| 1. |
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| 2. |
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| 3. |
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| 4. |
- Abdul-Jalbar, Beatriz, et al.
(författare)
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A new heuristic to solve the one-warehouse N-retailer problem
- 2010
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Ingår i: Computers & Operations Research. - : Elsevier BV. - 0305-0548 .- 1873-765X. ; 37:2, s. 265-272
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Tidskriftsartikel (refereegranskat)abstract
- We deal with a multi-echelon inventory system in which one warehouse supplies an item to multiple retailers. Customer demand arrives at each retailer at a constant rate. The retailers replenish their inventories from the warehouse that in turn orders from an outside supplier. It is assumed that shortages are not allowed and lead times are negligible. The goal is to determine replenishment policies that minimize the overall cost in the system. We develop a heuristic to compute efficient policies, which also can easily be used in a spreadsheet application. The main idea consists of finding a balance between the replenishment and the inventory holding costs at each installation. This new heuristic we compare with two other approaches proposed in the literature; the computational studies show that in most of the instances generated the new method provides lower costs.
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| 5. |
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| 6. |
- 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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| 7. |
- Alnestig, Peter, et al.
(författare)
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Produktkalkyler
- 1997. - 2. utg.
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Bok (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Alnestig, Peter, et al.
(författare)
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Produktkalkyler
- 2008
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Bok (populärvet., debatt m.m.)
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| 9. |
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| 10. |
- Brander, Pär, et al.
(författare)
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Economic lot scheduling problems incorporating a cost of using the production facility
- 2009
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 47:13, s. 3611-3624
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers scheduling the production of several different items on a single machine with constrained capacity, commonly known as the Economic Lot Scheduling Problem (ELSP). Most traditional approaches for the ELSP consider the sum of the setup cost and inventory holding cost and provide cyclic schedules that minimize this sum. In practice, there are not only costs for setups and inventory holding, but also costs for operating the production facility due to e.g. electricity, service, maintenance, tools, operators etc, which depend on the number of hours the facility is operating per working day. In this paper, we modify the traditional cost function to include not only setup and inventory holding cost but also a time variable cost for operating the production facility. The paper shows it is possible to adapt a previous heuristic procedure to this complemented cost. The model can help to determine cyclic schedules and the number of production hours per working day.
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| 11. |
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| 12. |
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| 13. |
- Brander, Pär, et al.
(författare)
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Lot sizes in a capacity constrained facility : a simulation study of stationary stochastic demand
- 2005
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 93-94:Spec. issue, s. 375-386
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the scheduling of several different items on a single machine, in literature known as the economic lot scheduling problem, ELSP. One of the characteristics of this problem is that the demand rate is deterministic and constant. However, in a practical situation demand usually varies. In this paper we examine if a deterministic model can be used if demand is stationary stochastic. A dynamic programming approach from Bomberger (Manage. Sci. 12(11) (1966) 778) and a heuristic method from Segerstedt (Int. J. Production Econom. 59(1–3) (1999) 469) are used to calculate lot sizes for four items. The production of these items is simulated with different variations in demand rates. Our conclusion is that a deterministic model of this kind can be used in a practical situation where the demand rate is stationary stochastic, but the models must be complemented by a decision rule; which item to produce and when to produce it. In our tests the heuristic method and the dynamic programming approach perform rather similarly with respect to costs and inventory levels, but the dynamic programming approach results in more backorders when there is small variation in demand rates. This study indicates that the model used for determination of lot sizes is of less importance than the decision rule used for identification of the item to produce and when to produce it.
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| 14. |
- Chronéer, Diana, et al.
(författare)
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Planering och styrning av byggprojekt : Platschefers versioner
- 2011
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Ingår i: PLANs Forsknings- och tillämpningskonferens 2011 – Logistik i praktisk tillämpning. - Stockholm : Logistikföreningen Plan. - 9789197644457 ; , s. 71-80
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ett antal platschefer och arbetschefer i olika byggbolag har intervjuats. De har presenterat sina tankegångar och idéer om vad som är svårt och vad som är lätt i olika byggprojekt. Det som diskuterats är för och nackdelar med olika entreprenadformer, ackord, 3D-modellering, olika hjälpmedel som används, historisk kontra framtida utveckling m.m. Ett byggprojekt är ett logistiskt problem och utmaning, material skall in, men material skall oftast även ut och bort. Den inledande planeringen, val av byggmetod och arbetsplatsen organisering, var byggbaracker och materialupplag placeras är mycket viktig för att byggprojektet kan genomföras på ett effektivt sätt. Ett flertal andra konstateranden presenteras också.
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| 15. |
- Eriksson, Sune, et al.
