| 1. |
- Mårald, Erland, 1970-, et al.
(författare)
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Forest governance and management across time : developing a new forest social contract
- 2017
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Bok (refereegranskat)abstract
- The influence of the past, and of the future on current-time tradeoffs in the forest arena are particularly relevant given the long-term successions in forest landscapes and the hundred years' rotations in forestry. Historically established path dependencies and conflicts determine our present situation and delimit what is possible to achieve. Similarly, future trends and desires have a large influence on decision making. Nevertheless, decisions about forest governance and management are always made in the present – in the present-time appraisal of the developed situation, future alternatives and in negotiation between different perspectives, interests, and actors.This book explores historic and future outlooks as well as current tradeoffs and methods in forest governance and management. It emphasizes the generality and complexity with empirical data from Sweden and internationally. It first investigates, from a historical perspective, how previous forest policies and discourses have influenced current forest governance and management. Second, it considers methods to explore alternative forest futures and how the results from such investigations may influence the present. Third, it examines current methods of balancing tradeoffs in decision-making among ecosystem services. Based on the findings the authors develop an integrated approach – Reflexive Forestry – to support exchange of knowledge and understandings to enable capacity building and the establishment of common ground. Such societal agreements, or what the authors elaborate as forest social contracts, are sets of relational commitment between involved actors that may generate mutual action and a common directionality to meet contemporary challenges.
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| 2. |
- Asif, Sana, et al.
(författare)
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Oxygen-charged HTK-F6H8 emulsion reduces ischemia : reperfusion injury in kidneys from brain-dead pigs
- 2012
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 0022-4804 .- 1095-8673. ; 178:2, s. 959-967
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Tidskriftsartikel (refereegranskat)abstract
- Background:Prolonged cold ischemia is frequently associated with a greater risk of delayed graft function and enhanced graft failure. We hypothesized that media, combining a high oxygen-dissolving capacity with specific qualities of organ preservation solutions, would be more efficient in reducing immediate ischemia-reperfusion injury from organs stored long term compared with standard preservation media.Methods:Kidneys retrieved from brain-dead pigs were flushed using either cold histidine-tryptophan-ketoglutarate (HTK) or oxygen-precharged emulsion composed of 75% HTK and 25% perfluorohexyloctane. After 18 h of cold ischemia the kidneys were transplanted into allogeneic recipients and assessed for adenosine triphosphate content, morphology, and expression of genes related to hypoxia, environmental stress, inflammation, and apoptosis.Results:Compared with HTK-flushed kidneys, organs preserved using oxygen-precharged HTK-perfluorohexyloctane emulsion had increased elevated adenosine triphosphate content and a significantly lower gene expression of hypoxia inducible factor-1 alpha, vascular endothelial growth factor, interleukin-1 alpha, tumor necrosis factor-alpha, interferon-alpha, JNK-1, p38, cytochrome-c, Bax, caspase-8, and caspase-3 at all time points assessed. In contrast, the mRNA expression of Bcl-2 was significantly increased.Conclusions:The present study has demonstrated that in brain-dead pigs the perfusion of kidneys with oxygen-precharged HTK-perfluorohexyloctane emulsion results in significantly reduced inflammation, hypoxic injury, and apoptosis and cellular integrity and energy content are well maintained. Histologic examination revealed less tubular, vascular, and glomerular changes in the emulsion-perfused tissue compared with the HTK-perfused counterparts. The concept of perfusing organs with oxygen-precharged emulsion based on organ preservation media represents an efficient alternative for improved organ preservation.
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| 3. |
- Babazadeh, Davood, et al.
(författare)
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Real-Time Estimation of AC-Grid Short Circuit Capacity for HVDC Control Application
- 2016
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Ingår i: IET Generation, Transmission & Distribution. - : IET. - 1751-8687 .- 1751-8695.
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Tidskriftsartikel (refereegranskat)abstract
- Being able to estimate the AC grid strength using Short Circuit Capacity (SCC) fromthe perspective of a connected HVDC station allows adjustment of converter control parameters orto select the converter’s operational control mode. The short circuit capacity can be calculated byestimation of the grid’s impedance and its equivalent voltage. This paper presents the operationaland practical challenges in real-time implementation of the grid estimation algorithms especiallyfor HVDC applications. This paper shows that the Recursive Least Square (RLS) algorithm can bevery efficiently used for the real-time estimation of SCC. This technique forms a regression prob-lem using algebraic complex equations with an objective to minimize the error between estimatedand measured parameters. The algorithm has been reformulated and simplified to make it non-complex without the use of matrices, in order to facilitate further implementation on an industrialreal-time controller. The performance of the real-time implementation has been evaluated usinga HIL platform. A sensitivity analysis has been also carriedout to study the impact of differentparameters and operational conditions on the performance of the estimation algorithm. Finally, theactual application of real-time SCC estimation for the HVDCsystems has been demonstrated.
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| 4. |
- Babazadeh, Davood, et al.
