Approximate Calculation of Optimal Inspection Times

This paper considers an inspection model whose failure is known only through checking. A new approximate calculation of optimal checking procedures is suggested. This computes successive check times backwards, supposing that an appropriate check time is previously given after a large number of checks. This policy is simple to compute and compares fairly well with the optimal policy.     

An improved class of estimators of a finite population quantile in sample surveys

This work proposes a general class of estimators for a finite population quantile using auxiliary information. This information is provided by the population means of auxiliary variables. The optimum estimator in this class is derived. This result is supported with a numerical example.     

投资环境地区横向比较

本文以各地区经济数据为基础,通过建立统计分析的数学模型,给出了度量、评测投资环境的客观标准,并应该标准对几个典型城投资环境进行评价和分类,从一个新的角度,就客观、定量的研究投资环境进行了探索.     

Production control of an unreliable manufacturing system under the assumption of no backlog

This paper deals with an unreliable manufacturing system in which no backlog is allowed. The hedging point policy is used to control production. This paper's objective is to find the optimum hedging point so as to minimize the average inventory cost. Firstly, for a tentative hedging point, we derive the limiting distribution of the inventory level. This derivation is accomplished by comparison between this system and a finite storage-production system. Based on it we calculate the average inventory cost and find the optimum hedging point.This research was supported in part by the National Natural Science Foundation of China. Bin Liu was partially supported by ITDC, contract No. 105-82150.     

A combinatorial generalization of polytopes

Primoids and duoids are collections of subsets of a fixed finite set with a natural generalization of a pivoting property of convex polytopes. This structure is precisely what is necessary for the application of complementary pivoting algorithms. This paper investigates the combinatorial structure of primoids and duoids, showing them to form the circuits and cocircuits of a binary matroid. This matroid is then compared with the simplicial geometries of Crapo and Rota.     

Tariff structure of Japanese electric power companies: An empirical analysis using DEA

This research explores a Marginal Cost (MC)-based pricing system, using Data Envelopment Analysis (DEA). This DEA technique is widely applied for performance analysis and efficiency measurement in public and private sectors. This article does not follow such a previous research direction, rather directing itself towards the new measurement of MC and Ramsey prices of multiple electric power services. As an important case study, this research applies the proposed DEA approach to examine how much the current tariffs of Japanese electric power services deviate from these MC and Ramsey prices. This type of research has never been explored in Japan, even though such a research effort is needed by many policy makers and consumers. It is hoped that our empirical findings can serve as a policy-making basis for guiding the Japanese electric power industry. This study believes that this Japanese experience is useful for other nations, such as Asia-Pacific countries, where many public industries are regulated by their governments.     

The assessment of retailing efficiency using Network Data Envelopment Analysis

This paper describes a method for the assessment of retail store performance based on Data Envelopment Analysis (DEA). The assessment considers the stores as complex organizations that aggregate several subunits, corresponding to sections with management autonomy. This structure motivated an analysis at two different levels: the section level and the store level. The performance assessment of the sections envolves a comparison among similar sections located in different stores, and evaluates efficiency spread. This is followed by an analysis at the store level to define targets for the sections. This analysis takes into account the interdependencies of the sections composing a store, as they share limited resources such as the floor area. This is achieved using a Network DEA model, which determines the maximum store sales allowing for reallocations of area among the sections within a store. The method developed is illustrated using a case study consisting of a Portuguese chain of supermarkets.     

复合型脆断的周向应力应变乘积判据

本文提出一个新的复合型脆断判据,即周向应力应变乘积判据,该判据与实验数据非常一致.     

An Inventory Model with an Inventory-Level-Dependent Demand Rate and Relaxed Terminal Conditions

This paper investigates an inventory system with an inventory-level-dependent demand rate followed by a constant demand rate. The analysis previously conducted on this model imposed a terminal condition of zero inventory at the end of the order cycle. This condition is not warranted for systems with inventory-level-dependent demand rates, even for deterministic models. This paper relaxes this restriction, and an appropriate model is developed.     

Optimal prevention and prudence in a two-period model

This work shows that, in a two-period framework, prudence has a positive effect on optimal prevention. This conclusion is the opposite to that obtained in a one-period framework [Eeckhoudt L., Gollier C., 2005. The impact of prudence on optimal prevention. Economic Theory 26, 989–994]. This is due to the opposite effect of prevention on wealth in the period where the risk occurs.     

