Thèses : « Measurements and monitoring »

1

Kuhlmann, Volker. « Synchronous measurements and power quality monitoring ». Thesis, University of Canterbury. Electrical and Electronic Engineering, 2004. http://hdl.handle.net/10092/6158.

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The task of simultaneous power systems measurements at locations which can be hundreds of kilometres apart carries the problem of precise synchronisation. To introduce this topic, this thesis begins with an overview of time, time stamping and synchronised data acquisition, and reviews its application to power quality monitoring. It then discusses the requirements for such systems and how different application scenarios shift the emphasis between aspects of the requirements. The complexity of a power distribution monitoring system is most dependent on the number of channels and sites which must be analysed, and the required time stamping accuracy. For some applications, samples need to be time stamped with an accuracy of 1µs. A requirements specification template is presented which aids, for example, in purchase decisions to establish needed features. A specific example of such a system, CHART III, has been developed at the University of Canterbury (Christchurch, New Zealand), which uses a hardware time base and sample dock generation, hardware time stamping, and GPS synchronisation to achieve a time stamping accuracy of 0.5 µs. The design of the time base of this system is published in this thesis and described in detail. The CHART III system was used to gain practical experience and to establish its usability and operational limitations, and provided input for the theoretical considerations of an ideal system. Synchronised distributed data acquisition using two and three CHART III instrument was performed on two live power systems, collecting data in the frequency and time domains. A number of enhancements were made as a result, particularly to the control and analysis software in the areas of extending the handling of the GPS receiver and provision of additional system status and error information. Because the emphasis of the work is on the instrumentaton, no further analysis of the collected data is presented in this thesis. The CHART III system was connected to the internet to investigate issues of remote configuration and the consolidation of sample analysis at a single powerful computer. Limits for time domain measurements, which have a higher data rate than the system can handle continuously, were established as being a minimum of 10 seconds. In a data acquisition system, the quantisation error introduced by the ADC sets a lower limit for the noise. The effects of this quantisation noise on the recovery of harmonic magnitudes and phases were examined. Simulations were performed to model the influence of ADC width, fast Fourier transform length, harmonic amplitude and harmonic order. Both magnitude and phase errors are independent of harmonic order, decrease with the number of ADC quantisation levels, and decrease with the square root of the transform length. The magnitude error is independent of the harmonic amplitude for a sufficiently large amplitude to noise ratio. The phase error is inversely proportional to the amplitude. The accuracy of a harmonic analyser can therefore be increased by increasing the ADC width or the transform length. For accuracies likely to be required by typical power quality applications, these simulations indicate that a 12 bit ADC gives sufficiently accurate results. Finally, the effect of current trends in microprocessor technology is discussed. Power quality monitoring systems can now be built much more simply and cheaply then when CHART III was designed. The most important improvement is that a single standard CPU can now handle the data from a number of channels, eliminating the need for specialised digital signal processors and the associated cost of producing software for a second architecture. Processor performance seems to be set to increase steadily, promising future improvements in time stamping accuracy, the number of channels which can be handled by one processor, and the availability of more complex analysis functions.

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2

Zhou, Ming. « Advanced System Monitoring with Phasor Measurements ». Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27813.

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Phasor Measurement Units (PMUs) are widely acknowledged as one of the most promising developments in the field of real-time monitoring of power systems. By aligning the time stamps of voltage and current phasor measurements that are consistent with Coordinated Universal Time (UTC), a coherent picture of the power system state can be achieved through either direct measurements or simple linear calculations. With the growing number of PMUs planned for installation in the near future, both utilities and research institutions are looking for the best solutions to the placement of units as well as to the applications that make the most of phasor measurements. This dissertation explores a method for optimal PMU placement as well as two applications of synchronized phasor measurements in state estimation. The pre-processing PMU placement method prepares the system data for placement optimization and reduces the size of the optimization problem. It is adaptive to most of the optimal placement methods and can save a large amount of computational effort. Depth of un-observability is one of the criteria to allow the most benefit out of a staged placement of the units. PMUs installed in the system provide synchronized phasor measurements that are highly beneficial to power system state estimations. Two related applications are proposed in the dissertation. First, a post-processing inclusion of phasor measurements in state estimators is introduced. This method avoids the revision of the existing estimators and is able to realize similar results as mixing phasor data with traditional SCADA with a linear afterwards step. The second application is a method to calibrate instrument transformers remotely using phasor measurements. Several scans of phasor measurements are used to accomplish estimating system states in conjunction with complex instrument transformer correction factors. Numerical simulation results are provided for evaluation of the calibration performance with respect to the number of scans and load conditions. Conducting theoretical and numerical analysis, the methods and algorithms developed in this dissertation are aimed to strategically place PMUs and to incorporate phasor measurements into state estimators effectively and extensively for better system state monitoring. Simulation results show that the proposed placement method facilitates approaching the exact optimal placement while keep the computational effort low. Simulation also shows that the use of phasor measurement with the proposed instrument transformer correction factors and proposed state estimation enhancement largely improves the quality of state estimations.
Ph. D.

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3

Engelbrecht, André. « Structural integrity monitoring using vibration measurements ». Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-07032006-122342/.

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Al-Haider, Sahailah Ahmed. « Monitoring and modelling direct atmospheric formaldehyde measurements ». Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436382.

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Aaltonen, Jaana. « Ground Monitoring using Resistivity Measurements in Glaciated Terrains ». Doctoral thesis, Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3177.

