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1
Vavrille, Benjamin. "Développement d'une méthode innovante de mesures des propriétés thermomécaniques de films minces. Application à un dispositif imageur." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALI126.
Анотація:
Les polymères sont des matériaux de plus en plus utilisés dans le domaine de la microélectronique. Outre les propriétés électriques ou optiques intéressantes pour les intégrations, ils présentent généralement de forts contrastes de propriétés thermomécaniques avec les substrats semi-conducteurs mais aussi avec les autres matériaux également intégrés dans les dispositifs, tels que les oxydes ou les métaux. Cette inadéquation entre les matériaux provoque généralement une forte augmentation des contraintes dans les différentes couches considérées, ce qui entraine en retour une forte augmentation de la courbure de la plaque. Des contraintes trop intenses peuvent provoquer l'apparition de fissure ou un délaminage, menaçant l'intégrité mécanique de la structure. Connaître les propriétés de chaque couche, en particulier des films polymères, permet aux concepteurs de vérifier la compatibilité des matériaux intégrés et de garantir la fiabilité du composant. Toutefois pour atteindre cet objectif, il est essentiel de développer des techniques de caractérisation de ces propriétés thermomécaniques spécifiquement adaptées pour les films minces déposés sur substrat.Ainsi, l'objectif de ce travail est de mettre au point une méthode expérimentale de détermination précise et réaliste des propriétés thermomécaniques des couches d'intégration, et ensuite de vérifier à l'aide d'outils de simulation analytiques ou numériques, l'intégrité mécanique des dispositifs microélectroniques. Cette méthode est basée sur la mesure de l'évolution de la courbure des plaques au cours de cycles en température. Elle permet non seulement de vérifier l'achèvement du processus de réticulation des polymères, mais aussi d'estimer leurs températures de transition vitreuse. En mesurant la courbure en température de deux substrats distincts sur lesquels sont déposés un même matériau polymère, la méthode développée permet de déterminer le module biaxial et le coefficient de dilatation thermique du film. La caractérisation d'un grand nombre de polymères par cette technique permet de constituer une base de données matériaux que l'on peut compléter avec les propriétés des autres matériaux intégrés. Ces données alimentent des modélisations dans le but de prédire le niveau de déformation de plusieurs dispositifs utilisés en microélectronique.Nous étudierons en particulier le cas des capteurs d'images en réalisant un calcul prédictif des déformations et des contraintes dans les empilements afin d'examiner la compatibilité des différents matériaux. Nous travaillerons également sur l'intégrité mécanique de ces dispositifs, afin de garantir leur fabrication et leur fiabilité dans le temps. Nous montrerons que le choix des matériaux est facilité par la modélisation des structures et qu'il est également possible d'étudier l'initiation et la propagation de fissures à l'aide de modèles numériquesPolymers are very widespread in microelectronics. In addition to their relevant electrical and optical properties for integration, their thermomechanical properties generally exhibit a high contrast with semiconductor substrates, but also with other materials also integrated into microchips, like oxides or metals. This mismatch between materials generally leads to a sharp increase of stresses in the various layers under consideration, which in returns results of a sharp increase in the wafer curvature. Excessive stresses can lead to cracking or delamination, threatening the mechanical integrity of the structure. Knowing the properties of each layer, especially polymer films, enables designers to verify the compatibility of integrated materials and guarantee component reliability. However, to achieve this goal, it is mandatory to develop characterization techniques, especially for thin films deposited on substrates.Thus, the aim of this work is to develop an experimental method to determine the thermomechanical properties of integrated layers, and then to verify the mechanical integrity of microelectronic devices using analytical or numerical simulation tools. This method is based on measuring the variation of curvature during thermal cycles. Then the completion of the polymer cross-linking process can be checked and its temperature of glass transition can be determined. By measuring the thermally induced curvature of two distinct substrates with the same deposited polymer material, the biaxial modulus and the coefficient of thermal expansion of the film are determined. By characterizing a large number of polymers using this technique, we can build up a materials database that can be supplemented with other integrated materials. These data are used in modeling to predict the strain and stress levels of several devices used in microelectronics.In particular, we will study the case of image sensors by performing a predictive calculation of strain and stress distributions of stacks in order to examine the compatibility of different materials. We will also work on the mechanical integrity of these devices, to guarantee their manufacture and reliability over time. We will show that the material selection is eased by structural modeling and a method to study crack initiation and propagation using numerical models
2
Py, Matthieu. "A study of interfaces and nanostructures by time of flight mass spectrometry : towards a spatially resolved quantitative analysis." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00721832.
Анотація:
Les dispositifs avancés pour la microélectronique intègrent divers matériaux et sont de dimensions nanométriques. Une connaissance précise de leur composition est requise pour améliorer leurs procédés de fabrication et comprendre leur comportement électrique. Le ToF-SIMS est un candidat intéressant, qui souffre cependant des effets de matrice et ne possède pas toujours une résolution spatiale suffisante. Le but de ce travail est de permettre une analyse quantitative et résolue en profondeur de matériaux et structures pour la microélectronique avancée à l'aide d'un ToF-SIMS standard. Cette étude porte sur SiGe, sur des matériaux à haute permittivité, des implants basse énergie et des matériaux organiques. Elle se concentre sur la préparation d'échantillons, l'optimisation des conditions expérimentales et le traitement de données pour mettre au point des protocoles d'analyse originaux dont la précision est évaluée grâce à d'autres techniques de caractérisation de pointe. Ces protocoles permettent d'améliorer la qualité des analyses en termes de résolution en profondeur, de précision et de reproductibilité
3
Neelamraju, Bharati. "Characterization Techniques for Photonic Materials." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613403.
Анотація:
The advancement of photonics technologies depends on synthesis of novel materials and processes for device fabrication. The characterization techniques of the optical, electrical and magnetic properties of the synthesized materials and devices, by non-contact, non-invasive and nondestructive methods plays a significant role in development of new photonics technologies. The research reported in this thesis focuses on two such aspects of photonic materials characterization: Magneto-Optic characterization and Spectroscopic Ellipsometry. The theoretical and experimental basis of these two techniques, and experimental data analysis are presented in two parts. In Part 1, the changes in magneto-optic parameters of FePT PS-P2VP block copolymer nanocomposites with increasing concentrations of FePt nanoparticles in the block copolymer are analyzed. We present the results of change in MO anisotropy factor with the wt% of FePt and try to analyze these changes with further experimentation. Part 2 presents the results of spectroscopic ellipsometry of group III-IV multilayered thin film materials to give their precise thicknesses and optical constants. Both these techniques are unique ways to understand novel material characteristics for future use in device development.
4
Bosley, Amber L. "Algae Characterization and Processing Techniques." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321538296.
5
FRANCO, CAROLINE SOUSA. "GLASS ELECTROTHERMAL POLING AND CHARACTERIZATION TECHNIQUES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5435@1.
Анотація:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOERICSSON DO BRASIL
É possível criar uma não-linearidade de segunda ordem em amostras de sílica a partir do processo de polarização. Essas amostras vítreas com o X(2) induzido potencialmente podem ser utilizadas na fabricação de componentes como moduladores ópticos e dobradores de freqüência. O processo de polarização eletrotérmica utiliza alta tensão e alta temperatura e forma uma região de depleção de íons (camada de depleção) onde um campo elétrico intenso é gravado de forma permanente dentro da amostra. Neste trabalho, foram utilizadas diferentes técnicas de caracterização para medir a extensão dessa camada e os resultados foram comparados. As técnicas escolhidas foram: Ataque Químico Interferométrico (com ácido fluorídrico), Maker Fringe, Microscopia Óptica e de Força Atômica e Ataque Interferométrico com Medida de Segundo Harmônico em Tempo Real. Além disso, foram feitos alguns estudos paralelos visando à otimização e a reprodutibilidade do processo de polarização. Foram realizadas dessa forma análises sobre o material dos eletrodos utilizados e sobre a influência da condição inicial da superfície da amostra antes da polarização.
It is possible to create a second order non linearity in silica samples with the poling process. The glass samples with an induced X(2) have a potential application on the fabrication of optical devices such as modulators and frequency converters. In the electrothermal poling process, high voltage and high temperature are applied to the samples forming an ion depleted region (depletion layer), where an intense electric field is permanently recorded. In this work, several characterization techniques have been utilized to measure the width of the depletion layer and compared the obtained results. The chosen techniques were: Interferometric Etching, Maker Fringe, Optical and Atomic Force Microscopy and the Interferometric Etching with Real Time Second Harmonic Measurement. In addition to this, we performed other studies aiming the optimization and reproducibility of the poling process. In this way, we analyzed the material used for the electrodes and the influence of the initial condition of the sample surface before poling.
6
Damianou, Christakis 1964. "Characterization techniques for contaminated gate oxide." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/278760.
Анотація:
The effect of homogeneous contamination on the oxide integrity is studied by electrical measurements. The contamination is introduced in the Buffered Oxide Etchant (BOE) used for the pre-oxidation clean. The DC parametric test of forcing 1 nA and measuring voltage across the oxide is used to relate contamination to the leakage current and also to the number of failures. The factors affecting the measured voltage such as temperature, light and noise are eliminated so that contamination dominates the change in the measured voltage. The current-transport mechanism through the oxide was found to obey the Fowler-Nordheim equation at high fields. The barrier height at both interfaces was lowered in some devices. A technique for measuring the low-field breakdown which is caused by defects in the oxide is developed.
7
Stangoni, Maria Virginia. "Scanning probe techniques for dopant profile characterization /." [S.l.] : [s.n.], 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16024.
8
Xia, Huiyong. "Materials characterization using novel ion beam techniques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ28531.pdf.
9
Wisell, David. "Measurement Techniques for Characterization of Power Amplifiers." Doctoral thesis, Stockholm : KTH School of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4566.
10
George, Lindsay. "Characterization of Unsaturated Soils Using Acoustic Techniques." ScholarWorks @ UVM, 2009. http://scholarworks.uvm.edu/graddis/91.
Анотація:
Recently there has been a great interest in the ability to relate the hydro-mechanical properties of soils to their acoustic response. This ability could enhance high resolution non-destructive evaluation of the shallow subsurface, and would have applications in a variety of fields including groundwater and contaminant hydrogeology, oil recovery, soil dynamics, and the detection of buried objects. Groundwater hydrologists and environmental engineers are challenged with the task of characterizing the material, mechanical and hydraulic properties of the subsurface with limited information generally collected from discrete points. Geophysical testing offers a suite of measurement techniques that allow for the non destructive evaluation of potentially large areas in a continuous manner. Acoustic testing is one geophysical method used by many professions to characterize the subsurface. Unsaturated and multiphase flow modeling relies on the relationship between the capillary pressure and the level of saturation of the porous media. It has been previously suggested that this relationship may be non-unique and rate dependent. A theory which relates this dynamic relationship to the acoustic properties of the soil was developed by others. This research attempts to experimentally verify this theory by meeting the following three objectives: (1) develop an apparatus and procedure to collect acoustic waveforms on laboratory sized unsaturated soil samples, (2) develop a forward modeling technique using a one-dimensional wave propagation model as an alternative analysis method for waves collected on relatively small laboratory specimens, and (3) apply the theory to the measured acoustic data in an attempt to predict the dynamic behavior of the capillary pressure relationship. The acoustic data collected showed variation in compressional wave velocity and attenuation with saturation, and the trends were consistent with data collected by others in partially saturated rocks. The forward modeling technique was shown to provide objective results with reasonable accuracy and low computational time. The dynamic effects predicted with these acoustic measurements did not sufficiently explain the dynamic behavior seen in the laboratory. This is attributed to other causes of significant attenuation not accounted for in the wave propagation theory that was evaluated.
11
Shukla, Anuj. "Characterization of microemulsions using small angle scattering techniques." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969395817.
12
Lakshminarayanan, S. "Process characterization and control using multivariate statistical techniques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq21588.pdf.
13
Potvin-Trottier, Laurent. "Temporal frequency image correlation techniques: development and characterization." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110729.
