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排序方式: 共有361条查询结果,搜索用时 15 毫秒
351.
Toru Takahashi Takayasu Fujino Motoo Ishikawa 《IEEJ Transactions on Electrical and Electronic Engineering》2013,8(5):440-445
Numerical analyses of the experimental‐scale scramjet engine driven magnetohydrodynamics generator implemented in the Hypersonic Vehicle Electric Power System project have been carried out to clarify plasma behaviors and power generation characteristics. Three‐dimensional numerical analyses have been performed under the two inlet conditions: one is the uniform inlet temperature condition, and the other is the nonuniform inlet temperature condition. Under the nonuniform inlet temperature condition, the generator performance approximately agrees with the experimental result. The tendency of the voltage loss is also reconstructed near the power takeoff electrodes though the voltage loss is smaller than that observed in the experimental result. The electric power output under the nonuniform inlet temperature condition is 40% smaller than that under the uniform inlet temperature condition. This is because the ratio of the Joule dissipation to the work by the Lorentz force increases owing to the decrease of active generator region as the current concentrates in the high‐temperature region when the inlet temperature nonuniformity is considered. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
352.
Kenjiro Fukuda Tsuyoshi Sekitani Ute Zschieschang Hagen Klauk Kazunori Kuribara Tomoyuki Yokota Takushi Sugino Kinji Asaka Masaaki Ikeda Hirokazu Kuwabara Tatsuya Yamamoto Kazuo Takimiya Takanori Fukushima Takuzo Aida Makoto Takamiya Takayasu Sakurai Takao Someya 《Advanced functional materials》2011,21(21):4001-4001
353.
To achieve the stabilization of greenhouse gas (GHG) concentrations in the atmosphere, the international community will need to intensify its long-term efforts. Many EU countries have released national long-term scenarios toward 2050, and their ambitious targets for CO2 emission reduction are aiming at a decrease of more than 50% of today's emission. In April 2004, Japan began a research project on its long-term climate policy. This paper discusses the long-term scenarios in other countries and the medium-term scenarios in Japan to support the development of a Japan's long-term climate stabilization scenario. In this study, CO2 emission is decomposed with an extended Kaya identity (indexes: CO2 capture and storage, carbon intensity, energy efficiency, energy intensity, economic activity) and a Reduction Balance Table is developed. 相似文献
354.
Porous monolithic SiO2–poly(vinyl alcohol) (PVA) nanocomposites were fabricated by drying an SiO2–PVA suspension. Depending on the amount of added PVA and pH value of the suspension, the Brunauer–Emmett–Teller surface areas, total pore volumes, and mean pore radii of the (100 ? x)SiO2–xPVA (x = 0, 10, 20, 30 wt%) nanocomposites were 102–313 m2 g?1, 0.61–1.42 cm3 g?1, and 8.1–14.7 nm, respectively. Some cracks were observed in the monolithic SiO2–PVA nanocomposite, affected by the pore size. To elucidate crack generation, the correlation between the dispersion/aggregation in the SiO2–PVA suspension and the pore size distribution of the nanocomposite was evaluated in terms of the added PVA amount and pH value. At x = 20 and pH 3, the SiO2 particles and PVA aggregated in the suspension. The preparation of crack-free monolithic SiO2–PVA nanocomposites was possible using the aggregated suspension owing to the low capillary force during drying because of the relatively large pores. 相似文献
355.
Y. Fujino M. Ito H. Yamaguchi 《Journal of Wind Engineering & Industrial Aerodynamics》1988,30(1-3):17-26
It has been reported that many telecommunication cables of figure-8 section suffered from operating problems and sometimes even failed because of wind-induced large-amplitude galloping oscillation. In this study three-dimensional figure-8 cable model was tested in the wind tunnel and aeroelastic behavior of the cable was observed in detail. It is found that wind-induced change in the angle of attack of the wind relative to the cable is significant and this is the fundamental cause of galloping. The critical wind speed that triggers galloping and the initial direction of the self-excited cable motion are explained by the Den Hartog's quasi-steady treatment of the aerodynamic force with some modifications. Applicability of 3-dimensional dynamic analysis with quasi-steady wind forces was also discussed. 相似文献
356.
