Dissertations / Theses on the topic 'Inerzia variabile'

Elaborazione di un algoritmo per la stima della curva dell'inerzia e della sua derivata (in caso di inerzia variabile) di un cinematismo a partire dai dati misurati dal controllore relativi a posizione angolare, velocità, accelerazione e corrente. Indagine teorica e sperimentazione su banco di prova con dati reali.

Nel presente lavoro di tesi è stato effettuato lo studio di un impianto di riscaldamento basato su pompa di calore aria-acqua multi-compressore al servizio della palazzina uffici della società Galletti S.p.a. allo scopo di individuare la configurazione idraulica ottimale del circuito di distribuzione che garantisca il miglior compromesso tra le prestazioni energetiche dell’impianto ed il comfort termoigrometrico percepito all’interno dell’edificio. L’analisi sviluppata durante questo lavoro si è basata sui risultati di simulazioni dinamiche condotte per mezzo del software TRNSYS (TRaNsient System Simulation): i modelli implementati all’interno del software hanno permesso di valutare il comportamento del sistema edificio-impianto tenendo conto della reale dinamica del sistema in corrispondenza di fenomeni transitori caratteristici di impianti a pompa di calore: cicli di accensione-spegnimento e cicli di defrost. In particolare, sono state valutate differenti configurazioni del circuito di distribuzione idraulica al fine di trovare la soluzione ottimale per massimizzare le prestazioni energetiche dell’impianto, minimizzare lo stress meccanico della pompa di calore ed ottimizzare il comfort termico interno agli ambienti climatizzati. A tal fine, sono state considerate diverse logiche di gestione della portata d’acqua (fissa o variabile), legate a diversi terminali di emissione (fan-coil dotati di valvole a 3 vie di by-pass o di valvole a 2 vie on-off), ed è stata variata la taglia e la posizione del serbatoio di accumulo inerziale del sistema, allo scopo di investigare l’influenza dell’inerzia termica del circuito sul comportamento dell’impianto.

Dans le cadre des efforts effectués pour la réduction des émissions de CO2 des véhicules automobiles, ce travail présente la conception d'un volant moteur à inertie variable. Initialement, le volant moteur est une inertie située sur le vilebrequin du moteur d'un véhicule. Son rôle dans la chaîne cinématique consiste à filtrer la vitesse du moteur car le couple qu'il génère est très irrégulier dû aux phases de compressions et de combustions. Le principe de variation d'inertie consisterait alors à désolidariser une partie de l'inertie du volant lors des phases d'accélération du véhicule. Le moteur ayant une inertie en moins à mettre en rotation, une économie d'énergie significative pourrait être réalisée. La solution de volant à inertie variable étudiée de deux volants, l'un dit « fixe » complètement solidaire du vilebrequin qui représente alors la partie constante de l'inertie, l'autre « dit mobile » connectable et déconnectable du vilebrequin qui représente alors la partie variable de l'inertie. Deux solutions d'accrochage mécaniques sont présentées, capable de solidariser les volants en rotation malgré l'importance du couple instantané : la première consiste à embrayer le volant mobile sur le volant fixe à l'aide d'une garniture de friction, la seconde utilise un crabot, soit un verrouillage mécanique réalisé avec des dentures. Pour l'embrayage des volants, un actionneur de séparation réluctant à bobinage et un actionneur de plaquage réluctant à aimants sont modélisés analytiquement par des circuits aux reluctances, validés expérimentalement et optimisés. Pour le déplacement du crabot, un actionneur électromagnétique linéaire est dimensionné et validé expérimentalement
Within the framework of the efforts made to reduce the CO2 emission of motor vehicles, this paper presents the conception of a flywheel with a variable inertia. Usually, the flywheel is an inertia standing on the crankshaft of the engine of a vehicle. Its function in the cinematic chain is to filter the speed of the engine because the torque which is generated is very irregular due to the phases of compression and combustion. The principle of the variation of inertia would consist in decreasing a part of the inertia of the flywheel during the phases acceleration of the vehicle. The engine having less inertia to put in rotation, a significant energy saving could be realized. The solution of variable inertia flywheel studied involves two wheels, one called « steady » permanently bound to the crankshaft, which then represents the constant part of the inertia, and the other one called « mobile » that can be connected to and disconnected from the crankshaft which then represents the variable part of the inertia. Two solutions to realize the mechanical binding are presented, capable of keeping the flywheel connected in rotation in spite of the importance of the instant torque : the first one consists in clutching the mobile wheel in the steady one by means of a friction lining, the second uses a dog clutch, which is a mechanical locking realized with a set of teeth. For the clutching of the wheels, a reluctant separation actuator made of coils and a binding actuator made of magnets are analytically modelled with reluctance circuits, then experimentally validated and optimized. For the movement of the dog clutch, a linear electromagnetic actuator is sized and experimentally validated

