Digital communication system for interaction is a part of the everyday life for the majority of people in the society. The Internet offers a space for counselling, support and/ or discussion. By using the Internet chat page familjeliv.se as a field research for a critical discourse analysis (CDA) following Norman Fairclough approach on the discussed and debated child fostering technique “timeout”, his theory and method enables a study on the construction of identity, roles and discourses. According to Fairclough, CDA does not stand on its own. It is depended on complementary theory(s) in the analysis of the social practice, for example theories on social interaction and power relations. Therefor Erving Goffmans theory on interaction and Anders Perssons comparative analysis of Goffman in the context of online interaction is applied with the company of Michele Foucault and Erich Fromm s theories on power relations. CDA origins from social constructionism and is therefor questioning the statement that there is an absolute objective truth. In that aspect, the theory of social constructionism is integrated and applied on the discussion of how and why certain constructions exist. The users of the forum position them selves for or against timeout and by using the method of CDA on the text and the discursive practice, ideologies can come to light in the social practice such as behaviourism. In certain senses, the discourse on Familejliv mirrors society’s disagreement on the effect and consequences of timeout and how to preserve children’s rights and not place the child at the risk of offensive abuse. The discourse of the child as in need of discipline also constitute and reflects the social learning theory aspects and behaviourism in society and social work through state parent support programs. On the topic of child fostering and the technique timeout, other discourses came to surface and when analysing the texts using the tools of CDA, an unequal power relation between mother and child became noticeable which shows how the parent use its natural power to supress the child verbally and physically which constructs discourses like  “the damn child”. With the same method the construction of  “the powerless and tired mother” is detected which can be explained by society’s anticipations on motherhood and can be traced to high expectation and therefor cause parental burnout.

Transmission Control Protocol (TCP) designed to deliver seamless and reliable end-to-end data transfer across unreliable networks works impeccably well in wired environment. In fact, TCP carries the around 90% of Internet traffic, so performance of Internet is largely based on the performance of TCP. However, end-to-end throughput in TCP degrades notably when operated in wireless networks. In wireless networks, due to high bit error rate and changing level of congestion, retransmission timeouts for packets lost in transmission is unavoidable. TCP misinterprets these random packet losses, due to the unpredictable nature of wireless environment, and the subsequent packet reordering as congestion and invokes congestion control by triggering fast retransmission and fast recovery, leading to underutilization of the network resources and affecting TCP performance critically. This thesis reviews existing approaches, details two proposed systems for better handling in networks with random loss and delay. Evaluation of the proposed systems is conducted using OPNET simulator by comparing against standard TCP variants and with varying number of hops.

The purpose of the present study was to examine the role of timeouts in competitive elite table tennis in relation to psychological momentum (PM). To that end, archival data from elite top-international matches (N= 48) was firstly examined to gather information on when timeouts are most taken, and whether these have any objective influence on subsequent performance (set outcome and ultimately match outcome). Secondly, similar archival data for Swedish League matches (N= 36) was examined and interviews with elite coaches from the highest Swedish league (N= 6) at these given matches were carried out to gain further knowledge and understanding on the role and use of timeouts in competitive elite table tennis. Findings showed that timeouts were mostly called following a sequence of three consecutive lost points; that is, coaches used timeouts to break negative PM. However, findings also showed that these given timeouts had no objective impact on neither set nor match outcomes; that is, sets and matches were ultimately lost. Future research examining the subjective coach-player experience revolving around timeouts is needed to comprehend potential ‘secondary’ purposes when calling timeouts and, subsequently, understand timeouts role in table tennis fully.

