A new frequency hopped spread spectrum system is introduced. The frequency hopped signal is a combination of multi frequency and multi phase signals and is referred to as Frequency Hopped/Joint Frequency-Phase Modulation (FH/JFPM). A noncoherent receiver for the FH/JFPM signals is introduced and an exact expression for the bit error rate is obtained. A performance analysis of this system is given in the presence of broadband and partial-band noise jamming. The optimal jamming strategy is evaluated. The results show that under these jamming conditions the FH/JFPM perform better than the FH/M-ary DPSK and FH/M-ary FSK systems. It is also shown that for a given channel bandwidth and data rate, the FH/JFPM system has more processing gain than its FSK or DPSK counterparts.

With the advent of an aging society, the incidence of Alzheimer-type dementia (hereinafter referred to as AD for convenience) has drastically increased. Compared with classic cerebrovascular dementia, AD requires different therapeutic modalities. Despite such differences, it is difficult to establish a differential diagnosis of AD and cerebrovascular dementia. In the present paper, we analyze the neuropsychological symptoms and signs associated with AD, such as visual cognitive dysfunction, with particular attention to head and eye coordination. The subjects were allowed to gaze at targets disposed 1 m away and at a visual angle of 25 and 50 in order to compare healthy volunteers and patients with senile dementias such as multi-infarct dementia (MID). As a consequence, patients with AD presented clinical manifestations not seen in patients with other senile dementias; that is, (1) an increase in stepwise eye movement, (2) anisotropy in the velocity of right-directional and left-directional eye movements, (3) a decrease in the velocity of head movements (4) incomplete gaze, and (5) decreased head share.

This paper describes a novel technique to realize high performance digital sequential circuits by using Hopfield neural networks. For an example of applications of neural networks to digital circuits, a novel gate circuit, full adder circuit and latch circuit using neural networks, which have the global convergence property, are proposed. Here, global convergence means that the energy function is monotonically decreasing and each circulit always operates correctly independently of the initial values. Finally the several digital sequential circuits such as shift register and asynchronous binary counter are designed.

An approach to estimate the information of moving objects is described in terms of their kinetic and static properties such as 2D velocity, acceleration, position, and the size of each object for the features of motion snd shape. To obtain the information of motion/shape of multiple objects, an advanced contour matching scheme is developed, which includes the synthesis of edge images and the analysis of object shape with a high matching confidence as well as a low computation cost. The scheme is composed of three algorithms: a motion estimation by an iterative triple cross-correlation, an image synthesis by shifting and masking the object, and a shape analysis for determining the object size. Implementing fuzzy membership functions to the object shape, the scheme gets improved in accuracy of capturing motion and shape of multiple moving objects. Experimental result shows that the proposed method is valid for several walking men in real scene.

An adaptive array antenna can be considered as a useful tool of combating with fading in mobile communications. We can directly obtain the optimal weight coefficients without updating in temporal sampling, if the arrival angles and signal-to-noise ratio (SNR) of the desired and the undesired signals can be accurately estimated. The Maximum Entropy Method (MEM) can estimate the arrival angles, and the SNR from spatially sampled signals by an array antenna more precisely than the Discrete Fourier Transform (DFT). Therefore, this paper proposes and investigates an adaptive array antenna based on spatial spectral estimation using MEM. We call it MEM array. In order to reduce complexity for implementation, we also propose a modified algorithm using temporal updating as well. Furthermore, we propose a method of both improving estimation accuracy and reducing the number of antenna elements. In the method, the arrival angles can be approximately estimated by using temporal sampling instead of spatial sampling. Computer simulations evaluate MEM array in comparison with DFT array and LMS array, and show improvement owing to its modified algorithm and performance of the improved method.

The transient behavior in the fractal admittance acting as a non-integer-rank differential/integral operator, Y(s) ∝ sa with -1a1 and a0, is examined from the point of view of memory effects by employing the distributed-relaxation-time model. The internal state of the diode is found to be represented by the current spectrum i(λ, t) with respect to the carrier relaxation rate λ, leading to a general formulation of the long-time-tail memory behavior characteristic of the operator. One-to-one corrsepondence is found among the input voltage in the past ν(-t), the short-circuit current isc(t) and the initial current spectrum i(λ, 0) within the framework of the Laplace-type integral transformation and its inverse, assuring that each response retains in principle the entire information on the corresponding input, such as the functional form, the magnitude, the onset time, and so forth. The current and voltage responses are exemplified for various single-pulse voltage inputs. The responses to the pulse-train inputs corresponding to different ASCII codes are found to be properly discriminated between one another, showing the potentials of the present memory effects.

