| 1. |
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| 2. |
- Eriksson, Daniel, et al.
(författare)
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Health-related quality of life across all stages of autosomal dominant polycystic kidney disease
- 2017
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Ingår i: Nephrology, Dialysis and Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 32:12, s. 2106-2111
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A limited number of studies have assessed health-related quality of life (HRQoL) in autosomal dominant polycystic kidney disease (ADPKD). Results to date have been conflicting and studies have generally focused on patients with later stages of the disease. This study aimed to assess HRQoL in ADPKD across all stages of the disease, from patients with early chronic kidney disease (CKD) to patients with end-stage renal disease.METHODS: A study involving cross-sectional patient-reported outcomes and retrospective clinical data was undertaken April-December 2014 in Denmark, Finland, Norway and Sweden. Patients were enrolled into four mutually exclusive stages of the disease: CKD stages 1-3; CKD stages 4-5; transplant recipients; and dialysis patients.RESULTS: Overall HRQoL was generally highest in patients with CKD stages 1-3, followed by transplant recipients, patients with CKD stages 4-5 and patients on dialysis. Progressive disease predominately had an impact on physical health, whereas mental health showed less variation between stages of the disease. A substantial loss in quality of life was observed as patients progressed to CKD stages 4-5.CONCLUSIONS: Later stages of ADPKD are associated with reduced physical health. The value of early treatment interventions that can delay progression of the disease should be considered.
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| 3. |
- Eriksson, Daniel, et al.
(författare)
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Real-world costs of autosomal dominant polycystic kidney disease in the Nordics
- 2017
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Ingår i: BMC Health Services Research. - : Springer Science and Business Media LLC. - 1472-6963. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is limited real-world data on the economic burden of patients with autosomal dominant polycystic kidney disease (ADPKD). The objective of this study was to estimate the annual direct and indirect costs of patients with ADPKD by severity of the disease: chronic kidney disease (CKD) stages 1-3; CKD stages 4-5; transplant recipients; and maintenance dialysis patients. Methods: A retrospective study of ADPKD patients was undertaken April-December 2014 in Denmark, Finland, Norway and Sweden. Data on medical resource utilisation were extracted from medical charts and patients were asked to complete a self-administered questionnaire. Results: A total of 266 patients were contacted, 243 (91%) of whom provided consent to participate in the study. Results showed that the economic burden of ADPKD was substantial at all levels of the disease. Lost wages due to reduced productivity were large in absolute terms across all disease strata. Mean total annual costs were highest in dialysis patients, driven by maintenance dialysis care, while the use of immunosuppressants was the main cost component for transplant care. Costs were twice as high in patients with CKD stages 4-5 compared to CKD stages 1-3. Conclusions: Costs associated with ADPKD are significant and the progression of the disease is associated with an increased frequency and intensity of medical resource utilisation. Interventions that can slow the progression of the disease have the potential to lead to substantial reductions in costs for the treatment of ADPKD.
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| 4. |
- Jay, Raphael M., et al.
(författare)
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Disentangling Transient Charge Density and Metal-Ligand Covalency in Photoexcited Ferricyanide with Femtosecond Resonant Inelastic Soft X-ray Scattering
- 2018
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 9:12, s. 3538-3543
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Tidskriftsartikel (refereegranskat)abstract
- Soft X-ray spectroscopies are ideal probes of the local valence electronic structure of photocatalytically active metal sites. Here, we apply the selectivity of time resolved resonant inelastic X-ray scattering at the iron L-edge to the transient charge distribution of an optically excited charge-transfer state in aqueous ferricyanide. Through comparison to steady-state spectra and quantum chemical calculations, the coupled effects of valence-shell closing and ligand-hole creation are experimentally and theoretically disentangled and described in terms of orbital occupancy, metal-ligand covalency, and ligand field splitting, thereby extending established steady-state concepts to the excited-state domain. pi-Back-donation is found to be mainly determined by the metal site occupation, whereas the ligand hole instead influences sigma-donation. Our results demonstrate how ultrafast resonant inelastic X-ray scattering can help characterize local charge distributions around catalytic metal centers in short-lived charge-transfer excited states, as a step toward future rationalization and tailoring of photocatalytic capabilities of transition-metal complexes.
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| 5. |
- Jonson, Emma, 1981, et al.
(författare)
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Exploring the competition between variable renewable electricity and a carbon-neutral baseload technology
- 2020
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Ingår i: Energy Systems. - : Springer Science and Business Media LLC. - 1868-3975 .- 1868-3967. ; 11:1, s. 21-44
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we explore the competition between variable renewable energy sources (VRE) and a carbon-neutral baseload technology in the transition to a low-carbon power system. We study a stylized system subject to a gradually increasing carbon tax using an agent-based model where agents are power companies investing in new capacity. The agents make predictions of the profitability of different investment options. Five electricity generating technologies are available in the model: coal, gas, wind, solar PV and a more expensive carbon-neutral baseload technology. We compare the output from our model with a corresponding optimization model. We present two main findings: (1) installed capacity of VRE initially increases with a carbon tax. However, once the carbon tax has reached a certain level the installed capacity of VRE starts to decline due to competition with the stylized carbon-neutral baseload technology. (2) With limited foresight we find that the model underinvests (first 25 years) in wind and then overinvests in wind compared to the optimal solution. The reasons for these dynamic phenomena are explained and an extensive sensitivity analysis is carried out.
