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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

"Expanded" local mode approach and isotopic effect in polyatomic molecules / Approche du mode local "étendu" et effet isotopique dans des molécules polyatomiques

Fomchenko, Anna 18 September 2014 (has links)
Dans cette thèse, sur la base de l'approche du mode local "étendu" et de la théorie générale de la substitution isotopique, nous obtenons un ensemble de relations analytiques simples entre les paramètres spectrocopiques (fréquences harmoniques, coefficients d'anharmonicité, paramètres rovibrationels, différents types de paramètres d'interaction de Fermi et de Coriolis) des molécules de CH2D2, CH3D et CHD3. Tous ces paramètres sont exprimés en termes de relations simples à partir des paramètres spectroscopiques de la molécule mère CH4. Des calculs tests avec des relations isotopiques montrent que même sans introduire d'informations majeures sur les espèces isotopiques, les résultats numériques de ces calculs sont en bon accord avec les données expérimentales et les calculs ab initio. A partir de le théorie des opérateurs de perturbation et des propriétés de symétrie des molécules axiales XYZ3 (C3v), nous déterminons des formules générales permettant la détermination des paramètres spectroscopiques sous la forme de fonctions des paramètres structuraux et des paramètres de la fonction potentiel intramoléculaire. Nous présentons aussi une approche permettant la détermination du hamiltonien de molécules polyatomiques qui permet de résoudre le problème de la description de la surface d'énergie potentielle via la construction et la diagonalisation d'une matrice hamiltonienne de grande dimension. / In this thesis, on the base of the "expanded", local mode approach and general isotopic substitution theory we obtain sets of simple analytical relations between spectroscopic parameters (harmonic frequencies, anharmonic coefficients, ro-vibrational parameters, different kinds of Fermi and Coriolis-type interaction parameters) of the CH2D2, CH3D and CHD3 molecules. All of them are expressed as simple functions of spectroscopic parameters of the mother CH4 molecule. Test calculations with the isotopic relations show that even without including prior informations about the isotopic species, numerical results of calculations are in a good agreement both with experimental data and results of ab initio calculations. On the base of operators perturbation theory and the symmetry properties of the axially symmetric XYZ3 (C3v) type molecules, we derive general formulae for the determination of the spectroscopic parameters in the form of functions of structural parameters and parameters of the intramolecular potential function. We present also an approach for determination of the Hamiltonian of polyatomic molecules that allows to solve the problem of potential energy surface determination via the construction and the diagonalization of a Hamiltonian matrix of large dimension.
492

Algebraic methods for constructing blur-invariant operators and their applications

Pedone, M. (Matteo) 09 August 2015 (has links)
Abstract Image acquisition devices are always subject to physical limitations that often manifest as distortions in the appearance of the captured image. The most common types of distortions can be divided into two categories: geometric and radiometric distortions. Examples of the latter ones are: changes in brightness, contrast, or illumination, sensor noise and blur. Since image blur can have many different causes, it is usually not convenient and also computationally expensive to develop ad hoc algorithms to correct each specific type of blur. Instead, it is often possible to extract a blur-invariant representation of the image, and utilize such information to make algorithms that are insensitive to blur. The work presented here mainly focuses on developing techniques for the extraction and the application of blur-invariant operators. This thesis contains several contributions. First, we propose a generalized framework based on group theory to constructively generate complete blur-invariants. We construct novel operators that are invariant to a large family of blurs occurring in real scenarios: namely, those blurs that can be modeled by a convolution with a point-spread function having rotational symmetry, or combined rotational and axial symmetry. A second important contribution is represented by the utilization of such operators to develop an algorithm for blur-invariant translational image registration. This algorithm is experimentally demonstrated to be more robust than other state-of-the-art registration techniques. The blur-invariant registration algorithm is then used as pre-processing steps to several restoration methods based on image fusion, like depth-of-field extension, and multi-channel blind deconvolution. All the described techniques are then re-interpreted as a particular instance of Wiener deconvolution filtering. Thus, the third main contribution is the generalization of the blur-invariants and the registration techniques to color images, by using respectively a representation of color images based on quaternions, and the quaternion Wiener filter. This leads to the development of a blur-and-noise-robust registration algorithm for color images. We observe experimentally a significant increase in performance in both color texture recognition, and in blurred color image registration. / Tiivistelmä Kuvauslaitteet ovat aina fyysisten olosuhteiden rajoittamia, mikä usein ilmenee tallennetun kuvan ilmiasun vääristyminä. Yleisimmät vääristymätyypit voidaan jakaa kahteen kategoriaan: geometrisiin ja radiometrisiin distortioihin. Jälkimmäisestä esimerkkejä ovat kirkkauden, kontrastin ja valon laadun muutokset sekä sensorin kohina ja kuvan sumeus. Koska kuvan sumeus voi johtua monista tekijöistä, yleensä ei ole tarkoitukseen sopivaa eikä laskennallisesti kannattavaa kehittää ad hoc algoritmeja erityyppisten sumeuksien korjaamiseen. Sitä vastoin on mahdollista erottaa kuvasta sumeuden invariantin edustuma ja käyttää tätä tietoa sumeudelle epäherkkien algoritmien tuottamiseen. Tässä väitöskirjassa keskitytään esittämään, millaisia eri tekniikoita voidaan käyttää sumeuden invarianttien operaattoreiden muodostamiseen ja sovellusten kehittämiseen. Tämä opinnäyte sisältää useammanlaista tieteellistä vaikuttavuutta. Ensiksi, väitöskirjassa esitellään ryhmäteoriaan perustuva yleinen viitekehys, jolla voidaan generoida sumeuden invariantteja. Konstruoimme uudentyyppisiä operaattoreita, jotka ovat monenlaiselle kuvaustilanteessa ilmenevälle sumeudelle invariantteja. Kyseessä ovat ne rotationaalisesti (ja/tai aksiaalisesti) symmetrisen sumeuden lajit, jotka voidaan mallintaa pistelähteen hajaantumisen funktion (PSF) konvoluutiolla. Toinen tämän väitöskirjan tärkeä tutkimuksellinen anti on esitettyjen sumeuden invarianttien operaattoreiden hyödyntäminen algoritmin kehittelyssä, joka on käytössä translatorisen kuvan rekisteröinnissä. Tällainen algoritmi on tässä tutkimuksessa osoitettu kokeellisesti johtavia kuvien rekisteröintitekniikoita robustimmaksi. Sumeuden invariantin rekisteröinnin algoritmia on käytetty esiprosessointina tässä tutkimuksessa useissa kuvien restaurointimenetelmissä, jotka perustuvat kuvan fuusioon, kuten syväterävyysaluelaajennus ja monikanavainen dekonvoluutio. Kaikki kuvatut tekniikat ovat lopulta uudelleen tulkittu erityistapauksena Wienerin dekonvoluution suodattimesta. Näin ollen tutkimuksen kolmas saavutus on sumeuden invarianttien ja rekisteröintiteknikoiden yleistäminen värikuviin käyttämällä värikuvien kvaternion edustumaa sekä Wienerin kvaternion suodatinta. Havaitsemme kokeellisesti merkittävän parannuksen sekä väritekstuurin tunnistuksessa että sumean kuvan rekisteröinnissä.
493