Анотація:
Protein transport and trafficking are essential processes in living cells and therefore, important to understand. Spatio-temporal image correlation spectroscopy (STICS) allows quantification of the magnitude and direction of flow of fluorescently tagged proteins inside living cells. This is done through computation of the space-time correlation function of the intensity recorded in image series acquired via standard fluorescence microscopy. However, this powerful technique is often hindered by a high concentration of immobile particles in cells. New methods overcoming this problem will be developed in this thesis.We start by creating a theoretical framework for spatio-temporal correlation functions. This allows easy extension to more complex type of kinetics, but more importantly, it constitutes the basis for our new techniques. Most of these techniques share a common characteristic: they rely on the time frequency space to separate populations of particles with different transport properties from each other. Effectively, slow dynamics are concentrated in the low frequencies, allowing extraction of faster dynamics for a minority population.The first approach we propose is based on the theory of discrete-time signal processing. We use a highpass first-order Butterworth infinite-impulse response (IIR) filter on a pixel-per-pixel basis to select the dynamics we are interested in from a particular data set. Via a dimensionless analysis, we show a first approximation on how this filter will affect measurements of flowing and diffusing populations of particles. This filter can be tuned to select particular dynamics and, in contrast to a previously developed filter, does not depend on the length of the time series to be analyzed. An alternative analysis is to look at only the asymmetric part of the correlation function, since flows are the only asymmetric component.The second approach is to look directly in temporal frequency space, or nu-space. Two new spaces of analysis are introduced, nu-space image correlation spectroscopy (nICS) and k-nu-space image correlation spectroscopy (knICS) for its spatial reciprocate. We derive the form of the correlation function for simple dynamics in knICS. In nICS, due to analytic difficulties we simply derive the form for a simple flow.Finally, we use numerical simulations to show the validity of our approaches and explore the strengths and limits of the newly developed techniques. We show that they are only moderately affected by immobile concentration, noise and other background populations. However, the ratio of flow to the diffusion coefficient in biased diffusion is the major constraint. Two new parameters which were previously not accessible with image correlation analysis are extracted from simulations, the diffusion coefficient of a biased diffusion and flow density.This thesis provides new image correlation tools, which complement existing ones, that promise to shed light on the complicated inner workings of the cell.Le transport et l'adressage de protéines sont des procédés essentiels pour la cellule; leur compréhension est donc primordiale. La spectroscopie de corrélation spatio-temporelle d'images (spatio-temporal image correlation spectroscopy, STICS) permet la quantification de l'amplitude et de la direction du débit de protéines fluorescentes à l'intérieur de cellules vivantes. Ceci est possible à l'aide du calcul de la fonction de corrélation spatio-temporelle d'une série d'images acquises à l'aide d'un microscope à fluorescence standard. Par contre, cette technique est souvent limitée par de hautes concentrations de particules immobiles. De nouvelles méthodes pour surmonter ce problème seront développées dans ce mémoire. Nous commencerons par développer un cadre théorique pour les fonctions de corrélation spatio-temporelle. Ceci nous permet de généraliser facilement les méthodes pour prendre en compte des dynamiques plus complexes, mais, surtout, ceci constitue la base pour nos nouvelles techniques. La plupart de ces méthodes partagent une caractéristiques communes: elles utilisent les fréquences temporelles afin de séparer les populations possédant des propriétés de transport différentes. En effet, les dynamiques lentes sont situées dans la région des basses fréquences, permettant ainsi l'extraction de dynamiques rapides de populations minoritaires. La première approche que nous proposons se base sur la théorie du traitement de signal à temps discret. Nous utilisons un filtre passe-haut de type Butterworth de premier ordre (réponse à une impulsion infinie, infinite-impulse response, IIR) appliqué sur chaque pixel afin de sélectionner les dynamiques recherchées dans nos données. À l'aide d'une analyse adimensionnelle, nous montrons une première approximation de l'effet de ce filtre sur des populations de flux et de diffusion. Une analyse alternative est d'isoler la partie asymétrique de la fonction de corrélation, puisque seulement les populations de flux s'y retrouvent.La deuxième approche est d'inspecter directement l'espace des fréquences temporelles, ou l'espace nu. Deux nouveaux espaces d'analyse sont présentés, la spectroscopie de corrélation d'images dans l'espace nu (nu-space image correlation spectroscopy, nICS) et la spectroscopie de corrélation d'images dans l'espace k-nu (k-nu-space image correlation spectroscopy, knICS). Nous dérivons la forme de la fonction de corrélation pour des dynamiques simples pour knICS mais, dues à des difficultés analytiques, nous présentons seulement la forme de la fonction d'un flux pour nICS. Enfin, nous utilisons des simulations numériques afin de montrer la validité de nos approches en plus d'explorer les forces et les limites de chacune d'entre elles. Nous montrons qu'elles sont peu affectées par la concentration de particules immobiles, le bruit et les autres populations d'arrière-plan. Néanmoins, le ratio entre la vitesse et la diffusion pour une diffusion biaisée émerge comme une contrainte majeure. Deux nouveaux paramètres précédemment non accessibles aux techniques d'imagerie de corrélation sont extraits soit le coefficient de diffusion d'une diffusion biaisée ainsi que la densité de flux. Ce mémoire fournit de nouveaux outils d'imagerie de corrélation, complétant ainsi les techniques pré-existantes, qui promettent de faire la lumière sur le fonctionnement complexe des cellules.
14
LaPointe, Jamie. "Adaptive estimation techniques for resident space object characterization." Thesis, The University of Arizona, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10250698.
Анотація:
This thesis investigates using adaptive estimation techniques to determine unknown model parameters such as size and surface material reflectivity, while estimating position, velocity, attitude, and attitude rates of a resident space object. This work focuses on the application of these methods to the space situational awareness problem.
This thesis proposes a unique method of implementing a top-level gating network in a dual-layer hierarchical mixture of experts. In addition it proposes a decaying learning parameter for use in both the single layer mixture of experts and the dual-layer hierarchical mixture of experts. Both a single layer mixture of experts and dual-layer hierarchical mixture of experts are compared to the multiple model adaptive estimation in estimating resident space object parameters such as size and reflectivity. The hierarchical mixture of experts consists of macromodes. Each macromode can estimate a different parameter in parallel. Each macromode is a single layer mixture of experts with unscented Kalman filters used as the experts. A gating network in each macromode determines a gating weight which is used as a hypothesis tester. Then the output of the macromode gating weights go to a top level gating weight to determine which macromode contains the most probable model. The measurements consist of astrometric and photometric data from non-resolved observations of the target gathered via a telescope with a charge coupled device camera. Each filter receives the same measurement sequence. The apparent magnitude measurement model consists of the Ashikhmin Shirley bidirectional reflectance distribution function. The measurements, process models, and the additional shape, mass, and inertia characteristics allow the algorithm to predict the state and select the most probable fit to the size and reflectance characteristics based on the statistics of the measurement residuals and innovation covariance. A simulation code is developed to test these adaptive estimation techniques. The feasibility of these methods will be demonstrated in this thesis.
15
Pathange, Lakshmi Prasad. "Characterization of protein microstructure by various chromatographic techniques." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/26851.
Анотація:
Due to the rising health care costs and with the advent of biogenerics, there is a growing demand to develop new and reliable techniques to characterize proteins and biopharmaceuticals. In addition, characterization aids in understanding the intricate relationship between a protein's structure and its function. To address this challenge, two protein structural parameters, 1) amino acid surface area and 2) amino acid microstructure, were chosen to be investigated. Two chromatographic techniques, 1) ion exchange chromatography (IEC) and 2) immobilized metal affinity chromatography (IMAC), were used to characterize the above-mentioned protein structure parameters.
The model protein chosen for our work is T4 lysozyme. The protein consists of 164 amino acids with molecular weight ~ 18 kD. SYBYL 7.1 software was used to generate in silico point mutants. Two categories of protein variants (point mutants) were generated using site-directed protein mutagenesis. The goal for generating point mutants was to obtain mutants that vary in the two structural parameters. The first category point mutants vary in the surface accessibility of a surface accessible histidine residue. The second category point mutants predominantly vary in protein net charge and the amino acid microstructure. In total, seventeen point mutants were generated: 1) category I consists of seven variants that vary predominantly in their histidine surface accessibility, and were obtained by replacing a charged amino acid residue at different locations on the surface of the protein molecule, and 2) category II consists of ten variants that vary in both net charge and charge distribution were obtained by replacing charged and neutral amino acid residues at different locations (different microenvironments) on the protein surface.
PCR technique was used to generate the point mutants. Gene and protein sequencing were employed to confirm the veracity of point mutation. CD and Lysozyme activity assays were performed to determine whether or not the 3D structure of all the protein variants was intact. Zonal analysis was used to obtain the binding strength values of all seventeen variants in IMAC with copper as the immobilized metal ions, and gradient elution method was used to obtain the relative retention times (rRT) values of all the variants in IEC.
The seven lysozyme variants generated in category I each contains one surface histidine residue. In IMAC, there is a correlation between the surface accessibility of the lone surface histidine and the protein's binding strength with R²⁺= 0.76. In IEC, the correlation between the protein's microstructure, which predominantly consists the surface accessibility of the histidine residue, and the protein's retention times was R²⁺= 0.95. However, there were few outlier variants (e.g. variant K83H) which did not follow the correlations. The variations presented by few outlier variants can be attributed to the presence of intramolecular bonds, which restrict the mobility of the amino acid side chains and subsequently hinder the specific interaction between the amino acid residue and chromatographic media.
For category II variants, short and medium range charge perturbations around the sole histidine residue in T4 lysozyme were engineered within 15 Ã distance of histidine. There was a strong correlation (R²⁺ = 0.96) between the theoretical (DeltaDeltaGElec) values, calculated using simple Coulomb's law, and the experimental (DeltaDeltaGB) values, which were obtained by measuring the protein binding strength values using IMAC. Similar correlation (R²⁺= 0.93) was obtained between the change in net charge (-2 to +2 units) and the relative retention times in IEC. Similarly, there were few variants (e.g. S136K, R76D) that did not follow the trends. The deviations of the few outlier variants can be attributed to the presence of unique microstructure effects around the histidine residue. These microstructure effects were quantified in IMAC as (DeltaDeltaGMicro), and in IEC they were quantified by the change in rRT values.
In summary, all seventeen variants had different binding strengths and rRT values indicating the variation in the protein structure around the histidine residue. Our work reveals that it is possible to capture the microstructural effects of a protein through the combination of protein molecular modeling and simple chromatographic experiments.Ph. D.
16
Clinton, Jamie C. "Colloidal Cerium Oxide Nanoparticle: Synthesis and Characterization Techniques." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31065.
Анотація:
Fluorescence spectra and UV-Vis absorption spectra are collected on cerium oxide nanocrystalline particles. While CeO2 is the stable form of bulk cerium oxide, ceria nanoparticles exhibit a nonstoichiometric composition, CeO2-γ, due to the presence of oxygen vacancies and the formation of Ce2O3 at the grain boundaries. The Ce(III) ions, which are more reactive and therefore more desirable for various applications, are created by oxygen vacancies, which act as defects in the CeO2-γ crystal lattice. These defects form trap states in the band gap of CeO2, which can be seen in the absorption spectra. Ce(III) is required for fluorescence of the ceria nanoparticles while Ce(IV) is involved in only nonradiative transitions. The optical spectroscopy results show that the ceria samples have different ratios of Ce(III) ions to Ce(IV) ions, which is verified by x-ray photoemission spectroscopy (XPS).Master of Science
17
Li, Linlin. "Microstructure characterization of polymers by modern NMR techniques." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353000762.
18
Borkar, Neha. "Characterization of microporous membrane filters using scattering techniques." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289943937.
19
Mendes, José de Araújo. "Leather inspection and characterization using non-destructive techniques." Thesis, University of Hull, 2000. http://hydra.hull.ac.uk/resources/hull:5624.