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| 6. |
- Jonson, Emma, 1981, et al.
(författare)
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Impacts on Stability of Interdependencies Between Markets in a Cobweb Model
- 2015
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Ingår i: Lecture Notes in Economics and Mathematical Systems. - Cham : Springer International Publishing. - 2196-9957 .- 0075-8442. ; 676, s. 195-205
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Tidskriftsartikel (refereegranskat)abstract
- We present a cobweb model of interdependent markets on both the sup- ply and demand sides and apply it to a food and bioenergy framework. The supply side is represented by an agent based model of global land use while the consumer side consists of interlinked demand functions. We find that the two kinds of inter- dependencies have opposing effects. Linking markets on the supply side transfers instabilities within the system and may cause price fluctuations in previously sta- ble markets. Market interdependency on the demand side, on the other hand, has a stabilizing effect.
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| 7. |
- Karlsson, Kristian, et al.
(författare)
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Test Level in Reverberation Chamber EMC Immunity Assessment Based on the Quantile to Average Ratio
- 2022
-
Ingår i: IEEE International Symposium on Electromagnetic Compatibility. Volume 2022-September, 2022, Pages 178-182. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665407878 ; , s. 178-182
-
Konferensbidrag (refereegranskat)abstract
- As more and more advanced electronics are incorporated into devices and vehicles, there is a need to improve and refine the test methods for performance assessment of electromagnetic compatibility. Traditional standards in reverberation chamber electromagnetic compatibility immunity assessment define the test level according to a calibration based on an average of maximum received electrical field probe readings. In this paper, we propose a converging approach based on the average, in combination with an additional offset to generate a quantile defined test level.
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| 8. |
- Lindgren, Kristian, 1960, et al.
(författare)
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Projection of a Heterogenous Agent-Based Production Economy Model to a Closed Dynamics of Aggregate Variables
- 2015
-
Ingår i: Advances in Complex Systems. - 0219-5259. ; 18:5-6, s. 1550012-
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Tidskriftsartikel (refereegranskat)abstract
- A model framework that describes a simple production economy is presented, in which the micro-dynamics can be projected to a closed dynamics of aggregate variables. The construction is based on an agent-based model with heterogeneity both regarding pro- duction characteristics and the strategies agents use to predict future prices as a basis for choosing what to produce. The world is divided into a number of regional markets that collect the locally produced goods and via inter-market trade supply regional demands with goods. We discuss the model features that make it possible to project the agent- based micro-dynamics to a closed form dynamics on the level of regionally aggregate quantities. One advantage of such a projection from a high dimensional agent-based dynamics to a low dimensional dynamical system is that the stability characteristics can be analytically approached, and this is illustrated by a derived condition for when a mix of naive and rational agents can stabilize the system. Some illustrations of the general framework in a model of global agricultural land-use are also given.
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| 9. |
- Lundberg, Anders, 1966-, et al.
(författare)
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Structures of loyalty : A comparative study of Jewish and Palestinian evangelicals’ acquiescence to fundamentalist and authoritarian values
- 2022
-
Ingår i: ID: International Dialogue. - Omaha, Nebraska : University of Nebraska. - 2155-160X. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- This is a qualitative comparative study of two evangelical movements in Israel and in the West Bank: the Israeli Messianic (IM) movement and the Palestinian Evangelical (PE) movement. Through interviews on how informants understand the Middle Eastern conflict, our aim is (1) to compare the prevalence of fundamentalist/authoritarian (F/A) values in the IM and PE movements and (2) to understand how a particular socio-political context – Israel and the West Bank – might affect the acquiescence to a F/A mindset amongst the two movements. To accomplish this, we created a F/A construct that measures five values: literalism, social withdrawal, authoritarian aggression, authoritarian submission, and conventionalism. We found that the IM scores higher on all five F/A values. To explain the difference, we point out the importance of structures of loyalty: the difference in how IMs and PEs connect to key societal groups affects the way they acquiesce to fundamentalist and authoritarian values.
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| 10. |
- Lundberg, Anders, 1966-, et al.
(författare)
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The remaining few : Christian Zionists making sense of a changed ecclesiastic landscape
- 2018
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Ingår i: Journal of Contemporary Religion. - : Taylor & Francis. - 1353-7903 .- 1469-9419. ; 33:1, s. 71-86
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Tidskriftsartikel (refereegranskat)abstract
- Using a hermeneutical method, this study seeks to understand Christian Zionism as a meaningful practice in late modern Sweden. We visited four Christian Zionist conferences: we observed, analysed the sermons, and conducted interviews. The conferences are almost entirely attended by elderly people and the style is characterized by an old-time revivalist nostalgia. Results show that Israel is seen as key to understanding a general conflict that the informants experience in late modern Swedish society, and in relation to the majority church. Supporting Israel is intertwined with support for conservative values and theology, and Israel becomes a nodal point that puts the greater conflict in new perspective: identifying with Old Testament prophecies and God’s dealings with Israel gives hope and a sense of continuity to a revivalist movement that has become out-of-date. In Israel they connect with both the past and the future, personally and as a movement.
