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1
Tichý, Jiří. „Multi-body modely dynamických soustav s elektro-mechanickými rezonátory“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443721.
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This thesis is dealing with creation of computation model of energy harvestors. Harvestors based on translational motion and planar motion were modeled. These models were created in MSC Adams. Proposed harvestors are tranforming mechanical vibrations into electrical energy by electromagnetical induction. To achieve better electrical output, harvestors were tuned to natural frequency suitable for chosen aplication. First proposed harvestor is meant for railway track. For validation of its usability in intended application, model of railway track section is also proposed. Force generated by passing train is used for excitation of the track model. Second harvestor is nonlinear electromechanical oscilator proposed for use on unanchored sea buoy (drifter). After retuning previously proposed concept of energy harvestor to natural frequency 1.6 Hz, computation model for simulation purposes was created. After the simulation of sinusoidal excitation, the excitation based on real sea data was simulated. When excited by regular sea, the peak electric power 9 W was achieved. When excited by irregular sea the peak electrical power of the generator was 7.5 mW.
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Enström-Granath, Inger. „Ambulatory blood pressure monitoring a tool for more comprehensive assessment /“. Dalby : Kävlinge : Dept. of Community Health Sciences, Lund University ; Kävlinge Health Centre, 1992. http://books.google.com/books?id=9gdsAAAAMAAJ.
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3
De, Villiers Daniel Johannes. „Hybrid energy harvesting system for a condition monitoring mote“. Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1067.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009Traditional high voltage power transformers feature sensors measuring basic parameters from oil and gas and are limited to on-site monitoring. Unforeseen failures and breakdowns on these transformers have led to extensive financial losses even with planned maintenance schedules in place. A distinct need has arisen to actively monitor and identify causes of such failures. However, no or little infrastructure exists for effective remote condition monitoring. Wireless sensor networks can be introduced to actively monitor and identify causes of such failures. Sensor motes in the network are battery operated and therefore constrained by limited energy in these batteries. An alternative to battery-powered sensor motes is the conversion of available energy harvested from the surrounding environment into useable electrical energy powering the sensor motes. The primary objective of this research was to examine methods to harvest energy from both the environment and high voltage power transformer. A low cost and feasibly sized hybrid energy harvesting power management prototype was successfully developed that enabled sustained sensor mote operation for prolonged condition monitoring of high voltage transformers. The sensor mote utilised a piezoelectric cantilever to generate usable electrical energy from the transformer tank vibration. Together with solar energy harvesting, the system allowed for a battery-less self-sustained wireless sensor mote capable of autonomously monitoring its surroundings. The power management system's modular architecture provided for the inclusion of additional energy harvesting techniques. This allowed condition monitoring solutions not exclusively for power transformers but proposed an extensible condition monitoring solution for various applications.
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Nilsson, Lena. „Respiratory monitoring using reflection mode photoplethysmography : clinical and physiological aspects /“. Linköping : Dept. of Medicine and Care, Univ, 2005. http://www.bibl.liu.se/liupubl/disp/disp2005/med898s.pdf.
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5
Backus, Jonathon. „Monitoring the interaction of multiple mode deterioration mechanisms in concrete“. Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669541.
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The current Eurocodes (British Standards 2005b) and American Standards (ACI Committee 318 2004) stipulate single deterioration mechanism design that caters to the worst case scenario, However, in certain environments such as coastal structures and road structures where de-icing salts are used, combinations of chlorides, sulfates and carbon dioxide are possible. Thus as current codes of practice provide no guidance on how to deal with multiple modes of deterioration this is the main subject of this thesis, In this research project the effects of combined deterioration mechanisms in concrete have been measured over time, Although the effects of chloride, carbon dioxide ingress have been widely researched previously, their interactions and effect on durability of concrete has not been comprehensively covered for common cementitious materials, In this study an accelerated exposure regime was established, This allowed the interactions between carbon dioxide and chloride, and chloride and sulfate, and their effects on the concrete to be assessed. The progression was measured using the following techniques: chloride, sulfate and pH profiles, phenolphthalein indicator, Autoclaim air permeability, compressive strength and X-ray diffraction analysis, It has been shown that combined mechanisms can occur and can have a detrimental effect on the durability of concrete, Thus structures designed to the current standards may deteriorate prematurely, It is recommended that further research is carried out to check that the experimental data correlates with results for existing structures, If these trends hold true then the standards need to be updated to account for these interactions,
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Janssen, Volker Surveying & Spatial Information Systems Faculty of Engineering UNSW. „A mixed-mode GPS network processing approach for volcano deformation monitoring“. Awarded by:University of New South Wales. School of Surveying and Spatial Information Systems, 2003. http://handle.unsw.edu.au/1959.4/20771.
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Ground deformation due to volcanic magma intrusion is recognised as an important precursor of eruptive activity at a volcano. The Global Positioning System (GPS) is ideally suited for this application by being able to measure three-dimensional coordinate changes of the monitoring points over time. Due to the highly disturbed ionosphere in equatorial regions, particularly during times of maximum solar activity, a deformation monitoring network consisting entirely of single-frequency GPS receivers cannot deliver baseline solutions at the desired accuracy level. In this thesis, a mixed-mode GPS network approach is proposed in order to optimise the existing continuous single-frequency deformation monitoring system on the Papandayan volcano in West Java, Indonesia. A sparse network of dual-frequency GPS receivers surrounding the deformation zone is used to generate empirical 'correction terms' in order to model the regional ionosphere. These corrections are then applied to the single-frequency data of the inner network to improve the accuracy of the results by modelling the residual atmospheric biases that would otherwise be neglected. This thesis reviews the characteristics of existing continuously operating GPS deformation monitoring networks. The UNSW-designed mixed-mode GPS-based volcano deformation monitoring system and the adopted data processing strategy are described, and details of the system's deployment in an inhospitable volcanic environment are given. A method to optimise the number of observations for deformation monitoring networks where the deforming body itself blocks out part of the sky, and thereby significantly reduces the number of GPS satellites being tracked, is presented. The ionosphere and its effects on GPS signals, with special consideration for the situation in equatorial regions, are characterised. The nature of the empirically-derived 'correction terms' is investigated by using several data sets collected over different baseline lengths, at various geographical locations, and under different ionospheric conditions. Data from a range of GPS networks of various sizes, located at different geomagnetic latitudes, including data collected on Gunung Papandayan, were processed to test the feasibility of the proposed mixed-mode deformation monitoring network approach. It was found that GPS baseline results can be improved by up to 50% in the midlatitude region when the 'correction terms' are applied, although the performance of the system degrades in close proximity to the geomagnetic equator during a solar maximum.
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Janssen, V. „A mixed-mode GPS network processing approach for volcano deformation monitoring“. School of Surveying and Spatial Information Systems, The University of New South Wales, 2003. http://eprints.utas.edu.au/510.
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Ground deformation due to volcanic magma intrusion is recognised as an important precursor of eruptive activity at a volcano. The Global Positioning System (GPS) is ideally suited for this application by being able to measure three-dimensional coordinate changes of the monitoring points over time. Due to the highly disturbed ionosphere in equatorial regions, particularly during times of maximum solar activity, a deformation monitoring network consisting entirely of single-frequency GPS receivers cannot deliver baseline solutions at the desired accuracy level. In this thesis, a mixed-mode GPS network approach is proposed in order to optimise the existing continuous single-frequency deformation monitoring system on the Papandayan volcano in West Java, Indonesia. A sparse network of dual-frequency GPS receivers surrounding the deformation zone is used to generate empirical 'correction terms' in order to model the regional ionosphere. These corrections are then applied to the single-frequency data of the inner network to improve the accuracy of the results by modelling the residual atmospheric biases that would otherwise be neglected. This thesis reviews the characteristics of existing continuously operating GPS deformation monitoring networks. The UNSW-designed mixed-mode GPS-based volcano deformation monitoring system and the adopted data processing strategy are described, and details of the system's deployment in an inhospitable volcanic environment are given. A method to optimise the number of observations for deformation monitoring networks where the deforming body itself blocks out part of the sky, and thereby significantly reduces the number of GPS satellites being tracked, is presented. The ionosphere and its effects on GPS signals, with special consideration for the situation in equatorial regions, are characterised. The nature of the empirically-derived 'correction terms' is investigated by using several data sets collected over different baseline lengths, at various geographical locations, and under different ionospheric conditions. Data from a range of GPS networks of various sizes, located at different geomagnetic latitudes, including data collected on Gunung Papandayan, were processed to test the feasibility of the proposed mixed-mode deformation monitoring network approach. It was found that GPS baseline results can be improved by up to 50% in the mid-latitude region when the 'correction terms' are applied, although the performance of the system degrades in close proximity to the geomagnetic equator during a solar maximum.
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Alder, Tyson Scott. „Determining Natural Frequencies Using Embedded and Placed Sensors under Ambient and Shaker Excitation“. DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5857.
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Dynamic monitoring of structures is a method of detecting changes and damage to the structure. Vibration based monitoring has been used to detect damage in rotating machinery and is gaining popularity in the field of Structural Health Monitoring (SHM). Monitoring involves detecting changes in natural frequencies and changes in mode shapes. These changes reflect changes to properties of the bridge which can indicate damage.
The Nibley Bridge is a single span bridge comprised of ten deck bulb girders. The bridge spans 25.91m (85 ft.) and includes two lanes, sidewalks on both sides, and a small median. The Nibley Bridge was constructed with monitoring in mind. A dynamic monitoring system was planned to detect frequencies for long term monitoring. Initial monitoring of the embedded accelerometers was ineffective, so additional testing was required. An impact test was done with additional sensors to calibrate the embedded sensors. To further define the natural frequencies and mode shapes of the bridge, two shaker tests were also performed.
The embedded sensors were noted as having a large noise range. Also, they required a specific data logger to detect meaningful data. Recommendations for the use of the embedded accelerometers were determined and defined. The additional tests were able to assist in calibrating the accelerometers, as well as defining the natural frequencies and mode shapes of the structure. Natural frequencies were defined for each test and the changing condition of the bridge between those tests. The addition of asphalt occurred between two tests and a change of approximately 20° C between the other two tests. Though there is not much information to form a correlation, the detected changes define the dynamic aspects of the bridge.
Lastly, mode shapes were determined and a Modal Assurance Criterion (MAC)analysis was done to correlate the measured and analytical mode shapes. This model helped to indicate which parameters effect the mode shapes of the structure. Comparison between these parameters and changes between them help to indicate the predicted behavior of the structure under different circumstances. Though these tests do not define all of the dynamic properties of the bridge, they do provide a general baseline of values that can be expected for future tests of the structure.
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Mehdizadeh, Mohammad, und n/a. „Curvature Mode Shape Analyses of Damage in Structures“. RMIT University. Aerospace, Mechanical & Manufacturing Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091022.154814.
