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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.
181

Attentional biases in social anxiety: an investigation using the inattentional blindness paradigm

Lee, Han-Joo 05 November 2009 (has links)
Social anxiety disorder is the third most common mental disorder with the lifetime prevalence rate of 13.3% in the US population. Typically, it causes significant impairment in a wide range of functioning and follows a chronic, unremitting course if untreated. Over the past two decades, there has been a dramatic increase in clinical research aimed at examining underlying mechanisms maintaining social anxiety. One line of research has investigated attentional biases in social anxiety, using various cognitive experiment paradigms, including the emotional Stroop and the modified dotprobe tasks. However, overall findings are equivocal about the nature of attentional biases in social anxiety and several methodological problems limit the interpretability of the data. The present study examined attentional biases associated with social anxiety using a new research paradigm in the field of anxiety disorders: the inattentional blindness paradigm. This paradigm presents a social cue in the absence of the subjects’ expectation while they are engaged in a cognitively demanding task, thereby enabling the more purely attentional aspect of information processing to be examined reducing the influence of potential response biases or effortful strategies. Two independent experiments were conducted using nonclinical student samples consisting of individuals high in social anxiety (HSAs) versus individuals low in social anxiety (LSAs) based on the static and sustained inattentional blindness tasks. Overall, results revealed that HSAs were more likely to detect or identify a socially-threatening cue, relative to LSAs; whereas LSAs were more likely to detect or identify a non-threatening social cue, relative to HSAs. These findings were observed only in the presence of a bogus-speech manipulation. These data suggest the promising utility of the inattentional blindness paradigm in investigating attentional biases in social anxiety and perhaps other psychopathological conditions. Theoretical and clinical implications are discussed. / text
182

An associative approach to task switching

Forrest, Charlotte Louise January 2012 (has links)
This thesis explores the behaviour of participants taking an associative approach to a task-cueing paradigm. Task-cueing is usually intended to explore controlled processing of task-sets. But small stimulus sets plausibly afford associative learning via simple and conditional discriminations. In six experiments participants were presented with typical task-cueing trials: a cue (coloured shape) followed by a digit (or in Experiment 5 a symbol) requiring one of two responses. In the standard Tasks condition (Monsell Experiment and Experiments 1-3), the participant was instructed to perform either an odd/even or a high/low task dependent on the cue. The second condition was intended to induce associative learning of cue + stimulus-response mappings. In general, the Tasks condition showed a large switch cost that reduced with preparation time, a small, constant congruency effect and a small perturbation when new stimuli were introduced. By contrast the CSR condition showed a small, reliable switch cost that did not reduce with preparation time, a large congruency effect that changed over time and a large perturbation when new stimuli were introduced. These differences may indicate automatic associative processing in the CSR condition and rule-based classification in the Tasks condition. Furthermore, an associative model based on the APECS learning algorithm (McLaren, 1993) provided an account of the CSR data. Experiment 3 showed that participants were able to deliberately change their approach to the experiment from using CSR instructions to using Tasks instructions, and to some extent vice versa. Experiments 4 & 5 explored the cause of the small switch cost in the CSR condition. Consideration of the aspects of the paradigm that produced the switch cost in the APECS model produced predictions, which were tested against behavioural data. Experiment 4 found that the resulting manipulation made participants more likely to induce task-sets. Experiment 5 used random symbols instead of numbers, removing the underlying task-sets. The results of this experiment broadly agreed with the predictions made using APECS. Chapter 6 considers an initial attempt to create a real-time version of APECS. It also finds that an associative model of a different class (AMAN, Harris & Livesey, 2010) can provide an account of some, but not all, of the phenomena found in the CSR condition. This thesis concludes that performance in the Tasks condition is suggestive of the use of cognitive control processes, whilst associatively based responding is available as a basis for performance in the CSR condition.
183

