Various phantoms are used to predict the specific absorption rate (SAR) in a human head for radio-wave exposure. To study a head phantom for estimating the SAR due to microwave exposure, this paper numerically examines the dependence of the surface-SAR on head tissue structure in two kinds of head models: an anatomically detailed head-model and realistic shaped homogeneous model. The finite-difference time-domain method is used to compute the surface-SAR for 750 MHz and 1.5GHz far-field exposures. The spatial patterns of the one-gram averaged suface-SAR are compared between the above head models. Their correlation relationships are also discussed. The findings obtained here suggest that in experimentally predicting the surface-SAR in a human head for microwave exposure, a realistic shaped homogeneous head model can be used as a head phantom.
With the proliferation of on-board information in recent years, vehicle display devices, such as navigation system, have multiplied and instrument panels have become very complex. Still, a driver must be able to see and understand the information. For safe and comfortable driving, there are increasing demands for improving visibility of the onboard display. There have been various reports for visibility of the display. But, most of the reports have been on the evaluation by human sense, and there has been few for the visibility evaluation during vehicle driving. This paper describes the method for detecting the driver's eye movements using the facial images illuminated by infrared light source with a single TV camera on dashboard, measuring the gaze duration and evaluating visibility in driving. In addition, the usefulness of the navigation system with voice route guidance compared with a conventional non-voice system has been demonstrated using the measuring system based on this method by day and by night.
A 3-D corner reflector antenna (3D-CRA) exhibits more sharper radiated beam when its primary radiator, a monopole antenna, is extended and operated at higher order modes. For numerical analysis, UTD which is a, simple but accurate high frequency technique is useful. Optimization of the structural parameters of a 3D-CRA to obtain optimized directivity under the condition of the sidelobe ratio less than -20dB was performed by applying UTD. This showed that the possible maximum length of the rnonopole is 9/4 λ Experiment has been conducted for a 3D-CRA with optimized structural parameters. For thinner monopoles, e.g. 1/30 λφ, we have obtained results which are close to the expected theoretical characteristics, but the power gain is 22.7 dB (corresponding to 70% aperture efficiency) which is greater than the maximum directivity expected in theory. However, thicker monopoles, e.g. 1/10 λφ, exhibit broader frequency characteristics, and the sidelohe level is lower than -20dB even for the case of 13/4 λ monopole.
A numerical scheme to analyze a three-dimensional perfectly conducting body that has edges and corners is presented. The geometry of the body can be arbitrary. A new 3-D formulation using boundary element method (BEM) has been developed. The 3-D fields exhibit jump discontinuities at material interfaces and singularities at edges or corners, and thus a general linear vector basis function is insufficient. This formulation allows that a scatterer has edges and corners, where the behavior of the electromagnetic fields become singular. The objectives of this paper are to provide a foundation for the use of basis functions representing the singularities at edges and corners, and to demonstrate the implementation of these functions in a 3-D scattering formulation. Results are presented for scattered field patterns and induced current distributions on the body. These results are compared with analytical solutions and the agreement is found to be good. The present study shows that the scalar basis functions produce remarkably accurate scattered fields.
In this paper, a robust control strategy is proposed for hybrid position and force control of two-link elastic robot manipulators. Both the structured uncertainty caused by the nonlinear mechanical structure and the unstructured one caused by elasticity of links are considered in designing controllers. By using the integral manifold approach the model is reduced to the slow and the fast models. The slow controller, which is robust against the structured uncertainty, is designed for the slow model on the basis of VSS theory. And, the fast controller, which is robust against the unstructured uncertainty, is designed for the fast model on the basis of H∞ control theory. Then the composite controller is constructed. Simulation results are presented to show the effectiveness of this design procedure.
Although scene simulation with computer graphics has been done at the planning stage of buildings and cities, no system has been reported which performs interactive simulation. We developed a system for the design and modification and simulation of city planning with real-time interaction. By this system, we can comparatively evaluate several plans, since attributes of objects in the scene can be changed quickly with GUI-based operations. A scene database is designed to handle enormous scene data efficiently and is put at the core of the system. Comfortable scene evaluation is realized in the experience (simulation) system by viewing the scene from arbitrary viewpoints as if in a virtual train, car, plane or as a walker.