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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.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Um 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.

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Halén, Axel. « Cloud Monitoring and observation measurements in OpenStack environment ». Thesis, Luleå tekniska universitet, Datavetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70896.

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8

Gerrard, Carl Andrew. « Remote monitoring of power system conductor voltages ». Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263990.

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9

Hamilton, Ruth Munro. « Cardiorespiratory measurements using inspired oxygen sinusoids ». Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301515.

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10

Lindh, Thomas. « Performance monitoring in communication networks ». Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3724.

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Performance monitoring in communication networks, which isthe main topic of this thesis, is an essential part ofperformance and network management. The applications cover anumber of different areas such as daily operations andmaintenance, usage information for billing purposes, customerreports, traffic control, planning, and dimensioning.

The main purpose of the thesis is to develop a single methodfor measurement of the most significant network performanceparameters in IP networks. It is a continuation from a previouslicentiate thesis that focused on performance monitoring incell-based networks.

The development of a measurement method that combines activeand passive approaches using monitoring blocks is the maincontribution of this work. A traffic flow performance meterbased on these principles has been implemented as an extensionto the open source flow meter NeTraMet and tested. Theresolution and precision of the results are determined by thesize of the monitoring block, which is the methods mainparameter. Relevant statistical issues regarding packet lossesand delays are analysed. Finally, the measurement method isdiscussed in the context of applications, as well as networkand service management systems in general.

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Fung, Stephanie SY. « Seismic monitoring of dynamic bridge deformations using strain measurements ». Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/6975.

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In recent years, civil engineers have become very interested in developing systems to monitor the health of the structures that they have designed and built. There are many systems that can monitor the vertical deflections of structures, but there are few that can effectively measure deflections due to dynamic loads. This report investigates the use of a mathematical model proposed by Swiss engineers, Vurpillot et al [1998], and the selection of innovative fiber optic strain gauges along with a high-speed data acquisition system for future verification tests. Various laboratory static and dynamic verification tests using traditional electrical resistance strain gauges were performed on three beam specimens in the Structures Laboratory at the University of Hawaiʻi at Manoa. The results produced by the mathematical model agreed well with the measured results and the theoretical results from the SAP2000 model. Further tests will be performed using the Fabry-Perot fiber optic strain gauges and data acquisition system that has been selected in this report.
x, 107 leaves

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12

McCormick, Jackson C. « Spatial and temporal ionospheric monitoring using broadband sferic measurements ». Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54469.

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The objective of this thesis is to use radio emissions from lightning, known as `radio atmospherics' or `sferics', to study the temporal and spatial variation of the lower ionosphere, a layer of ionized atmosphere beginning at $\sim$70 km altitude (D-region). Very Low Frequency (VLF, 3$-$30kHz) radio waves are a useful diagnostic for lower ionospheric monitoring due to their reflection from this region and global propagation. Traditionally, the lower ionosphere has been sensed using single-frequency VLF transmitters allowing for analysis of a single propagation path, as there are only a small number of transmitters. A lightning stroke, however, releases an intense amount of impulsive broadband VLF radio energy in the form of a sferic, which propagates through the Earth-ionosphere waveguide. Lightning is globally distributed and very frequent, so a sferic is therefore also a useful diagnostic of the D-region. This is true both for ambient or quiet conditions, and for ionospheric perturbations such as solar flare x-ray bursts. Lightning strokes effectively act as separate VLF transmitting sources. As such, they uniquely provide the ability to add a spatial component to ionospheric remote sensing, in addition to their broadband signature which cannot be achieved with man-made transmitters. We describe the methods of processing in detail. As an example, we analyze a solar flare during which time there is a significant change in magnitude and frequency content of sferics. This disturbance varies with distance from the source, as well as time. We describe the methods of processing in detail, and show results at Palmer Station, Antarctica for both a quiet and active solar day.

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Hall, Angus John. « Electronic measurements of area and perimeter in ultrasonic images ». Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328883.

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14

Jazayeri, Sina. « Measurement and monitoring of moisture content in timber and investigations of moisture gradients using dielectric measurements ». Thesis, University of Bedfordshire, 1999. http://hdl.handle.net/10547/622156.

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This thesis addresses various issues in connection with the measurement of moisture content in timber. The early parts include long term experimentally based studies which culminated in producing recommendations to existing British Standards for equilibrium moisture content (EMC) of timber in internal environments. Findings consistently showed lower EMCs than existing recommended values; these are believed to be caused by socio-economic factors. Intermediate sections of the thesis continue with tests on electrical methods of moisture content measurement to establish a basis for comparability and the claimed accuracy of currently available moisture meters in the market. To this end, the performance of a wide range of resistance-type moisture meters in worldwide use was critically investigated under laboratory conditions - it was established that even under the strict controlled conditions of the study, large discrepancies are not uncommon (as great as 13% moisture content difference was observed). While some instruments consistently underestimated, others overestimated under identical conditions. Lack of agreed standards for species corrections and temperature correction factors were found to be the main cause of disagreement between the meters. Further discussions include the layout for a proposed standard in which agreed values for species and temperature correction factors would be established. In the latter part of the thesis moisture gradients in timber, the causes and the current methods of assessment are discussed. In particular, the performance of a leading brand capacitance-type moisture meter was systematically investigated both in the absence and in the presence of predetermined moisture gradients. It was established that moisture gradients severely affect the measured moisture content. A computer controlled capacitance measurement system based on resonance detection was developed to initially replicate the behaviour of conventional capacitance-type moisture meters, and to further investigate possible moisture gradient detection protocols. Two electrode designs were used in order to investigate methods by which moisture gradients could be detected. It was shown that a multi-plate electrode can be used to detect moisture gradients in timber to depths of at least 10 mm.

