For investigating biological effects of a localized SAR (specific absorption rate) deposited in a human body for electromagnetic wave exposure, it is indispensable to graps a temperature-rise inside a human brain including the control center for the body temperature. This paper numerically analyzes a temperature-rise inside an eyeball of our developed realistic head model for 1.5GHz microwave exposure, using the FD-TD (finite-difference time-domain) method. The computed results are validated in comparison with the data obtained by Taflove and his colleague. In order to examine a quantitative relationship between the localized SAR and temperature-rise, we also obtained a tissue amount over which the localized SAR should be averaged so as to well reflect the temperature-rise distribution inside the eyeball.
It is well-known that transient electromagnetic fields caused by low-voltage electrostatic discharge (ESD) often gives a fatal shock to digital information equipment. This peculiar properties can qualitatively be explained by our previously proposed dipole model having a spark current, whereas the model is unable to predict any effects of charged metals on the ESD field level. This paper proposes a new ESD source model for estimating the transient field level caused by the spark discharge between charged metal spheres. The new model consists of numberless image dipoles placed so as to keep the same potential on the metal surface, which enables us to calculate the ESD field level by superimposing the fields due to each image dipole. In order to verify the validity of the new model presented here, we measure through a shielded loop probe the magnetic field waveform caused by the spark discharge between spherical metal electrodes.
Using the wavetheoretical analysis, this paper investigates the lasing characteristics of three sectioned single-mode DFB semiconductor lasers with chirped gratings. Analytical expressions are derived for the threshold gain and lasing wavelength of chirped DFB lasers. Numerical results show the sectioned chirped gratings have significant effects on the fine tuning of lasing wavelength and the improvement of the singlemode gain margin to the DFB lasers.
In this paper, we propose a new cooperative control method for multiple robotic systems that eliminates several issues in the discentralized control method. The proposed control method is constructed by extending a Passive Velocity Field Control (PVFC). It is easy to guarantee the stability in control, because the PVFC can keep the passivity of the controlled system. In this study, the cooperative control method is proposed and then it's stability is proven. Moreover, it is extended so as to control an internal force and to control a virtual time. Finally, the efficiency of the proposed cooperative control method are examined by computer simulations for cooperation tasks with two manipulators.
The adaptive frequency estimation has many engineering applications, and a lot of techniques have been worked out. In this paper, we propose a new computationally efficient adaptive frequency estimation algorithm which is based on the blocked variable sampling and the synchronous addition / subtraction processing (SAS). The SAS requires additions and subtractions only, which makes the new frequency estimation technique very attractive in terms of computation load. Extensive simulations are presented to reveal the performance of the proposed technique which is expected to have potential applications where the sinusoidal frequencies vary slowly around their nominal values and the estimation algorithm with small complexity is highly desired. The proposed algorithm is also compared with the DFT (FFT) and the conventional gradient-based IIR adaptive notch filter methods in terms of both estimation accuracy and computational complexity.
This paper deals with the treatment effects of the far infrared irradiation. The autonomic response was analyzed in order to evaluate the relaxation effects caused by infrared irradiation and to analyze the function of the peripheral nervous system. In an experiment, the local temperature, blood flow and ECG were measured during and post-irradiation. Infrared irradiation was found to cause an increase in parasympathetic activities. This result shows the relaxation effects of infrared irradiation. An increase in blood flow appeared a few minutes following the increase in skin temperature.
An Adaptive Digital Filter (ADF), which has palarel connected 2nd order IIR filters, for narrow band noise elimination is proposed already. The proposed adaptation algorithm, however, does not take account of delay caused by anti-alias Low-Pass Filter (LPF) and Analogue to Digital (A/D), and Digital to Analogue (D/A) converter. So, in real applications, the ADF implemented with Digital Signal Procceser (DSP) shows poor capability of eliminating narrow band noise. In this paper, we propose a method to compensate phase of output signal from ADF. The compensation is accomplished with lst order FIR filter inserted in the output line of the ADF. We also show how to set the coefficient values of the FIR filter. And, we scrutinize ability to eliminate noise and computational cost through practical implementation of the ADF and the proposed phase compensation filter.
In this paper we consider the force control of a one-link flexible arm with contact motion to an environment. Even in case of a flexible arm, we think that the optimal approach velocity reduces the contact force and realizes the smooth transition from the free space to the constraint space. However, the contact of flexible arms to environments may cause the excitation of link vibrations. For this reason, a vibration controller for the force control of the flexible arm is designed on the basis of the Integral Manifold Approach. This whole control system consists of both the proportional force control and the vibration control of the flexible arm. Then, the optimal approach velocity of the contact motion is calculated. Some experimental results are presented to show the effectiveness of the proposed control system and the optimal approach velocity.
In this paper, we propose a method of the automatic transcription system remarking zero outputs of comb filters. In the frequency domain, the comb filter has zero points at the integer multiple of the fundamental frequency. The fundamental frequency and harmonic frequencies of the musical tone can be eliminated by comb filters which are corresponding to the scales. In the method using comb filters which has already presented, 60 comb filters are required, and the processing time is too long to detect the scale of the 32th note. In the proposed method, we can estimate the scale of both monophony and chords using only seven comb filters and a few notch filters connected in cascade, and we can also detect the scale of the 32th note (62.5ms). We have done some computer simulations on transcribing the melody played on a piano. As a result, it is clear that the proposed method is useful to detect musical scale.
This study describes a simultaneous multiple points measurement system for the electrostatic voltage. The induced voltage caused by the electric charge is measured by the high impedance single MOSFET amplifiers. The 12×8 sensing arrays are adopted to measure the 2-dimensional voltage distribution. Moreover, a capacitive model around the gate of FET is proposed to design the probe figure for the detectors of the charge voltage. The induced voltage and the capacitance are numerically analyzed by the surface charge method. The capacitive model that mainly consists of gate capacitance is verified by this analysis. The dependence of the induced voltage on the length of the probe with an electrostatic shielding is also confirmed.
