Integrated design technique for materials and structures of vehicle body under crash safety considerations

With the rapid development of the vehicle industry, crashworthiness has become a crucial aspect in vehicle body design. In fact, crashworthiness is a multivariable optimization design problem for a vehicle body, regardless of structure or material. However, when crashworthiness involves a large number of design variables, including both material and structure variables, it is more difficult to deal with. In this paper, an integrated design technique for materials and structures of vehicle body under crash safety consideration is suggested. First, a finite element model of the vehicle body is established according to relevant vehicle safety standards. Then, the material parameters of the vehicle body are set as analytical factors for factor screening. Next, significant factors are obtained using a three-level saturated design integrated with multi-index comprehensive balance analysis and the MaxUr ⁽³⁾ method, with an improved evaluation method. These screened material parameters along with the corresponding continuous variables of the structure, are considered as the design variables of the integrated design of the vehicle body. Both the weight and the crashworthiness properties are set as the design objectives. Optimal Latin hypercube sampling and radius basis functions are utilized to construct highly accurate surrogate models. Furthermore, the non-dominated sorting genetic algorithm II is implemented to seek the optimal solutions. Finally, two cases considering the roof module and the frontal module of a vehicle body are analyzed to verify the proposed method.     

Error Estimates for Semidiscrete Finite Element Approximations of the Stokes Equations Under Minimal Regularity Assumptions

Semidiscrete (spatially discrete) finite element approximations of the Stokes equations are studied in this paper. Properties of L ², H ¹ and H ^–1 projections onto discretely divergence-free spaces are discussed and error estimates are derived under minimal regularity assumptions on the solution.     

工程总承包公司的合同管理研究

山东鲁能工程有限责任公司开展电力工程总承包始于上世纪九十年代中期,近五年来总承包事业发展迅速,公司陆续签订了嘉峪关宏晟2×300M W电厂、重庆永川2×125M W电厂、费县2×600M W电厂脱硫、章丘2×300M W电厂脱硫、潍坊2×25M W电厂、单县1×25M W生物发电厂等一批总承包合同,均采用了国际上通行的FID IC合同条款。为规范公司的经营管理,防范合同风险,维护公司合法权益,我们研究摸索了一套适应矩阵管理的总承包公司合同管理体系,在此做简要介绍,与同行交流。一、合同管理中常见问题合同是市场经济下确定不同主体之间经济关系的重…     

Observation and computer simulation of multicomponent chemical short-range order （MCSRO） for the bulk metallic glasses

The atomic configuration of chemical short-range order (CSRO) for the Zr-base metallic glasses was investigated by using nano-diffraction and high resolution transmission electronic microscopy (HRTEM) technology with a beam size of 0.5 rim. It is illustrated that the pattern of atomic configuration of CSRO might have various compound counterparts because of the chemical interaction of bonding atoms. Some atomic configuration of MCSRO is similar to the icosahedral structure with 10-fold symmetry of very weak spots. In deed, the nano-beam technology could clearly detect the evolution of atomic configuration in nanometer scale during the transformation from the metallic melt to the primary crystallization. The local atomic configuration of CSRO is also investigated by molecular dynamics simulation (MD) for the Zr2Ni compound in a wider temperature range. The CSRO in the melt could be pictorially demonstrated as distorted coordination polyhedron of the compound structure and/or the structure similar to cubo-octahedron analogs. The MD simulation illustrates that the atomic packing of long-range order disappears just above the melting point, but the chemical interaction of bonding atoms still exists that leads to form the various CSRO with the atomic configuration similar to stable or metastable unit cell of Zr2Ni compound. The icosahedral polyhedron became more abundance as the overheating temperature was raised.     

Ipv6高级套接口的研究和实现

IPv6的高级套接口规范还在定义之中,不断地增加新的功能。该文根据IPv6接入路由器的实现经验,提供给大家新一代网络层协议IPv6高级套接口主要功能的实现机制和应用示例。通过对实现机制的分析,文章给出了新增高级套接口功能的实现参考。     

基于电话网络的矿山综合监控系统设计

本文根据矿山综合监控系统的功能要求，提出了监控系统的总体设计、系统配置方案及软硬件技术特点和功能等。该系统在矿山中的应用提高了矿山管理的现代化水平。     

基于以太网的工业控制远程访问的研究

NAT是一项专门用于网络互联的技术，可以用来解决工业控制网络的互联及远程访问的问题。探讨了利用NAT技术实现基于以太网的远程访问的实现，并给出了具体的实例。     

汽车照明防眩的新技术

文章介绍了一种新颖的汽车照明防眩技术，这是汽车前照灯的脉冲化照明所带来全新功能之一。通过利用高速频闪的脉冲氙灯，配合高速液晶电光开关制成的挡光板，让对方照明效果光透过，而挡去大部进入眼睛的外部眩光，从而达到防止眩光的目的。本文详细论述了这种新颖的防眩控制技术，并给出了在实用中多车交会时的处理方法。     

Advances in selective wet oxidation of AlGaAs alloys

We review the chemistry, microstructure, and processing of buried oxides converted from AlGaAs layers using wet oxidation. Hydrogen is shown to have a central role in the oxidation reaction as the oxidizing agent and to reduce the intermediate predict As₂O₃ to As. The stable oxide is amorphous (Al_xGa_1-x) ₂O₃ which has no defects along the oxide/semiconductor interfaces but can exhibit strain at the oxide terminus due to volume shrinkage. The influence of gas flow, gas composition, temperature, Al-content, and layer thickness on the oxidation rate are characterized to establish a reproducible process. Linear oxidation rates with Arrhenius activation energies which strongly depend upon AlAs mole fraction are found. The latter produces strong oxidation selectivity between AlGaAs layers with slightly differing Al-content. Oxidation selectivity to thickness is also shown for layer thickness <60 nm. Differences between the properties of buried oxides converted from AlGaAs and AlAs layers and the impact on selectively oxidized vertical cavity laser lifetime are reported     

一点对多点通讯在卫星测试无线转发系统中的应用

分析了卫星测试无线转发中一点对多点通讯系统中的关键性技术：包括硬件连接、通讯方式及有关技术，并给出了具体方案。