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| 11. |
- Lundberg, Kristian
(författare)
-
Effect Oriented Planning in Military Mission Support Systems : Models and Heuristic Approaches
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today there are many aspects of model based planning, probably much more than for just 20 years ago. Today data is not the problem, data is everywhere, but the big issue is to understand how to gain advantage of data in decision making - a growing focus is now on modeling!This work is devoted to this task and can be seen as a three part study. First a general problem of multi-resource routing with sequence dependent costs is studied both in terms of models, as well as the development of methods to solve this class of problems efficiently. Sequence dependent costs among resources arise in situations where for instance, one resource is allocated to a task which influence another task and makes that easier in the sense that it can be conducted to a lower cost or shorter time or some other measured effort. This is a useful building block in military decision making when making plans for troops, attacks or missions in general.The next part is founded by Vinnova via the research project “Effect Oriented Planning in Dynamic Scenarios”, and deals with a military ground attack problem with simultaneous attacks against a plurality of targets. This part deals with the difficulties of the attacker-defender problem which is modeled in a Nonlinear Mixed Integer Programming formulation. Suggestions are given how to refine and transform this into robust solution methods.The last part, also included in the Vinnova research project, deals with mission support modeling of Air to Ground missions including multiple aircrafts and a plurality of targets. In this case, sequencing is most important and a strong effort has been put in the understanding and transformation of the problem into models and methods.In these last two parts implementations of models and heuristics as well as computer runs and simulations, originates from the work in [19] and [20] which has been an invaluable contribution to this work.The results are very promising where fast execution and sufficient planning accuracy have drawn the attention as a foundation for future work and research in model based decision making applicable to industry needs and ambitions.
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| 12. |
- Lundberg, Liv, 1987, et al.
(författare)
-
A cobweb model of land-use competition between food and bioenergy crops
- 2015
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Ingår i: Journal of Economic Dynamics and Control. - : Elsevier BV. - 0165-1889. ; 53, s. 1-14
-
Tidskriftsartikel (refereegranskat)abstract
- We present a model of interacting cobweb markets and apply it to land-use competition between food and bioenergy crops. In our model the markets are interlinked on the supply side by the limited availability of land. Therefore, instabilities are transferred between the markets and we find that bioenergy demand affects food price volatility. The agents in the model have heterogeneous production capacities, representing variation in global land quality. When we allow agents to choose price predictor, we find that a more sophisticated (but costly) predictor is concentrated to some key parcels of land, which enables the system to reduce instability significantly. The system can also be brought closer to a stable state by introducing costs for changing production type, but it may then be shifted away from the optimum situation predicted by the corresponding equilibrium model.
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| 13. |
- Lundberg, Liv, 1987, et al.
(författare)
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Context Matters: Exploring the Cost-effectiveness of Fixed Payments and Procurement Auctions for PES
- 2018
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Ingår i: Ecological Economics. - : Elsevier BV. - 0921-8009. ; 146, s. 347-358
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Tidskriftsartikel (refereegranskat)abstract
- Successfully implemented payment for ecosystem services (PES) programs can provide both conservation of nature and financial support to rural communities. In this paper, we explore how PES programs can be designed so as to maximize the amount of additional ecosystem services provided for a given budget. We also provide a brief summary of the use of auction mechanisms in real world PES programs. To explore the potential additionality of different PES program designs we use a conceptual agent based simulation model where payments are either fixed, or set through a uniform or discriminatory auction. The program can also be designed to target payments to land-owners based on their provision of ecosystem services. Theoretically, auctions should be the most effective design, especially if payments are differentiated and targeted by ecosystem service provision. However, what we find is that the context in which the PES program is implemented—baseline compliance with program standards among the participants, correlation between opportunity costs and ecosystem services in the landscape, heterogeneity in costs and budget size—has a determining impact on the relative effectiveness of the different payment designs, with fixed payments schemes being much more effective than auctions in certain settings. Our findings suggest that context should be taken into serious consideration when a PES program design is chosen.
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| 14. |
- Lundberg, Valeria, 1984, et al.
(författare)
-
Converting a kraft pulp mill into a multi-product biorefinery – Part 1: Energy aspects
- 2013
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Ingår i: Nordic Pulp and Paper Research Journal. - 2000-0669 .- 0283-2631. ; 28:4, s. 480-488
-
Tidskriftsartikel (refereegranskat)abstract
- Conversion from kraft pulp into dissolving pulp production is an interesting development since it allows the production of a pulp with higher market value, as well as the production of valuable by-products, for example, hemicellulose, lignin, electricity, and/or heat. In this paper the major energy consequences of converting a modern kraft pulp mill into dissolving pulp production were investigated.Three critical choices for process configuration were examined:a) export the hydrolysate (extracted hemicellulose liquor) to an upgrading plant vs. combustion of the hydrolysateb) level of heat integrationc) type of by-products produced (electricity or lignin)The results show that conversion into dissolving pulp production affects the energy balance of the mill considerably and can drastically affect the pulp production capacity of the mill, e.g. if the recovery boiler is the bottleneck. Sending the hydrolysate to combustion decreases the pulp production capacity, whereas lignin separation can debottleneck the recovery boiler and allow for higher pulp production. A higher level of heat integration increases the possibilities for debottlenecking and/or producing by-products. The conclusion is that an economic assessment is necessary in order to identify the most attractive process configuration. This assessment will be presented in the second part of this study.
