| 1. |
|
|
| 2. |
|
|
| 3. |
- Strömberg, Ann, et al.
(författare)
-
Jämförelse av arbets-miljöbelastning från betalning med kontanter resp. kort - en arbetsmiljö-LCA
- 2001
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- IVL har tidigare utvecklat en kvantitativ metod för arbetsmiljö-LCA. Metoden kan användas som ett komplement till livscykelanalys (LCA) för den yttre miljön. Metoden bygger på användning av arbetsskadestatstik men är i övrigt analog med metoder för LCA för den yttre miljön. I denna rapport redovisas en fallstudie där en tidigare LCA kompletterats med en arbetsmiljö-LCA. Samma utgångsdata har använts för arbetsmiljö-LCA som för den tidigare genomförda LCAn. Metoden fungerar väl och ger möjlighet till jämförelse och analys av de två betalningsformerna ur arbetsmiljösynpunkt. I rapporten diskuteras resultatet av arbetsmiljön-LCAn och åtgärder för att minska arbetsmiljöbelastningen av kort- respektive kontantbetalning. Den metod som använts diskuteras och jämförelse görs med resultatet av LCAn för den yttre miljön.
|
|
| 4. |
- Strömberg, Dan, 1959, et al.
(författare)
-
Relativistic calculations on some mercury sulphide molecules
- 1991
-
Ingår i: Water Air and Soil Poll. - 0049-6979. ; 56:1, s. 681-695
-
Tidskriftsartikel (refereegranskat)abstract
- Relativistic quantum calculations at the CASSCF- and CCI-levels were performed on the Hg(SH)2, HgSH and HgS molecules. The relativistic effects were taken into account by a relativistic effective core potential method. Dissociation energies and optimal geometries were calculated for these three molecules, which are plausible atmospheric Hg compounds. The Hg(SH)2 and HgSH molecules (in the gaseous phase) have never been studied before, neither experimentally nor theoretically, i.e. the existence of these molecules are uncertain. The theoretical dissociation energies, De's, of Hg(SH)2 and HgSH (at the CCI-level) were 59 kcal·mol–1 and 3 kcal·mol–1, respectively, indicating that Hg(SH)2 could be stable in the atmosphere but probably not HgSH. The theoretical De of HgS differs very much from the experimental one, but the reason for this is not clear. The Hg-S distances for Hg(SH)2, HgSH and HgS were found to be 2.38, 2.63 and 2.30 Å, respectively. The Hg-S-H angle in Hg(SH)2 was optimized to 93°. The excitation energies of Hg(SH)2, Hg(SH)2(H2O)4 and (HSHg)2S were calculated in order to see whether these species can absorb photons with wavelengths longer than 290 nm (the sunlight limit) and subsequently be photolyzed. The Hg(SH)2(H2O)4 complex is intended as a model for Hg(SH)2(aq). Photoreduction of Hg-sulfide species in sea water, yielding Hg0, could be an important source of Hg in the atmosphere. Excitation energies lower than the sunlight limit (4.3 eV290 nm) were found for Hg(SH)2 and Hg(SH)2(H2O)4, although the lowest spin and dipole allowed excitations probably lie slightly (0.2 to 0.3 eV) above this limit. Therefore a photodecomposition of Hg(SH)2(g) and Hg(SH)2(aq) by sunlight seems likely to occur.
|
|
| 5. |
- af Bjerkén, Sara, et al.
(författare)
-
Effects of glial cell line-derived neurotrophic factor deletion on ventral mesencephalic organotypic tissue cultures.
- 2007
-
Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 1133:1, s. 10-9
-
Tidskriftsartikel (refereegranskat)abstract
- Glial cell line-derived neurotrophic factor (GDNF) is potent for survival and promotion of nerve fibers from midbrain dopamine neurons. It is also known to exert different effects on specific subpopulations of dopamine neurons. In organotypic tissue cultures, dopamine neurons form two diverse nerve fiber growth patterns, targeting the striatum differently. The aim of this study was to investigate the effect of GDNF on the formation of dopamine nerve fibers. Organotypic tissue cultures of ventral mesencephalon of gdnf gene-deleted mice were studied. The results revealed that dopamine neurons survive in the absence of GDNF. Tyrosine hydroxylase immunoreactivity demonstrated, in gdnf knockout and wildtype cultures, nerve fiber formation with two separate morphologies occurring either in the absence or the presence of astrocytes. The outgrowth that occurred in the absence of astrocytes was unaffected by gdnf deletion, whereas nerve fibers guided by the presence of astrocytes were affected in that they reached significantly shorter distances from the gdnf gene-deleted tissue slice, compared to those measured in wildtype cultures. Treatment with GDNF reversed this effect and increased nerve fiber density independent of genotype. Furthermore, migration of astrocytes reached significantly shorter distances from the tissue slice in GDNF knockout compared to wildtype cultures. Exogenous GDNF increased astrocytic migration in gdnf gene-deleted tissue cultures, comparable to lengths observed in wildtype tissue cultures. In conclusion, cultured midbrain dopamine neurons survive in the absence of GDNF, and the addition of GDNF improved dopamine nerve fiber formation - possibly as an indirect effect of astrocytic stimulation.
|
|
| 6. |
- Almgren, Torgny, 1962, et al.
(författare)
-
Optimization models for improving periodic maintenance schedules by utilizing opportunities
- 2012
-
Ingår i: Proceedings of 4th Production and Operations Management World Conference, July 2012.
-
Konferensbidrag (refereegranskat)abstract
- We present mathematical models for finding optimal opportunistic maintenance schedules for systems, in which components are assigned maximum replacement intervals. Our mod- els are applied to safety-critical components in an aircraft engine, for which maintenance opportunities naturally arise since entire modules are sent to the workshop when mainte- nance is required on one or more components. Case study results illustrate the advantage of the mathematical models over simpler policies, the benefit of coordinating the maintenance in economically dependent systems, and that our models can be utilized also for strategic investment decision support.
|
|
| 7. |
- Almgren, Torgny, 1962, et al.
(författare)
-
Optimization of opportunistic replacement activities: A case study in the aircraft industry
- 2007
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In the aircraft industry maximizing availability is essential. Maintenance schedules must therefore be opportunistic, incorporating preventive maintenance activities within the scheduled as well as the unplanned ones. At the same time, the maintenance contractor should utilize opportunistic maintenance to enable the minimization of the total expected cost to have a functional aircraft engine and thus to provide attractive service contracts. This paper provides an opportunistic maintenance optimization model which has been constructed and tested together with Volvo Aero Corporation in Trollhättan, Sweden for the maintenance of the RM12 engine. The model incorporates components with deterministic as well as with stochastic lives. The replacement model is shown to have favourable properties; in particular, when the maintenance occasions are fixed the remaining problem has the integrality property, the replacement polytope corresponding to the convex hull of feasible solutions is full-dimensional, and all the necessary constraints for its definition are facet-inducing. We present an empirical crack growth model that estimates the remaining life and also a case study that indicates that a non-stationary renewal process with Weibull distributed lives is a good model for the recurring maintenance occasions. Using one point of support for the distribution yields a deterministic replacement model; it is evaluated against classic maintenance policies from the literature through stochastic simulations. The deterministic model provides maintenance schedules over a finite time period that induce fewer maintenance occasions as well as fewer components replaced.
|
|
| 8. |
|
|
| 9. |
- Almgren, Torgny, 1962, et al.
(författare)
-
The opportunistic replacement problem: analysis and case studies
- 2011
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We consider an optimization model for determining optimal opportunistic maintenance (that is, component replacement) schedules when data is deterministic. This problem generalizes that of Dickman, Epstein, and Wilamowsky [21] and is a natural starting point for the modelling of replacement schedules when component lives are non-deterministic. We show that this basic opportunistic replacement problem is NP-hard. We show that the convex hull of the set of feasible replacement schedules is full-dimensional, and that all the necessary inequalities also are facet-inducing. We show that when maintenance occasions are fixed, the remaining problem can be stated as a linear program; when maintenance costs are monotone with time, the latter is solvable through a greedy procedure. Results from a series of case studies performed in the areas of aircraft engine and wind turbine maintenance are also reported. These illustrate the advantages of utilizing opportunistic maintenance activities based on a complete optimization model, as compared to simpler policies.
|
|
| 10. |
- Almgren, Torgny, 1962, et al.
