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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.
1

A systematic approach to the tuning of multivariable Dynamic Matrix Control (DMC) controllers

Gous, Gustaf Zacharias 25 May 2012 (has links)
Traditionally the tuning of DMC-type multivariable controllers is done by trial and error. The APC engineer would choose arbitrary starting values and test the performance on a simulated controller. The engineer would then either increase the values to suppress movement more, or decrease them to have the manipulated variables move faster. When the controller performs acceptably in simulation, then the tuning is improved during the commissioning of the controller on the plant. This is a time consuming and unscientific exercise and therefore often does not get the required attention, leading to unacceptable controller behaviour during commissioning and sub-optimal control once commissioning is completed. This dissertation presents a new method to obtain move suppression factors for DMC type multivariable controllers. The challenge in choosing move suppressions lies in the multivariable nature of the controller. Changing the move suppression on one manipulated variable will not only change the performance of that manipulated variable, it will also change the performance of every other manipulated variable with models to the same controlled variables. In the same way, changing the steady state cost of a manipulated variable or the equal concern error of a controlled variable will also affect the behaviour of every other manipulated variable with shared models. There have been attempts to calculate the required move suppression factors mathematically. Some methods used an approach that is based on the premise that move suppression factors that present a well-conditioned controller matrix will provide a well behaved controller in terms of tuning. Some other methods focussed on providing parameters that will cause desirable controlled variable response, either by determining tuning parameters offline, or by re-tuning the controller in real time. The method described in this paper uses a Nelder Mead (Nelder and Mead, 1965) search algorithm to search for move suppressions that will provide acceptable control behaviour. Acceptable behaviour is defined by characterising the dynamic move plan calculated by the controller for each of the manipulated variables, or by characterising the controlled variable path that will result from the manipulated variable moves. The search algorithm can change the move suppressions, the steady state costs, or the move suppression multipliers as used in DMC type controllers. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted
2

Novas abordagens para estudos em leptospirose: contribuindo para o desenvolvimento de vacinas / New approaches for leptospirosis studies: contributing to vaccine development

