Дисертації з теми "Vibrational Monitoring"
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Coronado, Higuero Marcelo. "Biodiesel quality monitoring using vibrational spectroscopy." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13799.
Повний текст джерелаDepartment of Biological and Agricultural Engineering
Wenqiao Yuan
Biodiesel production and utilization has been increasing rapidly worldwide in recent years. A main challenge in the commercialization and public acceptance of biodiesel is its quality control. This work reports the use of infrared spectroscopy to monitor biodiesel quality through the development of models to predict (1) the blending level of biodiesel in biodiesel-diesel mixtures, (2) the fatty acid profile of biodiesel fuels derived from various lipids, and (3) the concentration of most common impurities present in biodiesel including water, glycerol, methanol and triglycerides. Regressions based on near-infrared (NIR) spectroscopy were developed for relatively inexpensive and rapid on-line measurement of the concentration and specific gravity of biodiesel-diesel blends. Methyl esters of five different oils—soybean oil, canola oil, palm oil, waste cooking oil, and coconut oil—and two different brands of commercial-grade No. 2 on-highway diesel and one brand of off-road No. 2 diesel were used in the calibration and validation processes. The predicted concentration and specific gravity of the biodiesel-diesel blends were compared with the actual values. The maximum and average root-mean-square errors of prediction (RMSEP) of biodiesel concentration were 5.2% and 2.9%, respectively, from the biodiesel type-specific regression. For the general regression, the RMSEP were 3.2% and 0.002 for biodiesel concentration and specific gravity predictions, respectively. Five different models were developed to determine the concentration of methyl palmitate (C16:0), methyl stearate (C18:0), methyl oleate (C18:1), methyl linoleate (C18:2), and methyl linolenate (18:3) present in biodiesel. Using the NIR range a set of models based on four different types of biodiesel was developed. The maximum RMSEP was 0.553% when the models were validated with biodiesel samples that were used in the calibration, however, prediction accuracy of the model under external samples was poor, therefore, a new set of models was proposed. For this case, six different types of biodiesel were used. The models developed for C18:1, C18:2 and C18:3 presented good accuracy on prediction. However, for C16:0 and C18:0, additional work was necessary to reach reasonable accuracy in prediction. Three sub models for specific ranges of concentration (low, medium, and high) were developed. The RMSEP was reduced from 2.98% to 1.51% for the C16:0 and from 2.33% to 0.56% for C18:0, when the sub-models were validated under internal and external samples. Similar procedures were followed to develop regression models based on mid infrared (MIR) spectra. The RMSEP for C16:0, C18:0, C18:1, C18:2, and C18:3 were 0.83%, 0.37%, 1.45%, 1.59%, and 0.84%, respectively. Predictions using MIR spectroscopy models were better than those obtained with NIR spectroscopy models for the C16:0 and C18:0 models. The most common impurities present in biodiesel from production processes, including methanol, free glycerol, triglycerides, and water, were determined by infrared methods using NIR and MIR spectra and partial least square regression (PLSR) methods. The models were developed in two different approaches, one was when a single impurity was present and the other was when all impurities were present. In the single impurity models, the maximum RMSEP obtained in the NIR and MIR models were 647 mg kg[superscript]-1 and 206 mg kg[superscript]-1, respectively. The models for methanol, glycerol, and water performed better using the NIR data. For the triglycerides model, MIR worked better. Only NIR data were used to develop the models for samples with all impurities. Data pre-treatment (Savitzky-Golay second derivative) was necessary to achieve reasonable accuracy in the predictions in this type of models. The maximum RMSEP was 932 mg kg[superscript]-1 presented in the model for triglycerides. The best performance was obtained in the model developed to predict methanol concentration in biodiesel with RMSEP of 177 mg kg[superscript]-1 when all listed impurities were presented. The feasibility of using NIR and MIR spectroscopy to monitor biodiesel quality was demonstrated in this work. The developed method was accurate, rapid, convenient, yet inexpensive to determine some important characteristics of biodiesel, such as biodiesel blending level in biodiesel-diesel mixtures, the fatty acid profile of biodiesel, and impurities present in the fuel.
