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  • 1192001.
    Yakob, Nancy
    Södertörn University College, Lärarutbildningen.
    Religionskunskapsundervisning ur elevperspektiv2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    I denna uppsats har jag valt att undersöka fem elevers syn/uppfattning av religionskunskapsundervisningen. Syftet med uppsatsen är att ta reda på dessa fem elevers syn/uppfattning av religionskunskapsämnet samt deras åsikter om de metoder (tillvägagångssätt) som deras lärare använder i undervisningen. Detta ligger i mitt intresse som blivande religionskunskapslärare. I undersökningen användes en kvalitativ forskningsmetod med djupintervjuer som grund. Resultatet av studien är att eleverna upplever religionskunskapsundervisningen som intressant, rolig samt lärorik. De har även förstått religionskunskapens relevans både för skolan men även för det övriga samhället. Vad gäller deras åsikter om de metoder som läraren använder menar de att de är nöjda med de men att de skulle uppskatta studiebesök samt föreläsningar med externa föreläsare.  

  • 1192002.
    Yakob Olsson, Benjamin
    et al.
    Södertörn University, School of Social Sciences, Business Studies.
    Nasr, Dalal
    Södertörn University, School of Social Sciences, Business Studies.
    Det ideella måttet på prestation: En studie om hur ideella organisationer arbetar med prestationsmätning2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The emerging of new arrangements of financial auditing, accounting and efficiency measurements have had a dramatic impact on the vocabulary and the underlying principles of public sector organizations. This, in turn, has led nonprofit organizations into embracing more business-like and profit-driven approaches. The research field of Nonprofit Management emphasizes that the unique features of nonprofit organizations such as their financial and legal status, as well as the operational goals based on social values, contribute to the extremely complex nature of the conceptualization of organizational effectiveness. Which in turn gives rise to a problematic dilemma which entails that traditional measurement criteria based on financial measures are not able to account for nonprofit organizations' achievements, but in the nonprofit context becomes both ineffective and misleading. In particular, it is about the nonprofit sector's inability to duplicate the sharp and straightforward approach to measuring, manage, and account for nonprofit organizations´ performance. Departing from the above issues the study aims to analyze and examine how nonprofit organizations with an interconnecting business area makes practices of performance management to achieve social and financial goals. And to examine the problem of performance management within the nonprofit sector.

  • 1192003.
    Yakob Olsson, Benjamin
    et al.
    Södertörn University, School of Social Sciences, Business Studies.
    Zraki, Homam
    Södertörn University, School of Social Sciences, Business Studies.
    Utformning och framtagning av en organisationsförändring: En fallstudie på Astra Zeneca2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Läkemedelsindustrin är en starkt reglerad industri där all tillverkning av läkemedel måste utföras efter regler och riktlinjer som går under benämning Good Manufacturing Practice, GMP. Dessa riktlinjer är avsedda för att minimera alla risker som finns och uppkommer med farmaceutisk tillverkning. Astra Zenecas tillverkningsenhet i Södertälje tillverkar mer än 30 olika läkemedel till fler än 100 marknader. Detta har lett till att denna tillverkningsenhet ständigt är uppvaktad av inspektioner från olika marknader och myndigheter, för att försäkra att all tillverkning av läkemedel genomdrivs utifrån GMPs regler och riktlinjer. I denna tillverkningsenhet har ett projekt påbörjats för att utforma och framta en organisationsförändring. Denna förändring handlar om att hitta ett effektiviserat sätt för att kunna hantera och bemöta dessa inspektioner, förändringen innebär skapandet av en ny virtuell enhet som går under benämning Inspektionsteam. Syfte: Syftet med denna studie är att analysera processarbetet vid utformningen och framtagningen av en organisationsförändring inom en specifik avdelning på Astra Zeneca. Metod: Studien har en kvalitativ ansats där fyra personer som är involverade i projektet intervjuats. Studien är baserad på teorier för att djupare kunna studera studieobjektet. Respondenterna och avdelningen som studien utfördes på har hållits anonyma på begäran av företag

  • 1192004.
    Yakob, Ramsin
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Intelligence of Solution Search:Linking errors back to problems2011Conference paper (Refereed)
    Abstract [en]

    This paper investigates the iterative process between analytical-and directional solutionsearch modes in complex problem-solving. It aims to contribute to the growing stream of researchthat focuses on the evolution of solution search strategies that underlie the unfolding ofknowledge-intensive activities in projects. The theoretical departure is the distinction betweenanalytical and directional reasoning in solution search. Empirical material is collected from aqualitative-case study of design engineering activities in a platform development project at VolvoCar Corporation. Personal interviews, project documentation and observations are used to establishconstruct and internal validity of findings. Results show that the search for solutions to complexobstacles is more than a monotonic process of representing action-outcome linkages andsubsequently exploring such beliefs. Synthesized search is discussed as an important mechanismfor reducing knowledge gaps between errors and their underlying problems, and the subsequentdiscrepance between believed action-outcome linkages. Results are presented through a dynamicsolution search model illuminating the relationship between three different forms of solutionsearch modes: analytical-, directional- and synthesized search.

  • 1192005.
    Yakob, Ramsin
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    The Problem with Errors: Solution Search in Platform Development2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation is concerned with problem-solving in platform development. A problem isconceived of as an obstacle that needs to be overcome in order to reach a desired outcome,whereas a solution is denoted by the set of activities required to reach such an outcome. Aplatform is conceived of as the technological foundation made up of a number of elements thatare purposely planned and developed to form a common structure from which a stream ofderivative products can be developed. Problem-solving in platform development is a non-trivialtask since platforms need to cater for both commonality and distinctiveness across a number ofderivative products. Further, several design architectures are intertwined in the development ofplatforms, giving rise to increased complexity. The purpose of this dissertation is to exploreplatform development from a problem-solving perspective, with the purpose of answering whatproblem-solving activities are carried out in platform development processes, how are differentapproaches to the search for solutions related to problem-solving in platform development, andhow can problem-solving in platform development be conceptualized? This dissertation is basedon two empirical studies of platform development processes from the telecommunication andautomotive industry, and draws upon a qualitative research methodology. The result of this studyis an iterative and dynamic model of solution search in problem-solving. This dissertationimplies a distinction between problems and errors in platform development. Solution searchemerge as a matter of choice of whether to engage in problem-solving activities and/or errorcorrection activities during the development of platforms. Solution search also surface as anintermingled process of search for required inputs, outputs, or governing laws (i.e. solutions) forreaching a desired goal. In this process, analytical search, directional search, and synthesizedsearch and the facilitation and management of both feed-back and feedforward is important.

