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91.
Yukimitsu Okano Tamio Kohriyama Yoshitaka Yoshida Michio Murase 《Nuclear Engineering and Design》2003,223(2):145-158
For severe accident assessment in a light water reactor, heat transfer models in a narrow annular gap between the overheated core debris and the reactor pressure vessel (RPV) are important for evaluating RPV integrity and emergency procedures. Using existing data, the authors developed heat transfer models on the average critical heat flux (CHF) restricted by countercurrent flow limitation (CCFL) and local boiling heat fluxes, and showed that the average CHF depended on the steam–water flow pattern in the narrow gap and that the local heat fluxes were similar to the pool boiling curve. We evaluated the validity of heat transfer models by simple calculations for ALPHA experiments performed at Japan Atomic Energy Research Institute. Calculated results showed that heat fluxes on the crust surface were restricted mainly by thermal resistance of the crust after the crust formation, and emissivity on the crust surface did not have much effect on the heat fluxes. The calculated vessel temperature during the heat-up process and peak vessel temperature agreed well with the measurements, which confirmed the validity of the average CHF correlation. However, the vessel cooling rate was underestimated mainly due to underestimation of the gap size. 相似文献
92.
Balance between genetic search and local search in memetic algorithms for multiobjective permutation flowshop scheduling 总被引:9,自引:0,他引:9
This paper shows how the performance of evolutionary multiobjective optimization (EMO) algorithms can be improved by hybridization with local search. The main positive effect of the hybridization is the improvement in the convergence speed to the Pareto front. On the other hand, the main negative effect is the increase in the computation time per generation. Thus, the number of generations is decreased when the available computation time is limited. As a result, the global search ability of EMO algorithms is not fully utilized. These positive and negative effects are examined by computational experiments on multiobjective permutation flowshop scheduling problems. Results of our computational experiments clearly show the importance of striking a balance between genetic search and local search. In this paper, we first modify our former multiobjective genetic local search (MOGLS) algorithm by choosing only good individuals as initial solutions for local search and assigning an appropriate local search direction to each initial solution. Next, we demonstrate the importance of striking a balance between genetic search and local search through computational experiments. Then we compare the modified MOGLS with recently developed EMO algorithms: the strength Pareto evolutionary algorithm and revised nondominated sorting genetic algorithm. Finally, we demonstrate that a local search can be easily combined with those EMO algorithms for designing multiobjective memetic algorithms. 相似文献
93.
Ceramic matrix composites (CMC) were prepared by the active-filler-controlled polymer pyrolysis, using a siloxane polycyclic network filled with CrSi2. The starting CrSi2-filled polysiloxane was pyrolyzed in both nitrogen and argon atmospheres, up to 1450°C. During the pyrolysis in nitrogen atmosphere, the CrSi2 particles reacted with N2, and also with carbon from the preceramic polymer binder, still complete consumption of the filler particles. Such reactions led to a dramatic change in the composition and microstructure of the resulting ceramic monoliths, which displayed linear expansion of 1.7%. In argon atmosphere, the CrSi2 particles acted as inert filler during the pyrolysis process. The final CMC compositions obtained in N2 and Ar atmospheres were Cr0.62C0.25N0.03-Si3N4-Cr3C2 and SiOxCy-SiC-CrSi2, respectively. 相似文献
94.
Hisashi Abe Isao Yoshida Hiroki Hamada Derek Luke Yongbao Xin Yue Xu Rong Yang Eiric Johnstone Joe Acchione Paul Balmforth 《Journal of the Society for Information Display》2004,12(3):275-280
Abstract— Defect‐free large‐area inorganic thick‐dielectric EL (TDEL) displays using Color by Blue (CBB) technology have been successfully developed. We have achieved the world's highest blue‐phosphor luminance of 900 cd/m2 for a single‐pixel device by using CBB and by optimizing the e‐beam gun configuration and the flow rate of H2S in the vacuum chamber. By analyzing the defects on panels with triple‐pattern phosphors and CBB panels, we also found that the number of defects on CBB panels can be drastically reduced compared with those on triple‐pattern panels. The defect‐free 17‐in. VGA CBB panels show better characteristics, a high peak luminance of 600 cd/m2 and a high contrast ratio of 1000:1, compared with those of triple‐pattern panels. 相似文献
95.
Ohta Y Yano H Suzuki R Yoshida M Kawashima N Nakazawa K 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2007,221(6):629-639
A number of orthoses have been developed to restore stance and walking in paraplegic subjects. Compliance, however, has been limited, mainly owing to walking effort. Use of the forces produced by actuators is an effective way to solve the problem of the considerable effort required for orthotic gait, namely high muscular effort and high energy expenditure. The purpose of the present study was to investigate the effects of assistance by external actuators on the orthotic gait of spinal cord injury (SCI) patients. Two kinds of linear actuator were developed by using direct current (d.c.) motors for assisting the knee and hip joint of a gait orthosis. They were mounted on the knee and hip joint of a commercial advanced reciprocating gait orthosis (ARGO), and a new two-degree-of-freedom externally powered gait orthosis was thus developed. The orthosis was assessed through inter-subject experiments on five male adult complete SCI patients. Owing to the short training period available for the assisted gait, simultaneous operation of both joint actuators was not conducted: either the knee actuation or the hip actuation was executed only. Thus, the knee actuator and the hip actuator were assessed with a T12 subject and with subjects for T5, T8, T11, and T12 respectively. The motions of the gaits, assisted by the linear actuators, were measured by a Vicon 370 system, and the general gait parameters and compensatory motions were evaluated. Results demonstrated that (a) all subjects could walk without falling, assisted either by the knee or the hip actuator; (b) both the knee and hip joint actuator increased the gait speed and the step length; (c) the knee flexion produced by the orthosis improved the dynamic cosmesis of walking; and (d) lateral compensatory motions as well as vertical ones tended to decrease when the hip joint was assisted, which could contribute to a reduction in walking effort. 相似文献
96.