Grassmann, André Alex 09 January 2015 (has links)
Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-08-30T12:51:03Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_andre_alex_grassmann.pdf: 4530859 bytes, checksum: 5ae8d428fc82e0464179c0d4fc50987b (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-09-01T19:12:33Z (GMT) No. of bitstreams: 2 tese_andre_alex_grassmann.pdf: 4530859 bytes, checksum: 5ae8d428fc82e0464179c0d4fc50987b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-09-01T19:12:42Z (GMT) No. of bitstreams: 2 tese_andre_alex_grassmann.pdf: 4530859 bytes, checksum: 5ae8d428fc82e0464179c0d4fc50987b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-09-01T19:12:54Z (GMT). No. of bitstreams: 2 tese_andre_alex_grassmann.pdf: 4530859 bytes, checksum: 5ae8d428fc82e0464179c0d4fc50987b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-01-09 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / A leptospirose é uma doença tropical negligenciada, de caráter zoonótico, responsável por cerca de 873 mil casos humanos e 49 mil mortes em todo o mundo a cada ano. O agente causador pertence ao gênero Leptospira, um grupo antigenicamente e geneticamente diverso de espiroquetas, dividido em nove espécies patogênicas, 24 sorogrupos e mais de 250 sorovares. As leptospiras podem infectar praticamente qualquer espécie de mamífero. Roedores podem carrear leptospiras nos túbulos renais, eliminando-as em grande número através da urina, sendo esta a fonte mais importante para novas infecções. Em hospedeiros suscetíveis, as leptospiras patogênicas se espalham no organismo resultando em uma doença febril com icterícia, seguida de falência renal, hepática e cardíaca, que com frequência leva à morte. A vacinação é a abordagem profilática mais efetiva contra a leptospirose. A bacterina é a única vacina licenciada, sendo usada em todo o mundo para algumas espécies animais, enquanto o uso em humanos é permitido em apenas alguns poucos países. A razão para isso é a resposta imune de curta duração e sorovar-específica induzida por essa vacina, que apresenta ainda, efeitos colaterais adversos. Vários esforços para desenvolver uma vacina recombinante protetora contra diferentes sorovares e com resposta de longa duração, falharam. O pouco conhecimento sobre os fatores de virulência e a patogênese de Leptospira spp. são as principais razões para o lento avanço na descoberta de antígenos protetores. Esta tese apresenta várias abordagens diferentes de estudos em leptospirose na tentativa de acrescentar ao conhecimento acerca da doença e seu agente etiológico: O cenário atual de desenvolvimento de novas vacinas contra a leptospirose é devidamente revisado. Uma nova cepa virulenta de L. interrogans isolada de um cão com leptospirose aguda foi caracterizada e pode ser utilizada em experimentos de infecção em modelo animal, ou, ainda, para o entendimento de mecanismos de virulência. Foi desenvolvido um protocolo para obtenção de leptospiras adaptadas ao hospedeiro, através do cultivo destes organismos dentro de Câmaras de Membrana de Diálise (DMC) implantadas na cavidade peritoneal de ratos. Este protocolo foi utilizado para identificar, a partir do sequenciamento de RNA total (RNA-seq), genes relacionados com as mudanças sofridas pela Leptospira spp. para se adaptar ao hospedeiro durante a infecção, novos fatores de virulência e seleção de alvos para mutagênese. Finalmente, uma via alternativa para infecção de hamsters por L. interrogans virulenta foi descrita, mimetizando a entrada natural pela via transcutânea de leptospiras no hospedeiro. Esta metodologia pode substituir a injeção intraperitoneal de leptospiras. Juntos, estes achados representam um progresso substancial no campo de estudo da leptospirose e possivelmente irão contribuir para a descoberta futura de antígenos protetores para utilização no desenvolvimento de vacinas aperfeiçoadas contra leptospirose. / Leptospirosis is a widespread neglected tropical zoonotic disease responsible for at least 873,000 human cases and 49,000 deaths each year globally. The causative agent belongs to the genus Leptospira, a unique and genetically and antigenically diverse group of spirochetes divided into nine pathogenic species, 24 serogroups and more than 250 serovars. Leptospires can infect virtually any mammalian species. Rodents can carry spirochetes in their renal tubules and shed large numbers in their urine, the main source of leptospires for new infections. In susceptible hosts, pathogenic leptospires spread throughout the body, resulting in a febrile icteric illness, followed by renal, hepatic and cardiac failure that can lead to death. Vaccination is the most effective approach for leptospirosis prophylaxis. Bacterins are the only licensed vaccines, and are used worldwide in certain animals, however, human vaccination is approved in only a few countries. The reason for this is that the vaccine induces a serovar specific, short-term immune response that has several adverse side effects. Efforts to develop a new recombinant vaccine with long-term, cross-protective immunity have failed. The lack of knowledge of Leptospira spp. virulence factors and pathogenesis is the main reason for the slow progress in the discovery of protective antigens. This thesis describes several different approaches in leptospirosis studies in an attempt to improve understanding of the disease and its causative agent: The current scenario of leptospirosis vaccine development is comprehensively reviewed. A new L. interrogans virulent strain isolated from a dog presenting with acute leptospirosis was characterized and can be used for experimental infections in animal models, or for understanding virulence mechanisms. A protocol to obtain host-adapted leptospires cultivated within Dialysis Membrane Chambers (DMC) implanted in rat peritoneum was developed. This protocol was applied to the identification, by total RNA sequencing (RNA-seq), of several genes related to the changes that leptospires undergo during adaptation to infection, new virulence determinants and selection of targets for mutagenesis. Finally, an alternative route of infection of hamsters by virulent L. interrogans is described, mimicking the natural transcutaneous entry of leptospires into the host. This methodology could replace the intraperitoneal injection of leptospires. Together, these findings represent substantial progress in the field of leptospirosis, possibly contributing to the future discovery of protective antigens for the development of improved vaccines against leptospirosis.
3