Анотація:
Leather is a widely used component of many products such as shoes, car seats, garments and other leather goods. Because it is a natural material, a tanned hide will contain visual and hidden flaws. In addition, its mechanical properties vary over the hide. At present, hides are inspected and assessed by skilled operatives. Further, current objective leather testing requires removal of samples and is either destructive and/or incompatible with real time operation, and little or no information about the rest of the skin is provided. A novel mechanical scanning system was built for non-destructive leather testing. The investigation was focused on two of the most important physical leather properties, static compressibility across thickness and tensile properties for low strain regions. The results of static compression energy measurements for a compressive strain of 10 percent, showed a close agreement with the results of tests performed by a conventional compressibility tester. Further, the results of strain energy and stress measurements for a strain of 2 percent, revealed a very good correlation with the results of conventional tensile tests for a similar strain. The application of infrared thermography, a non destructive and contact less technique, to leather characterisation and inspection was investigated in this work. It was shown that this technique could be used for detecting defects in leather, as well as for estimating their size and deepness. However, defect visibility by infrared thermography is conditioned by the fact that a defective area has to cause different material properties or produce an internal thermal resistance. Further, the prohibitive cost of infrared thermography cameras for automation is a serious limitation for its application in current leather testing. It is recommended that the ideal testing system would be based on the combination of mechanical scanning, normal computer vision and infrared thermography. The normal computer vision part of this system would be responsible for measuring area and detecting defects that are visible in nature. The infrared thermography part of the system would be responsible for detecting the type of defects overlooked by the previous method, as well as some thermo-physical parameters. Finally, the Mechanical Scanning System would provide the physical properties of leather, like compressibility, tensile modulus, shear stress and softness that the vision based inspection systems are incapable of providing. In this way, every single skin could be completely characterised in terms of defects and physical properties.
20
LaPointe, Jamie J., and Jamie J. LaPointe. "Adaptive Estimation Techniques for Resident Space Object Characterization." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/623263.
Анотація:
This thesis investigates using adaptive estimation techniques to determine unknown model parameters such as size and surface material reflectivity, while estimating position, velocity, attitude, and attitude rates of a resident space object. This work focuses on the application of these methods to the space situational awareness problem. This thesis proposes a unique method of implementing a top-level gating network in a dual-layer hierarchical mixture of experts. In addition it proposes a decaying learning parameter for use in both the single layer mixture of experts and the dual-layer hierarchical mixture of experts. Both a single layer mixture of experts and dual-layer hierarchical mixture of experts are compared to the multiple model adaptive estimation in estimating resident space object parameters such as size and reflectivity. The hierarchical mixture of experts consists of macromodes. Each macromode can estimate a different parameter in parallel. Each macromode is a single layer mixture of experts with unscented Kalman filters used as the experts. A gating network in each macromode determines a gating weight which is used as a hypothesis tester. Then the output of the macromode gating weights go to a top level gating weight to determine which macromode contains the most probable model. The measurements consist of astrometric and photometric data from non-resolved observations of the target gathered via a telescope with a charge coupled device camera. Each filter receives the same measurement sequence. The apparent magnitude measurement model consists of the Ashikhmin Shirley bidirectional reflectance distribution function. The measurements, process models, and the additional shape, mass, and inertia characteristics allow the algorithm to predict the state and select the most probable fit to the size and reflectance characteristics based on the statistics of the measurement residuals and innovation covariance. A simulation code is developed to test these adaptive estimation techniques. The feasibility of these methods will be demonstrated in this thesis.
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Wozniak, Mariusz. "Characterization of nanoparticle aggregates with light scattering techniques." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4818/document.
Анотація:
Ce travail de thèse de doctorat propose et évalue différentes solutions pour caractériser, avec des outils optiques et électromagnétiques non intrusifs, les nanoparticules et agrégats observés dans différents systèmes physiques : suspensions colloïdales, aérosols et plasma poussiéreux. Deux types de modèles sont utilisés pour décrire la morphologie d'agrégats fractals (p. ex. : suies issues de la combustion) et agrégats compacts (qualifiés de « Buckyballs » et observés dans des aérosols produits par séchage de nano suspensions). Nous utilisons différentes théories et modèles électromagnétiques (T-Matrice et approximations du type dipôles discrets) pour calculer les diagrammes de diffusion (ou facteur de structure optique) de ces agrégats, de même que leurs spectres d'extinction sur une large gamme spectrale. Ceci, dans le but d'inverser différentes données expérimentales. Différents outils numériques originaux ont également été mis au point pour parvenir à une analyse morphologique quantitative de clichés obtenus par microscopie électronique. La validation expérimentale des outils théoriques et numériques développés au cours de ce travail est focalisée sur la spectrométrie d'extinction appliquée à des nano agrégats de silice, tungstène et siliciumThis Ph.D. work provides and evaluates various solutions to characterize, with optical/electromagnetic methods nanoparticles and aggregates of nanoparticles found in suspensions, aerosols and dusty plasmas. Two main models are introduced to describe the morphology of particle aggregates with fractal-like (for particles in plasmas and combustion systems) and Buckyballs-like (aerosols, suspensions) shapes. In addition, the author proposes various solutions and methods (T-Matrix, Rayleigh type approximations) to calculate the scattering diagrams (optical structure factors) of fractal aggregates as well as algorithms to inverse extinction spectra. As a reference case for the performed analysis, several tools to describe the morphology of fractal aggregates from electron microscopy images have been also developed. The experimental validation carried out with the Light Extinction Spectrometry (LES) technique (for nano silica beads, tungsten, dusty plasma and silicon aggregates) clearly proves the validity of the algorithms developed as well as the potential of the LES technique
22
De, Leonardis Piero. "Preparation and characterization techniques for nano-structured materials." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/preparation-and-characterization-techniques-for-nanostructured-materials(5b5468e8-1fe7-4baa-b073-9ce51f2b280a).html.
Анотація:
The first part of the project focused on the optimization of processes for the preparation of enzyme-containing silicagel nanoparticles and for their coating and stabilization with a polycationic layer. A procedure for coating surfaces with polymer layers was established. Atom transfer radical polymerization was used for the synthesis of a cationic macroinitiator adsorbed on the anionic surface of near-monodisperse silica nanoparticles, used as model for enzyme-containing silicagel nanoparticles. The latter were easily purified via gel filtration, while enzymatic activity was substantially retained during both macroinitiator adsorption and gel filtration. The subsequent growth of water soluble poly (glycerol monomethacrylate) (pGMMA) via ATRP onto coated enzyme-containing silicagel nanoparticles was achieved in a living fashion and with a substantial retention of the activity of encapsulated enzymes. The decoration of the surface with hydrophilic and protein-repellent polymers can provide 'stealth' properties to the supported enzymes, which can be eventually functionalized to obtain more sophisticated biologically responsive nanoparticles.In the second part of the project characterization of nano-structured materials at sub-nanometer resolution was achieved by Atomic Force Spectroscopy (AFM) to probe simultaneously the structure and specific chemical and physical parameters of the system. At the same time, the force-deformation behavior of nano-structured materials subjected to concentrated loads (nanoindentation) yield detailed information and insight about their local mechanical and adhesion properties. In particular, we have focused on the characterization of nanoparticles, surface layers and self-assembled fibrillar materials, combining imaging with a local mechanical (Young's modulus) and physical (adhesion force and surface energy) analysis of the materials.
23
Wang, Xing. "Human motion sequence characterization using machine learning techniques /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?mphil-cs-b23750492f.pdf.
Анотація:
Thesis (M.Phil.)--City University of Hong Kong, 2009."Submitted to Department of Computer Science in partial fulfillment of the requirements for the degree of Master of Philosophy." Includes bibliographical references (leaves [152]-163)
24
Bányay, Dániel. "MLSurf : Surfer Motion Characterization Using Machine Learning Techniques." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264921.
Анотація:
Wave surfing is a popular sport that requires minimal financial investment, while it can still be enjoyable from the very first attempt. At the same time, the demand for smart devices that enhance the experience of doing sports by analyzing and evaluating the activities is growing. For surf sport, there are some solutions that are able to collect statistics about activities being done during a surf session, but none of them is able to recognize specific maneuvers that are performed during wave riding. The goal of this Master Thesis is to improve a currently existing surf activity monitoring solution by extending it with the ability to identify the two most common surf maneuvers during a wave riding session, namely cutback and snap. The solution is using the user’s smartphone to collect IMU sensor data and feed it to a classification pipeline. The implemented algorithm takes raw sensor data as an input, performs various preprocessing steps, splits the input stream into segments, extracts features from these segments and feed them into a hierarchical classification tree. The implemented pipeline is able to classify non-maneuver, cutback and snap segments with 78% accuracy on a self-collected dataset.Vågsurfing är en populär sport som kräver minimala finansiella investeringar, medan det kan vara roligt från första början. Samtidigt växer efterfrågan på smarta enheter som förbättrar sportupplevelsen genom att analysera och utvärdera aktiviteterna. För surfsport finns det några lösningar som kan samla in data om aktiviteter som utförs under en surfsession, men ingen av dem kan känna igen specifika manövrar som utförs under vågsurfing. Målet med denna uppsats är att förbättra en befintlig lösning för surfaktivitetsövervakning genom att utöka den med förmågan att identifiera de två vanligaste surfmanövren nämligen cutback och snap. Lösningen använder användarens smartphone för att samla IMU-sensordata och mata dem till en klassificeringspipeline. Den implementerade algoritmen tar råa sensordata som input, utför olika förbehandlingssteg, segmenterar input-strömmen, extraherar funktioner från dessa segment och matar in dem i ett hierarkiskt klassificeringsträd. Den implementerade pipeline kan klassificera non-maneuver-, cutback- och snapsegment med 78% noggrannhet på ett självsamlat dataset.
25
Xu, Ming. "Photoluminescence Techniques for the Characterization of Photovoltaic Interfaces." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS053/document.
