Expected termination times of progressively Type-I censored step-stress accelerated life tests under continuous and interval inspections

A step-stress accelerated life test is a special life test where test units are subjected to higher stress levels than normal operating conditions so that the information on the lifetime parameters of a test unit can be obtained more quickly in a shorter period of time. Also, progressive Type-I censoring is a generalized form of time censoring where functional test units are withdrawn successively from the life test at some prefixed nonterminal time points. Despite its flexibility and efficient utilization of the available resources, progressively censored sampling has not gained much popularity due to its analytical complexity compared to the conventional censoring schemes. In particular, understanding the mean completion time of a life test is of great practical interest in order to design and manage the life test optimally under frequent budgetary and time constraints. In this work, the expected termination time of a general k-level step-stress accelerated life test under progressive Type-I censoring is derived using a recursive relationship of the stochastic termination time based on the conditional block independence. To be comprehensive, two different modes of failure inspections are considered: continuous inspection, where the exact failure times are observed, and interval inspection, where the exact failure times are not available but only the number of failures that occurred.     

论连续并购与间隔并购样本的差异

在已有对并购的研究中,学者们没有细分连续并购样本和间隔并购样本。他们大多数采取两种方式:一种是把连续并购剔除在外,另一种是把连续并购和间隔并购放在一起,致使我们的并购研究无法突破。本研究选取四大类别熵,即:支持型熵、压力型熵、还原型熵、氧化型熵作为变量,利用参数和非参数检验进行样本的差异检验。最后发现:连续并购和间隔并购有实质性的区别。这给我们今后做并购研究的样本选取提供了有利的支持。     

智能变电站间隔层防误闭锁运行维护有关问题的探讨

文章通过对220 kV兴国智能变电站在间隔层防误闭锁的实践,分析了间隔层防误的原理,提出了防误闭锁规则的设计思路,总结了管理中存在的问题。     

An investigation of transformation-based prediction interval for the Weibull median life

Statistical inference based on the Weibull distribution, a distribution widely used in reliability and survival analysis, is usually difficult as it often involves numerical computation and approximation. However, this distribution can be transformed to near-normality by a simple power transformation. Based on this transformation, a prediction interval (PI) for its median can be easily constructed through an inverse transformation. The procedure for selecting the best power transformation through minimizing Kullback-Leibler information is described. The property of this transformation-based PI is investigated. Simple correction factors are also proposed. It is shown that the transformation-based PI with corrections performs well, irrespective of the sample size and parameter values. Simulation results show that the new PI generally outperforms the existing PI. Numerical examples are given for illustration.     

老字号品牌资产五维度探析——基于Aaker理论

作为曾经的强势品牌,老字号品牌资产流失严重,在老字号品牌资产的五个维度中:忠诚顾客偏少、趋于老化但相对牢固;品质认知度和美誉度较高;品牌联想中历史文化联想丰富而现代联想不足;知名度则限于老顾客且区域性较强,在新顾客中知名度较低;市场行为方面,市场份额低,营销能力薄弱。     

考虑运输时间的生产过程时间组织问题研究

在考虑运输时间的基础上,研究一批零件在工序间的移动方式,推导出含运输时间的顺序移动、平行移动和平行顺序移动方式的零件生产周期计算公式。之后,研究三种不同移动方式下,零件在各工序间的搬运次数和零件的搬运数量等问题。最后,以一个实例进行详细的分析。     

Asymptotically optimal estimation of smooth functionals for interval censoring, part 2

Estimation in the interval censoring model is considered. A class of smooth functionals is introduced, of which the mean is an example. We consider case 2, with two observation times for each unobservable event time, in the situation that the observation times cannot become arbitrarily close to each other. It is proved that the nonparametric maximum likelihood estimator of the functional asymptotically reaches the information lower bound.     

计算机库存控制系统的开发与应用

以库存控制论、决定支持系统理论为基础，对计算机库存控制系统的分析与设计作了深入的分析研究，提出了企业借助计算机技术实现科学控制库存的实用方法。     

Measuring the readability performance (RP) of aircraft maintenance technical orders by fuzzy MCDM method and RP index

With the development of the global economy and the ease of air transportation, extra emphasis has been placed on flight safety. There are precise specifications and procedures in the operation and maintenance of aircraft. Human errors and mechanical disorders are two key factors of flight safety. The maintenance personnel need to follow an outlined procedure to avoid human errors and ensure flight safety. Readability of aircraft maintenance technical orders can affect the quality and reliability of aircraft maintenance. To ensure the editing quality of technical orders, controlling/monitoring the number of unreadable sentences is important and necessary. In this study, the number of unreadable sentences found in a technical order was used as the measure of readability performance (RP) as well as a readability performance index was provided to evaluate whether the RP of individual readability characteristics of technical orders was adequate. Different readability characteristics make different grade of RP loss. Based on fuzzy multiple criteria decision-making (Fuzzy MCDM) approaches, we investigated the expert opinions to rank and calculate the weights of all readability characteristics. At the same time, we proposed the upper limits of unreadable sentences according the weights of individual readability characteristics. In this paper, the technical orders issued by Taiwan Aerospace Industrial Development Corporation was used as an example to evaluate the readability of the technical orders and total RP losses for individual readability characteristics. Finally, an improved way of editing quality for technical orders was recommended.     