Europeiska mötesdestinationer : En jämförelsestudie om professionella möten & mötesindustrin i Stockholm, Warszawa & Rom

Kyritsis Froelich, Nikolaos Christian, Keding, Caroline, Margarone, Luisa January 2011 (has links)
The meeting industry is a growing industry around the world, and the technological development in recent decades is one of the contributing factors to the increased travel opportunities and meeting industry's expansion. It can be assumed that the technology could replace some of the personal meetings, but humans have always had a need to meet in physical locations in work related purposes, therefore there is no evidence that personal meetings will disappear. Technological development should be seen as complementary rather than a substitute to the existing professional meetings. Public and private sectors within countries has drawn attention to meeting industry's potential, as favored destinations in terms of economic administration, image creation, expansion and acquisition of further market share in the global market. Meeting industry is complex precisely because there are so many different actors and stakeholders that integrate. For a destination to differentiate them and excel in the increasingly global world needed an elaborate marketing plan and effective cooperation between the various actors at the destination. Usually the largest professional meetings takes place in cities where there is capacity to receive large numbers of visitors. Essential elements for sustainable meeting industry are mutually dependent network relationships with strong organizational skills, and are of primary importance to a functioning whole. Among the various meeting actors, Convention Bureau occupy key role as the representative, the primary aim is to market the destination, display options, and finally bring together stakeholders with meeting participants. Lack of a Convention Bureau inhibit communication between meeting participants and stakeholders, also weakened the meeting related image because of incomplete representation.
4

Sociala medier inom destinationsmarknadsföring : Om Stockholms och Sigtunas arbete med sociala medier

Sillfors, Viktor, Salman, Irak January 2012 (has links)
Syftet med denna studie är att undersöka vad destinationsmarknadsföringsorganisationerna (DMC) Stockholm Visitor Board och Destination har för syn gällande sociala medier. Samt att titta på hur dessa två arbetar med sociala medier i sin marknadsföring och även vilka fördelar och nackdelar en sådan marknadsföring kan ha. Studien har haft en kvalitativ utgångspunkt när det gäller metodval. Men ett inslag av kvantitativa aspekter har förekommit då en enkätstudie har utförts. Flertalet kvalitativa intervjuer har ägt rumt med relevanta personer för denna studie. En vardera representant från Stockholm Visitor Board och Destination Sigtuna har intervjuats. Även personer från den akademiska världen har kommit tills tals för att ge sin syn på sociala medier både generellt men även som ett marknadsföringsverktyg. Utifrån intervjuerna så har författarna kommit fram till att både Stockholm Visitor Board och Destination Sigtuna vill och strävar efter att ha en personlig kontakt via sociala medier med sina besökare. Detta är dock något som de inte lyckats med anser författarna. Närmast att lyckas kommer Destination Sigtuna. Då båda är mitt uppe i en ny satsning kring sociala medier så kommer det troligtvis ske stora förändringar när det gäller sociala medier för båda dessa företag. Det författarna menar är att dessa två använder sociala medier likt ett traditionellt sätt att marknadsföra sig, något som det inte är skapat för. Sociala medier ska inbringa till kommunikation mellan människor, både som företag till kund men även från människa till människa. Fördelarna med att marknadsföra sig via sociala medier är att det är ett billigt och enkelt att göra det. Det tar inte mycket av din tid och det kostar inte speciellt mycket. Men det krävs att man marknadsför sig på rätt sätt, annars kan det stjälpa mer än hjälpa. Nackdelarna är då att, som sagt, man gör det på rätt sätt. Att vara närvarande via sociala medier är viktigt, annars kan man inte svara på det som sägs om ens företag. / This study has as purpose to analyze how two destination management companies reflect on social media. The two companies are Stockholm Visitor Board and Destination Sigtuna. The authors also want to analyze how they market themselves via social media and what the advantages and downsides of such marketing strategy may be. By using a qualitative research point with several interviews, the authors wanted to come with an answer to the purpose of this study. The authors came to the conclusion that neither Stockholm Visitor Board nor Destination Sigtuna uses social media as the media is attended to do. They talk about having a personal level of communication, but they do not pursue it. This is something that probably will change do to that both are in a reorganization within the social media aspect. The advantages of marketing via social media are many. It’s a cheap and easy way to market your company. And if you do it right, it will save you a lot of money. The downside is the absent from social media. If your company isn’t on social media and talk to the costumers, it can be quite expensive in the long run.
5

