MEEP清灰钢刷失效分析与试验装置设计

移动电极电除尘器（MEEP）具有出口粉尘排放浓度低、可有效收集PM2.5等优点,其运动部件的可靠性越发受到国内外制造厂家的重视,清灰钢刷作为其关键部件之一,其国产化后的寿命和失效形式的研究越来越重要。分析了钢刷结构失效形式,并在综述了国外移动电极电除尘器钢碡4的研究经验的基础上,设计了钢刷失效形式和寿命测试试验装置。为提高钢刷寿命和降低移动电极电除尘器出口粉尘排放浓度提供了试验数据,推动了移动电极电除尘器关键的运动部件的研究进程,为移动电极电除尘器钢刷的改进和现有设备间距时间调整提供参考。     

基于可靠性仿真分析的一体化设计研究

可靠性仿真分析通过施加温度、振动等载荷应力在产品的数字样机上,并分解到基本组件上,通过开展应力分析和应力损伤分析,得到产品的薄弱环节,并据此进行改进设计,以提高产品可靠性水平,并可预计出平均首发故障时间。讨论了如何利用可靠性仿真分析方法进行可靠性优化设计,克服了传统的"设计"与"可靠性"两张皮的现状,实现了可靠性与性能的一体化设计。     

聚焦离子束加工技术在元器件可靠性领域中的应用研究

FIB技术通过截面加工实现部分失效样品的原位观察,通过截面加工获得的图像获取相关信息;能够进行TEM制样,是材料微分析领域中不可缺少的分析技术;能够进行纳米器件加工,是微加工领域的一种新型技术。FIB技术可操作性强、样品损伤小,对航天型号元器件可靠性质量保证技术具有一定的指导意义。     

Effect of PCM on temperature fluctuation during the door opening of a household refrigerator

Temperature fluctuation inside the cabinet of a household refrigerator significantly affects the quality of preserved food. Phase change material (PCM) is a latent heat storage system that can store and release the heat energy by changing its phase from liquid to solid and solid to liquid respectively. Therefore, use of PCM inside the refrigerator cabinet has the potential for minimizing the temperature fluctuation during the door opening and the power failure. However, very few studies in the literature were dedicated to investigating the role of PCM to reduce the temperature fluctuation. The aim of this work is to experimentally investigate the effects of PCM on temperature fluctuation inside the cabinet of a household refrigerator during the door opening and power failure. The results found that a significantly lower temperature fluctuation can be obtained using PCM. It was found that during the door opening condition the air temperature in the cabinet rose rapidly. However, when a PCM container was used, temperature variation was reduced to 3–5°C. During the power failure, the system with PCM maintained a lower temperature inside the storage chamber for a long period of time (about 2 hours). Moreover, the test results indicate that PCM maintains more stable temperature in the foodstuffs inside the refrigerator. This reduction of temperature fluctuation ultimately improves the quality of preserved food.     

An examination of the efficacy of the precautionary principle as a robust environmental planning and management protocol

The precautionary principle is regularly cited in cases that involve development in eco-sensitive locations. We investigated whether the precautionary principle provides the basis for a coherent framework to prevent environmental harm, and does it work in practice? We suggest that, in principle, the precautionary principle makes good sense. In practice, however, it is imprecise in policy and law and fails to fulfil its promise because it is loosely defined and thus lacks substance and clarity. Consequently, it operates in a framework that is ambiguous, leaving it open to manipulation by discretionary powers. To counter such deficiencies, human-induced environmental harm should be formally observed as ‘criminogenic’ and environmental protection prioritised against which other competing priorities (e.g., ‘year on year’ economic growth) are measured. This would overcome the politico-legal obfuscation and contestations of climate change policy that currently impedes the precautionary principle's practical application.     

Using an expanded Safety Failure Event Network to analyze railway dangerous goods transportation system risk-accident