(författare)
-
The opportunistic replacement problem: theoretical analyses and numerical tests
- 2012
-
Ingår i: Mathematical Methods of Operations Research. - : Springer Science and Business Media LLC. - 1432-2994 .- 1432-5217. ; 76:3, s. 289-319
-
Tidskriftsartikel (refereegranskat)abstract
- We consider a model for determining optimal opportunistic maintenance schedules with respect to a maximum replacement interval. This problem generalizes that of Dickman et al. (J Oper Res Soc India 28:165–175, 1991) and is a natural starting point for modelling replacement schedules of more complex systems. We show that this basic opportunistic replacement problem is NP-hard, that the convex hull of the set of feasible replacement schedules is full-dimensional, that all the inequalities of the model are facet-inducing, and present a new class of facets obtained through a {0,1/2}-Chvátal–Gomory rounding. For costs monotone with time, a class of elimination constraints is introduced to reduce the computation time; it allows maintenance only when the replacement of at least one component is necessary. For costs decreasing with time, these constraints eliminate non-optimal solutions. When maintenance occasions are fixed, the remaining problem is stated as a linear program and solved by a greedy procedure. Results from a case study on aircraft engine maintenance illustrate the advantage of the optimization model over simpler policies. We include the new class of facets in a branch-and-cut framework and note a decrease in the number of branch-and-bound nodes and simplex iterations for most instance classes with time dependent costs. For instance classes with time independent costs and few components the elimination constraints are used favorably. For fixed maintenance occasions the greedy procedure reduces the computation time as compared with linear programming techniques for all instances tested.
|
|
| 11. |
- Almgren, Torgny, 1962, et al.
(författare)
-
The replacement problem: A polyhedral and complexity analysis. The complete version
- 2009
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We consider an optimization model for determining optimal opportunistic maintenance (that is, component replacement) schedules when data is deterministic. This problem, which generalizes that of Dickman et al., is a natural starting point for the modelling of replacement schedules when component lives are non-deterministic, whence a mathematical study of the model is of large interest. We show that the convex hull of the set of feasible replacement schedules is full-dimensional, and that all the necessary inequalities are facet-inducing. Additional facets are then provided through Chvatal-Gomory rounding. We show that when maintenance occasions are fixed, the remaining problem reduces to a linear program; in some cases the latter is solvable through a greedy procedure. We further show that this basic replacement problem is NP-hard.
|
|
| 12. |
- Andersson, Ann-Catrin, et al.
(författare)
-
Analysis of protein expression in cell microarrays : A tool for antibody-based proteomics
- 2006
-
Ingår i: Journal of Histochemistry and Cytochemistry. - 0022-1554 .- 1551-5044. ; 54:12, s. 1413-1423
-
Tidskriftsartikel (refereegranskat)abstract
- Tissue microarray (TMA) technology provides a possibility to explore protein expression patterns in a multitude of normal and disease tissues in a high-throughput setting. Although TMAs have been used for analysis of tissue samples, robust methods for studying in vitro cultured cell lines and cell aspirates in a TMA format have been lacking. We have adopted a technique to homogeneously distribute cells in an agarose gel matrix, creating an artificial tissue. This enables simultaneous profiling of protein expression in suspension- and adherent-grown cell samples assembled in a microarray. In addition, the present study provides an optimized strategy for the basic laboratory steps to efficiently produce TMAs. Presented modifications resulted in an improved quality of specimens and a higher section yield compared with standard TMA production protocols. Sections from the generated cell TMAs were tested for immunohistochemical staining properties using 20 well-characterized antibodies. Comparison of immunoreactivity in cultured dispersed cells and corresponding cells in tissue samples showed congruent results for all tested antibodies. We conclude that a modified TIVIA technique, including cell samples, provides a valuable tool for high-throughput analysis of protein expression, and that this technique can be used for global approaches to explore the human proteome.
|
|
| 13. |
- Apel, Christina, et al.
(författare)
-
Safe-and-sustainable-by-design: State of the art approaches and lessons learned from value chain perspectives
- 2024
-
Ingår i: Current Opinion in Green and Sustainable Chemistry. - Stockholm : IVL Svenska Miljöinstitutet. - 2452-2236. ; 45, s. 100876-100876
-
Tidskriftsartikel (refereegranskat)abstract
- Safe-and-sustainable-by-design (SSbD) is central in the European Chemicals Strategy for Sustainability, yet a common understanding of what SSbD is in concept and in practice isstill needed. A comparison of current SSbD descriptions and approaches was made and lessons learned were derived from value chain discussions (packaging, textile, construction,automotive, energy materials, electronics, and fragrances value chains) to help provide input on how to implement SSbD in practice.Five important building blocks were identified:design, data, risk and sustainability governance, competencies, and social and corporate strategic needs. Other lessons learned include the identification of the biggest safety andsustainability challenges in a lifecycle-thinking approach towards the development of purpose-driven innovations, and connecting trans-disciplinary experts to the innovation process, already from the early phases. A clear understanding of what SSbD is and how to implement the SSbD framework is needed with clear procedures and incentives to support the industrial sector, especially SMEs.
|
|
| 14. |
|
|
| 15. |
- Apelgren, Britt Marie, 1956, et al.
(författare)
-
Introduction: Language Matters in Higher Education
- 2022
-
Ingår i: Language matters in Higher Education Contexts: Policy and Practice. - Leiden, The Netherlands : Brill. - 2542-8721. - 9789004507920 ; , s. 1-15
-
Bokkapitel (refereegranskat)abstract
- The introductory chapter is designed to set the scene for the different contributing chapters in the book Language Matters in Higher Education Contexts – Policy and Practice. Two overarching themes, ‘internationalisation’ and ‘societal responsibility,’ are identified in relation to language matters in higher education. These themes are both intertwined and nestled together, which sometimes causes significant tensions or fluxing borders. Within these chapters, researchers from different higher education institutions in several European countries bring up emerging and current language issues relating to the ever-increasing urge for universities to be and become international.
|
|
| 16. |
- Apelgren, Britt Marie, 1956, et al.
(författare)
-
Language Matters in Higher Education Contexts: Policy and Practice
- 2022
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- This book highlights that language matters permeate all areas of higher education and that language matters for everyone involved in academic institutions: in policy, in teaching and learning, in administration, in research and in leadership. The chapters in this volume address national, institutional and local levels, and range from legal texts to students’ and teachers’ stories across disciplines. It provides a useful picture for all those who work in the various fields of higher education.
|
|
| 17. |
- Austeng, Dordi, et al.
(författare)
-
Incidence of and risk factors for neonatal morbidity after active perinatal care : extremely preterm infants study in Sweden (EXPRESS)
- 2010
-
Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 99:7, s. 978-992
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: The aim of this study was to determine the incidence of neonatal morbidity in extremely preterm infants and to identify associated risk factors. Methods: Population based study of infants born before 27 gestational weeks and admitted for neonatal intensive care in Sweden during 2004-2007. Results: Of 638 admitted infants, 141 died. Among these, life support was withdrawn in 55 infants because of anticipation of poor long-term outcome. Of 497 surviving infants, 10% developed severe intraventricular haemorrhage (IVH), 5.7% cystic periventricular leucomalacia (cPVL), 41% septicaemia and 5.8% necrotizing enterocolitis (NEC); 61% had patent ductus arteriosus (PDA) and 34% developed retinopathy of prematurity (ROP) stage >= 3. Eighty-five per cent needed mechanical ventilation and 25% developed severe bronchopulmonary dysplasia (BPD). Forty-seven per cent survived to one year of age without any severe IVH, cPVL, severe ROP, severe BPD or NEC. Tocolysis increased and prolonged mechanical ventilation decreased the chances of survival without these morbidities. Maternal smoking and higher gestational duration were associated with lower risk of severe ROP, whereas PDA and poor growth increased this risk. Conclusion: Half of the infants surviving extremely preterm birth suffered from severe neonatal morbidities. Studies on how to reduce these morbidities and on the long-term health of survivors are warranted.
|
|
| 18. |
- Axelsson, Ulrik, et al.