Návrh robotického pracoviště pro laserové značení automotive komponent / Design of a Robotic Cell for Laser Marking of Automotive Components

Pátek, Václav January 2021 (has links)
This diploma thesis is focused on the design of a robotic workstation for laser marking of aluminium hinges for the automotive industry. Robots remove wheel hinges from palettes at the end of a preassembly line, mark them a sort them. At first, selected marking technologies used in the automotive industry are introduced. Afterwards, a few robot and process simulation software are described. Subsequently, several layout variants are created as viable options for process handling and the chosen variant is designed in detail. Using RobotStudio software, a simulation of the robotic marking cell is made for process verification. Finally, a technical - economic evaluation is performed.
6

Προβλεπτικός έλεγχος για ιπτάμενα οχήματα

Πιπεράκης, Στυλιανός 31 May 2012 (has links)
Στην προκειμένη εργασία μελετάται όλο το θεωρητικό υπόβαθρο για τον προβλεπτικό έλεγχο για τις δύο κατηγορίες συστημάτων (Single Input-Single Output SISO, Multiple Input-Multiple Output MIMO). Αρχικά μελετάται η πρώτη μορφή προβλεπτικού ελέγχου που ήταν ο δυναμικός έλεγχος μητρών (DMC). Στην συνέχεια ακολουθεί το πρόβλημα του βέλτιστου προβλεπτικού ελέγχου διακριτού χρόνου όπως αυτό παρουσιάζεται και αναλύεται στην θεωρία του κ. Μaciejowski. Αμέσως μετά μελετάται πάλι το πρόβλημα εύρεσης βέλτιστου προβλεπτικού ελέγχου διακριτού χρόνου αλλά με την χρησιμοποίηση των διακριτών ορθοκανονικών συναρτήσεων βάσης Laguerre όπως αναλύεται από τον κ. Wang στο βιβλίο του. Στις δύο επόμενες ενότητες παρουσιάζονται οι ορθοκανονικές συναρτήσεις βάσης Laguerre συνεχούς χρόνους καθώς και μια άλλη κατηγορία, οι συναρτήσεις Κautz και αναλύεται ο τρόπος που υπολογίζεται ο προβλεπτικός έλεγχος συνεχούς χρόνου με τη χρήση αυτών. Αφού ο αναγνώστης αποκτήσει τις γνώσεις που χρειάζονται πάνω στον προβλεπτικό έλεγχο, ακολουθεί μια πρακτική εφαρμογή πάνω σε ένα ελικόπτερο 2 βαθμών ελευθερίας της Quanser. Εκεί αρχικά αφού περιγραφεί πλήρως η διάταξη μελετάμε τα προβλήματα ελέγχου πρώτα με Pole Placement στην συνέχεια με LQR καθώς και με την χρησιμοποίηση εκτιμητών κατάστασης όπως κάποιο παρατηρητή (observer) ή φίλτρο Kalman πάντα με τη βοήθεια του Μatlab και του Simulink. Επίσης όλη η θεωρία του ΜPC που μελετήσαμε έχει εφαρμοσθεί επιτυχώς σε προσομοίωση στο Μatlab και Simulink. Παρουσιάζονται ο κώδικας που χρειάζεται κάθε φορά καθώς και ενδιαφέροντα αποτέλεσματα για την απόκριση της διεργασίας. Επιπλέον μελετήθηκε το toolbox του Matlab για τον προβλεπτικό έλεγχο (MPC Toolbox). Τέλος οι παραπάνω έλεγχοι εφαρμόσθηκαν κατευθείαν στην πραγματική διεργασία (μη γραμμική) και τα αποτελέσματα ήταν ικανοποιητικά. / This work presents all the necessary theory for the Model Predictive Control for both system categories (Single Input-Single Output SISO, Multiple Input-Multiple Output MIMO). To start, the earliest form of MPC called dynamic matrix control (DMC) is studied. Then the optimal Model Predictive Control for discrete time is analyzed based on the theory that Maciejowski presented. Afterwards the same problem is studied using the discrete time Laguerre orthonormal base functions and the optimal Model Predictive Control is computed as presented in Wang’s theory. In the next two chapters the reader will be guided through the continuous time Laguerre and Kautz orthonormal base functions and how they are used in computing the optimal continuous time Model Predictive Control. Since the reader has acquired all the necessary knowledge about MPC, a practical approach on the Quanser’s two degrees of freedom helicopter follows. Initially, after we have fully described the plant and all its components, we study the control problems using the pole placement and LQR techniques along with state estimators such as observers and Kalman filter, always in the Matlab and Simulink enviroment. Next, the MPC approaches we’ve studied are applied successfully, again using Matlab and Simulink. In every case, all the necessary programs and results are presented in detail. Addionally, the Matlab MPC Toolbox is studied along with its results for the problem. Finally all those controls are applied directly to the real nonlinear plant successfully and the results are discussed.
7

