Дисертації: "Contact parameters"

1

Ozsahin, Orkun. "An Investigation On Dynamic Contact Parameters In Machining Center Spindle." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610084/index.pdf.

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In machining centers, with the increasing trends in high precision machining, chatter has become an important problem which results in poor surface finish and low material removal rate. Chatter can be avoided with stability diagrams which provide the stable regions in the machining process for the depth of cut and spindle speed combinations. In order to obtain stability diagrams, tool point frequency response function (FRF) of the system should be obtained. Throughout this study, contact parameters which are the most critical part of the analytical modeling of spindle-holder-tool assembly in order to obtain tool point FRF, are examined. For the accurate identification of the contact parameters, a recently suggested closed form approach based on measured FRFs is improved and applied to real structures by solving several application problems. In addition to the identification of contact parameters from experimental results, in order to eliminate the dependency on experiments, artificial neural networks are used to predict contact parameters for cases for which no experiments were carried out. By using trained neural network, contact parameters are predicted for the first seen combination of tool gauge length and diameter with a high accuracy. Such an application will have an important contribution to the machining stability studies since elimination of dependency on experiments will make it possible to predict stability diagrams for different combinations of spindle, holder and tool without performing any experiments. Additionally, since accurate identification of contact parameters, thus tool point FRFs and stability diagrams are highly dependent on accuracy of the performed experiments, possible errors due the mass of the accelerometers are also investigated. In order to compensate the mass effect of the accelerometers, a structural modification with matrix inversion method is applied to the accelerometer based results.

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2

McCloskey, Rosemary Martha. "Phylogenetic estimation of contact network parameters with approximate Bayesian computation." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58663.

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Models of the spread of disease in a population often make the simplifying assumption that the population is homogeneously mixed, or is divided into homogeneously mixed compartments. However, human populations have complex structures formed by social contacts, which can have a significant influence on the rate and pattern of epidemic spread. Contact networks capture this structure by explicitly representing each contact that could possibly lead to a transmission. Contact network models parameterize the structure of these networks, but estimating their parameters from contact data requires extensive, often prohibitive, epidemiological investigation. We developed a method based on approximate Bayesian computation (ABC) for estimating structural parameters of the contact network underlying an observed viral phylogeny. The method combines adaptive sequential Monte Carlo for ABC, Gillespie simulation for propagating epidemics though networks, and a previously developed kernel-based tree similarity score. Our method offers the potential to quantitatively investigate contact network structure from phylogenies derived from viral sequence data, complementing traditional epidemiological methods. We applied our method to the Barabási-Albert network model. This model incorporates the preferential attachment mechanism observed in real world social and sexual networks, whereby individuals with more connections attract new contacts at an elevated rate (“the rich get richer”). Using simulated data, we found that the strength of preferential attachment and the number of infected nodes could often be accurately estimated. However, the mean degree of the network and the total number of nodes appeared to be weakly- or non-identifiable with ABC. Finally, the Barabási-Albert model was fit to eleven real world HIV datasets, and substantial heterogeneity in the parameter estimates was observed. Posterior means for the preferential attachment power were all sub-linear, consistent with literature results. We found that the strength of preferential attachment was higher in injection drug user populations, potentially indicating that high-degree “superspreader” nodes may play a role in epidemics among this risk group. Our results underscore the importance of considering contact structures when investigating viral outbreaks.
Science, Faculty of
Graduate

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3

Gestlöf, Rikard, and Johannes Sörman. "Contact-free Cognitive Load Classification based on Psycho-Physiological Parameters." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-44695.

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Cognitive load (CL) is a concept that describes the relationship between the cognitive demands from a task and the environment the task is taking place in, which influences the user’s cognitive resources. High cognitive load leads to higher chance of a mistake while a user is performing a task. CL has great impact on driving performance, although the effect of CL is task dependent. It has been proven that CL selectively impairs non-automized aspects of driving performance while automized driving tasks are unaffected. The most common way of measuring CL is electroencephalography (EEG), which might be a problem in some situations since its contact-based and must be connected to the head of the test subject. Contact-based ways of measuring different physiological parameters can be a problem since they might affect the results of the research. Since the wirings sometimes might be loose and that the test subject moves etc. However, the biggest concern with contact-based systems is that they are hard to involve practically. The reason for this is simply that a user cannot relax, and that the sensors attached to the test subjects can affect them to not provide normal results. The goal of the research is to test the performance of data gathered with a contact-free camera-based system compared to a contact-based shimmer GSR+ system in detecting cognitive load. Both data collection approaches will extract the heart rate (HR) and interbeat interval (IBI) while test subjects perform different tasks during a controlled experiment. Based on the gathered IBI, 13 different heart rate variability (HRV) features will be extracted to determine different levels of cognitive load. In order to determine which system that is better at measuring different levels of CL, three major stress level phases were used in a controlled experiment. These three stress level phases were the reference point for low CL where test subjects sat normal (S0), normal CL where the test subjects performed easy puzzles and drove normally in a video game (S1) and high CL where the test subjects completed hard puzzles and drove on the hardest course of a video game while answering math questions (S2). To classify the extracted HRV features from the data into the three different levels of CL two different machine learning (ML) algorithms, support vector machine (SVM) and k-nearest-neighbor (KNN) were implemented. Both binary and multiclass feature matrixes were created with all combinations between the different stress levels of the collected data. In order to get the best classification accuracy with the ML algorithms, different optimizations such as kernelfunctions were chosen for the different feature matrixes. The results of this research proved that the ML algorithms achieved a higher classification accuracy for the data collected with the contact-free system than the shimmer sense system. The highest mean classification accuracy was 81% on binary classification for S0-S2 collected by the camera while driving using Fine KNN. The highest F1 score was 88%, which was achieved with medium gaussian SVM for the class combination S0-(S1/S2) feature matrix recorded with the camera system. It was concluded that the data gathered with the contact-free camera system achieved a higher accuracy than the contact-based system. Also, that KNN achieved the higher accuracy overall, than SVM for the data. This research proves that a contact-free camera-based system can detect cognitive better than a contact-based shimmer sense GSR+ system with a high classification accuracy.

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4

McQuaid, Grainne. "Development of non-contact 3D measurement of areal pavement texture parameters." Thesis, Ulster University, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.667769.

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5

Karim, Kh Nafis. "INTELLIGENT SYSTEM FOR MONITORING PHYSIOLOGICAL PARAMETERS USING CAMERA." Thesis, Mälardalens högskola, Inbyggda system, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-29834.

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Measuring physiological parameters or vital sign using camera has become popular in recent years. Contact-less monitoring and extraction of vital signs can be important source of information in situations like medical care system and safety control system. This paper presents the implementation of real-time, non-contact method for extraction of vital signs, heart rate in this case. A better face tracking method is used for efficient face detection. This study extends some of the previous works done and have a comparison study with several methods. The developed system used filtering with window over the green channel of the signal and then Converted to frequency domain to analyze the signal to detect heart rate. The developed system achieved high correlation and showed small error while referencing with actual heart signal from ECG. This method delivers better result in better light condition but gives fairly good result on lower light as well.

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6

Janakiraman, Venkatakrishna. "An Investigation of the Impact of Contact Parameters on the Wear Coefficient." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366906387.

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7

DE, MELIS MIRKO. "Cardiovascular parameters for healthy state assessment: an optical-based, non contact approach." Doctoral thesis, Università Politecnica delle Marche, 2008. http://hdl.handle.net/11566/242581.

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8

Fink, Barbara A. "Quantifying the effects of contact lens prescription parameters on human corneal oxygen uptake /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487331541709205.

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9

Zhang, Yilei. "The effect of surface roughness parameters on contact and wettability of solid surfaces." [Ames, Iowa : Iowa State University], 2007.

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10

Marchionni, Paolo, and Paolo Marchionni. "Non-contact techniques for the measurement of physiological parameters in neonatal intensive care units." Doctoral thesis, Università Politecnica delle Marche, 2011. http://hdl.handle.net/11566/242484.

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Lo scopo di questa tesi consiste nello sviluppo e nella costruzione di nuovi metodi di misura senza contatto per la valutazione di parametri fisiologici (saturazione del sangue, frequenza cardiaca, frequenza respiratoria, e temperatura) molto importanti all’interno di un reparto di terapia intensiva neonatale (NICU). In questo ultimi anni, come dimostrato in letteratura, è aumentato l’ interesse sui dispositivi senza contatto. La principale motivazione è quella di eliminare i rischi biologici, chimici ed elettrici, che sono sempre presenti quando un dispositivo medicale viene applicato su un paziente. Ciò è particolarmente evidente in pazienti ricoverati in un’unità di terapia intensiva; specialmente se nati pre-termine e perciò con l’apparato cardiaco/respiratorio non ancora del tutto formato e con le difese immunologiche basse. Le tesi è stata organizzata per esplorare e proporre soluzioni fattibili per misure senza contatto di parametri fisiologici nei pazienti pre-termine, quali: • Saturazione del sangue (SaO2) • Frequenza Cardiaca (HR) • Frequenza Respiratoria (RR) • Temperatura superficiale del paziente (T) SaO2 è generalmente affetta da numerosi falsi positivi dovuti all’errato posizionamento del pulso ossimetro oppure agli artefatti da movimento. Nel capitolo 4 è descritto ed implementato un metodo consolidato per l’eliminazione di dati saturimetrici erronei, l’algoritmo è stato applicato a 24 pazienti con un’acquisizione di 483 giorni, di cui più del 12% (equivalente a 58 giorni) sono risultati falsi e quindi da scartare. L’HR e la RR sono state misurate senza contatto su 8 pazienti, senza che questi fossero spostati dalle isole neonatali o dalle incubatrici. I dati raccolti sono stati rielaborati e validati con ECG e ventilatori, mostrando un’accuratezza della misura di ± 43 ms e ± 150 ms. Infine è stato progettato un nuovo metodo senza contatto per la misura della temperatura superficiale di pazienti NICU. Lo strumento usato è una termo camera IR che ha permesso di ottenere mappature termiche del soggetto in modo da avere un riscontro indiretto della termogenesi e dei parametri metabolici del paziente. Inoltre è stato costruito un modello per valutare e quantizzare i parametri vitali del paziente. I metodi descritti, permettono misure molto accurate e continue di parametri vitali, eliminando il contatto paziente-dispositivo biomedicale (fatta eccezione del pulso ossimetro), diminuendo significativamente il rischio biologico, chimico ed elettrico ritenuti molto gravi in pazienti presenti in NICU.
The main aim of this thesis is to design and develop novel measurement methods for the non-contact assessment of physiological quantities (oxygen saturation, heart rate, respiration rate and temperature) of importance in neonatal intensive care units (NICU). During the last decade, a growing interest on non-contact medical devices was testified by the literature; the reason is mainly due to the importance to eliminate the possible biological, chemical and electrical hazards always present when a medical device is used on a patient. This is particularly true on patients recovered in intensive care unit; especially if such patients are pre-born babies with low cardiac/respiration apparatus efficiency or reduced immunological defense systems. The work has been organized in order to explore and propose feasible solutions for the non-contact measurements of the following vital signs in pre-term patients: • Oxygen saturation (SaO2) • Heart rate (HR) • Respiration rate (RR) • Patient skin temperature (T) Oxygen saturation (SaO2) is typically affected by numerous fake values due to the non-optimal placement of the pulse oximeter or to movement artifacts. In chapter 4, a robust method for the rejection of the fake/erroneous values of SaO2 is described and implemented on 24 patient over 483 days period of time. More than 12% of erroneous data (equivalent to a 58 days period of time) have been individuated and rejected. Heart rate (HR) and respiration rate (RR) without any physical contact have been implemented on 8 patients maintained into thermal cribs or incubators. Data have been recorded, processed and compared with ECG and patient ventilator, showing an uncertainty of ± 43 ms and ± 150 ms. Finally a novel non-contact method for the measurement of the patient skin temperature (T) was designed and implemented for the use on NICU patients. An IR thermo-camera was used for determination of multi-point temperature determination with special attention on the indirect determination of thermogenesis and metabolic parameters of the patient. A specially devoted algorithm has been developed for the assessment and quantization of the patient parameters. The studied methods allow to perform the continuous and accurate measurement of important physiological parameters eliminating (a part from the pulse oxymeter) the contact between the patient and the medical devices and consequently reducing significantly the biological and electrical hazards risks which are particularly severe for NICU patients.