Although the perception of gloss is based on human visual perception, some methods for extracting glossiness, in contrast to human ability, have been proposed involving curved surfaces. Glossiness defined in these methods, however, does not correspond with psychological glossiness perceived by the human eye over the wide range from relatively low gloss to high gloss. In addition, the obtained glossiness in these methods changes remarkably when the curvature radius of the high-gloss object becomes larger than 10mm. In reality, psychological glossiness does not change. These methods, furthermore, are available only for spherical objects. A new method for extracting glossiness is proposed in this study. For the new definition of glossiness, a spatial filter which simulates human retina function is utilized. The light intensity distribution of the curved object is convoluted with the spatial filter. The maximum value Hmax of the convoluted distribution has a high correlation with psychological glossiness Gph. From the relationship between Gph and Hmax, new glossiness Gf is defined. The gloss-extraction equipment consists of a light source, TV camera, an image processor and a personal computer. Cylinders with the curvature radii of 3-30 mm are used as the specimens in addition to spherical balls. In all specimens, a strong correlation, with a correlation coefficient of more than 0.97, has been observed between Gf and Gph over a wide range. New glossiness Gf conforms to Gph even if the curvature radius in more than 10 mm. Based on these findings, it is found that this method for extracting glossiness is useful for the extraction of glossiness of spherical and cylindrical objects over a wide range from relatively low gloss to high gloss.

IC performance simulation for statistical purpose is usually very time-consuming since the scale and complexity of IC have increased greatly in recent years. A common approach for reduction of simulation cost is aimed at the nature of simple modeling instead of actual circuit performance simulations. In this paper,a stochastic interpolation model (SIM) scheme is proposed which overcomes the drawbacks of the existing polynomial-based approximation schemes. First,the dependence of the R2press statistic upon a parameter in SIM is taken into account and by maximizing R2press this enables SIM to achieve the best approximation accuracy in the given sample points without any assumption on the sample data. Next, a sequential sampling strategy based on variance analysis is described to effectively construct SIM during its update process. In each update step, a new sample point with a maximal value of variance is added to the former set of the sample points. The update process will be continued until the desired approximation accuracy is reached. This would eventually lead to the realization of SIM with a quite small number of sample points. Finally, the coefficient of variance is introduced as another criterion for approximation accuracy check other than the R2press statistic. The effectiveness of presented implementation scheme is demonstrated by several numerical examples as well as a statistical circuit analysis example.

We propose an optical computing architecture called pure optical parall array logic system (P-OPALS) as an instance of sophisticated optical computing system. On the P-OPALS, high density images can be processed in parallel using the optical system with high resolving power. We point out problems on the way to develop the P-OPALS and propose logical foundation of the P-OPALS called single-input optical array logic (S-OAL) as a solution of those problems. Based on the proposed architecture, an experimental system of the P-OPALS is constructed by using three optical techniques: birefringent encoding, selectable discrete correlator, and birefringent decoding. To show processing capability of the P-OPALS, some basic parallel operations are demonstrated. The results obtained indicate that image consisting of 300 100 pixels can be processed in parallel on the experimental P-OPALS. Finally, we estimate potential capability of the P-OPALS.

In this paper, we propose a plausible software reliability growth model by applying a mathematical technique of stochastic differential equations. First, we extend a basic differential equation describing the average behavior of software fault-detection processes during the testing phase to a stochastic differential equation of ItÔ type, and derive a probability distribution of its solution processes. Second, we obtain several software reliability measures from the probability distribution. Finally, applying a method of maximum-likelihood we estimate unknown parameters in our model by using available data in the actual software testing procedures, and numerically show the stochastic behavior of the number of faults remaining in the software system. Further, the model is compared among the existing software reliability growth models in terms of goodness-of-fit.

Reflection type optical switches with intersecting waveguides and curved electrodes are newly proposed. The guided incident mode is expanded into an infinite spectrum of plane wavelets. The effects of light tunneling into the transmission port is taken care of by treating the 3-layer structure and using its reflection and transmission coefficients in estimation of the extinction ratios. It is found that the electrode curved in the form of an exponential spiral provides remarkably improved power reflectivity. This is because it poses a constant angle of incidence (smaller than the critical angle) to all variously oriented impinging wavelets. In this way, all plane wavelets are made to undertake total reflections. These total reflections result in considerably high extinction ratios to be achivable at the transmission port. It is also shown that the electrode length is shorter and the intersection angle is wider than those corresponding to a straight electrode. Therefore, it is concluded that the curvature of the electrode improves the switching characteristics of the device.

This letter shows that VEPs can be easily measured by using color cards as the color stimulus, and that the responses evoked by a difference in chroma could be described largely by the value of the first principal component in principal component analysis.

For the production of high quality synthetic sounds in a text-to-speech system, an excellent synthesizing method of speech signals is indispensable. In this paper, a new speech analysis-synthesis method for the text-to-speech system is proposed. The signals of voiced speech, which have a line spectrum structure at intervals of pitch in the linear frequency domain, can be represented approximately by the superposition of sinusoidal waves. In our system, analysis and synthesis are performed using such a harmonic structure of the signals of voiced speech. In the analysis phase, assuming an exact harmonic structure model at intervals of pitch against the fine structure of the short-time power spectrum, the fundamental frequency f0 is decided so as to minimize the error of the log-power spectrum at each peak position. At the same time, according to the value of the above minimized error, the rate of periodicity of the speech signal is detemined. Then the log-power spectrum envelope is represented by the cosine-series interpolating the data which are sampled at every pitch period. In the synthesis phase, numerical solutions of non-linear differential equations which generate sinusoidal waves are used. For voiced sounds, those equations behave as a group of mutually synchronized oscillators. These sinusoidal waves are superposed so as to reconstruct the line spectrum structure. For voiceless sounds, those non-linear differential equations work as passive filters with input noise sources. Our system has some characteristics as follows. (1) Voiced and voiceless sounds can be treated in a same framowork. (2) Since the phase and the power information of each sinusoidal wave can be easily controlled, if necessary, periodic waveforms in the voiced sounds can be precisely reproduced in the time domain. (3) The fundamental frequency f0 and phoneme duration can be easily changed without much degradation of original sound quality.

