No description available.

La capacité des systèmes de stockage de données ne cesse de croître pour atteindre actuellement l’échelle de l’exaoctet, ce qui a un réel impact sur la robustesse des systèmes de stockage. En effet, plus le nombre de disques contenus dans un système est grand, plus il est probable d’y avoir une défaillance. De même, le temps de la reconstruction d’un disque est proportionnel à sa capacité. La simulation permet le test de nouveaux mécanismes dans des conditions quasi réelles et de prédire leur comportements. Open and Generic data Storage system Simulation tool (OGSSim), l’outil que nous proposons, supporte l’hétérogénéité et la taille importante des systèmes actuels. Sa décomposition modulaire permet d’entreprendre chaque technologie de stockage, schéma de placement ou modèle de calcul comme des briques pouvant être combinées entre elles pour paramétrer au mieux la simulation. La robustesse étant un paramètre critique dans ces systèmes, nous utilisons le declustered RAID pour assurer la distribution de la reconstruction des données d’un disque en cas de défaillance. Nous proposons l’algorithme Symmetric Difference of Source Sets (SD2S) qui utilise le décalage des blocs de données pour la création du schéma de placement. Le pas du décalage est issu du calcul de la proximité des ensembles de provenance logique des blocs d’un disque physique. Pour évaluer l’efficacité de SD2S, nous l’avons comparé à la méthode Crush, exemptée des réplicas. Il en résulte que la création du schéma de placement, aussi bien en mode normal qu’en mode défaillant, est plus rapide avec SD2S, et que le coût en espace mémoire est également réduit (nul en mode normal). En cas de double défaillance, SD2S assure la sauvegarde d’une partie, voire de la totalité, des données / Capacity of data storage systems does not cease to increase to currently reach the exabyte scale. This observation gets a real impact on storage system robustness. In fact, the more the number of disks in a system is, the greater the probability of a failure happening is. Also, the time used for a disk reconstruction is proportional to its size. Simulation is an appropriate technique to test new mechanisms in almost real conditions and predict their behavior. We propose a new software we callOpen and Generic data Storage system Simulation tool (OGSSim). It handles the heterogeneity andthe large size of these modern systems. Its modularity permits the undertaking of each storage technology, placement scheme or computation model as bricks which can be added and combined to optimally configure the simulation.Robustness is a critical issue for these systems. We use the declustered RAID to distribute the data reconstruction in case of a failure. We propose the Symmetric Difference of Source Sets (SD2S) algorithmwhich uses data block shifhting to achieve the placement scheme. The shifting offset comes from the computation of the distance between logical source sets of physical disk blocks. To evaluate the SD2S efficiency, we compared it to Crush method without replicas. It results in a faster placement scheme creation in normal and failure modes with SD2S and in a significant reduced memory space cost (null without failure). Furthermore, SD2S ensures the partial, if not total, reconstruction of data in case of multiple failures.

Master of Agribusiness / Department of Agricultural Economics / Jason Bergtold / Efficiency and technology are increasingly important selling points for combine harvesters. Diesel-electric hybrid drives have taken hold in the construction equipment industry, and are providing marketable efficiency benefits for some heavy equipment customers. This thesis explores the technical and economic feasibility of utilizing diesel-electric hybrid drives on AGCO combine harvesters. To determine the technical feasibility of utilizing diesel-electric hybrid drives on AGCO combine harvesters, a search was conducted for prior literature relating to the use of electric drives on other heavy, off-highway equipment. This information, coupled with data provided by experts in the field, was used to determine if electric drives could fulfill the unique requirements of combine harvesters, and be practically utilized for this application. To determine the economic feasibility of utilizing diesel-electric hybrid drives on AGCO combine harvesters, an optimization model was constructed to seek out the most economically viable configuration of electric drives for this application. The model takes in to consideration the different use-cases in which this equipment is expected to perform, as well as the component costs and operating efficiencies of both the drives in place currently and the proposed electric drives. The outcome of the model was then utilized to compare the best-case configuration to the minimum requirement for economic feasibility. The technical feasibility assessment conducted for this thesis led to the conclusion that it would be technically feasible to utilize electric drives on a combine harvester. There are commercially available electric drive components which are suitable for use in the environment that this equipment is expected to operate in, and a prototype combine harvester having electric drives has previously been constructed. The economic feasibility assessment conducted for this thesis revealed that it is not economically feasible to utilize electric drives on AGCO combine harvesters at this time. Under the current circumstances, the most economically viable configuration would take nearly twice the machine’s usable operating life to provide a benefit to a customer from fuel savings. Sensitivity analysis revealed that significant changes in the price of fuel or electric drive components would be necessary to change the outcome of this study.