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In recent years, the use of composite structures in engineering application has increased. This is mainly due to their special advantages such as high structural performance, high corrosion resistance, tolerance of temperature; extreme fatigue resistance and high strength/weight ratio. However, some disorders like fibre breakage, matrix cracking and delaminations could be caused by operational loading, aging, chemical attack, mechanical vibration, changing of ambient conditions and shock etc. during the service. Although these disorders are hardly visible, they can severely reduce the mechanical properties and the load carrying capability of the composite structure. The aim of this research project is to develop a Vibration-based Structural Health Monitoring (SHM) method for carbon/epoxy composite beam specimens with the embedded artificial delaminations. The Laser Vibrometer Machine was used to excite the beams and gather the responses of the structure to the excitations. The physical properties such as frequency, velocity, mode shapes, and damping of the defective beams were measured. By using a C-SCAN machine, the accuracy of the positions of the delaminations was verified to be about 95% is accurate. Curvature mode shapes as a scalable damage detection parameter is calculated using an analytical model based on the Heaviside step function and the Central Difference Approximation (CDA) technique. The vibration-based damage detection method is then obtained using the difference between curvature mode shapes of the intact and damaged carbon/epoxy beams. An accurate prediction of 90% was attained. These results are proposed and discussed in detail in this study. Finally, the Fatigue Crack Propagation Test was applied on Samples with embedded delamination to extend the crack. The ASTM E399-90 standard is used for the experiment and a careful fatigue crack growth routine was designed and implemented to advance the delamination in a controlled manner. The total extension of 17 mm was observed with Microscope. The total propagation as determined by the curvature mode plots was 17.84 mm.
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Walia, Anoop Singh. „Novel current-mode sensor interfacing and radio blocks for cell culture monitoring“. Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5291.
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Since 2004 Imperial College has been developing the world’s first application-specific instrumentation aiming at the on-line, in-situ, physiochemical monitoring of adult stem cell cultures. That effort is internationally known as the ‘Intelligent Stem Cell Culture Systems’ (ISCCS) project. The ISCCS platform is formed by the functional integration of biosensors, interfacing electronics and bioreactors. Contrary to the PCB-level ISCCS platform the work presented in this thesis relates to the realization of a miniaturized cell culture monitoring platform. Specifically, this thesis details the synthesis and fabrication of pivotal VLSI circuit blocks suitable for the construction of a miniaturized microelectronic cell monitoring platform. The thesis is composed of two main parts. The first part details the design and operation of a two-stage current-input currentoutput topology suitable for three-electrode amperometric sensor measurements. The first stage is a CMOS-dual rail-class AB-current conveyor providing a low impedancevirtual ground node for a current input. The second stage is a novel hyperbolic-sinebased externally-linear internally-non-linear current amplification stage. This stage bases its operation upon the compressive sinh−1 conversion of the interfaced current to an intermediate auxiliary voltage and the subsequent sinh expansion of the same voltage. The proposed novel topology has been simulated for current-gain values ranging from 10 to 1000 using the parameters of the commercially available 0.8μm AMS CMOS process. Measured results from a chip fabricated in the same technology are also reported. The proposed interfacing/amplification architecture consumes 0.88-95μW. The second part describes the design and practical evaluation of a 13.56MHz frequency shift keying (FSK) short-range (5cm) telemetry link suitable for the monitoring of incubated cultures. Prior to the design of the full FSK radio system, a pair of 13.56MHz antennae are characterized experimentally. The experimental S-parameter-value determination of the 13.56MHz wireless link is incorporated into the Cadence Design Framework allowing a high fidelity simulation of the reported FSK radio. The transmitter of the proposed system is a novel multi-tapped seven-stage ring-oscillator-based VCO whereas the core of the receiver is an appropriately modified phase locked loop (PLL). Simulated and measured results from a 0.8μm CMOS technology chip are reported.
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Huang, Weimin Carleton University Dissertation Engineering Systems and Computer. „Monitoring and modelling multimedia traffic over TCP/IP/ATM networks“. Ottawa, 1997.
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Kelly, Brendan T. „A Newly Proposed Method for Detection, Location, and Identification of Damage in Prestressed Adjacent Box Beam Bridges“. Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339520527.
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13
Pagno, Bruno Lorandi. „Everyday visualization: discovering more about individuals“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/179522.
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As pessoas estão ficando cada vez mais interessadas no uso de monitores de atividade. A quantidade de dados de indivíduos disponível está ajudando na expansão e desenvolvimento de novas aplicações e projetos de visualizações para ser usados em casa, em ciência (e.g. para entender melhor o comportamento de populações) ou em governos interessados em desenvolver cidades inteligentes. Nesse trabalho é apresentada uma visualização simples e intuitiva que permite a exploração de dados pessoais por pessoas comuns. Com foco em ajudar as pessoas a compreenderem a si mesmas melhor e perceber coisas novas sobre seus dados. A visualização construída neste projeto é baseada em metáforas de calendários, relógios e mapas, além de utilizar gráficos de barra para explorar dados crus. A exploração desses dados se dá pela interação entre essas visualizações. Para avaliar o produto do trabalho são apresentados dois casos de uso onde alguns usuários tiveram a oportunidade de observar e discutir suas informações de dois pontos de vista diferente: exploração de dados pessoais para auto-aperfeiçoamento e o uso do Everyday Visualization por cientistas da saúde. Em nenhum dos casos houve treinamento. As visualizações resultantes agregam diversas fontes de dados, indo além de outros trabalhos de visualização casual e pessoal. Os resultados promissores demonstram a viabilidade de tais técnicas para visualização de dados pessoais.People are becoming increasingly more interested in the use of activity monitors and selfimprovement. The availability of individuals’ data is also pushing the development of new applications and data visualization projects to be used at home, in science (e.g. to better understand the behavior of populations) or for governments interested in developing intelligent cities. In this work, we present an easy and intuitive set of visualizations to allow the exploration of personal data by common people. We focus on helping people to know themselves better and to make sense of their own data. Our visualizations are based on the metaphors of calendars, clocks, and maps, as well as on the use of bar charts to explore raw data. Data exploration is therefore guaranteed by the interaction between them. In order to evaluate our work we present two use cases, where few users observe and discuss the data from different points of view: the exploration of personal data for self-improvement purposes, and the use of Everyday Visualization by health scientists. Both use cases were ran without any training session. The resulting visualization aggregates several different data sources, going beyond many of the personal and casual visualization works. The promising results achieved demonstrated the viability of the use of such techniques for personal data visualizations and sense making.
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Abhinav, Abhinav. „Sensor Failure Mode Detection and Self-Validation“. University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227254283.
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Schumacher, Peter Michael. „Components of variability in digitized M-mode echocardiography : applied to monitoring of Adriamycin cardiotoxicity“. Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/25688.
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This work concerns the use of M-mode echocardiography, a medical diagnostic technique based on sound wave imaging, in the assessment of the degree of impairment of heart function in children. One cause of left ventricular (LV) impairment is Adriamycin (doxorubicin), a drug used commonly in the treatment of cancer.
Although many investigators have used echocardiography (ECHO) to monitor cardiac damage due to Adriamycin (ADM), the magnitude of long-term longitudinal or serial changes one can expect in a typical healthy child's readings has not been assessed. This knowledge might be useful in monitoring. We designed and carried out a study with 18 healthy children to: (i) quantify the longitudinal variation in ECHO parameters between successive months, and compare this to short-term (minutes) serial variation and to between-subject variability; (ii) compare different ECHO measures with respect to these types of variability, as well as on the basis of measurement accuracy; (iii) compare short-term serial variation with that due to the measurement process, with the aim of increasing the precision of a reading; (iv) examine whether subject age and sex have any bearing on the readings.
Our ECHO variables consist of 4 measures of change in cardiac dimension between systole and diastole, 6 peak velocities and 6 peak normalized velocities. We used a 4-factor hierarchal factorial design. To address (i) to (iii) above, the data were analyzed in a univariate fashion with a variance components model. It was found that: (a) between-subject variation accounts for the largest proportion of total variability; (b) within-subject monthly longitudinal variation is substantial, and approaches the magnitude of that between subjects; (c) variation between successive months is markedly larger than the short-term variability; (d) tracing variation, a type of measurement error, is negligible in comparison with short-term variation, implying that the precision of a reading can be improved more by analyzing additional heartbeats than by replicating the analysis of each beat; (e) the LV shortening fraction is more stable over time and is subject to less measurement error than the peak systolic and peak diastolic velocities of the LV, the septal, or the posterior walls.
To address (iv) above, we performed an Analysis of Covariance for each variable. Subject sex was found to have no bearing on ECHO readings. There is some indication that some of the measures are linearly related to subject age.
In addition, these data were combined with single ECHO measurements on 33 other healthy children to yield 95% prediction intervals for normal ECHO parameters; 95% bounds for normal monthly differences in the values were also obtained. Together with serial data on 25 children being treated with ADM, we attempted to identify which ECHO variables would be more useful in monitoring for LV dysfunction. As well as taking into account the relative sensitivities of the variables to ADM, we found the smallest set of measures which would collectively identify all children displaying abnormal (drops in) LV function. This was formulated and solved as an integer programming problem. Lastly, a Factor Analysis was used in an attempt to reveal the dimensionality of normal LV function.
Apparently the major impact of ADM on LV function occurs during the first half of therapy. Many patients are marginally within normal bounds at mid-therapy, even though they may exhibit abnormally large changes since onset.
Based on the above criteria, we tentatively recommend the following ECHO measures as potentially useful for monitoring of ADM cardiotoxicity: ejection fraction (shortening fraction may be used equivalently), systolic percent change of the septal and posterior wall thicknesses, peak (normalized) LV diastolic velocity, peak posterior wall systolic and normalized diastolic velocities, and peak septal wall diastolic velocity.Business, Sauder School of
Graduate
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Zheng, Rongpeng. „An FPGA Based MPPT and Monitoring System : suitable for a photovoltaic based microgrid“. Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-85558.
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Microgrids containing photovoltaic (PV) cells and wind power gain more and more interest. These microgrids may work in stand-alone mode ("islanding") or be conncted to the main grid. In both modes of operation, power quality must be monitored and controlled. This report focuses on microgrids and aims to implement a monitoring system based on FPGA. In the monitoring system, two applications can be achieved, firstly a PAS-MPPT algorithm in a DC-DC boost converter to improve the maximun power point tracking of a PV unit, and secondly a detection and switching system of the grid mode - stand-alone or connected to the main grid. Simulation results prove the Verilog programs in FPGA are suitable to be used in microgrids.
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Wiliem, Leonard. „Incorporating interdependence in risk likelihood analysis to enhance diagnostics in condition monitoring“. Queensland University of Technology, 2008. http://eprints.qut.edu.au/28559/.
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This research is aimed at addressing problems in the field of asset management relating to risk analysis and decision making based on data from a Supervisory Control and Data Acquisition (SCADA) system. It is apparent that determining risk likelihood in risk analysis is difficult, especially when historical information is unreliable. This relates to a problem in SCADA data analysis because of nested data. A further problem is in providing beneficial information from a SCADA system to a managerial level information system (e.g. Enterprise Resource Planning/ERP). A Hierarchical Model is developed to address the problems. The model is composed of three different Analyses: Hierarchical Analysis, Failure Mode and Effect Analysis, and Interdependence Analysis. The significant contributions from the model include: (a) a new risk analysis model, namely an Interdependence Risk Analysis Model which does not rely on the existence of historical information because it utilises Interdependence Relationships to determine the risk likelihood, (b) improvement of the SCADA data analysis problem by addressing the nested data problem through the Hierarchical Analysis, and (c) presentation of a framework to provide beneficial information from SCADA systems to ERP systems. The case study of a Water Treatment Plant is utilised for model validation.
