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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.
51

Analys av massapumps- och mixerarbete vid Metsä Board Sverige AB, Husums Fabriker : Energibesparingsåtgärder vid blekeri 4 & 5 med jämförelse mot ny utrustning

Agrell, Elias January 2014 (has links)
Husums plant has a selection of different pulp pumps at bleaching plant 4 and 5. The displacement- (HC-pump, Sund Defibrator PTD-60) and centrifugalpumps (MC-pump, MCA 42-200, MCP 30/20) are of interest in this report. The centrifugal pumps are controlled by throttle valves, which result in an energy loss. Chemical mixers are used to mix ClO2 into the pulp before proceeding into a holding tower where the bleaching process occurs. The energy demand of the different positions has been measured or calculated to be used in comparisons against new equipment. Quotations were requested and delivered from Valmet and Sulzer. The quotations were made with a production increase of 10 ADMt/h and plant compared to current equipment. Therefore energy need of the equipment in the quotation had to be recalculated to the same production output as when measurements were conducted to be comparable. Quotation of the pumps assumes the use of frequency inverters. A deeper investigation was made for 441PU255 which is located at bleaching plant 4. The drop leg level of the pump is controlled via a throttle valve. A frequency inverter is installed but not utilized to maintain constant pulp level in the drop leg. This was due to physical changes in the process not being compensated for in the control system. This caused the drop leg level to oscillate when automatic control was used. As a workaround the drive had been set at a constant speed. To investigate the potential savings, an attempt was made in which the speed was lowered from 1520 rpm to 1100 rpm, resulting in a power reduction of 82 kW or 342,081 Sek per year at a production of 36 ADMT/h. The experiment was done with slightly lower production output than desirable; because of this, savings will decrease slightly at higher outputs. Comparisons showed that considerable amounts of energy could be saved at all positions. However the investment cost is high and therefore favorable payback times can only be seen for some of the positions. The MC-pumps are oversized and in need of constant throttling therefore the majority of the energy savings is made through the installation of frequency inverters and not the pump upgrade. / Metsä Board Husum har idag ett flertal olika modeller av massapumpar vid blekeri 4 och 5. Dessa är av deplacerande typ (HC-pump, Sunds Defibrator PTD-60) samt centrifugalmodell (MC-pump, MCA 42-200, MCP 30/20), centrifugalmodellen regleras med strypventiler vilket innebär en extra förlust, speciellt märkbar är denna då produktionen tas ned. Vid blekeriet finns även kemikaliemixrar för att mixa in ClO2 innan pappersmassan pumpas till ett uppehållstorn där blekprocessen sker. Anläggningens nuläge genomgick en mindre kartläggning där specifikationer och mätdata samlades in för att ge en bakgrund till det energibehov som finns idag. Tillgänglighet för reservdelar har varit av intresse för de äldre HC-pumparna. Tillsammans med Sulzer har uppfordringshöjd beräknats för positioner utrustade med PTD -60 då uppgifter för denna saknades. Sulzer och Valmet har offererat ny utrustning för dessa positioner som jämförs mot uppmätta värden för att beräkna återbetalningstid. Inkomna offerter förutsätter frekvensomriktare och baseras på en önskad produktionsökning till 50 ADMt/h för blekeri 4 och 60 ADMt/h för blekeri 5. Detta är en ökning på 10 ADMt/h och blekeri. Erforderlig effekt för drifter i inkomna offerter och uppmätt effekt är ej angiven vid samma driftpunkt. De offererade pumparnas driftpunkt har därför räknats om för att motsvara driftpunkt vid tillfället för insamling av data. Detta för att enkelt kunna jämföra offerter mot nuläge. På blekeri 4 återfinns en MC-pump av modell MCA 42-200 med posnummer 441PU255. Vid denna position gjordes en djupare undersökning då nivåregleringen ej fungerar som tänkt. Nivåhållning sker via reglerventil och varvtalsreglering med frekvensomriktare. För att kunna köra driften har frekvensomriktaren manuellt ställts i ett fast varvtal och reglerventilen lagts i automatik. Ventilen styr därmed nivå i fallröret och har vid normal drift en öppningsgrad på 40-50 %. Vid genomgången upptäcktes att parametrar i styrsystem gällande de varvtal motorn skall arbeta vid inte korrigerats efter en ombyggnation. Detta har medfört att nivån inte gått att reglera i automatik utan att systemet börjat självsvänga. För att undersöka skillnad mellan varvtalsstyrning och strypreglering gjordes ett försök där varvtalet sänktes från 1520 rpm till 1100 rpm vilket resulterade i en effektminskning på 82 kW eller 342 081 kr per år jämfört med strypreglering; detta var vid en produktion av 36 ADMt/h. Försöket gjordes med något lägre produktion än önskvärt; på grund av detta kommer besparingen minska något vid högre produktion. Samtliga positioner uppvisar minskat energibehov med ny utrustning. Dock gör hög investeringskostnad och krav på kort återbetalningstid att endast några få positioner är lämpliga kandidater för ombyggnad i dagsläget. För MC-pumparna kan däremot majoriteten av besparingen uppnås genom att bygga om dagens strypreglering till varvtalsreglering. Detta sker till en betydligt lägre kostnad än vid uppgradering av pump. Arbetet visar att det finns stor potential att minska energikonsumtion vid blekning av pappersmassa, detta gäller speciellt för de befintliga MC-pumparna som är kraftigt överdimensionerade och regleras med strypventil. De gamla kemikaliemixrarna använder stora mängder energi för att mixa in ClO2, nya mixrar använder mindre än hälften av energin och ger överskådliga återbetalningstider.
52

