Global ETD Search

11	FE Analysis of axial-bearing in large fans : FE analys av axialkullager i stora fläktar Hjalmarsson, Joel, Memic, Anes January 2010 (has links) Detta examensarbete har utförts på Fläktwoods AB i Växjö, som producerar stora axialfläktar för olika industriapplikationer. Syftet är att öka kunskapen om fettsmorda axiella kullager genom FE analyser. Projektet har genomförts i fem delsteg för att avgöra påverkan av en eller några få parametrar i taget. De studerade parametrarna är: elementstorlek, kontaktstyvhet, last, lagergeometri (dvs. oskulation), ickelinjär geometri och ickelinjära materialegenskaper (dvs. plasticitet). Slutsatsen är att elementstorleken bör väljas fint nog för att ge ett jämnt resultat men grovt nog för att beräkningstiden skal vara rimlig. Kontaktstyvheten har inte stor, men tydlig, inverkan på kontakttrycket och penetrationen. Förändringar av oskulationen leder till förändringar i kontaktellipsens form medan olika laster inte påverkar formen på ellipsen, utan snarare storleken. När det handlar om plasticitet är sträckgränsen den viktigaste faktorn att beakta. / This thesis project was carried out at Fläktwoods AB in Växjö who produces large axial fans for different industry applications. The purpose is to increase the knowledge of grease lubricated axial ball bearings through FE analyses. The project was executed into five sub steps to determine the influence of one or few parameters at a time. The studied parameters are: mesh density, contact stiffness, load, bearing geometry (i.e. osculation), geometrical nonlinearity and material nonlinearity (i.e. plasticity). It is concluded that the mesh density should be selected fine enough to give a smooth result but course enough to give a reasonable calculation time. The contact stiffness has not a major, but a clear, impact on the contact pressure and penetration. Changes of the osculation lead to changes of the contact ellipse shape and applying different load level does not affect the shape of the ellipse but rather the size. When dealing with plasticity the yield strength is the most important factor to take in consideration. Ansys axial ball bearings bearing geometry contact stiffness FEM Fläktwoods geometrical nonlinearity load material nonlinearity mesh density normal stiffness factor osculation plasticity thrust ball bearing Ansys axialkullager elementstorlek FEM Fläktwoods ickelinjär geometri last ickelinjära materialegenskaper kontaktstyvhet lagergeometri oskulation plasticitet
12	Hybridhotbilden mot Sverige : En kvalitativ försvars- och säkerhetspolitisk innehållsanalys om hybridhot / The Hybrid Threat Scenario in Sweden : A qualitative defense and security policy content analysis on hybrid threats Nilsson, Pierre January 2021 (has links) With a changing state of security in Europe, defined by instability and unpredictability, the use of hybrid threats presents itself as an international security challenge. Characterized by the antagonistic use of both conventional and unconventional means, the hybrid threat actor coordinates these means in an attempt achieve specific goals, often under a guise of ambiguity. The complexity of hybrid threats deepens as advancing technology and globalisation enables the hybrid threat actor to use tools not only bound by geographical constraints, but tools that makes use the cyber domain and the constant flow of information. Tools ranging from military, political, economic, civil, and informational tools can, in various combinations, take advantage of specific vulnerabilities in the target state. Identifying and countering such a wide range of multifaceted tools provides a difficult task for most states. This study aims to investigate the Swedish hybrid threat scenario by focusing on the authorities concerned with national defence and security and their identification of potential hybrid threats that faces Sweden. For countering such hybrid threats the study investigates the highly topical Swedish defence act 2021-2025. Its focus being on investigating potential goals, strategies and abilities for building resilience and countermeasures regarding hybrid threats. The study finds that Sweden is subject to the use of hybrid threats by antagonistic state actors, mainly Russia and China. Tools being used against Sweden include for example espionage, strategic acquisition of businesses and real estate, disinformation, and cyberattacks. For countering these threats, the study fails to find a specific set of goals for hybrid threat defence. Instead, the study finds a broad effort to strengthen national defence and security including among others the rebuilding of the Total Defence, founding of a national cybersecurity centrum, instituting an agency for psychological defence as well as lifting the perspective of hybrid threat among relevant national agencies. hybrid threats hybrid warfare Sweden Russia China national security Hybridhot hybridangrepp hybridkrig ickelinjär krigföring säkerhetspolitik försvarspolitik Sverige Ryssland Kina
