A Marketing Model for a Price-Promoted Consumer Good: A Case Study

The paper describes a simple competitive marketing model based on regression analysis of historical data. It outlines the analysis stages, and then describes the practical implementation of the results. One section considers the way results from the model were analysed to indicate the best competitive strategy.     

用力学子单元模型求解与时间有关的各向异性塑性问题

本文介绍了用力学子单元模型摹拟金属各向异性弹-塑性平面应力行为的做法,模型引用的纵向与横向应力-应变曲线,是用几个光滑的短线段来表达的;但为简化起见,把它们当作分段线性线段。模型已纳入粘塑性杂交应力有限元分析程序。     

Numerical methods for the Lotka–McKendrick's equation

The Lotka–McKendrick's model is a well-known model which describes the evolution in time of the age structure of a population. In this paper we consider this linear model and discuss a range of methods for its numerical solution. We take advantage of different analytical approaches to the system, to design different numerical methods and compare them with already existing algorithms. In particular we set up some algorithms inspired by the approach based on Volterra integral equations and we also consider a direct approach based on the nonlinear system that describes the evolution of the age profile of the population.     

Determination of Stock for Sales Promotions

This paper describes the solution of the practical problems encountered by a Company when a product is made and sold for a limited promotional period only. The production and inventory control aspects are considered and a system aimed at the reduction of obsolescence costs is described which is based on a model of the demand pattern which uses a Gompertz exponential growth curve. Under pressure for an early improvement from the organisation, a system based on an empirical model was implemented, as an interim measure, which achieved a considerable improvement in performance. The Gompertz model has now been put into operation and the results of a simulation model are presented indicating that further improvements can be achieved.     

Model and algorithm of the conceptual scheme formation for knowledge domain in distance learning

The article describes a knowledge model, oriented to the asynchronous mode of distance learning. The formalization of the knowledge model for a given domain, the operations on the knowledge and the algorithm of the knowledge model creation are submitted. All received decisions can be realized in a program environment compatible with the SCORM standard. The described methodology, based on a generalized knowledge model, enables to develop a distance learning course mainly for the fundamental knowledge. In this paper we describe the methodology and illustrate its use through a project to develop a distance learning course for a queuing system. Moreover, a practical application is proposed based on the eQuality project.     

An Efficient Method for the Multi-Depot Location—Allocation Problem

This paper describes a procedure based on large-scale nonlinear programming for solving the multidepot location-allocation problem. Both the location of depots and the allocation of customers are allowed to vary simultaneously. Numerical experience on a 5 x 50 and a 10 x 50 example is described, and possible extensions to the basic model are discussed.     

SOS: A Quantile Estimation Procedure for Dynamic Lot-sizing Problems

This paper reviews some of the current approaches available for computing the demand quantiles required to plan the procurement of items with stochastic non-stationary demands. The paper first describes the stochastic single-item lot-sizing problem considered and then presents a practical solution approach based on a dynamic lot-sizing model. Three methods available to compute demand quantiles are then reviewed and a new procedure based on smoothed order statistics (SOS) is proposed. Finally, the behaviour of these estimation methods, when used to solve single-item lot-sizing problems with non-stationary stochastic demands, is studied by simulation.     

Probabilistic Model for the Growth of Thesauri

The paper deals with a mathematical model which describes how the collection of key phrases (and key words) evolves as a field of science develops. The experimental material is based on statistical observations on the sets of key phrases which have been assigned to papers in representative major journals in the field in question. Asymptotic properties of the model are considered, as well as estimators for the parameters of the model with particular emphasis on estimators that can indicate at what stage a collection of key phrases can be assumed as complete for the field in question at a given moment in time.     

Fuzzy systems based on component software

This paper describes hierarchical modeling of fuzzy logic concepts that has been used within the recently developed model of intelligent systems, called OBOA. The model is based on a multilevel, hierarchical, general object-oriented approach. Current methods and software design and development tools for intelligent systems are usually difficult to extend, and it is not easy to reuse their components in developing intelligent systems. The OBOA model tries to reduce these deficiencies. The model starts with a well-founded software engineering principle, making clear distinction between generic, low-level intelligent software components, and domain-dependent, high-level components of an intelligent system. This paper concentrates on modeling and implementation of fuzzy logic concepts within the hierarchical levels of the OBOA model. The fuzzy components described are extensible and adjustable. As an illustration of how these components are used in practice, a practical design example from the domain of medical diagnosis is shown. The paper also suggests some steps towards future design of fuzzy components and tools for intelligent systems.     

Dynastic cycle: a generic structure describing resource allocation in political economies,markets and firms

A generic system embodies basic principles and insights that are common to a set of diverse cases and situations. This paper presents a new generic system that we name the dynastic cycle structure. It is based on a stylized model of events from the Chinese history. The model describes resource allocation between social, asocial and control uses in political economies, markets and firms that experience cyclical behaviour and homeostasis symbolizing low levels of performance. Numerical simulations with the model are used to understand the internal dynamics and to test several policy scenarios.     

