The aim of this study is to examine the effectiveness of various open-ended resonators. According to the required filter responses, the application to microwave filters based on presented open-ended resonators is systematically examined as well. First, the resonance property of the basic open-ended resonator is discussed based on even-and odd-mode analysis. The intrinsic property of a tapped open-ended resonator is also discussed here. Second, the basic properties of a stepped impedance resonator (SIR) and a loaded-element resonator are examined theoretically for improvement of spurious responses and the dual-passband response. The basic operations of these resonators are also explained based on even- and odd-mode analysis. Examples for filter applications based on presented resonators are also provided. We found that the intrinsic properties of the open-ended resonators are very useful for practical filter responses.

Magnetoencephalography (MEG) is a powerful and non-invasive technique for measuring human brain activity with a high temporal resolution. The motivation for studying MEG data analysis is to extract the essential features from measured data and represent them corresponding to the human brain functions. In this paper, a novel MEG data analysis method based on independent component analysis (ICA) approach with pre-processing and post-processing multistage procedures is proposed. Moreover, several kinds of ICA algorithms are investigated for analyzing MEG single-trial data which is recorded in the experiment of phantom. The analyzed results are presented to illustrate the effectiveness and high performance both in source decomposition by ICA approaches and source localization by equivalent current dipoles fitting method.

In high-speed data networks, it is important to execute high-speed address resolution for packets at a router. To accomplish high-speed address resolution, address cache is effective. For HTTP accesses, it has been discussed that the Dual Zipfian Model can describe the distribution of the destination IP addresses, and it enabled us to derive the cache miss ratio in the steady state, i. e. , the cache miss ratio when the cache has full entries. However, at the time that systems are initialized or network topology is changed, the address cache has no address information or invalid address information. This paper shows the compulsory miss ratio which is the cache miss ratio when the cache has no address entry. In addition, we discuss the replacement policies of cache entries, for fast recovery of packet reachability, when the cache has information of unreachable address.

This paper surveys how geometric information can be effectively used for efficient algorithms with focus on clustering problems. Given a complete weighted graph G of n vertices, is there a partition of the vertex set into k disjoint subsets so that the maximum weight of an innercluster edge (whose two endpoints both belong to the same subset) is minimized? This problem is known to be NP-complete even for k = 3. The case of k=2, that is, bipartition problem is solvable in polynomial time. On the other hand, in geometric setting where vertices are points in the plane and weights of edges equal the distances between corresponding points, the same problem is solvable in polynomial time even for k 3 as far as k is a fixed constant. For the case k=2, effective use of geometric property of an optimal solution leads to considerable improvement on the computational complexity. Other related topics are also discussed.

For NP-hard combinatorial optimization problems, approximation algorithms with high performances have been proposed. In many of these algorithms, mathematical programming techniques have been used and proved to be very useful. In this survey, we present recent mathematical programming techniques as well as classic fundamental techniques, by showing how these techniques are used in designing high-quality approximation algorithms for NP-hard combinatorial optimization problems.

This paper describes a dual-looped PLL architecture to improve voltage-to-frequency linearity of VCO. The V-I converter employing a current-pumping algorithm is proposed to enhance the linearity of the VCO circuit. The designed VCO operates at a wide frequency range of 75.8 MHz-1 GHz with a good linearity. The PFD circuit design technique preventing fluctuation of the charge pump circuit under the locked condition is discussed. Simulation results show that a locking time of the proposed PLL is 3.5 µs at 1 GHz and the power dissipation is 92 mW.

Diffraction pattern functions of an E-polarized scattering by a wedge composed of perfectly conducting metal and lossless dielectric with arbitrary permittivity are analyzed by applying an improved physical optics approximation and its correction. The correction terms are expressed into a complete expansion of the Neumann's series, of which coefficients are calculated numerically to satisfy the null-field condition in the complementary region.

This paper proposes an associative memory neural network whose limiting state is the nearest point in a polyhedron from a given input. Two implementations of the proposed associative memory network are presented based on Dykstra's algorithm and a fixed point theorem for nonexpansive mappings. By these implementations, the set of all correctable errors by the network is characterized as a dual cone of the polyhedron at each pattern to be memorized, which leads to a simple amplifying technique to improve the error correction capability. It is shown by numerical examples that the proposed associative memory realizes much better error correction performance than the conventional one based on POCS at the expense of the increase of necessary number of iterations in the recalling stage.

