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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.
71

Evolution de modèles différentiels de systèmes complexes concrets par programmation génétique / Evolution of differential models for concrete complex systems through genetic programming / Evolução de modelos diferenciais para sistemas complexos concretos por programação genética

Santos Peretta, Igor 21 September 2015 (has links)
Un système est défini par les entités et leurs interrelations dans un environnement qui est déterminé par une limite arbitraire. Les systèmes complexes présentent un comportement émergent sans un contrôleur central. Les systèmes concrets désignent ceux qui sont observables dans la réalité. Un modèle nous permet de comprendre, de contrôler et de prédire le comportement du système. Un modèle différentiel à partir d'un système pourrait être compris comme une sorte de loi physique sous-jacent représenté par l'un ou d'un ensemble d'équations différentielles. Ce travail vise à étudier et mettre en œuvre des méthodes pour effectuer la modélisation des systèmes automatisée par l'ordinateur. Cette thèse pourrait être divisée en trois étapes principales, ainsi: (1) le développement d'un solveur numérique automatisé par l'ordinateur pour les équations différentielles linéaires, partielles ou ordinaires, sur la base de la formulation de matrice pour une personnalisation propre de la méthode Ritz-Galerkin; (2) la proposition d'un schème de score d'adaptation qui bénéficie du solveur numérique développé pour guider l'évolution des modèles différentiels pour les systèmes complexes concrets; (3) une implémentation préliminaire d'une application de programmation génétique pour effectuer la modélisation des systèmes automatisée par l'ordinateur. Dans la première étape, il est montré comment le solveur proposé utilise les polynômes de Jacobi orthogonaux comme base complète pour la méthode de Galerkin et comment le solveur traite des conditions auxiliaires de plusieurs types. Solutions à approximations polynomiales sont ensuite réalisés pour plusieurs types des équations différentielles partielles linéaires, y compris les problèmes hyperboliques, paraboliques et elliptiques. Dans la deuxième étape, le schème de score d'adaptation proposé est conçu pour exploiter certaines caractéristiques du solveur proposé et d'effectuer l'approximation polynômiale par morceaux afin d'évaluer les individus différentiels à partir d'une population fournie par l'algorithme évolutionnaire. Enfin, une mise en œuvre préliminaire d'une application GP est présentée et certaines questions sont discutées afin de permettre une meilleure compréhension de la modélisation des systèmes automatisée par l'ordinateur. Indications pour certains sujets prometteurs pour la continuation de futures recherches sont également abordées dans ce travail, y compris la façon d'étendre ce travail à certaines classes d'équations différentielles partielles non-linéaires. / A system is defined by its entities and their interrelations in an environment which is determined by an arbitrary boundary. Complex systems exhibit emergent behaviour without a central controller. Concrete systems designate the ones observable in reality. A model allows us to understand, to control and to predict behaviour of the system. A differential model from a system could be understood as some sort of underlying physical law depicted by either one or a set of differential equations. This work aims to investigate and implement methods to perform computer-automated system modelling. This thesis could be divided into three main stages: (1) developments of a computer-automated numerical solver for linear differential equations, partial or ordinary, based on the matrix formulation for an own customization of the Ritz-Galerkin method; (2) proposition of a fitness evaluation scheme which benefits from the developed numerical solver to guide evolution of differential models for concrete complex systems; (3) preliminary implementations of a genetic programming application to perform computer-automated system modelling. In the first stage, it is shown how the proposed solver uses Jacobi orthogonal polynomials as a complete basis for the Galerkin method and how the solver deals with auxiliary conditions of several types. Polynomial approximate solutions are achieved for several types of linear partial differential equations, including hyperbolic, parabolic and elliptic problems. In the second stage, the proposed fitness evaluation scheme is developed to exploit some characteristics from the proposed solver and to perform piecewise polynomial approximations in order to evaluate differential individuals from a given evolutionary algorithm population. Finally, a preliminary implementation of a genetic programming application is presented and some issues are discussed to enable a better understanding of computer-automated system modelling. Indications for some promising subjects for future continuation researches are also addressed here, as how to expand this work to some classes of non-linear partial differential equations.
72