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Kwoun, Sun Jong Lec Ryszard. „A multiresonance thickness-shear mode (MTSM) sensor for monitoring the formation of biological thin films /“. Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1161.
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Vinod, Kalkotwar Divya. „Wireless Body Area Network for Patient Monitoring in Hospitals“. Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206121.
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The master thesis is a prototyping project of a wireless body area network (WBANs) for patient monitoring in hospitals. The goal of this project was to study various technologies suitable for wireless body area networks, complete a requirement analysis, design a WBAN suitable to achieve the requirements and to test and evaluate the system against the requirements. Seven sensor end nodes are chosen to monitor seven vital signs for patient monitoring. After studying different technologies suitable for WBANs, IEEE 802.15.4j was chosen because it communicates in a special allocation of medical spectrum of 2360 to 2400MHz. A coordinator or master will be the center of the network using a star topology. Due to certain limitations in the firmware of the NXP FRDMKW40Z, IEEE 802.15.4j had to be dropped and IEEE 802.15.4 was the final chosen technology because the only difference between IEEE 802.15.4j and IEEE802.15.4 is the difference in the physical layer, while the developed application remains the same, making the shift back to IEEE802.15.4j, in the future, simple. There have been several projects working on the same idea with IEEE 802.15.4, but they do not combine multiple sensors to form a network and the total throughput requirements for this thesis project are much higher. The beacon mode and the non-beacon mode of IEEE 802.15.4 are studied. Non beacon mode is unpredictable due to the use of carrier sense multiple access with collision avoidance (CSMA/CA) to access the medium. When multiple end nodes compete to get access to the medium, unreliability is introduced into the system. In the beacon mode, because of the slotted CSMA access of sixteen equally spaced time slots for communication, there is a restriction of the size of a time slot and thus, the high throughput requirement of the system is not met. The solution proposed in the thesis project is to develop a custom time slot system in the non-beacon mode, where each end node is granted a reserved time slot of a specific length as required by the end node. There is a timer mechanism which makes sure that the time slots for each device maintain the time limit on the time slot, on the side of the main master/coordinator of the network and on the side of the end node. The protocol for an end node to join a personal area network (PAN) is called as the association process. The association process enables the end node to be a part of a PAN to exchange its sensor data. Traditionally, in IEEE 802.15.4, the end nodes scan the sixteen IEEE 802.15.4 channels and when an appropriate coordinator is found, the end node initiates the association process with the coordinator. The solution proposed for the formation of the network by the association process is to use two different technologies. The end nodes and the coordinator exchange information using near field communication (NFC) technology by a simple tapping mechanism. The end node has an active NFC tag while the coordinator has an NFC reader. During the tap between the two devices, first the coordinator reads the end node data from the active tag. This data is required to form the custom time slot. Next the coordinator writes all association information into the active tag. After the NFC data exchange is done, the end node initiates the traditional IEEE 802.15.4 association protocol to join the coordinator’s PAN. Similarly after seven end nodes are associated to the coordinator, the network begins to function. All the end nodes communicate their data to the coordinator. The coordinator collects all the sensor data from the seven end nodes and may send the cumulative sensor data to the backend database servers which may be viewed by the medical authorities, this part is not included in the current version of the project. Several tests are run on this system to evaluate the requirements of latency, throughput and quality of service with two different ranges of 20cm and 250cm. The latency of association between the coordinator and end node is 632ms. The required throughput is met by the network. The packet delivery rate of the system is always above 99%. The graphs for packet delivery rates for all the sensors with a range of 20cm and 250 cm are shown in the appendices. The probabilities for the packet delivery rates greater than 90%, 99%, 99.9% and 99.99% are also graphically shown using a normal distribution in the appendices.
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Bremstedt, Pedersen Ivan, und Alfred Andersson. „More than downloading : Visualization of data produced by sensors in a home environment“. Thesis, KTH, Kommunikationssystem, CoS, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-97937.
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A home automation system usually contains a set of tools that users use to control devices in their homes, often remotely. These devices often include but are not limited to light switches, thermostats, thermometers, window blinds, and climate controls. The potential for these kinds of systems is huge because of the sheer number of devices that could be controlled and managed with minimal and inexpensive extra hardware. Many of the appliances in a normal home could benefit from being connected to a system that allows the owner to manage and control the devices in their home. Thus the number of potential devices is orders of magnitude larger than the number of homes connected to the system. There are several systems on the market that provide systems to monitor and control a home environment, however these systems only support specific in system devices. This uncovers a problem where a homeowner only has the opportunity to use specific products that fit into these systems. By introducing an open platform for the public that are not bound to any system we can allow more devices to be integrated in the home and contribute to further development of smarter homes. The goal with this project was to provide a scalable open platform with the possibility of asynchronous updating. This has been done by implementing multiple logical parts to both provide a web interface for the user and to allow us to handle communication and storage of data. All these parts are linked together to form a system of servers that handles all background operations. This thesis discusses and presents implementations of all of these servers, how they are implemented, communicate with each other, provide secure connections and how they can scale with increasing usage. In this process we also discuss and present techniques that were used, how to use them and their benefits, to help us reach our goal.”Home automation” syftar till ett system som låter användaren kontrollera och styra olika apparater i hemmet, ofta sker detta utifrån. Dessa apparater inkluderar, men är inte begränsade till ljusbrytare, termostater, termometrar, persienner eller klimatanläggningar. Potentialen för ett sådant system är enormt då antalet apparater som skulle kunna övervakas med endast minimal och billig extra hårdvara är stort. Många av dessa apparater kan dra nytta av att vara ansluten till ett system som gör det möjligt för ägaren att hantera och styra enheter i deras hem. Antalet apparater är därför mångdubbelt fler än antalet hem som är kopplade till systemet. Det finns flera system på marknaden som ger användaren ett sätt att övervaka och styra en hemmiljö, men dessa system är ofta låsta och stödjer bara specifika enheter. Genom att införa en öppen plattform för allmänheten som inte är bunden till något system, kan vi tillåta att fler enheter kan integreras i hemmet och bidra till ytterligare utveckling av smartare hem. Målet med detta projekt var att skapa en skalbar öppen plattform med möjlighet till asynkron uppdatering. Detta har gjorts genom att implementera flera logiska delar för att förse användaren med ett webbgränssnitt och för att tillåta oss hantera kommunikation och lagring av data. Alla dessa delar är sammanlänkade för att bilda ett system av servrar som hanterar alla bakgrundsprocesser. Denna avhandling diskuterar och presenterar implementeringar av alla dessa servrar, hur de genomförs, kommunicera med varandra, ger säkra anslutningar och hur de kan skala med ökad användning. I denna process diskuterar och presenterar vi de tekniker som använts, hur man använder dem och deras fördelar.
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Oruganti, Krishna, und krishnaov@yahoo com. „Evaluation of Damage in Structures using Vibration-based Analyses“. RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091002.143408.
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Composite materials are supplanting conventional metals in aerospace, automotive, civil and marine industries in recent times. This is mainly due to their high strength and light weight characteristics. But with all the advantages they have, they are prone to delamination or matrix cracking. These types of damage are often invisible and if undetected, could lead to appalling failures of structures. Although there are systems to detect such damage, the criticality assessment and prognosis of the damage is often more difficult to achieve. The research study conducted here primarily deals with the structural health monitoring of composite materials by analysing vibration signatures acquired from a laser vibrometer. The primary aim of the project is to develop a vibration based structural health monitoring (SHM) method for detecting flaws such as delamination within the composite beams. Secondly, the project emphasises on the method's ability to recognise the locatio n and severity of the damage within the structure. The system proposed relies on the examination of the displacement mode shapes acquired from the composite beams using the laser vibrometer and later processing them to curvature mode shapes for damage identification and characterization. Other identification techniques such as a C-scan has been applied to validate the location and size of the defects with the structures tested. The output from these plots enabled the successful identification of both the location and extent of damage within the structure with an accuracy of 96.5%. In addition to this, this project also introduces a method to experimentally compute the critical stress intensity factor, KIC for the composite beam. Based on this, a technique for extending the defect has been proposed and validated using concepts of fatigue and fracture mechanics. A composite specimen with a 40 mm wide delamination embedded within was loaded under fatigue conditions and extension of the defect by 4mm on either s ide of the specimen's loading axis was achieved satisfactorily. The experimental procedure to extend the defect using fatigue was validated using the SLV system. Displacement and Curvature mode shapes were acquired post-fatigue crack extension. Upon analysing and comparing the displacement and curvature mode shapes before and after crack extension, the extended delamination was identified satisfactorily.
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Vilar, Mateo Ruth. „Optical performance monitoring in optical packet-switched networks“. Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8926.
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Para poder satisfacer la demanda de mayores anchos de banda y los requisitos de los nuevos servicios, se espera que se produzca una evolución de las redes ópticas hacia arquitecturas reconfigurables dinámicamente. Esta evolución subraya la importancia de ofrecer soluciones en la que la escalabilidad y la flexibilidad sean las principales directrices. De acuerdo a estas características, las redes ópticas de conmutación de paquetes (OPS) proporcionan altas capacidades de transmisión, eficiencia en ancho de banda y excelente flexibilidad, además de permitir el procesado de los paquetes directamente en la capa óptica. En este escenario, la solución all-optical label switching (AOLS) resuelve el cuello de botella impuesto por los nodos que realizan el procesado en el dominio eléctrico. A pesar de los progresos en el campo del networking óptico, las redes totalmente ópticas todavía se consideran una solución lejana . Por tanto, es importante desarrollar un escenario de migración factible y gradual desde las actuales redes ópticas basadas en la conmutación de circuitos (OCS). Uno de los objetivos de esta tesis se centra en la propuesta de escenarios de migración basados en redes híbridas que combinan diferentes tecnologías de conmutación. Además, se analiza la arquitectura de una red OPS compuesta de nodos que incorporan nuevas funcionalidades relacionadas con labores de monitorización y esquemas de recuperación.
Las redes ópticas permiten mejorar la transparencia de la red, pero a costa de aumentar la complejidad de las tareas de gesión. En este escenario, la monitorización óptica de prestaciones (OPM) surge como una tecnología capaz de facilitar la administración de las redes OPS, en las que cada paquete sigue su propia ruta en la red y sufre un diferente nivel de degradación al llegar a su destino. Aquí reside la importancia de OPM para garantizar los requisitos de calidad de cada paquete.Vilar Mateo, R. (2010). Optical performance monitoring in optical packet-switched networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8926
Palancia
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Bellamy, Christopher A. „Sensor-based soil water monitoring to more effectively manage agricultural water resources in coastal plain soils“. Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1263402218/.
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Thanopoulos, Sotirios. „Condition Monitoring of MV Remotely Controlled Distributed Disconnectors“. Thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215947.
