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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Escalabilidade Paralela de um Algoritmo de Migra??o Reversa no Tempo (RTM) Pr?-empilhamento / PARALLEL SCALABILITY OF A PRESTACK REVERSE TIME MIGRATION (RTM) ALGORITHM

Ros?rio, Desnes Augusto Nunes do 21 December 2012 (has links)
Made available in DSpace on 2014-12-17T14:56:09Z (GMT). No. of bitstreams: 1 DesnesANR_DISSERT.pdf: 3501359 bytes, checksum: 5155a508018af1e52dae20205b8f726b (MD5) Previous issue date: 2012-12-21 / The seismic method is of extreme importance in geophysics. Mainly associated with oil exploration, this line of research focuses most of all investment in this area. The acquisition, processing and interpretation of seismic data are the parts that instantiate a seismic study. Seismic processing in particular is focused on the imaging that represents the geological structures in subsurface. Seismic processing has evolved significantly in recent decades due to the demands of the oil industry, and also due to the technological advances of hardware that achieved higher storage and digital information processing capabilities, which enabled the development of more sophisticated processing algorithms such as the ones that use of parallel architectures. One of the most important steps in seismic processing is imaging. Migration of seismic data is one of the techniques used for imaging, with the goal of obtaining a seismic section image that represents the geological structures the most accurately and faithfully as possible. The result of migration is a 2D or 3D image which it is possible to identify faults and salt domes among other structures of interest, such as potential hydrocarbon reservoirs. However, a migration fulfilled with quality and accuracy may be a long time consuming process, due to the mathematical algorithm heuristics and the extensive amount of data inputs and outputs involved in this process, which may take days, weeks and even months of uninterrupted execution on the supercomputers, representing large computational and financial costs, that could derail the implementation of these methods. Aiming at performance improvement, this work conducted the core parallelization of a Reverse Time Migration (RTM) algorithm, using the parallel programming model Open Multi-Processing (OpenMP), due to the large computational effort required by this migration technique. Furthermore, analyzes such as speedup, efficiency were performed, and ultimately, the identification of the algorithmic scalability degree with respect to the technological advancement expected by future processors / A s?smica ? uma ?rea de extrema import?ncia na geof?sica. Associada principalmente ? explora??o de petr?leo, essa linha de pesquisa concentra boa parte de todo o investimento realizado nesta grande ?rea. A aquisi??o, o processamento e a interpreta??o dos dados s?smicos s?o as partes que comp?em um estudo s?smico. O processamento s?smico em especial tem como objetivo ? obten??o de uma imagem que represente as estruturas geol?gicas em subsuperf?cie. O processamento s?smico evoluiu significativamente nas ?ltimas d?cadas devido ?s demandas da ind?stria petrol?fera, e aos avan?os tecnol?gicos de hardware que proporcionaram maiores capacidades de armazenamento e processamento de informa??es digitais, que por sua vez possibilitaram o desenvolvimento de algoritmos de processamento mais sofisticados, tais como os que utilizam arquiteturas paralelas de processamento. Uma das etapas importantes contidas no processamento s?smico ? o imageamento. A migra??o ? uma das t?cnicas usadas para no imageamento com o objetivo de obter uma se??o s?smica que represente de forma mais precisa e fiel as estruturas geol?gicas. O resultado da migra??o ? uma imagem 2D ou 3D na qual ? poss?vel a identifica??o de falhas e domos salinos dentre outras estruturas de interesse, poss?veis reservat?rios de hidrocarbonetos. Entretanto, uma migra??o rica em qualidade e precis?o pode ser um processo demasiadamente longo, devido ?s heur?sticas matem?ticas do algoritmo e ? quantidade extensa de entradas e sa?das de dados envolvida neste processo, podendo levar dias, semanas e at? meses de execu??o ininterrupta em supercomputadores, o que representa grande custo computacional e financeiro, o que pode inviabilizar a aplica??o desses m?todos. Tendo como objetivo a melhoria de desempenho, este trabalho realizou a paraleliza??o do n?cleo de um algoritmo de Migra??o Reversa no Tempo (RTM - do ingl?s: Reverse Time Migration), utilizando o modelo de programa??o paralela OpenMP (do ingl?s: Open Multi-Processing), devido ao alto esfor?o computacional demandado por essa t?cnica de migra??o. Al?m disso, foram realizadas an?lises de desempenho tais como de speedup, efici?ncia, e, por fim, a identifica??o do grau de escalabilidade algor?tmica com rela??o ao avan?o tecnol?gico esperado para futuros processadores
352

