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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.
21

Dynamique des Ions en Solution et aux interfaces : Modèles et Applications

Dufrêche, Jean-François 17 December 2001 (has links) (PDF)
Ce travail présente une nouvelle approche de la dynamique des ions dans les solutions d'électrolytes concentrées, que l'on rencontre dans les milieux naturels ainsi que dans les procédés industriels. Les variations des coefficients de transport ioniques avec la concentration, ont été obtenues en utilisant les fonctions de distribution d'équilibre de l'approximation sphérique moyenne (MSA). Ce travail a tout d'abord été conduit par une théorie au niveau Smoluchowski. En particulier la diffusion mutuelle d'électrolytes associés et dissociés a été étudiée, à la fois par des calculs analytiques et par des simulations de dynamique brownienne. L'autocohérence de la description, qui consiste à utiliser les mêmes paramètres pour décrire les différentes grandeurs d'équilibre et de transport, est l'un des principaux points de cette thèse. Elle a pu être obtenue grâce à une analyse soignée des référentiels dans lesquels sont évalués les différents coefficients, ce qui n'avait pas encore été réalisé. Il est ainsi possible de rendre compte du comportement de solutions jusqu'à 2 M avec comme seuls paramètres les coefficients de diffusion des ions à dilution infinie et leur rayon en solution. Ces résultats sont en accord avec les lois limites phénoménologiques d'Onsager et les généralisent. La thèse aborde aussi un point encore non élucidé auparavant, qui est celui de la dynamique aux temps courts dans les électrolytes. Une théorie de couplage de mode, en accord avec les simulations de dynamique brownienne, a permis la détermination de la variation des coefficients d'autodiffusion des ions en fonction du temps d'observation et de la concentration, avec le même jeu de paramètres que pour les autres grandeurs de transport et d' ́équilibre. Pour des durées d'observation trop courtes, l'effet de relaxation n'a pas le temps de se manifester : l'autodiffusion est alors plus rapide. Le couplage de mode retrouve ainsi le fait que les mesures expérimentales de diffusion quasi-élastique de neutrons, réalisées aux temps courts, donnent des valeurs plus importantes que les autres méthodes (traceurs, RMN), réalisées aux temps longs. Le problème des électrolytes aux interfaces chargées, dans le cas d'une argile hydratée, a également été étudié au cours de cette thèse. Il a été possible de démontrer la coh ́erence entre la description microscopique à solvant discret et celle à solvant continu.
22

Disentangling Individual and Community Effects on Environmentally Sensitive Behaviors

Harmon, Mary P. 13 November 2009 (has links)
A major criticism of the environmental behavior literature is the nearly exclusive focus on the role of attitudes and individual-level characteristics. Despite this concentration on individual-level causes, variation in environmental behavior remains. As individual behavior becomes an increasingly significant source of pollution, a better understanding of the influences individual behavior is critical to addressing environmental degradation. This research re-directs the focus on individual-level influences on environmental behaviors by building models examining the varying dimensions of environmental behaviors as influenced by community characteristics. This is accomplished by testing a series of hypotheses under the auspices of two theoretical frameworks: the neoclassical economic theory and a social contextual model of environmental actions. Using individual-level data from the 1993 and 2000 General Social Survey and MSA data from the U.S. Census and the Environmental Protection Agency, I estimate two-level hierarchical models for three environmentally sensitive behaviors (environmentally sensitive food consumption, environmentally sensitive automobile use, and environmental activism). Multi-level analyses yield models revealing significant associations between MSA measures and individual environmental behaviors. Objective environmental conditions, region of MSA and MSA education level are significantly associated with environmentally sensitive food consumption behaviors, environmentally sensitive automobile use, and environmental activism behaviors, though their influence assumes diverse forms. Among the community measures, MSA education level is the primary social process that produces change in all environmental behaviors. In each of the models, MSA education level exhibits effects on all three behavioral measures and significant cross-level effects on automobile use behaviors. Living in a well educated MSA, particularly in the West or Northeast suggests higher environmental participation. Region of MSA is also a characteristic that must be considered when evaluating environmental behaviors, particularly for those living in the West and Northeast. Theoretical conclusions suggest that individual environmental behavior decision making is not simply a market exchange, but social forces are at work in the individual decision-making process.
23

Efficient Characterization of Short Anelloviruses Fragments Found in Metagenomic Samples

