Analysis of integrated procurement — production systems using mathematical and simulation modelling approaches

Abstract

Integrated procurement-production (IPP) systems offer interesting scope for unifying procurement and production policies in a batch environment. The available literature on IPP is restrictive in its scope for applying to real-life situations. In this paper, an attempt is made to widen the scope of application by judiciously combining an analytical model with a simulation model. The results presented apply to a number of experimental studies carried out with this hybrid approach. The usefulness of such a hybrid approach is highlighted through the results pertaining to a number of simulated problem sets generated.     

The Effort-Reward Imbalance model of psychosocial stress at the workplace—a comparison of ERI exposure assessment using two estimation methods

It is not unusual for old data to be used in epidemiological studies. Recently developed instruments for measuring work-related stress did not exist when the data collection was carried out. Therefore, approximate questions are sometimes used. An apparent problem is the lack of validation of proxy questions. The aim of this study was to compare the original questions for measuring Effort-Reward Imbalance (ERI) with approximate questions. The study population corresponded with a subgroup in the WOLF-n (WOrk, Lipids, Fibrinogen–north) cohort study of cardiovascular risk in a working population in the north of Sweden: 655 men and 178 women. The agreement in exposure between the original and the approximate ERI single questions was relatively low throughout, whereas the correlation between the ERI subscales and the ERI ratios was reasonable. The latter agreement between the original and the approximate ERI ratio indicates that the approximate measures might have been useful in the past. Yet, whenever possible the implementation of the original questionnaire in study protocols is recommended since a complete measurement of ERI might help to further improve the internal consistency and the predictive validity of this exposure to effort-reward imbalance.     

Social forecasting: An integral part of corporate planning?

The increasing need for business to monitor the social dimensions of its environment and, hopefully make some forecasts of future trends has met with some constructive response from academics and consultants although not as yet on a very liberal scale. The published literature does not indicate to what extent companies in general attemp social forecasting and, where they do, the degree of integration which exists within their corporate planning systems. The authors, therefore, decided to survey a sample of British organizations to see if they could shed some light on these issues and thereby add some information to the excellent accounts of individual cases of social forecasting in, they suspect, the more advanced and atypical companies. The survey suggests a general picture of: awareness of the value of social forecasting; fairly widespread ignorance of the techniques which do exist, primitive though these may largely be; successful integration of social forecasting into the corporate planning systems of a substantial number of organizations but not in the majority.     

Provider–user differences in perceived usefulness of forecasting formats

This paper aims to examine potential differences in perceived usefulness of various forecasting formats from the perspectives of providers and users of predictions. Experimental procedure consists of asking participants to assume the role of forecast providers and to construct forecasts using different formats, followed by requesting usefulness ratings for these formats (Phase 1). Usefulness of the formats are rated again in hindsight after receiving individualized performance feedback (Phase 2). In the ensuing role switch exercise, given new series and external predictions, participants are required to assign usefulness ratings as forecast users (Phase 3). In the last phase, participants are given performance feedback and asked to rate the usefulness in hindsight as users of predictions (Phase 4). Results reveal that regardless of the forecasting role, 95% prediction intervals are considered to be the most useful format, followed by directional predictions, 50% interval forecasts, and lastly, point forecasts. Finally, for all formats and for both roles, usefulness in hindsight is found to be lower than usefulness prior to performance feedback presentation.     

Strategic planning and product innovation—Some systematic approaches

Companies interact with society. The desires and needs of society change. If an enterprise wants to continue to function, then it must adapt its course to the changes. Such a process of adaptation occurs in two stages. In the first, the strategy of the enterprise must be formulated. This strategy forms the dynamic framework for the second phase—product innovation. In this second phase future strategy is made concrete by launching new or improved products on the market. This whole adaptation process has organizational consequences for the relationship between the enterprise and society, for the internal organizational structure and for the human beings involved in the process. These consequences are discussed briefly in this paper. The paper concludes with an example taken from practice, which shows clearly that the transformation of theory into practice is very definitely not free from problems.     