Анотація:
Dans ce travail, nous avons appliqué des techniques de photoluminescence en régime stationnaire (PL) et photoluminescence en régime modulé (MPL) à l'étude d'hétérojonctions formées entre du silicium cristallin (c-Si) et du silicium amorphe hydrogéné (a-Si:H). Plus précisément, nous avons comparé des échantillons constitués de dépôts de (n)a-Si:H, (i)a-Si:H, (n)a-Si:H/(i)a-Si:H, et (p)a-Si:H/(i)a-Si:H sur des wafers de (n) c-Si de haute qualité électronique. Les mesures en fonction de la température montrent que la durée de vie des porteurs en excès diminue lorsque la température diminue, ce qui peut être qualitativement reproduit par la simulation dans un mécanisme de recombinaison de type Shokley-Read-Hall (SRH) en tenant compte du niveau d’énergie du dopant (phosphore) dans le substrat et de niveaux peu profonds électroniquement actifs à l'interface.Nous avons également étudié des échantillons dopés par implantation d'ions puis passivés par AlOx, a-Si:H et SiC. Des signatures de dislocations sont révélées à basse température par des pics supplémentaires de PL.Nous avons également comparé les résultats de cartographies de PL et de durée de vie obtenues par l'analyse de l'amplitude de MPL, et par l'analyse de son déphasage. Il est constaté que les propriétés optiques des échantillons ont un grand impact sur la cartographie PL, ce qui pourrait conduire à une conclusion erronée sur leur homogénéité. En revanche, les cartographies de durée de vie sont moins sujettes à des variations de paramètres optiques et au bruit provenant du processus de mesure, phénomènes qui ne sont pas intrinsèques à l'échantillon étudié.La nature différentielle de la mesure MPL est étudiée. Nous démontrons la notion de durée de vie à l'état stationnaire et de durée de vie différentielle. Nous analysons différents types de recombinaisons avec la durée de vie MPL et avons mis en œuvre des simulations des hétérojonctions a-Si:H/c-Si. Nous constatons que dans le domaine d'excitation intéressant pour le photovoltaïque, la durée de vie différentielle est souvent inférieure à la durée de vie à l'état stationnaire. Nous faisons aussi des comparaisons entre les durées de vie obtenues par mesures dites QSSPC et MPL et montrons qu'elles sont en fait égales.La combinaison des techniques de PL et de MPL nous a permis d'étudier le coefficient de recombinaison radiative en fonction de la température. Les résultats publiés jusqu'ici dans la littérature couvrent la plage de température de 300 K à 90 K. Dans cette plage, nos résultats sont en très bon accord avec ces résultats publiés précédemment. Mais, grâce à notre système de mesure et à la combinaison PL/MPL, nous avons obtenu des valeurs de ce coefficient jusqu’à 20 K et nous avons pu proposer une fonction polynômiale du cinquième degré qui permet de bien reproduire les variations en fonction de la température sur toute la plage de 20 K à 300 K.Dans une dernière partie de la thèse, les propriétés de transport de porteurs et l'effet de couplages sont étudiés dans des empilements de quantum dots. Nous avons examiné les quantum dots de InAs qui croissent de manière ordonnée en formant des chaînes à partir d'une couche tampon en InGaAs (couche dite de "cross hatch pattern"). Nous avons caractérisé par PL des monocouches ainsi que des multicouches empilées de chaînes de quantum dots. L'effet de couplage entre dots dans le plan est observé sur des échantillons de monocouches, et nous remarquons une inhibition du couplage vertical entre couches qui est expliqué par l'effet du champ de déformation de la couche de cross hatch patternSilicon solar cells remain the driving technology and dominate the photovoltaics market. Hydrogenated amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction cells achieve the best efficiency in silicon cells to date (25.6%). A great part of this achievement is assigned to the improvement of the passivation of the emitter/absorber interface. In that regard, luminescence techniques whether Photoluminescence (PL) or Modulated photoluminescence (MPL), are particularly appropriate to investigate surface defects and effective carrier lifetime.In this work, we developed a PL/MPL setup coupled to a helium cooled cryostat to the study of a-Si:H/c-Si heterojunctions. Considering the modulated nature of the MPL, we introduced the concept of steady state lifetime and differential lifetime. Through simulations, we analyzed different types of recombination mechanisms and found that the differential lifetime is lower than the steady state lifetime. We also benchmarked the lifetime determined by photoconductance decay measurements and the MPL lifetime and demonstrated that they are actually equal.We have analyzed various samples of a-Si:H/c-Si heterojunctions from multiple sources, particularly within the framework of the European project HERCULES (High Efficiency Rear Contact solar cells and Ultra powerful moduLES). The samples are composed of various doping and passivation layers such as AlOx, a-Si:H and a-SiC:H fabricated on high quality (n)c-Si wafers. The temperature dependent measurements show that the excess carrier lifetime decreases when temperature decreases, which is explained by the Shockley-Read-Hall recombination model at the heterojunction interface. The combination of PL and MPL measurements have enabled us to determine the radiative recombination coefficient in crystal silicon as a function of temperature. Our measurements have extended the original data to 20 K. We propose a fifth order polynomial of the radiative recombination coefficient as a function of temperature in the range of 20 to 300 K and it agrees very well to others’ work.We also investigated the possibility to extend the system to carry out PL and MPL mapping in order to extract the cell homogeneity and the lifetime distribution across the sample. We found that the optical property of sample has a significant impact on the PL mapping and could lead to incorrect conclusion with respect to the homogeneity. However the lifetime mapping from MPL produces imaging that is less prone to variation of optical properties.At last, we utilized the temperature dependent micro PL to investigate the coupling of InAs quantum dot chains (QDC) stacks grown on InGaAs cross hatch patterns separated with a 10 nm GaAs layer. The PL spectra are dominated by the top-most stack, indicating that the QDC layers are nominally uncoupled. However, under the high excitation power densities achievable with the micro PL system, when the high-energy peaks of the top stack are saturated, low-energy PL peaks from the bottom stacks emerge as a result of the carrier transfer across the GaAs spacers. These unique PL signatures contrast with the state-filling effects in conventional, coupled QD stacks and serve as a means to quickly assess the presence of electronic coupling in stacks of dissimilar-sized nanostructures
26
Maggio, Simona <1984>. "Analysis and modeling techniques for ultrasonic tissue characterization." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3333/1/maggio_simona_tesi.pdf.
Анотація:
This thesis introduces new processing techniques for computer-aided interpretation of ultrasound images with
the purpose of supporting medical diagnostic. In terms of
practical application, the goal of this work is the improvement of current prostate biopsy protocols by providing physicians with a visual map overlaid over ultrasound images marking regions potentially affected by disease. As far as analysis techniques are concerned, the main contributions of this work to the state-of-the-art is the introduction of deconvolution as a pre-processing step in the standard ultrasonic tissue characterization procedure to improve the diagnostic significance of ultrasonic features.
This thesis also includes some innovations in ultrasound
modeling, in particular the employment of a continuous-time autoregressive moving-average (CARMA) model for ultrasound signals, a new maximum-likelihood CARMA estimator based on exponential splines and the definition of CARMA parameters as new ultrasonic features able to capture scatterers concentration.
Finally, concerning the clinical usefulness of the developed techniques, the main contribution of this research is showing, through a study based on medical ground truth,
that a reduction in the number of sampled cores in standard
prostate biopsy is possible, preserving the same diagnostic
power of the current clinical protocol.Cette thèse introduit de nouvelles techniques de traitement pour l’interprétation guidée d’images ultrasons, dans le but de soutenir le diagnostic médical. L’objectif pratique de ce travail est l’amélioration du protocole standard pour la biopsie de la prostate, en fournissant au médecin une carte visuelle sur l’écographie qui marque les régions potentiellement malignes. En ce qui concerne les techniques d’analyse, la contribution principale de cette thèse est l’introduction de la déconvolution comme étape de pré-traitement dans la procédure standard de caractérisation des tissus par ultrasons, afin d’améliorer la valeur diagnostique des caractéristiques du signal. Cette thèse présente, en outre, des innovations dans la modélisation du signal ultrason, en particulier la proposition d’un modèle autorégressif à moyenne glissante en temps continu (CARMA), le développement d’un nouvel estimateur au maximum de vraisemblance de paramètres CARMA fondé sur les splines exponentielles et la définition des paramètres CARMA comme des nouvelles caractéristiques du signal ultrason capables de capturer l’information sur la concentration de scatterers. Enfin, concernant l’utilité clinique des techniques développées, la contribution principale de cette recherche est dans la démonstration, au travers d’une étude médicale, de la possibilité de réduire concrètement le nombre d'échantillons prélevés pendant la biopsie de la prostate standard, en préservant le même pouvoir diagnostique du protocole biopsique standard.
27
Maggio, Simona <1984>. "Analysis and modeling techniques for ultrasonic tissue characterization." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3333/.
Анотація:
This thesis introduces new processing techniques for computer-aided interpretation of ultrasound images with
the purpose of supporting medical diagnostic. In terms of
practical application, the goal of this work is the improvement of current prostate biopsy protocols by providing physicians with a visual map overlaid over ultrasound images marking regions potentially affected by disease. As far as analysis techniques are concerned, the main contributions of this work to the state-of-the-art is the introduction of deconvolution as a pre-processing step in the standard ultrasonic tissue characterization procedure to improve the diagnostic significance of ultrasonic features.
This thesis also includes some innovations in ultrasound
modeling, in particular the employment of a continuous-time autoregressive moving-average (CARMA) model for ultrasound signals, a new maximum-likelihood CARMA estimator based on exponential splines and the definition of CARMA parameters as new ultrasonic features able to capture scatterers concentration.
Finally, concerning the clinical usefulness of the developed techniques, the main contribution of this research is showing, through a study based on medical ground truth,
that a reduction in the number of sampled cores in standard
prostate biopsy is possible, preserving the same diagnostic
power of the current clinical protocol.Cette thèse introduit de nouvelles techniques de traitement pour l’interprétation guidée d’images ultrasons, dans le but de soutenir le diagnostic médical. L’objectif pratique de ce travail est l’amélioration du protocole standard pour la biopsie de la prostate, en fournissant au médecin une carte visuelle sur l’écographie qui marque les régions potentiellement malignes. En ce qui concerne les techniques d’analyse, la contribution principale de cette thèse est l’introduction de la déconvolution comme étape de pré-traitement dans la procédure standard de caractérisation des tissus par ultrasons, afin d’améliorer la valeur diagnostique des caractéristiques du signal. Cette thèse présente, en outre, des innovations dans la modélisation du signal ultrason, en particulier la proposition d’un modèle autorégressif à moyenne glissante en temps continu (CARMA), le développement d’un nouvel estimateur au maximum de vraisemblance de paramètres CARMA fondé sur les splines exponentielles et la définition des paramètres CARMA comme des nouvelles caractéristiques du signal ultrason capables de capturer l’information sur la concentration de scatterers. Enfin, concernant l’utilité clinique des techniques développées, la contribution principale de cette recherche est dans la démonstration, au travers d’une étude médicale, de la possibilité de réduire concrètement le nombre d'échantillons prélevés pendant la biopsie de la prostate standard, en préservant le même pouvoir diagnostique du protocole biopsique standard.
28
CIGANDA, LYL MERCEDES. "New Techniques for Reliability Characterization of Electronic Circuits." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2507391.
Анотація:
Integrated electronic systems are increasingly used in an wide number of applications and environments, ranging from critical missions to low cost consumer products. Information processing has been thoroughly integrated into everyday objects and activities, in the so-called ubiquitous computing paradigm. This wide distribution is caused mainly by the miniaturization of semiconductor devices (transistor channel length scaling from 180 nm in 1999 to 22 nm in 2012), which allows integrating a complete system on a single chip (SoC). However, there are many difficult challenges associated with continued cost reduction, size reduction, improved performance and improved power efficiency.
One of these challenges is the reliability of these electronic systems. Important research efforts are aimed at improving the reliability of semiconductors. Manufacturing processes, intrinsic aging phenomena of components and environmental stress may cause internal defects and damages during the lifetime of a system, possibly causing misbehaviours or failures. In order to guarantee product quality and consumer satisfaction, it is necessary not only to discover faults as soon as possible in the manufacturing process, but also to continuously check for their absence throughout a product lifetime.
Today’s modern systems have become increasingly complex to design and build, while the demand for reliability and cost effective development continues. Reliability is one of the most important attributes in all these systems, including aerospace applications, real-time control, medical care, defence equipment, transportation, communication, entertainment products, agriculture, energy and environmental systems. Growing international competition has increased the need for all designers, managers, practitioners, scientists and engineers to ensure a high level of reliability of their product before release and during mission time, at the lowest cost. The interest in reliability has been growing in recent years and this trend will continue during the next decade and beyond.
With testers being expensive pieces of equipment and the cost of transistors continuously decreasing, it make sense to use some of these low-cost transistors to replace the costly test tools, whenever possible.
The first low cost approach we can think about is using the devices themselves to implement their own test. This is the underlying motivation of functional Software-Based Self-Test (SBST): a fast, powerful microprocessor, which has lots of resources, could certainty help in its testing procedure. Having the outstanding advantages of enabling at-speed testing, zero area overhead and actually testing the device’s operation, this approach also has some drawbacks. Even if SBST is essentially suitable for online testing (and sometimes it is the only possible approach), it requires some dedicated system memory for the functional testing data, which can reach very big sizes. Also some faults happen to be functionally untestable; i.e., you cannot detect them exclusively by running proper software routines. For this reason a combination of both functional and structural test approaches is common practise.
A second natural approach to low cost testing is design for test (DfT). Add some extra (cheap) area on-chip specifically in charge of performing and managing tests. The DfT path started long ago, but it is still a key element in 2012 International Technology Roadmap for Semiconductors (ITRS)[1] test roadmap. Different sorts of DfT enable the use of low cost testers, contributing to the full checking of a device, and may also be reused for online testing purposes. Logic and Memory Built-In Self Test (BIST) schemas are usual practises. Analogue DfT, even if it is not as advances as digital one, is also an interesting strategy, especially when the analogue or mixed-signal device is integrated in a wider digital system like a SoC
Finally, there are some fields where the use of external (and generally expensive) testers is mandatory. Diagnosis is one of the cases in which an Automatic Test Equipment (ATE) is needed to store the huge amount of retrieved data and to drive the cyclic characteristic of the diagnosis procedure. In particular, even if memories are commonly tested making use of internal BIST structures, their diagnosis demands the use of a tester. Another interesting and blooming field is that of the mixed energy-domain devices as Micro Electro Mechanical Systems (MEMS). MEMS require unique testing apparatus applying both electrical and physical stimuli: movement, pressure, magnetic fields. Additionally, they not only need to be exhaustively tested but in most of the cases also calibrated.
The work described in this thesis falls in low cost testing domain. Strategies for new and/or improved SBST, DfT and ATE mechanisms are proposed, implemented and evaluated. The strategies deal mainly with memories, processor and mixed-signal devices (analogue-to-digital converters is our target device) embedded in Systems-on-a-Chip, where standard communication protocols and wrappers are used to communicate with the device under test.
29
ZUZUL, JOSIP. "Characterization of thunderstorm downburst winds through CFD techniques." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1081542.
