Optimal ordering time interval taking account of time value

In this paper, the optimal inventory policies for an infinite lime span taking account of time value is discussed. First, bounds for the optimal ordering time interval are derived. Second, with these bounds, a simple algorithm to compute die optimal ordering time interval is developed. Numerical examples are given to illustrate the algorithm.     

An adaptation of the EOQ formula for JIT quasi-pull system production

This research demonstrates for the first time that in a just-in-time (JIT) quasi-pull production environment, a model adapted from the Economic Order Quantity and made up of two specific formulas can be employed for calculating an optimised lot size. The assumptions of our model are: a low level of defects, and insignificant shortage backordering and failure of the equipment. JIT quasi-pull production is the state typically reached by many manufacturing companies because it is almost impossible to achieve zero set-ups and zero work-in-process (WIPs) even in the best Lean Production implementations. In this model, finished products are shipped at once in a JIT way. The two developed formulas are specialised: one for balanced stations/processes and the other for unbalanced stations; the formulas allow calculation of an optimised lot size. Several applications of the formulas have been tested and discussed through a case study. Findings demonstrated that the optimised quantity of a lot size has to be smaller than the customer’s daily demand for the product. Moreover, in case of unbalanced stations with long cycle times, the formula forces the company to reduce its set-up times and the cycle times. The new model will be of interest to practitioners who are seeking a way to balance the costs of set-ups and the cost of holding some WIPs and offers interesting avenues for new research.     

A note on the deterministic EPQ with partial backordering

In a recent paper published in Omega [Pentico DW, Drake MJ, Toews C. The deterministic EPQ with partial backordering: a new approach. Omega 2009; 37(3):624–36], the authors proposed an EPQ model with partial backordering. In the EPQ model, a critical value of backordering rate was developed, below which the optimal production policy is either to lose all sales or meet all demand, above which the optimal policy is to allow stockouts with partial backordering and meet fractional demand. However, there exists a flaw in the critical value of backordering rate, which will be amended in this note.     

投资时限对项目期权价值的影响分析

针对一般实物期权研究中,项目投资无限期假设的不足,研究实际中对投资时间有限期要求项目的投资期权评价问题.文章以我国房地产投资政策为背景,建立模型,研究给出了对投资机会限定在时间T内有效、投资者在其中具有投资管理柔性的投资项目的价值评价.用数值分析方法讨论了投资时限对投资机会价值和对投资者最优决策的影响,给出了投资者在等待以降低投资风险和尽快投资以避免机会失效之间的权衡.     

A note on supply risk and inventory outsourcing

To fully accommodate the correlations between semiconductor product demands and external information such as the end market trends or regional economy growth, a linear dynamic system is introduced in this paper to improve the forecasting performance in supply chain operations. In conjunction with the generic Gaussian noise assumptions, the proposed state-space model leads to an expectation-maximisation (EM) algorithm to estimate model parameters and predict production demands. When the dimension of external indicators is high, principal component analysis (PCA) is applied to reduce the model order and corresponding computational complexity without loss of substantial statistical information. Experimental study on some real electronic products demonstrates that this forecasting methodology produces more accurate predictions than other conventional approaches, which thereby helps improve the production planning and the quality of semiconductor supply chain management.     

ICT-enabled time performance: an investigation of value creation mechanisms

The study presented in this paper aimed at checking whether companies that embed information and communication technologies (ICT)-enabled time performance into their product offering can achieve better economic outcomes from technology adoption. Indeed, it is still questionable whether technology adoption results in a superior profitability, especially if such an improvement is achieved through the use of functional ICT applications. In this study, we assume that a better alignment among ICT investments, improvements of the logistics process and the value proposition of the firm can lead towards a superior economic performance. A survey was conducted and 180 usable questionnaires were collected from companies engaged in the electronics and vehicle manufacturing industries. Data were analysed through the structural equation modeling approach. The results show that improvements in speed and dependability, achieved through technology adoption, can lead to a better economic performance if they are embedded into superior after-sales services and/or into an improved product offering.     