Situation-based measurement of the full range of leadership model — Development and validation of a situational judgment test

In response to calls for context-specificity in leadership research, we developed and validated a Situational Judgment Test of the Full Range of Leadership Model (SJT-FRLM). Three consecutive studies were conducted following the typical steps of test development. Study 1 served measure development and pilot testing: item stems were generated empirically, item responses were developed with a theory-driven approach, and pilot testing was based on a leader sample. Study 2 served to analyze construct- and criterion-related validity of the instrument. Moreover, an empirical scoring key was developed that weights each item response according to its relation with leadership effectiveness in each situation. In Study 3, we demonstrated incremental validity and interrater agreement. The test fills an important gap in literature because it not only has predictive validity above and beyond established measures, but also takes into account the contextual element of leadership.     

Average-Case Performance Analysis of a 2D Strip Packing Algorithm—NFDH

The two-dimensional strip packing problem is a generalization of the classic one-dimensional bin packing problem. It has many important applications such as costume clipping, material cutting, real-world planning, packing, scheduling etc. Average-case performance analysis of approximation algorithms attracts a lot of attention because it plays a crucial role in selecting an appropriate algorithm for a given application. While approximation algorithms for two-dimensional packing are frequently presented, the results of their average-case performance analyses have seldom been reported due to intractability. In this paper, we analyze the average-case performance of Next Fit Decreasing Height (NFDH) algorithm, one of the first strip packing algorithms proposed by Coffman, Jr. in 1980. We prove that the expected height of packing with NFDH algorithm, when the heights and widths of the rectangle items are independent and both obey (0, 1] uniform distribution, is about n/3, where n is the number of rectangle items. We also validate the theoretical result with experiments.This work is supported by National 973 Fundamental Research Project of China on NP Complete Problems and High Performance Software (No. G1998030403).     

The use of a model in long term planning—A case history

Long term planning in companies can range from the partial simplistic approach to a structured time-consuming ritual. Either extreme can bring planning into disrepute, and both reflect the lack of the proper tools of the trade. Models, by themselves, are no panacea, but properly conceived, constructed, and developed they can transform the planning process. The key to effective and practical models is use, and this can be achieved through direct management involvement on the model's development, and by making sure the model is basically simple and flexible. This article describes how such a model was constructed using a modular approach, and how it was used effectively in long term planning.     

Corporate planning for a town—a case history

Corporate planning is relatively new in U.K. local government. This article suggests the reasons behind this late development, and outlines the particular problems in local government and the approach adopted in one authority. The author's philosophy is that there is no blueprint for introducing corporate planning and that any approach must be evolutionary, reflecting local circumstances. The article covers the period from 1971 outlining the four main stages of development and includes the effects of local government reorganization in 1974. The views expressed are those of the author and do not necessarily represent those of the borough.     

Comparison of the influences of structured on-the-job training and classroom training approaches on trainees’ motivation to learn

Increasing trainees’ learning motivation is critical to help them perform well in the training programme. This paper aims to examine the influences of the structured on-the-job training (S-OJT) and classroom training approaches on trainees’ learning motivation and learning performance. An exploratory study was conducted with 90 students from a vocational school located at the Yunlin County in the Midwest of Taiwan who enrolled in a course entitled ‘hair coloring’. The training modules for S-OJT and classroom training were developed and delivered in the training courses. The survey was administered prior to and after the training courses to assess the influences of the training approaches. It was found that the trainees who received S-OJT generated higher learning motivation and learning performance compared with those who received the classroom training. Moreover, the trainees with lower initial learning motivation were motivated more and generated higher learning performance after receiving S-OJT. This study provides the potential theoretical and practical implications and can serve as reference when choosing the training approach for a designed training programme.     

