein also bound to IL-2. These researchers opined that this reactive molecule contained the binding site for IL-2 for normal lymphocytes.
Leonard et al., 80 Proc. Natl. Acad. Sci. (USA) 6957 (1983) observed that receptors recognized by anti-Tac antibody on HUT-102 cells and on phytohemaggelutinin-activated normal T-cells appear to be larger on reducing gels than on nonreducing gels, thus suggesting the presence of intrachain disulfide bonds. Also, the HUT-102 cell receptor was reported to exhibit an isoelectric point of from 5.5 to 6.0. From post-translational studies, Leonard et al. suggested that the HUT-102 receptor is composed of a peptide backbone of 33,000 daltons that is initially glycosylated by an N-linked mechanism to achieve a 35,000-37,000 daltons doublet and then glycosylated by an O-linked mechanism to increase the weight of the molecule by about 13,000-15,000 daltons. Although the researchers stated that their studies "suggested" that the HUT-102 cell receptor recognized by the anti-Tac antibody is the human receptor for IL-2, they admitted that actual proof would require purifying the receptor, which prior to the making of the present invention had not been accomplished.
Recombinant DNA techniques have been developed for economically producing a desired protein once the gene coding for protein has been isolated and identified. A discussion of such recombinant DNA techniques for protein production is set forth in the editorial and supporting papers in Vol. 196 of Science (April, 1977). However, to take advantage of the recombinant DNA techniques discussed in these references, the gene coding for the IL-2 receptor must first be isolated.


A compact apparatus for generation of desired pseudorandom sequences with controllable period. The apparatus includes two-dimensional cellular automata for generating a first sequence, 2-by-L cellular automata for generating a second sequence, adders for performing bit-to-bit mod2 sum of the first sequences and the second sequences, and a buffer for buffering the resultant sequences from the adders.

