基于Moldflow的带金属嵌件打印机板浇口优化设计

针对带金属嵌件打印机板使用传统注塑模具设计方法时,存在开发周期长、成本高且质量不易保证等缺点,采用 计算机辅助设计软件Pro/E和有限元分析软件Moldflow相结合的方法对制品进行不同浇口位置方案下的“填充+保压 +翘曲”模拟分析,从充填时间、流动前沿温度、气穴、熔接痕和翘曲变形等方面进行了综合比较和评测,确定了最佳浇口 设计方案。结果表明,应用Moldflow软件进行模拟仿真,找出了制件在不同浇口设置环境下缺陷产生的原因,从而为避 免或消除制件上的缺陷,进一步优化模具设计、降低生产成本,为指导实际生产提供合理的依据。     

Availability analysis for general repairable systems with repair time threshold

Availability analysis is an important issue in many practical fields. This paper investigates the availability for general repairable systems with repair time threshold. Based on practical applications, a repair time threshold is introduced. If the period of a repair is less than a predefined time threshold, then the system may be considered as working during this period, i.e., the effect of the repair could be neglected. Otherwise, if the period of a repair is longer than the given threshold, then the system is considered as working from the beginning of the system failure until the repair time exceeding the threshold, i.e., the time point of the system down could be delayed. We consider both constant and random repair time threshold. This paper valuates the user-perceived availability, when the user does not experience any service interruption because the duration of repair is too short. The results can be applied in reliability engineering, queueing theory and many other fields. A numerical example for ventilator system is presented to demonstrate the application of the developed approach.     

VaR方法在信用衍生债券投资风险测量中的应用

在介绍和引进信用衍生债这一衍生工具的过程中,以往研究者过多地注重于该衍生工具风险分散功能的应用,却很少考虑这一衍生工具投资风险的特殊性.在揭示信用衍生债券投资风险的同时,拟应用VaR方法举例说明如何衡量此类风险,进而实现定量化的投资风险控制.     

From the Digital Divide to the Connectivity Dividend Difference: A Connectivity Capital Perspective*

The access divide was once the basic form of the digital divide. The development of Internet infrastructure has narrowed the access divide and increased application coverage, but it has also touched off a connectivity dividend difference. Taking the online market as an example, we examine the sources of the dividend difference and the factors influencing it with in a connectivity framework. We found that the narrowing of the access divide has resulted in enhanced connectivity and platform development, giving people the chance to benefit from transforming the various assets in which they have previously invested into differentiated compound connectivity capital. In the course, the scale and rate of the conversion are affected by two multiplier effects and especially by online platforms. The process is ultimately expressed in the dividend difference.     

乌托邦情结的消解——中国“后新时期”文学创作的一种精神向度及其文化品性

乌托邦作为一种人文主义的理想 ,是历代具有使命和责任感的作家的精神追求。本文拟就 80年代中期以来 ,中国文学领域出现的一种反乌托邦创作倾向 ,阐述文学作品在削弱和厌弃了精神性力量之后 ,具有明显的后现代文化品性这一观点。其表现为 :深度意义的消失 ,历史意识被抹去 ,主体的跌落等。并指出 ,反乌托邦作品是以消解理想主义谜底的方式重设虚无的寓言。     

我国化学修饰电极研究概况

评述了我国化学修饰电极的研究状况及其在电催化、富集分离、化学传感器等方面的应用,展望了化学修饰电极用于分析化学的前景。     

区位导向型产业政策对城市创新的影响研究

本文以国家高新区设立为准自然实验,通过构建渐进双重差分模型对国家高新区政策的创新激励效应进行了识别与评估.研究结果表明:国家高新区政策实施有助于提升地区创新水平,但国家高新区政策影响城市创新的方向和程度取决于高新区成长周期及所属地区环境,处于成熟期或者位于东部地区的高新区对城市创新水平提升具有更强的带动作用;动态效应检验结果发现,随着国家高新区发展日趋成熟,其对城市创新水平的促进作用将越来越大.     

跟踪调查中的拒访行为分析——以中国家庭动态跟踪调查为例

在梳理拒访影响因素理论模型的基础上,本文运用中国家庭动态跟踪调查(China Family Panel Study,CFPS)测试初访和测试第一次追访的并行数据和问卷数据,运用Logit模型对CFPS测试第一次追访中出现的受访家户拒访行为进行分析。分析发现,CFPS追访调查样本存在选择性拒访现象。追访中,被拒访的特点和模式与发达国家的基本一致,即受到受访家户和主事者社会经济特征、参访经历等因素的影响。分析还发现,在追访中,受访对象的拒访行为是可预测的。根据前次收集的并行数据和问卷数据,可以甄别未来可能拒访的重点对象。如能依此采取特别的样本维护策略,应可降低跟踪调查样本的损失率。     

物联网及其在物流产业中的应用研究

作为一项战略性新兴产业,物联网的出现正在改变着社会的生产方式、生活方式和生存方式。本文探讨了物联网的主要关键技术构成,并深入分析其在运输、仓储、配送和物流信息平台建设等方面的应用,最后指出物联网在物流产业中应用所面临的困难和挑战。     

An improved two-stage procedure to compare hazard curves

Qiu and Sheng has proposed a powerful and robust two-stage procedure to compare two hazard rate functions. In this paper we improve their method by using the Fisher test to combine the asymptotically independent p-values obtained from the two stages of their procedure. In addition, we extend the procedure to situations with multiple hazard rate functions. Our comprehensive simulation study shows that the proposed method has a good performance in terms of controlling the type I error rate and of detecting power. Three real data applications are considered for illustrating the use of the new method.