This paper deals with the application of speed variable pumps in industrial hydraulic systems. The benefit of the natural feedback of the load torque is investigated for the issue of condition monitoring as the development of losses can be taken as evidence of faults. A new approach is proposed to improve the fault detection capabilities by tracking the changes via machine learning techniques. The presented algorithm is an art of adaptive modeling of the torque balance over a range of steady operation in fault free behavior. The aim thereby is to form a numeric reference with acceptable accuracy of the unit used in particular, taking into consideration the manufacturing tolerances and other operation conditions differences. The learned model gives baseline for identification of major possible abnormalities and offers a fundament for fault isolation by continuously estimating and analyzing the deviations.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / The work presented in this thesis forms part of the participation of the University of Stellenbosch in an electric vehicle project. The thesis deals with three aspects of the dynamics and energy management of the electric vehicle. The three aspects that are dealt with are the suspension system of an electric vehicle with in-wheel propulsion, the traction control of an electric vehicle and the energy system of such a vehicle. An investigation is presented in the thesis on the effect the mass of the hub motors has on the safety, stability and comfort of the electric vehicle. The investigation is done through a system frequency analysis and a comparative simulation. A comparison is made between a standard vehicle and a vehicle with in-wheel propulsion. A vehicle model is derived for the simulation of the vehicle. Finally, a few of the results of physical measurements performed are also presented. The traction control requirements of an EV are investigated. A discussion is given on the parts that make up an EV’s traction control system. A few examples of possible traction control systems are given through a step by step evolution of a traction control system. A vehicle model is derived for both static and kinetic friction conditions. The model is used in simulations to illustrate the need for traction control in EV’s. The thesis presents two methods for choosing a battery pack size, in terms of energy capacity etc. The difficulties associated with choosing a battery pack, using each of these methods are given. A battery pack choice for the specific electric vehicle, is presented. The measurements of one of the required charge-discharge cycles are presented to illustrate the charge and discharge curves of the battery cells used. The management of energy flow within the energy system of the EV is crucial, especially if regenerative braking is utilized. This is to protect the battery cells as well as to extend the range of the vehicle. The thesis presents the evaluation of an energy management system (EMS) using ultra capacitors as auxiliary storage device. An electronic load system is designed to simulate the operation of the vehicle motors. The transfer functions for the EMS and load system are derived and used to design the respective control algorithms. The control algorithms were implemented in both simulation as well as a laboratory setup to show the operation of the EMS. A new energy system configuration is presented. The aim of the new configuration is to solve certain problems encountered when implementing a conventional EMS. The operation of the new configuration is discussed. A comparative study is made between the conventional and the new configurations.

