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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Inverse analysis of the structures of the liquid molecules and colloidal particles near the solid-liquid interfaces: the relation between the number density distribution and the experimental force curve / 固液界面における液体分子とコロイド粒子の構造の逆解析:数密度分布と実験のフォースカーブの関係

Hashimoto, Kota 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23217号 / 工博第4861号 / 新制||工||1759(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 佐藤 啓文 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
262

A sensor based fixturing system to determine the minimum required clamping force for unte[n]ded machining operations

Gupta, Shelly January 1988 (has links)
No description available.
263

Investigation of Non-DLVO Forces using an Evanescent Wave Atomic Force Microscope

McKee, Clayton T. 29 December 2006 (has links)
This dissertation describes new methods for measuring surface forces using evanescent waves, and applications to non-DLVO forces. An evanescent wave, generated at a solid-liquid interface, is scattered by AFM tips or particles attached to AFM cantilevers. The scattering of this wave is used to determine absolute separation between surfaces and/or the refractive index as a function of separation in AFM measurements. This technique is known as evanescent wave atomic force microscopy (EW-AFM). The scattering of an evanescent wave by Si3N4 AFM tips is large and decays exponentially with separation from a refractive index boundary. Thus, scattering is a useful method for measuring the separation between a Si3N4 tip and sample. This method has been used to measure the absolute separation between a tip and sample in the presence of an irreversibly adsorbed polymer film. Measurement of the film thickness and time response of the polymer to applied loads has also been studied. These measurements are not possible using current AFM techniques. In addition to measurements in polymer systems, the simple scattering profile from Si3N4 tips was used to re-examine short range hydration forces between hydrophilic surfaces. Results presented in this thesis suggest this force does not depend on the hydrated radius of the ion between glass and silicon nitride. The scattering generated by a Si3N4 tip has also been used to measure the refractive index of bulk fluids and thin films between hydrophobic surfaces. Based on these results, I have shown that a long-range attraction between hydrophobic surfaces is accompanied by an increase in the refractive index between the tip and surface. From this I have concluded that the attractive force, measured in this study, is the result of an increase in the concentration of organic material between surfaces. Finally, I have shown that the scattering profile depends on the material and size of the scattering object. Scattering from silicon nitride tips is exponential with separation. In contrast, the scattering profile from silicon tips, which are similar in size and geometry, is not a simple exponential. The scattering profile of larger spherical particles attached to cantilevers is also not exponential. It is approximately the sum of two exponentials. The functional form of the scattering profile with separation is consistent with the transmission of evanescent light through flat planar films. This result would suggest that a re-examination of the separation-dependence of scattering in TIRM measurements is necessary. / Ph. D.
264

Surface and Hydrodynamic Forces in Wetting Films

Pan, Lei 27 August 2013 (has links)
The process of froth flotation relies on using air bubbles to collect desired mineral particles dispersed in aqueous media on the surface, while leaving undesirous mineral particles behind. For a particle to be collected on the surface of a bubble, the thin liquid films (or wetting films) of water formed in between must rupture. According to the Frumkin-Derjaguin isotherm, it is necessary that wetting films can rupture when the disjoining pressures are negative. However, the negative disjoining pressures are difficult to measure due to the instability and short lifetimes of the films. In the present work, two new methods of determining negative disjoining pressures have been developed. One is to use the modified thin film pressure balance (TFPB) technique, and the other is to directly determine the interaction forces using the force apparatus for deformable surfaces (FADS) developed in the present work. The former is designed to obtain spatiotemporal profiles of unstable wetting films by recording the optical interference patterns. The kinetic information derived from the spatiotemporal profiles were then used to determine the disjoining pressures using an analytical expression derived in the present work on the basis of the Reynolds lubrication theory. The technique has been used to study the effects of surface hydrophobicity, electrolyte (Al3+ ions) concentration, and bubble size on the stability of wetting films. Further, the geometric mean combining rule has been tested to see if the disjoining pressures of the wetting films can be predicted from the disjoining pressures of the colloid films formed between two hydrophobic surfaces and the disjoining pressures of the foam films formed between two air bubbles. The FADS is capable of directly measuring the interaction forces between air bubble and solid surface, and simultaneously monitoring the bubble deformation. The results were analyzed using the Reynolds lubrication theory and the extended DLVO theory to determine both the hydrodynamic and disjoining pressures. The FADS was used to study the effects of surface hydrophobicity and approach speeds. The results show that hydrophobic force is the major driving force for the bubble-particle interactions occurring in flotation. / Ph. D.
265