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11

Casaccia, Sara. "Measurement of physiological parameters in the human body by non-contact technique: Laser Doppler Vibrometry." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/243056.

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La misura senza contatto di segnali fisiologici e vitali ѐ uno dei fattori di maggior rilievo per la strumentazione biomedicale di nuova generazione. I metodi di misura con contatto di parametri fisiologici presentano dei limiti come l’invasività con la pelle, l’impossibilità di poter applicare gli elettrodi in particolari regioni corporee o in parti del corpo ristrette ed ѐ necessaria la collaborazione del soggetto. Per queste ragioni la Vibrometria Laser Doppler (LDV) ѐ stata introdotta per acquisire segnali associati all’attività biologica del corpo umano, per eliminare il contatto con la pelle e per rendere le prove più semplici. Questa tesi di dottorato si focalizza sull’utilizzo dell’LDV per la misura dell’attività cardiovascolare e muscolare in quanto sono parametri che permettono una valutazione dello stato di salute ed emozionale del soggetto sotto esame. Infatti, nella pratica clinica e giornaliera ѐ fondamentale la valutazione dei segnali vitali ed emozionali e la tecnologia LDV ha la capacità di misurare i movimenti vibrazionali della superficie corporea senza contatto, con una elevata sensibilità di acquisizione e ad una distanza notevole. Questo lavoro ha lo scopo di esplorare e dimostrare le capacità della Vibrometria Laser Doppler nel misurare la frequenza cardiaca con una incertezza di ± 9 ms rispetto alla tecnica convenzionale (elettrocardiografia) ed altri parametri cardiovascolari puntando il fascio laser sulla carotide. Infine, LDV viene usato anche per la misura delle proprietà di contrazione muscolare dei grandi e piccoli muscoli (muscoli facciali) con una accuratezza elevata sempre in confronto alla tecnica considerata gold standard (elettromiografia di superficie). La tecnica LDV, senza contatto, può dunque sostituire le tecnologie convenzionali, più invasive che richiedono l’applicazione di sensori sulla pelle del paziente e in questo modo si possono ottenere misurazioni di parametri cardiovascolari e muscolari completamente senza contatto andando a migliorare la qualità delle prove come interrogatori, controlli di sicurezza, controlli clinici e programmi di riabilitazione.
The measurements of physiological and vital signals without contact is a relevant research issue in modern biomedical instrumentation. Contact methods presently used to measure physiological parameters sometimes can be inconvenient or inadequate for patient comfort or to detect signals from particular body regions and the presence of cables is a limit for the patient mobility. For these reasons, the Laser Doppler Vibrometry (LDV) technique was introduced to acquire signals associated with biological activity in the human body, to avoid the contact with the skin and to make the tests easiest. This dissertation is focused on the novel use of LDV to measure cardiovascular and muscular activity to evaluate health and emotional state of participants. In fact, in daily and clinical practice is fundamental the assessment of vital and emotional signals and the LDV technique has the capability to measure the vibrational movements of the skin surface without contact, with a high sensitivity of acquisition and at a distance of several meters. In this work, the possibility to use LDV to measure the heart rate, with a deviation of ± 9 ms from the conventional gold standard method (electrocardiography) and other cardiovascular parameters assessed from the carotid artery are measured with LDV, will be explored and demonstrated. Finally, LDV is used to measure muscle contraction properties from the big and small muscles (facial muscles) with a high accuracy in confront of the gold standard method (surface electromyography). Using the non-contact LDV technique might provide surrogate measures for those obtained using conventional, more obtrusive assessment methods that require attached sensors and so, measurements of cardiovascular and muscular parameters without contact can improve tests as investigations, safety controls, clinical controls, rehabilitation programs.

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12

Cunha, Alex Pereira da. "A method for measuring contact angle and influence of surface fluid parameters on the boiling heat transfer performance /." Ilha Solteira, 2019. http://hdl.handle.net/11449/183048.

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Orientador: Elaine Maria Cardoso
Resumo: O avanço de novas tecnologias, associado à minimização dos custos de fabricação e instala-ção, constitui um grande desafio para a área de refrigeração, uma vez que a geração de calor tem aumentado gradativamente nos últimos anos. Assim, a busca de novos fluidos com pro-priedades térmicas superiores aos comumente usados tornou-se indispensável para melhorar a eficiência energética. Nas últimas décadas os nanofluidos - dispersões de partículas de escala nanométrica (1 a 100nm) em um fluido-base - têm atraído especial interesse não somente da comunidade acadêmica, mas também da indústria em áreas como: a microeletrônica, microflu-ídica, transporte, manufatura, assistência médica, entre outras. O melhor desempenho térmico e a vasta gama de aplicações fazem dos nanofluidos potenciais substitutos dos refrigerantes utilizados em diversos segmentos da engenharia. Dentro desse contexto, o presente trabalho teve como objetivos: o estudo teórico e experimental da influência das propriedades termofísi-cas e concentração de nanofluidos, bem como, das características geométricas da superfície aquecedora sobre o ângulo de contato e a molhabilidade. Também, atenção foi dada à prepa-ração e caracterização dos nanofluidos (Al2O3-água e Fe2O3-água), por meio da análise expe-rimental da condutividade térmica e da viscosidade dinâmica para diferentes concentrações; uma bancada experimental, para aquisição de imagens de gota séssil, foi construída a fim de viabilizar as análises de ângulo de conta... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The advance of new technologies, associated to the minimization of manufacturing and installation costs, presents a great challenge for the refrigeration area, since the heat generation has increased in recent years. Thus, the search for new fluids with thermal properties higher than those commonly used has become indispensable to improve energy efficiency. In recent decades, nanofluids-dispersions of nanometer-scale particles (1 to 100 nm) in a base fluid - have attracted special interest not only from the academic community but also from industry in areas such as microelectronics, microfluidics, transport, manufacturing, medical assistance, among others. In this context, the present work had the following goals: the theoretical and experimental study of the influence of thermophysical properties and nanofluid concentration, as well as the geometric characteristics of the heating surface on the contact angle and wetta-bility. Attention was also given to the preparation and characterization of nanofluids (Al2O3-water and Fe2O3-water) by the experimental analysis of thermal conductivity and dynamic viscosity for different concentrations; an experimental apparatus for the acquisition of sessile droplet images was designed in order to analyze the contact angle and wettability; and a computational routine was developed to obtain the drop profile and the surface-fluid interaction for the different nanofluids and surfaces used. Based on database, it was possible to evaluate the pre... (Complete abstract click electronic access below)
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13

Takahashi, Eigo. "Correlation between preparation parameters and properties of molybdenum back contact layer for CIGS thin film solar cells." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4554.

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Molybdenum (Mo) thin film back contact layers for thin film CuIn(subscript 1-x])Ga[subscript] xSe[sub]2 (CIGS) solar cells were deposited onto soda lime glass substrates using a direct current (DC) planar magnetron sputtering deposition technique. Requirements for the Mo thin film as a back contact layer for CIGS solar cells are various. Sheet resistance, contact resistance to the CIGS absorber, optical reflectance, surface morphology, and adhesion to the glass substrate are the most important properties that the Mo thin film back contact layer must satisfy. Experiments were carried out under various combinations of sputtering power and working gas pressure, for it is well known that mechanical, morphological, optical, and electrical property of a sputter-deposited Mo thin film are dependent on these process parameters. Various properties of each Mo film were measured and discussed. Sheet resistances were measured using a four-point probe equipment and minimum value of 0.25 [omega]/sq was obtained for the 0.6 [micro]meter-thick Mo film. Average surface roughnesses of each Mo film ranged from 15 to 26 A were measured by Dektak profilometer which was also employed to measure film thicknesses. Resistivities were calculated from the sheet resistance and film thickness of each film. Minimum resistivity of 11.9 mu [omega]cm was obtained with the Mo thin film deposited at 0.1 mTorr and 250 W. A residual stress analysis was conducted with a bending beam technique with very thin glass strips, and maximum tensile stress of 358 MPa was obtained; however, films did not exhibit a compressive stress. Adhesive strengths were examined for all films with a "Scotch-tape" test, and all films showed a good adhesion to the glass substrate.; Sputter-deposited Mo thin films are commonly employed as a back contact layer for CIGS and CuInSe[sub]2 (CIS)-based solar cells; however, there are several difficulties in fabricating a qualified back contact layer. Generally, Mo thin films deposited at higher sputtering power and lower working gas pressure tend to exhibit lower resistivity; however, such films have a poor adhesion to the glass substrate. On the other hand, films deposited at lower power and higher gas pressure tend to have a higher resistivity, whereas the films exhibit an excellent adhesion to the glass substrate. Therefore, it has been a practice to employ multi-layered Mo thin film back contact layers to achieve the properties of good adhesion to the glass substrate and low resistivity simultaneously. However, multi layer processes have a lower throughput and higher fabricating cost, and requires more elaborated equipment compared to single layer processes, which are not desirable from the industrial point of view. As can be seen, above mentioned process parameters and the corresponding Mo thin film properties are at the two extreme ends of the spectrum. Hence experiments were conducted to find out the mechanisms which influence the properties of Mo thin films by changing the two process parameters of working gas pressure and sputtering power individually. The relationships between process parameters and above mentioned properties were studied and explained. It was found that by selecting the process parameters properly, less resistive, appropriate-surfaced, and highly adhesive single layer Mo thin films for CIGS solar cells can be achieved.
ID: 028916841; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.S.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 97-111).
M.S.M.S.E.
Masters
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science and Engineering

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14

Jaza, Rabii. "Towards a prediction of the tribological behaviour of a contact with third body particles : Relating the morphological descriptors of the third body particles with the rheological parameters of the contact." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI023.