Conception multidisciplinaire de microsystèmes autonomes / Multidisciplinary design of autonomous microsystems

Dupé, Valérie 28 November 2011 (has links)
Toute action naturelle crée de l’énergie perdue qui pourrait être exploitée pour alimenter nos appareils électriques et mobiles. Nos environnements physiques disposent d’un nombre élevé de micro-sources d’énergies ; certes chacune est de faible puissance, mais leur multiplicité pourrait s’avérer significative, notamment dans le cadre du fonctionnement de microsystèmes.C’est le principe précédent qui a conduit nos travaux sur la problématique de la conception de microsystèmes autonomes. Ainsi, pour être innovante, l’ingénierie de microsystèmes doit à la fois s’appuyer sur la culture de l’électronique, de la mécanique mais aussi de l’énergétique. Le processus de conception est fortement pluridisciplinaire et son efficacité réside dans la capacité à mettre en œuvre des méthodologies et des outils :- de conception collaborative,- de capitalisation des connaissances techniques, - d’ingénierie multi-physique,- d’ingénierie intégrée.Sur le base de ces fondamentaux, nous avons développé un outil d’aide à la conception. La méthodologie sous-jacente permet :1- l’analyse et la structuration d’un problème de conception d’un microsystème autonome : cette phase conduit l’identification, la description fonctionnelle et environnementale du système et de son environnement.2- la modélisation des connaissances : une analyse architecturale conduit à la description des composants et des interactions liées au microsystème (directement ou indirectement) puis à la modélisation des comportements,3- la qualification énergétique et le couplage physique : la réutilisation structurée des modèles de connaissances est pilotée pour coupler les modèles physiques et décrire les sources, les puits et les mécanismes énergétiques des environnements,4- la conduite de la recherche de concepts innovants : la base de connaissances, les critères de qualification et la description fonctionnelle préalablement construits sont agencés dans une seule méthode de conception virtuelle pour rechercher des concepts de solutions innovants,5- le pré-dimensionnement : tout en assurant l’intégration des outils spécialisés de simulation (méthode des éléments finis et simulation fonctionnelle), le pré-dimensionnement de microsystèmes autonomes est supportée selon un schéma synthétique, assurant un raisonnement abductif (ou bottom-up)La conjonction des raisonnements physiques, l’intégration des méthodes et des cultures métiers, l’exploration virtuelle des espaces de solutions et la modélisation constituent les bases d’un nouveau moyen d’aide à la conception de microsystèmes autonomes. Cette approche a été déployée pour la conception d’un capteur piézoélectrique autonome. / Any natural action creates lost energy which could be exploited to supply our electrical and mobile appliance. Our physical environments have a high number of micro-energy sources. Admittedly, each one provides low power but their multiplicity could be significant, in particular within the framework of the microsystem operation.The previous observation guided our works towards the problematic of autonomous microsystem design. Thus, to be innovative, microsystems engineering must lean on electronic, mechanical and energy domains. The design process is highly multidisciplinary and its efficiency depends on the ability to implement methods and tools:- of collaborative design- of capitalization of technical knowledge- of multiphysic engineering- of integrated design.Based on these fundamentals, we developed a design support tool. The underlying methodology enables:1- the design problem analysis and structuring of an autonomous microsystem: this phase leads to the identification and functional and environmental description of the system and its environment2- the knowledge modelling: an architectural analysis gives the description of components and interactions related to the microsystem (directly or indirectly). Then, it leads to a behaviour modelling.3- the energy qualification and physical coupling: the structured reuse of knowledge models is guided to couple physical models and describe the sources, sinks and the energy mechanism of the environment.4- the control of innovative concept search: the knowledge base, qualification criteria and functional description, previously constructed, are combined in an unique virtual design approach dedicated to search innovative concepts as a solution5- the predimensioning: this phase ensures the integration of specific simulation tools (finite elements method and functional simulation). The predimensioning of autonomous microsystems is supported by a synthetic scheme based on an abductive reasoning (bottom-up).The combination of physical reasoning, the integration of methods and engineering domains, the virtual exploration of solution spaces and the modelling represent a new way to support autonomous microsystem design. This approach was applied to the design of an autonomous piezoelectric sensor.
73