Анотація:
The characteristic wind field of a certain region is mostly governed by the climatology of its larger scale area. In the case of mid-latitude regions (e.g. Europe), their climatology is determined by the extra-tropical cyclones at the larger synoptic scale. Atmospheric boundary layer (ABL) winds based on synoptic-scale structures are hence considered as the foundation for codes and standards used to assess the wind loading of structures and to design structures to prevent wind-related damage accordingly. In addition to the ABL winds, the mid-latitude regions are also prone to winds of a non-synoptic origin at the mesoscale level, with thunderstorm outflows or downbursts being the representative of such non-synoptic wind action. Since they are determined by a set of features that makes them fundamentally different from the ABL winds, downbursts can produce the corresponding wind action that is often fatal to low-rise and mid-rise structures. On these grounds, a comprehensive initiative to enable a better understanding of fundamental downburst flow features relevant for the structural loading was framed under the umbrella of the ERC THUNDERR Project. The present thesis, as the numerical modeling part of the THUNDERR Project framework, aims to address the physical characteristics of thunderstorm downbursts through the application of Computational Fluid Dynamics (CFD) technique. The focus of this work is placed on the CFD reconstruction of experimental tests of the reduced-scale thunderstorm downbursts carried out in the WindEEE Dome Research Institute (University of Western Ontario, Canada). Although they recreate the downburst flow field, the experimental analysis is restricted to the limited number of probe points. In that perspective, CFD allows expanding the analysis of experimental tests to the entire flow field, which can reveal phenomenological aspects that are either challenging or impossible to retrieve from experimental tests only. Two fundamental downburst scenarios were analyzed: (i) an isolated vertical downburst, and (ii) a downburst embedded inside the approaching ABL flow. For that purpose, three CFD approaches of a ranging complexity level were adopted. The unsteady Reynolds-Averaged Navier-Stokes (URANS), hybrid Scale-Adaptive Simulations (SAS), and Large-Eddy Simulations were used, and their overall reliability was examined. Theimplications of the WindEEE Dome specific geometrical features (i.e. bell-mouth inflow nozzle) on the downburst flow reconstruction by the facility were further discussed. The bulk of the thesis discusses the dominant flow features of the downburst with the particular emphasis on the dynamics of dominant vortex structures (i.e. primary vortex, secondary vortex, trailing ring vortices) and their spatio-temporal influence on the vertical profiles of radial velocity component. The non-dimensional flow characteristics of interest were evaluated such as the trajectory of the primary vortex and the spatial dependence of the velocity of primary vortex propagation. Analyses were further extended for the case of a joint downburst and ABL wind interaction to address the dynamics between two different wind fields, and the genesis of the worst condition in terms of the maximum radial velocity due to the ABL wind entrainment was discussed. The flow field was analyzed across various azimuth angles with respect to the ABL flow to report on the flow asymmetry, and general implications of such downburst configuration on spatio-temporal evolution of wind velocity profiles which can produce severe conditions for low-rise and mid-rise structures.
30
Playez, Mickaël. "Titan atmosphere plasma characterization using spectroscopic measurement techniques." Châtenay-Malabry, Ecole centrale de Paris, 2006. http://www.theses.fr/2006ECAP1007.
Анотація:
Lors des manoeuvres d'entrée ou d'aérocapture dans l'atmosphère de Titan, une quantité importante d'énergie est émise sous forme de radiation dans la couche de choc présente autour du véhicule spatial. Le dimensionnement du bouclier thermique du véhicule demande une évaluation précise de la quantité d'énergie qu'il reçoit sous forme radiative. Nous proposons dans cette étude une analyse du rayonnement émis par un plasma dont la composition est représentative de l'atmosphère de Titan, et ceci dans l'intervalle de longueur d'onde compris entre 350 et 1000 nm. Le plasma analysé est produit dans un tunnel plasma à couplage inductif (ICP). Des mesures par spectroscopie d'émission sont effectuées pour deux pressions différentes, 300 et 23 mbar. Le cas à haute pression favorise l'équilibre thermodynamique local dans l'écoulement, tandis que le cas à basse pression permet d'étudier un plasma hors équilibre. La modélisation de l'émission radiative du plasma est effectuée pour des conditions d'équilibre thermodynamique et montre un bon accord, sur une échelle absolue de l'émission, avec le spectre mesuré à haute pression. L'application du modèle développé à l'analyse du cas basse pression démontre l'obtention de conditions hors équilibre thermique. Des limitations liées à l'implémentation des mesures sont néanmoins observées. Elles sont liées aux fluctuations du plasma étudiéDuring entry or aero-capture in the atmosphere of the Saturn’s satellite Titan, largeamounts of radiation are produced in the shock layer of a spacecraft. The design of theheat shield of this vehicle requires a precise assessment of the radiative heat flux impingingon it. We propose in this study an analysis of the radiation emitted in the spectral range350-1000 nm by a high temperature gas mixture with a composition representative of theTitan atmosphere composition. The plasma is produced in an Inductively Coupled Plasmawind tunnel. Emission spectroscopy measurements are performed for two different pressureconditions, 300 and 23 mbar, in order to produce equilibrium and non-equilibrium plasmas. The modelling of the plasma emission at equilibrium is performed and shown to agree tothe measured spectra on a absolute scale for the high-pressure case. The use of the samemodel for the analysis of the low-pressure case provides evidence of departure from equilibrium. Limitations of the implemented procedure are observed. They are due to unresolved fluctuations of the plasma source
31
Anger, Sabrina. "Potential and challenges of compound semiconductor characterization by application of non-contacting characterization techniques." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-201487.
Анотація:
Trotz der im Vergleich zu Silizium überragenden elektronischen Eigenschaften von Verbindungshalbleitern, ist die Leistung der daraus gefertigten elektrischen Bauelemente aufgrund der vorhandenen, die elektronischen Materialeigenschaften beeinflussenden Defekte nach wie vor begrenzt. Die vorliegende Arbeit trägt dazu bei, das bestehende ökonomische Interesse an einem besseren Verständnis der die Bauelementeleistung limitierenden Defekte zu befriedigen, indem sie die Auswirkungen dieser Defekte auf die elektronischen und optischen Materialeigenschaften von Indiumphosphid (InP) und Siliziumkarbid (SiC) aufzeigt. Zur Klärung der Effekte finden in der Arbeit sich ergänzende elektrische und optische Charakterisierungsmethoden Anwendung, von denen die meisten kontaktlos und zerstörungsfrei arbeiten und sich daher prinzipiell auch für Routineanalysen eignen. Die erzielten Ergebnisse bestätigen und ergänzen Literaturdaten zum Defektinventar in InP und SiC nutzbringend. So wird insbesondere das Potential der elektrischen Charakterisierung mittels MDP und MD-PICTS, welche in der Arbeit erstmals für die Defektcharakterisierung von InP und SiC eingesetzt wurden, nachgewiesen. Die experimentellen Studien werden dabei bedarfsorientiert durch eine theoretische Betrachtung des entsprechenden Signalentstehungsmechanismuses ergänztAlthough the electronic properties of compound semiconductors exceed those of Silicon, the performance of respective electronic devices still is limited. This is due to the presence of various growth-induced defects in compound semiconductors. In order to satisfy the economic demand of an improved insight into limiting defects this thesis contributes to a better understanding of material inherent defects in commonly used Indium Phosphide (InP) and Silicon Carbide (SiC) by revealing their effects on electronic and optical material properties. On that account various complementary electrical and optical characterization techniques have been applied to both materials. Most of these techniques are non-contacting and non-destructive. So, in principle they are qualified for routine application. Characterization results that are obtained with these techniques are shown to either confirm published results concerning defects in InP and SiC or beneficially complement them. Thus, in particular the potential of electrical characterization by MDP and MD-PICTS measurements is proofed. Both techniques have been applied for the first time for defect characterization of InP and SiC during these studies. The respective experiments are complemented by a theoretical consideration of the corresponding signal development mechanism in order to develop an explanation approach for occasionally occurring experimental imperfection also arising during silicon characterization from time to time
32
Venkatesan, Sriram. "SURFACE TEXTURES FOR ENHANCED LUBRICATION: FABRICATION AND CHARACTERIZATION TECHNIQUES." Lexington, Ky. : [University of Kentucky Libraries], 2005. http://lib.uky.edu/ETD/ukymeen2005t00274/Venkatesan%5FThesis.pdf.
Анотація:
Thesis (M.S.)--University of Kentucky, 2005.Title from document title page (viewed on November 9, 2005). Document formatted into pages; contains viii, 85 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 83-84).
33
Kotte, Timo Oliver. "Application of Image Processing Techniques for Lamb Wave Characterization." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4787.
Анотація:
Characterization of dispersion curves in plate-like structures is possible with guided Lamb waves. In this research, experimental development of dispersion curves relies on the spectrogram, which suffers from the Heisenberg Uncertainty Principle. Reassignment is capable of localizing ill--defined dispersion curves. Unfortunately, reassignment also introduces spurious components, which reduce reassignment performance. This research develops an algorithm that provides both localization of dispersion curves and elimination of spurious components. To achieve this, an alternative formulation
of reassignment called differential reassignment is modified and superimposed with nonlinear anisotropic diffusion. This study first examines reassignment and diffusion components individually. Three different versions of differential reassignment are considered, two of which are modifications explicitly derived in
this research. The combined algorithm is then applied to reassign experimentally measured spectrograms, leading to a significant increase in clarity and notch detection performance.
34
Saberi, Rezmin. "Characterization of femoral prostheses using refined holographic interferometric techniques." Thesis, Queen Mary, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311927.
35
Kozan, Mehmet. "CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/567.
Анотація:
Light scattering is a powerful characterization tool for determining shape, size, and size distribution of fine particles, as well as complex, irregular structures of their aggregates. Small angle static light scattering and elliptically polarized light scattering techniques produce accurate results and provide real time, non-intrusive, and in-situ observations on prevailing process conditions in three-dimensional systems. As such, they complement conventional characterization tools such as SEM and TEM which have their known disadvantages and limitations. In this study, we provide a thorough light scattering analysis of colloidal tungsten trioxide (WO3) nanoparticles in the shape of irregular nanospheres and cylindrical nanowires, and of the resulting aggregate morphologies. Aggregation characteristics as a function of primary particle geometry, aspect ratio of nanowires, and the change in dispersion stability in various polar solvents without the use of dispersants are monitored over different time scales and are described using the concepts of fractal theory. Using forward scattered intensities, sedimentation rates as a result of electrolyte addition and particle concentration at low solution pH are quantified, in contrast to widely reported visual observations, and are related to the aggregate structure in the dispersed phase. For nanowires of high aspect ratios, when aggregate structures cannot directly be inferred from measurements, an analytical and a quasiexperimental method are used.
36
Dai, Sheng. "Natural hydrate-bearing sediments: Physical properties and characterization techniques." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52186.
Анотація:
An extensive amount of natural gas trapped in the subsurface is found as methane hydrate. A fundamental understanding of natural hydrate-bearing sediments is required to engineer production strategies and to assess the risks hydrates pose to global climate change and large-scale seafloor destabilization. This thesis reports fundamental studies on hydrate nucleation, morphology and the evolution of unsaturation during dissociation, followed by additional studies on sampling and pressure core testing.
Hydrate nucleation is favored on mineral surfaces and it is often triggered by mechanical vibration. Continued hydrate crystal growth within sediments is governed by capillary and skeletal forces; hence, the characteristic particle size d10 and the sediment burial depth determine hydrate morphologies in natural sediments. In aged hydrate-bearing sand, Ostwald ripening leads to patchy hydrate formation; the stiffness approaches to the lower bound at low hydrate saturation and the upper bound at high hydrate saturation. Hydrate saturation and pore habit alter the pore size variability and interconnectivity, and change the water retention curve in hydrate-bearing sediments.
The physical properties of hydrate-bearing sediments are determined by the state of stress, porosity, and hydrate saturation. Furthermore, hydrate stability requires sampling, handling, and testing under in situ pressure, temperature, and stress conditions. Therefore, the laboratory characterization of natural hydrate-bearing sediments faces inherent sampling disturbances caused by changes in stress and strain as well as transient pressure and temperature changes that affect hydrate stability. While pressure core technology offers unprecedented opportunities for the study of hydrate-bearing sediments, careful data interpretation must recognize its inherent limitations.
