复合材料构件MBD模型规范化检查系统研究及应用

随着MBD技术在航空复合材料构件设计当中的应用,三维模型成为产品几何与非几何信息的唯一载体,是生产制造过程中的主要依据。由于复合材料构件结构多样性以及设计表达的复杂性,仅靠设计人员经验不能保证三维模型的质量,需要建立全面的建模规范以及面向设计/制造的检查系统来实时指导和规范复合材料构件全三维建模。为了实现对复合材料构件MBD模型的质量控制,研究了基于检查模板的构件模型规范性检查技术,对复合材料构件建模过程进行了规范性分析,并设计了构件MBD模型规范化检查系统,保障了三维模型定义的规范性、完整性和工艺性。基于B/S和C/S混合模式进行了系统开发,将其应用到某航空制造企业复合材料构件建模过程,并以某复合材料构件三维模型的检查为例验证了系统的可行性。     

NIR在导热油定性识别中的应用研究

本文采用近红外光谱技术(NIR)区分识别矿物型和合成型两种类型的导热油,准确率100%。同时以区分识别矿物型导热油为例,对同一类型但属不同品牌的导热油进行区分识别,平均预测准确率95%。研究表明,该方法可用于定性识别不同性能的导热油。     

内燃机缸内零件系统传热的计算机模拟进展

本文综合介绍了内燃机缸内零件系统传热计算机模拟的国际和国内现状，并介绍了作者目前正在进行的缸内耦合三维零件系统传热的研究情况。由于缸内零件传热的计算机模拟是未来内燃机虚拟设计的关键技术，因而有必要对缸内零件的分析历史和现状进行综合探讨。     

一种五级自动复叠制冷系统的初步试验研究

提出了一种五级自动复叠制冷循环,根据不同的系统采用不同的制冷工质和不同的混合配比,可以获得不同的蒸发温度,分析了非共沸混合工质的组分选取原则并选取了组分,探讨了适用于自动复叠制冷系统混合工质计算的方法,根据要求选择了R22、R23、R14、R740和R728五种制冷工质作为系统循环工质,对混合工质的配比进行了模拟计算,得出了理论模拟最优配比并通过试验研究加以比较确定.     

The organization of a study of the field failure of electronic components

This paper describes the organization that has been evolved for the collection and analysis of field failure data. A summary breakdown is given of the data collection organization, the Data Format and the methodology of Data Analysis. Preliminary studies show the system is working. The concept of superpopulation has been established in order to judge the relative importance of data as it is accumulated.     

酸、甜杨桃的营养成分分析

本试验对酸、甜杨桃的营养成分进行了分析。结果表明,每100g酸杨桃中水分为91.812g,碳水化合物为8.3202g,灰分为4.2096g,粗蛋白为13.8947g,粗脂肪为2.2925g。每100g甜杨桃中水分为90.409g,碳水化合物为8.7817g,灰分为3.4163g,粗蛋白为13.8957g,粗脂肪为2.6993g。除色氨酸水解破坏未测出外,两种杨桃的必需氨基酸种类齐全,各占氨基酸总量的39.0%、40.1%,必需氨基酸指数分别为24.22、25.25;矿质元素Mg最高,Ca、K次之。     

山药的药理作用分析及其开发利用

本文综述了山药的成分及其药理作用,并对山药的开发利用前景进行了探讨。     

载人航天运载火箭用元器件可靠性保证技术研究与应用

元器件的可靠性是影响载人航天运载火箭高可靠的关键因素之一.本文针对载人航天的高可靠要求,以现实条件为基础,以载人航天为目标,进行了元器件可靠性保证技术的研究,包括:管理控制、监制验收、复验筛选等.最后总结了元器件质量保证工作的成效与经验.     

Review: Durability and Degradation Issues of PEM Fuel Cell Components

Besides cost reduction, durability is the most important issue to be solved before commercialisation of PEM Fuel Cells can be successful. For a fuel cell operating under constant load conditions, at a relative humidity close to 100% and at a temperature of maximum 75 °C, using optimal stack and flow design, the voltage degradation can be as low as 1–2 μV·h. However, the degradation rates can increase by orders of magnitude when conditions include some of the following, i.e. load cycling, start–stop cycles, low humidification or humidification cycling, temperatures of 90 °C or higher and fuel starvation. This review paper aims at assessing the degradation mechanisms of membranes, electrodes, bipolar plates and seals. By collecting long‐term experiments as well, the relative importance of these degradation mechanisms and the operating conditions become apparent.     

Local entropy generation and entropy fluxes of a transient flame during head-on quenching towards solid and hydrogen-permeable porous walls

Premixed H₂-air flames are studied in a one-dimensional wall-bounded configuration. The laminar flame propagates towards and quenches at a wall that is either solid or permeable. Entropy generation by each of 19 elementary reactions is evaluated. Their total contribution remains the most important up to the quenching instance. Close to quenching, the conduction entropy generation grows considerable. Mass diffusion has a modest contribution, which decreases towards quenching. Viscous forces are negligible as a source of entropy. Effects of unburnt-mixture temperature and fuel-air ratio are investigated, and also dilution with nitrogen (inert) and water vapour. The diffusive entropy flux changed direction away from the permeating wall compared that of the solid wall. A major finding is that fuel permeation through the wall tends to decrease the entropy generation per unit of converted fuel, in particular for initially lean mixtures.