排序方式: 共有33条查询结果,搜索用时 15 毫秒
1.
MASARU MIYAYAMA SHINICHI KATSUTA YOSHIHIRO SUENAGA HIROAKI YANAGIDA 《Journal of the American Ceramic Society》1983,66(8):585-588
Electrical conduction in tetragonal β-Bi2 O3 doped with Sb2 O3 was investigated by measuring electrical conductivity, ionic transference number, and Seebeck coefficient. The β-Bi2 O3 doped with 1 to 10 mol% Sb2 O3 was stable up to 600°C and showed an oxygen ionic and electronic mixed conduction, where the electron conduction was predominant at low oxygen pressures. The oxygen-ion conductivity showed a maximum at 4 mol% Sb2 O3 , whereas the activation energy for the ionic conduction remained unchanged for 4 to 10 mol% Sb2 O3 -doped specimens. These results were interpreted in terms of the oxygen vacancy concentration and the distortion of the tetragonal structure. The electron conductivity and its oxygen pressure dependence decreased with increasing Sb2 O3 content. The fact that Sb5+ is partially reduced by excess electrons in heavily doped β specimens at low oxygen pressures is explained. 相似文献
2.
Formation of the Pb(Zr,Ti)O3 solid solution in the system PbO-TiO2 -ZrO2 was studied by chemical analysis and X-ray powder diffrac-tometry. Only PbTiO3 and Pb(Zr,Ti)O3 were found as reaction products. The following three elementary reactions seemed to be reasonable for the formation of the Pb(Zr,Ti)O3 phase: PbO + TiO2 → PbTiO3 , PbTiO3 + PbO + ZrO2 →Pb(Zr1-λ Tiλ )O3 , and Pb(Zrl-λ Tiλ )O3 + PbTiO3 → Pb(Zr1-λ' Tiλ' )O3 (λ<λ'). 相似文献
3.
YOSHIHIRO ABE KOICHI KAWASHIMA SUGURU SUZUKI 《Journal of the American Ceramic Society》1981,64(4):206-209
Coloring and bleaching of reduced phosphate glasses in the systems K2 O-B2 Or Al2 O3 -P2 O5 and K2 O-Al2 O3 -P2 O5 , containing no silver halide, were studied. The as-cast glasses, which are colorless and transparent, become tinged with red when they are reheated at high temperatures for long times. The bleached specimens (PTC-RP glass) are obtained by heating at >600°C, then quenching. The PTC-RP glasses exhibit coloring phenomena by irradiation of light or by heating above 200°C; the colored glasses are again bleached thermally. Coloring of the glasses by heating is described in this paper in terms of phase change within the colloidal phosphorus formed in the glasses. The apparent activation energy for the thermocoloring is estimated to be ∼15×104 J/mol (35 kcal/mol). 相似文献
4.
R‐θ two‐dimensional numerical simulations have been carried out to clarify the plasma behavior in a high‐temperature noble gas plasma disk‐shaped magnetohydrodynamic (MHD) generator. At low inlet total temperature and high load resistance, the plasma has spiral structure which is similar to the nonuniform structure under the weak noble gas ionization condition in a seed‐plasma MHD generator. As seen in a linear‐shaped Faraday‐type MHD generator, the plasma becomes stable with increase in the inlet total temperature because the coulomb collision of electrons becomes dominant. Even at low inlet total temperature, the ionization instability can be suppressed for low load resistance, because the relatively low electron temperature due to less Joule heating makes the ionization relaxation time longer than plasma residential time. 相似文献
5.
KOHEI SHIMAMURA MASAYOSHI KOIZUMI YOSHIHIRO MIZUNO KIMIYA KOMURASAKI 《Electrical Engineering in Japan》2016,197(1):46-54
Wireless power transfer using a metallic tube with an axial slit was attempted to demonstrate the wireless power transfer using magnetic resonance coupling to the diagnostics infrastructure. The transmission efficiency with variable distance was measured using the transmission and receiver resonators in the tube. Besides, the transmission and receiver resonators were, respectively, set outside and inside the tube. These experiments are carried out in the computational study using FDTD method. 相似文献
6.
This paper is concerned with the problem of determining eigenvalues, retained in Marshall's reduced order model, which have the largest effect on the retaining state vector or give the best approximate reduced system in the sense of ISE criterion. The main objective is to show that the usual choice of eigenvalues in Marshall's model reduction technique (decomposition of eigenvalues into fast modes and slow modes) does not necessarily give a well approximated reduced order model. Here the measure of approximation is defined and calculated by means of ISE criterion. The effectiveness of this method is explained by two illustrative examples. 相似文献
7.