(författare)
-
Kommunernas roll i näringslivets arbete för en hållbar utveckling
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Genom intervjuer med kommunrepresentanter och företagsrepresentanter samt enkäter till representanter inom kommuner, länsstyrelser, självstyrelse- och samverkansorgan samt näringslivet har en kartläggning genomförts av vilka insatser från kommunerna som anses ge bästa effekt när det gäller att stödja näringslivets arbete för en hållbar utveckling. Resultatet av kartläggningen visar att representanterna från kommunerna och näringslivet har en likartad uppfattning om vad som skulle vara bra insatser. Förslagen till insatser kan grupperas i kategorierna: Information och ökad kunskap, nätverk och erfarenhetsutbyte, effektiv tillsyn och handläggning, premiera föregångare, samverkansprojekt och rådgivning. Förslagen på insatser från de intervjuade representanterna i kommunerna, Länsstyrelserna och självstyrelse- och samverkansorganen är mycket lika de förslag som kommer från de intervjuade representanterna från näringslivet. Detta kan tolkas som att kommunerna har en, med näringslivet, samstämmig bild av vilken typ av stöd och åtgärder som skulle passa näringslivet. På många håll fattas dock resurser i form av tid och pengar för att genomföra dessa åtgärder.
|
|
| 19. |
- Axelsson, Ulrik, et al.
(författare)
-
Miljömålsstyrd tillsyn : Miljökvalitetsmål, miljölagstiftning ochföretagens frivilliga miljöarbete i samverkan Huvudrapport
- 2008
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna studie är främst kvalitativ med syftet att bygga upp kunskap om hur miljötillsynen framöver kanutvecklas för att ge största möjliga miljönytta och därmed bidra till att de nationella miljökvalitetsmålenuppnås samtidigt som det inte hämmar det svenska näringslivet utan snarare bidrar till att förbättraderas förutsättningar att bedriva ett kraftfullt miljöarbete. Projektet har huvudsakligen fokuserat på småföretags förutsättningar.Projketet har omfattat flera olika delmoment såsom litteraturstudie, enkät till landets kommuner,intervjuer med kommuner som bedriver stödjande insatser inom ramen för miljötillsynen och intervjuermed små företag kring tillsyn och lagefterlevnad.Litteraturstudien har fokuserat på två frågor; små företags syn på miljölagstiftning och förutsättningarför lagefterlevnad samt småföretagsanpassade tillsynsmetoder. Litteraturen kopplat till dessa bådafrågor har funnits starkt begränsad.I rapporten diskuteras den stödjande och kontrollerande rollen inom miljötillsynen. Vidare presenterasett antal slutsatser vilka är viktiga att beakta för att den framtida miljötillsynen ska få största möjligamiljönytta.Utifrån studiens kunskaper har en workshop genomförts för att diskutera ”Morgondagens miljötillsyn –hur kan den bli effektiv ur ett miljömåls- och näringslivsperspektiv?”.Studie är genomförd av IVL Svenska Miljöinstititet med finansiellt stöd från Miljömålsrådet och Nutek.
|
|
| 20. |
- Axelsson, Ulrik, et al.
(författare)
-
Miljömålsstyrd tillsyn - Miljökvalitetsmål, miljölagstiftning och företagens frivilliga miljöarbete i samverkan. Bilagor
- 2008
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport innehåller bilagorna till huvudrapporten 'Miljömålsstyrd tillsyn - Miljökvalitetsmål, miljölagstiftning och företagens frivilliga miljöarbete i samverkan' (B1765). I denna bilagedel finns utförligare beskrivningar av den litteratur som finns inom ämnet. Dessutom finns information om de goda exempel på småföretagsanpassade tillsynsmetoder som inventerats inom projektet. I bilagedelen finns även den enkät och de intervjufrågor som använts inom projektet
|
|
| 21. |
- Axelsson, Åsa B., 1955, et al.
(författare)
-
European cardiovascular nurses and allied professions’ practical skills in cardiopulmonary resuscitation
- 2009
-
Ingår i: Cardiology. - 0008-6312. - 9783805591430 ; 113:S1
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this study was to test practical skills of cardiopulmonary resuscitation (CPR) in European cardiovascular nurses and allied professions. Methods: Eighty-six delegates at the Spring Meeting on Cardiovascular Nursing in Malmö, Sweden, in 2008, were recruited for this study. Laerdal Resusci Anne SkillReporter manikins connected to a computer with the Laerdal PC SkillReporting System were used. The participants were told to perform CPR according to the “new”guidelines from 2005; 30:2 for three minutes. Results: 88% of the tested participants were nurses and 79% were female. Mean age were 42 years (range 19–63 years). They came from 14 different European countries, though one third was from Sweden. About two thirds had trained CPR within the last year. Seven per cent had no previous CPR training. According to practical skills the average inflations per minute were five (SD+1.5), average inflation volume 992 ml (SD+423) and average flow rate 857 ml/second (SD+401). According assessment of chest compressions the average compression rate was 121 (SD+22.5), average compression per minute 79.5 (SD+14.4), average compression depth 43.8 mm (SD+9.4) and average compression duty cycle 43.8% (SD+5.7). Hand position “too low”was the most common committed error. Conclusion: The practical skill in CPR among the tested delegates was rather satisfying regarding chest compressions. However, there were wide ranges as shown by large standard deviations. Regarding ventilations, too large volumes together with flow rates as high as those performed by many of these delegates may easily lead to gastric inflation during clinical CPR.
|
|
| 22. |
- Barman, Malin, 1983, et al.
(författare)
-
Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE): a prospective birth cohort in northern Sweden
- 2018
-
Ingår i: BMJ Open. - : BMJ. - 2044-6055 .- 2044-6055. ; 8:10
-
Tidskriftsartikel (refereegranskat)abstract
- © Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. INTRODUCTION: Prenatal and neonatal environmental factors, such as nutrition, microbes and toxicants, may affect health throughout life. Many diseases, such as allergy and impaired child development, may be programmed already in utero or during early infancy. Birth cohorts are important tools to study associations between early life exposure and disease risk. Here, we describe the study protocol of the prospective birth cohort, 'Nutritional impact on Immunological maturation during Childhood in relation to the Environment' (NICE). The primary aim of the NICE cohort is to clarify the effect of key environmental exposures-diet, microbes and environmental toxicants-during pregnancy and early childhood, on the maturation of the infant's immune system, including initiation of sensitisation and allergy as well as some secondary outcomes: infant growth, obesity, neurological development and oral health.METHODS AND ANALYSIS: The NICE cohort will recruit about 650 families during mid-pregnancy. The principal inclusion criterion will be planned birth at the Sunderby Hospital in the north of Sweden, during 2015-2018. Questionnaires data and biological samples will be collected at 10 time-points, from pregnancy until the children reach 4 years of age. Samples will be collected primarily from mothers and children, and from fathers. Biological samples include blood, urine, placenta, breast milk, meconium, faeces, saliva and hair. Information regarding allergic heredity, diet, socioeconomic status, lifestyle including smoking, siblings, pet ownership, etc will be collected using questionnaires. Sensitisation to common allergens will be assessed by skin prick testing and allergic disease will be diagnosed by a paediatrician at 1 and 4 years of age. At 4 years of age, the children will also be examined regarding growth, neurobehavioural and neurophysiological status and oral health.ETHICS AND DISSEMINATION: The NICE cohort has been approved by the Regional Ethical Review Board in Umeå, Sweden (2013/18-31M). Results will be disseminated through peer-reviewed journals and communicated on scientific conferences.
|
|
| 23. |
|
|
| 24. |
- Besnard, Francois, 1983, et al.
