This paper proposes a methodology for fine evaluation of the uncertain behaviors of systems affected by any fluctuation of internal structures and internal parameters, by the use of a new concept on the fuzzy mapping. For a uniformly convex real Banach space X and Y, a fuzzy mapping G is introduced as the operator by which we can define a bounded closed compact fuzzy set G(x,y) for any (x,y)∈X×Y. An original system is represented by a completely continuous operator f defined on X, for instance, in a form xλ(f(x)) by a continuous operator λ: YX. The nondeterministic fluctuations induced into the original system are represented by a generalized form of the fuzzy mapping equation xG_β (x,f(x)) {ζX|µ_G(x,f(x))(ζ)β}, in order to give a fine evaluation of the solutions with respect to an arbitrarily–specified β–level. By establishing a useful fixed point theorem, the existence and evaluation problems of the "β–level-likely" solutions are discussed for this fuzzy mapping equaion. The theory developed here for the fluctuation problems is applied to the fine estimation of not only the uncertain behaviors of system–fluctuations but also the validity of system–models and -simulations with uncertain properties.

It is shown that a self–recurrent fuzzy inference can cause chaotic responses at least three membership functions, if the inference rules are set to represent nonlinear relations such as pie–kneading transformation. This system has single input and single output both with crisp values, in which membership functions is taken to be triangular. Extensions to infinite memberships are proposed, so as to reproduce the continuum case of one–dimensional logistic map f(x)=Ax(1–x). And bifurcation diagrams are calculated for number N of memberships of 3, 5, 9 and 17. It is found from bifurcation diagrams that different periodic states coexist at the same bifurcation parameter for N9. This indicates multistability necessarily accompanied with hysteresis effects. Therefore, it is concluded that the final states are not uniquely determined by fuzzy inferences with sufficiently large number of memberships.

A new algorithm, which is incorporated into the waveform relaxation analysis, for efficiently simulating the transient response of single lossy transmission lines or lossy coupled multiconductor transmission lines, terminated with arbitrary networks will be presented. This method exploits the inherent delay present in a transmission line for achieving simulation efficiency equivalent to obtaining converged waveforms with a single iteration by the conventional iterative waveform relaxation approach. To this end we propose 'line delay window partitioning' algorithm in which the simulation interval is divided into sequential windows of duration equal to the transmission line delay. This window scheme enables the computation of the reflected voltage waveforms accurately, ahead of simulation, in each window. It should be noted that the present window partitioning scheme is different from the existing window techniques which are aimed at exploiting the non–uniform convergence in different windows. In contrast, the present window technique is equivalent to achieving uniform convergence in all the windows with a single iteration. In addition our method eliminates the need to simulate the transmission line delay by the application of Branin's classical method of characteristics. Further, we describe a simple and efficient method to compute the attenuated waveforms using a particular form of lumped element model of attenuation function. Simulation examples of both single and coupled lines terminated with linear and nonlinear elements will be presented. Comparison indicates that the present method is several times faster than the previous waveform relaxation method and its accuracy is verified by the circuit simulator PSpice.

In this paper we propose a formal linearization method which permits us to transform nonlinear systems into linear systems by means of the Chebyshev interpolation. Nonlinear systems are usually represented by nonlinear differential equations. We introduce a linearizing function that consists of a sequence of the Chebyshev polynomials. The nonlinear equations are approximated by the method of Chebyshev interpolation and linearized with respect to the linearizing function. The excellent characteristics of this method are as follows: high accuracy of the approximation, convenient design, simple operation, easy usage of computer, etc. The coefficients of the resulting linear system are obtained by recurrence formula. The paper also have error bounds of this linearization which show that the accuracy of the approximation by the linearization increases as the order of the Chebyshev polynomials increases. A nonlinear filter is synthesized as an application of this method. Numerical computer experiments show that the proposed method is able to linearize a given nonlinear system properly.