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During the last decades, the power grid is getting rapidly digitalised in order to contribute to theestablishment of Smart Grids and evaluate efficiently the extracted bidirectional data from the powersystem infrastructure. This thesis focuses on the MV grid, since its design and operation have changedmainly because of distributed generation installations and the increased demand of information fromstakeholders. Thus, asset management constitutes a significant tool that can increase the reliability ofthe MV network’s operation and its level of control. Studies have shown that a maintenance planbased on condition monitoring of power system apparatuses would be more effective compared to theimplemented time-based scheduled maintenance.This project focuses on MV remotely controlled disconnectors since studies have shown that theirnumber of failures is double compared to manually operated ones. Since maneuverability andsecondary function are the causes of a major failure with the highest occurrence rate, motor currentmonitoring is studied in this thesis. Some devices that have the capability to monitor disconnectors’motor current, are presented. Additionally, the obtained max motor current measurements areevaluated through a parametric and a non-parametric statistical test. The main challenge of this thesisis to show whether the behaviour of motor current can be an indicator regarding to the disconnector’scondition status.Hence, the impact of different factors on the behaviour of motor current is investigated. It is concludedthat disconnectors without a failure during the studied period are more likely to have max motorcurrent measurements higher than 8A and especially in the interval [10-12]A. The difference in motorcurrent of disconnectors with a work order and without failure is more significant in 2015/2016. Itseems that under the aforementioned values of max motor current, a disconnector is more probable tohave the capability to operate properly. It is also concluded that in case of malfunction “Mellanläge”,the value of max motor current is lower than 8A with higher probability and it maybe indicates aproblem of the studied disconnector.Through the comparison in pairs, it could be concluded that the effect of the external environmentalconditions is not so high on the behaviour of disconnectors’ max motor current measurements. Incontrast, it seems that the implementation of a work order, the number of operations and if adisconnector is installed more northerly in Zone 3 play a more significant role on the behaviour of thisdisconnector’s max motor current measurements. Consequently, based on the aforementioned results itis shown that some of the investigated factors could constitute an indicator whether a disconnector ismore or less probable to have the capability to operate properly.Finally, it is calculated the reduction in the interruption cost that could be achieved in case ofimplementation of motor current monitoring on Vattenfall’s remotely controlled distributeddisconnectors.Under de senaste årtiondena har kraftnät blivit snabbt digitaliserad För att bidra till upprättandet hosSmart Grids och effektivt utvärdera de extraherade dubbelriktade data från kraftsystemetsinfrastruktur. Denna exjobbsrapport fokuserar på MV-nätet, eftersom dess design och drift harförändrats främst på grund av distribuerade produktionsanläggningar och ökad efterfrågan påinformation från intressenter. Därför utgör ”asset management’’ ett viktigt verktyg som kan öka elnätstillförlitligheten och styrning. Studier har visat att elnäts underhåll baserad på tillståndsövervakningpå kraftsystemkomponenter skulle kunna vara effektivare jämfört med tidsbaserade schemalagdaunderhåll.Detta exjobb fokuserar på MV-fjärrstyrda frånskiljare eftersom studier har visat att deras felfrekvensär dubbelt högre jämfört med manuella. Eftersom problem i manövrerbarhet och sekundär funktionkan orsaka allvarliga fel med hög frekvens, har studien fokuserats på motorströmövervakningen idetta exjobb. Vissa produkter som har förmåga att övervaka frånskiljares motorström, presenteras.Dessutom utvärderas de maximala motorströmsmätningarna genom både parametriskt och ickeparametrisktstatistiskt test. Huvudutmaningen i denna avhandling är att utreda om motors strömmarkan vara en indikator för frånskiljares tillstånd.Olika faktorer hos motorströmmar har också undersökts. Det dras slutsatsen att frånskiljare utanmisslyckande manövern under den studerade perioden är mer benägna att ha maximalamotorströmmar högre än 8A och speciellt i intervallet [10-12] A. Skillnaden i motors strömmar hosfrånskiljare med arbetsorder och utan fel är mer signifikant under åren 2015/2016. Det verkar som attenligt ovan nämnda värden på max motorström, är en frånskiljare mer sannolikt att fungera korrekt.Det kommer också fram till att i händelse av "Mellanläge" är värdet av max motorströmmar lägre än8A med högre sannolikhet, detta kan kanske indikera ett problem hos frånskiljaren.Genom jämförelsen kan man dra slutsatsen att effekten av de yttre miljöförhållandena inte är så högpå maximala motorströmmar hos frånskiljare. Däremot verkar det som om genomförandet av enarbetsorder, antalet operationer och om en frånskiljare är installerad i zon 3 spelar en viktig roll föruppförandet av denna frånskiljares maximala motors strömmen. På grundval av det ovan nämndaresultatet framgår det att några av de undersökta faktorerna kan utgöra en indikator på att om enfrånskiljare är mer eller mindre sannolikt att ha förmågan att fungera korrekt.Slutligen visar beräkningar att minskningen av avbrottskostnaden kan uppnås vid genomförande avmotorströmövervakning på Vattenfalls fjärrstyrda distribuerade frånskiljare.
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Mann, Jaspreet Kaur. „On-line health monitoring of passive electronic components using digitally controlled power converter“. Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/10778.
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This thesis presents System Identification based On-Line Health Monitoring to analyse the dynamic behaviour of the Switch-Mode Power Converter (SMPC), detect, and diagnose anomalies in passive electronic components. The anomaly detection in this research is determined by examining the change in passive component values due to degradation. Degradation, which is a long-term process, however, is characterised by inserting different component values in the power converter. The novel health-monitoring capability enables accurate detection of passive electronic components despite component variations and uncertainties and is valid for different topologies of the switch-mode power converter. The need for a novel on-line health-monitoring capability is driven by the need to improve unscheduled in-service, logistics, and engineering costs, including the requirement of Integrated Vehicle Health Management (IVHM) for electronic systems and components. The detection and diagnosis of degradations and failures within power converters is of great importance for aircraft electronic manufacturers, such as Thales, where component failures result in equipment downtime and large maintenance costs. The fact that existing techniques, including built-in-self test, use of dedicated sensors, physics-of-failure, and data-driven based health-monitoring, have yet to deliver extensive application in IVHM, provides the motivation for this research ... [cont.].
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Elbadawy, Mohamed Mohamed Zeinelabdin Mohamed. „Dynamic Strain Measurement Based Damage Identification for Structural Health Monitoring“. Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/86167.
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Structural Health Monitoring (SHM) is a non-destructive evaluation tool that assesses the functionality of structural systems that are used in the civil, mechanical and aerospace engineering practices. A much desirable objective of a SHM system is to provide a continuous monitoring service at a minimal cost with ability to identify problems even in inaccessible structural components. In this dissertation, several such approaches that utilize the measured dynamic response of structural systems are presented to detect, locate, and quantify the damages that are likely to occur in structures. In this study, the structural damage is identified as a reduction in the stiffness characteristics of the structural elements. The primary focus of this study is on the utilization of measured dynamic strains for damage identification in the framed structures which are composed of interconnected beam elements. Although linear accelerations, being more convenient to measure, are commonly used in most SHM practices, herein the strains being more sensitive to elemental damage are considered. Two different approaches are investigated and proposed to identify the structural element stiffness properties. Both approaches are mode-based, requiring first the identification of system modes from the measured strain responses followed by the identification of the element stiffness coefficients. The first approach utilizes the Eigen equation of the finite element model of the structure, while the second approach utilizes the changes caused by the damage in the structural curvature flexibilities. To reduce size of the system which is primarily determined by the number of sensors deployed for the dynamic data collection, measurement sensitivity-based sensor selection criterion is observed to be effective and thus used. The mean square values of the measurements with respect to the stiffness coefficients of the structural elements are used as the effective measures of the measurement sensitivities at different sensor locations. Numerical simulations are used to evaluate the proposed identification approaches as well as to validate the sensitivity-based optimal sensor deployment approach.Ph. D.
All modern societies depend heavily on civil infrastructure systems such as transportation systems, power generation and transmission systems, and data communication systems for their day-to-day activities and survival. It has become extremely important that these systems are constantly watched and maintained to ensure their functionality. All these infrastructure systems utilize structural systems of different forms such as buildings, bridges, airplanes, data communication towers, etc. that carry the service and environmental loads that are imposed on them. These structural systems deteriorate over time because of natural material degradation. They can also get damaged due to excessive load demands and unknown construction deficiencies. It is necessary that condition of these structural systems is known at all times to maintain their functionality and to avoid sudden breakdowns and associated ensuing problems. This condition assessment of structural systems, now commonly known as structural health monitoring, is commonly done by visual onsite inspections manually performed at pre-decided time intervals such as on monthly and yearly basis. The length of this inspection time interval usually depends on the relative importance of the structure towards the functionality of the larger infrastructure system. This manual inspection can be highly time and resource consuming, and often ineffective in catching structural defects that are inaccessible and those that occur in between the scheduled inspection times and dates. However, the development of new sensors, new instrumentation techniques, and large data transfer and processing methods now make it possible to do this structural health monitoring on a continuous basis. The primary objective of this study is to utilize the measured dynamic or time varying strains on structural components such as beams, columns and other structural members to detect the location and level of a damage in one or more structural elements before they become serious. This detection can be done on a continuous basis by analyzing the available strain response data. This approach is expected to be especially helpful in alerting the owner of a structure by identifying the iv occurrence of a damage, if any, immediately after an unanticipated occurrence of a natural event such as a strong earthquake or a damaging wind storm.
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Mahjoub, Youssif. „Development and Integration of a Low-Cost Occupancy Monitoring System“. Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1404589/.
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The world is getting busier and more crowded each year. Due to this fact resources such as public transport, available energy, and usable space are becoming congested and require vast amounts of logistical support. As of February 2018, nearly 95% of Americans own a mobile cell phone according to the Pew Research Center. These devices are consistently broadcasting their presents to other devices. By leveraging this data to provide occupational awareness of high traffic areas such as public transit stops, buildings, etc logistic efforts can be streamline to best suit the dynamics of the population. With the rise of The Internet of Things, a scalable low-cost occupancy monitoring system can be deployed to collect this broadcasted data and present it to logistics in real time. Simple IoT devices such as the Raspberry Pi, wireless cards capable of passive monitoring, and the utilization of specialized software can provide this capability. Additionally, this combination of hardware and software can be integrated in a way to be as simple as a typical plug and play set up making system deployment quick and easy. This effort details the development and integration work done to deliver a working product acting as a foundation to build upon. Machine learning algorithms such as k-Nearest-Neighbors were also developed to estimate a mobile device's approximate location inside a building.
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Yamamoto, Kyosuke. „Bridge Damage Identification Using Vehicle Response“. 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/159406.
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Kambisseri, Roby Neelu. „Wireless communication using metasurfaces for condition monitoring in motor“. Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-246051.