13	Precision Tailoring Cooling Systems using Linear Regression / Precisionsanpassning av Kylsystem med Linjär Regression Bjelle, Kajsa, Cui, Ida January 2021 (has links) This bachelor thesis is written for KTH Royal Institute of Technology and Ymer Technology AB. It examines the friction factor associated with the pressure drop in wavy-fin heat exchangers. Previous studies have used a nonlinear approach for determining the regression coefficients. This study introduces a linearizing transform that solves the issues of finding non-optimal parameter values stemming from the current nonlinear approach. The linearization also drastically improves the computational time. A final model explaining 95.4\% of the variance in the data is presented. Methods for avoiding overfitting, detecting outliers and hidden extrapolation are presented and used to evaluate the model. The implications of the mathematical results on improving profit, competitiveness, and customer relationships are analyzed in the second part of the report with a qualitative approach. / Denna kandidatuppsats är skrivet vid Kungliga Tekniska Högskolan och Ymer Technology AB. Det undersöker den friktionsfaktor som associeras med tryckfallet i kylare med wavy-fins. Tidigare studier har använt ett ickelinjärt tillvägagångssätt för att bestämma regressionskoefficienterna. Denna studie introducerar en linjäriserande transform som löser problemen med att hitta icke-optimala paramatervärden, som härstammar från tidigare icke-linjära tillvägagångsätt. Linjäriseringen visar sig även förbättra beräkningstiden drastiskt. En slutgiltig modell som förklarar 95\% av variansen i datan presenteras. Metoder för att undvika overfitting, identifiera outliers, och undvika att falla offer för gömd extrapolation presenteras och används för att evaluera modellen. De matematiska resultatens implikationer för Ymer med avseende på vinst, konkurrenskraft och kundrelationer, analyseras i den andra delen av rapporten med en kvalitativ ansats. Regression analysis nonlinear regression linear regression Levenberg-Marquardt applied mathematics friction factor wavy fin bachelor thesis Regressionsanalys ickelinjär regression linjär regression Levenberg-Marquardt tillämpad matematik friktionsfaktor wavy fin kandidatexamensarbete Probability Theory and Statistics Sannolikhetsteori och statistik
14	Towards topology-aware Variational Auto-Encoders : from InvMap-VAE to Witness Simplicial VAE / Mot topologimedvetna Variations Autokodare (VAE) : från InvMap-VAE till Witness Simplicial VAE Medbouhi, Aniss Aiman January 2022 (has links) Variational Auto-Encoders (VAEs) are one of the most famous deep generative models. After showing that standard VAEs may not preserve the topology, that is the shape of the data, between the input and the latent space, we tried to modify them so that the topology is preserved. This would help in particular for performing interpolations in the latent space. Our main contribution is two folds. Firstly, we propose successfully the InvMap-VAE which is a simple way to turn any dimensionality reduction technique, given its embedding, into a generative model within a VAE framework providing an inverse mapping, with all the advantages that this implies. Secondly, we propose the Witness Simplicial VAE as an extension of the Simplicial Auto-Encoder to the variational setup using a Witness Complex for computing a simplicial regularization. The Witness Simplicial VAE is independent of any dimensionality reduction technique and seems to better preserve the persistent Betti numbers of a data set than a standard VAE, although it would still need some further improvements. Finally, the two first chapters of this master thesis can also be used as an introduction to Topological Data Analysis, General Topology and Computational Topology (or Algorithmic Topology), for any machine learning student, engineer or researcher interested in these areas with no background in topology. / Variations autokodare (VAE) är en av de mest kända djupa generativa modellerna. Efter att ha visat att standard VAE inte