Wells, Ian. "Flow injection, vibrational spectroscopy and multivariate calibration techniques for on-line process monitoring." Thesis, University of Plymouth, 1996. http://hdl.handle.net/10026.1/1877.
Повний текст джерелаRibeiro, Marcos Pellegrini. "Inaccessible equipment monitoring via vibratory signature analysis utilising data collected by remote accelerometers." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313689.
Повний текст джерелаGuo, Changning Nafie Laurence A. Freedman Teresa B. "Enantiomeric excess determination and reaction monitoring of chiral molecules using near-infrared and mid-infrared vibrational circular dichroism." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.
Повний текст джерелаVALENTE, VANESSA SOUZA BREDER. "PHYSICOCHEMICAL CHARACTERIZATION OF COMMERCIAL BIODIESEL/DIESEL BLENDS AND POTENTIALITY EVALUATION OF UNCONVENTIONAL SPECTROSCOPIC VIBRATIONAL TECHNIQUES IN MONITORING THEIR OXIDATION AND HYDROLYSIS DURING STORAGE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29804@1.
Повний текст джерелаCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Uma série de ensaios físico-químicos realizados em misturas comerciais Bx (0 por cento, 7 por cento, 20 por cento, e 100 por cento de biodiesel soja/sebo) em óleo diesel S10 e S500, bem como o desempenho de duas técnicas rápidas e ainda pouco exploradas, denominadas, espectroscopia FTIR-HATR e Raman, foram utilizadas para avaliar a estabilidade oxidativa e a hidrólise destas misturas. A adição de biodiesel ao diesel afeta negativamente a resistência ao envelhecimento das misturas resultantes. Misturas S500 são mais ácidas do que misturas S10, em concordância com o teor de água mais elevado da primeira. Testes de estabilidade oxidativa acelerada por Rancimat mostraram que os tempos de indução das amostras de B7 e B20 são maiores do que os de B100, independente do teor de enxofre do diesel. O uso prático de FTIR-HATR para caracterizar o estágio de degradação das misturas é condicionado pelo fato de existirem duas contribuições químicas para cada uma das bandas estudadas. Por outro lado, a espectroscopia Raman representa uma técnica espectroscópica muito adequada para detectar presença de insaturações das cadeias de ácidos graxos do biodiesel. Uma vez que as espectroscopias FTIR-HATR e Raman não necessitam de preparação de amostras, são técnicas rápidas e de baixo custo, e causam baixo impacto ao meio ambiente, mais atenção pode ser dada a elas.
A series of physicochemical studies performed on Brazilian commercial Bx (0 per cent, 7 per cent, 20 per cent, and 100 per cent soybean/tallow biodiesel) mixtures in S10 and S500 oil diesel, as well as the performance of two rapid and still underexplored techniques, namely, FTIR-HATR and Raman spectroscopies, to evaluate the hydrolysis and oxidative stability of these blends are reported. The addition of biodiesel to diesel affects negatively the aging resistance of the resulting blends. S500 blends are more acidic then S10 blends, in accordance with the higher water content of the former. Rancimat accelerated oxidative stability tests showed that the induction times of B7 and B20 samples are greater than that of B100, independent of the sulfur content of the diesel. The practical use of FTIR-HATR to characterize the mixtures degradation stage is conditioned by the fact that there are two chemical contributions for each of the studied bands. On the other hand, Raman spectroscopy represents a very suitable spectroscopic technique to detect the presence of unsaturations in the fatty acids chains of biodiesel. Since FTIR-HATR and Raman spectroscopies do not require sample preparation, are fast and quite low cost techniques, and cause low impact to the environment, further attention may be paid to them.