The Relationship Between Data Visualization and Task Performance

Phillips, Brandon 12 1900 (has links)
We are entering an era of business intelligence and big data where simple tables and other traditional means of data display cannot deal with the vast amounts of data required to meet the decision-making needs of businesses and their clients. Graphical figures constructed with modern visualization software can convey more information than a table because there is a limit to the table size that is visually usable. Contemporary decision performance is influenced by the task domain, the user experience, and the visualizations themselves. Utilizing data visualization in task performance to aid in decision making is a complex process. We develop and test a decision-making framework to examine task performance in a visual and non-visual aided decision-making by using three experiments to test this framework. Studies 1 and 2 investigate DV formats and how complexity and design affects the proposed visual decision making framework. The studies also examine how DV formats affect task performance, as measured by accuracy and timeliness, and format preference. Additionally, these studies examine how DV formats influence the constructs in the proposed decision making framework which include information usefulness, decision confidence, cognitive load, visual aesthetics, information seeking intention, and emotion. Preliminary findings indicate that graphical DV allows individuals to respond faster and more accurately, resulting in improved task fit and performance. Anticipated implications of this research are as follows. Visualizations are independent of the size of the data set but can be increasingly complex as the data complexity increases. Furthermore, well designed visualizations let you see through the complexity and simultaneously mine the complexity with drill down technologies such as OLAP.
184

The Human Analysis Element of Intrusion Detection: A Cognitive Task Model and Interface Design and Implications

Ellis, Brenda Lee 01 January 2009 (has links)
The use of monitoring and intrusion detection tools are common in today's network security architecture. The combination of tools generates an abundance of data which can result in cognitive overload of those analyzing the data. ID analysts initially review alerts generated by intrusion detection systems to determine the validity of the alerts. Since a large number of alerts are false positives, analyzing the data can severely reduce the number of unnecessary and unproductive investigations. The problem remains that this process is resource intensive. To date, very little research has been done to clearly determine and document the process of intrusion detection. In order to rectify this problem, research was conducted which involved several phases. Fifteen individuals were selected to participate in a cognitive task analysis. The results of the cognitive task analysis were used to develop a prototype interface which was tested by the participants. A test of the participants' knowledge after the use of the prototype revealed an increase in both effectiveness and efficiency in analyzing alerts. Specifically, the findings revealed an increase in effectiveness as 72% of the participants made better determinations using the prototype interface. The results also showed an increase in efficiency when 72% of the participants analyzed and validated alerts in less time while using the prototype interface. These findings, based on empirical data, showed that the use of the task diagram and prototype interface helped to reduce the amount of time it previously took to analyze alerts generated by intrusion detection systems.
185

Analyse moléculaire des canaux potassiques task dans l'aldostéronisme primaire humain / Molecular analysis of TASK potassium channels in human primary aldosternism