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Virebrand, Marcus. « Real-time monitoring of voice characteristics usingaccelerometer and microphone measurements ». Thesis, Linköpings universitet, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69760.

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VoxLog is a portable voice accumulator, that uses both an accelerometer that measures skin vibrations and a regular microphone to collect data. The goal of the thesis was to implement and evaluate methods that based on this data estimate the three different voice parameters fundamental frequency, phonation and soundpressure level. For pitch, three different methods were evaluated. The different methods all require relatively low computational power since the goal was to implement at least one of them on the digital signal processor in the VoxLog. The results from these evaluations show that the best estimations of pitch were made with a FFT-based approach that uses phase information to get an estimation with high frequencyresolution. Phonation is estimated with an energy based voice activity detection method.This estimation is then used to choose when sound pressure level should be estimated. Here one of the main problems was to make a distinction between when sound pressure level should be estimated for the wearer of the VoxLog or when an estimation should be made for the background noise. This was solved by implementing a time window before and after phonation were neither is estimated. For both pitch and sound pressure level a feedback functionality was implemented. The feedback is given to the user via vibrations in the VoxLog, the feedback is given when estimated parameters break set limits on pitch or sound pressure level.

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Veen, Robertus Leonardus Petrus van. « In Vivo optical measurements for diagnostics and monitoring ot treatment ». [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2006. http://hdl.handle.net/1765/10483.

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Nuqui, Reynaldo Francisco. « State Estimation and Voltage Security Monitoring Using Synchronized Phasor Measurements ». Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/28266.

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The phasor measurement unit (PMU) is considered to be one of the most important measuring devices in the future of power systems. The distinction comes from its unique ability to provide synchronized phasor measurements of voltages and currents from widely dispersed locations in an electric power grid. The commercialization of the global positioning satellite (GPS) with accuracy of timing pulses in the order of 1 microsecond made possible the commercial production of phasor measurement units. Simulations and field experiences suggest that PMUs can revolutionize the way power systems are monitored and controlled. However, it is perceived that costs and communication links will affect the number of PMUs to be installed in any power system. Furthermore, defining the appropriate PMU system application is a utility problem that must be resolved. This thesis will address two key issues in any PMU initiative: placement and system applications. A novel method of PMU placement based on incomplete observability using graph theoretic approach is proposed. The objective is to reduce the required number of PMUs by intentionally creating widely dispersed pockets of unobserved buses in the network. Observable buses enveloped such pockets of unobserved regions thus enabling the interpolation of the unknown voltages. The concept of depth of unobservability is introduced. It is a general measure of the physical distance of unobserved buses from those known. The effects of depth of unobservability on the number of PMU placements and the errors in the estimation of unobserved buses will be shown. The extent and location of communication facilities affects the required number and optimal placement of PMUs. The pragmatic problem of restricting PMU placement only on buses with communication facilities is solved using the simulated annealing (SA) algorithm. SA energy functions are developed so as to minimize the deviation of communication-constrained placement from the ideal strategy as determined by the graph theoretic algorithm. A technique for true real time monitoring of voltage security using synchronized phasor measurements and decision trees is presented as a promising system application. The relationship of widening bus voltage angle separation with network stress is exploited and its connection to voltage security and margin to voltage collapse established. Decision trees utilizing angle difference attributes are utilized to classify the network voltage security status. It will be shown that with judicious PMU placement, the PMU angle measurement is equally a reliable indicator of voltage security class as generator var production. A method of enhancing the weighted least square state estimator (WLS-SE) with PMU measurements using a non-invasive approach is presented. Here, PMU data is not directly inputted to the WLS estimator measurement set. A separate linear state estimator model utilizing the state estimate from WLS, as well as PMU voltage and current measurement is shown to enhance the state estimate. Finally, the mathematical model for a streaming state estimation will be presented. The model is especially designed for systems that are not completely observable by PMUs. Basically, it is proposed to estimate the voltages of unobservable buses from the voltages of those observable using interpolation. The interpolation coefficients (or the linear state estimators, LSE) will be calculated from a base case operating point. Then, these coefficients will be periodically updated using their sensitivities to the unobserved bus injections. It is proposed to utilize the state from the traditional WLS estimator to calculate the injections needed to update the coefficients. The resulting hybrid estimator is capable of producing a streaming state of the power system. Test results show that with the hybrid estimator, a significant improvement in the estimation of unobserved bus voltages as well as power flows on unobserved lines is achieved.
Ph. D.

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Zhu, Ruoxi. « Online Voltage Stability Monitoring and Control Using Limited Synchrophasor Measurements ». Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/97197.