Modelling of psychological behavior on the basis of ultrametric mental space: Encoding of categories by balls

In this paper we present a model of processing of mental information based on encoding by points of ultrametric space. Basic mental entities categories are encoded by ultrametric balls. Our model describes processes which take place in subconsciousness. It seems that ultrametric is a right tool for modeling of unconscious mental processes. Properties of ultrametric balls match well properties of unconscious representation of information which have been discussed in psychology.     

An integrated queuing and multi-objective bed allocation model with application to a hospital in China

In this paper, a multi-objective decision aiding model is introduced for allocation of beds in a hospital. The model is based on queuing theory and goal programming (GP). Queuing theory is used to obtain some essential characteristics of access to various departments (or specialities) within the hospital. Results from the queuing models are used to construct a multi-objective decision aiding model within a GP framework, taking account of targets and objectives related to customer service and profits from the hospital manager and all department heads. The paper describes an application of the model, dealing with a public hospital in China that had serious problems with loss of potential patients in some departments and a waste of hospital beds in others. The performance of the model and implications for hospital management are presented.     

Tanker chartering: A system dynamics case study

This paper describes a practical system dynamics case study. It attempts to show how this OR technique can be applied to a practical problem and the results which it can, and cannot, be expected to give.Although the paper is based on a real project, the details have been altered for commercial secrecy, and the emphasis in this paper is, for the same reason, rather different from that of the original work. The aim of the paper is, therefore, to give enough of a “real” background to contrast the industrial application of SD with some of its other applications.For the sake of reasonable brevity, the emphasis in this paper is on the managerial viewpoint, and the extent to which an SD model provides helpful answers to managerial questions. The model paper is described only briefly as full details, and a model listing are given by Coyle. Some other aspects of the system are treated by Winch.     

Investigation of inverse simulation for design of feedforward controllers

This paper describes the use of inverse simulation to develop feedforward controllers for model-based output-tracking control system structures, thus avoiding the more complicated techniques of model inversion. Similarities and shortcomings of the inverse simulation and model inversion approaches are explored. It is found that, with suitable values of discretized time interval, the method based on inverse simulation may be preferable for minimum-phase systems. Depending upon zero redistribution within the process of inverse simulation, non-minimum-phase problems for linear systems can also be handled. The conclusions are demonstrated using a non-linear HS125 aircraft model, a linearised Lynx helicopter model and a container ship model for ship steering control and roll stabilization.     

On structures in instability zones

Two mathematical crystallization models describing structure formations in instability zones are proposed and justified. The first model, based on a phase field system, describes crystallization processes in binary alloys. The second model, based on a modified Biot model of a porous medium and the convective Cahn–Hilliard model, governs oriented crystallization. Physical interpretation and numerical analysis are discussed. Bibliography: 23 titles. Illustration: 5 figures.     

Multivariate spatial regression models

This paper describes the inference procedures required to perform Bayesian inference to some multivariate econometric models. These models have a spatial component built into commonly used multivariate models. In particular, the common component models are addressed and extended to accommodate for spatial dependence. Inference procedures are based on a variety of simulation-based schemes designed to obtain samples from the posterior distribution of model parameters. They are also used to provide a basis to forecast new observations.     

Numerical resolution for a compressible two-phase flow model based on the theory of thermodynamically compatible systems

This paper is concerned with the numerical solution of the equations governing two-phase gas-solid mixture in the framework of thermodynamically compatible systems theory. The equations constitute a non-homogeneous system of nonlinear hyperbolic conservation laws. A total variation diminishing (TVD) slope limiter centre (SLIC) numerical scheme, based on the splitting approach, is presented and applied for the solution of the initial-boundary value problem for the equations. The model equations and the numerical methods are systematically assessed through a series of numerical test cases. Strong numerical evidence shows that the model and the methods are accurate, robust and conservative. The model correctly describes the formations of shocks and rarefactions in two-phase gas-solid flow.     

Linear Programming Applied to Production Planning—A Case Study

This paper describes the installation of a planning system in a food factory, based on the use of linear programming. Owing to the seasonal nature of many of the parameters, it is essential to use a multi-period model.The formulation of the L.P. model is discussed in some detail. This includes a considerable number of restrictions of a commercial rather than a physical nature.A particular aspect of the application is the way in which the model is used, in slightly different forms, at the three distinct stages of the planning process.Some of the practical difficulties encountered in implementing the solution are discussed.     

A simple graphical decision aid for the placement of elderly people in long-term care

This paper describes the construction of a graphical decision tool to aid placement decisions of a multidisciplinary review panel for admissions to long-term care in a London borough in the UK. First we construct a prediction model of placement decisions based on an applicant's attributes. Using data from the London borough, a composite model comprising syndromic decision rules followed by a two-stage hierarchical logistic regression model is proposed. The model proved to be robust in differentiating cases needing residential home care and nursing home care. Placement outcomes generated by the model are then represented graphically on a triangle plot. This approach could potentially be used as a decision support tool by managers of long-term care for continuous monitoring and assessment of the appropriateness of placements with respect to residents’ needs.