A micro solar boat(MSB), a miniature boat of 1mm×0.8mm×0.15mm driven by a light beam, has been developed by use of wafer processing techniques of semiconductor devices. The driving principle, the fabrication processes of a micro solar cell and driving electrodes, and the result of sailing experiment are described. The driving force is created by the reaction from flowing liquid, the flow of which is generated by a drag force of ions in the liquid. To accelerate the ions in one direction by a low DC voltage, a pair of special electrodes and a particular liquid are used: an interdigitated elec trode has half-covered fingers, while the liquid contains molecules that can be both plus and minus ions. The body of the MSB was made of semi-insulating GaAs. On the front surface four micro solar cells connected in series were formed to provide the output voltage of over 3 V, and on the rear surface the driving electrodes were formed with fingers of 20μm width. Under illumination by a laser beam of 2.3mW, the MSB proceeded in an expected direction at the maximum speed of 6mm/min.
This paper presents a new approach to computing multiple inverse kinematic solutions for redundant manipulators by inverting modular neural networks. This approach is a three-phase procedure. In the first phase, the configuration space is partitioned into a set of regions to learn the forward kinematic function of a manipulator, and a set of modular neural networks is trained on associated sets of input-output data sampled over these regions. In the second phase, multiple inverse kinematic solutions for a desired end-effector position are computed by inverting the corresponding trained modular neural networks. In the third phase, an “optimal” solution is selected from the multiple inverse kinematic solutions according to a given criterion. The important advantage of this approach over existing methods is that an “optimal” inverse kinematic solution can be obtained from the multiple solutions. Therefore, better control of the manipulator can be achieved. This approach is illustrated with a three-joint planar arm.
In this paper, a new partial-normalized least mean square (partial-NLMS) algorithm for updating the coefficients of an adaptive FIR digital filter (ADF) is proposed. The new adaptive algorithm is modified to overcome the NLMS method's problem, about unstability when very small input enters into the filter, and the LMS method's gradient noise amplification problem by using the preset value pσ2x to decide which method is to be used. This value is determined beforehand by the knowledge of the statistical properties (probability density function and variance) of the input signal. In the new partial-NLMS (P-NLMS) algorithm, the measured input signal's square norm is compared with the preset value pσ2x. If the square norm is larger than pσ2x the coefficients of the ADF are renewed by the NLMS algorithm. Renewal of the ADF's coefficients is done with the LMS algorithm when the square norm is smaller than pσ2x. The simulation results and theoretical analyses show the effectiveness of the proposed P-NLMS, and a good agreement between both results. The saturated residual error of the P-NLMS ADF under the noisy circumstances is smaller than that of the ordinary NLMS ADF and also have good stability. Even in bad condition, corrupted input, the proposed method still shows good performance.
According to increases of the computer controlled mechanics, native feature of the machine, is locally compensated So that outer loop controller can be easily designed. e.g., exact linearization techniques. When such a control method is implemented and some assumed condition is not likely to be satisfied. the system should automatically recover the normal condition automatically without conflicts of the human operator who does not know the native feature of the system well. In this paper we investigate a new configuration of master-slave system, namely a heterogeneous constrainted master-slave system which consists of a holonomically constrained master system and a non-holonomically constrained slave system. As a concrete example of the heterogeneous constrained master-slave system. we cousider a three wheel cart as the slave system and an actuated joy-stick as the toaster system. and a coordination of the system and the human operator which keeps an internal state of the input-output linealized slave system bounded is discussed. The coordination is realized as a fictitious force which the human operator can feel through the master system. The effectiveness of the proposed method will be shown by a numerical simulation and an experimental system.
Precision position control techniqes using moire signals have been investigated. First. the calculated results of the moire signals are compared with the experimental results. Good agreements were obtained between these results. Secondly, two position control techniques using moire signals have been investigated under the same experimental conditions. One is a differential moire technique using two grating pairs. The signals obtained by the grating pairs are out of phase 180 each other. In this technique, a differential moire signal between the two moire signals is used as the control signal. In-phase noises in the moire signals are cancelled and the S/N ratio of the signal is improved. Therefore, high positioning accuracy is obtained by this technique. The other is a modified moire technique. In this technique, only one grating pair is used. An inverted moire signal is calculated by a computer from the experimentally obtained moire signal. The positioning accuracies and S/N ratios are compared between these two techniques. The accuracy and the S/N ratio for the differential moire technique were better than those of the modified moire technique. However, the system using later technique is simpler in construction.