(författare)
-
A stochastic model for opportunistic maintenance planning of offshore wind farms
- 2011
-
Ingår i: 2011 IEEE PES Trondheim PowerTech: The Power of Technology for a Sustainable Society, POWERTECH 2011; Trondheim; 19 June 2011 through 23 June 2011. - 9781424484195
-
Konferensbidrag (refereegranskat)abstract
- A sound maintenance planning is of crucial importance for wind power farms, and especially for offshore locations. This paper presents a stochastic optimization model for opportunistic service maintenance of offshore wind farms. The model takes advantage of 7 days wind production ensemble forecast and opportunities at corrective maintenance activities in order to perform the service maintenance tasks at the lowest cost. The model is based on a rolling horizon, i.e. the optimization is performed on a daily basis to update the maintenance planning based on the updated production and weather forecasts. An example based on real wind data is used to demonstrate the value of the proposed approach. In this example, it is shown that 32% of the cost for production losses and transportation could be saved. © 2011 IEEE.
|
|
| 25. |
- Besnard, Francois, et al.
(författare)
-
An Optimization Framework for Opportunistic Maintenance of Offshore Wind Power System
- 2009
-
Ingår i: 2009 IEEE BUCHAREST POWERTECH, VOLS 1-5. - NEW YORK : IEEE. - 9781424422340 ; , s. 2970-2976
-
Konferensbidrag (refereegranskat)abstract
- A sound maintenance planning is of crucial importance for wind power farms, and especially for offshore locations. There is a large potential in cost savings by maintenance optimization to make the projects more cost-efficient. This paper presents an opportunistic maintenance optimization model for offshore wind power system. The model takes advantage of wind forecasts and corrective maintenance activities in order to perform preventive maintenance tasks at low costs. The approach is illustrated with an example to demonstrate the value of the optimization. In this example 43% of the cost to perform preventive maintenance could be saved using the proposed method.
|
|
| 26. |
- Bryhn, Andreas, et al.
(författare)
-
Fisk- och skaldjursbestånd i hav och sötvatten 2019 : Resursöversikt
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fisken i havet är en resurs som rör sig fritt över nationella gränser. EU har därför en gemensam fiskeripolitik (GFP). Många arter som är viktiga för Sverige regleras inte i GFP och förvaltas därför nationellt.Denna rapport syftar till att:beskriva utvecklingen av fiskeripolitikenförklara den nuvarande politikens mål och regelverk och dess relation till mål och regler på miljöområdetförklara politikens nationella genomförande och det nationella handlingsutrymmetexemplifiera hur Havs- och vattenmyndigheten arbetat med att reglera fisket.
|
|
| 27. |
- Bryhn, Andreas, et al.
(författare)
-
Fisk- och skaldjursbestånd i hav och sötvatten 2020 : Resursöversikt
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I rapporten kan du ta del av bedömningen som görs av situationen för bestånd som regleras inom ramen för EU:s gemensamma fiskeripolitik (GFP). Bedömningarna baseras på det forskningssamarbete och den rådgivning som sker inom det Internationella Havsforskningsrådet (ICES). Totalt redovisas underlag och råd för 48 fisk- och skaldjursarter.De bestånd som förvaltas nationellt baseras på de biologiska underlagen, och rådgivningen i huvudsak på den forskning och övervakning samt analys som bedrivs av Institutionen för akvatiska resurser vid Sveriges lantbruksuniversitet (SLU Aqua) samt yrkesfiskets rapportering.
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
- Ehrstedt, Christoffer, et al.
(författare)
-
Cognition, health-related quality of life, and mood in children and young adults diagnosed with a glioneuronal tumor in childhood
- 2018
-
Ingår i: Epilepsy & Behavior. - : Elsevier BV. - 1525-5050 .- 1525-5069. ; 83, s. 59-66
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: The aim of this study was to investigate long-term cognitive outcome, health-related quality of life (HRQoL), and psychiatric symptoms in children and young adults diagnosed with a glioneuronal tumor in childhood.Methods: Twenty-eight children and adolescents (0-17.99 years) with a minimum postoperative follow-up time of five years were eligible for the study; four persons declined participation. A cross-sectional long-term follow-up evaluation was performed using the following study measures: Wechsler Intelligence Scale for Children (WISC-IV) or Wechsler Adult Intelligence Scale (WAIS-IV), Reys Complex Figure Test (RCFT), Short Form 36 version 2 (SF-36v2), Short Form 10 (SF-10), Quality of Life in Epilepsy 31 (QOLIE-31), Hospital Anxiety Depression Scale (HADS) or Beck Youth Inventory Scales (BYI), and Rosenberg Self-Esteem Scale. Historical WISC-III and RCFT data were used to compare cognitive longitudinal data.Results: Mean follow-up time after surgery was 12.1 years. Sixty-three percent (15/24) were seizure-free. Despite a successive postoperative gain in cognitive function, a significant reduction relative to norms was seen in the seizure-free group with respect to perceptual reasoning index (PRI), working memory index (WMI), and full-scale intelligence quotient (FSIQ). Seizure freedom resulted in acceptable HRQoL. Thirty-two percent and 16% exceeded the threshold level of possible anxiety and depression, respectively, despite seizure freedom.Conclusion: Although lower than in corresponding reference groups, cognitive outcome and HRQoL are good provided that seizure freedom or at least a low seizure severity can be achieved. There is a risk of elevated levels of psychiatric symptoms. Long-term clinical follow-up is advisable.
|
|
| 31. |
- Ehrstedt, Christoffer
(författare)
-
Glioneuronal tumours in childhood : Clinical picture, long-term outcome and possible new treatments
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Glioneuronal tumours are a subgroup of low-grade tumours of the central nervous system (CNS), often causing epilepsy. Overall survival is excellent, but data regarding long-term seizure outcome and late effects are scarce.Aims: The overall aim was to gather data about pre- and postsurgical factors of importance and long-term outcomes to improve standards of care. Another aim was to explore the expression of somatostatin receptor (SSTR) subtypes and mTOR pathway markers.Methods: This thesis, based on four population-based studies with both retrospective and cross-sectional parts, was performed through a long-term follow-up of a Swedish cohort of children with glioneuronal tumours in the Uppsala-Örebro health region. Patients were identified from the National Brain Tumour Registry and the National Epilepsy Surgery Registry. Various methods were used: reviews of hospital medical records, patient interviews, health-related quality of life (HRQoL) assessments with generic (Short Form 36version2) and disease specific (Quality of Life in Epilepsy-31) questionnaires, neuropsychological evaluations with Wechsler Intelligence Scale for Children-IV or Wechsler Adult Intelligence Test-IV and Reys Complex Figure Test and evaluation for possible depression with Hospital Anxiety Depression Scale. Immunohistochemical analyses for SSTR subtypes 1, 2a, 3 and 5 and mTOR pathway components ezrin-radixin-moesin and pS6 were performed on tumour specimens.Results: Glioneuronal tumours seem to be more frequent than previously reported, accounting for 13.5% of all childhood CNS tumours. They often cause medically refractory epilepsy resulting in cognitive impairment. Neurosurgery was often delayed; mean time from symptom debut to lesionectomy was 4.6 years. Long-term seizure freedom was achieved in 84% of patients who had a gross total resection (GTR) and is important for long-term cognitive restitution, HRQoL, educational and vocational outcomes. SSTR2a and SSTR3 expression was a frequent finding in glioneuronal tumours. Signs of mTOR pathway activation were abundant in ganglioglioma.Conclusions: A safe GTR should be striven for and considered a first-line treatment. Long-term clinical follow-up should be offered to all patients and for those with an inoperable tumour/tumour remnant causing tumour growth and/or medically refractory epilepsy, somatostatin analogues and/or mTOR inhibitors might represent a therapeutic alternative worth exploring further.
|
|
| 32. |
- Ehrstedt, Christoffer, et al.
