| 1. |
- Agrell, Per J, et al.
(författare)
-
Risk, information and incentives in telecom supply chains
- 2004
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Ingår i: International Journal of Production Economics. - 0925-5273. ; 90:1, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- Supply chain management involves the selection, coordination and motivation of independently operated suppliers. The central planner's perspective in operations management translates poorly to vertically separated chains, where suppliers recurrently seem to object to benevolent information sharing and centralized decision rights. Seen from the supplier's perspective, such resistance may very well be rational. A downstream assembly line disclosing reliable information on actual and forecasted sales puts itself at a disadvantage when bargaining on share of chain profits. In this paper, we use a minimal agency model to contrast known optimal mechanisms with the actual practice in the telecommunications industry. A three-stage supply chain under stochastic demand and varying coordination and information asymmetry is modeled. A two-period investment-production game addresses the information sharing and specific investment problem in the telecom industry. The observed price-quantity contracts under limited commitment are shown to be inadequate under realistic asymmetric information assumptions. More a result of gradually evolving changes in bargaining power than coordination efforts, the upstream urge to coordinate may further deteriorate performance in terms of our model. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 2. |
- Al-Najjar, Basim, 1954-, et al.
(författare)
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Selecting the Most Efficient Maintenance Approach Using Fuzzy Multiple Criteria Decision Making
- 2003
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 84:1, s. 85-100
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Tidskriftsartikel (refereegranskat)abstract
- We assess the most popular maintenance approaches, i.e. strategies, policies, or philosophies, using a fuzzy multiple criteria decision making (MCDM) evaluation methodology. We illustrate with two examples how the suggested evaluation methodology identifies the most informative approach. Using the fuzzy MCDM, it would be possible to select in advance, the most informative (efficient) maintenance approach. Consequently, this leads to less planned replacements, and failures would be reduced to approximately zero and higher utilization of component life can be achieved. Thus, the maintenance department could contribute more to the business objectives throughout participating effectively in adding value to the production activities.
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| 3. |
- Axsäter, Sven
(författare)
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Approximate Optimization of a Two-Level Distribution Inventory System
- 2002
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Ingår i: International Journal of Production Economics. - 0925-5273. ; 81-82, s. 545-553
-
Tidskriftsartikel (refereegranskat)abstract
- A two-echelon distribution inventory system with a central warehouse and a number of retailers is considered. The retailers face stochastic demand. The system is controlled by continuous review installation stock (R,Q) policies with given batch quantities. There are linear holding costs at all locations and linear backorder costs at the retailers. We present a simple technique for approximate optimization of the reorder points. The technique means that we use normal approximations both for the retailer demand and the demand at the warehouse, i.e., the orders from the retailers.
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| 4. |
- Yard, Stefan
(författare)
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Costing fixed assets in Swedish municipalities: Effects of changing calculation methods
- 2004
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Ingår i: International Journal of Production Economics. - 0925-5273. ; 87:1, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- When pricing public utility services Swedish municipalities are not allowed to charge more than their full cost. A dominant cost component in operations such as energy distribution or handling water and wastewater is the cost of fixed assets-depreciation plus interest, here referred to as "capital service cost" (CSC). The maximum acceptable price for the services is the full cost, i.e., variable cost plus fixed cost, which is mainly CSC. For CSC the sum of the present values (PV) should not exceed the investment value. Several different CSC methods meet such a PV criterion but allocate the CSC differently over time. To achieve a better match with the generated services, costing practice has changed, shifting among several alternate CSC methods. As these alternates all meet the PV criterion, the issue of charging more than full cost has not been given much attention. However, it is not enough to focus on the internal consistency of the methods. The implementation of changes and the choice of parameter values, such as interest rates, have to be considered. Such wider analysis reveals that Swedish municipalities have overestimated the full costs in public utilities by a total of several tens of billions SEK (several billions USD) giving rise to a corresponding overcharge. (C) 2003 Published by Elsevier Science B.V.
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| 5. |
- Agrell, Per J., et al.
(författare)
-
A Coherent Methodology for Productivity Analysis Employing Integrated Partial Efficiency
- 1996
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 46-47, s. 401-411
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Tidskriftsartikel (refereegranskat)abstract
- An activity decomposition methodology with theoretical foundation in the principles of activity control and stated focus of interest in the enterprise value-chain is presented. Characteristics of inputs and outputs are discussed, where a set of non-transformable inputs are defined and motivated. An integrated partial efficiency measure is formulated, compensating for some weaknesses of the Debreu-Farrell technical efficiency concept. Providing a coherent basis for productivity analysis, the IPE approach poses an alternative to e.g. DEA especially in the case of multi-level systems and sparse data. The method is easily communicable in terms of measurement and analysis, and may be extended to complement economic performance assessments and benchmarks.
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| 6. |
- Agrell, Per, J., et al.
(författare)
-
An MCDM Framework for Dynamic Systems
- 1996
-
Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 45:1-3, s. 279-292
-
Tidskriftsartikel (refereegranskat)abstract
- A multi-criteria formulation for continuous and discrete-time dynamic systems is presented. The fundamental problem in the design of dynamic systems is the trade-off between response speed (e.g., the time to reach final value and the raise time) and response smoothness (e.g., the overshoot, the undershoot, and the transient dampening). Separate optimisation of criteria is impossible, thus the problem is inherently multiobjective. In a general dynamic system, this is accomplished by adjusting a number of technical parameters in accordance with some ad hoc practice. Previous multi-criteria approaches have been modelled as weighted sums of criteria, with shortcomings in terms of sensitivity analysis and preference articulation. The proposed framework enables the decision maker to design a most preferred system, with full knowledge of local trade-off ratios in terms of chosen criteria. Combining analytical techniques with simulation, the formulation makes the optimisation process transparent to the decision maker, working entirely in decision space. The framework is demonstrated on a dynamic production-inventory model.
