Made available in DSpace on 2014-08-20T13:42:05Z (GMT). No. of bitstreams: 1 Dissertacao_Milena_Tomasi_ Bassani.pdf: 628517 bytes, checksum: af4a756ae84e13ef34c451b2d486162e (MD5) Previous issue date: 2009-10-27 / he accessory gene regulator (agr) is a S. aureus global regulator of virulence factors, as the staphylococcal enterotoxins (SE), responsible for the staphylococcal food poisoning. There are four different agr groups due to the polymorphism in the amino acids sequence of the agrC and agrD. In the literature is described a relationship among agr groups and virulence factors, diseases, preferential host and antibiotic resistance. In this context, it was aimed to characterize the agr groups through biplex PCR, and relationship among agr groups, enterotoxigenic and antimicrobian profiles of S. aureus isolated from foods and bovine mastitis milk. A total of 115 strains were used to characterize the agr groups , being 30 isolated from f bovine mastitis milk and 85 isolated from several sources of foods. To assess the relationship between agr groups and enterotoxin production were used 14/85 strains previously characterized for the presence of some enterotoxins (sea, seb, sec, sed e cluster egc). To determine the profile of antibiotics resistance were used 71/115 strains. We observed a prevalence of agr group II with19.1% (22/115 strains), followed by the agr I with 8.6% (10/115 strains), agr III with 7.8% (9 / 115 strains), and agr IV with6.0% (7 / 115 strains). Among the strains isolated from bovine mastitis milk agr group I was prevailed with 20% (6/30 strains), whereas in the strains isolated from several food sources was observed prevalence of agr group II with 32.7% (18/85 strains), especially among those from chicken meat. Among the 14 strains (14/85) that contained enterotoxin genes, the majority of them contained the cluster egc (70%) belonged to agr II, whereas no relationship was found with those who had the genes for the classical SE (sea, seb, sec, sed). Considering the antibiotic resistance 100% of bovine mastitis milk strains and from various sources of food were resistant to penicillin, ampicillin, cefoxitin, and vancomycin. Relationship was observed between food strains, which were resistant to vancomycin and agr II, however, no relationship was found between antibiotic profile and agr groups among the strains isolated from bovine mastitis milk. These results demonstrated the prevalence of agr II among food strains and agr I among bovine mastitis milk strains. Moreover, the strains that carried the cluster egc were predominant agr II, which could indicate the occurrence of a clonal group among those. Another important result obtained in this study was the high rate of S. aureus multiresistant strains isolated from food, which emphasizes the importance of dissemination of these strains among foods. / O accessory gene regulator (agr) é um regulador global de fatores de virulência em S. aureus, como as enterotoxinas estafilocócicas (EE), responsáveis pela intoxicação alimentar estafilocócica. São conhecidos quatro distintos grupos agr devido ao polimorfismo na seqüência dos aminoácidos de agrC e agrD. Na literatura descreve-se relação entre fatores de virulência, patogenias, hospedeiro preferencial e perfil de resistência a antibióticos com grupos agr. Neste contexto, objetivou-se caracterizar grupos agr através de biplex PCR, e relacioná-los com os perfis enterotoxigênico e antimicrobiano de cepas de S. aureus isoladas em alimentos e leite de vacas mastíticas. Para caracterização dos grupos agr foram utilizadas 115 cepas, sendo 30 isoladas em leite de vacas mastíticas e 85 em diversas fontes de alimentos. Para a relação entre grupos agr e produção de enterotoxina foram utilizadas 14/85 cepas previamente caracterizadas quanto à presença de alguma enterotoxina (eea, eeb, eec, eed e cluster egc), já para determinar o perfil de resistência a antibióticos utilizaram-se 71/115 cepas. Observou-se uma prevalência do grupo agr II, com 19,1% (22/115 cepas), seguido do agr I, com 8,6% (10/115 cepas), agr III 7,8% (9/115 cepas), e agr IV, 6,0% (7/115 cepas). Entre as cepas isoladas em leite de vacas com mastite houve predomínio do grupo agr I, com 20% (6/30 cepas); já nas cepas isoladas de diversas fontes de alimentos observou-se prevalência do grupo agr II, com 32,7% (18/85 cepas), especialmente entre as provenientes de carne de frango. Entre as 14/85 cepas que carreavam genes de enterotoxinas, a maioria que albergava o cluster egc (70%), pertencia ao grupo agr II, enquanto nenhuma relação foi observada com aquelas que possuíam os genes para as EE clássicas (eea, eeb, eec, eed). Com relação ao perfil de resistência antimicrobiana, 100% das cepas isoladas de leite de vacas com mastite e das diversas fontes de alimentos apresentaram resistência à penicilina, ampicilina, cefoxitina e vancomicina. Observou-se relação entre cepas isoladas de alimentos, que eram resistentes à vancomicina e grupo agr II, entretanto, nenhuma relação foi observada entre perfil antimicrobiano e grupos agr entre as cepas isoladas em leite de vacas com mastite. Através destes resultados demonstra-se a prevalência do grupo agr II entre as cepas isoladas de alimentos e do grupo agr I em cepas isoladas de leite de vacas mastíticas. Além disso, nas cepas que carreiam o cluster egc houve predominância do grupo agr II, podendo indicar um grupo clonal entre essas. Outro resultado relevante obtido neste estudo foi à elevada taxa de cepas de S. aureus multiresistentes isoladas em alimentos, o que ressalta a importância da disseminação de cepas multiresistentes entre os alimentos.

Quelles sont les particules élémentaires et comment l'univers proviennent sont les principales forces motrices de la physique des hautes énergies. Afin de démontrer le modèle standard et découvrez la nouvelle physique, plusieurs détecteurs sont construits pour les expériences en physique des hautes énergies. Capteurs à pixels CMOS offrent un compromis attirant entre la vitesse de lecture, le budget matériel, la tolérance au rayonnement, la consommation d'énergie et la granularité, par rapport aux capteurs à pixels hybrides et des dispositifs à transfert de charge. Ainsi, les CPS sont un bon choix pour détecter les particules chargées dans les détecteurs de vertex et des télescopes de faisceau. La distribution de puissance devient un enjeu important dans les détecteurs à venir, puisque une quantité considérable de capteurs seront installés. Malheureusement, le «Independent Powering» échoue, comme l'approche traditionnelle. Afin de résoudre les problèmes de distribution de puissance et de fournir des tensions silencieuses, cette thèse se concentre sur la conception de la gestion de l'alimentation à faible bruit, à basse consommation d'énergie, de petite taille et sur-puce pleinement pour les CPS. Les CPS sont d'abord introduits en tirer les exigences de conception de la gestion de l'alimentation. La distribution de puissance dédiées à les CPS est ensuite proposé, dans laquelle la gestion de l'alimentation est utilisée comme seconde étape de conversion de puissance. Deux régulateurs sur-puce pleinement sont proposés pour générer la tension d'alimentation analogique et de la tension d'alimentation de référence requis par l'opération d'échantillonnage double corrélé, respectivement. Deux prototypes ont vérifié ces régulateurs. Ils peuvent répondre aux exigences des CPS. En outre, les techniques de gestion de l'alimentation et de la conception tolérance au rayonnement sont également présentés dans cette thèse. / What are the elementary particles and how did the universe originate are the main driving forces in the high energy physics. In order to further demonstrate the standard model and discover new physics, several detectors are built for the high energy physics experiments. CMOS pixel sensors (CPS) can achieve an attractive tradeoff among many performance parameters, such as readout speed, granularity, material budget, power dissipation, radiation tolerance and integrating readout circuitry on the same substrate, compared with the hybrid pixel sensors and charge coupled devices. Thus, the CPS is a good candidate for tracking the charged particles in vertex detectors and beam telescopes.The power distribution becomes an important issue in the future detectors, since a considerable amount of sensors will be installed. Unfortunately, the independent powering has been proved to fail. In order to solve the power distribution challenges and to provide noiseless voltages, this thesis focuses on the design of a low noise, limited area, low power consumption and full on-chip power management in CPS chips. The CPS are firstly introduced drawing the design requirements of the power management. The power distribution dedicated to CPS chips is then proposed, in which the power management is utilized as the second power conversion stage. Two full on-chip regulators are proposed to generate the analog power supply voltage and the reference voltage required by correlated double sampling operation, respectively. Two prototypes have verified these regulators. They can meet the requirements of CPS. Moreover, the power management techniques and the radiation tolerance design are also presented in this thesis.