(författare)
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Varför sysselsättningen minskar trots ökande produktion : om sambandet teknisk utveckling, produktivitet, sysselsättning och kapitalbehov
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Så gott som dagligen når oss nyheter om den tekniska utvecklingen, dess nya produkter, effektivare produktionsmetoder och nya tillämpningsområden. Allt kostnadseffektivare tekniska produktionsmedel underlättar och ersätter den mänskliga arbetskraften i allt fler funktioner. Produktiviteten ökar. Endast i undantagsfall omnämns att behovet av mänsklig arbetskraft – och kapital – för given produktion, minskar med ökande produktivitet. Så här skriver Svenska Arbetsgivareföreningen i Aftonbladets bok 1900-TALET: "Under 1900-talet har Sverige blivit ett bättre land att leva i. Arbetstiden har nära nog halverats, samtidigt som vi producerar tio gånger mer per innevånare." I sin bok Vetenskapen och förnuftet skriver den finske filosofen professor Georg Henrik von Wright: "Det är också en självklarhet, som bara den som sluter ögonen kan undgå att inse, att en fortgående minskning av den nödvändiga mänskliga arbetsinsatsen inte kan på sikt kompenseras av en ständig ökning av summan producerade varor och tjänster. Tillväxtens gräns sätts, om inte av resurserna så av konsumtionen." Den tekniska utvecklingen fortsätter – och sprids – kanske i snabbare takt än hittills. Vilka blir följderna för samhället?
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| 16. |
- Frenckner, Paulsson, et al.
(författare)
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Motiverat vägval : vid avhandlingar i företagsekonomi
- 2001
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Rapport (populärvet., debatt m.m.)abstract
- Ett vetenskapligt arbete bör ge ett bidrag till kunskapen om de frågor som det behandlar. Bidraget bör ha uppnåtts på ett förtroendeingivande sätt. Detta fordrar en noggrann och motiverad "snitsling" av vägen från ämnesval fram till resultat, uttolkning och slutsatser.Syftet med detta arbetspapper är:• att påminna om många av de praktiska hänsyn som kan behöva tas vid utarbetandet av vetenskapliga arbeten;• att ge uttryck för någorlunda allmänt accepterade krav på avhandlingar;• att ge mina personliga råd till den doktorand, främst inom företagsekonomi som känner osäkerhet inför uppgiften;Framställningen är inriktad på arbetsmetodiken i det vetenskapliga arbetet. För vetenskapsteoretiska frågor hänvisas läsaren till mer djupgående läroböcker om forskningsmetodik, modellkonstruktioner och datainsamling, enkät- och intervjuteknik m.m.
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| 17. |
- Hageback, Charlotte, et al.
(författare)
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The need for co-distribution in rural areas : a study of Pajala in Sweden
- 2004
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 89:2, s. 153-163
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Tidskriftsartikel (refereegranskat)abstract
- To be a part of a supply chain network a company competing on the global market must mostly show short lead times and deliver at the right time. Is this really possible for a company placed in a rural or sparsely populated area? Pajala, a village and a municipality in the north of Sweden, has 7500 inhabitants in an area of 7900 km2 which means one inhabitant per km2. The number of inhabitants in the municipality of Pajala is decreasing. To stop this problem, Pajala needs more work opportunities and therefore they need more successful companies. Approximately 20 different conveyers/suppliers transport goods to and from companies in Pajala. But most of the conveyers/suppliers transport goods only once a week. Companies in Pajala, to be able to compete and be a part in a supply chain and a chain that competes with other supply chains, should have the opportunity to send and receive goods any day they want for shortening the delivery times to customers. One solution to this may be co-distribution. Co-distribution means that different conveyers/suppliers transport their goods in only one truck that goes for example in this case to and from Pajala. A preliminary study has been performed in Pajala to investigate if co-distribution has any benefits in rural areas. We find that the companies receive and distribute goods with a low frequency and that the trucks carrying loads to and from Pajala are often loaded less than 50%. This implies that to lower transportation costs and increase delivery services some sort of co-distribution is necessary to strengthen the capability of competing for the companies in Pajala. We have here studied specifically Pajala but we are convinced we would find almost the same result if we had studied other municipalities in rural areas of Sweden.
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| 18. |
- Helleday, Ragnberth, et al.
(författare)
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Exploring the time dependence of serum clara cell protein as a biomarker of pulmonary injury in humans.
- 2006
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Ingår i: Chest. - : Elsevier BV. - 0012-3692 .- 1931-3543. ; 130:3, s. 672-5
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Tidskriftsartikel (refereegranskat)abstract
- We have previously demonstrated Clara cell protein (CC16) [secretoglobin 1A1] in serum to be a highly sensitive biomarker of altered lung epithelial permeability after ozone challenge. As a previous experimental study has indicated a diurnal variation in serum CC16 in humans, the aims of the present investigation were to confirm this observation and to attempt to model the diurnal variation in CC16 concentrations. In 18 healthy nonsmoking subjects, peripheral blood samples were drawn at six sampling points over a 15-h period and repeated twice within 3 to 4 weeks. A clear within-day variation was revealed in serum CC16 concentrations, falling significantly from baseline levels between the 11:30 am and 10:00 pm time points (p = 0.000). Furthermore, it was shown that this within-day variation was reproducible regardless of subject or day, enabling the diurnal variation in serum CC16 to be modeled and fitted a second-degree polynomial for the observed time span. In conclusion, the present data demonstrate a pronounced time-dependent diurnal variation in serum levels of CC16, which can be mathematically compensated for, when addressing the issue of an air pollution-induced effect on CC16 in field studies.
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| 19. |
- Holmbom, Martin, et al.
