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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.
151

Formal Verification Of Analog And Mixed Signal Designs Using Simulation Traces

Lata, Kusum 01 1900 (has links) (PDF)
The conventional approach to validate the analog and mixed signal designs utilizes extensive SPICE-level simulations. The main challenge in this approach is to know when all important corner cases have been simulated. An alternate approach is to use the formal verification techniques. Formal verification techniques have gained wide spread popularity in the digital design domain; but in case of analog and mixed signal designs, a large number of test scenarios need to be designed to generate sufficient simulation traces to test out all the specified system behaviours. Analog and mixed signal designs can be formally modeled as hybrid systems and therefore techniques used for formal analysis and verification of hybrid systems can be applied to the analog and mixed signal designs. Generally, formal verification tools for hybrid systems work at the abstract level where we model the systems in terms of differential equations or algebraic equations. However the analog and mixed signal system designers are very comfortable in designing the circuits at the transistor level. To bridge the gap between abstraction level verification and the designs validation which has been implemented at the transistor level, the very important issue we need to address is: Can we formally verify the circuits at the transistor level itself? For this we have proposed a framework for doing the formal verification of analog and mixed signal designs using SPICE simulation traces in one of the hybrid systems formal verification tools (i.e. Checkmate from CMU). An extension to a formal verification approach of hybrid systems is proposed to verify analog and mixed signal (AMS) designs. AMS designs can be formally modeled as hybrid systems and therefore lend themselves to the formal analysis and verification techniques applied to hybrid systems. The proposed approach employs simulation traces obtained from an actual design implementation of AMS circuit blocks (for example, in the form of SPICE netlists) to carry out formal analysis and verification. This enables the same platform used for formally validating an abstract model of an AMS design to be also used for validating its different refinements and design implementation, thereby providing a simple route to formal verification at different levels of implementation. Our approach has been illustrated through the case studies using simulation traces form the different frameworks i.e. Simulink/Stateflow framework and the SPICE simulation traces. We demonstrate the feasibility of our approach around the Checkmate and the case studies for hybrid systems and the analog and mixed signal designs.
152

Interaction entre yOgg1, une ADN glycosylase de la voie BER, et l’ADN polymérase réplicative Polε chez Saccharomyces cerevisiae / yOgg1, a Saccharomyces cerevisiae bifunctional DNA glycosylase involved in base excision repair of oxidative DNA damage, interacts with the replicative DNA polymerase, Polε