In regions with increasing penetration of variable-speed wind generators, grid operators are concerned about frequency security as system inertia is decreasing. The partial replacement of conventional plants with modern wind plants may cause system frequency regulation to fall below acceptable levels, especially in isolated power systems. This study investigates the contribution of variable-speed wind generators to short-term frequency support. This contribution is obtained by transiently releasing part of the stored kinetic energy in the turbine blades, namely the inertial response. Some inertial response schemes have been researched to be incorporated as auxiliary loops in the controllers of wind generators. First, we compare the performance of these earlier implementations and identify their shortcomings. Then, we quantify the extractable inertial power from a modern wind turbine, given its power characteristic, equivalent inertia, and prevailing wind condition. From this understanding, a new controller, based on the asynchronous release of kinetic energy, is proposed to achieve a superior, more controllable performance. The controller is composed of a 'detection and triggering' scheme that detects the frequency event, a 'power shaping' function that decides the duration and amount of inertial power released, and a 'rotor speed recovery' scheme that brings the turbine back to its optimal speed which corresponds to maximum power tracking. Time-domain simulations were performed to examine the performance of this controller. Based on its impact on system frequency and wind farm operation, the new controller was compared to earlier implementations of wind plant inertial response. The results show that the proposed controller is capable of bringing together the advantages of the different earlier implementations for better grid integration of wind turbine generators. Its effectiveness in reducing the initial frequency fall after a load-generation mismatch promises significant contribution to system inertia. Its controllable, predictable nature is a distinct advantage that enables grid operators to understand, forecast and quantify the impact of incorporating this controller into grid-connected wind generators.
Dans les régions à forte pénétration d'éoliennes à vitesse variable, les opérateurs de réseau sont concernés par la sécurité de la fréquence lorsque l'inertie du système décroît. La substitution partielle d'usines conventionnelles par des usines éoliennes modernes pourrait causer le réglage de la fréquence du système à chuter sous des niveaux acceptables, surtout dans le cas de systèmes d'alimentation isolés. Cette étude se penche sur comment les éoliennes à vitesse variable peuvent contribuer au support de la fréquence à court terme. Cette contribution est obtenue grâce au relâchement transitoire d'une partie de l'énergie cinétique contenue dans les aubes de turbine, plus spécifiquement la réponse transitoire. Quelque programmes de réponse inertielle ont été étudiés afin d'être incorporés comme boucle auxiliaire dans les contrôles des génératrices à vent. En premier lieu, on compare la performance d'implémentations préexistantes entre-elles afin d'en identifier les défauts respectifs. En second lieu, on quantifie la puissance inertielle capable d'être extraite d'une génératrice à vent moderne tout en prenant en considération les caractéristiques de puissance, son inertie équivalente ainsi que les conditions de vent dominantes. Avec cette notion, un nouveau régulateur qui est basé sur un relâchement non-synchronisé d'énergie cinétique est proposé afin d'obtenir une performance supérieure et plus contrôlable. Le contrôleur est composé d'un programme de «détection et déclenchement» qui détecte la variation de la fréquence, d'une fonction «formatrice de puissance» qui calcule la durée ainsi que la quantité de puissance cinétique relâchée, et d'un programme de «récupération de vitesse du rotor» qui ramène la turbine à sa vitesse optimale qui correspond au suivi de la vitesse maximale. Des simulations dans le domaine du temps ont été effectuées afin d'examiner la performance du régulateur. À partir de son impact sur la fréquence du système et l'opération de plants éolien, le nouveau contrôleur a été comparé aux implémentations antérieures de réponse inertielle d'usines de vent. Les résultats démontrent que le contrôleur proposé est capable d'unifier les avantages des implémentations précédentes afin d'avoir une meilleure intégration des éoliennes. Sa capacité de réduire la chute de fréquence initiale qui suit un décalage au niveau de la génération de charge promet une contribution significative sur l'inertie du système. En fait, sa nature contrôlable et prévisible lui donne un avantage distinct qui permet aux opérateurs de réseau de pouvoir comprendre, prédire et quantifier l'impact potentiel de l'implémentation de ce régulateur dans des génératrices à vent connectées au réseau.

Conventional vehicle suspensions consist of a spring and a damper, while mass is rarely used. A mass, if properly used, can also create a damping-like effect. However, a mass has only one terminal which makes it difficult to be incorporated into a suspension. In order to use a mass to achieve the damping-like effect, a two-terminal mass (TTM) has to be designed. However, most of the reported TTMs are of fixed moment of inertia (TTM-CMI), which limits the further improvement of the suspension performance and responsiveness to changes in environment and driving conditions. In this study, a TTM-based vibration absorber with variable moment of inertia (TTM-VMI) is proposed. The main component of the proposed TTM absorber contains a hydraulic-driven flywheel with sliders. The moment of inertia changes with the positions of the sliders in response to the driving conditions. The performance of the proposed TTM-VMI absorber has been analyzed via dynamics modeling and simulation and further examined by experiments. The analysis results indicate that the TTM-VMI absorber outperforms the TTM-CMI design in terms of body displacement; and ride comfort, tire grip and suspension deflection for zero and impulse inputs with comparable performance for sinusoidal input.

Syfte och frågeställning Syftet med denna studie är att identifiera effekten av svänghjulsträning på styrkerelaterade variabler som påverkar idrottslig prestation genom en sammanställning av befintlig vetenskaplig litteratur. Studiens frågeställning var: (1) Vilken effekt har svänghjulsträning på muskeltillväxt (hypertrofi)? (2) Vilken effekt har svänghjulsträning på utvecklingen av maximal styrka? (3) Vilken effekt har svänghjulsträning på utvecklingen av Power (effektutveckling)? (4) Vilken effekt har svänghjulsträning på horisontell förflyttning? (5) Vilken effekt har svänghjulsträning på vertikal förflyttning? Metod En metaanalys för 15 experimentella studier som uppfyllt urvalskriterierna genomfördes. De inkluderade studierna kvalitetsgranskades med Pedros skala. För att möjliggöra en sammanställning av samtliga resultat analyserades resultaten i dataprogrammet Review Manager version 5.3 med Random effekt modell och presenteras med Forest plots. Jämförelserna gjordes över en period på 4-24 veckor. Resultat Svänghjulsträning under en period av 4-24 veckor visar på en statistisk signifikant utveckling  av muskulär hypertrofi (effektstorlek 0,68), maximal styrka (1,40), Power (1,0), horisontell (0,54) och vertikal förflyttning (0,60). Slutsats Det finns stöd i litteraturen för att friska individer presterar bättre på så väl dynamiska styrketest som funktionella test efter svänghjulsträning. Evidensen är särskilt stark för att svänghjulsträning utvecklar maximal styrka och Power för tränade yngre individer samt i kortare mer intensiva block. Denna metaanalys har bara sammanställt skillnader i prestation före och efter svänghjulsträning och kan därför inte säga om effekten av svänghjulsträning är större än effekten av upprepade mätningar eller annan träning.
Aim The aim of this study was to identify the effect of the flywheel training on strength-related variables that affect athletic performance by compiling existing scientific literature. Research questions: (1) What effect does flywheel training have on muscle growth (hypertrophy)? (2) What effect does flywheel training have on the development of maximum strength? (3) What effect does flywheel training have on the development of Power (effect development)? (4) What effect does flywheel training have on the development of horizontal movement? (5) What effect does flywheel training have on the development of vertical movement? Method A meta-analysis was conducted from 15 experimental studies that met the selection criteria. The quality of included studies was reviewed by Pedro scale. In order to identify possible bias in the selection process a Funnel plot was carried out. To enable the compilation of all results an analyze with Random effect model was carried out with software Review Manager Version 5.3 and presented with Forest plots. Comparisons were made over a period of 4-24 weeks. Results Flywheel training for a period of 4-24 weeks show a statistically significant increase in effect size for muscular hypertrophy (0,49), maximum strength (1,40), Power (1,00), horizontal-(0,54) and vertical movement (0,60). Conclusions There's support in published studies that healthy individuals perform better on dynamic strength tests as wells as functional test after flywheel training. The evidence is particularly strong that flywheel training develops maximum strength and Power in trained younger individuals and in shorter more intensive blocks. This meta-analysis has just compiled the differences in performance before and after flywheel training and therefore cannot say if the effect of flywheel training is greater than the effect of repeated measurements or other exercise.

