Global dynamic behavior particularly the bifurcation of periodic orbits of a parallel blower system is studied using a piecewise linear model and the one-dimensional map defined by the Poincare map. First several analytical tools are presented to numerically study the bifurcation process particularly the bifurcation point of the fixed point of the Poincare map. Using two bifurcation diagrams and a bifurcation set, it is shown how periodic orbits bifurcate and leads to chaotic state. It is also shown that the homoclinic bifurcations occur in some parameter regions and that the Li & Yorke conditions of the chaotic state hold in the parameter region which is included in the one where the homoclinic bifurcation occurs. Together with the above, the stable and unstable manifolds of a saddle closed orbit is illustrated and the existence of the homoclinic points is shown.

In this paper, two models for associative memory based on a measure of manhattan length are proposed. First, we propose the two-layered model which has an advantage to its implementation by using PDN. We also refer to the way to improve the recalling ability of this model against noisy input patterns. Secondly, we propose the other model which always recalls the nearest memory pattern in a measure of manhattan length by lateral inhibition. Even if a noise of input pattern is so large that the first model can not recall, this model can recall correctly against such a noisy pattern. We also confirm the performance of the two models by computer simulations.

This article analyzes the property of the fully interconnected neural networks as a method of solving combinatorial optimization problems in general. In particular, in order to escape local minimums in this model, we analyze theoretically the relation between the diagonal elements of the connection matrix and the stability of the networks. It is shown that the position of the global minimum point of the energy function on the hyper sphere in n dimensional space is given by the eigen vector corresponding the maximum eigen value of the connection matrix. Then it is shown that the diagonal elements of the connection matrix can be improved without loss of generality. The equilibrium points of the improved networks are classified according to their properties, and their stability is investigated. In order to show that the change of the diagonal elements improves the potential for the global minimum search, computer simulations are carried out by using the theoretical values. In according to the simulation result on 10 neurons, the success rate to get the optimum solution is 97.5%. The result shows that the improvement of the diagonal elements has potential for minimum search.

We examine the characteristics of the past successful m-valued I2L and ROMs that have been designed and we discuss the reasons of their success and withdraw. We look at the problems associated with scaling of m-valued CMOS current mode circuits. Then we discuss the tolerance issue, the respective propagation delays of binary and m-valued ICs and the interconnection issue. We conclude with the challenges for m-valued circuits in the competition with the exponential performance increase of binary circuits.

A file transmission net N is a directed communication net with vertex set V and arc set B such that each arc e has positive cost ca(e) and each vertex u in V has two parameters of positive cost cv(u) and nonnegative integral demand d(u). Some information to be distributed through N is supposed to have been written in a file and the written file is denoted by J, where the file means an abstract concept of information carrier. In this paper, we define concepts of file transfer, positive demand vertex set U and mother vertex set M, and we consider a problem of distributing d(v) copies of J through a file transfer on N from a vertex v1 to every vertex v in V. As a result, for N such that MU, we propose an O(nm+n2 log n) algorithm, where n=|V| and m=|B|, for synthesizing a file transfer whose total cost of transmitting and making copies of J is minimum on N.

In a display system with a line-of-gaze (LOG) controller, it is difficult to make the directions and motions of a LOG-controlled object coincide as closely as possible in the display with the user's intended LOG-directions and motions. This is because LOG behavior is not only smooth, but also saccadic due to the problem of involuntary eye movement. This article introduces a flexible on-line LOG-control scheme to realize nearly perfect LOG operation. Using a mesh-wise cursor pattern, the first visual experiment elucidates subjectively that a Kalman Filter (KF) for smoothing and predicting is effective in filtering out macro-saccadic changes of the LOG and in predicting sudden changes of the saccade while movement is in progress. It must be assumed that the LOG trajectory can be described by a linear position-velocity-acceleration approximation of Sklansky Model (SM). Furthermore, the second experiment uses a four-point pattern and simulations to scrutinize the two physical properties of velocity and direction-changes of the LOG in order to quantitatively and efficiently resolve "moving" and "gazing". In order to greatly reduce the number of LOG-small-position changes while gazing, the proposed Gaze-Holding algorithm (GH) with a gaze-potential function is combined with the KF. This algorithm allows the occurrence frequency of the micro-saccade to be reduced from approximately 25 Hz to 1 or 2 Hz. This great reduction in the frequency of the LOG-controlled object moves is necessary to achieve the user's desired LOG-response while gazing. Almost perfect LOG control is accomplished by the on-line SM+KF+GH scheme while either gazing or moving. A menu-selection task was conducted to verify the effectiveness of the proposed on-line LOG-control method.

