This paper quantitatively evaluates the visibility of an object on the road illuminated by vehicle headlamps under tunnel lighting based on Total Revealing Power (TRP). First, we derived the critical reflectance for drivers to detect an object on the road to calculate TRP. Then, we characterized optical property of vehicle headlamps in the real tunnel, and evaluated the visibility of objects under vehicle headlamps and tunnel lighting. As a result the high beam headlamps ensured the visibility of reverse silhouette vision. We have shown that the visibility of the tunnel lighting is mainly silhouette vision. It revealed that the visibility of an obstacle on the road is not changed greatly depending on headlamps.

View full abstract

For reducing the hemodialysis time of kidney disease patients, we are attempting to monitor hemodialysis quality in a real time based on dielectric constants of blood. Using a network analyzer with an open-ended coaxial-type dielectric probe, we measured complex relative permittivities ranging from 200 MHz to 6 GHz for blood of eighteen kidney disease patients before and after hemodialysis, and then derived from them admittance consisting of conductance G [S/m] and susceptance B [S/m] in order to make statistical correlation analyses between the G-B plots and blood biochemical components. As a result, we found that significant correlations are observed between the parameters of the linear approximations to the G-B plots at frequencies from 4 GHz to 6 GHz and blood urea nitrogen or creatinine before and after the hemodialysis. This finding suggests a possibility of real-time monitoring of the hemodialysis quality.

View full abstract

The operating voltage of power electronics modules is increasing and it results in higher demands on the electrical insulation. Therefore, it is essential to overcome weak points in the insulation system. The weak points were specified by observing the trace of partial discharges (PDs) by a microscope. When the applied voltage is slightly above partial discharge inception voltage, streamer inception occurred at indented rims of the metallization. Silicone gel is used to encapsulate power electronic circuits. Sometimes the degassing is imperfect and voids may form. These voids induce PDs and limit the reliability of the module. As the indented rims may not be degassed and may contain voids, a simplified encapsulation technique is discussed quantitatively and was verified experimentally. The proposed encapsulation technique could reduce the number and amplitude of PDs.

View full abstract

For the development of higher voltage vacuum circuit breakers (VCB) and vacuum interrupters (VI), surface discharge phenomenon in vacuum is one of the most significant issues. We measured the charge activity on alumina dielectrics in vacuum through ultra-high speed optical and electrical measurements. We found out that the surface flashover in vacuum starts with an explosive electron emission (EEE) with the higher current density, which is the electron emission from the cathode, and results in the surface flashover development. Transient charge on the alumina dielectrics formed by electrons emitted by EEE influences the distortion of electric field distribution around the cathode rod and then the subsequent flashover development. Especially, in the case of the shorter gap between the cathode rod and the alumina dielectrics, the electron emission could be suppressed by the relaxation effect of the electric field due to the transient charge accumulation.

View full abstract

In general, dielectric barrier discharge (DBD) typed ozone generators are used for water treatment including drinking water and wasted water. Recently, it has been reported that composed ozone concentration by DBD type ozone generator decreases with time using high purity oxygen as a fed gas. The phenomenon is called “Ozone Zero Phenomenon”. As one of factors responsible for the occurrence of this phenomenon is speculated to be an influence from electrode surface, we have focused our investigation on electrode surface heating generated by electrical discharge. Rate of thermal decomposition of ozone by heated stainless steel (SUS) pipe and Pyrex glass pipe were evaluated by ozone concentrations at inlet and outlet of heated pipes. As a result, for temperature of heated both pipes below 120°C, thermal decomposition of ozone was not confirmed in each transit time (0.25-1.5s). However, when both heated pipes are over 160°C, thermal decomposition of ozone was found and the rate of ozone decomposition increased depend to transit time in heated pipes. It was thought that there were at the least 2 processes of decomposition of ozone: one is oxidation of surface of pipes, and another is thermal decomposition in gas phase. The former is enhanced at the stepwise increase of ozone concentration in stainless steel pipe below 160°C compare with Pyrex pipe. The temperature above 180°C, thermal decomposition is increased against the time in the both kind of pipes. This is considered decomposition of ozone in gas phase.

View full abstract

Efficient decomposition of perfluoro compounds in water was studied by combining plasma and persulfate treatments. Although plasma generated within bubbles in water could decompose perfluorooctane sulfonic acid (PFOS: C₈F₁₇SO₃H) rapidly and efficiently, the plasma treatment was not suitable for the treatment of the by-products with short carbon chains. Thus, a persulfate-added hot-water treatment was conducted after decomposing PFOS by 99% with the plasma treatment. The combination of the plasma and persulfate treatments for 200 mL PFOS solution at an initial concentration of 100 mmol/L decreased the treatment time from 430 min to 240 min, and increased the energy efficiency from 8.3 mg/kWh to 13.5 mg/kWh.

View full abstract

The two-dimensional resistive MHD simulation is carried out to find the mechanism of flux lifetime extension by means of axial neutral gas flow injection; it is thought as a process equivalent to FRC translation into a region where neutral gas is filled. We have derived the MHD equations with the source terms due to ionization of neutral particles. Extension of the flux lifetime has been found and its increment rate increases with the injection energy. We have investigated the flux variation calculated from the Faraday's law, and found that the inductive electric field due to the Lorentz force is a dominant reason for lifetime extension.

View full abstract

The sterilization methods of several drinks are mainly based on thermal sterilization process, as it is cheaper and easier to be performed. But thermal process may change the original taste of the drinks due to chemical change in it. But on the other hand, the non-thermal sterilization methods like Ultra Violet (UV) radiation, pulse light, filtration etc. are yet not to spread out due to the economical and technical problems. We have developed a non-thermal sterilization process controlling the motion of ferrite particles in the liquids. Ferrite particles are non toxic and they are ferro magnetic particles which motion can be easily controlled by magnetic flux. Ferrite particles were put in a plastic container with liquid. Two electromagnets were set up in vertical direction with a certain gap in between them. The container was hold in between the two electric magnets. These electromagnets were controlled by an AC supply. By controlling the movements of ferrite particles with liquids with different microorganisms, sterilization of the liquids had been achieved. This paper also describes the process of sterilization by ferrite particles. We also applied our process on Escherichia coli with different types of ferrite particles and achieved sterilization.

View full abstract

Si-gradient steel sheet, which has a silicon concentration gradient in the sheet thickness direction, manufactured by Chemical Vapor Deposition (CVD) Siliconizing process, possesses unique magnetic properties. In this paper, the magnetization behaviors of the single crystal of Si-gradient steel sheet are investigated in the direction <100> and <110>, comparing with Si-homogeneous steel sheet, in order to clarify the magnetization mechanism. The internal stress of Si-gradient steel sheet was evaluated. The induced magnetic anisotropy which arose according to the magnetoelastic effect is considered to play an important role in the magnetization process of Si-gradient steel sheet. The reduction of eddy current loss can be explained by the effect of the magnetic flux concentration to the sheet surface resulting from the internal stress.

View full abstract

The precursor of calcium cobalt oxide thermoelectric material was fabricated by reflux method. Cobalt acetate and calcium acetate were used as starting materials. We investigated the calcination temperature to obtain Ca₃Co₄O₉ and the effect of temperature raising rate on size of grains.

View full abstract