Дисертації: "Mechanical diagnosis"

1

Flepp, Beat. "Wear diagnosis of mechanical seals with neural networks /." Zürich, 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13171.

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2

May, Stephen J. "Development of aspects of mechanical diagnosis and therapy." Thesis, Sheffield Hallam University, 2009. http://shura.shu.ac.uk/20757/.

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Mechanical Diagnosis and Therapy is a system of classification, assessment and management applied to all musculoskeletal problems that is used by clinicians worldwide. The first section concerns the up-dating and contextualising of Mechanical Diagnosis and Therapy (MDT). The books, co-authored with the founder of MDT, Robin McKenzie, applied the principles to extremity musculoskeletal problems, and then set MDT in the contemporary evidence-based background for lumbar, cervical and thoracic problems. This involved an up-dating of the classification system, as well as synthesis and analysis of aspects of musculoskeletal medicine. The second section presents a patient perspective on musculoskeletal problems. This involves an exploration of patient opinions about back pain and its management, and an audit of outcomes in a clinical setting in which an active exercise-based treatment approach was applied. The third section relates to a number of publications that sought to validate aspects of MDT. Centralisation is a key finding during the assessment of spinal patients and work on this included a systematic review of the relevant literature and an analysis of centralisation in patients with sciatica. In another study we conducted a secondary analysis of a published trial to see what happened if patients were crossed-over from exercises that were unmatched with directional preference to matched exercises. We published a case-control study that validates the postural syndrome and measured the prevalence rates of MDT classifications in the patient population. Reliability is a keycomponent of any musculoskeletal assessment system in which clinicians are making management decisions based on physical examination procedures - a systematic review that detailed the reliability of MDT compared to other commonly used examination procedures was an important contribution to the literature. Overall these works have led to a significant independent and original contribution to knowledge and understanding of MDT.

3

Calis, Hakan. "Current based detection of mechanical faults in induction motors." Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300597.

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4

Mao, Wenshu 1971. "Qualitative model-based fault diagnosis : applied to extrusion blow molding." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80129.

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This thesis develops the concept of qualitative model-based fault diagnosis technique and applies it to extrusion blow molding. The extrusion blow molding process is reviewed along with theories of qualitative reasoning, from which process-based qualitative models are developed. Based on the models, a fault diagnosis system is developed consisting of two parts: a fault reasoning system based on a simulation of the EBM process and a process monitor to measure process variables and to adapt the diagnosis to changing environments.

5

Wortman, Tyler David. "LesionAir : a low-cost tool for automated skin cancer diagnosis and mapping." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104499.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 235-252).
Skin cancer is the most common form of cancer in the United States; one out of every five Americans develops skin cancer at some point in their lifetime. Diagnosing cancerous lesions early is critical as it significantly increases the chance of survival. However, current techniques for diagnosing skin cancer lack specificity and sensitivity, resulting in many unnecessary biopsies and missed diagnoses. Although some researchers have increased diagnostic efficacy by quantitatively diagnosing skin cancer in an automated fashion, these methods require extremely bulky, expensive, and complicated equipment. This thesis presents the design and testing of LesionAir, a small, low-cost skin cancer diagnostic tool that measures the full-field compliance of the skin - which is well known to correlate strongly with skin cancer - by applying a vacuum force to the tissue and measuring precise deflection using structured light 3D reconstruction. Image processing algorithms determine additional morphological information about the potentially cancerous lesion. A pilot study of ten patients with suspect lesions validated LesionAir's effectiveness. After biopsy and analysis, a dermatopathologist confirmed the diagnosis of skin cancer in tissue that LesionAir identified as noticeably stiffer, and the regions of this stiffened tissue aligned nearly perfectly with the bounds established by the histological tests, which showed the method determines the precise coordinates that must be excised to safely remove all cancerous tissue. This technology can thus enable patients, primary care physicians, and dermatologists to rapidly identify and diagnose skin cancer with diagnostic quality not seen before from any equipment in this class.
by Tyler David Wortman.
Ph. D.

6

Balden, Victor. "The identification of structural modal parameters, as an alternative in-vivo diagnosis for osteoporosis." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9503.

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Includes bibliographies.
An alternative non-invasive diagnostic technique was sought for the diagnosis of osteoporosis in human subjects. The tibia vibration technique was proposed after reviewing the literature on detection techniques for osteoporosis. The basis of diagnosis of the tibia vibration technique is the measured resonant frequency of the patient's tibia. The patient's tibia is excited, generally by means of an impact hammer, while the response is captured and resonant frequencies extracted. This dissertation does not attempt to measure the resonant frequencies of a human tibia, but rather develop and validate the required experimental protocol and system identification procedures, on a simple test structure. A theoretical finite element model of the test structure was developed to ensure that both the experimental protocol and system identification procedures provided accurate results. The impulse response technique was adopted to excite the test structure.

7

Zhongyi, Cai. "Vibration diagnosis of elastic shafts with a transverse crack." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/405.

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Detection of the shaft crack in a rotating machine is one of the most challenging problems in equipment predictive maintenance. In the available literature, various crack detection methods have been applied to study the dynamic behaviour of a cracked shaft. This study sought to attempt a vibration-based method. Elastic shafts with three different types of transverse cracks, including experimentally-induced fatigue crack, welded shaft crack, and wire-cut crack, were fabricated, and used to analyse the bending stiffness and frequency response in the vertical direction. The results from the cracked shafts were compared with that of an intact shaft. Bending stiffness of different shafts was measured as a function of rotation angle of the shafts. Among the three different crack types, the bending stiffness of the fatigue crack shaft showed a typical breathing behaviour, which was consistent with the previous theoretical results. The welded shaft crack also demonstrated opening and closing characteristics, but the stiffness was found to be much lower compared with that of a fatigue cracked shaft. As for the wire-cut crack, no breathing mechanism was observed for any rotational angle, due to the big width of the gap. Therefore, it is concluded that the fatigue induced crack is the most accurate method to evaluate the vibration characteristics of cracked shafts. Our results also indicated that existing switching model and harmonic models cannot describe the periodic stiffness of a transverse shaft crack accurately. Modal analysis was carried out on the intact shaft, as well as the three types of cracked shafts. Frequency responses in the X-axis direction were obtained. The correlation between the bending stiffness and the resonant frequency was examined, and it was experimentally proved that the decrease in resonant frequency was almost proportional to the reduction in the stiffness. Also, the amplitude of vibration response was found to be amplified by the crack element. The cause and implications of these results were analysed, and they are expected to deepen our understanding of crack diagnosis using vibration method.

8

Dellah, Aaron Scott. "Noninvasive diagnosis of acute compartment syndromes using ultrasound and mechanical vibration, feasibility study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/MQ36021.pdf.

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9

CHAO, YUE. "Fault Detection and Diagnosis of Electro-Mechanical Systems Based on Real-time Data." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1215092937.

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10

Pastras, Christopher John. "Assessment of Utricular Nerve, Hair Cell and Mechanical Function, in vivo." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20075.

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Vestibular research currently relies on single response measures such as ex vivo hair cell and in vivo single unit recordings. Although these methods allow detailed insight into the response properties of individual vestibular hair cells and neurons, they do not provide a holistic understanding of peripheral vestibular functioning and its relationship to vestibular pathology in a living system. For this to take place, in vivo recordings of peripheral vestibular nerve, hair cell and mechanical function are needed. The previous inability to record vestibular hair cell responses stemmed from a difficulty in accessing the vestibular end-organs and stimulating them in isolation of the cochlea. To circumvent this, we developed a ventral surgical approach, removing the cochlea, to provide full access to the basal surface of the utricular macula. This allowed functional and mechanical utricular hair cell recordings, alongside gross utricular nerve responses. Recordings were performed in anaesthetized guinea pigs using Bone Conducted Vibration (BCV) and Air Conducted Sound (ACS) stimuli, providing a clinical link to vestibular reflex testing. We have thus far performed experiments involving: 1) Selective manipulation of vestibular nerve function, using electrical stimulation of the central vestibular system. 2) Glass micropipette recordings from the basal surface of the macular epithelium, which provided a robust and localized measure of extracellular utricular hair cell function. 3) With the macular exposed, we have measured the dynamic motion of the macula using Laser Doppler Vibrometry, which was recorded alongside the hair cell and nerve response recordings. 4) We have used physiological and pharmacological experimental manipulations to selectively modulate utricular nerve, hair cell or mechanical function, demonstrating the ability to differentially diagnose the basis of peripheral vestibular disorders in the mammalian utricle. These tools allow for a more complete understanding of peripheral vestibular function and a first order perspective into clinical disorders effecting the otoliths.

