非确定工作状态下机械系统可靠性分析

产品的可靠性是设计出来的,在产品设计阶段如何预计其可靠性水平,为产品设计提供参考显得尤为重要。通过建立零件失效率与零件状态向量、系统失效率与零件失效率、系统状态向量与零件状态向量之间的关系,最终建立起系统状态向量与系统失效率之间的联系。由于系统状态的不确定性,使得系统在工作过程中的可靠性水平也表现出不确定性。利用蒙特卡洛方法,以某机床主轴传动系统为例,利用系统状态向量与系统失效率之间的关系,对非确定工作状态下主轴传动系统的失效率进行了统计规律分析。     

无铅工艺在电梯印板生产的技术准备

无铅化工艺会对可靠性带来冲击,特别是对于要求高可靠性的电梯行业,对于PCB组件,原先可最低程度接受的焊接,现在成为了缺陷或不合格。无铅化装配要求在铜、基础材料和设计之间进行均衡,在工艺方面进行更新,以确保印板装配质量可靠性。     

FC2000发动机测控系统在微型和轻型手动变速器可靠性试验中的应用

随着汽车工业的发展,人们对汽车的要求越来越高.变速器是汽车的关键零部件总成之一,其可靠性极大地影响了汽车的寿命.在湘仪FC2000测控系统上进行手动变速器的可靠性试验和针对试验对系统进行相应的调整和修改,以顺利完成试验.     

油气管道结构全寿命周期可靠性优化方法

对油气管道结构的优化设计方法进行了新的探讨,得到了以油气管道结构生命全过程的动态可靠性为约束,以油气管道结构初始投资、失效损失和维修加固费用之和为目标函数的油气管道结构优化设计表达式。该方法对油气管道结构的设计和管理具有一定的参考价值。     

深亚微米CMOS器件可靠性机理及模型

随着CMOS集成电路特征尺寸的不断缩小,特别是在其发展到深亚微米阶段之后,CMOS器件面临着负偏置温度的不稳定性、栅氧化层经时击穿、互连系统的电迁移和热载流子注入等可靠性问题。重点对近年来研究得到的深亚微米CMOS器件可靠性机理及其可靠性模型进行了总结。     

仿真技术在电子产品优化设计中的应用

随着电子产品的高速发展,采用EDA软件进行电路仿真与设计已成趋势。针对电子产品设计方法的不断更新,讨论了电子产品的最优化设计。以低通滤波电路设计为例,借助AltiumDesigner软件,对设计电路的直流工作点、瞬态过程、交流小信号、参数扫描等进行了详细分析。实验结果表明:实际设计电路的响应与仿真结果吻合,说明该方法可缩短新产品的开发周期,提高电子产品的设计效率与质量,有利于改进产品的可靠性。     

一种全封闭的对称型刚挠结合板生产工艺

以刚性板的制程工艺为基础介绍了一种全封闭式的对称型刚挠结合板的制作方法,并且对制程的几个关键环节进行充分的分析和说明,以一种能够产业化的工艺路线从设计、生产、质量控制等角度全面展示了这一工艺的实现过程。     

Semi-flex印制板制作工艺研究

使用半固化片(PP)开窗法制作Semi-flex印制电路板时,半固化片开窗的尺寸及品质直接影响压合时树脂向Semi-flex印制板挠性区域的流动情况,进而影响其挠曲性能。本文使用开窗法制作挠性层为L5/L6层的10层Semi-flex印制板,研究了铣刀转速、叠合张数等加工参数对半固化片开窗品质的影响,以及半固化片开窗放大尺寸与压合时刚挠结合处PP溢胶长度的关系。为了验证产品其可靠性,对其进行了漂锡测试、回流焊测试和冷热冲击测试。     

Agreement and reliability in measuring central corneal thickness with a rotating Scheimpflug–Placido system and ultrasound pachymetry

PurposeWe compare the agreement and the reliability in measuring central corneal thickness (CCT) using two different technologies.MethodThe right eyes of 35 healthy individuals who had a negative history of ophthalmic disease, or ocular surgery were examined. The CCT was determined sequentially with a rotating Scheimpflug camera (Sirius; CSO), and an ultrasound pachymeter (P-1; Takagi). For statistical analysis, we used the methods suggested by Bland and Altman.ResultsThe mean values of CCT obtained from Sirius, and ultrasound were 537 ± 28 μm, and 550 ± 35 μm, respectively. There was a high correlation between Sirius and ultrasound (r = 0.92; p < 0.001), but the difference between the two measurements was statistically significant (t = −5.7; p < 0.00001). The precision of Sirius and ultrasound were 9.4 and 15.9 μm; repeatability 13.3 and 22.4 μm, and coefficient of variation 0.9% and 1.5%, respectively. The intraclass correlation coefficient was 0.97 for Sirius and 0.95 for ultrasound.ConclusionsThe average difference between corneal thickness measured with Sirius and ultrasound pachymetry was small but clinically significant. This means that the two instruments cannot be used interchangeably. Sirius showed precision and repeatability almost twice as much as ultrasound pachymetry. Confidence interval of 13.3 μm for Sirius can show variations in corneal thickness with an uncertainty value lower than 2.5% in 95% of cases. The simplicity of use, the possibility to obtain pachymetric maps, and less invasiveness make this instrument potentially useful in contact lens practice.     

Slope Reliability Analysis Considering Site-Specific Performance Information

The performance of a slope, such as surviving a certain groundwater condition, can be viewed as the outcome of a full-scale test performed directly on the slope and may provide valuable information for safety assessment, upgrading analysis, and repair design of the slope. Performance information can be divided into two types: (1)?the slope survived a certain state, and (2)?the slope failed at a certain state. This paper illustrates two methods for slope reliability analysis considering site-specific performance information, i.e., an indirect method based on back-analysis of the performance information, and a direct method, in which the back-analysis procedure is bypassed. The two methods are theoretically the same but different in implementation details. As examples, an existing slope for safety assessment and a failed slope to be repaired are studied in this paper. Considering the past survival information increases the reliability of the slope. The increase in reliability is larger if the slope survives a more critical state. Thus, ignoring the survival information may result in uneconomical decisions. In contrast, ignoring the failure information may either underestimate or overestimate the reliability of a slope. As a result, neglecting the past failure information may lead to unsafe or uneconomical decisions.