(författare)
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A solution procedure for Economic Lot Scheduling Problems even in high utilisation facilities
- 2013
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 51:12, s. 3765-3777
-
Tidskriftsartikel (refereegranskat)abstract
- Economic lot scheduling problem (ELSP) handles the problem of deciding what order quantities to use when different products/items are produced in the same capacity constrained production facility. It has previously been shown, and it is shown in this article, that it is possible to find a feasible solution fulfilling true feasibility conditions. However, if the utilisation of the production facility is high the production often has to start before the inventory reaches zero to avoid future shortages. Such ‘early starts’ creates an extra inventory holding cost that the traditional approximation for the inventory holding cost does not account for. This article presents an iterative solution procedure that computes the true inventory holding cost and minimises the total costs. Contrary to previous solution procedures, this procedure requires that the production is scheduled in detail. The heuristic solution procedure is illustrated by a numerical example, it is programmed in MATLAB and variants of the problem are presented.
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| 20. |
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| 21. |
- Holmbom, Martin, et al.
(författare)
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Economic Order Quantities in Production : From Harris to Economic Lot Scheduling Problems
- 2014
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 155, s. 82-90
-
Tidskriftsartikel (refereegranskat)abstract
- This article provides a short historical overview from Harris and his Economic Order Quantity (EOQ) formula to the Economic Lot Scheduling Problem (ELSP). The aim is to describe the development of the ELSP field from the EOQ formula to the advanced methods of today in a manner that suits master and graduate students. The article shows the complexities, difficulties and possibilities of scheduling and producing several different items in a single production facility with constrained capacity. The items have different: demand, cost, operation time and setup time. Setup time consumes capacity and makes the scheduling more complicated. Idle time makes the scheduling easier but is bad from a practical point of view since it creates unnecessary costs due to low utilisation of the facility. A heuristic solution method is used on a small numerical example to illustrate different solution approaches. The solution method creates a detailed schedule and estimates the correct setup and inventory holding cost even if the facility works close to its capacity.
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| 22. |
- Holmbom, Martin, et al.
(författare)
-
Planering och styrning av hemtjänsten i Jokkmokk
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna skrift är en sammanfattning och aktuell konklusion av vårt studiebesök vid hemtjänsten i Jokkmokk 10 och 11 december 2013. Tanken var att vi eventuellt med ruttplanering skulle minska bilkörningen och energiförbrukningen. Vår slutsats är att enkla tumregler och uppföljningar, som presenteras nedan, i det system som redan finns, är att föredra jämfört med dyr avanserad datoriserad ruttplanering. Vi kommenterar historisk utveckling, systemleverantörers ansvar, matdistribution, andra system för hemtjänst mm.
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| 23. |
- Kilpala, Heli, et al.
(författare)
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Analysis of ICT use in the Barents region : research findings from logistics service providers and forest industry
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Efficient logistics is a major aspect in the competitiveness of the companies in the Barents Region because their customers are typically located far away from the region. This study focuses on the Logistics Service Provider (LSP) and the forest industries in the Barents region. The LSPs are important facilitators of trade whose role has increased with the prevailing outsourcing trends of the industries. The appropriate use of Information and Communication Technologies (ICT) provides one means to support the competitive strategies of the LSPs in the Barents region, where the sector is typically composed of small and medium-sized LSPs. To date, the role and competitive developing processes of small and medium-sized LSPs have not been extensively studied and there is very little information on the ICT capabilities and practices in the sector. The research provides general information on the types of LSPs that are found in the Barents region (number of companies, industry trends, company cooperation practices etc.) and studies the current status of ICT implementation in the industry. In particular, the perceived motivators and barriers for ICT implementation are of interest. A survey is conducted in Barents area Finland, Norway, and Sweden, resulting in a total of 168 responses. The results indicate that majority of the LSPs are familiar with computer technology and have some ICT tools available. The surveyed Norwegian LSPs are most “technology-oriented” overall, but the conclusion does not hold for all technology tools. In order to better understand the ICT implementation from the supply chain management perspective, the Russian forest sector is studied in more detail. A total of 9 qualitative interviews are conducted with companies in or related to the Russian forest industry. Overall, the ICT implementation is in a very incipience stage in forestry in Russia. Nonunderstanding of benefits that could be obtained using ICT was mentioned as the main barrier for development of ICT competence. The lack of IT-skilled specialists in Kostomuksha, where majority of the interviews took place, was mentioned as one of the obstacles for a more wide-spread use of ICT in forestry.
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| 24. |
- Lagerkvist, Birgitta Json, et al.
(författare)
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Pulmonary epithelial integrity in children: relationship to ambient ozone exposure and swimming pool attendance.