This master’s thesis deals with the design of integrated voltage regulator. Topologies of linear voltage regulators and their stability are discussed. Part of the thesis deals with description and simulation of blocks of selected regulator topology. The thesis describes the difficulties of integrated circuit design in the automotive industry. The electrical scheme of the designed regulator is explained. The work also focuses on the stability of designed regulator. Then presents simulations. It discusses the layout of integrated circuits and the designed voltage regulator.

This thesis is focused on simulation of laboratory stand located on University of technology in Brno which is containing DC and asynchronous motor. This thesis includes mathematical model of DC motor, regulator of current, regulator of speed and DC convertor. It also contains model of asynchronous squirrel cage motor and models for scalar and vector control. Whole simulation is calculated in Simulink which is part of program Matlab.

Heterochromatin is a silenced chromatin region essential for maintaining genomic stability in eukaryotes and for driving developmental processes in higher organisms. A hallmark of heterochromatin is the presence of specialized architectural proteins that alter chromatin structure to inhibit transcription and recombination. Although it is generally assumed that heterochromatin is highly condensed, surprisingly little is known about the structure of heterochromatin or its dynamics in solution. In budding yeast, heterochromatin assembly at telomeres and the HM silent mating type loci requires the Sir proteins: Sir3, believed to be the major structural component of SIR heterochromatin, and the Sir2/4 complex, responsible for SIR recruitment to silencing regions and deacetylation of lysine 16 of the histone H4 tail, a mark associated with active chromatin. A combination of sedimentation velocity, atomic force microscopy, and nucleosomal array capture was used to characterize the stoichiometry and conformation of SIR nucleosomal arrays. The results indicate that Sir3 interacts with nucleosomal arrays with a stoichiometry of two Sir3 monomers per nucleosome, and that Sir2/4 may additionally bind at a ratio of one per nucleosome. Despite Sir3’s ability to repress transcription in vivo and homologous recombination in vitro in the absence of Sir2/4, Sir3 fibers were found to be significantly less compact than canonical magnesium-induced 30 nanometer fibers. However, heterochromatin fibers composed of all three Sir proteins did adopt a more condensed, globular structure. These results suggest that heterochromatic silencing is mediated both by the creation of more stable nucleosomes and by the steric exclusion of external factors.

