Formulation of multiple-choice situations in linear programming models using binary coding matrices

In order to reduce the number of binary variables in a mixed integer LP model, the principle of binary coding is employed for the formulation of various multiple-choice situations. On the basis of a given coding matrix it is possible to find powerful constraints which define the binary coding procedure within an LP model. This procedure may be employed if the LP code available has not the potential to handle special ordered sets of type 1 algorithmically.     

The effect of sample size on the grey system model

Some forecasting models have been developed, each has its own application condition. The grey model is used for small sample forecasting, but until now there is no reasonable explanation for the reason why it is not used for large sample. Therefore, in this paper, matrix perturbation theory is employed to explain the reason. The results of practical numerical examples from previous works demonstrate that the small sample usually has more accuracy than the large sample when establishing grey model in theory. Furthermore, we used the grey model with small samples to analyse the trend of syphilis incidence in China.     

工程中的PGM(1,1)模型应用

采用PGM(1,1)模型替代GM(1,1)模型完成工程数据的拟合应用,通过实例数据较差比较证明PGM(1,1)模型具有更良好的短数据序列模拟性能.     

基于因子分析的元认知外语教学策略研究

从心理学、第二语言习得理论出发,研究了场独立与场依存认知风格的外语学习者特点,应用因子分析数学模型,进行了培养元认知策略意识及发展双重认知风格等教学策略的教学实验,仿真实验表明了该方法的实用性和有效性.     

Three dimensional finite element model to study heat flow in dermal regions of elliptical and tapered shape human limbs

In this paper a three-dimensional steady state model has been developed to study heat flow in dermal regions of tapered shape human limbs, which are elliptical in shape. The model incorporates the important biophysical parameters like blood mass flow rate, thermal conductivity and rate of metabolic heat generation. Appropriate boundary conditions have been framed using biophysical conditions. The finite element method has been employed using coaxial elliptical hexahedral elements to solve the problem. MATLAB 7.0 has been used to simulate the model and obtain numerical results.     

基于遗传算法的生产批量优化问题

本文针对生产费用、生产准备费用和库存费用综合指标最小的最优的能力约束生产批量问题,建立基于遗传算法的数学模型,通过模拟试验及实际问题的计算验证了算法的可行性。     

Machine-Shop Problems: An Operational Research Approach

Production planning and scheduling in a batch production environment presents management with many problems, ranging from long-term capital investment in machine tools to short-term batch sequencing. This paper, which is aimed at the production manager, introduces the general concept of model building and then discusses the more specific technique of computer simulation modelling. A simple example of the latter is used to illustrate the basic properties of such a model and then the actual model currently being used is described. The possible applications of such models are discussed and developed. Finally, a case study is presented which shows how the model has been employed in an actual production environment.     

Model selection of copulas: AIC versus a cross validation copula information criterion

Akaike Information Criterion (AIC) is frequently employed in the semiparametric setting of selection of copula models, even though as a model selection tool it was developed in a parametric setting. Recently a Copula Information Criterion (CIC) has been especially designed for copula model selection. In this paper we examine the two approaches and present a simulation study where the performance of a cross-validated version of CIC is compared with the AIC criterion. Only minor differences are observed.     

A higher order Markov model for analyzing covariate dependence

During the recent past, there has been a renewed interest in Markov chain for its attractive properties for analyzing real life data emerging from time series or longitudinal data in various fields. The models were proposed for fitting first or higher order Markov chains. However, there is a serious lack of realistic methods for linking covariate dependence with transition probabilities in order to analyze the factors associated with such transitions especially for higher order Markov chains. L.R. Muenz and L.V. Rubinstein [Markov models for covariate dependence of binary sequences, Biometrics 41 (1985) 91–101] employed logistic regression models to analyze the transition probabilities for a first order Markov model. The methodology is still far from generalization in terms of formulating a model for higher order Markov chains. In this study, it is aimed to provide a comprehensive covariate-dependent Markov model for higher order. The proposed model generalizes the estimation procedure for Markov models for any order. The proposed models and inference procedures are simple and the covariate dependence of the transition probabilities of any order can be examined without making the underlying model complex. An example from rainfall data is illustrated in this paper that shows the utility of the proposed model for analyzing complex real life problems. The application of the proposed method indicates that the higher order covariate dependent Markov models can be conveniently employed in a very useful manner and the results can provide in-depth insights to both the researchers and policymakers to resolve complex problems of underlying factors attributing to different types of transitions, reverse transitions and repeated transitions. The estimation and test procedures can be employed for any order of Markov model without making the theory and interpretation difficult for the common users.     

Thermal analysis of hot strip rolling using finite element and upper bound methods

Thermal analysis of hot rolling process has been studied in this work. A finite element method has been coupled with an upper bound solution assuming, triangular velocity field, to predict temperature field during hot strip rolling operation. To do so, an Upwind Petrov–Galerkin scheme together with isoparametric quadrilateral elements has been employed to solve the steady-state heat transfer equation. A comparison has been made between the published and the model predictions and a good agreement was observed showing the accuracy of the proposed model.     

需求分布未知且提前期可控的联合库存决策

在提前期内需求为自由分布且提前期依赖于订购批量和生产率的条件下,建立了同时考虑供需双方成本的联合库存决策模型,运用最小最大准则分析了模型最优解的存在性,设计了高效的最优解搜索算法.通过数值算例说明算法的有效性,分析了获取需求分布信息的代价与收益;并与供需独立的决策模型比较,表明了联合库存决策可以显著地降低供应链成本.     