The demand for performance and resources that is placed on the system is dictated by the application alone in non-interactive environments, and by a combination of application and user interactions in interactive environments. Understanding user interaction can provide valuable information about which resources will be needed ahead of time. This leads to performance optimizations such as better resource allocations for applications that can utilize a given resource more productively, and transitioning devices to a more appropriate energy performance state before the demand arrives. The challenge is to provide a performance/energy schedule that best matches the task at hand, since keeping the device in one performance level is not energy efficient due to the continually changing demand placed on the device. This dissertation addresses the challenge of designing energy efficient systems by examining the role of user interaction in energy consumption and in providing an energy-performance schedule that adequately accommodates user demand. It is shown that system performance can be tailored to a user's pattern of interaction and it's energy-performance schedule optimized.First, a detailed design of context capture systems in Linux's X-Window System is presented with an evaluation of the associated storage and computation overheads. Due to the overall low complexity of the application window representations, the overheads of computing interaction identifiers and storing a secondary representation of the application interface within the context capture system are likewise low. Additionally, a Microsoft Windows-based context capture system leveraging the Active Accessibility framework is discussed and applied to improving the navigation of cascading pull-down menus.Secondly, this dissertation addresses the application of interaction capture in energy and delay management of Wireless Network Interface Controllers/Cards (WNICs) and hard drives. The Interaction Aware Prediction (IAP) system for WNICs is evaluated showing that the available power modes can be effectively managed to provide energy efficiency while maintaining performance. Similarly, the Interaction Aware Spin-up Prediction (IASP) uses interaction awareness to reduce or eliminate the interactive delays associated with aggressive hard disk energy management.

Great portion of today's industry are <em>Adjustable Speed Drives</em> (<em>ASD's</em>) operated in order to fulfill certain processes. When these processes are critical ones or sensitive to voltage disturbances, that might take place due to inserting high load in an area near to the Point of Common Coupling (<em>PCC</em>) of the process or due to a short term outage, few tens of thousands up to millions of dollars will be lost once such interruptions (voltage sags) take place as a result of the process failure. On the other hand, a distorted voltage waveform at the PCC for some sensitive process might malfunction as a result of the high harmonic content of the voltage waveform. Utilities are required to deliver as pure as possible sinusoidal voltage waveform according to certain limits; thus, they might apply fines against the consumers who are responsible for producing high amounts of current harmonics that affect the voltage wave shape at the <em>PCC</em> in order to force them to improve the consumer's load profile by adding filters at <em>PCC</em> for instance. Utilities are charging the consumers who are drawing power at poor power factor as well. <br /><br /> This thesis presents an <em>ASD</em> retrofitted with a dual-functional piece of hardware connected in series to its <em>DC-link</em> that is capable of handling the previously two mentioned problems. In other words, hardware that is capable of providing <em>voltage sag ride-through</em> during the voltage sag conditions on one side, on the other side, during the normal operating conditions, it is capable to mitigate the harmonic contents of the drawn current by the ASD's rectifier and to improve the power factor. <br /><br /> Survey on voltage sag ride-through for ASD's approaches are presented in the literature has been made. Approaches are classified as the topology utilized; first, topologies that utilizes energy storage elements that store energy to compensate the DC-link voltage with during the voltage sags, second, topologies retrofitting the DC-link itself with additional hardware to compensate the DC-link voltage. The first group is capable to provide voltage compensating during the full outages while the second can't. The presented voltage sag ride-through work of this thesis belongs to the second group. <br /><br /> Boost converter has been used as the hardware to compensate the DC-link voltage because of its simplicity and cheap price. An adaptive linear network (ADALINE) is investigated as the detection system to detect the envelope of the input voltage waveform. Once the envelope of the voltage goes below a certain level, the boost converter is activated to compensate the difference between voltage set point and the actual DC-link voltage. Simulation results supporting the proposed configuration are presented. <br /><br /> A third-harmonic current injection approach is utilized in this work in order to achieve <em>total harmonic distortion</em> (<em>THD</em>) mitigation from 32% to 5. 125% (theoretically). Two third-harmonic current injection networks have been investigated; one utilizes a real resistor, the other utilizes a resistor emulator to reduce the energy dissipated. The proposed controller for the resistor emulator does not require a proportional-integral (PI) controller. <br /><br /> As a result of the common devices between the voltage sag ride-through circuitry and the harmonic mitigation one, they can be integrated together in one circuitry connected in series with the DC-link of the ASD. And hence, the dual functionality of the hardware will be achieved. Simulation results supporting the theoretical results have been presented.