Contribuição ao estudo de controle plantwinde: controle indireto e coordenação de controladores descentralizados.

Hori, Eduardo Shigueo 28 March 2005 (has links)
Made available in DSpace on 2016-06-02T19:55:38Z (GMT). No. of bitstreams: 1 TeseESH.pdf: 888621 bytes, checksum: 78265ad461fce078c72dd73a8ce9da02 (MD5) Previous issue date: 2005-03-28 / The design of plantwide control systems has received increasing attention in the last years. The modern chemical plants usually consist of hundreds of interconnected elementary processes and unit operations (large scale complex systems). These plants are usually characterized and dominated by large and highly integrated and automatized installations, with several recycle streams, more heat integration and fewer inventories. All these factors lead to high interactions among the subunits caused by material and energy recycle and, consequently to the need for a perspective beyond individual units. The plantwide system control design procedure is not clear and the literature is scarce about this issue, comparatively with simple unit design. In this way, a large challenge for the Chemical Engineer in the last decades has been designing control systems that operate with safety and bring the performance objectives needed to control these complex plants. The main objective of this project is to study the plantwide control problem aiming, particularly, the choice of controlled variables and the coordination of several decentralized controllers to avoid conflicting control actions. The results presented in this thesis show that the work objective was reached successfully, due to a significant contribution to plantwide control study. / O projeto de sistemas de controle de plantas inteiras ( plantwide ) tem recebido muita atenção nos últimos anos. As plantas químicas modernas são, usualmente, formadas por centenas de processos elementares e operações unitárias interconectados. Dessa forma, essas plantas são, normalmente, caracterizadas e dominadas por instalações enormes, altamente integradas e automatizadas, com muitas correntes de reciclo e menos inventários. Todos esses fatores levam a grandes interações entre as unidades, causadas pelo reciclo de material e de energia, e, portanto, à necessidade de perspectivas de controle que não se restrinjam a unidades individuais. O procedimento de projeto de sistemas de controle dessas plantas inteiras não é muito claro e a literatura ainda é escassa sobre o assunto, comparativamente com o projeto de controladores de unidades simples. Dessa forma, um grande desafio para o Engenheiro Químico nas últimas décadas tem sido o projeto de sistemas de controle que operem com segurança e atinjam os objetivos de desempenho necessários para o controle dessas plantas complexas. Por esses motivos, o principal objetivo deste trabalho é estudar o problema do controle plantwide visando, em particular, a escolha de variáveis a serem controladas e a coordenação de diversos controladores descentralizados de forma a evitar ações de controle conflitantes. Os resultados apresentados nesta tese mostram que o objetivo do trabalho foi alcançado com sucesso, visto que há uma contribuição significativa ao estudo de controle plantwide .
8