Recently a plurality of methods for generation of pseudorandom sequences with very good statistical characteristics based on employment of cellular automata have been reported. For example, Non-Patent Document 1 discloses two-dimensional cellular automata for generating high quality random number. Below, typical two-dimensional cellular automata (2D-CA) are explained.
Cellular automata (CA) are dynamical systems in which space and time are discrete. A cellular automaton consists of an array of cells, each of which can be in one of a finite number of possible states, updated synchronously in discrete time steps, according to a local, interaction rule. Here, only Boolean automata in which the cellular state, s, ε{0,1} is considered. The state of a cell at the next time step is determined by the current states of a surrounding neighborhood of cells.
The cellular array (grid) is d-dimensional, where d=1, 2, 3, is used in practice. In this section of the present specification, d=2, i.e., two-dimensional grids is considered.
The rule contained in each cell is essentially a finite state machine rule, usually specified in the form of a rule table (also known as the transition function), with an entry for every possible neighborhood configuration of states. The cellular neighborhood of a cell consists of itself and of the surrounding (adjacent) cells. For one-dimensional CAs, a cell is connected to r local neighbors (cells) on either side, where r is referred to as the radius (thus, each cell has 2r+1 neighbors).
For two-dimensional CA (2D-CA), two types of cellular neighborhoods are usually considered. Those are: five cells, consisting of the cell along with its four immediate non-diagonal neighbors (also known as the von Neumann neighborhood) and nine cells, consisting of the cell along with its eight surrounding neighbor. (also known as the Moore neighborhood).
When considering a finite-size grid, cyclic boundary conditions are frequently applied, resulting in a circular grid for the one-dimensional case and in a toroidal one for the two-dimensional case. Fixed, or null, boundary conditions can also be used, in which the grid is surrounded by an outer layer of cells in a fixed state of zero. This latter case is usually easier to implement in hardware.
Non-uniform, or inhomogeneous, cellular automata function in the same way as uniform ones, the only difference being in the cellular rules that need not be identical for all cells. Nonuniform CAs share the basic attractive properties of uniform ones: simplicity, parallelism, and locality.
A suitable background consideration of 2D-CA is available in Non-Patent Document 2, for example.
[Non-Patent Document 1]
M. Tomassini, M. Sipperand, M. Perrenoud, "On the generation of high-quality random number by two-dimensional cellular automata", IEEE Trans. Computers, vol. 49, pp. 1146-1151, October 2000
[Non-Patent Document 2]
P. P. Chaudhuri, D. R. Chaudhuri, S. Nandiand, S. Chattopadhyay, "Additive Cellular Automata: Theory and Applications", New York, IEEE Press, 1997.
[Non-Patent Document 3]
S. Wolfram, "Cryptography with Cellular Automata", Advances in cryptology—CRYPTO85, Lecture Notes in Computer Science, vol. 218, pp. 429-432, 1985
[Non-Patent Document 4]
K. Cattell, S. Zhang, M. Serraand, J. C. Muzio, "2-by-n hybrid cellular automata with regular configuration: Theory and application", IEEE Trans. Computers, vol. 48, pp. 285-295, March 1999
[Non-Patent Document 5]
A. Klimov and A. Shamir, "Cryptographic applications of T-functions", SAC'2003, pre-print 15 pages, August 2003, (to appear in Lecture Notes in Computer Science).
[Non-Patent Document 6]
S.-U. Guan and S. Zhang, "An evolutionary approach to the design of controllable cellular automata: structure for random number generation", IEEE Trans. Evolutionary Computation, vol. 7, pp. 23-36. February 2003.
[Non-Patent Document 7]
P. D. Hortensius, R. D. Mcleod, W. Pries, D. M. Miller and H. C. Card, "Cellular automata-base pseudorandom number generators for built-in self-test", IEEE Transactions on Computer-Aided Design, vol. 8, pp. 842-859, August 1989.
[Non-Patent Document 8]
M. Mihaljevic, M. P. C. Fossorier and H. Imai, "Fast correlation attack algorithm with the list decoding and an application", FSE2001, Lecture Notes in Computer Science, vol. 2355, pp. 196-210, 2002.
[Non-Patent Document 9]
N. T. Courtois and W. Meier, "Algebraic attacks on stream ciphers with linear feedback", EURO-CRYPT2003, Lecture Notes in Computer Science, vol. 2656, pp. 345-359, 2003.
[Non-Patent Document 10]
M. Mihaljevic and H. Imai, "A family of fast keystream generators based on programmable linear cellular automata over GF(q) and time variant table", IEICE Transactions on Fundamentals, vol. E82-A, pp. 32-39, January 1999.
[Non-Patent Document 11]
G. Marsaglia, "Diehard" (1998). http:JJstat.fsu.eduJgeoJdiehard.htm.
[Non-Patent Document 12]
A. K. Das, A. Ganguly, A. Dasgupta, S. Bhawmik, and P. PalChaudhuri, "Efficient characterization of cellular automata", IEE Proc. Pt. E, vol. 137, pp. 81-87, January 1990.
[Non-Patent Document 13]
K. Cattell and J. C. Muzio, "Synthesis of one-dimensional linear hybrid cellular automata", IEEE Trans. Computer-Aided Design, vol. 15, pp. 325-335, March 1996.
[Non-Patent Document 14]
S. Nandi, B. K. Kar and P. Pal Chaudhuri, "Theory and applications of cellular automata in cryptography", IEEE Trans. Comput., vol. 43, pp. 1346-1357, December 1994.
[Non-Patent Document 15]
W. Meier and O. Staffelbach, "Analysis of pseudorandom sequences generated by cellular automata", Advances in Cryptology—EUROCRYPT 91, Lecture Notes in Computer Science, vol. 547, pp. 186-189, 1992.
[Non-Patent Document 16]
C. K. Koc and A. M. Apohan, "Inversion of cellular automata iterations", IEE Proc. Comput. Digit. Tech., vol.-144, pp. 279-284, 1997.
[Non-Patent Document 17]
M. Mihaljevic, "An improved key stream generator based on the programmable cellular automata", ICICS'97, Lecture Notes in Computer Science, vol. 1334, pp. 181-191, 1997.
[Non-Patent Document 18]
M. Mihaljevic, "Security examination of a cellular automata based pseudorandom bit generator using an algebraic replica approach", AAECC12, Lecture Notes in Computer Science, vol. 1255, pp. 250-262, 1997.
[Non-Patent Document 19]
S. R. Blackburn, S. Murphy and K. G. Peterson, "Comments on "Theory and Applications of Cellular Automata in Cryptography"", IEEE Trans. Comput., vol. 46, pp. 637-638, May 1997.
[Non-Patent Document 20]
M. Mihaljevic, "Security examination of a cellular automata based pseudorandom bit generator using an algebraic replica approach", AAECC12, Lecture Notes in Computer Science, vol. 1255, pp. 250-262, 1997.
[Non-Patent Document 21]
A. J. Menezes, P. C. van Oorschot and S. A. Vanstone, Handbook of Applied Cryptography. Boc. Roton: CRC Press, 1997.

Method and apparatus for cellular automata based generation of pseudorandom sequences with controllable period