Umstellung des PS/2-Pools Ausserbetriebnahme der IBM 4381 Neues vom Campus-Netz Sicherheit in Unix-Systemen - Teil 2 Unix-Stammtisch Kurstermine Semesterpause

Service-Angebot Neues aus dem PS/2-ABZ Sicherheit in Unix-Systemen IBM 4381 DOS-Rechner am Netz Kostenfreie Software fuer die Lehre Software-Information

Das URZ stellt sich vor Die Technik des URZ Netzbetrieb Stand Rechnernetzausbau Ansprechpartner

Neuer WWW-Server Metacomputing - neue Aufgabenverteilung im Netz Harvest Secure Shell Nutzung der WS-Pools SW-Umgebung Parsytec URZ auf der CeBit Software-News Dienste des URZ - Ueberblick

The characteristics of irregular algorithms make a parallel implementation difficult, especially for PC clusters or clusters of SMPs. These characteristics may include an unpredictable access behavior to dynamically changing data structures or strong irregular coupling of computations. Problems are an unknown load distribution and expensive irregular communication patterns for data accesses and redistributions. Thus the parallel implementation of irregular algorithms on distributed memory machines and clusters requires a special organizational mechanism for a dynamic load balance while keeping the communication and administration overhead low. We propose task pool teams for implementing irregular algorithms on clusters of PCs or SMPs. A task pool team combines multithreaded programming using task pools on single nodes with explicit message passing between different nodes. The dynamic load balance mechanism of task pools is generalized to a dynamic load balance scheme for all distributed nodes. We have implemented and compared several versions for task pool teams. As application example, we use the hierarchical radiosity algorithm, which is based on dynamically growing quadtree data structures annotated by varying interaction lists expressing the irregular coupling between the quadtrees. Experiments are performed on a PC cluster and a cluster of SMPs.

Ce travail aborde la problématique des systèmes de refroidissement ou de contrôle thermique industriels. Nous avons particulièrement mis l'accent sur le refroidissement des serveurs informatiques. Une première partie consiste en l'étude des moyens d'amélioration des techniques de refroidissement existantes, tandis que la deuxième partie est une réflexion sur des techniques de refroidissement alternatives potentiellement plus efficaces et répondant aux demandes actuelles du contrôle thermique industriel. Dans le premier chapitre, nous analysons la bibliographie et la théorie relatives aux phénomènes physiques derrière les techniques de refroidissement étudiées. Ensuite, une classification des techniques de refroidissement est proposée en fin de chapitre. Ce chapitre a servi de base pour l'amélioration des technologies de refroidissement existantes et à la réflexion sur de nouvelles techniques plus efficaces. Le second chapitre porte sur l'optimisation d'une plaque froide, destinée au refroidissement des serveurs informatiques, en s'aidant d'un outil numérique et d'essais expérimentaux. Nous avons noté une augmentation des transferts de chaleur dans la plaque froide en utilisant des inserts, notamment ceux en forme de losange disposés en quinconce. A l'inverse, l'utilisation de certains nanofluides en tant que fluides caloporteurs ne semble pas apporter de gain significatif. Dans le troisième chapitre nous détaillons la démarche suivie pour la conception d'un dissipateur de chaleur basé sur une technologie caloducs, destiné au refroidissement des cartes électroniques. En premier lieu, nous présentons le modèle thermohydraulique de dimensionnement d'un caloduc cylindrique ; une étude paramétrique (géométrique, type de fluide,...) nous a permis d'identifier le jeu de paramètres donnant la meilleure performance du caloduc. En second lieu, nous évoquons les tests réalisés sur le dissipateur de chaleur à caloduc qui nous amènent à valider en partie le modèle thermohydraulique développé. Le dernier chapitre porte sur la réalisation et l'étude d'un démonstrateur pour le refroidissement des cartes électroniques par immersion dans un liquide à basse température de saturation. On commence par la mise en place et l'utilisation d'un modèle numérique pour la conception du démonstrateur, puis des tests expérimentaux sont réalisés. Les premiers résultats obtenus en utilisant le SES-36 comme fluide de travail sont assez prometteurs.Mots clés : modélisation, transfert de chaleur, refroidissement, datacenter, liquid-cooling, caloducs, échangeurs, nanofluides, ébullition en vase, simulation numérique / The present work is about industrial thermal control systems issues, a focus is done on IT servers cooling. The first part of this document is about cooling techniques optimization. The second part concerns investigations for new cooling techniques potentially more efficient and which can address today's challenges of industrial thermal control systems. In the first chapter, we have done a literature survey and a theoretical analysis of physical phenomena behind studied cooling techniques. Then, we have sorted those techniques according to some criteria. This chapter is a basis for optimization studies we have achieved in the second chapter and for our new cooling techniques investigations in the two last chapters. In the second chapter, we have presented a study about heat transfer enhancement in a cold plate developed for IT servers liquid-cooling. We have observed great heat transfer enhancement when adding lozenge shaped fins inside the cold plate channels. No gain was noted when using some nanofluids as heat transfer liquids. We have shown, in the third chapter, a conception algorithm of a heat spreading device destined for IT servers cooling. The heat spreader is based on a heatpipe technology. First of all, we have presented the thermohydraulic model for cylindrical heatpipes design. A parametric study (geometric, working fluids ...) showed the best combination to obtain the highest heatpipe performance. Then, the heat spreader has been tested and we have validated partially the heatpipe model. The last chapter of this work is a study of a demonstrator destined for cooling down electronic components by immersion in a dielectric fluid with a low saturation temperature. We first built a numerical model to design the demonstrator and then it has been tested. The first results are very encouraging, when using SES-36 as a working fluid.Keywords : modeling, heat transfer, cooling, datacenter, liquid-cooling, heat pipes, heat exchangers, nanofluids, pool boiling, numerical simulation