11

Peelukhana, Srikara Vishwanath. "Better diagnosis of coronary artery disease using combined trans-lesional hemodynamics and anatomical information." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1407406861.

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12

Madamedon, Misan. "The characteristics of instantaneous angular speed of diesel engines for fault diagnosis." Thesis, University of Huddersfield, 2018. http://eprints.hud.ac.uk/id/eprint/34553/.

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Early fault detection and diagnosis of diesel engines are paramount now, especially with countries like the UK and France, in-line with the 2015 Paris agreement on climate change, making plans to ban the use of an automobile with diesel and petrol engines before the year 2040. This ban could affect other sectors where diesel engines are the prime mover and result in more stringent exhaust emission regulations. The instantaneous angular speed (IAS) model based fault diagnosis has shown more prospects of fault detection and location. However, there are serious gaps in available knowledge regarding IAS model based fault diagnosis which takes into account the effect of the system’s modal properties. Hence, this research focuses on the online modal properties identification of a typical engine-load system for an improved performance of IAS based fault diagnosis. Having acknowledged the essentials of IAS based fault diagnosis techniques through a comprehensive literature study, this research firstly investigates the impact of modal properties on the IAS of a four-cylinder engine. This is achieved through a three degree of freedom (DOF) torsional vibration model of the engine-load system, which allows for the modal properties of the system to be calculated and analysed. The calculated modal properties of the system showed one rigid and two flexible modes which had a low (< 13Hz) and high (< 92Hz) frequencies. The mode shape of the low frequency resonance shows more amplitude on the flywheel-load reference point of the system while that of the high frequency resonance shows more amplitude on the engine-flywheel reference point of the system. It then simulated the IAS which represents the torsional vibration signature with altered modal properties. The simulated result demonstrated that the low frequency resonance is more sensitive to the peak and trough values of the IAS waveform. After identifying the deployment merits of operational modal analysis (OMA) techniques through a comprehensive literature study, this research then explore the prospect of an IAS based output-only modal properties identification of a typical engine-load system. This was done through both experimental and simulation evaluations, which allowed simulated and experimental IAS to be used for implementing covariance-driven reference based stochastic subspace identification (SSI). The simulated result using pseudo-random input shows that the identified resonance frequencies and mode shapes are 80% correlated with the calculated ones. The simulation results also demonstrated that the accuracy of the identified modal properties is dependent on the number of IAS responses used for implementing the covariance-driven reference based SSI technique. The experimental result using estimated IAS during engine shutdown operation showed that both high and low frequency vibration mode can be identified. The identified resonance frequencies with their mode shapes are 80% correlated with the predicted ones. Having identified the modal properties of the engine-load system online through the implementation of an IAS based covariance-driven SSI, this research then investigates the impact of misfire on the system’s modal properties especially the mode shape of the low frequency resonance. This was achieved experimentally by inducing a complete misfire in respective cylinders (1st, 3rd and 4th) and the IAS estimated during engine’s transient shutdown operation was used for implementing a covariance-driven reference based stochastic subspace modal properties identification. While the mode shape of the identified high frequency resonance (< 80Hz) showed no characteristics for cylinder misfire detection, that of the low frequency resonance (< 13Hz) did. Faults in the engine’s injection system and an abnormal clearance valve train conditions significantly affects its combustion process. The cylinder by cylinder pressure torque obtained from measured IAS through order domain deconvolution technique can be used to detect and diagnose injection faults. In the interim, this research has also recognised that the closer the low-resonance frequency of the model used for the order domain deconvolution gets to its real time value the more accurate the pressure torque becomes. The reconstructed pressure torque which takes into consideration the real time low frequency resonance can be used to detect faulty injection system with different severities and abnormal clearance valve conditions of several severities. Furthermore, the importance of an accurate modal properties utilisation in IAS model.

13

Katz, Edward A. "Biomechanical Assessment of Parkinson's Disease." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/83.

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Parkinson's disease is a chronic neurological disorder affecting hundreds of thousands of Americans. The current best practice for assessment of this disease is a clinical examination and subjective rating using the Unified Parkinson's Disease Rating Scale. Such ratings are coarse scaled, subject to rater bias, and costly. Instruments which provide objective measurements of disease state can eliminate rater bias, provide repeatable data, and increase the frequency and responsiveness of subject assessments, expediting the validation of new therapies and treatments. This thesis describes the design and implementation of a battery of bio-mechanical devices suitable for clinical and in home use, including descriptions of the instruments and the functionality of the data acquisition software, as well as the overall system used for data collection. A data analysis algorithm is fully described, and descriptive statistics of pilot data from twenty two subjects are reported. These statistics show promising correlations of time duration metrics with the motor subsection of the UPDRS, as well as good responsiveness to dopaminergic intervention. Data also suggests that these devices have an advantage over previously described devices in the ability to record the full range of motion in standard assessment tasks, thereby providing additional metrics related to hesitations and halts in prescribed movements.

14

Deosthale, Eeshan Vijay. "Model-Based Fault Diagnosis of Automatic Transmissions." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542631227815892.

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15

Tian, Xiange. "Enhanced information extraction from noisy vibration data for machinery fault detection and diagnosis." Thesis, University of Huddersfield, 2017. http://eprints.hud.ac.uk/id/eprint/31440/.

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As key mechanical components, bearings and gearboxes are employed in most machines. To maintain efficient and safe operations in modern industries, their condition monitoring has received massive attention in recent years. This thesis focuses on the improvement of signal processing approaches to enhance the performance of vibration based monitoring techniques taking into account various data mechanisms and their associated periodic, impulsive, modulating, nonlinear coupling characteristics along with noise contamination. Through in-depth modelling, extensive simulations and experimental verifications upon different and combined faults that often occur in the bearings and gears of representative industrial gearbox systems, the thesis has made following main conclusions in acquiring accurate diagnostic information based on improved signal processing techniques: 1) Among a wide range of advanced approaches investigated, such as adaptive line enhancer (ALE), wavelet transforms, time synchronous averaging (TSA), Kurtogram analysis, and bispectrum representations, the modulation signal bispectrum based sideband estimator (MSB-SE) is regarded as the most powerful tool to enhance the periodic fault signatures as it has the unique property of simultaneous demodulation and noise reduction along with ease of implementation. 2) The proposed MSB-SE based robust detector can achieve optimal band selection and envelope spectrum analysis simultaneously and show more reliable results for bearing fault detection and diagnosis, compared with the popular Kurtogram analysis which highlights too much on localised impulses. 3) The proposed residual sideband analysis yields accurate and consistent diagnostic results of planetary gearboxes across wide operating conditions. This is because that the residual sidebands are much less influenced by inherent gear errors and can be enhanced by MSB analysis. 4) Combined faults in bearings and gears can be detected and separated by MSB analysis. To make the results more reliable, multiple slices of MSB-SE can be averaged to minimise redundant interferences and improve the diagnostic performance.

16

Buzza, Matthew. "An Evaluation of Classification Algorithms for Machinery Fault Diagnosis." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490702571145903.

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17

Kolli, Kranthi Kumar. "Diagnosis of Coronary Artery Disease Using Pressure Drop Coefficient." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1415615529.

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18

Liu, Tingting. "Electrokinetic Real-Time Polymerase Chain Reaction Toward Point-Of-Care Diagnosis." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/579083.