  • 1192006.
    Yakob, Ramsin
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Bengtsson, Marie
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Wahlstedt, Linnéa
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Att Styra Problemlösning2012In: Styrning: med projekt och kunskap i fokus / [ed] Söderlund, Jonas & Tell, Fredrik, Lund: Studentlitteratur, 2012, p. 225-244Chapter in book (Other academic)
  • 1192007.
    Yakob, Ramsin
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering.
    Tell, Fredrik
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering, Business Administration .
    Decomposing and Recomposing - On Anatomies and Integration2007In: International Continuous Innovation Network CINet Conference,2007, 2007Conference paper (Refereed)
    Abstract [en]

      

  • 1192008.
    Yakob, Ramsin
    et al.
    Linköpings universitet, Filosofiska fakulteten.
    Tell, Fredrik
    Linköpings universitet, Filosofiska fakulteten.
    Decomposing and Recomposing - On Anatomies and Integration2007In: International Continuous Innovation Network CINet Conference,2007, 2007Conference paper (Refereed)
    Abstract [en]

      

  • 1192009.
    Yakob, Ramsin
    et al.
    Linköpings universitet, Filosofiska fakulteten.
    Tell, Fredrik
    Linköpings universitet, Filosofiska fakulteten.
    Decomposing and Recomposing - On Anatomies and Integration. A case study of a platform development project in the Telecom Industry2007In: the International Research Network on Organizing by Projects IRNOP Conference,2007, 2007Conference paper (Refereed)
  • 1192010.
    Yakob, Ramsin
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering.
    Tell, Fredrik
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering, Business Administration .
    Decomposing and Recomposing - On Anatomies and Integration. A case study of a platform development project in the Telecom Industry2007In: the International Research Network on Organizing by Projects IRNOP Conference,2007, 2007Conference paper (Refereed)
  • 1192011.
    Yakob, Ramsin
    et al.
    Linköpings universitet.
    Tell, Fredrik
    Linköpings universitet.
    Detecting Errors Early: Management of problem-solving in product platform projects2008In: Platforms, Markets and Innovation / [ed] Annabelle Gawer, Edward Elgar Publishing, 2008Chapter in book (Refereed)
  • 1192012.
    Yakob, Ramsin
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Tell, Fredrik
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Detecting Errors Early: Management of problem-solving in product platform projects2009In: Platforms, Markets and Innovation / [ed] Annabelle Gawer, Cheltenham and Northampton: Edward Elgar , 2009, 1, p. 416-Chapter in book (Other academic)
    Abstract [en]

    'Annabelle Gawer's Platforms, Markets and Innovation is the first serious exploration of the critical but subtle role that platforms play in business, society and our personal lives. As digital technologies penetrate every nook and cranny of the world around us, we rely on platforms to both help us use the new technologies, as well as to organize new markets of innovation that add applications on top of the platforms and make them far more valuable. Dr Gawer's excellent book is designed to help us understand the mysterious nature of platforms. It brings together the insights of twenty-four experts around the world who contributed to the fourteen chapters of the book. Dr Gawer's book is invaluable to anyone trying to understand the nuanced nature of platforms, and their implications for the evolution of innovation in the 21st century.'- Irving Wladawsky-Berger, IBM Academy of Technology, US

    The emergence of platforms is a novel phenomenon impacting most industries, from products to services. Industry platforms such as Microsoft Windows or Google, embedded within industrial ecosystems, have redesigned our industrial landscapes, upset the balance of power between firms, fostered innovation and raised new questions on competition and innovation.

    Annabelle Gawer presents cutting-edge contributions from 24 top international scholars from 19 universities across Europe, the USA and Asia, from the disciplines of strategy, economics, innovation, organization studies and knowledge management. The novel insights assembled in this volume constitute a fundamental step towards an empirically based, nuanced understanding of the nature of platforms and the implications they hold for the evolution of industrial innovation. The book provides an overview of platforms and discusses governance, management, design and knowledge issues.

    With a multidisciplinary approach, this book will strongly appeal to academics and advanced students in management, innovation, strategy, economics and design. It will also prove an enlightening read for business managers in IT industries.

    Contributors: C.Y. Baldwin, K.J. Boudreau, S. Brusoni, M.A. Cusumano, T.R. Eisenmann, D.S. Evans, T.

  • 1192013.
    Yakob, Ramsin
    et al.
    Linköpings universitet, Filosofiska fakulteten.
    Tell, Fredrik
    Linköpings universitet, Filosofiska fakulteten.
    Managing Near Decomposability in Complex Platform Development Projects2007In: the RD Management Conference,2007, 2007Conference paper (Refereed)
  • 1192014.
    Yakob, Ramsin
    et al.
    Linköpings universitet, Filosofiska fakulteten.
    Tell, Fredrik
    Linköpings universitet, Filosofiska fakulteten.
    Managing near decomposability in complex platform development projects2007In: International Journal of Technology Intelligence and Planning (IJTIP), ISSN 1740-2832, E-ISSN 1740-2840, Vol. 3, no 4, p. 387-407Article in journal (Refereed)
    Abstract [en]

    Product Platforms are understood as the sharing of common and underlying technological assets from which a number of derivative products can be produced. The large number and character of technological interdependences give rise to system complexities, implying that product platforms can be managed as nearly decomposable system. We study the managerial implications of such complexity in a telecommunications platform enhancement project. We find that managing near decomposability requires the ability to provide feed-back and feed-forward information, relating to the implementation and planning activities of such a project and that this required output can be provided through the process of aggregation. © 2007, Inderscience Publishers.