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Wireless sensors are used widely for condition monitoring in electric machines. The metal enclosure of an electric motor restricts the signal from sensors to radiate outside. The signal from the metal cavity needs to be guided to the only opening in the enclosure, through a narrow gap between the stator and the rotating rotor. Gap waveguide technology is proposed as a solution by texturing the stator surface with electromagnetic band gap (EBG) structures. Arrays of periodic holey structures are used to realize the metasurface waveguide. Two Bravais lattice structures – square and hexagonal, are explored for guiding waves along a desired path in a parallel plate waveguide. Simulations are carried out to study the influence of various dimensions of the unit cells. A waveguide with hexagonal hole-type unitcell is designed and manufactured for experimental verification. The possibility of extending the same technology to cylindrical surface is confirmed by simulations.Trådlösa sensorer används allmänt för tillståndsövervakning i elektriska maskiner. Metallhöljet hos en elektrisk motor begränsar signalen från sensorerna från att stråla utåt. Signalen från metallhåligheten behöver styras till den enda öppningen i höljet, genom ett smalt mellanrum mellan statorn och den roterande rotorn. Gap-vågledarteknik föreslås som en lösning genom att strukturera statorytan med elektromagnetiska bandgap-strukturer (EBG). Arrayer av periodiskt håliga strukturer används för att realisera metayt-vågledare. Två Bravais gitterkonstruktioner –kvadratiska och sexkantiga, undersöks för styrning av vågor längs en önskad väg i en parallellplattvågledare. Simuleringar utförs för att studera påverkan av olika dimensioner hos enhetscellerna. En vågledare med hexagonal håltypsenhetscell är konstruerad och tillverkad för experimentell verifiering. Möjligheten att utvidga samma teknik till cylindrisk yta bekräftas genom simuleringar.
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Raak, Fredrik. „Investigation of Power Grid Islanding Based on Nonlinear Koopman Modes“. Thesis, KTH, Elektriska energisystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-136834.
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To view the electricity supply in our society as just sockets mountedin our walls with a constant voltage output is far from the truth. Inreality, the power system supplying the electricity or the grid, is themost complex man-made dynamical system there is. It demands severecontrol and safety measures to ensure a reliable supply of electric power.Throughout the world, incidents of widespread power grid failures havebeen continuously reported. The state where electricity delivery to customersis terminated by a disturbance is called a blackout. From a stateof seemingly stable operating conditions, the grid can fast derail intoan uncontrollable state due to cascading failures. Transmission linesbecome automatically disconnected due to power flow redirections andparts of the grid become isolated and islands are formed. An islandedsub-grid incapable of maintaining safe operation conditions experiencesa blackout. A widespread blackout is a rare, but an extremely costlyand hazardous event for society.During recent years, many methods to prevent these kinds of eventshave been suggested. Controlled islanding has been a commonly suggestedstrategy to save the entire grid or parts of the grid from a blackout.Controlled islanding is a strategy of emergency control of a powergrid, in which the grid is intentionally split into a set of islanded subgridsfor avoiding an entire collapse. The key point in the strategy is todetermine appropriate separation boundaries, i.e. the set of transmissionlines separating the grid into two or more isolated parts.The power grid exhibits highly nonlinear response in the case oflarge failures. Therefore, this thesis proposes a new controlled islandingmethod for power grids based on the nonlinear Koopman Mode Analysis(KMA). The KMA is a new analyzing technique of nonlinear dynamicsbased on the so-called Koopman operator. Based on sampled data followinga disturbance, KMA is used to identify suitable partitions of thegrid.The KMA-based islanding method is numerically investigated withtwo well-known test systems proposed by the Institute of Electrical andElectronics Engineers (IEEE). By simulations of controlled islanding inthe test system, it is demonstrated that the grid’s response following afault can be improved with the proposed method.The proposed method is compared to a method of partitioning powergrids based on spectral graph theory which captures the structural propertiesof a network. It is shown that the intrinsic structural propertiesof a grid characterized by spectral graph theory are also captured by theKMA. This is shown both by numerical simulations and a theoreticalanalysis.
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Nichols, Gilbert. „Statistical Models of I-15 Bridge C-846: Changes in Natural Frequencies due to Temperature“. DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5260.
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Structural Health monitoring is to determine the condition of a bridge based on instrument measurements. The C-846 Bridge in Salt Lake City has such instrumentation. The bridge is located in Salt Lake City at about 2100 South and Interstate 15. This bridge has two kinds of instruments on it: accelerometers and thermocouples. The accelerometers measure the vibrations of the bridge. The accelerometers have been recording data on the bridge since 2001. The thermocouples, which measure temperature, were added as part of this thesis in April 2016.
In light of recent research, damage may be detected from measuring the change in the natural frequency of a bridge, which can be obtained by manipulating the accelerometer data. However, the natural frequencies of a bridge change due to environmental effects, especially temperature. Temperature effects must be accounted for in order to better understand the damage.
The purpose of this research is not to detect damage. The bridge that is being monitored does not have any damage. The purpose of this study is to show how the dynamic properties of the C-846 Bridge in South Salt Lake City correlate with temperature. Additionally, several frequencies including the fundamental frequency of the bridge are identified.
It was found that the natural frequencies of the bridge increase with a decrease in temperature, and that the fundamental frequency of the bridge is 1.15 Hz.
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SOUTO, MAIOR Caio Bezerra. „Remainig useful life prediction via empirical mode decomposition, wavelets and support vector machine“. Universidade Federal de Pernambuco, 2017. https://repositorio.ufpe.br/handle/123456789/24930.
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The useful life time of equipment is an important variable related to reliability and maintenance. The knowledge about the useful remaining life of operation system by means of a prognostic and health monitoring could lead to competitive advantage to the corporations. There are numbers of models trying to predict the reliability’s variable behavior, such as the remaining useful life, from different types of signal (e.g. vibration signal), however several could not be realistic due to the imposed simplifications. An alternative to those models are the learning methods, used when exist many observations about the variable. A well-known method is Support Vector Machine (SVM), with the advantage that is not necessary previous knowledge about neither the function’s behavior nor the relation between input and output. In order to achieve the best SVM’s parameters, a Particle Swarm Optimization (PSO) algorithm is coupled to enhance the solution. Empirical Mode Decomposition (EMD) and Wavelets rise as two preprocessing methods seeking to improve the input data analysis. In this paper, EMD and wavelets are used coupled with PSO+SVM to predict the rolling bearing Remaining Useful Life (RUL) from a vibration signal and compare with the prediction without any preprocessing technique. As conclusion, EMD models presented accurate predictions and outperformed the other models tested.
O tempo de vida útil de um equipamento é uma importante variável relacionada à confiabilidade e à manutenção, e o conhecimento sobre o tempo útil remanescente de um sistema em operação, por meio de um monitoramento do prognóstico de saúde, pode gerar vantagens competitivas para as corporações. Existem diversos modelos utilizados na tentativa de prever o comportamento de variáveis de confiabilidade, tal como a vida útil remanescente, a partir de diferentes tipos de sinais (e.g. sinal de vibração), porém alguns podem não ser realistas, devido às simplificações impostas. Uma alternativa a esses modelos são os métodos de aprendizado, utilizados quando se dispõe de diversas observações da variável. Um conhecido método de aprendizado supervisionado é o Support Vector Machine (SVM), que gera um mapeamento de funções de entrada-saída a partir de um conjunto de treinamento. Para encontrar os melhores parâmetros do SVM, o algoritmo de Particle Swarm Optimization (PSO) é acoplado para melhorar a solução. Empirical Mode Decomposition (EMD) e Wavelets são usados como métodos pré-processamento que buscam melhorar a qualidade dos dados de entrada para PSO+SVM. Neste trabalho, EMD e Wavelets foram usadas juntamente com PSO+SVM para estimar o tempo de vida útil remanescente de rolamentos a partir de sinais de vibração. Os resultados obtidos com e sem as técnicas de pré-processamento foram comparados. Ao final, é mostrado que modelos baseados em EMD apresentaram boa acurácia e superaram o desempenho dos outros modelos testados.
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Wallace, Rick L., und Nakia J. Woodward. „Fashioning the Future: Creating More Effectively Informed Clinicians via the Implementation of an Electronic Morning Report Search Results Form“. Digital Commons @ East Tennessee State University, 2007. https://dc.etsu.edu/etsu-works/8774.
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Paget, Christophe. „Active Health Monitoring of Aerospace Composite Structures by Embedded Piezoceramic Transducers“. Doctoral thesis, KTH, Aeronautical Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3277.
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The objectives of the thesis work were to study theinteraction between embedded piezoceramic transducers andcomposite structures as well as determine techniques tosimplify the Lamb waves analysis. Firstly, this studyconsidered the design of the embedded piezoceramic transducers.Secondly, the effect of the embedded transducer on thecomposite strength as well as the influence of the mechanicallyloaded composite on the characteristics of the embeddedtransducer were investigated. Finally, to simplify the analysisof such complex Lamb wave responses, two techniques weredeveloped. They were based on the wavelet technique and amodelling technique, respectively.
The design of the embedded piezoceramic transducers wasimproved by reducing the stress concentrations in the compositeas well as in all components constituting the piezoceramictransducer, that is, the piezoceramic element, interconnectorand conductive adhesive. The numerical analysis showed that thethickness of the interconnector had no significant influence onthe stress state of the piezoceramic transducer. It was alsofound that a compliant conductive adhesive reduced the stressconcentration located at the edge of the piezoceramic element.The structural integrity of composites embedded with theimproved piezoceramic transducer was investigated. Theexperiments, performed in tensile and compressive staticloading, indicated that the strength of the composite was notsignificantly reduced by the embedded piezoceramic transducer.Further investigations were conducted to evaluate theperformance of the improved piezoceramic transducer used as aLamb wave generator embedded in composites subjected tomechanical loading. The tests were conducted in tensile andcompressive static loading as well as fatigue loading. Thestudy showed a large working range of the embedded piezoceramictransducer. A post processing technique based on the waveletswas further assessed in the detection of damage and in thedamage size evaluation. A new wavelet basis was developedspecially for processing the Lamb wave response. This method,focused on the wavelet coefficients from the decomposition Lambwave response, showed promising results in evaluating thedamage size. The wavelets offered a sensitive tool to detectsmall damage, compared to other detection methods, improvingthe damage detection capabilities. The other technique wasdevoted to the simplification of the generated Lamb waves bythe use of multi-element transducers. The transducers weredesigned using both a normal-mode expansion and a FE-method.This technique allowed reducing the effect of a Lamb wave modetowards another. This technique was successfully implemented ina damage detection system in composites.
Keywords:Embedded piezoceramic, transducer, composite,structural integrity, health monitoring, damage detection, Lambwaves, wavelets, normal-mode expansion, FE-method
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Queisser, Manuel Peter. „Quantitative monitoring of CO2 injection at Sleipner using seismic full waveform inversion in the time lapse mode and rock physics modeling“. Paris, Institut de physique du globe, 2012. http://www.theses.fr/2012GLOB0001.