The following work demonstrates that chromatin regulators play far more pronounced roles in dynamic gene expression than they do in steady-state. Histone modifications have been associated with transcription activity. However, previous analyses of gene expression in mutants affecting histone modifications show limited alteration. I systematically dissected the effects of 83 histone mutants and 119 gene deletion mutants on gene induction/repression in response to diamide stress in yeast. Importantly, I observed far more changes in gene induction/repression than changes in steady-state gene expression. The extensive dynamic gene expression profile of histone mutants and gene deletion mutants also allowed me to identify specific interactions between histone modifications and chromatin modifiers. Furthermore, by combining these functional results with genome-wide mapping of several histone modifications in the same time course, I was able to investigate the correspondence between histone modification occurrence and function. One such observation was the role of Set1-dependent H3K4 methylation in the repression of ribosomal protein genes (RPGs) during multiple stresses. I found that proper repression of RPGs in stress required the presence, but not the specific sequence, of an intron, an element which is almost unique to this gene class in Saccharomyces cerevisiae. This repression may be related to Set1’s role in antisense RNA-mediated gene silencing. Finally, I found a potential role for Set1 in producing or maintaining uncapped mRNAs in cells through a mechanism that does not involved nuclear exoribonucleases. Thus, deletion of Set1 in xrn1Δ suppresses the accumulation of uncapped transcripts observed in xrn1Δ. These findings reveal that Set1, along with other chromatin regulators, plays important roles in dynamic gene expression through diverse mechanisms and thus provides a coherent means of responding to environmental cues.

The transition to more environmentally sustainable transports, as well as rising fuel prices create a demand for efficient means of transportation. Liftable axles have shown potential to save fuel and reduces tire wear on heavy vehicles. This thesis proposes a simulation environment and a control method for the electronically controlled air suspension system on a four axle truck that enables axle lifting. The goal of the work is to propose a control method that fulfills certain safety criteria and is robust to disturbances introduced by an external un-modeled controller. A simulation environment is proposed, based upon two different physical models of the suspension system. The first model offers simplicity for the initial tuning of the controller and the second model serves as a platform for more realistic testing of the controller before the final vehicle test. The results from the vehicle tests show that the proposed controller is able to regulate the pressure in the suspension bellows to the desired load distribution between the axles of the vehicle, while the vehicle is maintaining a certain height above ground. The vehicle test showed that it was difficult to read the correct pressure in the suspension bellows when the valves controlling the airflow in and out of the suspension bellow were open. A method for compensating the error when the valves are open is proposed. / Övergången till hållbara och miljövänliga transporter samt stigande bränslepriser skapar en efterfrågan av mer effektiva transportmedel. Lyftbara axlar har visats medföra minskad bränsleförbrukning och däckslitage. Denna uppsats föreslår en simuleringsmiljö samt en metod för reglering av det elektroniskt styrda luftfjädringssystemet på en fyraxlig lastbil som möjliggör lyftning av en axel. Målet med arbetet är att föreslå en metod för reglering av systemet som uppfyller en rad säkerhetskriterier och är robust för störningar introducerade av en extern, icke-modellerad styrenhet. Den föreslagna simuleringsmiljön är baserad på två olika fysiska modeller av fjädringssystemet. Den första modellen karakteriseras av dess enkelhet och används för inledande testning och justering av regulatorn. Den andra modellen används för mer realistisk testning av regulatorn innan det avslutande fordonstestet. Resultatet från fordonstesterna visar att den föreslagna regulatorn kan reglera trycket i luftbälgen till den önskade lastfördelningen mellan axlarna på fordonet medan dess höjd bibehålls. Under fordonstestet konstaterades att det inte gick att avläsa det korrekta trycket i luftbälgen när ventilerna som styr luftflödet till och från luftbälgen var öppna. En metod för att kompensera felet som uppstår när ventilerna är öppna föreslås.