Le criminel asocial dans la littérature américaine de la seconde moitié du vingtième siècle / The asocial criminal in the American literature of the second half of the twentieth century

Martel, Audrey 08 November 2013 (has links)
Qu’y a-t-il de commun entre Vladimir Nabokov, Norman Mailer, Don DeLillo, Cormac McCarthy et James Ellroy ? Ces cinq écrivains contemporains se sont intéressés au personnage du criminel asocial sur le territoire des États-Unis. Son existence repose sur le paradoxe propre à tout individu asocial : bien qu'il n'adhère pas aux conventions établies qu'il perçoit comme des entraves, il ne souhaite pas rompre les ponts avec la collectivité et refuse la vie en autarcie. S'il n'est donc pas antisocial, pourquoi fait-il le choix de l'asocialité ? Parce qu'il ne peut accepter ce qu'il perçoit comme des déviances dans le modèle de vie qui lui est proposé et qu'il va le remettre en question. Mais pourquoi serait-il de plus enclin à la criminalité ? La question est légitime dans la mesure où la relation entre criminalité et asociabilité n'est pas évidente alors que lier antisocial et criminel serait plus aisé car il y alors négation affirmée des lois de la société et volonté de s'en affranchir par l'action. A l'inverse, un asocial n'est pas nécessairement criminel. Cependant, chez les protagonistes des auteurs, ces deux caractéristiques vont de pair : peut-être sont-ils à la fois asociaux et criminels parce qu'ils ont décidé de vivre leur transgression en marge d'une société qui ne les satisfait pas mais qui ne les intéresse pas assez pour qu'il la combatte activement ? Ou peut-être trouvent-ils nécessaire de s'affranchir des lois pour exister dans le cadre qui leur est imposé et qu'ils ne cautionnent plus ? Il en résulte une écriture façonnée par ces questionnements et leurs nombreuses variations. Le corpus fait de biographies, récits fictionnels et non-fictionnels, entraîne une réflexion sur le modèle sociétal américain des années 50 à la fin des années 90 et plus particulièrement sur ses dysfonctionnements à l’origine de l’émergence de ce type de personnage qui devient alors l'instrument à visée démonstrative d'une littérature engagée. / What is the common point between Vladimir Nabokov, Norman Mailer, Don DeLillo, Cormac McCarthy et James Ellroy ? These five authors have been interested in a specific character in the contemporary literature, the asocial criminal in The United States. He appeared in a paradoxical way : while he is fighting against the established social conventions, he does not wish to live away from this society. So if this character is not antisocial, why does he make the choice to be asocial ? Because he cannot accept what he considers as a deviance inside the American way of life and he is going to fight against it in order to achieve his personal goals. But why should he also be a criminal ? This is a legitimate question since the link between crime and lack of sociability is not necessarily an obvious fact. On the contrary, it is pretty easier to tie crime and antisocial behaviors because there is a desire to live like an outcast, to infringe laws with violence. So, an asocial cannot be a criminal. However, concerning the authors' protagonists, both of these features work well together. Maybe they are asocial and criminal because they decided to live according to their wishes inside their society with its restrictive rules but as they refuse to lose their freedom, they know perfectly well they must not go too far ? Or maybe they also simply think they do not have to follow rules that they cannot accept and support ? Anyway, all these questions lead to a various corpus composed by biographies, fictions and non fiction stories. It entires the reader to think about the American consumer society and more particularly about the dysfunctions which gave birth to the asocial criminal character. So that the latter becomes a thought-provoking within the socially-engaged literature.
53