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Carbon capture and sequestration is a technology to achieve a considerable deceleration of CO2 emission promptly. Since 1996 one of the largest CO2 storage projects is taking place at Sleipner in the Norwegian North Sea. In order to monitor injected CO2, time lapse surface seismic monitoring surveys have been carried out. Estimating subsurface parameters from the Sleipner seismic data is a challenging problem due to the specific geology of the storage reservoir, which is further complicated by injected CO2. Most seismic imaging methods enable only qualitative insights into the subsurface. Full waveform inversion is well known in the seismic community but not well established yet. Presented results are mostly of demonstrative character. Applying full waveform inversion as an actual tool to a complex problem such as Sleipner is novel. Motivated by the need for a quantitative seismic monitoring of the injected CO2, I have applied 2D seismic full waveform inversion to seismic data sets from Sleipner from 1994 (baseline), 1999 and 2006 along three seismic lines to infer subsurface parameters and parameter changes in the storage reservoir. The P-wave velocity is the major parameter, as it is the most sensitive to CO2 injection. An energy preconditioning of the gradient has been implemented. The usual source wavelet calibration did not prove to be reliable. An alternative source calibration has been successfully applied. By comparing seismic images with inversion results, I found that using seismic images to locate CO2 accumulations in the subsurface may be misleading. The quantitative imaging approach using full waveform inversion resulted in a consistent evolution of the model parameter with time. Major reductions in Pwave velocity and hence the CO2 accumulations could be quantitatively imaged down to a resolution of 10 m. Observed travel time shifts due to CO2 injection are comparable to those derived from the inversion result. In order to estimate CO2 saturations, rock physical concepts have been combined and extended to arrive at a rock physical formulation of the subsurface at Sleipner. I used pseudo Monte Carlo rock physics modeling to assess the influence of lithologic heterogeneity on the CO2 saturations as well as to generate pseudo well logs to estimate confidence intervals of the inverted parameters. The rock physics modeling has been used to relate inverted parameters to CO2 saturations. The injected CO2 is buoyant. The highest CO2 saturations are in the upper half of the storage reservoir but not necessarily at the top. Non-uniqueness of the saturation maps associated with the density scenario has been assessed. As a result, the distribution of the maximum saturation values remains the same. The quantity of dissolved CO2 in the reservoir water is a key parameter from both a security and optimization point of view. A quantitative estimation of dissolved CO2 by seismic means has not been undertaken yet to our knowledge. Based on the seismic inversion result of a seismic line, I found that along the line at least 20% of the injected CO2 mass was dissolved in 2006, after 10 years of injection. Such a high value indicates enhanced solubility trapping, which is very advantageous for storage safety at Sleipner. The results of this work represent a further step towards ultimate goals of quantitative monitoring, such as the estimation of the injected CO2 in-situ volume.
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Sellami, Takwa. „Contribution à l’usage de l’analyse vibratoire comme outils de monitoring et de diagnostic d’avaries pour les machines électriques tournantes“. Thesis, Cergy-Pontoise, 2017. http://www.theses.fr/2017CERG0915.
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Les capacités installées d’énergie éolienne continuent à croître rapidement et prennent une place de plus en plus significative dans le monde. Au fur et à mesure, les études menées sur la conception, la sureté de fonctionnement et la supervision de la chaîne éolienne ont pris progressivement de l’importance. Deux axes de recherche ont été privilégiés dans cette thèse. Le premier concerne la continuité de service d'une éolienne connectée au réseau en présence de défaut de court-circuit entre spires dans une phase du stator de la génératrice asynchrone à cage d'écureuil. L'analyse du défaut ainsi que son impact sur le système éolien et notamment sur la qualité de la puissance produite souligne l'intérêt de développement d'un algorithme de détection et d'isolation rapide, dédié par la suite à la reconfiguration de la commande. Ainsi, une commande tolérante au défaut (CTD) a été conçue de manière à éviter l'arrêt de la production, compenser l'impact de défaut et garder des performances acceptables de la qualité d'énergie produite. Le travail effectué s'est articulé sur les observateurs à mode glissant (OMG), communément connus comme outil puissant pour la supervision et la commande à la fois. Le deuxième axe porte sur la sécurité structurale et la stabilité du système éolien sous contraintes vibratoires. Les travaux se répartissent en deux parties complémentaires : L'établissement d'un modèle numérique tridimensionnel (3-D) sous un logiciel d’analyse par éléments finis (ANSYS) et la réalisation des essais vibratoires sous différentes excitations au sein d'une plateforme vibratoire (TREVISE). Dans ce cadre, un modèle numérique (3-D) d'une éolienne à axe horizontal couplée à un mât et une fondation adéquats a été développé en utilisant la méthode de volumes finis (FVM) afin d'appréhender son comportement vibratoire. Les essais vibratoires expérimentaux valident le modèle numérique et permettent l’identification de la réponse dynamique de la structure d'une manière fine. De plus, nous avons élaboré un modèle expérimental de la tenue de l’éolienne aux contraintes vibratoires de formes aléatoire, sinusoïdale et impulsionnelleThe wind energy capacity carries on growing quickly and taking an increasingly significant place in the world. Progressively, research studies dealing with designing and supervising wind turbines have become more important. Two areas of research were developed in this thesis. The first one concerns the continuity of service of a wind turbine connected to the grid while an inter-turn short-circuit fault is present in the stator phase of the induction squirrel cage generator. The analysis of the fault as well as its impact on the wind turbine system and mainly on the quality of the produced power highlights the interest of development of a fast detection and isolation algorithm, dedicated to the reconfiguration of the control law. Hence, a fault tolerant control scheme has been established in order to avoid stopping production, compensate the fault impact and maintain acceptable performances of the quality of the produced energy. The carried out work was based on sliding mode observers, commonly known as robust tools for monitoring and controlling at the same time. The second axis concerns the structural modeling and stability checking of the wind system under vibratory stresses. The work is divided into two complementary parts: The establishment of a three-dimensional (3-D) numerical model using a finite element analysis software (ANSYS) and the realization of vibratory tests under different excitations within the platform (TREVISE). In this framework, a numerical (3-D) model of a horizontal axis wind turbine coupled to a suitable tower and foundation was developed basing on the finite volume method (FVM) in order to analyze its vibratory behavior. The experimental vibratory tests validate the numerical model and allow the identification of the dynamic response of the structure in a precise way. In addition, we have developed an experimental model of the behavior of the wind turbine under vibratory stresses of random, sinusoidal and impulse shapes
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KEHLENBACH, JOSUA. „Fault diagnosis of axlebox roller bearings of high speed rail vehicles based on empirical mode decomposition and machine learning“. Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299774.
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Axlebox bearings are one of the most critical components of a rail vehicle with regard to safety. An axlebox bearing that breaks during operation can be dangerous for the passengers and expensive for the operator. In-service failure of axlebox bearings has been the cause of many catastrophic accidents. Thus, it is of utmost importance to predict bearing failures as early as possible. This will increase reliability and safety of the vehicle as well as reduce the vehicle maintenance cost. Monitoring of roller bearings is an active research eld, and many methods have been proposed by other researchers. Many of these methods employ complex algorithms to make the most use of the given measurements. The algorithms often lack interpretability and have high computational costs, making them dicult to employ in an on-board system. This thesis proposes an interpretable and transparent algorithm that predicts bearing damages with high accuracy. Meanwhile, it tries to retain interpretability as much as possible. The algorithm is based on Empirical Mode Decomposition (EMD) and Singular Value Decomposition (SVD). These two techniques extract essential and meaningful information from the axlebox accelerations. The algorithm is benchmarked on two benchmark datasets, and the results are compared to the respective literature. Then the algorithm is employed on the railway axlebox acceleration measurements that were taken on an axlebox test bench available at SWJTU. The proposed algorithm can be extended to incorporate additional measurements of dierent types, e.g. sound or temperature measurements. The incorporation of other types of measurements will improve the performance of the algorithm even further.Axelbox lager är en av de viktigaste komponenterna i ett järnvägsfordon när det berör säkerheten. Ett axelbox lager som havererar under drift kan vara farligt for passagerarna och även dyrt för operatören. Driftfel av lagren har varit orsaken till många katastrofala olyckor. Därför är det av yttersta vikt att förutsäga lagerfel så tidigt som möjligt. Detta ökar fordonets tillförlitlighet och säkerhet samt minskar underhållskostnaderna. Mycket forskning har utförts inom övervakning av rullager. Många metoder använder komplexa algoritmer för att maximalt utnyttja matningarna. Algoritmerna saknar ofta tolkbarhet och har höga beräkningskostnader, vilket gör dem svåra att använda i ett integrerat system. Denna avhandling kombinerar era metoder för databehandling och maskininlärning till en algoritm som kan förutsäga lagerskador med hög precision, samtidigt som tolkningsförmågan bibehalls. Bland andra välkända metoder sa använder algoritmen Empirical Mode Decomposition (EMD) och Singular Value Decomposition (SVD) för att extrahera väsentlig information for vibrationsmätningarna. Algoritmen testas sedan med tre olika vibrationsdatamängder, varav en mättes specikt med tanke på simulering av axelbox lager. Ett annat mål med algoritmen är att göra den tillämpad för ytterligare mätningar. Det bör vara möjligt att inkludera mätningar av olika slag, dvs ljud- eller temperaturmätningar, och därigenom förbättra resultaten. Detta skulle minska implementeringskostnaden avsevärt eftersom befintliga sensorer används för detta ändamål. I händelsen av att de föreslagna metoderna inte fungerar med nya mätningar är det även möjligt att integrera ytterligare funktioner i algoritmen.
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Klintenberg, Patrik. „More Water, Less Grass? : An assessment of resource degradation and stakeholders’ perceptions of environmental change in Ombuga Grassland, Northern Namibia“. Doctoral thesis, Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6707.
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Eriksson, Matts, und Jonas Lundmark. „Technical Verification and Validation of ADS-B/VDL Mode 4 for A-SMGCS“. Thesis, Linköping University, Department of Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1417.
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This report is a technical verification and validation of ADS-B (Automatic Dependent Surveillance – Broadcast) over VDL Mode 4 (Very High Frequency Data Link Mode 4) for the use in the surveillance element of an A-SMGCS (Advanced Surface Movement Guidance and Control System).
The main objective of this report is to examine if ADS-B/VDL Mode 4 fulfils the technical requirements for an implementation at Arlanda airport, Stockholm Sweden. The report also includes a FMECA (Failure Mode, Effects and Criticality Analysis), a theoretical background and methods for monitoring.
The process of making this report can be divided into three phases:
1. Preliminary Study. In this phase the requirements were examined and structured.
2. Verification. In this phase the system performance has been verified both theoretically and by several tests at Arlanda Airport. Simulation results have also been used.
3. Validation and documentation. The tests and verifications that were performed in phase 2 were validated in the third phase of the project. The final project document was also written in this phase.
The main conclusion from this analysis is that ADS-B/VDL Mode 4 is well suited for surveillance. ADS-B/VDL Mode 4 has the possibility to fulfil all considered requirements, apart from detecting all obstacles. But if all the requirements are going to be fulfilled depends both on the implementation and the operational environment.
The results from this verification and validation should be used as the technical subset in a future safety case, both in Sweden and internationally.
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Yagüe, Martínez Néstor [Verfasser], Michael [Akademischer Betreuer] Eineder, Alberto [Gutachter] Moreira, Andrew [Gutachter] Hooper, Richard H. G. [Gutachter] Bamler und Michael [Gutachter] Eineder. „Burst-Mode Wide-Swath SAR Interferometry for Solid Earth Monitoring / Néstor Yagüe Martínez ; Gutachter: Alberto Moreira, Andrew Hooper, Richard H. G. Bamler, Michael Eineder ; Betreuer: Michael Eineder“. München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1202922724/34.
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Taquet, Noémie. „Monitoring géochimique de la géosphère et l'atmosphère : application au stockage géologique du CO2“. Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0252/document.