Al-Absi, Thabit January 2012 (has links)
Some viral metagenomic serum samples contain a huge amount of Anellovirus, which is a genetically diverse family with a few conserved regions making it hard to efficiently characterize. Multiple sequence alignment of the Anelloviruses found in the sample must be constructed to get a clear picture of Anellovirus diversity and to identify stable regions. Using available multiple sequence alignment software directly on these fragments results in an MSA of a very poor quality due to their diversity, misaligned regions and low-quality regions present in the sequence. An efficient MSA must be constructed in order to characterize these Anellovirus present in the samples. Pairwise alignment is used to align one fragment to the database sequences at a time. The fragments are then aligned to the database sequences using the start and end position from the pairwise alignment results. The algorithm will also exclude non-aligned portions of the fragments, as these are very hard to handle properly and are often products of misassembly or chimeric sequenced fragments. Other tools to aid further analysis were developed, such as finding a non-overlapping window that contains the most fragments, find consensus of the alignment and extract any regions from the MSA for further analysis. An MSA was constructed with a high percent of correctly aligned bases compared to an MSA constructed using MSA softwares. The minimal number of genomes found in the sampled sequence was found as well as a distribution of the fragments along the database sequence. Moreover, highly conserved region and the window containing most fragments were extracted from the MSA and phylogenetic trees were constructed for these regions.
24

Circuit Design of LDPC Decoder for IEEE 802.16e systems

Wang, Jhih-hao 29 March 2010 (has links)
A circuit design of Low Density Parity Check (LDPC) decoder for IEEE 802.16e systems is with new overlapped method is proposed in this thesis. This circuit can be operated with 19 modes which are corresponding to block sizes of 576, ¡K, 2304. LDPC decoders can be implemented by using iterations with Variable Node and Check Node Processes. The hardware utilization ratio, which can be enhanced from 50% to 100% by using our proposed overlapped method, is better than traditional overlapped method. In [2], the traditional overlapped method utilization ratio just can be enhanced from 50% to 75% for IEEE 802.16e LDPC decoder with code rate 1/2. Under the same operating frequency, our proposed method can further increase 25% when compared with traditional overlapped method [2]. In this thesis, we also propose two circuit architectures to increase the operating frequency. First, we use a faster comparison circuit in our comparison unit [1]. Second, we use Carry Save Adder¡]CSA¡^method [8] to replace the common adder unit. The circuit is carried out by TSMC CMOS 0.18£gm 1P6M process with chip area 3.11 x 3.08 mm2. In the gate level simulation, the output data rate of this circuit is above 78.4MHz, so the circuit can meet the requirement of IEEE 802.16e system.
25

Entwicklung und Einsatz von Mikrostrukturreaktoren mit katalytisch wirksamen Strömungskanälen für die partielle Gasphasen-Oxidation von 1-Buten

Kah, Stefan 10 May 2005 (has links) (PDF)
In der vorliegenden Arbeit wurden erstmalig Mikrostrukturreaktoren bei der partiellen Oxidation von 1-Buten zu Maleinsäureanhydrid (MSA) eingesetzt. Diese stark exotherme, heterogen katalysierte Umsetzung fand hierbei in Stapeln mikrostrukturierter Aluminiumfolien statt, welche durch parallele Strömungskanäle mit katalytisch wirksamen Oberflächenschichten charakterisiert sind. Als Aktivkomponenten kamen Vanadium-, Phosphor- und Titanoxide zur Anwendung. Ein Vergleich von drei kompakten Mikrostrukturreaktoren mit Kanaldurchmessern der Mikrokanäle von 0,08, 0,2 bzw. 0,4 mm mit einem Schüttgutreaktor wurde durchgeführt. Vorausgehend war die Entwicklung von 3 verschiedenen Methoden zur Immobilisierung von V2O5 und P2O5 auf dem Katalysatorträger bei jeweils unterschiedlichen Katalysatorvorläufern. Die Herstellungsparameter der geeignetsten Immobilisierungsmethode wurden, entsprechend einem Screening in Schüttgutreaktoren, systematisch variiert. Die katalytische Aktivierung der Folien erfolgte nach der gleichen Präparationsvorschrift die zur Herstellung des „besten“ Katalysator-Schüttguts führte. Bei der partiellen Oxidation von 1-Buten außerhalb des Explosionsbereiches bestanden nur geringfügige Unterschiede zwischen den MSA-Selektivitäten im Schüttgut bzw. in der Mikrostruktur (33%). In letzterer wurden hingegen um den Faktor 3 bis 5 höhere Raum-Zeit-Ausbeuten als im Schüttgut erzielt. Des weiteren konnte die partielle Oxidation von 1-Buten innerhalb des Explosionsbereiches ausschließlich in den Mikrostrukturreaktoren explosionssicher - und ohne Anzeichen auf instabile Betriebspunkte – gehandhabt werden. Begleitend dazu fand die Entwicklung und der Einsatz dreier modularer Mikrostrukturreaktoren bei der partiellen Oxidation von 1-Buten statt. Praktische Ergebnisse wurden anhand eines entwickelten Reaktormodells bestätigt.
26

Software Architectural Metrics for the Scania Internet of Things Platform : From a Microservice Perspectiv