Implementa??o paralela escal?vel e eficiente do algoritmo simplex padr?o em arquitetura multicore

Coutinho, Demetrios Ara?jo Magalh?es 24 January 2014 (has links)
Made available in DSpace on 2014-12-17T14:56:18Z (GMT). No. of bitstreams: 1 DemetriusAMC_DISSERT.pdf: 2429364 bytes, checksum: 57aaf24560c189720b218dbca0ef1a56 (MD5) Previous issue date: 2014-01-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work presents a scalable and efficient parallel implementation of the Standard Simplex algorithm in the multicore architecture to solve large scale linear programming problems. We present a general scheme explaining how each step of the standard Simplex algorithm was parallelized, indicating some important points of the parallel implementation. Performance analysis were conducted by comparing the sequential time using the Simplex tableau and the Simplex of the CPLEXR IBM. The experiments were executed on a shared memory machine with 24 cores. The scalability analysis was performed with problems of different dimensions, finding evidence that our parallel standard Simplex algorithm has a better parallel efficiency for problems with more variables than constraints. In comparison with CPLEXR , the proposed parallel algorithm achieved a efficiency of up to 16 times better / Este trabalho apresenta uma implementa??o paralela escal?vel e eficiente do algoritmo Simplex padr?o em arquitetura de processadores multicore para resolver problemas de programa??o linear de grande escala. Apresenta-se um esquema geral explicando como foi paralelizado cada passo do algoritmo simplex padr?o, apontando pontos importantes da implementa??o paralela. Foram realizadas an?lises de desempenho atrav?s da compara??o dos tempos sequenciais utilizando o Simplex tableau e Simplex do CPLEXR da IBM. Os experimentos foram realizados em uma m?quina de mem?ria compartilhada com 24 n?cleos. A an?lise de escalabilidade foi feita com problemas de diferentes dimens?es, encontrando evid?ncias de que a implementa??o paralela proposta do algoritmo simplex padr?o tem melhor efici?ncia paralela para problemas com mais vari?veis do que restri??es. Na compara??o com CPLEXR , o algoritmo proposto paralelo obteve uma efici?ncia de at? 16 vezes maior
353

Predictable and Scalable Medium Access Control for Vehicular Ad Hoc Networks

Sjöberg Bilstrup, Katrin January 2009 (has links)
This licentiate thesis work investigates two medium access control (MAC) methods, when used in traffic safety applications over vehicular ad hoc networks (VANETs). The MAC methods are carrier sense multiple access (CSMA), as specified by the leading standard for VANETs IEEE 802.11p, and self-organizing time-division multiple access (STDMA) as used by the leading standard for transponders on ships. All vehicles in traffic safety applications periodically broadcast cooperative awareness messages (CAMs). The CAM based data traffic implies requirements on a predictable, fair and scalable medium access mechanism. The investigated performance measures are channel access delay, number of consecutive packet drops and the distance between concurrently transmitting nodes. Performance is evaluated by computer simulations of a highway scenario in which all vehicles broadcast CAMs with different update rates and packet lengths. The obtained results show that nodes in a CSMA system can experience unbounded channel access delays and further that there is a significant difference between the best case and worst case channel access delay that a node could experience. In addition, with CSMA there is a very high probability that several concurrently transmitting nodes are located close to each other. This occurs when nodes start their listening periods at the same time or when nodes choose the same backoff value, which results in nodes starting to transmit at the same time instant. The CSMA algorithm is therefore both unpredictable and unfair besides the fact that it scales badly for broadcasted CAMs. STDMA, on the other hand, will always grant channel access for all packets before a predetermined time, regardless of the number of competing nodes. Therefore, the STDMA algorithm is predictable and fair. STDMA, using parameter settings that have been adapted to the vehicular environment, is shown to outperform CSMA when considering the performance measure distance between concurrently transmitting nodes. In CSMA the distance between concurrent transmissions is random, whereas STDMA uses the side information from the CAMs to properly schedule concurrent transmissions in space. The price paid for the superior performance of STDMA is the required network synchronization through a global navigation satellite system, e.g., GPS. That aside since STDMA was shown to be scalable, predictable and fair; it is an excellent candidate for use in VANETs when complex communication requirements from traffic safety applications should be met.
354