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As the scale and complexity of an interconnected power grid has increased significantly, power systems can be operated close to the verge of voltage instability. With the application of Phasor Measurement Units (PMUs), dispatchers are able to monitor long term voltage stability in a real time operational environment. This research addresses the critical issues by proposing three different methods. Voltage Stability Assessment Index (VSAI) is a Thévenin Equivalent (TE) based method considering voltage dynamic mechanisms. To extend the model from one load bus to a critical load center, Optimal Power Flow-Loading limit (OPF-LI) is developed to assess the voltage stability margin. To utilize limited available PMU measurements, State Calculator (SC) is included in the algorithm to approximate the dynamic states at the buses where PMU measurements are not available. The online voltage regulating method in terms of On-load Tap Changer (OLTC) control is also investigated. The methods proposed in this research have been validated with the test cases from the WECC 179 bus system.
M.S.
This thesis proposed a hybrid solution of voltage stability monitoring and control in a power system. For the performance of motors, heaters or other loads in the power system, it is important that the customers are supplied with stable voltage. The variation of the voltage may cause damages to the load. Therefore, the methods in this thesis provides a feasible solution to monitor voltage stability of load centers in a power system. In addition, a novel approach for voltage control is proposed to prevent a voltage collapse of the system. The simulation results illustrate that the approach introduced in this thesis is promising for real time application.

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Medrano, Guillermo [Verfasser]. « Continuous Monitoring of Body Fluids Using Bioimpedance Measurements / Guillermo Medrano ». Aachen : Shaker, 2011. http://d-nb.info/1071528432/34.

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Vargas, MariÌa Angeles MartiÌnez. « Real-time monitoring of cellular toxicity using electrical impedance measurements ». Thesis, University of the West of England, Bristol, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444490.

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Alharbi, Sami Hamad. « Measurements and monitoring of naturally occurring radioactive materials for regulation ». Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/98122/1/Sami_Alharbi_Thesis.pdf.

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This project investigated the measurement of naturally occurring radioactive material. Such measurements are usually conducted to demonstrate compliance with the national and international requirements for radiation protection. The thesis reviewed the current regulation of these radioactive materials and identified the key regulatory challenges that relevant authorities face when implementing or establishing a regime for NORM. Limitations on the measurement of the release of radon (a radioactive gas) from surfaces were determined. The parameters influencing radon and thoron levels in indoor environments were investigated. The potential use of a broad energy germanium detector for the application of NORM was examined.

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McDannold, Nathan J. « MRI monitoring of high temperature ultrasound therapy / ». Thesis, Connect to Dissertations & ; Theses @ Tufts University, 2002.

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Thesis (Ph.D.)--Tufts University, 2002.
Adviser: David Weaver. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 218-243). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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Junaid, Junaid. « Network-Based Monitoring of Quality of Experience ». Doctoral thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-10495.

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The recent years have observed a tremendous shift from the technology-centric assessment to the user-centric assessment of network services. Consequently, measurement and modelling of Quality of Experience (QoE) attracted many contributions from researchers and practitioners. Generally, QoE is assessed via active and passive measurements. While the former usually allows QoE assessment on the test traffic, the latter opens avenues for continuous QoE assessment on the real traffic generated by the users. This thesis contributes towards passive assessment of QoE. This thesis document begins with a background on the fundamentals of network management and objective QoE assessment. It extends the discussion further to the QoE-centric monitoring and management of network, complimented by the details about QoE estimator agent developed within the Celtic project QuEEN (Quality of Experience Estimators in Network). The discussion on findings starts with results from subjective tests to understand the relationship between waiting times and user subjective feedback over time. These results strengthen the understanding of timescales on which users react, as well as, the effect of user memory on QoE. The findings show that QoE drops significantly when the user faces recurring waiting times of 0.5 s to 4 s durations in case of video streaming and web browsing services. With recurring network disturbances within every 8 s – 16 s time intervals, the user tolerance to waiting times decreases constantly, showing the sign of user memory of recent disturbances. Subsequently, this document introduces and evaluates a passive wavelet-based QoE monitoring method. The method detects timescales on which transient outages occur frequently. A study presents results from qualitative measurements, showing the ability of wavelet to differentiate on-fly between “Good” and “Bad” traffic streams. In sequel, a quantitative study systematically evaluates wavelet-based metrics. Subsequently, the subjective evaluation and wavelet analysis of 5 – 6 minutes long video streaming sessions on mobile networks show that wavelet-based metrics is indeed useful for passive monitoring of QoE issues. Finally, this thesis investigates a method for passive monitoring of user reactions to degrading network performance. The method is based on the TCP termination flags. With a systematic evaluation in a test environment, the results characterise termination of data transfers in case of different user actions in the web browser.

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Culliss, Jerel Alan. « A Method for PMU-Based Reconfigurable Monitoring ». Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35646.

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Given an increasing tendency towards distributed generation and alternative energy sources, the power grid must be more carefully monitored in order to ensure stability. Phasor Measurement Units (PMUs) provide very good observation of a small area of a network, but their relatively high cost prevents them from being deployed at every point. Therefore, to monitor an entire network, State Estimation is still required. By combining these two techniques, the accuracy and speed of power network monitoring can be improved. This thesis presents a method for achieving this goal from both hardware and computational perspectives. Practical considerations for PMU placement are discussed, such as instrument transformer calibration, and an algorithm is developed to apply this technique to any power system. The resulting method is termed reconfigurable monitoring - computationally isolated areas which may be grouped as necessary to allow for flexibility in power system monitoring.
Master of Science

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Lee, Chi-yeung. « Estimation of blood glucose variations using noninvasive metabolic measurements ». Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39330680.

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Lee, Chi-yeung, et 李子洋. « Estimation of blood glucose variations using noninvasive metabolic measurements ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39330680.

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Al-Rawi, S. A. N. « Silicon sublimation at ultra high vacuum with microprocessor monitoring and measurements ». Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382189.

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Kokko, V. (Voitto). « Condition monitoring of squirrel-cage motors by axial magnetic flux measurements ». Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:9514269381.