Essalhi, Kadija 12 December 2013 (has links)
Les dommages oxydatifs de l’ADN sont impliqués dans les processus pathologiques que sont le cancer, les maladies neurodégénératives ou le vieillissement. Ces dommages résultent en partie de l’action des espèces réactives de l’oxygène (ERO), qui proviennent du métabolisme cellulaire ou d’agents exogènes (physiques ou chimiques), et qui conduisent à différents types de lésions parmi lesquelles l’oxydation des bases de l’ADN (8-oxoguanine, 8-oxoG) ou la formation de sites abasiques AP (apurique/apyrimidique). Ces lésions, qui si elles ne sont pas éliminées conduisent à des processus de mutagenèse ou de mort cellulaire, sont prises en charge spécifiquement par le système de réparation de l’ADN par excision de base ou BER. Le BER est initié par l’action d’une ADN glycosylase, telles que la 8-oxoG-ADN glycosylase (Ogg1) chargée d’éliminer la 8-oxoG, une lésion très abondante. Une étude par « double-hybride » initiatrice de ce projet a révélé l’existence d’une interaction in vivo chez S. cerevisiae entre la protéine yOgg1 et la sous-unité catalytique de l’ADN polymérase réplicative Polε (yPol2), également impliquée dans la voie BER chez la levure. Nos travaux démontrent que yOgg1 et yPol2 interagissent bien physiquement entre elles et de façon spécifique. Une étude par troncations et mutagenèse dirigée nous a permis d’identifier le domaine 3’→5’ exonucléase de yPol2 comme faisant partie de la forme tronquée minimale de yPol2 capable d’interagir avec yOgg1. La poche du site actif de yOgg1 et/ou son voisinage immédiat pourrait contenir pour partie le site d’interaction pour yPol2. Nous observons d’ailleurs une corrélation nette entre l’activité de yOgg1 et sa capacité à interagir avec yPol2 dans la levure. De même, l’activité 3’→5’ exonucléase de yPol2 pourrait être liée à son interaction avec yOgg1. D’un point de vue fonctionnel, yPol2 stimulerait l’activité AP lyase de yOgg1 et le couplage entre l’activité ADN glycosylase et AP lyase de l’enzyme, permettant ainsi une meilleure coordination de l’étape d’excision du nucléoside endommagé et l’étape de resynthèse de l’ADN dans la voie BER. / Oxidative DNA damages are involved in pathological processes such as cancer, neurodegenerative diseases and aging. Part of these damages results from the action of reactive oxygen species (ROS), which are produced by cellular metabolism or (physical or chemical) exogenous agents. They lead to different types of DNA lesions including DNA base oxidation (8-oxoguanine, 8-oxoG) and abasic site formation (AP, apuric/apyrimidic). If not removed, these lesions lead to mutagenesis or cell death. Most of base lesions are dealt specifically by the base excision repair (BER) pathway. BER is initiated by a DNA glycosylase, such as 8-oxoG-DNA glycosylase (Ogg1) which is responsible for the removal of 8-oxoG. In previous unpublished work, a yeast two-hybrid study revealed the existence in S. cerevisiae of an interaction between yOgg1 and the catalytic subunit of the replicative DNA polymerase Polε (yPol2), also involved in the BER pathway in eukaryotes. Our work shows that yOgg1 and yPol2 physically and specifically interact with each other. Truncation and site-directed mutagenesis studies allowed us to identify the 3 ' → 5' exonuclease activity domain of yPol2 as part of the minimal form of yPol2 still able to interact with yOgg1. The active site of yOgg1 and/or its immediate vicinity may contain part of its interaction domain with yPol2. Besides, we observe a clear correlation between yOgg1 catalytic activity and its ability to interact with yPol2 in vivo. Similarly, the 3'→5' exonuclease activity of yPol2 could be useful to its interaction with yOgg1. From a functional point of view, yPol2 stimulates in vitro the AP lyase activity of yOgg1 and the coupling of both DNA glycosylase and AP lyase enzyme activity. The interaction yOgg1/yPol2 could allow a better coordination of damaged nucleoside excision and DNA re-synthesis steps in BER.
153

Procesy řízení v energetických systémech s alternativními zdroji energie / Control Processes in Energy Systems with Alternative Power Sources

Morávek, Jan January 2017 (has links)
The dissertation is an publication summary focused on the field of management processes in renewable energy systems, mathematical models and optimization possibilities for large and small scale photovoltaic systems. The articles were published in foreign impacted and reviewd journals and indexed proceedings of foreign and domestic conferences. The main results of the dissertation are the design, configuration and realization of the hybrid energy system with subsequent optimization. Using the data from the laboratory system, a mathematical model was compiled and subsequently validated in the Matlab/Simulink environment for a hybrid energy system with accumulation. The options for power production optimization with photovoltaic sources are based on both operational measurements (for commercial applications) and on the analysis of power flow controllers to optimize the~energy balance (for small scale applications in private buildings).
154

Ostrovní systémy / Autonomous energy systems

Dolinský, Filip January 2018 (has links)
Master thesis deals with usage issues of autonomous, self-sufficient and decentralized systems. In the first part convectional and experimental sources for autonomous systems are disclosed. Second chapter deals with accumulation of electrical and thermal energy and possibilities of applications. 3rd part is focused on pilot project realized for autonomous and smart systems, which were built in last years. In the 4th chapter electrical and thermal energy consumption curves are made on daily and monthly basis for 4 type objects. In the fifth part issue of autonomy is explained, and for type buildings solutions are made with additional return on investment. The last chapter is focused on calculation of thermal accumulator and briefly discloses small district heating.
155