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| 7. |
- Aguilar Sommar, Ruth
(författare)
-
Business process modelling : Review and framework
- 2004
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 90:2, s. 129-149
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Tidskriftsartikel (refereegranskat)abstract
- A business process is the combination of a set of activities within an enterprise with a structure describing their logical order and dependence whose objective is to produce a desired result. Business process modelling enables a common understanding and analysis of a business process. A process model can provide a comprehensive understanding of a process. An enterprise can be analysed and integrated through its business processes. Hence the importance of correctly modelling its business processes. Using the right model involves taking into account the purpose of the analysis and, knowledge of the available process modelling techniques and tools. The number of references on business modelling is huge, thus making it very time consuming to get an overview and understand many of the concepts and vocabulary involved. The primary concern of this paper is to make that job easier, i.e. review business process modelling literature and describe the main process modelling techniques. Also a framework for classifying business process-modelling techniques according to their purpose is proposed and discussed. © 2003 Elsevier B.V. All rights reserved.
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| 8. |
- Alnestig, Peter, et al.
(författare)
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Product costing in ten Swedish manufacturing companies
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 46-47, s. 441-457
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the main results from case studies in 10 Swedish manufacturing companies concerning their product costing. The main purpose of the study is to find out what models of product costing the companies use, what allocation bases are applied. Several questions have been asked to the companies: What is the purpose of the product costing? Is a special product costing used for inventory valuation? Is full costing or variable costing used? How are depreciation costs and cost of capital treated? Is some sort of activity-based costing used? If so, which arethe cost drivers? The study is a case analysis, no questionnaires are used. The study presents arguments that a separation of product costing in “Activity-Based Costing” or “traditional costing” is not possible, but also that more “ABC-thinking” is necessary.
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| 9. |
- Axsäter, Sven, et al.
(författare)
-
Approximating general multi-echelon inventory systems by Poisson models
- 1994
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 35:1-3, s. 201-206
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Tidskriftsartikel (refereegranskat)abstract
- We consider a continuous review two-level inventory system with a central warehouse and a number of retailers. The demand processes at the retailers are different compound Poisson processes. We present and evaluate an approximate optimization technique, where the real demand is replaced by "equivalent" Poisson demand such that the ratio between mean and standard deviation is the same as for the real distribution. The solution of the Poisson model is then scaled back to the original problem.
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| 10. |
- Axsäter, Sven, et al.
(författare)
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Comparison of Echelon Stock and Installation Stock Policies for Two-Level Inventory Systems
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 45:1-3, s. 303-310
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Tidskriftsartikel (refereegranskat)abstract
- It is previously known that echelon stock reorder point policies dominate installation stock reorder point policies for serial and assembly multi-level inventory systems. This paper presents worst-case results for the relative cost difference in case of constant demand and no backorders. Furthermore, we analyze distribution systems with stochastic demand by simulation. Depending on the structure of the system either echelon stock or installation stock policies may be advantageous.
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| 11. |
- Axsäter, Sven, et al.
(författare)
-
Comparison of echelon stock and installation stock policies with policy adjusted order quantities
- 1997
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 48:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Echelon stock and installation stock reorder point policies for multi-level inventory control have been compared in previous studies. It is known that echelon stock policies dominate installation stock policies for serial and assembly systems. Earlier comparisons assume that both policies use the same given order quantities, while each policy is optimized with respect to its reorder points. This paper presents worst case results for the cost ratio when the order quantities can be optimized for each policy.
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| 12. |
- Bengtsson, Jens
(författare)
-
Manufacturing flexibility and real options : A review
- 2001
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 74:1-3, s. 213-224
-
Forskningsöversikt (refereegranskat)abstract
- This paper considers manufacturing flexibility and real options from an industrial engineering/production management perspective. Real options papers are related to different types of manufacturing flexibility in order to show which types that are considered and in what way they are considered. Flexibility types not valued with real options and real options without any corresponding manufacturing flexibility type are identified and discussed. © 2001 Elsevier Science B.V. All rights reserved.
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| 13. |
- Bengtsson, Jens, 1973-, et al.
(författare)
-
Valuation of product-mix flexibility using real options
- 2002
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 78:1, s. 13-28
-
Tidskriftsartikel (refereegranskat)abstract
- Flexibility in manufacturing operations is becoming increasingly more important to industrial firms, due to e.g., increasing market demand volatility, internationalisation of markets and competition, and shorter product life cycles. Defining, measuring and evaluating manufacturing flexibility have not been straightforward - neither in theory nor in practice. The use of real options has shown to be an accessible approach for the valuation of certain types of flexibility. When using real options for capital budgeting purposes it is possible to take flexibility options into account in the valuation process. In this paper, we use real options to evaluate one specific type of manufacturing flexibility, i.e., product-mix flexibility. We provide both theoretical and practical perspectives, based on a real case. The main interest of the company under study is to evaluate product-mix flexibility with respect to capacity, set-ups, level of automation and multi-functionality of resources. The case involves multiple products and demand uncertainty, wherefore product demands are used as the underlying asset in the real options models. Thus, the contribution of this paper concerns the combination of real case, multiple products, capacity constraints, and set-up costs. The results of the analysis show that (i) the value of flexibility decreases when demand volatility increases, (ii) flexible resources add substantial value as compared to dedicated resources, and (iii) the flexibility value of marginal capacity decreases with increasing levels of capacity.
