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| 3. |
- Agrell, Cecilia, et al.
(författare)
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Polybrominated diphenyl ethers (PBDES) at a solid waste incineration plant I: Atmospheric concentrations
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:30, s. 5139-5148
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Tidskriftsartikel (refereegranskat)abstract
- In the first of two papers, the atmospheric poly brominated diphenyl ether (PBDE) concentrations at a municipal solid waste incineration (MSW) plant with electronic recycling is compared with that at an industrial urban reference site producing asphalt and concrete. In the second paper, atmospheric deposition and washout behaviour is presented (Atmos. Environ. (2004a)). PBDEs (BDE28, -47, -66, -100, -154, -153, -183, -209) in the gaseous and particulate phase were measured with high resolution in time during the colder parts of the year to minimise the influence of potential historical pollution at the sites through volatilisation. This also means that reported levels are lower compared to other reported data. Results of BDE47 (TetraBDE) and BDE209 (DecaBDE) as representatives of "old" vs. "new" PBDEs as well as SigmaPBDE, excluding BDE209, are presented. Median SigmaPBDE, BDE47 and BDE209 concentration were 6.3, 2.1 and 10.4 pg m(-3) at the MSW and 3.5, 1.7 and 6.5 pg m-3 at the reference site. The total concentrations (gaseous and particulate phase) were significantly higher at the MSW compared to the reference site for SigmaPBDE and BDE47 but not for BDE209. The same results were obtained regarding concentrations in the gaseous phase. Particle concentrations were significantly higher at the MSW for SigmaPBDE, BDE47 and BDE209. Within each site, the gaseous-phase concentration was significantly higher than the particulate-phase concentration except for BDE209 at the MSW. Thus, the proportion of BDE209 detected in the particulate phase was higher at the MSW compared to the reference site. Together with the results of the second paper, we suggest that treatment of waste is presently a source of "old" PBDEs to the environment, whereas the rather similar BDE209 concentrations at the two sites are more a result of proximity to potential diffuse sources.
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- Agrell, Per J., et al.
(författare)
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A Coherent Methodology for Productivity Analysis Employing Integrated Partial Efficiency
- 1996
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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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- Agrell, Per, J., et al.
(författare)
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An MCDM Framework for Dynamic Systems
- 1996
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273 .- 1873-7579. ; 45:1-3, s. 279-292
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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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| 6. |
- Agrell, Per J., et al.
(författare)
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Horizontal Carrier Coordination through Cooperative Governance Structures
- 2017
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273. ; 194, s. 59-72
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines how governance structures found in the trucking industry impact the coordination between a forwarder and its carriers, including three cases: no forwarder coordination (direct contracting with shippers), investor-owned coordination (price-only contract), and carrier-cooperative coordination (revenue-sharing contract). The carriers are engaged in a Cournot competition, where they decide upon service provision and truck investment. Economic theory predicts that integration of firms under oligopolistic competition always leads to a more efficient supply chain in the sense that prices decrease and quantities increase, which reduces total profits. This suggests that the benefit of avoiding double marginalization does not outweigh the benefit of upstream competition in the successive oligopoly case, whereas both integrated and independent firms coexist, the integrated chains do perform better. In this paper we examine the interaction between governance structures, a key decision when managing supply chains, including that found in the trucking industry, and shippers willingness to procure trucking services instead of producing them using a private fleet. We find that cooperative governance can contribute to improved service provision, reduced service price, improved consumer surplus, and improved profit for the carriers in equilibrium. We use parameter values based on the Swedish trucking industry and a larger grocery retailer acting as shipper to numerically illustrate the impact of different governance structures.
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| 7. |
- Agrell, Per J., et al.
(författare)
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Impacts on efficiency of merging the Swedish district courts
- 2020
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Ingår i: Annals of Operations Research. - : Springer. - 0254-5330 .- 1572-9338. ; 288:2, s. 653-679
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Tidskriftsartikel (refereegranskat)abstract
- Judicial courts form a stringent example of public services using partially sticky inputs and outputs with heterogeneous quality. Notwithstanding, governments internationally are striving to improve the efficiency of and diminish the budget spent on court systems. Frontier methods such as data envelopment analysis are sometimes used in investigations of structural changes in the form of mergers. This essay reviews the methods used to evaluate the ex post efficiency of horizontal mergers. Identification of impacts is difficult. Therefore, three analytical frameworks are applied: (1) a technical efficiency comparison over time, (2) a metafrontier approach among mergers and non-mergers, and (3) a conditional difference-in-differences approach where non-merged twins of the actual mergers are identified by matching. In addition, both time heterogeneity and sources of efficiency change are examined ex post. The method is applied to evaluate the impact on efficiency of merging the Swedish district courts from 95 to 48 between 2000 and 2009. Whereas the stated ambition for the mergers was to improve efficiency, no structured ex post analysis has been done. Swedish courts are shown to improve efficiency from merging. In addition to the particular application, this work may inform a more general discussion on public service efficiency measurement under structural changes, and their limits and potential.
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| 8. |
- Agrell, Per J, et al.
(författare)
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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
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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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| 10. |
- ter Schure, Arnout, et al.
(författare)
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Atmospheric transport of polybrominated diphenyl ethers and polychlorinated biphenyls to the Baltic sea
- 2004
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 38:5, s. 1282-1287
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric transport of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) was compared by measuring concentrations in air and deposition on an island located in the central basin of the Baltic Sea. Median SigmaPBDE and SigmaPCB concentrations (gaseous + particle) were 8.6 and 7.4 pg m(-3), respectively. Airborne PCBs were mainly found in the gaseous phase, while most of the PBDEs were detected on particles, which agrees with predicted particle/gas distributions. SigmaPBDE levels were dominated by the decabrominated BDE209 followed by the tetrabrominated BDE47 and pentabrominated BDE99. BDE209 is a marker for the environmental distribution of the commercial deca-BDE formulation (>99.5% BDE209), whereas BDE47 and BDE99 are markers for the commercial penta-BDE mixture. General correlations between PBDEs and PCBs suggested similarities in sources and transport mechanism, while more detailed examination of the data identified notable behaviors and exceptions. Differences in regression slopes among tetra-, penta-, and decabrominated PBDEs may reflect different transport processes and the change in usage pattern. Tetra- and pentabrominated PBDEs may originate from secondary sources such as air surface exchange in a manner similar to that of the PCBs, while the deca-BDE209 formulation still has primary sources. The tribrominated BDE17 was also detected and is proposed to be a breakdown product due to atmospheric debromination processes. PBDEs had higher washout ratios than PCBs, explaining their higher concentrations compared to PCBs in precipitation (median of 6.0 and 0.5 ng L-1 for SigmaBDE and SigmaPCB concentrations ("dissolved" + particle), respectively) than in air. The calculated yearly deposition of PBDEs and PCBs indicated that the atmospheric input of PBDEs to the Baltic Proper is currently exceeding that of the PCBs by a factor of 40, while that of the PCBs is decreasing.
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