This paper describes fractal characteristics of luminance distribution on a male head statue made of plaster to express quantitatively modeling effect of the statue. The luminance distributions of the statue were measured by photographic photometry and CCD photometry methods. Both measured data obtained under various luminous environments were analyzed using the box-counting method. It was found that the distributions showed fractal characteristics in both methods and the main factors to determine the fractal dimensions were an image resolution of the photometry methods and vertical angle of the light sources. The fractal dimension decrease due to low resolution corresponded to indistinctness of the luminance distribution. On the other hand, the fractal dimension decrease due to low vertical angle corresponded to emphasizing the shadow. Paying attention to the latter fact, it was considered that the fractal dimension was useful as a modeling index of a human face under the condition that an image resolution was kept constant.

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This paper proposes the two approaches evaluating an electric field source distribution from locally measured electric field. We try to evaluate unique solutions of the inverse problem by means of the weighted inverse matrix and the vector sampled pattern matching (SPM) methods.
The weighted inverse matrix method is one of the generalized inverse matrix methods, which may be possible to give the good solutions when the solution is represented in terms of the continuous functions. The vector SPM method is an iterative solution strategy in order to obtain an approximate solution.
At first, the simple simulation examples are solved by both methods and compared in order to examine the nature of both solution strategies. Second, we apply both solution strategies to the electric field source searching from the locally measured electric field on a DC/DC switching converter.

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A ballast circuit with an inverter combined with a chopper (hereinafter referred to as a present circuit) is a circuit in which the inverter and the chopper share at least one switching element.
In order to have an added output control for dimming, the present circuit is required to give a control scheme of the switching elements for satisfying stable circuit characteristics over a wider range of load vari-ations. We have made an analysis to have stable circuit characteristics and optimization. Also, we have developed a new drive (termed as a self-and-separate complex excitation drive) for running the switching elements and realized a dimmer ballast for a fluorescent lamp having a dimmer ratio of 55% or less and a THD (total harmonic distortion) of 13% or less.

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We have studied two methods to compute parameters for the impulse voltage expressed by the double exponential functions under given front time and tail time. The first method is based on the Newton method and shows good convergence in several iterations over wide ratio of front time and tail time. The second method uses an acceleration factor to decrease the differences of time parameters which are given by the iteration process. We can determine a double exponential function under a millisecond by both methods. However, a short tail impulse needs more number of iterations than standard lightning impulse.

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We propose a new surface charge method based on the continuity of electric flux passing through each partial area on the dielectric boundary. N partial areas divided on the boundary give the boundary equa-tions for solving N unknown variables representing the surface charge density distribution. The electric flux is numerically calculated by integrating the normal component of electric flux density on each partial area. This method permits us to exclude the singularity of edge parts from the boundary equations because these parts do not contribute to the integration area. In this paper, we apply first-order functions to simulate both triangular surface shape and charge density distribution on its surface as well.
First, we have computed the electric field for a spherical dielectric under a uniform field. The calculated results show that the accuracy of the electric field at the spherical center is almost equal to the accuracy of the total surface area of the polygon which represents the sphere. Furthermore, this method has improved the accuracy of the field by about one order compared with the conventional surface charge methods. Sec-ond, we have computed the electric field for a dielectric human model under a uniform field. The calculated results demonstrates that the proposed method works well for a complicated shaped object with a dielectric constant greatly different from that of an ambient medium.

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It was elucidated from charge measured by the pulsed electro-acoustic (PEA) method that the accumulation and decay processes of interfacial charge in LDPE/EVA laminate. When dc voltage is applied to the laminate composed of two different kinds of dielectrics, the space charge will be accumulated at the interface, and cause to distort the electric filed in specimen. It is confirmed that its peak penetrates into LDPE and it may be drawn via the electric force. After short-circuit the interfacial charge on the EVA side attenuates fast and the charge jumped over the LDPE side decays slow.

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The current-voltage characteristics and the electrical responses of the electrorheological (ER) fluids were measured under DC electric field conditions. The test fluids consisted of microsphere particles with various moisture levels (in a range of 1500 to 7000ppm wt.%) dispersed in a dimethylsilicone oil (at 30wt.%). In these fluids, the relationship between the current density and electric field strength could roughly be fitted with sinh functions suggesting ionic conduction. The forces of cohesion between individual particles in the ER fluids were considered using the mathematical model in which the current passes through the surface layer of the particles. The current-force relationship predicted by the theory was compared to experimental results for the test fluids. It is shown that the particle conductivity in ER fluids plays a dominant role in the mechanisms of the ER effect.