Simulation multi-moteurs multi-niveaux pour la validation des spécifications système et optimisation de la consommation / Multi-engine multi-level simulation for system specification validation and power consumption optimization

Li, Fangyan 29 March 2016 (has links)
Ce travail vise la modélisation au niveau système, en langage SystemC-AMS, et la simulation d'un émetteur-récepteur au standard Bluetooth Low Energy (BLE). L'objectif est d'analyser la relation entre les performances, en termes de BER et la consommation d'énergie du transceiver. Le temps de simulation d’un tel système, à partir de cas d’étude (use case) réaliste, est un facteur clé pour le développement d’une telle plateforme. De plus, afin d’obtenir des résultats de simulation le plus précis possible, les modèles « haut niveau » doivent être raffinés à partir de modèles plus bas niveau où de mesure. L'approche dite Meet-in-the-Middle, associée à la méthode de modélisation équivalente en Bande Base (BBE, BaseBand Equivalent), a été choisie pour atteindre les deux conditions requises, à savoir temps de simulation « faible » et précision des résultats. Une simulation globale d'un système de BLE est obtenue en intégrant le modèle de l'émetteur-récepteur dans une plateforme existante développée en SystemC-TLM. La simulation est basée sur un système de communication de deux dispositifs BLE, en utilisant différents scénarios (différents cas d'utilisation de BLE). Dans un premier temps nous avons modélisé et validé chaque bloc d’un transceiver BT. Devant le temps de simulation prohibitif, les blocs RF sont réécrits en utilisant la méthodologie BB, puis raffinés afin de prendre en compte les non-linéarités qui vont impacter le couple consommation, BER. Chaque circuit (chaque modèle) est vérifié séparément, puis une première simulation système (point à point entre un émetteur et un récepteur) est effectuée / This work aims at system-level modelling a defined transceiver for Bluetooth Low energy (BLE) system using SystemC-AMS. The goal is to analyze the relationship between the transceiver performance and the accurate energy consumption. This requires the transceiver model contains system-level simulation speed and the low-level design block power consumption and other RF specifications. The Meet-in-the-Middle approach and the Baseband Equivalent method are chosen to achieve the two requirements above. A global simulation of a complete BLE system is achieved by integrating the transceiver model into a SystemC-TLM described BLE system model which contains the higher-than-PHY levels. The simulation is based on a two BLE devices communication system and is run with different BLE use cases. The transceiver Bit-Error-Rate and the energy estimation are obtained at the end of the simulation. First, we modelled and validated each block of a BT transceiver. In front of the prohibitive simulation time, the RF blocks are rewritten by using the BBE methodology, and then refined in order to take into account the non-linearities, which are going to impact the couple consumption, BER. Each circuit (each model) is separately verified, and then a first BLE system simulation (point-to-point between a transmitter and a receiver) has been executed. Finally, the BER is finally estimated. This platform fulfills our expectations, the simulation time is suitable and the results have been validated with the circuit measurement offered by Riviera Waves Company. Finally, two versions of the same transceiver architecture are modelled, simulated and compared
74

Optimisation of charging strategies and energy storage operation for a solar driven charging station