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| 15. |
- Lundberg, Valeria, 1984, et al.
(författare)
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Converting a kraft pulp mill into a multi-product biorefinery – Part 2: Economical aspects
- 2013
-
Ingår i: Nordic Pulp and Paper Research Journal. - 2000-0669 .- 0283-2631. ; 28:4, s. 489-497
-
Tidskriftsartikel (refereegranskat)abstract
- Conversion into dissolving pulp production is an interesting pathway for kraft pulp mills experiencing decreasing marginal revenues. In this two-part study, the technical and economic consequences of the conversion have been investigated.In Part 1, the energy aspects of converting into dissolving pulp production were studied, as well as the consequences on the by-product and pulp production capacity of the converted mill.In this paper, the economic performance of different process configurations is evaluated. Our results indicate that the price of dissolving pulp and the pulp production capacity of the mill have the largest influence on the overall profitability. Accordingly, in order to achieve high profitability, it is necessary to debottleneck the mill’s capacity for pulp production. Debottlenecking the recovery boiler by upgrading capacity and increasing power generation requires large investments and downtime costs but can be profitable if the price of electricity is high. Debottlenecking by means of lignin separation can nevertheless be more interesting if lignin is valued high or if investment capital is limited. Regardless of the way the recovery boiler is debottlenecked, a higher level of heat integration is always more attractive than a lower, simpler level of heat integration.
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| 16. |
- Lundberg, Valeria, 1984, et al.
(författare)
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Converting a kraft pulp mill into a multi-product biorefinery: techno-economic analysis of a case mill
- 2014
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Ingår i: Clean Technologies and Environmental Policy. - : Springer Science and Business Media LLC. - 1618-954X .- 1618-9558. ; 16:7, s. 1411-1422
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Tidskriftsartikel (refereegranskat)abstract
- In this case study, we investigated the conversion of an existing Swedish kraft pulp mill to the production of dissolving pulp, with export of electricity, lignin, and a hemicellulose stream suitable for upgrading. By increasing the level of heat integration of the mill, it was possible to achieve self-sufficiency in terms of steam and to produce significant amounts of excess steam. The excess steam could facilitate the integration of a lignin separation plant or be used for power generation. The production of dissolving pulp requires a higher input of wood that is required for the same level of pulp production as is achieved with kraft pulp. For the studied mill, the batch digester was the main limitation for pulp production. Nevertheless, if the digester capacity was increased, then the level of pulp production could be maintained. In addition, the recovery boiler, causticization plant, and evaporation plant had sufficient capacities for preserving the same production level upon conversion, and could easily be upgraded to a certain degree through relatively simple measures for an increase in pulp production. However, increasing pulp production beyond that limit required extensive upgrades or investments in new equipment, which negatively affected annual earnings. Annual earnings were found to be also dependent upon the level of heat integration, type of by-product, and the costs for lignin and electricity. However, our results suggest that the optimal process configuration is more dependent upon other factors, such as the long-term vision of the company and policy instruments.
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| 17. |
- Lundberg, Valeria, 1984, et al.
(författare)
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Energy Analysis for Conversion of a Kraft Pulp Mill into a Dissolving Pulp Mill
- 2012
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Ingår i: Chemical Engineering Transactions. - 2283-9216 .- 2283-9216. ; 29, s. 13-18
-
Tidskriftsartikel (refereegranskat)abstract
- Currently, kraft pulp mills in Europe and North America are facing several challenges and have been forced to think along new products and new business areas. One opportunity is the conversion of chemical pulp mills into dissolving pulp mills by extracting hemicellulose prior to digesting via pre-hydrolysis. From the extracted wood chips, the more valuable dissolving pulp can be produced whereas the hydrolysate can be upgraded to high-value products. In this paper, pinch analysis is used to evaluate the consequences in the energy balance and utility system of a kraft mill converted into dissolving pulp production as well as to identify the potential for heat integration within the host mill itself, between the host mill and the pre-hydrolysis unit and with a hemicellulose upgrading process. The results show that proper heat integration within the host mill itself, and between the host mill and the pre-hydrolysis unit gives significant amounts of surplus steam which could be exported to a hemicelluloses upgrading process, used for power generation or to facilitate lignin extraction.
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| 18. |
- Lundberg, Valeria, 1984, et al.
