Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Includes bibliographical references. / by Thomas F. Quatieri, Jr. / Sc.D.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 53-54. / by Bruce Edward Bates. / B.S.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Includes bibliographical references. / M.S.

This PhD thesis proposes a bottom-up approach that accurately addresses the operational flexibility embedded in each part of a multi-energy system (MES). Several models which cover the simulations from replicating domestic electrified demands to power system scheduling are proposed. More specifically, a domes-tic multi-energy consumption model is firstly developed to simulate one minute resolution energy profiles of individual dwellings with the installation of prospec-tive technologies (i.e., electric heat pumps (EHPs), electric vehicles (EVs)). After-wards, a fast linear programming (LP) unit commitment (UC) model is devel-oped with the consideration of characteristics of generators and a full set of ancil-lary services (i.e., frequency response and reserves). More importantly, the fre-quency response requirements in low inertia systems are assessed with the con-sideration of three grid frequency regulations (i.e., rate of change of frequency, Nadir and quasi-steady state). Furthermore, the UC model has integrated vari-ous flexibility contributors in MES to provide ancillary and flexibility services, which include pumped hydro storages (PHSs), interconnectors, batteries and demand side resources (i.e., individual EHPs, heat networks, electrolysers). More importantly, the fast frequency response (FFR) provision from nonsynchronous resources is implemented and the demand response application of electrolysers is taken as an example to provide FFR in the UC model. By using the integrated UC model with the consideration of flexibility services provided by resources in the MES, the advantages of multi-energy operation can be clearly identified which can be used to inform system operators and policy makers to design and operate energy systems in a more economic and environment-friendly way.

Neste trabalho são apresentados diversos métodos de localização de vazamentos, desde as técnicas e equipamentos mais elementares, como a inspeção visual e o geofone mecânico, até o uso dos sofisticados armazenadores de ruídos e de modelação computacional. Algumas dessas técnicas são amplamente difundidas e largamente utilizadas pelas empresas de saneamento, outras porém, constituem-se em ótimas promessas para o aperfeiçoamento do controle das perdas físicas nos sistemas de abastecimento. É dada ênfase na utilização do diagrama de resposta em freqüência para localizar e quantificar vazamentos, com especial aplicação às adutoras de água tratada. A técnica de utilização da resposta em freqüência desenvolvida por Lee et al. (2005) é esmiuçada, inclusive acerca do impacto que um vazamento impõe ao diagrama de resposta em freqüência. São abordadas as formas de obtenção do referido diagrama, tanto do ponto de vista do modelo matemático e computacional, quanto dos ensaios de campo necessários. / This work presents some methods for leak location, from de most elementary techniques and equipments, as visual inspection and mechanical geophone, until using sophisticated noise data-logger and computational modeling. Some of these techniques are very well issued and largely used by water companies, but others play excellent promises for the improvement of leak control in systems of water supply. The pattern of the frequency response diagram is used for leak location and quantification, with special application in drinking water pipelines. The frequency response technique developed by Lee et al. (2005) is studied in details, including the impact produced by the leak on the frequency response diagram. The ways to obtain the frequency response diagram, by using mathematical and computational models or necessary field data survey, are also discussed.