Some qualitative properties of an inductively coupled circuit containing two Josephson junction elements with a dc source are investigated. The system is described by a four–dimensional autonomous differential equation. However, the phase space can be regarded as S¹×R³ because the system has a periodicity for the invariant transformation. In this paper, we study the properties of periodic solutions winding around S¹ as a bifurcation problem. Firstly, we analyze equilibria in this system. The bifurcation diagram of equilibria and its topological classification are given. Secondly, the bifurcation diagram of the periodic solutions winding around S¹ are calculated by using a suitable Poincar mapping, and some properties of periodic solutions are discussed. From these analyses, we clarify that a periodic solution so–called "caterpillar solution" is observed when the two Josephson junction circuits are weakly coupled.

We investigate chaotic dynamics due to the homoclinic points observed from a widely used phase–locked loops operating as a frequency–modulated demodulator. Our purpose is to obtain parameter region of the homoclinic points using Melnikov method in a periodically-forced second–order nonlinear nonautonomous equation representing phase–locked loops. If the PLL equation has large damping (actually, this is the case of standard PLL), the unperturbed system becomes non–Hamiltonian. Therefore, one cannot obtain the saddle loop analytically in general, and hence it is very difficult to apply Melnikov method to such a system. Since the current PLL used in practice has a triangular phase detector (i.e., a periodic triangular shaped function) as its nonlinearity, we can use piecewise–linear method, and thus we are succeeded in deriving both the saddle loop and the Melnikov integral analytically even in the PLL equation with practical large damping. We have obtained many boundary curves for homoclinic tangency for a wide range of damping coefficients and modulation frequency. In particular, we treat the general case of β2ζ in this paper where β denotes the normalized natural frequency and ζ denotes the damping coefficient. We compare this results with our previous totally numerical results and have found that this method gives more accurate boundary curves than our previous method.

In this paper, we subjects the case that frequency–shift–keying (FSK) modulation and phase locked loop (PLL) demodulator are used in frequency hopped spread spectrum (FH–SS) communication system. So the carrier frequencies of undesired transmitters may come into collision with the carrier frequency of desired transmitter in this communication system, we evaluate the response of PLL by two sinusoidal inputs so as to estimate how the response of PLL demodulator is affected by the collision of carrier frequencies. First, we compute the synchronization diagrams of PLL with two sinusoids. From this, it is indicated that allowable value of amplitude ratio of interference transmitter's signal to disired transmitter's signal decreases with increasing FSK modulation width of desired transmitter. Next, we calculated the output of PLL demodulator with two sinusoids. To this end, it is shown that the allowable value of amplitude ratio is bounded by a constant value even if FSK modulation width is enough small.

The analytic structure of the governing equation for a 2nd order Phase–Locked Loops (PLL) is studied in the complex time plane. By a local reduction of the PLL equation to the Ricatti equation, the PLL equation is analytically shown to have singularities which form a fractal structure in the complex time plane. Such a fractal structure of complex time singularities is known to be characteristic for nonintegrable, especially chaotic systems. On the other hand, a direct numerical detection of the complex time singularities is performed to verify the fractal structure. The numerical results show the reality of complex time singularities and the fractal structure of singularities on a curve.

Bifurcations of quasi–periodic responses in an oscillator described by conductively coupled van der Pol equations with a sinusoidal forcing term are investigated. According to the variation of three base frequencies, i.e., two natural frequencies of oscillators and the forcing frequency, various nonlinear phenomena such as harmonic or subharmonic synchronization, almost synchronization and complete desynchronization are ovserved. The most characteristic phenomenon observed in the four–dimensional nonautonomous system is the occurrence of a double Hopf bifurcation of periodic solutions. A quasi–periodic solution with three base spectra, which is generated by the double Hopf bifurcation, is studied through an investigation of properties of limit cycles observed in an averaged system for the original nonautonomous equations. The oscillatory circuit is particularly motivated by analysis of human circadian rhythms. The transition from an external desynchronization to a complete desynchronization in human rest–activity can be referred to a mechanism of the bifurcation of quasi–periodic solutions with two and three base spectra.