Reconstruction de sollicitations dynamiques par méthodes inverses / Identification of a dynamic sollicitation by an inverse approach

Tran, Duc Toan 29 August 2014 (has links)
Dans le domaine de l'ingénierie, connaitre le chargement appliqué sur une structure permet de résoudre des problèmes directs dont le résultat est le champ de déplacement, de déformation dans une structure. Il est alors possible d'effectuer un dimensionnement. Cependant, parfois ce chargement doit être identifie a posteriori. Malheureusement, il n'est pas toujours possible de mesurer ce chargement : ainsi, par exemple, on ne sait pas a priori où aura lieu le chargement, ou bien il n'est pas possible de placer un capteur sans l'endommager ou encore il peut nécessiter un encombrement trop important. On a alors recours à des mesures indirectes de déplacement, de déformation, d'accélération et on est alors amené à résoudre des problèmes inverses, qui sont en général mal posés. Il est alors nécessaire d'ajouter une (des) conditions supplémentaire(s) pour obtenir une solution unique et stable : c'est la régularisation du problème. Ces techniques sont bien connues et leur essor est dû à l'utilisation des décompositions en valeurs singulières des matrices de transfert. Toutefois, elles nécessitent l'utilisation d'un paramètre additionnel qui pondère cette condition supplémentaire : la détermination de ce paramètre est délicate. Peu de travaux ayant été réalisé pour tester de façon intensive les méthodes usuelles de régularisation (Tikhonov et troncature de la (G)SVD), en association avec les différents critères de détermination du paramètre de régularisation et les différentes réponses possibles, on a effectué un tel travail pour tirer des conclusions sur la méthodologie optimale. On a pu mettre en évidence que la mesure de l'accélération associée à un critère faisant intervenir les dérivées du signal à reconstruire donne en général les meilleurs résultats sous réserve d'utiliser le critère GCV pour déterminer le paramètre de régularisation. Ces méthodes supposent que la localisation de la zone de chargement est connue. Aussi on s'est intéressé à déduire cette zone de chargement en tentant de reconstruire des chargements identiquement nuls. Cette identification a été effectuée aisément sous réserve qu'on ait peu de forces à identifier par rapport au nombre de mesures disponibles. En revanche une telle identification est délicate lorsqu'on n'a pas plus de mesures que de forces à identifier. Finalement on s'est tourné vers l'identification de chargement ayant plastifié la structure étudiée. On a alors essayé de reconstruire le chargement en supposant que la structure reste linéaire élastique, alors qu'elle a été plastifiée : on a utilisé la méthode du double chargement et effectue des simulations à l'aide du logiciel de simulation Ls-dyna.La force reconstruite fait alors apparaitre une composante statique traduisant la déformation résiduelle dans la structure. Dans ce cas, la réponse à utiliser pour identifier le chargement est une déformation dans une zone non plastifiée / In the field of the engineering, knowing the load applied on the structure which allows to solve the direct problem of which the results are given the field of displacement and strain in a structure. It is possible to perform a dimensioning. However, sometimes this load must be identified a posteriori. Unfortunately, it is not always possible to measure this load. Thus, for example, we do not know a priori where it will be loaded, either it is not possible to place a sensor without damaging it or needs too much space. We then have to use indirect measures of displacement, strain, acceleration and then we are lead to solve the inverse problems which are generally an ill-posed. It is then necessary to add one (or more) conditions to obtain a unique and stable solution: it is the regularization of the problem. These techniques are well known and their development is due to the use of the singular value decomposition of the transfer matrix. However, they require the use of an additional parameter that weights this additional condition: the determination of this parameter is difficult. Few studies having been realized in way the usual regularization methods of (Tikhonov and truncation of the (G)SVD), in association with the various criteria for determining the regularization parameter and the various possible responses, we conducted a such work, to draw conclusions on the optimal methodology. It has been highlighted that the measurement of the acceleration associated with a criterion involving the derived signal to reconstruct generally gives the best results via the GCV criterion to determine the regularization parameter. These methods suppose that the location of the loading area is known. We also were interested to deduct this loading area while trying to reconstruct load that is identically zero. This identification was performed easily that has little load to identify compared to the number of measurements available. However such identification is difficult when there are no more measures than loads to identify. Finally we turned to the identification of loading with the plastic structure. We then tried to reconstruct the load assuming that the structure remains linear-elastic, while it was plasticized: we used the method of the double load and performed simulations using the software ls-dyna. The reconstructed load then shows a static component reflecting the residual strain in the structure. In this case, the response used to identify the load is a strain in a non-plasticized zone
266

