Analytical solutions have been obtained for the electromagnetic scattering by a modified Luneberg lens with the permittivity of arbitrary parabolic function. They are expressed by four spherical vector wave functions for radially stratified medium which were introduced for the Luneberg lens by C. T. Tai. They consist of the confluent hypergeometric function and a "generalized" confluent hypergeometric function, in which the parameters for the permittivity of arbitrary parabolic function are involved. The characteristics of the modified Luneberg lens are numerically investigated using exact solutions in comparison with that of the conventional Luneberg lens. The bistatic cross section, the forward cross section and the radar cross section are studied in detail. The near-field distribution is also investigated in order to study the focal properties of the Luneberg lens. The focal shifts defined by the distance between the geometrical focal point and the electromagnetic focal point are obtained for various ka (k is the wave number and a is the radius of the lens). The focal shift normalized to the radius of the sphere becomes larger as ka is smaller. However it drops down rapidly for ka5 when the peak of the electric field amplitude appears on the surface of sphere.

We proposed a new method to evaluate display legibility as a function of resolution. This method was able to evaluated display legibility without being restricted to the display resolution. Using this method, subjective psychological experiments were carried out to investigate display resolution, which provides legibility, in observing small characters. Samples viewed by subjects were images displayed on a high-resolution TFT-LCD that we developed, CRT images and printed documents for comparison. We have found that TFT-LCD legibility was much better than that of CRT, and that minimum resolution of about 175 dpi was needed for use in legible document viewers.

The dynamics is investigated on the delayed regulation model under period-2 perturbation described as x(t+1)={A+(-1)te}x(t){1-x(t-1)}, t=1, 2, 3 . . . The e-dependences of the bifurcation points are analyzed through usual stability analysis of fixed point and periodic solution, however one of them is derived through the stability analysis of the "virtual" period-2 solution.

The growth behavior of copper particle on crystalline and amorphous silicon surfaces has been investigated. The study reveals that the growth behavior of copper particle depends on the substrate condition. When samples are intentionally contaminated in ultrapure water, both crystalline and amorphous silicon surfaces show no difference in their contamination levels. However, copper particles were not observed on an amorphous silicon surface except dipping in dilute CuCl2 solution. The copper concentration on an amorphous silicon surface after dipping in a 0.5% HF solution is similar to the level after contaminating in ultrapure water. The copper contamination level on a crystalline silicon surface, except from CuCl2 solution, decreased two orders of magnitude as compared with ultrapure water. The copper impurity level on crystalline silicon surface was reduced by two orders by cleaning in a sulfuric acid-hydrogen peroxide mixture. The sulfuric acid-hydrogen peroxide mixture cleaning was not effective on an amorphous silicon surface. When native oxide pre-existed on an amorphous silicon surface before contamination, however, the sulfuric acid-hydrogen peroxide mixture cleaning was effective for removing copper impurity. Our results suggest that copper contamination on an amorphous silicon surface have the characteristics of bonding directly with silicon and/or existing in the native oxide, in contrast with the situation on crystalline silicon surface. After contamination with 1000 ppm copper in CuF2 solution, the etch rate of an amorphous silicon film in a 0.5% HF solution was approximately one order of magnitude faster than that of crystalline silicon. This is attributed to the difference in crystalline structure between crystalline silicon and amorphous silicon.

We have developed an experimental 4 K 2 K pixel progressive scan color camera system. This new camera system has a data rate of 297 MHz pixel/sec and 60 frame/sec and we are sure that horizontal and vertical limiting resolution of 1500 TVL (TV lines) can be achieved on a color monitor. Instead of the previous approach of improving resolution simply by increasing the pixel count in a imager, a novel four-sensor pickup method with 2/3 inch 2 million pixel CMD (Charge Modulation Device) imagers is used in this system. These sensors have 1920 (H) 1035 (V) pixels within a 16:9 wide aspect image area and are successfully driven at 148 M pixel/sec in the progressive scan mode. In the four-sensor pickup method, two sensors are used for green and the rest are for red and blue. A spatial offset imaging method in the diagonal direction was applied to the two green sensors to improve the horizontal and vertical resolution effectively. The horizontal and vertical resolution of the red and blue signals become half that of the green signal, because only one 2 M-pixel imager is used for each signal. The resolution of this system, however, is not degraded so much because the luminance signal is mainly composed of green signals.

We propose an optical spread-time code-division multiple-access (ST-CDMA) with pulse position modulation (PPM) signaling for high-speed communication networks. We obtain a union upper bound on the bit error rate (BER) considering the multi-access interference (MAI), shot noise and thermal noise at the receiver. As a result, we show that the optical ST-CDMA with PPM signaling improves the BER performance at the same received power and bit rate compared to that with OOK signaling. This leads to an increase of the bit rate at the same BER. Moreover, we show that the proposed system can relax the requirement for spectral resolution compared to the optical ST-CDMA with OOK signaling under the received power and bit rate constraints.

A new concept of "an imperfect singular solution" is defined as an approximate solution which becomes a singular solution by adding a suitable small perturbation to the original equations. A numerical method is presented for proving the existence of imperfect singular solutions of nonlinear equations with guaranteed accuracy. A few numerical examples are also presented for illustration.

We consider an algorithm for finding all solutions in order to clarify all the stable equilibrium points of a hysteresis neural network. The algorithm includes sign test, linear programming test and a novel subroutine that divides the solution domain efficiently. Using the hysteresis network, we synthesize an associative memory whose cross connection parameters are trinalized. Applying the algorithm to the case where 10 desired memories are stored into 77 cells network, we have clarified all the solutions. Especially, we have confirmed that no spurious memory exists as the trinalization is suitable.