This paper proposes a new admission control strategy for ATM networks, which is based on the simulation approach and regression results. Instead of using many traffic descriptors, in our strategy only numbers of connections of different types are needed in performing admission control. The strategy is evaluated from different points of view, real-time, safety, policing and its efficiency which is referred as allowed utilized bandwidth. Since the admission criteria is developed in a form of regression model, the computation of performance for accepting a new connection is quick and easy. Using the confidence region in statistics to represent the admission criteria, a conservative estimation of performance can be achieved. Besides, this strategy is quite independent, thus can be compatible with most policing functions. Finally, its bandwidth utilization is found to be above 0.54. However, the success of this strategy still depends on the reality of input traffic model. Whenever the traffic can be clearly described, the proposed strategy can be easily and precisely applied. Therefore, we also build a traffic model for different type of traffic including constant-bit-rate (CBR), variable-bit-rate (VBR) and bursty traffic. The application of the proposed strategy to different multiplexing schemes, like priority queues and polling system, etc., should be further studied. Considering different level of performance requirement for different type of traffic, which should aid the bandwidth utilization of this strategy, is also an interesting research issue.

In conventional trellis coded modulation (TCM), a bit rate of m/m+1 convolutional encoder is employed for n information bits (mn), where 2n+1 signal points are required. In this paper, we propose a novel TCM system using totally overlapped signal sets (TO-TCM), i.e., each signal point is used twice. Thus, TO-TCM can realize only half signal points (2n) comparing with those of a conventional TCM system (2n+1), and it is possible to implement a coded modulation system without doubling the signal points by an insertion of redundant bits. The cases of the proposed schemes which have a process to extend the minimum free distances between the signal points can achieve a considerable coding gain in comparison to the traditional uncoded systems with 2n signal points. Moreover, as the proposed scheme needs only half signal points (2n) of those of conventional TCM, the average power is lower and it is less sensitive to the carrier phase offset.

This letter describes a new input and cross-point buffering matrix switching architecture for high-speed ATM switching systems. The proposed switch has input queuing buffers at each input port, and small size buffers for output port arbitration at each cross-point. These two types of buffers share loads using a simple and high-speed retry algorithm. Hardware size is only half that of conventional cross-point buffering switches. In addition, the switch achieves high-throughput at a condition that the switching speed matches the input and output port speed. This switch is expected to enable the development of high-speed ATM switching systems with each port supporting speeds in excess of 1Gbit/s.

Asynchronous Transfer Mode (ATM) is an information transport technique that well supports Broadband ISDN (B-ISDN). One unsolved problem to the perfection of ATM networks is to provide a testing environment that conforms to some standardized network management scheme. From this point of view, remotely controlled virtual path testing is considered in this paper. Remotely controlled virtual path testing should be executed through the standardized Telecommunications Management Network (TMN) model, which employs the OSI systems management concept as the basis of information exchange. Thus, this paper addresses the two issues that arise when OSI systems management standards are applied to virtual path testing. One issue is to define relevant information models. The other issue is to provide test resources with a concurrency control mechanism that guarantees a consistent test environment without causing deadlocks. To resolve these issues, technical requirements are clarified for the remote control of test resources. Next, alternatives to the concurrency control mechanism are shown and compared through computer simulations. A method of defining information models is then proposed. The proposed method ensures the easy storage and retrieval of intermediate test results as well as permitting the effective provision of concurrency control for test resources. An application scenario is also derived. The scenario shows that tests can be executed by using standardized communication services. These results confirm that virtual path testing can be successfully achieved in conformance with the OSI systems management standards.

A fail-safe logic operation refers to such a processing operation that the output assumes the logical value zero when the operation circuit fails. The fail-safe multiple-valued logic operation is proposed as one method of logic operation. Section 2 defines the fail-asfe multiple-valued logic operation and presents an example of method for accomplishing the fail-safe multiple-valued logic operation. Section 3 describes the method of designing a fail-safe threshold operation device (window comparator) as basic device in the fail-safe multiple-valued logic operation in consideration of LSI implementation and shows an example of prototype fail-safe window comparator. This operation device has higher and lower thresholds. It oscillates and produces an operational output signal only when the input signal level falls between the higher and lower thresholds. Unless the fail-safe window comparator is supplied with input signals of higher voltage than the power supply voltage, it dose not form a feedbadk loop as required for it to oscillate. This characteristic prevents the device from erroneously producing an output signal when any failure occurs in the amplifiers comprising the oscillation circuit. The window comparator can be built as a fail-safe threshold operation device. The fail-safe characteristic is utilized in its LSI implementation. Section 4 verifies the fail-safe property of the prortotype fail-safe window comparator. It is shown that even when the LSI develops failures not evident from outsid (latent failures), it does not lose the operational function and maintains the fail-safe characteristic.