Řízení toků energie v energetickém systému s více akumulačními jednotkami / Implementation of control algorithm in application with several accumulation systems

Klusáček, Jan January 2020 (has links)
Rozptýlená výroba elektrické energie využívající obnovitelné zdroje, jako je sluneční energie, přispívá ke snížení emisí skleníkových plynů. Z hlediska provozu distribuční soustavy je také výhodné, aby energie byla primárně spotřebována v místě výroby. To je částečně možné přizpůsobením spotřeby, ale především využitím akumulačních systémů. V této práci je představen hybridní systém složený z fotovoltaické elektrárny, akumulátoru elektrické energie a akumulátoru tepelné energie. Výběr a parametry všech částí hybridního systému jsou popsány v práci. Akumulátor elektrické energie je navržen a sestaven z LiNiMnCoO2 článků a řídícího systému zajišťujícího bezpečný provoz. Řídicí systém akumulátoru (BMS) zajistí odpojení baterie, pokud je překročen některý z provozních parametrů baterie. Návrh baterie i sestavy je popsán v práci. Akumulátor tepelné energie sestává z výkonového spínače a nádrže na teplou vodu s topnou patronou pro odporový ohřev vody. Na základě rešerše komerčně používaných zařízení pro regulaci příkonu byly definovány jejich nedostatky a na základě nich bylo navrženo optimální řešení. Řešení spočívá v použití komerčního polovodičového spínacího prvku. Pro tento výkonový spínací prvek byla vytvořena zpětnovazební řídící smyčka s regulátorem výkonu, který byl implementován v prostředí softwaru LabVIEW. V práci je také uveden postup návrhu chladiče spínacího prvku a LCL filtru, který je klíčový pro splnění požadavků elektromagnetické kompatibility. V druhé části práce je popsán návrh nadřazeného řídícího algoritmu, jehož úkolem je řídit výkonové toky v hybridním systému tak, aby byly splněny požadavky definované jak uživatelem, tak i okamžitým stavem akumulátorů. Algoritmus byl implementován v prostředí LabVIEW. Funkčnost celého systému byla ověřena měřením v laboratorních podmínkách. Z výsledků plyne, že nadřazený řídící algoritmus funguje správně. Řídící smyčka tepelného akumulátoru je stabilní a reguluje zátěž na požadovanou hodnotu. Přidanou hodnotou je kratší reakční doba na změnu toku výkonu oproti hybridnímu měniči a díky tomu dochází k minimalizaci přetoků elektrické energie do distribuční sítě. Na práci je možné navázat rozšířením stávajícího algoritmu o možnost řízení/ovládání více typů akumulačních jednotek a generátorů nebo implementováním odlišných strategií řízení.
156

Provozní parametry FV panelů pracujících v hybridních energetických systémech – porovnání / Operating parameters of the PV modules operating in hybrid energy systems - comparison

Jílek, Milan January 2015 (has links)
The master’s thesis deals with the principle of the photoelectric effect, the composition of the photovoltaic cell and different types of solar panels. Here is described the principle of converting wind energy into electricity. This master’s thesis describes reasons for using of the hybrid system. The next section describes the measurement system which is used to measure real operating statuses. The last section is an analysis of measured values and there are listed factors influencing the design of hybrid power system.
157

The use of a holistic machine simulation for the development of hydraulic hybrid modules to reduce transient engine-out emissions

Brinkschulte, Lars, Pult, Felix, Geimer, Marcus 25 June 2020 (has links)
In contrast to constant operating states, particle and NOx emissions of internal combustion engines are significantly higher during transient operating states, which occur repeatedly at working cycles of mobile machines. This paper therefore deals with the conception, development and testing of hydraulic hybrid systems to reduce these emissions by phlegmatization of the engine. A wheel loader with its machine-typical working cycle serves as an example for the investigation of the benefits of such a system. Therefore, model based development techniques are used. In a holistic machine simulation, four different typical wheel loader cycles were carried out and the optimum size of the hydraulic accumulator for the hybrid system is identified by a parameter variation. The lowest emitted emissions and the smallest construction dimensions are the key elements for the accumulator selection. With an optimal hydraulic accumulator, a reduction in particle emissions of up to 29.4 % is achieved in one of the cycles investigated.
158

