An Aggregate Production Planning Model Incorporating Dynamic Productivity: Part II. Solution Methodology and Analysis

In Part I in a previous issue, the authors developed a procedure for incorporating dynamic productivity considerations into aggregate planning models. However, the dynamic cost functions of these models result in heterogeneous decision systems which are difficult to solve. In this article a solution methodology is discussed that was developed for dynamic aggregate planning models. In addition, the results from using a dynamic productivity aggregate planning model are analyzed. It is concluded that dynamic productivity can be significant; incorporating these considerations into a model can provide more realistic results.     

一类劳动力受限的模糊集约生产计划

通过对模糊需求量和模糊等式的描述，建立了模糊环境下具有劳动力水平约束的集约生产计划模型，利用区间数规划方法将其进一步转化为清晰型的一般参数规划问题来求解。决策者可以根据自已的主观判断和客观情况，对约束条件水平做出不同的估计，从而得到在相应情况下的满意解，使决策过程更具柔性。     

Five Approaches to Aggregate Production Planning

Production scheduling problems are reviewed briefly and the smoothing problem is defined as planning the aggregate production level for each period in a given horizon to meet forecast demand. Five approaches to the problem are reviewed: (1) the HMMS linear decision rule for production and employment; (2) the DE rule for production, in which time lag is incorporated; (3) the management coefficients method; (4) the use of LP models; (5) the production switching method. The assumptions and objectives inherent in each approach are discussed and certain shortcomings are indicated.     

Practical Productivity Analysis for Management: Part I. Analytic Framework

In this first of two papers, the nature of productivity changes and their measurement are examined. Various widespread misconceptions of such changes and of the means of measurement are discussed. The multiple requirements of a practical productivity analysis system are outlined, and an analytic framework which meets these requirements is presented. Samples are provided of empirical findings which have resulted from the use of this framework. The second paper will provide a discussion of the determinants of change in productivity relationships and problems encountered and experiments used in productivity measurement. A guide to analysis and interpretation is provided.     

A New Approach to Aggregate Production Planning

This paper proposes a new framework for modelling aggregate production planning problems in which emphasis is placed upon offering the user the flexibility to specify (1) the production options to be employed, (2) the relationships among those options (some of which may be highly situation-specific), and (3) the relevant cost structure. The procedure offered for solving the problem embeds Bowmann's “transportation” approach to aggregate production planning into a large mixed integer programming framework.     

区间数多产品多计划期生产计划问题的目标规划求解方法

针对多目标、多产品、多计划期和需求、生产费用、生产能力等参数不确定的综合生产计划问题进行了研究。引入区间数描述生产计划问题中存在的不确定性,建立了以生产成本最小和设备利用率最大为优化目标的目标规划模型。为求解模型,运用区间规划理论和基于区间序关系的可能度定义,实现了区间目标规划模型的清晰等价转换,并采用Lingo软件完成模型求解。该方法解决了传统不确定优化方法在获取概率分布和模糊隶属度函数较为困难的不足,能根据决策者的偏好以交互方式分析出不同置信水平对目标的影响,为决策者在不确定环境下进行生产计划决策提供理论依据。最后,通过算例说明方法的有效性和灵活性。     

An elasticity microscope. Part I: Methods

An elasticity microscope images tissue stiffness at fine resolution. Possible applications include dermatology, ophthalmology, pathology, and tissue engineering. In addition, if the resolution approaches cellular dimensions, then this system may be very useful in understanding tissue micromorphology. Elasticity images can be reconstructed from displacement and strain fields measured throughout the specimen during controlled external loading. High frequency ultrasound is used to obtain these images by tracking coherent speckle motion during deformation. In this paper, methods are presented to track speckle in two dimensions with near unity correlation coefficients using a high frequency, single element focused transducer. These techniques include improved means for speckle tracking. Procedures to control boundary conditions for consistent specimen deformation and scanning techniques required to obtain a plane-strain state in the imaging plane are also discussed. To test these methods, a 50 MHz elasticity microscope was constructed     

随机综合生产计划模型及其求解研究

制订一个有效、可行的综合生产计划,必须考虑各种随机因素的影响。本文在前人工作的基础上,提出了一种改进的随机综合生产计划模型,并探讨了采用数学分析和蒙特卡罗模拟相结合的模型求解方法。     

Dynamic crack propagation in steel line pipes. Part I: Experimental investigation

An experimental-theoretical research project on dynamic crack propagation on steel line pipes intended for arctic service was developed. The aim of this study is to characterize the dynamic material behavior, to propose line pipe qualification tests, and to identify the variables that govern the dynamic fracture process and their relationships. The first part of this research involves the experimental work and outlines a practical test to assess fitness for service of arctic pipelines. Burst tests of line pipes samples at low temperature were carried out and crack extension vs. time was measured. The axial crack fracture mechanism was quasi-cleavage in the center of the pipe wall with lateral shear lips. A pressure range for LBB (leak before break) condition was obtained. In Part II of this research a new model for the assessment of the dynamic material properties from the analysis of test results obtained in Part I is developed.     

Goal Programming Approaches to Solving Linear Decision Rule Based Aggregate Production Planning Models

This paper reviews several goal programming extensions to the Linear Decision Rule Formulation of the Aggregate Production Planning Problem, and presents an extension using Polynomial Goal Programming. Employing a well known problem as a point of reference, the solution of the various model formulations is illustrated using commercially available mathematical programming software.     