Optimisation des performances d'un système de transmission multimédia sans fil basé sur la réduction du PAPR dans des configurations réalistes / Performance optimization of wireless multimedia transmission system based on PAPR reduction in realiste configuration

Koussa, Badreddin 18 April 2014 (has links)
Ce travail de thèse s'intéresse à l'optimisation des performances de transmissions multimédias par une approche originale combinant des circuits radiofréquences, tel que l'am-plificateur de puissance et les distorsions du canal de transmission. Les signaux OFDM sont très sensibles aux non-linéarités de l'amplificateur à cause des fortes fluctuations du niveau du signal, caractérisées par le PAPR. Afin de réduire le PAPR, on propose tout d'abord d'améliorer la méthode TR en termes de rapidité de convergence et de réduction du PAPR, en comparant plusieurs algorithmes d'optimisation. On montre que l'algorithme du gradient con-jugué offre les meilleures performances tout en respectant les spécifications fréquentielles du standard IEEE 802.11a. Par la suite, la méthode TR est évaluée expérimentalement en pré-sence d'un amplificateur de puissance (SZP-2026Z) en utilisant un banc de mesures. On montre ainsi que la méthode TR permet une amélioration de la qualité de transmission. Cette amélioration peut être utilisée pour modifier le point de fonctionnement de l'amplificateur et per-mettre ainsi une réduction de 18 % de la puissance consommée. Les résultats expérimentaux ont conduit au choix d'un modèle réaliste d'amplificateur en considérant les effets mémoires. Ce dernier a été intégré dans une chaîne de simulation SISO comprenant également un modèle réaliste de canal de transmission. La chaîne décrite a permis d'évaluer les performances de la méthode TR dans des conditions de transmission réalistes. Enfin, on propose d'appliquer la méthode TR dans une chaîne MIMO-OFDM en boucle fermée dédiée à la transmission de contenus multimédias scalables dans un environnement réaliste, en utilisant le standard IEEE 802.11n. Cette étude présente une évaluation originale de l'impact de la méthode TR sur la qualité visuelle des images transmises, en prenant en compte le contenu multimédia, la non-linéarité de l'amplificateur et les distorsions apportées par le canal. / In this thesis, we are interested on the performances optimization of multimedia transmissions systems with an original contribution combining RF circuits' imperfections presented by the power amplifier (PA) nonlinearities and the transmission channel distortions. The studied system uses the OFDM technique which is the most widespread multicarrier modulation in recent radio communications systems. However, its major drawback is the high PAPR value, which degrades the transmission quality due to the PA nonlinearities. To reduce the PAPR, we first propose to improve the TR method in terms of convergence speed and PAPR reduction, by studying several optimization algorithms. We show that the conjugate gradient algorithm provides the best performance while respecting the frequency specifica-tions of the IEEE 802.11a standard. Thereafter, TR method has been evaluated experimentally in the presence of a commercial PA (SZP-2026Z) and using a measurement bench. It is shown that the TR method improves the quality of service (QoS), with 18% reduction in PA power consumption. The experimental study has resulted to choosing a realistic PA model consider-ing memory effects. This PA model has been integrated into a SISO simulation chain includ-ing also a realistic channel model. This chain is used to evaluate the TR method performances under realistic transmission conditions. Finally, we propose to apply the TR method in a closed-loop MIMO-OFDM chain dedicated to the transmission of scalable multimedia con-tent in a realistic context with the IEEE 802.1n standard. This study presents a new contribu-tion of the TR method evaluation to improve the visual quality of the JPWL transmitted imag-es, considering in the same time the multimedia content, the PA nonlinearity and the channel transmission distortions.
355

Transmission de multimédia dans les réseaux sans fil à qualité de service garantie / Multimedia transmission in wireless network with QoS guarantee