A note on special optimal batching structures to minimize total weighted completion time

A batch is a subset of jobs which must be processed jointly in either serial or parallel form. The algorithmic aspects of the batching scheduling problems have been extensively studied in the literature. This paper presents necessary and sufficient conditions of the existence of optimal batch sequences for the single machine, batching, total weighted completion time scheduling problems on two batching ways: (1) all jobs form one batch; (2) each batch contains a single job. This kind of conditions can help us to recognize some special optimal schedules quickly. Research supported by NSFC (10671183).     

A note on “The EPQ with partial backordering and phase-dependent backordering rate”

Pentico et al. [The EPQ with partial backordering and phase-dependent backordering rate. Omega 2011;39(5):574-7] recently proposed an EPQ model with partial backordering. They tried to determine the minimum average total cost per year from the three cases: to lose all sales, to meet all demand, and to allow stockouts with partial backordering. In this paper, we solve the same model without differential calculus and present a different decision procedure. Without the comparison of those costs, a numerical example is illustrated to determine the optimal production policy by our criteria.     

A note on an economic production quantity model and just-in-time production

In this paper an economic production quantity (EPQ) model in which the production rate is variable is studied. An analysis is presented of the impact of a variable production rate on the optimal production quantity and the total relevant cost. It is observed that this EPQ production and inventory system, in which the production rate is close to the demand rate, possesses many characteristics that are similar to a just-in-time (JIT) production system. It is shown that the normal prerequisites and benefits of JIT production can be identified from an analysis of such an EPQ system.     

Application of value stream mapping (VSM) for lean and cycle time reduction in complex production environments: a case study

The application of VSM is a proven approach for lean-based improvements. Typically, this becomes challenging, when applied for complex production environments. The purpose of this research is to demonstrate, how with some approximations and simplifications in VSM application, lean can be successfully achieved in these environments. The research follows case study method and systematically guides about the segregation and treatment of non-value-adding(NVA) and value-adding (VA) activities of heavy-duty industrial power transformer making process. The focal company operates in engineer to order (ETO) and high-mix low-volume (HMLV) environments. With a research team using gemba walks and systematic questioning technique, relevant data were collected for mapping. Taguchi method was also applied for one of the critical steps, which was influencing cycle time and energy requirements. The generalisable findings endorse the strengths of approach for lean by addressing wastes and cycle time reduction. The study establishes that VSM application-based lean messages remain same for both simple and complex environments. It also exposes that non-compliance of ‘VSM assumptions’ and ‘micro-concepts’ are the root causes for application complexities. The study also offers useful insights and practical guidelines to facilitate lean in ETO, construction and HMLV production environments.     

考虑成本和收益净现值的确定性存储决策模型研究

净现值是企业决策中需要考虑的重要宏观经济因素.本文建立了考虑成本和收益净现值的连续时间有限时段确定性库存系统的最优存储和定价决策模型,证明了给定价格下最优策略中任意两个相邻订货周期之间的递推关系,分析了该关系的解析性质,并得出订货周期长度的上下限.在此基础上提出求解最优存储策略和最优价格的两步优化算法.最后通过数值算例对本文模型及结果做出说明.     

On the integration of production,inventory and trade-credit policies

The primary objective of this paper is to highlight the need for the integration of procurement, production and marketing strategies. This is accomplished through the development of a model for a small firm, where the objective is the maximization of the present value of profits within an infinite horizon framework Other features include a JIT-like procurement system, a continuous production situation and a combination of cash discounts and credit period to stimulate sales. A numerical example is presented to illustrate the main features of the study.     

石油储备价值研究:基于供应链视角

石油储备是应对石油供应链危机的重要途径.构建了反映石油供应链运营的线性规划模型,利用该模型模拟供应链发生不同程度的供应危机和价格危机时,30 d、60 d和90 d的石油储备在应对需求及价格危机中的作用.研究结果表明:当需求及价格发生较大幅度上升时,供应链石油储备可以有效抑制需求及价格上升引起的运作成本上涨,且不同规模...     