Partner selection in green supply chains using PSO – a practical approach

Partner selection is crucial to green supply chain management as the focal firm is responsible for the environmental performance of the whole supply chain. The construction of appropriate selection criteria is an essential, but often neglected pre-requisite in the partner selection process. This paper proposes a three-stage model that combines Dempster–Shafer belief acceptability theory and particle swarm optimisation technique for the first time in this application. This enables optimisation of both effectiveness, in its consideration of the inter-dependence of a broad range of quantitative and qualitative selection criteria, and efficiency in its use of scarce resources during the criteria construction process to be achieved simultaneously. This also enables both operational and strategic attributes that can be selected at different levels of hierarchy criteria in different decision-making environments. The practical efficacy of the model is demonstrated by an application in Company ABC, a large Chinese electronic equipment and instrument manufacturer.     

Planning a cost-effective cellular manufacturing process—a case study

The drive key is one of the most important high-precision components of aircraft braking systems. In this paper, a cost-effective drive key manufacturing process is developed. This proposed manufacturing process makes use of near net shape manufacturing, CNC machining, and cellular manufacturing methods. To make the proposed process a reality, proper engineering changes of the parts along with group technology are applied to the product design, in conjunction with the pro posed manufacturing methods. In addition, a general spread sheet program is developed for each style of fixture module to assist in part program coding. Moreover, statistical process control (SPC) is implemented to verify product quality and accept the product at the point of manufacture. It is observed that the implementation of the proposed drive key cellular manufacturing process results in a tremendous improvement in quality, throughput and productivity as well as a drastic reduction in manufacturing operations, workholding fixtures, cutting tools, and inspection media.     

Multilocation plant sizing and timing problem: a study of spatial—temporal decomposition procedure

An attempt has been made to develop a spatial-temporal decomposition procedure to solve the multilocation plant sizing and timing problem (MLPSTP). MLPSTP involves the determination of site, location, timing and utilization of the plants to meet the demands of geographically distributed customers. These decisions are assumed to interact through a common objective of minimizing the net present value (NPV) of capital costs and streams of operating and transportation costs. A solution procedure for MLPSTP is proposed using aggregation and disaggregation methodology. In the aggregation phase, MLPSTP is considered to be a single-period problem. This problem is decomposed over different geographical areas to obtain a set of feasible sites and projects. These projects are then sequenced over a finite planning horizon in the disaggregation phase. A multiple criteria based evaluation of spatial decomposition, temporal decomposition, and spatial-temporal decomposition is provided.     

EDLP versus Hi–Lo pricing strategies in retailing—a state of the art article

The pricing strategy is seen as one of the five most important priorities in retail management. Over the past years, price wars have emerged and price has become an even more focal point of retailers’ agendas. Especially grocery retailers operate on very low margins and have fallen into a price-promotion trap, pressured both by competition and consumers. In times of intensive competition it is getting even more important for retailers to focus on profitable and successful pricing strategies. Furthermore, retailers act under complex circumstances, especially because of broad assortments, and should therefore define a clear framework for their pricing strategy. There are several studies which have been published on pricing strategy in retailing during the last years, but no comprehensive literature review of this topic with its determinants and outcomes exists. Based on the theoretical and conceptual foundations of pricing strategy in retailing, all relevant conceptual and empirical studies are analyzed. First, the different definitions of pricing strategy in retailing are examined and systemized. Furthermore, a division into studies on determinants and outcomes of pricing strategy in retailing is included followed by a discussion of main and further results. Based on this analysis of the existing literature, avenues for further research are identified and prioritized.     

MRO inventory reduction—challenges and management: a case study of the Tennessee Valley Authority

Emphasis on maintenance, repair, and operations inventory (or MRO inventory) can lead to improved inventory control, reduced operational costs, enhanced productivity, and increased cost accounting accuracy. To review the benefits of MRO inventory reduction, as well as highlight the management challenges associated with the process, a case study of the Tennessee Valley Authority (TVA) is presented. TVA is a not-for-profit electric power generation entity. TVA standardised inventory policies and procedures. Their comprehensive five-year plan included employee training, changes in organisational structure and strategy, reduced MRO inventories and the establishment of new growth drivers. Net inventory reductions of $47 million were realised. Suggestions for future MRO inventory reductions as well as replication of the management involvement and improvement process in other organisations are included.