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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.
71

Commande prédictive distribuée pour un réseau de systèmes partiellement coopératifs. / On a partially cooperative distributed control framework with priority assignment

Ding, Haiyang 10 July 2013 (has links)
Une structure de contrôle distribué partiellement coopérative est proposée dans cette thèse. La structure est consacrée au problème de commande d’un réseau composé de sous-systèmes non linéaires/linéaires qui sont interconnectés par leurs états et les entrées de commande. Par la coopération partielle, cela signifie que chaque sous-système est capable de préserver son propre objectif en utilisant un indice de la coopération ajustable qui définit dans quelle mesure il accepte de dégrader son propre niveau de performance afin d’aider ses voisins à maintenir leur intégrité sous les interconnexions potentiellement déstabilisantes. La communication entre les sous-systèmes est basée sur l’échange de niveaux de fonction de Lyapunov avec les contraintes associées et la quantité d’information transmise est plutôt réduite par rapport aux travaux les plus récents. Une autre caractéristique intéressante de cet structure de contrôle distribué non linéaire coopératif est l’utilisation de vecteurs prioritaires par chaque sous-système. Ce vecteur définit un ordre hiérarchique de l’importance de ses voisins menant à une stratégie de coopération dans lequel les sous-systèmes critiques dans le réseau peuvent être préservés en dépit des interactions. Une version linéaire de la structure de contrôle distribué coopératif est présenté. Cette conception de structure linéaire conduit à une évaluation rigoureuse de stabilité du réseau en boucle fermée globale. Une méthode d’amélioration de la stabilité est proposée basée sur la résolution d’un problème d’optimisation non convexe avec des degrés de liberté liés au paramétrage de l’affectation de priorité. Pour montrer son efficacité, le contrôle distribué coopératif proposé pour le réseau linéaire est appliqué pour traiter le problème de contrôle de la fréquence de charge dans un réseau d’alimentation et le problème de contrôle du système cryogénique. / In this dissertation, a partially cooperative distributed control framework is proposed. The framework is dedicated to the control problem for a network consisting of linear/nonlinear subsystems that are interconnected through their states and control inputs. By partial cooperation, it means that each subsystem is able to preserve its own objective while using a tunable cooperation index that defines to what extend it accepts to degrade its own performance level so as to help its neighbors maintain their integrity under potentially destabilizing interconnections. The communication between the subsystems is rather reduced comparing to most of the existing contributions. Another attractive feature of the proposed framework is that each subsystem in the network can be assigned with priority indicating the importance of the corresponding subsystem seen by its neighbors. Through proper parameterization of the priority assignment, improved performance of the subsystems and the network can be acheived. In the linear version, a rigorous stability assessment method is presented and a systematic way of proposing an optimized priority assignment for a given network is introduced as well. The proposed scheme is applied to handle the load frequency control problem in a 4-area power network and the control problem of a cryogenic system to illustrate its effectiveness.
72

Atenuação de Harmônicos nos Geradores Síncronos Provenientes das Cargas Não Lineares Utilizando Geradores de Indução / Attenuation of harmonics on synchronous generators arising from nonlinear loads using induction generators

Delbone, Edval 28 February 2012 (has links)
This work demonstrates the theoretical and experimental feasibility of a induction generator to work as an attenuator of the harmonics in main generators of on the electric power system, i.e., the synchronous generators. The induction and synchronous machines were analyzed in physical terms and established mathematical modeling in the frequency domain in order to prove the purpose of the thesis. Computer simulations were also carried out in the time domain and laboratory tests were made to check levels of attenuation of current harmonics (THDi) in accordance with the maximum standardized voltage harmonic distortion (THDv). Furthermore, this work presents a study of technical and economical feasibility of a typical application. / Este trabalho demonstra a viabilidade teórica e experimental de um gerador de indução funcionar como um atenuador dos harmônicos nos geradores principais do sistema elétrico de potência, ou seja, os geradores síncronos. Foram analisadas as máquinas de indução e síncronas do ponto de vista físico e estabelecidas modelagens matemáticas no domínio da frequência, a fim de comprovar o objetivo da tese. Foram realizadas também´em, simulações computacionais no domínio do tempo e ensaios em laboratório para verificar os n´níveis de atenuação de harmônicos de corrente (THDi) em conformidade com os limites máximos de distorções harmônicas de tensão (THDv) normalizados. Apresenta-se também neste trabalho um estudo de viabilidade técnica e econômica de uma aplicação típica. / Doutor em Ciências
73