Elbagerma, Mohamed A. "Analytical method development for structural studies of pharmaceutical and related materials in solution and solid state : an investigation of the solid forms and mechanisms of formation of cocrystal systems using vibrational spectroscopic and X-ray diffraction techniques." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4467.
Повний текст джерелаScherer, Markus Josef. "VIBRATION HEALTH MONITORING OF GEARS." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/820.
Повний текст джерелаBarbini, Leonardo. "Techniques for condition monitoring using cyclo-non-stationary signals." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761025.
Повний текст джерелаThörnevall, Per. "Analys av driftparametrars inverkan på maskinlivslängd : En studie utförd på pappersmaskin 2 vid BillerudKorsnäs AB i Karlsborg." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62104.
Повний текст джерелаÖkad konkurrens inom den kapitalintensiva pappersindustrin gör att en optimerad drift blir en viktig del i företagens strategier för att minska dem totala kostnaderna. Att köra maskinerna på ett driftsäkert sätt bidrar till högre anläggningstillgänglighet, vilket är särskilt viktigt vid industrier där produktionstakten är hög och ett avbrott leder till kostsamma produktionsbortfall. För att uppnå hög anläggningstillgänglighet krävs också ett effektivt underhåll av tillverkningsutrustningen. Detta kräver att rätt åtgärder sätts in i rätt tid. Syftet med detta examensarbete var att öka förståelsen för hur olika driftparametrar för en pappersmaskin påverkar tillståndet för maskinen. Tillståndet bedömdes genom att studera vibrationsnivåer från ett lagerövervakningssystem installerat på virapartiets valsar. Målet var att hitta redskap som kan hjälpa operatörerna att köra pappersmaskinen på ett så skonsamt och kostnadseffektivt sätt som möjligt. Studien genomfördes genom att variera tre driftparametrar: virahastighet, viraspänning och undertryck i virapartiets suglådor. Virahastighet och viraspänning varierades för både planviran och överviran. Undertryck i virapartiets suglådor varierades endast för planviran. Varje parameter varierades separat och parametrarnas påverkan på valsarnas vibrationsnivåer analyserades. Intervallet för de olika driftparametrarna bestämdes i samråd med driftspersonalen. Sett för hela maskinen gick det inte att se några tydliga trender för hur driftparametrarna påverkade tillståndet för maskinen. Däremot kunde man se förändringar i vibrationsnivå för enstaka valsar. För planviran var ändringarna i vibrationsnivåerna marginella undantaget en specifik vals där vibrationsnivån sjönk drastiskt vid ökad hastighet, ökat vacuum samt ökad spänning. Även för överviran var ändringarna i vibrationsnivåer marginella utom för en specifik vals, där ökad spänning gav minskad vibrationsnivå, -från 2,74mm/s till 1,56 mm/s vilket är en betydande skillnad då larmgränsen från maskintillverkaren är 2,5mm/s. Detta är en viktig upptäckt eftersom valsarna kan ses som vitala komponenter i ett seriekopplat system och deras funktion är nödvändig för att pappersmaskinen skall kunna utföra krävd funktion. En slutsats är att det med ganska små justeringar i driftparametrar går att påverka vibrationsnivåerna, som i sin tur påverkar komponenternas livslängd och systemets tillgänglighet.
Engelbrecht, André. "Structural integrity monitoring using vibration measurements." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-07032006-122342/.
Повний текст джерелаAbboud, Dany. "Vibration-based condition monitoring of rotating machines in nonstationary regime." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0106/document.