(författare)
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Enlarging the Product Portfolio of a Kraft Pulp Mill via Hemicellulose and Lignin Separation – Process Integration Studies in a Case Mill
- 2013
-
Ingår i: Chemical Engineering Transactions. - 2283-9216 .- 2283-9216. ; 35, s. 127-132
-
Tidskriftsartikel (refereegranskat)abstract
- Increased energy and raw material prices along with contracting markets for kraft pulp, have highlighted the need for the pulp industry to enlarge their traditional product portfolio with new value-added products via the implementation of biorefinery concepts. In this paper, we have investigated potentials for enlarging the product portfolio of a kraft pulp mill by extracting hemicellulose prior to digesting and in this way, converting to dissolving pulp production.A case study has been performed on a Swedish kraft pulp mill, in order to evaluate the consequences of the original mill configuration, level of heat integration and choice of by-products produced have on theoverall profitability of the mill upon conversion to dissolving pulp production. For the mill studied, the batch digester is identified to be the bottleneck for both kraft and dissolving pulp production. If the digester capacity is increased by e.g. purchasing new effects, the pulp production could be maintained.The results from the energy study indicate that dissolving pulp production is more heat demanding than kraft production. However, by increasing the heat integration of the mill, it is possible to, not only become self-sufficient in terms of steam, but also to produce significant amounts of excess steam. The steam excess facilitates integration of a lignin separation plant or can be used for power generation.The net annual profit was evaluated for varying prices of electricity and lignin. For the economic conditions studied, lignin separation was always better than power generation, if lignin can be priced as oil.
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| 19. |
- Lundberg, Valeria, 1984, et al.
(författare)
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Process integration of near-neutral hemicellulose extraction in a Scandinavian kraft pulp mill - Consequences for the steam and Na/S balances
- 2012
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 43, s. 42-50
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Tidskriftsartikel (refereegranskat)abstract
- While in a conventional kraft pulp mill, most of the hemicellulose and lignin fraction of the wood is burned in the recovery boiler to produce steam, in a biorefinery it can partially be used to produce added-value products. In this paper, the most important consequences of integrating a bioethanol production plant with a model pulp mill are presented in terms of steam and Na/S balances. The model mill represents an average Scandinavian hardwood kraft pulp mill, and the bioethanol plant is based on the "near-neutral" hemicellulose pre-extraction method. Regarding the steam balance, a comprehensive heat integration study is performed. Implementing hemicellulose extraction increases the net steam demand by 48 MW. However, process integration at the mill and the bioethanol plant individually leads to significant steam savings, and a corresponding net increase of steam by only 3 MW. Additional steam savings can be achieved if the total integration of the two processes (between the pulp mill and the bioethanol plant) is considered (3 MW), resulting in a biorefinery with no increase of steam demand. As regards the Na/S balance, it is shown that green liquor export from the mill to the bioethanol plant results in severe disruptions in the sodium and sulphur balance of the mill. Different attempts to solve this problem are discussed, but are very costly and/or negatively affect the water and steam balance of the mill.
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| 20. |
- Mullier, G.A., et al.
(författare)
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Search for quantum black hole production in lepton + jet final states using proton-proton collisions at vs = 13 TeV with the ATLAS detector
- 2024
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 109:3
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Tidskriftsartikel (refereegranskat)abstract
- A search for quantum black holes in electron + jet and muon + jet invariant mass spectra is performed with 140 fb-1 of data collected by the ATLAS detector in proton-proton collisions at √s = 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton + jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model. © 2024 CERN, for the ATLAS Collaboration.
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| 21. |
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| 22. |
- Obradovic, Gabrijela, 1994, et al.
(författare)
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Scheduling the repair and replacement of individual components in operating systems: a bi-objective mathematical optimization model
- 2024
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Ingår i: Journal of Scheduling. - 1099-1425 .- 1094-6136. ; 27:1, s. 87-101
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Tidskriftsartikel (refereegranskat)abstract
- Preventive maintenance (PM) is performed so that failure is avoided while corrective maintenance is performed after a failure has occurred in order to restore the system back to an operational state. This research aims at scheduling PM activities for a multi-component system within a finite time horizon. We consider a setting with two stakeholders, being the system operator and themaintenanceworkshop, and two different contract types governing their joint activities, namely an availability contract and a turn-around time contract. Components in the systems that are to be maintained are sent to the maintenance workshop, which needs to schedule and perform all maintenance activities while at the same time satisfying the contract and not exceeding the workshop capacity. Our modelling is based on a mixed-binary linear optimization model of a PM scheduling problem with so-called interval costs over a finite and discretized time horizon.We enhance this scheduling model with the flow of individual components through the maintenance workshop, including stocks of spare components, both those components that need repair and the repaired ones. The resulting scheduling model is then utilized in the optimization of two main contracts, namely maximizing the availability of repaired (or new) components and minimizing the deviation from the contracted turn-around times for the components in the maintenance loop. Each of these objectives is combined with the objective to minimize the costs for maintenance of the operating system, leading to two bi-objective optimization problems. We analyse the two contracting forms between the stakeholders by studying and comparing the Pareto fronts resulting from different parameter settings, regarding minimum allowed stock levels and investments in repair capacity of the workshop. Our bi-objective mixed-binary linear optimization model is able to capture important properties of the results from the contracting forms as well as to show that, in our setting, an availability contract performs better than a turn-around time contract in terms of tractability.