Ingeniero Civil Eléctrico
Diferentes países alrededor del mundo se han planteado ambiciosos objetivos para alcanzar altos niveles de producción de energía en base a energías renovables en los próximos años. Esta situación, sumada a condiciones favorables desde el punto de vista de costos de inversión tanto para los proyectos de generación fotovoltaica como eólica, lleva a que se espere que ambas tecnologías tengan un rol importante en los sistemas de potencia del futuro. Sin embargo, una alta penetración de energías renovables no convencionales puede afectar el control y estabilidad de un sistema de potencia, especialmente desde el punto de vista de la frecuencia. Esto, ya que la generación variable desplaza generación síncrona convencional. Lo anterior provoca problemas, entre otras cosas, con la inercia del sistema debido a dos factores: 1) las plantas fotovoltaicas no poseen partes rotatorias, por lo tanto no pueden proveer de respuesta inercial durante desbalances de carga-generación y 2) la generación eólica al ser conectada mediante conversor, pierde la respuesta inercial natural asociada a sus partes giratorias. Como consecuencia, mientras más plantas eólicas y solares fotovoltaicas se integren al sistema, más reducida será la inercia del mismo y con esto su capacidad de hacer frente a las desviaciones de frecuencia ante grandes perturbaciones, lo que afecta fuertemente la estabilidad en frecuencia. Es por esto que con el fin de permitir altos niveles de energía renovable no convencional (ERNC) manteniendo la seguridad del sistema, se requiere incluir en el Unit Commitment restricciones adicionales. Los efectos mencionados son relevantes en sistemas de potencia aislados y pequeños. En el caso chileno el Sistema Interconectado del Norte Grande (SING) tiene proyectada una alta penetración de proyectos fotovoltaicos sin inercia. Por lo anterior, este trabajo se enfoca en estudiar la estabilidad de frecuencia del SING proyectado para el año 2017. El objetivo es encontrar funciones que caractericen la respuesta de la frecuencia del sistema frente a desbalances de carga-generación. Para ello, se realizan simulaciones dinámicas frente distintas contingencias en base a un modelo proyectado del SING. Los resultados del estudio indican que a medida que aumenta la generación variable, el sistema ve deteriorada su capacidad de control de frecuencia. Además se concluye una alta correlación entre el porcentaje de generación ERNC y la inercia del sistema y a su vez una estrecha correlación entre el rate of change of frecuency (Rocof) y la inercia del sistema. Esto último permite representar de forma matemática la relación entre el Rocof y la inercia del sistema. Finalmente el trabajo entrega una función por tramos que caracteriza la pendiente de caída de la frecuencia (Rocof), en función del desbalance, para diferentes valores de inercia del sistema. Se prueba la validez de la función obtenida con fallas históricas reales ocurridas en el SING para validar la propuesta. De esta forma se podría incorporar una restricción adicional al Unit Commitment para caracterizar la influencia de una alta penetración de ERNC en la frecuencia del sistema.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Este trabalho propõe um modelo com reversão à média e inércia para taxas de juros e para cargas dos fatores de Nelson e Siegel (1987), e adiciona variáveis macroeconômicas selecionadas. As previsões geradas são comparadas com o Passeio Aleatório e com a metodologia de Diebold e Li (2006).
This work proposes a model with mean reversion and inertia for the yields and the loadings of the Nelson and Siegel (1987) factors, and includes selected macroeconomic variables. The generated forecasts are compared with the Random Walk and the Diebold e Li (2006) methodology.

Le but de ce travail est de définir les règles de synthèse de différentes lois de commande afin de leur donner un caractère robuste. Nous étudions la problématique du contrôle d'un actionneur synchrone en présence d'une charge mécanique. Cette charge est entraînée par un accouplement élastique et présente une valeur d'inertie variable et bornée. La synthèse de correcteurs simples est présentée et des méthodes pour obtenir le meilleur correcteur sur l'intervalle de variation des paramètres sont presentées. Nous avons présenté dans ce travail, les règles de synthèse d'un régulateur PID sur lequel nous avons ajouté une méthode itérative d'optimisation basée sur l'expertise du comportement du système ainsi qu'un algorithme génétique. Cette partie a permis de donner des règles simples de synthèse et de paramétrisation de la méthode d'optimisation afin de trouver les 3 degrés de liberté de correction optimaux. La synthèse de correcteurs dans l'espace d'état a ensuite été abordée en étudiant le meilleur placement de pôle en fonction de l'élasticité et de la variation d'inertie. La méthode de synthèse par optimisation d'un critère quadratique intégrale (LQI) est largement presentée. Cette partie permet de donner les lignes directrices et les critères à choisir pour obtenir un placement de pôle respectant au mieux le cahier des charges et un comportement robuste aux variations de paramètres. L'étude de la méthode LQI à 3 degrés de liberté à permis de lier la valeur des coefficients aux pôles et au comportement du système en boucle fermée. Une deuxième méthode de synthèse par optimisation LQI permet de définir les gains du régulateur à partir d'un placement de pôles souhaité. Toutes ces structures de contrôle ont été vérifiées en simulation en tenant compte du pilotage de la machine synchrone au travers de son convertisseur statique. Les boucles internes de gestion des rapports cycliques et des boucles de courant sont présentées de manière à expliquer certain phénomène et afin de fixer correctement les dynamiques internes souvent négligées. Ces correcteurs ont ensuite été implanté dans un environnement dSPACE, sur un banc d'essai constitué d'un convertisseur MLI, d'un actionneur synchrone autopiloté entraînant une charge mécanique identique au problème évoqué présentant un accouplement élastique et des disques additionnels permettant la variation d'inertie. Une extension vers des correcteurs plus avancés sont présentés en mettant l'accent sur les difficultés qui apparaissent pour la représentation des systèmes (mathématique et forme augmentée pour les approches H1, LMI, réduction de modèle, etc) sur la complexité des méthodes de recherche de solution (Riccati, inégalités matricielles contraintes, etc). Finalement une perspective mélangeant l'effet des correcteurs et des observateurs est brièvement présentée au travers de la méthode LQI et d'un observateur d'état et de perturbation. Des résultats de simulation et d'expérimentation encourageants sont également présentés tout en conservant des règles de synthèse simples et liées à la connaissance du comportement du système.