Повний текст джерелаIn the last decades, vibration-based condition monitoring of rotating machine has gained special interest providing an efficient aid for maintenance in the industry. Nowadays, many efficient techniques are well-established, rooted on powerful tools offered in particular by the theory of cyclostationary processes. However, all these techniques rely on the assump-tion of constant— or possibly fluctuating but stationary— operating regime (i.e. speed and/or load). Unfortunately, most monitored machines used in the industry operate under nonstationary regimes in order to fulfill the task for which they have been designed. In this case, these techniques fail in analyzing the produced vibration signals. This issue, therefore, has occupied the scientific committee in the last decade and some sophisticated signal processing techniques have been conceived to deal with regime variability. But these works remain limited, dispersed and generally not supported by theoretical frameworks. The principal goal of this thesis is to partially fill in this gap on the basis of a theoretical formalization of the subject and a systematic development of new dedicated signal processing tools. In this work, the nonstationarity of the regime is confined to that of the speed— i.e. variable speed and constant load, assumed to be known a priori. In order to reach this goal, the adopted methodology consists in extending the cyclostationary framework together with its dedicated tools. We have elaborated this strategy by distinguishing two types of signatures. The first type includes deterministic waveforms known as first-order cyclostationary. The proposed solution consists in generalizing the first-order cyclostationary class to the more general first-order cyclo-non-stationary class which enfolds speed-varying deterministic signals. The second type includes random periodically-correlated waveforms known as second-order cyclostationary. Three different but complementary visions have been proposed to deal with the changes induced by the nonstationarity of the operating speed. The first one adopts an angle\time cyclostationary approach, the second one adopts an envelope-based solution and the third one adopts a (second-order) cyclo-non-stationary approach. Many tools have been conceived whose performances have been successfully tested on simulated and real vibration signals
Macintyre, John. "Condition monitoring and neural networks." Thesis, University of Sunderland, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297129.
Повний текст джерелаAshwear, Nasseradeen. "Vibration-based Assessment of Tensegrity Structures." Doctoral thesis, KTH, Strukturmekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185789.
Повний текст джерелаQC 20160429
Esu, Ozak O. "Vibration-based condition monitoring of wind turbine blades." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21679.
Повний текст джерелаAl-Arbi, Salem. "Condition monitoring of gear systems using vibration analysis." Thesis, University of Huddersfield, 2012. http://eprints.hud.ac.uk/id/eprint/17821/.
Повний текст джерелаGuan, Hong. "Vibration-based structural health monitoring of highway bridges." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3211821.
Повний текст джерелаAndrieux, Patrick. "Methods and practice of blast-induced vibration monitoring." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23860.
Повний текст джерелаIt is the purpose of this thesis to address these questions in some detail, in an attempt to provide the reader with an understanding of how all the components involved in blast-induced vibration monitoring interact, and on how the choices made at each step can significantly affect overall results. (Abstract shortened by UMI.)
CAMERINI, MURILO GIRON. "FLEXIBLE RISERS MONITORING TECHNIQUE BASED ON VIBRATION MEASUREMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=20697@1.
Повний текст джерелаUm dos principais mecanismos de falha em risers flexíveis é o rompimento de arames da armadura de tração. A experiência tem mostrado que esta classe de dano tende a surgir primariamente na parte emersa do riser, próximo à sua terminação. A ruptura dos arames ocorre de forma progressiva, podendo ser causada por diferentes processos, tais como corrosão pelo ingresso de fluido no espaço anular entre capa e armadura, desgaste excessivo associado com o contato e atrito entre arames adjacentes ou entre as diferentes camadas metálicas da armadura, ou mesmo a presença de níveis elevados de tensões produzidas pelos carregamentos mecânicos aos quais o riser é submetido durante a operação. O deterioramento progressivo pode dar origem a defeitos localizados que agem como concentradores de tensão e levam o arame à ruptura através de um processo de fadiga. O duto flexível é capaz de manter-se em operação mesmo com alguns dos arames de suas armaduras rompidos, porém uma sequencia de rupturas pode levar à ocorrência de vazamentos ou mesmo a falhas catastróficas. O monitoramento contínuo em tempo real é uma das principais alternativas para evitar que o dano progressivo nas armaduras do riser resulte em acidentes com severas consequências econômicas e ambientais. As técnicas de monitoramento da integridade de risers flexíveis podem ser classificadas como diretas, onde é possível identificar diretamente a existência de um dano/falha, ou indiretas, em que o sistema de sensoriamento registra indicações