(författare)
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Selection of DC Voltage Controlling Station in an HVDC Grid
- 2016
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 144, s. 224-232
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a real-time quantitative evaluation of HVDC converters’ in an HVDC grid to select the suitable DC slack converter. This real-time evaluation considers the strength of connecting AC grid and the converter's on-line capacity margin as selection metrics. The strength of AC grid is evaluated in real-time by the estimation of grid short circuit capacity using recursive lease square algorithm. Given these selection metrics, the credibility of HVDC stations in controlling the DC voltage can be offered to the system operator in real-time for further operational decisions. This paper also studies the practical aspect of the estimation algorithm regarding selection of the operating points. As major contribution, it suggests to intelligently use a naturally occurring droop response in HVDC grids as a second operating point in the estimation algorithm to calculate the short circuit capacity. The method has been tested through set of scenarios using a real-time co-simulation platform. This platform includes real-time power system simulator to model AC/DC grid, industrial HVDC controllers and corresponding ICT systems. The results show that the proper selection of DC slack station can improve the AC system response and DC voltage drops during disturbances.
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| 5. |
- Babazadeh, Davood, et al.
(författare)
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Short Circuit Capacity Estimation for HVDC Control Application
- 2016
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Ingår i: Power Systems Computation Conference (PSCC), 2016. - : IEEE conference proceedings.
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Konferensbidrag (refereegranskat)abstract
- This paper studies various operational aspects ofrecursive least square algorithm as a potential solution for theestimation of short circuit capacity in HVDC application. Inthis work, low computational requirement, minor operationalcomplication and acceptable accuracy of the estimated gridparameters have been considered as the performance metricsfor the selection of the suitable estimation algorithm. The chosenalgorithm forms a regression problem using at least two algebraiccomplex equations based on two different operating points. Theappropriate selection of the second operating point which fulfillsthe minimum required accuracy and convergence rate is of greatimportance, particularly in the practical implementation. Thispaper proposes and analyzes several choices of providing thesecond operating point for the estimation algorithm adopted toHVDC application. Furthermore, a sensitivity analysis has beencarried out to assess the impact of different parameters andoperational conditions such as execution time on the performanceof the estimation algorithm for the HVDC control purposes.
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| 6. |
- Bengtsson, Lars, et al.
(författare)
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The REMAP Reconfigurable Architecture : a Retrospective
- 2006
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Ingår i: FPGA Implementations of Neural Networks. - New York : Springer-Verlag New York. - 0387284850 ; , s. 325-360
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Bokkapitel (refereegranskat)abstract
- The goal of the REMAP project was to gain new knowledge about the design and use of massively parallel computer architectures in embedded real-time systems. In order to support adaptive and learning behavior in such systems, the efficient execution of Artificial Neural Network (ANN) algorithms on regular processor arrays was in focus. The REMAP-β parallel computer built in the project was designed with ANN computations as the main target application area. This chapter gives an overview of the computational requirements found in ANN algorithms in general and motivates the use of regular processor arrays for the efficient execution of such algorithms. REMAP-β was implemented using the FPGA circuits that were available around 1990. The architecture, following the SIMD principle (Single Instruction stream, Multiple Data streams), is described, as well as the mapping of some important and representative ANN algorithms. Implemented in FPGA, the system served as an architecture laboratory. Variations of the architecture are discussed, as well as scalability of fully synchronous SIMD architectures. The design principles of a VLSI-implemented successor of REMAP-β are described, and the paper is concluded with a discussion of how the more powerful FPGA circuits of today could be used in a similar architecture. © 2006 Springer.
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| 10. |
- Eggers, Jeannette, et al.
(författare)
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Balancing different forest values: Evaluation of forest management scenarios in a multi-criteria decision analysis framework
- 2019
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Ingår i: Forest Policy and Economics. - : Elsevier BV. - 1389-9341 .- 1872-7050. ; 103, s. 55-69
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Tidskriftsartikel (refereegranskat)abstract
- Besides traditional timber production, other forest functions, such as biodiversity and recreation, have gained increasing importance during the last few decades. Demands on forests have become more diversified, thus making forest management and planning more complex. To meet these challenges, there is a growing interest in a more diversified silviculture, for which a number of different management options are available. However, it remains unclear how the various management options affect economic, ecological, and social aspects of sustainable forest management. Hence, in this study, we assess the consequences of various management options on different aspects of sustainable forest management through scenario analysis using a forestry decision support system. We evaluate 10 different forest management scenarios for two contrasting municipalities in Sweden, based on expert participation by way of a web-based multi-criteria decision analysis framework. We asked experts in economic, ecological, and social forest values, as well as those in reindeer husbandry, to weigh a number of indicators in their field of expertise against each other, and to create value functions for each indicator. We then determined scenario ranking for different sets of weights for economic, ecological and social forest values. Our results indicate that current management practices are favorable for economic aspects (wood production), while a number of scenarios would be better suited to fulfill the Swedish co-equal forest policy goal of production and consideration of environmental issues, such as scenarios with longer rotation periods, a larger share of set-asides and a higher share of continuous cover forestry. These measures would be beneficial not only for ecological values, but also for social values and for reindeer husbandry. Furthermore, we found that expert participation through the web-tool was a promising alternative to physical meetings that require more commitment in terms of time and resources.
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