An economic evaluation model of product mix flexibility

This paper develops a product mix flexibility model comprising labor flexibility, machine flexibility, routing flexibility, and information technology, with the product mix flexibility measured by an economic index. Outputs from the model can be useful in making suitable production decisions to produce multiple products in an uncertain environment. Example solutions are given. How the product mix flexibility is affected by flexibility factors is discussed, and the results show that the bottleneck plays the most important role. This paper can help economic evaluation when product mix flexibility and the factors affecting flexibility are to be improved. It can also assist in making enterprise flexibility promotion decisions.     

Concurrent consideration of product design,process planning and production planning activities

In manufacturing engineering, product design, process planning and production planning activities are often considered independently. However, in order to effectively respond to changes in business situations, such as changes in demand forecast, product mix and technology, it is desirable to consider them concurrently. For this purpose, a large-scale linear programming model has been developed. The model considers minimization of the sum of processing cost, late shipment cost and inventory holding cost as the objective, and concurrently selects product designs, and generates process plans and production plans. The number of columns in the formulation can be large and, hence, an efficient column generation scheme is developed to solve the model. The model and solution procedure are illustrated with examples.     

Engineering change: A theoretical assessment and a case study

The competitive playground where nowadays firms struggle to survive has rapidly become unforeseeable: product life cycle has shrunk, becoming even shorter than in the past, and world-wide market is suffering for a strong customer differentiation which led to an increasingly wide product mix. In this industrial environment, the engineering change process is getting more and more attention throughout the branches of industry, as it appears as a critical process which seeps into the operations management core, thus influencing the overall firm's performances. A brief state-of-the-art in the area of engineering change is firstly presented. Then a proposal of classification and a new methodology for an effective engineering change process management are suggested. The new proposed methodology has been successfully applied to a real-life manufacturing system and the related case study is reported at the end of the paper.     

Processing in a multi-machine batch manufacturing system with sequence dependent cost

Many workcells in batch manufacturing systems are populated with multiple, nonidentical machines that perform similar tasks. Because of the size of a batch when a job arrives, it may be uneconomical to set up two or more machines to process the same job simultaneously. An economic decision has to be made as regards which machine in the cell to assign the job. Likewise, many multi-operation jobs can be processed using one of several feasible operation sequences that may lead to different total manufacturing costs. The cost differences are the result of several factors, among which are processing time and cost dependencies between operations, fixturing requirements, and material handling requirements. When the workcell machine selection decision is considered along with the operation sequencing decision, determination of the best machine in a cell and the best operation sequence for the batch is a non-trivial task. In this paper, we address the problem of selecting the best machine within a cell and the best operation sequence for a batch when operation cost is machine and sequence dependent. The problem is modeled mathematically and solved using a heuristic algorithm. The performance of the algorithm is compared with that of an exact solution procedure.     

A framework for production control in health care organizations

The paper presents a hierarchical framework for production control of hospitals which deals with the balance between service and efficiency, at all levels of planning and control. The framework is based on an analysis of the design requirements for hospital production control systems. These design requirements are translated into the control functions at different levels of planning required for hospital production control. The framework consists of five levels of planning and control: patient planning and control, patient group planning and control, resources planning and control, patient volumes planning and control and strategic planning, though this last level does not make part of production control as such. Each of the levels of the framework is further elaborated in terms of the decisions made regarding patient flows and resources, and the co-ordination of the different planning levels. Implications of the framework are discussed by describing some points where current practice deviates from assumptions made in our approach. Recommendations for future research and development of the planning framework are formulated.     

面向安全硬约束的煤矿生产物流效率优化研究

在保证安全生产前提下实现效率最大化是煤炭生产企业亟需解决的现实问题。本文结合煤矿生产物流系统的复杂性特征,首先从人员素质、机械装备、环境改善、安全管理、应急救援等方面确定了煤矿生产物流的安全投入指标,运用响应曲面法分析了安全指标与安全水平间的作用关系,确定了煤矿生产物流安全硬约束条件;然后以效率最大化为目标函数、安全目标和资源投入为约束条件,构建了煤矿生产物流效率优化模型;最后通过实例验证了模型的有效性及适用性,为安全生产前提下实现资源优化配置,提高煤矿生产物流效率提供了科学依据。     

CAPACITATED REMANUFACTURING WITH SERVICE LEVEL CONSTRAINTS*

This research examines production planning and control for a remanufacturer that can sell returned items on a graded as‐is basis or remanufacture the returned items. Using a GI/G/1 queuing network, we model the firms decision to remanufacture an optimal product mix over the long run that maximizes profits while maintaining a desired service level. We further use simulation to explore dispatching heuristics that can be used at the shop‐floor level to achieve the desired optimal product mix, while meeting the service level constraint. Our research is grounded in actual practice and the results provide key insights into the decision‐making process required to maximize profits and minimize average flow times for remanufactured products.     