Kambou, Samy Jacques André 08 November 2016 (has links)
Cette thèse s'intéresse aux stratégies de transmission de contenu multimédia des réseaux sans fil. L'intérêt d'une stratégie repose sur sa capacité à gérer les ressources selon les objectifs des applications visées. On propose ainsi un schéma de transmission, qui garantit la qualité de service (QdS), quelles que soient les conditions du canal et suivant les spécificités du contenu multimédia. On exploite pour cela les diversités (spatiales, fréquentielles, etc.) du canal radio. A ce titre, l'association MIMO-OFDM apparaît comme une solution idéale pour accroitre les performances du système. On propose ainsi un système MIMO-OFDMA, qui intègre des stratégies inter-couches. Celles-ci se basent sur des techniques d'adaptation de lien pour régler dynamiquement les paramètres du système. On développe en premier un schéma inter-couches PHY 1 APPL, associé à un système MIMO-OFDM mono-utilisateur, qui transmet une vidéo H.264/SVC. L'adaptation de lien permet de définir le jeu de paramètres optimaux, qui minimise la distorsion de la vidéo reçue. On introduit ainsi une politique d'optimisation sous contraintes de puissance et de taux d'erreurs binaires. Pour tenir compte d'aspects de transmission réalistes, on propose un schéma inter-couches PHY/MAC, dédié à un système MIMO-OFDMA, multi-utilisateurs et multi-services. Ce dernier associe un algorithme d'ordonnancement, au paramétrage optimal, pour fournir au maximum d'utilisateurs des débits utiles respectant les exigences des services demandés. Enfin, on combine les deux premières solutions pour définir les paramètres optimaux minimisant la distorsion de la vidéo reçue par utilisateur, tout en garantissant la QdS des autres services. / This thesis focuses on the transmission strategies of the multimedia content in wireless networks. The advantage of a such strategy is its ability to manage the resources, according to the objectives of the targeted applications. We propose a transmission scheme, which guarantees the quality of service (QoS), depending on the channel state information and on the multimedia content specifications. We take advantage of the radio channel diversities (spatial, frequency, etc.). ln fact, the association of MIMO and OFDM techniques appears as effective solution to increase the system performance. For this reason, we propose a MIMO-OFDMA system, which considers cross-layer srtategies based on link adaptation schemes to dynamically adjust the system parameters. Firstly, we develop a PHY/APPL cross-layer strategy, dedicated to a single user of a MIMO-OFDMA system, which transmits an H.264/SVC video. The Iink adaptation scheme allows to define the optimum parameters, which minimize the end-ta-end video distortion by using an optimization algorithm under power and bit error rate constraints. To consider the realistic transmission aspects, we propose a PHY/MAC cross-layer strategy, dedicated to a multi-user, multi-service, MIMOOFDMA system. This scheme combines a scheduling policy with optimal parameterization to provide a satisfied troughput to a maximum number of users, acheiving the required services. Finally, the first two solutions are combined to determine the optimal parameters which minimize the end-ta-end distortion of the received video by user, and also acheive QoS requirements of the other services.
356

UM SISTEMA DE GERENCIAMENTO INTEGRADO E AUTOMATIZADO DE SERVIÇOS E COMPUTADORES DE REDES LOCAIS / An Integrated and Automated Network Management System for Services and Computers of Local Networks

Kreutz, Diego Luis 30 March 2005 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / The management of computer networks is an area that demands competence, creativeness, imagination, action, observation, autonomy and a lot of work. Even today it is still an area with a lack of tools and professionals qualified to the management of the most diverse administrative domains. In this context, this work describes the project and development of an integrated, dynamic and automated system that is able to simplify and reduce the time required by for many daily tasks of network administrators. The proposed system can also be used as a way of integrationg existing management tools, making use of their resources and functionalities. The results validate and show the appliance of the system. A prototype of the system was developed, that could already be applied to automate many administrative tasks of computer networks. / Gerenciamento de redes de computadores é uma área que exige competência, criatividade, imaginação, ação, observação, autonomia e muito trabalho. Apesar de anos de investimentos realizados nessa área, ainda continua sendo uma área com carência de ferramentas e profissionais qualificados para o gerenciamento dos mais diversos domínios administrativos. Neste contexto, este trabalho descreve o projeto e desenvolvimento de um sistema integrado, dinâmico e automatizado capaz de simplificar e agilizar várias tarefas do dia-a-dia de administradores de redes.O sistema se propõe também a ser uma forma de integração entre ferramentas de gerenciamento existentes, tanto estendendo seus recursos quanto suas funcionalidades. Os resultados demonstram a validade e aplicabilidade do sistema. Foi desenvolvido um protótipo do sistema, que já pôde ser aplicado em redes de computadores para a automatização de várias tarefas administrativas.
357