Rotational Spectra Of Weakly Bound H2S Complexes And 'Hydrogen Bond Radius'

Mandal, Pankaj Kanti 04 1900 (has links) (PDF)
No description available.
494

Method development for rheological characterization of microfibrillated cellulose / Utveckling av en metod för reologisk karakterisering av mikrofibrillerad cellulosa

Wahlkrantz, Elin January 2020 (has links)
This thesis contributes to a development of a method for rheological characterization of microfibrillated cellulose. The intended use of the method is to be able to distinguish between different grades of microfibrillated cellulose. The method that was developed had preparation procedure of suspensions, pH, dry content and conductivity as well as measuring geometry and measuring sequence in mind. The method resulted in using a propeller mixer for sample preparation and the most suitable properties of the samples for comparison of different qualities of microfibrillated cellulose was evaluated to be pH 8 with a dry content of 2.0 wt% and a conductivity of 110 µS/cm. The rheology of the microfibrillated cellulose suspensions was examined by using a dynamic rotational rheometer and a splined bob and cup (C25G/PC25G). The complex viscosity from amplitude sweeps is used as the parameter to distinguish between different grades of 2 wt% microfibrillated cellulose suspensions. At 1.0 wt% the pH of the suspensions appeared to have a very small impact on the results from rheological measurements while an increased conductivity of the suspensions resulted in an increased complex viscosity. The dry content dependency appeared to be exponential in the range of 0.5 to 3.0 wt% and it was thus easier to distinguish between different grades of microfibrillated cellulose when the dry content is 2.0 wt% compared to 1.0 or 1.5 wt%.
495

Vliv etherů celulózy na reologické vlastnosti vápna / Influence of cellulose ethers on rheological properties of lime

Hegrová, Michaela January 2018 (has links)
The subject of this diploma thesis is a study of the influence of cellulose ethers on the rheological properties of lime. The theoretical part focuses on rheological parameters, techniques and test equipment used in rheology measurements. Various types of cellulose ethers and their influence on the rheological properties of fresh mortars are described. The practical part deals with the study of the influence of different types and quantities of cellulose ethers on the properties of fresh lime pastes and mortars. The results were obtained from measurements on a rotational rheometer with a special geometry for building materials. Measuring methods used were flow and oscillatory tests. Yield stress, viscosity and flow index were determined by the flow measurement. The stability and stiffness of fresh materials were determined during the oscillation measurements. The measured results are then evaluated and compared.
496

Diagnostika plazmatu výboje ve vodných roztocích a jeho aplikace / Diagnostics of plasma generated in water solutions and its application

