| 1. |
- Deans, Andrew R, et al.
(författare)
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Finding Our Way through Phenotypes.
- 2015
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Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1545-7885. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Despite a large and multifaceted effort to understand the vast landscape of phenotypic data, their current form inhibits productive data analysis. The lack of a community-wide, consensus-based, human- and machine-interpretable language for describing phenotypes and their genomic and environmental contexts is perhaps the most pressing scientific bottleneck to integration across many key fields in biology, including genomics, systems biology, development, medicine, evolution, ecology, and systematics. Here we survey the current phenomics landscape, including data resources and handling, and the progress that has been made to accurately capture relevant data descriptions for phenotypes. We present an example of the kind of integration across domains that computable phenotypes would enable, and we call upon the broader biology community, publishers, and relevant funding agencies to support efforts to surmount today's data barriers and facilitate analytical reproducibility.
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| 2. |
- Byass, Peter, et al.
(författare)
-
Beyond 2015 : time to reposition Scandinavia in global health?
- 2013
-
Ingår i: Global Health Action. - Järfälla, Sweden : CoAction Publishing. - 1654-9716 .- 1654-9880. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Global health currently finds itself in an exciting, almost bewildering, state of flux. A plethora of initiatives, statements, high-level meetings, and other activities are generating a continuous flow of new ideas, with the impetus at least partly driven by the advent of the 2015 target date set for the Millennium Development Goals that were adopted in 2000. Whatever shape the post-2015 global health landscape may eventually take, it is already clear that there will be new targets of some kind as the world tries to make further progress on some of the less tractable health issues.
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| 3. |
- Carpenter, Stephen R., et al.
(författare)
-
Accelerate Synthesis in Ecology and Environmental Sciences
- 2009
-
Ingår i: BioScience. - : Oxford University Press (OUP). - 0006-3568 .- 1525-3244. ; 59:8, s. 699-701
-
Tidskriftsartikel (refereegranskat)abstract
- Ecology is a leading discipline in the synthesis of diverse knowledge. Ecologists have had considerable experience in bringing together diverse, multinational data sets, disciplines, and cultural perspectives to address a wide range of issues in basic and applied science. Now is the time to build on this foundation and invest in ecological synthesis through new national or international programs. While synthesis takes place through many mechanisms, including individual efforts, working groups, and research networks, centers are extraordinarily effective institutional settings for advancing synthesis projects.
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| 4. |
- Friberg, Peter, et al.
(författare)
-
Public and global engagement with global health
- 2013
-
Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 381:9883, s. 2066-2066
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Tidskriftsartikel (refereegranskat)abstract
- Global health is widely regarded as being grounded in public and global engagement. But much of the process of global health is dominated by Northern institutions, expert groups, think-tanks, high-level meetings, and the like. Indeed, the exponential growth of global health in the past decade may soon turn into terminal decline unless truly global and broad-based ownership of the concept can be achieved.
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| 5. |
- Nilsson, Kerstin, et al.
(författare)
-
54 forskare: Inte alla klarar höjd pensions-ålder
- 2017
-
Ingår i: Svenska Dagbladet, Stockholm. - 1101-2412.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Ett hållbart och acceptabelt pensionssystem måste utformas utifrån personliga förutsättningar och förhållanden i arbetslivet, så att fler klarar att arbeta i högre ålder. Att enbart genom ekonomiska åtgärder höja pensionsåldern är inte långsiktigt hållbart, skriver 54 forskare.DEBATT | PENSIONForskning visar att cirka var fjärde har en diagnos eller skada orsakad av sitt arbete. Detta gör arbetsorsakad sjukdom och skada till ett betydelsefullt folkhälsoproblem. Att då enbart genom ekonomiska åtgärder höja pensionsåldern för samtliga (yrkes)grupper utifrån deras kronologiska ålder är inte långsiktigt hållbart när individers biologiska ålder är så olika bland annat till följd av arbetslivet. Detta är en demokratifråga. Forskning om äldre i arbetslivet och hållbart arbete visar att man då främst flyttar individer från pensionssystemet till sjukförsäkringssystemet och ökar klyftorna i samhället.Debatt Det här är en argumenterande text med syfte att påverka. Åsikterna som uttrycks är skribentens egna.Vi är 54 forskare som nu gemensamt har skrivit denna debattartikel. Anledningen är att vi är oroade över att cirka var fjärde blir sjuk av sitt arbete samtidigt som man i det förslag som ligger om att senarelägga ålderspensionen i princip utgår ifrån att arbetskraftsdeltagande enbart styrs av ekonomin. Vi vill trycka på betydelsen av åtgärder i arbetslivet för att komma tillrätta med ohälsan, det vill säga inte enbart ekonomiska restriktioner som tvingar folk som inte kan, vill och orkar att stanna kvar i arbetslivet till en högre kronologisk ålder.Pensionssystemet bygger på att vi ska arbeta en viss del av våra liv för att förtjäna möjligheter till pension. Vi bör dock inte enbart utgå ifrån antalet år sedan en person föddes, då korttidsutbildade generellt träder in på arbetsmarknaden tidigare än långtidsutbildade. De har alltså varit en del av arbetskraften från en yngre ålder. Människor med kortare utbildning har oftare ett arbete som innebär påfrestningar som kan inverka negativt på hälsotillståndet och som till och med kan påskynda det biologiska åldrandet. Dessutom lever korttidsutbildade generellt sett inte lika länge som långtidsutbildade, vilket delvis även avspeglar skilda livs- och arbetsvillkor.Den svenska sjukförsäkringsreformen 2008 avsåg att få tillbaka människor i arbete. Men studien fann att den faktiskt bidrog till att fler gick i tidig ålderspension av dem som var i åldern 55–64 år. Ökningen var störst bland korttidsutbildade. Mer än 5 procent fler gick i tidig ålderspension då det blev svårare att få sjukpenning och sjukersättning. Vi kan notera att det är vanligare att manliga chefer tar ut tidig ålderspension, jämfört med kvinnliga maskinskötare inom tillverkningsindustrin. I vissa yrken är det dessutom vanligare att