nödvändigtvis bevarar topologiska egenskaper, det vill säga formen på datan, mellan inmatningsdatan och det latenta rummet, försökte vi modifiera den så att topologin är bevarad. Det här skulle i synnerhet underlätta när man genomför interpolering i det latenta rummet. Denna avhandling består av två centrala bidrag. I första hand så utvecklar vi InvMap-VAE, som är en enkel metod att omvandla vilken metod inom dimensionalitetsreducering, givet dess inbäddning, till en generativ modell inom VAE ramverket, vilket ger en invers avbildning och dess tillhörande fördelar. För det andra så presenterar vi Witness Simplicial VAE som en förlängning av en Simplicial Auto-Encoder till dess variationella variant genom att använda ett vittneskomplex för att beräkna en simpliciel regularisering. Witness Simplicial VAE är oberoende av dimensionalitets reducerings teknik och verkar bättre bevara Betti-nummer av ett dataset än en vanlig VAE, även om det finns utrymme för förbättring. Slutligen så kan de första två kapitlena av detta examensarbete också användas som en introduktion till Topologisk Data Analys, Allmän Topologi och Beräkningstopologi (eller Algoritmisk Topologi) till vilken maskininlärnings student, ingenjör eller forskare som är intresserad av dessa ämnesområden men saknar bakgrund i topologi. Variational Auto-Encoder Nonlinear dimensionality reduction Generative model Inverse projection Computational topology Algorithmic topology Topological Data Analysis Data visualisation Unsupervised representation learning Topological machine learning Betti number Simplicial complex Witness complex Simplicial map Simplicial regularization. Variations autokodare Ickelinjär dimensionalitetsreducering Generativ modell Invers projektion Beräkningstopologi Algoritmisk topologi Topologisk Data Analys Datavisualisering Oövervakat representationsinlärning Topologisk maskininlärning Betti-nummer Simplicielt komplex Vittneskomplex Simpliciel avbildning Simpliciel regularisering. Computer Sciences Datavetenskap (datalogi)
15	"Do not fade, do not wither, do not grow old" : En adaptionsanalys av tid och rum i Sally Potters Orlando (1992) / "Do Not Fade, Do Not Wither, Do Not Grow Old" : An Analysis of Time and Space in Sally Potter's Film Adaptation Orlando (1992) Weber, Minon January 2021 (has links) For almost a century, Virginia Woolf has enchanted readers all over the world with her novel about the gender fluid and time travelling character Orlando. British director Sally Potter adapted Orlando into film in 1992, and her adaptation has since gained immense fame and a continuous presence in world cinema. Potter's Orlando has been the object of a great deal of scholarly interest. However, previous research has predominantly focused on questions of gender and sexuality. Considerably underdiscussed is the film's fascinating conception of time and space. This thesis therefore sets out to analyze Sally Potter's Orlando in order to demonstrate how time and space is shaped in the film. Theories developed by George Bluestone and André Bazin form the theoretical framework of this thesis. Through a close reading of the film, this thesis demonstrates that Potter establishes an unconventional temporality and spatiality through constructing a nonlinear, often contradictory temporality conveyed through contrasts between the organic and the fantastic, the real and the fictitious. Furthermore, the analysis finds that spatiality in Potter's Orlando is presented as multidimensional, allowing certain characters the possibility to inhabit a "fluid spatiality". Through presenting the past and the present as fused, Potter's Orlando can be understood through the optics of Bluestone's concept of "the flux of time" and Henri Bergsons la durée réelle. Simultaneously, breaks in the narrative presented through intertitles can be read as representing Bergsons idea of l'étendu, while also establishing a tangible spatiality. Adaptation Studies Adaptation Spatiotemporal Orlando Sally Potter Virginia Woolf George Bluestone André Bazin Henri Bergson flux time flux nonlinear nonlinear time unconventional temporality spatiality la durée réelle l'étendu chronological time psychological time Adaptionsstudier adaptionsanalys adaption temporalitet rumslighet Orlando Sally Potter Virginia Woolf George Bluestone André Bazin Henri Bergson tid rum ickelinjär tid okonventionell temporalitet okonventionell tidslighet la durée réelle l'étendu kronologisk tid psykologisk tid Studies on Film Filmvetenskap

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