(författare)
-
Weekly vinblastine is a therapeutic option in recurrent/refractory pediatric low-grade gliomas
- 2012
-
Ingår i: Neuro-Oncology. - : Oxford University Press (OUP). - 1522-8517 .- 1523-5866. ; 14:suppl 1, s. i70-i70
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: In a majority of cases efficient treatment of low-grade gliomas in the pediatric population is achieved by surgery, sometimes accompanied by chemotherapy according to the LGG SIOP 2003 protocol. However, some cases of LGG is refractory, treatment options in these cases often consists of LGG SIOP 2003 relapse protocol or radiotherapy. Vinblastine can be used as a secondline chemotherapy.METHODS: Four patients with refractory low grade gliomas were given vinblastine intravenously. These patients had previously failed chemotherapy and/or radiation for unresectable low-grade glioma. Tumor location has differed, 1 brainstem, 1 optic pathway, 1 thalamus, 1 cerebellar. Three of the patients were given vinblastine at a dose of 6mg/m2 weekly, the fourth patient received a 50% dose reduction because of intolerable side-effects. The treatment was given for at least 12 months in three of the cases.RESULTS: There have been significant reduction of tumor size in the 3 patients who have received vinblastine for at least 12 months. Response to treatment has been followed at three months interval with MRI. None of the patients have been forced to discontinue the treatment because of intolerable side-effects. The fourth patient has been treated for three months and follow-up with MRI indicates a slight reduction of tumor size.CONCLUSION: Vinblastine should be considered as a secondline chemotherapy in refractory low grade gliomas. Extended administration (>12 months) seems to be tolerated well. If untolerable side effects dose reduction should be tried.
|
|
| 33. |
- Enarsson, Karin, 1975, et al.
(författare)
-
Differential mechanisms for T lymphocyte recruitment in normal and neoplastic human gastric mucosa
- 2006
-
Ingår i: Clin Immunol. - : Elsevier BV. ; 118:1, s. 24-34
-
Forskningsöversikt (refereegranskat)abstract
- Worldwide, gastric adenocarcinoma (GC) is the second most common cause of death from malignant disease. The reason why immune responses are unable to clear the tumour is not fully understood, although aberrant lymphocyte recruitment to the tumour site might be one factor. Therefore, we investigated the homing phenotype of mucosal T lymphocytes in GC, compared to tumour-free mucosa. We could detect significantly decreased frequencies of mucosal homing alpha4beta7+ T cells in the tumour tissues and increased frequencies of L-selectin+ T cells. This was probably due to the correlated decrease in MAdCAM-1 positive and increase in PNAd positive blood vessels in the tumour mucosa. There were also fewer CXCR3+ T lymphocytes in the tumour tissue. These findings provide evidence that endothelial cells within tumours arising at mucosal sites do not support extravasation of typical mucosa-infiltrating T cells. This may be of major relevance for future immunotherapeutic strategies for treatment of GC.
|
|
| 34. |
|
|
| 35. |
- Eriksson, Ann-Marie, 1964, et al.
(författare)
-
Epilogue: The Intricate Weave of Language Policy and Practice
- 2022
-
Ingår i: Language Matters in Higher Education Contexts: Policy and Practice. - Leiden, The Netherlands : Brill. - 2542-8721. - 9789004507920 ; , s. 169-176
-
Bokkapitel (refereegranskat)abstract
- By weaving together the broad range of empirical and conceptual examples of research from local academic European settings presented in the book Language Matters in Higher Education Contexts: Policy and Practice, this chapter reflects on how European higher education is permeated by, and entangled with, language matters, and how such matters are tightly interwoven with, for example, internationalisation and societal responsibility in higher education contexts.
|
|
| 36. |
- Eriksson Barman, Sandra, 1985, et al.
(författare)
-
Modeling and solving vehicle routing problems with many available vehicle types
- 2015
-
Ingår i: Springer Proceedings in Mathematics & Statistics. - Cham : Springer International Publishing. - 2194-1009 .- 2194-1017. - 9783319185668
-
Konferensbidrag (refereegranskat)abstract
- Vehicle routing problems (VRP) involving the selection of vehicles from a large set of vehicle types are hitherto not well-studied in the literature. Such problems arise at Volvo Group Trucks Technology, who faces an immense set of possible vehicle configurations, of which an optimal set needs to be chosen for each specific combination of transport missions. Another property of real-world VRP’s that is often neglected in the literature is that the fuel resources required to drive a vehicle along a route is highly dependent on the actual load of the vehicle. We define the fleet size and mix VRP with many available vehicle types, called many-FSMVRP, and suggest an extended set-partitioning model of this computationally demanding combinatorial optimization problem. To solve the extended model, we have developed a method based on Benders’ decomposition, the subproblems of which are solved using column generation, and the column generation subproblems being solved using dynamic programming; the method is implemented with a so-called projection-of-routes procedure. The resulting method is compared with a column generation approach for the standard set-partitioning model. Our method for the extended model performs on par with column generation applied to the standard model for instances such that the two models are equivalent. In addition, the utility of the extended model for instances with very many available vehicle types is demonstrated. Our method is also shown to efficiently handle cases in which the costs are dependent on the load of the vehicle. Computational tests on a set of extended standard test instances show that our method, based on Benders’ algorithm, is able to determine combinations of vehicles and routes that are optimal to a relaxation (w.r.t. the route decision variables) of the extended model. Our exact implementation of Benders’ algorithm appears, however, too slow when the number of customers grows. To improve its performance, we suggest that relaxed versions of the column generation subproblems are solved, and that the set-partitioning model is replaced by a set-covering model.
|
|
| 37. |
- Fotedar, Sunney, 1989, et al.
(författare)
-
A criterion space decomposition approach to generalized tri-objective tactical resource allocation
- 2023
-
Ingår i: Computational Management Science. - : Springer Science and Business Media LLC. - 1619-697X .- 1619-6988. ; 20:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present a tri-objective mixed-integer linear programming model of the tactical resource allocation problem with inventories, called the generalized tactical resource allocation problem (GTRAP). We propose a specialized criterion space decomposition strategy, in which the projected two-dimensional criterion space is partitioned and the corresponding sub-problems are solved in parallel by application of the quadrant shrinking method (QSM) (Boland in Eur J Oper Res 260(3):873–885, 2017) for identifying non-dominated points. To obtain an efficient implementation of the parallel variant of the QSM we suggest some modifications to reduce redundancies. Our approach is tailored for the GTRAP and is shown to have superior computational performance as compared to using the QSM without parallelization when applied to industrial instances.
|
|
| 38. |
- Fotedar, Sunney, 1989, et al.
(författare)
-
A decision-making tool to identify routings for an efficient utilization of machining resources: the decision makers’ perspective
- 2020
-
Ingår i: PLANs forsknings-och tillämpningskonferens.
-
Konferensbidrag (refereegranskat)abstract
- In the aerospace industry, efficient management of machining capacity is crucial to meet the required service levels to customers (which includes, measures of quality and lead-times ) and keeps the tied-up working capital in check. The proposed decision-making tool, described in this paper, aims to combine information and knowledge of manufacturing and logistics experts in a company to improve flow of materials through the factory. The material flow situation is different for a large aerospace tier-1 supplier as opposed to flow-based manufacturing company; when there is no pandemic or natural calamity, having relatively stable demand due to long-term contract is common, but there exists short-term demand variability. There is a complex flow of products at GKN Aerospace, as the products share machining resources, thus, resulting in uneven loads at machines and sometimes excess loading at certain machines. This along with short-term demand variability results in long queues in-front of machines which contributes with the biggest share of the total lead-time. Thus, long waiting times at one/many machine/s is common and may lead to bottlenecks in many places in the production pipeline. So, there is potential benefit in having rerouting-flexibility for products which can help in reducing queuing. However, qualifying a product for a new machine is time-consuming activity, and thus, should be done few years in advance. We propose a mathematical model aimed at improving some of these deficiencies of commonly used methods by facilitating balanced resource loading levels, i.e. to provide more degrees of freedom to the planner to absorb demand variations. The output provided by the model includes production routings in each time period (quarter) for the next 4–5 years; new qualifications to be done by technical staff for allocation of part types/products to machines which are not yet qualified/used for a given product. We keep the resource loading levels that are above a given threshold as low as possible and reduce the time/money spent for qualifying new allocations.
|
|
| 39. |
- Fotedar, Sunney, et al.