DrillBeyond: Processing Multi-Result Open World SQL Queries

Eberius, Julian, Thiele, Maik, Braunschweig, Katrin, Lehner, Wolfgang 11 July 2022 (has links)
In a traditional relational database management system, queries can only be defined over attributes defined in the schema, but are guaranteed to give single, definitive answer structured exactly as specified in the query. In contrast, an information retrieval system allows the user to pose queries without knowledge of a schema, but the result will be a top-k list of possible answers, with no guarantees about the structure or content of the retrieved documents. In this paper, we present DrillBeyond, a novel IR/RDBMS hybrid system, in which the user seamlessly queries a relational database together with a large corpus of tables extracted from a web crawl. The system allows full SQL queries over the relational database, but additionally allows the user to use arbitrary additional attributes in the query that need not to be defined in the schema. The system then processes this semi-specified query by computing a top-k list of possible query evaluations, each based on different candidate web data sources, thus mixing properties of RDBMS and IR systems. We design a novel plan operator that encapsulates a web data retrieval and matching system and allows direct integration of such systems into relational query processing. We then present methods for efficiently processing multiple variants of a query, by producing plans that are optimized for large invariant intermediate results that can be reused between multiple query evaluations. We demonstrate the viability of the operator and our optimization strategies by implementing them in PostgreSQL and evaluating on a standard benchmark by adding arbitrary attributes to its queries.
159

On the Analysis and Design of Series Hybrid Distributed Electric Propulsion with Boundary Layer Ingestion of Remotely Piloted Aircraft