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Ce travail de thèse est une preuve de concept. C'est la première partie d'un travail beaucoup plus vaste où nous essayons de répondre à la question de savoir s'il est possible d'établir un lien entre les aspects morphologiques des particules du troisième corps et les paramètres rhéologiques du contact où ils ont été créés. Les mesures rhéologiques sont presque impossibles à obtenir sans ouvrir le contact lui-même. Par conséquent, un tel lien pourrait changer la donne, en particulier dans la surveillance des machines et la prévision des pannes, ce qui est l'objectif à long terme de ce projet. Dans cet effort, nous évaluons l'efficacité des algorithmes d'apprentissage automatique supervisé pour relier les particules du troisième corps aux tests dont elles proviennent. De plus, nous évaluons la capacité des algorithmes à prédire les propriétés rhéologiques du contact à partir des descripteurs morphologiques des débris d'usure qu'il a produits. Nous avons effectué nos propres tests tribologiques à l'aide d'un tribomètre à disque à broches classique. Pour assurer la production de diverses particules du troisième corps, nous effectuons neuf tests organisés en trois séries. Une condition expérimentale variait entre les tests d'un ensemble donné. Les paramètres rhéologiques de ce projet ont été calculés directement à partir des signaux in situ enregistrés lors des tribotests. Ce ne sont pas les mesures habituelles mais ce sont des mesures mécaniques qui décrivent le flux des débris d'usure. Concernant l'ensemble de données morphologiques, nous avons choisi cinq descripteurs différents pour caractériser les particules post mortem après la fin des tests tribologiques. Ces descripteurs sont calculés grâce à des algorithmes d'analyse d'images d'images SEM. Les algorithmes d'apprentissage automatique avaient un taux de réussite de 40% à l'apprentissage à partir duquel le test de chaque particule a été créé en utilisant uniquement les descripteurs de forme. Cependant, les résultats de la prévision des paramètres rhéologiques à partir de la base de données morphologiques n'étaient pas aussi prometteurs, mais ils étaient essentiels pour les travaux futurs
This thesis work is a proof of concept. It is the first part of a much larger work where we try to answer the question whether it is possible to set a link between the morphological aspects of the third body particles and the rheological parameters of the contact where they were created. The rheological measurements are almost impossible to obtain without opening the contact itself. Therefore, such a link could be a game changer especially in machine monitoring and failure prediction, which is the long-term goal of this project. In this effort, we evaluate the efficiency of supervised machine learning algorithms in linking back the third body particles with the tests from which they originate. In addition, we assess the ability of the algorithms in predicting the rheological properties of the contact from the morphological descriptors of the wear debris it produced. We held our own tribological tests using a classical pin-disk tribometer. To ensure the production of diverse third body particles, we conduct nine tests organized in three sets. One experimental condition was varied between the tests of a give set. The rheological parameters in this project were calculated directly from the in situ signals recorded during the tribotests. They are are not the usual measures but they are mechanical measurement that describe the flow of the wear debris. Regarding the morphological dataset, we chose five different descriptors to characterize the particles post mortem after the tribological tests were terminated. Those descriptors are calculated through image analysis algorithms of SEM images. Machine learning algorithms had a 40% success rate at learning from in which test each particle was created using only the shape descriptors. However, the results of predicting the rheological parameters from the morphological database were not as promising however they were essential for the future work

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15

Bhatt, Rita. "Growth and Characterization of ZnO for the Front Contact of Cu(In,Ga)Se2." Scholar Commons, 2000. http://scholarcommons.usf.edu/etd/3840.

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ZnO window layers for CIGS solar cells are grown with a DC sputtering technique instead of a conventional RF sputtering technique. Transparent window layers and buffer layers are sputtered from the Zn target in the presence of Oxygen. The window layer is doped with Aluminum in order to achieve high electrical conductivity and thermal stability. The effect of different sputtering parameters on the electrical and optical properties of the films is elaborately studied. Sets of annealing experiments are also performed. Combinations of different deposition parameters are examined to design the optimum fabrication conditions. We are able to deposit 85% transparent, Al doped ZnO films having 002-axis orientation and 4e-4 ohm-cm resistivity, which is successfully, used on CIGS solar cells. Resistivity of undoped ZnO buffer layers is varied form 10-2 ohm-cm to unmeasurable by varying the sputtering parameters. The performance of a reactively sputtered window layer and a buffer layer have matched the performance of the RF sputtered ZnO on CIGS solar cells. There has been considerable effort to eliminate Chemical Bath Deposition of the CdS buffer layer from CIS solar cell fabrication. The performance of an undoped DC sputtered ZnO layer is examined on Cd free CIGS solar cells. The ZnO buffer layer is directly sputtered on an underlying CIGS material. The performance of Cd free solar cells is highly susceptible to the presence of Oxygen in the sputtering ambient of the buffer layer deposition [6]. As Oxygen is a growth component in reactive sputtering, the growth mechanisms of the DC-sputtered buffer layer are studied to improve the understanding. The performance of all reactively sputtered ZnO devices matched the values reported in the literature and the results for DC sputtered ZnO on Cd-free solar cells were encouraging.

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16

BERNACCHIA, NATASCIA. "Measurement techniques based on image processing for the assessment of biomedical parameters." Doctoral thesis, Università Politecnica delle Marche, 2014. http://hdl.handle.net/11566/242751.

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L’imaging biomedicale rappresenta un tema importante nel settore della diagno-si e della ricerca clinica. I software per l’analisi delle immagini permettono di individuare automaticamente informazioni non visibili all’occhio umano. Lo sviluppo tecnologico e l'u-so di diverse modalità di imaging aprono una sfida circa la necessità di analizzare un volu-me significativo di immagini per garantire informazioni di alta qualità per diagnosi, tratta-mento e monitoraggio, in strutture cliniche così come a casa. I sistemi di misura comunemente impiegati in ambiente clinico richiedono il contatto con il soggetto, provocando discomfort e risultando non adatti per tempi di osservazione lunghi. D'altra parte, il contatto può alterare la forma, la composizione dei campioni, e tecniche al-lo stato dell'arte potrebbero richiedere molto tempo e fornire bassa risoluzione. Questa tesi di dottorato presenta una serie di applicazioni sperimentali originali dell’analisi di immagini in campo biomedicale. L'obiettivo è quello di sviluppare e validare nuove me-todologie, basate sull’analisi di immagini, per la misura senza contatto di grandezze di di-versa natura. Lo studio tratta come prima applicazione l'estrazione di caratteristiche morfologiche di ag-gregati cellulari per studiare i processi di rigenerazione in cuori infartuati, poi lo sviluppo di una metodologia senza contatto per la misura delle proprietà meccaniche dei tendini rotulei di coniglio sottoposti a prove di trazione, e di metodi innovativi per il monitoraggio dei pa-rametri fisiologici (frequenza cardiaca e respiratoria, variazioni di volume del torace) usan-do sistemi quali il dispositivo Kinect ™ e una camera digitale. I banchi sperimentali, progettati in questo lavoro, sono stati validati, ottenendo un'elevata correlazione rispetto ai metodi di riferimento. I sistemi, seppur diversi per molti aspetti, hanno dimostrato di essere adatti ai rispettivi compiti, confermando la fattibilità dell’approccio basato sull’imaging biomedicale.
Biomedical imaging represents an important topic in the field of diagnosis and clinical research. Image analysis and processing software also helps to automatically identify what might not be apparent to the human eye. The technological development and the use of different imaging modalities create more challenges, as the need to analyse a significant volume of images so that high quality information can be produced for disease diagnosis, treatment and monitoring, in clinical structures as well as at home. All the measurement systems routinely used in clinical environment require to be put in di-rect contact with the subject, which in some cases can be uncomfortable or even non-suited for long monitoring. On the other hand, in some cases contact could alter shape or composition of the samples under study, and state-of-the-art techniques could require a lot of time and provide very low resolution. This doctoral thesis presents a series of new experimental applications of the image analysis and processing in the biomedical field. The aim was to develop and validate new method-ologies, based on image analysis, for non contact measurement of quantities of different nature. The study is focused on the extraction of morphological characteristics of cell ag-gregates to assess of the regeneration processes in infarcted hearts, the design of a non con-tact methodology to measure mechanical properties of rabbit patellar tendons subjected to tensile tests, the development of new methods for the monitoring of physiological parame-ters (heart and respiration rate, chest volume variations) through the use of image acquisi-tion systems, as Kinect™ device and a digital camera. The experimental setups, designed in this work, were validated, showing high correlation respect to the reference methods. Imaging systems, although so different in many aspects, have demonstrated to be suitable for the respective tasks, confirming the feasibility of the imaging approach in the biomedical field.

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17

Baird, Patrick James Samuel. "Mathematical modelling of the parameters and errors of a contact probe system and its application to the computer simulation of coordinate measuring machines." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320548.

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18

Piroti, Shwana, and Jesper Eriksson. "Friction Modeling in FE Simulation : Identification of Friction Model Parameters in Airbag and Crash Dummy Head Contact through Simulation and Experimental Data Response Correlation." Thesis, KTH, Hållfasthetslära (Avd.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232473.

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Motor vehicle-traﬃc accidents are a common cause of traumatic brain injuries, resulting in severe and sustaining disabilities, or even fatality. In an eﬀort to mitigate injuries related to vehicle crashes, various safety systems such as the occupant airbag has been implemented. In angled impacts, occupant interaction with the airbags can lead to head rotation, and during recent years head rotation has been emphasized as an important contributor to head injury risk. Therefore, for prediction of head injury risk in crash simulations it is important to correctly model the friction force which arises in the contact between occupants and the car interior. The aim of this thesis is therefore to study the friction within such a system. More speciﬁcally, the analysis is focusing on dummy head to airbag interaction and to correlate a three parameter friction model for this contact pair, as well as a one parameter model currently used by Volvo Car Group, with measured laboratory test data in the software LS-DYNA.A preliminary study in LS-DYNA was conducted to determine the conﬁguration of the laboratory setup consisting of a statically inﬂated customized driver airbag and a crash dummy head being launched to impact the airbag. The laboratory test data was analyzed using linear regression and Students T-test to identify the inﬂuence of parameters on the measured responses. The simulation model was then modiﬁed to represent the laboratory setup, prior to an optimization study performed to correlate simulation and laboratory test data responses. Lastly, an evaluation study was made to test whether or not the proposed friction model could improve occupant crash simulations.It was found in the thesis study that the friction force had a large eﬀect on the rotation of the head around the vertical axis (z−axis in the anatomical coordinate system of the head). The experimental data showed that the internal pressure of the airbag had little eﬀect on the response. This was likely due to the studied pressures being large enough for the airbag to be so stiﬀ that no plowing eﬀect of the dummy head moving through the airbag fabric could be seen. Furthermore, results from the optimization study indicated that the model correlation was improved when a three parameter friction model with velocity dependence was used. This implies that the friction coeﬃcient is dependent on the velocity. It was also shown that material properties aﬀecting friction behavior vary between diﬀerent crash dummy heads, as well as diﬀerent surface coating. Both dummy T-shirt fabric and grease paint resulted in signiﬁcantly lower surface friction.Due to the diﬀerence in friction for diﬀerent dummy heads, a single set of friction model parameter values that describes the friction behavior of all crash dummy heads does not exist. The study ﬁnds that when sliding is present in a contact, a three parameter model for describing the friction improves the correlation, as it can account for the velocity dependence of the friction in the contact. In contrast, when sliding is not present the one parameter and the three parameter model give similar results.Keywords: friction, velocity dependent friction coeﬃcient, ﬁnite element analysis, car crash simulation, Volvo Cars, crash test dummy head, driver airbag, LS-DYNA, laboratory testing, optimization study.