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Abstract The aim of this research work is to develop a tool for condition monitoring of squirrel-cage motors using axial magnetic flux measurements, and to design a diagnostics system for electrical motors. The basic theory of the measurements and systems was found through literature reviews and was further developed from the experimental results of this research work. Fluxgate magnetometers and Hall effect sensors are not reliable enough for condition monitoring purposes, but measurements by flux coil sensors can reach adequate reliability. The useful frequency area of the flux coil sensor is from about 0.2 Hz to 15 kHz, an area is well applicable for condition monitoring of squirrel-cage motors. Output voltage is frequency dependent, increasing towards higher frequencies. Sufficient sensitivity is usually reached by a flux coil sensor having a diameter of about 30 cm and the number of turns of about 200. Sensitivity can be improved by increasing the diameter or number of turns of the coil. The sensor should be placed axially centred on the end of the motor, and measurements should be made with the loaded motor in steady operation. Output voltage is typically from the microvolt to millivolt level, however, installation inside the motor can increase it from tens of millivolts to some volts. The dynamic resolution requirement of measurement is about 70 dB and the highest line resolution needed for the spectrum analysis is about 3200 lines. Time base signal can be used to study rapid disturbances of flux caused by mechanical loading or switching of the frequency converter. Various motor failures cause specific variation to the frequency distribution of flux, so spectrum analysis is well applicable for condition monitoring. Reference measurement of each motor is required because stator winding factors, installation tolerances, operating conditions and mechanical load affect leakage flux. A broken rotor bar failure can be detected from the amplitude difference between the supply frequency and its rotor bar induced sideband. A broken rotor end ring failure can be detected by the amplitude difference between the slip frequency and the supply frequency. However, it was found that the stator current spectrum is a more reliable method of detecting both these rotor failures. The supply voltage asymmetry can also be evaluated by specific sidebands of axial flux. Turn to turn failure of the stator winding was most reliably detected by sidebands around the rotor slot pass frequencies. Equations for frequency converter supplied motors are the bases for similar equations, but the supply frequency is replaced by the output current frequency of the converter. The developed diagnostics system design for condition monitoring of ac motors includes stator current, flux coil, temperature, vibration, partial discharge, bearing current and voltage measurements. At the system diagnosis stage these measurable signals are divided to time base and frequency base signals and for each of them a fault indicator is determined. For flux coil measurements four fault indicators were found: rotor bar failure ratio, rotor end ring failure ratio, stator winding turn to turn ratio and supply voltage asymmetry operation ratio. With these failure indicators we determine failure location, state and cause. From this information a lifetime prediction of the motor is made. The results of this work are used to analyse flux coil measurements of squirrel-cage motors. In addition the research has led to a special application to monitor electric motors using an on-line condition monitoring system for paper machines and power plants.

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Hajiabdolmajid, Vahid Reza. « Remote monitoring of underground excavations by means of deformation measurements (CIUS) ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq21767.pdf.

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Carbone, Daniele. « Gravity monitoring of Mount Etna (Italy) through discrete and continuous measurements ». Thesis, Open University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393192.

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Cindemir, Umut. « Thin films for indoor air monitoring : Measurements of Volatile Organic Compounds ». Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302558.

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Volatile organic compounds (VOCs) in the indoor air have adverse effects on the dwellers residing in a building or a vehicle. One of these effects is called sick building syndrome (SBS). SBS refers to situations in which the users of a building develop acute health effects and discomfort depending on the time they spend inside some buildings without having any specific illness. Furthermore, monitoring volatile organic compounds could lead to early diagnosis of specific illnesses through breath analysis. Among those VOCs formaldehyde, acetaldehyde can be listed. In this thesis, VOC detecting thin film sensors have been investigated. Such sensors have been manufactured using semiconducting metal oxides, ligand activated gold nanoparticles and Graphene/TiO2 mixtures. Advanced gas deposition unit, have been used to produce NiO thin films and Au nanoparticles. DC magnetron sputtering has been used to produce InSnO and VO2 thin film sensors. Graphene/TiO2 sensors have been manufactured using doctor-blading. While presenting the results, first, material characterization details are presented for each sensor, then, gas sensing results are presented. Morphologies, crystalline structures and chemical properties have been analyzed using scanning electron microscopy, X-ray diffraction and X-ray photo electron spectroscopy. Furthermore, more detailed analyses have been performed on NiO samples using extended X-ray absorption fine structure method and N2 adsorption measurements. Gas sensing measurements were focused on monitoring formaldehyde and acetaldehyde. However, responses ethanol and methane were measured in some cases to monitor selectivity. Graphene/TiO2 samples were used to monitor NO2 and NH3. For NiO thin film sensors and Au nano particles, fluctuation enhanced gas sensing is also presented in addition to conductometric measurements.

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Ali, Md Afsar. « In-process quality monitoring of laser welds using multi-sensor measurements / ». The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192447428925.

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Dong, Jingyuan. « Power System Disturbance Analysis and Detection Based on Wide-Area Measurements ». Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/30129.