Ulander, David January 2017 (has links)
There are limited tools to evaluate a microservice architecture and no common definition of how the architecture should be designed. Moreover, developing systems with microservices introduces additional complexity to the software architecture. That, together with the fact the systems are becoming more complex has led to a desire for architecture evaluation methods. In this thesis a set of quality attributes measured by structural metrics are used to evaluate Scania's IoT Offboard platform. By implementing a metrics evaluation program the quality of the software architecture can be improved. Also, metrics can assist developers and architects while they are becoming more efficient since they better understand how performance is measured, i.e. which quality attributes are the most important and how these are measured. For Scania's IoT Offboard platform the studied quality attributes are listed in decreasing importance: flexibility, reusability and understandability. All the microservices are loosely coupled in the platform, which results in a loosely coupled architecture. This indicates a flexible, reusable and understandable system, in terms of coupling. Furthermore, the architecture is decentralized, i.e. the system is unflexible and difficult to change. The other metrics were lacking a reference scale, hence they will act as a point of reference for future measurements as the architecture evolves. To improve the flexibility, reusability and understandability of the architecture the large microservices should be divided into several smaller microservices. Also aggregators should be utilized more to make the system more flexible.
27

Påverkan av skillnader mellan arabiska varieteter; från arabisktalande tolkars och tolkanvändares perspektiv / The influence of differences between Arabic varieties; from the perspective of Arabic-speakers interpreter and users of the interpreter.

Ridha, Mohaned January 2013 (has links)
Syftet med min magisteruppsats är att undersöka om arabisktalande tolkanvändare och tolkar tycker att skillnaden mellan arabiska varieteter kan påverka kommunikationen mellan dem under det tolkade samtalet eller inte. Studien är begränsad för att bara fokusera på de två samtalsparternas bedömning och uppfattning av varietetsskillnad. Enkätundersökning användes som metod, där enkäten vänder sig till de nämnda två grupperna, för att ta reda på vad samtalsparterna själva tycker om påverkan av varietetsskillnaderna. Resultatet visade att tolkarna och de arabisktalande tolkanvändarna inte har samma bedömning och uppfattning om påverkan av varietetsskillnad. Det visade också att både tolkar och arabisktalande tolkanvändare anser att varietetsskillnad kan påverka kommunikationen mellan dem och att påverkan är variabel, för att den beror på varietetsskillnad, dvs. den kan ökas och minskas parallellt enligt varietetsskillnad. / The aim of my master thesis is to investigate whether the Arabic-speakers users of the interpreter and interpreters think that the difference between Arabic varieties can affect the communication between them during the interpreted conversation or not. The study is limited to focus only on the evaluation and understanding of these two conversation-parties. I used the questionnaire as a method, where it addressed to the same mentioned two groups, to find out what the interlocutors think about the effect of the varieties-difference. The results of the analysis showed that the Arabic-speakers users of the interpreter and interpreters do not have the same evaluation and understanding for the difference between varieties. It also showed that both the Arabic-speakers users of the interpreter and interpreters consider that the difference between the varieties can affect the communication between them and that effect is variable, because it depends on the difference between the varieties, i.e. it can be increased and decreased in parallel way according to the varieties-difference.
28

Mätsystemanalys för förbättring av mätnoggrannheten med mätsticka, mikrometer och skjutmått på SKF i Hofors

Valler, Agnes, Ågren, Isabelle January 2017 (has links)
SKF Coupling in Hofors manufactures screws and couplings to the energy sector and the marine industry. The products have tight tolerances to be more attractive at the market through the tolerances. With increased competition on the market, the quality requirements increase, which means that many products fail to meet the quality requirements in order to avoid customer complaints. The purpose of this work was to improve measurement accuracy. To get an overview of the current situation, interviews and observations were made. A measurement system analysis was conducted by tests where a certain number of products were measured by a certain number of operators, with a certain number of repetitions. The test results were analyzed by a two-way ANOVA and Gauge R&R, which are common methods in measurement system analysis. A cause-and-effect diagram was used to investigate the causes of quality problems. The results indicated that the existing measurement systems were not reliable enough. The shortcomings may depend on the measuring device and the operator. The measuring device may be defective or have calibration defects. Operators can have different methods when measuring which contributes to variations in the measurements. The work led to suggestions for improvements that could imply higher accuracy in the measurement systems. For example, a tighter calibration interval of the measuring device would lead to reduced impact from the measuring device. A standardized education of measurement method, measurement environment and the importance of deviation management can also lead to improved measurement accuracy. / SKF Coupling i Hofors tillverkar skruvar och kopplingar till energisektorn och den marina industrin. Produkterna har snäva toleranser för att genom toleranserna vara mer attraktiva på marknaden. I och med ökad konkurrens ökar kvalitetskraven. Därför kasseras många produkter, som inte uppnår kvalitetskraven, för att undvika returer från kunderna. Syftet med arbetet var att förbättra mätnoggrannheten. För att få en överblick av nuläget gjordes intervjuer och observationer. En mätsystemanalys gjordes genom tester där ett utvalt antal produkter mättes av ett utvalt antal operatörer, med ett visst antal upprepningar. Testresultaten analyserades med en tvåvägs-ANOVA och Gauge R&R som är vanliga metoder inom mätsystemanalys. Ett orsak-verkan-diagram användes för att undersöka orsakerna till kvalitetsproblemen. Resultatet visade att det finns brister i det nuvarande mätsystemet. Bristerna kan bland annat bero på mätdonet och operatören. Mätdonet kan exempelvis vara defekt eller ha brister i kalibreringen. Operatörerna kan ha olika metoder som bidrar till variationer i mätningarna. Arbetet ledde till förbättringsförslag, som kan innebära högre noggrannhet i mätsystemen. Exempelvis skulle ett tätare kalibreringsintervall hos mätdonen leda till minskad påverkan från mätdonen. En standardiserad utbildning av mätmetod, mätmiljö och vikten av att avvikelsehanteringen följs kan också leda till en förbättrad mätnoggrannhet.
29