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19

Spaulding, Jeremy Maximillian. "Effects of Age on Gait Parameters and Muscle Activity During Adjustment, and the Relationship of Fear of Falling." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/42015.

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Previous research has shown that with advancing age, there are increasing incidences of slip and fall injuries. Understanding mechanisms associated with gait adjustments across a known slippery surface may help in proactively avoiding slips and falls. The primary goal of this study involved examination of gait parameters and muscle activity characteristics of the lower extremities during two different walking conditions. Research has shown that both physical and mental changes accompany the aging process in humans. Moreover, research has shown that emotions and physiological responses are related. A secondary goal of this study was to examine the relationships of fear of falling with gait parameters and muscle activity. This study consisted of exposing 14 younger and 14 older participants to controlled slippery conditions safely, while studying normal and adjusted gait characteristics (friction requirement, heel contact velocity, and step length) and muscle activity characteristics (Integrated EMG). First, a baseline measure was done to study normal gait prior to any exposure to slipping. A second measure was done following a slip from a contaminated floor surface, but before the initiation of a second slip. The results indicate that there were significant gait parameter differences between younger and older participants for both walking conditions. Results also indicate that there were differences in muscle activity between to the two age groups for the adjusted condition. Findings suggest that older individuals require an additional step to properly adjust gait for a contaminated walking surface.
Master of Science

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20

Vespalec, Vítězslav. "Hodnocení kvality vývrtu brokové hlavně." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232160.

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The diploma thesis deals with the issue of a quality assessment of a bore of shotgun barrels. There are mentioned both definitions of a quality shotgun barrel and also a quality of shotgun barrel bore. In conclusion, there are presented particular proposals for evaluation of parameters of surface texture of forged shotgun barrel blanks.

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21

Bercht, Bernardo Stefano. "Avaliação do endotélio da córnea de chinchilas ( chinchilla Lanigera) em diferentes faixas etárias utilizando a microscopia especular." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/79479.

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O endotélio é uma monocamada de células achatadas, poligonais e interligadas que recobrem a superfície posterior da córnea, sendo fundamental na manutenção da transparência desta estrutura. Embora as chinchilas (Chinchilla lanigera) sejam utilizadas em pesquisas oftálmicas, não existem dados referentes ao endotélio da córnea nesta espécie. Portanto, objetivou-se avaliar a densidade celular, a paquimetria, a área celular média e a morfologia do endotélio da córnea de chinchilas em diferentes faixas etárias. Foram estudados 60 bulbos oculares de 30 chinchilas, machos ou fêmeas, de diferentes faixas etárias. As chinchilas foram subdivididas em três grupos com 10 animais cada, designados por: G I (animais com idade entre dois a quatro meses); G II (animais com 11 meses de idade) e G III (animais com quatro anos de idade). A densidade celular endotelial média nos animais dos grupos G I, G II e G III foi de respectivamente 3385,39 ± 507,53, 2565,51 ± 220,46 e 1812,82 ± 117,92 células/mm2. A área celular média foi de respectivamente 301,51 ± 43,94, 392,46 ± 33,34 e de 553,79 ± 35,70 μm2 para G I, G II e G III. Os resultados apontam decréscimo da densidade, do pleomorfismo, e aumento da área celular média com o aumento da idade. A espessura da córnea aumentou em animais mais velhos. Conclui-se que o endotélio da córnea de chinchilas sofre alterações com o avanço da idade.
The corneal endothelium is a monolayer of interconnected flattened polygonal cells that cover the back surface of the cornea, it is essential for the maintenance of its transparency. Due to the complete lack of data on the endothelial cells of chinchilla (Chinchilla lanigera) and its possible use as an animal model in ophthalmic research, the objective was to evaluate the cellular density, pachymetry, the average cell area and morphology of the corneal endothelium of chinchillas in different age groups. It was studied 60 eyes of 30 chinchillas, male or female, of different ages. Chinchillas were divided into three groups with 10 animals each, designated by: G I (animals aged two to four months), G II (animals with 11 months) and G III (animals with four years of age). The mean endothelial cell density in the animals of G I, G II and G III were respectively 3385,39 ± 507,53, 2565,51 ± 220,46 and 1812,82 ± 117,92 cells/mm2. The average cell area was respectively 301,51 ± 43,94, 392,46 ± 33,34 and 553,79 ± 35,70 μm2 for GI, G II and G III. The results indicate a decrease in density, pleomorphism, and increased in average cell area with increasing age. Corneal thickness increased in older animals. The corneal endothelium of chinchillas changes with advancing age.

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22

Brambatti, Gustavo. "Avaliação do endotélio da córnea de coelhos (oryctolagus cuniculus) em diferentes faixas etárias utilizando a microscopia especular." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/142886.

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O endotélio é uma monocamada de células achatadas, poligonais e interligadas que recobrem a superfície posterior da córnea, sendo fundamental na manutenção da transparência desta estrutura. Apesar dos coelhos (Orictolagus cuniculus) serem amplamente utilizados em pesquisas oftálmicas, não existem avaliações detalhadas referentes ao endotélio da córnea desta espécie em diferentes idades. Objetivou-se estudar os parâmetros morfológicos e morfométricos do endotélio da córnea de coelhos de diferentes idades, utilizando-se a microscopia especular. Foram estudados 36 bulbos oculares de 18 coelhos, machos ou fêmeas, de diferentes faixas etárias divididos em três grupos com seis animais cada, designados por: G I (animais com idade de seis meses); G II (animais com 1 ano de idade) e G III (animais com quatro anos de idade). A densidade celular endotelial média nos animais dos grupos G I, G II e G III foi de respectivamente 2307,16± 319,04, 1894,75 ± 170,81 e 1818,66 ± 245,11 células/mm2. A área celular média foi de respectivamente 364,43 ± 39,36, 374,79 ± 48,46 e de 378.50 ± 02,97 μm2 para G I, G II e G III. O pleomorfismo médio ou porcentagem de células hexagonais no endotélio central do olho direito e esquerdo de coelhos foi respectivamente de 65,40 ± 23,39% e de 75,15 ± 10,44%, com variação de 42,01 a 88,80% e de 60,71 a 81,60%. Os resultados apontam decréscimo da densidade, do pleomorfismo, e aumento da área celular média com o aumento da idade. O endotélio da córnea de coelhos sofre alterações decorrentes do avanço da idade.
The corneal endothelium is a monolayer of interconnected flattened polygonal cells that cover the back surface of the cornea, it is essential for the maintenance of its transparency. Due to the complete lack of data on the endothelial cells of rabbits (Orictolagus cuniculus) it`s ophthalmic widely used in research, no data relating to corneal endothelium in this species correlating their age. Therefore aimed to assess cell density, the average cell area and morphology of the corneal endothelium of rabbits at different ages. It was studied 36 eyes of 18 rabbits, male or female, of different ages. Rabbits were divided into three groups with 6 animals each, designated by: G I (animals aged six months), G II (animals with 1 year) and G III (animals with four years of age). The mean endothelial cell density in the animals of G I, G II and G III were respectively 2307,16± 319,04, 1894,75 ± 170,81 e 1818,66 ± 245,11 células/mm2. The average cell area was respectively 364,43 ± 39,36, 374,79 ± 48,46 e de 378.50 ± 02,97 μm2 for GI, G II and G III. The pleomorphism medium or percentage of hexagonal cells in the endothelium of the central right and left eyes of rabbits was respectively 65.40 ± 23.39% and 75.15 ± 10.44%, ranging from 42.01 to 88.80 %, and 60.71 to 81.60%. The results indicate a decrease in density, pleomorphism, and increased in average cell area with increasing age. The corneal endothelium of rabbits changes with advancing age.

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23

Lee, Hyunwook. "A Polynomial Chaos Approach for Stochastic Modeling of Dynamic Wheel-Rail Friction." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77195.

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Accurate estimation of the coefficient of friction (CoF) is essential to accurately modeling railroad dynamics, reducing maintenance costs, and increasing safety factors in rail operations. The assumption of a constant CoF is popularly used in simulation studies for ease of implementation, however many evidences demonstrated that CoF depends on various dynamic parameters and instantaneous conditions. In the real world, accurately estimating the CoF is difficult due to effects of various uncertain parameters, such as wheel and rail materials, rail roughness, contact patch, and so on. In this study, the newly developed 3-D nonlinear CoF model for the dry rail condition is introduced and the CoF variation is tested using this model with dynamic parameters estimated from the wheel-rail simulation model. In order to account for uncertain parameters, a stochastic analysis using the polynomial chaos (poly-chaos) theory is performed using the CoF and wheel-rail dynamics models. The wheel-rail system at a right traction wheel is modeled as a mass-spring-damper system to simulate the basic wheel-rail dynamics and the CoF variation. The wheel-rail model accounts for wheel-rail contact, creepage effect, and creep force, among others. Simulations are performed at train speed of 20 m/s for 4 sec using rail roughness as a unique excitation source. The dynamic simulation has been performed for the deterministic model and for the stochastic model. The dynamics results of the deterministic model provide the starting point for the uncertainty analysis. Six uncertain parameters have been studied with an assumption of 50% uncertainty, intentionally imposed for testing extreme conditions. These parameters are: the maximum amplitude of rail roughness (MARR), the wheel lateral displacement, the track stiffness and damping coefficient, the sleeper distance, and semi-elliptical contact lengths. A symmetric beta distribution is assumed for these six uncertain parameters. The PDF of the CoF has been obtained for each uncertain parameter study, for combinations of two different uncertain parameters, and also for combinations of three different uncertain parameters. The results from the deterministic model show acceptable vibration results for the body, the wheel, and the rail. The introduced CoF model demonstrates the nonlinear variation of the total CoF, the stick component, and the slip component. In addition, it captures the maximum CoF value (initial peak) successfully. The stochastic analysis results show that the total CoF PDF before 1 sec is dominantly affected by the stick phenomenon, while the slip dominantly influences the total CoF PDF after 1 sec. Although a symmetric distribution has been used for the uncertain parameters considered, the uncertainty in the response obtained displayed a skewed distribution for some of the situations investigated. The CoF PDFs obtained from simulations with combinations of two and three uncertain parameters have wider PDF ranges than those obtained for only one uncertain parameter. FFT analysis using the rail displacement has been performed for the qualitative validation of the stochastic simulation result due to the absence of the experimental data. The FFT analysis of the deterministic rail displacement and of the stochastic rail displacement with uncertainties demonstrates consistent trends commensurate with loss of tractive efficiency, such as the bandwidth broadening, peak frequency shifts, and side band occurrence. Thus, the FFT analysis validates qualitatively that the stochastic modeling with various uncertainties is well executed and is reflecting observable, real-world results. In conclusions, the development of an effective model which helps to understand the nonlinear nature of wheel-rail friction is critical to the progress of railroad component technology and rail safety. In the real world, accurate estimation of the CoF at the wheel-rail interface is very difficult since it is influenced by several uncertain parameters as illustrated in this study. Using the deterministic CoF value can cause underestimation or overestimation of CoF values leading to inaccurate decisions in the design of the wheel-rail system. Thus, the possible PDF ranges of the CoF according to key uncertain parameters must be considered in the design of the wheel-rail system.
Ph. D.