In this paper we study the bifurcation phenomena of quasi–periodic states of a model of the human circadian rhythm, which is described by a system of coupled van der Pol equations with a periodic external forcing term. In the system a periodic or quasi–periodic solution corresponds to a synchronized or desynchronized state of the circadian rhythm, respectively. By using a stroboscopic mapping, called a Poincar mapping, the periodic or quasi–periodic solution is reduced to a fixed point or an invariant closed curve (ab. ICC). Hence we can discuss the bifurcations for the periodic and quasi–periodic solutions by considering that of the fixed point and ICC of the mapping. At first, the geometrical behavior of the 3 generic bifurcations, i.e., tangent, Hopf and period doublig bifurcations, of the periodic solutions is given, Then, we use a qualitative approach to bring out the similar behavior for the bifurcations of the periodic and quasi–periodic solutions in the phase space and in the Poincarsection respectively. At last, we show bifurcation diagrams concerning both periodic and quasi–periodic solutions, in different parameter planes. For the ICC, we concentrate our attention on the period doubling cascade route to chaos, the folding of the parameter plane, the windows in the chaos and the occurrence of the type I intermittency.

Binary sequences with good correlation properties are required for a variety of engineering applications. We previously proposed simple methods to generate binary sequences based on chaotic nonlinear maps. In this paper, statistical properties of chaotic binary sequences generated by Chebyshev maps are discussed. We explicitly evaluate the correlation functions by means of the ensemble–average technique based on the Perron–Frobenius (P–F) operator. As a consequence, we can confirm an important role of the P–F operator in evaluating statistics of chaos by means of the ensemble-average technique.

A systematic method for locating and computing branches of connecting orbits developed by the authors is outlined. The method is applied to the sine–Gordon and Hodgkin–Huxley equations.

Numerical studies of reaction–diffusion systems which consist of chaotic oscillators are carried out. The Rössler oscillators are used, which are arranged two–dimensionally and coupled by diffusion. Pacemakers where the average periods of the oscillators are artificially changed are set to produce target patterns. It is found that target patterns emerge from pacemakers and grow up as if they were in a regular oscillatory medium. The wavelength of the pattern can be varied and controlled by changing the parameters (size and frequency) of the pacemaker. The behavior of the coupled system depends on the size of the system and the strength of the pacemaker. When the system size is large, the Poincar return maps show that the behavior of the coupled system is not simple and the orbit falls into a high–dimensional attractor, while for a small system the attractor is rather simple and a one–dimensional map is obtained. Moreover, for appropriate strength of pacemakers and for certain sizes of the systems the oscillations become periodic. It is also found that the largest and local Lyapunov exponents of the system are positive and these values are uniformly distributed over the pattern. The values of the exponents are smaller than that of the uncoupled Rössler oscillator; this is due to the fact that the diffusion reduces the exponents and modifies the form of the attractor. We conclude that the large scale patterns can stably exist in the chaotic medium.

More than 200 papers, two special issues (Journal of Circuits, Systems, and Computers, March, June, 1993, and IEEE Trans. on Circuits and Systems, vol.40, no.10, October 1993), an International workshop on "Chua's Circuit: chaotic phenomena and applications" at NOLTA'93, and a book (Edited by R. N. Madan, World Scientific, 1993) on Chua's circuit have been published since its inception a decade ago. This review paper attempts to present an overview of these timely publications, almost all within the last 6 months, and to identify four milestones of this very active research area. An important milestone is the recent fabrication of a monolithic Chua's circuit. The robustness of this IC chip demonstrates that an array of Chua's circuits can also be fabricated into a monolithic chip, thereby opening the floodgate to many unconventional applications in information technology, synergetics, and even music. The second milestone is the recent global unfolding of Chua's circuit, obtained by adding a linear resistor in series with the inductor to obtain a canonical Chua's circuit--now generally referred to as Chua's oscillator. This circuit is most significant because it is structurally the simplest (it contain only 6 circuit elements) but dynamically the most complex among all nonlinear circuits and systems described by a 21–parameter family of continuous odd–symmetric piecewise–linear vector fields. The third milestone is the recent discovery of several important new phenomena in Chua's Circuits, e.g., stochastic resonance, chaos–chaos type intermittency, 1/f noise spectrum, etc. These new phenomena could have far-reaching theoretical and practical significance. The fourth milestone is the theoretical and experimental demonstration that Chua's circuit can be easily controlled from a chaotic regime to a prescribed periodic or constant orbit, or it can be synchronized with 2 or more identical Chua's circuits, operating in an oscillatory, or a chaotic regime. These recent breakthroughs have ushered in a new era where chaos is deliberately created and exploited for unconventional applications, e.g., secure communication.