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Cette thèse touche à la problématique des échanges de gaz aux interfaces entre la géosphère, la biosphère, l'hydrosphère et l'atmosphère par l'intermédiaire du monitoring géochimique des gaz appliqué aux sites de stockage géologiques du CO2. Au niveau de l'axe « Métrologie », nous avons développé une plate-forme de monitoring géochimique continu, in situ et déportée par spectrométrie FTIR/Raman pour la mesure des gaz du sol (CO2, CH4, N2, O2, H2O). Des protocoles de quantification ont été développés pour la mesure par télédétection infrarouge terrestre en mode passif du CO2, CH4, SO2, H2S dans l'atmosphère. Au niveau des axes « Monitoring » et « Modélisation », les mesures de gaz du sol à proximité du puits d'injection de Rousse (Pilote CO2 Total, Lacq/Rousse, France) sur plus de sept cycles saisonniers ont montré une anti-corrélation entre la teneur en CO2 et les variations du niveau piézométrique de la nappe. Cette relation a permis de modéliser l'enveloppe de variabilité « naturelle » de la teneur en CO2 dans le sol, qui constitue un élément clé pour la surveillance des sites de stockage. Les variations majeures de teneur en CO2 sont attribuées à des processus de dissolution/libération de CO2 par la nappe, jouant un rôle de pompe à CO2. La concentration en CO2 en surface (+1m) serait gouvernée par les variations de teneur en CO2 du sol. Les mesures par télédétection FTIR des gaz dans l'atmosphère ont permis d'établir pour la première fois une simulation expérimentale 3D des enveloppes de CO2 à l'aplomb du site d'injection. Ces résultats constituent un premier pas vers la mise en place d'un outil de surveillance des panaches gazeux dans l'atmosphèreThis study is based on the problematic of gas exchanges at the interface between the geosphere, biosphere, hydrosphere and atmosphere through the geochemical monitoring of gas applied to CO2 geological storage sites. Concerning the "Metrological" aspect, we developed and implemented an in situ continuous geochemical monitoring station, based on coupling FTIR/ Raman spectrometry for measuring soil gas (O2, N2, CO2, CH4 and H2O) close to the injection wells of Rousse 1 (CCS Total pilot, Lacq-Rousse, France). We also developed protocols to identify and quantify CO2, CH4, SO2, H2S in the atmosphere (plume) by passive remote sensing FTIR. On the "Monitoring" and "Modelling" aspects, the continuous recording of soil CO2 concentration during more than 7 seasonal cycles indicate that CO2 concentration in the soil was anti-correlated with changes in piezometric level of the groundwater. This correlation was used to model the limits of natural variability of CO2 content in the soil, which is a key to CCS sites monitoring. The main fluctuations in soil CO2 content was assigned to a dissolution/release process of CO2 by the perched water table, acting as a CO2 pump. The CO2 concentration at the near surface (+ 1 m) would be governed by changes of the soil CO2 content. FITR remote sensing measurement of atmospheric gases allowed for the first time to perform an experimental 3D simulation of CO2 layers on the injection site. This type of experimental simulation is a first step for the monitoring of gases in the atmosphere
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Piccioni, Flavio. „Numerical Evaluation of Mode II Disbonding on Fiberglass CCPs-Specimens and Material Characterization Utilizing a Distributed Sensing Rayleigh Backscattering System“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/19848/.
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Nowadays, composite materials have become the main construction materials for aeronautical structures, replacing traditional materials commonly used in this industry. However, composite structures are still characterized by conservative designs due to the lack of understanding from a physics-based approach their damage propagation and failure mechanisms. Since repairs of composite structures are a crucial part of the long-term use of composites in aerospace, the stakeholders require an in depth understanding of the physics of disbonding in composites. The aim of this research is a numerical evaluation of mode II disbonding on Center Cut Plies (CCPs) specimens with a preliminary study on material characterization performed through a Distributed Sensing System (DSS). In order to fulfill the objectives of this research, CCPs specimens manufactured from unidirectional fiber prepregs will be considered. The specimens will be produced from unidirectional prepregs in order to minimize the effects of residual stress fields introduced into the specimen during the curing process. That residual stress field will be evaluated and monitored making use of a Distributed Sensing System (DSS) optical fiber mounted and embedded within the laminas of the specimen. In addition, an analytical and numerical approach through FEM analysis will be adopted and validated to verify the experimental results obtained from the DSS.
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Yazdanpanah, Moghadam Peyman. „Optimisation de transducteurs piézoélectriques pour la génération d'ondes guidées“. Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/8172.
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Résumé : Les systèmes de surveillance de santé structurale sont proposés pour la détection d’endommagement dans les infrastructures qui dépassent leur durée de vie en utilisant les ondes guidées (GW). Les ondes guidées peuvent parcourir de longues distances et sont sensibles à une variété d’imperfections. Les transducteurs piézoélectriques sont communément utilisés pour générer et mesurer les ondes guidées dans des structures minces. Comme la détection du défaut et sa localisation sont souhaitées, la nature de la génération des ondes guidées sous forme de plusieurs modes implique une complexité supérieure dans le traitement du signal. Pour remédier à cette limitation, une nouvelle méthode est présentée ici pour la génération des ondes guidées par sélection de mode, et un nouveau transducteur piézoélectrique est ensuite conçu, fabriqué et testé.
Tout d'abord, la génération des ondes guidées par optimisation systématique du profil interfacial de la contrainte de cisaillement en mode sélectif est étudiée. En utilisant le principe de superposition, une méthode d'analyse est d'abord développée pour la modélisation de la génération des ondes guidées par un nombre fini de segments de contrainte de cisaillement uniforme, chacun contribuant à un profil élémentaire d’une contrainte constante de cisaillement. Sur cette base, deux fonctions coût sont définies afin de minimiser les modes indésirables et amplifier le mode sélectionné et le problème d'optimisation est résolu avec un cadre d'optimisation d’algorithme génétique parallèle. Les avantages de cette méthode par rapport à d'autres approches de conception de transducteurs classiques sont (1) la contrainte de cisaillement peut être explicitement optimisée à la fois pour exciter un mode et supprimer d'autres modes indésirables, (2) la taille de la zone d'excitation n’est pas limitée et l’excitation en mode sélectif est toujours possible, même si la largeur d'excitation est inférieure à toutes les longueurs d'onde excitées, et (3) la sélectivité est accrue et la largeur de bande est étendue.
La méthode analytique et les fonctions coût sont ensuite développées pour concevoir un transducteur piézoélectrique à éléments multiples (MEPT) simple et performant. Une méthode numérique est tout d'abord mise au point pour extraire la contrainte interfaciale entre un seul élément piézocéramique et une structure d'accueil et ensuite utilisée comme entrée d'un modèle analytique pour prédire la propagation des ondes guidées à travers l'épaisseur d'une plaque isotrope. Deux nouvelles fonctions coût sont proposées pour optimiser la contrainte de cisaillement interfaciale pour supprimer le(s) mode(s) indésirable(s) et maximiser un mode désiré. Simplicité et faible coût de fabrication sont deux principales cibles visées dan la conception du MEPT. Un prototype TPEM est ensuite fabriqué à l'aide de micro-usinage laser. Une procédure expérimentale est présentée afin de valider les performances de la TPEM comme une nouvelle solution pour la génération des ondes guidées en mode sélectif. Des essais expérimentaux illustrent la forte capacité du TPEM pour la génération des ondes guidées en mode sélectif, puisque le mode indésirable est supprimé par un facteur allant jusqu'à 170 fois par rapport aux résultats obtenus avec un seul piézocéramique.Abstract : Structural Health Monitoring (SHM) systems are being proposed for damage detection of infrastructures that exceed their life using ultrasonic Guided waves (GWs). GWs can travel over long distances and are sensitive to variety of defects. Piezoelectric transducers (PZTs) are commonly used to generate and measure GWs in plate-like structures. As damage detection and localization is sought, the multi-mode nature of GW generation involves higher complexity in signal processing. To overcome this limitation, a new method is presented here for modeselective GW generation, and a novel mode-selective PZT is then designed, manufactured and tested. First, mode-selective generation of GWs by systematic optimization of the interfacial shear stress profile is investigated. Using the superposition principle, an analytical method is first developed for modeling GWs generation by a finite number of uniform shear stress segments, each contributing with a constant elementary shear stress profile. Based on this, two cost functions are defined in order to minimize the undesired modes and amplify the selected mode and the optimization problem is solved with a parallel Genetic Algorithm (GA) optimization framework. Advantages of this method over more conventional transducers tuning approaches are that (1) the shear stress can be explicitly optimized to both excite one mode and suppress other undesired modes, (2) the size of the excitation area is not constrained and mode-selective excitation is still possible even if excitation width is smaller than all excited wavelengths, and (3) the selectivity is increased and the bandwidth extended. The analytical method and objective functions are then developed to design a novel and costeffective multi-element piezoelectric transducer (MEPT). A numerical method is first developed to extract the interfacial stress between a single piezoceramic element and a host structure and then used as the input of an analytical model to predict the GW propagation through the thickness of an isotropic plate. Two novel objective functions are proposed to optimize the interfacial shear stress for both suppressing unwanted mode(s) and maximizing a desired mode. Simplicity and low manufacturing cost are two main targets driving the design of the MEPT. A prototype MEPT is then manufactured using laser micro-machining. An experimental procedure is presented to validate the performances of the MEPT as a new solution for mode-selective GW generation. Experimental tests illustrate the high capability of the MEPT for mode-selective GW generation, as unwanted mode is suppressed by a factor up to 170 times compared with the results obtained with a single piezoceramic.
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Dixit, Akash. „Damage modeling and damage detection for structures using a perturbation method“. Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43575.
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This thesis is about using structural-dynamics based methods to address the existing challenges in the field of Structural Health Monitoring (SHM). Particularly, new structural-dynamics based methods are presented, to model areas of damage, to do damage diagnosis and to estimate and predict the sensitivity of structural vibration properties like natural frequencies to the presence of damage.
Towards these objectives, a general analytical procedure, which yields nth-order expressions governing mode shapes and natural frequencies and for damaged elastic structures such as rods, beams, plates and shells of any shape is presented. Features of the procedure include the following:
1. Rather than modeling the damage as a fictitious elastic element or localized or global change in constitutive properties, it is modeled in a mathematically rigorous manner as a geometric discontinuity.
2. The inertia effect (kinetic energy), which, unlike the stiffness effect (strain energy), of the damage has been neglected by researchers, is included in it.
3. The framework is generic and is applicable to wide variety of engineering structures of different shapes with arbitrary boundary conditions which constitute self adjoint systems and also to a wide variety of damage profiles and even multiple areas of damage.
To illustrate the ability of the procedure to effectively model the damage, it is applied to beams using Euler-Bernoulli and Timoshenko theories and to plates using Kirchhoff's theory, supported on different types of boundary conditions. Analytical results are compared with experiments using piezoelectric actuators and non-contact Laser-Doppler Vibrometer sensors.
Next, the step of damage diagnosis is approached. Damage diagnosis is done using two methodologies. One, the modes and natural frequencies that are determined are used to formulate analytical expressions for a strain energy based damage index. Two, a new damage detection parameter are identified.