Do bailouts make banks “too interconnected to fail”?: the effects of TARP on the interbank market and bank risk-taking

Wang, Weichao 09 May 2018 (has links)
Submitted by Weichao Wang (weichao.wang@fgv.edu.br) on 2018-05-11T16:03:27Z No. of bitstreams: 1 Wang2018_Thesis_TARP_Interbank_Risk_May9.pdf: 2618673 bytes, checksum: dc1254edf6febf9dacf740dc3f7d48a8 (MD5) / Rejected by Diego Andrade (diego.andrade@fgv.br), reason: A ordem dos documentos está errada. on 2018-05-14T18:11:37Z (GMT) / Submitted by Weichao Wang (weichao.wang@fgv.edu.br) on 2018-05-14T18:24:47Z No. of bitstreams: 1 Wang2018_Thesis_TARP_Interbank_Risk_May9.pdf: 2618806 bytes, checksum: add9b0e474645e1acb2fd7f4b86eb1f2 (MD5) / Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2018-05-15T16:30:20Z (GMT) No. of bitstreams: 1 Wang2018_Thesis_TARP_Interbank_Risk_May9.pdf: 2618806 bytes, checksum: add9b0e474645e1acb2fd7f4b86eb1f2 (MD5) / Made available in DSpace on 2018-05-18T12:30:42Z (GMT). No. of bitstreams: 1 Wang2018_Thesis_TARP_Interbank_Risk_May9.pdf: 2618806 bytes, checksum: add9b0e474645e1acb2fd7f4b86eb1f2 (MD5) Previous issue date: 2018-05-09 / I investigate how the Troubled Asset Relief Program (TARP) affected the stressed interbank money market trading during the recent financial crisis via a difference-in-difference (DiD) design. I find that the TARP capital injection significantly enlarged the interbank exposure for the TARP recipients relative to others, particularly for banks in smaller size, with lower level of interbank trading and located in relatively poor economic conditions. I further test whether the distorted interbank liquidity position of the TARP recipients stimulated their credit risk appetite. I find that TARP recipient banks with larger interbank exposure also significantly shifted to riskier credit portfolios than others after the TARP implementation, suggested by estimates on forward- and backward-looking risk measures. Results are robust to the instrumental variable analysis, the sample self-selection model, the propensity score matching analysis, various placebo experiments and alternative econometric models. My results are most consistent with the “capital spillover” hypothesis that banks used the TARP capital to develop more interconnected interbank relationships, and the moral hazard effect that higher future bailout expectation and increased systemic relevance jointly construct a “new government safety net” for the TARP beneficiaries to take excessive credit risks under the implicitly perceived “too interconnected to fail” protection.
74

Smart grid critical information infrastructure protection through multi-agency

Mavee, Sheu Menete Alexandre 30 June 2015 (has links)
M.Com. (Informatics) / Critical Infrastructure is the term used to describe assets that are of utmost importance, or in other words, essential in the functioning of an environment. Societies depend on their critical infrastructure in order to maintain and continuously improve on their population’s standard of living. The creation of more self-sustainable methods of energy consumption and generation drives towards the creation of a better and more efficient evolution of the power grid critical infrastructure, named the smart grid. The introduction of the smart grid brought in a paradigm shift towards the practices used to manage the generation and distribution of electric power. The introduction of highly capable information systems to intrinsically work with current power grid technologies provided the ability to enhance economic and environmental efficiency of power systems. Although providing a wide variety of benefits, such information systems also created new points of vulnerabilities, which if exploited, place the smart grid at risk of disruptions. In order to address the security issues that occur at the application and data exchange level of smart grid information systems, the dissertation proposed the use of a security model to protect the smart grid. The Multi-Agent Smart Grid Security (MA-SGS) model is based on the use of multiple autonomous intelligent software agents which attempt to create operational stability and efficiency in the smart grid...
75