A novel planar mesh-type microelectromagnetic sensor. Part I. Model formulation

The formulation of analytical model and results for a novel planar mesh-type microelectromagnetic sensor for multiple applications has been reported in this paper. The sensor can be used for the estimation of near-surface properties (such as conductivity, permeability, permittivity, liftoff, etc.) of materials, inspecting the quality of electroplated materials, and has the potential of possible inspection of dairy foods, such as butter, cheese, curds, yogurts, etc. The results obtained from the analytical model for the calculation of the transfer impedance of the sensors has been discussed. The transfer impedance is used for the quality inspection of the system under test in an indirect way.     

An Overview of Complexity Theory in Discrete Optimizations: Part I. Concepts

Over the past decade, complexity theory has emerged from a branch of computer science almost unknown to the operations research community into a topic of widespread interest and research. The goals of the theory are to broadly classify problems and algorithms according to their convenience for solution by digital computers. Very considerable progress has been achieved, but some of the concepts in the theory are so subtle that their implications are as often misunderstood as grasped correctly. In this and the succeeding paper, we will present an elementary tutorial review of the important concepts and results in complexity theory. Emphasis is placed on constructs and implications for persons interested in discrete optimization—especially scheduling theory. The present Part I develops background concepts and definitions. Part II (in the June 1982 TRANSACTIONS) will cover results and implications.     

Practical Productivity Analysis for Management: Part II. Measurement and Interpretation

In Part I, a framework for the analysis and measurement of productivity was provided, along with a sample of some empirical findings obtained with this framework. In this paper, the array of factors which must be examined in order to account for the observed findings is reviewed. Problems encountered in the application of this framework in different kinds of plants are discussed, including problems with the development of managerial ability to interpret the results of the analysis.     

炭黑填充型导电复合材料的聚集体结构模型

分析了炭黑填充聚合物导电复合材料的非线性导电行为和机理,基于有效介质理论及以炭黑聚集体的等效球形单元为基本单元,建立了描述其非线性导电行为的聚集体结构模型。进而推导出复合体系导电率与炭黑体积分数之间的关系式及其逾渗阈值的计算式,克服了有效介质理论只能得到逾渗阈值为1/3而不能解释低于1/3的逾渗阈值的不足。应用这些表达式预测了导电复合体系的导电率和逾渗阈值,并与实验结果进行了比较,结果表明:预测值与实验结果有较好的一致性。     

Hypoelastic soft tissues. Part I: Theory

Refinements are made to an existing hypoelastic theory developed by Freed [18, 19] for the purpose of modeling the passive response of soft, fibrous, biological tissues. Oldroyd’s [27] operators for convected differentiation and integration, which he derived from the tensor transformation law, are re-derived here from an integral equation defined in the polar configuration. Fields that obey these convected polar operators are said to be viable tensor fields, from which a new definition for strain and its rate are obtained and applied to a hypoelastic theory for tissue. Anisotropy is addressed through a material tensor, from which viable tensor fields describing fiber strain and strain rate are constructed. Material anisotropy and material constitution are handled separately for maximum flexibility. Isochoric hypoelastic models for isotropic, anisotropic, and fiber/matrix composite materials are derived. A material function is introduced to address special attributes that biological fibers impart on tissue behavior, four of which are proposed that represent various ways through which the fiber constituents might be described. Application to in-plane biaxial deformation is the focus of part II of this paper [23].     

生产计划制定过程的分析及数学建模

通过对某企业中MTO和ATO混合生产方式的分析，建立了描述其生产计划制定过程的数学模型。生产计划与调度是整个生产管理过程的核心，也是ERP系统中的核心模块。该项研究为企业生产管理规范了流程，为实施ERP系统提供了理论和逻辑基础。     

多产品生产计划与设备维修整合优化模型

将有限长度的生产计划期,合理地分成若干个等时间长度的时段。基于给定的各时段每种产品的需求量以及延迟时间理论,建立数学规划模型,同时优化设备维修和生产计划问题,即确定生产计划期内对设备进行预防性维修的最优时间间隔以及各种产品在每一个时段的最优生产批量大小,使得生产计划期内的产品生产费用、库存费用、延迟交货费用、设备调整费用以及设备维修费用的总和达到最小。并运用数值案例对所建立的模型进行了计算分析。     

A Transportation Model for Production Planning with Convex Costs

This expository note reviews a somewhat neglected, but elementary, method for reformulating linear and convex cost production planning problems with inventory and back-order constraints as un-capacitated transportation-type problems.     

Dynamic behavior of a direct expansion evaporator under frosting condition. Part I. Distributed model

A general distributed model with two-phase flow for refrigerant coupled with a frost model is developed for studying the dynamic behavior of an evaporator. The equations are derived in non-steady-state manner for the refrigerant and a quasi-steady state model with permeation for the frost. The complex flow and geometry of the finned tube evaporator lead to uneven wall and air temperature distributions, which in turn affect the rate of frost growth and densification along the coil depth. Results include frost accumulation and its effect on energy transfer, air off-coil temperature, refrigerant liquid dry-out position and propagation of frost formation along the coil.