Varela Martínez, Pau 18 April 2023 (has links)
[ES] En el presente trabajo se explora posibles soluciones a dos hechos correlacionados que podrían comprometer hasta cierto punto nuestro futuro. Por un lado, el crecimiento de la flota de aeronaves pequeñas en los próximos años, ya sean tripuladas o no, es una realidad. El acceso a estas aeronaves por parte de un público cada vez más mayoritario crece año a año y, al mismo tiempo, los fabricantes adaptan sus aeronaves a misiones que hace unos años no éramos capaces de contemplar. Por otro lado, y por desgracia, el cambio climático también es una realidad que no solo compromete nuestro futuro, sino también nuestro presente. Hoy en día la alerta climática es y debe ser elevada, y si no encontramos soluciones que ayuden a paliar este problema, la vida en el planeta podría cambiar irremediablemente para peor. Ambos hechos se encuentran implícitamente relacionados. La fabricación y operación de vehículos contribuye notablemente a aumentar la huella de carbono. Por lo tanto, el aumento de flota en los próximos años puede tener un impacto notablemente negativo en las emisiones contaminantes y gases de efecto invernadero globales. Es por ello por lo que organismos oficiales y sectores de desarrollo científico y tecnológico impulsan la investigación de posibles soluciones. Este trabajo intenta poner su grano de arena para minimizar este problema común. Se propone la utilización de múltiples tecnologías con el objetivo de disminuir el combustible requerido por aeronaves de 25kg al despegue, y de esta forma, disminuir las emisiones asociadas a su operación. Las tecnologías aplicadas son la hibridación eléctrica en serie, la propulsión eléctrica distribuida y la ingestión de capa límite. Por separado, estas tecnologías han demostrado múltiples ventajas, especialmente en términos de mejora propulsiva y aerodinámica de las aeronaves, lo que repercute directamente en el consumo de combustible. Sin embargo, este trabajo propone la utilización simultánea de todas ellas con el objetivo de disminuir aún más el consumo de combustible y, por tanto, las emisiones contaminantes y gases de efecto invernadero. Para ello, tras estas páginas se eligen los parámetros principales de esta aeronave y se acompaña de un exhaustivo análisis del comportamiento fluidodinámico. Con la comprensión de su comportamiento, es posible optimizar la selección de sus componentes, de forma que se obtienen mejoras importantes en el consumo de combustible. Este ahorro de combustible se muestra en comparación con aeronaves similares en tamaño y peso, pero que no incluyen estas tecnologías, logrando para un mismo alcance un ahorro del 16% del peso del combustible. La realización de este trabajo se centra en el empleo de herramientas computacionales apoyándose sobre todo en la dinámica de fluidos computacional (CFD). Esta herramienta principal se verá complementada con el uso de descomposición modal para realizar los análisis y de la creación de una base de datos que ayude a crear modelos rápidos útiles en futuros diseños preliminares y conceptuales de aeronaves de este tipo. / [CA] En aquest treball s'exploren possibles solucions a dos fets correlacionats que podrien comprometre d'alguna manera el nostre futur. Per un costat, el creixement de la flota d'aeronaus de xicoteta dimensió en el futur, tant tripulades com no tripulades, és una realitat. L'accés a aquestes aeronaus per part d'un públic cada cop més majoritari creix any rere any i, al mateix temps, els fabricants adapten les aeronaus a feines que anys enrere no eren capaços d'assolir. Per l'altre costat, malauradament, el canvi climàtic és un fet que compromet tant el nostre futur com el nostre present. Hui en dia l'alerta climàtica és elevada i, si no trobem solucions per a pal·liar aquest problema la vida al nostre planeta, podria canviar irremeiablement a pitjor. Ambdós fets es troben implícitament relacionats. La fabricació i l'operació de vehicles contribueix notablement a augmentar l'empremta de carboni. Per tant, l'increment de flota en els pròxims anys pot tindre un efecte negatiu molt notable en les emissions contaminants i gasos d'efecte hivernacle globals. És per això que organismes oficials i sectors de desenvolupament científic i tecnològic impulsen la investigació de possibles solucions. Aquest treball intenta aportar el seu granet de sorra per minimitzar aquest problema comú. Es proposa la utilització de múltiples tecnologies amb l'objectiu de reduir el combustible emprat per aeronaus de fins a 25kg i, per tant, disminuir les emissions associades a la seua operació. Les tecnologies aplicades són la hibridació elèctrica en sèrie, la propulsió elèctrica distribuïda i la ingestió de capa límit. Separadament, aquestes tecnologies han demostrat múltiples avantatges, especialment en termes de millora propulsiva i aerodinàmica de les aeronaus, repercutint directament en el consum de combustible. No obstant, aquest treball proposa la utilització simultània de totes elles amb l'objectiu de reduir encara més el consum de combustible i, per tant, les emissions contaminants i gasos d'efecte hivernacle. Per fer-ho, en les darreres pàgines es trien els paràmetres principals de l'aeronau i s'acompanyen d'una exhaustiva anàlisi del comportament de la dinàmica de fluids. Comprenent el seu comportament, és possible optimitzar la selecció dels seus components, de manera que s'obtenen millores importants en el consum de combustible. L'estalvi de combustible es mostra en comparació amb aeronaus similars en mida i pes, però que no inclouen aquestes tecnologies, aconseguint per a un mínim abast un estalvi del 16% del pes del combustible. La realització d'aquest treball es centra en l'ús d'eines computacionals recolzant-se sobretot en la dinàmica de fluids computacional (CFD). Aquesta eina principal es veurà complementada amb l'ús de descomposició modal per a elaborar les anàlisis i de la creació d'una base de dades que ajude a crear models ràpids i útils en futurs dissenys conceptuals i preliminars d'aeronaus d'aquest tipus. / [EN] The present work explores possible solutions to two correlated events that could compromise our future to some extent. On the one hand, the growth of the fleet of small aircraft in the coming years, whether manned or not, is a reality. Access to these aircraft by an increasing majority of the public grows year after year and at the same time, manufacturers adapt their aircraft to missions that we could not contemplate a few years ago. On the other hand, and unfortunately, climate change is also a reality that compromises not only our future but also our present. Today the climate alert is and must be elevated. If we do not find solutions that help alleviate this problem, life on the planet could irremediably change for the worse. Both facts are implicitly related. The manufacture and operation of vehicles contribute significantly to increasing the carbon footprint, so the increase in the fleet in the coming years may have an extremely negative impact on global polluting and greenhouse gas emissions. That is why official organizations and scientific and technological development sectors promote research for possible solutions. This work tries to do its bit to minimize this common problem. Multiple technologies are proposed to reduce the fuel required by 25kg aircraft at takeoff and, thus, reduce the emissions associated with their operation. The applied technologies are electric series hybridization, distributed electric propulsion, and boundary layer ingestion. Separately, these technologies have shown multiple advantages, especially in terms of improving aircraft propulsion and aerodynamics, which directly affects fuel consumption. Nevertheless, this work proposes the simultaneous use of all of them to reduce fuel consumption further and, therefore, polluting and greenhouse gas emissions. To do this, after these pages, the main parameters of this aircraft are chosen and accompanied by an exhaustive analysis of the fluid dynamic behavior. With an understanding of its behavior, it is possible to optimize its components' selection so that significant fuel consumption improvements are obtained. This fuel saving is shown in comparison with similar aircraft in size and weight, but that does not include these technologies, achieving a saving of 16% of fuel weight for the same range. This work's conduction focuses on employing computational tools mainly based on computational fluid dynamics (CFD). This primary tool will be complemented by the use of modal decomposition to carry out the analyses, and the creation of a database that will help create quick models useful in future conceptual and preliminary designs of this type of aircraft. / The respondent would like to acknowledge the financial support received through contract FPI-UPV PREDOCFD/19 of Subprograma 2 of Universitat Politècnica de València / Varela Martínez, P. (2023). On the Analysis and Design of Series Hybrid Distributed Electric Propulsion with Boundary Layer Ingestion of Remotely Piloted Aircraft [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/192805
160