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Beiki, Majid. "New Techniques for Estimation of Source Parameters : Applications to Airborne Gravity and Pseudo-Gravity Gradient Tensors." Doctoral thesis, Uppsala universitet, Geofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-143015.

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Gravity gradient tensor (GGT) data contains the second derivatives of the Earth’s gravitational potential in three orthogonal directions. GGT data can be measured either using land, airborne, marine or space platforms. In the last two decades, the applications of GGT data in hydrocarbon exploration, mineral exploration and structural geology have increased considerably. This work focuses on developing new interpretation techniques for GGT data as well as pseudo-gravity gradient tensor (PGGT) derived from measured magnetic field. The applications of developed methods are demonstrated on a GGT data set from the Vredefort impact structure, South Africa and a magnetic data set from the Särna area, west central Sweden. The eigenvectors of the symmetric GGT can be used to estimate the position of the causative body as well as its strike direction. For a given measurement point, the eigenvector corresponding to the maximum eigenvalue points approximately toward the center of mass of the source body. For quasi 2D structures, the strike direction of the source can be estimated from the direction of the eigenvectors corresponding to the smallest eigenvalues. The same properties of GGT are valid for the pseudo-gravity gradient tensor (PGGT) derived from magnetic field data assuming that the magnetization direction is known. The analytic signal concept is applied to GGT data in three dimensions. Three analytic signal functions are introduced along x-, y- and z-directions which are called directional analytic signals. The directional analytic signals are homogenous and satisfy Euler’s homogeneity equation. Euler deconvolution of directional analytic signals can be used to locate causative bodies. The structural index of the gravity field is automatically identified from solving three Euler equations derived from the GGT for a set of data points located within a square window with adjustable size. For 2D causative bodies with geometry striking in the y-direction, the measured gxz and gzz components of GGT can be jointly inverted for estimating the parameters of infinite dike and geological contact models. Once the strike direction of 2D causative body is estimated, the measured components can be transformed into the strike coordinate system. The GGT data within a set of square windows for both infinite dike and geological contact models are deconvolved and the best model is chosen based on the smallest data fit error.
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 730

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25

Mackay, Allen B. "Large-Displacement Linear-Motion Compliant Mechanisms." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/901.

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Linear-motion compliant mechanisms have generally been developed for small displacement applications. The objective of the thesis is to provide a basis for improved large-displacement linear-motion compliant mechanisms (LLCMs). One of the challenges in developing large-displacement compliant mechanisms is the apparent performance tradeoff between displacement and off-axis stiffness. In order to facilitate the evaluation, comparison, and optimization of the performance of LLCMs, this work formulates and presents a set of metrics that evaluates displacement and off-axis stiffness. The metrics are non-dimensionalized and consist of the relevant characteristics that describe mechanism displacement, off-axis stiffness, actuation force, and size. Displacement is normalized by the footprint of the device. Transverse stiffness is normalized by a new performance characteristic called virtual axial stiffness. Torsional stiffness is normalized by a performance characteristic called the characteristic torque. Because large-displacement compliant mechanisms are often characterized by non-constant axial and off-axis stiffnesses, these normalized stiffness metrics are formulated to account for the variation of both axial and off-axis stiffness over the range of displacement. In pursuit of mechanisms with higher performance, this work also investigates the development of a new compliant mechanism element. It presents a pseudo-rigid-body model (PRBM) for rolling-contact compliant beams (RCC beams), a compliant element used in the RCC suspension. The loading conditions and boundary conditions for RCC beams can be simplified to an equivalent cantilever beam that has the same force-deflection characteristics as the RCC beam. Building on the PRBM for cantilever beams, this paper defines a model for the force-deflection relationship for RCC beams. Included in the definition of the RCC PRBM are the pseudo-rigid-body model parameters that determine the shape of the beam, the length of the corresponding pseudo-rigid-body links and the stiffness of the equivalent torsional spring. The behavior of the RCC beam is parameterized in terms of a single parameter defined as clearance, or the distance between the contact surfaces. The RCC beams exhibit a unique force-displacement curve where the force is inversely proportional to the clearance squared. The RCC suspension is modeled using the newly defined PRBM. The suspension exhibits unique performance, generating no resistance to axial motion while providing significant off-axis stiffness. The mechanism has a large range of travel and operates with frictionless motion due to the rolling-contact beams. In addition to functioning as a stand-alone linear-motion mechanism, the RCC suspension can be configured with other linear mechanisms in superposition to improve the off-axis stiffness of other mechanisms without affecting their axial resistance.

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Скуріхін, Владислав Ігорович. "Розвиток ресурсозберігаючих технологій раціонального струмознімання на міському електротранспорті". Thesis, Харківський національний університет міського господарства ім. О. М. Бекетова, 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/19886.

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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.22.09 – електротранспорт; Національний технічний університет "Харківський політехнічний інститут", Харків, 2015 р. Дисертаційна робота присвячена вирішенню актуальної науково-практичної задачі – розвитку ресурсозберігаючих технологій раціонального струмознімання на міському електротранспорті за рахунок застосування в системі струмознімання альтернативних матеріалів і удосконаленої конструкції сталеалюмінієвого контактного проводу. Проведено математичне моделювання процесів зношування деталей та вузлів транспортних засобів. Досліджено процеси, які відбуваються в контакті "струмоприймач-контактний провід" та доведено можливість застосування перспективного контактного проводу в контактній мережі міського електротранспорту. Розроблено конструкцію пристрою для фізичного моделювання основних параметрів струмознімання для випробування контактних проводів і струмоприймачів різних конструкцій.
Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.22.09 - Electrical Transport. - National Technical University "Kharkiv Politechnical Institute", Kharkiv, 2015. The dissertation is devoted to solving actual scientific and practical task – development of resource-saving technologies rational of current collection by a city electric vehicle through the use of alternative materials and improved construction of a contact wire. Mathematical modeling of the wear of the parts and components of vehicles. The processes that occur in contact "pantograph-contact wire" and proved the possibility of application promising contact wires of the contact network of city electric transport. Developed the design of the device for physical modeling of main parameters of current collection for testing contact wires and current collectors of different designs.

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Скуріхін, Владислав Ігорович. "Розвиток ресурсозберігаючих технологій раціонального струмознімання на міському електротранспорті". Thesis, Харківський національний університет міського господарства ім. О. М. Бекетова, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/19875.

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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.22.09 – електротранспорт; Національний технічний університет "Харківський політехнічний інститут", Харків, 2015 р. Дисертаційна робота присвячена вирішенню актуальної науково-практичної задачі – розвитку ресурсозберігаючих технологій раціонального струмознімання на міському електротранспорті за рахунок застосування в системі струмознімання альтернативних матеріалів і удосконаленої конструкції сталеалюмінієвого контактного проводу. Проведено математичне моделювання процесів зношування деталей та вузлів транспортних засобів. Досліджено процеси, які відбуваються в контакті "струмоприймач-контактний провід" та доведено можливість застосування перспективного контактного проводу в контактній мережі міського електротранспорту. Розроблено конструкцію пристрою для фізичного моделювання основних параметрів струмознімання для випробування контактних проводів і струмоприймачів різних конструкцій.
Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.22.09 - Electrical Transport. - National Technical University "Kharkiv Politechnical Institute", Kharkiv, 2015. The dissertation is devoted to solving actual scientific and practical task – development of resource-saving technologies rational of current collection by a city electric vehicle through the use of alternative materials and improved construction of a contact wire. Mathematical modeling of the wear of the parts and components of vehicles. The processes that occur in contact "pantograph-contact wire" and proved the possibility of application promising contact wires of the contact network of city electric transport. Developed the design of the device for physical modeling of main parameters of current collection for testing contact wires and current collectors of different designs.

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Ben-Naser, Abdusalam. "Measurement of range of motion of human finger joints, using a computer vision system." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/12531.

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Assessment of finger range of motion (ROM) is often required for monitoring the effectiveness of rehabilitative treatments and for evaluating patients' functional impairment. There are several devices which are used to measure this motion, such as wire tracing, tracing onto paper and mechanical and electronic goniometry. These devices are quite cheap, excluding electronic goniometry; however the drawbacks of these devices are their lack of accuracy and the time- consuming nature of the measurement process. The work described in this thesis considers the design, implementation and validation of a new medical measurement system utilized in the evaluation of the range of motion of the human finger joints instead of the current measurement tools. The proposed system is a non-contact measurement device based on computer vision technology and has many advantages over the existing measurement devices. In terms of accuracy, better results are achieved by this system, it can be operated by semi-skilled person, and is time saving for the evaluator. The computer vision system in this study consists of CCD cameras to capture the images, a frame-grabber to change the analogue signal from the cameras to digital signals which can be manipulated by a computer, Ultra Violet light (UV) to illuminate the measurement space, software to process the images and perform the required computation, a darkened enclosure to accommodate the cameras and UV light and to shield the working area from any undesirable ambient light. Two calibration techniques were used to calibrate the cameras, Direct Linear Transformation and Tsai. A calibration piece that suits this application was designed and manufactured. A steel hand model was used to measure the fingers joint angles. The average error from measuring the finger angles using this system was around 1 degree compared with 5 degrees for the existing used techniques.

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Holušová, Kateřina. "Standardizace a harmonizace znalecké metodiky pro potřeby Forenzní ekotechniky: les a dřeviny." Doctoral thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234301.