37
Bruce, Elizabeth J. (Elizabeth Jane) 1972. "The characterization of particle clouds using optical imaging techniques." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/58860.
Анотація:
Thesis (M. Eng. in Ocean Engineering)--Joint Program in Marine Environmental Systems (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 1998.Includes bibliographical references (leaves 70-71).
Optical imaging techniques can be used to provide a better understanding of the physical properties of particle clouds. The purpose of this thesis is to design, perform and evaluate a set of experiments using optical imaging techniques to characterize parameters such as shape factor and entrainment coefficient which govern the initial descent phase of particle clouds in water. Several different aspects of optical imaging are considered and evaluated such as the illumination, camera, and data acquisition components. A description of the experimental layout and procedure are presented along with a description of the image processing techniques used to analyze the data collected. Results are presented from a set of experiments conducted with particle sizes ranging from 250 to 980um. A shape factor is used to demonstrate how the cloud's shape changes from approximately spherical to approximately hemispherical over depth. The entrainment coefficient is shown to vary both as a function of depth and particle size diameter. The experimental cloud velocity is compared to the output of a simplified version of the model, STFATE, used to simulate the short term fate of dredged materials in water. This analysis provides a method of evaluating the experimental results and examining the feasibility of using the experimental data to refine the input parameters to the model.
by Elizabeth J. Bruce.
M.Eng.
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Pretorius, Nadine Odette. "Multidimensional analytical techniques for the characterization of aliphatic polyesters." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80127.
Анотація:
Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Complex polymers are defined by their distributive properties with respect to molecular weight, chemical composition, functionality and molecular topology. As a result, polymer properties are very frequently determined not only by one of these entities but by the correlation of two or more distributions. Aliphatic polyesters are industrially implemented in high performance coatings, paints and varnishes. However, it is typically difficult to correlate the resulting properties with the synthesis parameters as these polymers vary in reactivity and application properties. Copolyester synthesis by direct polyesterification is often assumed to produce randomized products due to the mechanisms involved in stepwise polymerization. The formation of cyclic products by intramolecular reactions of hydroxyl (OH) and carboxylic (COOH) functional groups, sidereactions such as transesterification, alcoholysis, and ester-ester interchange allow even further randomization, enabling a highly complex system. Therefore, in addition to molecular weight distribution, polyesters exhibit chemical composition, functionality type as well as branching distributions, classifying them as complex polymeric systems. The different methods of polymer chromatography in combination with sophisticated spectrometry techniques are useful tools for enabling the full description of the molecular heterogeneity of these complex polyesters. The present study entails method development of different modes of chromatography and mass spectrometry along with their combination, to facilitate the analysis of the various distributions of two model polyester systems, phthalic and maleic anhydride, respectively, in combination with propylene glycol. Gradient HPLC analysis enabled an oligomeric separation based on chemical composition of the respective anhydride/propylene glycol samples. Its off-line coupling to MALDITOF MS and ESI-QTOF MS revealed the presence of several distributions of varying endgroup functionality type and molecular weight distributions at different intervals throughout the polymerization. In addition, online gradient HPLC x size exclusion chromatography (2D-LC) was conducted to obtain the dual chemical composition-molecular weight (CCD-MWD) distribution. The combination of the different coupling techniques provided the opportunity to a more in-depth analysis of the structure-property relationships.
AFRIKAANSE OPSOMMING: Komplekse polimere word gedefinieer deur hul verdelings eienskappe ten opsigte van molekulêre massa, chemiese samestelling, funksionaliteit en molekulêre topologie. Gevolglik, word hul eienskappe dikwels bepaal deur nie net een van hierdie entiteite nie, maar ‘n korrelasie van twee of meer verdelings. Alifatiese poliësters word industrieel geϊmplimenteer in hoë werkverrigting bestrykings, verwe en politoere, dog is dit tipies moeilik om die uiteinde eienskappe met die verwante sintese parameters te korrelleer, aangesien die polimere varieer in reaktiviteit en toepassingseienskappe. Ko-poliëster sintese vanaf direkte poliësterivering word dikwels aanvaar om willekeurige produkte op te lewer as gevolg van die meganismes wat betrokke is tydens trapgroei polimerisasie. Die produsering van sikliese produkte weens intra-molekulêre reaksies van hidroksiel(OH) en karboksiel (COOH) verwante funksionele groepe, newereaksies soos transverestering, alkoholise en ester-ester verwisseling, het verdere ewekansigmaking tot gevolg wat ‘n hoog gekomplekseerde sisteem tot gevolg het. Benewens die molekulere massa verdeling, vertoon poliësters dus chemiese samestelling, funksionaliteit tipe so wel as vertakkings verdeling wat hul as komplekse polimeer sisteme klassifiseer. Die verskillende metodes van polimeer chromatografie in kombinasie met gesofistikeerde spektrometriese tegnieke dien as nuttige bronne vir die volledige beskrywing wat betref die molekulêre heterogeniteit van komplekse poliesters. Die huidige studie stel metode ontwikkeling van verskillende modus van chromatografie, massa spektrometrie sowel as hul aaneenvoeging bekend, om die die verskillende verdelings van twee model poliester sisteme, ftaal- en maleϊensuuranhidried onderskeidelik in kombinasie met propileenglikol, suksesvol te analiseer. Gradiënt hoë-druk vloeistof chromatografie (HPLC) analise het ‘n oligomeriese skeiding, gebaseer op die chemiese samestelling van die verskeie anhidried /propileenglikol monsters, opgelewer. Die nie-gekoppelde skakeling met matriks-assisteerdelaser/ desorpsie-ionisasie tyd-van-vlug (MALDI-TOF) en elektron-sproei-ionisasie kwadrupool-tyd-van-vlug (ESI-QTOF) massa spektrometrie het die teenwoordigheid van verskeie verdelings van varieërende endgroep funksionaliteit tipe en molekulêre verdelings by verskillende intervalle tydens die polimerisasie aan die lig gebring. Gekoppelde skakeling van gradient HPLC en grootte uitsluitings chromatografie is ook uitgevoer om die tweedelige chemiese samestelling-molekulere massa verdeling te bepaal. Aaneenvoeging van die verskeie skakelings tegnieke het die geleentheid gebied om ‘n deeglike studie van die struktuureienskappe verhoudinge suksesvol uit te voer.
39
Lin, Lin. "Development of characterization techniques for negative bias temperature instabilities." Thesis, Liverpool John Moores University, 2012. http://researchonline.ljmu.ac.uk/6108/.
Анотація:
The requirements for ever faster circuits and higher packing density have driven the continuous downscaling of the transistor sizes in the last 50 years or so. This leads to higher electrical field and operation temperature and, in turn, accelerates the degradation. One of the most serious reliability issues for the current CMOS technology is the negative bias temperature instability (NETI). This project will focus on investigating the NBTI and the positive charges responsible for it. Modem MOSFETs use gate dielectrics in the nanometer range and the degradation will recover rapidly. To suppress the recovery, high speed characterization technique is needed. In this project the measurement speed has been improved from Sus to 200 ns for Id-Vg measurements and 800ns for C- V measurement. As a Hf-dielectric/SiON stack is replacing SiON as the gate dielectric, the task is to identify which layer of the stack dominates positive charging (PC). A main achievement in this project is the finding that PCs are dominated by the interfacial layer (IL) and they do not pile up at the HfSiON/(IL) interface. Evaluating the conventional threshold voltage shift measured by extrapolating transfer characteristics, Δ Vth( ex), underestimates the NBTI-induced degradation of drain current, Δld. In this project we proposed the effective threshold voltage shift, Δ Veff, in order to evaluate the devices degradation correctly. The next task was to develop a lifetime prediction method, based on ΔVeff. To predict the worst-case lifetime which is recovery free, a model for NBTI kinetics under operation gate bias was developed. This kinetics includes contributions from both as-grown and generated defects and it no longer follows a simple power law. Based on the new kinetics, a single test prediction method was proposed and its safety margin is estimated to be 50%. A fast single pulse charge pumping (SPCP) technique was developed in this project, reducing the measurement time to microseconds. By exploring the differences in the transient currents corresponding to the two edges of the gate pulse, the net charges pumped into devices can be obtained and their saturation level is used to evaluate interface states. For the first time, SPCP allows the recovery of interface states to be monitored with a time resolution in microseconds. The results show that the recovery of stress-induced interface states is substantial within 100μs, which would be missed if conventional charge pumping were used.
40
Voulgaris, Georgios. "Techniques for content-based image characterization in wavelets domain." Thesis, University of South Wales, 2008. https://pure.southwales.ac.uk/en/studentthesis/techniques-for-contentbased-image-characterization-in-wavelets-domain(14c72275-a91e-4ba7-ada8-bdaee55de194).html.
Анотація:
This thesis documents the research which has led to the design of a number of techniques aiming to improve the performance of content-based image retrieval (CBIR) systems in wavelets domain using texture analysis. Attention was drawn on CBIR in transform domain and in particular wavelets because of the excellent characteristics for compression and texture extraction applications and the wide adoption in both the research community and the industry. The issue of performance is addressed in terms of accuracy and speed. The rationale for this research builds upon the conclusion that CBIR has not yet reached a good performance balance of accuracy, efficiency and speed for wide adoption in practical applications. The issue of bridging the sensory gap, which is defined as "[the difference] between the object in the real world and the information in a (computational) description derived from a recording of that scene." has yet to be resolved. Furthermore, speed improvement remains an uncharted territory as is feature extraction directly from the bitstream of compressed images. To address the above requirements the first part of this work introduces three techniques designed to jointly address the issue of accuracy and processing cost of texture characterization in wavelets domain. The second part introduces a new model for mapping the wavelet coefficients of an orthogonal wavelet transformation to a circular locus. The model is applied in order to design a novel rotation-invariant texture descriptor. All of the aforementioned techniques are also designed to bridge the gap between texture-based image retrieval and image compression by using appropriate compatible design parameters. The final part introduces three techniques for improving the speed of a CBIR query through more efficient calculation of the Li-distance, when it is used as an image similarity metric. The contributions conclude with a novel technique which, in conjunction with a widely adopted wavelet-based compression algorithm, extracts texture information directly from the compressed bit-stream for speed and storage requirements savings. The experimental findings indicate that the proposed techniques form a solid groundwork which can be extended to practical applications.
41
Mandadi, Bharath Kumar Reddy. "Advanced Object Characterization and Monitoring Techniques Using Polarimetric Imaging." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1243780947.
42
Chung, Jae-Young. "Broadband Characterization Techniques for RF Materials and Engineered Composites." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269542888.
43
Sawan, Hisham. "Experimental Techniques for Characterization of Carbon Fiber-Reinforced Epoxy." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397743523.
44
Rosa, Nunes Danilo. "Synthesis of organogels and characterization by X-ray techniques." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS006.