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| 14. |
- Deleryd, Mats
(författare)
-
A pragmatic view on process capability studies
- 1999
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 58:3, s. 319-330
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years an increasing number of organisations use process capability studies on a regular basis. Contemporaneous with the increasing number of organisations using process capability studies, warnings have been launched that imprudent use of numerical measures of capability, the so-called process capability indices, might lead the user to make erroneous decisions. As a result, many practitioners of today are left with a somewhat ambivalent attitude towards process capability studies. In order to reduce these ambiguities, this paper outlines the advantages and disadvantages of the method. The results presented are based on a survey performed among 97 Swedish organisations that use process capability studies on a regular basis
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| 15. |
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| 16. |
- Grubbström, Robert W., et al.
(författare)
-
A stochastic model of multi-level/multi-stage capacity-constrained production–inventory systems
- 2003
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 81-82, s. 483-494
-
Tidskriftsartikel (refereegranskat)abstract
- A great deal of research has been done on capacity-constrained production–inventory systems, most of which concerns deterministic demand situations and single-product systems. In this paper we present a model of a multi-level capacity-constrained system when external demand is stochastic. Unlike the traditional total cost objective, adopted in the vast majority of capacity-constrained production–inventory models, the (expected) Net Present Value is here used as the objective function. Dynamic programming is chosen as the solution procedure. Numerical examples are given to explain the model and to illustrate features when changing available capacity.The Laplace transform together with input–output analysis are employed as tools to construct the model. This approach has been used in previous research to formulate a theoretical base for Material Requirements Planning (MRP) systems.The paper provides a further argument for the use of transforms in combination with matrix representations of product structures and capacity requirements, and it extends previous theory in the direction of capacity considerations combined with uncertainty in external demand. Dynamic programming is also shown to be a practical method for the multi-stage optimisation involved.The numerical examples further illustrate, for instance, the natural propensity for subordinate items to be lot sized in a more lumpy way than their parents, and also how the marginal benefit of capacity increments follows the law of diminishing returns. Also comparisons are made with solutions from the deterministic equivalence model, using average demand as a proxy.
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| 17. |
- Grubbström, Robert W., 1941-, et al.
(författare)
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Further Developments on Safety Stocks in an MRP System Applying Laplace Transforms and Input-Output Analysis
- 1999
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 60-61, s. 381-387
-
Tidskriftsartikel (refereegranskat)abstract
- In a sequence of previous papers, the Laplace transform and Input–Output Analysis have been applied to formulate a theoretical basis for material requirements planning (MRP) under different levels of generalisation. Searching for the optimal safety stock is one of the extensions of this theory. This paper investigates the safety stock properties in the case that the time interval of demand is Gamma-distributed. The Generalised Leontief inverse plays an effective role in describing the multi-level production–inventory system when the subordinate products are produced according to a lot-for-lot (L4L) policy.
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| 18. |
- Grubbström, Robert W., et al.
(författare)
-
Igls 2000
- 2002
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 77:3, s. 189-190
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
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| 19. |
- Grubbström, Robert, W., et al.
(författare)
-
Inventory Trigger Control Policies Developed in Terms of Control Theory
- 1996
-
Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 45:1-3, s. 397-406
-
Tidskriftsartikel (refereegranskat)abstract
- In this article we model standard inventory ordering rules in terms of control systems theory. A differential equation is designed describing the development of a system in which an input signal reaching a predefined level triggers an output. The reorder point of inventory control systems may be interpreted as such a level triggering a replenishment. Systems using this kind of control are frequent in a variety of applications. Apart from inventory, domestic heat and pressure control are but two examples.
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| 20. |
- Grubbström, Robert W., 1941-, et al.
(författare)
-
Modelling Rescheduling Activities in a Multi-Period Production-Inventory System
- 2000
-
Ingår i: International Journal of Production Economics. - : Elsevier. - 0925-5273 .- 1873-7579. ; 68:2, s. 123-135
-
Tidskriftsartikel (refereegranskat)abstract
- Decisions for planning production activities for multi-period production–inventory systems have been studied in a number of papers applying input–output analysis and the Laplace transform. The decisions have concerned activities spread out over time without having the opportunity to adjust future decisions when the external and/or internal circumstances change. In this paper, we extend the analysis to situations when rescheduling is possible. Firstly, different classes of causes justifying rescheduling activities are presented including periodic rescheduling and “net change”. Secondly, in terms of previously developed theory, we model the behaviour of a simple single-level production–inventory system for which its production plan may be modified at one point in the future.
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| 21. |
- Göthe-Lundgren, Maud, et al.