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Rapid diagnosis of infectious disease and timely initiation of proper clinical antibiotic treatment is the determinant in obtaining the optimal clinical outcomes and reducing emergences of multidrug-resistant organisms. In particular, acute infections require the detection to be accomplished in limited time with high sensitivity due to the low concentration of organisms causing the infections. Real-time Polymerase Chain Reaction can provide quantitative identification of specific genetic materials and has revolutionized clinical microbiology laboratory diagnosis. It is becoming a standard for infectious disease detection. However, most real-time PCR instruments on the market are bulky, fragile and costly due to their delicate optical components, which restricted their use to point-of-care application. Modern microfluidic and sensing technology provide a transition from benchtop real-time PCR to miniaturizable, robust, and portable real-time PCR devices to achieve rapid, low-cost, and efficient point-of-care diagnosis. In this work, an innovative electrokinetic PCR (EK-PCR) platform that combines AC electrothermal flow (ACEF) and Joule heating induced temperature gradient to implement thermal cycling for DNA amplification is discussed. In addition, in situ electrochemical sensing is incorporated in the EK-PCR chamber for real-time monitoring of the DNA concentration toward quantification of the initial copies of the DNA template. EK-PCR can improve the energy efficiency with minimized total thermal mass and remain high amplification efficiency. More importantly, it represents a highly integrated strategy for portable point-of-care devices.

19

Cecílio, Inês M. "On extending process monitoring and diagnosis to the electrical and mechanical utilities : an advanced signal analysis approach." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24962.

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This thesis is concerned with extending process monitoring and diagnosis to electrical and mechanical utilities. The motivation is that the reliability, safety and energy efficiency of industrial processes increasingly depend on the condition of the electrical supply and the electrical and mechanical equipment in the process. To enable the integration of electrical and mechanical measurements in the analysis of process disturbances, this thesis develops four new signal analysis methods for transient disturbances, and for measurements with different sampling rates. Transient disturbances are considered because the electrical utility is mostly affected by events of a transient nature. Different sampling rates are considered because process measurements are commonly sampled at intervals in the order of seconds, while electrical and mechanical measurements are commonly sampled with millisecond intervals. Three of the methods detect transient disturbances. Each method progressively improves or extends the applicability of the previous method. Specifically, the first detection method does univariate analysis, the second method extends the analysis to a multivariate data set, and the third method extends the multivariate analysis to measurements with different sampling rates. The fourth method developed removes the transient disturbances from the time series of oscillatory measurements. The motivation is that the analysis of oscillatory disturbances can be affected by transient disturbances. The methods were developed and tested on experimental and industrial data sets obtained during industrial placements with ABB Corporate Research Center, Kraków, Poland and ABB Oil, Gas and Petrochemicals, Oslo, Norway. The concluding chapters of the thesis discuss the merits and limitations of each method, and present three directions for future research. The ideas should contribute further to the extension of process monitoring and diagnosis to the electrical and mechanical utilities. The ideas are exemplified on the case studies and shown to be promising directions for future research.

20

Shi, Zhe. "A Comparative Study of Performance Assessment and Fault Diagnosis Approaches for Reciprocating Electromechanical Mechanism." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1468512813.

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21

Mrozewski, Kamil Janusz. "Diagnosis of mechanical tightening of a single polymer electrolyte membrane fuel cell (LT-PEM and HT-PEM) in aeronautical applications." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0034/document.

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Les activités R&D dans le domaine d’aéronautique sont actuellement orientées par l’évolution naturelle vers des technologies plus efficaces et durables. La motivation principale de cette tendance est le besoin de résoudre les problèmes liés à la nature de l’industrie très polluante. À cet égard, le développement d’avions plus électriques contribuerait à la réduction de la consommation de combustibles fossiles en intégrant des sources et des convertisseurs d’énergie alternatifs, tels que les piles à combustibles (PàC). Cependant, un système PàC devrait se conformer à des contraintes de fiabilité et de sécurité particulières, d’autant plus que l’environnement aéronautique n’est guère clément : cyclages en pression et en température, ainsi que des forces mécaniques, agissants dans les trois dimensions. Les vibrations et les chocs peuvent notamment entraîner un desserrage brusque ou graduel de la PàC, dégradant ainsi ses performances et pouvant aller jusqu’à une fuite de gaz. Il semble donc important de pouvoir surveiller l’état de serrage mécanique d’une PàC au cours du temps, idéalement de manière non intrusive. Les résultats présentés dans la littérature indiquent que la qualité du serrage mécanique d’une PàC peut être évaluée à travers sa résistance ohmique (Rohm), plus précisément par sa partie électronique (Re-, formée par les résistances des couches de la PàC et les résistances de contact). Dans les conditions nominales de fonctionnement, l’autre partie plus importante de la Rohm – la résistance protonique (RH+, formée par la résistance de la membrane et de l’ionomère) – ne dépend pas de la force de serrage. Cette amalgamation de résistances de natures différentes empêche une extraction de la Re- sans l’utilisation de capteurs invasifs. Par conséquent, l’estimation de la qualité du serrage mécanique d’une PàC n’est pas aisée. Au cours de cette thèse, une méthode de diagnostic préventif in situ capable de détecter la dégradation des conditions de serrage d’une PàC par la modélisation de sa résistance ohmique est proposée. Une étude théorique est d’abord réalisée afin de démontrer que les résistances RH+ et Re- peuvent être séparées de la Rohm totale, à partir de leur dépendance à la température. La méthode de diagnostic est ensuite validée à l’aide de données expérimentales générées lors de la caractérisation de deux PàC à membrane échangeuse de protons : basse et haute température. Quelques divergences entre les valeurs identifiées par l’algorithme et celles rapportées dans la littérature sont observées, néanmoins, elles représentent correctement l’état du serrage mécanique de la PàC. Dans l’ensemble, les résultats sont encourageants dans le but d’estimer la qualité du serrage mécanique d’une PàC à travers l’évolution de RH+ et Re-
The aeronautical R&D activities are currently shaped by the issues associated with the pollutantrich nature of the industry and the natural evolution towards more effective and sustainable technologies. In this regard, the development of more electric aircraft would contribute to reducing fossil fuel consumption by incorporating alternative sources and converters of energy, such as FCs. However, a FC system would have to comply with particular reliability and safety constraints, especially as the aeronautical environment is not very indulgent: abundant pressure and temperature cycling as well as mechanical loads, varying both in frequency and amplitude, in all three dimensions. Vibrations and shocks can in particular lead to a sudden or gradual loosening of the FC, thus degrading its performance, and possibly provoking a gas leak. It therefore seems important to be able to monitor the tightening state of a FC over time, ideally in a non-intrusive manner. Results reported in the literature indicate that the quality of the mechanical tightening of a FC assembly might be assessed through its ohmic resistance (Rohm), more precisely through its electronic part (Re-, formed by the bulk resistances of FC layers and the interfacial contact resistances). In nominal operating conditions, the second and more dominant part of Rohm – the protonic resistance (RH+, formed by the membrane and ionomer resistances) – does not depend on clamping pressure. This amalgamation of resistances of different natures prevents an easy extraction of Re- without the use of invasive sensors and thus an estimation of the quality of the mechanical tightening of a FC assembly. This thesis proposes an in situ preventive diagnosis method that is capable of detecting the degradation of clamping conditions of a FC through the modelling of its ohmic resistance. A theoretical study is performed and demonstrates that the RH+ and Re- resistances can be separated from the total Rohm, based on their temperature dependence. The proposed method is verified with experimental data generated during the characterization of low and high temperature Polymer Electrolyte Membrane (PEM) single cells. Although some differences between the values identified by the algorithm and those reported in the literature are observed, they correctly depict the behavior of the mechanical tightening of the tested FCs. Overall, the results are encouraging in the aim of monitoring the quality of mechanical tightening of a FC through the evolution of RH+ and Re-

22

Abdusslam, Shukri Ali. "Detection and diagnosis of rolling element bearing faults using time encoded signal processing and recognition." Thesis, University of Huddersfield, 2012. http://eprints.hud.ac.uk/id/eprint/17806/.

