Non-parametric Estimation for NHPP Software Reliability Models

The non-homogeneous Poisson process (NHPP) model is a very important class of software reliability models and is widely used in software reliability engineering. NHPPs are characterized by their intensity functions. In the literature it is usually assumed that the functional forms of the intensity functions are known and only some parameters in intensity functions are unknown. The parametric statistical methods can then be applied to estimate or to test the unknown reliability models. However, in realistic situations it is often the case that the functional form of the failure intensity is not very well known or is completely unknown. In this case we have to use functional (non-parametric) estimation methods. The non-parametric techniques do not require any preliminary assumption on the software models and then can reduce the parameter modeling bias. The existing non-parametric methods in the statistical methods are usually not applicable to software reliability data. In this paper we construct some non-parametric methods to estimate the failure intensity function of the NHPP model, taking the particularities of the software failure data into consideration.     

英语作文分项评分的多元概化理论分析

以分班测试项目中使用多元概化理论对英语作文分项评分进行实证分析以了解评分信度,数据分析结果表明作文分项评分能提供较为详细的得分信息,真实地反映出受试写作能力发展存在的不均衡性;分项评分的总体信度比较理想,但子项的评分信度差异较大,说明评分人对各评分子项的认识和掌握情况不一致.     

Reliability Evaluation of a Multi-state Network with Multiple Sinks under Individual Accuracy Rate Constraint

From the viewpoint of service level agreements (SLAs), Internet service providers and customers are gradually focusing on transmission accuracy. The Internet service provider should provide the specific bandwidth and individual accuracy rate requirement by their SLAs to each customer. This paper mainly evaluates the system reliability that a stochastic computer network can fulfill all requirements at all sinks. An efficient algorithm is proposed to generate the lower boundary points, minimal capacity vectors satisfying the demand and accuracy rate requirement for all sinks. The system reliability can be computed in terms of such points by applying recursive sum of disjoint products.     

某大型装置现场可靠性的贝叶斯分析

可靠性、维修性和可用性是描述复杂装置质量属性的三个重要指标。在某大型装置的现场故障和维修数据的经验分析基础上,运用分段线性模型确定了装置可靠性改进趋势。针对装置现场故障和维修数据的小样本问题,给出了装置现场可靠性和维修性的贝叶斯模型,并用WinBUGS软件对其进行了求解计算。继而分析给出了装置可用性最恰当描述——任务可用度的闭合表达形式。最后,通过与极大似然法进行对比,发现应用贝叶斯方法分析该大型装置现场可靠性更有效。     

On the optimal allocation of active redundancies in series system

This paper studies the allocations of two non identical active redundancies in series systems in terms of the reversed hazard rate order and hazard rate order, which generalizes some results built in Valdés and Zequeira (2003 Valdés, J. E., and R. I. Zequeira 2003. On the optimal allocation of an active redundancy in a two-component series system. Stat. Probab. Lett. 63:325–32.[Crossref], [Web of Science ®] , [Google Scholar], 2006 Valdés, J. E., and R. I. Zequeira 2006. On the optimal allocation of two active redundancies in a two-component series system. Oper. Res. Lett. 34:49–52.[Crossref], [Web of Science ®] , [Google Scholar]).     

Markov模型的软件可靠性测试充分性问题的研究

在分析现有Markov模型的软件可靠性的充分性判别的基础上,定义了严格转移概率的概念,提出了基于严格转移概率的测试充分性判别方法。将Markov模型转化为严格Markov模型,在每个边或者状态的差异计算时引入严格转移概率,对可达相异转移集中所有可达相异转移k的转移概率进行原转移概率对应计算后进行求和再平均运算,得到的结果作为每个边或者状态的差异值。实验表明严格测试充分性判别方法比非严格Markov模型方法更稳定、有效。     

大学生英语论文写作的言据性研究

言据性是作者对所述命题信息的来源及其可靠程度的语言编码。通过对大学生英语论文中言语证据（言据性）手段使用的考察后发现：论文得分与言语证据、感官证据等手段的使用存在显著性正相关;与信念手段的使用也显著相关,但方向为负;与演绎手段的使用呈弱相关。大学生在论文中言语证据手段使用的差异既体现在使用的频率上,又表现在使用的质量上,而且具有中介语特征。在英语论文写作教学过程中,教师应有意识地引导学生在实践中学会规范、合理、有效地使用各类言语证据手段。     

固体火箭发动机壳体强度可靠性分析

模拟某型号固体火箭发动机壳体水压试验状态.建立该固体火箭发动机壳体有限元模型,利用ANSYS软件对壳体进行确定性有限元分析找出应力值最大区域,再进行随机有限元分析,求得可靠度.根据所求的可靠度作为理论依据增加壳体承压并再计算可靠度.分析表明:原设计压力保守,在可靠度允许范围内壳体可承受更大压力;对各参量进行灵敏度分析,为结构参数的优化设计提供理论依据.     

英语专业课堂研究中问卷调查表的效度、信度及可操作性

问卷调查作为一种方法与采集数据的工具,有望在第二语言教学与研究中受到愈来愈广泛的使用.问卷调查的设计准备工作牵扯到问卷调查表本身,包括哪些相关问题、问题的形式和种类及排列顺序、问卷调查表的数量、印刷质量、成本以及调查表的发放、回收及后期数据的整理等.然而在问卷调查表设计的始终,我们都应当关注设计标准,关注问卷调查表在效度、信度及可操作性三大设计标准方面的具体体现.     

Safety and Aircraft Maintenance: A Moral Evaluation

In this article I will discuss the construction of safety in high reliability organizations. This construction is then evaluated from a moral point of view. I will argue that accidents happening to high reliability organizations make clear that we have to reconceptualize our notion of moral responsibility. This revised version was published online in July 2006 with corrections to the Cover Date.