(författare)
-
An optimization model for refinery production scheduling
- 2002
-
Ingår i: International Journal of Production Economics. - Amsterdam, Netherlands : Elsevier. - 0925-5273 .- 1873-7579. ; 78:3, s. 255-270
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we describe a production planning and scheduling problem in an oil refinery company. The problem concerns the planning and the utilization of a production process consisting of one distillation unit and two hydro-treatment units. In the process crude oil is transformed to bitumen and naphthenic special oils. The aim of the scheduling is to decide which mode of operation to use in each processing unit at each point in time, in order to satisfy the demand while minimizing the production cost and taking storage capacities into account. The production cost includes costs for changing mode and for holding inventory. We formulate a mixed integer linear programming model for the scheduling problem. The model can be regarded as a generalized lot-sizing problem, where inventory capacities are considered and more than one product is obtained for some modes of operation. A number of modifications and extensions of the model are also discussed. It is shown how the optimization model can be used as a viable tool for supporting production planning and scheduling at the refinery, and that it is possible to analyze scheduling scenarios of realistic sizes. It is also shown that the model can support shipment planning and strategic decisions concerning new products and investments in storage capacity. © 2002 Elsevier Science B.V. All rights reserved.
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| 22. |
- Johansson, Pontus, 1974-, et al.
(författare)
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Industrial service profiling : Matching service offerings and processes
- 2004
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 89:3, s. 309-320
-
Tidskriftsartikel (refereegranskat)abstract
- Firms using industrial goods as a resource in their own operations need support and services to maintain an efficient use of these resources. Education, spare parts and maintenance are just some examples of services required by many industrial customers. These services make up a large part of many industrial companies purchase budget, but, even more importantly, for the supplier these services often make up a substantial proportion of the company's profit. There is also a trend towards the integration of goods and services. However, there is little help available on strategies for the efficient supply or manufacture of such services. An operations strategy should not be limited to supporting just new sales if the after-sales market of industrial services has a large impact on the company's competitive advantage. A complete operations strategy should therefore be linked not only to the marketing strategy, but also to a service strategy of the company. In this paper we take the supplier's view on the task of providing industrial services, i.e. the supply of after-sales services, including tangibles such as spare parts and consumables, related to the maintenance of industrial goods. We focus on the positioning of industrial services relative manufacturing, aiming at an integrated approach for manufacturing and service operations management. We extend the product-profiling concept of Hill to service operations, developing the concept of industrial service profiling, providing a detailed analysis of market and service offering characteristics relative production characteristics. The resulting profile reveals possible mismatches in the existing operations, and can also be used to identify areas in need of corrective actions.
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| 23. |
- Levén, Erik, et al.
(författare)
-
Inventory control with a modified Croston procedure and Erlang distribution
- 2004
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 90:3, s. 361-367
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers an inventory control system, primarily for a finished goods inventory. The purpose is to create a procedure that can handle both fast-moving items with regular demand and slow-moving items. The suggested procedure should be easy to implement in a modern computerized ERP-system. Essentially, the system is a periodic review system built around a Croston forecasting procedure. An Erlang distribution is fitted to the observed data using the mean and variance of the forecasted demand rate. According to probabilities for stock shortages, derived from the probability distribution, the system decides if it is time to place a new order or not. The Croston forecasting method is theoretically more accurate than ordinary exponential smoothing for slow-moving items. However, it is not evident that a Croston forecasting procedure (with assumed Erlang distribution) outperforms ordinary exponential smoothing (with assumed normal distribution) applied in a “practical” inventory control system with varying demand, automatically generated replenishment, etc. Our simulation study shows that the system in focus will present fewer shortages at lower inventory levels than a system based on exponential smoothing and the normal distribution.
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| 24. |
- Lundmark, Robert, et al.
(författare)
-
Estimating and decomposing the rate of technical change in the Swedish pulp and paper industry : A general index approach
- 2004
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 91:1, s. 17-35
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to analyse the rate and the impacts of technical change in the Swedish pulp and paper industry. In contrast to earlier research on this industry we replace the standard time trend with time-specific dummy variables enabling the estimation and decomposing of a general index of technical change. The analysis is made within a Translog cost function model, which is estimated using a panel data set with observations across individual paper and board mills over the time period 1974–1994. Our results indicate that the highest rates of technical change have generally occurred during the latter part of this period. Pure technical change is the primary component that has directed technical change over the entire time period. We also find evidence of non-neutral technical change. Energy use has been stimulated by technical improvements while labour use has been discouraged. Also, technical change has had wastepaper and woodpulp using impacts. However, the magnitudes of these latter impacts are relatively small, implying that the increase in wastepaper use during the last decades has mainly been stimulated by relative price changes.
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| 25. |
- Lööf, Hans, et al.
(författare)
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Knowledge capital and performance heterogeneity : A firm-level innovation study
- 2002
-
Ingår i: International Journal of Production Economics. - : Elsevier B.V. - 0925-5273 .- 1873-7579. ; 76:1, s. 61-85
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is an empirical analysis of knowledge capital and performance heterogeneity at the firm level. We apply new econometric methods to extensive data on innovation and innovative activities in Swedish manufacturing. A number of interesting results emerge. First, the results show that knowledge capital, defined as the ratio of innovation sales to total sales, is found to be a significant factor contributing to performance heterogeneity among firms. This relationship holds even when we control for human capital, type of output, firm size. and the entry. merger., partial closure or exit of firms. Second. knowledge capital rises with innovation input. the firm's internal knowledge for innovation, and co-operation on innovation with domestic universities. Third, when controlling for differences in innovation investments and human capital, knowledge-intensive firms are not more innovative than labor-intensive or capital-intensive firms. Fourth, organizational rigidities in innovation projects and a lack of appropriate investment sources for innovative activities are found to have a negative impact on productivity. Finally, we find a positive association between an outspoken aggressive innovation strategy, customers and a firm's internal resources for innovation and the size of innovation investment.