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This thesis presents a systematic study of using TESPAR (Time Encoded Signal Processing and Recognition), which presently is in use as an effective tool for speech recognition and shows great advantages in computational demands and accuracy, to develop a new technique for rolling element bearing fault detection and diagnosis. The fundamentals of rolling element bearings are presented in line with different failure modes and relevant monitoring methods in the time domain, the frequency domain, the envelope spectrum and the wavelet analysis. These reviews show that vibration measurements are a proven and widely accepted data source for bearing monitoring of machinery. This research thus has focused on developing TESPAR based approaches using vibration signals which are generated from bearings under different severities of faults located at the outer race, the inner race and the roller element. It firstly examines the theoretical basis of TESPAR and examines the diagnosis performance with a number of different simulated signals, which confirms that TESPAR based methods are able to resolve different signals by using their statistics including S-matrix, A-matrix and epoch duration, which paves a frame work to process and interpolate the bearing signal. With understandings of the insights of bearing vibrations and TESPAR approaches a signal processing framework is then suggested to analyse bearing vibration signals. It consists of a pre-processing step which removes possible noise in the signal, a TESPAR coding step which converts the signal into TESPAR representations-TESPAR streams, a feature calculation step, which produces different TESPAR statistic parameters, and finally a diagnosis step which applies common statistics to TESPAR statistic parameters to obtain required results. The TESPAR solution proposed in this thesis shows that discrimination between different bearing signal waveforms has been implemented successfully. TESPAR S- and A-Matrices were constructed for the cases tested and used together with statistical correlation to differentiate between the types of faults. However, the severities of bearing faults have been identified using another TESPAR feature called the mean absolute magnitude value calculated using epoch durations. The performance of the TESPAR approach was then evaluated against the envelope spectrum; this being the most common method for bearing condition monitoring that is conducted in two terms; the process complexity and diagnosis performance. A major contribution of this research programme is the development of a method that can provide improved detection and diagnosis of bearing fault types and severity of faults seeded into roller bearings.

23

Seliktar, Dror. "Dynamic mechanical conditioning regulates the development of cell-seeded collagen constructs in vitro : implications for tissue-engineered blood vessels." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/25674.

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24

Zhang, Jiyu. "Model-Based Fault Diagnosis For Automotive Functional Safety." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480665190516692.

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25

Albero, Blanquer Laura. "Operando optical sensing for battery diagnosis." Thesis, Sorbonne université, 2022. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2022SORUS134.pdf.

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Les batteries, qui constituent l'une des technologies de stockage d'énergie les plus polyvalentes, sont essentielles dans un large spectre d'applications telles que les réseaux électriques, l'aérospatiale, la robotique, et les véhicules électriques. Cette dépendance rend la qualité, la fiabilité, la durée de vie et la sécurité des batteries immensément plus importantes que jamais. Cela confirme la nécessité de surveiller avec précision l'état fonctionnel des batteries et appelle donc au développement de techniques de détection intelligente dans ces dispositifs. Cette thèse vise à explorer ce sujet en utilisant des capteurs à fibre optique à réseau de Bragg (FBG). Pour commencer, nous donnons un aperçu historique de l'évolution de la surveillance des batteries, avant de nous concentrer sur la détection optique. Ensuite, nous démontrons la faisabilité de l'incorporation de capteurs FBG à l'intérieur de cellules cylindriques et de poches commerciales pour effectuer une calorimétrie optique. Ensuite, en utilisant le même capteur optique, on étudie la contrainte chimico-mécanique qui se produit au niveau de l'électrode dans des cellules contenant un électrolyte liquide ou solide. Pour la validation du concept, des électrodes en alliage de Li qui présentent d'importants changements de volume lors de l'insertion ou du retrait de Li sont sélectionnées. Au cours de cette thèse, le signal optique surveillé pendant le cyclage de la batterie est traduit soit en température, pression ou stress et corrélé avec le profil de voltage. Enfin, ce travail propose une technique operando avec une utilisation potentiellement efficace pour le diagnostic des cellules et le design des batteries
Rechargeable batteries, as one of the most versatile energy storage technologies, are essential in a broad range of applications such as power grids, aerospace, robotics, consumer electronics, and electric vehicles. Such dependence makes battery quality, reliability, lifetime, and safety (QRLS) immensely more important than ever before. This underlines the need to accurately monitor the batteries’ functional status and therefore calls for the development of non-invasive operando techniques that could inject smart sensing functionalities into these dynamic electrochemical devices directly from inside. This is exactly what this thesis aims to explore by using optical fiber Bragg grating (FBG) sensors. To begin with, we first provide an historical overview of the evolution of battery monitoring, before focusing on optical sensing. Then, we demonstrate the feasibility of incorporating FBG sensors inside commercial pouch and cylindrical cells to perform optical calorimetry, hence assessing chemical events such as solid electrolyte interphase formation or thermodynamic parameters. Next, by using the same optical sensor, the chemo-mechanical stress occurring at the electrode level in cells containing either liquid or solid-state electrolyte is investigated. For proof-of-concept, Li-alloying electrodes that undergo large volume changes upon Li uptake or removal are selected. More specifically, throughout this thesis the optical signal monitored during battery cycling is translated into either temperature, pressure or stress and correlated with the voltage profile. To sum up, this work proposes an operando technique with potential use in cell diagnosis and battery designs

26

Picciano, Nicholas I. "Battery Aging, Diagnosis, and Prognosis of Lead-Acid Batteries for Automotive Application." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243871818.

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Boonyaprapasorn, Arsit. "FAULT DETECTION AND DIAGNOSIS PROCESS FOR CRACKED ROTOR VIBRATION SYSTEMS USING MODEL-BASED APPROACH." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238469531.

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28

Das, Ashish. "Development of Energy-Based Endpoints for diagnosis of Pulmonary Valve Insufficiency." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384864758.

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29

Ainapure, Abhijeet Narhar. "Application and Performance Enhancement of Intelligent Cross-Domain Fault Diagnosis in Rotating Machinery." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623164772153736.

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Wang, Rongrong. "Fault-Tolerant Control and Fault-Diagnosis Design for Over-Actuated Systems with Applications to Electric Ground Vehicles." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365522537.

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31

Phung, Van Trang [Verfasser]. "Enhancement of the control and diagnosis of mechanical failures of a drive by using load cycle identification / Van Trang Phung." Siegen : Universitätsbibliothek der Universität Siegen, 2018. http://d-nb.info/1169398685/34.

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32

Li, Tianpei. "Fault Diagnosis for Functional Safety in Electrified and Automated Vehicles." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587583790925718.

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33

Doherty, Neil Francis. "Knowledge-based approaches to fault diagnosis : the development, implementation, evaluation and comparison of knowledge-based systems, incorporating deep and shallow knowledge, to aid in the diagnosis of faults in complex hydro-mechanical devices." Thesis, University of Bradford, 1992. http://hdl.handle.net/10454/4374.