Description and recognition of object is one of the central consideration of research of the computer vision. It is the key issue that how to represent 3D objects on machine for recognition of them. Researchers of computer vision are used to employ EGI model, but it's not able to express concave objects. In this paper, MEGI model and coefficient of extended spherical correlation have been proposed. MEGI model is an extended EGI model to represent concave objects. Extended spherical correlation is the measure to recognize object using MEGI model. It has been demonstrated that this model is able to recognize 3D objects which is included concave one and to distinguish objects using a part of MEGI which makes from range data.
Tapered couplers between optical fibers, and laser diodes or integrated circuits are very important components for optical communication and optical signal processing. Mode matching at the tapered junction of optical circular waveguide is required to obtain high efficiency and low loss in optical circuits. In this paper, electromagnetic fields in tapered couplers with the inhomogeneous refractive index are investigated for general optical waveguides with arbitrary cross sections. The optimum designs for tapered shape and inhomogeneous refractive index in matching coupler are found by the integral equations using conformal mapping. This method has been developped by the author for the analysis of the complicated millimeter waveguides. Electromagnetic mode conversions and reflections in axial symmetric circular tapered couplers are discussed by integral equations with Green's dyadics and conformall mapping.
Solid friction in machine elements is one of the dominant nonlinearities affecting the control accuracy of servo drive systems. Many schemes such as feedforward control, observer-based control, and repetitive learning control have been proposed to compensate for the nonlinear friction. Those schemes show the superior performance comparing to that of conventional P-and/or PI-controller, however, model errors of the friction and the restriction of bandwidth of the observer cause compensation errors, thus decreasing in control accuracy. This paper presents a new control algorithm for performance improvement of a motor speed control system having the nonlinear friction. By analyzing characteristics of the conventional compensation control schemes during the reversal of velocity, the relation between control parameters and control accuracy is examined to present problems of each scheme. Based on these analyses, a new feedforward control algorithm is proposed. The proposed algorithm is verified by analyses of control characteristics and experiments using a prototype. Experimental results show the superior performance improvement of the proposed algorithm.
Term Rewriting System (TRS) is one of the simplest computation models for functional programming languages. It can also be used to model term manipulation required in program verification and transformation. In such applications, an environment for term rewriting with user friendly graphical interface is strongly required for analyzing structure of terms and rewriting processes. Most TRS interpreters developed so far are text, based ones, and hence they do not provide sufficient supports for analyzing structure of terms. We have proposed a new idea for a term visualization based on Graphical User Interfaces (GUI)  . This paper shows how to realize the idea with the functional programming language Standard ML (SML). We illustrate the implementation can be easily modified and extended since the rewriting part and GUI part of the program are clearly separated owing to the module system of SML.
The genetic algorithm (GA) is one of the basic models of evolution and is one of the effective tools for constructing evolvable/adaptive complex systems. One of the difficulties of the GA is its low performance in improving local portions of chromosomes. The authors have proposed a local improvement mechanism for the GA which is efficient for the local improvement. This paper proposes a new algorithm which introduces a hill-climbing to the GA with the local improvement mechanism. The proposed method is very efficient in improving the local portions of chromosomes by doing hill-climbing of each portion of chromosomes. To demonstrate the effectiveness of the proposed method, evolutions of arm morphology and throwing motion for throwing a ball under limited link torques is simulated.
This paper proposes a new approach to realize a high performance real-time OS using VLSI technology. In this method, quick and steady response can be guaranteed by implementing basic operations of a real-time OS as a peripheral chip (Silicon TRON) to be connected to general purpose microprocessors. In order to confirm the effectiveness of this method, most basic system calls of μITRON have been designed using an HDL. According to the evaluation results based on an FPGA implementation, hardware portion of these functionalities can be executed within 3 clocks and the task scheduling can be performed within 9 clocks simultaneously, which are about 2 to 7 times faster than software implementation. Accordingly, high performance real-time systems can be realized by the proposed method.
This paper presents a new coding method of DNA chromosome for Genetic Algorithm (GA). The DNA chromosome is composed of four kinds of basic components.This DNA coding method makes applications of crossover and mutation operations easier. The proposed method has a redundancy in DNA chromosome and allows overlapped representation of genes. The new method applied to a knowledge acquisition of fuzzy rules of robots which avoid collision with other robots and reach goals. This paper also presents an application of transcription of DNA, virus DNA and enzyme operators into the proposed DNA coding method.