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| 26. |
- Nilsson, Carl-Henric, et al.
(författare)
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The strategic grounding of competitive advantage – The case of Scania
- 1995
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Ingår i: International Journal of Production Economics. - Amsterdam : Elsevier. - 0925-5273 .- 1873-7579. ; 41:1-3, s. 281-296
-
Tidskriftsartikel (refereegranskat)abstract
- Scania has performed well above average in the heavy truck industry during a considerable time span. Scania’s sources of competitive advantage are presented and their interrelations and significance for the business strategy analysed in order to explain the success of Scania. Strategic issues are traditionally analysed in a top-down procedure starting with the corporate strategy and proceeding by disaggregation of the strategy down in the organisation. This is known as the grand strategy perspective and views strategy as a "chain of causality". We introduce the grounded strategy perspective which views strategy as a "pattern in a stream of decisions and actions", and takes its starting point in the stream of activities within the company. Grounded strategy synthesises the strategy according to a bottom-up procedure. The case of Scania and the heavy truck industry is analysed according to these two different perspectives on strategy. The methodological approach may be different depending on the perspective. The results of the case study from each perspective reveal interesting implications to strategists: scholars as well as practitioners. The grand strategy approach appears to be advantageous for analysis at the higher levels of strategy, while the grounded approach appear to be advantageous at the lower levels of strategy. © 1995.
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| 27. |
- O'Brien, C., et al.
(författare)
-
Structuring and planning operations
- 2003
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 85:3, s. 273-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 28. |
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| 29. |
- Olhager, Jan, 1955-, et al.
(författare)
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Long-Term Capacity Management : Linking the Perspectives from Manufacturing Strategy and Sales and Operations Planning
- 2001
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 69:2, s. 215-225
-
Tidskriftsartikel (refereegranskat)abstract
- Efficient long-term capacity management is vital to any manufacturing firm. It has implications on competitive performance in terms of cost, delivery speed, dependability and flexibility. In a manufacturing strategy, capacity is a structural decision category, dealing with dynamic capacity expansion and reduction relative to the long-term changes in demand levels. Sales and operations planning (S&OP) is the long-term planning of production levels relative to sales within the framework of a manufacturing planning and control system. Within the S&OP, resource planning is used for determining the appropriate capacity levels in order to support the production plan. Manufacturing strategy and sales and operations planning provide two perspectives on long-term capacity management, raising and treating different issues. In this paper, we compare and link them in a framework for long-term capacity management.
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| 30. |
- Olhager, Jan, 1955-
(författare)
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Strategic positioning of the order penetration point
- 2003
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 85:3, s. 319-329
-
Tidskriftsartikel (refereegranskat)abstract
- The order penetration point (OPP) defines the stage in the manufacturing value chain, where a particular product is linked to a specific customer order. Different manufacturing environments such as make-to-stock (MTS), assemble-to-order (ATO), make-to-order (MTO) and engineer-to-order all relate to different positions of the OPP. These may be considered as product delivery strategies, having different implications for manufacturing objectives such as customer service, manufacturing efficiency and inventory investment. Furthermore, the OPP may differ between products and over time for a particular manufacturing firm. In this paper, the positioning of the OPP is treated from a strategic perspective. Market, product, and production factors are identified that affect the OPP positioning and the shifting of the OPP upstream or downstream in the manufacturing value chain. The major factors are demand volume and volatility, and the relationship between delivery and production lead times. These factors are included in a model that allows the manufacturing firm to choose the right product delivery strategy. Different manufacturing strategies must be developed for pre-OPP operations (i.e. upstream, forecast-driven) vs. post-OPP operations (i.e. downstream, customer-order-driven), since these two stages are fundamentally different. As a consequence, a manufacturing firm that has an ATO product delivery strategy must differentiate between MTS operations (upstream the OPP) and MTO operations (downstream the OPP). For example, the competitive priorities differ: price for pre-OPP operations but delivery speed and flexibility for post-OPP operations. Therefore, decision categories, such as production planning and control, and performance measurement must be designed accordingly. Guidelines are provided for this strategic choice. ⌐ 2003 Elsevier Science B.V. All rights reserved.
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| 31. |
- Olhager, Jan, 1955-, et al.
(författare)
-
Supply chain management survey of Swedish manufacturing firms
- 2004
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 89:3, s. 353-361
-
Tidskriftsartikel (refereegranskat)abstract
- Supply chain management practices and principles are evolving and changing rapidly, e.g. through modern information and communication technologies. These changes affect the ways supply chains are designed, the way they are managed, and how planning and control activities take place within these chains. But how far have companies come in dealing with supply chain issues? This paper investigates supply chain management strategies and practices in a sample of 128 Swedish manufacturing firms. We specifically study issues related to the supply chain design, integration, planning and control, and communication tools for managing supply chains. The main findings indicate the following. The extent to which suppliers and customers are involved in supply chain planning and control is expected to increase steadily over the next 2 years. The primary priority for the selection of supply chain partners is quality performance. However, delivery dependability, cost efficiency, volume flexibility, and delivery speed are also judged to be important inputs to the supply chain partner selection process. Today, companies expect to broaden and deepen the use of new information and communication technologies for improving supply chain operations. Our findings concerning future supply chain management practices, principles and priorities are discussed.