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| 23. |
- Obradovic, Gabrijela, 1994, et al.
(författare)
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Simultaneous scheduling of preventive system maintenance and of the maintenance workshop
- 2020
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Ingår i: PLANs forsknings-och tillämpningskonferens.
-
Konferensbidrag (refereegranskat)abstract
- While a system operates, its components deteriorate and in order for the system to remain operational, maintenance of its components is required. Preventive maintenance (PM) is performed so that component failure is avoided. This research aims at scheduling PM activities for a multi-component system within a finite horizon. The system to be maintained possesses positive economic dependencies, meaning that each time any component maintenance activity is performed, a common set-up cost is generated. Each component PM activity generates a cost, including replacement, service, and spare parts costs. We start from a 0-1 mixed integer linear optimization model of the PM scheduling problem with interval costs, which is to schedule PM of the components of a system over a finite and discretized time horizon, given common set-up costs and component costs, of which the latter vary with the maintenance interval. We extend the PMSPIC model to incorporate the flow of components through the maintenance/repair workshop, including stocks of spare components, both the components that require repair and the repaired ones. Our resulting model is a tight integration of the PM and the maintenance workshop scheduling. We investigate two different contract types between stakeholders, present and analyze preliminary numerical results obtained.
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| 24. |
- Obradovic, Gabrijela, 1994, et al.
(författare)
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Simultaneous scheduling of replacement and repair of common components in operating systems A multi-objective mathematical optimization model
- 2022
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Ingår i: Annals of Operations Research. - : Springer Science and Business Media LLC. - 0254-5330 .- 1572-9338. ; 322, s. 147-65
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Tidskriftsartikel (refereegranskat)abstract
- In order for a system to stay operational, its components need maintenance. We consider two stakeholders-a system operator and a maintenance workshop-and a contract governing their joint activities. Components in the operating systems that are to be maintained are sent to the maintenance workshop, which should perform all maintenance activities on time in order to satisfy the contract. The maintained components are then sent back to be used in the operating systems. Our modeling of this system-of-systems includes stocks of damaged and repaired components, the workshop scheduling, and the planning of preventive maintenance for the operating systems. Our modeling is based on a mixed-binary linear optimization (MBLP) model of a preventive maintenance scheduling problem with so-called interval costs over a finite and discretized time horizon. We generalize and extend this model with the flow of components through the workshop, including the stocks of spare components. The resulting scheduling model-a mixed-integer optimization (MILP) model-is then utilized to optimize the main contract in a bi-objective setting: maximizing the availability of repaired (or new) components and minimizing the costs of maintaining the operating systems over the time horizon. We analyze the main contract and briefly discuss a turn-around time contract. Our results concern the effect of our modeling on the levels of the stocks of components over time, in particular minimizing the risk for lack of spare components.
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| 25. |
- Priskorn, Lærke, et al.
(författare)
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RUBIC (ReproUnion Biobank and Infertility Cohort) : A binational clinical foundation to study risk factors, life course, and treatment of infertility and infertility-related morbidity
- 2021
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Ingår i: Andrology. - : Wiley. - 2047-2919 .- 2047-2927. ; 9:6, s. 1828-1842
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Tidskriftsartikel (refereegranskat)abstract
- Background: Infertility affects 15%–25% of all couples during their reproductive life span. It is a significant societal and public health problem with potential psychological, social, and economic consequences. Furthermore, infertility has been linked to adverse long-term health outcomes. Despite the advanced diagnostic and therapeutic techniques available, approximately 30% of infertile couples do not obtain a live birth after fertility treatment. For these couples, there are no further options to increase their chances of a successful pregnancy and live birth. Objectives: Three overall questions will be studied: (1) What are the risk factors and natural life courses of infertility, early embryonic loss, and adverse pregnancy outcomes? (2) Can we develop new diagnostic and prognostic biomarkers for fecundity and treatment success? And (3) what are the health characteristics of women and men in infertile couples at the time of fertility treatment and during long-term follow-up?. Material and Methods: ReproUnion Biobank and Infertility Cohort (RUBIC) is established as an add-on to the routine fertility management at Copenhagen University Hospital Departments in the Capital Region of Denmark and Reproductive Medicine Centre at Skåne University Hospital in Sweden. The aim is to include a total of 5000 couples equally distributed between Denmark and Sweden. The first patients were enrolled in June 2020. All eligible infertile couples are prospectively asked to participate in the project. Participants complete an extensive questionnaire and undergo a physical examination and collection of biospecimens (blood, urine, hair, saliva, rectal swabs, feces, semen, endometrial biopsies, and vaginal swabs). After the cohort is established, the couples will be linked to the Danish and Swedish national registers to obtain information on parental, perinatal, childhood, and adult life histories, including disease and medication history. This will enable us to understand the causes of infertility and identify novel therapeutic options for this important societal problem.
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| 26. |
- Quttineh, Nils-Hassan, 1979-, et al.