- 2004
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Ingår i: Environmental health perspectives. - 0091-6765. ; 112:17, s. 1768-71
-
Tidskriftsartikel (refereegranskat)abstract
- Airway irritants such as ozone are known to impair lung function and induce airway inflammation. Clara cell protein (CC16) is a small anti-inflammatory protein secreted by the nonciliated bronchiolar Clara cells. CC16 in serum has been proposed as a noninvasive and sensitive marker of lung epithelial injury. In this study, we used lung function and serum CC16 concentration to examine the pulmonary responses to ambient O3 exposure and swimming pool attendance. The measurements were made on 57 children 10-11 years of age before and after outdoor exercise for 2 hr. Individual O3 exposure was estimated as the total exposure dose between 0700 hr until the second blood sample was obtained (mean O3 concentration/m3 times symbol hours). The maximal 1-hr value was 118 microg/m3 (59 ppb), and the individual exposure dose ranged between 352 and 914 microg/m3hr. These O3 levels did not cause any significant changes in mean serum CC16 concentrations before or after outdoor exercise, nor was any decrease in lung function detected. However, children who regularly visited chlorinated indoor swimming pools had significantly lower CC16 levels in serum than did nonswimming children both before and after exercise (respectively, 57 +/- 2.4 and 53 +/- 1.7 microg/L vs. 8.2 +/- 2.8 and 8.0 +/- 2.6 microg/L; p < 0.002). These results indicate that repeated exposure to chlorination by-products in the air of indoor swimming pools has adverse effects on the Clara cell function in children. A possible relation between such damage to Clara cells and pulmonary morbidity (e.g., asthma) should be further investigated.
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| 25. |
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| 26. |
- Levén, Erik, et al.
(författare)
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A scheduling policy for adjusting economic lot quantities to a feasible solution
- 2007
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 179:2, s. 414-423
-
Tidskriftsartikel (refereegranskat)abstract
- A heuristic scheduling policy is introduced for a multi-item, single-machine production facility. The scheduling policy uses the presumed optimal order quantities derived from solving an Economic Lot Size Problem and checks that the quantities obtain a feasible production schedule according to current inventory levels and expected demand rates. If not, the scheduling policy modifies the order quantities to achieve a possible solution without shortages. The scheduling policy is inspired by modification of the similar heuristic Dynamic Cycle Lengths Policy by Leachman and Gascon from 1988, 1991. The main characteristics of this scheduling policy are successive batches of the same item are treated explicitly, due to that it is quite possible that one item be manufactured several times before one other item is manufactured once more; the batches are ordered in increasing run-out time; if the existing situation creates stock-outs with ordinary order quantities, then the order quantities are decreased with a common scaling factor to try to prevent inventory shortages; in case the decrease of the order quantities changes expected run-out times, the batches are reordered after new run-out times; no filling up to an explicit inventory level is done, the filling up is done by the desirable order quantity; to prevent possible excess inventory the policy suggests time periods where no production should be performed. The scheduling policy contains no economical evaluation; this is supposed to be done when the order quantities are calculated, the policy prevents shortages and excess inventory. A numerical example illustrates the suggested scheduling policy. Finally, it is discussed as to how the policy can also take into account stochastic behaviour of the demand rates and compensate the schedule by applying appropriate safety times.
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| 27. |
- Levén, Erik, et al.
(författare)
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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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| 28. |
- Levén, Erik, et al.
(författare)
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Polarica’s wild berries : an example of a required storage capacity calculation and where to locate this inventory
- 2004
-
Ingår i: Supply chain management. - : Emerald. - 1359-8546 .- 1758-6852. ; 9:3, s. 213-218
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Tidskriftsartikel (refereegranskat)abstract
- Polarica is a company in northern Europe buying, refining and selling wild berries and other specialty foods. During the last couple of years the volume of wild berries, mostly blueberries, has increased a lot. This expansion forces Polarica to consider investments in freezing-in capacity and cold-storage capacity. A simple heuristic model was constructed, from which it was concluded that additional volumes of frozen blueberries require more storage facilities and it was also recommended that the location should be based on load-distance analysis. The way this problem is tackled and solved can be copied and hopefully it presents ideas for other similar studies.
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| 29. |
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| 30. |
- Liu, Biyu, et al.
(författare)
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A min–max solution to optimise planned lead time in a remanufacturing system
- 2019
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Ingår i: International Transactions in Operational Research. - : John Wiley & Sons. - 0969-6016 .- 1475-3995. ; 26:2, s. 485-506
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Tidskriftsartikel (refereegranskat)abstract
- Determining a rational planned lead time (PLT) is a critical and difficult problem in production planning, especially for a remanufacturing system. This paper considers an optimisation problem of the PLT in a make-to-order remanufacturing system to coordinate disassembly–remanufacturing–reassembly and to improve performance. This optimisation model is designed to determine the PLT that minimises the inventory holding and shortage costs. Given the unknown distribution of remanufacturing time but with known first and second moments, this model is solved by a min–max approach, which can capture distributions with the same first and second moments. How the PLT and total cost are affected by yield rate with different first and second moments, unit holding cost, unit shortage cost and purchasing lead time are also investigated through numerical examples in this paper. The results of this study are shown to be consistent with practice and can be a support to decision-making in production planning and scheduling for remanufacturing.
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| 31. |
- Liu, Biyu, et al.