It is known that homogeneous networks are ones which perform parallel algorithms, and the dynamics of neural networks are applied to practical problems including combinatorial optimization problems. Both homogeneous and neural networks are parallel networks, and are composed of Boolean elements. Although a large number of studies have been made on the applications of homogeneous threshold networks, little is known about the relation of the dynamics of these networks. In this paper, some results about the dynamics, used to find the lengths of periodic and transient sequences, as built by parallel networks including threshold and homogeneous networks are shown. First, we will show that for non–restricted parallel networks, threshold networks which permit only two elements to transit at each step, and homogeneous networks, it is possible to build periodic and transient sequences of almost any lengths. Further, it will be shown that it is possible for triangular threshold networks to build periodic and transient sequences with short lengths only. As well, homogeneous threshold networks also seem to build periodic and transient sequences with short lengths only. Specifically, we will show a sufficient condition for symmetric homogeneous threshold networks to have periodic sequences with the length 1.

This paper proposes new real–time heuristic distributed parallel algorithms for search, which are based on the concepts of propagations and competitions of concurrent waves. These algorithms are characterized by simplicity and clearness of control strategies for search, and distinguished abilities in many aspects, such as real–time performance, wide suitability for searching AND/OR implicit graphs, and ease in hardware implementation.

We introduce recurrent networks that are able to learn chaotic maps, and investigate whether the neural models also capture the dynamical invariants (Correlation Dimension, largest Lyapunov exponent) of chaotic time series. We show that the dynamical invariants can be learned already by feedforward neural networks, but that recurrent learning improves the dynamical modeling of the time series. We discover a novel type of overtraining which corresponds to the forgetting of the largest Lyapunov exponent during learning and call this phenomenon dynamical overtraining. Furthermore, we introduce a penalty term that involves a dynamical invariant of the network and avoids dynamical overtraining. As examples we use the Hnon map, the logistic map and a real world chaotic series that correspond to the concentration of one of the chemicals as a function of time in experiments on the Belousov–Zhabotinskii reaction in a well–stirred flow reactor.

We have classified parenchymal echo patterns of cirrhotic liver into 3 types, according to the size of hypoechoic nodular lesions. We have been studying an ultrasonic image diagnosis system using the three–layer back–propagation neural network. In this paper, we will describe the applications of the neural network techniques for recognizing and classifying chronic liver disease, which use the nodular lesions in the Proton density and T2–weighed magnetic resonance images on the gray level of the pixels in the region of interest.

A novel optoelectronic mesoscopic neural device is proposed. This device operates in a neural manner, involving the electron interference and the laser threshold characteristics. The optical output is a 2–dimensional image, and can also be colored, if the light emitting elements are fabricated to form the picture elements in 3–colors, i.e. R, G, and B. The electron waveguiding in the proposed device is analyzed, on the basis of the analogy between the Schrödinger's equation and the Maxwell's wave equation. The nonlinear neural connection is achieved, as a result of the superposition an the interferences among electron waves transported through different waveguides. The sizes of the critical elements of this device are estimated to be within the reach of the present day technology. This device exceeds the conventional VLSI neurochips by many orders of magnitude, in the number of neurons per unit area, as well as in the speed of operation.

This paper discusses the characteristics of the nonlinearly amplified spread–spectrum (SS) signals. We evaluate the symbol error–rate performance with the conventional receiver, changing the length of the spreading sequence. In addition, we also propose the receiver with MLSE. The configuration of the MLSE for the nonlinearly amplified signals is generally complicated; however we show that the complexity of the MLSE receiver can be reduced, as the number of required reference sequences in the receiver for an SS signal is small. As the result, it is shown that the error rate performance of the nonlinearly amplified SS signal can be improved by this proposed receiver and that the degradation caused by the nonlinear amplification can be made negligibly small with a sufficiently long spreading sequence.

