| 11. |
- Eklöf, Johan S., et al.
(författare)
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How do seaweed farms influence fishery catches in a seagrass-dominated setting in Chwaka Bay, Zanzibar?
- 2006
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Ingår i: Aquatic Living Resources. - : EDP Sciences. - 0990-7440 .- 1765-2952. ; 19:2, s. 137-147
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed farming is often depicted as a sustainable form of aquaculture, contributing to poverty reduction and financial revenues in producer countries. However, farms may negatively affect seagrasses and associated organisms (e.g. invertebrate macrofauna) with possible effects on the flow of ecosystem goods and services to coastal societies. The present study investigates the influence of a seaweed farm, and the farmed seaweed Eucheuma denticulatum in particular, on fishery catches using a traditional fishing method ("madema" basket traps) in Chwaka bay (Zanzibar, Tanzania). The results suggest that a seaweed farm, compared to a seagrass bed, had no influence on catch per unit effort (no. of individuals per catch, or catch weight) or no. of species per catch, but significantly affected catch composition (i.e. how much that was caught of which species). The two species contributing most to differences between the sites were two economically important species; the herbivorous seagrass rabbit fish Siganus sutor, which was more common in the seaweed site and is known to graze on the farmed algae; and the benthic invertebrate feeder chloral wrasse Cheilinus chlorourus, more common in the seagrass site. Compared to vegetation-free bottoms, however, the catches were 3-7 times higher, and consisted of a different set of species (ANOSIM global R > 0.4). As traps placed close to the seaweeds fished three times more fish than traps placed on sand patches within the seaweed farm, the overall pattern is attributed to the presence of submerged vegetation, whether seagrass or seaweed, probably as shelter and/or food for fish. However, qualitative differences in terms of spatial and temporal dynamics between seagrass beds with and without seaweed farms, in combination with other factors such as institutional arrangements, indicate that seaweed farms cannot substitute seagrass beds as fishing grounds.
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| 12. |
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| 13. |
- Fernberg, Patrik, et al.
(författare)
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Piezoresistive performance of long-fiber composites with carbon nanotube doped matrix
- 2009
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Ingår i: Journal of Intelligent Materials Systems and Structures. - 1045-389X .- 1530-8138. ; 20:9, s. 1017-1023
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Tidskriftsartikel (refereegranskat)abstract
- The electrical and mechanical properties of carbon nanotube (CNT) doped epoxy resin and composites based on this matrix were studied. The investigation was carried out on neat nanocomposites and on structural composites i.e., when the nanocomposite is used as matrix in composite materials reinforced with long continuous fibers. Tensile tests showed that CNT doped epoxy exhibited clear piezoresistive behavior. It was, however, also shown that geometrical changes of the specimen also contribute significantly to resistance changes during tensile loading. Particular effort was made to establish the relations between transverse cracking in glass fiber cross-ply laminates with nanotube doped matrix and changes of electrical resistance. It was shown that changes of electrical resistance during tensile loading of composites containing CNT doped matrix gives highly relevant information about the damage state of the material. In an unloaded state the resistance change is proportional to the relative change of stiffness. This work demonstrates that there are three different mechanisms, which contribute to changes of electrical resistance of a composite specimen subjected to tensile strain. These three mechanisms are: (a) geometrical changes of the specimen (b) piezoresistive material response, and (c) accumulation of micro-damage.
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| 14. |
- Fernberg, Patrik, et al.
(författare)
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Piezoresistive performance of long fibre composites with carbon nanotube doped matrix
- 2007
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Ingår i: Proceedings of COMP07.
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Konferensbidrag (refereegranskat)abstract
- The electrical and mechanical properties of carbon nanotube doped epoxy resin and composites based on this matrix were studied. The investigation was carried out on neat nanocomposites and on structural composites i.e. when the nanocomposite is used as matrix in composite materials reinforced with long continuous fibers. Tensile tests showed that carbon nanotube (CNT) doped epoxy exhibited a clear piezoresistive behavior. It was however also shown that geometrical changes of the specimen also contribute significantly to resistance changes during tensile loading. Particular effort was made to establish the relations between transverse cracking in glass fibre cross-ply laminates with nanotube doped matrix and resistance changes. It was shown that resistance changes during tensile loading of composites containing CNT doped matrix gives highly relevant information about the damage state of the material. In an unloaded state the resistance change is proportional to the relative change of stiffness. This work demonstrates that there are three different mechanisms which contribute to resistance changes of a composite specimen subjected to tensile strain. These three mechanisms are: a) geometrical changes of the specimen b) piezoresistive material response and c) accumulation of micro-damage
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| 15. |
- Fernberg, Patrik, et al.
(författare)
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Strain and damage sensing during loading of carbon nanotube doped composites
- 2009
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Ingår i: ICCM International Conferences on Composite Materials. - London : IOM Communications.
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Konferensbidrag (refereegranskat)abstract
- This work explores the possibility to use resistance changes in a carbon nanotube (CNT) doped composites to monitor deformations and damage. Most other studies in the field are done on simplified uniaxial loading whereas current work also evaluates the possibilities to monitor strain in more complex loading case, such as bending.
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| 16. |
- Flisberg, Patrik, et al.