Les systèmes de stockage actuels font face à une explosion des données à gérer. A l'échelle actuelle, il serait illusoire d'imaginer une unique entité centralisée capable de stocker et de restituer les données de tous ses utilisateurs. Bien que du point de vue de l'utilisateur, le système de stockage apparaît tel un unique interlocuteur, son architecture sous-jacente est nécessairement devenue distribuée. En d'autres termes, le stockage n'est plus assigné à un équipement centralisé, mais est maintenant distribué parmi de multiples entités de stockage indépendantes, connectées via un réseau. Par conséquent, la bande passante inhérente à ce réseau devient une ressource à prendre en compte dans le design d'un système de stockage distribué. En effet, la bande passante d'un système est intrinsèquement une ressource limitée, qui doit être convenablement gérée de manière à éviter toute congestion du système. Cette thèse se propose d'optimiser l'utilisation de la bande passante dans les systèmes de stockage distribués, en limitant l'impact du churn et des défaillances. L'objectif est double, le but est d'une part, de maximiser la bande passante disponible pour les échanges de données, et d'une autre part de réduire la consommation de bande passante inhérente aux opérations de maintenance. Pour ce faire, nous présentons trois contributions distinctes. La première contribution présente une architecture pair-à-pair hybride qui tient compte de la topologie bas-niveau du réseau, c'est à dire la présence de gateways entre les utilisateurs et le système. La seconde contribution propose un mécanisme de timeout adaptatif au niveau utilisateur, basé sur une approche Bayésienne. La troisième contribution décrit un protocole permettant la réparation efficace de données encodées via des codes à effacement. Enfin, cette thèse se conclut sur la possibilité d'utiliser des techniques d'alignement d'interférence, communément utilisées en communication numérique afin d’accroître l'efficacité des protocoles de réparation de données encodées. / Modern storage systems have to face the surge of the amount of data to handle. At the current scale, it would be an illusion to believe that a single centralized storage device is able to store and retrieve all its users' data. While from the user's viewpoint the storage system remains a single interlocutor, its underlying architecture has become necessarily distributed. In others words, storage is no longer assigned to a centralized storage equipment, but is now distributed between multiple independent storage devices, connected via a network. Therefore, when designing networked storage systems, bandwidth should now be taken into account as a critical resource. In fact, the bandwidth of a system is intrinsically a limited resource which should be handled with care to avoid congestion. The focus of this thesis is to optimize the available bandwidth of distributed storage systems, lowering the impact of churn and failures. The objective is twofold, on the one hand the purpose is to increase the available bandwidth for data exchanges and on the other hand, to decrease the amount of bandwidth consumed by maintenance. We present three distinct contributions in this manuscript. The first contribution of this thesis presents an hybrid peer-to-peer architecture taking into account the low level topology of the network i.e., the presence of gateways between the system and the users. The second contribution proposes an adaptive and user-level timeout mechanism, based on a Bayesian approach. The third contribution describes a repair protocol especially designed for erasure-coded stored data. Finally, this thesis concludes on the possibility of employing interference alignment techniques in order to increase the efficiency of repair protocols especially designed for encoded data.

<p>The Transmission Control Protocol (TCP) has been the dominant transport protocol in the Internet for many years. One of the reasons to this is that TCP employs congestion control mechanisms which prevent the Internet from being overloaded. Although TCP's congestion control has evolved during almost twenty years, the area is still an active research area since the environments where TCP are employed keep on changing. One of the congestion control mechanisms that TCP uses is fast retransmit, which allows for fast retransmission of data that has been lost in the network. Although this mechanism provides the most effective way of retransmitting lost data, it can not always be employed by TCP due to restrictions in the TCP specification.</p><p>The primary goal of this work was to investigate when fast retransmit inhibitions occur, and how much they affect the performance of a TCP flow. In order to achieve this goal a large series of practical experiments were conducted on a real TCP implementation.</p><p>The result showed that fast retransmit inhibitions existed, in the end of TCP flows, and that the increase in total transmission time could be as much as 301% when a loss were introduced at a fast retransmit inhibited position in the flow. Even though this increase was large for all of the experiments, ranging from 16-301%, the average performance loss, due to an arbitrary placed loss, was not that severe. Because fast retransmit was inhibited in fewer positions of a TCP flow than it was employed, the average increase of the transmission time due to these inhibitions was relatively small, ranging from 0,3-20,4%.</p>

Transmission Control Protocol (TCP) designed to deliver seamless and reliable end-to-end data transfer across unreliable networks works impeccably well in wired environment. In fact, TCP carries the around 90% of Internet traffic, so performance of Internet is largely based on the performance of TCP. However, end-to-end throughput in TCP degrades notably when operated in wireless networks. In wireless networks, due to high bit error rate and changing level of congestion, retransmission timeouts for packets lost in transmission is unavoidable. TCP misinterprets these random packet losses, due to the unpredictable nature of wireless environment, and the subsequent packet reordering as congestion and invokes congestion control by triggering fast retransmission and fast recovery, leading to underutilization of the network resources and affecting TCP performance critically. This thesis reviews existing approaches, details two proposed systems for better handling in networks with random loss and delay. Evaluation of the proposed systems is conducted using OPNET simulator by comparing against standard TCP variants and with varying number of hops.