Třífázový DC/AC střídač na malé napětí pro synchronní motor AXi 5345/18 / Three-phase low-voltage DC/AC converter for a synchronous motor AXi 5345/18

Popek, Michal January 2008 (has links)
The target of this master's thesis is to describe, design and construct an extra low voltage three-phase DC/AC inverter for the motor AXI 5345/18, which will work in EC motor mode. The inverter is supplied by DC source 24 V. In order to save place, the wiring is designed on three separated printed board circuits. These are connected together by connectors for ribbon cables. The control is done by reverse current loop realized by active electronics and superior circuit MC 33035. The proper wiring of current loop is conformed for both control and testing of jet sensors ACS750. Power electronics of the inverter is realized by potential-free modul GWM 120-0075P3 consisted of 6 mosfet transistors. The designed wiring is not set for the concrete realisation, but it can be used for control of propulsion of the wheel, auxiliary propulsion of engine or in appliances, where servo with worse parameters of control loop is used in a sufficent way and it can be cheaper.
54

Caractérisation de la perception racinaire et de la résistance systémique induite par les rhamnolipides et leurs précurseurs chez Arabidopsis thaliana / Characterization of root perception and induced systemic resistance by rhamnolipids and their precursors in Arabidopsis thaliana

Touchard, Matthieu 13 December 2019 (has links)
Dans leur environnement, les plantes sont fréquemment soumises à des attaques de microorganismes pathogènes. Pour leur faire face, elles mettent en place des mécanismes de défense activés suite à la détection du microorganisme via des motifs moléculaires ou IPs (Invasion Patterns). Les rhamnolipides (RLs) sont des molécules glycolipidiques amphiphiles produites par des bactéries des genres Pseudomonas et Burkholderia. Ces molécules sont capables d’induire, au niveau foliaire chez différentes plantes, une résistance locale contre des microorganismes phytopathogènes. L’acide 3-hydroxydécanoïque (3-OH-C10:0), le constituant de base de la partie lipidique des RLs, active aussi une réponse immune dans la partie aérienne de la plante Arabidopsis thaliana. Cette réponse immune est déclenchée suite à sa perception par le récepteur kinase S-lectine LORE. Les travaux menés au cours ce projet de thèse ont permis de mettre en évidence que le 3-OH-C10:0 est perçu au niveau racinaire par LORE, conduisant à l’activation d’une réponse immune innée et à la mise en place d’une résistance systémique (ISR) efficace contre le champignon nécrotrophe Botrytis cinerea. D’autre part, ces travaux ont révélés que les RLs sont aussi perçus au niveau racinaire et activent une ISR contre B. cinerea n’impliquant pas le récepteur LORE. L’ensemble de ces résultats montrent que les RLs ainsi que le 3-OH-C10:0, sont deux IPs reconnus par A. thaliana au niveau racinaire via des mécanismes indépendants et tous deux conduisant à l’activation d’une résistance systémique. / In their environment, plants are frequently challenged by pathogenic microorganisms. Plants are able to trigger an innate immune response to fight against the infection. This immune response is activated after perception of the microorganisms through Invasion Patterns (IPs). Rhamnolipids (RLs) are amphiphilic glycolipidics molecules produced by some bacterial species including Pseudomonas and Burkholderia. RLs are able to induce an immune response in the aerial part of several plant which is effective against phytopathogens. 3-hydroxydecanoic acid (3-OH-C10:0), a lipid building block from RLs, is known to trigger Arabidopsis thaliana immune responses in leaves after its perception by the bulb-type lectin receptor kinase LORE. In the present work, we showed that the 3-OH-C10:0 is also sensed by roots through LORE, triggering local immune responses and a systemic induced resistance (ISR) effective against the necrotrophic fungus Botrytis cinerea. In addition, this work revealed that RLs are also recognized by root cells, activating a LORE-independent ISR against B. cinerea. This work shows that RLs and 3-OH-C10:0 are different IPs independently recognized by A. thaliana roots but both inducing a systemic resistance in plants.
55