Анотація:
Les organogels sont un type particulier de gels formés dans des liquides organiques par un réseau de polymères supramoléculaires. Ces matériaux diffèrent principalement des autres classes de gels en raison de la nature de leur réseau. Les gélifiants de faible poids moléculaire (LMWG) ont tendance à s'auto-agréger dans une direction préférentielle. Cela conduit à la formation de structures allongées, principalement des fibres, qui, par une évolution continue du processus d'assemblage, forment un réseau fibrillaire auto-assemblé enchevêtré (SAFIN). Ce mécanisme d'auto-assemblage est dirigé par des interactions non covalentes telles que la liaison hydrogène, l'empilement π – π, les interactions donneur – accepteur, la coordination des métaux et les interactions de van der Waals. La formation d'un réseau basé uniquement sur des interactions faibles affecte considérablement l'intégrité structurelle, rendant les organogels métastables et thermoréversibles.Il existe une grande variété structurelle d'organogélifiants, ce qui en fait un type de matériau intéressant, permettant une large gamme de propriétés et d'applications. Le principal défi des organogels est de prédire quel gélifiant est capable de gélifier quel liquide. Par conséquent, la découverte de nouveaux organogélateurs se fait encore principalement fortuitement, et leurs capacités de gélification sont généralement vérifiées par des processus exhaustifs d'essais et erreurs. Ainsi, il devient nécessaire de développer une méthodologie capable de réduire le temps et les dépenses nécessaires à la recherche de nouveaux organogélateurs ou du réglage de leurs propriétés.Cette thèse contient deux approches expérimentales principales. La première porte sur la détermination de l’empilement moléculaire d'organogélateurs dans les fibres par des techniques de diffusion de rayons X. La deuxième approche consiste à optimiser une méthodologie basée sur les paramètres de solubilité de Hansen, qui peut être utilisée pour rationaliser la formation d'organogel. La combinaison de ces deux outils a permis d’étudier l’effet qu’une altération structurelle du gélifiant a sur l’organogélation. Cinq familles d'organogélateurs ont été synthétisées avec des chaînes alkyles linéaires de différentes longueurs. À partir de ces cinq familles, nous avons pu déterminer l’assemblage cristallin de trois d’entre elles. Ces familles montrent une évolution régulière de la sphère de gélification qui est cohérente avec l’empilement cristallin. Ainsi, pour cette famille, la prédiction des sphères de gélification est possible. Les deux familles restantes d'organogélateurs ont présenté une évolution irrégulière de la gélification et il n'a pas été possible de déterminer avec précision l’empilement cristallin. Ce comportement est probablement dû à de petites différences du mode de cristallisation des membres de la familleOrganogels are a particular type of gels formed in organic liquids by a supramolecular polymer network. These materials mainly differ from other classes of gels due to the nature of their network. Low molecular weight gelators (LMWG) tend to self-aggregate in a preferential direction. This leads to the formation of elongated structures, mainly fibers, that by continuous evolution of the assembly process form an entangled Self-Assembled Fibrillar Network (SAFIN). This mechanism of self-assembly is led by non-covalent interactions like hydrogen-bonding, π–π stacking, donor–acceptor interactions, metal coordination and van der Waals interactions. Forming a network only based on weak interactions highly affects the structural integrity, making organogels metastable and thermoreversible.There is a wide structural variety of organogelators that makes them such an interesting type of materials, allowing a wide range of properties and applications. The main challenge with organogels is predicting which gelator is capable of gelating which liquid. Therefore, the discovery of new organogelators is still mainly the result of serendipity and their gelation abilities are usually probed by exhaustive trial and error processes. Thus, arises a need to develop a methodology capable to decrease time and expenses when researching new organogelators or tuning their proprieties.This thesis contains two main experimental approaches. The first focuses on the determination of the molecular packing of organogelators within the fibers by scattering techniques. The second approach consists in the optimization of a methodology based on Hansen solubility parameters, that can be used to rationalize organogel formation. The combination of these two tools has allowed to study the effect that a structural alteration of the gelator has on organogelation. Five families of organogelators were synthesized with linear alkyl chains at different lengths. From these five families we could determine the crystal packing for three of them. These families show a regular evolution of the gelation sphere that is coherent with the crystal packing. Thus, for these families the prediction of the gelation spheres is possible. The remaining two families of organogelators presented and erratic evolution of gelation and it was not possible to accurately determinate the crystal packing. This behavior is probably due to small differences in the crystal habit between all members of the family
45
Che, Idris Azam. "Characterization of high speed inlets using global measurement techniques." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/characterization-of-high-speed-inlets-using-global-measurement-techniques(ca8b687b-aff0-4b50-892f-897a962e22ba).html.
Анотація:
After the end of the NASA space shuttle programme, there has been resurgence of interest in developing a single stage-to-orbit spacecraft. The key technology to realize this dream is the airbreathing scramjet engine. The scramjet concept has been around for decades, but much work is still needed in order to eliminate the remaining obstacles to develop a practical working prototype of the engine. Many such obstacles are related to the inlet which functions as the main compression unit for the engine. Typically, a high speed inlet is designed to function properly in a single flight condition. Such an inlet would experience adverse flow conditions related to various shock-shock interactions, viscous effects, shock-boundary layer interactions, and many other flow phenomena at off-design conditions. The traditional mechanism to mitigate the adverse flow conditions is by varying the inlet geometry at off-design conditions. There are still gaps in understanding the behaviour of inlets at off-design conditions and the effectiveness of variable geometry as inlet flow control. This is partly due to complex flow diagnostics setup, which limits the type, quantity and quality of information that can be extracted from the inlet flow. The first objective of this thesis was to develop a global inlet measurement system that can provide an abundance of information on inlet flow. The pressure sensitive paint method was employed together with other methods to provide comprehensive understanding on inlet flow characteristics. Calculation of Mach number at the isolator exit using the isolator sidewall pressure map was successfully demonstrated. The measurement of Mach number at the isolator exit has allowed for performance of the inlet to be calculated without the need for intrusive flow diagnostics tools used by previous researchers. The global measurement system was then employed to investigate the characteristics of the scramjet inlet operating at various off-design conditions. Complex shock structures were observed at the inlet cowl entrance as the angle-of-attack was increased. The relationship of flow quality and inlet performance was examined and discussed. General improvements on the inlet performance were obtained if the size of separation on the compression ramp was reduced. The inlet was also observed to perform poorly when compression shocks impinged on the inner cowl surface. Cowl deflections were demonstrated to be effective in controlling the internal flow of the inlet and improving its performance. An exploratory study on the role of micro-vortex generators to control boundary layer separation on scramjet inlets has been included as well. Strategies for optimizing an inlet at off-design conditions were analysed, and it was found that any variable geometry combination must maintain high throat-to-freestream Mach number ratio in order to preserve high inlet performance.
46
Wilson, Jacob E. "CHARACTERIZATION OF ROTARY BELL ATOMIZERS THROUGH IMAGE ANALYSIS TECHNIQUES." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/115.
Анотація:
Three methods were developed to better understand and characterize the near-field dynamic processes of rotary bell atomization. The methods were developed with the goal of possible integration into industry to identify equipment changes through changes in the primary atomization of the bell. The first technique utilized high-speed imaging to capture qualitative ligament breakup and, in combination with a developed image processing technique and PIV software, was able to gain statistical size and velocity information about both ligaments and droplets in the image data. A second technique, using an Nd:YAG laser with an optical filter, was used to capture size statistics at even higher rotational speeds than the first technique, and was utilized to find differences between serrated and unserrated bell ligament and droplet data. The final technique was incorporating proper orthogonal decomposition (POD) into image data of a side-profile view of a damaged and undamaged bell during operation. This was done to capture differences between the data sets to come up with a characterization for identifying if a bell is damaged or not for future industrial integration.
47
Belluce, Maddalena <1979>. "Development and characterization of micromachined devices for separation techniques." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5843/1/Belluce_Maddalena_tesi.pdf.
Анотація:
Nowadays microfluidic is becoming an important technology in many chemical and biological processes and analysis applications. The potential to replace large-scale conventional laboratory instrumentation with miniaturized and self-contained systems, (called lab-on-a-chip (LOC) or point-of-care-testing (POCT)), offers a variety of advantages such as low reagent consumption, faster analysis speeds, and the capability of operating in a massively parallel scale in order to achieve high-throughput.
Micro-electro-mechanical-systems (MEMS) technologies enable both the fabrication of miniaturized system and the possibility of developing compact and portable systems.
The work described in this dissertation is towards the development of micromachined separation devices for both high-speed gas chromatography (HSGC) and gravitational field-flow fractionation (GrFFF) using MEMS technologies.
Concerning the HSGC, a complete platform of three MEMS-based GC core components (injector, separation column and detector) is designed, fabricated and characterized.
The microinjector consists of a set of pneumatically driven microvalves, based on a polymeric actuating membrane. Experimental results demonstrate that the microinjector is able to guarantee low dead volumes, fast actuation time, a wide operating temperature range and high chemical inertness.
The microcolumn consists of an all-silicon microcolumn having a nearly circular cross-section channel. The extensive characterization has produced separation performances very close to the theoretical ideal expectations.
A thermal conductivity detector (TCD) is chosen as most proper detector to be miniaturized since the volume reduction of the detector chamber results in increased mass and reduced dead volumes. The microTDC shows a good sensitivity and a very wide dynamic range.
Finally a feasibility study for miniaturizing a channel suited for GrFFF is performed. The proposed GrFFF microchannel is at early stage of development, but represents a first step for the realization of a highly portable and potentially low-cost POCT device for biomedical applications.
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Belluce, Maddalena <1979>. "Development and characterization of micromachined devices for separation techniques." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5843/.
Анотація:
Nowadays microfluidic is becoming an important technology in many chemical and biological processes and analysis applications. The potential to replace large-scale conventional laboratory instrumentation with miniaturized and self-contained systems, (called lab-on-a-chip (LOC) or point-of-care-testing (POCT)), offers a variety of advantages such as low reagent consumption, faster analysis speeds, and the capability of operating in a massively parallel scale in order to achieve high-throughput.
Micro-electro-mechanical-systems (MEMS) technologies enable both the fabrication of miniaturized system and the possibility of developing compact and portable systems.
The work described in this dissertation is towards the development of micromachined separation devices for both high-speed gas chromatography (HSGC) and gravitational field-flow fractionation (GrFFF) using MEMS technologies.
Concerning the HSGC, a complete platform of three MEMS-based GC core components (injector, separation column and detector) is designed, fabricated and characterized.
The microinjector consists of a set of pneumatically driven microvalves, based on a polymeric actuating membrane. Experimental results demonstrate that the microinjector is able to guarantee low dead volumes, fast actuation time, a wide operating temperature range and high chemical inertness.
The microcolumn consists of an all-silicon microcolumn having a nearly circular cross-section channel. The extensive characterization has produced separation performances very close to the theoretical ideal expectations.
A thermal conductivity detector (TCD) is chosen as most proper detector to be miniaturized since the volume reduction of the detector chamber results in increased mass and reduced dead volumes. The microTDC shows a good sensitivity and a very wide dynamic range.
Finally a feasibility study for miniaturizing a channel suited for GrFFF is performed. The proposed GrFFF microchannel is at early stage of development, but represents a first step for the realization of a highly portable and potentially low-cost POCT device for biomedical applications.
49
Rossi, Matteo. "Non invasive hydrogeophysical techniques for vadose zone hydrological characterization." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427485.
Анотація:
Hydrogeophysics is a discipline that emerged and had a great development in the last two decades. The aim of this discipline is the subsurface hydrological and hydrogeological characterization via non-invasive geophysical techniques. Conventional sampling techniques, for characterizing or monitoring the shallow subsurface, are typically sparsely distributed or acquired at an inappropriate scale. Non-invasive geophysical datasets can provide more dense 2D/3D information. The present work focused on the hydrological characterization of the vadose zone, as it is a challenging issue that may be more deeply and extended understood.
The dependence of the geophysical response on changes in soil moisture content, e.g. via changes in electrical resistivity or dielectric properties, is the key mechanism that permits the use of non-invasive techniques to monitor the vadose zone in time-lapse mode, i.e. via repeated measurements over time. The use of these techniques in different configurations in the shallow and deep vadose zones can provide high-resolution images of hydrogeological structures and a detailed assessment of dynamic processes in the subsurface environment. The data from non-invasive techniques can subsequently be used to calibrate physical-mathematical models of water flow in the unsaturated zone. The understanding of fluid-dynamics is the key to all hydrologically-controlled environmental problems. The hydrogeophysical approach is based on links that can be established between geophysical quantities and hydrological variables, such as water content and solute concentration, generally in the form of empirical or semi-empirical petrophysical relationships.
The classical hydrogeophysical approach in hydraulic parameters evaluation starts from the measured geophysical data to estimate the hydrological state, albeit careful is need at this step: essential is the knowledge achievable from field data and the relative accuracy in the physical translation. Anyway this is the starting point for the hydrological simulation. Subsequently the hydrological modelled parameters may be compared and evaluated with the hydrological quantities obtained from geophysics through the petrophysical relationships. This approach can lead to erroneous parameter inference, if the spatial resolution of the geophysical techniques is not taking into account.
A different approach can be proceed, to overcome this issue. In spite of translating geophysical parameters in hydrological quantities, the comparison may be done directly on the not-inverted geophysical data. The geophysical surveys can be simulated with a forward model, starting from the hydrological modelled properties distribution and applying the petrophysical relationship to reconstruct the geophysical spatially-distributed parameters. At this point geophysical measured and simulated data can be compared, with the aim of calibrate and validate the hydrological model under examination. This second approach, not requiring geophysical inversions, is able to overcome artefacts deriving from the inversion procedure; but the resolution of the surveys must be considered, because an hydrological state should not be reproduced from geophysical methodologies, even if the two datasets, both simulated and measured, are in a perfect fitting.