Multiple Fibre Bragg Grating Force Sensor

Fritzén, Felix January 2023 (has links)
The purpose of this project is to explore the FBG (Fiber Bragg Grating) technology and create a force sensor. The result can be used as a basis for further projects.The project starts with force and strain measurements. The project then evolves to incorporate multiple FBG sensors. An uncommon method of writing the FBG withcoating is tested, which results in a FBG with most of the coating left.The result is a multi-FBG sensor. And even though the individual FBG is not linear the sum shows fantastic linearity with R-square of 0.99999. The change in wavelength is 1328pm/N. A common issue in the strain measurement is discussed and proof is provided. This shows that the reference value of the FBG is 1.12pm/μstrain instead of 1.21pm/μstrain. This is important if the FBG is mounted in a structure, because then the material proprieties will be dominating. Another result is that the peaks of Fabry Perot grating pair are linear but with different coecients.
267

La rupture du contrat / Breach of contract

Saidani, Hariz 13 December 2016 (has links)
Le contentieux contractuel éclate lorsque l'une des parties n'exécute plus ou pas ses obligations. La préoccupation essentielle en matière contractuelle, consiste à lutter contre une rupture abusive et arbitraire du contrat. La particularité du droit civil français en matière de rupture du contrat, est la place très importante qu'occupe le juge judiciaire. L'assurance de la protection des intérêts des parties et la garantie d'une sanction juste et équitable, reposent en effet, sur les épaules du juge. Il est par conséquent inconcevable que le juge soit écarté du jeu de la rupture contractuelle. L'orientation traditionnelle a toujours fait du juge un pilier dans le domaine de la séparation contractuelle, mais cette tendance commence quelque peu à se dissiper. Le juge doit toujours jouer un rôle très important en droit des contrats en général et dans sa rupture en particulier. Une protection efficace des parties donnerait à l'intervention du juge une utilité plus importante. Il est primordial, que le juge soit un acteur, en matière de rupture contractuelle, dont le rôle serait la garantie du respect des lois et la protection complète des parties ; le cas contraire, pourrait réduire alors la portée du code civil actuel à un simple catalogue de lois régissant l'anéantissement du contrat. / Contractual litigation arises when one of the parties fails to fulfill its obligations. Its main concern is to fight against abusive and arbitrary breach of contracts. In the French civil law, the judge occupies a very important place when debating breach of contracts. It is impossible to alienate the judge when it comes down to contract breaches. In fact, he insures that the interests of every concerned party are protected. He also guarantees that fair and equitable sanctions will be applied. Traditionally, the judge was very important when discussing breach of contracts. However, this trend is beginning to dissipate. In general, the judge plays a very important role in contract law, but his role is primordial when disputing contract termination. Effective protection of the parties would give the intervention of the judge a greater utility. It is essential that the judge remains an important actor when it comes to breach of contract as his role is to guarantee that the law is respected and that every party is adequately protected. On the contrary, it could reduce the importance of the current Civil Code to a mere catalog of laws governing the annulment contracts
268