Optical Code Division Multiple Access (OCD- MA) has been emerging as an attractive scheme in fiber optic communication systems as well as in space communication systems in past few years. In OCDMA systems, M-ary Pulse Position Modulation (PPM), has been regarded as an efficient signalling format which has the capability to reduce the channel interference caused by the other users and also to increase the number of simultaneous users. We apply error control coding to improve the system performance of pulse position modulated OCDMA (PPM/OCDMA) systems and this paper investigates the performance of M-ary PPM/OCDMA systems with M-ary convolutional coding. Dual-k code is used as the M-ary convolutional code and Optical Orthogonal Codes with the maximum cross correlation value of 1 and 2 are employed as the signature sequences. We derive an expression for the bit error probability of the new system and show that combining M-ary convolutional coding and M-ary PPM results in an improved error performance. Also it is shown that the number of simultaneous users can be significantly increased with the proposed system compared to the uncoded PPM/OCDMA system with the same bit error probability and with the same information bit rate. We also analyze the system with binary convolutional coding and a comparison with the proposed system is given.

Dynamical theory of cellular automata on groups is developed. Main results are non-Euclidean extensions of Sato and Honda's results on the dynamics of Euclidean cellular automata. The notion of the period of a configuration is redefined in a more group theoretical way. The notion of a co-finite configuration substitutes the notion of a periodic configuration, where the new term is given to it to reflect and emphasize the importance of finiteness involved. With these extended or substituted notions, the relations among period preservablity, injectivity, and Poisson stability of parallel maps are established. Residually finite groups are shown to give a nice topological property that co-finite configurations are dense in the configuration space.

A novel dual-band internal antenna similar in size to the single-band internal antenna for cellular handsets is proposed. Our approach to realize a small and low-profile dual-band internal antenna is to use the dominant mode (TM10 mode) and the higher-order mode (TM30 mode). In order to use this approach for recent dual-band cellular systems it is necessary to lower the resonant frequency of the higher-order mode (TM30 mode). This motivated our development of a new antenna configuration with a slot on the radiation element of a quarter-wavelength shorted microstrip antenna to lower the resonant frequency of the TM30 mode. In this paper, the experimental and the analytical results for this antenna are presented. In the results, by adjusting the location and the length of the slot, the dual-frequency operation can be achieved with the frequency ratio (TM30 mode/TM10 mode) from 2 to 3. In addition, the enhancement of bandwidth is presented.

This paper presents a new approach to computer image generation via three proposed methods for translating the evolution of a Petri net into fractal image synthesis. The idea is derived from the concept of fractal iteration principles in the escape-time algorithm and chaos game. The approach uses a Petri net as a powerful abstract modeling tool for fractal image synthesis via its duality, deadlock, inhibitor arc, firing sequence and marking reachability. The objective of this approach is to enhance the analysis technique of a Petri net and use it as a novel technique for fractal image synthesis. Generating fractal images via the dynamics of a Petri net allows an easy and direct proof for the similarity and correspondence between the dynamics of complex quadratic fractals by the recursive procedure of the escape-time algorithm and the state of a Petri net via a reachability problem. The reachability problem will be manipulated in terms of the dynamics of the fractal in order to generate images via three proposed methods. Validation of our approach is given by discussion and an illustration of some experimental results.

We have improved the mechanical reliability of deep-submicron semiconductor devices by applying a simulation technique. Typical kinds of damages that reduce the reliability are dislocations in silicon substrates, delamination or cracking of thin films, and deterioration of electronic characteristics of devices. The mechanical stress that develops in device structures is caused by not only mismatches in thermal expansion coefficients among thin film materials but also intrinsic stress of thin films such as poly-silicon and silicides. Fine patterning by dry etching makes sharp edges and they also cause stress concentration and thus high stress. The manufacturing processes in which stress mainly develops are isolation, gate formation, and interconnect formation. We have developed methods for reducing the stress in each of the above-mentioned process. This stress reduction is very effective for highly reliable manufacturing. Finally, we clarify the effect of the residual stress in transistor structures on shift in the electronic characteristics of MOS transistors.

This paper proposes a newly developed dual-frequency antenna for 800 MHz and 1500 MHz band use. A uniformly spaced array configuration, originally designed for a 800 MHz analog system, is extended to yield dual frequencies operations. An important characteristic of a base station antenna is low sidelobe level in order to suppress inter-cell interference. In the case of a uniformly spaced array configuration, sidelobe levels are increased by the emergence of grating lobes at higher frequencies. Electrical beam tilt also degrades the sidelobe level. As does the change in the excitation coefficients of the array elements at higher frequencies. These three factors are studied theoretically to yield practical sidelobe levels. One more important beam characteristic is the sector beam in the horizontal plane. The same beam width in two frequency bands is achieved by designing the novel reflector shape and determining the proper array element positions in front of the reflector. Practical antenna characteristics are confirmed by designing, manufacturing, and testing a base station antenna.