In this paper, we analyze the inverse scattering problem by a new deterministic method called "Source and Radiation Field Solution," which has the merit that both the source and the radiation field can be treated at the same time, the effect of which has already shown in ordinary scattering problems.

Related with accuracy, computational complexity and so on, quality of computing for the so-called homotopy method has been discussed recently. In this paper, we shall propose an estimation method with interval analysis of region in which unique solution path of the homotopy equation is guaranteed to exist, when it is applied to a certain class of uniquely solvable nonlinear equations. By the estimation, we can estimate the region a posteriori, and estimate a priori an upper bound of the region.

Recent progress in neural network research has demonstrated the usefulness of neural networks in a variety of areas. In this work, its application in the spatial resolution improvement of a remotely sensed low resolution thermal infrared image using high spatial resolution of visible and near-infrared images from Landsat TM sensor is described. The same work is done by an algebraic method. The tests developed are explained and examples of the results obtained in each test are shown and compared with each other. The error analysis is also carried out. Future improvements of these methods are evaluated.

We show that characteristic functions of elements of self-similar tilings can be used as scaling functions of multiresolution analysis of L2(Rn). This multiresolution analysis is a generalization of a self-affine tiling multiresolution analysis using a characteristic function of element of self-affine tiling as a scaling function. We give a method of constructing a wavelet basis which realizes such an MRA.

This paper proposes the Dual Zipfian Model addressing how to describe HTTP access trends in large-scale data communication networks, and discusses how to design the capacity of address cache tables in an edge router of the networks. We show that destination addresses of packets can be characterized by two types of Zipf's law. Fundamental concept of the Dual Zipfian Model is in complementary use of these laws, and we can derive the relationship between the number of accesses and the number of destination addresses. Experimental results show that the relation gives a good approximation. Applying this relation, we derive cache hit probabilities of the address cache table that incorporates high-speed address resolution. Using the probabilities, design issues including the capacity of the cache tables and aging algorithms of cache entries are also discussed.

This paper proves a general sampling theorem, which is an extension of Shannon's classical theorem. Let o be a closed subspace of square integrable functions and call o a signal space. The main aim of this paper is giving a necessary and sufficient condition for unique existence of the sampling basis {Sn}o without band-limited assumption. Using the general sampling theorem we rigorously discuss a frequency domain treatment and a general signal space spanned by translations of a single function. Many known sampling theorems in signal spaces, which have applications for multiresolution analysis in wavelets theory are corollaries of the general sampling theorem.

An efficient algorithm is proposed for finding all solutions of bipolar transistor circuits. This algorithm is based on a simple test that checks the nonexistence of a solution using linear programming. In this test, right-angled triangles are used for surrounding exponential functions of the Ebers-Moll model, by which the number of inequality constraints decreases and the test becomes efficient and powerful.

Many image-processing techniques are based on texture features or gradation features of the image. However, Landsat images are complex; they also include physical features of reflection radiation and heat radiation from land cover. In this paper, we describe a method of constructing a super-resolution image of Band 6 of the Landsat TM sensor, oriented to analysis of an agricultural area, by combining information (texture features, gradation features, physical features) from other bands. In this method, a knowledge-based hierarchical classifier is first used to identify land cover in each pixel and then the least-squares approach is applied to estimate the mean temperature of each type of land cover. By reassigning the mean temperature to each pixel, a finer spatial resolution is obtained in Band 6. Computational results show the efficiency of this method.

In this article, we propose a square wave generator whose switching threshold values are switched by external inputs. This circuit is designed to simulate the synchronized luminescence of coupled fireflies. We investigate the behavior of the solutions in two coupled oscillators. The dynamics are demonstrated by a linear autonomous equation piecewisely, therefore, a one-dimensional return map is derived. We also prove the existence of stable in-phase synchronization in the coupled oscillator by using the return map, and we show the existence of regions of periodic solutions within a parameter space. Some theoretical results are confirmed by laboratory measurements.

A formal necessary and sufficient condition on the general Petri net reachability problem is presented by eliminating all spurious solutions among known nonnegative integer solutions of state equation and unifying all the causes of those spurious solutions into a maximal-strongly-connected and siphon-and-trap subnet Nw. This result is based on the decomposition of a given net (N, Mo) with Md and the concepts of "no immature siphon at the reduced initial marking Mwo" and "no immature trap at the reduced end marking Mwd" on Nw which are both extended from "no token-free siphon at the initial marking Mo" and "no token-free trap at the end marking Md" on N, respectively, which have been both effectively, explicitly or implicitly, used in the well-known fundamental and simple subclasses.

Sr0. 7Bi2. 3Ta2O9(SBT) films are drawing attention as fatigue-free materials. We prepared an SBT film containing discontinuous crystals in the Bi-layered compound using a misted deposition method. In comparison to films prepared by the spin-on method, leakage current was low and spontaneous polarization is high but saturation performance was low. The low saturation performance seems attributable to the inclusion of discontinuous crystals in the Bi-layered compound, while the low leakage current may be explained by the films smaller, denser particles, which form a film without voids, resulting in higher uniformity. The misted deposition method has advantages of finer grain size and higher uniformity.

We discussed on relationship between the width of slit ray and the accuracy of the measurement system for surface profile of electric contact. To obtain resolution of 10 [µm], we designed the mechanism which keeps constant the focal length between the object and the lens. As a result, the width of slit ray was clear in the whole surface. A section image could measured exactly and enhanced the resolution.