Comparative study in chemistry of microbially and electrochemically induced pitting of 316L stainless steel

Ennoblement of stainless steel (SS) by microbially deposited manganese oxides can lead to pitting corrosion at low chloride concentrations, causing unexpected material failures. We exposed 316L SS to manganese oxidizing bacteria Leptothrix discophora under well-defined laboratory conditions, and then placed the ennobled coupons in a 0.5 M sodium chloride solution until pitting developed. Using time-of-flight secondary ion mass spectroscopy we demonstrated that the pits and their immediate vicinity associated with microbial influenced corrosion had different chemical signatures than those associated with electrochemically induced pitting, suggesting a possibility that the microorganisms were directly involved in pit initiation. Based on the differences in the chemical signatures we were able to distinguish the microbially induced pits from those induced by anodic polarization.     

精铣缸体顶面、精镗缸孔及止口数控自动线的研制

文章阐述了用数控自动线精铣缸体顶面、精镗缸孔及止口的设计依据和工艺方案，并对自动线的布局及采用的浮动式精密镗削头、滑台式精密铣削头、数控三导轨机械滑台、自动补偿镗杆、数控系统等关键部件的结构、原理及功能做了详细的介绍。该自动线的研制，解决了单机加工效率低、国内用户只能依赖进口设备的关键技术问题。     

氢对不锈钢钝化膜破裂应力的影响

用纳米力学探针测量了316不锈钢电解抛光以及抛光后阳极钝化试佯的载荷-压入位移曲线，并研究了氢的影响．结果表明，一旦表面存在氧化膜(电解抛光)或钝化膜(阳极钝化)，在载荷-位移曲线上就会出现恒载荷平台；对氧化膜，平台载荷较小，对应膜的屈服；对钝化膜，平台载荷较大，对应膜的破裂．氢可降低钝化膜的平台载荷以及相同载荷下的压入位移，从而使得钝化膜的复合弹性模量Er和破裂应力σF都随试样中氢浓度Co的升高而下降，例如，Er(GPa)=100 82e^-0.01Co，σF(GPa)=1．59 2．93e^-0.010Co。     

IMPROVEMENT OF TYPE IV CRACKING RESISTANCE OF 9Cr HEAT RESISTING STEEL WELDMENT BY BORON ADDITION

Creep lives of high Cr ferritic heat resisting steel weldments decrease due to Type Ⅳ fracture, which occurs as a result of formation and growth of creep voids and cracks on grain boundaries in fine-grained heat affected zone (HAZ). Because boron is considered to suppress the coarsening of grain boundary precipitates and growth of creep voids, we have investigated the effect of boron addition on the creep properties of 9Cr steel weldments. Four kinds of 9Cr3WSCoVNb steels with boron content varying from 4.7×10-5 to 1.8×10-4 and with nitrogen as low as 2.0×10-5 were prepared. The steel plates were welded by gas tungsten arc welding and crept at 923K. It was found that the microstructures of HAZ were quite different from those of conventional high Cr steels such as P91 and P92, namely the fine-grained HAZ did not exist in the present steel weldments. Boron addition also has the effect to suppress coarsening of grain boundary carbides in HAZ during creep. As a result of these phenomena, the welded join     

可组合的描述符泄露类型检查

应用程序通过操作系统的系统调用对文件描述符进行操作并管理文件资源。如果应用程序对资源描述符的管理出现错误并发生描述符泄漏,会严重影响系统的可用性。据此,提出了一种检查程序是否会导致描述符泄漏的类型系统,给出了描述符操作方法的语义和类型约束,证明了类型系统的可靠性定理。此外,还初步讨论了该类型系统在并发程序下的扩展。     

Effectiveness of Security Control Risk Assessments for Enterprises: Assess on the Business Perspective of Security Risks

ABSTRACT

Today's businesses being IT enabled, the complexity of risks affecting the business has increased manifold and the need to gauge the Information Technology risks acting on the business operations has become paramount. The business managers who run business operations need to operate securely and seamlessly leveraging Information Technology and ability to recover and resume the business without any loss of confidentiality, integrity and availability of business information/data in any event of a security incident.

There is a need to quantify the impact of the IT security risk on the critical business processes, and provide the business-level insight at the management level. It is critical to classifying the Risk Ratings as per the impact on the business operations. This approach allows the organizations to understand and prioritize the security risk management activities that make the most sense for their organization to secure the business operations instead of trying to protect against every conceivable threat.     

基于模糊聚类算法的故障数据分析与类型识别

为精确分析测量系统故障数据和识别故障类型,提出一种基于模糊聚类算法的故障数据分析方法。该方法首先用小波变换有效地检测出系统故障的微弱非线性不规则信号,再用模糊聚类的方法对故障进行分类识别。由于该算法在目标函数中加入隶属度函数,同时定义明可夫斯基的距离测度,因此能够克服K-means算法不适用于进行非凸形状的聚类的缺点,从而使诊断的数据更加精确。     

缺陷需求分析与管理模型

需求管理是软件过程改进的重要活动,需求缺陷管理是需求管理的重要组成部分,其目的在于检测、分析、解决和预防需求缺陷.从社会因素和技术因素两大方面分析了需求工程阶段缺陷产生的原因,对缺陷进行了分类.建立了需求(模型)缺陷列表、缺陷需求分析模型和基于需求缺陷管理的需求过程模型.指出需求缺陷列表所反映的需求分析过程的数量特征,能够为评估需求工程师能力、准确和全面地定义需求成熟度、研究需求演化波及效应、研究需求模型复杂度和需求缺陷分布规律提供必要数据和有益启示.     

几种主流编程语言的特点与比较

计算机编程语言种类很多,但仅有少数几种语言得到了比较广泛的应用。本文选择了C语言、VB、VB．NET和Java作为讨论对象,首先总结比较了它们的数据类型、控制语句的语法,然后对编码规则的细节进行了阐述,最后讨论了这几门语言的技术性能特点。     

几种主流编程语言的特点与比较

计算机编程语言种类很多,但仅有少数几种语言得到了比较广泛的应用。本文选择了C语言、VB、VB.NET和Java作为讨论对象,首先总结比较了它们的数据类型、控制语句的语法,然后对编码规则的细节进行了阐述,最后讨论了这几门语言的技术性能特点。