How car dealers adjust prices to reach the product efficiency frontier in the Spanish automobile market

This paper investigates the relationship between the dynamics of price discounts at the dealership level and product efficiency in the Spanish auto market. Using data envelopment analysis (DEA), product efficiency scores are estimated for 2092 different vehicles commercialized during 2010, using an innovative database that accounts for more than 75 technical attributes of each model. By alternating official and discounted prices on the DEA specification, we are able to propose a measure of competitive improvement in the retailing stage. We also introduce a decomposition of this measure into two indices that account for the “commercial effort” made by the dealer and the “intensification of competition” that results from the discounting efforts of the other dealers. Finally, we explore the importance of a number of drivers of dealer discounts. As expected, the results confirm the existence of an inverse relationship between product efficiency and dealer discount. Also as expected, discounts are significantly larger for generalist brands, aged models and gasoline engines.     

Maximizing product mix profitability - what's the best analysis tool

This paper takes a look at product mix profitability and compares several alternative methodologies for selecting the optimal product mix. It is argued that the optimal product mix is not determined using traditional accounting methodologies and that dropping marginally profitable products based on the accounting rules will give you less than optimal profitability. This paper looks at two different ways for coming up with the optimal product mix: one using theory of constraints (TOC) and another using linear programming.     

内部营销对一线服务员工任务绩效影响的实证研究

本文以饭店业一线服务员工为研究对象,初步验证了Keller等学者的内部营销组合工具量表在中国背景下的适用性,并应用Bagozzi的态度理论模型,采用结构方程建模方法,构建并验证了基于内部营销组合工具视角的一线服务员工任务绩效预测模型。实证结果表明,一线服务员工对企业内部营销努力的感知,即对内部工作产品、内部价格、内部分销以及内部促销等内部营销组合工具的评价,决定了他们的情感承诺(对组织的情感反应)和工作满意(对工作的情感反应)水平,进而影响了他们的任务绩效水平(行为),一线服务员工的情感反应变量是解释企业内部营销努力影响一线服务员工任务绩效的中介变量。     

On flexible product-mix decision problems under randomness and fuzziness

This paper considers several models of product-mix decision problems and production planning problems under uncertain conditions, and shows that these are extensional and versatile models for resolving previous product-mix problems. These proposed models include randomness derived from statistical analysis based on historical data, ambiguity of decision maker's intuition and the quality of received information, and flexibility in accomplishing the original plan. Furthermore, given that the upper limit values of some constraints have flexibility, and given a decision maker's level of satisfaction, we propose a flexible product mix of problems using the theory of constraints (TOC), and develop an efficient solution method. We then provide a numerical example that compares our models with some previous basic models. Efficiency of flexibility is obtained when our proposed models are applied to several conditions, such as measurable changes from the expected value of future returns.     

Evaluating airline competitiveness using multiattribute decision making

This paper presents an objective approach to the evaluation of airline competitiveness. The evaluation problem is formulated as a multiattribute decision making model and solved by three widely used methods (the simple additive weighting method, the weighted product method and the technique for order preference by similarity to ideal solution) based on multiattribute value theory. A new empirical validation procedure is developed to deal with the inconsistency problem of evaluation outcomes produced by the three methods. The procedure selects the evaluation outcome which has a minimum expected value loss. An empirical study on Taiwan's five major domestic airlines is conducted to demonstrate the effectiveness of the approach. To measure and compare overall competitiveness of the airlines, five competitiveness dimensions and their associated objective performance measures on both efficiency and effectiveness are identified. The result of empirical validation for the three methods suggests the use of the simple additive weighting method. The evaluation outcome helps an airline identify its competitive advantages relative to its competitors. The objective approach presented is particularly applicable when subjective judgements on performance ratings and attribute weights are not reliable, or suitable decision makers are not available.     

AN OVERVIEW OF TRADEOFF CURVES IN MANUFACTURING SYSTEMS DESIGN

In this paper we review the use of tradeoff curves in the design of manufacturing systems that can be modeled as open queueing networks. We focus particularly on the tradeoff between expected work-in-process (or product leadtime) and capacity investment in job shops. We review the algorithms in the literature to derive tradeoff curves and illustrate their application in evaluating the efficiency of the system, in deciding how much capacity to have, how to allocate resources between the reduction of uncertainty and the introduction of new technologies, and how to assess the impact of changes in products throughput and product mix. The methodology is illustrated with an example derived from an actual application in the semiconductor industry.     

The marketing strategy worksheet—A practical planning tool

The Marketing Strategy Worksheet is a simple aid to strategic planners. It enables a coherent and integrated plan to be produced and communicated to others. It is a three-level flow chart comprising an analytical stage, formulation of some key primary decisions and subsequent settlement of strategic issues within the marketing mix. The analytical stage incorporates both external and internal analysis. The primary decisions concern company objectives, marketing objectives, demand management, target market and positioning. Using the conventional marketing mix format, decisions are made about product, promotion, distribution and price.     