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The use of knowledge-based systems to aid in the diagnosis of faults in physical devices has grown considerably since their introduction during the 1970s. The majority of the early knowledge-based systems incorporated shallow knowledge, which sought to define simple cause and effect relationships between a symptom and a fault, that could be encoded as a set of rules. Though such systems enjoyed much success, it was recognised that they suffered from a number of inherent limitations such as inflexibility, inadequate explanation, and difficulties of knowledge elicitation. Many of these limitations can be overcome by developing knowledge-based systems which contain deeper knowledge about the device being diagnosed. Such systems, now generally referred to as model-based systems, have shown much promise, but there has been little evidence to suggest that they have successfully made the transition from the research centre to the workplace. This thesis argues that knowledge-based systems are an appropriate tool for the diagnosis of faults in complex devices, and that both deep and shallow knowledge have their part to play in this process. More specifically this thesis demonstrates how a wide-ranging knowledge-based system for quality assurance, based upon shallow knowledge, can be developed, and implemented. The resultant system, named DIPLOMA, not only diagnoses faults, but additionally provides advice and guidance on the assembly, disassembly, testing, inspection and repair of a highly complex hydro-mechanical device. Additionally it is shown that a highly innovative modelbased system, named MIDAS, can be used to contribute to the provision of diagnostic, explanatory and training facilities for the same hydro-mechanical device. The methods of designing, coding, implementing and evaluating both systems are explored in detail. The successful implementation and evaluation of the DIPLOMA and MIDAS systems has shown that knowledge-based systems are an appropriate tool for the diagnosis of faults in complex hydro-mechanical devices, and that they make a beneficial contribution to the business performance of the host organisation. Furthermore, it has been demonstrated that the most effective and comprehensive knowledge-based approach to fault diagnosis is one which incorporates both deep and shallow knowledge, so that the distinctive advantages of each can be realised in a single application. Finally, the research has provided evidence that the model-based approach to diagnosis is highly flexible, and may, therefore, be an appropriate technique for a wide range of industrial applications.

34

Doherty, Neil F. "Knowledge-based approaches to fault diagnosis. The development, implementation, evaluation and comparison of knowledge-based systems, incorporating deep and shallow knowledge, to aid in the diagnosis of faults in complex hydro-mechanical devices." Thesis, University of Bradford, 1992. http://hdl.handle.net/10454/4374.

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The use of knowledge-based systems to aid in the diagnosis of faults in physical devices has grown considerably since their introduction during the 1970s. The majority of the early knowledge-based systems incorporated shallow knowledge, which sought to define simple cause and effect relationships between a symptom and a fault, that could be encoded as a set of rules. Though such systems enjoyed much success, it was recognised that they suffered from a number of inherent limitations such as inflexibility, inadequate explanation, and difficulties of knowledge elicitation. Many of these limitations can be overcome by developing knowledge-based systems which contain deeper knowledge about the device being diagnosed. Such systems, now generally referred to as model-based systems, have shown much promise, but there has been little evidence to suggest that they have successfully made the transition from the research centre to the workplace. This thesis argues that knowledge-based systems are an appropriate tool for the diagnosis of faults in complex devices, and that both deep and shallow knowledge have their part to play in this process. More specifically this thesis demonstrates how a wide-ranging knowledge-based system for quality assurance, based upon shallow knowledge, can be developed, and implemented. The resultant system, named DIPLOMA, not only diagnoses faults, but additionally provides advice and guidance on the assembly, disassembly, testing, inspection and repair of a highly complex hydro-mechanical device. Additionally it is shown that a highly innovative modelbased system, named MIDAS, can be used to contribute to the provision of diagnostic, explanatory and training facilities for the same hydro-mechanical device. The methods of designing, coding, implementing and evaluating both systems are explored in detail. The successful implementation and evaluation of the DIPLOMA and MIDAS systems has shown that knowledge-based systems are an appropriate tool for the diagnosis of faults in complex hydro-mechanical devices, and that they make a beneficial contribution to the business performance of the host organisation. Furthermore, it has been demonstrated that the most effective and comprehensive knowledge-based approach to fault diagnosis is one which incorporates both deep and shallow knowledge, so that the distinctive advantages of each can be realised in a single application. Finally, the research has provided evidence that the model-based approach to diagnosis is highly flexible, and may, therefore, be an appropriate technique for a wide range of industrial applications.
Science and Engineering Research Council, and Alvey Directorate

35

Saadawia, Mahmud-Sami [Verfasser], and Dirk [Akademischer Betreuer] Söffker. "Application of Wavelets-based SVM Classification for Automated Fault Diagnosis and Prognosis of Mechanical Systems / Mahmud-Sami Saadawia. Betreuer: Dirk Söffker." Duisburg, 2016. http://d-nb.info/1109745753/34.

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36

Saadawia, Mahmud-Sami Verfasser], and Dirk [Akademischer Betreuer] [Söffker. "Application of Wavelets-based SVM Classification for Automated Fault Diagnosis and Prognosis of Mechanical Systems / Mahmud-Sami Saadawia. Betreuer: Dirk Söffker." Duisburg, 2016. http://d-nb.info/1109745753/34.

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37

Rahman, Brian M. "Sensor Placement for Diagnosis of Large-Scale, Complex Systems: Advancement of Structural Methods." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562859497638274.

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38

Weatherwax, Scott Eric. "Use of the continuous wavelet tranform to enhance early diagnosis of incipient faults in rotating element bearings." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3013.

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39

Jin, Wenjing. "A Comparative Study of Fault Detection and Health Assessment Techniques for Motion Control Mechanism." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1416234423.

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40

Länne, Rosenlund Hanna. "Redesign of a generic human limb pressure device – towards early diagnosis of pressure ulcer risk patients." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-30300.

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This report is a Bachelor thesis in the field of product development and design. It includes a literature review in the field of pressure ulcers and diabetes as well as a design process. The writer of this report, Hanna Länne Rosenlund, is a Mechanical Engineering student at the School of Engineering at Jönköping University. The focus of the education lies within product development and design. Pressure ulcers are a growing health care problem due to an increase in the mean life expectancy as well as an increase in diabetes in the world population. Patients with artificial limbs are often victims of pressure ulcers due to prolonged pressures from the prosthetic sockets on already sensitive areas of the body. Research in the field of pressure-induced injuries is currently taking place at Jönköping University. Their knowledge in finite element modelling and orthopaedic engineering made the research project, PEOPLE, possible. PEOPLE is a collaboration project between the School of Engineering and the School of Health and Welfare at Jönköping University as well as three company partners. In the project they aim to develop a device that will apply pressure to a lower limb while a MR camera takes scans of the limb. The images are later analysed closely by use of the finite element model, which means that all the different tissue properties will be collected for a computer simulation. In that way the tissues reactions to more extreme forms of pressure can be evaluated. This will contribute to the research in hope of eventually being able to predict whether or not a person might be at risk of developing pressure ulcers. A design of the prototype’s chassis was needed to optimize ease of use for both patient and staff, user options to expand research abilities, and sustainability. The design process includes product decomposition, concept generation, conceptual design, brainstorming, design for assembly, and design for component manufacturing, which generated several concepts. The final concept was decided by use of Pugh’s-matrices. The different concepts and the final concept were created in the computer aided design programme, Solid Works. The work resulted in a highly adjustable two-piece concept with optimized ease of use and sustainability due to the use of a Velcro strap. The prototype will come in two different sizes and will be mountable by a developed screwing system and therefore easy to pack, store and replace. It will also contain a new pressure relief system for a more comfortable patient experience. For further development of chassis of this kind, a replaceable pressure relief system would enhance the comfort when usage of larger limbs. When the device will be available for testing, a patient’s point of view can be taken in to consideration for a more reliable thesis and for further optimization of the comfort.
Detta är ett examensarbete på kandidatnivå inom ämnet produktutveckling och design. I arbetet ingår en litterär överblick och sammanfattning av forskning i ämnet angående trycksår och diabetes, samt en designprocess. Författaren, Hanna Länne Rosenlund studerar Maskinteknik med inriktning Produktutveckling och Design på Jönköpings Tekniska Högskola. Trycksår är ett växande problem inom vården på grund av en ökning i medellivslängden samt en ökning av diabetesdiagnoser hos världens befolkning. Patienter med proteser faller ofta offer för trycksår på grund av extrema och långvariga tryckförhållanden där proteserna är lokaliserade. Ett område som redan är känsligare för tryck. Forskning inom tryckframkallande skador pågår just nu på Jönköping University. Deras kunskap inom finita elements modellering samt ortopedingenjörsteknik har gjort detta forskningsprojekt möjligt. Forskningsprojektet heter PEOPLE och är ett samverkningsprojekt mellan Tekniska Högskolan, Hälsohögskolan samt tre företagspartners. Tillsammans siktar de mot att utveckla en prototyp som ska utsätta en lem för ett konstant tryck medan en MR kamera scannar vävnaden. En finit elements modell av lemmen skapas sedan för närmre granskning av vävnaden hos individen. Vävnadens egenskaper samlas sedan för en simulering då man kan utvärdera hur vävnaden skulle reagera på mer extrema former av tryck. På så sätt kan prototypen bidra till forskningen inom ämnet för att förhoppningsvis kunna förutspå ifall en person är vid risk för att utveckla trycksår eller inte. En omkonstruktion av prototypens chassi har utvecklats för att optimera användarvänligheten för både patient och personal, användarmöjligheten för forskningssyfte, samt för att bättre bidra till en mer hållbar lösning. Designprocessen har inkluderat teorier såsom produktnedbrytning, konceptgenerering, konceptutveckling, brainstorming, design for assembly och design for manufacturing som alla har hjälpt till att generera koncept. Det slutgiltiga konceptet valdes med hjälp av Pugh matriser. Koncepten samt det slutliga konceptet skapades i ett CAD (computer aided design) program, Solid Works. Arbetet resulterade i ett justerbart tvådelat koncept med optimerad användarvänlighet och hållbarhet genom att använda sig av ett kardborreband. Prototypen kommer att finnas i två olika storlekar och vara monterbar genom att det går att skruva bort chassit och på så sätt optimera packning, hantering och förvaring. Det kommer också att innehålla ett nyutvecklat system för att underlätta fördelningen av tryck på motsatt sida från indenteringen. För fortsatt utveckling av chassit hade ett utbytbart system för tryckavledning optimerat produkten ytterligare då komforten hade ökat vid användning på större lemmar. När produkten finns tillgänglig för testning i framtiden kommer en patients syn vara möjlig att ta med och på så sätt förstärka trovärdigheten av arbetet samt bidra till fortsatt strävande för komfort.