A comment on: A note on the EOQ-JIT relationship

In a recently published note in this journal the need for independent control of the production rate (R) and production time (L) was established in order to adapt the economic production quantity (EPQ) model in JIT settings. In this comment we aim to improve the relevance of EPQ in a JIT environment. We focus on two issues, namely, modelling the production rate as a decision variable and also deriving an expession for the optimal number of batches (n* ) for the raw materials and/or subcomponents needed.     

论企业柔性价值的功能,成本与价值

运用价值工程理论 ,提出了企业柔性功能、柔性成本及柔性价值的概念 ,分析了三者之间的关系 ,指出企业不应盲目追求高柔性、而应努力提高柔性价值 ,并讨论了提高企业柔性价值的途径     

Work value orientations and patterns: A comparison of future managers with manager and non-manager groups

This study uses the Values for Working questionnaire to classify the primary value systems and value patterns of 501 senior business school students (future managers). The students' scores on six value systems measured by the questionnaire are compared to national data on blue collar and clerical workers and on managerial and professional workers. The business students scored in the average range for four of the six value systems when compared to the manager group, but for only one of the value systems when compared to the non-manager group. Of the business students who had a primary value system, 82 percent wereexistential ormanipulative. There were significant differences in the value systems scores by sex but not by business major.     

RUTA: A framework for assessing and selecting additive value functions on the basis of rank related requirements

In this paper, we present a new preference disaggregation method, called RUTA, which infers a set of additive value functions from the preference information referring to the desired ranks of some reference alternatives. Real-life experience indicates that people willingly refer to the range of allowed ranks that a particular alternative should attain, or to constraints on the final scores of the alternatives. We develop a mathematical model for incorporating such preference information via mixed-integer linear programming (MILP). Then, we discuss how decision making could be supported with the use of the already proposed extreme ranking analysis (ERA), which indicates the best and worst ranks gained by each alternative over the set of compatible preference model instances. We also introduce a new interactive UTA-like technique, which aims at selecting a single value function representing the outcomes of ERA. In the interactive process, the decision maker (DM) is assigning priorities to different pre-defined targets, which are built on results of ERA, and refer to the comparison of the best and/or worst ranks for pairs of alternatives. In particular, the DM may choose to emphasize or neglect the advantage of some alternatives over the others, in terms of results of ERA. In this way, one obtains a synthetic representation of extreme ranking analysis at a higher level of abstraction.     

A process-oriented perspective on differential business value creation by information technology: An empirical investigation

The relationship between information technology investments and firm value as an area of inquiry has sustained interest among IS researchers over the past decade. More recently, some have challenged the notion differential value among firms through Information Technology (IT) as it evolves into a ubiquitous utility-like set of technologies. This study examines the relationship between IT and business value from a process-oriented perspective, and also helps to identify the underlying links between IT and its differential business value to firms. By drawing upon economic and organizational theories, this paper develops a process framework to assess the intermediate organizational process capabilities and overall performance of firms that effectively deploy and use IT. Using data from over 80 firms, the study finds empirical support for the differential business value created by IT along a number of process oriented dimensions. These findings are discussed as these results set an optimistic tone for IT as a major causal driver of differentiation.     

Multinational alliances: A note on the perception of technology executives

Multinational alliances in the 1980s came into vogue as one of the prominent instruments of corporate strategies. In the process of forging alliances, especially in the technologyintensive firms, senior technology executives such as directors of R & D often play a vital advisory role. This short paper reports the findings of survey of American technology executives. Among the findings two are noteworthy in the conceptualizations of multinational alliances: Alliances are viewed as a means to solving a firm's strategic problems, and as offering mutual learning opportunities, rather than win-win possibilities for firms entering the alliances.