Evaluation of Hydraulically InterconnectedSuspension Systems on TARA Machine

Yu, Jingyao January 2023 (has links)
The TARA machine from Volvo is equipped with hydraulic suspension which can be connected with each other in different ways. The present study focuses on enhancing the dynamic performance of the TARA machine during its operations through the investigation of various hydraulically interconnected suspension (HIS) systems. Employing a comprehensive cosimulation approach using Adams Car (ACar) and MATLAB Simulink, a full-vehicle analysis was conducted. The TARA machine was modeled in ACar, while the Simulink environment was utilized to design the control system and implement the HIS configuration. The HIS system was connected within two wheels, explored with three different connection types: pendulum, cross or individual connections. The model was simulated in pitch, roll, bounce and warp modes, achieved by running on different road conditions generated in ACar. The change of different HIS systems were achieved by manipulation of the hydraulic circuit in Simulink. By analyzing the dynamic performance of the HIS systems in terms of acceleration, the study aims to identify the most favorable HIS configuration on TARA machine. This investigation provides valuable insights for optimizing the overall operational dynamics of TARA machines, thereby contributing to the development of advanced HIS systems in the field. / Den TARA-maskinen från Volvo är utrustad med hydraulisk fjädring som kan kopplas samman på olika sätt. Den aktuella studien fokuserar på att förbättra den dynamiska prestandan hos TARA-maskinen under dess drift genom undersökning av olika hydrauliskt sammanlänkade fjädringssystem (HIS). Genom att använda en omfattande sam-simulering med Adams Car (ACar) och MATLAB Simulink utfördes en helhetsanalys av fordonet. TARA-maskinen modellerades i ACar medan Simulink-miljön användes för att utforma kontrollsystemet och implementera HIS-konfigurationen. HIS-systemet var kopplat mellan två hjul och utforskades med tre olika typer av kopplingar: pendel, korsning eller individuella kopplingar. Modellen simulerades i lutning, roll, studs och förvrängning, vilket åstadkoms genom att köra på olika vägförhållanden genererade i ACar. Förändringen av olika HIS-system åstadkoms genom manipulering av hydraulikkretsen i Simulink. Genom att analysera HIS-systemens dynamiska prestanda i form av acceleration syftar studien till att identifiera den mest fördelaktiga HIS-konfigurationen för TARA-maskinen. Denna undersökning ger värdefulla insikter för att optimera den övergripande operationella dynamiken hos TARA-maskiner och bidrar därmed till utvecklingen av avancerade HIS-system inom området.
76

Sustainability Education at Industrial Engineering Programs in Sweden : A study of the relevant and received sustainability education, and the associated challenges, at 5-year industrial engineering programs / Hållbarhetsundervisning vid Industriell Ekonomiprogram i Sverige : En studie av den relevanta och erbjudna hållbarhetsundervisningen, samt dess utmaningar, vid civilingenjörsprogram inom industriell ekonomi