Measurement processes are vital for any organization as they are used to asses, analyze, monitor and control the processes, products and resources. The measurement programs are used in different ways in different organizations. Most of the measurement programs fail to provide the expected results; therefore it‘s needed to consider the success factors and reasons of failures for the measurement programs. The GQM is the most widely used model for measurement programs having various extensions to overcome its shortcomings in different scenarios. The Goals, Questions and metrics are defined and used in different ways at different levels in the organizations. There is a need of improving the measurement programs and one of the solutions is to provide a framework that can define the goals, questions and measures in a structured way. The prioritization, traceability and re-usability of goals and questions provide the effectiveness in the measurement program. The optimization of the measures and building a measurement repository makes the measurement collection process precise. In this thesis, the results of a systematic review on the current literature on software measurement programs are presented. An assessment of the current state of art on measurement programs, their usability and success factors is done. The study of measurement models, frameworks, tools and standards is done later on to know the different ways of goals, questions definition and measurement collection methods. The systematic review of the research work is done over the period 1997 – 2009. In order to understand and explore the difficulties in application of measurement programs in the industrial settings, interviews are conducted within a CMMI Level 3 company. On the basis of the systematic review analysis results and industrial interviews, a framework for a more effective measurement process is defined and within the framework, a model called ‗Structured Prioritized Goal Question Metrics (SPGQM)‘ is developed. This framework extends the well-known Goal Question Metric paradigm and basically comprises of two models; the Optimum Measures Set Decision (OMSD) model developed within a Master of Science thesis study at the Blekinge Institute of Technology and the SPGQM. This framework defines the process in order to define structured goals and questions with the help of templates and to prioritize them with the help of OMSD model. This framework has been validated in a CMMI Level 3 company. The validation was done by means of conducting a case study.