secundárias, possivelmente consequência da falha. Esta dissertação relata o desenvolvimento de um sistema de monitoramento baseado em vibrações. Trata-se de uma técnica indireta baseada em eventos, onde no momento da ruptura do arame um sinal de vibração, distinto tanto na frequência quanto na amplitude, é detectado por acelerômetros instalados na capa polimérica externa do riser. No trabalho, são apresentados resultados de quatro ensaios em escala real que demonstraram a viabilidade do sistema para um primeiro teste de campo. Estratégias de instrumentação dos dutos e as variações dos sinais detectados são apresentadas e discutidas. Os resultados mostraram que a resposta vibratória do sinal de ruptura apresenta características específicas, garantindo uma boa confiabilidade na detecção. Porém, em se tratando de uma técnica indireta, verifica-se que quando dois sistemas de monitoramento de naturezas complementares são empregados em conjunto, as probabilidades de detecção dos eventos de rupturas aumentam significativamente.
The main failure in flexible risers is the disruption of the wires from the tensile armor layer. Experience has shown that this class of damage occurs primarily near to the top riser connector. The breaking of the wires occurs gradually and may be caused by different processes as corrosion by inflow of fluid in the annular space, excessive wear associated with the contact and friction between adjacent wires or between different riser layers. The progressive deterioration can lead to localized defects that act as stress concentrators and may break the wire from the tensile armor layer through a fatigue process. The flexible pipe is able to remain in operation even with some broken wires, but a sequence of ruptures can conduce to a catastrophic failure. Real time continuous monitoring is one of the main alternatives to prevent progressive wire damage results in an accident with severe economic and environmental consequences. This thesis describes the development of a monitoring system based on vibrations. This is an indirect technique based on events, where in the moment of the wire break, one vibration signal is registered. This signal can be distinguished both in frequency and amplitude and detected by accelerometers installed on the polymeric outer layer of the riser. We present results of four tests in real scale that demonstrated the viability of the system for an initial field test. Instrumentation strategies in riser and the variations of the signals detected are presented and discussed. The results showed that the vibrational signal has specific characteristics ensuring good detection reliability.
Kim, Jeung Tae. "Source and path recovery from vibration response monitoring." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14806.
Повний текст джерелаYang, Chen. "Vibration-based structural health monitoring of composite laminates." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/vibrationbased-structural-health-monitoring-of-composite-laminates(b762020d-f2c6-49ed-84ba-dfc2e3ece187).html.
Повний текст джерелаHubert, Elisa. "Vibration monitoring of an aeronautic power transmission system." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSES015.
Повний текст джерелаThis thesis contains the results of the research studies performed with SafranTech and the Laboratoire d’Analyse des Signaux et des Processus Industriels (LASPI) of the University of Lyon. The main subject focuses on vibratory surveillance of aeronautic power transmission systems and more specifically gearboxes.Usually, vibrations are investigated with spectral analysis by means of the common representation of the Fourier spectrum. Based on these observations, gearbox vibrations have been represented by an empirical product model: on one hand the meshing signal, with high frequency, and on the other hand the gears rotations signals, with low frequencies.Indeed, gearbox vibrations develop a line spectrum having similar characteristics with some communication signals, as a carrier signal modulated in amplitude. For the purpose of incipient fault detection, it is interesting to be able to separate low frequency signals as they usually convey more fault information. Based on these model and observation, this research work investigate the answer to the two following questions:1. To which point the vibration signals produced by gears rotation can be explained by the representation as a product?2. Given a signal, is it possible to rebuild it by estimating the two components? Is the solution unique?In order to answer those questions, the given model was formulated as an optimization problem. Then a new tool has been defined to represent the discrete spectrum of gearbox vibration signal as a matrix containing the Fourier coefficients. This work has proven equivalence between the two representations of the matrix product of two vectors and the temporal multiplication of two signals. Furthermore, it allowed us to link the remote fields of signal demodulation and low rank approximation.This new separation and estimation approach for gearbox vibration signals has shown theoretical interesting performances, close to the ideal and allowed us to perform efficient incipient fault detection on real gearbox vibration dataset
Al-Tamimi, Adnan N. J. "Damage location in structures by monitoring vibration characteristics." Thesis, Aston University, 1985. http://publications.aston.ac.uk/11848/.