(författare)
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Billerud Optimizes Its Bleaching Process Using Online Optimization
- 2009
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Ingår i: INTERFACES. - : Institute for Operations Research and the Management Sciences (INFORMS). - 0092-2102 .- 1526-551X. ; 39:2, s. 119-131
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Tidskriftsartikel (refereegranskat)abstract
- Billerud, a Swedish company with four integrated pulp and paper mills, serves specific packaging-market segments. In 2000, the process-engineering department at Billeruds mill in Skarblacka sought to improve the mills bleaching process. It contacted Linkoping University, which collaborated with Eurocon Automation AB to develop a decision-support system, OptCab. Eurocon Automation AB now offers OptCab as a general tool in the market. Its core is an online optimization system that dynamically updates a process description and optimizes the bleaching control process. The system, which has been fully operational since 2004, has provided numerous benefits to Billerud. Chemical use has decreased by approximately 10 percent, saving approximately two million euros since its installation; the environmental impact has also been reduced; and the brightness quality of paper that the mill produces is more uniform and stable. Moreover, OptCab requires less operator time, freeing the operators for development and analysis work.
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| 17. |
- Flisberg, Patrik, et al.
(författare)
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Optimized on-line process control of bleaching operations with OptCab
- 2007
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Ingår i: Norges Handelshoeyskole. Institutt for Foretaksoekonomi. Discussion Paper. - 1500-4066.
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Forskningsöversikt (refereegranskat)abstract
- To produce pulp for paper production or as market pulp is a complicated on-line process with many integrated stages that impact the final quality. In the bleaching plant which is at the end of pulp production, the main objective is to increase pulp brightness within specified limits. Here chemical treatments are applied in sequential stages to achieve the right brightness while striving to maintain the pulp strength as unaffected as possible. The raw material, i.e. pulp logs and wood chips from saw mills, differ in quality and properties. Due to this, it is important to continuously update the amount of chemicals added to the pulp in real-time. This is typically done by experienced operators. In this paper, we describe an on-line optimization based decision support system called OptCab that controls the bleaching process at Billerud AB's paper mill in Skärblacka. The solution approach is based on two phases. In phase one, we establish approximations of each of the processes based on process data collected on-line. These approximations are found by solving a set of constrained least square problems and are updated every 15 minutes. In phase two, we formulate an overall nonlinear control problem that links all stages together and aims to minimize the cost of chemicals. This is solved on-line every five minutes. The system has been in operation during the last three years providing a 10% reduction in the use of chemicals. Additional benefits include a more stable brightness quality.
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| 18. |
- Flisberg, Patrik, et al.
(författare)
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Pulp fact, not fiction
- 2005
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Ingår i: OR/MS Today. - 1085-1038. ; 32:2, s. 42-47
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Tidskriftsartikel (refereegranskat)abstract
- By taking the guesswork out of the equation, operations research-based process control system helps cut costs, reduce environmental impact at Swedish paper mill.
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| 19. |
- Hall, Patrik, et al.
(författare)
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Bureau-Shaping Theories and Public Management Reforms
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- New Public Management (NPM) reform ideas are, in the literature, usually portrayed as exogenous models which somehow permeate public organisations (cf. Pollitt & Bouckaert, 2004). Hitherto, the question whether internal organisational motives for creating new units has been a contributing factor to the diffusion of NPM ideas has been notably overlooked. It is our contention that theories on bureau-shaping can complement other frameworks for describing the diffusion of NPM reforms. That is, bureaucrats (i.e. public management) can use the ‘discourse’ of NPM for pursuing the creation of new, more policy-shaping and second order functional, units and offices (for example, benchmarking, communication etc) within public organisations, thereby replacing old bureaucratic layers with ‘novel’ offices detached from the daily operative functions of bureaucracy. The aim of our paper is to discuss and review strategies for empirical studies of bureau-shaping theory in the light of public management reforms. Whilst Dunleavy's original thoughts have been widely discussed and contested, few actual attempts have been made to transfer them to empirical studies. In this paper, we examine some of the main traits of criticism, as well as some of the few attempts to apply the theory empirically. In addition, we propose a research strategy for a comparative empirical study of bureaucratic change within local and state administration in Sweden and Denmark inspired by bureau-shaping theory. From a preliminary case study, we conclude that bureau-shaping may be more of a systematic organisational response to administrative reforms than the utility-maximising strategy of individual bureaucrats.
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| 20. |
- Hall, Patrik, et al.
(författare)
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The small, but significant steps taken by the men within : a complementary understanding of incremental public organisation changes
- 2009
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Konferensbidrag (refereegranskat)abstract
- Organisational actors in the public sector are often characterised as path-dependent and tending to reject or translate change in accordance with institutional norms, while management change is often interpreted as emanating from “above” (international organisations, governments, thinktanks). In this article we present, inspired by Dunleavy’s bureau-shaping approach, a complementary understanding of incremental changes which goes beyond the existing explanations. Our claim is that incremental changes often are caused by ‘pull-factors’ inside the organisation. Based on an in-depth study of five Swedish public agencies 1980-2005 we present an inductively-derived typology of organisational change. In the five organisations considered, it is shown that the management level has been able to influence changes which emanate from “push-factors” in the environment (such as streamlining, cost reduction and symbolic adaptations). But the paper also highlights more gradual changes – “small but significant steps” - such as increased hiring of social scientists and managerialisation as important features in the process of reconstructing the agencies as policy-making, rather than operational, units, in line with Dunleavy’s general argument. A conclusion to this is that improved policy-making capacity, paradoxically, may reduce Swedish public agencies’ ability to steer.
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