Both the Visual Studies classroom, and the subject of Visual Studies itself, may open possibilities for solving problems in creative, challenging ways, that in other contexts might be regarded as disruptive. My study deals with transgressive behaviour in Visual Studies lessons, and how such behaviour is understood and received by teachers. It grows out of my own experience of incomprehension and unease around surprising work produced by students in my own Visual Studies workshops, and my hypothesis that behaviour like this is a form of resistance to control. I carry out a focus group interview with children that I know from workshops that I have been holding every Saturday for two years, using visual elicitation to encourage them to talk about Visual Studies lessons in general. My intention with the interview is to develop insights into why children do things that are different from their teacher’s expectations, with the aim of increasing my understanding of the work that children do in Visual Studies lessons, benefitting my own teaching practice, and being useful to colleagues. Ideas from other studies that have to do with imaginative play and creativity help me to conceive of children’s unexpected behaviour less as of a reaction against rules and authority, and more as a response to the possibilities of a Visual Studies workshop. The visual component of my study, where I install a ping-pong table in Konstfack’s Vita Havet gallery, can be regarded as a correlative to the written part. Through placing signs on the table, and changing how it is arranged, I draw attention to the way that it seems to be regarded differently from other objects placed in public spaces around Konstfack. The work is implicitly concerned with decisions about which objects, behaviours and people are regarded as acceptable in which spaces. As in the written study, through focussing on elements that don’t seem to fit in, my intention is to better understand the system as a whole.

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Le mode adjoint de la Différentiation Algorithmique (DA) est particulièrement intéressant pour le calcul des gradients. Cependant, ce mode utilise les valeurs intermédiaires de la simulation d'origine dans l'ordre inverse à un coût qui augmente avec la longueur de la simulation. La DA cherche des stratégies pour réduire ce coût, par exemple en profitant de la structure du programme donné. Dans ce travail, nous considérons d'une part le cas des boucles à point-fixe pour lesquels plusieurs auteurs ont proposé des stratégies adjointes adaptées. Parmi ces stratégies, nous choisissons celle de B. Christianson. Nous spécifions la méthode choisie et nous décrivons la manière dont nous l'avons implémentée dans l'outil de DA Tapenade. Les expériences sur une application de taille moyenne montrent une réduction importante de la consommation de mémoire. D'autre part, nous étudions le checkpointing dans le cas de programmes parallèles MPI avec des communications point-à-point. Nous proposons des techniques pour appliquer le checkpointing à ces programmes. Nous fournissons des éléments de preuve de correction de nos techniques et nous les expérimentons sur des codes représentatifs. Ce travail a été effectué dans le cadre du projet européen ``AboutFlow'' / The adjoint mode of Algorithmic Differentiation (AD) is particularly attractive for computing gradients. However, this mode needs to use the intermediate values of the original simulation in reverse order at a cost that increases with the length of the simulation. AD research looks for strategies to reduce this cost, for instance by taking advantage of the structure of the given program. In this work, we consider on one hand the frequent case of Fixed-Point loops for which several authors have proposed adapted adjoint strategies. Among these strategies, we select the one introduced by B. Christianson. We specify further the selected method and we describe the way we implemented it inside the AD tool Tapenade. Experiments on a medium-size application shows a major reduction of the memory needed to store trajectories. On the other hand, we study checkpointing in the case of MPI parallel programs with point-to-point communications. We propose techniques to apply checkpointing to these programs. We provide proof of correctness of our techniques and we experiment them on representative CFD codes

The workshop ¨Portierbare numerische Simulationen auf parallelen Architekturen¨ (¨Portable numerical simulations on parallel architectures¨) was organized by the Fac- ulty of Informatics/Professorship Computer Architecture at 18 April 1996 and held in the framework of the Sonderforschungsbereich (Joint Research Initiative) ¨Numerische Simulationen auf massiv parallelen Rechnern¨ (SFB 393) (¨Numerical simulations on massiv parallel computers¨) ( http://www.tu-chemnitz.de/~pester/sfb/sfb393.html ) The SFB 393 is funded by the German National Science Foundation (DFG). The purpose of the workshop was to bring together scientists using parallel computing to provide integrated discussions on portability issues, requirements and future devel- opments in implementing parallel software efficiently as well as portable on Clusters of Symmetric Multiprocessorsystems. I hope that the present paper gives the reader some helpful hints for further discussions in this field.