(författare)
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Aircraft Mission Planning
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper deals with a Military Aircraft Mission Planning Problem, where the problem is to find time efficient flight paths for a given aircraft fleet that should attack a number of ground targets. Due to the nature of the attack, two aircraft need to rendezvous at the target, that is, they need to be synchronized in both space and time. At the attack, one aircraft is launching a guided weapon, while the other is illuminating the target. Each target is associated with multiple attack and illumination options. Further, there may be precedence constraints between targets, limiting the order of the attacks. The objective is to maximize the outcome of the entire attack, while also minimizing the mission time span. We present two mathematical models for this problem and compare their efficiency on some small test cases. We also provide some heuristic approaches since direct application of a general MIP solver to the mathematical model is only practical for smaller scenarios. The heuristics are compared and they successfully provide solutions to a number of scenarios.
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| 27. |
- Quttineh, Nils-Hassan, 1979-, et al.
(författare)
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Effect Oriented Planning
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The problem setting concerns the tactical planning of a military operation. Imagine a big wide open area where a number of interesting targets are positioned. It could be radar stations or other surveillance equipment, with or without defensive capabilities, which the attacker wishes to destroy. Moreover, the targets are possibly guarded by defending units, like Surface-to-Air Missile (SAM) units. The positions of all units, targets and defenders, are known. We consider the problem of the attacker, where the objective is to maximize the expected outcome of a joint attack against the enemy, subject to a limited amount of resources (i.e. aircraft, tanks). We present a mathematical model for this problem, together with alternative model versions which provide optimistic and a pessimistic approximations. The model is not efficient for large problem instances, hence we also provide heuristic solution approaches and successfully provide solutions to a number of scenarios.
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| 28. |
- Quttineh, Nils-Hassan, 1979-, et al.
(författare)
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Effect Oriented Planning of Joint Attacks
- 2013
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Ingår i: Optimization Theory, Decision Making, and Operations Research Applications. - New York, NY : Springer-Verlag New York. - 9781461451334 - 9781461451341 ; , s. 49-70
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Konferensbidrag (refereegranskat)abstract
- We consider tactical planning of a military operation on a large target scene where a number of specific targets of interest are positioned, using a given number of resources which can be, for example, fighter aircraft, unmanned aerial vehicles, or missiles. The targets could be radar stations or other surveillance equipment, with or without defensive capabilities, which the attacker wishes to destroy. Further, some of the targets are defended, by, for example, Surface-to-Air Missile units, and this defense capability can be used to protect also other targets. The attacker has knowledge about the positions of all the targets and also a reward associated with each target. We consider the problem of the attacker, who has the objective to maximize the expected outcome of a joint attack against the enemy. The decisions that can be taken by the attacker concern the allocation of the resources to the targets and what tactics to use against each target. We present a mathematical model for the attacker’s problem. The model is similar to a generalized assignment problem, but with a complex objective function that makes it intractable for large problem instances. We present approximate models that can be used to provide upper and lower bounds on the optimal value, and also provide heuristic solution approaches that are able to successfully provide near-optimal solutions to a number of scenarios.
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| 29. |
- Quttineh, Nils-Hassan, 1979-, et al.
(författare)
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Military aircraft mission planning : a generalized vehicle routing model with synchronization and precedence
- 2013
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Ingår i: EURO Journal on Transportation and Logistics. - : Springer. - 2192-4376 .- 2192-4384. ; 2:1-2, s. 109-127
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a military aircraft mission planning problem where agiven fleet of aircraft should attack a number of ground targets. Due to the nature of the attack, two aircraft need to rendez-vous at the target, that is, they need to be synchronized in both space and time. At the attack, one aircraft is launching a guided weapon, while the other is illuminating the target. Each target is associated with multiple attack and illumination options. Further, there may be precedence constraints between targets, limiting the order of the attacks. The objective is to maximize the outcome of the entire attack, while also minimizing the mission timespan. We give a linear mixed integer programming model of the problem, which can be characterized as ageneralized vehicle routing problem with synchronization and precedence side constraints. Numerical results are presented for problem instances of realistic size.
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| 30. |
- Shankar, Vijay, et al.
(författare)
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An Automatic Method for Optimizing Venturi Shape in Cavitation Flows
- 2017
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Ingår i: Proceedings of the 4<sup>th</sup> International Conference of Fluid Flow, Heat and Mass Transfer (FFHMT'17). - : Avestia Publishing. ; 2017
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Konferensbidrag (refereegranskat)abstract
- In order to lower the energy consumption of the fibrillation stage for the pulp and paper industry, a new technology need to be innovated and developed. The current research work deals with a new innovative concept based on creating cavitation in the pulp flow. A venturi nozzle is designed and optimized, where hydrodynamic cavitation is achieved by the so called Venturi effect. This paper focuses on the development of an automatic method for venturi shape optimization. The process of cavitation is hard to control and can cause high mechanical wear, therefore an optimization study of the venturi shape is performed with two main objectives. Firstly, to achieve cavitation that is sustained for as long as possible downstream and secondly to avoid cavitation at the walls. The developed method is a type of two-level optimization based on neural networks and evolutionary optimization. A number of simulations are executed and the optimization is then performed on a solver approximation instead of the real solver, which considerably reduces computation time. The obtained results show the optimal venturi configuration and the relative importance of each shape parameter. The optimal configuration is a clear improvement of the baseline configuration and an improvement also compared to all of the tested samples, thereby validating the optimization method.