Criteria sensitivity analysis: a new approach to parameter sensitivity

The problem of parameter sensitivity is not well defined. This paper aims to make it well defined. This is done by requiring the modeller to provide a performance indicator l(X,t,β) which is a measure of how the behaviour of the system is to be judged. This forces the modeller to be precise about what he/she regards as acceptable behaviour. Mathematically we define behaviour to be acceptable at β if l >0 for that β, and we define the system as sensitive if the set of acceptable β's is small. The analysis which is required is termed criteria sensitivity analysis. This method is applicable to many different kinds of models. The basic ideas of criteria sensitivity analysis are presented here. A static model is used to demonstrate major points. The power of this new approach is illustrated by an application to a dynamic model.     

The Weber problem with regional demand

This paper is devoted to the study of the Regional Weber Problem, an extension of the Weber problem which allows the demand not be concentrated onto a finite set of points.The most serious drawback of this formulation, from a resolution viewpoint, is the high computational cost involved in the evaluation of the objective function. A new approach is proposed, which requires a low amount of computation and where it is possible to control the error on the approximation.This approximation suggests a new methodology to solve the problem. This methodology is compared with the existing ones, showing its relevance from a practical point of view.     

Towards an Automated Reduction Method for Polynomial ODE Models of Biochemical Reaction Systems

This paper presents the first version of an algorithmic scheme dedicated to the model reduction problem, in the context of polynomial ODE models derived from generalized chemical reaction systems. This scheme, which relies on computer algebra, is implemented within a new MAPLE package. It is applied over an example. The qualitative analysis of the reduced model is afterwards completely carried out, proving the practical relevance of our methods. We would like to thank Marc Lefranc and Pierre-Emmanuel Morant. This work was partially supported by the PPF Bioinfo of the University Lille I.     

On optimal control problems with state constraints

This paper is concerned with necessary conditions for a general optimal control problem developed by Russak and Tan. It is shown that, in most cases, a further relation between the multipliers holds. This result is of interest in particular for the investigation of perturbations of the state constraint.     

构造正交小波基的基本方法之一

本文不仅给出一种构造局部性好的正交小波基的方法,并且给出了构造各种优良性质的正交小波基的一般思想方法。其特点:使构造的小波母函数有具体的表达式,既有较好的光滑性,又有很好的局部性,并且其收敛速度与│t│~（-（3k 1））同阶,其中k为任意自然数。这种方法不需要每次重新构造函数,只要改变k的值,就能满足不同实际问题的需要。     

An active set strategy to generate quadrilateral grids

We consider the problem of the generation of quadrilateral grids on planar domains. This problem is numerically solved by a two phases method: an iterative procedure based on the well-known variational approach, and an active set procedure to obtain unfolded quadrilaterals. This second phase is performed only when it is really necessary, in fact the first phase alone gives satisfactory results on a large number of domains. This two phases approach provides a robust method with low computational cost. Numerical experiments show that this method is able to generate unfolded grids also on complex domains.     

Optimal control with a cost on changing control

In this paper, we consider a class of optimal control problems in which the cost functional is the sum of the terminal cost, the integral cost, and the full variation of control. The term involving the full variation of control is to measure the changes on the control action. A computational method based on the control parametrization technique is developed for solving this class of optimal control problems. This computational method is supported by a convergence analysis. For illustration, two numerical examples are solved using the proposed method.This project was partially supported by an Australian Research Grant.This paper is dedicated to Professor L. Cesari on the occasion of his 80th birthday.     

Higher Coverings of Racks and Quandles—Part II

Applied Categorical Structures - This article is the second part of a series of three articles, in which we develop a higher covering theory of racks and quandles. This project is rooted in...     

The generalized Gompertz distribution

This paper deals with a new generalization of the exponential, Gompertz, and generalized exponential distributions. This distribution is called the generalized Gompertz distribution (GGD). The main advantage of this new distribution is that it has increasing or constant or decreasing or bathtub curve failure rate depending upon the shape parameter. This property makes GGD is very useful in survival analysis. Some statistical properties such as moments, mode, and quantiles are derived. The failure rate function is also derived. The maximum likelihood estimators of the parameters are derived using a simulations study. Real data set is used to determine whether the GGD is better than other well-known distributions in modeling lifetime data or not.     

Lotka-Volterra模型参数的灰色估计法及其应用

基于灰色直接建模法,提出了估计Lotka-Volterra模型参数的一种方法,较好的反映了相互影响的两个变量之间的互惠、竞争等关系,为定性预测分析提供了实证支持,并得到了定量预测的结果.实例说明本模型的有效性和适用性.并证明了数乘交换不影响原始序列的模拟精度,为解决灰色预测模型的病态性提供了思路.