Nonlinear behavior of electromagnetic surface waves propagating along a tangentially magnetized ferrite slab is investigated. The nonlinear Schrodinger equation (NLSE) which describes the temporal evolution of the electromagnetic wave pulses has been derived directly from the Maxwell equations and the equation of precessional motion for the magnetization in the ferrite slab with the aid of the reductive perturbation method without magnetostatic approximation. Based on the formula derived, we have numerically evaluated the frequency-dependence of the nonlinear coefficient in the NLSE for both a magnetostatic surface wave mode and a dynamic mode. As a result, we have confirmed the possibility of the propagation of solitons in the waveguide.

This paper proposes a fault tolerant optical crossconnect (FTOXC) which can tolerate link, channel, and internal optical switch failures via spare optical channels, extra input/output (I/O) ports for an optical switch, and associated wavelength converters. It also proposes a fault tolerant wavelength routing algorithm (FTWRA) which is used in the normal and the restored state. The FTOXC and FTWRA can be applied to any all-optical network and can recover many types of failures. FTOXC can configure the number of working and spare channels in each output link based on the traffic demand. Two formulations in this paper can be used to determine the optimal settings of channels. A global optimal setting of working and spare channels in each link can be found by formulating the problem as an integer linear program (ILP). In addition, the number of working and spare channels in each link can be dynamically adjusted according to the traffic loads and the system reliability requirements. The tradeoff between these two conflicting objectives is analyzed by the Markov decision process (MDP).

The transmission S-parameter between two dipole-elements is a measure to evaluate sites for measuring complex antenna factors (CAF). In this paper, the S-parameter between two dipole-elements on a ground plane is measured using a network analyzer with its TRL (Thru-Reflect-Line) calibration. The S-parameter is also calculated by the method of moment (MoM) and compared to the measurement results. The comparison shows that the calculated S-parameter is usable as a reference value in the evaluation of CAF measurement sites. As an example of the evaluation and selection of measurement sites, the transmission S-parameter on a finite ground plane is calculated using the hybrid method combined the geometrical theory of diffraction (GTD) and MoM. As a result, a preferable antenna setting on the finite ground plane is recommended.

The use of a chirp signal is one of the methods to expand the detection range in subsurface radar. However, the presence of time-sidelobes after a conventional pulse-compression makes the detection range degraded because weak signals from underground objects are covered with a large time-sidelobe due to a ground surface reflection. In this paper, we propose a new pulse compression subsurface radar using a short chirp signal in which the echoes from the ground surface and the object are not overlapped. We show that the short chirp signal can improve the detection ability compared with a conventional chirp signal and examine the influence that the decreases of the signal duration and the compression ratio exert on the detection range. By the new pulse compression subsurface radar, the steel pipes buried down to 5 m in depth can be detected.

We investigate possibility of fault-tolerant and self-stabilizing protocols (ftss protocols) using an unreliable failure detector. Our main contribution is (1) to newly introduce k-accuracy of an unreliable failure detector, (2) to show that k-accuracy of a failure detector is necessary for any ftss k-group consensus protocol, and (3) to present three ftss k-group consensus protocols using a k-accurate and weakly complete failure detector under the read/write daemon on complete networks and on (n-k+1)-connected networks, and under the central daemon on complete networks.

In this paper, as a practical application, we focus on the genetic algorithm (GA) for multi-head surface mounting machines which are used to populate printed circuit boards (PCBs). Although there have been numerous studies on the surface mounting machine, studies on the multi-head case are rare because of its complexity. The multi-head surface mounting machine can pick multiple components simultaneously in one pickup operation and this operation can reduce much portion of the assembly time. Hence we try to minimize the assembly time by maximizing the number of simultaneous pickups, resulting in reduction of PCB production cost. This research introduces a partial-link GA method for the single-head case. Then, we apply this method to the multi-head case by regarding a reel-group as one reel and a component-cluster as one component. The results of computer simulation show that our genetic algorithm is greatly superior to the heuristic algorithm that is currently used in industry.

An algorithm that detects the surface echo peak position in a radar echo range profile has been developed for the TRMM Precipitation Radar (PR). The purpose of the surface echo peak detection is to determine the range window in which "over-sample" data are collected. The surface echo position in the range profile is variable due to the systematic change of satellite geodetic altitude and surface topography. The dynamic control of the over-sample range window using the surface detection algorithm contributes significantly to the reduction of PR data rate that should be sent to the ground station. The algorithm employs an α-β tracking filter and has three functions; surface tracking, lock-off detection and tracking loop initialization. After the launch of the TRMM satellite, a series of initial check-out of the PR was conducted. The performance of the algorithm was evaluated through the initial check-out and two-years operation of the PR. The results indicate that the algorithm is working as expected and basically meets the specification; however, it is found that some functions such as the tracking loop initialization algorithm need to be improved.