[ES] El contexto de esta Tesis se enmarca en los sistemas de dos componentes (TCS) para comprender el mecanismo de transducción de la señal. Se analizó la especificidad en el reconocimiento de los TCS abarcando estudios a nivel funcional, estructural y evolutivo. Primero se utilizó el sistema HK853-RR468, que al estar previamente caracterizado nos permitió analizar específicamente las regiones de reconocimiento (HK-RR) correspondientes a los Lß3α3 y Lß4α4 de RR468 mutando residuos que determinaran la influencia en la transferencia del grupo fosfato. Los mutantes se caracterizaron de manera bioquímica y se hicieron aproximaciones estructurales pudiendo asignar la reacción de fosfotransferencia a una estructura formada por un complejo entre HK853 y RR468 mutante. Esta estructura nos permitió observar el carácter disociativo de dicha reacción que ha sido descrito previamente y la nula participación del dominio CA. Al mismo tiempo, se analizó la influencia del pH en los residuos catalíticos de la HK y el RR (His y Asp), utilizando un rango de pH de 5 a 8. Los ensayos bioquímicos generados en este rango nos mostraron como la His catalítica perdía su carácter nucleofílico cuando el pH se acercaba y disminuía de 6. Esto se relaciona con el pKa del anillo de imidazol presente en el residuo de His, que se se encuentra en torno a 6 y la pérdida de protonación. También se cristalizó el complejo HK-RR a diferentes pHs donde observamos que la His adquiría un rotámero gauche- que se asignaba a un estado inactivo o de reposo. Por otra parte, se analizó la influencia de la mutación G63V en el RR OmpR, que fue descrita como una mutación relacionada con la resistencia al antibiótico ertapenem. Para esto se generaron mutantes en OmpR en la posición G63, tanto en el dominio REC aislado como en la proteína completa. Los estudios bioquímicos de estas mutaciones demostraron como la mutación en esta posición disminuía la capacidad del RR para fosforilarse e incluso a dimerizar. Esto afectaba a la afinidad de este RR para interaccionar con su ADN correspondiente, las cajas ompF y ompC. Estos efectos se lograron evidenciar con la estructura de OmpRRECG63V, donde se observó como la mutación generaba un cambio conformacional al reducir el tamaño del Lßα3 y generaba un bolsillo hidrofóbico donde quedaba atrapada la cadena lateral de la Val. Finalmente se analizó el aspecto evolutivo de la señalización, para lo que se buscaron organismos endosimbiontes que presentaran una HK y uno o varios RRs. Estas características nos sugerían que la menor presión selectiva nos iba a permitir encontrar organismos con TCSs menos evolucionados cuya especificidad se haya visto reducida. Se analizaron los sistemas de Chlamydia trachomatis, Chlamydia psittaci, Simkania negevensis y Methanobrevibacter sp. Abm4. Solo pudo evidenciarse reacción de fosfotransferencia en el sistema perteneciente a Methanobrevibacter, el cual presenta una HK y 4 RRs. Sin embargo, esta fosfotransferencia presentaba una eficiencia diferenciada, siendo más rápida en RRMet572 y RRMet589-1 mientras que era nula en RRMet589-2. Por su parte las HKs de C. trachomatis y S. negevensis, fueron capaces de fosfotransferir, de manera no selectiva, a RR468, probablemente debido a la alta similitud que presenta la hélice α1 de las HKs con HK853. La aproximación estructural de estos sistemas permitió obtener las estructuras de los RRsMet589-1 y RRMet572, ambos en estado no fosforilado. Las dos estructuras presentaron grandes diferencias conformacionales a partir del Lßα4. Esto sugiere que sus mecanismos de reconocimiento con HKMet y de regulación son diferentes lo que apoya la selectividad diferenciada entre los RRs de este sistema. / [CA] Esta Tesi s'emmarca en l'estudi dels sistemes de dos components (TCS) amb la finalitat d'entendre el seu mecanisme de transducció de senyal basat en l'especificitat de reconeixement a nivell funcional, estructural i evolutiu. Utilitzant el TCS HK853-RR468, analitzarem les regions Lß3α3 y Lß4α4 del regulador de la resposta (RR) RR468, que prèviament s'havien mostrat importants en el reconeixement, generant mutants i determinant la influència en la transferència del grup fosforil. Els mutants foren caracteritzats bioquímicament, observant que afectaven a una reacció específica i permetent-nos captar la reacció de fosfotransferència en una estructura formada per un complex entre HK853 i RR468 mutant. Aquesta estructura va mostrar el caràcter dissociatiu d'aquesta reacció i la nul·la participació del domini CA de la HK. Al mateix tems, s'analitzà l'efecte del pH sobre la transducció del senyal utilitzant els TCS K853-RR468 i EnvZ-OmpR. Els assajos bioquímics generats dins del rang de pH entre 5 i 8 ens mostraren com la His de la HK catalítica perdia el seu caràcter nucleofílic quan el pH s'aproximava i disminuïa de 