Modélisation tridimensionnelle des ARN par exploration de l'espace conformationnel et satisfaction de contraintes

Thibault, Philippe January 2004 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
56

On the System Level Performance of MC-CDMA Systems in the Downlink

Mourad, Abdel-Majid 10 January 2006 (has links) (PDF)
La technique de transmission multi-porteuse à étalement de spectre, MC-CDMA, est un candidat potentiel pour les interfaces radio des futurs systèmes radio mobiles. Cette technique bénéficie d'une part de la robustesse de la transmission multi-porteuse OFDM face à la propagation multi-trajets et d'autre part de la flexibilité de l'accès multiple à répartition par codes CDMA. Cette thèse s'intéresse à l'étude des performances systèmes de la technique MC-CDMA en voie descendante. L'objectif est de valider au niveau système les concepts et algorithmes de la couche physique MC-CDMA.<br />La thèse s'articule autour de deux thématiques qui sont liées. La première thématique concerne l'abstraction de la couche physique au niveau système. Cette thématique est aussi connue sous le nom d'interfaçage entre les niveaux lien physique et système. L'abstraction de la couche physique a pour principal objectif de définir une mesure adéquate pour prédire la qualité de transmission au niveau système. Dans cette thèse, nous étudions l'abstraction de la couche physique suivant deux échelles de temps. La première échelle est macroscopique et porte sur la transmission de plusieurs trames de données subissant des évanouissements de canal indépendants. La deuxième échelle est dite microscopique et porte sur la transmission d'une seule trame de données subissant un évanouissement particulier du canal. L'abstraction macroscopique est appropriée pour une évaluation des performances systèmes par des simulations systèmes statiques alors que l'abstraction microscopique est plus appropriée pour une évaluation plus précise des performances systèmes ainsi que pour étudier les algorithmes d'adaptation de lien par des simulations systèmes dynamiques. Dans notre étude, nous analysons les problèmes soulevés par les deux types d'abstraction et proposons des nouvelles solutions appropriées.<br />La deuxième thématique concerne l'évaluation de la capacité cellulaire des algorithmes et configurations de la couche physique MC-CDMA. En utilisant l'abstraction macroscopique, nous développons une méthodologie semi analytique d'évaluation de la capacité cellulaire. L'évaluation de la capacité est faite aussi bien au niveau lien à travers un nouvel indicateur de capacité qu'au niveau système à travers un simulateur statique de type Monte Carlo. La méthodologie développée ici est un outil simple et efficace pour identifier les algorithmes et configurations de couche physique les mieux adaptés pour un environnement donné.<br /><br />Mots clefs - MC-CDMA, modélisation d'interférence, interfaçage lien système, capacité cellulaire, simulations systèmes.
57

Soft Handoff in MC-CDMA Cellular Networks Supporting Multimedia Services

Zhang, Jinfang January 2004 (has links)
An adaptive resource reservation and handoff priority scheme, which jointly considers the characteristics from the physical, link and network layers, is proposed for a packet switching Multicode (MC)-CDMA cellular network supporting multimedia applications. A call admission region is derived for call admission control (CAC) and handoff management with the satisfaction of quality of service (QoS) requirements for all kinds of multimedia traffic, where the QoS parameters include the wireless transmission bit error rate (BER), the packet loss rate (PLR) and delay requirement. The BER requirement is guaranteed by properly arranging simultaneous packet transmissions, whereas the PLR and delay requirements are guaranteed by the proposed packet scheduling and partial packet integration scheme. To give service priority to handoff calls, a threshold-based adaptive resource reservation scheme is proposed on the basis of a practical user mobility model and a proper handoff request prediction scheme. The resource reservation scheme gives handoff calls a higher admission priority over new calls, and is designed to adjust the reservation-request time threshold adaptively according to the varying traffic load. The individual reservation requests form a common reservation pool, and handoff calls are served on a first-come-first-serve basis. By exploiting the transmission rate adaptability of video calls to the available radio resources, the resources freed from rate-adaptive high-quality video calls by service degradation can be further used to prioritize handoff calls. With the proposed resource reservation and handoff priority scheme, the dynamic properties of the system can be closely captured and a better grade of service (GoS) in terms of new call blocking and handoff call dropping probabilities(rates) can be achieved compared to other schemes in literature. Numerical results are presented to show the improvement of the GoS performance and the efficient utilization of the radio resources.
58