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Wide-area measurement systems (WAMS) enable the monitoring of overall bulk power systems and provide critical information for understanding and responding to power system disturbances and cascading failures. The North American Frequency Monitoring Network (FNET) takes GPS-synchronized wide-area measurements in a low-cost, easily deployable manner at the 120 V distribution level, which presents more opportunities to study power system dynamics. This work explores the topics of power system disturbance analysis and detection by utilizing the wide-area measurements obtained in the distribution networks. In this work, statistical analysis is conducted based on the major disturbances in the North American Interconnections detected by the FNET situation awareness system between 2006 and 2008. Typical frequency patterns of the generation and load loss events are analyzed for the three North American power Interconnections: the Eastern Interconnection (EI), the Western Electricity Coordinating Council (WECC), and the Electric Reliability Council of Texas (ERCOT). The linear relationship between frequency deviation and frequency change rate during generation/loss mismatch events is verified by the measurements in the three Interconnections. The relationship between the generation/load mismatch and system frequency is also examined based on confirmed generation loss events in the EI system. And a power mismatch estimator is developed to improve the current disturbance detection program. Various types of power system disturbances are examined based on frequency, voltage and phase angle to obtain the event signatures in the measurements. To better understand the propagation of disturbances in the power system, an automated visualization tool is developed that can generate frequency and angle replays of disturbances, as well as image snapshots. This visualization tool correlates the wide-area measurements with geographical information by displaying the measurements over a geographical map. This work makes an attempt to investigate the visualization of the angle profile in the wide-area power system to improve situation awareness. This work explores the viability of relying primarily on distribution-level measurements to detect and identify line outages, a topic not yet addressed in previous works. Line outage sensitivity at different voltage levels in the Tennessee Valley Authority (TVA) system is examined to analyze the visibility of disturbances from the point of view of wide-area measurements. The sensor placement strategy is proposed for better observability of the line trip disturbances. The characteristics of line outages are studied extensively with simulations and real measurements. Line trip detection algorithms are proposed that employs the information in frequency and phase angle measurements. In spite of the limited FDR coverage and confirmed training cases, an identification algorithm is developed which uses the information in the real measurements as well as the simulation cases to determine the tripped line.
Ph. D.

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Liaw, Hibisca. « Underwater measurements of heart rate ». Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47546.

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The objective of this project is to develop a device that can monitor the heart rate and respiration of cetaceans. This would provide a way to quantitatively measure stress and determine the impact of human activity on cetaceans, especially for certain species that have been difficult to monitor in the past. There are many challenges to developing such a device, including determining the appropriate type of sensor, reducing the effect of flow noise, and designing an effective attachment method; this paper primarily focuses on determining the most suitable acoustic transducer. Experiments were conducted to compare various acoustic sensors in detecting heart rate. The electronic stethoscope performed the best in the experiments, but the results showed that other transducers, such as accelerometers and pressure sensors, also performed well and could be successful options with further development. Data processing methods to identify heartbeats and characterize signals are also discussed in this paper. Future work on the project involves subsequent tests to address other design variables as well as replicate experiments on animals.

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Auchinvole, Craig Alexander R. « SERS nanosensors for intracellular redox potential measurements ». Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/9706.

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Redox regulation and homeostasis are critically important in the regulation of cell function; however, there are significant challenges in quantitatively measuring and monitoring intracellular redox potentials. The work in this thesis details a novel approach to intracellular redox monitoring. The approach is based on the use of nanosensors, which comprise molecules capable of sensing the local redox potential, assembled on gold nanoshells. Since the Raman spectra of the sensor molecules change depending on their oxidation state, and since the nanoshells allow a large enhancement of the Raman scattering, intracellular potential can be calculated by simple optical measurements. A full description of the design, fabrication and characterisation (spectroscopic and electrochemical) of the nanosensors is provided within. The ability to deliver nanosensors into cells in a controllable fashion was confirmed using electron microscopy. Results from a range of assays are also presented which reveal that introduction of nanosensors does not result in any cytotoxicity. Sensor utility in monitoring redox potentials as cells responded to physiological and superphysiological oxidative and reductive stimuli was investigated. Importantly, the capability of the nanosensors in monitoring intracellular potentials in a reversible, non-invasive manner, and over a previously unattainable potential range, is demonstrated.

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Matasane, Matasane Clement. « Investigation into the monitoring of microwaves in microwave cavities using optical techniques ». Thesis, Peninsula Technikon, 2002. http://hdl.handle.net/20.500.11838/1076.

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Thesis (MTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 2002.
Tne purpose of this research or study was to perform an investigation in the use of optical fibers as sensor elements in order to develop a millimetre wave instrument capable of measuring microwave power within microwave cavities. Included in the scope of the project was an investigation of microwaves and microwave power measurements techniques. The emphasis of the research work was to develop expertise in photonics, by modeling and developing a measuring technique using optical techniques. This was deemed to be highly beneficial in laboratory experimentation and for possible use by microwave technicians. The implementation was amongst others, done by means of computer simulation and associated hardware, together with fiber-optic accessories. In order to conduct this research a literature and technology survey of current non-optical microwave power measurement technique was done. With this a review different power measurements systems and their relationship towards microwave power measurements was conducted. Within the scope of the project, a study of fiber optics sensors and its components was also conducted, which enabled models for a Mach-Zehnder microwave sensor to be developed. This resulted in the development of inexpensive electronic signal conditioning and detection techniques to enable measurements that employed a Mach-Zehnder Interferometer for this sensor technique. Finally, as microwaves are difficult to measure with pure electronic equipment, different approaches were made to investigate the temperature changes and other parameters on optical fiber to avoid damage to it. The specifications of hardware and circuitry suitable to measure these effects were determined.

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Luthy, Thierry. « Three-dimensional permeability measurements based on direct current and ultrasound monitoring techniques / ». Zürich, 2003. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15050.