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In the presented thesis is an overview of the current state solved the problem, specifying the inclusion of Forensic Ecotechnique: forest and trees into the forensic sciences in the world and its description as part of special methods of forensic engineering. The results focus on the design of standardized and harmonized processes according to the type of expert opinions. As another of the key results of the work are designed functional biometric parameters for evaluating trees in the functional diagnosis of Methods of contact flora assessment (“CFA”). Application of some methods of measurement and selected functional biometric parameters are listed in the examples in the measurement of selected forest stands of beech in the National Nature Reserve Voděradské bučiny and in Chřiby hills. As a general supplement usable in Forensic ecotechnique: forest and trees are given the limits for functional diagnostics. In another series of work includes a discussion on the proposed standards and the measurement results. The work is concluded by summarizing the results and the benefits.

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Pavloň, Martin. "Analýza dynamických parametrů laserových vibrometrů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316221.

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This diploma thesis deals with the theoretical description of interference methods used to measure vibrations, examines main parasitic effects and analyses its contribution to achievable the resolution. In the practical part, it uses several measurements to verify the effects of the level of reflected beam, stand-off distance and speckle noise. It also proposes a practical experiment for measuring dynamic parameters and signal-noise ratio. Results show that, the noise is exponentially dependent on the level of the reflected beam. The visible maximum of the vibrometer proved to be critical in terms of time stability of the measured signal level in two of the three measurements. Results of the dynamic measurement show that, the measured deviations were not degraded or significantly disturbed by the noise signal. From the measurement of the speckle noise, it emerged that the lowest level of noise is achieved with smooth and highly reflective materials.

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Bršlicová, Tereza. "Bezkontaktní detekce fyziologických parametrů z obrazových sekvencí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221320.

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This thesis deals with the study of contactless and non-invasive methods for estimating heart and respiratory rate. Non-contact measurement involves sensing persons by using camera and the values of the physiological parameters are then assessed from the sets of image sequences by using suitable approaches. The theoretical part is devoted to description of the various methods and their implementation. The practical part describes the design and realization of the experiment for contactless detection of heart and respiratory rate. The experiment was carried out on 10 volunteers with a known heart and respiratory rate, which was covered by using of a sophisticated system BIOPAC. Processing and analysis of the measured data was conducted in software environment Matlab. Finally, results from contactless detection were compared with the reference from measurement system BIOPAC. Experiment results are statistically evaluated and discussed.

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Agar, Julie. "Contact parameter estimation using a space manipulator verification facility." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82459.

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Computer simulations play an important role in the design and verification of space robotic operations since on-orbit tests are impossible to conduct before launch. Thus, accurate computer modelling and simulation of space robotic tasks is essential. Of particular difficulty are space manipulator operations, which involve constrained or contact tasks. Here, the contact dynamics capability in the modelling tools becomes critical for high fidelity simulation. This in turn implies a need for accurate determination of contact parameters, which are used as inputs to contact dynamics simulation. In this work, the identification of contact dynamics parameters based on sensor data obtained during robotic contact tasks is considered.
The contact parameter estimation problem is addressed for simple and complex contacting geometries using the SPDM Task Verification Facility Manipulator Test-bed (SMT) at the Canadian Space Agency. The SMT is a space-representative robotic simulation facility. Single- and multiple-point contact parameter estimation software toolboxes were developed and used with SMT experiments. Single point SMT contact experiments were performed with six different payloads. The single point toolbox was used as part of the process of identifying payload stiffness from SMT experimental data.
Multiple point contact parameter estimation experiments with the SMT were conducted using a mock-up of an International Space Station Arm Computer Unit (ACU) as payload. The multiple point toolbox was used to generate contact stiffness, damping and friction estimates. An evaluation of the sensitivity of the parameter estimation algorithm to mismatches in ACU physical dimensions and ACU geometry files was conducted.

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Trarieux, Chloé. "Mesure des propriétés viscoélastiques non linéaires par une méthode d'acousto-élasticité dynamique : application aux produits cosmétiques." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR3312/document.

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Peu d’outils ont été développés pour le contrôle qualité industriel de textures sur des lignes de production. L’utilisation de techniques sans contact, à base d’ondes acoustiques, présente un avantage évident dans les secteurs agroalimentaire et cosmétique. L’acousto-élasticité dynamique (DAET) est une technique d’interaction entre une onde pompe basse-fréquence de compression/dilatation et une onde sonde ultrasonore, conduisant à l’estimation des propriétés viscoélastiques de la matière. Nous avons développé un modèle décrivant les variations du module viscoélastique : quantification des paramètres non linéaires élastiques (B/A,. C/A...) et visqueux (ωηB/A, ωηC/A...). La méthode DAET et le modèle ont ensuite été validés dans des milieux homogènes (eau, huiles et gels) conduisant à des non-linéarités viscoélastiques faibles (B/A < 15 et (ωηB/A <1). essentiellement liées à la composition du fluide ou un changement d’état. Les résultats les plus probants ont été obtenus dans des milieux granulaires ou constitués d’air (poudres sèches, mousses et billes creuses ): valeurs élevées des non-linéarités viscoélastiques (quadratiques, cubiques). Cette méthode pourra s’avérer être une alternative intéressante à la rhéométrie conventionnelle, en particulier pour la caractérisation de ces fluides complexes
Few tools have been developed for industrial quality control of textures on production lines. The use of contactless techniques. based on acoustic wavcs, offers an obvious advantage in food-processing industry and cosmetics. The dynamic acoustoelastic testing (DAET) is based on the interaction between a low-frequency compressionlexpansion pump wave and an ultrasound probe wave. leading to the quantification of the viscoelastic properties of the matter. We have initially developed a model describing the variations of the viscoelastic modulus: quantification of nonlinear elastic (B/A, C/A...) and viscous (ωηB/A. ωηC/A...) parameters. The DAET method and related model were then validated in homogeneous media (water, oils and gels) leading to low values of viscoelastic nonlineaiities (B/A<15 and ωηB/A<1), essentially governed by the fluid nature or state change. However, the most significant results were obtained in granular or air-based media (dry powder, foam and hollow beads): high values of quadratic and cubic nonlinearities due to microinhomogeneitics. This method appears to be an interesting alternative to conventional rheometry, especially for the characterization of these complex fluids

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Del, Galdo Vittorio. "Impact of the use of different blends of wood chips from diverse botanical species on quality parameters of white wine from Encruzado variety. A study on the effects of a different kind of wood on a white wine with no contact with lees." Master's thesis, ISA/UL, 2018. http://hdl.handle.net/10400.5/17935.

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Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de Agronomia
The aim of this study was to assess the influence of blends of wood from different botanical species in a white wine from Encruzado variety; the botanical species used in this study were French oak (Quercus peatraea), American oak (Quercus alba) and Cherry (Prunus avium) during a 60 days maceration period, with sampling done after 15, 30 and 60 days. The blends were obtained by combining 2 woods species in a ratio of 1:1, obtaining 3 blends; that is, Cherry and American oak (Ch+Am), French and American oak (Fr+Am), and Cherry and American oak (Ch+Am). In addition to these treatments 3 Control treatments were created by adding single wood of Cherry (CCh), American oak (CAm) and French oak (CFr), moreover a treatment without wood was kept (C). The amount of wood used was the same for all the treatments, that is 0,5 g/l. on the different sampling days were run both sensory analysis, by a panel of judges, evaluating aroma and taste parameters, and chemical analysis, that is, total phenols, non flavonoids and flavonoids phenols, color evolution, maderization test and tanning power. At the end of the experiment statistical analysis showed relevant data in almost all the analysis, for the chemical analysis cherry showed the highest level of total phenols and flavonoids, which is reflected also in the blends with other woods, while the French oak and its blends showed significant levels of non flavonoids phenols. The browning potential showed an decrease in wines in contact with wood except for CCh, while tanning power showed an increase in all the wines in contact with wood with the blend of cherry and American being the highest tannicity. In the sensory analysis we can observe how the global appreciation of the wines decrease with increasing maceration period with the wood both for the taste and aroma parameters, with C being the most appreciated wine at the last sampling, while the sampling of 15 and 30 days shows the wine with cherry and with American oak showing the highest values
N/A

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Damsongsaeng, Prapanpong. "Improvement of Steering Performance of a Two-axle Railway Vehicle via Look-up Tables Estimation." Thesis, KTH, Spårfordon, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285671.

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A conceptual design of an innovative two-axle lightweight railway vehicle for commuter services is carried out at KTH Railway Group. An active wheelset steering is introduced to improve the curving performance of the vehicle, which is one of the critical performance requirements. This thesis aims to improve the steering performance of the active wheelset steering. Look-up tables for estimating time-varying wheel-rail contact parameters are introduced to supervise a simple PID controller of the active steering system in order to improve steering performance. The look-up table (LUT) estimation is focused on time-varying wheel-rail contact parameters, including creep coefficients and contact patch variables due to their direct influence on curving performance and lateral stability of the wheelset. As a result, the estimated longitudinal unit creep forces (UCF) have the potential to supervise the gains determination of PID controller because it can appropriately distinguish running conditions. The estimation of longitudinal UCF is achieved by the combination of the results from the LUT of creep coefficients and the LUT of contact patch variables. The result from longitudinal unit creep force estimation is shifted to the first quadrant to use as critical gain in the Ziegler-Nichols tuning method for the PID controller. The critical oscillation period for PID tuning can be expressed as a function of vehicle speed. Consequently, the PID controller for the active steering system uses time-varying gains with real-time tuning. The proposed control system for active wheelset steering is validated with nine running conditions using SIMPACK and MATLAB/Simulink co-simulation. The proposed control system provides a stable wheelset lateral displacement control regardless of the running condition. The active steering system significantly reduces wheel-rail wear, which demonstrates the effectiveness of the proposed active steering system.
KTH:s Järnvägsgruppen utvecklar en konceptuell design av ett innovativt, två-axligt, lättvikts järnvägsfordon för tunnelbana eller pendeltåg. En aktiv hjuparsstyrning introduceras för att förbättra kurvtagningsförmågan hos fordonet, vilket är ett av de kritiska prestandakraven hos dessa fordon. Det här examensarbetet har som målsättning att förbättra styrningsprestandan av den aktiva hjulsatsstyrningen. För att uppskatta tidsvarierande hjul-rälskontaktparametrar introduceras pre-definierade tabeller (LUT) som en övervakning av en enkel PID-kontroll för det aktiva styrningssystemet, för att förbättra styrprestandan. Uppskattningen som baseras på tabellen fokuserar på tidsberoende hjul-rälsparametrar, inklusive krypkoefficienter och kontaktytans storlek och form. Dessa variabler är i fokus på grund av deras direkta effekt på kurvtagningsförmågan och den laterala stabiliteten hos hjulparet. Den uppskattade longitudinala enhets krypkraften (UCF) har potential att bestämma förstärkningen hos PID-kontrollen på grund av att den, på ett lämpligt sätt, kan skilja mellan olika körtillstånd. Uppskattningen av longitudinell UCF uppnås genom en kombination av resultat för krypkoefficienter och kontaktytavariabler i LUT. Resultaten från den longitudinella UCF-uppskattningen skiftas till den första kvadranten för att användas som kritisk förstärkning i Ziegler-Nichols justeringsmetod för PID-kontroller. Den kritiska oscillationsperioden för PID-justering kan utryckas som en funktion av fordonets hastighet. Utgående från detta använder PID-kontrollen tidsvarierande förstärkning med realtidsjustering för den aktiva styrningen. Det föreslagna kontrollsystemet valideras mot nio körtillstånd med hjälp av SIMPACK och MATLAB/Simulink-simuleringar. Det föreslagna kontrollsystemet tillhandahåller en stabil lateral förflyttning av hjulparet oberoende av körtillstånd. Det aktiva styrsystemet reducerar hjul-räls slitaget signifikant, vilket demonstrerar effektiviteten hos det framtagna aktiva styrsystemet.