människor, trots pension, både orkar och faktiskt ges möjlighet att arbeta vidare om de har en specialkompetens som efterfrågas. Om vi endast kombinerar ekonomiska morötter med piskor finns en stor risk att vi ökar klyftan mellan grupper som både kan och vill fortsätta att yrkesarbeta och personer som av olika skäl inte längre kan eller orkar.Ta nytta av den forskning som vi har tagit fram. Ett hållbart och acceptabelt pensionssystem måste utformas utifrån personliga förutsättningar och förhållanden i arbetslivet. Ett hållbart arbetsliv för allt fler i vår åldrande befolkning fordrar att vi samtidigt beaktar faktorer som relaterar till biologisk/kroppslig ålder, mental/kognitiv ålder samt social ålder/livsloppsfas och våra attityder som är kopplade till ålder. Vi måste ta större hänsyn till olika förutsättningar och varierande funktionsförmåga och utifrån detta anpassa de åtgärder som gör att arbetslivet blir möjligt och hållbart för allt fler även i högre ålder.”Morötter” är viktigare för en god arbetshälsa och hög produktivitet än en piska i form av oron för en dålig ekonomi.Forskning visar att pedagogik som bygger på ”morötter” oftast är betydligt bättre än ”piskor” för att nå framgångsrika och långsiktiga mål. ”Morötter” i samhället, för organisationer, företag och individer är därför viktiga för god arbetshälsa och fortsatt produktivitet och kan bidra till ett längre arbetsliv även för grupper som tidigare inte ens klarat av att arbeta fram till pensionsåldern. Genom forskning inom området har bland annat swage-modellen utarbetats. Detta är ett verktyg som visar på komplexiteten i ett hållbart arbetsliv och tillsammans med systematiskt arbetsmiljöarbete, handlingsplaner och åtgärder syftar till ett mer hållbart arbetsliv. Morötter är enligt forskningen i detta sammanhang åtgärder för en god fysisk och mental arbetsmiljö, avpassad arbetsbelastning, stödjande teknik, att man kan anpassa arbetstakten, alternativa arbetstidsmodeller vid behov. Det är viktigt att man känner sig trygg och förväntas och tillåts vara delaktig, att man blir sedd av chefen och arbetskamraterna. Att de egna arbetsuppgifterna upplevs som meningsfulla och behövda av andra skapar självförverkligande och tillfredsställelse i arbetet. Att man känner att ens arbetsuppgifter och man själv är viktig för organisationen och företaget. Att man trots högre ålder inkluderas i olika nysatsningar och får tillgång till kompetensutveckling och inte blir åsidosatt eller åldersdiskriminerad. Utvärderingar visar att de äldre medarbetarna som fick några av dessa anpassningar och möjligheter var mer effektiva, utvilade, stimulerade när de var på arbetet samtidigt som sjukfrånvaron minskade. Vilket i sin tur bidrar till ett längre arbetsliv för grupper som tidigare inte klarat av att arbeta fram till pensionsåldern. I organisationer som bygger på en deltagar- och lärandekultur rustas de anställda för att klara omställningar, nya arbetsuppgifter och vid behov även yrkesbyten.Med en åldrande befolkning där allt fler lever allt längre behöver vi arbeta till en högre ålder i framtiden för att pensionssystemet ska hålla. Men ”morötter” är viktigare för en god arbetshälsa och hög produktivitet än en piska i form av oron för en dålig ekonomi. Det kräver också att vi ändrar våra attityder och förhållningssätt till äldre på arbetsmarknaden, vilket vi bäst gör genom att organisationer och företag får incitament till och erbjuder mer individanpassade arbetsvillkor, särskilt för personer i högre ålder. Låt oss därför använda den framtagna kunskapen i praktiken för att göra arbetslivet friskt och hållbart för alla åldrar.
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| 6. |
- Nilsson, Kerstin, et al.
(författare)
-
Vi är oroade över senare ålderspension
- 2017
-
Ingår i: Dagens Samhälle. - 1652-6511.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Var fjärde person blir i dag sjuk till följd av sitt arbete. Att höja pensionsåldern för alla yrkesgrupper, utan konkreta åtgärder för att minska ohälsan, är därför problematiskt och mycket oroande. Det är, enligt forskarna, inte långsiktigt samhällsekonomiskt lönsamt att utan andra åtgärder höja pensionsåldern för alla. Vi – 54 forskare – är mycket oroade över konsekvenserna av att, som föreslagits, senarelägga ålderspensionen.Förslaget utgår i princip från arbetskraftsdeltagande i princip enbart styrs av ekonomin, medan forskningen visar att det bara är en av flera faktorer som styr hur länge och hur mycket människor väljer att arbeta.Det här sättet att lösa problemet med en åldrande befolkning och ett sviktande pensionssystem är inte samhällsekonomiskt lönsamt på lång sikt, utan riskerar bara att flytta runt folk mellan olika ersättningssystem. Pensionssystemet bygger på att vi ska arbeta en viss del av våra liv för att tjäna in vår pension. Vi bör dock inte enbart utgå ifrån ålder eller antalet år sedan en person föddes då korttidsutbildade generellt träder in på arbetsmarknaden tidigare än långtidsutbildade. De med kortare utbildningstid har alltså varit en del av arbetskraften från en yngre ålder. Människor med kortare utbildning har också oftare ett arbete som innebär påfrestningar som kan inverka negativt på hälsotillståndet och som till och med kan påskynda det biologiska åldrandet. Dessutom lever korttidsutbildade generellt sett inte lika länge som långtidsutbildade, vilket delvis även avspeglar skilda livs- och arbetsvillkor.Ta nytta av den forskning som vi har tagit fram. Ekonomin är självklart viktigt för att vi ska vilja arbeta, men den är som sagt enbart en av flera faktorer med betydelse vårt arbetsliv.Hälsotillståndet, både det fysiska och det mentala, har en avgörande betydelse för hur länge och hur mycket vi orkar arbeta. Ett fysiskt och mentalt belastande arbete är en stark riskfaktor för en nedsatt hälsa i slutet av arbetslivet. Arbetstid, arbetstakt och möjlighet till återhämtning spelar en allt större roll ju äldre vi blir. Andra aspekter är arbetsinnehåll, hur meningsfulla och stimulerande arbetsuppgifterna är, balansen mellan arbete och familjesituation och fritidsaktiviteter. Organisationskultur, ledarskapet, stöd i arbetet och kompetens har stor betydelse för om vi ska kunna och vilja arbeta till en högre ålder. Vi måste ta större hänsyn till olika förutsättningar och varierande funktionsförmåga och utifrån detta anpassa de åtgärder som gör att arbetslivet blir möjligt och hållbart för allt fler även i högre ålder.Ett hållbart och acceptabelt pensionssystem måste därför utformas utifrån personliga förutsättningar och förhållanden i arbetslivet. Ett hållbart arbetsliv för allt fler i vår åldrande befolkning fordrar att vi samtidigt beaktar faktorer som relaterar till biologisk/kroppslig ålder, mental/kognitiv ålder samt social ålder/livsloppsfas samt de attityder som är kopplade till ålder.
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| 7. |
- Raghavan, Maanasa, et al.