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Liu, Guoping. « Oscillation monitoring system based on wide area phasor measurements in power systems ». Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Summer2010/g_liu_060110.pdf.

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Thesis (Ph. D.)--Washington State University, August 2010.
Title from PDF title page (viewed on July 23, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 76-81).

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Johansson, Cecilia. « High-sensitivity Radioactive Xenon Monitoring and High-accuracy Neutron-proton Scattering Measurements ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4279.

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Kuhn, S., M. Buchholz, T. Wels, K. Breunig, B. Scholten, I. Spahn et H. H. Coenen. « Cross section measurements on 61Cu for proton beam monitoring above 20 MeV ». Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166097.

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Introduction All experimental studies involving charged particle induced nuclear reactions require a precise knowledge of monitor reactions. A number of well described proton induced monitor reactions exist in the lower energy range [1], which is covered by most medical cyclotrons. Concerning proton energies above 20 MeV, however, the accuracy of the monitor reactions declines as cross section data becomes scarcer. Furthermore, the growing interest in precise determination of projectile energies by comparing of ratios of monitor reaction cross sections demands new measurements and evaluations of known data for high threshold monitor radionuclides. In this work cross section measurements on the formation of 61Cu were done and energy de-pendent radionuclide ratios were calculated. Material and Methods For investigation of the natCu(p,x)61Cu reaction copper foils of natural isotopic composition (Goodfellow Ltd.) were irradiated. The targets were of 10 and 20 μm thickness, having a diameter of 15 mm. Proton bombardments up to 45 MeV incident energy were done in the stacked-foil arrangement at the accelerator JULIC of the Nuclear Physics Institute (IKP) of the Forschungszentrum Jülich. In addition to an internal irradiation possibility the cyclotron is equipped with an external target station which was used for most experiments. It can adapt standard and slanting solid target holders and is equipped with a water cooled four sector collimator and additional helium cooling of the entry foil. Several irradiations were executed. In each stack, besides copper samples, aluminium absorbers and additional nickel monitor foils were also placed, the latter for the determination of the respective beam current. The produced radioactivity of 61Cu was analysed non-destructively using HPGe γ-ray detectors (EG&G Ortec). Results and Conclusion Reaction cross sections of the natCu(p,x)61Cu process up to 45 MeV were measured and com-pared with existing data from the literature (FIG. 2). Except for the data of Williams et al. our results are in good agreement, showing a maxi-mum of about 165 mbarn at 37.5 MeV proton energy. The overall uncertainty of the new cross section data is between 8 and 10 %. In FIG. 3, the excitation functions of the relevant monitor reactions on Cu are shown. In combination with the excitation function of the natCu(p,xn)62Zn reaction, isotope ratios were calculated which can be used for determination of the proton energy within a target stack in the energy range of 22–40 MeV as described by Piel et al. [3]. FIGURE 4 shows the cross section ratio in dependence of the proton energy. Above this energy, 65Zn could be used to generate isotope ratios for energy determination, although the long half-life (T½ = 244.3 d) of that radionuclide may be a problem. Additional cross section measurements are planned in order to further strengthen the data base of this potential monitor reaction. The results of this work shall be evaluated in the framework of an ongoing Coordinated Research Project of the IAEA.

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Kuschmierz, R., Y. Huang, J. Czarske, S. Metschke, F. Löffler et A. Fischer. « 3D shape measurements with a single interferometric sensor for insitu lathe monitoring ». SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35040.

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Temperature drifts, tool deterioration, unknown vibrations as well as spindle play are major effects which decrease the achievable precision of computerized numerically controlled (CNC) lathes and lead to shape deviations between the processed work pieces. Since currently no measurement system exist for fast, precise and insitu 3d shape monitoring with keyhole access, much effort has to be made to simulate and compensate these effects. Therefore we introduce an optical interferometric sensor for absolute 3d shape measurements, which was integrated into a working lathe. According to the spindle rotational speed, a measurement rate of 2,500 Hz was achieved. In-situ absolute shape, surface profile and vibration measurements are presented. While thermal drifts of the sensor led to errors of several µm for the absolute shape, reference measurements with a coordinate machine show, that the surface profile could be measured with an uncertainty below one micron. Additionally, the spindle play of 0.8 µm was measured with the sensor.

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Barron, Darlene H. « Student progress monitoring teachers' perceptions / ». Diss., Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-07082009-152901.

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Schatzmann, Dominik [Verfasser]. « Correlating Flow-based Network Measurements for Service Monitoring and Network Troubleshooting / Dominik Schatzmann ». Aachen : Shaker, 2013. http://d-nb.info/1051573653/34.

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Palizban, Atefeh. « Wide-area monitoring and control utilizing PMU measurements for a system protection scheme ». Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52888.