Many parallel applications from scientific computing use MPI collective communication operations to collect or distribute data. Since the execution times of these communication operations increase with the number of participating processors, scalability problems might occur. In this article, we show for different MPI implementations how the execution time of collective communication operations can be significantly improved by a restructuring based on orthogonal processor structures with two or more levels. As platform, we consider a dual Xeon cluster, a Beowulf cluster and a Cray T3E with different MPI implementations. We show that the execution time of operations like MPI Bcast or MPI Allgather can be reduced by 40% and 70% on the dual Xeon cluster and the Beowulf cluster. But also on a Cray T3E a significant improvement can be obtained by a careful selection of the processor groups. We demonstrate that the optimized communication operations can be used to reduce the execution time of data parallel implementations of complex application programs without any other change of the computation and communication structure. Furthermore, we investigate how the execution time of orthogonal realization can be modeled using runtime functions. In particular, we consider the modeling of two-phase realizations of communication operations. We present runtime functions for the modeling and verify that these runtime functions can predict the execution time both for communication operations in isolation and in the context of application programs.

Ericsson is one of the world's largest providers of communications technology and services. Reliable networks are important to deliver services that live up to customers' expectations. Tests are frequently run on Ericsson's systems in order to identify stability problems in their networks. These tests are not always completely reliable. The logs produced by these tests are gathered and analyzed to identify abnormal system behavior, especially abnormal behavior that the tests might not have caught. To automate this analysis process, a machine learning system, called the Awesome Automatic Log Analysis Application (AALAA), is used at Ericsson's Continuous Integration Infrastructure (CII)-department to identify problems within the large logs produced by automated Radio Base Station test loops and processes. AALAA is currently operable in two versions using different distributed cluster computing platforms: Apache Spark and Apache Hadoop. However, it needs improvements in its machine-to-machine communication to make this process more convenient to use. In this thesis, message communication has successfully been implemented in the AALAA system. The result is a message bus deployed in RabbitMQ that is able to successfully initiate model training and abnormal log identification through requests, and to handle a continuous flow of result updates from AALAA. / Ericsson är en av världens största leverantörer av kommunikationsteknologi och tjänster. Tillförlitliga nätverk är viktigt att tillhandahålla för att kunna leverera tjänster som lever upp till kundernas förväntningar. Tester körs därför ofta i Ericssons system med syfte att identifiera stabilitetsproblem som kan uppstå i nätverken. Dessa tester är inte alltid helt tillförlitliga, producerade testloggar samlas därför in och analyseras för att kunna identifiera onormalt beteende som testerna inte lyckats hitta. För att automatisera denna analysprocess har ett maskininlärningssystem utvecklats, Awesome Automatic Log Analysis Application (AALAA). Detta system används i Ericssons Continuous Integration Infrastructure (CII)-avdelning för att identifiera problem i stora loggar som producerats av automatiserade Radio Base Station tester. AALAA är för närvarande funktionellt i två olika versioner av distribuerad klusterberäkning, Apache Spark och Apache Hadoop, men behöver förbättringar i sin maskin-till-maskin-kommunikation för att göra dem enklare och effektivare att använda. I denna avhandling har meddelandekommunikation implementerats som kan kommunicera med flera olika moduler i AALAA. Resultatet är en meddelandebuss implementerad i RabbitMQ som kan initiera träning av modeller och identifiering av onormala loggar på begäran, samt hantera ett kontinuerligt flöde av resultatuppdateringar från pågående beräkningar.