(författare)
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Genomic evidence for the Pleistocene and recent population history of Native Americans
- 2015
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 349:6250
-
Tidskriftsartikel (refereegranskat)abstract
- Howand when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericues and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.
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| 8. |
- Abylayeva, Akbota
(författare)
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Inequalities for some classes of Hardy type operators and compactness in weighted Lebesgue spaces
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This PhD thesis is devoted to investigate weighted differential Hardy inequalities and Hardy-type inequalities with the kernel when the kernel has an integrable singularity, and also the additivity of the estimate of a Hardy type operator with a kernel.The thesis consists of seven papers (Papers 1, 2, 3, 4, 5, 6, 7) and an introduction where a review on the subject of the thesis is given. In Paper 1 weighted differential Hardy type inequalities are investigated on the set of compactly supported smooth functions, where necessary and sufficient conditions on the weight functions are established for which this inequality and two-sided estimates for the best constant hold. In Papers 2, 3, 4 a more general class of -order fractional integrationoperators are considered including the well-known classical Weyl, Riemann-Liouville, Erdelyi-Kober and Hadamard operators. Here 0 < < 1. In Papers 2 and 3 the boundedness and compactness of two classes of such operators are investigated namely of Weyl and Riemann-Liouville type, respectively, in weighted Lebesgue spaces for 1 < p ≤ q < 1 and 0 < q < p < ∞. As applications some new results for the fractional integration operators of Weyl, Riemann-Liouville, Erdelyi-Kober and Hadamard are given and discussed.In Paper 4 the Riemann-Liouville type operator with variable upper limit is considered. The main results are proved by using a localization method equipped with the upper limit function and the kernel of the operator. In Papers 5 and 6 the Hardy operator with kernel is considered, where the kernel has a logarithmic singularity. The criteria of the boundedness and compactness of the operator in weighted Lebesgue spaces are given for 1 < p ≤ q < ∞ and 0 < q < p < ∞, respectively. In Paper 7 we investigated the weighted additive estimates for integral operators K+ and K¯ defined byK+ ƒ(x) := ∫ k(x,s) ƒ(s)ds, K¯ ƒ(x) := ∫ k(x,s)ƒ(s)ds.It is assumed that the kernel k of the operators K+and K- belongs to the general Oinarov class. We derived the criteria for the validity of these addittive estimates when 1 ≤ p≤ q < ∞
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| 9. |
- Abylayeva, A. M., et al.
(författare)
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Additive weighted Lp estimates of some classes of integral operators involving generalized Oinarov Kernels
- 2017
-
Ingår i: Journal of Mathematical Inequalities. - : Ele-Math. - 1846-579X .- 1848-9575. ; 11:3, s. 683-694
-
Tidskriftsartikel (refereegranskat)abstract
- Inequalities of the formkuK f kq 6C(kr f kp +kvH f kp) , f > 0,are considered, where K is an integral operator of Volterra type and H is the Hardy operator.Under some assumptions on the kernel K we give necessary and sufficient conditions for suchan inequality to hold.1
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| 10. |
- Aeddula, Omsri, 1993-, et al.
(författare)
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AI-driven Ossification Assessment in Knee MRI : A Product-Service System Development for Informed Clinical Decision-Making
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Traditionally, assessing the degree of ossification in the epiphyseal plate for growth plate development relies on manual evaluation, which can be inefficient due to the complexities of the distal femoral epiphysis anatomy. Existing methods lack efficient detection techniques.Method: This study proposes an AI-based decision support system, designed within a product-service system (PSS) framework, to automate ossification assessment and detection of the distal femoral epiphysis in knee magnetic resonance imaging (MRI) data. The system leverages advanced machine learning techniques, specifically two Convolutional Neural Networks (CNNs), combined with computer vision techniques. This intelligent system analyzes MRI slices to predict the optimal slice for analysis and identify variations in the degree of ossification within individual datasets.Results: The proposed method's effectiveness is demonstrated using a set of T2-weighted gradient echo grayscale knee MRI data. The system successfully detects the complex anatomy of the distal femoral epiphysis, revealing variations in the degree of ossification ranging from completely closed/open to fully open/closed regions.Conclusions: This study presents a robust and efficient AI-based method, integrated within a PSS framework, for measuring the degree of ossification in the distal femoral epiphysis. This approach automates ossification assessment, providing valuable insights for clinical decision-making by clinicians and forensic practitioners. The PSS framework ensures seamless integration of the AI technology into existing workflows.
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| 11. |
- Aeddula, Omsri, 1993-
(författare)
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Data-Driven Decision Support Systems for Product Development - A Data Exploration Study Using Machine Learning
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern product development is a complex chain of events and decisions. The ongoing digital transformation of society, increasing demands in innovative solutions puts pressure on organizations to maintain, or increase competitiveness. As a consequence, a major challenge in the product development is the search for information, analysis, and the build of knowledge. This is even more challenging when the design element comprises complex structural hierarchy and limited data generation capabilities. This challenge is even more pronounced in the conceptual stage of product development where information is scarce, vague, and potentially conflicting. The ability to conduct exploration of high-level useful information using a machine learning approach in the conceptual design stage would hence enhance be of importance to support the design decision-makers, where the decisions made at this stage impact the success of overall product development process.The thesis aims to investigate the conceptual stage of product development, proposing methods and tools in order to support the decision-making process by the building of data-driven decision support systems. The study highlights how the data can be utilized and visualized to extract useful information in design exploration studies at the conceptual stage of product development. The ability to build data-driven decision support systems in the early phases facilitates more informed decisions.The thesis presents initial descriptive study findings from the empirical studies, showing the capabilities of the machine learning approaches in extracting useful information, and building data-driven decision support systems. The thesis initially describes how the linear regression model and artificial neural networks extract useful information in design exploration, providing support for the decision-makers to understand the consequences of the design choices through cause-and-effect relationships on a detailed level. Furthermore, the presented approach also provides input to a novel visualization construct intended to enhance comprehensibility within cross-functional design teams. The thesis further studies how the data can be augmented and analyzed to extract the necessary information from an existing design element to support the decision-making process in an oral healthcare context.