In this paper we present a method to generate test sequences for stuck-at faults in sequential circuits which have distinguishing sequences. Since the circuit may have no distinguishing sequence, we use two design techniques for circuits which have distinguishing sequences. One is at state transition level and the other is at gate level. In our proposed method complete test sequence can be generated. The sequence consists of test vectors for the combinational part of the circuit, distinguishing sequences and transition sequences. The test vectors, which are generated by a combinational test generator, cause faulty staes or faulty output responses for a fault, and disinguishing sequences identify the differences between faulty states and fault free states. Transition sequences are necessary to make the state in the combinational vectors. And the distinguishing sequence and the transition sequence are used in the initializing sequence. Some techniques for shortening the test sequence is also proposed. The basic ideas of the techniques are to use a short initializing sequence and to find the order in concatenating sequences. But fault simulation is conducted so as not to miss any faults. The initializing sequence is obtained by using a distinguishing sequence. The efficiency of our method is shown in the experimental results for benchmark circuits.

An analysis of wave guidance by surface-relief grating waveguides is presented for the case of oblique propagation. This analysis is based on the first-order differential equations expressing the coupling of the space harmonics and an improved differential method is applied to solve the equations in the grating region with arbitrary profile. The propagation constants are calculated for isotropic grating waveguids with sinusoidal profile and the calculated results indicate that the accurate solutions can be obtained by increasing the number of expansion terms and the number of segments. Moreover, this method is extended to the case of the analysis of obliquely propagating waves and it is shown that peculiar leaky waves and stop bands appear owing to the coupling between TE and TM waves.

This letter presents an algorithm named SPM which generates test patterns for single stuck-at faults in synchronous sequential circuits based on a product machine traversal method. The new idea presented in this letter is partitioned image computation combined with a mixed breadth-first/depth-first search. Image computation is carried out in partitioned manner by substituting constant logical values to some input variables. This brings about significant reduction in storage requirement during image computation. A test generator based on SPM achieved 100% fault efficiency for the ISCAS'89 benchmark circuits with not more than 32 flip-flops.

Reactive systems respond to internal or external stimuli and act in an event-driven manner. It is generally difficult to specify a complex reactive systems' behavior using conventional state machine formalism. One reason is that actual reactive systems are usually formed by combining plural state-machince that behave concurretly. This paper presents the State Diagram Matrix (SDM) which is a visual and hierarchical formalism of such a reactive system's behavior. SDM has two concepts. The first is matrix plane description on which 3-dimensional state space is projected. The second is state abstraction for hierarchical state-machine definition. Understandability and reliability of control software was improved as a consequence of adopting SDM for specifying disk-subsystem control requirements. The development support functions of SDM using a workstation are also described.

The value distribution of the partial autocorrelation of periodic sequences is important for the evaluation of the sequence performances when sequences of long period are used. But it is difficult to find the exact value distribution of the autocorrelation in general. Therefore we derived some properties of the partial autocorrelation for binary m-sequences which may be used to find the exact value distribution.

Let U denote a set comprising elements called "keys." The goal of the nearest point problem is to search quickly for a key among some keys x1 , xn that is the nearest to a reference key x under a partial order relation defined as (x, y) (x, z) for x, y, zU if d(x, y)d(x, z) given a wide-sense distance measure d. This article proposes a method of rearranging x1 , xn into a binary perfectly-balanced tree for solving quickly the nearest point problems. Further, computational performances of the proposed method are evaluated experimentally.

This paper describes an adaptive sensing system with tracking and zooming a moving object in the stable environment. Both the close contour matching technique and the effective determination of zoom ratio by fuzzy control are proposed for achieving the sensing system. First, the estimation of object feature parameters, 2-dimensional velocity and size, is based on close contour matching. The correspondence problem is solved with cross-correlation in projections extracted from object contours in the specialized difference images. In the stable environment, these contours matching, capable of eliminating occluded contours or random noises as well as background, works well without heavy-cost optical flow calculation. Next, in order to zoom the tracked object in accordance with the state of its shape or movement practically, fuzzy control is approached first. Three sets of input membership function--the confidence of object shape, the variance of object velocity, and the object size--are evaluated with the simplified implementation. The optimal focal length is achieved of not only desired size but safe tracking in combination with fuzzy rule matrix constituted of membership functions. Experimental results show that the proposed system is robust and valid for numerous kind of moving object in real scene with system period 1.85 sec.