| 1. |
- Sakao, Tomohiko, 1969-, et al.
(författare)
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Addressing Uncertainty as a Key for Successful Integrated Product and Service Offerings : Literature Review and Company Interview
- 2008
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Ingår i: Swedish Production Symposium,2008. ; , s. 253-260
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Konferensbidrag (refereegranskat)abstract
- Services are getting increasingly important in the manufacturing industries today. As a result, it has become common for companies to provide a combination of services and products as an integrated offering. This paper focuses on such business models and development processes. It explores the current status and needs of industries on those issues. Through reviewing 12 journal articles tackling these issues and complementary academic contributions, it was found that uncertainty is a critical concept to be addressed properly. Based on this result, nine Swedish companies interested in such business were interviewed on this issue. The matured providers raised convincing customers as their major challenges while others consider understanding the internal meaning of IPSO business is their current challenge. In addition, there is a wish to have a quantitative tool for companies to utilize upon developing such offerings.
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| 2. |
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| 3. |
- Gao, Song, et al.
(författare)
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Comparative relation mining of customer reviews based on a hybrid CSR method
- 2023
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Ingår i: Connection science (Print). - : Taylor & Francis. - 0954-0091 .- 1360-0494. ; 35:1
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Tidskriftsartikel (refereegranskat)abstract
- Online reviews contain comparative opinions that reveal the competitive relationships of related products, help identify the competitiveness of products in the marketplace, and influence consumers’ purchasing choices. The Class Sequence Rule (CSR) method, which is previously commonly used to identify the comparative relations of reviews, suffers from low recognition efficiency and inaccurate generation of rules. In this paper, we improve on the CSR method by proposing a hybrid CSR method, which utilises dependency relations and the part-of-speech to identify frequent sequence patterns in customer reviews, which can reduce manual intervention and reinforce sequence rules in the relation mining process. Such a method outperforms CSR and other CSR-based models with an F-value of 84.67%. In different experiments, we find that the method is characterised by less time-consuming and efficient in generating sequence patterns, as the dependency direction helps to reduce the sequence length. In addition, this method also performs well in implicit relation mining for extracting comparative information that lacks obvious rules. In this study, the optimal CSR method is applied to automatically capture the deeper features of comparative relations, thus improving the process of recognising explicit and implicit comparative relations.
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| 4. |
- Grubbström, Robert W., 1941-, et al.
(författare)
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An Overview of Input-Output Analysis Applied to Production-Inventory Systems
- 2000
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Ingår i: Economic Systems Research. - : Informa UK Limited. - 0953-5314 .- 1469-5758. ; 12:1, s. 3-25
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Tidskriftsartikel (refereegranskat)abstract
- Input-Output Analysis, together with the Laplace transform, have been applied to multi-level, multi-period production-inventory systems in a number of papers. This article gives a historical overview of the areas involved in these studies. It is shown that the input and output matrices as well as the Leontief inverse can be generalised to include timing properties for the inputs by means of the Laplace transform. The consequent advantages are exemplified in different production models, treating, for instance, capacity requirements and safety stock problems. The main literature in this field concerns assembly systems, but the approach is easily applicable to process industries with a divergent material flow or when feedback is essential.
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| 5. |
- 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
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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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| 6. |
- Grubbström, Robert W., 1941-, et al.
(författare)
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Modelling Rescheduling Activities in a Multi-Period Production-Inventory System
- 2000
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Ingår i: International Journal of Production Economics. - : Elsevier. - 0925-5273 .- 1873-7579. ; 68:2, s. 123-135
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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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| 7. |
- Grubbström, Robert W., 1941-, et al.
(författare)
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The moments and central moments of a compound distribution
- 2005
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 170:1, s. 106-119
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Tidskriftsartikel (refereegranskat)abstract
- The compound distribution is of interest for the study of production/inventory problems, since it provides a flexible description of the stochastic properties of the system. However, due to the difficulties involved in obtaining analytical results for the compound distribution, studies are usually limited to searching for a good approximation by replacing a more complex model with a simpler one applying only the first few moments as parameters. This paper presents general closed form formulae for the moments and central moments of any order of a compound distribution made up of non-negative stochastic variables. The Laplace and z-transform methods play an important role in this study. The importance of taking into consideration higher-order moments, when computing a safety factor for inventory control, is illustrated in a numerical example. © 2004 Elsevier B.V. All rights reserved.