No novo contexto do setor elétrico brasileiro, as concessionárias passam a ter uma nova postura quanto à gestão. A energia elétrica, como produto, como negócio, deve levar lucro às empresas concessionárias. Começam a dar mais importância aos custos, entendendo que vários aspectos técnicos devem ser analisados, visando reduzir perdas substanciais. Assim sendo, o transformador de potência assume uma posição destacada, considerando sua posição estratégica no sistema elétrico, fundamental no processo de transporte e entrega de energia elétrica. Por este motivo vem despertando o interesse no desenvolvimento de estudos e pesquisas no sentido de aumentar sua vida útil. O método de Análise da Resposta em Frequência da impedância do transformador permite obter a “assinatura” do mesmo, a fim de verificar futuras degradações. Este método é adotado por várias empresas em todo o mundo, há mais de três décadas. Embora sua ampla aplicação entre muitas técnicas utilizadas na monitoração e análise de falhas em equipamentos, até agora não houve consenso na interpretação dos resultados obtidos por este método. A dificuldade de correlacionar parâmetros com prováveis falhas tem suscitado pesquisas para obtenção de resultados confiáveis e de interpretação fácil. Este trabalho objetiva determinar um modelo elétrico que represente a característica da resposta em frequência para fins de armazenamento de dados e simulações. A partir de dados reais do teste de resposta em frequência da impedância inseridos no modelo proposto, através de um programa computacional, foi verificada a confiabilidade nas respostas obtidas, comparadas com as reais. Os resultados obtidos asseguram que o modelo proposto é viável de ser aplicado. / In the new context of the Brazilian electric industry, the electric power provider companies have adopted a new administration posture. The electric power, as a product and business, should make the companies profitable. They have been paying more attention to the costs, .learning that many technical aspects should be analyzed in order to reduce substantial losses. Therefore, the power transformer takes an outstanding position, considering its strategic position in the electric system and being essential in the process of transport and delivery of the electric power. For this reason, there has been an interest in the development of studies and research in order to increase its useful life. The method of Frequency Response Analysis of impedance of the power transformer permits to obtain reference parameters of this one, in order to verify future degradations. This method has been adopted by many companies throughout the world for over three decades. Despite its wide application among several techniques used in the supervision and analysis of faults of equipments, there has been no consensus in the interpretation of the results obtained by this method so far. The difficulty of correlating the parameters with probable faults have increased research in order to obtain reliable results and of easy interpretation. This study aims to determine an electric model that represents the characteristic of the frequency response in order to store data and simulations. Starting from the real data of the FRA test inserted in the proposed model through a computer program, the reliability of the obtained responses were verified and compared with the real data. The obtained results assure that the proposed model is viable and can be applied.

Hot-wire anemometry has been routinely employed for laboratory measurements of turbulence for decades. This thesis presents a hot-wire anemometer suitable for use with the Boundary Layer Data System (BLDS). BLDS provides a unique platform for in- flight measurements because of its small, self-contained, robust design and flexible architecture. Addition of a hot-wire anemometer would provide BLDS with a sensor that could directly measure flow velocity fluctuations caused by turbulence. Hot-wires are commonly operated in constant-temperature mode for high frequency response, but require a carefully tuned bridge. The constant-voltage anemometer (CVA) uses a simple op-amp circuit to improve frequency response over constant-current operation. Due to its balance between ease of operation and performance, a CVA system built for this project was tested with a 3.8 micron diameter, platinum-coated tungsten probe. The CVA was calibrated in a steady jet and a power-law curve fit accurately represented the calibration data. The CVA successfully measured velocity fluctuations in a turbulent jet, as well as in laminar and tripped turbulent boundary layers over a flat plate in a 110 MPH wind tunnel. CVA frequency response was investigated using a thermal/electrical model, controlled oscillation in a steady flow, and with a square wave test; these three methods showed agreement. The CVA is selected for integration with BLDS.