The Conjugate Residual method, one of the iterative methods for solving linear systems, is applied to the problems with a dense coefficient matrix on distributed memory parallel computers. Based on an assumption on the computation and communication times of the proposed algorithm for parallel computers, it is shown that the optimal number of processing elements is proportional to the problem size N. The validity of the prediction is confirmed through numerical experiments on Hitachi SR2201.

A novel method is proposed to calculate the distributed coupling of dual-modes in a circular resonator. New theoretical expressions are devised to accumulate the infinitesimal coupling between orthogonal modes and their validity is justified by the FD-TD analysis and experiments. The distributed coupling concept of a circular disk resonator is applied to a square disk resonator to calculate its resonant frequency. We have fabricated two types of low-profile dual-mode square dielectric disk resonator BPF, using high dielectric constant material (εr = 93) having a dimension of 5 mm 5 mm 1 mm. The filter characteristics are explained by the transmission line circuit model.

Major problems of traffic control in ATM networks include how to decide whether a network accepts a new call or not in real time and how to select the best set of Dual Leaky Bucket (DLB) parameter values. To solve these problems, it is necessary to determine the amount of network bandwidth required by the call. In this paper, we present an analysis based on bounding technique to derive an upper bound on bandwidth requirement when the call is characterized by a set of DLB parameters. Consequently, a new definition of the upper bound on bandwidth requirement and simple formulae used for computing the upper bound have been obtained. To clarify the advantages of the derived upper bound, we demonstrate its two applications, one to select the best set of DLB parameter values from candidates for minimizing the amount of bandwidth to be allocated to the call and the other to establish a Connection Admission Control (CAC) scheme. The upper bound-based CAC scheme is fast enough to process in real time due to its simplicity and provides a significant improvement of network utilization compared to the peak rate-based CAC scheme.

A unified theory for the characteristics of dual modes in a circular resonator is elucidated in simple analytical expressions. First, a circular resonator is considered as a ring transmission line which allows two oppositely traveling waves. The essential quantities that characterize a transmission line, i. e. , the propagation constant and characteristic impedance are obtained theoretically and/or experimentally. Secondly, any circular resonator is described by a ring resonator model which can be treated analytically, and the resonant frequencies are obtained when perturbations are added along the periphery of a circular resonator. A two stage BPF is created by adding I/O ports to the perturbed circular resonator. Its center frequency and bandwidth is calculated based on the ring resonator model. The circuit condition for obtaining two attenuation poles at both sides of the passband is given together with the method for their control.

Cursor RAMs have been composed of two memory planes. A cursor pattern is stored in these planes with 2-bit data depth. While the pixel port requires data from both planes at the same time, the MPU port accesses either one of the planes at a time. Since the address space is defined differently between the ports, conventional cursor RAMs could not have dealt with these different access ways at real time. This paper proposes a dual port cursor RAM with a dynamic data alignment architecture. The architecture processes the different access ways at real time, and reduces a large amount of control circuitry. Conventional cursor RAMs have been organized with a single port memory because dual port memory cells have been large. We have applied the port swap architecture which has reduced the cell size. The control block is further simplified because the controller no longer emulate a dual port memory. The cursor RAM with these architectures is fabricated with a double metal 0. 5 µm CMOS process technology. The active area is 1. 51. 6 mm2 including a couple of shift registers and a control block. It operates up to 263 MHz at the supply voltage of 3. 3 V.

Video on demand is regarded as one of the most important applications in future broadband networks. Although several trial runs in various parts of the world do not bring instant success, its inherent requirements for bandwidth and bounded delay make it a suitable candidate for studying various networks and protocols in real-time applications. Recently, the Hybrid Fiber Coaxial (HFC) networks emerged as network architecture for bringing broadband services to the home. The co-axial cable network uses a tree-like architecture and requires complex protocols for synchronizing and sharing uplink communications among many users. This paper proposes that a dual bus network may be a simpler and cost effective alternative. We implement an interactive VOD (IVOD) system as an example to demonstrate its simplicity and suitability as a community network. The system uses client/server architecture with guaranteed bandwidth and bounded delays. Simulations are conducted to test the network load and response time for different number of users. The results indicate its feasibility and the delay time can be further reduced by releasing bandwidth during the pause operation.