  • 1192015.
    Yakob, Ramsin
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering, Business Administration .
    Tell, Fredrik
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering, Business Administration .
    Managing near decomposability in complex platform development projects2007In: International Journal of Technology Intelligence and Planning, ISSN 1740-2832, Vol. 3, no 4, p. 387-407Article in journal (Refereed)
    Abstract [en]

    Product Platforms are understood as the sharing of common and underlying technological assets from which a number of derivative products can be produced. The large number and character of technological interdependences give rise to system complexities, implying that product platforms can be managed as nearly decomposable system. We study the managerial implications of such complexity in a telecommunications platform enhancement project. We find that managing near decomposability requires the ability to provide feed-back and feed-forward information, relating to the implementation and planning activities of such a project and that this required output can be provided through the process of aggregation. © 2007, Inderscience Publishers.

  • 1192016.
    Yakob, Ramsin
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering.
    Tell, Fredrik
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Management and Engineering, Business Administration .
    Managing Near Decomposability in Complex Platform Development Projects2007In: the RD Management Conference,2007, 2007Conference paper (Refereed)
  • 1192017.
    Yakob, Silvana
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Utvecklingsprocess av en mobilapplikation anpassad för KOL patienter2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med arbetet var att utveckla en programvara (app) för patienter med kroniskt obstruktiv lungsjukdom (KOL) för att de skall kunna lära känna sin sjukdom bättre och därmed förbättra sin livsstil för att kunna bromsa försämringen av sjukdomen. Åldersgruppen som appen vänder sig till är mellan 40-80 år och för att de äldre skall ta till sig den nya tekniken med smartphones bör appen ha en enkel design. Den här gruppen patienter har kanske inte så stor teknikvana med datorer så det är också en anledning att ha en app som är lätt att använda.Utvecklingsprocessen av appen har gjorts i flera steg. Först formulerades en rad frågor om hur appen skulle fungera. Därefter formulerades frågor som patienten skulle svara på. Den första versionen av appen var en Powerpointdesign som därefter utvecklades i olika steg till en färdig Android app. Flera patienter fick testa appen under utvecklingens gång och även svara på ett frågeformulär om deras upplevelse av att använda appen. Patienterna gav förslag på ändringar och uttryckte behov av utveckling. Slutversionen av appen blev omtyckt av testgruppen och några förslag har även lämnats till vidare utveckling.

  • 1192018.
    Yakob, Sima
    Södertörn University College, Lärarutbildningen.
    Alternativ religionsundervisning:: En studie om IE- metoden2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This essay is about Abrahams children and its teaching method  the IE- method. The purpose of this essay is to see what four teachers who use the method in their teaching think about it. To get an idea of how these teachers are working with the IE- method, I interviewed them. What are the pros and cons, is it a good way to teach religion? In addition, I look at how the IE- method follows the Lpo94 values and goals. I want in my study to answer these questions:

    1. How is the IE- method used in the classroom?

    2. Is it a good way to teach religion in substance? Can you use the IE- method in other school subjects?

    3. What do the teachers think about the IE- method? The pros and cons?

    4. Does the IE-method meets the requirements of Lpo94? About values and goals?

    5. Is this a teaching method that I could work with in my future work as a teacher?

    To get the answers to my questions, I have been using the interviews in addition to observations of the IE- method in a classroom. And I've also read books and essays on the IE method. The theories I am using is Hjalmar Sunden's role theory, Ulla Holm's empathy theory and Kieran Egan theory about teaching as storytelling. I have linked together these theories with the information I have received through the interviews and my observations.

    With this study, I have been able to see how much the IE-method is popular among children and teachers who use it. The advantage of this method is that it includes all three Abrahamic religions, and among the students I have observed, this has been seen as something positive. The disadvantage with the IE- method is that if we as teachers are going to use it we should know our students very well, where the stories that can become very sensitive.

  • 1192019.
    Yakoob, Linda
    et al.
    Södertörn University College, Lärarutbildningen.
    Calancea, Diana
    Södertörn University College, Lärarutbildningen.
    IKT användning och digital kompetens: En studie om sju lärares IKT användning i historieundervisningen.2008Independent thesis Basic level (professional degree), 10 points / 15 hpStudent thesis
    Abstract [en]

    ICT and digital artifacts is an important resource in the society, especially in schools. That is why we have chosen to study if and how teachers uses ICT and other digital technology in their education in the history subject. We think that both subjects are important because history is a subject that has to do with the past, the present and the future.

    We made qualitative interviews with seven teachers from three different schools. We have analyzed if the teachers sees ICT as a burden or a resource in their education and also in which extend they have digital literacy. We have chosen to discuss different authors view on ICT in the education and digital literacy. We also examined the teaching plan Lpo94 to see what it says about media in the history subject.

    In our analysis we have worked with different perspectives on learning and knowledge. These perspectives are a socio cultural perspective, the cognitive view and the behavioristic view.

    The results indicate a connection between a socio cultural perspective and a cognitive view on learning and also in which extend ICT is used in the history education.

  • 1192020.
    Yakoub, Carola
    Mälardalen University, School of Health, Care and Social Welfare.
    Otillräcklig delaktighet: Medarbetares erfarenheter av organisationsförändringar i socialtjänsten2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 1192021.
    Yakoub, Inaam
    Mälardalen University, School of Education, Culture and Communication.
    Professionalism i förskolan: En kvalitativ studie om vad några förskollärare anser kring professionalism i förskolan samt vad deras professionella ansvar handlar om.2015Independent thesis Basic level (professional degree), 210 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att undersöka några förskollärares upplevelser kring professionalism i förskolan avseende förskollärares uppdrag och svårigheter i arbetet samt vad deras professionella ansvar handlar om. Studien är kvalitativ och datainsamlingen består av fokusgruppsintervjuer och individuella intervjuer. Resultatet visade att uppfattningar kring professionalism i förskolan utgick ifrån tre områden. Dessa områden var ansvar, uppdrag och svårigheter. Studiens slutsater är att förskolläraryrket är komplext och även om förskolläraryrket är professionellt är det inte alltid enkelt att agera på ett professionellt sätt i alla situationer.