Albiz, Niccolas January 2015 (has links)
The public concern for sustainability issues is ever increasing whilst the trust in corporations is decreasing. CEOs now see sustainability concern and compliance as an important component in retaining their competitive advantage and regaining the trust of their surrounding community. For these reasons it is important to find new manners of uniting societal improvement with business, requiring new forms of competencies. This study has investigated what sustainability education is actually central to the industrial engineering profile, as well as what of this is then covered in the programs. The study involved two phases. The first involved interviewing experts as to what was central for these engineers to learn, resulting in a content list. The second phase involved mapping the instances of this content in the five largest industrial engineering programs (covering circa 74% of these students) as well as the associated challenges to broaching this content. The first phase was primarily qualitative whilst the second phase was largely quantitative, though each data point consisted of a qualitative interview. Five key insights can be drawn from the study regardless of normative stand-point. 1) The sustainability topics that were deemed relevant cover a vast area of disciplines and aspects. 2) There is a skewedness in the content covered, favouring the environmental aspects. 3) There is a lack of integrative instances where the knowledge from different sources and perspectives is synthesized. 4) The key challenges revolve around concept definition and communication. 5) The normativity, interconnectedness and pedagogics contribute with uncertainty and complexity in the assessment of sustainability education. The study is finalized with a synthesis of the various insights to arrive at the conclusion that having sustainable business practice as the aim of the programs, establishing common content goals and employing active learning approach would circumvent many of the perceived challenges as well as align the programs with the need of the industry. This study contributes with deeper understanding of the sustainability education required and provided to industrial engineering students in Sweden. As such the study has practical applications for the programs studied. The theoretical implications of this study lie in the empirical data achieved regarding the topics of relevance to these engineers, showing high levels of agreement with current literature, as well as the perceived challenges to broaching this content in the current curricula. Furthermore it provides empirical data as to the sustainability education received at different programs. / Allmänhetens intresse över hållbarhetsfrågor ökar samtidigt som tilliten för företag minskar. Företagsledare ser numera hållbarhet som en viktig komponent i att bibehålla deras konkurrenskraft och att återfå allmänhetens tillit. Det är således viktigt att finna nya sätt att förena samhällsnytta med företagande, vilket kräver nya sorters kompetens inom hållbarhetsområdet. Denna studie har undersökt vilka hållbarhetsämnen som är centrala för industriell ekonomistudenten, givet deras profil i näringslivet, samt vad av detta som berörs i programmen. Studien var indelad i två faser. Den första ämnade till att skapa en lista av de, för dessa ingenjörer, centrala ämnen genom intervjuer med experter inom området. Den andra fasen kartlagde de ämnen som berördes inom de fem största industriell ekonomiprogrammen (täckandes cirka 74% av studenterna) samt vilka utmaningar som associerades till detta arbete. Den första fasen var till stora delar kvalitativ. Den efterföljande fasen var en kvantitativ kartläggning där varje datapunkt representerade en kvalitativ intervju. Ur studien uppkom fem nyckelinsikter, som står sig oavsett normativ ståndpunkt. Dessa inkluderade: 1) De hållbarhetsämnen som ansågs relevanta för denna målgrupp spänner en vid area av discipliner och aspekter. 2) Fördelningen på ämnen som täcks inom programmen påvisar en preferens mot den miljömässiga aspekten. 3) Det finns en brist på integrerande instanser i utbildningarna, där kunskap från olika aspekter och källor sammankopplas. 4) Nyckelutmaningarna centreras runt definiering och kommunikation. 5) Normativitet, sammankoppling och pedagogik bidrar alla till osäkerhet och komplexitet i bedömning av hållbarhetsutbildningar. Studien avslutas med en syntes av de olika insikterna för att komma till slutsatsen att hållbart företagande som övergripande syfte för utbildningarna, en gemensam målbild för innehållet samt komplettering med ”active learning” metodiker skulle övervinna många av de uppfattade utmaningarna samtidigt som det skulle uppfylla näringslivets kompetensbehov för framtida konkurrenskraft. Denna studie bidrar till förståelsen över vilken hållbarhetsutbildning som bedrivs och vilken som anses behövd av industriell ekonomistudenter i Sverige. Studien har därmed praktiska implikationer för de program som studerades. Teoretiska bidrag inkluderas av den empiriska data som framtagits gällande relevanta hållbarhetsämnen vilka uppvisar hög konvergens med litteraturen inom ämnen, samt de upplevda utmaningar kring att inkludera detta ämne i befintliga program. Vidare bidrar studien med empirisk data kring det som faktiskt berörs idag på de olika industriell ekonomiprogrammen.
77

Supporting At-Risk Students Through the Interconnected Systems Framework: Perspectives of Specialized Instructional Support Personnel

Sandoval, Luis Angel 01 January 2024 (has links) (PDF)
The number of students with mental health challenges has increased significantly in public schools during the past 10 years. Despite school and community efforts many students remain underserved, specifically at-risk populations. At-risk youth are more likely to experience adverse life outcomes such as performing poorly in school, dropping out of school, acting violently, and facing higher instances of mental health challenges when compared to peers with fewer risk factors. The purpose of this qualitative study was to examine specialized instructional support personnel’s attitudes and willingness to implement a change model, ISF, to support at-risk youth in the public school system. A secondary aim of this study was to answer the question of the attitudes of specialized instructional support personnel to provide insight for decision makers considering adopting this change model. The research question posed was: What are specialized instructional support personnel’s attitudes toward implementing a mental health change model, ISF, in their school district? This study also contributed to furthering the knowledge of a complex service delivery system intended to enhance student performance by identifying support structures that promote student wellness. The results of this study indicated the specialized instructional support personnel interviewed would be willing to support elements of the ISF.
78