Impact of technology and command on No 1 Squadron operations 1916-1958

Lax, Mark, Humanities & Social Sciences, Australian Defence Force Academy, UNSW January 1995 (has links)
Flying Squadrons are the very substance of an air force. By its nature, the air service is a highly technical one requiring both complex machinery and sound human judgement to function at its peak. The smallest independent unit of an air force is the squadron. Squadrons have a discrete status which makes them ideal candidates for in-depth study. This thesis examines the impact of technology and command on a single squadron's operations because technology and command have been and will remain pivotal in determining the success or failure of the air service. Although the Australian No 1 Squadron has existed almost continually from 1916 to the present, this thesis only examines a specific period of its life. The period 1916-1958 was chosen since the squadron formed as an independent Australian Flying Corps unit in January 1916, served in both World Wars and the Malayan Emergency, returning to Australia to resume domestic operations and training in 1958. Of significance to the work, during the specified period, the Squadron was controlled by both the Army and Air Force, by both the British and Australian Governments, had successes and failures and was an operational and a training unit. The Squadron has thus mirrored the growth and changes experienced by the developing Air Force as a whole. The main purpose of examining such a squadron is that it provides an insight into the development and thinking of the RAAF and highlights pitfalls evidenced in technological and command problems which still plague military staff today. In examining the operations and operational effectiveness of No 1 Squadron, three determinants have been specifically examined: technology, that is the aircraft flown, the commanding officer's personality and his methods and the organisational structure under which the Unit operated. Naturally, all three matured as doctrine, knowledge and experience also matured. The Thesis concludes that when the Squadron is winning, it is generally technology that creates the relative advantage and when loosing, strong leadership in the form of command must come to the fore. The results obtained support the thesis in keeping with contemporary RAAF doctrine, that technology and command strongly impact squadron operations and hence, operational effectiveness.
269

Force-Time Curve Characteristics and Hormonal Alterations During an Eleven-Week Training Period in Elite Women Weightlifters

Haff, G. Gregory, Jackson, Janna R., Kawamori, Naoki, Carlock, Jon M., Hartman, Michael J., Kilgore, J. Lon, Morris, Robert T., Ramsey, Michael W., Sands, William A., Stone, Michael H. 01 March 2008 (has links)
The purpose of this investigation was to study the effects of an 11-week training period performed by female weightlifters. Two weeks before this investigation, baseline measures for total testosterone, cortisol, and testosterone:cortisol ratio were collected. The 11-week training program consisted of the core exercises (i.e., clean, clean and jerk, and snatch) and other supplemental exercises (i.e., clean pull, snatch pull, squat, and front squat). Hormonal, isometric, and dynamic middle thigh pull force-time curve characteristics were assessed biweekly throughout the duration of the investigation, whereas volume load and training intensity were assessed weekly throughout the investigation. The testosterone:cortisol ratio of the baseline (1.19 ± 0.64) was significantly different from the ratio of weeks 1 (0.67 ± 0.36) and 9 (0.94 ± 0.66). When the week-to-week values were compared, week 1 (0.67 ± 0.36) was significantly different (P < 0.05; ηsup>2= 0.84) from week 3 (1.06 ± 0.54). A very strong correlation (r = −0.83; r 2 = 0.69) was found between the percentage change of the testosterone:cortisol ratio and volume load from weeks 1 to 11. Moderate to very strong correlations were noted between the percentage change in volume load and isometric peak force, peak force during the 30% isometric peak force trial, and peak force during the 100-kg trial during the 11 weeks of training. The primary finding of this study was that alterations in training volume load can result in concomitant changes in the anabolic-to-catabolic balance, as indicated by the testosterone:cortisol ratio, and the ability to generate maximal forces.
270

Development of an Instrument for Evaluation of a Management Education Program

Ballentine, Rodger D. 08 1900 (has links)
This study was designed to develop a rating instrument to measure the effectiveness of the first phase of management education for an Air Force officer, An officer's ability to lead, the first objective of management training, is intrinsically related to the ability to write, speak, and solve problems. These were behaviorally stated in a 60 item survey. Supervisors (N = 174) were asked to rate the frequency of occurrence of these behaviors for a subordinate. The survey was administered on two occasions to supervisors of officers eligible for training. Item analysis of the results reflected a strong favorable response bias with usable variability. Data indicated the instrument was a unidimensional internally consistent scale.

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