Повний текст джерелаUllah, Israr. "Vibration-based structural health monitoring of composite structures." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/vibrationbased-structural-health-monitoring-of-composite-structures(f21abb03-5b46-4640-9447-0552d5e0c7d6).html.
Повний текст джерелаEggers, Berndt Leonard. "Draglines gear monitoring under fluctuating conditions /." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-08272008-134253/.
Повний текст джерелаRiley, Caryn M. "Current-based sensorless vibration monitoring of small ac machines." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13741.
Повний текст джерелаRonval, Gilles P. L. "Automatic modal analysis and taxonomy for vibration signature recognition." Thesis, University of Huddersfield, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305084.
Повний текст джерелаVarney, Philip A. "Transverse fatigue crack diagnosis in a rotordynamic system using vibration monitoring." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47655.
Повний текст джерелаLin, Shui-Town. "Gear condition monitoring by wavelet transform of vibration signals." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318680.
Повний текст джерелаZachar, Ryan David. "Naval applications of enhanced temperature, vibration and power monitoring." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100058.
Повний текст джерелаThesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 131-133).
Navy ships require reliable information regarding their power and mechanical systems in order to perform their mission effectively. While today's shipboard systems are quite sophisticated, there are areas for improvement in monitoring individual loads, managing the loads to fit the ships mission, and continuously monitoring mechanical equipment. This thesis presents a method to continuously assess the condition of a rotating machinery system using vibration analysis during the machine's spin-down. A method to determine the thermal storage capacity of a structure, so that HVAC loads can be more effectively managed, is also explained. Finally, the potential impacts of a Non-Intrusive Load Monitor (NILM) on a ship are investigated.
by Ryan David Zachar.
Nav. E.
S.M. in Engineering and Management
Mirhadizadeh, S. A. "Monitoring hydrodynamic bearings with acoustic emission and vibration analysis." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7888.
Повний текст джерелаFeng, Guojin. "Optimisation of vibration monitoring nodes in wireless sensor networks." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/30320/.
Повний текст джерелаCharles, Peter. "Torsional vibration-based monitoring of medium-speed diesel engines." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706131.
Повний текст джерелаBisht, Saurabh Singh. "Vibration Measurement Based Damage Identification for Structural Health Monitoring." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77301.
Повний текст джерелаPh. D.
Smit, Wynand Gerhardus. "Fan blade damage detection using on-line vibration monitoring." Diss., Pretoria : [s.n.], 2002. http://upetd.up.ac.za/thesis/available/etd-11302005-091637/.
Повний текст джерелаRehman, Anees ur. "Vibration-based condition monitoring of a turbomachinery bladed system." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2557/.
Повний текст джерелаGoi, Yoshinao. "Bayesian Damage Detection for Vibration Based Bridge Health Monitoring." Kyoto University, 2018. http://hdl.handle.net/2433/232013.
Повний текст джерелаWiig, Johan. "Optimization of fault diagnosis in helicopter health and usage monitoring systems." Paris, ENSAM, 2006. http://www.theses.fr/2006ENAM0055.
