Some undetectable stuck-at faults called the redundant faults are included in practical combinational circuits. The redundant fault does not affect the functional behavior of the circuit even if it exists. The redundant fault, however, causes undesirable effects to the circuit such as increase of delay time and decrease of testability of the circuit. It is considered that some redundant faults may cause the logical defects in the future. In this paper, firstly, we study the testability of the redundant fault in the combinational circuit by using delay effects. Secondly, we propose a method for generating a test-pair of a redundant fault by using an extended seven-valued calculus, called TGRF (Test-pair Generation for Redundant Fault). TGRF generates a dynamically sensitizable path for the target line which propagates the change in the value on the target line to a primary output. Finally, we show experimental results on the benchmark circuits under the assumptions of the unit delay and the fanout weighted delay models. It shows that test-pairs for some redundant faults are generated theoretically.

A new clustering method was proposed to increase the effect of duration modeling on the HMM-based phoneme recognition. A precise observation on the temporal correspondences between a phoneme HMM with output probabilities by single Gaussian modeling and its training data indicated that there were two extreme cases, one with several types of correspondences in a phoneme class completely different from each other, and the other with only one type of correspondence. Although duration modeling was commonly used to incorporate the temporal information in the HMMs, a good modeling could not be obtained for the former case. Further observation for phoneme HMMs with output probabilities by Gaussian mixture modeling also showed that some HMMs still had multiple temporal correspondences, though the number of such phonemes was reduced as compared to the case of single Gaussian modeling. An appropriate duration modeling cannot be obtained for these phoneme HMMs by the conventional methods, where the duration distribution for each HMM state is represented by a distribution function. In order to cope with the problem, a new method was proposed which was based on the clustering of phoneme classes with plural types of temporal correspondences into sub-classes. The clustering was conducted so as to reduce the variations of the temporal correspondences in sub-classes. After the clustering, an HMM was constructed for each sub-class. Using the proposed method, speaker dependent recognition experiments were performed for phonemes segmented from isolated words. A few-percent increase was realized in the recognition rate, which was not obtained by another method based on the duration modeling with a Gaussian mixture.

Microwave radiometry has been investigated for non-invasive measurement of temperature in human body. Recent trends are to explore the capability of retrieving a temperature profile or map from a set of brightness temperatures measured by a multifrequency radiometer operating in a 1-6GHz range. The retrieval of temperature from the multifrequency measurement data is formulated as an inverse problem in which the number of independent measurement or data is limited (7) and the data suffer from considerably large random fluctuations. The standard deviation of the data fluctuation is given by the brightness temperature resolution of the instrument (0.04-0.1K). Solutions are prone to instabilities and large errors unless proper solution methods are used. Solution methods developed during the last few years are reviewed: singular system analysis, bio-heat transfer solution matched with radiometric data, and model-fitting combined with Monte Carlo technique. Typical results obtained by these methods are presented to indicate a crosssection of the present-state-of-the-development in the field. This review concludes with discussions on the radiometric weighting function which connects physical temperatures in object to the brightness temperature. Three-dimensional weighting functions derived by the modal analysis and the FDTD method for a rectangular waveguide antenna coupled to a four layered lossy medium are discussed. Development of temperature retrieval procedures incorporating the 3-D weighting functions is an important and challenging task for future work in this field.

Multifrequency microwave radiometry for non-invasive measurement of temperature in biological objects has been investigated in our laboratory. An open-ended rectangular waveguide filled with a dielectric has been used as a contact-type antenna of a radiometer operating over a 1-4GHz range. In the radiometric measurement, the radiometer measures the thermal radiation emitted by the object via the antenna as the brightness temperature. The brightness temperature is related to the physical temperatures in the object through the radiometric weighting function. By virtue of the reciprocity of antenna, the weighting function can be derived from the field distribution induced in the object by the same antenna when it is operated in the active mode. In this paper, the FD-TD method is used to analyze the problem of coupling between the rectangular waveguide antenna and a biological object. The objects studied in this paper are a homogeneous and a four-layered lossy media. Working frequency is 1.2GHz, which is the center frequency of the lowest-frequency band of our radiometer. Numerical results are presented in the form of SAR patterns. It is found that the SAR patterns tend to spread out in the lateral directions in the bolus, skin and fat layers due to the diffraction which becomes stronger at lower frequencies. Results also suggest that the lateral spreading can be controlled to a certain extent by choosing the size elf antenna flange properly.

We develop a software availability model incorporating software failure-occurrence and fault-correction times, under the assumption that the hazard rate for software failure-occurrence decreases geometrically with the progress in fault-removal process. Considering that the software system alternates two states, i.e. the operational state that a system is operating and the maintenance state that a system is inoperable due to the fault-correction activity, we model the time-dependent behavior of the system with a Markov process. Expressions for several quantities of software system perfomance are derived from this model. Finally, numerical examples are presented for illustration of software availability measurement.