A new leaky surface wave on lithium tetraborate that propagates along the surface with a higher phase velocity than that of ordinary leaky surface waves, radiating two bulk wave terms into the solid, is described.

By applying Wigner distribution, which has high time resolution and high random noise reducing capability, to the acoustic bio–signals, the possibility of early diagnosis in both intracranial vascular deformation and prosthetic cardiac valve malfunction increased. Especially in latter case, 1st–order local moment of the distribution showed its effectiveness.

For the purpose of detecting the intracranial vascular deformations noninvasively, transducer for bruit sound emanated from diseased lesion and analyzing system were developed and applied clinically. Several aspects of the bruit signals were clarified and the possibility of early diagnosis was increased.

The mechanical impedance of silicone–gel model or chest surface has been measured and the viscoelasticity and effective vibrating radius have been obtained from the impedance. They depend on the distance between the internal block of the silicone–gel/ribs of right chest and the gel surface/skin surface. The 3–D image of internal structure is reconstructed, based on the relation between the distance from the surface and the effective vibrating radius.

We propose two methods to fuse auditory information and visual information for accurate sppech recognition. The first method fuses two kinds of information by using linear combination after calculating two kinds of probabilities by HMM for each word. The second method fuses two kinds of information by using the histogram which expresses the correlation of them. We have performed experiments comparing the proposed methods with the conventional method and confirmed the validity of the proposed methods.

This paper describes that a neural network, which consists of neurons with piecewise–linear sigmoid characteristics, is able to approximate any piecewise–linear map with origin symmetry. The neural network can generate "deterministic diffusion" originating from its diffusive trajectory.

In this letter we present an electronic circuit based on a neural net to compute the discrete Walsh transform. We show both analytically and by simulation that the circuit is guaranteed to settle into the correct values.

This letter presents the results of an analysis concerning the global, dynamical structure of a second order phase–locked loop (PLL) in the presence of the continuous wave (CW) interference. The invariant manifolds of the PLL equation are focused and analyzed as to how they are extended from the hyperbolic periodic orbits. Using the Melnikov integral which evaluates the distance between the stable manifolds and the unstable manifolds, the transversal intersection of these manifolds is proven to occur under some conditions on the power of the interference and the angular frequency difference between the signal and the interference. Numerical computations were performed to confirm the transversal intersection of the system–generated invariant manifolds for a practical set of parameters.

This paper describes a segmentation method of liver structure from abdominal CT images using a three–layered neural network (NN). Before the NN segmentation, preprocessing is employed to locally enhance the contrast of the region of interest. Postprocessing is also automatically applied after the NN segmentation in order to remove the unwanted spots and smooth the detected boundary. To evaluate the performance of the proposed method, the NN–determined boundaries are compared with those traced by two highly trained surgeons. Our preliminary results show that the proposed method has potential utility in automatic segmentation of liver structure and other organs in the human body.

An optimal control theory has been applied to a biological compartment system to show a method to analyze the control principle of biological system represented by compartments. Present theory has been proposed to afford a theoretical back ground and validity for the strategy of drug administration or control of the anesthetic agent in practical medicine. The instantaneous change of the concentration of a given material within a biological system has been expressed by differential equations. Each compartment has been set to be transferred a material from all other compartments and conversely each compartment sends it to all other compartments. The control input was restricted to be one kind. The performance function involved the deviation from the target value, the rate of change in concentration and the amount of the control variables. The biological system was defined to operate optimally only when the performance function has been minimized during a given time period. By the optimal control theory of Pontoriagin, above biological problem has been converted to a mathematical problem and was solved numerically by multiple shooting method. The calculated trajectory of the optimal control has been asymmetric parabolic one with the maximum at its initiation and the minimum at the middle of total reaction time. This pattern has been consistent with that of probable transient change of the concentration of anesthetic agent when it has been inhalated under the most up to date "Rapid Inhalation Induction" method. The optimal trasient change of the concentration at each compartment has beeb affected by the difference in time dependent nature and the magnitude of the transfer rate. Present theory afforded a method to analyze the control strategy of biological system expressed by compartments model and showed an availability for actual clinical medicine. The optimal control principle must be a most adequate one to describe the Homeostasis in biological system.