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| 32. |
- Olsson, Richard
(författare)
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Subcontract Coordination in Construction
- 1998
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 56-57, s. 503-509
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Tidskriftsartikel (refereegranskat)abstract
- The building industry in Sweden has for the last five years been under hard pressure to reduce costs, and lead times, while at the same time improving quality. During this period the range of services such as air distribution, heating, cooling and electrical systems has continued to increase, creating more complex buildings. Today, we encounter problems with communication, boundaries between subcontractors, too many people in the same place at the wrong time and too little emphasis on the testing phase. In order to meet customer's expectations, to have a fully functional and tested product at a given time, several main contractors in Sweden have started to use a special subcontract coordinator in an effort to reduce problems.The case study method was used to find out how the subcontract coordinator was working, where in the organisation he should be placed and what he adds to the construction process. Studies have been conducted on several types of building projects, varying organisations and geographically spread projects.The need for the subcontract coordinator is clearly stated among all types of participants. The function adds a more holistic outlook in scheduling, communication, troubleshooting and performance testing before project completion. The aim of this study is to provide a guideline for the coordinator's work. The results can be used to achieve a smoother construction phase with a successful project close-out.
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| 33. |
- Persson, Fredrik, 1971-, et al.
(författare)
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Performance simulation of supply chain designs
- 2002
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 77:3, s. 231-245
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Tidskriftsartikel (refereegranskat)abstract
- The focus on supply chain management has increased in recent years, among academics as well as among practitioners. In this paper, we present a supply chain simulation study for a real case, concerned with the manufacturing of mobile communication systems. The purpose of the study is twofold. One objective is to evaluate alternative supply chain designs with respect to quality, lead-times and costs as the key performance parameters. A second objective is to increase the understanding of the interrelationships among these and other parameters, relevant for the design of the supply chain structure. The design alternatives differ in terms of the level of integration and synchronisation between supply chain stages. Modelling and validation issues are highlighted since these are fundamental to a supply chain simulation study. The results are discussed and a model capturing the relationships among cost, quality, and lead-times, based on the simulation study, is presented. ⌐ 2002 Elsevier Science B.V. All rights reserved.
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| 34. |
- Segelod, Esbjörn
(författare)
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A comparison of managers' perceptions of short-termism in Sweden and the U.S
- 2000
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Ingår i: International Journal of Production Economics. - 0925-5273. ; 63:3, s. 243-254
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Tidskriftsartikel (refereegranskat)abstract
- U.S. and U.K. firms have been thought to invest in a more short-term manner than Japanese and German firms. This article uses a questionnaire and interviews to compare U.S. and Swedish top executives' perceptions of short-termism. The study shows that managers in major Swedish groups feel far less pressure from the stock market to perform in the short run, than do their U.S. counterparts. Furthermore, the anticipated market growth and political uncertainty are far more important for the willingness to make long-term investments than is e.g. pressure from the stock market, the cost of capital, or the rate of inflation. Moreover, internal competition for funds can be a factor as important as pressure from the stock market as regards inhibition of long-term investments in diverse groups.
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| 35. |
- Segelod, Esbjörn
(författare)
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A note on the survey of project evaluation techniques in major corporations
- 1998
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 54:2, s. 207-213
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Tidskriftsartikel (refereegranskat)abstract
- Much of what we know about the capital budgeting routines of major corporations derives from postal surveys sent to head offices. This article compares the results gained from such surveys with those obtained from analyses of investment manuals, and interviews with corporate managers in charge of the capital budgeting routines of their groups. The analyses suggest that the value of postal surveys would be substantially improved if information was also collected on to whom and to which parts of the organization an administrative routine is applicable, and on whether it is articulated in a written and approved document; where the routine is applied, by whom, and how strictly.
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| 36. |
- Segelod, Esbjörn
(författare)
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Corporate control of investments and management styles
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273. ; 43:2-3, s. 227-237
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Tidskriftsartikel (refereegranskat)abstract
- This article describes how corporate managers of major Swedish groups in different industries exert control over investment requests and the direction of the investments of their groups, The study is based on interviews with the corporate managers, who are responsible for the capital budgeting procedures of their groups, and analyses of their investment manuals. The article describes what they perceive as their most important means of control, and differences between firms in different lines of industry. These differences can partly be explained by the need to coordinate investments of different kinds and in different parts of the group. The article shows how the design of the resource allocation system depends on the character of the investments and requires a certain management style. This connection between investments, management styles and resource allocation systems shows that there is no ideal resource allocation system optimal for all groups.
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| 37. |
- Segelod, Esbjörn
(författare)
-
Investments and investment processes in professional service groups
- 2000
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Ingår i: International Journal of Production Economics. - 0925-5273. ; 67:2, s. 135-154
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Tidskriftsartikel (refereegranskat)abstract
- This article describes and analyses the size and character of investments, the investment criteria, and the investment processes in some professional service groups. The focus is on means of control used by the corporate level to influence the volume and direction of investments in groups of companies. Comparisons are made with standardized service and manufacturing groups. Professional service groups are of special interest because theirs is a growth industry; moreover many manufacturing groups have become more knowledge-intensive, and have adopted project-based structures similar to those found in professional service groups. The article shows that professional service groups invest just as heavily as do manufacturing firms, but concentrate their investments on training and the development of new knowledge. The principles of investment planning and control are the same as in manufacturing groups, but the means and the weight attached to them differ. Investment requests are initiated on the business unit level and major investment requests are channelled through the executive team system for approval. However, there is no system of defining, requesting and reviewing intangible investments. Rather, review is by projects and units. The focus is on market and social, not administrative, means of control.