Teacher Developmen in Cuba : An analysis of two strategies

Buchberger, Helena January 2013 (has links)
The aim of this study is to describe two strategies of professional teacher development in Cuba and analyse how they affect the professional growth of the teachers. The strategies investigated are methodological work sessions and further education at the university. Eight upper-secondary school teachers were interviewed and it was analysed how their professional growth was affected by the Cuban professional development strategies. The model utilized was the interconnected model of professional growth (Clarke & Hollingsworth, 2002).The results show that, four of the eight interviewed teachers experienced change sequences and growth networks as a consequence of participating in the two investigated strategies. The methodological work sessions promote a collaborative approach among the teachers to developing the education in their school. Further education in the university, on the other hand, encourages the teachers to reflect individually on practical school-related problems. The results indicate that the organization of the work both the professional development strategies provided acted as an incentive for the interviewed teachers’ development. / Målet med den här studien är att beskriva två lärarutvecklingsstrategier i Kuba och analysera hur de påverkar lärarnas professionella utveckling. De undersökta strategierna är metodologiska arbetsmöten och vidareutbildning vid universitet. Åtta gymnasielärare intervjuades och det analyserades hur deras professionella utveckling påverkats av de kubanska lärarutvecklingsstrategierna. Modellen som använts är the interconnected model of professional growth (Clarke & Hollingsworth, 2002).Resultaten visar att de metodologiska arbetsmötena uppmuntrar lärarna att arbeta kollektivt med att utveckla utbildningen i sin skola. Universitetsvidareutbildning, vad andra sidan, främjar individuell reflektion över praktiska skolrelaterade problem. Resultatet indikerar att den organisation av arbetet som båda lärarutvecklingsstrategierna medför stimulerar lärarna att utvecklas.
79

Diagnostic de panne et analyse des causes profondes du système dynamique inversible / Fault diagnosis & root cause analysis of invertible dynamic system