Enhancing security and scalability of Virtual Private LAN Services

Liyanage, M. (Madhusanka) 21 November 2016 (has links)
Abstract Ethernet based VPLS (Virtual Private LAN Service) is a transparent, protocol independent, multipoint L2VPN (Layer 2 Virtual Private Network) mechanism to interconnect remote customer sites over IP (Internet Protocol) or MPLS (Multiprotocol Label Switching) based provider networks. VPLS networks are now becoming attractive in many Enterprise applications, such as DCI (data center interconnect), voice over IP (VoIP) and videoconferencing services due to their simple, protocol-independent and cost efficient operation. However, these new VPLS applications demand additional requirements, such as elevated security, enhanced scalability, optimum utilization of network resources and further reduction in operational costs. Hence, the motivation of this thesis is to develop secure and scalable VPLS architectures for future communication networks. First, a scalable secure flat-VPLS architecture is proposed based on a Host Identity Protocol (HIP). It contains a session key-based security mechanism and an efficient broadcast mechanism that increase the forwarding and security plane scalability of VPLS networks. Second, a secure hierarchical-VPLS architecture is proposed to achieve control plane scalability. A novel encrypted label-based secure frame forwarding mechanism is designed to transport L2 frames over a hierarchical VPLS network. Third, a novel Distributed Spanning Tree Protocol (DSTP) is designed to maintain a loop free Ethernet network over a VPLS network. With DSTP it is proposed to run a modified STP (Spanning Tree Protocol) instance in each remote segment of the VPLS network. In addition, two Redundancy Identification Mechanisms (RIMs) termed Customer Associated RIMs (CARIM) and Provider Associated RIMs (PARIM) are used to mitigate the impact of invisible loops in the provider network. Lastly, a novel SDN (Software Defined Networking) based VPLS (Soft-VPLS) architecture is designed to overcome tunnel management limitations in legacy secure VPLS architectures. Moreover, three new mechanisms are proposed to improve the performance of legacy tunnel management functions: 1) A dynamic tunnel establishment mechanism, 2) a tunnel resumption mechanism and 3) a fast transmission mechanism. The proposed architecture utilizes a centralized controller to command VPLS tunnel establishment based on real-time network behavior. Hence, the results of the thesis will help for more secure, scalable and efficient system design and development of VPLS networks. It will also help to optimize the utilization of network resources and further reduction in operational costs of future VPLS networks. / Tiivistelmä Ethernet-pohjainen VPLS (Virtual Private LAN Service) on läpinäkyvä, protokollasta riippumaton monipisteverkkomekanismi (Layer 2 Virtual Private Network, L2VPN), jolla yhdistetään asiakkaan etäkohteet IP (Internet Protocol)- tai MPLS (Multiprotocol Label Switching) -yhteyskäytäntöön pohjautuvien palveluntarjoajan verkkojen kautta. VPLS-verkoista on yksinkertaisen protokollasta riippumattoman ja kustannustehokkaan toimintatapansa ansiosta tullut kiinnostavia monien yrityssovellusten kannalta. Tällaisia sovelluksia ovat esimerkiksi DCI (Data Center Interconnect), VoIP (Voice over IP) ja videoneuvottelupalvelut. Uusilta VPLS-sovelluksilta vaaditaan kuitenkin uusia asioita, kuten parempaa tietoturvaa ja skaalautuvuutta, optimaalista verkkoresurssien hyödyntämistä ja käyttökustannusten pienentämistä entisestään. Tämän väitöskirjan tarkoituksena onkin kehittää turvallisia ja skaalautuvia VPLS-arkkitehtuureja tulevaisuuden tietoliikenneverkoille. Ensin väitöskirjassa esitellään skaalautuva ja turvallinen flat-VPLS-arkkitehtuuri, joka perustuu Host Identity Protocol (HIP) -protokollaan. Seuraavaksi käsitellään istuntoavaimiin perustuvaa tietoturvamekanismia ja tehokasta lähetysmekanismia, joka parantaa VPLS-verkkojen edelleenlähetyksen ja tietoturvatason skaalautuvuutta. Tämän jälkeen esitellään turvallinen, hierarkkinen VPLS-arkkitehtuuri, jolla saadaan aikaan ohjaustason skaalautuvuus. Väitöskirjassa kuvataan myös uusi salattu verkkotunnuksiin perustuva tietokehysten edelleenlähetysmekanismi, jolla L2-kehykset siirretään hierarkkisessa VPLS-verkossa. Lisäksi väitöskirjassa ehdotetaan uuden Distributed Spanning Tree Protocol (DSTP) -protokollan käyttämistä vapaan Ethernet-verkkosilmukan ylläpitämiseen VPLS-verkossa. DSTP:n avulla on mahdollista ajaa muokattu STP (Spanning Tree Protocol) -esiintymä jokaisessa VPLS-verkon etäsegmentissä. Väitöskirjassa esitetään myös kaksi Redundancy Identification Mechanism (RIM) -mekanismia, Customer Associated RIM (CARIM) ja Provider Associated RIM (PARIM), joilla pienennetään näkymättömien silmukoiden vaikutusta palveluntarjoajan verkossa. Viimeiseksi ehdotetaan uutta SDN (Software Defined Networking) -pohjaista VPLS-arkkitehtuuria (Soft-VPLS) vanhojen turvallisten VPLS-arkkitehtuurien tunnelinhallintaongelmien poistoon. Näiden lisäksi väitöskirjassa ehdotetaan kolmea uutta mekanismia, joilla voidaan parantaa vanhojen arkkitehtuurien tunnelinhallintatoimintoja: 1) dynaaminen tunnelinluontimekanismi, 2) tunnelin jatkomekanismi ja 3) nopea tiedonsiirtomekanismi. Ehdotetussa arkkitehtuurissa käytetään VPLS-tunnelin luomisen hallintaan keskitettyä ohjainta, joka perustuu reaaliaikaiseen verkon käyttäytymiseen. Tutkimuksen tulokset auttavat suunnittelemaan ja kehittämään turvallisempia, skaalautuvampia ja tehokkaampia VLPS järjestelmiä, sekä auttavat hyödyntämään tehokkaammin verkon resursseja ja madaltamaan verkon operatiivisia kustannuksia.
358