A new method is proposed for automatically evaluating the English pronunciation quality of non-native speakers. It is assumed that pronunciation can be rated using three criteria: the static characteristics of phonetic spectra, the dynamic structure of spectrum sequences, and the prosodic characteristics of utterances. The evaluation uses speech recognition techniques to compare the English words pronounced by a non-native speaker with those pronounced by a native speaker. Three evaluation measures are proposed to rate pronunciation quality. (1) The standard deviation of the mapping vectors, which map the codebook vectors of the non-native speaker onto the vector space of the native speaker, is used to evaluate the static phonetic spectra characteristics. (2) The spectral distance between words pronounced by the non-native speaker and those pronounced by the native speaker obtained by the DTW method is used to evaluate the dynamic characteristics of spectral sequences. (3) The differences in fundamental frequency and speech power between the pronunciation of the native and non-native speaker are used as the criteria for evaluating prosodic characteristics. Evaluation experiments are carried out using 441 words spoken by 10 Japanese speakers and 10 native speakers. One half of the 441 words was used to evaluate static phonetic spectra characteristics, and the other half was used to evaluate the dynamic characteristics of spectral sequences, as well as the prosodic characteristics. Based on the experimental results, the correlation between the evaluation scores and the scores determined by human judgement is found to be 0.90.

This paper describes a text-independent speaker recognition method using predictive neural networks. For text-independent speaker recognition, an ergodic model which allows transitions to any other state, including selftransitions, is adopted as the speaker model and one predictive neural network is assigned to each state. The proposed method was compared to quantization distortion based methods, HMM based methods, and a discriminative neural network based method through text-independent speaker identification experiments on 24 female speakers. The proposed method gave the highest identification rate of 100.0%, and the effectiveness of predictive neural networks for representing speaker individuality was clarified.

The Memory-Based Reasoning (MBR) is one of the mainstay approaches in massively parallel artificial intelligence research. However, it has not been explored from the viewpoint of hardware implementation. This paper demonstrates high robustness of the MBR, which is suitable for hardware implementation using Wafer Scale Integration (WSI) technology, and proposes a design of WSI-MBR hardware. The robustness is evaluated by a newly developed WSI-MBR simulator in the English pronunciation reasoning task, generally known as MBRTalk. The results show that defects or other fluctuations of device parameters have only minor impacts on the performances of the WSI-MBR. Moreover, it is found that in order to get higher reasoning accuracy, the size of the MBR database is much more crucial than the computation resolution. These features are proved to be caused by the fact that MBR does not rely upon each single data unit but upon a bulk data set. Robustness in the other MBR tasks can be evaluated in the same manner as discussed in this paper. The proposed WSI-MBR processor takes advantage of benefits discovered in the simulation results. The most area-demanding circuits--that is, multipliers and adders--are designed by analog circuits. It is expected that the 1.7 million processors will be integrated onto the 8-inch silicon wafer by the 0.3 µm SRAM technology.

We consider an asymptotically sparsely encoded associative memory. Patterns are encoded by n-dimensional vectors of 1 and 1 generated randomly by a sequence of biased Bernoulli trials and stored in the network according to Hebbian rule. Using a heuristic argument we derive the following capacities:c(n)ne/4k log n'C(n)ne/4k(1e)log n'where, 0e1 controls the degree of sparsity of the encoding scheme and k is a constant. Here c(n) is the capacity of the network such that any stored pattern is a fixed point with high probability, whereas C(n) is the capacity of the network such that all stored patterns are fixed points with high probability. The main contribution of this technical paper is a theoretical verification of the above results using the Poisson limit theorems of exchangeable events.

In this paper we propose a new timing optimization technique for multi-level networks by restructuring multiple nodes simultaneously. Multi-output subcircuits on critical paths are extracted and resynthesized so that the delays of the paths are reduced. The complete design space of the subcircuits is captured by Boolean relations, which allow us to perform more powerful resynthesis than previous approaches using don't cares. Experimental results are reported to show the effectiveness of the proposed technique.

Broadband ISDN, using asynchronous transfer mode, are expected to carry traffic of different classes, each with its own set of traffic characteristics and performance requirements. To achieve the quality of service in ATM networks, a suitable buffer management scheme is needed. In this paper, we propose a buffer management scheme using a priority service discipline to improve the delay time of delay-sensitive class and the packet loss ratio of loss-sensitive class. The proposed priority scheme requires simple buffer management logic and minor processing overhead. We also analyze the delay time and the packet loss ratio for each class of service. The results indicate that the required buffer size of the proposed priority scheme is reduced and the delay time of each class of service is controlled by a parameter. If the control parameter is appropriately chosen, the quality of service of each class is improved.

When we study time-domain electromagnetic fields, we frequently use the finite-difference time-domain (FD-TD) method. In this paper, we discuss errors of the FD-TD method and present the optimum mesh spacings in the FD-TD method when the three mesh spacings are different.

Two computational-geometric approaches to linear programming are surveyed. One is based on the prune-and-search paradigm and the other utilizes randomization. These two techniques are quite useful to solve geometric problems efficiently, and have many other applications, some of which are also mentioned.