Gong, Jindan January 2019 (has links)
The Swedish energy sector is undergoing transformational changes. Along with a rapid growth of renewables and a shift towards electromobility, the transformation is expected to bring challenges to the power system in terms of grid instability and capacity deficiency. Integrating distributed renewable electricity production into the electric vehicle (EV) charging infrastructure is a promising solution to overcome those challenges. The feasibility of implementing such a charging infrastructure system in northern Sweden is however uncertain, as the solar resources are scarce in the long winter period. This study aims to maximise the value of a solar powered EV charging station, placed in a workplace environment in Umeå. An integrated system model of the charging station is developed, comprising separate models of a solar PV system, a battery energy storage system (BESS), the workplace EV fleet and the building Växthuset, onto which the charging station will be installed. Three scenarios are developed to study the charging station’s system performance under different EV charging strategies and BESS dispatch strategies. Two additional scenarios are developed to study the potential grid services that the charging station can provide in the winter period. A techno-economic assessment is performed on each scenario’s simulation results, to measure their effect on the charging station’s value. It involves analysing the charging station’s profitability and how well the BESS is utilised by the end of a ten-year project period. The charging station’s grid impact is further assessed by its self-consumption of solar power, peak power demand and the grid energy exchange. The assessed charging station values indicate that the overall grid impact was reduced with dynamic EV charging strategies and that the BESS capacity utilisation was strongly influenced by its dispatch strategy. The charging station further implied a net capital loss under the explored scenarios, even while the dynamic charging strategies brought by a slightly increased economic value. Moreover, the studied winter scenarios showed a great potential for the charging station to provide ancillary services to the local distribution grid while maintaining an efficient BESS capacity utilisation. The winter period’s peak power demand was significantly reduced by optimising the BESS operation to shift peaks in the building’s load profile, and peaks caused by the additional EV charging demand and the EV heaters, to off-peak hours. On this basis, future research is recommended for improved simulations of the charging station operation and to study additional value-added features that the solar driven charging station can bring. / Sveriges energisystem genomgår en omfattande omställning. Förändringar i form av en ökad andel förnybar elproduktion och elektrifieringen av transportsektorn förväntas medföra stora utmaningar för elsystemets nätstabilitet och överföringskapacitet. Att integrera in distribuerad, förnybar elproduktion som en del av laddinfrastrukturen för elfordon ställer sig som en lovande lösning för att möta de väntande utmaningarna. Möjligheterna att tillämpa en sådan lösning i norra Sverige är däremot mindre självklara, då solresurserna är knappa under vintertid. Det här examensarbetet syftar till att maximera nyttan av en soldriven laddstation för elbilar, placerad på ett arbetsplatsområde i Umeå. En integrerad energisystemmodell av laddstationen har skapats, bestående av systemmodeller av solpaneler, ett batterienergilager, arbetsplatsens elbilsflotta samt byggnaden Växthuset, som laddstationen ska anslutas till. Tre scenarier har utformats för att undersöka hur laddstationens prestanda förändras beroende på olika laddstrategier för elbilarna och batterienergilagrets styrning. Ytterligare två scenarier har utvecklats för att utforska möjliga nättjänster som laddstationen kan bistå med under vintertid. Laddstationens värde har vidare bedömts utifrån systemets prestanda i de olika scenarierna. Bedömningen grundar sig på laddstationens lönsamhet och hur välutnyttjat batterienergilagret är efter en kalkylperiod på 10 år, samt på specifika påverkansfaktorer på elnätet. Faktorerna omfattar konsumtionen av egenproducerad el, toppeffektuttaget och nätöverföringarna orsakade av laddstationen. Från värderingen av laddstationen framgår det att de dynamiska laddstrategierna ledde till en, överlag, minskad påverkan på elnätet samt att styrningen av batterienergilagret hade stor inverkan på dess utnyttjandegrad. Laddstationens nettonuvärde förblev negativt i de tre scenarierna, även om de dynamiska laddstrategierna, ökade dess ekonomiska värde till en viss del. Vidare tyder simuleringen av vinterscenarierna på att det finns en stor potential för laddstationen att erbjuda tjänster för lokalnätet och samtidigt nyttiggöra sig av batterienergilagret. Växthusets toppeffektuttag reducerades märkbart genom att optimera batteristyrningen till att flytta effekttoppar orsakade av Växthusets ellastkurva eller elbilarnas laddning och uppvärmning, till de timmar där lasten var lägre. Med detta i bakgrund föreslås vidare studier som fokuserar på den integrerade energisystemmodellen för att förbättra simuleringarna, samt att undersöka möjligheterna till att erbjuda fler nättjänster, som ökar laddstationens mervärde.
75

Heat atlas of Gotland : A GIS-based support tool for modelling the heat sector.