  • 1192022.
    Yakoub, Janet
    Swedish National Road and Transport Research Institute.
    Bränsleförbrukning vid körning på väg med personbil med och utan husvagn1996Report (Other academic)
  • 1192023.
    Yakoub, Majckel
    Södertörn University, School of Historical and Contemporary Studies.
    Religiösa friskolor i Sverige: En kvalitativ argumentationsanalytisk undersökning av argumenten som presenterats av partipolitiska aktörer i debatten om religiösa friskolor efter Socialdemokraternas uttalande om att förbjuda religiösa friskolor2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Föreliggande uppsats har i syfte att lista de argument som presenterats av partipolitiker i debattartiklar där de debatterat för eller emot religiösa friskolor efter Socialdemokraternas uttalande om att förbjuda religiösa friskolor den 13 mars 2018. Undersökningen avgränsas till debattartiklar skrivna av partipolitiker under perioden 13 mars 2018 fram till den 24 april 2018 och med hjälp av sannolikhetsurval avgränsas analysen till totalt fyra debattartiklar, två för- respektive emot religiösa friskolor. Tesen och argumenten i varje artikel identifieras och argumenten kategoriseras sedan med hjälp av argumentationsanalys och verktyget pro et contra som pro(för)-argument med uppgift att stärka den identifierade tesen, eller contra(mot)-argument med uppgift att undergräva tesen. Argumenten analyseras sedan för att avgöra hur hög beviskraft de har baserat på graden av tilltro till argumenten (hållbarhet) och hur väl argumenten relaterar till bestämda ståndpunkter/teser i debatten (relevans). Detta för att på ett objektivt sätt analysera en del av debatten som pågått efter Socialdemokraternas uttalande för att avgöra vilka argument som har högst beviskraft samt om dessa argument används för att debattera för- eller emot religiösa friskolor.

    Med intertextualitet som teoretisk utgångspunkt har argumenten i artiklarna ställts mot varandra och resultatet av analysen visar att samtliga argument i alla fyra debattartiklar brister i sin beviskraft då de för olika anledningar inte är hållbara eller relevanta. Analysen visar på att det finns flera argument både för och emot religiösa friskolor som går ihop, för att sen gå isär. Analysen visar också att debatten om religiösa friskolors plats i det svenska samhället har olika åsikter och är en debatt som är värd att debatteras, dock görs bedömningen att det i den fortsatta debatten behövs argument med högre beviskraft för att argumenten ska vara hållbara och relevanta och kunna påverka debatten.

  • 1192024.
    Yakoub, Reem
    et al.
    Mälardalen University, School of Health, Care and Social Welfare.
    Younis, Edda
    Mälardalen University, School of Health, Care and Social Welfare.
    Compassion fatigue: En allmän litteraturöversikt2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 1192025. Yakovlev, A.
    et al.
    Furber, S.
    Krenz, René
    KTH, Superseded Departments, Electronic Systems Design.
    Bystrov, A.
    Design and analysis of a self-timed duplex communication system2004In: I.E.E.E. transactions on computers (Print), ISSN 0018-9340, E-ISSN 1557-9956, Vol. 53, no 7, p. 798-814Article in journal (Refereed)
  • 1192026. Yakovlev, D. G.
    et al.
    Haensel, P.
    Baym, G.
    Pethick, Christopher
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Lev Landau and the concept of neutron stars2013In: Physics Uspekhi, ISSN 1063-7869, E-ISSN 1468-4780, Vol. 56, no 3, p. 289-295Article, review/survey (Refereed)
    Abstract [en]

    We review Lev Landau's role in the history of neutron star physics in the 1930s. According to the recollections of Rosenfeld (Proc. 16th Solvay Conference on Physics, 1974, p. 174), Landau improvised the concept of neutron stars in a discussion with Bohr and Rosenfeld just after the news of the discovery of the neutron reached Copenhagen in February 1932. We present arguments that the discussion must have taken place in March 1931, before the discovery of the neutron, and that they, in fact, discussed the paper written by Landau in Zurich in February 1931 but not published until February 1932 (Phys. Z. Sowjetunion 1, 285). In this paper, Landau mentioned the possible existence of dense stars that look like one giant nucleus; this could be regarded as an early theoretical prediction or anticipation of neutron stars, albeit prior to the discovery of the neutron. The coincidence of the dates of the neutron discovery and the publication of the paper has led to an erroneous association of Landau's paper with the discovery of the neutron. In passing, we outline Landau's contribution to the theory of white dwarfs and to the hypothesis of stars with neutron cores.

  • 1192027. Yakovlev, D. G.
    et al.
    Haensel, P.
    Baym, G.
    Pethick, Christopher
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Lev Landau and the concept of neutron stars2013In: Physics Uspekhi, ISSN 1063-7869, E-ISSN 1468-4780, Vol. 56, no 3, p. 289-295Article, review/survey (Refereed)
    Abstract [en]

    We review Lev Landau's role in the history of neutron star physics in the 1930s. According to the recollections of Rosenfeld (Proc. 16th Solvay Conference on Physics, 1974, p. 174), Landau improvised the concept of neutron stars in a discussion with Bohr and Rosenfeld just after the news of the discovery of the neutron reached Copenhagen in February 1932. We present arguments that the discussion must have taken place in March 1931, before the discovery of the neutron, and that they, in fact, discussed the paper written by Landau in Zurich in February 1931 but not published until February 1932 (Phys. Z. Sowjetunion 1, 285). In this paper, Landau mentioned the possible existence of dense stars that look like one giant nucleus; this could be regarded as an early theoretical prediction or anticipation of neutron stars, albeit prior to the discovery of the neutron. The coincidence of the dates of the neutron discovery and the publication of the paper has led to an erroneous association of Landau's paper with the discovery of the neutron. In passing, we outline Landau's contribution to the theory of white dwarfs and to the hypothesis of stars with neutron cores.