(författare)
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Effects of carbon emission regulations on remanufacturing decisions with limited information of demand distribution
- 2015
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 53:2, s. 532-548
-
Tidskriftsartikel (refereegranskat)abstract
- Policy-makers are developing regulation policies to drive down carbon emissions from industries. Independent remanufacturers (IRs), which remanufacture recycled products/components/parts, must manage and evaluate economic costs generated by the production under future carbon emission regulations. We present three optimisation models to determine the remanufacturing quantity that maximises the total profits under three common carbon emission regulation policies: (a) mandatory carbon emissions capacity, (b) carbon tax and (c) cap and trade. These models include sales revenue, remanufacturing cost, disposal cost, inventory holding cost, shortage cost and carbon emission cost. The max–min approach is used to solve the models, which assume limited information on demand distribution. We investigate how the three regulation policies affect remanufacturing decision-making for IRs and we also solve some numerical examples where we vary the magnitudes of incentives, penalties and stringency of constraints to provide implications to policy-makers. The results indicate that remanufacturers should aim to improve yield rate to maximise the profit irrespective of the implemented carbon emissions policy. Policy-makers should prefer the carbon tax policy, if any of the other two policies must be performed, a remanufacturing discount such as a higher carbon emission cap or lower penalty should be implemented to better promote the development of remanufacturers.
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| 32. |
- Liu, Biyu, et al.
(författare)
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Maintenance service strategy for leased equipment : integrating lessor-preventive maintenance and lessee-careful protection efforts
- 2021
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Ingår i: Computers & industrial engineering. - : Elsevier. - 0360-8352 .- 1879-0550. ; 156
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Tidskriftsartikel (refereegranskat)abstract
- Lessees may abuse equipment during the lease period since lacking of ownership, thereby increasing lessors’ repair cost and lessees’ downtime losses. This study integrates lessees’ effort to protect leased equipment during the lease period with lessors’ preventive maintenance (PM) into maintenance service strategies. It is proved in a non-cooperative game, neither party achieves the cooperative game’s ideal revenue, but improvement in the lessee’s effort level and lessor’s PM degree can increase the other party’s revenue. A cost-sharing contract model is designed to achieve the maximum revenue as in a cooperative game and ensure Pareto improvement of the leasing parties. In the contract, the lessor grants the lessee a rental discount, and the lessor’s PM cost and lessee’s effort cost are shared with cost-sharing coefficients. Conditions under which the ideal revenue and Pareto improvement can be achieved are discussed. Numerical examples are provided to illustrate the effects of contract parameters, unit penalty on the effort level, and revenue. Managerial insights are finally proposed for leasing parties. The results show: the effect of the effort level and PM degree on equipment failures is marginally diminishing; proposed cost-sharing contract model can achieve the ideal revenue and Pareto improvement; the rental discount has a greater impact on the lessee, while the cost-sharing coefficients have a greater impact on the lessor; and increasing the unit penalty decreases (increases) the lessor’s (lessee’s) revenue but maintains the effort level at constant.
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| 33. |
- Liu, Biyu, et al.
(författare)
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Supplier evaluation and selection in a sustainable supply chain based on fuzzy-BWM, entropy method and grey relational TOPSIS
- 2023
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Ingår i: Journal of Intelligent & Fuzzy Systems. - : IOS Press. - 1064-1246 .- 1875-8967. ; 44:6, s. 9919-9932
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Tidskriftsartikel (refereegranskat)abstract
- Suppliers significantly affect the effectiveness of sustainable supply chain management. Hence, it is extremely important to evaluate and select suppliers scientifically and objectively. Based on the theory of triple bottom line (economic, social, and environmental dimension) and a balanced scorecard, a measureable supplier evaluation framework in a sustainable supply chain is first formulated. Second, to reduce the defects of the single weight method, the subjective and objective weights of evaluation indicators are determined by combining the fuzzy best-worst method (BWM) and the entropy method, and then the combination weights are obtained through linear weighting. Third, the grey relational technique for order performance by similarity to ideal solution (TOPSIS) method is further adopted to evaluate and rank the suppliers. Finally, a case study illustrates and demonstrates the availability of the proposed supplier evaluation index system and evaluation method. Subsequently, some suggestions are proposed according to the results.
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| 34. |
- Lu, Weizhuo, et al.
(författare)
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Application of discrete event simulation and CONWIP on inventory control
- 2010
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Ingår i: Proceedings of the CIB W78 2010.
-
Konferensbidrag (refereegranskat)abstract
- Simulation is an effective quantitative analysis tool to compare and evaluate different system design. However, the application of simulation in construction industry has been limited to relatively restricted research fields. This paper presents a discrete event simulation (DES) model using Simphony.net in which quantitative performance evaluation between constant work-in-progress (CONWIP), a pull method that limits the work-in-progress (WIP) level in the production system according to the status of system, and push are provided. A card element in the simulation model is used to authorize the production, collect cards and limit work-in-progress (WIP) level in the system. The purpose of such comparison and evaluation is to explore the utilization of DES and CONWIP on inventory control.Uncertainty and variation in construction process has an important influence on project performance. The common practice to deal with variation is the holding of inventory. As demonstrated in developed simulation model in this research, suitable inventory improves the performance of project. However, excessive inventory induces no-added value. Simulation experiments show that application of DES and CONWIP provides an effective way of inventory control, simultaneously, maintain throughput and cycle time compared to push system. The research will be of interest to those evaluating the impacting of lean base method on construction project performance with simulation.Keywords: DES, inventory control, lean, CONWIP
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| 35. |
- Nilsson, Andreas, et al.