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| 12. |
- Aeddula, Omsri, 1993-
(författare)
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Navigating Data Challenges: AI-Driven Decision Support for Product-Service System Development
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Solution providers are transitioning from product-centric models to service-oriented solutions. This shift has led to the rise of Product-Service Systems (PSS), which offer a holistic approach by integrating physical products with associated services. However, the inherent complexity and collaborative nature of PSS development present a significant challenge: information gathering, analysis, and knowledge building. This is further amplified in the early stages of PSS development due to data challenges such as uncertainty, ambiguity, and complexity. This complicates informed decision-making, potentially leading to the risk of sub-optimal outcomes and impacting the success of final offerings.This research proposes an AI-powered data analysis approach to address these data challenges and augment the decision-making process of PSS development. The focus is on supporting early-stage decision-making, as decisions made at this stage greatly impact the success of final solutions. The research investigates how data can be utilized and visualized to extract actionable insights, ultimately facilitating informed decision-making.The presented research demonstrates that AI-powered data analysis effectively supports informed decision-making in early-stage PSS development. By extracting actionable insights from complex data, handling data limitations, and enabling informed strategic decisions, knowledge sharing, and collaboration are facilitated among stakeholders. Furthermore, integrating AI with visualization tools fosters knowledge building and a deeper understanding of system behavior, ultimately leading to more successful PSS solutions. The efficacy of AI-powered data analysis for handling diverse data types across application domains is demonstrated, potentially leading to benefits such as a deeper understanding of system behavior and proactive solution strategies. These advancements contribute to developing decision support systems specifically for PSS development.Overall, this research demonstrates the efficacy of AI-powered data analysis in overcoming data challenges and empowering decision-makers in early-stage PSS development. This translates to more informed choices, leading to the creation of successful and efficient PSS solutions.
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| 13. |
- Akhmetkaliyeva, Raya D., et al.
(författare)
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Some new results concerning a class of third-order differential equations
- 2015
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Ingår i: Applicable Analysis. - : Taylor & Francis. - 0003-6811 .- 1563-504X. ; 94:2, s. 419-434
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Tidskriftsartikel (refereegranskat)abstract
- We consider the following third-order differential equation with unbounded coefficients:Some new existence and uniqueness results are proved, and precise estimates of the norms of the solutions are given. The obtained results may be regarded as a unification and extension of all other results of this type
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| 14. |
- Akhmetkaliyeva, Raya
(författare)
-
Maximal regularity of the solutions for some degenerate differential equations and their applications
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This PhD thesis deals with the study of existence and uniqueness together with coercive estimates for solutions of certain differential equations.The thesis consists of six papers (papers A, B, C, D, E and F), two appendices and an introduction, which put these papers and appendices into a more general frame and which also serves as an overview of this interesting field of mathematics.In the text below the functionsr = r(x), q = q(x), m = m(x) etc. are functions on (−∞,+∞), which are different but well defined in each paper. Paper A deals with the study of separation and approximation properties for the differential operator in the Hilbert space (here is the complex conjugate of ). A coercive estimate for the solution of the second order differential equation is obtained and its applications to spectral problems for the corresponding differential operator is demonstrated. Some sufficient conditions for the existence of the solutions of a class of nonlinear second order differential equations on the real axis are obtained.In paper B necessary and sufficient conditions for the compactness of the resolvent of the second order degenerate differential operator in is obtained. We also discuss the two-sided estimates for the radius of fredholmness of this operator.In paper C we consider the minimal closed differential operator in , where are continuously differentiable functions, and is a continuous function. In this paper we show that the operator is continuously invertible when these coefficients satisfy some suitable conditions and obtain the following estimate for : ,where is the domain of .In papers D, E, and F various differential equations of the third order of the form are studied in the space .In paper D we investigate the case when and .Moreover, in paper E the equation (0.1) is studied when . Finally, in paper F the equation (0.1) is investigated under certain additional conditions on .For these equations we establish sufficient conditions for the existence and uniqueness of the solution, and also prove an estimate of the form for the solution of equation (0.1).
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| 15. |
- Almqvist, Andreas, et al.
(författare)
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A new approach for studying cavitation in lubrication
- 2014
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Ingår i: Journal of tribology. - : ASME International. - 0742-4787 .- 1528-8897. ; 136:1
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Tidskriftsartikel (refereegranskat)abstract
- The underlying theory, in this paper, is based on clear physical arguments related to conservation of mass flow and considers both incompressible and compressible fluids. The result of the mathematical modeling is a system of equations with two unknowns, which are related to the hydrodynamic pressure and the degree of saturation of the fluid. Discretization of the system leads to a linear complementarity problem (LCP), which easily can be solved numerically with readily available standard methods and an implementation of a model problem in matlab code is made available for the reader of the paper. The model and the associated numerical solution method have significant advantages over today's most frequently used cavitation algorithms, which are based on Elrod-Adams pioneering work
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| 16. |
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| 17. |
- Almqvist, Andreas, et al.
(författare)
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Flow in thin domains with a microstructure : Lubrication and thin porous media
- 2017
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Ingår i: AIP Conference Proceedings. - : AIP Publishing. - 0094-243X .- 1551-7616. ; 1798
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Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to homogenization of different models of flow in thin domains with a microstructure. The focus is on applications connected to the effect of surface roughness in full film lubrication, but a parallel to flow in thin porous media is also discussed. Mathematical models of such flows naturally include two small parameters. One is connected to the fluid film thickness and the other to the microstructure. The corresponding asymptotic analysis is a delicate problem, since the result depends on how fast the two small parameters tend to zero relative to each other. We give a review of the current status in this area and point out some future challenges.
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| 18. |
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| 19. |
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| 20. |
- Almqvist, Andreas, et al.
(författare)
-
Homogenization of a Reynolds equation describing compressible flow
- 2012
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Ingår i: Journal of Mathematical Analysis and Applications. - : Elsevier BV. - 0022-247X .- 1096-0813. ; 390:2, s. 456-471
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Tidskriftsartikel (refereegranskat)abstract
- We homogenize a Reynolds equation with rapidly oscillating film thickness function hε, assuming a constant compressiblity factor in the pressure-density relation. The oscillations are due to roughness on the bounding surfaces of the fluid film. As shown by previous studies, homogenization is an effective approach for analyzing the effects of surface roughness in hydrodynamic lubrication. By two-scale convergence theory we obtain the limit problem (homogenized equation) and strong convergence in L2 for the unknown density ρε. By adding a small corrector term we also obtain strong convergence in the Sobolev norm.
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| 21. |
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| 22. |
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| 23. |
- Almqvist, Andreas, et al.
(författare)
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Homogenization of the Reynolds equation
- 2013
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Ingår i: Encyclopedia of Tribology. - Berlin : Springer-Verlag New York Inc.. - 9780387928968 - 9780387928975 ; , s. 1685-1690
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Bokkapitel (refereegranskat)
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| 24. |
- Almqvist, Andreas, et al.