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| 38. |
- Segelod, Esbjörn
(författare)
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Resource allocation in a few industries : Determinants and trends
- 2002
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Ingår i: International Journal of Production Economics. - 0925-5273. ; 77:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- When the major corporations divisionalised their organisation after the Second World War, they devised a performance measurement system to monitor the development of their business units, and a capital budgeting system to control the direction of investments. The appraisal of investments was decentralised and capital budgeting became a bottom-up process, standardised through written routines and supervised via a pre-approval control system. Since then, investments in training, R&D, marketing, and information technology have come to comprise a steadily increasing share of total investments. In consequence thereof companies have become flatter, and knowledge-intensive companies, project-based. The importance of the capital budgeting process has declined; indeed it rarely exists in professional service groups. Notwithstanding, the industry does not invest less but concentrates on intangible types of investments. The purpose of this article is to describe and identify the factors which dictate the design of the resource allocation system in a few industries, and thereby perceive the direction in which the development is heading. The analysis identifies five factors which determine the design of the resource allocation system, and shows how this affects the resource allocation system in six industries. It also discusses different means of control and the future trends, and explains why the capital budgeting system becomes less important as industry becomes more knowledge-intensive.
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| 39. |
- Segerstedt, Anders
(författare)
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A capacity-constrained multi-level inventory and production control problem
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 45:1-3, s. 449-461
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a mathematical formulation of a capacity constrained multistage inventory and production control problem. It argues that most practical multistage inventory and production control problems can be summarised in the formulation. The model has a strong connection to the model of Billington, McClain and Thomas (1983) and is also inspired of a paper from Bard and Golany (1991). The revised Billington/McClain/Thomas model is formulated in a dynamic programming recursion. A numerical solution to a simple problem is presented. A scheduling problem concerning capacity constrained models are enlightened. Further, the paper points to differences and relationships between this capacity constrained model, MRP, Kanban and Cover-Time Planning.
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| 40. |
- Segerstedt, Anders
(författare)
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Cover-Time Planning, a method for calculation of material requirements
- 1995
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 41:1-3, s. 355-368
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents Cover-Time Planning, a method for calculation of material requirements. Cover-Time Planning resembles MRP but it lacks its automatic time-phasing ability. Basically Cover-Time Planning is a reorder point system based on demand rates and time instead of quantities.
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| 41. |
- Segerstedt, Anders
(författare)
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Formulas of MRP
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 46-47, s. 127-136
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents MRP in formulas. The usual presentation of the MRP-calculation in textbooks for operations management and production economics in tables are described here in formulas. In the MRP-calculation: first MRP reschedules already open orders to current gross requirements, then MRP calculates and time-phases planned orders to satisfy remaining gross requirements. The MRP-calculation can face an open order with a planned due date in past time, and where the real due date will be some period in the future. Such problems are seldom pointed out in textbooks, but the presented formulas must handle it and similar problems. The paper tries to postulate the “real” MRP-calculation. It is important that we define what we really mean when we talk about MRP, formulas are a supreme method for communication. Furthermore the paper points to the connections between MRP and input-output analyses. Definitions of inefficiencies related to MRP, “remnant stock” and “imbalance”, are discussed with used formulas.
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| 42. |
- Segerstedt, Anders
(författare)
-
Inventory control with variation in lead times, especially when demand is intermittent
- 1994
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 35:1-3, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a model for inventory control where variation in lead times is allowed. No reorder point is computed. The mean value and the variance for the time between withdrawals, the order size and the lead time are measured by exponential smoothing. These variables are assumed to be Gamma distributed. Together with the constants: the inventory on hand plus on-order, passed time since the last withdrawal and time to the next inspection; the probability for a shortage is calculated. If the probability is greater than the service level requires then a replenishment order must be placed.
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| 43. |
- Segerstedt, Anders
(författare)
-
Lot sizes in a capacity constrained facility with available initial inventories
- 1999
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 59:1-3, s. 469-475
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an heuristic method for deciding what items and what order sizes to produce in a capacity constrained facility. The available inventories on hand decide in what order the production should be performed for avoiding shortages. The recursion procedure finds the same solution to the Bomberger (Management Science 12 (11) (1996) 778–784) problem as Doll and Whybark (Management Science 20 (1) (1973) 50–55).
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| 44. |
- Stehn, Lars, et al.
(författare)
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Integrated design and production of multi-storey timber frame houses – production effects caused by customer-oriented design
- 2002
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 77:3, s. 259-269
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results from an ongoing R and D project aiming for an industrialised development of a multi-storey timber frame house system. The development was conducted systematically using methods from concurrent engineering (CE) focusing on the customer satisfaction and production-design problems/possibilities. A Swedish SME building company was investigated from the viewpoint of customer orientation, production and design of multi-storey timber frame houses. The company uses industrial fabrication of volumes. The aim was to analyse how the production can benefit from an integration of a customer-oriented design and production. First, a model based on the QFD method is proposed on how requirements from customers, i.e., tenants, can be taken into account in the design process and how CE can be adapted to a SME design process. Second, a preliminary model is proposed considering disturbances and relative cost effects on the production due to changes in the design solutions. The presented model aims to predict the total cost for a customer affected design on the used building system to forecast the costs for the main contractor and building owner for a similar integrated design in the future. All observations are based on case studies of the design process and the industrialised production of a three-storey timber frame house with three different floor designs.