Segerström, Hugo January 2023 (has links)
With sharp climate goals to be climate neutral by 2045, Sweden needs to rapidly change the present energy system. The Swedish government has assigned Gotland as a pilot area for the energy transition, due to its geographical constrains as an island, and because of the major structural changes planned for Gotland’s energy supply and industrial establishment. These changes create the opportunity to build a more flexible, efficient, and robust energy system. To support the transition, IVL Swedish Environmental Research institute has initiated the GOT Heat project. This thesis contributes to the GOT Heat project by developing a GIS model that represent the heat sector of Gotland. The model has been developed in parallel with a TIMES model. The purpose of the GIS model is to be used as a heat atlas and to support the TIMES model of Gotland’s energy system by spatial visualization and knowledge. The GIS model was successfully developed and utilized to enhance the representation of Gotland’s energy system within the TIMES model. Data from Boverket, Lantmäteriet, Energimyndigheten and companies has been collected, processed for the development of the GIS model. The incorporation of spatial knowledge and visualization of the heat sector through the GIS model is expected to improve the overall outcomes of the TIMES model. The heat atlas also proved to be a valuable support tool, enabling the visualization of excess heat potentials within the heat sector. This visualization provides insights into potential opportunities for industrial and sector coupling, which would lead to more efficient utilization of excess heat.
76

Open Source Model of the Nordic Power System for EU Project Spine

Satheeskumar, Aravind January 2020 (has links)
Decision problems in operation and planning of power systems often rely on large-scale models and data sets. Lack of historical power flow data due to regulatory restrictions often limits researchers to study the system with aggregated network models. Aggregated data from the electricity market operators (Nordpool in the Nordics) and the Transmission System Operator (TSO) (from ENTSO-E) are openly available, and can be used to study the power flow and exchanges between different regions but do not directly provide information about intra-region flows. This project builds upon the Nordic 490 system, a previously built model of the Nordic power system. The main objective of this work is to improve the existing open source power flow model of the Nordic power system, in order to become in turn available for the multi-energy modelling and simulation software Spine. The N490 model generates a model of the Nordic power system consisting of various nodes/buses which represent substations at different voltage levels. Then, it distributes the aggregated production, consumption and power exchange data from Nordpool to the various buses. In this project, different possible improvements are evaluated for the model, aiming at estimating a set of network parameters that minimize the errors between the calculated inter-region flows and the ones from the open data repositories. The different improvements which are evaluated are the following. Firstly, the load distribution is modified and reassigned to match the regional electricity consumption. The generators and wind farms are then reallocated to different bus based on their bidding region and proximity to the bus. The databases are improved and the power balance relation modified. Transmission line parameters are then investigated, first to standard recommended values and then by solving an optimisation problem formulated to extract the parameters from the market data. Finally, the model is also tested with wind and solar generation modelled as a generator rather than as a negative load. / Beslutsproblem gällande drift och planering av kraftsystemet baseras ofta på storskaliga modeller och datamängder. Bristen på historiska data gällande effektflöden beror på säkerhetsrestriktioner vilket begränsar forskare till att enbart studera aggregerade nätverksmodeller. Det finns tillgängliga aggregerade data från den nordiska elmarknadsplatsen Nordpool och organisationen ENTSO-E som kan användas för att studera effektflöden mellan olika regioner, dock finns det inte direkta data för flöden inom regionerna. Det här projektet bygger på det nordiska 490-systemet, en tidigare byggd modell av det nordiska kraftsystemet. Huvudsyftet med detta arbete är att förbättra den existerande effektflödesmodellen av det nordiska kraftsystemet, för att i sin tur bli tillgänglig för multienergimodelleringar och simuleringsprogramvaran Spine. N490-modellen genererar en modell för det nordiska kraftsystemet som innehåller olika noder som presenterar ställverk med olika spänningsnivåer och modellen ger också aggregerade data för produktion, konsumtion och effektutbyte mellan de olika noderna från Nordpool. I detta projekt utvärderades olika möjliga förbättringar för modellen som syftar till att uppskatta nätverkets parametrar som kan minimera felen mellan beräkningar av flöde inom regionen och data från öppna datalagringskällor. Följande förbättringar gjordes: Först har lastens fördelning modifierats och ändrats för att matcha den regionala elkonsumtionen. Generatorer och vindkraftsparker allokerades till olika noder baserad på elhandelsområden och närhet till noderna. Databasen förbättrades för att erhålla en bättre effektbalans per område. Kraftledningarnas parametrar ändrades först till rekommenderade standardvärden, vilka sedan förbättrades genom att formulera ett optimeringsproblem för att extrahera parametrarna från markandsdata. Slutligen testades modellen genom att presentera vind- och sol-produktion som generatorer istället för som negativ förbrukning.
77