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Spacecraft charging occurs in space environment especially in plasma and radiation environment. Spacecraft charging induces degradation of dielectrics, anomalies or breakdown of on-board electronics. Spacecraft Charging is classified into two cases. One is Surface Charging, and the other is Internal Charging. Surface charging occurs on the surface of a spacecraft in low energy ambient plasma. Internal Charging occurs when high energy (_??_MeV) charged particles penetrate deep into materials. Until now, it seems that only surface charging has been major subject of studies. Recently, however, it has been reported that there is possibility that internal charging is related somehow to discharging of spacecraft besides surface charging, which indicates that importance of internal charging will have to be recognized. In the past, nobody has tried direct measurement of charged particles in dielectric materials used on spacecraft. We developed real-time charge distribution measurement technique for dielectrics for spacecraft using PIPWP (Piezo-electric Induced Pressure Wave Propagation) method. In addition, we measured space charge distribution in PMMA film during electron-beam irradiation.

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A new vertical radiant-heating reactor has been designed and constructed for thick SiC vapor-phase epitaxy (VPE). Growth of 4H-SiC epitaxial layers is performed under a reduced pressure as low as 6.7×10³ Pa. A high growth rate exceeding 16 μm/h has been achieved in the reactor. Smooth surface is obtained by controlling the input C/Si ratio of source gases, and we have demonstrated growth of very thick layers over 160 μm with a mirror-like morphology. Low-background doping of 10¹³ cm^-3 range (n-type) and intentional n-type doping in a range from low 10¹⁵ to low 10¹⁹ cm^-3 have also been demonstrated. We have performed photoluminescence spectroscopy and deep level transient spectroscopy to check impurities and intrinsic defects in the epitaxial layers, and the spectra show that the layers have a good purity and quality.

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Dynamic contact-angle measurements based on Wilhelmy method were performed to evaluate time variation of loss and recovery of hydrophobicity of silicone rubber. The technique can determine both advancing and receding con-tact-angles of a plate sample and evaluate very short time variation of the surface properties.
By changing dipping speed of the samples to the water, immersing time and drying time in the air, some aspects of overturn and/or re-orientation of polar groups at the surface were observed as a change of the contact-angle. Also, the contact-angle of silicone rubber was compared with that of fluorinated silicone.

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Boron carbide (B₄C) is known as a material having hardness, wear resistance and stability at high temperature. It can be applied, for example, as a coating material for cutting tools. The preparation of thin film of B₄C, therefore, is very important from the viewpoint of the industrial applications. We have experimentally attempted to prepare thin film of B₄C using the pulsed ion-beam evaporation (IBE) technique, where high-density ablation plasma is produced by an intense pulsed ion beam interaction with the target. Various configurations of IBE have been studied by front-side, back-side and mask-side depositions. The crystallized B₄C thin films have been successfully deposited on Si(100) substrate by front-side and mask-side depositions. Absorptions associated with the B-C combination and the vibration of B₁₂-B₁₂ clusters have been observed by Fourier transform infrared spectroscopy. The Vickers hardness of the film deposited by front-side deposition is observed to be HV-2300.

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Electromagnetic shielding is popularly used to suppress electromagnetic noise generated from electronic equipments. It is important to know the shielding mechanism in designing the effective shielding. In this paper, the electromagnetic field in the vicinity of a horizontal multilayered medium with either a magnetic or an electric dipole source was calculated theoretically by a Sommerfeld integral, in which a spherical wave radiated from the dipole source is expanded into a large number of cylindrical waves. The integration formulas are derived and they are numerically calculated for investigation of shielding effectiveness and Poynting flux. We calculate electromagnetic shielding effectiveness to confirm the applicability of this analysis. Calculation results are in good agreement with measurement results. To clarify the shielding mechanism, Poynting flux from either a magnetic or an electric dipole source in the vicinity of shielding materials and inside the shielding materials is demonstrated. The electromagnetic wave with the shield is attracted by the shielding material, and shielding effectiveness depends on energy flow along the shielding material.

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Linear silicone chains synthesized from dimethyldiethoxysi lane are applied to a heat resistive coupling agent in polyamideimide(PAI) composite containing crashed glass. The silicone chains have an effect on improving glass-PAI adhesion. It is concluded that silicone chains serve as a heat resistive coupling agent.

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