光电化学响应分析Ni201在中性溶液中形成表面钝化膜的半导体性质

应用光电化学响应法和:Mott-Schottky曲线法,研究了Ni201在500℃空气中生成的氧化膜和在pH值为8.4的中性缓冲溶液中阳极氧化生成钝化膜的半导体性质,分析了Ni201表面钝化膜的结构和组成.Mott-Schottky曲线表明,Ni20l在该中性溶液中生成钝化膜的平带电位约为0.40 V,其在500℃空气中生成的氧化膜的平带电位约为0.15 V,前者的载流子浓度约是后者的34倍.在中性缓冲溶液中生成钝化膜的光电流谱表明,Ni201的结构由内层NiO和外层Ni（OH）₂构成,其带隙宽度分别为2.8和1.6 eV.其中,具有晶体结构的内层NiO的带隙宽度与Ni201在500℃空气中生成的氧化膜的带隙宽度2.4 eV相似.通过光电化学法和Mott-Schottky曲线建立Ni201表面钝化膜的电子能带结构模型,解释了其内层NiO和外层Ni（OH）₂同是p型半导体组成的钝化膜的半导体性质.     

ZL201合金半固态成形本构模型

对采用近液相线铸造法制备的ZL201合金半固态坯料进行了热模拟压缩试验。根据试验获得的ZL201合金不同温度与应变速率下的应力-应变曲线,采用多元回归线性方法建立了能够表征ZL201合金半固态变形行为的本构方程。同时,根据半固态浆料的表观粘度与热模拟压缩试验中的应变速率等参数间的关系式,对表观粘度和剪切速率之间的关系进行了研究。利用仿真软件Anycasting对ZL201合金半固态触变压铸成形过程进行了数值模拟,研究了内浇道厚度对ZL201合金半固态触变压铸过程的影响,并预测了铸件缺陷。结果表明,当内浇道厚度为3mm时,半固态金属浆料充型过程最为理想。     

ZL201铝合金底板铸造工艺和性能研究

在普通红砂湿型、手工造型条件下,确定了合理的铸造工艺方案,铸造出合格的ZL201铝合金底板铸件。铸件实现均衡凝固,避免了气孔和疏松的产生。测试了铸件的力学性能并进行了金相组织观察,铸件的力学性能Rm=250 N/mm2、A=4%,满足使用要求。     

Reliability analysis of solar photovoltaic system using hourly mean solar radiation data

This paper presents the hourly mean solar radiation and standard deviation as inputs to simulate the solar radiation over a year. Monte Carlo simulation (MCS) technique is applied and MATLAB program is developed for reliability analysis of small isolated power system using solar photovoltaic (SPV). This paper is distributed in two parts. Firstly various solar radiation prediction methods along with hourly mean solar radiation (HMSR) method are compared. The comparison is carried on the basis of predicted electrical power generation with actual power generated by SPV system. Estimation of solar photovoltaic power using HMSR method is close to the actual power generated by SPV system. The deviation in monsoon months is due to the cloud cover. In later part of the paper various reliability indices are obtained by HMSR method using MCS technique. Load model used is IEEE-RTS. Reliability indices, additional load hours (ALH) and additional power (AP) reduces exponentially with increase in load indicates that a SPV source will offset maximum fuel when all of its generated energy is utilized. Fuel saving calculation is also investigated. Case studies are presented for Sagardeep Island in West Bengal state of India.     

基于IRMCK201的永磁同步电动机的矢量控制系统的设计

永磁同步电动机(PMSM)采用矢量控制策略后,就能像直流电动机调速控制系统一样引入双环、三环控制,从而大大提高了交流电动机的速度、位置控制性能.国际整流器件公司针对由永磁同步电动机的矢量控制系统实现高性能交流伺服驱动需求,设计出基于硬件实现的完整的伺服驱动控制芯片IRM-CK201.     