Performance of Bearing rotor system under various operating conditions

Abbas Shafiee (18863803) 22 June 2024 (has links)
<p dir="ltr">Rolling element bearings (REBs) are common components in rotating equipment. They are used to carry loads and allow for rotation and misalignments with minimal friction. There exists a wide variety of ball and roller bearings that are suited for a wide variety of applications. All varieties of REBs operate with the same fundamental principles: force transferred from the shaft is applied to the inner race of a bearing, distributed among the rolling elements, and passed on through the outer race to the bearing housing. Load distribution among the rolling elements and the dynamic performance of the bearing is dependent on the bearing’s specifications and operating conditions. Bearing-housing and inner race-shaft fit classifications also control the bearing radial internal clearance (RIC), which eventually affects the bearing performance and load transferred to the housing.</p><p dir="ltr">This thesis experimentally and analytically investigates the load distribution and dynamic performance of rolling elements and investigates roller slip, tilt, and skew in a spherical roller bearing (SRB) under various combinations of loads and speeds. In order to have better insight into the effect of flexible housing and shaft on load distribution and dynamics of REBs, it was experimentally investigated the variation of inner race-shaft and outer race-housing interfaces on load and pressure maps at the bearing-housing interface for four different varieties of rolling element bearing: deep groove ball bearings, angular contact ball bearings, cylindrical roller bearings, and spherical roller bearings. Moreover, an integrated rotor-bearing housing system model developed to examine the behaviors of the rotor, bearing, and housing operating under various conditions.</p><p dir="ltr">In order to gain a deeper understanding of the dynamic behavior of REBs, a full six degree of freedom SRB dynamic model was developed in MSC ADAMS software. C++ based ADAMS/Solver subroutines, called dynamic bearing model (DBM), were developed and incorporated in ADAMS to compute reaction forces and moments in a rolling element bearing. DBM is based on the discrete element method (DEM), which assumes each of the bearing elements (i.e., rolling elements, cage, inner race, and outer race) to be a rigid body with six degrees-of freedom (DOF) in a three-dimensional space. A novel test rig (spherical roller bearing test rig, SRBTR) was also designed and developed to investigate load distribution and roller slip, tilt, and skew in an SRB. The test rig utilized a double-row SRB and was designed to allow for direct visual access to each row using a high-speed camera. The dynamic behavior of the rollers was corroborated with the developed analytical model. The experimental and analytical results indicate that the roller tilt angle increases with axial load, remains constant with speed, and decreases with increasing radial load when the roller is located in the load zone. Furthermore, roller skew in the load zone increases with axial load and shaft speed; however, it decreases with the radial load. The results indicate that when the radial-to-axial load ratio is greater than 4, roller tilt and skew are minimized. Due to roller intermittent slip and roller cage pocket collision in the unload zone, tilt and skew become unpredictable. The magnitude of the tilt and skew in the unload zone is directly related to the roller-race and roller-cage pocket clearances, respectively. Another test rig (pressure mapping test rig, PMTR) was designed to solely investigate how bearing-housing and inner race-shaft interfaces affect the load distribution in REBs. Thin film pressure sensors were utilized and placed around the perimeter of the test bearings inside of a housing to experimentally evaluate the pressure distribution between REBs and a housing under different loads and bearing-shaft and bearing-housing interfaces. Pressure map results were used to evaluate the effect of radial internal clearance on the load distribution of different bearing types. Pressure map results confirmed that the amplitude of load variation reduces with the bearing internal clearance. The thin film sensor system was also used to investigate the circumferential load distribution on the housing.</p><p dir="ltr">Previous ADAMS bearing models have assumed the bearing outer race to be fixed to the ground and the bearing inner race to be attached to a rigid shaft. In order to develop a more realistic and versatile bearing simulation tool, ADAMS bearing models were combined with flexible housings and rotor. To achieve an integrated rotor-bearing housing system model, the ADAMS bearing model was coupled through a set of interface points using component-mode-synthesis (CMS) for the rotor and housing model. The bearing outer races were discretized into multiple nodes to compute the force and deformation at the bearing housing conformal contact as well as to minimize the computational requirements associated with the conformal contact problems. The integrated model was then utilized to investigate the effects of rotor flexibility in the bearing rotor system and the effect of bearing clearance and housing clearance on bearing dynamics. It was demonstrated that the flexibility of the rotor has a significant effect on bearing element motion and dynamics. The results also indicated that depending on the bearing type, the shaft deflection can induce a moment within the bearing that is not readily identifiable from elementary theory. The results showed that the flexible housing undergoes deformations that create ovality in the bearing housing, thus affecting bearing dynamics. The model was also used to investigate bearing performance in a miniature wind turbine main shaft, utilizing a combination of SRB and cylindrical roller bearing (CRB) ADAMS models. Results suggest that the axial-to-radial load ratio should be less than the tangent of the SRB contact angle to avoid premature failure due to rollers sliding in the SRB as well as detrimental parallel misalignment in the CRB.</p>
78