This letter proposes the method using a filter to suppress the very large noise obstructive to the radio pulsar surveys. This noise suppression filter is constructed from the average of the amplitude spectrum of pulsar signal for each channel. Using this method, the dispersion measure, one of the important parameters in the pulsar surveys, can easily be extracted.

Fractal image coding using iterated transformations compresses image data by exploiting the self–similarity of an image. Its compression performance has already been discussed in [2] and several other papers. However the relation between the performance and the self–similarity remains unclear. In this paper, we evaluate fractal coding from the perspective of this relationship.

We discuss a processor scheduling problem for parallel logic simulation of combinational circuits. In the processor scheduling problem, to be discussed in this paper, for logic simulation using time–first method, the time needed for each gate evaluation is not given beforehand, and is not constant. This feature distinguishes the processor scheduling problem from typical task scheduling problems. First, we devise newly Algorithm MET to solve the processor scheduling problem. The key idea of Algorithm MET is to determine processor scheduling incrementally and dynamically. Then, experimental evaluations using well–known twelve benchmark combinational circuits show the usefulness of Algorithm, MET, compared with conventional static algorithms. We believe that this is a first step to implement parallel logic simulation of combinational circuits.

In this paper, the power dissipation issue is considered in the gate sizing procedure. In order to observe the tradeoff among area, delar and power dissipation in a circuit, gate sizing algorithms which can minimize power under delay constraints or minimize area under power and delay constraints are formulated. Experiments are performed to investigate the properties of area–power–delay tradeoff in the gate sizing procedure.

We propose an optimal throughput problem using graph transformations to maximize throughput of a pipelined data path with some loops. The upper bound of the throughput, equals to the lower bound of the iteration interval between the start of two successive iterations, is limited by the length of a critical loop. Therefore we can maximize the throughput by minimizing the length of the critical loop. The proposed method first schedules an initial Data Flow Graph (DFG) under the initial iteration interval as few as it can use resources, then it transforms the DFG into the flow graph with the minimal length of the critical loop by rescheduling the given initial scheduling result. If there are any control steps which violate the resource constraints owing to the transformations, then these operations are adjusted so as to satisfy given resource consrtraints. Finally by rescheduling the transformed DFG, it gives a schedule with maximum throughput. Experiments show the efficiency of our proposed approach.

An emitter–coupled pair with a dynamic bias current and a source–coupled pair with a dynamic bias current are proposed as an exponential–law element and a square–law element that operate as a floating bipolar junction transistor (BJT) and a floating MOS field–effect transistor (MOSFET). In bipolar technology, a hyperbolic sine function circuit and a hyperbolic cosine function circuit are easily obtained by subtracting and summing the output currents of two symmetrical exponential–law elements with positive and negative input signals. In the same manner, an operational transconductance amplifier (OTA) and a squaring circuit are obtained by subtracting and summing the output currents of two symmetrical square-law elements with positive and negative input signals in CMOS technology. The proposed OTA and squaring circuit possess the widest input voltage range ever reported.

A MOS VCO which has improved linearity of oscillation frequency versus control voltage and has no 1/2 divider is studied. The improved VCO characteristic has been obtained by the use of only two additional transistors, one of which has a role of a load and another of which has a role of a control current source in a differential type delay cell.

This paper proposes a new class of unidirectional byte error locating codes, called single symmetric bit error correcting and single unidirectional byte error locating codes, or SEC–SUbEL codes. Here, "byte" denotes a cluster of b bits, where b2. First, the necessary and sufficient conditions of the codes are clarified, and then code construction method is demonstrated. The lower bound on check bit length of the SEC–SUbEL codes is derived. Based on this, the proposed codes are shown to be very efficient in some range of the information length. The code design concept presented for the SEC–SUbEL codes induces the generalized unidirectional byte error locating codes with single symmetric bit error correction capability.

The access control method adopted by UNIX is simple, understandable, and useful. However, it is quite possible that unexpected information flows occur when we are cooperating with some group members on UNIX. Introducing notions such as "flow right," "maximal permission" and "minimal umask value", this note proposes a simple method, can be seen as a natural extension of UNIX, to control indirect information flows without losing availability and understandability of UNIX.