Cette thèse est consacrée à l’étude du mélange turbulent dans des écoulements à densité variable et à coefficients de transport non uniformes. Nous utilisons un nouveau code de simulation numérique directe (DNS) basé sur une décomposition bidimensionnelle du domaine, capable de prendre en compte la densité variable et les contributions diffusives. Dans un premier temps, nous considérons le cas de la turbulence dans les plasmas faiblement couplés en compression isotrope, qui peuvent subir une dissipation soudaine d’énergie cinétique due à la croissance du coefficient de viscosité par une augmentation de la température. Dans ce cas, en plus des DNS, nous utilisons un modèle spectral basé sur la fermeture Eddy-Damped Quasi-Normal Markovian. On démontre la sensibilité de l’écoulement aux conditions initiales pour une turbulence homogène isotrope et une couche sphérique turbulente. Dans ce dernier cas, nous trouvons aussi la première indication d’un effet de diffusion soudain. L’importance des conditions initiales est également mise en évidence par l’étude de la turbulence homogène stratifiée instable à densité variable. Si les contrastes de densité initiale sont suffisamment forts, les grandes échelles de l’écoulement sont modifiées avec pour conséquence la modification des lois d’échelle des états autosemblables. Enfin, nous considérons une configuration idéalisée d’implosion de fusion par confinement inertiel, avec des effets de densité variable et des coefficients de transport. Pendant la compression, nous mettons en évidence la compétition entre la diffusion moléculaire du plasma, qui est renforcée par l’augmentation de la température, et la diffusion turbulente, qui au contraire diminue en raison de la croissance de la dissipation visqueuse. Dans la dernière phase de l’implosion, nous mettons en évidence un processus de diffusion soudaine, où les couches de mélange sphériques en compression sont rapidement diffusées
This thesis is dedicated to the study of turbulent mixing in flows with variable density and non-uniform transport coefficients. We use a new direct numerical simulation (DNS) code based on a two-dimensional domain decomposition, capable of taking into account variable density and diffusive contributions. At first, we consider the case of turbulence in weakly-coupled plasmas under isotropic compression, which can experience a sudden dissipation of kinetic energy due to the growth of the viscosity coefficient due to temperature increase. In this case, in addition to DNS we use a spectral model based on the Eddy-Damped Quasi-Normal Markovian closure. We evidence the sensitivity of the flow dynamics to initial conditions for homogeneous isotropic turbulence and an inhomogeneous spherical turbulent layer. In the latter case, we find, also, the first hint of a sudden diffusion effect. The importance of initial conditions is also shown in the study of the variable density unstably stratified homogeneous turbulence. If the initial density contrasts are sufficiently strong, the large scales of the flow are modified with the consequent modification of the self-similar scaling laws. Finally, we consider an idealized configuration of inertial confinement fusion implosion, with both variable density and transport coefficients effects. During the compression, we evidence the competition between the plasma molecular diffusion, which is enhanced by the temperature increase, and the turbulent diffusion, which on the contrary decreases due to the increased viscous dissipation. In the last phase of the implosion, we highlight a sudden diffusion process, where compressed spherical mixing layers are quickly diffused

Questa Tesi si occupa di una derivazione di un meccanismo con amplificazione inerziale per lo smorzamento delle vibrazioni, il quale è stato usato come un meccanismo costituente di un oscillatore semplice, ovvero di un modello matematico fondamentale su cui è basata la dinamica strutturale, aumentandogli notevolmente la sua complessità geometrica. Viene studiata la risposta dinamica ottenuta dall’analisi armonica, in quanto lo stesso è soggetto alla forzante passiva. Lo studio del comportamento dinamico ingloba un percorso, il quale parte dalla descrizione matematica dell’equilibrio dinamico, nonché delle condizioni al contorno, tramite l’uso di analisi matriciale delle strutture e del calcolo complesso, e si conclude, derivando le grandezze cinematiche e dinamiche, necessarie affinché si possa determinare, in un modo chiaro e privo di ambiguità, lo stato del sistema dinamico. Il passo successivo risiede nell’analisi analitica e numerica dei risultati ottenuti e anche della visualizzazione grafica ed interpretazione degli stessi. Affinché i risultati possano essere considerati validi, occorre che gli stessi passino la procedura di validazione tramite l’uso degli esempi numerici. Successivamente, i risultati validati vengono confrontati con la stessa tipologia dei risultati derivati per gli oscillatori classici o gli oscillatori di riferimento, il quale comportamento è già noto nell’ambito della dinamica strutturale. La Tesi procede con l’applicazione pratica degli oscillatori per lo smorzamento delle vibrazioni. In particolare si studia la loro capacità di alterare la risposta dinamica complessiva del sistema di cui fanno parte, rispetto al caso in cui la stessa struttura è priva di essi. In fine la Tesi si conclude, mettendo in evidenza i vantaggi e gli svantaggi dell’oscillatore dotato di un meccanismo con amplificazione inerziale rispetto agli altri oscillatori classici.

The thesis parts from the view that statistics starts with data, and starts by introducing the data sets studied: marine benthic species counts and chemical measurements made at a set of sites in the Norwegian Ekofisk oil field, with replicates and annually repeated. An introductory chapter details the sampling procedure and shows with reliability calculations that the (transformed) chemical variables have excellent reliability, whereas the biological variables have poor reliability, except for a small subset of abundant species. Transformed chemical variables are shown to be approximately normal. Bootstrap methods are used to assess whether the biological variables follow a Poisson distribution, and lead to the conclusion that the Poisson distribution must be rejected, except for rare species. A separate chapter details more work on the distribution of the species variables: truncated and zero-inflated Poisson distributions as well as Poisson mixtures are used in order to account for sparseness and overdispersion. Species are thought to respond to environmental variables, and regressions of the abundance of a few selected species onto chemical variables are reported. For rare species, logistic regression and Poisson regression are the tools considered, though there are problems of overdispersion. For abundant species, random coefficient models are needed in order to cope with intraclass correlation. The environmental variables, mainly heavy metals, are highly correlated, leading to multicollinearity problems. The next chapters use a multivariate approach, where all species data is now treated simultaneously. The theory of correspondence analysis is reviewed, and some theoretical results on this method are reported (bounds for singular values, centring matrices). An applied chapter discusses the correspondence analysis of the species data in detail, detects outliers, addresses stability issues, and considers different ways of stacking data matrices to obtain an integrated analysis of several years of data, and to decompose variation into a within-sites and between-sites component. More than 40 % of the total inertia is due to variation within stations. Principal components analysis is used to analyse the set of chemical variables. Attempts are made to integrate the analysis of the biological and chemical variables. A detailed theoretical development shows how continuous variables can be mapped in an optimal manner as supplementary vectors into a correspondence analysis biplot. Geometrical properties are worked out in detail, and measures for the quality of the display are given, whereas artificial data and data from the monitoring survey are used to illustrate the theory developed. The theory of display of supplementary variables in biplots is also worked out in detail for principal component analysis, with attention for the different types of scaling, and optimality of displayed correlations. A theoretical chapter follows that gives an in depth theoretical treatment of canonical correspondence analysis, (linearly constrained correspondence analysis, CCA for short) detailing many mathematical properties and aspects of this multivariate method, such as geometrical properties, biplots, use of generalized inverses, relationships with other methods, etc. Some applications of CCA to the survey data are dealt with in a separate chapter, with their interpretation and indication of the quality of the display of the different matrices involved in the analysis. Weighted principal component analysis of weighted averages is proposed as an alternative for CCA. This leads to a better display of the weighted averages of the species, and in the cases so far studied, also leads to biplots with a higher amount of explained variance for the environmental data. The thesis closes with a bibliography and outlines some suggestions for further research, such as a the generalization of canonical correlation analysis for working with singular covariance matrices, the use partial least squares methods to account for the excess of predictors, and data fusion problems to estimate missing biological data.