The work is divided in two complementary parts. The first part is centred on the hydrological quasi-steady state characterization from cross-hole radar measurements. In many studies cross-borehole zero offset profiles (ZOP) are used to infer subsoil moisture content, which are a key topic in hydrological modelling and consequently in hydraulic parameters estimation. The principal aim of this work is to have a more complete view of how boreholes GPR ZOP measurements are informative of the subsoil geometry and distribution of relative permittivity. This is essential in moisture content estimation, uncertainty quantification and in the initial setting of parameters necessary for starting an hydrological model. For this purpose three different ZOP datasets are analysed: a synthetic dataset and two field-measured datasets.
The second part of the work is the hydrogeophysical inversion of a tracer test in the vadose zone, conducted at the Hatfield site (near Doncaster, UK). The path of a tracer in vadose zone may be masked from the variations of the physical status surrounding the dispersive plume; this could lead to erroneous interpretations of the evolving plume. The load of the new water, that moves under gravitational forces, produces the raising of the degree of saturation in the media just below the plume. This incidental effect could significantly contribute to geophysical signals and hydrological characterizations. The aim of this study is the recognition and distinction of the paths of the new injected fluid from the groundwater, already present in the system and activated from pressure variations, in a sort of “piston” effect. The discrimination between the new percolating water and the old pushed-down water is a key issue in aquifer vulnerability and soil pollution migrations, which can affect the vadose zone. In this second part the hydrogeophysical inversion is conducted: the simulated hydrological quantities are used to obtain a geophysical forward model of ZOP surveys, that should be compared with measured ZOP soundings. An estimation of the goodness of the hydrological model is then possible. A particle tracking code is then run to detect the exact evolution of the tracer plume in the subsurface. A comparison with the results from the inverted geophysical datasets is able to discriminate the tracer fluid from the old water of the system and to individuate where the geophysical imaging could be deceptive and misleading.
The present work is an example of the hydrogeophysical inversion methods, where great emphasis is focused on the characterization of the hydraulic state preceding the tracer injection test. Anyway the system must be stressed under artificial hydraulic states to force the parameters estimation and to limit the range of probable hydrological models.L’idrogeofisica è una disciplina che è emersa ed ha avuto un importante sviluppo nelle ultime due decadi. Lo scopo di questa disciplina è la caratterizzazione idrologica ed idrogeologica del sottosuolo attraverso tecniche geofisiche non invasive. Le tecniche di campionamento convenzionali sono di norma spazialmente distribuite ed acquisite ad una scala impropria. Le tecniche geofisiche invece permettono indagini spazialmente più fitte in 2D o 3D. Il presente lavoro si focalizza sulla caratterizzazione idrologica della zona vadosa. I dati ottenuti dalle tecniche geofisiche possono essere utilizzati per calibrare modelli fisico matematici del flusso nella zona del non-saturo. Tale approccio idrogeofisico è basato su relazioni petrofisiche che legano le quantità geofisiche con le variabili idrologiche. Il classico approccio idrogeofisico parte dalle misure geofisiche per ottenere una stima di parametri idrologici, che a loro volta vengono impiegati in modelli idraulici in grado di fornire ulteriori proprietà del sistema idraulico del sottosuolo. I modelli idrologici vengono successivamente validati e calibrati con i risultati delle inversioni geofisiche in time-lapse. Questo approccio prevede l’inversione del dato geofisico, metodo che può portare ad immagini del sottosuolo che contengono artefatti e che non tengono conto della risoluzione della tecnica applicata. Un approccio differente prevede che ai parametri stimati dai modelli idraulici siano applicate le relazioni petrofisiche, al fine di tradurre le quantità idrologiche in quantità geofisiche. A questo punto la simulazione di modelli geofisici diretti permette un confronto immediato con i dati misurati, senza l’ausilio dell’inversione geofisica. Il presente lavoro è suddiviso in due parti. La prima parte è centrata sulla caratterizzazione idrologica dello stato stazionario iniziale attraverso misure radar (GPR). Lo scopo principale del lavoro è quello di quantificare quanto le misure GPR a zero offset profiling (ZOP) siano informative delle geometrie del sottosuolo e delle relative condizioni di contenuto idraulico dei materiali. Questo lavoro è essenziale per ottenere una stima del contenuto idrico del sottosuolo e della relativa incertezza che ne deriva, poiché tali stime sono il punto di partenza delle simulazioni idrauliche. La seconda parte del lavoro è focalizzata sulla inversione idrogeofisica di un test con tracciante salino condotto ad Hatfield (UK). L’approccio idrogeofisico adottato è quello di simulare misure geofisiche direttamente dalla distribuzione dei parametri idrologici calcolati, per ottenere una calibrazione di quelle quantità idrologiche scopo della metodologia applicata. La ricostruzione dell’evoluzione di un plume iniettato nella zona vadosa è interessante ai fini di identificare i possibili percorsi di un contaminante nel sottosuolo. A tale scopo un codice di particle tracking è stato applicato ai risultati dell’inversione idrologica. Il codice di partcle tracking è in grado di distinguere i percorsi dell’acqua iniettata dall’acqua già presente nel sistema e movimentata del cambiamento di pressione in atto, ‘effetto pistone’. Le inversioni delle misure geofisiche non permettono di distinguere il fluido tracciante dai cambiamenti del contenuto idrico dei materiali adiacenti al plume iniettato.
50
Fernández, de Labastida Ventura Marc. "Development of novel techniques of advanced transport characterization of membranes." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669832.
Анотація:
Optimization of membrane separation processes rely on the accurate determination of some parameters related to membrane structure, chemistry, morphology or transport mechanism. Therefore, membrane characterization is fundamental in membrane research and development. This thesis addresses two specific issues of membrane separation processes: the distribution of extent of concentration polarization (CP) over the membrane surface in test cells for pressure-driven membrane processes and the separate information of equilibrium (partitioning) and kinetic (diffusivity) properties of ion-exchange membranes for a better-understanding of ion-transport mechanisms. The implications of CP inhomogeneity for the interpretation of measurements of solute rejection were qualitatively illustrated using a simple model of locally-1D CP combined with a postulated probability distribution of unstirred-layer thickness over the membrane thickness. Disregarding the CP distribution under-estimates the CP of strongly positively-rejected solutes and over-estimates the CP for the negatively-rejected ones. This is especially important in nanofiltration where strong positive and pronounced negative rejections can occur simultaneously for solutes of different charges. Therefore, it is desirable to reduce the inhomogeneity of CP distribution to a minimum in membrane-testing devices. A novel test cell design was developed based on the classical configuration of rotating disk combined with the possibility of setting an operating pressure up to 20 bar. CFD simulations showed that CP was homogeneous over the major part of the membrane surface whereas there were some expectable deviations close to the membrane edge. The approach was also validated experimentally via studying the dependence of observed rejection on the rotation speed and demonstrating that intrinsic rejection was practically independent of it. Then, the cell utility was proved performing different ion rejection studies for several dominant salts (NaCl, MgCl2, Na2SO4 and MgSO4) plus trace ions (Na+, NH4+, Cl- and NO3-) and for electrolyte mixtures of NaCl and MgCl2. The solution-diffusion-electro-migration model was used to obtain ionic membrane permeances from the experimental data. Besides, experiments performed with a cross-flow test cell demonstrated that there was filtration along the membrane porous support even if the membrane is supported by an impermeable surface. This occurs in the peripheral parts of the membrane due to membrane sealing and contribute to CP inhomogeneity. Finally, a novel method based on non-stationary-diffusion of relatively small concentration differences was developed to determine salt diffusion and partitioning coefficients in addition to the ion perm-selectivity, which is the only parameter available from the conventional measurements of stationary membrane potential. An ion-exchange membrane supported by a relatively thick coarse-porous support (glass frit) is placed in a two-compartment stirred cell. The salt concentration in one compartment is kept stationary during the measurement whereas in the other compartment, the initial solution is rapidly replaced by a solution of different concentration. Thus, there is a time-dependent electrical response due to a progressive redistribution of applied concentration difference between the membrane and the porous support and the different ion perm-selectivities of those media. Experimental data was fitted to a mathematical model that describes transient transport phenomena including osmosis, which was found to contribute notably on the measurements. The osmotic permeability was determined in separate measurements. The rate of signal relaxation is primarily controlled by the diffusion permeability of the membrane but is also affected by the salt partitioning. The results were validated by comparison with the literature data and using conventional techniques. Systematic studies were also carried out under different conditionsL'optimització dels processos de separació amb membranes depèn d'una combinació de factors relacionats amb les propietats fisicoquímiques, l'estructura o la morfologia. Per tant, una caracterització acurada és fonamental en la investigació i desenvolupament de membranes. Aquesta tesi aborda dos problemes específics dels processos de separació amb membranes: la distribució de l'abast de la polarització per concentració (PC) sobre la superfície de la membrana als mòduls de membrana on la força impulsora és la pressió i l'obtenció d'informació diferenciada de les propietats cinètiques i d'equilibri en membranes de bescanvi iònic per a una millor comprensió dels mecanismes de transport d'ions. Les conseqüències de la inhomogeneïtat de la PC a l'hora d'interpretar les mesures del rebuig del solut es van il·lustrar qualitativament mitjançant un senzill model que descriu la PC localment en 1D combinat amb una distribució de probabilitats pel gruix de la capa límit. Ignorar la distribució a la PC subestima la PC dels soluts rebutjats positivament i sobreestima la PC per als rebutjats negativament. Aquest fet és especialment important en la nanofiltració, on es poden produir simultàniament rebuigs positius i negatius pronunciats per a soluts de diferents càrregues. Per tant, és desitjable reduir al màxim la inhomogeneïtat de la distribució de la PC als mòduls de membrana. Es va desenvolupar un nou disseny de mòdul per membranes basat en la clàssica configuració de disc rotatiu. Simulacions de dinàmics de fluids van demostrar que la PC es homogènia a la major part de la superfície de la membrana mentre que es van obtenir algunes desviacions esperables a prop de la vora de la membrana. A més, es va validar experimentalment estudiant la dependència del rebuig observat amb la velocitat de rotació i demostrant que el rebuig intrínsec es pràcticament independent. Posteriorment, es van obtenir les permeances iòniques mitjançant el model "Solution-diffusion-electro-migration" realitzant diferents estudis amb salts dominants (NaCl, MgCl2, Na2SO4 i MgSO4) més ions traça (Na+, NH4+, Cl- i NO3-) i amb mescles binàries de NaCl i MgCl2. D'altra banda, alguns experiments amb una cel·la de flux tangencial van demostrar que hi ha una filtració al llarg del suport porós de la membrana, fins i tot si aquesta esta recolzada per una superfície impermeable. Això es produeix a les zones perifèriques de la membrana, a causa de la pressurització del mòdul i contribueix a la inhomogeneïtat de la PC. Finalment, es va desenvolupar un nou mètode basat en la difusió no estacionària en condicions de diferències de concentració relativament petites per determinar la difusió i els coeficients de partició, a més de la permselectivitat iònica, que és l'únic paràmetre disponible a partir de les mesures convencionals del potencial de membrana en estat estacionari. Una membrana de bescanvi iònic recolzada per un suport relativament gruixut i porós es col·loca en una cel·la agitada de dos compartiments. La concentració de sal en un compartiment es manté estacionària durant l'experiment mentre que a l'altre compartiment, la solució inicial és substitueix ràpidament per una solució de concentració diferent. Així, hi ha una resposta elèctrica depenent de temps a causa d'una redistribució progressiva de la diferència de concentració aplicada entre la membrana i el suport porós degut a les diferents selectivitats iòniques entre ambdós medis. Les dades experimentals es van ajustar a un model matemàtic que descriu els fenòmens de transport en estat transitori, incloent la osmosis, ja que es va observar que contribueix significativament en les mesures. La permeabilitat osmòtica es va determinar paral·lelament. La velocitat de relaxació de la senyal obtinguda està controlada principalment per la difusió de la membrana, tot i que també es veu afectada pel coeficient de partició