41

Ramahaleomiarantsoa, Fanjason Jacques. "Diagnostic des systèmes à énergies renouvelables de type éolien." Phd thesis, Université Pascal Paoli, 2013. http://tel.archives-ouvertes.fr/tel-01022178.

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Avec l'évolution technologique, le progrès de l'électronique de puissance et surtout l'enjeu économique, l'utilisation des machines asynchrones à cages ou à rotor bobiné occupe de plus en plus de place dans tous les domaines comme les entrainements électriques et la production d'énergie, leur robustesse, leur fiabilité et leur coût moins élevé sont particulièrement appréciés. Ces deux types d'actionneur en fonctionnement générateur sont la base des éoliennes actuelles.Néanmoins, malgré les travaux de recherches effectués ainsi que les améliorations apportées, ces machines demeurent des sièges potentiels de défaillances aussi bien au niveau stator que rotor. Les défauts les plus courants qui peuvent se produire dans la génératrice asynchrone à rotor bobiné du système éolien, au niveau rotor et stator sont : a) le court circuit sur les enroulements rotoriques et statoriques, b) les défaillances de roulements, c) les irrégularités statiques ou dynamiques de l'entrefer, d) les problèmes au niveau des balais et collecteurs. Ces types de défauts doivent êtres détectés, localisés à temps car ils peuvent endommager gravement le système. Durant ces dernières années, le diagnostic des défauts affectant les systèmes éoliens a été largement étudié. Un grand nombre de méthodes est disponible visant à améliorer la conception du système, à augmenter la qualité et la production d'énergie électrique et d'en diminuer les coûts. Malgré les résultats de la recherche, ces systèmes multi-complexes restent encore les sièges de réflexions de plusieurs laboratoires tant qu'industriels qu'académiques.Ce rapport de thèse présente une nouvelle méthodologie de diagnostic de défauts combinant la méthode à base de modèle utilisant les équations mathématiques explicites du processus et la méthode sans modèle. Les machines électriques sont modélisées analytiquement par la méthode des circuits électriques magnétiquement couplés. L'objectif est de générer des données en fonctionnement sain et en fonctionnement défaillant de ses variables d'état. Tandis que la méthode sans modèle utilisée est l'analyse en composantes principales (ACP). Les deux méthodes sont implémentées sous Matlab/ Simulink. Les données de la machine acquises sont traitées et analysées par des méthodes statistiques pour générer des résidus. La détection et la localisation de défauts sur la machine sont obtenues par l'analyse des résidus de ses variables d'état. Les résidus sont des indicateurs de défaillance ou non du système étudié. L'analyse des grandeurs caractéristiques de la machine étudiée dans ce rapport de thèse par le biais de plusieurs résultats de simulation montre l'efficacité de la méthode ACP, aussi bien sur le plan de la détection que de la localisation, par rapport aux autres méthodes de diagnostic des machines électriques.

42

Yang, Ruochen. "Diagnosis of Evaporative Emissions Control System Using Physics-based and Machine Learning Methods." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587651390226087.

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43

Visagie, Claude. "Screening for abnormal heart sounds and murmurs by implementing neural networks." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/3119.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007.
This thesis is concerned with the testing of an “auscultation jacket” as a means of recording heart sounds and electrocardiography (ECG) data from patients. A classification system based on Neural Networks, that is able to discriminate between normal and abnormal heart sounds and murmurs, has also been developed . The classification system uses the recorded data as training and testing data. This classification system is proposed to serve as an aid to physicians in diagnosing patients with cardiac abnormalities. Seventeen normal participants and 14 participants that suffer from valve-related heart disease have been recorded with the jacket. The “auscultation jacket” shows great promise as a wearable health monitoring aid for application in rural areas and in the telemedicine industry. The Neural Network classification system is able to differentiate between normal and abnormal heart sounds with a sensitivity of 85.7% and a specificity of 94.1%.

44

Esposito, Angelo. "Numerical and Experimental Study of Droplet-Air Flow Interaction on the GDL Surface of PEMFC for Water Management Monitoring, Control and Diagnostics." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274977066.

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45

Subramony, Anantha Krishna. "Efficacy of New Diagnostic Parameters for Determining Arteriovenous Fistula Functionality: A Numerical Study." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470753788.

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46

Ozdurak, Rabia Hurrem. "Vibration Analysis In The Diagnosis Of Bone Mineral Density In Healthy And Osteopenic Radius Bone And Its Correlation To Muscle Strength." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12605109/index.pdf.

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Muscle strength is assumed to be closely related with BMD, the so called determinant of bone strength, however, new methods for bone strength measurement are arising. The purpose of this study was to determine the relationship between bone mineral density (BMD), muscle strength and natural frequency of the radius in the dominant and non-dominant arm in healthy and osteopenic individuals aged between 50-70 years. Sixty sedentary male (thirty healthy and thirty osteopenic) participated this study. Bone mineral density assessment was performed by dual x-ray absorbtiometry (DEXA) and quantitative computed tomography (QCT), whereas muscle strength was measured by an isokinetic dynamometer quantitatively. Natural frequency of the radius was determined by a dual channel frequency analyzer. Differences between BMD, muscle strength and natural frequency in healthy and osteopenic participants according to dominancy were examined by Analysis of Variance (ANOVA). Pearson Product Correlation Coefficient test was conducted to determine the magnitude of the correlation between cortical, trabecular and average BMD, muscle strength and natural frequency. Results demonstrated a statistically significant difference between BMD, natural frequency and muscle strength in the dominant arm of both groups. There was also a significant difference in the non-dominant arm in terms of BMD, natural frequency and muscle strength, except in total work in the non-dominant arms. Moreover, there was a moderate positive correlation between BMD measured by DEXA and natural frequency in the dominant arm (r = ,59
p <
.001) and non-dominant arm (r = 0,64
p <
0.001), whereas the muscle strength was correlated to BMD with a low positive correlation in terms of peak torque in extension (r = ,36
p = ,005), peak torque in flexion (r = ,31
p = ,016), total work in extension (r = ,28
p = ,030) and total work in flexion (r = ,27
p = ,041) in the dominant arms. The correlation between muscle strength and BMD was not significant in the non-dominant arm. The highest correlation between natural frequency and bone geometry parameters was observed in cortical thickness (r = ,82
p = ,02). A statistically significant positive correlation (r = ,81
p = ,04) was also observed between average BMD measured by QCT and by DEXA. In summary, according to the findings of this study, it can be concluded that vibration analysis is a precise method in predicting bone strength that depends highly on its size, shape and the distribution of its trabecular and cortical components.