Decentralized Secondary Frequency Control in an Optimized Diesel PV Hybrid System

Vieira Turnell, Alice January 2018 (has links)
This research argues that a diesel-based isolated electrical system can be optimized byintegrating a high share of solar photovoltaic (PV) generation and that the frequencystability of such system can be improved by including the PV participation in frequencyregulation. A case study is developed in order to explore an island’s expansion of theinstalled generating capacity and its optimization. This study uses the tool HOMER tosolve the optimization problem and PowerFactory to verify the frequency stability of theproposed system. The PV integration allows for a reduction of diesel fuel consumption,emissions and generation costs. Additionally, in high PV penetration scenarios, the reducedinertia in such systems can lead to high frequency deviations that may trip the systemprotection. The study demonstrates that the instantaneous frequency deviation after a loadand generation imbalance can be reduced by designing the PVs to operate with an allocatedreserve and a decentralized time-based secondary frequency control. The frequency stabilitywas achieved after different disturbance scenarios under high PV penetration and reducedavailable inertia, indicating that high PV integration is economically and technically feasiblein small island grids. / I detta examensarbete studeras hur ett dieselbaserat och isolerat elsystem kan optimeras genom att integrera en hög andel solceller (PV) i elproduktionen och att frekvensstabilitet kan förbättras när PV användas i regleringen. En fallstudie har utvecklats under denna forskning för att analysera en ökning av den installerade generationskapacitet vid en ö samt hur detta kan optimeras. I denna studie användas verktyget HOMER för modeloptimering och PowerFactory för att testa den optimerade systemfrekvens stabilitet. Med PV generation kan diesel konsumption, utsläpp och kostnader minskas för hela systemet. En hög andel PV i generationen reducerar elsystemet totala svängmassa vilket kan ledda till avvikelser i systemfrekvensen som kan ursaka att skyddsystem aktiveras. Studien demonstrerar att den momentana systemavvikelsen efter en obalans kan reduceras genom att designa PV i systemet med en allokerad reserv och en decentraliserad och tidsbaserad sekundär frekvensreglering. Frekvensstabiliteten nåddes i olika obalans scenarier med hög andel solcellgeneration och misnkat svängsmassa. Detta tyder på att en hög andel PV integration är både ekonomisk- och tekniskt möjligt i mindre elsystem.

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