Tareen, Shahwali Khan 25 March 2014 (has links)
L'hyperaldostéronisme primaire (HAP) est la plus fréquente cause identifiable de l'hypertension, et résulte de la production autonome d'aldostérone par les glandes surrénales. Chez la souris, la délétion génétique des canaux TASK1 et TASK3 provoque des changements biochimiques qui imitent HAP humain. Ces canaux permet la sortie de K+ et polarise le potentiel de la membrane des cellules glomérules. Nous avons étudié la variation et l'expression de KCNK3 et 9 chez l'homme. Notre étude d'association à montré aucune association d'HAP avec n'importe quel SNP au niveau de l'ensemble du génome. Le séquençage de l'ADN de la lignée germinale dans 825 cas d'HAP, et 41 échantillons d'ADN tumoral a abouti à 14 variantes différents dans KCNK3 et 9 dans la lignée germinale, dont 6 non-synonyme, 8 synonyme. Des tests in vitro n'ont montré aucune perte de la fonction du canal. Aucun changement de séquence somatique à été trouvé. L'hybridation-in-situ dans 6 glandes surrénales contrôle (CA) et 20 glandes adénomes produisant l'aldostérone (APA) a montré que KCNK3 été fortement exprimée dans les trois couches du cortex, tandis que l'expression de KCNK9 était faible et limitée au glomérule en CA. Dans les APA, l'expression de KCNK3 a été détectée, alors que l'expression KCNK9 était faible et hétérogène. Le transcriptome de 43 APA et 11 CA a révélé une légère surexpression de KCNK3 dans les APA, en corrélation avec l'expression de CYP11B2. La surexpression de TASK1 dans les APA peut être secondaire à un phénomène épigénétique. Alors que la variation de l'ADN est incompatible avec un rôle causal, il peut y avoir une possible contribution des changements d'expression de TASK1 dans HAP humain. / Hypertension is the leading cause of human mortality globally. Representing about a tenth of all patients, Primary Aldosteronism (PA) is the commonest identifiable cause of hypertension, and results from the autonomous production of aldosterone by the adrenal glands. The two principal sub-types are Bilateral Adrenal Hyperplasia (BAH), and Aldosterone Producing Adenoma (APA), which account for two-thirds and one-third of the cases respectively. The molecular etiology of primary aldosteronism has remained elusive until recently, when through an exome sequencing study, mutations in the potassium channel-coding gene KCNJ5 were found to cause PA in humans. These mutations were found in up to 40% of APAs, and only in a rare familial variety of BAH. A subsequent exome sequencing study identified mutations in ATPase famile genes in about 7% of APAs, bringing the total genetic yield to about 47%. The molecular pathology of more than half of APAs and of most BAHs remain unexplained. In mouse models, the genetic deletion of TASK-1 and TASK-3 potassium channels cause biochemical changes that resemble those seen in human PA. TASK 1 and TASK 3 are background ‘leak’ potassium channels, which by permitting the outward flow of K+ ions, polarise the adrenal glomerulosa cell membrane potential. The genetic removal of these channels therefore results in a marked depolarization of the glomerulosa cells, leading to their increased aldosterone secretory function, diagnosed as PA. In humans, the contribution of TASK-1 and TASK-3 channel dysfunction to PA has been negated by sequencing studies of the genes that code for these channels (KCNK3 and KCNK9 respectively). However, these studies have included only a small number of patients, motivating a comprehensive molecular analysis of the genes in a large patient cohort. To this end, we investigated commonly and rarely occuring genetic variation in, and expression of, KCNK 3 and KCNK9. Our Genome Wide Association Study (GWAS) showed no association of PA (either APA or BAH subtypes or both) with any single SNP at the genome-wide level of statistical significance. At sub genome-wide levels, however, SNPs of KCNK3 did associate, and the association signal strengthened when specific combinations of the SNPs were tested for association at a time. While no inherited or acquired DNA sequence variation in KCNK3 and KCNK9 have ever been detected in PA patients, on sequencing germline DNA in 825 PA cases, and 41 tumoral DNA samples, 14 different coding single nucleotide variants in KCNK3 and KCNK9 were found in the germline DNA only, of which 6 were non-synonymous, and 8 synonymous. However, on heterologous expression and electrophysiology, these did not affect channel function. No somatic sequence changes were found.Expression of KCNK3 and KCNK9 was investigated by in-situ hybridization in 6 control adrenal glands and 20 adrenals from patients with APA. In the control adrenal, the KCNK3 gene was highly expressed in all three layers of the adrenal cortex, while KCNK9 expression was barely detectable, and restricted to the zona glomerulosa. In APAs, KCNK3 expression was detected in a majority of patients, while KCNK9 expression was low and heterogeneous among samples. Strikingly, KCNK9 was highly expressed in the hyperplastic peritumoral zona glomerulosa, possibly due to a positive feed-back by high circulating aldosterone or low potassium levels on KCNK9 expression. Transcriptome profiling of 43 APA and 11 control adrenals revealed a slight, but significantly increased expression of KCNK3 in adenomas compared to controls that correlated positively with CYP11B2 expression. The quantitative changes of TASK1 expression observed in APAs may be secondary to a primary epigenetic phenomenon or be secondary to increased aldosterone production due to dysregulation of master transcription factors or upstream signaling cascades in the aldosterone biosynthetic pathway.
186

Optimisation du séquencement de tâches avec lissage du mouvement dans la réalisation de missions autonomes ou collaboratives d’un humanoïde virtuel ou robotique / Optimization of motion overlapping for task sequencing

