The resonance properties of the unslanted, planar diffraction gratings are presented and explained by means of modal expansion theory with a almost periodic functions for dielectric gratings. It is shown that these structures function as filters that produce complete exchange of energy between transmitted waves and reflected waves with smooth line shapes and arbitrarily narrow filter frequency bandwidths. Furthermore, the frequency bandwidths and the resonance frequencies can be controlled, separately, by the grating modulation amplitude and the grating thickness. The diffraction grating can be utilized as the optical resonance filter that represents a basic optical element with significant potential for practical applications.

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A negative input-output characteristic was obtained in an erbium doped yttrium aluminum garnet crystal which has multiple-level energy structure: absorption can occur between a ground level and an excited level (⁴I_15/2-⁴I_9/2) and between two other excited levels (⁴I_13/2-²H_11/2) in Er³⁺. It was caused at the wavelength between 786.6 and 788.4nm by the variation of incident laser intensity in the intensity range of 60 nW/cm² to 100 W/cm². It is considered that an enhanced absorption occurs due to the excited state absorption from ⁴I_13/2 to ²H_11/2. Because its spectra match the wavelength dependence of the incident laser. In addition, optical signal inverter phenomenon was observed using a laser diode modulated with 10 MHz. By considering multiple excited state absorption in detail, active functions such as an optical signal inverter could be derived from the negative nonlinear absorption effect.

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Pinch strength is the muscular strength exerted by the fingertips when an object is grasped between two fingers. Since daily work provides many instances in which the hands are used, decreased pinch strength can be considered a symptom of fatigue. This paper describes the development of a portable pinch strength dynamometer. It can be used during a short break while on the job, driving a car, and so on. Two boards with an air chamber sandwiched in between them are pinched between two fingers, and a gauge measures the pressure inside the air chamber. An examination of the device's accuracy showed that it is able to produce accurate pinch strength measurements. The following two experiments were conducted.
1. To measure the pinch strength of a driver and fellow passengers of a car, and the rider of a motorcycle during short breaks while coming and going on a 2000 km trip.
2. To measure the pinch strength of 14 workers in a watch assembly plant during working hours for one week including a holiday.
With these data, the measurement of the physical and mental work load and fatigue by the dynamometer is expected.

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Electrocardiogram has been developed to biological body surface potential, by many-points measurement on body surface, increasing measurement points from 3 points to a, few hundreds points. Medical body surface potential problems are very important for practical clinical technology, and these concern the electromagnetic field problems of electric current generated from cardiac cells of the heart, and have boundary value problems of Neuman type.
Analytical methods and numerical methods, such as finite element methods, have been used to obtain approximate inverse solutions for medical or biological body surface potential problems. However, exact inverse solutions of inverse potential problems on cardiac current fields have not been derived. In this paper, conformal mapping method, using singular potential functions and image method, is shown to give precise inverse solution for cardiac body potential problems.

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In this paper, we propose a new approach to designing visual displays for older people based on a human vision model. We have developed a system to simulate a human vision using image processing techniques. The model is represented by three vision properties; the contrast sensitivity of eyes, the spectral transmittance of crystalline lens and the accommodation. which are found in the visual science literature.
In order to compensate deteriorations of human vision with age, the image enhancements by sharpening edges and by changing color balance are used.
Simulated results are shown in the application of automotive displays, including a navigation system and a speedometer. And the improvement of visibility has been obtained in the subjective experiment using compensated images for various age groups.

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Recently, microwave techniques incorporating advances in signal processing have been developing rapidly. In particular mapping of sub-surface random ground and detection of underground objects are important applications. As a consequence, underground radar systems which display the scattering field patterns of electromagnetic waves have become practical. However, due to randomness and inhomogeneous nature of the underground media, it is very difficult to analyze their characteristics accurately. In principle, it is necessary to study electromagnetic wave reflection and scattering under various conditions of underground media. One of the most powerful methods of computational analysis applicable to such problem is the Finite Difference Time Domain (FDTD) method. In this paper, we apply FD-TD method to simulate the scattering characteristics of an underground media consisting of an air gap target region in the presence of randomly located obstacles. Statistical representation of a random media is done, and the relationship between the received signal and the media is established.

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Conventional artificial intelligence (AI) system has been criticized for its brittleness under dynamically changing environments. Therefore, in recent years much attention has been focused on the reactive planning approach such as behavior-based AI. However, in behavior-based AI approaches, the arbitration among competence modules is still an open question. On the other hand, biological information processing systems have various interesting characteristics viewed from the engineering standpoint. Among them, the immune system plays an important role in maintaining its own system against dynamically changing environments. Based on this fact, we have been investigating a new decentralized consensus-making system for the behavior arbitration of autonomous mobile robots inspired from the idiotypic network hypothesis in immunology. In this paper, we propose a reinforcement learning method using advantage of the proposed network architecture. To confirm the validity, we carried out some simulations.