  • 1192028. Yakovlev, S. L.
    et al.
    Volkov, Mikhail V.
    Stockholm University, Faculty of Science, Department of Physics.
    Yarevsky, E.
    Elander, Nils
    Stockholm University, Faculty of Science, Department of Physics.
    The impact of sharp screening on the Coulomb scattering problem in three dimensions2010In: Journal of Physics A: Mathematical and General, ISSN 0305-4470, E-ISSN 1361-6447, Vol. 43, no 24, p. 245302-Article in journal (Refereed)
    Abstract [en]

    The scattering problem for two particles interacting via theCoulomb potential isexamined for the case where the potential has a sharp cut-off at some distance.The problem is solved for two complementary situations, firstly, when theinterior part of the Coulomb potential is left in the Hamiltonian and, secondly,when the long-range tail is considered as the potential. The partial wave resultsare summed up to obtain the wavefunction in three dimensions. It is shownthat in the domains where the wavefunction is expected to be proportionalto the known solutions, the proportionality is given by an operator actingon the angular part of the wavefunction. The explicit representation for thisoperator is obtained in the basis of Legendre polynomials. We proposed adriven Schr¨odinger equation including an inhomogeneous term of the finiterange with purely outgoing asymptotics for its solution in the case of thethree-dimensional scattering problem with long-range potentials.

  • 1192029. Yakovlev, S. L.
    et al.
    Yarevsky, E. A.
    Elander, Nils O.
    Stockholm University, Faculty of Science, Department of Physics.
    Belyaev, A. K.
    Asymptotic Solution of A Multichannel Scattering Problem with A Nonadiabatic Coupling2018In: Theoretical and mathematical physics, ISSN 0040-5779, E-ISSN 1573-9333, Vol. 195, no 3, p. 874-885Article in journal (Refereed)
    Abstract [en]

    We consider a multichannel scattering problem in an adiabatic representation. We assume that the nonadiabatic coupling matrix has a nontrivial value at large internuclear separations, and we construct asymptotic solutions at large internuclear distances. We show that these solutions up to the first order of the perturbation theory are identical to the asymptotic solutions of the reprojection approach, which was previously proposed as a means for solving the electron translation problem in the context of the Born-Oppenheimer method.

  • 1192030.
    Yakovleva, S. A.
    et al.
    Herzen University, Department of Theoretical Physics and Astronomy, St. Petersburg.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Herzen University, Department of Theoretical Physics and Astronomy, St. Petersburg.
    Data on inelastic processes in low-energy potassium-hydrogen and rubidium-hydrogen collisions2018In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 473, no 3, p. 3810-3817Article in journal (Refereed)
    Abstract [en]

    Two sets of rate coefficients for low-energy inelastic potassium-hydrogen and rubidium-hydrogen collisions were computed for each collisional system based on two model electronic structure calculations, performed by the quantum asymptotic semi-empirical and the quantum asymptotic linear combinations of atomic orbitals (LCAO) approaches, followed by quantum multichannel calculations for the non-adiabatic nuclear dynamics. The rate coefficients for the charge transfer (mutual neutralization, ion-pair formation), excitation and de-excitation processes are calculated for all transitions between the five lowest lying covalent states and the ionic states for each collisional system for the temperature range 1000–10 000 K. The processes involving higher lying states have extremely low rate coefficients and, hence, are neglected. The two model calculations both single out the same partial processes as having large and moderate rate coefficients. The largest rate coefficients correspond to the mutual neutralization processes into the K(5s 2S) and Rb(4d 2D) final states and at temperature 6000 K have values exceeding 3 × 10−8 cm3 s−1 and 4 × 10−8 cm3 s−1, respectively. It is shown that both the semi-empirical and the LCAO approaches perform equally well on average and that both sets of atomic data have roughly the same accuracy. The processes with large and moderate rate coefficients are likely to be important for non-LTE modelling in atmospheres of F, G and K-stars, especially metal-poor stars.

  • 1192031.
    Yakovleva, Tatjana
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bazov, Igor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Watanabe, Hiroyuki
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Hauser, Kurt
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Transcriptional control of maladaptive and protective responses in alcoholics: a role of the NF-κB system2010In: Brain, behavior, and immunity, ISSN 0889-1591, E-ISSN 1090-2139, Vol. 25, no Suppl. 1, p. S29-S38Article, review/survey (Refereed)
    Abstract [en]

    Alcohol dependence and associated cognitive impairment appear to result from maladaptive neuroplasticity in response to chronic alcohol consumption, neuroinflammation and neurodegeneration. The inherent stability of behavioral alterations associated with the addicted state suggests that transcriptional and epigenetic mechanisms are operative. NF-κB transcription factors are regulators of synaptic plasticity and inflammation, and responsive to a variety of stimuli including alcohol. These factors are abundant in the brain where they have diverse functions that depend on the composition of the NF-κB complex and cellular context. In neuron cell bodies, NF-κB is constitutively active, and involved in neuronal injury and neuroprotection. However, at the synapse, NF-κB is present in a latent form and upon activation is transported to the cell nucleus. In glia, NF-κB is inducible and regulates inflammatory processes that exacerbate alcohol-induced neurodegeneration. Animal studies demonstrate that acute alcohol exposure transiently activates NF-κB, which induces neuroinflammatory responses and neurodegeneration. Postmortem studies of brains of human alcoholics suggest that repeated cycles of alcohol consumption and withdrawal cause adaptive changes in the NF-κB system that may permit the system to better tolerate excessive stimulation. This type of tolerance, ensuring a low degree of responsiveness to applied stimuli, apparently differs from that in the immune system, and may represent a compensatory response that protects brain cells against alcohol neurotoxicity. This view is supported by findings showing preferential downregulation of pro-apoptotic gene expression in the affected brain areas in human alcoholics. Although further verification is needed, we speculate that NF-κB-driven neuroinflammation and disruption to neuroplasticity play a significant role in regulating alcohol dependence and cognitive impairment.