(författare)
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Homogenization of the unstationary incompressible Reynolds equation
- 2007
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 40:9, s. 1344-1350
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to the effects of surface roughness during hydrodynamic lubrication. In the numerical analysis a very fine mesh is needed to resolve the surface roughness, suggesting some type of averaging. A rigorous way to do this is to use the general theory of homogenization. In most works about the influence of surface roughness, it is assumed that only the stationary surface is rough. This means that the governing Reynolds type equation does not involve time. However, recently, homogenization was successfully applied to analyze a situation where both surfaces are rough and the lubricant is assumed to have constant bulk modulus. In this paper we will consider a case where both surfaces are assumed to be rough, but the lubricant is incompressible. It is also clearly demonstrated, in this case that homogenization is an efficient approach. Moreover, several numerical results are presented and compared with those corresponding to where a constant bulk modulus is assumed to govern the lubricant compressibility. In particular, the result shows a significant difference in the asymptotic behavior between the incompressible case and that with constant bulk modulus.
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| 25. |
- Almqvist, Andreas, et al.
(författare)
-
Modelling cavitation in (elasto)hydrodynamic lubrication
- 2016
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Ingår i: Advances in tribology. - Croatia : INTECH. - 9789535127420 - 9789535127437 ; , s. 198-213
-
Bokkapitel (refereegranskat)abstract
- In this chapter we will present a derivation of a mathematical model describing how cavitation influences the pressure distribution in a thin lubricant film between two moving surfaces. The main idea in the derivation is to first describe the influence of cavitation on the mass flow and thereafter using a conservation law for the mass. This leads to a nonlinear system with two complementary variables: one is the pressure distribution and the other is related to the density, i.e. a nonlinear complementarity problem (NLCP). The proposed approach is used to derive a mass conserving cavitation model considering that density, viscosity and film thickness of the lubricant depend on the pressure. To demonstrate the applicability and evaluate the proposed model and the suggested numerical implementation, a few model problems are analysed and presented.
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| 26. |
- Almqvist, Andreas, et al.
(författare)
-
Multiscale homogenization of a class of nonlinear equations with applications in lubrication theory and applications
- 2011
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Ingår i: Journal of Function Spaces and Applications. - : Hindawi Limited. - 0972-6802 .- 1758-4965. ; 9:1, s. 17-40
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Tidskriftsartikel (refereegranskat)abstract
- We prove a homogenization result for monotone operators by using the method of multiscale convergence. More precisely, we study the asymptotic behavior as epsilon -> 0 of the solutions u(epsilon) of the nonlinear equation div a(epsilon)(x, del u(epsilon)) = div b(epsilon), where both a(epsilon) and b(epsilon) oscillate rapidly on several microscopic scales and a(epsilon) satisfies certain continuity, monotonicity and boundedness conditions. This kind of problem has applications in hydrodynamic thin film lubrication where the bounding surfaces have roughness on several length scales. The homogenization result is obtained by extending the multiscale convergence method to the setting of Sobolev spaces W-0(1,p)(Omega), where 1 < p < infinity. In particular we give new proofs of some fundamental theorems concerning this convergence that were first obtained by Allaire and Briane for the case p = 2.
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| 27. |
- Almqvist, Andreas, et al.
(författare)
-
New concepts of homogenization applied in rough surface hydrodynamic lubrication
- 2007
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Ingår i: International Journal of Engineering Science. - : Elsevier BV. - 0020-7225 .- 1879-2197. ; 45:1, s. 139-154
-
Tidskriftsartikel (refereegranskat)abstract
- This work introduces a new concept of homogenization that enables efficient analysis of the effects of surface roughness representations obtained by measurements in applications modeled by the Reynolds equation. Examples of such applications are trust- and journal-bearings. The numerical analysis of these types of applications requires an extremely dense computational mesh in order to resolve the surface roughness, suggesting some type of averaging. One such method is homogenization, which has been applied to Reynolds type equations with success recently. This approach is similar to the technique proposed by Patir and Cheng, who introduced flow factors determining the hydrodynamic action due to surface roughness. The difference is, however, that the present technique has a rigorous mathematical support. Moreover, the recipe to compute the averaged coefficients is simple without any ambiguities. Using either the technique proposed by Patir and Cheng or homogenization, the coefficients determining the averaged Reynolds equation are obtained by solving differential equations on a local scale. Unfortunately, this is detrimental when investigating the effects induced by real, measured, surface roughness, even though these local problems may be solved in parallel. The present work presents a solution by applying the technique based on bounds. This technique transforms the stationary Reynolds equation into two computationally feasible forms, one for the upper bound and one for the lower bound, where the flow factors are obtained by straightforward integration. Together with the preciseness of these bounds, the bounds approach becomes an eminent tool suitable for investigating the effect of real, measured, surface roughness on hydrodynamic performance.
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| 28. |
- Almqvist, Andreas, et al.
(författare)
-
New insights on lubrication theory for compressible fluids
- 2019
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Ingår i: International Journal of Engineering Science. - : Elsevier. - 0020-7225 .- 1879-2197. ; 145
-
Tidskriftsartikel (refereegranskat)abstract
- The fact that the film is thin is in lubrication theory utilised to simplify the full Navier–Stokes system of equations. For incompressible and iso-viscous fluids, it turns out that the inertial terms are small enough to be neglected. However, for a compressible fluid, we show that the influence of inertia depends on the (constitutive) density-pressure relationship and may not always be neglected. We consider a class of iso-viscous fluids obeying a power-law type of compressibility, which in particular includes both incompressible fluids and ideal gases. We show by scaling and asymptotic analysis, that the degree of compressibility determines whether the terms governing inertia may or may not be neglected. For instance, for an ideal gas, the inertial terms remain regardless of the film height-to-length ratio. However, by means of a specific modified Reynolds number that we define we show that the magnitudes of the inertial terms rarely are large enough to be influential. In addition, we consider fluids obeying the well-known Dowson and Higginson density-pressure relationship and show that the inertial terms can be neglected, which allows for obtaining a Reynolds type of equation. Finally, some numerical examples are presented in order to illustrate our theoretical results.
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| 29. |
- Almqvist, Andreas, et al.
(författare)
-
On flow of power-law fluids between adjacent surfaces : Why is it possible to derive a Reynolds-type equation for pressure-driven flow, but not for shear-driven flow?
- 2023
-
Ingår i: Applications in Engineering Science. - : Elsevier. - 2666-4968. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Flows of incompressible Navier–Stokes (Newtonian) fluids between adjacent surfaces are encountered in numerous practical applications, such as seal leakage and bearing lubrication. In seals, the flow is primarily pressure-driven, whereas, in bearings, the dominating driving force is due to shear. The governing Navier–Stokes system of equations can be significantly simplified due to the small distance between the surfaces compared to their size. From the simplified system, it is possible to derive a single lower-dimensional equation, known as the Reynolds equation, which describes the pressure field. Once the pressure field is computed, it can be used to determine the velocity field. This computational algorithm is much simpler to implement than a direct numerical solution of the Navier–Stokes equations and is therefore widely employed by engineers. The primary objective of this article is to investigate the possibility of deriving a type of Reynolds equation also for non-Newtonian fluids, using the balance of linear momentum. By considering power-law fluids we demonstrate that it is not possible for shear-driven flows, whereas it is feasible for pressure-driven flows. Additionally, we demonstrate that in the full 3D model, a normal stress boundary condition at the inlet/outlet implies a Dirichlet condition for the pressure in the Reynolds equation associated with pressure-driven flow. Furthermore, we establish that a Dirichlet condition for the velocity at the inlet/outlet in the 3D model results in a Neumann condition for the pressure in the Reynolds equation.