(författare)
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A new heuristics to solve the Joint Replenishment Problem using a spread-sheet technique
- 2004
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Konferensbidrag (refereegranskat)abstract
- In this paper, a heuristic method is presented which gives a novel approach to solve joint replenishment problems (JRP) with strict cycle policies. The heuristic solves the JRP in an iterative procedure and is based on a spreadsheet technique. The principle of the recursion procedure is to find a balance between the replenishment and inventory holding costs for the different items by adjusting the replenishment frequencies. The heuristic is also tested according to an extensive test template and shows pleasing results. It also performs well in comparison with many other heuristics.
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| 36. |
- Nilsson, Andreas, et al.
(författare)
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A new iterative heuristic to solve the joint replenishment problem using a spread-sheet technique
- 2007
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 108:1-2, s. 399-405
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a heuristic method is presented which gives a novel approach to solve joint replenishment problems (JRP) with strict cycle policies. The heuristic solves the JRP in an iterative procedure and is based on a spreadsheet technique. The principle of the recursion procedure is to find a balance between the replenishment and inventory holding costs for the different items by adjusting the replenishment frequencies. The heuristic is also tested according to an extensive test template and shows pleasing results. It also performs well in comparison with many other heuristics.
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| 37. |
- Nilsson, Kristina, et al.
(författare)
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Corrections of costs to feasible solutions of economic lot scheduling problems
- 2008
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Ingår i: Computers & industrial engineering. - : Elsevier BV. - 0360-8352 .- 1879-0550. ; 54:1, s. 155-168
-
Tidskriftsartikel (refereegranskat)abstract
- The paper considers the problem of choosing order quantities and a cyclic production pattern for several products that are produced in a common capacity constrained facility. The heuristic method from Segerstedt [Segerstedt, A. (1999). Lot sizes in a capacity constrained facility with available initial inventories. International Journal of Production Economics, 59, 469-475] is modified and improved. The method is compared with the heuristic technique according to Doll [Doll, C. L., & Whybark, D. C. (1973). An iterative procedure for the single-machine multi-product lot scheduling problem. Management Science, 20(1), 50-55; Goyal, S. K. (1975). Scheduling a single-machine multi-product system: A new approach. International Journal of Production Research, 13, 487-493]; the differences and similarities between the methods are illustrated in a common numerical example. It shows that feasible solutions can be found, both with our method and others; where the production can be scheduled during a time interval, the initial inventory level is the same as the final and the schedule can be repeated in a cyclic pattern without shortages. (This definition of feasibility differs from traditional.) However, it shows that the common approximation for the inventory holding costs [.....] does not fit. The real inventory holding cost becomes different compared to the approximated that is used in the calculations. The real inventory holding cost depends on the chosen scheduling, which makes it difficult to find an optimal solution. Different solutions and extensions are discussed.
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| 38. |
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| 39. |
- Norberg, Håkan, et al.
(författare)
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Byggsynkronisering
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten redovisar de resultat som hittills framkommit i ett ERABUILD-projekt där avsikten är att skapa industrialiserade processer för definition, utformning, byggande och fastighetsförvaltning som väsentligt kan effektivisera byggande och förvaltning av fastigheter över hela livscykeln. Målet med den svenska delen är att definiera en framtida industrialiserad byggprocess som är stödd av ett synkroniserat flöde av information, resurser, material och aktiviteter till byggplatsens olika produktionsställen. Hypotesen är att platsknutna planeringsmetoderna som Line of Balance och 4D tillsammans med en robust produktionsstyrningsmetod kan skapa arbetsscheman som kan genomföras med tillräcklig förutsägbarhet. Detta är nödvändigt för att kunna skapa bra och effektiva försörjningskedjor. Mobila verksamhetssystem är en lämplig teknologi för att kunna understödja ett sådant synkroniserat byggande. För att säkerställa en öppen tillgång till den gemensamma bygginformationsmiljön (VBE) kommer tekniken med standardiserade Web Services att testas för att koppla ihop applikationer som kan stödja ett synkroniserat byggande.I Etapp I av projektet har produktionsprocessen för en typisk byggplats kartlagts där informations- och materialflöden samt användning av gemensamma resurser nödvändiga för genomförandet av olika produktionsaktiviteter definierats för att utveckla en byggplatsanpassad logistikmodell. Applikationer och metoder för planering och styrning samt strategier och mått för byggplatsens försörjningskedjor av information, material och komponenter har identifierats. I Etapp II, har valda delar av modellen att jämförts och utvärderas mot traditionella metoder i ett pågående byggprojekt, (NCC:s projekt kvarteret Rådjuret i Luleå samt Solberga Torg). Framtagna metoder med stöd av valda applikationer har demonstreras i en avgränsad del av projektet. Idag implementeras 3D projektering i stor skala i den svenska byggbranschen. Detta har lett till bättre samordning mellan olika discipliner och mindre antal kollisioner som måste lösas på plats. I nästa steg kommer en övergång till bygginformationsmodeller att ske (BIM) där informationen kommer att integreras mellan olika aktörer och skeenden i byggprocessen. En sådant naturligt steg är att integrera projektering och produktion där stora värden kan sparas om BIM modellen kan användas för inköp, planering och genomförandet i produktionsprocessen. En demonstrationsmiljö har byggts upp med en modellserver, en BIM Collaboration Hub, för att hantera IFC-filer som definierar byggnaden och andra filtyper som används i olika affärsprocesser. De olika bygg- och installationsdelarna kan läsas in med sina versioner från CAD-system i IFC-formatet och därefter knytas till annan information som t ex krav och tidplaneaktiviteter. Arkitekturen ger en flexibel lösning där företag kan samverka med hjälp av olika överföringsmetoder - filöverföring, tjänster som anropas och inmatning via ett grafiskt användargränssnitt. Den processmodell som utvecklats i inVBE projektet och som utgör viktig del i Håkan Norbergs lic-avhandling (se referenslistan) skapar bättre förutsättningar för beredning/koordinering, synkronisering, rapportering och uppföljning av produktionen på byggarbetsplatserna. Vid projektets slutpresentation var intresset stort från flera byggföretag att prova och utvärdera det nya arbetssättet och de nya verksamhetsstödjande applikationerna. Ambitionen är därför att tillsammans med intresserat byggföretag med lämpligt byggprojekt ansöka om SBUF medel för att genom fältprov utvärdera om förväntade kvalitets- och produktivitetsförbättringar erhålls i verkligheten.