Zhang, Mei 17 July 2017 (has links)
Beaucoup de services vitaux de la vie quotidienne dépendent de systèmes d'ingénierie hautement complexes et interconnectés; Ces systèmes sont constitués d'un grand nombre de capteurs interconnectés, d'actionneurs et de composants du système. L'étude des systèmes interconnectés joue un rôle important dans l'étude de la fiabilité des systèmes dynamiques; car elle permet d'étudier les propriétés d'un système interconnecté en analysant ses sous-composants moins complexes. Le diagnostic des pannes est essentiel pour assurer des opérations sûres et fiables des systèmes de contrôle interconnectés. Dans toutes les situations, le système global et / ou chaque sous-système peuvent être analysés à différents niveaux pour déterminer la fiabilité du système global. Dans certains cas, il est important de déterminer les informations anormales des variables internes du sous-système local, car ce sont les causes qui contribuent au fonctionnement anormal du processus global. Cette thèse porte sur les défis de l'application de la théorie inverse du système et des techniques FDD basées sur des modèles pour traiter le problème articulaire du diagnostic des fautes et de l'analyse des causes racines (FD et RCA). Nous étudions ensuite le problème de l'inversibilité de la gauche, de l'observabilité et de la diagnosticabilité des fauts du système interconnecté, formant un algorithme FD et RCA multi-niveaux basé sur un modèle. Ce système de diagnostic permet aux composants individuels de surveiller la dynamique interne localement afin d'améliorer l'efficacité du système et de diagnostiquer des ressources de fautes potentielles pour localiser un dysfonctionnement lorsque les performances du système global se dégradent. Par conséquent, un moyen d'une combinaison d'intelligence locale avec une capacité de diagnostic plus avancée pour effectuer des fonctions FDD à différents niveaux du système est fourni. En conséquence, on peut s'attendre à une amélioration de la localisation des fauts et à de meilleurs moyens de maintenance prédictive. La nouvelle structure du système, ainsi que l'algorithme de diagnostic des fautes, met l'accent sur l'importance de la RCA de défaut des dispositifs de terrain, ainsi que sur l'influence de la dynamique interne locale sur la dynamique globale. Les contributions de cette thèse sont les suivantes: Tout d'abord, nous proposons une structure de système non linéaire interconnecté inversible qui garantit le fauts dans le sous-système de périphérique de terrain affecte la sortie mesurée du système global de manière unique et distincte. Une condition nécessaire et suffisante est développée pour assurer l'inversibilité du système interconnecté qui nécessite l'inversibilité de sous-systèmes individuels. Deuxièmement, un observateur interconnecté à deux niveaux est développé; Il se compose de deux estimateurs d'état, vise à fournir des estimations précises des états de chaque sous-système, ainsi que l'interconnexion inconnue. En outre, il fournira également une condition initiale pour le reconstructeur de données et le filtre de fauts local une fois que la procédure FD et RCA est déclenchée par tout fauts. D'une part, la mesure utilisée dans l'estimateur de l'ancien sous-système est supposée non accessible; La solution est de la remplacer par l'estimation fournie par l'estimateur de ce dernier sous-système. / Many of the vital services of everyday life depend on highly complex and interconnected engineering systems; these systems consist of large number of interconnected sensors, actuators and system components. The study of interconnected systems plays a significant role in the study of reliability theory of dynamic systems, as it allows one to investigate the properties of an interconnected system by analyzing its less complicated subcomponents. Fault diagnosis is crucial in achieving safe and reliable operations of interconnected control systems. In all situations, the global system and/or each subsystem can be analyzed at different levels in investigating the reliability of the overall system; where different levels mean from system level down to the subcomponent level. In some cases, it is important to determine the abnormal information of the internal variables of local subsystem, in order to isolate the causes that contribute to the anomalous operation of the overall process. For example, if a certain fault appears in an actuator, the origin of that malfunction can have different causes: zero deviation, leakage, clogging etc. These origins can be represented as root cause of an actuator fault. This thesis concerns with the challenges of applying system inverse theory and model based FDD techniques to handle the joint problem of fault diagnosis & root cause analysis (FD & RCA) locally and performance monitoring globally. By considering actuator as individual dynamic subsystem connected with process dynamic subsystem in cascade, we propose an interconnected nonlinear system structure. We then investigate the problem of left invertibility, fault observability and fault diagnosability of the interconnected system, forming a novel model based multilevel FD & RCA algorithm. This diagnostic algorithm enables individual component to monitor internal dynamics locally to improve plant efficiency and diagnose potential fault resources to locate malfunction when operation performance of global system degrades. Hence, a means of acombination of local intelligence with a more advanceddiagnostic capability (combining fault monitoring anddiagnosis at both local and global levels) to performFDDfunctions on different levels of the plantis provided. As a result, improved fault localization and better predictive maintenance aids can be expected. The new system structure, together with the fault diagnosis algorithm, is the first to emphasize the importance of fault RCA of field devices, as well as the influences of local internal dynamics on the global dynamics. The developed model based multi-level FD & RCA algorithm is then a first effort to combine the strength of the system level model based fault diagnosis with the component level model based fault diagnosis. The contributions of this thesis include the following: Firstly, we propose a left invertible interconnected nonlinear system structure which guarantees that fault occurred in field device subsystem will affect the measured output of the global system uniquely and distinguishably. A necessary and sufficient condition is developed to ensure invertibility of the interconnected system which requires invertibility of individual subsystems. Second, a two level interconnected observer is developed which consists of two state estimators, aims at providing accurately estimates of states of each subsystem, as well as the unknown interconnection. In addition, it will also provide initial condition for the input reconstructor and local fault filter once FD & RCA procedure is triggered by any fault. Two underlyingissues are worth to be highlighted: for one hand, the measurement used in the estimator of the former subsystem is assumed not accessible; the solution is to replace it by the estimate provided by the estimator of the latter subsystem. In fact, this unknown output is the unknown interconnection of the interconnected system, and also the input of the latter subsystem.
80

Avaliação de sistemas de sacarificação e cofermentação simultânea em reatores de coluna visando à produção de etanol a partir de hidrolisado de bagaço de cana-de-açúcar / Evaluation of saccharification and simultaneous cofermentation systems in column reactors aiming at the production of ethanol from sugarcane bagasse hydrolyzate