Повний текст джерелаA Health and usage Monitoring System (HUMS) anticipates discrepancies in the rotorcraft drive-train, giving the operator an opportunity to perform corrective maintenance before any damage becomes critical. In addition to usage spectrum analysis, a HUMS deploys vibration monitoring as a means to detect propagating faults. This method consists in comparing in-flight vibration recordings to a normal state baseline. A recurrent problem with this approach is that this baseline is aircraft specific and subject to change between major overhauls, forcing the operator to relearn the baseline on regular bases. This study presents methods for evaluating the time-progression of the drive-train vibration signature. By studying fluctuation in vibration signature over time, it is possible to detect events such as maintenance actions and fault propagations without any aircraft specific baseline. Several progression analysis methods are tested, both parametric models and filter-banks. Finally, progression analysis is used as a basis for fault detection, and is shown to produce better results than traditional methods
Moussa, Wael. "Thermography-Assisted Bearing Condition Monitoring." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31379.
Повний текст джерелаMcCarthy, David M. J. "Monitoring 3D vibrations in structures using high resolution blurred imagery." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21680.
Повний текст джерелаWang, KeSheng. "Vibration monitoring on electrical machine using Vold-Kalman filter order trackin." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-08282008171945/.
Повний текст джерелаQian, Feng. "Piezoelectric Energy Harvesting for Powering Wireless Monitoring Systems." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99156.
Повний текст джерелаDoctor of Philosophy
Wireless monitoring systems with embedded wireless sensor nodes have been widely applied in human health care, structural health monitoring, home security, environment assessment, and wild animal tracking. One distinctive advantage of wireless monitoring systems is to provide unremitting, wireless monitoring of interesting parameters, and data transmission for timely decision making. However, most of these systems are powered by traditional batteries with finite energy capacity, which need periodic replacement or recharge, resulting in high maintenance costs, interruption of service, and potential environmental pollution. On the other hand, abundant energy in different forms such as solar, wind, heat, and vibrations, diffusely exists in ambient environments surrounding wireless monitoring systems which would be otherwise wasted could be converted into usable electricity by proper energy transduction mechanisms. Energy harvesting, also referred to as energy scavenging and energy conversion, is a technology that uses different energy transduction mechanisms, including electromagnetic, photovoltaic, piezoelectric, electrostatic, triboelectric, and thermoelectric, to convert ambient energy into electricity. Compared with traditional batteries, energy harvesting could provide a continuous and sustainable power supply or directly recharge storage devices like batteries and capacitors without interrupting operation. Among these energy transduction mechanisms, piezoelectric materials have been extensively explored for small-size and low-power generation due to their merits of easy shaping, high energy density, flexible design, and low maintenance cost. Piezoelectric transducers convert mechanical energy induced by dynamic strain into electrical charges through the piezoelectric effect. This dissertation presents novel piezoelectric energy harvesters, including design, modeling, prototyping, and experimental tests for energy harvesting from human walking, broadband bi-stable nonlinear vibrations, and torsional vibrations for powering wireless monitoring systems. A piezoelectric footwear energy harvester is developed and embedded inside a shoe heel for scavenging energy from heel striking during human walking to provide a power supply for wearable sensors embedded in health monitoring systems. The footwear energy harvester consists of multiple piezoelectric stacks, force amplifiers, and two heel-shaped metal plates taking dynamic forces at the heel. The force amplifiers are designed and optimized to redirect and amplify the dynamic force transferred from the heel-shaped plates and then applied to the inner piezoelectric stacks for large power output. An analytical model and a finite model were developed to simulate the electromechanical responses of the harvester. The footwear harvester was tested on a treadmill under different walking speeds to validate the numerical models and evaluate the energy generation performance. An average power output of 9.3 mW/shoe and a peak power output of 84.8 mW are experimentally achieved at the walking speed of 3.0 mph (4.8 km/h). A two-stage force amplifier is designed later to improve the power output further. The dynamic force at the heel is amplified twice by the two-stage force amplifiers before applied to the