Fabrication of the slanted electrode matrix on tilting 4.5° (1 1 1) silicon

The slanted low electrode matrix is designed and fabricated on one tilting 4.5° (1 1 1) silicon wafer to reduce the actuating voltage of 8×8 micro-electromechanical systems (MEMS) optical switch matrix. Due to compact size of the upper electrode chip and (1 1 1) silicon anisotropic etching in KOH solution, photomask is designed which is to fabricate the slanted low electrode matrix that can be matched with the upper electrode chip and every slanted low electrode has enough space for actuating cantilever. The experimental results show that all of the applied voltages for the full range of actuating micromirrors of 8×8 MEMS optical switch matrix are in the range of 67.2±0.5 V. It is demonstrated that the fabricated slanted low electrode matrix has good consistency and every slanted low electrode can be precisely aligned with one-to-one corresponding upper electrodes.     

Study of transient photoconductivity of GaN epilayer grown by metalorganic chemical vapor deposition

Received: 24 March 1998/Accepted: 10 July 1998     

A new arc algorithm for unconstrained optimization

The gradient path of a real valued differentiable function is given by the solution of a system of differential equations. For a quadratic function the above equations are linear, resulting in a closed form solution. A quasi-Newton type algorithm for minimizing ann-dimensional differentiable function is presented. Each stage of the algorithm consists of a search along an arc corresponding to some local quadratic approximation of the function being minimized. The algorithm uses a matrix approximating the Hessian in order to represent the arc. This matrix is updated each stage and is stored in its Cholesky product form. This simplifies the representation of the arc and the updating process. Quadratic termination properties of the algorithm are discussed as well as its global convergence for a general continuously differentiable function. Numerical experiments indicating the efficiency of the algorithm are presented.     

Using CEMS method to study Sb-doped SnO2 thin film as reducing gas sensing material

¹¹⁹Sn Mossbauer spectra for surface layers of thin film Sb doped SnO were obtained by CEMS method, the emissive internal conversion electrons were detected by multi-wire chamber. In practice the gas-sensing response of these films for H₂, CO depended on Sb concentration of doping (X%) and the annealling processes. It was found that the CEMS parameters of samples-(IS), (QS) and its distribution (HW), reach minima when x=1%, just in agreement with the gas-sensing responsive sensitivity reaching maximum. And then it is helpful for the study of the gas-sensitive mechanism.     

Numerical experiments on stability and transition in plane channel flow

Various secondary and tertiary instabilities in plane channel flow are explored via time-dependent numerical simulations using the incompressible Navier-Stokes equations. Comparisons are made between transitional flows at Reynolds numbers 1500, 5000, and 8000. The lambda vortex, detached shear layer, and inverted vortex regions are identified and the origin of the latter is explained. The laminar breakdown of the Re=1500 flow is computed with high resolution and the nature of its ensuing hairpin eddies is clarified by numerical particle paths. The potential of center-mode rather than wall-mode transitions is proposed and the resulting flow structure is described.     

Measurement of dynamic properties of dilute polymer solutions with a Laser-Doppler velocimeter

The complex velocity field of an oscillating Couette flow is measured with a Laser-Doppler velocimeter. Different evaluation methods are used for the determination of material functions such as relaxation times and the dynamic complex viscosity.     

气垫船稳态船波势及波阻的边界元法

本文给出了气垫船在静水中航行时稳态船波势问题的边界元数值分析方法，根据本文的数值计算方法，可以得到气垫船行时所兴起的波浪形状以及气垫附近流场情况，由此可计算气垫所受到的兴波阻力，本文的方法适用于任意已知气压分布情况。     

Protection of mitochondrial integrity from oxidative stress by selenium-containing glutathione transferase

The antioxidant activity of a novel artificial glutathione peroxidase-like enzyme, selenium-containing glutathione 5-transferase from Lucilia cuprina (seleno-LuGST1-1), was studied by using a ferrous sulfate/ascorbate-induced mitochondrial damage model system. Swelling of mitochondria, lipid peroxidation, and cytochrome-c oxidase activity were selected to evaluate the preservation of mitochondrial integrity in this system. Seleno-LuGST1-1 could effectively protect the mitochondria against oxidative damage in a dose-dependent manner and exhibited both higher catalytic activity and greater antioxidant ability than the classic mimic, 2-phenyl-1,2-benziososelenazol-3(2H)-one (Ebselen). This novel artificial biocatalyst therefore may have great protential for pharmacologic application in the treatment of reactive oxygen species-related diseases.     

再循环重力供液蒸发器管内换热性能预测

为了找出适用于再循环重力供液蒸发器管内强制对流沸腾换热系数的关系式,通过对以R404A为制冷剂的重力供液实验台的研究,编程计算出J.Chawla关系式及Shah关联式对重力供液沸腾换热系数进行预测值。与实验结果比较可知:J.Chawla关系式在较低温度下较接近于实验值,Shah关联式在较高的温度下可以对实验值进行预测,两种关系式相结合的方法就可以较好对重力供液蒸发器管内沸腾换热进行预测。