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| 30. |
- Almqvist, Andreas, et al.
(författare)
-
On lower-dimensional models in lubrication, Part A : Common misinterpretations and incorrect usage of the Reynolds equation
- 2021
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : Sage Publications. - 1350-6501 .- 2041-305X. ; 235:8, s. 1692-1702
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Tidskriftsartikel (refereegranskat)abstract
- Most of the problems in lubrication are studied within the context of Reynolds’ equation, which can be derived by writing the incompressible Navier-Stokes equation in a dimensionless form and neglecting terms which are small under the assumption that the lubricant film is very thin. Unfortunately, the Reynolds equation is often used even though the basic assumptions under which it is derived are not satisfied. One example is in the mathematical modelling of elastohydrodynamic lubrication (EHL). In the EHL regime, the pressure is so high that the viscosity changes by several orders of magnitude. This is taken into account by just replacing the constant viscosity in either the incompressible Navier-Stokes equation or the Reynolds equation by a viscosity-pressure relation. However, there are no available rigorous arguments which justify such an assumption. The main purpose of this two-part work is to investigate if such arguments exist or not. In Part A, we formulate a generalised form of the Navier-Stokes equation for piezo-viscous incompressible fluids. By dimensional analysis of this equation we, thereafter, show that it is not possible to obtain the Reynolds equation, where the constant viscosity is replaced with a viscosity-pressure relation, by just neglecting terms which are small under the assumption that the lubricant film is very thin. The reason is that the lone assumption that the fluid film is very thin is not enough to neglect the terms, in the generalised Navier-Stokes equation, which are related to the body forces and the inertia. However, we analysed the coefficients in front of these (remaining) terms and provided arguments for when they may be neglected. In Part B, we present an alternative method to derive a lower-dimensional model, which is based on asymptotic analysis of the generalised Navier-Stokes equation as the film thickness goes to zero.
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| 31. |
- Almqvist, Andreas, et al.
(författare)
-
On lower-dimensional models in lubrication, Part B : Derivation of a Reynolds type of equation for incompressible piezo-viscous fluids
- 2021
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : Sage Publications. - 1350-6501 .- 2041-305X. ; 235:8, s. 1703-1718
-
Tidskriftsartikel (refereegranskat)abstract
- The Reynolds equation is a lower-dimensional model for the pressure in a fluid confined between two adjacent surfaces that move relative to each other. It was originally derived under the assumption that the fluid is incompressible and has constant viscosity. In the existing literature, the lower-dimensional Reynolds equation is often employed as a model for the thin films, which lubricates interfaces in various machine components. For example, in the modelling of elastohydrodynamic lubrication (EHL) in gears and bearings, the pressure dependence of the viscosity is often considered by just replacing the constant viscosity in the Reynolds equation with a given viscosity-pressure relation. The arguments to justify this are heuristic, and in many cases, it is taken for granted that you can do so. This motivated us to make an attempt to formulate and present a rigorous derivation of a lower-dimensional model for the pressure when the fluid has pressure-dependent viscosity. The results of our study are presented in two parts. In Part A, we showed that for incompressible and piezo-viscous fluids it is not possible to obtain a lower-dimensional model for the pressure by just assuming that the film thickness is thin, as it is for incompressible fluids with constant viscosity. Here, in Part B, we present a method for deriving lower-dimensional models of thin-film flow, where the fluid has a pressure-dependent viscosity. The main idea is to rescale the generalised Navier-Stokes equation, which we obtained in Part A based on theory for implicit constitutive relations, so that we can pass to the limit as the film thickness goes to zero. If the scaling is correct, then the limit problem can be used as the dimensionally reduced model for the flow and it is possible to derive a type of Reynolds equation for the pressure.
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| 32. |
- Almqvist, Andreas, et al.
(författare)
-
On lower-dimensional models of thin film flow, Part C: Derivation of a Reynolds type of equation for fluids with temperature and pressure dependent viscosity
- 2023
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : Sage. - 1350-6501 .- 2041-305X. ; 237:3, s. 514-526
-
Tidskriftsartikel (refereegranskat)abstract
- This paper constitutes the third part of a series of works on lower-dimensional models in lubrication. In Part A, it was shown that implicit constitutive theory must be used in the modelling of incompressible fluids with pressure-dependent viscosity and that it is not possible to obtain a lower-dimensional model for the pressure just by letting the film thickness go to zero, as in the proof of the classical Reynolds equation. In Part B, a new method for deriving lower-dimensional models of thin-film flow of fluids with pressure-dependent viscosity was presented. Here, in Part C, we also incorporate the energy equation so as to include fluids with both temperature and pressure dependent viscosity. By asymptotic analysis of this system, as the film thickness goes to zero, we derive a simplified model of the flow. We also carry out an asymptotic analysis of the boundary condition, in the case where the normal stress is specified on one part of the boundary and the velocity on the remaining part.
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| 33. |
- Almqvist, Andreas, et al.
(författare)
-
Reiterated homogenization applied in hydrodynamic lubrication
- 2008
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - 1350-6501 .- 2041-305X. ; 222:7, s. 827-841
-
Tidskriftsartikel (refereegranskat)abstract
- This work is devoted to studying the combined effect that arises due to surface texture and surface roughness in hydrodynamic lubrication. An effective approach in tackling this problem is by using the theory of reiterated homogenization with three scales. In the numerical analysis of such problems, a very fine mesh is needed, suggesting some type of averaging. To this end, a general class of problems is studied that, e.g. includes the incompressible Reynolds problem in both artesian and cylindrical coordinate forms. To demonstrate the effectiveness of the method several numerical results are presented that clearly show the convergence of the deterministic solutions towards the homogenized solution.Moreover, the convergence of the friction force and the load carrying capacity of the lubricant film is also addressed in this paper. In conclusion, reiterated homogenization is a feasible mathematical tool that facilitates the analysis of this type of problem.
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| 34. |
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| 35. |
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| 36. |
- Almqvist, Andreas, et al.