Testování MEMS gyroskopů / Testing of MEMS gyroscopes

Hasík, Stanislav January 2016 (has links)
This diploma thesis presents theoretical information regarding MEMS gyroscopes their parameters and designs. The description of measurement chain be used for testing of MEMS gyroscopes in Honeywell International s.r.o. is presented. Special focus is devoted to: the Polytec MSA-500 system, the Standa goniometers and their controller, Peltier cell and its driver. The practical part of this thesis contains the description of the thermal control system and also the description of the developed “Measurement system” in the LabVIEW software which is used for controlling the goniometers position and the Peltier cell. The system is able to fully control two goniometer stages, align the surface of tested MEMS device to orthogonal position with respect to the Polytec MSA-500 measurement head and also control the temperature of the tested device. The last part of this thesis presents the tests of the MEMS gyroscope parameters with special focus to the MEMS gyroscope angle random walk and the bias dependence on the vacuum quality of the structure environment.
30

Arquitecturas inteligentes para gestión de sistemas ciberfísicos en ambientes IoT

Duque Gómez, Henry 27 October 2020 (has links)
La necesidad de diseñar e implementar arquitecturas inteligentes impone grandes retos que exceden las capacidades del software desarrollado hasta el momento, pues no existen arquitecturas inteligentes que se adapten a los cambios del escenario físico y tomen decisiones en tiempo real. Esto significa que uno de los retos críticos en el problema planteado está en el campo de la ingeniería y arquitectura software, que tienen que estar dispuestos a entender la interactividad de cambios en las variables del entorno físico, lo cual implica que el enfoque dado a dichas arquitecturas debe redirigirse al diseño e implementación de un nuevo paradigma de inteligencia en los ecosistemas en los que actúan la ingeniería y la arquitectura. Para atacar las necesidades de inteligencia expuestas anteriormente, proponemos una arquitectura como marco de referencia inteligente, diseñada en torno a la exposición de servicios y microservicios dirigidos por eventos con la capacidad funcional de procesar eventos complejos, los cuales pueden ser configurados, parametrizados y direccionados, diseñando patrones que adquieren inteligencia. Estos patrones son diseñados e implementados de acuerdo con un análisis previo de las rutinas de comportamiento de objetos o personas en un escenario dado. La inteligencia radica en la forma de inferir nuevos eventos más complejos, con mayor significado semántico y ontológico, a partir de la suma de eventos simples. Esto nos permite implementar patrones de comportamiento relevantes detectados por dispositivos sensores (cámaras de videovigilancia, sensores visuales, sensores de detección de señales, de proximidad, etc.) instalados en escenarios físicos. El diseño de arquitectura propuesto está orientado al aprendizaje de los patrones, de tal forma que a partir de este aprendizaje, analice la serie de eventos y derive conclusiones de ellos, dependiendo si en los eventos analizados existen situaciones catalogadas como inusuales o de interés. Todo lo anterior le permite al sistema reaccionar y someter la información a un procesamiento en línea y mejorar en la toma decisiones. En nuestro caso, también proveemos inteligencia desde el software, dado que la inteligencia diseñada a través de los patrones es recursiva en la suma de capacidades de los diferentes comportamientos que puede adquirir un evento expuesto a través de un microservicio. En el cual, la inteligencia se debe al engranaje conjunto de los componentes en un ecosistema dado en el que actúe el microservicio (sistemas ciberfísicos, la nube, redes neuronales, inteligencia artificial, robótica, etc.). Además, la inteligencia radica en la forma como los servicios compiten por los recursos de información subyacentes en los dispositivos sensores y por las necesidades de competencia por la infraestructura del ambiente IoT y la nube.

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