Keith, François 10 December 2010 (has links)
La réalisation d'une mission robotique se décompose usuellement en trois étapes: la planification, i.e. le choix des taches à réaliser, le séquencement, i.e. la détermination du timing et de l'ordre de réalisation des tâches, et finalement l'exécution du plan de tâches. Pour les systèmes redondants tels que les robots humanoïdes, la tâche (dans le sens de fonction de tâche) détermine une commande sur une partie du robot, permettant ainsi la réalisation simultanée de plusieurs tâches à l'aide d'un formalisme de pile de tâches. Cependant, les mécanismes d'ordonnancement classiques ne gèrent pas les cas où le mouvement est déterminé par un ensemble de tâches hiérarchisé: pour ces robots, la phase d'ordonnancement est éludée et l'exécution se base directement sur la plan de tâches donné par le planificateur. Le but de cette thèse est de réintroduire cette phase d'ordonnancement, tout en maintenant le rôle central de la tâche. Dans un premier temps, la continuité de la commande fournie par la pile de tâches est étudiée. En particulier, nous mettons en évidence les discontinuités accompagnant la réalisation d'événements discrets (à savoir l'insertion, le retrait et l'échange de priorité de tâches), puis proposons et comparons plusieurs méthodes de lissage. Ensuite, nous présentons une méthode permettant d'optimiser une séquence de tâches donnée en modifiant le timing et la paramétrisation des tâches, tout en respectant les contraintes liées à l'environnement. Enfin, une nouvelle utilisation de la flexibilité de la fonction de tâche consistant à adapter une séquence de tâches aux préférences d'un utilisateur humain est illustrée. Ces résultats sont illustrés sur un robot humanoïde. / A general agreed approach on mission and motion planning consists in splitting it into three steps: decomposing the mission into a sequence of tasks (task planning), determining the order of realization and the timing of the tasks (task scheduling) and finally executing the task sequence. This approach maintains the task component in the entire reasoning, using it as a bridge between planning, scheduling and execution.In the sense of task function, a task defines a control law on part of the robot. Hence, for highly redundant systems such as humanoid robots, it is possible to realize several tasks simultaneously using a stack-of-tasks formalism. Though, classical schedulers do not handle the case where the motion is specified not by one, but by a combination of tasks organized into a hierarchy. As a result, the scheduling phase is usually skipped. This thesis aims at reintroducing the scheduling phase, while maintaining the central role of the task.First, the stack-of-tasks formalism is recalled and the continuity of the control law is studied. Particularly, we show that discreet operations (insertion, removal and swap of priority between tasks) create discontinuities in the control. We then present and discuss smoothing methods. Second, we present a task-overlapping based method to optimize not only the scheduling but also the behavior of the tasks of a given sequence, while accounting for the physical constraint of the execution. Finally, we introduce a new perspective in the usage of the task-function approach the task function approach to personalize a task sequence and take into account user preferences.These results are experimented on the humanoid robot platform HRP-2.
187

O lúdico na sala de aula de língua portuguesa no fundamental II. / Games in the portuguese class in middle school.