Holíková, Lenka January 2011 (has links)
This thesis deals with the study of parameters of diaphragm discharge in liquids. NaCl solution of different conductivity was used as a conductive medium. Conductivities were adjusted in the range from 220 to 1000 µS cm-1. Two diagnostic methods were used for the study of plasma parameters. The first one was employed in the laboratory of plasma chemistry at Faculty of Chemistry, Brno University of Technology, namely the optical emission spectroscopy. The second method used for plasma diagnostics was the time resolved ICCD camera at the Laboratoire de Physique des Plasmas at the École Polytechnique in Paris. The reactor for the diagnostics by optical emission spectroscopy had the volume of 4 l, and it was made of polycarbonate. PET diaphragm was placed in the barrier separating the cathode and the anode space. Electrodes were made of titanium coated with platinum. Electric power source supplied a constant DC voltage of maximum 5 kV and electric current up to 300 mA. Spectrometer Jobin Yvon TRIAX 550 with CCD detector was used during the experiments in order to measure overview spectra within the range from 200 to 900 nm as well as OH molecular spectra and Hß line spectra. All spectra were scanned in both discharge polarities, i.e. at the cathode and the anode part of reactor. The basic parameters of the discharge plasma were calculated from the spectra, that means rotational and electron temperature and electron density. Another part of experiment consisted of measurements by the ICCD camera iStar 734. Two types of reactors were used. The first one was the same as the reactor for the measurements by the optical emission spectroscopy. The second one was also made of polycarbonate, but the volume of conductive solution was 110 ml, only. HV electrodes made of stainless steel were placed in this reactor. Ceramic diaphragm (Shapal-MTM) was used in both reactors. Diaphragms had different thickness and diameter of holes. ICCD camera acquired photographs with details of processes of the bubbles generation and discharge operation (propagation of plasma channels), depending on solution conductivity, dimensions of the diaphragm, and with respect to the electrode part of the reactor.
497

Modelování tlumících zařízení v interakci s konstrukcí / Modelling of damping devices in interaction with a structure

Kalina, Martin January 2013 (has links)
The aim of my master’s thesis was to create models of the damping device and observing their behavior in interaction with the structure. First was the construction separately modeled with Java application named FyDiK2D like a model with one degree of freedom. Model of construction takes form like a high, thin rod with full circular cross section. The lower part was restrained into the subsoil. The design was to verify the correct functionality of the model by comparing the analytical and numerical solutions. For capturing the precise behavior of the structure was converted to a multi-stage model. Then the pendulum damper was applied on this construction and found amplitude lies in highest point of multi-stage model. He was then replaced by tuned mass damper. By comparing these amplitudes from both dampers was found which kind of damper is efficient for multi-stage model.
498

Vytvoření databáze tuhosti statorových svazků elektrických strojů točivých / Creation of database of stator core stiffness of rotational electrical machines

Podzemný, Zdeněk January 2013 (has links)
In this thesis is wrote up a complete procedure of stator core stiffness determination using finite element method (FEM), subsequently, the stator core stiffness database was created according to this procedure. In the next chapter is carried out a sensitivity analysis of one chosen stator core, which led to identifying parameters that affected its stiffness the most. Finally, a modal analysis of one synchronous machine was performed using FEM, in order to determine the effect of stator core stiffness on modal characteristics of the machine. Several modal shapes and corresponding natural frequencies were computed in this analysis, then only a few shapes with the highest core effect were chosen and compared.
499

Návrh vestavěného systému pro řízení výukového modelu rotačního kyvadla / Design of embedded system for control of educational model of rotary pendulum

Jajtner, Jan January 2015 (has links)
The basic aim of this work is to improve existing model of rotational inverted pendulum by adding new mechanical features, implement the control algorithm to dsPIC microcontroller and develop related control electronics thus extending the functionality of current model while making it more compact. The work contains derivation of dynamic equations both by means of analytical methods and multi-body formalism of SimMechanics. These are used to design a state controller stabilizing the pendulum in inverse position. In addition, parameters of the system are being estimated experimentally. Swing-up controller is developed to drive the pendulum to unstable position. Various state estimators are added to controller to improve the control process while comparing their overall performance. The last point is devoted to development of superior state-automaton designed to switch between different regulating modes including fail-detection algorithms providing smooth operation of the model.
500

Výroba olejové vany / The Production of the oil pan

Šupa, Jan January 2016 (has links)
The dissertation deals with a suggestion of the production of an oil pan into the car with a deep drawing. The part will be produced out of a deep drawed steel plate – class 11 305 (DC04). On the basis of a calculation and the study of the corresponding literature about the deep drawing a reverse drawing in a convention tools with a blank holder has been suggested. The part of the machine will be also an upper ejector for the fall of a sticking of a drawn part in the die. As a semi-product a blank has been chosen, which is burned out from the piece of plate with the dimension of 2500 x 12500 mm and thickness 1 mm with the help of the laser. The production quantity is 30 000 per one year. As a forming machine a universal hydraulic presser CTH 250 from the Czech company Žďas a.s. with the nominal power 2500 kN has been chosen.

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