(författare)
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Similarities and differences between the flow factor method by Patir and Cheng and homogenization
- 2011
-
Ingår i: Journal of tribology. - : ASME International. - 0742-4787 .- 1528-8897. ; 133:3, s. 031702-1
-
Tidskriftsartikel (refereegranskat)abstract
- Different averaging techniques have proved to be useful for analyzing the effects of surface roughness in hydrodynamic lubrication. This paper compares two of these averaging techniques, namely the flow factor method by Patir and Cheng (P&C) and homogenization. It has been rigorously proved by many authors that the homogenization method provides a correct solution for arbitrary roughness. In this work it is shown that the two methods coincide if and only if the roughness exhibits certain symmetries. Hence, homogenization is always the preferred method.
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| 37. |
- Almqvist, Andreas, et al.
(författare)
-
The homogenization process of the time dependent Reynolds equation describing compressible liquid flow
- 2007
-
Ingår i: Tribologia : Finnish Journal of Tribology. - 0780-2285. ; 26:4, s. 30-44
-
Tidskriftsartikel (refereegranskat)abstract
- To increase the hydrodynamic performance in different machine elements during lubrication, e.g. journal bearings and thrust bearings, it is important to understand the influence of surface roughness. In this connection one encounters different approaches commonly based on some form of the Reynolds equation. They may generally be divided into deterministic- and averaging- techniques. The former regards all surface roughness information and provides a detailed understanding of the local effects that arise. The latter method is suitable when investigating how the surface roughness affects performance of the machine element as a whole. Homogenization is a rigorous mathematical concept that when applied to a certain problem may be thought of as an averaging technique also providing information about local effects. In this work the compressible time dependent Reynolds equation is homogenized. Related problems have recently been analyzed by homogenization techniques under various assumptions. In the present paper the compressibility is modeled assuming a constant lubricant bulk modulus. The formal method of multiple scale expansion is used to derive a so-called homogenized equation and a numerical solution method to solve both the deterministic problem and the homogenized problem is implemented. The numerical results clearly show that the solution of the homogenized equation is a suitable approximation to the solution of the deterministic problem. It is also demonstrated that for small values of the roughness wavelength, the homogenization technique is superior, since the solution of the deterministic problem requires an extremely fine discretization mesh. More over, the solution of the time dependent homogenized problem may in some cases be reduced to solve a stationary problem that facilitates the solution process and interpretation of results.
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| 38. |
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| 39. |
- Almqvist, Andreas, et al.
(författare)
-
Variational bounds applied to unstationary hydrodynamic lubrication
- 2008
-
Ingår i: International Journal of Engineering Science. - : Elsevier BV. - 0020-7225 .- 1879-2197. ; 46:9, s. 891-906
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to the effects of surface roughness in hydrodynamic lubrication. The numerical analysis of such problems requires a very fine mesh to resolve the surface roughness, hence it is often necessary to do some type of averaging. Previously, homogenization (a rigorous form of averaging) has been successfully applied to Reynolds type differential equations. More recently, the idea of finding upper and lower bounds on the effective behavior, obtained by homogenization, was applied for the first time in tribology. In these pioneering works, it has been assumed that only one surface is rough. In this paper we develop these results to include the unstationary case where both surfaces may be rough. More precisely, we first use multiple-scale expansion to obtain a homogenization result for a class of variational problems including the variational formulation associated with the unstationary Reynolds equation. Thereafter, we derive lower and upper bounds corresponding to the homogenized (averaged) variational problem. The bounds reduce the numerical analysis, in that one only needs to solve two smooth problems, i.e. no local scale has to be considered. Finally, we present several examples, where it is shown that the bounds can be used to estimate the effects of surface roughness with very high accuracy.
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| 40. |
- Baramidze, Lasha, et al.
(författare)
-
Sharp Hp- Lptype inequalities of weighted maximal operators of Vilenkin-Nörlund means and its applications
- 2016
-
Ingår i: Journal of inequalities and applications. - : Springer Science and Business Media LLC. - 1025-5834 .- 1029-242X. ; :1
-
Tidskriftsartikel (refereegranskat)abstract
- We prove and discuss some new Hp-Lptype inequalities of weighted maximal operators of Vilenkin-Nörlund means with monotone coefficients. It is also proved that these inequalities are the best possible in a special sense. We also apply these results to prove strong summability for such Vilenkin-Nörlund means. As applications, both some well-known and new results are pointed out
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| 41. |
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| 42. |
- Berhane, Yemane, et al.
(författare)
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A rural Ethiopian population undergoing epidemiological transition over a generation : Butajira from 1987 to 2004
- 2008
-
Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 36:4, s. 436-441
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: To describe the epidemiological development of a rural Ethiopian population from 1987 to 2004 in terms of mortality and associated sociodemographic factors. Methods: A rural population comprising 10 communities was defined in 1987 and has since been followed by means of regular household visits. After an initial census, births, deaths and migration events were recorded, together with key background factors, on an open cohort basis. Over 97,000 individuals were observed during a total of over 700,000 person years. Results: The initial population of 28,614 increased by an average of 3.64% annually to 54,426 from 1987 to 2004, and also grew older on average. Birth and mortality rates fell, but were still subject to short-term variation due to external factors. Overall mortality was 13.5 per 1000 person years. Increasing mortality in some adult age groups was consistent with increasing AIDS-related deaths, but a new local hospital in 2002 may have contributed to later falls in overall mortality. Sex, age group, time period, literacy, water source, house ownership and distance to town were all significantly associated with mortality differentials. Conclusions: This population has undergone a complex epidemiological transition during a generation. Detailed long-term surveillance of this kind is essential for describing such processes. Many factors that significantly affect mortality cannot be directly controlled by the health sector and will only improve with general development.
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| 43. |
- Berhane, Yemane, et al.
(författare)
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Gender, literacy, and survival among Ethiopian adults, 1987 - 96.
- 2002
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Ingår i: Bulletin of the World Health Organization. - 0042-9686 .- 1564-0604. ; 80:9, s. 714-20
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Tidskriftsartikel (refereegranskat)abstract
- Special attention should be given to raising literacy levels among rural women with a view to improving their survival.
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| 44. |
- Botvinik-Nezer, Rotem, et al.
(författare)
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Variability in the analysis of a single neuroimaging dataset by many teams
- 2020
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 582, s. 84-88
-
Tidskriftsartikel (refereegranskat)abstract
- Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses(1). The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset(2-5). Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed. The results obtained by seventy different teams analysing the same functional magnetic resonance imaging dataset show substantial variation, highlighting the influence of analytical choices and the importance of sharing workflows publicly and performing multiple analyses.
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| 45. |
- Broekman, Maarten J. E., et al.