6, valor del pKa de l'anell d'imidazole de la cadena lateral del residu d'His, indicant que aquesta disminució en l'activitat es correlacionava amb el canvi en la protonació de l'anell. Un exhaustiu estudi estructural del complex HK853-RR468 a diferents pHs mostrà que la His catalítica sempre adquiria un rotàmer gauche- independentment del valor del pH, invalidant el model que proposava que el pH regulava l'activitat de les HKs de la família HisKA induint un canvi en el rotàmer de la His catalítica. D'altra banda, s'analitzà la influència de la mutació G63V en el RR OmpR, que fou descrita com una mutació relacionada amb la resistència a l'antibiòtic ertapenem. Amb aquesta finalitat, es generaren mutants a OmpR a la posició G63 tant al domini REC aïllat com a la proteïna completa. Els estudis bioquímics demostraren com la mutació en aquesta posició disminuïa la capacitat de OmpR per fosforilar-se i per dimeritzar, afectant a la capacitat d'interaccionar amb les seqüències d'ADN palindròmiques diana, corresponents a les caixes ompF i ompC. Aquests efectes es visualitzaren a nivell molecular al resoldre l'estructura del mutant G63V d'OmpRREC, on s'observava com la mutació induïa un canvi conformacional al reduir la mida del Lßα3 generant una butxaca hidrofòbica degut a la presència de la nova Val en posició 63. Aquests canvis es transmeten a la resta de l'estructura d'OmpR produint canvis en Lßα4 i α4 que impedeixen la formació d'una superfície de dimerització competent i impedint la seua interacció amb l'ADN. Finalment, s'analitzà l'aspecte evolutiu de l'especificitat HK-RR. Buscaren organismes endosimbionts que presentaren TCS aïllats consistent en una HK i un o diversos RRs, suggerint que la menor pressió selectiva permetria trobar TCS menys evolucionats, on l'especificitat s'haguera vist reduïda. S'analitzaren HKs i RRs presents en Chlamydia trachomatis, Chlamydia psittaci, Simkania negevensis i Methanobrevibacter sp. Abm4. La reacció de fosfotransferència es va detectar en Methanobrevibacter, que presenta una sola HK i 4 RRs. Aquesta HK mostrà eficiència diferenciada per a la reacció de fosfotransferència, presentant major velocitat per als RRs RRMet572, RRMet589-1 i nul·la per a RRMet589-2. Per la seua banda, les HKs de C. trachomatis i S. negevensis, foren capaces de transferir, de manera no selectiva, a RR468 de Thermotoga maritima, probablement degut a l'alta similitud que presenta l'hèlix α1 de les HKs amb HK853. L'aproximació estructural d'aquests sistemes ens va permetre resoldre les estructures dels RRsMet589-1 i RRMet572 en estat no fosforilat. Les dues estructures presentaren grans diferències conformacionals a partir del Lßα4, els que ens suggereix que els seus mecanismes de reconeixement amb HKMet i de regulació són diferents, cosa que suporta la selectivitat diferenciada entre els RRs d’aquest sistema. / [EN] The context of the Thesis is framed in the two component systems (TCS) to understand the signal transduction mechanism. The specificity in the recognition of TCS was analyzed covering studies at the functional, structural, and evolutionary level. First, the previously characterized HK853-RR468 was used, this allowed us to analyze specific recognition regions corresponding to Lß3α3 and Lß4α4 of RR468 and induce mutations in these regions and understand the recognition between HK and RR and determine the phosphate group transfer's influence. The mutants were characterized biochemically, and structural approximations were prepared, thus assigning the phosphotransfer reaction in a formed structure by an HK8536 and a mutant RR468 complex. This structure allowed us to observe the dissociative character of this reaction that has been previously described and the null participation of the CA domain. Simultaneously, the influence of pH on the catalytic residues of HK and RR (His and Asp) was analyzed, using a pH range of 5 to 8. The biochemical assays generated in this range showed how HK's catalytic His lost the nucleophilic characteristic when pH reached six or below. This is related to the pKa of the imidazole ring present in the His residue that if found around 6 and the loss of protonation. The HK853-RR468 complex was also crystallized at different pHs where we observed that His acquired a gauche- rotamer that was assigned an inactive or resting state. In addition, the influence of mutation G63V in the RR OmpR was analyzed. This mutation was associated with resistance to the antibiotic ertapenem in E. coli. For this, mutants in OmpR were generated in position G63 in both the isolated REC domain and in the whole protein. Biochemical studies of this mutations showed how the mutation in this position reduced the capacity of RR to phosphorylate and even to form a dimer. This affected the affinity of the RR to interact with it's corresponding DNA, the