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| 45. |
- Tang, Ou, et al.
(författare)
-
Planning and replanning the master production schedule under demand uncertainty
- 2002
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 78:3, s. 323-334
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Tidskriftsartikel (refereegranskat)abstract
- The Master Production Schedule (MPS) is essential in maintaining customer service levels and stabilising production planning in a Material Requirements Planning (MRP) environment. Traditionally, an MPS is derived from a demand forecast and aggregate production plan but the associated cost to cover demand uncertainty is usually not considered. Another difficulty in the MPS is its planning frequency. Frequent changes in the MPS reduce productivity whereas a long-term frozen MPS results in a poor service level and an unfavourable inventory situation. This paper first investigates the possibility to establish a method for planning the MPS under stochastic demand. Secondly, it aims to evaluate the value of replanning actions. Finally, it provides a model for estimating appropriate MPS parameters such as the length of the replanning interval and the length of the interval to freeze the plan. © 2002 Elsevier Science B.V. All rights reserved.
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| 46. |
- Tang, Ou, et al.
(författare)
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The detailed coordination problem in a two-level assembly system with stochastic lead times
- 2003
-
Ingår i: International Journal of Production Economics. - : Elsevier. - 0925-5273 .- 1873-7579. ; 81-82, s. 415-429
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, we study the detailed coordination problem in a two-level assembly system with stochastic lead times for lower-level items and constant and deterministic demand for the finished item. General formulae are developed for solving the optimal planned lead times with the objective to minimise total stockout and inventory holding costs. Consequently, we obtain the optimal safety lead time, which is the difference between planned and expected lead time. A solution procedure for the optimal planned lead times is discussed. Numerical examples are then given to illustrate the model. Moreover, the influence of the mean value and variance of actual lead times on the system performance and optimal control variables (such as the total cost of the system and planned lead times) is studied using our numerical results. © 2002 Elsevier Science B.V. All rights reserved.
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| 47. |
- Wikner, Joakim, et al.
(författare)
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Smoothing Supply Chain Dynamics
- 1991
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Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 22:3, s. 231-248
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Tidskriftsartikel (refereegranskat)abstract
- A three-echelon Forrester production distribution system is used as a supply chain reference model for comparing various methods of improving total dynamic performance. Many authors have exploited the original simulation results for the nominal system, especially when describing problems associated with supply chain behaviour. However, few of these authors have attempted to produce a dynamically superior supply chain as distinct from offering detailed organisational and attitudinal changes needed to achieve any improvement. As the starting point of this paper, the production-distribution system has been transformed into a block diagram representation capable of considerable simplification. A combination of analysis and simulation can then be used to gain a far deeper understanding of the system dynamics than has so far been published. Thus, although the Forrester model is far from optimal, it does provide a well established benchmark against which proposals may be evaluated. For the purpose of illustration, five different approaches are then used to improve the supply chain dynamics. These are-“fine tuning” the existing ordering policy parameters;-reducing system delays;-removal of the distribution echelon;-changing the individual echelon decision rules;-better use of information flow throughout the supply chain.It is shown that by better utilisation of the information flow, significant reductions in the demand amplification can be achieved without substantial expenditure. This is because it is only necessary to separate out the flow of “real” orders from “system” orders as they are passed up the chain. Such collaboration does, however, correspond to the establishment of an integrated supply chain in which the concept of “total system stocks” is accepted.
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| 48. |
- Zackrisson, Jesper, et al.
(författare)
-
Quality by a step-by-step program in low scale industries
- 1995
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 41:1-3, s. 419-427
-
Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the effectiveness of the on-line QC in the low scale or experience industries. The basis of the study is the manufacturing process of trams in Sweden. The result indicates that the QC program demands a solid base to be effective from the beginning of its implementation. Empirical results show that during the off-line process the lead-time in the production was reduced by 50% and the mean cycle time of the storage is decreased by 33%. Formally, quality tools are investigated as regards the scale of the industry.
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| 49. |
- Zhou, Li, et al.
(författare)
-
Analysis of the effect of commonality in multi-level inventory systems applying MRP theory
- 2004
-
Ingår i: International Journal of Production Economics. - 0925-5273 .- 1873-7579. ; 90:2, s. 251-263
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Tidskriftsartikel (refereegranskat)abstract
- Commonality, i.e. using the same type of component in different locations of product structure trees, is frequently encountered in manufacturing industries. It has long been known that using a common component can reduce the cost of safety stock. Basically, taking commonality into account can reduce the inventory level, shorten the time for reaching the market, decrease the set-up time, increase productivity, and improve flexibility. However, using the same component in different locations might require that the component is made more flexible and, therefore, more expensive as compared to choosing tailor-made items for its respective locations. The manufacturing cost of commonality items may therefore be much higher because of its greater number of functions. So, there may be a balance to be struck between the value of the advantage of commonality, and the cost of its disadvantage. This paper focuses on the effect of commonality in multi-level production-inventory systems, especially assembly systems. The basic balance equations of MRP theory, using input-output analysis together with the Laplace transform, are used for comparing the cases when commonality is disregarded, on the one hand, and when commonality is taken into account, on the other. Applying the net present value as the objective function, conclusions are derived in the form of conditions for when commonality is recommended, and when not. © 2003 Elsevier B.V. All rights reserved.
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| 50. |
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