MC-CDMAを用いた車車間通信に適したターボ等化の検討(研究速報,<特集>通信技術の未来を拓く学生論文)

平岩, 士昌, 坂田, 篤則, 山里, 敬也, 片山, 正昭 01 January 2009 (has links)
No description available.
59

Soft Handoff in MC-CDMA Cellular Networks Supporting Multimedia Services

Zhang, Jinfang January 2004 (has links)
An adaptive resource reservation and handoff priority scheme, which jointly considers the characteristics from the physical, link and network layers, is proposed for a packet switching Multicode (MC)-CDMA cellular network supporting multimedia applications. A call admission region is derived for call admission control (CAC) and handoff management with the satisfaction of quality of service (QoS) requirements for all kinds of multimedia traffic, where the QoS parameters include the wireless transmission bit error rate (BER), the packet loss rate (PLR) and delay requirement. The BER requirement is guaranteed by properly arranging simultaneous packet transmissions, whereas the PLR and delay requirements are guaranteed by the proposed packet scheduling and partial packet integration scheme. To give service priority to handoff calls, a threshold-based adaptive resource reservation scheme is proposed on the basis of a practical user mobility model and a proper handoff request prediction scheme. The resource reservation scheme gives handoff calls a higher admission priority over new calls, and is designed to adjust the reservation-request time threshold adaptively according to the varying traffic load. The individual reservation requests form a common reservation pool, and handoff calls are served on a first-come-first-serve basis. By exploiting the transmission rate adaptability of video calls to the available radio resources, the resources freed from rate-adaptive high-quality video calls by service degradation can be further used to prioritize handoff calls. With the proposed resource reservation and handoff priority scheme, the dynamic properties of the system can be closely captured and a better grade of service (GoS) in terms of new call blocking and handoff call dropping probabilities(rates) can be achieved compared to other schemes in literature. Numerical results are presented to show the improvement of the GoS performance and the efficient utilization of the radio resources.
60

B2B Information Service Quality and Customer Satisfaction

Hou, Ya-Hui 01 July 2012 (has links)
Electronic business covers the enterprise purchase and sale activities, collaboration between customers and partners, and inter-organizational electronic transactions. In the 21st century, the enterprise take Information Technology deeply to embed in each process (the Process Step), with the Internet technique that has become the indispensable kernel of competition in the business operations. After a number of semiconductor manufacturers participating in ¡§RosettaNet For Semiconductor Contract Manufacturing B2B Integration Project¡¨, it has been a necessary condition whether semiconductor manufacturers can provide customers with B2B information services now. However,the semiconductor manufacturers should be thinking how to meet the customers changing needs of B2B information service, how to integrate information, and how to synchronize induction environmental change. This research is based on ¡§the Impact of the QM practices on MC the capability mode¡¨. The B2B team members provide all of the ad hoc group for B2B project members' empirical perception to do the quality of B2B information services empirical analysis during implementation project. The objective aims to understand the impact of service quality for customer satisfaction. The result clearly indicates that the five dimensions will be a significant impact in B2B service quality for the enterprise information services, namely, small group problem solving, top management leadership for quality, information and feedback, supplier involvement and Process management. But if each dimension is to be analyzed individually, customer focus would impact on B2B information service quality. Generally speaking, the B2B team wants to enhance service quality, and then they should start with these five dimensions to proceed, and thereby to raise customer satisfaction. From the investing funds scale, they want to pursue efficiency, and almost each of semiconductor company has set up a similar B2B team to dominate the B2B project for customer service. Furthermore, this research used variables in the different conditions of demographic variables to summarize the diversity of satisfactions, and these analyses acquire the managerial implications that will be managers an important basis for improving the quality of B2B information services.

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