Digital Lots : En kvalitativ studie om offentliga sektorn roll i att stötta företag i regionen med digital transformation

Qvarfordt, Oskar January 2020 (has links)
The digital environment we live in today puts pressure on businesses to adapt and digitally transform their organizations. In 2018 Örnsköldsviks municipality started Digilots, a program which aims to help organizations in the region with digital transformation. This thesis intention is to help the municipality and other actors in the public sector understand the challenges and needs of small to medium sized enterprises (SME) to better help them support these companies in their digital transformation. The study accomplishes this by looking at previous research on the subject as well as collecting empirical data from SMEs in the region of Örnsköldsvik. The purpose of the study is therefore to investigate how actors from the public sector can aid SMEs in their digital transformation. The study finds that there are multiple challenges faced by both the SMEs in the region and within the municipality. The challenges include mainly a lack of knowledge and resources needed to pursue a digital transformation. This thesis contributes to the current body of research in two ways. The first is a practical contribution to Örnsköldsvik municipality in the form of a new way for them to engage with SMEs and help them with their digital transformation. Secondly the study presents empirical evidence on the struggles of digital transformation of SMEs and how the public sector can help address issues faced by SMEs.
9

Charakterizace elektrolytů na bázi směsi iontová kapalina a aprotické rozpouštědlo / Electrolytes characterization based on mixtures of ionic liquids and aprotic solvents

Šašek, Martin January 2017 (has links)
The thesis deals with liquid aprotic electrolytes based on mixtures of ionic liquid and solvent. EmimBF4, namely 1-ethyl-3-ethylimidazolium tetrafluoroborate, was used as the starting ionic liquid. A mixture of propylene carbonate, ethylene carbonate and dimethyl carbonate was used as solvents. Electrolytes were enriched with two electrolyte salts LiBF4 and NaBF4 from the resulting mixtures selected the most suitable electrolytes for Li-ion and Na-ion accumulators. Electrolytes were selected taking into account the required properties: the width of the potential window, the measured electrical conductivity and, last but not least, the safety.
10

HRM digitalization in emerging economies : A qualitative study on the factors influencing the implementation of digital HR tools in Russian SMEs

Churilina, Mariia January 2021 (has links)
Background: Digital technologies have been revolutionizing the corporate world during the last few decades. Companies that want to keep their competitive positions are forced to adapt. The digitalization of the corporate Human Resource function is of special importance in this regard due to the increasing role of digitalized HRM for business success. The existing research on the digital HRM implementation environment and the factors that shape it is limited to bigger companies operating in developed economies, with nascent research available for small and medium-sized firms operating in emerging economies. Purpose: The purpose of this study is to explore how individual-, firm-level and environmental context-specific factors shape HRM digitalization in SMEs in emerging economies context with Russia as an example. Method: To achieve an in-depth understanding of the research phenomenon, a qualitative study with an exploratory design was conducted. Empirical data was gathered through semi-structured interviews with ten professionals with extensive experience in HRM digitalization in SMEs, chosen by purposive sampling method. An abductive research approach enabled establishing the connection between obtained empirical insights and existing knowledge from the literature on HRM digitalization. Conclusion: As a result, the following factors were identified as the most influential for the implementation of digital HR tools in Russian SMEs. At the individual level, it is top executives digital awareness and innovativeness that facilitate implementation. At the firm level, it is SME’s resource munificence, innovation-friendly corporate culture, low hierarchical structure and developed IT infrastructure that enables implementation. Finally, among context-specific factors, the following appeared to shape the implementation: declining national economy, unpredictable business environment, highly competitive business environment, IT vendors' market specificity, governmental policy in terms of digitalization, labour market specificity. Most of the contextual factors contributed to the disabling environment for HRM digitalization, with a few exceptions.

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