EFFECT OF FROZEN TEMPERATURE ON AUTOXIDATION AND AGGREGATION OF BLUEFIN TUNA MYOGLOBIN IN SOLUTION 总被引:1,自引:0,他引:1
The effect of frozen storage temperatures in the range of -3C to -80C on the autoxidation and aggregation of bluefin tuna oxy- and deoxy-myoglobin (Mb) in solution was examined. Mb solution was kept frozen at various temperatures after prefreezing by dry ice-acetone and examined for autoxidation rate constant and aggregation ratio. The temperature-dependency of these two parameters showed the highest values at -10C with both oxy or deoxy forms. The autoxidation rate constant of deoxyMb was higher than that of oxyMb between -6C and -20C, while the reverse trend was observed at lower temperatures. These results suggest that the structure of Mb was perturbed through freezing resulting in promotion of the autoxidation and aggregation of Mb simultaneously. These results could explain the observation that deoxyMb in the inner portion of tuna flesh discolors faster than oxyMb in the surface portion in the temperature range of -3C and -20C. 相似文献
8.
Alleviation Technique for Thermal Concentration on Specific Switching Devices in Zero‐Speed Driving of PMSM
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, a technique is proposed for alleviating the thermal concentration on specific switching devices by using a zero‐sequence voltage in a three‐level inverter that drives a permanent magnet synchronous motor (PMSM) in a zero‐speed and high‐torque condition. The use of the PMSM in home electronics and industrial products has become widespread, since it can realize miniaturization and a high efficiency drive. However, a large DC current flows when the PMSM is used in a zero‐speed and high‐torque condition, for example, in the hill‐start of electric vehicles, start or stop of elevators, or servo lock of servo pressing machines, and so on. In these cases, the current flows in the specific switching devices and heat generation is locally concentrated. This problem is unavoidable in a conventional two‐level inverter. A technique that can change the current path in a three‐level inverter and control the losses generated in the switching devices is proposed. We evaluated the effects of the proposed technique through a circuit simulation in which the electrical characteristics of a commercially available power device were applied. The proposed technique can reduce the highest loss of the switching devices in the three‐level inverter by about 40% as compared to that in a conventional inverter. Moreover, a method is proposed that suppresses the neutral point potential variation between the power supplies. This method can also reduce the maximum loss of the specific switching devices by about 30%. 相似文献
9.
Method for Diffusing Carrier Noise under Zero‐Speed Condition using a Zero‐Sequence Voltage
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, a technique is proposed to reduce the carrier noise of pulse width modulation (PWM) inverters for a permanent magnet motor drive. The carrier noise is generated by the motor and the reactor driven by the inverter and affected by the switching frequency. When a motor rotates and drives a machine, the carrier noise is hidden by the machine noise. However, when the motor speed is approximately zero, the carrier noise becomes dominant and raucous. The typical method to reduce the noise employs a switching frequency higher than the audible frequency of human hearing. However, the increase in switching frequency results in the inverter suffering a higher switching loss and lower efficiency. In particular, when the permanent magnet motor operates at approximately zero‐speed and full‐load, for example, in the hill‐start conditions of electric vehicles and the start and stop conditions of elevators, the current flows in specific power devices and the switching loss further increases. The proposed technique uses a zero‐sequence voltage, which is generated randomly with the M‐sequence signal, and diffuses the frequency components of the ripple contained in the current. The technique is able to reduce the noise without increasing the switching frequency of the inverter when the motor speed is almost zero. Simulation and experimental results show that the proposed technique can diffuse the carrier noise and the cycle of the M‐sequence signal changes the diffusion effect of the carrier noise. 相似文献
10.
The plasma fluid flow behavior and power generation characteristics in a Faraday magnetohydrodynamic (MHD) generator using a high‐temperature inert gas (argon) plasma have been examined in a time‐dependent two‐dimensional numerical simulation. The inhomogeneous and unstable plasma at an inlet total temperature of 7000 K results in reductions and fluctuations in the output power. The plasma becomes homogeneous and stable as the inlet total temperature increases to 9000 K. One of the reasons for the suppression of ionization instability may be weakness of the dependency of the electrical conductivity on the electron number density, because the Coulomb collision of electrons becomes dominant during deviation from Saha equilibrium. 相似文献