Les systèmes de stockage actuels font face à une explosion des données à gérer. A l'échelle actuelle, il serait illusoire d'imaginer une unique entité centralisée capable de stocker et de restituer les données de tous ses utilisateurs. Bien que du point de vue de l'utilisateur, le système de stockage apparaît tel un unique interlocuteur, son architecture sous-jacente est nécessairement devenue distribuée. En d'autres termes, le stockage n'est plus assigné à un équipement centralisé, mais est maintenant distribué parmi de multiples entités de stockage indépendantes, connectées via un réseau. Par conséquent, la bande passante inhérente à ce réseau devient une ressource à prendre en compte dans le design d'un système de stockage distribué. En effet, la bande passante d'un système est intrinsèquement une ressource limitée, qui doit être convenablement gérée de manière à éviter toute congestion du système. Cette thèse se propose d'optimiser l'utilisation de la bande passante dans les systèmes de stockage distribués, en limitant l'impact du churn et des défaillances. L'objectif est double, le but est d'une part, de maximiser la bande passante disponible pour les échanges de données, et d'une autre part de réduire la consommation de bande passante inhérente aux opérations de maintenance. Pour ce faire, nous présentons trois contributions distinctes. La première contribution présente une architecture pair-à-pair hybride qui tient compte de la topologie bas-niveau du réseau, c'est à dire la présence de gateways entre les utilisateurs et le système. La seconde contribution propose un mécanisme de timeout adaptatif au niveau utilisateur, basé sur une approche Bayésienne. La troisième contribution décrit un protocole permettant la réparation efficace de données encodées via des codes à effacement. Enfin, cette thèse se conclut sur la possibilité d'utiliser des techniques d'alignement d'interférence, communément utilisées en communication numérique afin d'accroître l'efficacité des protocoles de réparation de données encodées.

No description available.

Cellular networks are becoming more common, this introduces new challenges in dealing with their error prone nature. To improve end-to-end performance when the first link in the connection is wireless, an adaptive timeout based on network conditions is constructed. Relevant network factors are identified by examining data collected by a device located in a vehicle moving around in southern Sweden. Channel Quality Indicator (CQI) is shown to be the primary predictor of errors in the connection. In our datasets, a CQI index of 2 is a very good predictor of an error prone state. The collected data is split into training and evaluation data, the training data is used to construct a model. An adaptive timeout mechanism which uses this model is proposed, the mechanism is shown to be superior in all tested cases in the dataset compared to the optimal static counterpart. Reducing timeouts allows for applications to make new decisions based on new information faster, increasing responsiveness and user satisfaction.

The Transmission Control Protocol (TCP) has been the dominant transport protocol in the Internet for many years. One of the reasons to this is that TCP employs congestion control mechanisms which prevent the Internet from being overloaded. Although TCP's congestion control has evolved during almost twenty years, the area is still an active research area since the environments where TCP are employed keep on changing. One of the congestion control mechanisms that TCP uses is fast retransmit, which allows for fast retransmission of data that has been lost in the network. Although this mechanism provides the most effective way of retransmitting lost data, it can not always be employed by TCP due to restrictions in the TCP specification. The primary goal of this work was to investigate when fast retransmit inhibitions occur, and how much they affect the performance of a TCP flow. In order to achieve this goal a large series of practical experiments were conducted on a real TCP implementation. The result showed that fast retransmit inhibitions existed, in the end of TCP flows, and that the increase in total transmission time could be as much as 301% when a loss were introduced at a fast retransmit inhibited position in the flow. Even though this increase was large for all of the experiments, ranging from 16-301%, the average performance loss, due to an arbitrary placed loss, was not that severe. Because fast retransmit was inhibited in fewer positions of a TCP flow than it was employed, the average increase of the transmission time due to these inhibitions was relatively small, ranging from 0,3-20,4%.