An open-ended rectangular waveguide filled with a dielectric has been used as a contact-type antenna of microwave radiometer for non-invasive measurement of temperature in a biological object. In this application, the thermal radiation emitted by the object is measured as the brightness temperature by the instrument via the antenna. The brightness temperature is related to the physical temperatures in the object through the radiometric weighting function. By virtue of the reciprocity of antenna, the weighting function can be derived from the field distribution induced in the object by the antenna when it is operated in the active mode. In this work, we treat a problem of the rectangular waveguide antenna radiating into a four-layered medium by modal analysis. The results are first compared with those obtained by the FD-TD method to indicate that the results of the two methods are in a good agreement. The operation of an antenna used in a radiometer system in our laboratory is analyzed by this method and the weighting functions at different frequencies are computed, and the results are presented along with discussions on the results.

We have developed a new muscle-equivalent phantom which is composed of water, polyethylene powder, NaCl, agar and so on. This phantom can maintain its shape by itself and it is easy to make and handle. The complex permittivity of the phantom is very similar to that of the actual muscle tissue at UHF. The specific heat and thermal conductivity are suitable for the thermographic method.

We describe a formal verification algorithm for pipelined processors. This algorithm proves the equivalence between a processor's design and its specifications by using rewriting of recursive functions and a new type of mathematical induction: extended recursive induction. After the user indicates only selectors in the design, this algorithm can automatically prove processors having more than 10(1010) states. The algorithm is manuary applied to benchmark processors with pipelined control, and we discuss how data width, memory size, and the numbers of pipeline stages and instructions influence the computation cost of proving the correctness of the processors. Further, this algorithm can be used to generate a pipeline invariant.

The recursive least-squares filter and fixed-point smoother are designed in linear discrete-time systems. The estimators require the information of the system matrix, the observation vector and the variances of the state and white Gaussian observation noise in the signal generating model. By appropriate choices of the observation vector and the state variables, the state-space model corresponding to the ARMA (autoregressive moving average) model of order (n,m) is introduced. Here,some elements of the system matrix consist of the AR parameters. This paper proposes modified iterative technique to the existing one regarding the estimation of the variance of observation noise based on the estimation methods of ARMA parameters in Refs. [2],[3]. As a result, the system matrix, the ARMA parameters and the variances of the state and observation noise are estimated from the observed value and its sampled autocovariance data of finite number. The input noise variance of the ARMA model is estimated by use of the autocovariance data and the estimates of the AR parameters and one MA parameter.

This paper describes a parameter extraction system that can easily accommodate many MOSFET models. The model-adaptability is contributed by tow factors; a model-adaptable initial value estimation technique and an environment which stores and reuses extraction procedures. A designer can easily develop an extraction procedure for a new MOSFET model by modifying a procedure for another MOSFET model developed previously. We have verified that the system is suitable for major SPICE models.

This letter addresses stability problems of interval matrices stemming from robustness issues in control theory. A quick overview is first made pertaining to methods to obtain stability conditions of interval matrices, putting particular emphasis upon one of them, regularity condition approach. Then, making use of this approach, several new stability criteria, for both Hurwitz and Schur stability, are derived.

This paper describes a fully digitized modem designed for variable baud rate transmission systems with the aim of efficiently providing multimedia services over a wireless communication network. The concept of a variable baud rate wireless communication system is discussed focusing on the access scheme and channel allocation from the viewpoint of frequency utilization efficiency. For easy system construction, we propose a fully digitized variable baud rate modem based on multirate digital signal processing, taking into account the need for even performance and easy clock control for all transmission rates. We also discuss the operational principle of modulation, the degradation factor in the A/D converter, and the configuration of the clock recovery circuit. Steady modulation performance can be kept by generating the same frequency system clock for all transmission rates and using the sampling rate conversion technique without selecting the channel filter for each transmission rate. It is proved by the analysis of the degradation factor in the A/D converter that only the bandwidth of the channel filter in demodulator should be changed for the transmission rate. A double loop clock recovery configuration capable of both tank-limit type and baseband estimation type clock recovery is shown to be suitable for this system. The tank-limit clock recovery circuits can be constructed easily by employing a tank circuit array. Finally, we present experimental results for a modem having transmission rates of 1.544Mbps and 6.312Mbps for the digital hierarchy and information speed of video signals such as MPEG-1 and MPEG-2. The measured basic performance of the proposed modem shows it delivers superior performance without the need for precise adjustment when a QPSK modulation scheme is employed.

The superconducting magnet on a maglev vehicle vibrate and heats up inside under the influence of various disturbances in running. We have investigated the characteristics of heating in the superconducting magnet vibrating under the electro-magnetic disturbance from the ground coils. This magnetic disturbance has a frequency component ranging widely from 0 Hz to several hundred Hz which is proportional to the speed of the maglev vehicle. It was revealed that an extreme increase of heat load on the inner vessel of the energized magnet occurred at a particular frequency and it surpassed the capacity of the refrigerator installed in the tank of the superconducting magnet. As a result of the investigation, we could identify broadly three factors of heating, and now we have good prospects of largely suppressing the heating by reducing the disturbance through the folded arrangement of the ground coils and a structural improvement of the magnet.