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| 40. |
- Pettersen, Jan-Arne, et al.
(författare)
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Production performances vs machine down times and buffer sizes : a case study
- 2008
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Ingår i: 15th International Working Seminar on Production Economics. ; , s. 511-520
-
Konferensbidrag (refereegranskat)abstract
- In autumn 2007 a new production facility were inaugurated in the north of Norway. To protect business confidentiality we will refer to the company as The Company and the product as the product. This work is based on pre study of the facility. The product is mass-produced in a highly automated production system consisting of series of chemical and mechanical processes. We investigate how variation in machine down time and different sizes of intermediate buffers affects total system performance. The investigation was done using a sensitivity analysis performed in a simulation environment for discrete event systems called AutoMod. Simulation was chosen instead of an analytical analysis because of two reasons: firstly, the production system consists of series of processes that influence each other, and secondly, we want to see the effect on both long term average values and short term variation. To analyze and compare two or more system configurations, system performance metrics are needed. In cooperation with the Company, the average and the variance of input rate (parts into the system per hour), output rate (parts out of the system per hour), WIP (parts in the system) and lead time (time in minutes each part is in the system) was chosen as performance metrics. This work shows that system configurations and system decisions should be compared not only with average metrics but also by some variation metrics. Another discovery is, when analysing throughput variation in a system, input – and output rate variation is not the same.
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| 41. |
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| 42. |
- Pettersen, Jan-Arne, et al.
(författare)
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Restricted work-in-process : a study of differences between Kanban and CONWIP
- 2009
-
Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 118:1, s. 199-207
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a simulation study over a small supply chain, where the amount of work-inprocess (WIP) is restricted. The supply chain consists of five linked machines, or production facilities, with stochastic operation times. A number of test cases are made where the number of jobs in the machines and the buffer areas are restricted. The restrictions are designed both in the Kanban way, linked to every machine, and in the CONWIP way, connected only to the total production line. But no Kanban-cards and no Kanban-cells are involved in our study, just restricted inventories between the machines. With the same amount of limited WIP, CONWIP control compared to Kanban control presents a higher throughput rate, less time between jobs out, but the jobs stay on average longer in the system. The stochastic operation times cause that the upstream machine sometimes consumes the jobs in a rate that the downstream machine does not catch up with, therefore all available storage room temporarily are not used. Kanban and CONWIP control presents the same amount of average outflow per time unit with the same variation in operation times and with the same amount of real average WIP. But Kanban control causes a lower utilisation of present available storage room and storage equipment than CONWIP. The user of Kanban and CONWIP can only control maximum WIP and not average WIP; average WIP is a consequence of existing variations, so the difference is important. The coefficient of variation of the lead-times increases when WIP increases; this is very difficult to handlein practical applications. Restricted WIP that shortens the lead-time and decreases its variation is more important than if it is a "push" or "pull" system. Finally it is argued that CONWIP control is to prefer over Kanban control in theory, but in practice there is a lack of CONWIP installation guidelines.
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| 43. |
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| 44. |
- Pettersen, Jan-Arne, et al.