This paper proposes a system for incremental English-Japanese spoken language translation, the system behaving like simultaneous interpretation. Since spontaneous speech appears continuously, each stage of a machine translation system for spoken languages should work incrementally. However, machine translation systems which have been proposed so far can not achieve high degree of incrementality because of the difference in word-order between the source language and the target one. In this paper, the system utilizing some ill-formed expressions characterizing Japanese spoken language such as repetitions, inversions, ellipses, repairs and hesitations, we have succeeded in the incremental transfer from English to Japanese. An experimental system on the basis of a chart parsing framework has been implemented. To evaluate the system we have made an experiment with 278 English dialogue sentences. 228 of them are translated correctly, providing a success rate of 82.0%, and 47msec on the average was taken to process one word. These results show our technique to be useful for spoken language translation with acceptable accuracy and high real-time nature.
With the increasing number of on-board visual displays, it is important to develop such on-board displays as easy to see even in various driving environments, such as driving on a snow covered. In this paper, we propose a new displaying method based on luminance adaptation, one of the human vision properties, associated with luminance changes while driving. In this method, adaptation level of the driver is estimated with the luminance of inside and outside of the vehicle. Then, the luminance of the display is determined by the adaptation luminance in order to perceive the constant brightness of the display even in the different environmental luminance. Experimental results of subjective evaluation comparing the conventional display indicate the effectiveness of the method.
Power spectrum analysis of R-R intervals time series provides a noninvasive means of assessment of the regulatory activity of the autonomic nervous system. In this paper we examine the physiological sources of the very low frequency component (VLF In a range between 0.014Hz and 0.025Hz) of beat-to-beat fluctuations during periodic mental work load (MWL in mental arithmetic) and physical work load (PWL by bicycle ergometer). Mean amplitude of the VLF component is calculated from the DFT algorithm by area under VLF peak. We show that the periodic MWL and PWL evokes increase of the amplitude.
Scattering of electromagnetic waves by underground objects has received much attention in recent years. Sensing techniques have been developed to locate and identify various target objects under the ground, such as, cables for optical fiber communications, gas and water pipes, and ancient tombs for archaelogical evidence. However, the detection of buried objects with subsurface radar is a difficult problem, since the electromagnetic (EM) wave which propagates through the underground (a random medium), is scattered by objects, such as air gap, and rocks. Many unwanted scattered waves become the noise in the received signal and therefore signal processing of radar echo is very important for accurate sensing. Practically, some radar sensing systems which display EM wave scattering from underground objects are available. However, for archaelogical uses, higher resolution is needed. Considering the use of subsurface radar from archaelogical prospective, the field of sensing is always rough. The EM pulse transmitted by subsurface radar is mainly scattered from the random rough surface. In this simulation, we analyzed the received wave using wavelet transform. Wavelet is a new and rapidly evolving field. Wavelet analysis gives the variability of the oscillated data by each scale. Application of wavelet to remote sensing is very important and a great deplorement is expected.
High bit rate and high speed mobile radio communications using microwaves and millimeter waves are very attractive for wireless mega and giga bits LAN and video transmissions. Radio interferences due to multi-propagation paths and multiple scattering by street buildings and natural structures of hills and trees are very important problems for high bit rate mobile radio communications. Real time high speed signal processing for delayed fading noises may be required. Optical signal processing using optical and radio interactions are most useful method to accomplish real time high speed signal processing. Fundamental properties and applications of optical signal processors using optical active waveguide devices are shown for high bit-rate mobile communications.
Generally, robot arms with flexible joints are multi-mass resonant systems, thus causing mechanical vibration. Since the vibration deteriorates the arm position control accuracy, the vibration suppression is indispensable to achieve the high performance arm motion. The authors have already proposed a feedforward vibration suppression scheme using an optimal control command shaping. The scheme is suitable for practical industrial use because of its simple control algorithm, however, there still remains a problem inherent in feedforward techniques that parameter setting errors in controller have significant effects on the suppression control accuracy. This paper presents an adaptive feedforward control of the vibration suppression with on-line mechanical parameter identifier, based on the proposed command shaping. In this scheme, the on-line identification of arm inertia using a method of least squares is performed during acceleration in arm motion. The identified parameter is used during deceleration to suppress the residual vibration. Experimental results using a prototype show the effectiveness of the proposed control.
Recently, mobile communication is used in many environments. One of the main problems in mobile communications is scattering of electromagnetic waves by shielding objects. We have to take notice of a girder bridge or tunnel model into consideration. Because of the complexity of these models, the analysis of scattering using these models becomes very difficult. We considered an infinite conducting elliptic cylinder and rectangular cylinder near a perfectly conducting plane as a simple model. This model described by elliptic and rectangular cylinder and plane are replaced by girder bridge and ground plane, respectively. Propagation and scattering of electromagnetic waves in the presence of objects with elliptic geometry have many interesting features. In this paper, we obtained numerical results for these models using FD-TD method.
To achieve high performance control of a nonlinear plant such as D. D. (Direct Drive) manipulators, the disturbance force added on each joint and the nonlinear forces such as gravity and interacting forces should be compensated. Recently, the scheduled H∞ control, which guarantees global stability and high performance for nonlinear plants, has been investigated. In this papers, we propose a new control of D. D. manipulators using the scheduled H∞ control. Firstly, we treat the D. D. manipulators as a linear system with scheduling parameters. Secondly, we apply the scheduled H∞ control to it. Finally, we verify the effectiveness by some experiments.