piezoelectric stacks. An average power output of 34.3 mW and a peak power output of 110.2 mW were obtained from the harvester with the two-stage force amplifiers. A bio-inspired bi-stable piezoelectric energy harvester is designed, prototyped, and tested to harvest energy from broadband vibrations induced by animal motions and fluid flowing for the potential applications of self-powered fish telemetry tags and bird tags. The harvester consists of a piezoelectric macro fiber composite (MFC) transducer, a tip mass, and two sub-beams constrained at the free ends by in-plane pre-displacement, which bends and twists the two sub-beams and consequently creates curvatures in both length and width directions. The bi-direction curvature design makes the cantilever beam have two stable states and one unstable state, which is inspired by the Venus flytrap that could rapidly change its leaves from the open state to the close state to trap agile insects. This rapid shape transition of the Venus flytrap, similar to the vibration of the harvester from one stable state to the other, is accompanied by a large energy release that could be harvested. Detailed design steps and principles are introduced, and a prototype is fabricated to demonstrate and validate the concept. The energy harvesting performance of the harvester is evaluated at different excitation levels. Finally, a piezoelectric energy harvester is developed, analytically modeled, and validated for harvesting energy from the rotation of an oil drilling shaft to seek a continuous power supply for downhole sensors in oil drilling monitoring systems. The position of the piezoelectric transducer on the surface of the shaft is parameterized by two variables that are optimized to obtain the maximum power output. Approximate expressions of voltage and power of the torsional vibration piezoelectric energy harvester are derived from the theoretical model. The implicit relationship between the power output and the two position parameters of the transducer is revealed and physically interpreted based on the approximate power expression. Those findings offer a good reference for the practical design of the torsional vibration energy harvesting system.
Calabrese, Francesca. "Vibration Monitoring and Intelligent Diagnosis Tools for Condition-Based Maintenance." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Знайти повний текст джерелаHe, Xianfei. "Vibration-based damage identification and health monitoring of civil structures." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3289036.
Повний текст джерелаTitle from first page of PDF file (viewed February 5, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
Casey, Cody. "Crack detection in a rotor dynamic system by vibration monitoring." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17838.
Повний текст джерелаYao, ShiPing. "Modelling and simulation of vibration signals for monitoring of gearboxes." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301653.
Повний текст джерелаIbrahim, Ghalib Rzayyig. "Design and implementation of gearboxes vibration based condition monitoring system." Thesis, Manchester Metropolitan University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543248.
Повний текст джерелаChen, Mingxian. "Combining the active control of gear vibration with condition monitoring." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286755.
Повний текст джерелаQin, Dong. "HAND-ARM VIBRATION EXPOSURE MONITORING WITH SKIN TEMPERATURE AND PHOTOPLETHYSMOGRAPHY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1492098556166678.
Повний текст джерелаHansson, Johan. "Detection of Long Term Vibration Deviations in GasTurbine Monitoring Data." Thesis, Linköpings universitet, Fordonssystem, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-170266.
Повний текст джерелаJhinaoui, Ahmed. "Subspace-based identification and vibration monitoring algorithms for rotating systems." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S161.
Повний текст джерелаSubspace identification methods are widely used for caracterizing modal param-eters and for vibration monitoring of mechanical structures. They were shown powerful for the so-called linear time-invariant systems. However, they are not adapted to rotating sys-tems such as helicopters and wind turbines, which are inherently time-periodic systems. The goal of this thesis is to extend the applicability of these methods to this particular class of systems. First, a new identification algorithm is suggested. This algorithm permits to iden-tify the so-called Floquet modal structure. Then, a sensitivity study is conducted in order to quantify uncertainties, related to noises and other sources, about the identified modal param-eters. Finally and based on the suggested identification algorithm, a method for instability detection is developed. The main feature of this method is to define some residual, which is function of modal parameters, then to detect an eventual change over it which means a possible deviation toward an unstable regime. The suggested methods were applied to both numerical and experimental data