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Patel, Ketan. "Frequency and time domain contact parameter estimation for space robotic operations." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19579.

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Computer simulations play a significant role in the development and operation of space systems because of the difficulty in performing ground-based hardware testing and onorbit tests are impossible before the launch of these systems. Hence, accurate modeling and simulation of space robotic tasks involving contact is very crucial. This in turn implies that accurate model (contact) parameters, used as inputs to the software to represent the contact operation being simulated, are imperative. In this work, we addressed the contact parameter estimation problem for simple contacting geometries (one-point contact) and complex contacting geometries (multiple-point contact). Several frequency domain identification strategies were applied to one-point contact parameter estimation problem to estimate contact stiffness and damping. The performance of these frequency domain algorithms was evaluated and compared with time domain identification algorithms. The identification algorithm for multiple point contact scenario to estimate contact stiffness, damping and coefficient of friction was also investigated. We determined the cause for poor estimation results obtained with previous implementation of this identification algorithm and were able to improve the performance of the algorithm. Finally, a thorough evaluation of sensitivity of the algorithm to noise in measured data was conducted.

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Schlegel, Katharina Verena Schlegel Katharina Verena. "Ein Vergleich zwischen histologischen und klinischen Parametern während der experimentellen Gingivitis beim Menschen = (Comparison between histological and clinical parameters during human experimental gingivitis) /." [S.l : s.n.], 1986. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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Eriksson, Anna-Frida. "An Empirical Investigation of the Influence of Context Parameters on Everyday Planning Activities." Thesis, Linköping University, Department of Computer and Information Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4300.

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The purpose of the study is to explore the context, from the users’ perspective, in order to find relevant context parameters that can be useful in the development of the future context-aware technology. The goal is to find some of the context parameters relevant to the situated activity and investigate to what extent and in which way they influence the user in everyday planning activities.

The method used in the study was based on scenario descriptions. A total of 41 participants reported how they would have acted in the different situations and they also rated how important they believed the different context factors were in the situations. Analyses were made to reveal relationships between context factors and service properties used by the participants in the scenarios.

In the study several interesting relationships between context factors and the use of services were discovered. The level of urgency was in several situations considered to be important, and it was also found to have an impact on how the participants chose to communicate. The cost was introduced by the participants during the study. It seemed to be important; however, in situations with high urgency it became less important. The study revealed a potential relationship between the risk of disturbing the people in the vicinity and the effort to communicate quietly. Another interesting finding was the relationship between privacy and the choice of modality when communicating: voice-based services were avoided. Further, the importance of privacy and disturbance also appeared to have greater influence in non-anonymous situations than in anonymous.

Syftet med studien är att undersöka kontexten, utifrån användarens perspektiv, för att kunna hitta relevanta kontextfaktorer som kan vara användbara i utvecklingen av kontextmedveten teknologi. Målet är att finna kontextfaktorer som är relevanta för den pågående aktiviteten och undersöka i vilken utsträckning och på vilka sätt dessa faktorer påverkar användaren i de dagliga planeringsaktiviteterna.

Metoden som användes i studien baserades på scenariobeskrivningar. 41 stycken försöksdeltagare fick beskriva hur de skulle ha handlat i de olika situationerna och de fick också skatta hur viktiga de olika kontextfaktorerena var i situationerna. Analyser genomfördes för att finna samband mellan kontextfaktorer och egenskaper hos de tjänster som försöksdeltagarna använde sig av i scenarierna.

I studien upptäcktes en rad intressanta relationer mellan kontextfaktorer och användningen av tjänster. Exempelvis ansågs nivån av brådska vara betydelsefull i flera situationer och den verkade också ha inverkan på hur försöksdeltagarna valde att kommunicera. Försöksdeltagarna introducerade under studien kontextfaktorn kostnad. Kostnaden påverkade valet av tjänster men blev mindre betydande i situationer med stor brådska. Studien visade också på potentiella samband mellan risken att störa människor i sin omgivning och viljan att kommunicera tyst. En annan intressant upptäckt var sambandet mellan avskildhet och kommunikationssätt: röstbaserade tjänster undveks när andra människor fanns i närheten. Dessutom verkade det som om det var viktigare att värna om sin avskildhet och att inte störa andra i ickeanonyma situationer än i situationer där man var helt anonym.

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Saccheto, Thiago Jose da Silva. "Estudo dos parametros influentes na vida de uma transmissão continuamente variavel do tipo esfera-cone submetida a contato com"slip/Spin"." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264393.

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Orientador: Franco Giuseppe Dedini
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-11T07:24:04Z (GMT). No. of bitstreams: 1 Saccheto_ThiagoJosedaSilva_M.pdf: 4654886 bytes, checksum: f2c656d8a1ed2a3a88bfd852d26a13d6 (MD5) Previous issue date: 2008
Resumo: Neste trabalho, é apresentado um estudo dos parâmetros que influem na vida de uma CVT do tipo esfera-cone para aplicação em sistemas de tração humana, particularmente bicicletas. Nos primeiros capítulos, é apresentado um histórico sobre as transmissões e seus grupos principais e em seguida um breve resumo descrevendo os tipos de CVTs mais comuns encontrados no mercado, seu princípio de funcionamento e características principais. Após esse capítulo, é introduzida a teoria de contato de Hertz como forma de cálculo do perfil de pressão normal e o algorítmo de Kalker para o cálculo do perfil de pressão tangencial e slip. As equações de lubrificação também são estudadas nesse trabalho, a fim de determinar a espessura de filme lubrificante no contato da CVT. Por fim é apresentada a CVT do tipo esfera-cone Wagner Forti, na qual são discutidos suas características cinemáticas, dinâmicas e geométricas, além da simulação para um conjunto de condições de operação com o intuito de calcular a vida de contato com slip/spin. Finaliza-se o trabalho correlacionando o tempo de vida calculado com as condições de operação. Palavras Chave- CVT, Tempo de Vida, Contato, Slip, Spin
Abstract: In this work, a study of the parameters that influences the lifetime of a TrackBall CVT for use in systems of human traction, particularly bicycles. First, the mechanical transmissions history is told and mentioned its main groups. Then it presented a brief summary describing the types of CVTs most common in market, their principle of operation and main features. After this chapter, it introduces the theory of Hertz contact as way of calculating the normal pressure profile and, by Kalker algorithm, calculating the tangential profile with slip. The equations of lubrication are also studied in this work in order to determine the thickness of the lubricant film in the contact of CVT. Finally it shows the type of CVT TrackBall Wagner Forti, which is commented on its cinematic, dynamic and geometric features, and the simulation for a range of operating conditions in order to calculate the life of contact with slip/spin. Finally it is the work correlating the life calculated with the conditions of operation. Key Words:CVT, Lifetime, Contact, Slip, Spin
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica

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Mateášik, Timko Marek. "Experimentální ověření pasivních prvků tepelné regulace družic." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443228.

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Diplomová práca sa zaoberá vplyvom termálnych medzivrstiev na tepelnú kontaktnú vodi- vosť a tepelný kontaktný odpor. Práca sa zameriava na aplikáciu termálnych medzivrstiev pre vylepšenie tepelnej kontaktnej vodivosti v tepelnom spínači a v kozmických zariade- niach obecne. Teoretická časť práce stručne skúma rôzne pasívne termálne kontrolné systémy použí- vane v kozmických zariadeniach, vrátane termálnych medzivrstiev, a vysvetľuje pozadie tejto práce. Táto práca ďalej skúma rôzne termálne medzivrstvy, predovšetkým povlaky a fólie, a uvádza výber vhodnej termálnej medzivrstvy. Experimentálna časť práce skúma povrchové parametre, tepelnú vodivosť a mikrotvr-dosť medených vzoriek, ktoré slúžia ako substrát pre povlak čistého striebra. Ďalej rieši podmienky merania, metódy vyhodnocovania a samotné experimentálne merania. Experimentálne merania sú vykonané v termo-vákuovej testovacej komore a na základe výsledkov sú vyvodené závery. Pre ďalšiu prácu sú uvedené doporučenia.

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Naveira, Suarez Aldara. "Parameters affecting the functionality of additives in lubricated contacts : effect of base oil polarity /." Luleå : Luleå University of Technology, 2010. http://pure.ltu.se/ws/fbspretrieve/3541725.

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Suarez, Aldara Naveira. "Parameters affecting the functionality of additives in lubricated contacts : effect of base oil polarity." Licentiate thesis, Luleå tekniska universitet, Maskinelement, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26576.

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Traditionally rolling contact fatigue observed in bearing field applications was subsurface initiated. However, despite the improvement of steel properties, some factors such as downsizing in bearing design, extreme loading of the bearings as well as demanding application conditions (start up-stop cycles) have led to an increase on the cases of surface damage related to surface initiated fatigue, that comes basically from surface distress. Possible causes leading to surface initiated fatigue are: material and surface properties, marginal lubrication and lubricant chemical composition. Lubricants are formulated products composed of base oil, and an additive package designed for a specific application. Extreme-pressure (EP) and antiwear (AW) additives are chemically active additives, they react with the steel surfaces in contact to form a protective additivederived layer, thus reducing friction and controlling wear. However, certain EP/AW additives that increase the performance of other machine elements, such as gears, can be detrimental for the bearings running in the same lubrication environment. In order to identify the plausible mechanisms that govern the detrimental effect of EP/AW additives on bearing performance, it is necessary to study closely the interactions occurring in the system form by the base oil, the additives present and the steel surface, as well as the influence of operating conditions. The focus of the present work is to identify the parameters affecting the additive-derived layer formation, as it is directly related to the additive reactivity towards the surface, and the tribological properties of the layer, that will determine the tribological performance. Zinc dialkyldithiophosphate (ZDDP), and two low viscosity model oils with different polarity were selected. The influence of base oil polarity on the additive performance was studied in the nanoscale using Atomic Force Microscopy and the tribological performance was evaluated using a ball-on-disc test rig under mixed rolling-sliding conditions in the boundary lubrication regime. An in-situ interferometry technique was used to monitor the additive derived reaction layer formation, and the chemical composition, morphology and nanomechanical properties were studies using X-ray Photoelectron Spectroscopy, Atomic Force Microscopy and Nanoindentation respectively. It was found that base oil polarity determines the transport of additives to the surface thereby controlling the maximum reaction layer thickness, friction and wear, as well as the morphology and nanomechanical properties of the additive-derived reaction layer. However the reaction layer chemical composition is not determined by the base oil polarity. Among the operating conditions, shear was identified as a fundamental parameter on the activation of additives on rubbing steel surfaces and the properties of the derived reaction layer.
Godkänd; 2010; 20100112 (aldara); LICENTIATSEMINARIUM Ämnesområde: Maskinelement/Machine Elements Examinator: Professor Roland Larsson, Luleå tekniska universitet Tid: Onsdag den 10 februari 2010 kl 10.00 Plats: E 231, Luleå tekniska universitet

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43

Qin, Wenyi. "Many server queueing models with heterogeneous servers and parameter uncertainty with customer contact centre applications." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33167.

