Estimation of system reliability for exponential distributions based on L ranked set sampling

Abstract

In the case where strength and stress both follow exponential distributions, this paper considers the maximum likelihood estimator (MLE) of the system reliability based on L ranked set sampling (LRSS). The proposed MLE is shown to have existence, uniqueness and asymptotic normality, and its asymptotic variance is obtained by the Fisher information matrix of LRSS. The values of asymptotic relative efficiencies show that the proposed MLE is always more efficient than the MLE using simple random sampling (SRS). However, the MLE using LRSS cannot be written in closed form. Therefore, the modified MLE is proposed using the technique replaced some terms in the maximum likelihood equations by their expectations. The newly modified MLE using LRSS is shown to be superior to the MLE using SRS. Finally, the proposed method is applied to a real data set on metastatic renal carcinoma study.     

A sampling plan for one-shot systems considering destructive inspection

Abstract

The paper is concerned with an acceptance sampling problem under destructive inspections for one-shot systems. The systems may fail at random times while they are operating (as the systems are considered to be operating when storage begins), and these failures can only be identified by inspection. Thus, n samples are randomly selected from N one-shot systems for periodic destructive inspection. After storage time T, the N systems are replaced if the number of working systems is less than a pre-specified threshold k. The primary purpose of this study is to determine the optimal number of samples n*, extracted from the N for destructive detection and the optimal acceptance number k*, in the sample under the constraint of the system interval availability, to minimize the expected cost rate. Numerical experiments are studied to investigate the effect of the parameters in sampling inspection on the optimal solutions.     

城市社区老人心理健康服务现状调查——来自重庆市主城社区的调查数据

以重庆市主城社区老人为调查对象,从老人的基本情况、心理健康状况、心理健康服务需求、心理服务支持系统等方面的调查数据进行详细分析,得出了家庭、邻里同辈群体是老人心理健康的重要支持系统、需要建立完善的城市社区老人心理健康服务体系等结论。     

客户价值评价指标体系设计

客户关系管理是目前管理研究的热点,企业对客户价值的评估是其基础问题之一。如何设计一套实用的客户价值评价指标体系仍是尚未解决的问题。针对这种情况,在客户全生命周期管理的指导下,本文设计了一套分别针对最终客户和中间客户的评价指标体系,详细阐述了其管理应用,并进行了具体案例分析,证实了该指标体系的有效性。     

基于进化博弈的专利联盟形成研究

专利联盟作为高新技术产业发展的主导范式,对技术标准的建立有重要的作用。但是多数情况下提高社会福利的联盟却难以形成,这就是所谓专利联盟的形成困境问题。从专利权人的有限理性和重复博弈角度分析专利联盟的形成,分别建立对称和非对称专利联盟形成的进化博弈模型,得到不同条件下的进化稳定策略,并探讨影响联盟形成的条件和因素。研究结果表明,专利联盟更容易在弹性高、竞争激烈的市场环境中形成;与事实标准建立以后相比,在事前组建的专利联盟形成可能性更大;通过多方途径保护和提高加入联盟的专利权人的利润,同时抑制阻碍联盟的专利权人的利润,是促进联盟形成的关键;与专业R&D企业相比,纵向一体化企业有更强的动机加入联盟。健全和完善相关法规及配套服务对联盟形成也是有益的。     

企业体系结构的建模框架研究

经济全球化的趋势深刻影响着企业组织管理的各方面.在新的环境下,企业的业务处在不断变化的过程中,企业信息系统(Enterprise Information Systems,EIS)作为企业管理系统的重要组成部分,面临前所未有的挑战.EIS项目的开发方式存在的问题使得业务与技术的演进难以同步,阻碍了企业的变革.近年来,企业体系结构(En-terprise Architecture,EA)的研究在信息管理领域正得到越来越多的关注.EA作为业务流程和IT架构的组织逻辑,反映了标准化和集成化的公司运作模型,目标是得到业务的敏捷性和利润的增长.本文探讨EIS开发方法的问题,介绍EA的概念和代表框架,总结EA的一般特点,研究EA对EIS开发的重要意义.     

A dynamic business modelling approach to design and experiment new business venture strategies

Business Modelling has evolved as a key activity to reflect new business venture strategy by framing the way a firm will operate and how it will function in achieving its goals (e.g., profitability, growth, innovation, social impact). However, scholars and practitioners have criticized the adoption of a too static perspective in the design and use of conventional Business Model representations. Such a static perspective prevents nascent entrepreneurs experimenting with their Business Models and, as a result, identifying the most effective strategies, especially in terms of business sustainability and profitability. In this paper, we argue that combining conventional Business Model schemas with System Dynamics modelling results in a strategy design tool that may overcome several limitations related to a static view of Business Model representation. Mapping the different key elements underlying value creation processes into a system of causal interdependencies – through the use of simulation – allows strategy analysts and entrepreneurs to experiment and learn how the business reacts to strategic and organizational changes in terms of performance, innovation and value creation. As such, Dynamic Business Models provide useful insights to strategy formulation and business venturing by capturing how critical Business Model elements interact to produce enduring competitive advantages over time.     

Aggregation and Optimization with State‐Dependent Pricing: A Comment

A key argument in Caplin and Leahy (1997) states that the correlation between monetary shocks and output is falling in the variance of the money supply. We demonstrate that this conclusion depends on solving for the correlation in the nonstationary state of the model. In the stationary state, that correlation is initially rising.     

Scrutinising the interplay between governance and resilience in supply chain management: A systems thinking framework

Supply chain disruptions recurrently challenge end-to-end operations owing to the ambiguous understanding of the role of governance in impacting supply network resilience. This paper scrutinises the relevant literature to understand the plethora of interpretations in supply chain governance and resilience while further providing a new perspective on the representation of the interplay between governance and resilience in supply chains. In this regard, the Systems Thinking lens is adopted to pull together the typologies and constructs of supply chain governance and resilience from the literature. Methodologically, System Dynamics modelling principles are leveraged to capture the underpinning structural interdependencies in a causal loop diagram. The study reveals that endogenous and exogenous supply chain governance processes and mechanisms support the intrinsic and extrinsic resilience in networks. Overall, this research contributes to the supply chain risk management domain by synthesising the interplay between governance and resilience, identifying pertinent typologies, and articulating research propositions that can inform decision-making at policy and management levels.