In order to improve the reliability and safety of railway dangerous goods transportation system (RDGTS), and prevent the similar accidents happened again, an easier operated, dynamic, systemic and quantitative approach called expanded Safety Failure Event Network (SFEN) is proposed to analyze the past typical RDGTS accidents. The expanded SFEN focuses on transfer the traditional safety occurrence process into a visible Accident Analysis Network (AAN) platform. To improve the previous SFEN approach, the risk factors categories are expanded including Human actions, Technical failure, Nature of transported goods, Environment factors, Management failure and External factors of the system. An AAN is established by using the risk factors as the nodes and using the interactions among these risk factors as the edges, the RDGTS risk analysis problem is transferred into a quantitative network structure analysis problem from a network perspective. After that, based on the AAN, TouchGraph and NetMiner are applied to calculate and rank the centrality degree of each sub-risk factor (or sub-heading) in a network. A RDGTS accident happened in 2001 is analyzed, the results show that TouchGraph and NetMiner can present the same interactions and importance of sub-risk factors (or sub-headings) through visible circle images in the platform, NetMiner is more digital because the results can be presented as the centrality degree values. The greatest contributed sub-risk factors are Equipment maintenance failure and Railway inspection agency failure, followed by cargo packaging problems, illegal entrainment problem. Misbehaves of the freight inspector with centrality degree 0.523810 shows that this sub-heading has the greatest contribution to the accident.     

基于非线性破坏准则的边坡稳定性分析

Baker提出的非线性破坏准则是一种广义的岩土体强度准则,常规的M-C强度准则、格里菲斯强度准则以及Hoek-Brown强度准则均为其特例。该准则通过大量的三轴试验引入无量纲强度参数A,n和T,其中A为尺度参数用于控制剪切强度的大小;n为准则曲线的次数用于控制曲率;T为转换参数用于控制准则曲线与σ轴的位置,并反映其无量纲拉伸强度。以Baker非线性强度准则为基础,以极限分析上限法为工具,采用"切线法"思想研究了静、动荷载下边坡的稳定性,将边坡的稳定性问题转化为含多变量的数学优化问题,并给出其最优解。通过算例分析,研究了非线性强度参数对边坡稳定系数与屈服加速度系数的影响。结果表明:边坡稳定系数随无量纲参数A,T的增大而增大;边坡屈服加速度系数随坡高、坡角的增加而降低。     

军用电子组件(PCBA)失效分析技术与案例

随着武器装备集成化、高密度化和轻量化的发展,大量的高密度器件如BGA、CSP得到了广泛的应用,由此作为武器装备心脏的军用电子组件的组装密度也越来越高。伴随着电子组件组装密度的提高,对于电子组件的组装技术也提出了更高的要求。然而,由于军用电子组件器件种类繁多,导致其电子组装工艺复杂,加上我国装备制造企业的工艺水平较国际先进企业相比还存在很大的差距,军用电子组件存在较为严重的工艺缺陷和可靠性问题。大量的工艺缺陷如润湿不良、焊点空洞、焊点机械强度差和疲劳寿命低严重影响了军用电子组件的质量和可靠性,并制约了武器装备的发展。本文针对军用电子组件存在的焊接缺陷、绝缘性失效(CAF和ECM)以及焊点疲劳失效的主要问题,介绍了军用电子组件常用的失效分析方法和手段,包括金相切片分析、声学扫描分析、扫描电镜与能谱、热分析以及傅立叶红外光谱分析等。然后结合军用电子组件的典型的失效分析案例,介绍这些分析技术在实际的案例中的应用。PCBA失效机理与原因的获得将有利于将来对PCBA的质量控制以避免类似问题的再度发生。     

亚急性镉暴露对雄性黑斑蛙生殖毒性的研究

在实验条件下,将健康性成熟雄性黑斑蛙暴露于2.5、5.0、7.5和10.0mg·L-1浓度的镉溶液中14d,观察和分析黑斑蛙的精子数量、精子畸形率,测定精巢组织中酸性磷酸酶(ACP)、乳酸脱氢酶(LDH)、丙二醛(MDA)、谷胱甘肽(GSH)、超氧化歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)的水平和活力,以探讨镉对黑斑蛙的雄性生殖毒性及作用机理.结果表明:①镉可引起黑斑蛙精子数量减少和精子畸形率增加,且呈剂量-效应关系;②镉可引起精巢ACP、LDH酶活性的降低,且随染毒剂量的增加而降低;③镉可引起精巢组织MDA、GSH含量的升高,引起抗氧化酶SOD、GSH-Px活性的降低.由此推论,亚急性镉暴露对黑斑蛙精巢有明显的毒性作用,其机制与镉致黑斑蛙精巢组织标志酶活力的降低和精巢脂质过氧化作用有关.     

装备故障率预测模型

通过对武器装备故障数据统计分析,建立故障率模型,重点考虑装备使用年限和年平均湿度两个指标,提出环境适应因子计算方法,并通过实例分析验证了模型的准确性,为提高装备的维修保障效率提供一定决策依据.