Synchronization has been one of the problems in M–ary spread spectrum communication systems. In this letter, we propose the frame synchronization method using the Hadamard matrix and a frame synchronization method of PCM communication systems. Moreover, we analyze the probabilities of keeping synchronous state and frame renewal rates, and we evaluate the relationship between these probabilities and the number of stages of counters.

On ranging system on short distance using spread spectrum, we examine waveform responses to predict the state of electromagnetic waveform propagation while the signal is received after scattered by a target. Then this system and the numerical results are discussed.

An efficient full–wave spectral domain moment method is developed to compute the current distribution and the radiation associated with microstrip discontinuities. Two techniques are used to increase the efficiency of the method of moments algorithm so that a transmission line of moderate electrical size can be analyzed in reasonable time.

The design theory was revealed by theoretical analysis of the measuring apparatus, and was confirmed experimentally. Higher quality tags having new circuit disigns were proposed by the revealed theory. The measuring apparatus equivalent to the security system was produced to estimate the properties of the LC resonant circuit security tags quantitatively.

Precise measurements of temperature dependence of the Andreev reflection current for the N–I–S junctions were carried out. Au and Pb were used as N (normal metal) and S (superconducting material), respectively. The experimental results agreed with the analyses based on the Arnold theory.

This paper describes a procedural detailed compaction method for the symbolic layout design of CMOS leaf cells and its algorithmic aspects. Simple symbolic representations that are loosely designed by users in advance are automatically converted into densely compacted physical patterns in two phases: symbolic–to–pattern conversion and segment–based detailed compaction. Both phases are executed using user-defined procedures and a specified set of design rules. The detailed compaction utilizes a segment–based constraint graph generated by an extended plane sweep method where various kinds of design rules can be applied. Since various kinds of basic operations can be applied to the individual segments of patterns in the procedures, the detailed procedure for processing can be described in accordance with fabrication process technologies and the corresponding sets of design rules. This combined stepwise procedure provides a highly flexible framework for the symbolic layout of CMOS leaf cells. The proposed approach was implemented in a symbolic layout system called CAMEL. To date, more than 300 kinds of symbolic representations of CMOS leaf cells have been designed and are stored in the database. Using several different sets of design rules, symbolic representations have been automatically converted into compacted patterns without design rule violations. The areas of those generated patterns were averaged at 98% of the manually designed patterns. Even in the worst case, the increases in area were less than about 10% of the manually designed ones. Furthermore, since processing times are much shorter than manual design periods, for example, 300 kinds of symbolic representations can be converted to corresponding physical patterns in only a day. It is evident, through these practical design experiences with CAMEL, that our approach is more flexible and process–tolerant than conventional ones.

We report on an experimental hysteresis in the Hopfield networks and examine the effect of the hysteresis on some important characteristics of the Hopfield networks. The detail mathematic description of the hysteresis phenomenon in the Hopfield networks is given. It suggests that the hysteresis results from fully–connected interconnection of the Hopfield networks and the hysteresis tends to makes the Hopfield networks difficult to reach the global minimum. This paper presents a T–Model network approach to overcoming the hysteresis phenomenon by employing a half–connected interconnection. As a result, there is no hysteresis phenomenon found in the T–Model networks. Theoretical analysis of the T–Model networks is also given. The hysteresis phenomenon in the Hopfield and the T–Model networks is illustrated through experiments and simulations. The experiments agree with the theoretical analysis very well.

Transistor stuck–open faults in CMOS devices are such that they force combinational circuits to exhibit sequential behaviors. It has been proved that, in general, stuck–open faults can not be modeled as stuck–at faults and, therefore, a sequence of two consecutive test vectors is necessary to guarantee stuck–open fault detection. In this paper we propose a technique to modify CMOS circuits in such a way that any stuck–open fault in the circuit can be detected using only a single test pattern. The amount of additional logic required to achieve the goal is rather limited: Two pass transistors, one input line, and one inverter (or buffer) at the output of the circuit are sufficient to make stuck–open faults detectable by test patterns generated by usual stuck–at fault test generators.