  • 1192032.
    Yakovleva, Tatjana
    et al.
    Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden.
    Marinova, Z.
    Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden.
    Kuzmin, A.
    Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden.
    Seidah, N. G.
    Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Que., Canada.
    Haroutunian, V.
    Department of Psychiatry, The Mount Sinai School of Medicine, New York, USA.
    Terenius, L.
    Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden.
    Bakalkin, G.
    Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden.
    Dysregulation of dynorphins in Alzheimer disease2007In: Neurobiology of Aging, ISSN 0197-4580, E-ISSN 1558-1497, Vol. 28, no 11, p. 1700-8Article in journal (Refereed)
    Abstract [en]

    The opioid peptides dynorphins may be involved in pathogenesis of Alzheimer disease (AD) by inducing neurodegeneration or cognitive impairment. To test this hypothesis, the dynorphin system was analyzed in postmortem samples from AD and control subjects, and subjects with Parkinson or cerebro-vascular diseases for comparison. Dynorphin A, dynorphin B and related neuropeptide nociceptin were determined in the Brodmann area 7 by radioimmunoassay. The precursor protein prodynorphin, processing convertase PC2 and the neuroendocrine pro7B2 and 7B2 proteins required for PC2 maturation were analyzed by Western blot. AD subjects displayed robustly elevated levels of dynorphin A and no differences in dynorphin B and nociceptin compared to controls. Subjects with Parkinson or cerebro-vascular diseases did not differ from controls with respect to any of the three peptides. PC2 levels were also increased, whereas, those of prodynorphin and pro7B2/7B2 were not changed in AD. Dynorphin A levels correlated with the neuritic plaque density. These results along with the known non-opioid ability of dynorphin A to induce neurodegeneration suggest a role for this neuropeptide in AD neuropathology.

  • 1192033.
    Yakovleva, Tatjana
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Watanabe, Hiroyuki
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala Univ, Uppsala, Sweden..
    Lateralized response in endogenous pathogenic peptides dynorphins caused by traumatic brain injury: Relevance for human psychopathology2016In: Brain Injury, ISSN 0269-9052, E-ISSN 1362-301X, Vol. 30, no 5-6, p. 733-733Article in journal (Other academic)
  • 1192034. Yakpo, Kofi
    et al.
    van den Berg, Margot
    Borges, Robert
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of History, The Hugo Valentin Centre.
    On the linguistic consequences of language contact in Suriname: The case of convergence2015In: In and out of Suriname / [ed] Carlin, Eithne, Isabelle Léglise, Bettina Migge, and Paul Tjon Sie Fat, Leiden: Brill Academic Publishers, 2015Chapter in book (Refereed)
  • 1192035.
    Yakub, Gabriela
    et al.
    Mälardalen University, School of Health, Care and Social Welfare.
    Issa, Enoz
    Mälardalen University, School of Health, Care and Social Welfare.
    Compassion fatigue hos sjuksköterskor2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Compassion is to know how another person feel, fatigue is a condition of constant tiredness. Compassion fatigue occurs among caregivers and is characterized by nurses’ empathetic ability to nurture patients and appears physically, mentally and spiritually in nurses and can have a negative outcome on their well-beings. Problem: Compassion fatigue can occur within care giving professions which can affect the nurse and patient negatively. To prevent it, awareness of compassion fatigue should be highlighted in a larger context. Purpose: To describe aspects of compassion fatigue from the nurse perspective. Method: A general literature review has been applied in the thesis work, as eight quantitative articles, two qualitative articles and three articles of mixed method have been used. Findings: Compassion fatigue has shown to affect nurses working in different care departments caused by high work load, stress, time shortage and critically ill patients. Strategies for coping with compassion fatigue turned to be physical activity and support from family, friends and colleagues. Time for recovery was considered important for nurses as they could disconnect their negative thinking. Conclusion: Knowledge about compassion fatigue and its risk factors should be noted to prevent the condition.

  • 1192036.
    Yakubov, Gleb E.
    et al.
    University of Queensland, Australia; Unilever, UK.
    Macakova, Lubica
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. Unilever, UK.
    Wilson, Stephen
    Unilever, UK.
    Windust, John H. C.
    Unilever, UK.
    Stokes, Jason R.
    Unilever, UK; University of Queensland, Australia.
    Aqueous lubrication by fractionated salivary proteins: Synergistic interaction of mucin polymer brush with low molecular weight macromolecules2015In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 89, p. 34-45Article in journal (Refereed)
    Abstract [en]

    The remarkable lubrication provided by saliva in the oral cavity is vital to human health and wellbeing. Yet, molecular mechanisms for saliva lubrication remain unclear. In this work we report a possible mechanism of synergistic interaction between salivary proteins. By isolating a number of salivary protein fractions, we identify major protein candidates that contribute to saliva lubrication. We discover that a key driver for low friction is a hydrated brush-like layer formed by glycosylated species, with an essential synergistic contribution coming from the low molecular weight components that facilitate spreading, adsorption and strengthening of the salivary film on hydrophobic substrates. Lessons may be learned from saliva for understanding other natural bio-aqueous lubrication systems and for the development of saliva mimics.

  • 1192037. Yakunin, I.
    et al.
    Wade, G.
    Bohlender, D.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Marcolino, W.
    Shultz, M.
    Monin, D.
    Grunhut, J.
    Sitnova, T.
    Tsymbal, V.
    The surface magnetic field and chemical abundance distributions of the B2V helium-strong star HD 1849272015In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 447, no 2, p. 1418-1438Article in journal (Refereed)
    Abstract [en]

    A new time series of high-resolution Stokes I and V spectra of the magnetic B2V star HD 184927 has been obtained in the context of the Magnetism in Massive Stars Large Program with an Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) spectropolarimeter at the Canada-France-Hawaii Telescope and dimaPol liquid crystal spectropolarimeter at 1.8-m telescope of Dominion Astrophysical Observatory. We model the optical and UV spectrum obtained from the International Ultraviolet Explorer (IUE) archive to infer the stellar physical parameters. Using magnetic field measurements, we derive an improved rotational period of 9.531 02 +/- 0.0007 d. We infer the longitudinal magnetic field from lines of H, He, and various metals, revealing large differences between the apparent field strength variations determined from different elements. Magnetic Doppler Imaging using He and O lines yields strongly non-uniform surface distributions of these elements. We demonstrate that the diversity of longitudinal field variations can be understood as due to the combination of element-specific surface abundance distributions in combination with a surface magnetic field that is comprised of dipolar and quadrupolar components. We have reanalysed IUE high-resolution spectra, confirming strong modulation of wind-sensitive C IV and S IV resonance lines. However, we are unable to detect any modulation of the Ha profile attributable to a stellar magnetosphere. We conclude that HD 184927 hosts a centrifugal magnetosphere (eta(*) similar to 2.4(-1.1)(+22) x 10(4)), albeit one that is undetectable at optical wavelengths. The magnetic braking time-scale of HD 184927 is computed to be tau(J) = 0.96 or 5.8 Myr. These values are consistent with the slow rotation and estimated age of the star.