(författare)
-
Three-dimensional performance surfaces : a tool for analysing and estimation of production system performances
- 2010
-
Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 48:17, s. 4937-4948
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new method to describe, analyse and estimate production system performances. Work-in-process (units), lead time (number of time units spent in the production system for each unit) and throughput (number of produced units per time unit) are basic performance measures, also used in this article. It is essential for industry to know about relations between system parameters and system performances in existing systems, and in not yet implemented system alternatives. Different performances are achieved by adjusting system parameters. Trade-offs between system parameters and its different performances are necessary to stay efficient and competitive in today's market. Queuing theory and simulation can help the decision makers to estimate system performances of existing and not yet implemented systems. When the complexity increases queuing theory becomes cumbersome, very difficult and eventually impossible to use. A single simulation presents limited information. Multiple simulations are necessary to ensure that the best alternative is chosen. A high number of simulations demand a lot of computer time and resources. Reduction of runs is desirable even with cheaper computer equipment. Currently, traditional two-dimensional charts are the only tools to present and analyse system performances. This article presents a new surrogate model for easier estimation and presentation of system performances, their internal relations, and relations to the system parameters. With the new surrogate model, system performances based on simulations are presented as positions in a three-dimensional environment. Parametric curves and surfaces of Bezier type are generated and adapted to these positions. System performances of other system alternatives can then be estimated without explicit simulation. The number of simulation calculations can thereby be moderated. The method is illustrated with a small production line system
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| 45. |
- Petterssen, Jan-Arne, et al.
(författare)
-
A literature review about Kanban and CONWIP
- 2010
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Ingår i: Book of Abstracts, 16th International Symposium on Inventories. - : International Society for Inventory Research.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 46. |
- Pettersson, Annelie I., et al.
(författare)
-
Measuring Supply Chain costs
- 2010
-
Ingår i: Book of Abstracts, 16th International Symposium on Inventories. - : International Society for Inventory Research.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 47. |
- Pettersson, Annelie I., et al.
(författare)
-
Performance measurements in supply chains within Swedish industry
- 2011
-
Ingår i: International Journal of Logistics Systems and Management. - 1742-7967 .- 1742-7975. ; 9:1, s. 69-88
-
Tidskriftsartikel (refereegranskat)abstract
- A critical issue for a company to gain a competitive position is to improve its supply chain performance. This study investigates with interviews how 30 Swedish companies in ten different sectors define an excellent supply chain and work with Supply Chain Management, performance measurements and Supply Chain Costs. It shows that the companies define excellence more by a performance focus than a cost focus. Delivery precision, inventory turnovers (days of inventory) and lead time are the most common performance measurements. The costs of the supply chain are measured in many different ways and with different accuracy.
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| 48. |
- Pettersson, Annelie, et al.
(författare)
-
Measurements of excellence in a supply chain
- 2012
-
Ingår i: International Journal of Logistics Systems and Management. - 1742-7967 .- 1742-7975. ; 13:1, s. 65-80
-
Tidskriftsartikel (refereegranskat)abstract
- Organisations focus on having an excellent supply chain to increase net income. But how to measure excellence in a supply chain? This paper is concerned with excellence within Supply Chain Management (SCM) and how this can be measured. The focus is on identifying and suggesting a model that can be used for measuring excellence in a supply chain. The result from a study of 30 companies with the aim to investigate how companies in 10 different sectors are working with supply chain excellence is an origin for the model. The paper suggests a coordinate and cooperate model, or index figure, that is based on a combination of the cost for the supply chain and performance towards the customer.
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| 49. |
- Pettersson, Annelie, et al.
(författare)
-
Measuring supply chain cost
- 2013
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 143:2, s. 357-363
-
Tidskriftsartikel (refereegranskat)abstract
- Organisations focus on reducing costs in their supply chains to increase net income. In order to reduce costs a company needs to know how to measure Supply Chain Cost (SCC). This paper is concerned with SCC and how measurements of SCC are and can be used in industry. The paper describes a suggested model for measuring SCC. Representatives from 30 companies in 10 different business sectors are interviewed about how they measure costs in their supply chains compared against this model. The focus is also on identifying the difference between SCC based on estimated standard cost compared to actual cost. A case study describes and shows the difference between measuring SCC based on calculated standard cost and measuring it based on actual cost. Our studies show that general thorough cost and supply chain analyses in many companies can be improved and further developed.
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| 50. |
- Pettersson, Annelie, et al.
(författare)
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To Evaluate Cost Savings in a Supply Chain : Two Examples from Ericsson in the Telecom Industry
- 2013
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Ingår i: Operations and Supply Chain Management. - : OSCM Forum. - 1979-3561 .- 2579-9363. ; 6:3, s. 94-102
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Tidskriftsartikel (refereegranskat)abstract
- An accurate cost analysis is necessary to evaluate changes in a supply chain; this article shows how a rather simple framework can be used when evaluating changes in a supply chain. The framework is built on a Supply Chain Cost (SCC) model and customer service measurements, delivery precision and lead-time. Both suggested changes in a supply chain and already executed changes can be evaluated by the framework. Two different examples from the company Ericsson are presented to illustrate the framework, which is a 5 step analysis model. The existing, or pre-existing, supply chain is analysed, described and defined. The SCC and performance measures are mea-sured and/or estimated. Improvements are designed and defined. The same measures as before are measured again. The measures from before and after the change of the supply chain are evaluated to decide if the changes are improvements or not. Cutting costs in one area of the supply chain can be a mistake if not the total supply chain is considered and the total SCC. Considering both the SCC part and customer service measures present a wider understanding of the change. It is shown that SCC can be used as a tool to identify cost savings and evaluate if a change project will, or has, resulted in the cost savings the project aims for. Rough standard costs measures should be avoided instead actual costs should be used as much as possible. The used framework hopefully stimulate to similar analyses in other companies with other supply chains.
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