The application of subsurface radar using electromagnetic waves in the VHF band is wide and includes surveying voids under the ground and archaeological prospecting. To achieve a wider application range, the survey depth must be deeper. In this paper, a method of pulse compression using a chirp signal as one of the methods to fulfill this requirement is described, and its advantages and problems are discussed. First, a delay correlation method is proposed as a processing method of pulse compression. It converts RF band chirp signal directly into a pulse. Moreover, the method improves the S/N ratio by over 40 dB compared with conventional pulse radar. Therefore, it has the same detection ability as conventional pulse radar even though it uses less transmitting power. Next, the influences of RF amplifier saturation and underground propagation characteristics on the chirp signal are discussed; both are shown to have little influence on the detection ability of the method.

This paper describes an individual effect of soil moisture (mg) and surface roughness (hrms) of bare soil on the back scattering coefficient (σ0) at the X-band frequency. The study contributes to the design of an efficient microwave sensor. For this purpose, experimentally observed data was utilized to provide a composite σ0 equation model accounting for individual effect in regression analysis. The experimental data are compared with Small Perturbation Method. It is observed that the X-band gives better agreement up to incidence angle 50 for HH-polarization and 60 for VV-polarization as compared to the C-band. The lower angles of incidence give better results than the higher angles for observing mg at the X-band. The multiple and partial regression analyses have also carried out for predicting the dependence of scattering coefficient (σ0) on mg and hrms more accurately. The analyses suggest that the dependence of dielectric constant (i.e., mg) is much more significant in comparison to surface roughness at lower angles of incidence for both like polarizations. The results propose the suitable angle of incidence for observing bare surface roughness and soil moisture at the X-band. All these data can be used as a reference for satellite or spaceborne sensors.

Recently, cerebral disease is being a serious problem in an aging society. But, rank evaluation of cerebral disease is not developed and therefore rehabilitation is hard. In this study, we try to assess slight cerebral disease by taking notice of recognition mechanism of face and realizing face image synthesis using computer technology. If we can find a slight cerebral disease and rank evaluation, we can apply to rehabilitation, and a load of medical doctor and patient decreases. We have obtained a result by the experiment, so we report it.

To accomplish an efficient test pattern generation, the isomorphism identification algorithm and the pseudo dominator identification algorithm are developed which are used to identify redundant faults efficiently. Results show that test pattern generation using these algorithms is very efficient.

A tunable optical Fabry-Perrot filter was designed by setting a single-mode optical fiber normal to the diaphragm of a capacitive pressure sensor. The silicon diaphragm is deflected by the electrostatic force generated by applying a voltage to the capacitive electrodes. According to the movement of the diaphragm, the peak wavelength changed from 1546 to 1551 nm when applied voltage was increased from 20 to 50 V. The relationship of the wavelength change to the applied voltage was derived from the silicon diaphragm deflection theory. That measured change of the wavelength agrees well with the wavelength change calculated from this relationship. The commercial pressure sensors are expected to be able to be used as a tunable optical filter.

At the sliding contact of brush and rotating slip-ring or commutator, it has been recognized that the brush wear is influenced by brush pressure, current density and atmosphere nearby contact part. However, little is known about the relation between brush wear and atmosphere condition in detail. In this paper, the experiments are carried out with a great attention to the effect of surrounding temperature and humidity on brush wear. The sliding part of brush and slip-ring is put on the sealed box and the atmosphere in the sealed box is kept on the specified condition by temperature and humidity control system. The brush wear, contact voltage drop and slip-ring surface morphology are observed after the sliding test. From these results, in both cases of the high humidity (nearby 80%) and low humidity (nearby 20%), the brush wear are large. And the brush wear rate is the lowest around 60% relative humidity. However, the characteristics of brush wear under the 15C is not similar to others. When the surrounding temperature is changed, in case of the 20% humidity, the brush wear increases with increasing surrounding temperature. On the other hand, in case of 80% humidity, the brush wear increases with decreasing surrounding temperature. Consequently, the results clearly shows that the temperature and humidity not only affect the brush wear but also change the condition of the film formation on slip-ring.