(författare)
-
Bi-objective optimization of the tactical allocation of job types to machines: mathematical modeling, theoretical analysis, and numerical tests
- 2022
-
Ingår i: International Transactions in Operational Research. - : Wiley. - 0969-6016 .- 1475-3995.
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce a tactical resource allocation model for a large aerospace engine system manufacturer aimed at long-term production planning. Our model identifies the routings a product takes through the factory, and which machines should be qualified for a balanced resource loading, to reduce product lead times. We prove some important mathematical properties of the model that are used to develop a heuristic providing a good initial feasible solution. We propose a tailored approach for our class of problems combining two well-known criterion space search algorithms, the bi-directional epsilon-constraint method and the augmented weighted Tchebycheff method. A computational investigation comparing solution times for several solution methods is presented for 60 numerical instances.
|
|
| 40. |
- Fotedar, Sunney, 1989, et al.
(författare)
-
Mathematical optimization of the tactical allocation of machining resources for an efficient capacity utilization in aerospace component manufacturing
- 2019
-
Ingår i: Proceedings of the 10th Aerospace Technology Congress. - : Linköping University Electronic Press. - 1650-3686 .- 1650-3740. - 9789175190068 ; , s. 183-188
-
Konferensbidrag (refereegranskat)abstract
- In the aerospace industry, with low volumes and many products, there is a critical need to efficiently use available manufacturing resources. Currently, at GKN Aerospace, resource allocation decisions that in many cases will last for several years are to some extent made with a short-term focus so as to minimize machining time, which results in a too high load on the most capable machines, and too low load on the less capable ones. This creates an imbalance in capacity utilization that leads to unnecessary queuing at some machines, resulting in long lead times and in an increase in tied-up capital. Tactical resource allocation on the medium to long-range planning horizon (six months to several years) aims to address this issue by allocating resources to meet the predicted future demand as effectively as possible, in order to ensure long range profitability. Our intent is to use mathematical optimization to find the best possible allocations.
|
|
| 41. |
- Fotedar, Sunney, et al.
(författare)
-
Robust optimization of a bi-objective tactical resource allocation problem with uncertain qualification costs
- 2022
-
Ingår i: Autonomous Agents and Multi-Agent Systems. - : Springer Science and Business Media LLC. - 1387-2532 .- 1573-7454. ; 36:2
-
Tidskriftsartikel (refereegranskat)abstract
- In the presence of uncertainties in the parameters of a mathematical model, optimal solutions using nominal or expected parameter values can be misleading. In practice, robust solutions to an optimization problem are desired. Although robustness is a key research topic within single-objective optimization, little attention is received within multi-objective optimization, i.e. robust multi-objective optimization.This work builds on recent work within robust multi-objective optimization and presents a new robust efficiency concept for bi-objective optimization problems with one uncertain objective. Our proposed concept and algorithmic contribution are tested on a real-world multi-item capacitated resource planning problem, appearing at a large aerospace company manufacturing high precision engine parts. Our algorithm finds all the robust efficient solutions required by the decision-makers in significantly less time than the approach of Kuhn et al. (Eur J Oper Res 252(2):418-431, 2016) on 28 of the 30 industrial instances.
|
|
| 42. |
- Fröidh, Oskar, et al.
(författare)
-
Färdplan för ökad forskning och innovation inom underhåll av järnvägsfordon
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- KTH, Chalmers och Handelshögskolan vid Göteborgs universitet har av Trafikverket fått uppdraget att ta fram ett dokument om forskningen inom underhåll av järnvägsfordon. Det är föreliggande färdplan som ingår i Trafikverkets satsning Morgondagens depåer. Färdplanen ska ligga till grund för en strategi och förslag på utveckling för kostnadseffektivt fordonsunderhåll med de förutsättningar som råder i Sverige, med avreglering och många aktörer i branschen likväl som speciella klimatförutsättningar. Trafikverket har uppmärksammat att frågor om depåer och fordonsunderhåll inte alltid hanteras på ett bra sätt för att utveckla järnvägssystemet. Tidigare hade Banverket ett sektorsansvar men det avskaffades i och med att Trafikverket bildades. Det behövs dock ett övergripande systemansvar och incitament för att leda processen framåt mot en stabil utveckling genom forskning, utveckling och innovation i den fortsatta omreglering som sker av den svenska järnvägssektorn. Hur kan en effektiv samverkan mellan universitet, näringsliv och offentlig sektor utformas för att bidra till en säker och pålitlig tågtrafik i Sverige? En litteraturgenomgång har genomförts för att visa var den internationella forskningsfronten står. Det tycks dock som att det samlade greppet inom underhåll av järnvägsfordon inte är ett genomarbetat forskningsområde, utan det kan bli ett svenskt ”pionjärområde” där universitet, högskolor och institut i samarbete med branschen kan skapa forskningsresultat och kunskapsutveckling. Denna färdplan föreslår ett antal olika områden som skulle behöva ökad forskning för större kunskap och kompetens. Var ska depåer för person- respektive godsfordon mest effektivt lokaliseras, centralt eller perifert i jämförelse med trafiksystemet och respektive omlopp? Hur ska de utformas mest effektivt med tanke på fordonstyper, reservdelar och personalutnyttjande? Hur ska infrastrukturen till och internt i depåerna utformas för effektivt arbete? Detta ska ske i en avreglerad järnvägssektor med olika operatörer, vagnägare, depåägare samt underhållsleverantörer på olika långa kontrakt. Hur ska detta organiseras på ett stabilt sätt med långsiktig ekonomisk bärkraft för samtliga parter? Arbetet går att dela upp i avhjälpande och förebyggande underhåll; i depå eller mobilt, med säkerhets-, drifts- eller komfortrelaterat underhåll. På vilka olika sätt går det att utvärdera samt utveckla modeller för att prognostisera behovet av underhåll enligt ovan nämnda variabler? Målet är att ta fram vetenskapliga metoder för att effektivisera fordonsunderhåll för järnvägstrafiken på ett optimalt sätt. I färdplanen rekommenderas en strategi för fordonsunderhåll: Trafikverket ska verka för att efterfrågad funktion i det svenska järnvägssystemet uppnås, inkluderande kostnadseffektivt underhåll av både infrastruktur och fordon. Hög driftsäkerhet är attraktivt för resenärer och godskunder och har ett värde och motiverar ett samhällsekonomiskt synsätt på underhåll av järnvägsfordon. Tillståndsövervakning och relaterad prediktering ges en viktigare roll för förebyggande underhåll. Öka synergin mellan infrastruktur- och fordonsbaserad tillståndsövervakning, inte minst av den dynamiska samverkan mellan infrastruktur och fordon. Utred hur ”intelligensen” hos infrastruktur och fordon bäst fördelas och utvecklas för ett mera kostnadseffektivt underhåll av järnvägssystemet. Detta innefattar att man vet vad man skall mäta och att uppmätta storheter kan länkas till framtida nedbrytning av fordon och infrastruktur. Utred flödet och ”flaskhalsar” i dagens system av fordonsunderhåll (kritiska aspekter). Utveckla distinktionen av säkerhetsnödvändigt underhåll och komfortrelaterat underhåll. Verka för tydliga och rimliga ”spelregler” för aktörer inom fordonsunderhåll. Förbättra nätverket bland dessa aktörer, inte minst kring tekniska frågor. Skapa ytterligare incitament för effektivt fordonsunderhåll genom att se över kostnader och intäkter i intressentkedjan mellan de primära kunderna och de som kan åtgärda problemen. Lyft fram goda exempel (best practice) på väl fungerande fordonsunderhåll. Låt universitet och högskolor få en viktig och neutral roll i den kunskapsbaserade utvecklingen. Detta bör ske genom att skapa ett forsknings- utvecklings- och demonstrations (FUD)-program inom området underhåll för järnvägsfordon. I denna färdplan föreslås även ett antal olika forskningsprojekt och -områden som skulle kunna utvecklas i ett sammanhållet forskningsprogram.
|
|
| 43. |
- Fröidh, Oskar, et al.