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The ever increasing complexity of the electrical grid has made it difficult to predict and anticipate contingencies. This is mainly due to the advent of deregulated electricity markets, aging transmission infrastructure and the growing penetration of renewable resources. The wave of blackouts in recent years has made utilities much more aware of the need for power system wide monitoring and control. One of the fundamental requirements to achieve that goal is to have common measurement reference. A few technology enablers have emerged which have led to development of a new kind of measurement paradigm; Phasor Measurement Units, or PMUs. PMUs bear high potential for wide-area system monitoring and control as well for conducting advanced engineering analysis. PMUs can provide time-synchronized high-resolution estimates of voltage and currents (both phase amplitude and angle) as well as frequency and rate of change of frequency. Such measurements, alternatively called synchrophasors, can provide visibility of a power system distributed over a wide geographical area and can be utilized in a multitude of applications including real-time monitoring, advanced power system protection, and advanced control schemes. In this thesis, a new special protection scheme (SPS) is proposed based on synchronized measurements provided by PMUs. An existing remedial action scheme (RAS) protecting for contingencies impacting the tie-line interconnecting the Alcan system to B.C. Hydro, using conventional relays is studied, and a new scheme based on time-synchronized, and high-resolution voltage angle measurements from PMU’s in a Wide-are monitoring system (WAMs) is proposed . In this new scheme, the angles of the buses at large power plants in both systems are examined and used to calculate various criteria based on region center of angle and the kinetic energy function to implement RAS. The results of a number of time domain simulations demonstrate that the proposed scheme can lead to faster operation of the SPS and decreased amount of generation and load shedding in the Alcan system. The achieved speed and efficiency of the proposed scheme in comparison to the existing installed scheme further highlight the opportunity in utilizing PMU measurements in online applications for power system protection and monitoring.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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Janssen, Pierre. « Monitoring, protection and fault location in power distribution networks using system-wide measurements ». Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209366.

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This work takes place in the context of distribution grids with high level of distributed generation, for example in microgrids. With high level of distributed generation, it has been shown that selective, fast and sensitive network protection is expected to be more difficult. Furthermore, during system restoration, the accurate fault location could be more challenging to assess, thereby increasing the average outage duration.

Thanks to cost reductions and improvement of information and communication technologies, future distribution networks will probably have advanced communication infrastructures and more measurement devices installed in order to manage the increasing complexity of those networks, which is primarily caused by the introduction of distributed generation at the distribution level.

Therefore this thesis investigates how the monitoring, protection and fault location functions can be improved by using system-wide measurements, i.e. real-time measurements such as synchronized voltage and current measurements recorded at different network locations. Distributed synchronized measurements bring new perspectives for these three functions: protection and fault location are usually performed with local measurements only and synchronized measurements are not common in monitoring applications. For instance, by measuring distributed generators infeed together with some feeder measurements, the protection is expected to be more sensitive and selective and the fault location to be more accurate.

The main contribution of this work is the use of state estimation, which is normally only used for network monitoring, for the protection and the fault location.

The distribution system state estimation is first developed using the classical transmission system approach. The impact of the placement of the measurement devices and of a relatively low measurement redundancy on the accuracy, on the bad data detection and on the topology error identification capabilities of the estimator are discussed and illustrated. This results in recommendations on the placement of the meters.

Then, a backup protection algorithm using system-wide measurements is presented. The coherence of the measurements and the healthy network model are checked thanks to a linear three-phase state estimation. If the model does not fit to the measurements and if the estimated load is too high or unbalanced, a fault is detected. The advantages of the method are that the voltage measurement redundancy is considered, improving the detection sensitivity, and that load models may be considered in the algorithm, avoiding the need to install measurement devices on every line of the network.

Finally, two new impedance-based fault location algorithms using distributed voltage and current recordings are proposed. By defining statistical errors on the measurements and the network parameters, a method to compute a confidence interval of the fault distance estimate is proposed. The fault location accuracy and its sensitivity to the fault conditions (e.g. fault resistance or fault type) and to the different sources of error are assessed on a simulated distribution system.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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Safizadeh, Fariba. « Monitoring deposit properties and passivation of impure copper anodes by electrochemical noise measurements ». Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28449/28449.pdf.

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Konopacky, Q. M., C. Marois, B. A. Macintosh, R. Galicher, T. S. Barman, S. A. Metchev et B. Zuckerman. « ASTROMETRIC MONITORING OF THE HR 8799 PLANETS : ORBIT CONSTRAINTS FROM SELF-CONSISTENT MEASUREMENTS ». IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621227.

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We present new astrometric measurements from our ongoing monitoring campaign of the HR 8799 directly imaged planetary system. These new data points were obtained with NIRC2 on the W.M. Keck II 10 m telescope between 2009 and 2014. In addition, we present updated astrometry from previously published observations in 2007 and 2008. All data were reduced using the SOSIE algorithm, which accounts for systematic biases present in previously published observations. This allows us to construct a self-consistent data set derived entirely from NIRC2 data alone. From this data set, we detect acceleration for two of the planets (HR 8799b and e) at >3 sigma. We also assess possible orbital parameters for each of the four planets independently. We find no statistically significant difference in the allowed inclinations of the planets. Fitting the astrometry while forcing coplanarity also returns chi(2) consistent to within 1 sigma of the best fit values, suggesting that if inclination offsets of less than or similar to 20 degrees are present, they are not detectable with current data. Our orbital fits also favor low eccentricities, consistent with predictions from dynamical modeling. We also find period distributions consistent to within 1 sigma with a 1:2:4:8 resonance between all planets. This analysis demonstrates the importance of minimizing astrometric systematics when fitting for solutions to highly undersampled orbits.

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Baldwin, Thomas L. « Real-time phasor measurements for improved monitoring and control of power system stability ». Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-170758/.

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Barber, David Edward. « Applications of phasor measurements to the real-time monitoring of a power system ». Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12162009-020322/.

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Xu, Xueyan. « Prediction of life-threatening events in infants using heart rate variability measurements ». Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2288.

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Thesis (Ph. D.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains viii, 250 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 240-250).

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