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| 31. |
- Shankar, Vijay, et al.
(författare)
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Flow Induced Venturi Cavitation to Improve Energy Efficiency in Pulp Production
- 2018
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Ingår i: Journal of Fluid Flow, Heat and Mass Transfer (JFFHMT). - : Avestia Publishing. - 2368-6111. ; 5, s. 10-17
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Tidskriftsartikel (refereegranskat)abstract
- In order to lower the energy consumption of the fibrillation stage for the pulp and paper industry, a new technology need to be innovated and developed. This paper presents an innovative new design of a venturi nozzle as a concept for refining pulp using hydrodynamic cavitation. The conditions created by cavitation bubbles collapsing near paper fibres are similar to the conditions in conventional refiners used in the pulp and paper industry. The cavitation created in the venturi implodes on the surface of the cellulose fibres, increasing the fibrillation and processing the fibres further. Cavitation is hard to control and can cause high mechanical wear, therefore an optimization study of the venturi nozzle is performed using Computational Fluid Dynamics (CFD) and state-of-the-art optimization techniques. Finally, the optimal venturi shape is investigated in a series of detailed numerical simulations, using a Bingham fibre model to include the effect pulp fibres has on the flow. The investigation shows that cavitation bubbles start to form at an outlet pressure of 1.87 bar, for an inlet pressure of 3.00 bar. The intensity of the bubble collapse depends on the surrounding pressure and this outlet pressure therefore enables a powerful treatment of the pulp fibres. In conclusion, the venturi concept is plausible and seems promising at this stage. More research, in particular physical experiments, is however required before a conclusive verdict can be given.
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| 32. |
- Steiner, Kristian, et al.
(författare)
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Loving Violent Arabs : A Study of Radicalism Within the Israeli Messianic Movement
- 2018
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Ingår i: Expressions of Radicalization. - Cham : Palgrave Macmillan. - 9783319655659 - 9783319655666 - 3319655655 ; , s. 147-180
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Bokkapitel (refereegranskat)abstract
- Steiner and Lundberg examine how Israeli Messianic leaders articulate the hope for peace in the Middle East. More specifically, they draw attention to how Messianic leaders understand the Middle Eastern conflicts and whether this understanding could be considered as radical. All of the informants underline the complexity of the conflicts and most of them tend to emphasize their permanence. The informants are pessimists regarding the conflict, half of them describe it in fatalist terms. This colours their hope for peace; they expect an escalation of the Middle Eastern conflicts, even the apocalypse. And lastly, the informants prefer a one-state solution. In comparison to the Israeli political mainstream, like Likud, the Messianic movement is not necessarily radical.
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| 33. |
- Steiner, Kristian, 1964-, et al.
(författare)
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Peace and End Time Expectations in Christian Zionism : A comparative Analysis of Swedish Christian Zionist Movements
- 2014
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Konferensbidrag (refereegranskat)abstract
- This is a study on how ideas of peace, expressed in Christian Zionist literature, are articulated in Christian Zionist public gatherings in Sweden and Germany.Christian Zionism literature demonstrates very little hope for peace. Arabs are depicted as an obstacle to peace, and inferior. Jews are given appreciative attributes and seen as God’s tool in history, thus instrumentalized. The readership of this literature is required to pray for Israel, but dissuaded from supporting peace initiatives, and from saving Jews on Armageddon.This study scrutinizes whether, to what extent, and how these ideas on peace are expressed in public gatherings in Swedish and German Christian Zionism. Using participant observations, we study what is being said, both from the platform and from partakers, in hymns, prayers, sermons, and what is being conveyed implicitly, including symbols used, signs of emotions, supporting humming in prayer, and centres of attention and authority, and offerings.
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| 34. |
- Steiner, Kristian, et al.
(författare)
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Peace and End Time Expectations in Christian Zionism : A Qualitative Analysis of Swedish Christian Zionist Movements
- 2015
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Ingår i: Nordic Journal of Religion and Society. - Oslo : Fagbokforlaget. - 0809-7291 .- 1890-7008. ; 28:2, s. 117-136
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Tidskriftsartikel (refereegranskat)abstract
- This study examines how the hope for peace in the Middle East is articulated in Swedish Christian Zionist movements, both publicly and in private interviews with leaders and speakers. The article shows that Swedish Christian Zionist movements’ public lectures and sermons rarely address political issues as peace. However, they do reiterate favorable images of Jews and occasionally negative images of Muslims and Arabs. It is apparent in interviews that these leaders and speakers are pessimistic regarding peace in the Middle East. For them, it is not attainable, and, in some cases, it is described as transcendent. In some interviews, Islam, Muslims, and Arabs–in some cases specific Muslim actors–are depicted as inferior, violent, and obstacles to peace. The favorable images of Jews reoccur, and they are instrumentalized, albeit infrequently. Lastly, Christians are repeatedly discouraged to support peace, since it might be false, or to demand Israeli territorial concessions.
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