Board-to-board signal transmission in a rack system is affected by various types of noise. Signal transmission capability is evaluated on the basis of physical construction parameters and signal conditions, such as rise time and amplitude. This paper examines noise in a rack system and shows that the maximum single-ended transmission capability is 100Mbps when pin-type connectors are used with a signal/ground pin assignment ratio of 1/1.

In this paper, we propose a method to design ternary cellular arrays by using Ternary Decision Diagrams (TDD's). Our cellular array has a rectangular structure composed of ternary switch cells. The ternary functions represented by TDD's are realized by mapping the TDD's to the arrays directly. That is, both the nodes and the edges in the TDD are realized by some sets of the cells. Since TDD's can represent easily multiple-output functions without large memory requirements, our arrays are wuitable for the realization of multiple-output functions. To evaluate our method, we apply our method to some benchmark circuits, and compare our arrays with the ternary PLA's. The experimental results show that our arrays have the advantage for their sizes, especially in the realization of symmetric functions. The results also clarify that the size of our arrays depends on the size of TDD's.

In this paper, we propose a method, called Kernel Hidden Unit Analysis, to reduce the network size. The kernel hidden unit analysis in composed of two principal components: T-component and S-component. The T-component transforms original networks into the networks which can easily be simplified. The S-component is used to select kernel units in the networks and construct kernel networks with kernel units. For the T-component, an entropy function is used, which is defined with respect to the state of the hidden units. In a process of entropy minimization, multiple strongly inhibitory connections are to be generated, which tend to turn off as many units as possible. Thus, some major hidden units can easily be extracted. Concerning the S-component, we use the relevance and the variance of input-hidden connections and detect the kernel hidden units for constructing the kernel network. Applying the kernel hidden unit analysis to the symmetry problem and autoencoders, we perfectly succeeded in obtaining kernel networks with small entropy, that is, small number of hidden units.

Data communication by using TCP/IP is one of important services on ATM networks. At one approach in traffic control of this service, the dedicated bandwidth for data transfer is not guaranteed and the feedback congestion control to prevent cell loss is performed in the congestion case. However, when a large quantity of data is transferred within a short period, this traffic control cannot be expected to achieve high efficiency. In this case, it is suitable that the dedicated bandwidth is guaranteed by FRP (Fast Reservation Protocol) before the data is transferred. This paper describes that FRP is superior to the feedback congestion control for large size data transmission. Next, it proposes a selectable traffic control which selects adaptively one of the feedback congestion control and FRP.

The recent progress of B-ISDN signaling systems has enabled networks to handle calls which require a wide variety of ATM connection sets. This paper is concerned with the circuit group which handles calls requesting asymmetric forward and backward multi-connections, and has the capability of both bandwidth negotiation and bandwidth reservation as a traffic control for enhancing call blocking performance. A model of the circuit group is first established focusing on the call level characteristics of the group, and then a method based on the reduced load approximation and an approximate analysis of a multirate group is proposed for calculating approximate blocking probabilities. The accuracy of the approximation method is evaluated numerically by comparing with an exact method and simulation. Further the impact of bandwidth negotiation and reservation on call blockings is examined based on numerical examples.

In the actual sound environmental systems, it seems to be essentially difficult to exactly evaluate a whole probability distribution form of its response fluctuation, owing to various types of natural, social and human factors. We have reported a unified probability density expression in the standard expansion form of Hermite type orthonormal series taking a well-known Gaussian probability density function (abbr. p.d.f.) as the basis for generally evaluating non-Gaussian, non-linear correlation and/or non-stationary properties of the fluctuation phenomenon. However, in the real sound environment, there still remain many actual problems on the necessity of improving the above standard type probability expression for practical use. First, a central point in this paper is focused on how to find a new probabilistic theory of practically evaluating the variety and complexity of the actual random fluctuations, especially through newly introducing an equvivalence transformation toward the standard type probability expression mentioned above in the expansion form of Hermite type orthonormal series. Then, the effectiveness of the proposed theory has been confirmed experimentally too by applying it to the actual problems on the response probability evaluation of various sound insulation systems in an acoustic room.

This paper reports an overload control method for the Intelligent Network (IN). The IN, which is being investigated as a future communication network, facilitates both rapid introduction of new services and easy modification of existing services. In the IN, the call processing functions and data needed to achieve IN services are distributed over several nodes. Therefore, traffic demand for the various services may cause varying patterns of node overloads. It is therefore important to develop effective overload control methods and to evaluate their characteristics. We propose an overload control method and evaluate its characteristics in comparison with other methods under various overload traffic patterns with a network simulator that models all nodes and their relationships in the IN. In particular, we focus on three aspects of overload control: how can high throughput be maintained, how can an overloaded node be stabilized, and how can fair access be guaranteed.