  • 1192038. Yakush, S. E.
    et al.
    Konovalenko, Alexander
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Basso, Simone
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Effect of particle spreading on coolability of Ex-Vessel debris BED2015In: International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015, American Nuclear Society, 2015, p. 1210-1222Conference paper (Refereed)
    Abstract [en]

    Debris bed formation and coolability are studied by DECOSIM code. Main physical mechanisms affecting dispersed particle spreading in the course of melt-water interaction are considered, and their relevance to the formation of porous debris bed in various melt ejection modes is discussed. Numerical simulations of gradually growing and instantly formed debris beds are performed by DECOSIM code. Also, coupled simulations are carried out in which all mechanisms are taken into account simultaneously. It is shown that particle spreading limits the height of debris bed. Also, it is obtained that in some parameter ranges even if local dryout occurs, further particle spreading can render the debris bed coolable, resulting in its reflooding and quenching of the material.

  • 1192039. Yakush, S. E.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Melt agglomeration influence on ex-vessel debris bed coolability2016In: 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2017, Association for Computing Machinery (ACM), 2016Conference paper (Refereed)
    Abstract [en]

    A deep pool of water below reactor vessel is employed in some light water reactors in order to arrest the core melt progression in case of severe accident. The melt is expected to fragment and quench in the pool. Coolability of a porous debris bed in a water pool is considered in this work, with emphasis on the effect of agglomerates formed due to incomplete fragmentation of a melt jet, or incomplete freezing of melt particles reaching the debris bed. Agglomerates block the escape paths for vapor generated in the debris bed, increasing resistance to coolant flow and facilitating occurrence of dry zones. Numerical simulations are carried out by DECOSIM multiphase code. Two main types of debris bed inhomogeneity due to agglomeration are considered: (i) solid impermeable “cake” on the debris bed top, and (ii) distributed low-permeability low-porosity zone with properties determined according to prediction of an agglomeration model. In the presence of either type of flow obstruction, dryout occurs at significantly lower decay heat power than in the case of homogeneous non- agglomerated debris. There is a critical agglomeration fraction above which a large dry zone develops in the debris bed. Debris temperature escalates in the dry zone leading to subsequent remelting of the material. On the contrary, below the critical agglomeration fraction, the dry zone temperature is stabilized by vapor cooling. Implications of the obtained results for assessment of severe accident risks are discussed.

  • 1192040. Yakush, S. E.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    On the evaluation of dryout conditions for a heat-releasing porous bed in a water pool2019In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, p. 895-905Article in journal (Refereed)
    Abstract [en]

    This work is motivated by the problem of restraining temperature escalation inside a porous heat-releasing media submerged in a pool of liquid coolant. When coolant temperature reaches saturation, boiling begins in the bulk of the porous bed, with void generation rate determined by the heating power. Amount of void determines hydrostatic pressure difference that drives natural circulation of two-phase flow through the porous material. At a certain critical value of the heat release rate, the driving head cannot overcome drag of the two phase porous media flow, which results in complete evaporation of coolant in some zone. Temperature of material in the dry zone increases significantly due to deterioration of heat exchange with single phase vapor flow in comparison with boiling flow heat transfer. The paper considers the problem of determining the critical conditions for onset of dryout in a heat-releasing porous bed of an arbitrary shape. The well-known one-dimensional problem for a flat top-flooded bed is revisited, and the functional form of the dryout boundary (expressed as the dryout heat flux, DHF) is derived using non-dimensional parameters. Asymptotic behavior of the solution is analyzed, and, by the method of asymptotic interpolation, a surrogate model is proposed consisting of three single-argument, non-dimensional functions. It is shown that such a model provides acceptable accuracy even in the cases where complete similarity of solutions is not achieved. The results obtained provide important insights into the physics of the problem, reduce the number of free parameters, and enable fast evaluation of dryout conditions without the need of numerical solution of algebraic equations involved in the exact formulation. The ultimate goal of the surrogate model development, i.e. its application to multidimensional configurations, is discussed.

  • 1192041. Yakush, S. E.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Transient phenomena of ex-vessel debris bed formation in an LWR severe accident2009In: Transactions of the American Nuclear Society, 2009, p. 546-547Conference paper (Refereed)
  • 1192042. Yakush, S. E.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Lubchenko, N. T.
    Coolability of heat-releasing debris bed. Part 1: Sensitivity analysis and model calibration2013In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 52, no SI, p. 59-71Article in journal (Refereed)
    Abstract [en]

    Coolability of heat-releasing debris bed is an important issue in the severe accident analysis and management. Traditionally, theoretical studies of top or bottom-fed debris bed coolability have been focused on obtaining a "best estimate" value for the Dryout Heat Flux (DHF) as a function of debris bed parameters (mean particle diameter and porosity). However, an important question for safety analysis is the quantification of uncertainties inherent in the problem. In this paper, a one-dimensional coolability problem is considered, with the aim of analyzing the influence of aleatory uncertainties in input physical parameters and modeling (epistemic) uncertainties on the prediction of DHF. Global sensitivity analysis is applied to rank the aleatory and epistemic parameters according to their effects on DHF and average pressure drop. The most influential model parameters are then calibrated to achieve the best fit to experimental data available. On the one hand, we demonstrate that model calibration is instrumental in achieving considerable improvement of quantitative agreement between the experimental and simulation data. On the other hand, experience of model calibration also suggested that (i) optimization of model parameters with respect to available experimental data on DHF is an ill-posed problem, and (ii) model calibration with respect to one-dimensional pressure drop experiments does not automatically improve the prediction of DHF and in some cases can even worsen it. Based on these insights, one can speculate that further analytical and experimental efforts are necessary to establish a better consistency between model form and experimental data on pressure drop and DHF.