Minimizing Overhead for Fault Tolerance in Event Stream Processing Systems

Martin, André 20 September 2016 (has links) (PDF)
Event Stream Processing (ESP) is a well-established approach for low-latency data processing enabling users to quickly react to relevant situations in soft real-time. In order to cope with the sheer amount of data being generated each day and to cope with fluctuating workloads originating from data sources such as Twitter and Facebook, such systems must be highly scalable and elastic. Hence, ESP systems are typically long running applications deployed on several hundreds of nodes in either dedicated data-centers or cloud environments such as Amazon EC2. In such environments, nodes are likely to fail due to software aging, process or hardware errors whereas the unbounded stream of data asks for continuous processing. In order to cope with node failures, several fault tolerance approaches have been proposed in literature. Active replication and rollback recovery-based on checkpointing and in-memory logging (upstream backup) are two commonly used approaches in order to cope with such failures in the context of ESP systems. However, these approaches suffer either from a high resource footprint, low throughput or unresponsiveness due to long recovery times. Moreover, in order to recover applications in a precise manner using exactly once semantics, the use of deterministic execution is required which adds another layer of complexity and overhead. The goal of this thesis is to lower the overhead for fault tolerance in ESP systems. We first present StreamMine3G, our ESP system we built entirely from scratch in order to study and evaluate novel approaches for fault tolerance and elasticity. We then present an approach to reduce the overhead of deterministic execution by using a weak, epoch-based rather than strict ordering scheme for commutative and tumbling windowed operators that allows applications to recover precisely using active or passive replication. Since most applications are running in cloud environments nowadays, we furthermore propose an approach to increase the system availability by efficiently utilizing spare but paid resources for fault tolerance. Finally, in order to free users from the burden of choosing the correct fault tolerance scheme for their applications that guarantees the desired recovery time while still saving resources, we present a controller-based approach that adapts fault tolerance at runtime. We furthermore showcase the applicability of our StreamMine3G approach using real world applications and examples.
359

Posouzení informačního systému firmy a návrh změn / Information System Assessment and Proposal for ICT Modification

