The inverse problem we consider in this paper seeks, based on the equivalent source method, to determine the shape of perfectly conducting cylinders from the scattered farfield data obtained by using several incident waves. When incident waves of different frequencies are used, the shape of the scatterer can be reconstructed by employing only a few number of observation points. In the reconstruction problem, to determine the shape of the scatterer, the conjugate gradients method is applied. The general approach is applicable to cylindrical scatterers of arbitrary shape. Results of numerical simulations are presented to support the suggested approach.

Recently, a flexible image database retrieval system where image keywords can be captured automatically is strongly required, in order to manage a practical number of image data successfully. However, image recognition/understanding technology level is not generally sufficient enough to achieve this requirement. In order to overcome this problem, a new type of image database framework is proposed in this paper. In the proposed system, image keywords are extracted in fully-automated fashion by the flexible and generalized image recognition system. Image keywords employed in this system are a collection of recognized objects in the image, where achieved recognition levels are allowed to be intermediate or imperfect. The concept of recognition thesaurus" has been introduced to manage these various abstraction level of kerwords successfully. As an embodiment of this concept, an experimental image database with various types of sports scenes has been implemented and various retrieval evaluations have been performed. Experimental results reveal the effectiveness of the proposed method.

A method for detecting multiple rigid motions in images from an optical flow field obtained with multi-scale, multi-orientation filters is proposed. Convolving consecutive gray scale images with a set of eight orientation-selective spatial Gaussian filters yields eight gradient constraint equations for the two components of a flow vector at every location. The flow vector and an uncertainty measure are obtained from these equations. In the neighborhood of motion boundary, the uncertainty of the flow vectors increase. By using multiple sets of filters of different scales, multiple flow vectors are obtained at every location, from which the one with minimal uncertainty measure is selected. The obtained flow field is then segmented in order to solve the aperture problem and to remove noise without blurring discontinuity in the flow field. Discontinuities are first detected as those locations where flow vectors have relatively larger uncertainty measures. Then similar flow vectors are gouped into regions. By modeling flow vectors, regions are merged to form segments each of which belongs to a planar patch of a rigid object in the scene.

As a new method to generate a homogeneous, random, binary image with a rational power spectrum, this paper proposes a discrete-valued auto-regressive equation, of which random coefficients and white noise excitation are all discrete-valued. The average and spectrum of the binary image are explicitly obtained in terms of the random coefficients. Some computer results are illustrated in figures.

We are concerned with a subclass of deterministic pushdown automata (dpda) called very simple dpda's, and present a new direct branching algorithm for checking the inclusion for a pair of languages accepted by these dpda's. As usual, we take the maximal thickness (i.e., the length of the shortest input strings that make each stack symbol go to empry) of all stack symbols into account as one parameter of the given dpda's. Then the worst-case time complexity of our algorithm is polynomial with respect to these parameters. Without considering the thickness, the complexity is single exponential in the description length of the given dpda's. As far as we are concerned with very simple dpda's, our algorithm is very simple and direct, and is faster and much better than the previously given algorithms for the inclusion problem of dpda's.

We often use data flow diagrams or state transition diagrams to design software systems with concurrency. We call those diagrams as nets in this paper. Semantics of any methods to describe such software systems should be defined in some formal ways. There would be no doubts that any nets should be supported by appropriate theoretical frameworks. In this paper, we use CCS as a typical algebraic approach of using formulas to express concurrent behaviors and point out the different features of CCS from Petri nets. Any approaches should be not only theoretically beautiful but also practically useful. We use a specification language LOTOS as such example which has two features, CCS and ADT, and is designed to specify practical communication protocols. Algebraic approaches of using formulas, like LOTOS, can be considered as a compact way to express concurrent behaviors. We explore our discussions of net-oriented approaches into UIMS research fields. After mentioning state transition models of UIMS, we exemplify a practically used example, VIA-UIMS, which has been developed by one of authors. VIA-UIMS employs a net-oriented architecture. It has been designed to reconstuct tools which have already been widely used in many sites.