Measurements of the residual stress and observations of the microstructure at the surface and in the subsurface of rollers were performed during rolling contact fatigue tests of annealed 0.45% carbon steel and case-hardened nickel-chromium steel rollers. Compressive residual stresses in annealed rollers were induced by the rolling contact. With case-hardened rollers they were induced by heat treatment prior to the rolling contact fatigue tests. After the rolling contact fatigue tests the compressive residual stresses on the surface of the annealed rollers and in the subsurface of the case-hardened rollers relaxed; a characteristic substructure was formed by the stress cycles, which caused surface failure. It was confirmed that the microcracks leading to surface failure initiate on the surfaces of annealed rollers and in the subsurface of case-hardened rollers. 相似文献
97.
Recent analyses of tears indicate the presence of glycosaminoglycans as their components, but their origin remains unknown. To further understand the origin of these tear components, we investigated by immunohistochemical techniques the localization of glycosaminoglycans and CD44 human lacrimal glands obtained from 20 cadavers at autopsy. Monoclonal antibodies to CD44, a receptor for hyaluronic acid, dermatan sulfate, chondroitin sulfate, and keratan sulfate were applied to the tissue. Hyaluronic acid binding region was also used for the staining of hyaluronic acid. By light microscopy, immunoreactivity for CD44 was mostly detected on the baso-lateral membrane of acinar and ductal cells, and the vascular endothelium in the interstitium. Positive staining of hyaluronic acid was associated intensely with the basal membrane of acinar and ductal cells and weakly, faintly or not at all with their lateral membrane. Positive staining of hyaluronic acid and immunoreactivity for dermatan sulfate were detected in interstitial fibrous structures; particularly, the former was intense in the perivascular fibrous structures, and the latter along the periparenchimal fibrous structures. Immunoreactivity for chondroitin sulfate and keratan sulfate was seen in some acinar cells and the acinar and ductal lumen. By electron microscopy, immunogold particles indication chondroitin sulfate sulfate or keratan sulfate labeled secretory granules of the acinar cells. Considering the fact that CD44 is a receptor molecule for hyaluronic acid, the association of hyaluronic acid with the basal membrane and weakly or faintly with the lateral membrane of acinar and ductal cells may be attributed to the expression of CD44 on the baso-lateral membrane of the cells. Moreover, the presence of immunoreactivity for chondroitin sulfate and keratan sulfate in secretory granules of acinar cells and their lumens suggests that tears from the lacrimal gland contain these glycosaminoglycans. 相似文献
98.
S.K. Sharma H. Zushi I. Takagi Y. Hisano T. Shikama S. Morita T. Tanabe N. Yoshida M. Sakamoto Y. Higashizono K. Hanada M. Hasegawa K. Nakamura H. Idei K.N. Sato S. Kawasaki H. Nakashima A. Higashijima Y. Takase 《Journal of Nuclear Materials》2012,420(1-3):83-93
In order to investigate the overall atomic hydrogen background and the dynamic characteristics of wall pumping/fuelling phenomenon, a permeation probe system has been developed and applied in the spherical tokamak QUEST. Reliability of measurements, within ±3% accuracy and a positive correlation with the hydrogen line emission over three orders of magnitude have been demonstrated for more than 3000 various plasma discharges. By comparison of the experimental permeation (flux) curves with the numerically simulated curves, the net incident atomic hydrogen flux is evaluated in the range of 1 × 1019 H m?2 s?1 to 4 × 1020 H m?2 s?1. The atomic flux has been investigated as a function of various plasma operation parameters like RF power, gas pressure and magnetic configuration. Using the static particle balance and permeation measurements, the progress in wall conditioning has been investigated. An inverse correlation between the atomic hydrogen flux and improvement in wall pumping has been observed over the two campaigns. 相似文献
99.
Lawanwong Komgrit Hamasaki Hiroshi Hino Ryutaro Yoshida Fusahito 《The International Journal of Advanced Manufacturing Technology》2020,106(5):1855-1867
The International Journal of Advanced Manufacturing Technology - This paper presents a novel technology called ‘double-action bending (DAB)’ to eliminate springback in hat-shape forming... 相似文献
100.
Kakimoto S. Nakajima Y. Sakakibara Y. Watanabe H. Takemoto A. Yoshida N. 《Quantum Electronics, IEEE Journal of》1990,26(9):1460-1466
The low threshold current of 9 mA, the high side-mode suppression ratio of more than 45 dB, the extremely narrow spectral linewidth of 1.1 MHz, and the low chirping of 2.8 Å at -20 dB at 2 Gb/s nonreturn to zero (NRZ) modulation have been achieved in the multiple quantum well (MQW) distributed feedback (DFB) p-substrate partially inverted buried heterostructure (PPIBH) laser diode. The spectral linewidth of 1.1 MHz is the narrowest value among 300-μm-length solitary laser diodes. These results suggest that the MQW-DFB laser diodes are a promising light source for longer distance and higher bit-rate optical communication systems and coherent optical communication systems 相似文献