Pereira, Juliana Rodrigues Fonseca 28 September 2018 (has links)
A produção de biocombustíveis de segunda geração está entre os temas mais pesquisados atualmente. Entre estes, a obtenção de etanol a partir de bagaço de cana-de-açúcar é de grande interesse nacional, considerando-se a abundância desta matéria-prima no país e a possibilidade de incremento na produção deste álcool sem necessidade de expansão da área plantada. Sob o ponto de vista de produção industrial, no entanto, é fundamental o desenvolvimento de trabalhos visando ao estudo de alternativas de processos e biorreatores susceptíveis de ampliação de escala. Estratégias como sacarificação e fermentação/cofermentação simultâneas (SSF/SSCF) têm sido estudadas e têm como vantagens a intensificação do processo pela redução do custo de investimento e minimização de problemas de inibição de enzimas por produtos. No entanto, neste caso, geralmente o uso de condições não otimizadas (temperatura) para cada passo biológico é desvantajoso. Com o objetivo de superar essa desvantagem, avaliou-se o uso de reatores de coluna interconectados para a produção de etanol a partir de bagaço de cana-de-açúcar empregando células de Scheffersomyces shehatae imobilizadas em alginato de cálcio em sistema SSCF. O bagaço foi previamente pré-tratado por processo alcalino e alcalino assistido por cavitação hidrodinâmica. Experimentos em SSCF em batelada foram realizados usando duas colunas interconectadas. Uma delas (para hidrólise) foi mantida a 50ºC e carregada com bagaço pré-tratado e a outra coluna (para fermentação) foi mantida a 30°C e carregada com células imobilizadas. Meio contendo preparação comercial de celulases e nutrientes para o micro-organismo foi recirculado entre as colunas. Os efeitos da vazão de recirculação e carga enzimática foram avaliados usando planejamento estatístico como ferramenta. Dados iniciais de hidrólise enzimática em reator de coluna mostraram elevada taxa de reação no início do processo, com redução desta ao longo da hidrólise devido à recalcitrância crescente do material residual à ação enzimática. Os resultados obtidos no planejamento estatístico mostraram que a carga enzimática foi a variável mais influente no processo, embora a vazão de recirculação e a interação entre as variáveis também tenham apresentado efeitos significativos. As condições selecionadas corresponderam a uma vazão de recirculação de 14 mL/min e carga enzimática de 15 FPU/g e os experimentos nestas condições resultaram em valores de fator de rendimento (Yp/s) de 0,493 g/g, produtividade volumétrica de 0,469 g.L-1.h-1 e eficiência de 96,58%. Além disso, nestas condições, 70,72±1,32 % da celulose presente inicialmente no material e 56,37±0,76 % da hemicelulose foram hidrolisadas. O sistema mostrouse adequado para realização do processo SSCF, com potencial para ser utilizado para intensificação da produção de etanol 2G em biorrefinarias. / Currently, the production of second generation biofuels is one of the most researched topics. Among these, the ethanol obtained from sugarcane bagasse is of great national interest, considering the abundance of this raw material in the country and the possibility of increasing the production of this alcohol without the need of expanding the crop area. From viewpoint of industrial production, however, the development of studies of process alternatives and bioreactors adequate for scale up is fundamental. Strategies as saccharification and simultaneous fermentation/cofermentation (SSF/SSCF) have been studied and have as advantages the intensification of the process by reducing the cost of investment and minimizing problems of inhibition of enzymes by hydrolysis products. However, in this case, generally the use of non-optimized conditions (temperature) for each biological step is disadvantageous. In order to overcome this drawback, the use of interconnected column reactors for the production of ethanol from sugarcane bagasse was evaluated using calcium alginate immobilized cells of Scheffersomyces shehatae in SSCF system. The bagasse was previously pretreated by alkaline and hydrodynamic cavitation-assisted alkaline process. Batch experiments of SSCF were performed using two interconnected columns. One of them (for hydrolysis) was kept at 50 ° C and loaded with pre-treated bagasse and the other column (for fermentation) was kept at 30 ° C and loaded with immobilized cells. Medium containing comercial preparation of cellulases and nutrients for the microorganism was recirculated between the columns. The effects of recirculation flow and enzymatic loading were evaluated using statistical design as a tool. Initial data on enzymatic hydrolysis in a column reactor showed a high reaction rate at the beginning of the process, with a reduction in the hydrolysis rate along the process due to the increasing recalcitrance of the residual material to the enzymatic action. The results obtained in the statistical design showed that enzymatic loading was the most influential variable in the process, although the recirculation flow rate and the interaction between the variables also had significant effects. The selected conditions corresponded to a recirculation flow rate of 14 mL/min and enzyme loading of 15 FPU/g and the experiments carried out under these conditions resulted in yield factor (Yp/s) values of 0.493 g/g, volumetric productivity of 0.469 gL- 1.h-1 and fermentation efficiency of 96.58%. Moreover, under these conditions, 70.72±1.32 % of the cellulose initially present in the material and 56.37±0.76 % of the hemicellulose were hydrolyzed. The system proved to be adequate to perform the SSCF process, with potential to be used to intensify the production of 2G ethanol in biorefineries.

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