Architecture Design and Interoperability Analysisof a SCADA System for the Power Network Control and Management / Arkitekturdesign och interoperabilitetsanalys avett SCADA-system för kraftsystemstyrning

Albiol Graullera, Pablo January 2017 (has links)
SCADA-system (Supervisory Control and Data Acquisition) har under de senaste decennierna använts i stor utsträckning, med utmärkta resultat för nätverksdrift och -förvaltning. Kunder ställer emellertid krav på att SCADA-system ska kunna integrera externa komponenter för att möjliggöra utveckling av befintliga och nya affärsprocesser. Det innebär att dessa system utvecklas från en monolitisk infrastruktur till en löst kopplad och flexibel arkitektur. Således har nya behov uppstått för att förbättra systemets interoperabilitet, minska komplexiteten och förbättra underhållet. Föreliggande masterprojekt presenterar ett ramverk för att förutsäga systems interoperabilitetet (IPF); ett ramverk som stöder arkitekturprocessen under de tidiga stadierna av produktutveckling. Vidare har arbetet undersökt några alternativa arkitekturer, vilka har modellerats och verifierats med hjälp av ovannämnda ramverk. En första konceptuell arkitektur har utvecklats för att förbättra interoperabiliteten hos interna system, för att reducera kopplingen mellan det grundläggande SCADA-systemet och Energy Management-systemet (EMS). Därefter genererades en andra arkitektur som möjliggör integration av externa komponenter för att främja den externa interoperabiliteten. Resultat visar att de föreslagna arkitekturerna är korrekta (enligt IPF) och systemets driftskompatibilitet förbättras. Vidare förefaller den slutligt föreslagna lösningen vara mindre komplex än den nuvarande arkitekturen på lång sikt, men det skulle behövas en större insats och väsentliga förändringar för att uppgradera systemarkitekturen. / SCADA (Supervisory Control and Data Acquisition) systems have been widely used during the last decades delivering excellent results for the power network operation and management. However, some current customer requirements are for SCADA systems to integrate external components in order to perform advanced power network studies and develop both existing and new business processes. This novel viewpoint will make these systems evolve from a monolithic infrastructure towards a loosely coupled and flexible architecture. Hence, new needs have arisen with the aim of improving the system interoperability, reducing the complexity and enhancing the maintainability. This master´s thesis project presents an Interoperability Prediction Framework (IPF), that supports the architecture design process during the early stages of product development. In addition, this work has also investigated some alternative architectures, which have been modelled and verified using the previously mentioned framework. A first conceptual architecture has been designed to improve the internal system interoperability, reducing the coupling between the basic SCADA and the Energy Management System (EMS). Later, a second architecture that allows the integration of external components has been introduced to promote the external interoperability. Results show that the proposed architectures are correct (according to the IPF) and the interoperability of the system is improved. Furthermore, initial conclusions suggest that the final proposed solution would be less complex than the current architecture in the long term, although a large effort and substantial changes would be needed to upgrade the system architecture.

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