Gestalten von Eisenbahnbrücken

Design of railway bridges. Railway bridges are high performance structures concerning their load bearing capacity, durability and serviceability. But high demands of usage and loading combined with the special conditions of building technology under continuing traffic led to a lack of aesthetic bridge design during the last decades. The structures of infrastructure, and in particular bridges, are large and tend to dominate their natural or urban environments. Bridges must, therefore, meet high levels of aesthetic and design value in addition to meeting the basic requirements of providing safety, functionality and economic solutions. Two years ago an advisory board for bridge design was established to support the Deutsche Bahn in making considerable improvements to the aesthetic and design quality of bridges promoting innovation in bridge design and construction.     

Nonlinear Iterative Nodal Method Applied to Neutron Flux Modal Analysis

The CCCMA (Correction Coupling Coefficient Modal Analysis) method has been proposed to improve the spatial resolution of the neutron flux modal analysis. The improvement has been achieved by including the higher order intra-nodal information through the NLM (Nonlinear Iterative Method)-correction coupling coefficient. The new code system, ENTRÉE/ACCORD-N, has been developed in which both the polynomial and semi-analytical Legendre flux expansion functions have been implemented. The application to the two-dimensional homogeneous and heterogeneous cores that were created from the stability test point, in Ringhals Unit 1 was demonstrated. The neutral line angle, eigenvalue and power shape obtained by the CCCMA were compared with those by the FDMA (Finite Difference Modal Analysis) of various mesh sizes. The CCCMA was shown to improve the solution accuracy significantly in the heterogeneous core. The ratios of the NLM-correction to FDM. (Finite Difference Method) coupling coefficients in the fuel region gave a quantitative explanation of these trends. For the 1st azimuthal mode which is important in the regional instability analysis, the CCCMA produced almost the same level of accuracy as that of the (4 × 4) FDMA solution without any additional computational cost. The methodology has been also extended to include the discontinuity factor.     

Analytical Study on Detailed Void Distributions Inside BWR Fuel Bundle under Turbine Trip Event Considering Time-Dependent Pin Power Distributions

A one-way coupling system between the plant simulator TRAC/BF1-ENTRÉE and the subchannel code with the improved cross flow model, NASCA, has been developed. Based on a scenario of turbine trip tests in the Peach Bottom Unit 2, the wide and rapid reactivity insertion transient induced by the system pressure rise was calculated. The pin power distribution in hot bundles was re-constructed considering heterogeneity of the fuel bundle. When the neighboring control blade is withdrawn, NASCA predicted that the steady-state bundle exit void distribution was nearly flat with regardless of the pin power distribution. However, void distributions in the middle and lower bundle regions became complicated depending on the pin power and the two-phase flow regime in each subchannel. The pin power distribution rapidly changed according to traveling of control blades. However, influence in the void distribution was delayed and damped due to the fuel heat conduction. The detailed void distribution under transient events has an impact on the location of dryout. It has been shown that the coupling calculation including the subchannel code is useful in understanding transition of the detailed void distribution depending on the pin power and the two-phase flow regime.     

Flow boiling of non-azeotropic mixture R32/R1234ze(E) in horizontal microfin tubes

Flow boiling of a potential refrigerant R32/R1234ze(E) in a horizontal microfin tube of 5.21 mm inner diameter is experimentally investigated. The heat transfer coefficient (HTC) and pressure drop are measured at a saturation temperature of 10 °C, heat fluxes of 10 and 15 kW m^?2, and mass velocities from 150 to 400 kg m^?2 s^?1. The HTC of R1234ze(E) is lower than that of R32. Degradation in the HTC of the R32/R1234ze(E) mixture is significant; the HTC is even lower than that of R1234ze(E). The HTC is minimized at the composition 0.2/0.8 by mass, where the temperature glide and the mass fraction distribution are maximized. A predicting correlation based on Momoki et al. (1995) associated with the correction methods of Thome (1981) to consider the mass transfer resistance and Stephan (1992) to consider the additionally required sensible heat is proposed and validated with the experimental results.