This paper presents a linear time optimal algorithm to a channel pin assignment problem for hierarchical building-block layout design. The channel pin assignment problem is to determine positions of the pins of nets on the top and the bottom sides of a channel, which are partitioned into several intervals, and the pins are permutable within their associated intervals. The channel pin assignment problem has been shown NP-hard in general. We present a linear time optimal algorithm for an important special case of the problem, in which there is at most one pin of a net within each interval in the channel. The proposed algorithm is optimal in a sense that it can minimize both the channel density and the total wire length of the channel. We also disscuss how to apply our algorithm to the pin assignment in the L-shaped and staircase channels. Experimental results indicate that substantial reduction in both channel density and estimated total wire length can be obtained by permuting pins in each interval. Combining the proposed algorithm with a conventional channel router, results of channel routing also achieve large amount of reduction of the number of tracks, total wire length, and the number of vias.

There have been several studies related to a reduction of the amount of computational resources used by Turing machines. As consequences, linear speed-up theorem" tape compression theorem", and reversal reduction theorem" have been obtained. In this paper, we consider reversal- and leaf-bounded alternating Turing machines, and then show that the number of leaves can be reduced by a constant factor without increasing the number of reversals. Thus our results say that a constant factor on the leaf complexity does not affect the power of reversal- and leaf-bounded alternating Turing machines

The synchronic distance is a fundamental concept in a Petri net. Marked graphs form a subclass of Petri nets. Given a matrix D, we are interested in the problem of finding a marked graph whose synchronic distance matrix is D. It is wellknown that the synchronic disrance matrix of a marked graph is a distance matrix. In this letter, we give a matrix D such that D is a distance matrix and there does not exist a marked graph whose synchronic distance matrix is D.

A hardware accelerator for a raster-based design-rule checking called BITDRC for a bit-mapping CAD system is described. BITDRC is a special-purpose hardware accelerator which performs design-rule checking for the Manhattan layout style VLSI circuis, much faster than the software checking which belonged to the bit-mapping CAD system before. The bit-mapping CAD system had effectively been developed for both of educational and VLSI design purposes, and just needs only a personal computer as a compact working environment. The proposed hardware architecture is rather simply and characterized by the bit-mapping CAD system where it works on. The hardware architecture and checking algorithm have been confirmed by implementing a bread-board prototype using discrete components. As a result, the processing time of BITDRC is speeded up as much as 500 times faster than the original software and takes only 4 seconds for checking every rule on a(15001500) grids layout pattern. BITDRC performs the error checking together with the data scanning that makes it can be as an on-line design-rule checker for the bit-mapping CAD system. Finally, the physical layout of BITDRC has been designed using a conventional CMOS technology.

The transient scattering of a half sine pulse wave by a conducting rectangular cylinder with an open sidewall is rigorously analyzed by using the point matching method (taking into account the edge condition exactly) combined with the fast inversion of Laplace transform. Numerical results are presented for back scattered and forward scattered responses of the far fields when a half sine pulse is incident on the open side and the closed side of the cylinder. The physical meaning of the transient responses is discussed in detail. The comparison of the responses with those by a perfect conducting rectangular cylinder is presented.

The antennas for subsurface radar are usually covered with a conducting cavity to prevent the radiation field from affecting the electromagnetic environment and to protect the received field from external noises. Furthermore, radiowave absorber is attached to the interior wall of the cavity in order to suppress the multiple reflections in the cavity. In this paper, the characteristics of the two-dimensional cavity-backed antenna having the absorber and the over-all properties of this subsurface radar due to buried objects are numerically analyzed by the Finite-Difference Time-Domain method. It is shown that the pulse propagation in the ground is confined to the narrow region due to the cavity. It is also shown that the multiple reflections in the cavity are effectively suppressed by choosing the suitable absorber, and so that the distinctive pulse echo can be obtained.

In this paper, a novel Y-junction type demultiplexer utilizing a stratified-waveguide configuration in the branching region is proposed for the purpose of improving the extinction ratio. A high extinction ratio of about 20 dB is achieved at 0.6328 µm and 0.83 µm operation wavelengths both for the TE and TM modes. The properties of the new type branchig waveguides which consist of the diffused waveguide and the striploaded waveguide are described to explain the operation principle. Simulation results by the BPM are also shown to check the designed values of the waveguide parameters.