There is a trend in Sweden towards increasing the electricity production from renewable energy sources in the electric grid. The increased share of renewables could be seen as essential for Sweden to be able to meet the obligated climate goals. Integration of renewables will enable Sweden to be a progressive part in reducing greenhouse gases and decreasing the global warming. However, one issue with renewable energy sources is the inverter governed production. This, together with the decommission of larger synchronous generators, results in decreasing the inertia and increasing the instability inthe grid.  This thesis is dedicated to elaborating on frequency stability issues and investigating how Variable Speed Wind Turbines (VSWT) could contribute towards stabilized operation when included in frequency support services.  The study is generated through an extensive research process where focus areas are identified. Questions are purposed and then discussed through interviews with experienced people in the field. Estimated power production series from a wind turbine park (WTP) are applied in a constructed model to study the possibilities appearing when  including VSWTs in frequency support services. The income generated from including VSWTs in different regulation power market services is with the model compared against solely procuring the production capacity on the day ahead market. The studied frequency support services are then compared altogether to generate favorable solutions. The study examines both economic as well as technical features of the inclusion of VSWTs in frequency support services.  Results found in the study were that inclusion of wind turbines for power regulation purposes could be seen as increasingly manageable and needed in the electric grid. The maturity of technical solutions alongwith a transition in the regulation power market could be observed as leading factors. The diversification of regulation abilities and the increasing economic incentives in the regulation power market was also found to be important reasons for including wind turbines in the regulation power market. In the study, it was also found thataggregating the power production from several VSWT could increase the ability to deliver the studied services.  It was concluded that inclusion of VSWT in the frequency containment reserve during disturbed operation for down-regulation purposes as well as the fast frequency reserve was the most promising frequency support products for the inclusion of wind turbines. When including battery energy storages and to a larger part managing the durability demands for the services then the frequency contain reserve for normal operation and the frequency containment reserve for disturbed operation for upregulation purposes could be observed as preferable alternatives. Regulation abilities were concluded as achievable with the use of pitch and torque regulation techniques available in the variable speed wind turbine.

Plusieurs stratégies sans liens apparents coexistent pour mettre en œuvre les algorithmes de résolution de problèmes d'inclusion monotone dans les espaces hilbertiens. Nous proposons un cadre synthétique permettant d'englober diverses approches algorithmiques pour la construction de point fixe, clarifions et généralisons leur théorie asymptotique, et concevons de nouveaux schémas itératifs pour l'analyse non linéaire et l'optimisation convexe. Notre méthodologie, qui est ancrée sur un modèle de compositions de quasicontractions moyennées, nous permet de faire avancer sur plusieurs fronts la théorie des algorithmes de point fixe et d'impacter leurs domaines d'applications. Des exemples numériques sont fournis dans le contexte de la restauration d'image, où nous proposons un nouveau point de vue pour la formulation des problèmes variationnels
Several apparently unrelated strategies coexist to implement algorithms for solving monotone inclusions in Hilbert spaces. We propose a synthetic framework for fixed point construction which makes it possible to capture various algorithmic approaches, clarify and generalize their asymptotic behavior, and design new iterative schemes for nonlinear analysis and convex optimization. Our methodology, which is anchored on an averaged quasinonexpansive operator composition model, allows us to advance the theory of fixed point algorithms on several fronts, and to impact their application fields. Numerical examples are provided in the context of image restoration, where we propose a new viewpoint on the formulation of variational problems

System identification is used in engineering sciences to build mathematical models from data. A common issue in system identification problems is that the true inputs to the system are not fully known. In this thesis, existing approaches to unknown input problems are classified and some of their properties are analyzed.  A new indirect framework is proposed to treat system identification problems with unknown inputs. The effects of the unknown inputs are assumed to be measured through possibly unknown dynamics. Furthermore, the measurements may also be dependent on other known or measured inputs and can in these cases be called indirect input measurements. Typically, these indirect input measurements can arise when a subsystem of a larger system is of interest and only a limited set of sensors is available. Two examples are when it is desired to estimate parts of a mechanical system or parts of a dynamic network without full knowledge of the signals in the system. The input measurements can be used to eliminate the unknown inputs from a mathematical model of the system through algebraic manipulations. The resulting indirect model structure only depends on known and measured signals and can be used to estimate the desired dynamics or properties. The effects of using the input measurements are analyzed in terms of identifiability, consistency and variance properties. It is shown that cancelation of shared dynamics can occur and that the resulting estimation problem is similar to errors-in-variables and closed-loop estimation problems because of the noisy inputs used in the model. In fact, the indirect framework unifies a number of already existing system identification problems that are contained as special cases. For completeness, an instrumental variable method is proposed as one possibility for estimating the indirect model. It is shown that multiple datasets can be used to overcome certain identifiability issues and two approaches, the multi-stage and the joint identification approach, are suggested to utilize multiple datasets for estimation of models. Furthermore, the benefits of using the indirect model in filtering and for control synthesis are briefly discussed.  To show the applicability, the framework is applied to the roll dynamics of a ship for tracking of the loading conditions. The roll dynamics is very sensitive to changes in these conditions and a worst-case scenario is that the ship will capsize.  It is assumed that only motion measurements from an inertial measurement unit (IMU) together with measurements of the rudder angle are available. The true inputs are thus not available, but the measurements from the IMU can be used to form an indirect model from a well-established ship model. It is shown that only a subset of the unknown parameters can be estimated simultaneously. Data was collected in experiments with a scale ship model in a basin and the joint identification approach was selected for this application due to the properties of the model. The approach was applied to the collected data and gave promising results.
Till skillnad från många andra industrier där avancerade styrsystem har haft en omfattande utveckling under de senaste decennierna så har styrsystem för skepps- och marinindustrin inte alls utvecklats i samma utsträckning. Det är framförallt under de senaste 10 åren som lagkrav och stigande driftskostnader har ökat intresset för effektivitet och säkerhet genom användning av styrsystem. Rederier och den marina industrin är nu intresserade av hur de avancerade styrsystem som används inom andra områden kan tillämpas för marina ändamål. Huvudmålet är typiskt att minska den totala energianvändningen, och därmed också bränsleförbrukningen, genom att hela tiden planera om hur skeppet skall användas med hjälp av ny information samt styra skeppet och dess ingående system på ett sätt som maximerar effektiviteten. För många av dessa avancerade styrsystem är det grundläggande att ha en god förståelse för beteendet hos det systemet som skall styras. Ofta används matematiska modeller av systemet för detta ändamål. Sådana modeller kan skapas genom att observera hur systemet reagerar på yttre påverkan och använda dessa observationer för att finna eller skatta den modell som bäst beskriver observationerna. Observationerna är mätningar som görs med så kallade sensorer och tekniken att skapa modeller från mätningarna kallas för systemidentifiering. Detta är i grunden ett utmanande problem och det kan försvåras ytterligare om de sensorer som behövs inte finns tillgängliga eller är för dyra att installera. I denna avhandling föreslås en ny teknik där de mätningar som finns tillgängliga används på ett nytt och annorlunda sätt. Detta kan minska mängden nödvändiga sensorer eller möjliggöra användandet av alternativa sensorer i modell-framtagningen. Med hjälp av denna nya teknik kan enkla sensorer användas för att skatta en matematisk modell för en del av skeppet på ett sätt som inte är möjligt med traditionella metoder. Genom att skatta denna modell kan fysikaliska egenskaper hos skeppet, så som dess massa och hur massan är fördelad över skeppet, övervakas för att upptäcka förändringar. Just dessa två egenskaper har stor inverkan på hur skeppet beter sig och om skeppet är fellastat kan det i värsta fall kapsejsa. Vetskapen om dessa fysikaliska egenskaper kan alltså utöver effektivisering användas för att varna besättningen eller påverka styrsystemen så att farliga manövrar undviks. För att visa att tekniken fungerar i verkligheten har den använts på mätningar som har samlats in från ett skalenligt modellskepp. Experimenten utfördes i bassäng och resultaten visar att tekniken fungerar. Denna nya teknik är inte specifik för marint bruk utan kan också vara användbar i andra typer av tillämpningar. Även i dessa tillämpningar möjliggörs användandet av färre eller alternativa sensorer för att skatta modeller. Tekniken kan vara speciellt användbar när en modell av ett system eller process som verkar i ett nätverk av många system är av intresse, något som också diskuteras i avhandlingen.

Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.

碩士
崑山科技大學
機械工程研究所
95
In a machine motive delivery system, the motor or engine is familiar motive sources, the organization that particularly is a fixed importation to turn soon, it design to carry to all will install up the importation a certainly inertia flywheel, storing the kinetic energy, equilibrium motive by this. However some changes to turn soon the organization on the design the importation to turn soon and then is not an operation under the condition that certainly turn soon, if the importation bar of the organization have to in the pole play acceleration or the deceleration, settling the flywheel of the inertia will can't satisfy the dissimilarity turns soon with carry of request. So this text mainly takes the concept of the inertia of the change flywheel quantity as the point of departure, in order to synthesize the new variable and inertia flywheel organization, the purpose make the new organization produced be able to have original settle the function of the inertia flywheel, at combine with the motive source up can satisfy the dissimilarity to turn soon carry with the dissimilarity the request of the exercise characteristic, then let the motive machine be able to reach the multi-function usage. The thesis introduces the foreign variable and inertia flywheel organization structure and principle first, due to currently domestic study concerning variable and inertia organization also not much, so this study with the Laser of the CD driver reads and write the head and the motorcycle Continuously Variable Transmission(CVT) its front pully to make to move the principle for concept foundation, design a prototype that the viable organization is the variable and inertia flywheel organization, and analyze the Topological structure characteristic of the prototype organization, then joins the design need that this variable and inertia organization needs, be the foundation that the structure synthesizes, immediately after makes use of the Yan, H. S., ﹝3﹞﹝9﹞ to creative organization design method as foundation, the design limits the condition, and join Hsu,.﹝7﹞ to allow the organization structure design learns lift it (degree of motion ) of in order to lend support to, the idea will be able to move the degree by 2 one by one inquire into to 5th to synthesize to match to design the mission and demanding and variable and inertia flywheel organization, finally produce three bars three deal with contact with four variable and inertia flywheel organizations that deal with contacts of four bars. For making the new organization satisfied the actual need, this study also to creative of organization, present with a design, by use SolidEdge software view and imitate it with the 3 D software(Inventor) exercise process, finally carry on the exercise and dynamical analysis, by canning normally make to move while having no interference condition with identifying the variable and inertia flywheel.

碩士
國立臺灣大學
土木工程學研究所
94
The goal of the present thesis is to investigate shallow water flows propagating through a medium of variable porosity. One particular case considered is a dam-break wave partially reflected and transmitted at a vertical porous boundary. The contents of this thesis include the derivation of governing equations, experimental methods, image analysis and the numerical modeling. In the derivation of the governing equations we will introduce how to use the Hamilton’s principle of least action to account for added mass effects. Image processing will offer some sample way to solve the radial distortion problem in 2D. Besides, we will show how to use piston to do dam-break experiment without using a sluice gate. Finally, we use experimental and numerical results to characterize the influence of inertia and added mass on the wave propagation.

碩士
臺灣大學
機械工程學研究所
98
The purpose of this study is to analyze and to develop the possible design concepts for the hybrid power systems with variable inertia flywheel. Through this study, we are able to synthesize and evaluate the hybrid systems and to compose of the hybrid power system with 1 engine, 1 flywheel and 1 engine, 1 flywheel, 1 electric machine. In the study, firstly, the “functional power graph” is developed, which can transform the traditional mechanical diagrams into a simplified graph for representing its mechanical structure and function. The atlases of structural graphs and functional power graph are built by a systematical design method, which includes all possible concepts of the hybrid power systems. The system for studying is 1 motor, 1 variable inertia flywheel which is used as the energy storage device, a planetary gear set, and a set of actuators. Then, the kinematic and kinetic equations of the hybrid power system are developed in order to establish the relationships of the speed and torque of all elements, and the specific speed and torque of the output can be found by using the software “ADVISOR” in various operation modes. Thus, with a prescribed mechanical brake energy recovery system model and a control model, a comprehensive analysis can be achieved. Finally, various driving modes, such as ECE, ECE+EUDC and New York Bus driving mode are investigated in order to demonstrate the characteristics of the hybrid power system. The numerical results show and conclude the effectiveness of the variable inertia flywheel, and the improvement on the efficiency of hybrid power systems.

碩士
國立中山大學
機械與機電工程學系研究所
98
The effect of variable inertia flywheel (VIF) on the driving speed fluctuation, and residual vibration of high speed machine systems is investigated in this thesis. Different variable inertia flywheels are proposed to an experimental purpose roller gear cam system and a commercial super high speed paper box folding machine. The effects of time varying inertia and intermittent cam motion on the dynamic responses of different high speed cam droved mechanism systems are simulated numerically. The nonlinear time varied system models are derived by applying the Lagrange’s equation and torque-equilibrium equations. The dynamic responses of these two nonlinear systems under different operating speed are simulated by employing the 4th order Runge-Kutta method. The effects of VIF parameters on the dynamic responses, i.e. the output precision, variation of motor speed, and torque, during the active and dwell periods for these two systems are studied and discussed. The difference between the dynamic responses of constant inertia and variable inertia flywheel systems are also compared. The feasibility and effectiveness of depression of driving speed and torque fluctuations by analying variable inertia flywheel has also been demonstrated.