Prediction of vehicle-induced local responses and application to a skewed girder bridge 总被引:1,自引:0,他引:1
This paper proposes an innovative and flexible simulation method that predicts the dynamic responses of bridges induced by passing vehicles. The decoupled equations of motion of the vehicle-bridge system are derived from Lagrange equations and include the effect of road surface roughness, while the interaction forces between the two systems are calculated step by step, using Newmark’s method. This algorithm does not require a special finite element (FE) code and can be implemented with standard FE software and general numerical software such as ABAQUS and MATLAB, respectively. In order to illustrate the practicability of the method, an extensive case study is then presented in which some aspects of the dynamic behaviour of a skewed bridge monitored under vehicle-induced loads are investigated. After adjustment of the boundary conditions and the spectral roughness coefficient, good agreement is obtained between the bridge vibrations predicted by the numerical model and the field measurements. The validated model is further used to analyse the distinctive dynamic effects caused by the skewness. For that purpose, a reference non-skewed bridge model is prepared according to the same design as the original skewed bridge. The obtuse corner of the skewed bridge located near the loading path is found to be a critical region where the slab-negative moments, the girder stress near the sole plate and the bearing force are significantly greater than those in the reference bridge. 相似文献
357.
Yasutaka Narazaki Vedhus Hoskere Tu A. Hoang Yozo Fujino Akito Sakurai Billie F. Spencer 《Computer-Aided Civil and Infrastructure Engineering》2020,35(5):465-482
This research investigates vision‐based automated bridge component recognition, which is critical for automating visual inspection of bridges during initial response after earthquakes. Semantic segmentation algorithms with up to 45 convolutional layers are applied to recognize bridge components from images of complex scenes. One of the challenges in such scenarios is to get the recognition results consistent with high‐level scene structure using limited amount of training data. To impose the high‐level scene consistency, this research combines 10‐class scene classification and 5‐class bridge component classification. Three approaches are investigated to combine scene classification results into bridge component classification: (a) naïve configuration, (b) parallel configuration, and (c) sequential configuration of classifiers. The proposed approaches, sequential configuration in particular, are demonstrated to be effective in recognizing bridge components in complex scenes, showing less than 1% of accuracy loss from the naïve/parallel configuration for bridge images, and less than 1% false positives for the nonbridge images. 相似文献
358.
A theoretical study on an aerodynamic control method for suppression of the wind-induced instabilities of a very long span bridge is presented in this paper. The control system consists of additional control flaps attached to the edges of the bridge deck. Their rotational movement, commanded via feedback control law, is used to modify the aerodynamic forces acting on the deck and provides aerodynamic forces on the flaps used to stabilize the bridge. A time domain formulation of self-excited and buffeting forces is obtained through the rational function approximation of the generalized Theodorsen function. The optimal configuration of the deck-flaps system is found with respect to the performance index based on stability robustness of the system. A control system with the rotational center of the flaps that is located on the edges of the deck was found to be the most effective. It is also shown that this control system can provide sufficient aerodynamic damping and satisfactory stability robustness of the system with a relatively small flap size for the considered range of wind speed. 相似文献
359.
Masanori Takemoto Shinji Sakai Kazunori Wakai Isao Sumida Tomoki Kondou Takayasu Inatomi 《亚洲传热研究》2000,29(5):412-426
The cross flow between subchannels in a BWR fuel assembly has been typically analyzed using three types of mixing models, namely, pressure difference, turbulent mixing, and void drift which are expressed by time‐averaged flow parameters. However, in our previous paper, we expressed the above cross flow phenomenon simply by a fluctuating pressure model and confirmed its validity experimentally. In this present study, we examine the relationship between the fluctuating pressure difference and the cross flow rate more precisely by using a short mixing zone with no steady pressure difference. Results show that the experimental cross flow data agree well with the calculations using this model. Furthermore, we tried to express the fluctuating pressure difference by using a sinusoidal wave as a new cross flow model. This model is shown to have no dependence on frequency. We verify that the cross flow can be analyzed using only the pressure difference amplitude. © 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 412–426, 2000 相似文献
360.
Takahiro Hasebe Ryo Sasaki Takayasu Fujino Hidemasa Takana Hiromichi Kobayashi 《Electrical Engineering in Japan》2023,216(3):e23446
Experiments on power generation were conducted under the open-circuit condition to validate theoretical analyses on the power generation characteristics of a co-axial MHD energy conversion device. Considering distribution of externally applied magnetic field and the electromotive force induced by the rotation of the conductive inner cylinder, the results show that the experimental open-circuit voltage was lower than the theoretical one for the wide channel width, whereas the experimental open-circuit voltage was higher than the theoretical one for the narrow channel width. The inclination of the inner cylinder might cause the decrease in effective radial ratio. 相似文献