boxes ompF and ompR. These effects were shown with the structure of the REC domain of the OmpR protein mutant G63V. This mutation generated a conformational change by reducing the Lßα3 and generating a hydrophobic pocket that trapped Val's lateral chain. Finally, the evolutive aspect of signaling was analyzed. For this, endosymbiotic organisms that had one HK or many RRs were identified. These characteristics suggested that lower selective pressure would allow us to find organisms with TCSs that showed lower KH-RR specificity. The systems of Chlamydia trachomatis, Chlamydia psittaci, Simkania negevensis, and Methanobrevibacter sp. Abm4 were analyzed. The phosphotransference reaction was only evident in the the Methanobrevigbacter system. This system presents only one KH and four RRs. This HK shows differentiated efficiency in the phosphotranference. It has a higher speed in RRMet572, RRMet589-1 and it is null in RRMet589-2. On the other hand, the HKs of C. trachomatis y S. negevensis were able to transfer in a nonselective manner the RR468 of T. maritima. This is due to the similarity between the α1 helix of the HKs with HK853. The structural approach of there systems allowed us to obtain the structure of RRMet589-1 y RRMet572, both in a non-phosphorylated state. The two structures presented large conformational differences from Lßα4. This suggests that the recognition mechanisms with KHMet and regulation are different. This supports differentiated selectivity between the RRs in this system. / Mideros Mora, C. (2021). Bases moleculares de la especificidad en el mecanismo de transducción de señal en los sistemas de dos componentes bacterianos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/161920

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / For any automated surveillance operation to be successful, it is critical to have sensing resources strategically positioned to observe, interpret, react and maybe even predict events.In many practical scenarios, it is also expected that different zones within a surveillance area may have different probability of event detection (or false alarm) requirements. The operational objective in such surveillance systems is to optimize resources (number of sensors and the associated cost) and their deployment while guaranteeing a certain assured level of detection/false alarm performance. In this dissertation, we study two major challenges related to sensor deployment in distributed sensor networks (DSNs) for detection applications. The first problem we study is the sensor deployment problem in which we ask the following question: Given a finite number of sensors (with a known sensing profile), how can we deploy these sensors such that we best meet the detection and false alarm requirements in a DSN employing a specific information fusion rule? Even though sensor deployment has garnered significant interest in the past, a unified, analytical framework to model and study sensor deployment is lacking. Additionally, the algorithms proposed in literature are typically heuristic in nature and are limited to (1) simplistic DSN fusion architectures, and (2) DSNs with uniform detection/false alarm requirements. In this dissertation, we propose a novel treatment of the sensor deployment problem using concepts from optimal control theory. Specifically, the deployment problem is formulated as a linear quadratic regulator (LQR) problem which provides a rigorous and analytical framework to study the deployment problem. We develop new sensor deployment algorithms that are applicable to a wide range of DSN architectures employing different fusion rules such as (1) logical OR fusion; (2) value fusion; (3) majority decision fusion, and (4) optimal decision fusion. In all these cases, we demonstrate that our proposed control theoretic deployment approach is able to significantly outperform previously proposed algorithms. The second problem considered in this dissertation is the “self healing” problem in which we ask the following question: After the failure of a number of sensors, how can one reconfigure the DSN such that the performance degradation due to sensor loss is minimized? Prior efforts in tackling the self healing problem typically rely on assumptions that don’t accurately capture the behavior of practical sensors/networks and focus on minimizing performance degradation at a local area of the network instead of considering overall performance of the DSN. In this work, we propose two self healing strategies the first approach relies on adjusting decision thresholds at the fusion center. The second approach involves sensor redeployment based on our control theoretic deployment framework. Simulation results illustrate that the proposed algorithms are effective in alleviating the performance degradation due to sensor loss.

Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / ENGLISH ABSTRACT: This thesis discusses the development of a 5 kVA single phase AC voltage regulator, specifically designed to assist in the reduction of electrification costs in sparsely populated rural areas. The voltage regulator is based on a solid state auto-transformer tap changer, designed to be robust and maintenance free. Electrification cost savings can be realized if the length of the LV network can be extended to reach more households. To accomplish this, a voltage regulator can be installed onto the extended LV feeder at the point where the LV voltage will drop below the minimum valid voltage, thereby boosting the voltage downstream and enabling more customers to be connected. A variety of voltage regulator topologies were investigated to obtain the best topology for the application. The voltage regulator design is discussed in detail with careful attention given to the power loss incurred, surge voltage protection requirements, protection coordination with the existing LV network and the thermal design requirements. An electronic controller based on a digital signal processor together with an appropriate power supply is designed and built. The software to control the voltage regulator is developed, integrated with the hardware and debugged. The complete voltage regulator is evaluated through extensive laboratory testing and field trials are performed to verify the performance of the device. / AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die ontwikkeling van ‘n 5 kVA, enkelfase, wisselstroom spannings reguleerder, spesifiek ontwerp om koste besparings te bewerkstellig in die elektrifisiëring van yl bevolkte landelike gemeenskappe. Die spannings reguleerder se ontwerp is gebaseer op ‘n outo-transformator tap wisselaar met vaste toestand skakelaars, om sodoende robuust en instandhoudings vry te funksioneer. Elektrifisiërings koste besparings is moontlik indien die laag spannings distribusie kabel verleng kan word, om sodoende elektrisiteit aan meer huishoudings te voorsien. Om dit mootlik te maak kan ‘n spannings reguleerder geinstalleer word op die punt waar die kabel spanning onder die minimum toegelate spanning daal. Sodoende word die spanning weer verhoog aan al die huishoudings wat aan die verlengde gedeelte van die kabel verbind is. ‘n Verskeidenheid uiteenlopende spannings reguleerder topologieë is ondersoek om die beste topologie vir die toepassing te identifiseer. Die ontwerp van die spannings reguleerder is baie deeglik bespreek en spesifieke aandag is gegee aan die verliese, spits opwelling spannings beveiliging, sinkronisasie met die huidige laag spannings netwerk se beveiligings meganismes en die termiese ontwerp van die stelsel. ‘n Elektroniese beheerder, gebaseer op ‘n digitale sein verwerker, tesame met ‘n toepaslike kragbron is ontwerp en gebou. Die nodige sagteware om die spannings reguleerder te beheer is ontwikkel, geintegreer met die hardeware en ontfout. Die volledige spannings reguleerder is ontleed deur intensiewe toetse in die laboratorium en toets installasies op laag spannings netwerke, om sodoende die nakoming van die werks verrigting vereistes van die toestel te bevestig.