Frequency selectivity is one of the most important functions of the mammalian hearing organ – the cochlea. The interaction of fluid mass and organ of Corti compliance sets a traveling wave along the basilar membrane (BM), which is longitudinally tuned to different frequencies. Beyond this passive tuning process, cochlear amplification locally enhances the vibration of the best frequency peak by factors of hundreds to boost the frequency selectivity and sensitivity of the cochlea. This amplification is achieved by a positive feedback loop between BM motion and outer hair cell (OHC) electrical-mechanical response. However, this active mechanism is vulnerable to damage and cannot be fully recovered in vivo. As the instruments of cochlear amplification, the frequency response of BM and OHCs are of great importance to understand cochlear tuning process. This thesis used animal models, aimed to understand cochlear tuning and investigate possibilities to manipulate the cochlear amplifier, by testing the cochlear amplifier’s sensitivity to operating conditions. The first project tested whether the cochlear amplification can adjust to a lower endocochlear potential (EP), which controls OHC electromechanical force by providing part of the voltage source to drive OHC transduction current. To investigate this possibility, we use intraperitoneal (IP) and intravenous (IV) injection of furosemide to reversibly reduce EP, while monitoring the EP and cochlear amplification simultaneously. Cochlear amplification was monitored by measuring the local cochlear microphonic (LCM) and distortion product emission (DPOAE). With IV injection, the cochlear amplification observed in LCM could attain nearly full or even full recovery with reduced EP. This showed the cochlea has an ability to adjust to diminished operating condition. Furthermore, the cochlear amplifier and EP recovered with different time courses: cochlear amplification just started to recover after the EP was nearly fully recovered and stabilized. Using a Boltzmann model and the 2nd harmonic of the LCM to estimate the mechanoelectric transducer channel operating point, we found that the recovery of cochlear amplification occurred with re-centering of the operating point. The second project studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid, for better understanding cochlear fluid mechanics. Perilymphatic perfusion was applied with artificial perilymph and viscous sodium hyaluronate (Healon, HA) in four different concentrations. Using compound action potential (CAP) thresholds as an indicator of cochlear condition, our results and analysis indicated that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Histology of the cochleae perfused with higher shear stress showed the Reissner's membrane was torn. These data also indicated that the cochlea mechanics remains normal within increased perilymphatic fluid viscosity up to an increase of a factor of 50. Beside these findings, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the organ of Corti. The last project was to test the effect of OHC intracellular Cl- concentration on cochlear amplification. Chloride is known to enable the electromotility of the OHC by binding its motor protein, prestin. By locally perfusing high chloride perilymph and the chloride ionophore tributyltin, this study investigated whether increasing intracellular chloride concentration can restore cochlear sensitivity in a cochlea that was slightly damaged. This had been shown by others in guinea pig. However, we did not observe recovery in several attempts in gerbil.

This thesis is aimed at analysis of sampled-data feedback systems. Our approach is in the frequency-domain, and stresses the study of sensitivity and complementary sensitivity operators. Frequency-domain methods have proven very successful in the analysis and design of linear time-invariant control systems, for which the importance and utility of sensitivity operators is well-recognized. The extension of these methods to sampled-data systems, however, is not straightforward, since they are inherently time-varying due to the intrinsic sample and hold operations. In this thesis we present a systematic frequency-domain framework to describe sampled-data systems considering full-time information. Using this framework, we develop a theory of design limitations for sampled-data systems. This theory allows us to quantify the essential constraints in design imposed by inherent open-loop characteristics of the analog plant. Our results show that: (i) sampled-data systems inherit the difficulty imposed upon analog feedback design by the plant's non-minimum phase zeros, unstable poles, and time-delays, independently of the type of hold used; (ii) sampled-data systems are subject to additional design limitations imposed by potential non-minimum phase zeros of the hold device; and (iii) sampled-data systems, unlike analog systems, are subject to limits upon the ability of high compensator gain to achieve disturbance rejection. As an application, we quantitatively analyze the sensitivity and robustness characteristics of digital control schemes that rely on the use of generalized sampled-data hold functions, whose frequency-response properties we describe in detail. In addition, we derive closed-form expressions to compute the L2-induced norms of the sampled-data sensitivity and complementary sensitivity operators. These expressions are important both in analysis and design, particularly when uncertainty in the model of the plant is considered. Our methods provide some interesting interpretations in terms of signal spaces, and admit straightforward implementation in a numerically reliable fashion. / PhD Doctorate

Thomas F. Quatieri, Jr. / Originally published as thesis (Dept. of Electrical Engineering and Computer Science, Sc.D., 1979). / Bibliography: p. 133-135. / Supported in part by the Advanced Research Projects Agency (monitored by ONR) under Contract N00014-75-C-0951 NR 409-328