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In this thesis, we study the queueing systems with heterogeneous servers and service rate uncertainty under the Halfin-Whitt heavy traffic regime. First, we analyse many server queues with abandonments when service rates are i.i.d. random variables. We derive a diffusion approximation using a novel method. The diffusion has a random drift, and hence depending on the realisations of service rates, the system can be in Quality Driven (QD), Efficiency Driven (ED) or Quality-Efficiency-Driven (QED) regime. When the system is under QD or QED regime, the abandonments are negligible in the fluid limit, but when it is under ED regime, the probability of abandonment will converge to a non-zero value. We then analyse the optimal staffing levels to balance holding costs with staffing costs combining these three regimes. We also analyse how the variance of service rates influence abandonment rate. Next, we focus on the state space collapse (SSC) phenomenon. We prove that under some assumptions, the system process will collapse to a lower dimensional process without losing essential information. We first formulate a general method to prove SSC results inside pools for heavy traffic systems using the hydrodynamic limit idea. Then we work on the SSC in multi-class queueing networks under the Halfin-Whitt heavy traffic when service rates are i.i.d. random variables within pools. For such systems, exact analysis provides limited insight on the general properties. Alternatively, asymptotic analysis by diffusion approximation proves to be effective. Further, limit theorems, which state the diffusively scaled system process weakly converges to a diffusion process, are usually the central part in such asymptotic analysis. The SSC result is key to proving such a limit. We conclude by giving examples on how SSC is applied to the analysis of systems.

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44

Schneck, William Carl III. "Estimation of the Real Area of Contact in Sliding Systems Using Thermal Measurements." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35244.

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This thesis seeks two objectives. One objective is to develop a means to estimate time invariant real contact areas and surface temperatures through thermal measurements in 1D/2D systems. This allows computationally easier models, resulting in faster simulations within acceptable convergence. The second objective is to provide experimental design guidance. The methods used are a modified cellular automata technique for the direct model and a Levenberg-Marquardt parameter estimation technique to stabilize inverse solutions. The modified cellular automata technique enables each piece of physics to be solved independently over a short time step, thus frequently allowing analytical solutions to those pieces. Overall, the method was successful. The major results indicate that appropriately selected measurement locations can determine the contact distribution accurately, and that the preferred measurement location of the sensor is not very sensitive to the contact distribution specifics. This is useful because it allows selection of measurement locations regardless of the specifics of the generally unknown contact distribution. Further results show the combined effects of the normalized length and the Stanton number have a significant impact on the estimation quality, and can change the acceptable sensor domain, if the loss is high. The effect of placing the sensor in the static body can, for low loss, provide a coarse image of the contact distribution. This is useful because the static body is easier to instrument than a moving body. Finally, the estimation method worked well for the most complex model utilized, even in a sub-optimal measurement location.
Master of Science

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45

Ozarkar, Malhar. "Design Parameter Identification and Verification for Thermoplastic Inserts." Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-170132.

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Inserts are a crucial part of household and industrial furniture. These small plastic parts which often go unnoticed to the naked eye perform crucial functions like providing a base for the furniture, leveling the furniture, safeguarding the user from edges of the tubes used and providing an aesthetic finish. The inserts have a wing like structure on the exterior which enables them to be inserted and securely held in the tubes. The inserts are assembled into the pipes manually or through machines. The force required to install these inserts in the tube is called a push-in force whereas a pull-out force is the force required for removal of the is called a pull-out force. These forces are experienced by someone who assembles the furniture together. Thus, these forces directly define the ease with which the furniture can be assembled. In the first part of the present thesis, these push-in and pull-out forces are predicted using finite element simulations. These finite element simulations were validated by performing physical assembly and disassembly experiments on these inserts. It was found that the finite element simulations of the insert are useful tool in predicting the push-in forces with a high accuracy. These push-in and pull-out forces for a single insert vary by 2-5 times when the dimensional variations in the tube are considered. The dimensional variations can be a result of the manufacturing processes from which these tubes are produced. The maximum and minimum dimensions that the tube can have are defined by the maximum material condition (MMC) and the least material condition (LMC). To reduce the variation in push-in and pull out forces, a stricter tolerance control can be applied to the manufacturing process. To avoid this cost while having a lower variation in the push-in and pull out forces, the design of the insert was modified. To achieve this enhanced design of the insert, a metamodel based optimization technique was used in the second part of the thesis. For this optimization, the geometrical parameters - wing height, wing diameter and stem thickness the of the insert were identified as the crucial factors which govern the assembly/disassembly forces. The identification of these parameters was done through a design of experiments. These parameters were then varied simultaneously in a metamodel based optimization which had an objective to minimize the variation in forces observed for an insert when the maximum material condition and the least material conditions are considered. The result for the enhanced design of the insert was then stated in terms of the ratio of these identified parameters. The modified design of the insert not only enables the manufacturer to have better performance, but also reduces the amount of plastic material required for manufacturing of the insert.

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46

Urbanowicz, Mirosław. "Influence parameters of ignition arrangement on profile of engine : PhD thesis summary." Rozprawa doktorska, [s.n.], 2015. http://dlibra.tu.koszalin.pl/Content/1057.

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47

Schmid, Beat. "Sun photometry, a tool for monitoring atmospheric parameters /." Bern : [s.n.], 1995. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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48

Szoltys, Kryštof. "Parametrické CAD systémy a databáze součástí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217957.

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Autodesk Inventor is a full 3D CAD system. This system includes tools for working environment tool, component design tool including information data management and technical support. The target of the first part is to describe the most important new features brought by Autodesk Inventoru 2009 version. In of next chapters the work describes creation common iPart, which is basically different variants set (proportions, material …) of one entity, and preparation before correct publication to the content center, which is a virtual database of all iPart. Also there is presented how to create the content center, how to work with it and adjust data. The aim of work is then the creation database a stator and a rotor packet for the firm ATAS electromotor Náchod Inc. In the thesis there is described creation of the lamination as an iPart and their publication to the new content center.

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49

Silva, Gabriel Hattori da. "Escolha de parametros para analise de contato entre corpos elasticos usando elementos finitos e redes neurais." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265005.

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Orientador: Alberto Luiz Serpa
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-12T19:17:55Z (GMT). No. of bitstreams: 1 Silva_GabrielHattorida_M.pdf: 1021601 bytes, checksum: 4cc8fdf21ddc6d423c4f3264c5c4a0f2 (MD5) Previous issue date: 2009
Resumo: Este projeto tem o objetivo de estudar o efeito dos principais parâmetros que afetam a solução do problema de contato entre corpos elásticos. Foi utilizado o software comercial ANSYS 11.0 para realizar as análises de contato. A influência dos principais parâmetros considerados pelo ANSYS no problema de contato, tais como a rigidez de contato normal, o limite de penetração, os algoritmos de contato e métodos de solução, é investigada no trabalho. Observou-se que a rigidez de contato normal influi diretamente na convergência e nos resultados obtidos. Foram estudados alguns exemplos com resultados conhecidos (analíticos ou numéricos) para uma comparação com a solução do ANSYS, e exemplos de maior interesse prático, como o problema de contato do olhal menor de uma biela automotiva. A partir dos casos analisados, algumas recomendações foram feitas para a escolha dos parâmetros de contato. No entanto, existem parâmetros que dependem do conhecimento do usuário ou da realização de testes preliminares, o que requer em muitas situações um maior tempo para se obter os resultados. Como alternativa, foi investigado o potencial das redes neurais para contornar esta limitação. As redes neurais foram treinadas com resultados obtidos da solução do problema de contato (penetração e variação da pressão de contato) de modelos simplificados, tendo como saída da rede a rigidez de contato normal, que é então usada para estimar a rigidez de contato normal de problemas mais complexos. Foi usada a implementação de redes neurais do software MATLAB 7.0 para o treinamento e a simulação das redes neurais
Abstract: The objective of this project is to study the effect of the main contact parameters that affect the solution of the elastic bodies contact problem. The commercial software ANSYS 11.0 was used to run the contact analysis. The influence of ANSYS main parameters in the contact problem, such as normal contact stiffness, penetration limit, contact algorithms and solvers, is investigated in this work. The normal contact stiffness acts directly in convergence and in the obtained results. Some examples with known results (analytic or numeric) were studied to be compared with ANSYS solution, and some examples of more practical interest, as the connecting rod small end contact problem, were also studied. With the analysed cases, some recommendations were done to the choice of the contact parameters. However, there are parameters that depend on the user's knowledge or it is necessary to run some preliminary tests. As an alternative, it was investigated the neural networks potential to overcome this limitation. The neural networks were trained with obtained results of the contact problem solution (penetration and contact pressure variation) of simplified models. The normal contact stiffness was used as output of the network, which was used to estimate the normal contact stiffness of more complex problems. It was used the neural network implementation of the softwareMATLAB 7.0 to the training and simulation of the neural networks
Mestrado
Mecanica dos Solidos
Mestre em Engenharia Mecânica

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50

Mistry, Zubin, Venkata Harish Babu Manne, Andrea Vacca, Etienne Dautry, and Martin Petzold. "A numerical model for the evaluation of gerotor torque considering multiple contact points and fluid-structure interactions." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71111.

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This paper presents a numerical model for the evaluation of the actual torque in Gerotor units. The model consists of two major modules: the pre-processor module and the HYGESim module. The preprocessor module consists of the geometric and the mechanical module. The geometric pre-processor module considers the CAD geometry of Gerotor with tolerances as input and it provides as output the geometric features needed to evaluate the rotor loading and the flow features. The mechanical preprocessor module evaluates the forces of interaction at the contact points between the rotors. The flow displaced by the unit is evaluated using a lumped parameter model whereas the lubricating gaps are evaluated by solving the Reynolds Equation. The main novel aspects consist of the evaluation of the frictional losses at various interfaces. An Elasto-Hydrodynamic Lubrication (EHL) approach is used to evaluate the frictional losses at the contact points between the rotors. Tests on a prototype Gerotor unit are performed for the model validation, particularly as pertains to the features of the shaft torque. Additionally, the paper comments on the distribution of the different torque loss contributions associated with the operation of the unit taken as reference.

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