Marinič, Štefan January 2016 (has links)
The diploma thesis deals with migration of SAP Business Warehouse system to the new in-memory technology SAP HANA. Theoretical basis defines basic terms, usage in-memory technology in Business Intelligence and migration options. In the practical part, the best option of migration and best practices for the company was designed.
360

Berufsbezogene Handlungs- vs. Lageorientierung: Skalierbarkeit und Beziehung zu beruflicher Arbeitsleistung: Occupational action state orientation: Scalability and its relation to job performance

Stadelmaier, Ulrich W. 01 December 2016 (has links)
Die vorliegende Arbeit verknüpft die Theorie der Interaktion psychischer Systeme von Kuhl (2000, 2001) mit dem Modell beruflicher Arbeitsleistung von Tett und Burnett (2003). Unter Anwendung reizorientierter arbeitspsychologischer Stressmodelle werden Hypothesen über einen durch das subjektive Bedrohungs- und Belastungspotenzial der Arbeitssituation moderierten Zusammenhang zwischen dem berufsbezogenen und nach Maßgabe der Item Response Theorie skalierbaren Persönlichkeitsmerkmal Handlungs- vs. Lageorientierung und beruflicher Arbeitsleistung aufgestellt. In drei Befragungen an N = 415, N = 331 sowie N = 49 Berufstätigen wurden querschnittliche Daten zur Hypothesenprüfung erhoben. Berufsbezogene Handlungs- vs. Lageorientierung zeigt sich als valides Subkonstrukt der allgemeinen Handlungs- vs. Lageorientierung, welches gemäß Graded Response Modell von Samejima (1969, 1997) mit 14 Items skalierbar ist. Prospektive berufsbezogene Handlungs- vs. Lageorientierung erklärt in multiplen hierarchischen Regressionsanalysen, im Gegensatz zu allgemeiner Handlungs- vs. Lageorientierung, inkrementell zu Gewissenhaftigkeit, Extraversion und Neurotizismus Anteile kontextueller und aufgabenbezogener Arbeitsleistung. Hypothesenkonträr werden diese Zusammenhänge nur marginal vom subjektiven Belastungspotential der Arbeitssituation moderiert. Die Prädiktorfunktion prospektiver berufsbezogener Handlungs- vs. Lageorientierung für berufliche Arbeitsleistung bleibt auch unter pfadanalytischer Kontrolle eines vorhandenen Common Method Bias erhalten. Die dispositionelle Fähigkeit, durch berufliche Hindernisse gehemmten positiven Affekt vorbewusst gegenregulieren zu können, scheint demnach ein bedeutender Prädiktor beruflicher Arbeitsleistung zu sein, insbesondere bei Führungskräften. Für die berufliche Eignungsbeurteilung ist es damit von diagnostischem Mehrwert, Handlungs- vs. Lageorientierung kontextualisiert zu erheben. Der Einsatz probabilistisch- testtheoretisch konstruierter Skalen steigert dabei die Effizienz des Beurteilungsprozesses. / The current paper combines personality systems interaction theory (Kuhl, 2000, 2001) with the model of job performance by Tett and Burnett (2003). Using established stress models from work psychology it is hypothesized that there is a relation between occupational action state orientation, scalable by means of items response theory, and job performance, which is moderated by the subjective stress level of job characteristics. Three surveys among samples of N = 415, N = 331, and N = 49 professionals yielded cross sectional data for investigating the hypotheses. Occupational action state orientation proves a valid construct which is compatible with Samejima’s (1969, 1997) Graded Response Model using a 14-item scale. As a result of multiple hierarchical regression analyses, the hesitation dimension of specifically occupational, in contrast to general action state orientation is a predictor of both contextual and task performance, incremental to conscientiousness, extraversion, and neuroticism. Contrary to expectations this relation is only marginally moderated by stress-relevant job characteristics. Even when controlling for an occurring common method bias by means of path analysis the occupational hesitation dimension’s predictor role perseveres. Therefore, the dispositional ability in subconsciously regulating inhibited positive affect due to occupational obstacles, seems to be a crucial predictor of job performance, especially regarding leaders. Hence, professional aptitude assessment benefits from assessing action state orientation in a contextualized manner. Application of item response theory-based scales further enhances assessment process efficiency.

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