A Model of the Dynamics of the Third World War — An Exercise in Technology Transfer

The paper discusses two scenarios for a Third World War in Europe, and argues that it is often convenient to supplement a scenario by a formal model. The problems of creating such a model are examined, and a model is formulated for land, air, and sea combat in Europe and the Atlantic, using the System Dynamics approach, which has not hitherto been widely employed for military analysis.The model confirms the results of the two scenarios, and its use for the analysis of alternative force configurations is illustrated. Some implications in the interpretation of Soviet military literature are discussed, and the paper ends with speculations on the role and value of such models.     

DEA中连续C~2R模型理论的研究

在DEA中的C2R模型的基础上,针对决策单元输入与输出为[0,1]区间上的连续函数,建立了在一个时间区间内评价决策单元间的相对有效性的连续C2R模型以及其对偶模型,同时给出了决策单元的效率定义和弱DEA有效、DEA有效的定义.同时得到了弱对偶定理,从而初步构建了连续C2R模型的理论体系.     

Application of homotopy-Padé technique in limit analysis of circular plates under arbitrary rotational symmetric loading using von-Mises yield criterion

The upper and lower bound principals of limit analysis are employed to determine the critical loading on solid circular plate with simply supported boundary conditions and subjected to any distributed loading with rotational symmetry. In this study, material behavior follows a rigid perfectly plastic model and yielding obeys the von-Mises criterion. Homotopy analysis method is employed to achieve the analytical solution to the high nonlinear ordinary differential equations governing the problem. This analytic solution has been obtained in terms of convergent series with easily computable terms. The results are verified with the Tresca yield criterion and presented as plots to show the reliability and simplicity of the method.     

Stability analysis of sampled-data fuzzy controller for nonlinear systems based on switching T–S fuzzy model

This paper investigates the system stability of a sampled-data fuzzy-model-based control system, formed by a nonlinear plant and a sampled-data fuzzy controller connected in a closed loop. The sampled-data fuzzy controller has an advantage that it can be implemented using a microcontroller or a digital computer to lower the implementation cost and time. However, discontinuity introduced by the sampling activity complicates the system dynamics and makes the stability analysis difficult compared with the pure continuous-time fuzzy control systems. Moreover, the favourable property of the continuous-time fuzzy control systems which is able to relax the stability analysis result vanishes in the sampled-data fuzzy control systems. A Lyapunov-based approach is employed to derive the LMI-based stability conditions to guarantee the system stability. To facilitate the stability analysis, a switching fuzzy model consisting of some local fuzzy models is employed to represent the nonlinear plant to be controlled. The comparatively less strong nonlinearity of each local fuzzy model eases the satisfaction of the stability conditions. Furthermore, membership functions of both fuzzy model and sampled-data fuzzy controller are considered to alleviate the conservativeness of the stability analysis result. A simulation example is given to illustrate the merits of the proposed approach.     

Dynamic modeling of a high-precision self-moving stage with various frictional models

The piezoelectric actuator (PA) has been used for precision positioning from micro-meter down to nano-meter scale. In this paper, the frictional force is first described by the LuGre model and Leuven model, which allow accurate dynamic modeling both in the sliding and the presliding regimes without using switching functions. The hysteresis frictional parameters controlling the restoring force amplitude and the shape of hysteresis loop are investigated. Sequentially, the two frictional models are employed in the self-moving stage for high-precision positioning under different applied voltages. From the numerical results in the pre-sliding regime, it is shown that the hysteresis frictional force has critical influence on the final position of the micro- and nano-meter positioning.     

Forecasting urban traffic flow by SVR with continuous ACO

Accurate forecasting of inter-urban traffic flow has been one of the most important issues globally in the research on road traffic congestion. Because the information of inter-urban traffic presents a challenging situation, the traffic flow forecasting involves a rather complex nonlinear data pattern. In the recent years, the support vector regression model (SVR) has been widely used to solve nonlinear regression and time series problems. This investigation presents a short-term traffic forecasting model which combines the support vector regression model with continuous ant colony optimization algorithms (SVRCACO) to forecast inter-urban traffic flow. Additionally, a numerical example of traffic flow values from northern Taiwan is employed to elucidate the forecasting performance of the proposed SVRCACO model. The forecasting results indicate that the proposed model yields more accurate forecasting results than the seasonal autoregressive integrated moving average (SARIMA) time series model. Therefore, the SVRCACO model is a promising alternative for forecasting traffic flow.     

The Asymptotic Distribution of REML Estimators

Restricted maximum likelihood (REML) estimation is a method employed to estimate variance-covariance parameters from data that follow a Gaussian linear model. In applications, it has either been conjectured or assumed that REML estimators are asymptotically Gaussian with zero mean and variance matrix equal to the inverse of the restricted information matrix. In this article, we give conditions under which the conjecture is true and apply our results to variance-components models. An important application of variance components is to census undercount; a simulation is carried out to verify REML′s properties for a typical census undercount model.     

Influence of turbulence model constants and boundary conditions on the computed hydrodynamic variables in gas-stirred reactors

A finite difference procedure has been employed to obtain numerical predictions of recirculating flows in gas-stirred reactors. Sensitivity of alternative boundary conditions at gas-liquid interface as well as empirical constants of the turbulence model on the predicted flow field have been investigated.