Tail index estimation based on linear combinations of intermediate order statistics

Based on linear combinations of intermediate order statistics, we introduce a new class of estimators for the exponent of a distribution function F with a regularly varying upper tail. We prove asymptotic normality and we make a comparison with existing proposals using the mean squared error as criterion.     

Regression with errors in variables: estimators based on third order moments

In this paper consistent and, in a well–defined sense, optimal moment–estimators of the regression coefficient in a simple regression model with errors in variables are derived. The asymptotic variance and other asymptotic properties of these estimators are given. As is known for a long time, serious estimation problems exist in this model. There are two ways out of this problem: using either additional assumptions or additional information in the data. A lot of attention has been paid to the use of additional assumptions. However, quite often this leads to rather unrealistic models. In this paper we use additional information in the data. That means here that, besides first and second order moments, third order moments are formulated as functions of the model parameters. Besides theoretical derivations a small study with generated data is discussed. This study shows that for samples larger than 50 the estimates we consider behave nicely.     

基于要素构成的街道景观营建与导控

街道景观是城市意象体验的基本裁体,也是规划和建设多种要素的结构体现.通过分析城市街道景观系统的构成特点,在空间导控和营建工作两个方面提出思路策略和技术原则,探索适宜的街路界面塑造模式与特色.针对空间、要素两个方面的组成关系进行街路景观的系统解析;同时结合当前的工程实践操作,提出有效的控制与引导方法,建立街道景观建设的内部秩序.     

区间规划在证券投资组合问题中的运用

本文基于区间规划的方法研究了摩擦市场的投资组合选择问题。文中把风险证券的收益率、投资风险及证券的流动性用区间数来描述,并结合绝对偏差风险函数的思想建立了一种关于区间数的证券投资组合选择模型。最后利用区间数的两种序关系将所提出的模糊线性规划问题转化为普通的参数线性规划问题进而求其解。     

Business model based on strong sustainability: Insights from an empirical study

The extant literature on traditional and sustainable business models lacks insights into how strong sustainability—that is, constraining economic and social activities within the limitations of natural resources—can shape business models. Thus, the purpose of this article is to propose a business model framework based on the principles of strong sustainability (SSBM). The proposed framework is developed combining available literature and empirical insights from a qualitative abductive study of 12 permaculture business ventures in Sweden. The results identify nature as the primary stakeholder and recommend strong local anchorage, the creation of diversified income sources, deliberate limitations on economic growth, the infusion of the business model with a systemic and ecosystem perspective, and the design of value flows beyond financial aspects. The discussion reflects on the most important results, provides practical implications and managerial guidelines, and suggests future research in the SSBM.     

基于改进遗传算法的生鲜加工配送中心连续选址模型

建立了生鲜加工配送中心选址连续模型，在引入监控算子的基础上，运用改进的遗传算法对模型进行求解。该模型和改进的遗传算法可有效的解决生鲜加工配送中心的选址问题。     

Functional laws of the iterated logarithm for small increments of empirical processes

Let F , denote the uniform empirical distribution based on the first n ≥ 1 observations from an i.i.d. sequence of uniform (0, 1) random variables. We describe the almost sure limiting behavior of the sets of increment functions {F_n(t + h_n.) - F_n(t): 0 ≤ t ≤ 1 - h_n}, when {h_n: n ≥ 1) is a nonincreasing sequence of constants such that nh_n /log n ← 0.     

The distribution of the relative arc density of a family of interval catch digraph based on uniform data

We study a family of interval catch digraph called proportional-edge proximity catch digraph (PCD) which is also a special type of intersection digraphs parameterized with an expansion and a centrality parameter. PCDs are random catch digraphs that have been developed recently and have applications in classification and spatial pattern analysis. We investigate a graph invariant of the PCDs called relative arc density. We demonstrate that relative arc density of PCDs is a U-statistic and using the central limit theory of U-statistics, we derive the (asymptotic) distribution of the relative arc density of proportional-edge PCD for uniform data in one dimension. We also determine the parameters for which the rate of convergence to asymptotic normality is fastest.     

On maximum likelihood prediction based on Type II doubly censored exponential data

In this paper, the maximum likelihood predictor (MLP) of the kth ordered observation, t _k, in a sample of size n from a two-parameter exponential distribution as well as the predictive maximum likelihood estimators (PMLE's) of the location and scale parameters, θ and β, based on the observed values t _r, …, t _s (1≤r≤s<k≤n), are obtained in closed forms, contrary to the belief they cannot be so expressed. When θ is known, however, the PMLE of β and MLP of t _k do not admit explicit expressions. It is shown here that they exist and are unique; sharp lower and upper bounds are also provided. The derived predictors and estimators are reasonable and also have good asymptotic properties. As applications, the total duration time in a life test and the failure time of a k-out-of-n system may be predicted. Finally, an illustrative example is included. Received: August 1999     

Enhancing employee and organizational performance through coaching based on mystery shopper feedback: A quasi‐experimental study

Based on reinforcement theory, a quasi‐experimental design was used to evaluate the effect of (a) feedback obtained from (b) a relatively neutral third party (namely, mystery shoppers) that was obtained on a (c) variable interval schedule for managers to use to (d) coach their employees. An interrupted time‐series design showed that both employee and organizational performance increased as a result of this intervention. Performance dropped when this intervention was cut back and, subsequently, discontinued. These results were replicated in two additional restaurants. © 2012 Wiley Periodicals, Inc.