基于(k,y)空间技术分解的企业投资效率评价

目前国内外企业层次上综合投资效率评价的研究还是一个未探索的领域,现有企业业绩评价方法没有将投资效率列为评价的内容,对企业发展能力的评价呈现出明显的不合理。本文在相关领域投资效率评价方法以及对投资效率内涵界定的基础上,总结投资效率评价基本出发点,利用技术效率评价在(k,y)空间的投影来建立企业层次上综合投资效率的评价方法。在(k,y)空间内,可以识别并分解企业资产技术和运营效率,能够有效跟踪企业资产及相应运营效率的变化。在此基础上建立的投资效率评价指标融合了目前宏观经济和微观具体项目投资效率评价方法,反映的是企业投资活动对其经营效率的带动作用,能够准确评价企业投资效率的真实业绩。     

An Information‐Processing Approach for Evaluating In‐Store Retail Operational Design Strategies

We develop a model to evaluate retail store operational design strategies using an information‐processing perspective of organizational design. We propose that three model constructs pertaining to in‐store shopper task uncertainty—the product mix complexity, the service production complexity, and the product mix changeover—create shopper encounter information requirements (IR). These requirements can be met using specific retail service operational design choices for managing shopper encounters, namely, designing layouts for self‐service (SS) and providing employees with task empowerment (TE). The model is then operationalized using a two‐stage approach to develop new multi‐item, measurement scales. The psychometric properties and predictive validity of the scales and model are then confirmed by using structural equation modeling with survey data from 175 merchandise retail store managers. We find that our model can be generically applied across the retail industry to understand how shopper encounter IR motivate retailer store design choices and can be used to determine whether to design stores for SS or to provide store employees with TE. We then evaluate the efficacy of the studied store design choices on customer delivery satisfaction, and offer some suggestions for future research.     

Plans—Their preparation and implementation

This article outlines the methodology developed in the adoption of long range planning at Reed International. Whilst the author rightly draws attention to the fact that the methodology described may not be applicable, or preferable, for all businesses it can give valuable lessons. Particularly, since Reed International is a highly diversified multi-national group of companies whose activities range from pulp and paper to publishing and building products, the difficulties of ensuring that plans are logically coherent, informative and examine the relative range of alternatives, is a complex and difficult task. Therefore, the paper provides a highly relevant and detailed insight into the planning methodology adopted by a company whose activities are wide ranging both in terms of product mix and geographical location. The author stresses the importance of planning as a process which includes the necessary structural underpinning but which concentrates essentially on the integration of concepts and ideas which may help the future performance of the company. Finally, the author also examines the important but often forgotten element of planning, the elements of control necessary to ensure effective implementation.     

Flexible home care scheduling

Home care services are in high demand given how they are steadily becoming the primary source of care for the elderly. Powerful decision support tools are indispensable for effectively managing available staff in the context of ever-increasing demand for care and limited caregiver availability. This paper advances home care literature by introducing flexible task durations, thereby enabling tasks to be completed faster and ultimately more care to be scheduled. This new concept, which originates from practice, introduces an additional decision to be made when creating a schedule, thereby greatly increasing the scheduling complexity. Consequently, this paper introduces a new optimization-based decision support model which allows for scheduling with flexible task duration, as well as other types of flexibility. A computational study quantifies the impact of: (i) scheduling with a finer task granularity thereby enabling accurate prioritization of high and low priority care, (ii) flexibility in task duration enabling tasks to be completed faster and more care to be scheduled, and (iii) increasing the number of different locations visited by a caregiver thereby enabling a trade-off between the number of serviced clients and caregiver workload. A new publicly available real-world data set is used, obtained directly from home care organizations operating in Flanders. Analysis of the computational results demonstrates that significant improvements in operational efficiency may be realized with minimal effort required by organizations. Furthermore, the proposed algorithm’s performance is confirmed by comparison against the bounds obtained by solving an integer programming formulation of the problem. Finally, a management policy scheme is proposed which, when gradually implemented in a home care organization, results in a more efficient and therefore cost-effective deployment of its workforce.     

DEMAND FULFILLMENT RATES IN AN ASSEMBLETO- ORDER SYSTEM WITH MULTIPLE PRODUCTS AND DEPENDENT DEMANDS

This paper presents a model for evaluating product fulfillment rates in an assemble-to-order system with a two-level bill-of-material structure (products and components). Inventories are kept at the component level and are used to support service levels to product demands; each component is managed under a periodically reviewed, decentralized order-up-to policy. Product demands are correlated in a given period but are independent across periods. We develop the demand fulfillment rate for each product when demands are filled based on a first-come-first-served discipline with limited priorities for different products within a period. We show that the fulfillment rate can be expressed as a multivariate normal probability when the product demands follow a multivariate normal distribution. We then use a numerical example to discuss computational issues and bounds associated with the evaluation of the demand fulfillment rates. Finally, we consider a model for minimizing the total inventory investment subject to given product demand fulfillment rates.     

The TOC-based algorithm for solving product mix problems

The five steps of the theory of constraints (TOC) emphasize exploiting constraints in order to increase the throughput of a system. The product mix decision is one application of the TOC five steps. However, these steps were considered to be implicit or incomplete, the criticism being that they result in deriving an infeasible solution when a plant has multiple resource constraints. This paper follows the essence of these five steps and presents an explicit algorithm to address the problem. When testing its effectiveness by using a dual-simplex method with bounded variables, this algorithm gives the same result in each iteration.