47

Cédric, Peeters. "Advanced signal processing for the identification and diagnosis of the condition of rotating machinery." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI107.

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Cette thèse porte sur des méthodes innovantes de contrôle de l'état de santé des machines tournantes par l’analyse des signaux vibratoires. En effet, la surveillance de l’état de santé des machines contribue à des améliorations substantielles des points de vue économique et de sureté. Afin d’y aboutir, l’une des manières les plus populaires est de recueillir les vibrations de la machine. La plupart de ces vibrations sont directement liées au comportement périodique des sous-systèmes de la machine tels que les arbres de rotation, engrenages, champs électriques rotationnels, etc. Cette connaissance peut être exploitée afin de concevoir une méthodologie adaptée à chaque type de défaut. Cette thèse s’intéresse aux étapes de la mise en œuvre de cette méthodologie. En règle générale, la première condition préalable à l’analyse avancée de l’information récoltée est la disponibilité de la vitesse instantanée de rotation. Cette vitesse doit être connue car la plupart des techniques du traitement du signal sont adaptées aux conditions de fonctionnement stationnaires. Ainsi, la connaissance de la vitesse permettra de compenser les fluctuations de vitesse, par exemple par le ré-échantillonnage angulaire du signal de vibration. Malgré l’existence d’outils de mesure permettant l’estimation de la vitesse tels que les codeurs et les tachymètres, cette thèse étudie le potentiel d’estimer la vitesse instantanée de rotation à partir des signaux vibratoires. Après l'estimation de la vitesse et le ré-échantillonnage angulaire, une étape suivante courante consiste à séparer le signal en composantes déterministes et stochastiques. Dans ce sens, l’efficacité et l’applicabilité de la procédure d'édition du cepstre sont analysées. Ensuite, différentes méthodes de filtrage sont appliquées au signal résiduel afin d’améliorer le rapport signal sur bruit. Pour cette fin, les méthodes existantes utilisant des critères conventionnels sont étudiées en parallèles avec une nouvelle méthodologie aveugle de filtrage. La dernière étape du processus de traitement consiste à diagnostiquer le défaut potentiel. Ainsi, des indicateurs statistiques sont calculés sur le signal obtenu après traitement et suivis dans le temps pour vérifier leurs variations. Dans de nombreux cas, la signature du défaut présente un comportement cyclostationaire. Par conséquent, cette thèse examine également différentes techniques d'analyse de la cyclostationarité. Enfin, les performances des différentes méthodes de traitement sont validées sur deux ensembles de données expérimentales de vibrations issues de boîtes de vitesses d’éoliennes
This Ph.D. dissertation targets innovative methods for vibration-based condition monitoring of rotating machinery. Substantial benefits can be achieved from an economical and a safety point of view using condition monitoring. One of the most popular methods to gather information about the state of machine parts is through the analysis of machine vibrations. Most of these vibrations are directly linked to periodical behavior of subsystems within the machine like e.g. rotating shafts, gears, rotating electrical fields, etc. This knowledge can be exploited to enable faultdependent processing schemes. This dissertation investigates how to implement and utilize these processing schemes and details the steps in such a procedure. Typically, the first prerequisite for advanced analysis is the availability of the instantaneous rotation speed. This speed needs to be known since most frequency-based analysis techniques assume stationary behavior. Knowledge of the speed thus allows for compensating speed fluctuations, for example through angular resampling of the vibration signal. While there are hardware-based solutions for speed estimation using angle encoders or tachometers, this thesis investigates the potential in vibration signals for speed estimation. After speed estimation and angular resampling, a common next step is to separate the signal into deterministic and stochastic components. The cepstrum editing procedure is examined for its efficacy and applicability. Afterwards, different filtering methods are inspected as to improve the signal-to-noise ratio of the signal content of interest. Existing methods using conventional criteria are investigated together with a novel blind filtering methodology. The final step in the multi-step processing scheme is to search for the potential fault. Statistical indicators can be calculated on the processed time domain signal and tracked over time to check for increases. In many cases, the fault signature exhibits cyclostationary behavior. Therefore this dissertation also examines different cyclostationary analysis techniques. Lastly, the performance of the different processing methods is validated on two experimental vibration data sets of wind turbine gearboxes

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Djuric, Natasa. "Real-time supervision of building HVAC system performance." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2215.

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This thesis presents techniques for improving building HVAC system performance in existing buildings generated using simulation-based tools and real data. Therefore, one of the aims has been to research the needs and possibilities to assess and improve building HVAC system performance. In addition, this thesis aims at an advanced utilization of building energy management system (BEMS) and the provision of useful information to building operators using simulation tools.

Buildings are becoming more complex systems with many elements, while BEMS provide many data about the building systems. There are, however, many faults and issues in building performance, but there are legislative and cost-benefit forces induced by energy savings. Therefore, both BEMS and the computer-based tools have to be utilized more efficiently to improve building performance.

The thesis consists of four main parts that can be read separately. The first part explains the term commissioning and the commissioning tool work principal based on literature reviews. The second part presents practical experiences and issues introduced through the work on this study. The third part deals with the computer-based tools application in design and operation. This part is divided into two chapters. The first deals with improvement in the design, and the second deals with the improvement in the control strategies. The last part of the thesis gives several rules for fault diagnosis developed using simulation tools. In addition, this part aims at the practical explanation of the faults in the building HVAC systems.

The practical background for the thesis was obtained though two surveys. The first survey was carried out with the aim to find the commissioning targets in Norwegian building facilities. In that way, an overview of the most typical buildings, HVAC equipment, and their related problems was obtained. An on-site survey was carried out on an example building, which was beneficial for introducing the building maintenance structure and the real hydronic heating system faults.

Coupled simulation and optimization programs (EnergyPlus and GenOpt) were utilized for improving the building performances. These tools were used for improving the design and the control strategies in the HVAC systems. Buildings with a hydronic heating system were analyzed for the purpose of improving the design. Since there are issues in using the optimization tool, GenOpt, a few procedures for different practical problems have been suggested. The optimization results show that the choice of the optimization functions influences significantly the design parameters for the hydronic heating system.

Since building construction and equipment characteristics are changing over time, there is a need to find new control strategies which can meet the actual building demand. This problem has been also elaborated on by using EnergyPlus and GenOpt. The control strategies in two different HVAC systems were analyzed, including the hydronic heating system and the ventilation system with the recovery wheel. The developed approach for the strategy optimization includes: involving the optimization variables and the objective function and developing information flow for handling the optimization process.

The real data obtained from BEMS and the additional measurements have been utilized to explain faults in the hydronic heating system. To couple real data and the simple heat balance model, the procedure for the model calibration by use of an optimization algorithm has been developed. Using this model, three operating faults in the hydronic heating system have been elaborated.

Using the simulation tools EnergyPlus and TRNSYS, several fault detection and diagnosis (FDD) rules have been generated. The FDD rules were established in three steps: testing different faults, calculating the performance indices (PI), and classifying the observed PIs. These rules have been established for the air cooling system and the hydronic heating system. The rules can diagnose the control and the component faults. Finally, analyzing the causes and the effects of the tested faults, useful information for the building maintenance has been descriptively explained.