Costa, Andrea Volante 24 March 2008 (has links)
Este trabalho tem por objetivo a reflexão sobre uma alternativa de ensino e aprendizagem de Língua Portuguesa no Fundamental II cujo foco esteja no desenvolvimento efetivo das habilidades de leitura, oralidade e escrita por meio de atividades lúdicas. Para tanto, pautou-se pela experiência bem sucedida com esse tipo de recurso no ensino e aprendizagem de Língua Inglesa, notadamente em cursos de idiomas, cuja orientação metodológica é a Abordagem Comunicativa, e, em especial, o Task-based Language Teaching. O conceito de jogo aqui empregado provém das obras de Huizinga (2004), Wittgenstein (1975) e Brougère (1995, 1999), enquanto a relação entre jogo e Educação foi discutida tendo em vista as considerações de Kishimoto (1992, 1994, 1998, 2001, 2007), Brougère (1995, 1999) e Macedo, Petty e Passos (2005), e entre jogo e língua estrangeira, por Crookall e Oxford (1990) e Bullards (1990). Discutiu-se as abordagens e metodologias mais difundidas no Brasil (FERRO, 1998; RODRIGUES, 2005; BERGO E GOMES, 1985) com a finalidade de se contextualizar a utilização do jogo no Task-based Language Teaching (ELLIS, 2003). A análise do que se compreende como tarefa central do ensino e aprendizagem de Língua Portuguesa privilegiou quatro pontos de vista distintos: o da tradição escolar, dos resultados das avaliações do ensino Fundamental, da perspectiva oficial (PCN) e dos estudos lingüísticos voltados à Educação. Partindo desse referencial teórico, realizou-se em duas etapas uma pesquisa de cunho etnográfico. A Primeira Entrada em Campo consistiu na observação de aulas de Língua Portuguesa e de Língua Inglesa extracurricular em um colégio particular em São Paulo. Objetivou-se verificar como tem sido a prática efetiva nessas disciplinas com relação ao uso de jogos em sala de aula, concluindo-se que 60% do tempo das aulas observadas de Língua Inglesa foram ocupados por atividades lúdicas, enquanto, a rigor, nenhuma atividade desse caráter ocorreu na de Língua Portuguesa. Na Segunda Entrada em Campo realizou-se um minicurso de leitura, oralidade e escrita, ministrado pela pesquisadora a alunos da rede pública de ensino, no qual verificou-se as possibilidades reais de sucesso de uma metodologia de Língua Portuguesa cuja prática considerasse as atividades lúdicas como uma alternativa ao excesso de atividades metalingüísticas revelados por estudos de Neves (2003) e Semeghini- Siqueira (1998, 2006a). O referencial metodológico para a elaboração das aulas do minicurso pautou-se pelos conceitos de Avaliação Diagnóstica e Formativa (SEMEGHINI-SIQUEIRA, 1997, 2002) e Seqüência Didática (SCHNEUWLY; DOLZ; NOVERRAZ, 2007) como forma de estruturação para atividades lingüísticas e epilingüísticas (SEMGHINI-SIQUEIRA, 1977, 1997, 2001, 2005, 2006b, 2006c; FRANCHI, 1991; GERALDI, 1985, 1991, 2002; TRAVAGLIA, 1996; POSSENTI, 1996), organizadas em torno do gênero textual entrevista. A inserção de atividades lúdicas que privilegiaram diversas habilidades e diferentes formas de abordagem da língua resultou em um aprendizado mais significativo e eficiente do que aquele observado em aulas de Língua Portuguesa cujas atividades restringem-se apenas às metalingüísticas. / This dissertation aims at reflecting upon an alternative to Portuguese learning and teaching in Middle school1 in which the focus is the development of the proficiency in reading, writing and speaking by means of game-like activities. Therefore, it bears resemblance to the highly successful experience conducted by English courses in line with the Communicative Approach, specially, those of Task-based Language Teaching orientation. The concept of game hereafter presented comes from the works of Huizinga (2004), Wittgenstein (1975) and Brougère (1995, 1999), meanwhile the relationship between games and education relies upon the considerations of Kishimoto (1992, 1994, 1998, 2001, 2007), Brougère (1995, 1999) and Macedo, Petty e Passos (2005); as for games and second language learning and teaching, by Crookall and Oxford (1990) and Bullards (1990). Approaches and methodologies with a greater importance in the Brazilian context (FERRO, 1998; RODRIGUES, 2005; BERGO E GOMES, 1985) were discussed in order to provide background information on the usage of games in Task-based Language Teaching (ELLIS, 2003). Four points of view were privileged to the analysis of the main reasons for learning and teaching Portuguese: the schooling tradition, the results of the evaluation conducted to measure the performance of the students enrolled on the Middle school, the official perspective (PCN) and the linguistic studies related to Education. Having this theoretical scope in mind, two different pieces of ethnographic research were conducted. The first one consisted of the observation of both Portuguese and English (extracurricular) classes at a private school in São Paulo, so that it would be possible to verify whether their delivery has really been taking into consideration the use of games or not. It was reached the conclusion that 60% of the time spent in the English classes observed were on game activities. On the other hand, none activity was observed during the Portuguese class. In the SECOND FIELD STUDY, there was a mini-course of reading, writing and speaking, taught by the researcher, in which students from a public school in São Paulo participated in. Its main objective was to access the real possibilities of success in teaching Portuguese by making use of game activities instead of the metalinguistic ones, pointed as the major resource for Portuguese classes by Neves (2003) and Semeghini-Siqueira (1998, 2006a). The methodological reference for the mini-course is based upon the concepts of \"Avaliação Diagnóstica e Formativa\" (SEMEGHINI-SIQUEIRA, 1997, 2002) and \"Seqüência Didática\" (SCHNEUWLY; DOLZ; NOVERRAZ, 2007) as a means of structuring the linguistic and epilinguistic activities (SEMGHINI-SIQUEIRA, 1977, 1997, 2001, 2005, 2006b, 2006c; FRANCHI, 1991; GERALDI, 1985, 1991, 2002; TRAVAGLIA, 1996; POSSENTI, 1996) around the interview genre. As a result, the game activities carried out in the Portuguese classes held by the mini-course proved to be very effective, therefore the learning was enriched by the variety of approaches as well as the range of skills involved in performing the tasks.
188