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In motion control applications, servo drive systems have widely applied to various load systems with complicated mechanisms. A robot arm with flexible joints is one of typical examples and it forms multi-mass resonant systems which generate mechanical vibration. Since such vibration gives tracking errors in motion and/or increase of settling time, the vibration suppression is indispensable to achieve the high performance robot arm motion. Many schemes such as model-based feedforward control and modern control theory-based feedback control have been proposed to overcome those problems.
This paper presents a new feedforward control scheme using optimal control command shaping to suppress the resonant vibration in robot arm motion. By analyzing characteristics of the conventional position controller with the S-shaped position command, an optimal command design can be examined to eliminate the resonant vibration. Based on these analyses, a new command shaping algorithm is proposed. The proposed feedforward scheme can obtain the same vibration suppression characteristics as those by the conventional feedback schemes, regardless of the simple input position command shaping. Experimental results with a prototype show an effectiveness of the proposed control.

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Since the shape of color gamut differs for each color reproduction device, it is necessary to transform the colors in order to fit them into the reproducible colors, called Gamut Mapping. However, there have been no practical method for gamut mapping so far because it is difficult to describe the shape of gamut effectively. In this paper, we propose a method of extraction and mapping of destination color gamut based on mutual color space conversion between device-dependent and -independent color spaces performed by two multilayered neural networks. Furthermore, we propose a novel method for gamut mapping which adjusts compression ratio adaptively to the shape of gamut.

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Linear actuators are used often in electromagnetic devices. It is necessary for the optimum design to analyze the dynamic characteristics of linear actuators. It is difficult to obtain the dynamic characteristics of linear actuators which have long stroke by the conventional method, because the conventional method are limited to actuators which have short stroke. A new method using the finite element method to obtain the transient dynamic characteristics taking into account the motion of the armature, which have long stroke, has been developed. The new method combines the meshes of the armature region and the stator region automatically. The method makes it possible to analyze the dynamic characteristics of linear actuators exactly. The new method is applied to obtain the static and dynamic characteristics of a linear solenoid valve. The validity of the new method is confirmed by the experiment.

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It has been widely accepted that the physical stimulation, like illumination, music and environmental variables having a 1/f fluctuation power spectrum, relaxes a person. There should, however, exist a number of the stimulation waveforms that have 1/f power spectral characteristics, and thus the parameters of the waveform in the time domain causing comfortable biostimulation remain unknown. As a first step in elucidating what kinds of biostimulation waveforms relax a person, this paper theoretically derives CRD (Crossing Rate Distribution: the number of times per one second where the amplitude crosses various levels in the positive direction) and APD (Amplitude Probability Distribution) for a Gaussian fluctuation waveform with a 1/f-like power spectrum. Flame fluctuation of candles which is said to cause a sedative effect to a person is statistically measured. The findings obtained here show that the flame has the peak crossing rate of 0.08 to 0.4Hz, fluctuating with the rhythm close to person's blood pressure (0.1Hz) or breathing (0.25-0.33Hz).

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The skin tissue of a human head can play an electromagnetic shielding role in protecting the central organs from microwave exposure. For the electrical properties, however, the publication data are being widely scattered from fat (low water content) to muscle (high water content), and thus various electrical properties of the skin tissue are used for SAR calculations in a heterogeous head model. This paper examines numerically how variations in electrical properties of the skin tissue have an effect on the SAR in a human head. Skin tissue properties are newly estimated from a Debye equation with two relaxation time constants, which are used to calculate the SAR in an our developed heterogeous head model for 1.5-GHz microwave exposure. The SAR details are compared with the following cases: the results computed for the skin tissue having the same electrical properties as those of fat, our previously obtained results and the results computed for the Furse's tissue properties. The effects of tissue mass densities on the SAR calculation are also examined.

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In this paper, we proposed a new algorithm RVHT (Randomized Voting HT). RVHT is an improved PHT, in which edge points are deleted from the edge image according to the sequential line detection process of PHT.
The relations between RVHT and RHT algorithms were discussed both experimentally and theoretically. It was clarified theoretically that RVHT becomes strictly equivalent to RHT when the sequence of the combinations of two edge points is selected in a specified order, and experimentally that the proposed RVHT can detect shorter edge lines than RHT by using real microscopic images. As a result, several practical knowledges were presented for the practical use of Hough transform.

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