Finite Element Analysis of a Moving Boundary Value Problem

A finite element formulation and the solution of a set of nonlinear coupled heat and mass transfer equations for a two-phase system with a moving evaporation interface is presented. The interface condition takes into account the moisture transfer balance at the moving boundary. The finite element results were compared with existing results for a single phase system for model validation. In the two-phase system, the movement of evaporation front has an appreciable effect on the temperature and moisture distribution inside the porous medium during drying. The effect of the nondimensional heat of vapourization parameter γ on the evaporation front, temperature and moisture distribution in porous medium was studied. The higher the value of γ, the slower is the movement of the evaporation front. The temperature decreased and the moisture content increased as the nondimensional vapourization parameter γ increased. This model has potential applications in studying the heat and mass transfer characteristics in food and biomaterials.     

Analysis of polarization plane rotation characteristic in 2D photonic crystal waveguide with chiral medium by condensed node spatial network

Using the photonic band gap in photonic crystals, the fundamental waveguide structures for the light wavelength range have been developed. Based on the fine structure of these many functional devices have been proposed by analytical or numerical simulation methods and the experiments of trial manufacture. In this paper, the treatment of chiral dielectric in the Condensed Node Spatial Network for the vector potential is explained, and we show the polarization plane rotation property in air‐hole and pillar type photonic crystal waveguide structures with the chiral medium substrate. Then, we show the fundamental advantage of the air‐hole type photonic crystal waveguide structure in application to a mode converter. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(1): 7–14, 2005; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20098     

Analysis of junction temperatures in high-power GaN-based LEDs

We presented the analysis of the incomplete conduction in bonding medium in high power GaN-based light-emitting diode (LED) packages. A numerical study was carried out with parametric model to understand the junction temperature variation due to bonding medium defects. Transient thermal measurement was performed to evaluate LED’s junction temperature. Thermal resistance from chip to lead frame was 20 K/W in our sample LED. It was suggested that only 60% of the surface area of the bonding medium was involved...     

FEM analyses for influences of stress corrosion and pressure solution on THM coupling in dual-porosity rock mass

With the models of stress corrosion and pressure solution, by Yasuhara et al., two computation conditions were designed for a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass: (i) the fracture apertures are changed with the stress corrosion and pressure solution (the porosity of rock matrix is also a function of stress); (ii) the fracture apertures and the porosity of rock matrix are constants. Then the corresponding two-dimensional FEM analyses for the coupled thermohydro-mec...     

高速锯床防护罩抗冲击能力的有限元分析

利用ANSYS/LS_DYNA的动力学分析功能对GS3050型超高速数控锯床安全防护罩的抗冲击能力进行了数值分析,对刀具碎片侵彻有机玻璃的过程进行了数值模拟.结果表明,采用厚度为15 mm的改性丙烯酸脂有机玻璃作为GS3050锯床的安全防护罩是可靠的.数值分析和试验的结果吻合.     

Automation, work organization and skills: The case of numerical control

This paper deals with small and medium sized firms. Since the late seventies small and medium sized mechanical engineering firms in France have resorted increasingly to new technologies, and in particular to numerical control. Numerical control has introduced major changes in work organization. On the one hand it tends to reinforce the role of methods of production engineering whatever the type of numerical control may be. Programming is seldom left to the machine operators, except in the case of straightforward machining operations or in machining shops with a strong tradition of highly skilled or artisan labour. Numerical control, on the other hand, does provide more opportunity for collaboration between the workshop and the production engineers. On a workshop level it introduces a more mobile division of labour between programmers, machine setters and operators, which covers everything from the start-up of programs to the supervision of maching operations. The operator may therefore acquire new skills, but this is only possible if there are open-ended training systems available to facilitate the transmission of know-how from the programmers to the machine setters and from the machine setters to the operators, and vice versa. Small and medium sized firms would appear to have a special role to play in developing skills.     

Modeling radiative properties of nanoscale patterned wafers

Temperature nonuniformity in rapid thermal processing of wafers is a critical problem facing the semiconductor industry. One cause of the problem is the nonuniform absorption of thermal radiation in patterned wafers where the optical properties vary across the wafer surface. This paper presents a parametric study of the radiative properties of patterned wafers, considering the effect of temperature, wavelength, and polarization. The finite-difference time-domain (FDTD) method is employed to examine the effe...     

电网规划中常规中长期负荷预测方法的探讨

电力负荷的不断增长是电网发展的根据,正确地预测电力负荷,既是为了保证国民经济发展及人民生活对电力的需求,也是电网自身发展的需求。电力负荷预测工作是电网规划工作的重要组成部分,也是电网规划的基础工作。在掌握铜陵地区经济、电网历史实绩的前提下,探讨了在电网规划中运用中长期常规负荷预测的几种方法,得出铜陵地区中长期负荷预测结果,以便为铜陵地区电网发展提供与此相适应的负荷保证。     

激光淬火与中频感应淬火对比研究

利用摩擦磨损实验机对45CrNi钢开展了激光淬火和中频感应淬火摩擦磨损对比实验研究，并利用扫描电镜(SEM)、投射电镜(TEM)和X射线衍射仪(XRD)等设备对两种淬火试样硬化层进行了微观分析。结果表明，在载荷50～250 N条件下，激光淬火试样的耐磨性比中频感应淬火试样提高了4%～21%;中频感应淬火试样的摩擦系数略大于激光淬火试样的摩擦系数。两者的主要磨损形式均为磨粒磨损，但中频感应淬火试样磨损后表面犁沟的深度和宽度大于激光淬火试样表面犁沟的深度和宽度。两种淬火方法淬硬层均为板条马氏体和少量针状马氏体的混合组织，但中频感应淬火淬硬层有大量的碳化物析出，碳化物含量多且碳化物颗粒大、残余奥氏体多。     

太湖流域不同种浮萍淀粉积累的研究

对在太湖采集的15株浮萍进行分子鉴定,从中筛选出3株高淀粉含量浮萍作为供试材料,对其生长培养基进行优化,并研究饥饿条件对其生长和淀粉积累的影响。结果表明:采集到的浮萍分布于5个种,分别为Lemna aequinoctialis,Lemna minor,Lemna turionfera,Spirodela polyrhiza,Landoltia punctata;与SH培养基相比,改良的培养基SH-1和SH-2均能显著促进浮萍的生长;在饥饿试验中,筛选的3种浮萍S.polyrhizza,L.aequinoctialis和L.punctata每周的生长速率(以鲜重计)分别为18.64,20.77和16.52g/m2,饥饿培养33 d后,淀粉含量分别达到20.6%,21.98%和24.30%,较饥饿前分别增加了73.4%,75.4%和137.5%。相较于S.polyrhiza和L.aequinoctialis,L.punctata在淀粉积累方面表现出一定的优势。