Synthesis of continuous whole-body motion in hexapod robot for humanitarian demining

Khudher, Dhayaa Raissan January 2018 (has links)
In the context of control, the motion of a legged robot is very challenging compared with traditional fixed manipulator. Recently, many researches have been conducted to control the motion of legged robot with different techniques. On the other hand, manipulation tasks have been addressed in many applications. These researches solved either the mobility or the manipulation problems, but integrating both properties in one system is still not available. In this thesis, a control algorithm is presented to control both locomotion and manipulation in a six legged robot. Landmines detection process is considered as a case study of this project to accelerate the mine detection operation by performing both walking and scanning simultaneously. In order to qualify the robot to perform more tasks in addition to the walking task, the joint redundancy of the robot is exploited optimally. The tasks are arranged according to their importance to high level of priority and low level of priority. A new task priority redundancy resolution technique is developed to overcome the effect of the algorithmic singularities and the kinematic singularity. The computational aspects of the solution are also considered in view of a real-time implementation. Due to the dynamic changes in the size of the robot motion space, the algorithm has the ability to make a trade-off between the number of achieved tasks and the imposed constraints. Furthermore, an appropriate hierarchy is imposed in order to ensure an accurate decoupling between the executed tasks. The dynamic effect of the arm on the overall performance of the robot is attenuated by reducing the optimisation variables. The effectiveness of the method is evaluated on a Computer Aided Design (CAD) model and the simulations of the whole operation are conducted using MATLAB and SimMechanics.
189

Alocação dinâmica de tarefas periódicas em NoCs malha com redução do consumo de energia / Energy-aware dynamic allocation of periodic tasks on mesh NoCs