High performances of CMOS/SOI inverter by simulations of analytical model, reducing the poly-Si gate thickness (tm), and experiments are verified and proposed. It is shown that the tm and gate oxide thickness(tox) are correlated to gate fringing capacitance, which largely influences on the Propagation Delay Time(TPD). Contributions of gate fringing capacitance to CMOS/SIMOX inverter time delay in deep submicrometer gate devices are propounded. Measurements of the fifty-one stage ring oscillator's TPDs are completed for comparison with analytical model. Simulation results by the analytical model, including Time-Dependent Gate Capacitance (TDGC) model, agree well with the experimental results at the same conditions. Simulation results are also predicted that SOI technology is promising for speed enhancement by reducing the poly-Si gate thickness, while the tox remains constant. It is concluded that the TPDs by reducing the tm to zero are improved up to about two times faster than typically fabricated ring oscillator at 350 nm of the tm in deep-submicrometer gate CMOS/SIMOX inverters at room temperature.

Poled polymer films doped with novel nonlinear organic materials, α-cyano unsaturated carboxylic acid (α-CUCA) derivatives, are prepared. Linear and second-order nonlinear optical properties are investigated. It is found that as the value of hyperpolarizability of the derivatives increases, the second-order nonlinear susceptibility of the film increases. Cerenkov-type second harmonic generation (SHG) of Nd: YAG laser is realized in a poled polymer waveguide doped with the α-CUCA material with a slight absorption at doubled wavelength.

The fast and highly reliable method reported here uses two techniques to detect all types of defects, such as unsoldered leads, solder bridges, and misalignes leads in the minute solder joints of high density mounted devices. One technique uses external force applied by an air jet that vibrates or shifts unsoldered leads. The vibration and shift is detected as a change in the speckle pattern produced by laser illumination of the solder joints. The other technique uses fluorescence generated by short-wavelength laser illumination. The fluorescence from a printed circuit board produces a silhouette of the solder joint and this image is processed to detect defects. Experimental results show that this inspection method detects all kinds of defects accurately and with a very low false alarm rate.

For each two positive integers r, s, let [1DCM(r)-Time(ns)] ([1NCM(r)-Time(ns)]) and [1DCM(r)-Space(ns)] ([1NCM(r)-Space(ns)]) be the classes of languages accepted in time ns and in space ns, respectively, by one-way deterministic (nondeterministic) r-counter machines. We show that for each X{D, N}, [1XCM(r)-Time(ns)][1XCM(r+1)-Time(ns)] and [1XCM(r)-Space(ns)][1XCM(r+1)-Space(ns)]. We also investigate the relationships between one-way multicounter machines and cooperating systems of one-way finite automata. In particular, it is shown that one-way (one-) counter machines and cooperating systems of two one-way finite automata are equivalent in accepting power.

A fully focused Synthetic Aperture Radar (SAR) image can be obtained only if the raw data processing procedure takes into account the space-variance of the SAR system transfer function. This paper presents a nonconventional Fast Fourier Transform (FFT) algorithm which allows an efficient compensation of the space-variant effect. It is specially designed for the SAR data of the Japanese Earth Resources Satellite (JERS-1) but can be extended to different cases.

We present an extension of the previously proposed 3-layer feedforward network called a cascaded network. Cascaded networks are trained to realize category classification employing binary input vectors and locally represented binary target output vectors. To realize a nonlinearly separable task the extended cascaded network presented here is consreucted by introducing high order cross producted inputs at the input layer. In the construction of the cascaded network, two 2-layer networks are first trained independently by delta rule and then cascaded. After cascading, the intermediate layer can be understood as a hidden layer which is trained to attain preassigned saturated outputs in response to the training set. In a cascaded network trained to categorize binary image patterns, saturation of hidden outputs reduces the effect of corrupted disturbances presented in the input. We demonstrated that the extended cascaded network was able to realize a nonlinearly separable task and yielded better generalization ability than the Backpropagation network.

We propose a third-order low-pass notch filter realized by a single operational amplifier and a minimum number of equal-valued capacitors. As a design example we realize a Chebyshev filter with a ripple of 0.5 dB and it is shown that the experiment result is very good.