  • 1192043. Yakush, S. E.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Lubchenko, N. T.
    Coolability of heat-releasing debris bed. Part 2: Uncertainty of dryout heat flux2013In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 52, no SI, p. 72-79Article in journal (Refereed)
    Abstract [en]

    One-dimensional coolability problem for a flat homogeneous heat-releasing debris bed is considered, with the critical conditions for steady-state cooling characterized by the Dryout Heat Flux (DHF). DHF is determined for top-fed and bottom-fed debris beds from several two-phase models differing by the treatment of porous and interphase drag. Aleatory uncertainties due to randomness of the debris bed formation scenario and respective physical parameters (particle diameter, porosity) are quantified. The influence of ranges and distributions of input parameters on the uncertainty in the DHF are studied. Major contributors to the DHF uncertainty are identified. Influence of model uncertainty on the prediction of the lower boundary for DHF is discussed.

  • 1192044. Yakush, S. E.
    et al.
    Kudinov, Pavel Yu
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    A model for prediction of maximum post-Dryout temperature in decay-heated debris BED2014In: International Conference on Nuclear Engineering, Proceedings, ICONE, 2014, Vol. 2BConference paper (Refereed)
    Abstract [en]

    Several designs of light water reactors consider melt fragmentation and cooling of corium debris bed in a deep pool as important part of their severe accident management strategies. Traditional approach to assessment of debris coolability is based on the bed dryout criterion. However, this is the most conservative criterion which doesn’t take into account possibility of debris temperature stabilization in steam cooling regime. In this work numerical simulations of cooling of a decay heat-releasing porous debris bed in a water pool are carried out for the conditions where local dryout of porous material occurs. It is shown that the temperature of solid material in the dry zone can be stabilized if sufficient vapor flow is generated in the wetted part of the debris bed beneath the dry zone. A simple one-dimensional model which connects the maximum temperature and the relative size of the dry zone is proposed and verified against the numerical simulations with DECOSIM code for different shapes of the debris beds relevant to severe accident conditions in a Nordic type boiling water reactor (BWR). On the basis of this model, a criterion is obtained which defines the critical relative height of the dry zone corresponding to specific temperature of debris material which can be considered as a safety limit (e.g. start of zirconium oxidation, remelting of metallic debris or oxidic corium, etc.). The criterion allows one to evaluate the safety margins and degree of conservatism introduced by the dryoutbased approach to assessment of debris coolability.

  • 1192045. Yakush, S. E.
    et al.
    Lubchenko, N. T.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Risk-informed approach to debris bed coolability issue2012In: Proceedings Of The 20th International Conference On Nuclear Engineering And The ASME 2012 Power Conference - 2012, Vol 2, ASME Press, 2012, no 1, p. 531-543Conference paper (Refereed)
    Abstract [en]

    Coolability of an ex-vessel debris bed in severe accident conditions is considered from the risk perspective. The concept of "load versus capacity" is employed to quantify the probability of failure (local dryout). Possible choices of "load" and "capacity" in terms of heat fluxes, thermal power or melt mass are discussed. Results of Monte Carlo simulations of distribution functions for the local heat flux and the dryout heat flux at the debris bed top point (defined as the extensions of one-dimensional counterparts) are presented. A surrogate model for the dryout heat flux is developed by the generalization of two-dimensional simulation results. Dryout probabilities are obtained under the conservative assumptions (neglecting the coolability improvement due to side ingress of water into a non-flat debris bed), and from the surrogate model. Outlook is given for the prospective development of the risk-informed approach to debris bed coolability in the context of comprehensive severe accident risk analysis.

  • 1192046.
    Yakush, S.
    et al.
    Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow, Russia.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Simulation of Ex-Vessel Debris Bed Formation and Coolability in a LWR Severe Accident2009In: Proceedings of ISAMM 2009: Implementation of severe accident management measures, Paul Scherrer Institute , 2009Conference paper (Refereed)
  • 1192047.
    Yakush, S.
    et al.
    Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow, Russia.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Transient Phenomena of Ex-vessel Debris Bed Formation in a LWR Severe Accident2009In: American Nuclear Society Transactions 2009, American Nuclear Society, 2009, p. 546-547Conference paper (Refereed)
  • 1192048. Yakush, S.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Dinh, Truc-Nam
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Modeling of Two-Phase Natural Convection Flows in a Water Pool with a Decay-Heated Debris Bed2008In: Proceedings of International Congress on Advances in Nuclear Power Plants (ICAPP 2008), 2008Conference paper (Refereed)
    Abstract [en]

    Coolability of a debris bed in a water pool is studied numerically with the emphasis on the effects of natural convection flows driven by vapor release in the porous bed. A multifluid computer code DECOSIM is developed and applied to the simulation of liquid-vapor flows in the saturated conditions relevant to the long transient of the debris bed formation and coolability problems. Numerical calculations carried out reveal the influence of the debris bed shape on the structure of natural circulation flows in the water pool, as well as on the void fraction distributions inside the debris bed. The effect of large scale flow structures in the pool on transport of debris particles is demonstrated. It is shown that the vortical flow can capture the smaller particle which may result in considerable spreading of the sedimented debris over the pool floor.

  • 1192049. Yakush, S.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Dinh, Truc-Nam
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Multiscale Simulations of Self-organization Phenomena in the Formation and Coolability of Corium Debris Bed2009In: Proc. The 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13), 2009Conference paper (Refereed)
  • 1192050. Yakush, S.
    et al.
    Kudinov, Pavel
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Lubchenko, N.T.
    Sensitivity and Uncertainty Analysis of Debris Bed Coolability2011In: The 14th International Topical Meeting on Nuclear Reactor Thermalhydraulics (NURETH-14), 2011Conference paper (Refereed)
    Abstract [en]

    Theoretical studies of top-fed debris bed coolability available so far have been focused on obtaining the Dryout Heat Flux (DHF) as a function of debris bed parameters (mean particle diameter and porosity). In this paper, uncertainty analysis is carried out to quantify the influence of different factors on DHF. Global sensitivity analysis is applied to rank the drag model parameters according to their effects on DHF and average pressure drop (epistemic uncertainty). The most influential model parameters are then optimized to achieve the best fit to experimental data available. Finally, aleatory uncertainties due to randomness of the debris bed format

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