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| 8. |
- Hagenbjörk, Johan, 1985-
(författare)
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Optimization-Based Models for Measuring and Hedging Risk in Fixed Income Markets
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The global fixed income market is an enormous financial market whose value by far exceeds that of the public stock markets. The interbank market consists of interest rate derivatives, whose primary purpose is to manage interest rate risk. The credit market primarily consists of the bond market, which links investors to companies, institutions, and governments with borrowing needs. This dissertation takes an optimization perspective upon modeling both these areas of the fixed-income market. Legislators on the national markets require financial actors to value their financial assets in accordance with market prices. Thus, prices of many assets, which are not publicly traded, must be determined mathematically. The financial quantities needed for pricing are not directly observable but must be measured through solving inverse optimization problems. These measurements are based on the available market prices, which are observed with various degrees of measurement noise. For the interbank market, the relevant financial quantities consist of term structures of interest rates, which are curves displaying the market rates for different maturities. For the bond market, credit risk is an additional factor that can be modeled through default intensity curves and term structures of recovery rates in case of default. By formulating suitable optimization models, the different underlying financial quantities can be measured in accordance with observable market prices, while conditions for economic realism are imposed.Measuring and managing risk is closely connected to the measurement of the underlying financial quantities. Through a data-driven method, we can show that six systematic risk factors can be used to explain almost all variance in the interest rate curves. By modeling the dynamics of these six risk factors, possible outcomes can be simulated in the form of term structure scenarios. For short-term simulation horizons, this results in a representation of the portfolio value distribution that is consistent with the realized outcomes from historically observed term structures. This enables more accurate measurements of interest rate risk, where our proposed method exhibits both lower risk and lower pricing errors compared to traditional models.We propose a method for decomposing changes in portfolio values for an arbitrary portfolio into the risk factors that affect the value of each instrument. By demonstrating the method for the six systematic risk factors identified for the interbank market, we show that almost all changes in portfolio value and portfolio variance can be attributed to these risk factors. Additional risk factors and approximation errors are gathered into two terms, which can be studied to ensure the quality of the performance attribution, and possibly improve it.To eliminate undesired risk within trading books, banks use hedging. Traditional methods do not take transaction costs into account. We, therefore, propose a method for managing the risks in the interbank market through a stochastic optimization model that considers transaction costs. This method is based on a scenario approximation of the optimization problem where the six systematic risk factors are simulated, and the portfolio variance is weighted against the transaction costs. This results in a method that is preferred over the traditional methods for all risk-averse investors.For the credit market, we use data from the bond market in combination with the interbank market to make accurate measurements of the financial quantities. We address the notoriously difficult problem of separating default risk from recovery risk. In addition to the previous identified six systematic risk factors for risk-free interests, we identify four risk factors that explain almost all variance in default intensities, while a single risk factor seems sufficient to model the recovery risk. Overall, this is a higher number of risk factors than is usually found in the literature. Through a simple model, we can measure the variance in bond prices in terms of these systematic risk factors, and through performance attribution, we relate these values to the empirically realized variances from the quoted bond prices.
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| 9. |
- Li, Dong, et al.
(författare)
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Improve food retail supply chain operations with dynamic pricing and product tracing
- 2006
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Ingår i: International Journal of Services Operations and Informatics. - : InderScience Publishers. - 1741-539X .- 1741-5403. ; 1:4, s. 347-362
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the potential value adding capability of dynamic product tracing to the food supply chain management. As the environment of supply chain processes affect product quality significantly, technologies and approaches for tracking and tracing products have the potential to improve the food supply chain performance by dynamically identifying product quality situations. This can be achieved by tracing the product manufacturing and supply process with Automatic Product Identification (AutoID) technologies. An optimisation model has been developed to generate optimal pricing policies based on the dynamically identified product quality information. The research concluded that the dynamic identification of the product value (quality) would generate benefits to the food supply chain management with widely adopted optimal pricing approaches.
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| 10. |
- Li, Lin, et al.
(författare)
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Backroom effect on perishable inventory management with IoT information
- 2023
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Ingår i: International Journal of Production Research. - : TAYLOR & FRANCIS LTD. - 0020-7543 .- 1366-588X. ; 61:12, s. 4157-4179
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Tidskriftsartikel (refereegranskat)abstract
- We introduce an original concept of the backroom effect for perishable products when the deterioration rate in a backroom is lower than that on retail shelves. With IoT-generated real-time information about the perishable products, this phenomenon has a significant impact on joint shelf-space and inventory decisions. We define the deterioration rate gap, formulate the perceived on-shelf product freshness, and describe the freshness-dependent demand distribution, with continuous backroom-shelf replenishment. Assuming that demand depends on both perceived freshness and shelf level, we develop a decision-making model that simultaneously determines the inventory replenishment policy and the shelf space allocation for multiple items. To facilitate the solution process, we propose a hybrid solution approach by combining genetic algorithm (GA) and variable neighbourhood search (VNS). The results provide a prioritised inventory policy for item selection that incorporates the deterioration improvement. The results of the performance analysis show that a policy considering the backroom effect achieves increased profit when the backroom/shelf deterioration gap increases. The optimal solutions for the problems with large backroom/shelf gap also show that the practitioner should increase the ordering quantity, which is contradictory to the outcome of traditional models.
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