(författare)
-
Färdplan för ökad forskning och innovation inom underhåll av järnvägsfordon
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- KTH, Chalmers och Handelshögskolan vid Göteborgs universitet har av Trafikverket fått uppdraget att ta fram ett dokument om forskningen inom underhåll av järnvägsfordon. Det är föreliggande färdplan som ingår i Trafikverkets satsning Morgondagens depåer. Färdplanen ska ligga till grund för en strategi och förslag på utveckling för kostnadseffektivt fordonsunderhåll med de förutsättningar som råder i Sverige, med avreglering och många aktörer i branschen likväl som speciella klimatförutsättningar.Trafikverket har uppmärksammat att frågor om depåer och fordonsunderhåll inte alltid hanteras på ett bra sätt för att utveckla järnvägssystemet. Tidigare hade Banverket ett sektorsansvar men det avskaffades i och med att Trafikverket bildades. Det behövs dock ett övergripande systemansvar och incitament för att leda processen framåt mot en stabil utveckling genom forskning, utveckling och innovation i den fortsatta omreglering som sker av den svenska järnvägssektorn. Hur kan en effektiv samverkan mellan universitet, näringsliv och offentlig sektor utformas för att bidra till en säker och pålitlig tågtrafik i Sverige?En litteraturgenomgång har genomförts för att visa var den internationella forskningsfronten står. Det tycks dock som att det samlade greppet inom underhåll av järnvägsfordon inte är ett genomarbetat forskningsområde, utan det kan bli ett svenskt ”pionjärområde” där universitet, högskolor och institut i samarbete med branschen kan skapa forskningsresultat och kunskapsutveckling.Denna färdplan föreslår ett antal olika områden som skulle behöva ökad forskning för större kunskap och kompetens. Var ska depåer för person- respektive godsfordon mest effektivt lokaliseras, centralt eller perifert i jämförelse med trafiksystemet och respektive omlopp? Hur ska de utformas mest effektivt med tanke på fordonstyper, reservdelar och personalutnyttjande? Hur ska infrastrukturen till och internt i depåerna utformas för effektivt arbete? Detta ska ske i en avreglerad järnvägssektor med olika operatörer, vagnägare, depåägare samt underhållsleverantörer på olika långa kontrakt. Hur ska detta organiseras på ett stabilt sätt med långsiktig ekonomisk bärkraft för samtliga parter? Arbetet går att dela upp i avhjälpande och förebyggande underhåll; i depå eller mobilt, med säkerhets-, drifts- eller komfortrelaterat underhåll. På vilka olika sätt går det att utvärdera samt utveckla modeller för att prognostisera behovet av underhåll enligt ovan nämnda variabler? Målet är att ta fram vetenskapliga metoder för att effektivisera fordonsunderhåll för järnvägstrafiken på ett optimalt sätt.I färdplanen rekommenderas en strategi för fordonsunderhåll:Trafikverket ska verka för att efterfrågad funktion i det svenska järnvägssystemet uppnås, inkluderande kostnadseffektivt underhåll av både infrastruktur och fordon.Hög driftsäkerhet är attraktivt för resenärer och godskunder och har ett värde och motiverar ett samhällsekonomiskt synsätt på underhåll av järnvägsfordon.Tillståndsövervakning och relaterad prediktering ges en viktigare roll för förebyggande underhåll.Öka synergin mellan infrastruktur- och fordonsbaserad tillståndsövervakning, inte minst av den dynamiska samverkan mellan infrastruktur och fordon.Utred hur ”intelligensen” hos infrastruktur och fordon bäst fördelas och utvecklas för ett mera kostnadseffektivt underhåll av järnvägssystemet. Detta innefattar att man vet vad man skall mäta och att uppmätta storheter kan länkas till framtida nedbrytning av fordon och infrastruktur.Utred flödet och ”flaskhalsar” i dagens system av fordonsunderhåll (kritiska aspekter).Utveckla distinktionen av säkerhetsnödvändigt underhåll och komfortrelaterat underhåll.Verka för tydliga och rimliga ”spelregler” för aktörer inom fordonsunderhåll.Förbättra nätverket bland dessa aktörer, inte minst kring tekniska frågor.Skapa ytterligare incitament för effektivt fordonsunderhåll genom att se över kostnader och intäkter i intressentkedjan mellan de primära kunderna och de som kan åtgärda problemen.Lyft fram goda exempel (best practice) på väl fungerande fordonsunderhåll.Låt universitet och högskolor få en viktig och neutral roll i den kunskapsbaserade utvecklingen.Detta bör ske genom att skapa ett forsknings- utvecklings- och demonstrations (FUD)-program inom området underhåll för järnvägsfordon. I denna färdplan föreslås även ett antal olika forskningsprojekt och -områden som skulle kunna utvecklas i ett sammanhållet forskningsprogram.
|
|
| 44. |
- Gad, Helge, et al.
(författare)
-
MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
-
Tidskriftsartikel (refereegranskat)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
|
|
| 45. |
- Georgian, Samuel E., et al.
(författare)
-
Biogeographic variability in the physiological response of the cold-water coral Lophelia pertusa to ocean acidification
- 2016
-
Ingår i: Marine Ecology. - : Wiley. - 0173-9565 .- 1439-0485. ; 37:6, s. 1345-1359
-
Tidskriftsartikel (refereegranskat)abstract
- While ocean acidification is a global issue, the severity of ecosystem effects is likely to vary considerably at regional scales. The lack of understanding of how biogeographically separated populations will respond to acidification hampers our ability to predict the future of vital ecosystems. Cold-water corals are important drivers of biodiversity in ocean basins across the world and are considered one of the most vulnerable ecosystems to ocean acidification. We tested the short-term physiological response of the cold-water coral Lophelia pertusa to three pH treatments (pH = 7.9, 7.75 and 7.6) for Gulf of Mexico (USA) and Tisler Reef (Norway) populations, and found that reductions in seawater pH elicited contrasting responses. Gulf of Mexico corals exhibited reductions in net calcification, respiration and prey capture rates with decreasing pH. In contrast, Tisler Reef corals showed only slight reductions in net calcification rates under decreased pH conditions while significantly elevating respiration and capture rates. These differences are likely the result of environmental differences (depth, pH, food supply) between the two regions, invoking the potential for local adaptation or acclimatization to alter their response to global change. However, it is also possible that variations in the methodology used in the experiments contributed to the observed differences. Regardless, these results provide insights into the resilience of L. pertusa to ocean acidification as well as the potential influence of regional differences on the viability of species in future oceans.
|
|
| 46. |
- Granfeldt, Caroline, 1991, et al.