碩士
大葉大學
機械工程研究所碩士班
96
Internal-combustion engines have been used for over one hundred years. Though high-performance internal-combustion engines have been developed constantly, but their thermal efficiency is unable to break through the limit of innate restriction. Combining the Stirling engine and the internal-combustion engine might be able to attain the goal of reducing pollution. The Stirling engine is one kind of heat machinery with a fixed amount of output power. It is very difficult to control its output power. The design of applying the variable crank and the flywheel with variable mass moment of inertia on the Stirling engine makes its output power can be easily controlled. This study made an analysis of dynamics by using different types of variable crank and stroke. Getting result curves of position, velocity and acceleration. According to the analysis curve, we can see the advantage and the faults of this machinery, and using the result compare to a reciprocating engine as a standard. This study use the reciprocating engine as a standard and made an analysis of dynamics by using different types of variable crank and stroke. Getting the result curves of position, velocity and acceleration. According to the analysis curves, we can see the advantage and the faults of this machinery. Design flywheel with variable mass moment of inertia to increase stirling engines environmental adaption. Using the spring control the clutch, and set the clutch into high speed and low speed two steps of mass moment of inertia. Flywheel function is set by rotational speed. When the speed is low, the variable mass moment of inertia is bigger than the high speed. This study uses ADAMS for simulate analysis. By high speed computing, we can find the problems and solved them before the products has been completed.

博士
國立交通大學
機械工程學系
99
Clinical gait analysis is the process of using quantitative information, including kinematic, kinetic and anthropometric data to aid in understanding the etiology of gait abnormalities. It has been widely used in the diagnosis of patients with neuromusculoskeletal pathology, subsequent planning and evaluation of treatment. In human motion analysis, the kinetic data are usually obtained from forceplates mounted on the ground. Therefore, in situ calibration of the forceplate is necessary to improve the accuracy of the measured ground reaction force (GRF) and center of pressure (COP). The current study developed a small device (160 x 88 x 43 cm) with a mass of 50 kg, equipped with auxiliary wheels and fixing suction pads for rapid deployment and easy set-up. A PC-based controller enabled quick movement and accurate positioning of the applied force to the calibration point. After correction by an artificial neural network (ANN) trained with the static data from 121 points, the mean errors for the vertical GRF were all reduced from a maximum of 0.38 % to less than 0.00 %. Those for the X and Y components of COP were all reduced from a maximum of about 1.37 and 1.15 mm to less than 0.02 and 0.04 mm, respectively. For dynamic calibration, the mean errors for the vertical GRF were reduced from a maximum of -0.19 % to less than -0.03 %, while those for the X and Y components of COP were reduced from a maximum of -0.50 and 0.95 mm to less than -0.01 and -0.11 mm. The results suggested that the calibration device with the ANN method will be useful for obtaining more accurate GRF and COP measurements. Thereafter, the device was used to calibrate our newly developed instrumented treadmill to measure GRF on the treadmill during successive cycles of gait. By the same error analysis and neural network methods, the measured GRF and center of pressure (COP) can be calibrated to reduce the errors. The results of calibration indicated that mean errors for the vertical GRF from a maximum of 0.82 % to less than 0.01 %, while those for the X and Y components of COP were reduced from a maximum of 1.59 and 0.71 mm to less than 0.07 and -0.06 mm. Correct anthropometric data is also needed for accurate calculation of the motion data. Currently, anthropometric data are mostly obtained from studies on adult cadavers because no data exist for the children between 6 to 12 years of age. However, methods using cadavers or invasive techniques are not suitable for children. Noninvasive methods are either too difficult or too expensive to be used routinely in clinical settings. The current study therefore aimed to develop a noninvasive, fast, cost-effective and accurate method for the estimation of the anthropometric data of subjects with different ages. We proposed an optimization-based, non-invasive, radiation-free method for estimating subject-specific body segment inertial properties (BSIPs) by using a motion capture system and two forceplates. Twelve healthy adult subjects (24?b2 y/o; 69?b8 kg; 178?b5 cm) and twenty children (9?b3 yrs; 31?b10 kg; 130?b9 cm) were recruited in this study. Firstly, a three-dimensional custom-made model of the human body was developed for the simulation of the segment geometry; the estimation of the mass, center of mass and second moment of inertia of the segments and the whole body. Then the subject was asked to stand in twenty different postures for static test, and to perform squatting for dynamic test. The static and dynamic tests were used to customize the model to the subject with optimization method, and the subject-specific anthropometric data were the calculated consequently. The performance of the current method was compared to two commonly used predictive methods (Dempter, 1955 and Cheng ,2000) in terms of the errors of the calculated COP and ground reaction force (GRF) using the corresponding predicted BSIPs. During stationary standing postures, the mean COP errors were less than 4 and 5 mm for the child and adult groups respectively, while those from the existing comparative methods ranged from 11 to 19 mm and 15 to 25 mm for these two groups respectively. During dynamic activities, mean COP errors from the current method were less than 7.9 and 9.4 mm for the child and adult groups respectively, while those from the existing methods ranged from 24.8 to 31.1 mm and 20.6 to 27.9 mm for these two groups respectively. In evaluation of the accuracy in vertical GRF during dynamic test, the mean error of vertical GRF from the current method showed similar values to the existing methods. The results showed that the current method was capable of producing estimates of subject-specific BSIPs that predicted accurately the important variables in human motion analysis during static and dynamic activities. In conclusion, this optimization-based and accurate method was developed for the estimation of the anthropometric data of subjects with different age groups for clinical gait or motion analysis. Being non-invasive and using standard motion laboratory equipment, the current method would be useful for building up the anthropometric data of adults and children in Taiwan.

碩士
中華科技大學
飛機系統工程研究所
104
The Variable Frequency Starter Generator (VFSG) is the newest electrical power system used in Boeing 787 engine. With high technology VFSG delivers so many benefits to the engine, and in our experiment we using VFSG technology program our Flywheel energy storage. Flywheel energy storage works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. The capture of energy produced at one time for use at a later time. Over the last century, the energy storage industry has continued to evolve and adapt to changing energy requirements and advances in technology. And today there are so many types of energy storage such as Chemical Energy storage, Electrochemical energy storage, Electrical energy storage, Thermal energy storage, and Mechanical energy storage. Flywheel Energy Storage Device is a Mechanical energy storage device that harness rotational energy to deliver instantaneous electricity.