The most important conclusions are related to a practical connection of the real data and simulation-based tools. For a complete understanding of system faults, it is necessary to provide real-life information. Even though BEMS provides many building data, it was proven that BEMS is not completely utilized. Therefore, the control strategies can always be improved and tuned to the actual building demands using the simulation and optimization tools. It was proven that many different FDD rules for HVAC systems can be generated using the simulation tools. Therefore, these FDD rules can be used as manual instructions for the building operators or as a framework for the automated FDD algorithms.

Denne avhandlingen presenterer noen fremgangsmåter for forbedring av ytelser for VVS-tekniske anlegg i eksisterende bygninger basert på bruk av simuleringsverktøy og virkelige måledata. Ett av målene har vært å undersøke behov og muligheter for vurdering og forbedring av ytelser for VVS-anlegg i bygninger. I tillegg har denne avhandlingen hatt som mål å fremme bruk av SD-anlegg samt å fremskaffe nyttig informasjon til driftspersonalet.

Bygninger blir stadig mer kompliserte systemer som inneholder flere og flere komponenter mens SD-anlegg håndterer en stadig større mengde data fra bygningsinstallasjoner. På den ene siden registreres det ofte feil og problemer med hensyn til ytelsene til de VVS-tekniske installasjonene. På den andre siden innføres det stadig strengere lovmessige pålegg og kost-nyttekrav motivert i energieffektiviseringen. SD-anlegg og databaserte verktøy bør derfor brukes mer effektivt for forbedring av ytelsene.

Avhandlingen består av fire hoveddeler hvor hver del kan leses separat. Den første delen, som er basert på literatturstudie, forklarer funksjonskontroll som begrep og prinsipper for oppbygging av verktøy for funksjonskontroll. Den andre delen presenterer praktisk erfaring og problemstillinger utviklet og behandlet i løpet av arbeidet med avhandlingen. Den tredje delen handler om anvendelse av databaserte verktøy for forbedring av ytelsen for VVS-tekniske installasjoner. Den tredje delen er delt opp i to kapitler, hvorav et handler om forbedring av systemløsninger og et om forbedring av styringsstrategier. Den siste delen presenterer flere regler for feilsøking og diagnostisering utviklet gjennom bruk av simuleringsverktøy. I tillegg gir denne delen en praktisk forklaring av feilene i de VVS-anleggene som er behandlet i undersøkelsen.

Det praktiske grunnlaget for avhandlingen er etablert gjennom to undersøkelser. Den første var en spørreundersøkelse som hadde til hensikt å kartlegge målsetninger for funksjonskontroll i norske bygninger. Gjennom dette ble det etablert en oversikt over de mest typiske bygninger med tilhørende VVS-anlegg og de mest forekommende problemene. En dypere undersøkelse ble utført på ett casebygg. Denne undersøkelsen viste seg å være nyttig både for kartlegging av betydningen av organisering av driften av bygningen og for avdekking av de virkelige feilene i det vannbårne oppvarmingssystemet.

En kobling mellom et simulerings- og et optimaliseringsprogram (EnergyPlus og GenOpt) har vært benyttet for forbedring av ytelsene for de VVS-tekniske installasjonene. Disse verktøyene har vært brukt for forbedring av både systemløsningene og styringsstrategiene for VVS-anlegg. Bygninger med vannbåren oppvarmingssystem har vært analysert for å forbedre systemløsningen. På grunn av begrensninger i bruken av optimaliseringsverktøyet GenOpt, har det blitt utviklet egne prosedyrer for håndtering av visse typer problemstillinger hvor denne begrensningen opptrer. Resultatene for optimaliseringen viser at valg av objektfunksjoner påvirker betydelig parametrene i det vannbårne oppvarmingssystemet.

Endringer i egenskapene til både bygningskonstruksjoner og utstyr som skjer på grunn av aldring over tiden, gjør det nødvendig med tilpassning av styringsstrategier slik at det virkelige behovet kan bli dekket. Denne problemstillingen har vært analysert ved bruk av EnergyPlus og GenOpt. Styringsstrategiene for to forskjellige VVS-anlegg, et vannbåret oppvarmingssystem og et ventilasjonsanlegg med varmegjenvinner har blitt behandlet. Den utviklete prosedyren for optimalisering av styringsstrategien består av følgende steg: innføring av optimaliseringsvariabler og objektfunksjon, samt utvikling av informasjonsflyt for behandling av optimaliseringsprosessen.

De virkelige data, både fra SD-anlegg og tilleggsmålinger, har vært benyttet for praktisk forklaring av feilene i oppvarmingssystemet. En prosedyre for modellkalibrering basert på bruk av en optimaliseringsalgoritme som kobler sammen de virkelige data og en enkel varmebalansemodell har blitt foreslått. Tre konkrete driftsfeil i oppvarmingssystemet har blitt belyst gjennom bruk av denne varmebalansemodellen.

Flere regler for feilsøking og diagnostisering har blitt utviklet ved hjelp av simuleringsverktøyene EnergyPlus and TRNSYS. Denne utviklingen har bestått av tre ulike steg: testing av bestemte feil, beregning av ytelsesindikatorer og til slutt klassifisering av de observerte ytelsesindikatorer. Reglene har blitt utviklet for et system av aggregater for luftkjøling og for et vannbåret oppvarmingssystem. Reglene kan diagnostisere både styringsfeil og komponentfeil. Til slutt presenteres informasjon som er nyttig for drift av VVS-tekniske installasjoner i bygninger basert på en analyse av årsakene for og virkningene av de feil som er behandlet.

De viktigste konklusjonene er knyttet til praktisk kombinasjon av virkelige måleverdier og simuleringsverktøy. Informasjon fra det virkelig liv er helt nødvendig for å få en god forståelse av feil som oppstår i anlegg. Det er også vist at potensialet som ligger i alle de data som er tilgjengelige gjennom SD-anlegg, ikke er fullt utnyttet. Gjennom bruk av simuleringsverktøy kan styringsstrategiene alltid bli bedre tilpasset og innjustert til de virkelige behov i bygningen. Simuleringsverktøy kan også brukes for utvikling av prosedyrer for feilsøking og diagnostisering i VVS-tekniske anlegg. Disse prosedyrene kan brukes enten som en veileder for manuell feilsøking og detektering eller som grunnlag for utvikling av automatiserte algoritmer.

Paper II, VI and VII are reprinted with kind permission from Elsevier, sciencedirect.com

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OVERLY, TIMOTHY G. S. "DEVELOPMENT AND INTEGRATION OF HARDWARE AND SOFTWARE FOR ACTIVE-SENSORS IN STRUCTURAL HEALTH MONITORING." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1178813386.

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Bin, Hasan M. M. A. "Current based condition monitoring of electromechanical systems : model-free drive system current monitoring : faults detection and diagnosis through statistical features extraction and support vector machines classification." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5732.

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A non-invasive, on-line method for detection of mechanical (rotor, bearings eccentricity) and stator winding faults in a 3-phase induction motors from observation of motor line current supply input. The main aim is to avoid the consequence of unexpected failure of critical equipment which results in extended process shutdown, costly machinery repair, and health and safety problems. This thesis looks into the possibility of utilizing machine learning techniques in the field of condition monitoring of electromechanical systems. Induction motors are chosen as an example for such application. Electrical motors play a vital role in our everyday life. Induction motors are kept in operation through monitoring its condition in a continuous manner in order to minimise their off times. The author proposes a model free sensor-less monitoring system, where the only monitored signal is the input to the induction motor. The thesis considers different methods available in literature for condition monitoring of induction motors and adopts a simple solution that is based on monitoring of the motor current. The method proposed use the feature extraction and Support Vector Machines (SVM) to set the limits for healthy and faulty data based on the statistical methods. After an extensive overview of the related literature and studies, the motor which is the virtual sensor in the drive system is analysed by considering its construction and principle of operation. The mathematical model of the motor is used for analysing the system. This is followed by laboratory testing of healthy motors and comparing their output signals with those of the same motors after being intentionally failed, concluding with the development of a full monitoring system. Finally, a monitoring system is proposed that can detect the presence of a fault in the monitored machine and diagnose the fault type and severity

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