Channel estimation is a fundamental task for exploiting the advantages of massive Multiple-Input Multiple-Output (MIMO) systems in fifth generation (5G) wireless technology. Channel estimates require solving sparse linear inverse problems that is usually performed with the Least Squares method, which brings low complexity but high mean squared error values. Thus other methods are usually needed to obtain better results, on top of Least Squares. Approximate Message Passing (AMP) is an efficient method for solving sparse linear inverse problems and recently a deep neural network approach to quickly solving such problems has been proposed, called Learned Approximate Message Passing (LAMP) [1], which estimates AMP with a fixed number iterations and learnable parameters. We formalize the channel estimation problem as a dictionary-based sparse linear inverse problem and investigate the applicability of LAMP to the task. We build upon the work of Borgerding et al. [1], providing a new loss function to minimize for our dictionary-based problem, we investigate empirically LAMP’s capabilities in various conditions: varying the dataset size, number of subcarriers, depth of network, and signal-to-noise ratio (SNR). We also propose a new network called Adaptive-LAMP which differs from LAMP for the introduction of a small neural network in each layer for estimating certain parameters instead of learning them. Experiments show that LAMP performs significantly better than AMP in terms of NMSE at low signal-to-noise ratio (SNR) levels and worse at high SNR levels. Interestingly, both proposed networks perform well at discovering active paths in cellular networks, paving the way for new approaches to the Channel Estimation problem. / Kanalbedömning är en grundläggande uppgift för att utnyttja fördelarna med massiva MIMO-system (Multiple-Input Multiple-Output) i femte generationens (5G) trådlösa teknik. Kanalskattningar kräver att man löser glesa linjära inversa problem som vanligtvis utförs med Least Squares-metoden, som ger låg komplexitet men höga medelvärden för det kvadratiska felet. Därför behövs vanligtvis andra metoder för att få bättre resultat, utöver Least Squares. Approximate Message Passing (AMP) är en effektiv metod för att lösa sparsamma linjära inversa problem, och nyligen har det föreslagits ett djupt neuralt nätverk för att snabbt lösa sådana problem, kallat Learned Approximate Message Passing (LAMP) [1], som uppskattar AMP med ett fast antal iterationer och inlärningsbara parametrar. Vi formaliserar kanalskattningsproblemet som ett ordboksbaserat sparse linjärt inversproblem och undersöker LAMP:s tillämplighet på uppgiften. Vi bygger på Borgerding et al. [1], som tillhandahåller en ny förlustfunktion att minimera för vårt ordboksbaserade problem, och vi undersöker empiriskt LAMP:s kapacitet under olika förhållanden: vi varierar datasetets storlek, antalet underbärare, nätverkets djup och signal-brusförhållandet (SNR). Vi föreslår också ett nytt nätverk kallat Adaptive-LAMP som skiljer sig från LAMP genom att det införs ett litet neuralt nätverk i varje lager för att uppskatta vissa parametrar i stället för att lära sig dem. Experiment visar att LAMP presterar betydligt bättre än AMP när det gäller NMSE vid låga signal-brusförhållande (SNR) och sämre vid höga SNR-nivåer. Intressant nog presterar båda de föreslagna nätverken bra när det gäller att upptäcka aktiva vägar i cellulära nätverk, vilket banar väg för nya metoder för kanalskattningsproblemet.

Despite the increasing interest in asylum seekers and refugees within the field of migration studies, there has been a gap in queer migrants’ research. This thesis is an attempt to investigate how migrant and gender identity are influencing each other and how they lead to experiences of both inclusion and exclusion in Swedish society, based on experiences of six queer migrants. In the first half, there is a presentation and criticism on migrant theories and previous studies related to the subjects of migration, gender and sexuality. There is also an attempt to defining queer and presenting how it intersects with migrant identity, through the stages of welcoming, adapting, developing, and maintaining oneself in a Swedish level. Finally, aspects of space and feelings of belonging are discussed further on. The second half of the thesis consists of a methodological part and the analysis of the interviews with queer migrants in Sweden, leading to further discussions, additional thoughts, and suggestions.

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