Dissertação de Mestrado Integrado em Engenharia Electrotécnica e de Computadores apresentada à Faculdade de Ciências e Tecnologia
Com aumento da penetração das energias renováveis intermitentes e devido à natureza da ligação dos seus ativos de geração à rede, têm-se observado um decréscimo da inércia global dos sistemas de energia elétrica, que pode levar a problemas no seu normal funcionamento. O sistema português não é exceção, sendo até um dos países mais avançado no que toca a tecnologias renováveis. Este trabalho investiga quais os impactos da atual penetração das VRE no sistema português e analisa ainda como se comportará inercialmente o sistema, no período de 2020-2040, segundo possíveis cenários de desenvolvimento da capacidade instalada em Portugal. Conclui-se que, se medidas preventivas não forem colocadas em prática, o sistema poderá sofrer com instabilidade. Um conjunto de soluções para possíveis problemas que possam surgir é investigada, para que a estabilidade do sistema seja mantida, sendo que a maioria foi implementada com sucesso.Com aumento da penetração das energias renováveis intermitentes e devido à natureza da ligação dos seus ativos de geração à rede, têm-se observado um decréscimo da inércia global dos sistemas de energia elétrica, que pode levar a problemas no seu normal funcionamento. O sistema português não é exceção, sendo até um dos países mais avançado no que toca a tecnologias renováveis. Este trabalho investiga quais os impactos da atual penetração das VRE no sistema português e analisa ainda como se comportará inercialmente o sistema, no período de 2020-2040, segundo possíveis cenários de desenvolvimento da capacidade instalada em Portugal. Conclui-se que, se medidas preventivas não forem colocadas em prática, o sistema poderá sofrer com instabilidade. Um conjunto de soluções para possíveis problemas que possam surgir é investigada, para que a estabilidade do sistema seja mantida, sendo que a maioria foi implementada com sucesso.Com aumento da penetração das energias renováveis intermitentes e devido à natureza da ligação dos seus ativos de geração à rede, têm-se observado um decréscimo da inércia global dos sistemas de energia elétrica, que pode levar a problemas no seu normal funcionamento. O sistema português não é exceção, sendo até um dos países mais avançado no que toca a tecnologias renováveis. Este trabalho investiga quais os impactos da atual penetração das VRE no sistema português e analisa ainda como se comportará inercialmente o sistema, no período de 2020-2040, segundo possíveis cenários de desenvolvimento da capacidade instalada em Portugal. Conclui-se que, se medidas preventivas não forem colocadas em prática, o sistema poderá sofrer com instabilidade. Um conjunto de soluções para possíveis problemas que possam surgir é investigada, para que a estabilidade do sistema seja mantida, sendo que a maioria foi implementada com sucesso.
With the increasing penetration of intermittent renewable energies and due to the nature of the connection of its generation assets to the grid, there has been a decrease in the global inertia of power, which can lead to problems in their normal operation. The portuguese power system is no exception, being one of the most advanced countries in terms of renewable technologies. This work investigates the impacts of the current VRE penetration of the VRE in the Portuguese system and also analyzes its possible inertial behavior from 2020 to 2040, according to possible scenarios for the development of installed capacity in Portugal. It can be concluded that, if preventive measures put into practice, the power system will suffer with frequency instability. A set of solutions for possible problems that may arise is investigated, so that the stability of the system is maintained, given that the majority were implemented with success.With the increasing penetration of intermittent renewable energies and due to the nature of the connection of its generation assets to the grid, there has been a decrease in the global inertia of power, which can lead to problems in their normal operation. The portuguese power system is no exception, being one of the most advanced countries in terms of renewable technologies. This work investigates the impacts of the current VRE penetration of the VRE in the Portuguese system and also analyzes its possible inertial behavior from 2020 to 2040, according to possible scenarios for the development of installed capacity in Portugal. It can be concluded that, if preventive measures put into practice, the power system will suffer with frequency instability. A set of solutions for possible problems that may arise is investigated, so that the stability of the system is maintained, given that the majority were implemented with success.With the increasing penetration of intermittent renewable energies and due to the nature of the connection of its generation assets to the grid, there has been a decrease in the global inertia of power, which can lead to problems in their normal operation. The portuguese power system is no exception, being one of the most advanced countries in terms of renewable technologies. This work investigates the impacts of the current VRE penetration of the VRE in the Portuguese system and also analyzes its possible inertial behavior from 2020 to 2040, according to possible scenarios for the development of installed capacity in Portugal. It can be concluded that, if preventive measures put into practice, the power system will suffer with frequency instability. A set of solutions for possible problems that may arise is investigated, so that the stability of the system is maintained, given that the majority were implemented with success.

Text in Afrikaans
Summaries in English and Afrikaans
Key terms in English and Afrikaans
Die doel van die studie was om organisasietraagheid as stremmende fenomeen te konseptualiseer en die manifestasie daarvan te ondersoek binne 'n tipiese werkorganisasie. Aandag is gegee aan organisasietransformasie binne die raamwerk van 'n diagnostiese model vir organisasie- en individuele ontwikkeling. Die empiriese studie bevestig die manifestasie van organisasietraagheid ten opsigte van die teikenorganisasie. Resultate bevestig dat respondente ten gunste is van veranderingsinisiatiewe, maar ondergeskiktes toon 'n emstige behoefte aan leierskap. Dit blyk ook dat die organisasie nie die vermoe het om vinnig op omgewingsveranderings te reageer nie. Gesonde bestuurspraktyke word nie gevolg nie en kreatiwiteit word nie aangemoedig nie. By ondergeskiktes bestaan ook twyfel oor veranderingsagente se vermoe om verandering te fasiliteer.
The purpose of the study was to conceptualise organisation inertia as a retarding phenomenon and to investigate its manifestation within a typical work organisation. Attention was given to organisational and individual development within the framework of a diagnostic model. The empirical study focussed on the manifestation of organisational inertia within the target organisation. Results confirmed that respondents are in favour of change initiatives but that the stimulation thereof do not exist. Subordinates are not encouraged to show creativity. The organisation demonstrates an incapability to respond to environmental changes and reflects a non-existence of healthy management practices. Little trust exists in the capability of change agents to facilitate change.
Economics and Management Sciences
M.A. (Industrial Psychology)

The theoretical part of the thesis includes introduction of Riemann integral and its qualities, introduction of function of more variables, introduction of double and triple Riemann integral and physical applications of integral. The practical part includes derivation of general area formulas for different shapes and volume formulas for different solids, in some examples there are shown different ways of solution. The practical part also includes the use of Riemann integral for the determination of centre of mass, of statical moments and moments of inertia of objects.