Cette étude vise à comprendre le rôle de l’histoire dans la philosophie de Nietzsche et à faire ressortir son lien étroit avec l’articulation du corps vivant comme fil conducteur philosophique. Notre objectif principal est de montrer comment cette philosophie aphoristique a su maintenir les préoccupations historiographiques de jeunesse en permutant leur sens à l’aune de la pulsionnalité interprétative du corps. Prenant notre départ des considérations critiques écrites lors de son professorat à Bâle, nous démontrons que le sens historique se manifeste alors comme une sensibilité historique déterminée par une saisie intuitive, mais existentiellement difficile, du passé. Nous procédons ensuite à décrire comment le renouveau philosophique de sa période intermédiaire peut être vu comme une réduction pathologique de l’histoire de la métaphysique qui emprunte ses éléments critiques au scepticisme de Michel de Montaigne, à l’évolutionnisme naissant et au développement du néo-kantisme. Cette réduction, qui ramène l’expression des valeurs morales et métaphysiques au corps vécu (Leib). Par sa déconstruction de la subjectivité au profit d’une réalité pulsionnelle primordiale, mais irréductible, nous démontrons ensuite comment Nietzsche a su réinterpréter l’hérédité biologique comme une mémoire physiologique incorporée dont l’expression première est la reconduction de la notion d’espèce à celle de type. Enfin, par un retour à la sensibilité historique et notre analyse du phénomène historique en tant que tel, nous proposons de comprendre l’articulation ultime de la philosophie nietzschéenne comme une philosophie historique qui ne cherche pas à comprendre ou à expliquer le devenir, mais en opérer la synthèse par le truchement de « l’instant décisif ». / This study aims to understand the role played by history in Friedrich Nietzsche’s philosophy and its underappreciated relation to the introduction of the body (Leib) as its philosophical red-thread. Our main goal is to show how his philosophy was able to preserve the historiographical interests on his early period by transforming history’s importance in accordance with the body’s constitutive forces. Starting with his critical discussion of history during his professorship in Basel, we demonstrate how he understood the historical sense as a form of historical sensibility determined by an intuitive yet existentially demanding grasp of the past. We then describe the philosophical renewal of his middle period as a reduction of the history of metaphysics to pathological states that owes much to Michel de Montaigne’s skepticism, nascent evolutionary biology and the burgeoning neo-Kantian movement. By bringing moral and metaphysical values to determinate bodily states, Nietzsche introduces the body as philosophically significant. By a careful reading of contemporary science and its influence on Nietzsche’s thinking, we show how the deconstruction of human subjectivity into its primordial physiological existence culminates in a reinterpretation of biological heredity as a form of incarnate memory, which reduces the concept of biological species to that of morphological types. Finally, we return to our initial discussion of our historical sensibility in order to demonstrate how Nietzsche’s philosophy is through and through historical and seeks not to understand Becoming but to decisively synthesise and decide our historical destiny.

General purpose operating systems have been designed to provide fast, loss-free disk service to all applications. However, multimedia applications are capable of tolerating some data loss, but are very sensitive to variation in disk service timing. Present research efforts to handle multimedia applications assume pessimistic disk behaviour when deciding to admit new multimedia connections so as not to violate the real-time application constraints. However, since multimedia applications are ``soft' real-time applications that can tolerate some loss, we propose an optimistic scheme for admission control which uses average case values for disk access. Typically, disk scheduling mechanisms for multimedia applications reduce disk access times by only trying to minimize movement to subsequent blocks after sequencing based on Earliest Deadline First. We propose to implement a disk scheduling algorithm that uses knowledge of the media stored and permissible loss and jitter for each client, in addition to the physical parameters used by the other scheduling algorithms. We will evaluate our approach by implementing our admission control policy and disk scheduling algorithm in Linux and measuring the quality of various multimedia streams. If successful, the contributions of this thesis are the development of new admission control and flexible disk scheduling algorithm for improved multimedia quality of service.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Includes bibliographical references. / by William Robert Gandler. / M.S.