(författare)
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Evaluating expert-based habitat suitability information of terrestrial mammals with GPS-tracking data
- 2022
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 31:8, s. 1526-1541
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Macroecological studies that require habitat suitability data for many species often derive this information from expert opinion. However, expert-based information is inherently subjective and thus prone to errors. The increasing availability of GPS tracking data offers opportunities to evaluate and supplement expert-based information with detailed empirical evidence. Here, we compared expert-based habitat suitability information from the International Union for Conservation of Nature (IUCN) with habitat suitability information derived from GPS-tracking data of 1,498 individuals from 49 mammal species.Location: Worldwide.Time period: 1998-2021.Major taxa studied: Forty-nine terrestrial mammal species.Methods: Using GPS data, we estimated two measures of habitat suitability for each individual animal: proportional habitat use (proportion of GPS locations within a habitat type), and selection ratio (habitat use relative to its availability). For each individual we then evaluated whether the GPS-based habitat suitability measures were in agreement with the IUCN data. To that end, we calculated the probability that the ranking of empirical habitat suitability measures was in agreement with IUCN's classification into suitable, marginal and unsuitable habitat types.Results: IUCN habitat suitability data were in accordance with the GPS data (> 95% probability of agreement) for 33 out of 49 species based on proportional habitat use estimates and for 25 out of 49 species based on selection ratios. In addition, 37 and 34 species had a > 50% probability of agreement based on proportional habitat use and selection ratios, respectively.Main conclusions: We show how GPS-tracking data can be used to evaluate IUCN habitat suitability data. Our findings indicate that for the majority of species included in this study, it is appropriate to use IUCN habitat suitability data in macroecological studies. Furthermore, we show that GPS-tracking data can be used to identify and prioritize species and habitat types for re-evaluation of IUCN habitat suitability data.
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| 46. |
- Bunzli, Samantha, et al.
(författare)
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Placebo Surgery Controlled Trials : Do They Achieve What They Set Out To Do? A Systematic Review
- 2021
-
Ingår i: Annals of Surgery. - 1528-1140. ; 273:6, s. 1102-1107
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To explore whether placebo surgery controlled trials achieve what they set out to do by investigating discrepancy between projected and actual design aspects of trials identified through systematic review methods. SUMMARY BACKGROUND: Interest in placebo surgery controlled trials is growing in response to concerns regarding unnecessary surgery and the societal cost of low-value healthcare. As questions about the justifiability of using placebo controls in surgery have been addressed, attention is now being paid to more practical concerns. METHODS: Six databases were searched from inception - May 2020 (MEDLINE, Embase, Emcare, APA PsycInfo, CINAHL, Cochrane Library). Placebo surgery controlled trials with a published protocol were included. Three authors extracted "projected" design aspects from protocols and "actual" design aspects from main findings papers. Absolute and relative difference between projected and actual design aspects were presented for each trial. Trials were grouped according to whether they met their target sample size ("completed") and were concluded in a timely fashion. Pairs of authors assessed risk of bias. RESULTS: Of 24 trials with data available to analyse; 3 were completed and concluded within target timeframe; 10 were completed and concluded outside the target timeline; 4 were completed without clear target timeframes; 2 were incomplete and concluded within the target framework; 5 were incomplete and concluded outside the target timeline. Trials which reached the recruitment target underestimated trial duration by 88% and number of recruitment sites by 87%. CONCLUSIONS: Trialists need to factor additional time and sites into future placebo surgery controlled trials. A robust reporting framework of projected and actual trial design is imperative for trialists to learn from their predecessors. REVIEW REGISTRATION: PROSPERO (CRD42019133296).
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| 47. |
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| 48. |
- Burtseva, Evgeniya, 1988-
(författare)
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Operators and Inequalities in various Function Spaces and their Applications
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Licentiate thesis is devoted to the study of mapping properties of different operators (Hardy type, singular and potential) between various function spaces.The main body of the thesis consists of five papers and an introduction, which puts these papers into a more general frame.In paper A we prove the boundedness of the Riesz Fractional Integration Operator from a Generalized Morrey Space to a certain Orlicz-Morrey Space, which covers the Adams resultfor Morrey Spaces. We also give a generalization to the case of Weighted Riesz Fractional Integration Operators for a class of weights.In paper B we study the boundedness of the Cauchy Singular Integral Operator on curves in complex plane in Generalized Morrey Spaces. We also consider the weighted case with radial weights. We apply these results to the study of Fredholm properties of Singular Integral Operators in Weighted Generalized Morrey Spaces.In paper C we prove the boundedness of the Potential Operator in Weighted Generalized Morrey Spaces in terms of Matuszewska-Orlicz indices of weights and apply this result to the Hemholtz equation with a free term in such a space. We also give a short overview of some typical situations when Potential type Operators arise when solving PDEs.In paper D some new inequalities of Hardy type are proved. More exactly, the boundedness of multidimensional Weighted Hardy Operators in Hölder Spaces are proved in cases with and without compactification.In paper E the mapping properties are studied for Hardy type and Generalized Potential type Operators in Weighted Morrey type Spaces.
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| 49. |
- Byass, Peter, et al.
(författare)
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Lessons from History for Designing and Validating Epidemiological Surveillance in Uncounted Populations
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:8, s. e22897-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Due to scanty individual health data in low- and middle-income countries (LMICs), health planners often use imperfect data sources. Frequent national-level data are considered essential, even if their depth and quality are questionable. However, quality in-depth data from local sentinel populations may be better than scanty national data, if such local data can be considered as nationally representative. The difficulty is the lack of any theoretical or empirical basis for demonstrating that local data are representative where data on the wider population are unavailable. Thus these issues can only be explored empirically in a complete individual dataset at national and local levels, relating to a LMIC population profile. Methods and Findings: Swedish national data for 1925 were used, characterised by relatively high mortality, a low proportion of older people and substantial mortality due to infectious causes. Demographic and socioeconomic characteristics of Sweden then and LMICs now are very similar. Rates of livebirths, stillbirths, infant and cause-specific mortality were calculated at national and county levels. Results for six million people in 24 counties showed that most counties had overall mortality rates within 10% of the national level. Other rates by county were mostly within 20% of national levels. Maternal mortality represented too rare an event to give stable results at the county level. Conclusions: After excluding obviously outlying counties (capital city, island, remote areas), any one of the remaining 80% closely reflected the national situation in terms of key demographic and mortality parameters, each county representing approximately 5% of the national population. We conclude that this scenario would probably translate directly to about 40 LMICs with populations under 10 million, and to individual states or provinces within about 40 larger LMICs. Unsubstantiated claims that local sub-national population data are "unrepresentative" or "only local" should not therefore predominate over likely representativity.
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