Assuming the damaged structure to be a linear system, the response is expressed as the summation of the responses of the corresponding undamaged structure and the response (negative response) of the damage alone. If the second part of the response is isolated, it forms what can be regarded as the damage signature. The damage signature gives a clear indication of the damage. In this thesis, the existence of the damage signature is investigated when the damaged structure is excited at one of its natural frequencies and therefore it is called ``partial mode contribution". The second damage detection method is based on this new physical parameter as determined using the partial mode contribution. The physical reasoning is verified analytically, thereupon it is verified using finite element models and experiments. The limits of damage size that can be determined using the method are also investigated. There is no requirement of having a baseline data with this damage detection method. Since the partial mode contribution is a local parameter, it is thus very sensitive to the presence of damage. The parameter is also shown to be not affected by noise in the detection ambience.
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Maric, Danilo. „Firmware development of a User Interface on medical devices of DIMA ITALIA Srl“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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This dissertation was written based on an internship experience at Dima Italia Srl, a leader in designing, production and marketing of medical ventilators. Once these ventilators were simple machines for breathing support, manually pumping the air in and out. Today, medical ventilators are computerized machines, electronically controlled by a small embedded system. They feature a plethora of available modes and an easy-to-use graphical interface. Exactly this is the topic of the thesis: developing a firmware with graphical interface for the next ventilator, produced and sold by Dima Italia. The firmware is based on C++ language and was developed in a Qt Creator framework, ideal for developing applications with graphical interfaces on Linux-based devices. In the paper are found all the pages of the firmware, along with the logic of operation of the application. Moreover, all the details about the operation and modes of a medical ventilator are also found in the document. In the end, there's a section related to deployment of a Qt application on a device, along with the issues and bugs encountered during the development process.
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Zimmer, Christoph Thomas [Verfasser], und P. W. [Akademischer Betreuer] Zebitz. „Monitoring, mechanisms and management of insecticide resistance and insecticide mode of action in coleopteran pests of winter oilseed rape with special reference to neonicotinoid insecticides under laboratory and applied aspects / Christoph Thomas Zimmer. Betreuer: P.W. Zebitz“. Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2015. http://d-nb.info/1067485406/34.
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Menday, M. T. „Multi-body dynamics analysis and experimental investigations for the determination of the physics of drive train vibro-impact induced elasto-acoustic coupling“. Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/20789.
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A very short and disagreeable audible and tactile response from a vehicle driveline may be excited when the throttle is abruptly applied or released, or when the clutch is rapidly engaged. The condition is most noticeable in low gear and in slow moving traffic, when other background engine and road noise levels are low. This phenomenon is known as clonk and is often associated with the first cycle of shuffle response, which is a low frequency longitudinal vehicle movement excited by throttle demand. It is often reported that clonk may coincide with each cycle of the shuffle response, and multiple clonks may then occur. The problem is aggravated by backlash and wear in the drivetrain, and it conveys a perception of low quality to the customer. Hitherto, reported investigations do not reveal or discuss the mechanism and causal factors of clonk in a quantitative manner, which would relate the engine impulsive torque to the elastic response of the driveline components, and in particular to the noise radiating surfaces. Crucially, neither have the issues of sensitivity, variability and non-linearity been addressed and published. It is also of fundamental importance that clonk is seen as a total system response to impulsive torque, in the presence of distributed lash at the vibro-elastic impact sites. In this thesis, the drivetrain is defined as the torque path from the engine flywheel to the road wheels. The drivetrain is a lightly damped and highly non-linear dynamic system. There are many impact and noise emitting locations in the driveline that contribute to clonk, when the system is subjected to shock torque loading. This thesis examines the clonk energy paths, from the initial impact to many driveline lash locations, and to the various noise radiating surfaces. Both experimental and theoretical methods are applied to this complex system. Structural and acoustic dynamics are considered, as well as the very important frequency couplings between elastic structures and acoustic volumes. Preliminary road tests had indicated that the clonk phenomenon was a, very short transient impact event between lubricated contacts and having a high frequency characteristic. This indicated that a multi-body dynamics simulation of the driveline, in conjunction with a high frequency elasto-acoustic coupling analysis, would be required. In addition, advanced methods of signal analysis would be required to handle the frequency content of the very short clonk time histories. These are the main novelties of this thesis. There were many successful outcomes from the investigation, including quantitative agreement between the numerical and experimental investigations. From the experimental work, it was established that vehicle clonk could be accurately reproduced on a driveline rig and also on a vehicle chassis dynamometer, under controlled test conditions. It then enabled Design of Experiments to be conducted and the principal causal factors to be identified. The experimental input and output data was also used to verify the mathematical simulation. The high frequency FE analysis of the structures and acoustic cavities were used to predict the dynamic modal response to a shock input. The excellent correlation between model and empirical data that was achieved, clearly established the clonk mechanism in mathematical physics terms. Localised impact of meshing gears under impulsive loads were found to be responsible for high frequency structural wave propagation, some of which coupled with the acoustics modes of cavities, when the speed of wave propagation reached supersonic levels. This finding, although previously surmised, has been shown in the thesis and constitutes a major contribution to knowledge.
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Shih, Hoi Wai. „Damage assessment in structures using vibration characteristics“. Queensland University of Technology, 2009. http://eprints.qut.edu.au/30319/.
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Changes in load characteristics, deterioration with age, environmental influences and random actions may cause local or global damage in structures, especially in bridges, which are designed for long life spans. Continuous health monitoring of structures will enable the early identification of distress and allow appropriate retrofitting in order to avoid failure or collapse of the structures. In recent times, structural health monitoring (SHM) has attracted much attention in both research and development. Local and global methods of damage assessment using the monitored information are an integral part of SHM techniques. In the local case, the assessment of the state of a structure is done either by direct visual inspection or using experimental techniques such as acoustic emission, ultrasonic, magnetic particle inspection, radiography and eddy current. A characteristic of all these techniques is that their application requires a prior localization of the damaged zones. The limitations of the local methodologies can be overcome by using vibration-based methods, which give a global damage assessment. The vibration-based damage detection methods use measured changes in dynamic characteristics to evaluate changes in physical properties that may indicate structural damage or degradation. The basic idea is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Changes in the physical properties will therefore cause changes in the modal properties. Any reduction in structural stiffness and increase in damping in the structure may indicate structural damage. This research uses the variations in vibration parameters to develop a multi-criteria method for damage assessment. It incorporates the changes in natural frequencies, modal flexibility and modal strain energy to locate damage in the main load bearing elements in bridge structures such as beams, slabs and trusses and simple bridges involving these elements. Dynamic computer simulation techniques are used to develop and apply the multi-criteria procedure under different damage scenarios. The effectiveness of the procedure is demonstrated through numerical examples. Results show that the proposed method incorporating modal flexibility and modal strain energy changes is competent in damage assessment in the structures treated herein.
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Ramli, Nur Ilyani Binti. „Design and development of a low cost heart best monitor device using finger photoplethysmography technique :|bcircuit design and fabrication of a non-invasive heart beat monitoring device that employs reflectance and transmission mode photoplethysmography using parallel port interface and microcontroller PIC16F84A“. Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/7291.
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A low cost Heart Beat Monitoring device (HBMD) for detecting heart beat in beats per minute is presented in this thesis. An optical technique called “Photoplethysmography” is utilized by attaching to the base of the finger for monitoring beat to beat pulsation. Two major design issues addressed in this research is to achieve a strong and accurate PPG signal and simultaneously minimizing physiological artefacts and interference. In order to achieve the aim and objectives of the research, this thesis thoroughly explores two new signal conditioning hardware designs. Firstly is the design and fabrication of a low cost reflectance mode PPG heart monitor using parallel port interfacing and secondly are the design and development of a portable transmission mode PPG heart monitor using microcontroller PIC16F84A and PIC16F87. Both PPG heart monitor design is divided into three phases. First is the detection of weak pulses through the fingertip. The PPG signal is then amplified, filtered and digitized by the signal processing unit. Finally the heart rate is calculated, analyzed and displayed on the computer using parallel port interface and on the liquid crystal display using microcontroller PIC16F87. A comprehensive circuit design and analysis work was implemented verified by Proteus VSM circuit simulations and laboratory experiments. Data is presented from the method comparison study in which heart rates measured with the reflectance mode PPG and portable transmission mode PPG heart monitor were compared with those measured with standard techniques on 13 human subjects. Benchmarking tests with approved pulse oximeter and blood pressure monitor Omron M6 reveals that the PPG heart monitor is comparable to those devices in displaying the heart rate. It is also verified through experiments that both PPG heart monitor design fulfill the objectives, including achieving strong and accurate PPG signal, reduction in physiological artefacts and interference and financially low in cost. As the conclusion, the current version of the reflectance mode PPG and portable transmission mode PPG heart monitor successfully measure heart rates fast and reliably in most subjects in different body position. The PPG heart monitor proposed avoid the need to apply electrodes or other sensors in the correct position which directly minimizes the preparation time drastically. This makes the PPG heart monitor more attractive for heart monitoring purpose and its advantage should be explored further.Ministry of Higher Education Malaysia (MOHE) and Universiti Tun Hussein Onn Malaysia (UTHM)
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Ramli, Nur Ilyani Binti. „Design and development of a low cost heart best monitor device using finger photoplethysmography technique : circuit design and fabrication of a non-invasive heart beat monitoring device that employs reflectance and transmission mode photoplethysmography using parallel port interface and microcontroller PIC16F84A“. Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/7291.
Der volle Inhalt der QuelleAnnotation:
A low cost Heart Beat Monitoring device (HBMD) for detecting heart beat in beats per minute is presented in this thesis. An optical technique called “Photoplethysmography” is utilized by attaching to the base of the finger for monitoring beat to beat pulsation. Two major design issues addressed in this research is to achieve a strong and accurate PPG signal and simultaneously minimizing physiological artefacts and interference. In order to achieve the aim and objectives of the research, this thesis thoroughly explores two new signal conditioning hardware designs. Firstly is the design and fabrication of a low cost reflectance mode PPG heart monitor using parallel port interfacing and secondly are the design and development of a portable transmission mode PPG heart monitor using microcontroller PIC16F84A and PIC16F87. Both PPG heart monitor design is divided into three phases. First is the detection of weak pulses through the fingertip. The PPG signal is then amplified, filtered and digitized by the signal processing unit. Finally the heart rate is calculated, analyzed and displayed on the computer using parallel port interface and on the liquid crystal display using microcontroller PIC16F87. A comprehensive circuit design and analysis work was implemented verified by Proteus VSM circuit simulations and laboratory experiments. Data is presented from the method comparison study in which heart rates measured with the reflectance mode PPG and portable transmission mode PPG heart monitor were compared with those measured with standard techniques on 13 human subjects. Benchmarking tests with approved pulse oximeter and blood pressure monitor Omron M6 reveals that the PPG heart monitor is comparable to those devices in displaying the heart rate. It is also verified through experiments that both PPG heart monitor design fulfill the objectives, including achieving strong and accurate PPG signal, reduction in physiological artefacts and interference and financially low in cost. As the conclusion, the current version of the reflectance mode PPG and portable transmission mode PPG heart monitor successfully measure heart rates fast and reliably in most subjects in different body position. The PPG heart monitor proposed avoid the need to apply electrodes or other sensors in the correct position which directly minimizes the preparation time drastically. This makes the PPG heart monitor more attractive for heart monitoring purpose and its advantage should be explored further.