A Frequency Modulated Continuous Wave (FMCW) radar using only in-phase channel is advantageous for automotive applications. In this radar, it is necessary to search the pairs of beat frequencies in an up-chirp mode and a down-chirp mode to measure the distances and the velocity of multiple targets similarly to a FMCW radar with both of in-phase and quadrature-phase channel. However the number of combinations to search the pairs is larger than that for the FMCW radar with both of in-phase and quadrature-phase channel. Therefore, false targets by mistaking the combination of these pairs increase. In this paper, we propose a novel measurement algorithm to reduce the false targets. We extract only the beat frequencies of the relatively moving targets using the differential frequency power spectrum of the up-chirp mode and the down-chirp mode. We can reduce the number of selected incorrect pairs by separating the stationary targets and the moving targets. We have conducted some simulations to confirm the capability of the proposed measurement algorithm. It was shown that the false target appearance probability is reduced without significant deterioration of the target detection probability.

Future high density magnetic recording requires a nanometer spaced head-slider interface, high track seeking velocity and high spindle speed. Such a combination greatly increases the likelihood of slider-disk and slider-particle-disk impact. Furthermore, the impact can generate high flash temperature and leads to data reliability problems, such as partial or full data erasure. This work report a method to conduct controlled experimental investigations into the possibility of such a data erasure even when the temperature is far below the Curie temperature. Results indicate that the high density magnetic transitions are of high likelihood of being affected by the flash temperature. Investigations also extended to micromagnetic modeling of the flash temperature effect. Results suggest that thermally induced local stress can play important roll in the data erasure process. Modeling results also exhibit that smaller grain size and higher recording density are also of higher likelihood of getting the transitions being affected by the flash temperature.

Efficient radio resource utilization and fairness are important goals that must be achieved since wireless ATM systems support various services with different traffic characteristics such as CBR and UBR. This paper proposes a novel delay-and-queuing data size-based MAC protocol for broadband wireless ATM. The proposed MAC protocol relies on a new resource scheduling algorithm that decides the priority of channel assignment based on both the queuing delay and the queuing data size in the transmission buffer. Simulation results confirm that the proposed MAC protocol is able to provide throughput fairness and to achieve excellent throughput performance for ATM services that experience dynamic traffic fluctuations.

The Infostation concept has been proposed to provide convenient and cost effective access to high-speed mobile data services. An efficient IP packet transmission protocol is required to compensate for the high error rate inherent to fading radio channels. In this paper, a novel link layer retransmission scheme is proposed. Using the channel state and fading state estimators, the scheme adjusts the retransmission parameters dynamically in order to achieve the optimum performance under time-varying channel conditions. A theoretical analysis is presented for the case of a random error channel. Furthermore, a simulation tool is developed for evaluating the performance of the scheme in a fading channel with various parameters. The analysis and simulation results show that this new retransmission scheme can provide substantial improvement over traditional schemes. It gives a robust performance in both slow and fast fading conditions. In addition, the algorithm's sensitivity to parameter values and channel characteristics, such as Doppler frequency and fading statistics, is investigated. A unique attribute of this algorithm and performance analysis is that throughput is evaluated in IP packets rather than in physical layer packets.

Coding and modulation tradeoffs for limiter-discriminator based CPM transceivers are examined in Rayleigh, fast fading environments. Comparisons are made on the basis of a fixed bandwidth to information rate ratio, so coded schemes and uncoded schemes can be compared fairly. It is shown that using the proper balance of modulation and coding is important to achieve good performance. It is found that combining bandwidth efficient modulation with convolutional coding achieves better performance than trellis coded modulation (TCM). The increase in performance as the code complexity is increased is also found to be larger for convolutional coding than for TCM.

An experiment was conducted to measure and compare the physiological effects of three types of CRT on users. We proposed a new strategy for measuring the user's level of relaxation. In this strategy, called "Task Break Monitoring (TBM)," the subjects took a break with eyes closed after each interaction with the computer. During each break, electroencephalogram (EEG), especially alpha 1 waves, electrocardiogram (ECG) and galvanic skin resistance (GSR) were monitored and recorded. The results show that the type of CRT display which emits far-infrared rays modulated by a FIR-fan induce less fatigue in users while they are working and reduce the recovery time after the task was completed. We believe "TBM" to be an important innovation in human computer research and development because the after effects of computer use have an obvious bearing on recovery time, user endurance and psychological attitude to the technology in general etc.

This work presents two novel algorithms to prevent rollback propagation for independent checkpointing: an efficient adaptive independent checkpointing algorithm and an optimized adaptive independent checkpointing algorithm. The last opportunity strategy that yields a better performance than the conservation strategy is also employed to prevent useless checkpoints for both causal rewinding paths and non-causal rewinding paths. The two methods proposed herein are domino effect-free and require only a limited amount of control information. They also take less unnecessary adaptive checkpoints than other algorithms. Furthermore, experimental results indicate that the checkpoint overhead of our techniques is lower than that of the coordinated checkpointing and domino effect-free algorithms for service-providing applications.