Ce travail examine les bénéfices d’un apprentissage par situation complexe en natation de vitesse chez des élèves de 5ème ; les soubassements théoriques sont pluriels. L’Approche Par Compétence (APC) à l’école, selon la pédagogie de l’intégration, invite à concevoir des situations complexes conduisant les élèves à intégrer leurs ressources pour résoudre des problèmes. Cette approche pédagogique se base aussi sur la psychologie sociale du développement et des acquisitions plaçant au coeur des dispositifs d’apprentissage, les interactions sociales et les échanges verbaux. Plus précisément, le dispositif étudié est construit à partir des principes socioconstructivistes de l’apprentissage coopératif. Au cours d’une séquence de douze séances d’EPS, les élèves de deux conditions d’enseignement différentes, ont été testés de façon répétée en situation complexe. Ce travail poursuit trois objectifs. En premier lieu, nous avons comparé les acquisitions sur les plans moteur, social et méthodologique, des élèves selon la condition (individuelle / interactive). Les résultats révèlent des progrès plus importants au niveau des performances chronométriques pour les élèves de la condition interactive. Ensuite, nous avons examiné le processus de « mise en synergie » des ressources, induit par la situation complexe. Etre préparé à intégrer ses ressources en situation complexe, optimise le développement de compétences motrices, cognitives et sociales. Enfin, nos observations dévoilent les effets de la compétition sur la coopération des élèves. L’apprentissage par situation complexe optimise l’exploitation des compétences individuelles au profit de la réalisation d’une performance collective. / This work examines the advantages of training in speed swimming complex situations for 8th grade pupils and there are many theoretical bases attached to it. The competencies-based approach (APC in French) at school, according to the pedagogy of integration, invites to conceive complex situations leading pupils to integrate their resources to solve problems. This teaching approach is also based on the development and acquisition social psychology putting forward training devices, social interactions and verbal exchanges. More precisely, this work is built according to the socioconstructivist principles of the co-operative learning. During a sequence of twelve PE sessions, two groups of pupils in two different teaching conditions, were tested in complex situations. This work pursues three goals. Initially, we compared pupils according to the condition (individual/interactive), their acquisitions on the physical, social and methodological levels. The results reveal more important progress on the level of chronometric performances for the pupils of the interactive condition. Then, we examined the resources, induced by the complex situation in the process of “setting in synergy”. To be prepared to integrate his complex situation resources optimizes the development of physical, cognitive and social skills. Lastly, our observations reveal the effects of competition on the pupils’ co-operation. The training by complex situation optimizes the coordination of individual skills to succeed in the collective performance.

Abstract Fishways are hydraulic structures designed to dissipate the energy of flowing water in order to decrease water velocities and increase water depths. The history of fishways is long, the first written remarks date back to the 17th century. Fishway hydraulics, however, have been intensively studied only starting since the 1980's. Fishways have been classified into three main categories according to their hydraulic characteristics: pool-and-weir, vertical slot, and Denil fishways. Fishways are hydraulically complex structures, and thus designing tools for different fishway types have been developed. In this report, a new designing procedure has been established, and equations for each main fishway type have been suggested. In addition, flow conditions below different fishway types have been examined, and velocity distributions at weirs with V-shaped crests in both pool-and-weir fishways and at a single weir have been compared in different discharges and drops. Fishway flows have been compared with flows over single weirs.

Master of Science / Department of Mechanical and Nuclear Engineering / Steven J. Eckels, Bruce R. Babin / This project studied the pool boiling of R-134a and R-123 on smooth and enhanced tubes. This is the 1st phase of ASHRAE project RP-1316 "Experimental Evaluation of The Heat Transfer Impacts of Tube Pitch in a Highly Enhanced Surface Tube Bundle". A Turbo BII-HP and a Turbo BII-LP enhanced tubes were used in this study. These tubes were manufactured and donated by Wolverine Tube, Inc. Four different boiling cases were tested, R-134a on smooth tube, R-123 on smooth tube, R-134a on Turbo BII-HP tube, and R-123 on Turbo BII-LP tube. The first step in this study was performing a modified Wilson plot analysis, once completed, the average and local refrigerant heat transfer coefficients were determined. This thesis also presents the enthalpy-based heat transfer analysis (EBHT), a new method for determining the heat exchanger's overall heat transfer coefficient as a function of the enthalpy change of incompressible fluids. The test tubes' outer diameter is 19.05 mm and length is 1 m. Tests were conducted in a single tube test section, in which the test tube was water heated. All tests were conducted at a saturation temperature of 4.44 °C. The heat flux range is 9.2-126.6 kW/m[superscript]2 for testing with R-134a on smooth tube, 9.2-58 kW/m[superscript]2 for R-123 on smooth tube, 4.1-135.1 kW/m[superscript]2 for R-134a on Turbo BII-HP tube and 4.7-59.8 kW/m[superscript]2 for R-123 on Turbo BII-LP tube. Results show that the heat transfer coefficient increases with heat flux for all cases except the case of R-134a on Turbo BII-HP tube, where it experiences a trend change. Part of this study was comparing the smooth and enhanced tubes performances. R-134a Turbo BII-HP tube to smooth tube heat transfer coefficient ratio changes from 4 at low heat flux to 1.7 at high heat flux. R-123 Turbo BII-LP tube to smooth tube heat transfer coefficient ratio changes from 24 at low heat flux to 7 at high heat flux. The performance of Turbo BII-HP and Turbo BII-LP was found to be very similar over the tested heat flux range of the Turbo BII-LP tube. Comparison plots with available literature are presented.