(författare)
-
A Lagrangian relaxation approach to an electricity system investment model with a high temporal resolution
- 2023
-
Ingår i: OR Spectrum. - 1436-6304 .- 0171-6468. ; 45:4, s. 1263-1294
-
Tidskriftsartikel (refereegranskat)abstract
- The global production of electricity contributes significantly to the release of carbon dioxide emissions. Therefore, a transformation of the electricity system is of vital importance in order to restrict global warming. This paper proposes a modelling methodology for electricity systems with a large share of variable renewable electricity generation, such as wind and solar power. The model developed addresses the capacity expansion problem, i.e. identifying optimal long-term investments in the electricity system. Optimal investments are defined by minimum investment and production costs under electricity production constraints—having different spatial resolutions and technical detail—while meeting the electricity demand. Our model is able to capture a range of strategies to manage variations and to facilitate the integration of variable renewable electricity; it is very large due to the high temporal resolution required to capture the variations in wind and solar power production and the chronological time representation needed to model energy storage. Moreover, the model can be further extended—making it even larger—to capture a large geographical scope, accounting for the trade of electricity between regions with different conditions for wind and solar power. Models of this nature thus typically need to be solved using some decomposition method to reduce solution times. In this paper, we develop a decomposition method using so-called variable splitting and Lagrangian relaxation; the dual problem is solved by a deflected subgradient algorithm. Our decomposition regards the temporal resolution by defining 2-week periods throughout the year and relaxing the overlapping constraints. The method is tested and evaluated on some real-world cases containing regions with different energy mixes and conditions for wind power. Numerical results show shorter computation times as compared with the non-decomposed model, and capacity investment options similar to the optimal solution provided by the latter model.
|
|
| 47. |
- Gustavsson, Emil, 1987, et al.
(författare)
-
Preventive maintenance scheduling of multi-component systems with deterioration costs
- 2012
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the preventive maintenance scheduling problem with interval costs (PMSPIC), which is to schedule preventive maintenance of components of a system over a finite discretized time horizon, given a common set-up cost and component costs dependent on the lengths of the maintenance intervals. We present a 0-1 integer linear programming (0-1 ILP) model for the PMSPIC which was originally presented by Joneja (1990) to model the joint replenishment problem. We show that most of the integrality constraints can be relaxed and that the linear inequality constraints define facets of the convex hull of the feasible set. We present three applications demonstrating that the PMSPIC can be used to model several types of maintenance problems with deterioration costs. The first considers rail grinding. If the interval between the grinding occasions increases, then the sizes of the rail cracks increase, which implies that more grinding passes must be performed, generating a higher maintenance cost. We presume a deterministic model for crack growth and optimize the scheduling of the rail grinding on a set of track sections. Our second application concerns two approaches for the scheduling of component replacements in aircraft engines. In the first approach a bi-objective problem, simultaneously minimizing the cost for the scheduled preventive maintenance and the probability of unexpected stops, is formulated. The second approach considers the minimization of the sum of costs of preventive and expected corrective maintenance, without rescheduling. We also demonstrate that if rescheduling is allowed, then the 0-1 ILP model can be used as a policy by re-optimizing the schedule at a component failure, thus utilizing the opportunity for preventive maintenance. We evaluate the use of such a strategy in a simulation of the engine. The third approach considers components’ replacement in wind mills in a wind farm, extending the PMSPIC to consider several systems with a joint set-up cost. As for the aircraft engine application, we use the 0-1 ILP model as a policy for deciding upon replacement decisions allowing for rescheduling, and evaluate it by simulating the joint system. In each of the three applications, the use of the 0-1 ILP model is compared with age or constantinterval policies, resulting in a reduction of maintenance costs by up to 15% compared with the respective best simple policy.
|
|
| 48. |
- Gustavsson, Emil, 1987, et al.
(författare)
-
Preventive maintenance scheduling of multi-component systems with interval costs
- 2014
-
Ingår i: Computers & industrial engineering. - : Elsevier BV. - 0360-8352. ; 76, s. 390-400
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce the preventive maintenance scheduling problem with interval costs (PMSPIC), which is to schedule preventive maintenance (PM) of the components of a system over a finite and discretized time horizon, given a common set-up cost and component costs dependent on the lengths of the maintenance intervals. We present a 0–1 integer linear programming (0–1 ILP) model for the PMSPIC; the model is identical to that presented by Joneja (1990) for the joint replenishment problem within inventory management. We study this model from a polyhedral and exact solutions’ point of view, as opposed to previously studied heuristics (e.g. Boctor, Laporte, & Renaud, 2004; Federgruen & Tzur, 1994; Levi, Roundy, & Shmoys, 2006; Joneja, 1990).We show that most of the integrality constraints can be relaxed and that the linear inequality constraints define facets of the convex hull of the feasible set. We further relate the PMSPIC to the opportunistic replacement problem, for which detailed polyhedral studies were performed by Almgren et al. (2012a). The PMSPIC can be used as a building block to model several types of maintenance planning problems possessing deterioration costs. By a careful modeling of these costs, a polyhedrally sound 0–1 ILP model is used to find optimal solutions to realistic-sized multi-component maintenance planning problems. The PMSPIC is thus easily extended by side constraints or to multiple tiers, which is demonstrated through three applications; these are chosen to span several levels of unmodeled randomness requiring fundamentally different maintenance policies, which are all handled by variations of our basic model. Our first application considers rail grinding. Rail cracks increase with increasing intervals between grinding occasions, implying that more grinding passes must be performed—thus generating higher costs. We optimize the grinding schedule for a set of track sections presuming a deterministic model for crack growth; hence, no corrective maintenance (CM) will occur between the grinding occasions scheduled. The second application concerns two approaches for scheduling component replacements in aircraft engines. The first approach is bi-objective, simultaneously minimizing the cost for the scheduled PM and the probability of unexpected stops. In the second approach the sum of costs for PM and expected CM—without rescheduling—is minimized. When rescheduling is allowed, the 0–1 ILP model is used as a policy by re-optimizing the schedule at a component failure, which then constitutes an opportunity for PM. The policy manages the trade-off between costs for PM and unplanned CM and is evaluated in a simulation of the engine. The third application considers components’ replacement in wind mills in a wind farm, extending the PMSPIC to comprise multiple tiers with joint set-up costs. Due to the large number of components unexpected stops occur frequently, thus calling for a dynamic rescheduling, which is evaluated through a simulation of the system. In each of the three applications, the use of the 0-1 ILP model is compared with age or constant-interval policies; the maintenance costs are reduced by up to 16% as compared with the respective best simple policy. The results are strongest for the first two applications, possessing low levels of unmodeled randomness.
|
|
| 49. |
- Gustavsson, Emil, 1987, et al.
(författare)
-
Primal convergence from dual subgradient methods for convex optimization
- 2012
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- When solving a convex optimization problem through a Lagrangian dual reformulation subgradient optimization methods are favourably utilized, since they often find near-optimal dual solutions quickly. However, an optimal primal solution is generally not obtained directly through such a subgradient approach. We construct a sequence of convex combinations of primal subproblem solutions, a so called ergodic sequence, which is shown to converge to an optimal primal solution when the convexity weights are appropriately chosen. We generalize previous convergence results from linear to convex optimization and present a new set of rules for constructing the convexity weights that define the ergodic sequence of primal solutions. In contrast to previously proposed rules, they exploit more information from later subproblem solutions than from earlier ones. We evaluate the proposed rules on a set of nonlinear multicommodity flow problems and demonstrate that they clearly outperform the ones previously proposed.
|
|
| 50. |
- Gustavsson, Emil, 1987, et al.
(författare)
-
Primal convergence from dual subgradient methods for convex optimization
- 2015
-
Ingår i: Mathematical Programming. - : Springer Science and Business Media LLC. - 0025-5610 .- 1436-4646. ; 150:2, s. 365-390
-
Tidskriftsartikel (refereegranskat)abstract
- When solving a convex optimization problem through a Lagrangian dual reformulation subgradient optimization methods are favorably utilized, since they often find near-optimal dual solutions quickly. However, an optimal primal solution is generally not obtained directly through such a subgradient approach unless the Lagrangian dual function is differentiable at an optimal solution. We construct a sequence of convex combinations of primal subproblem solutions, a so called ergodic sequence, which is shown to converge to an optimal primal solution when the convexity weights are appropriately chosen. We generalize previous convergence results from linear to convex optimization and present a new set of rules for constructing the convexity weights that define the ergodic sequence of primal solutions. In contrast to previously proposed rules, they exploit more information from later subproblem solutions than from earlier ones. We evaluate the proposed rules on a set of nonlinear multicommodity flow problems and demonstrate that they clearly outperform the ones previously proposed.
|
|