Wronski, Fabio January 2007 (has links)
O objetivo deste trabalho é propor técnicas de alocação dinâmica de tarefas periódicas em MPSoCs homogêneos, com processadores interligados por uma rede emchip do tipo malha, visando redução do consumo de energia do sistema. O foco principal é a definição de uma heurística de alocação, não se considerando protocolos de escalonamento distribuído, uma vez que este ainda é um primeiro estudo para o desenvolvimento de um alocador dinâmico. Na arquitetura alvo utilizada, cada nodo do sistema é dado como autônomo, possuindo seu próprio escalonador EDF. Além disso, são aplicadas técnicas de voltage scaling e power managmenent para redução do consumo de energia durante o escalonamento. Durante a pesquisa do estado da arte, não foram encontradas técnicas de alocação dinâmica em NoCs com restrições temporais e minimização do consumo de energia. Por isso, esse trabalho se concentra em avaliar técnicas de alocação convencionais, como bin-packing e técnicas baseadas em teoria de grafos, no contexto de sistemas embarcados. Dessa forma, o modelo de estimativas do consumo de energia de alocações é baseado no escalonamento de grafos de tarefas, e foi utilizado para implementar a ferramenta Serpens com este propósito. Os grafos de tarefas utilizados nos experimentos são tirados do benchmark E3S – Embedded System Synthesis Benchmark Suite, composto por um conjunto de grafos de tarefas gerados aleatoriamente com a ferramenta TGFF – Task Graph for Free, a partir de dados de aplicações comuns em sistemas embarcados obtidos no EEMBC – Embedded Microprocessor Benchmark Consortium. Entre as heurísticas de bin-packing, Best-Fit, First-Fit e Next-Fit geram alocações com concentração de carga, enquanto a heurística Worst-Fit faz balanceamento de carga. O balanceamento de carga favorece a aplicação de voltage scaling enquanto a concentração favorece o power management. Como o bin-packing não contempla comunicação e dependência entre tarefas em seu modelo, o mesmo foi reformulado para atender esta necessidade. Nos experimentos, a alocação inicial com bin-packing original apresentou perdas de deadlines de até 84 % para a heurística Worst-Fit, passando para perdas em torno de 16% na alocação final, praticamente com o mesmo consumo de energia, após a reformulação do modelo. / The goal of this work is to offer dynamic allocation techniques of periodic tasks in mesh networks-on-chip, aiming to reduce the system power consumption. The main focus is the definition of an allocation heuristic, which does not consider distributed scheduling protocols, since this is the beginning of a study for the development of a dynamic partitioning tool. In the target architecture, each system node is self-contained, that is, the nodes contain their own EDF scheduler. Besides, voltage-scaling and power management techniques are applied for reducing power consumption during the scheduling. To the best of our knowledge, this is the first research effort considering both temporal constraints and power consumption minimization on the dynamic allocation of tasks in a mesh NoC. This way, our concentrates in the evaluation of dynamic allocation techniques, which are generally used in distributed systems, in the embedded systems context, as bin-packing and graph theory based techniques. Therefore, the estimation model for power consumption is based on task graph scheduling, and it was used for implementing the Serpens tool with this purpose. The task graphs used in the experiments were obtained from the E3S benchmark (Embedded System Synthesis Benchmark Suite), which is composed by a set of task graphs randomly generated with the TGFF tool (Task Graph for Free), from common application data obtained from the EEMBC (Embedded Microprocessor Benchmark Consortium). Among the bin-packing heuristics, Best-Fit, First-Fit, and Next-Fit generate allocations with load concentration, while the Worst-Fit heuristics works with load balancing. Load balancing favors the application of voltage scaling, while load concentration favors the utilization of power management. Since the bin-packing model does not consider inter-task communication and dependency, it has been modified to fulfill this need. In the experiments, the initial allocation using the original bin-packing model presented deadline losses of up to 84% for the Worst-Fit heuristic, changing for losses around 16% in the final allocation, after modification of the model, maintaining almost the same power consumption.
190

The Concurrent Development Scheduling Problem (CDSP)

Paul, Leroy W 27 October 2005 (has links)
The concurrent development (CD) project is defined as the concurrent development of both hardware and software that is integrated together later for a deliverable product. The CD Scheduling Problem (CDSP) is defined as most CD baseline project schedules being developed today are overly optimistic. That is, they finish late. This study researches those techniques being used today to produce CD project schedules and looks for ways to close the gap between the baseline project schedule and reality. In Chapter 1, the CDSP is introduced. In Chapter 2, a review is made of published works. A review is also made of commercial scheduling software applications to uncover their techniques as well as a review of organizations doing research on improving project scheduling. In Chapter 3, the components of the CDSP are analyzed for ways to improve. In Chapter 4, the overall methodology of the research is discussed to include the development of the Concurrent Development Scheduling Model (CDSM) that quantifies the factors driving optimism. The CDSM is applied to typical CD schedules with the results compared to Monte Carlo simulations of the same schedules. The results from using the CDSM on completed CD projects are also presented. The CDSM does well in predicting the outcome. In Chapter 5, the results of the experiments run to develop the CDSM are given. In Chapter 6 findings and recommendations are given. Specifically, a list of findings is given that a decision maker can use to analyze a baseline project schedule and assess the schedules optimism. These findings will help define the risks in the CD schedule. Also included is a list of actions that the decision maker may be able to take to reduce of the risk of the project to improve the chances of coming in on time.

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