Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 135-137).

Thesis (M.S.)--Rochester Institute of Technology, 1995. / Typescript. Bibliography: leaf 54.

th. 3e cycle--Math. pures--Grenoble 1, 1983. N°: 117.

Submitted in fulfillment of the academic requirements for the degree of Master of Engineering in Engineering, Durban University of Technology, Durban, South Africa, 2018. / Many separation processes in the chemical and petrochemical industries are energy intensive, and unfortunately, involve a range of solvents that are environmentally harmful and destructive. Alternative, sustainable separation techniques are desired to replace these conventional methods used in the separation of azeotropic as well as close-boiling mixtures, with the intention of reducing energy costs and adverse impact on the environment. In the present study, a new class of solvents called deep eutectic solvents (DESs) of Type III were investigated as alternatives to conventional solvents currently employed in separation processes. DESs are classified as ‘green’ solvents because of a range of favourable properties including lower cost, desirable solubility properties and reduced environmental impact (Abbott et al., 2003b; Smith et al., 2014). The infinite dilution activity coefficients (IDACs) values of 24 solutes – including alk-1-anes, alk-1-enes, alk-1-ynes, cycloalkanes, alkanols, alkylbenzenes, heterocyclics, esters, and ketones – were measured at 313.15, 323.15, 333.15 and 343.15 K by gas-liquid chromatography (GLC) in DESs. The four investigated DESs were as follows: 1) Tetramethylammonium chloride + Glycerol (DES1); 2) Tetramethylammonium chloride + Ethylene Glycerol (DES2); 3) Tetramethylammonium chloride + 1,6 Hexanediol (DES3); and 4) Tetrapropylammonium bromide + 1,6 Hexanediol (DES4). This work focused on the performance of DESs as extractive solvents for selected azeotropic and close-boiling binary mixtures. The two key performance criteria for these extractive solvents – selectivity and capacity – were determined from experimental infinite dilution activity coefficients (IDACs) of various solutes. The effect of solute molecular structure on IDAC values was investigated. Moreover, the effect of varying the hydrogen bond donors (HBDs) in DESs on IDAC values was examined. Partial excess molar enthalpies at infinite dilution were determined from the experimental IDAC data. Moreover, common industrial separation problems were selected to investigate DES potential to separate various mixtures by determining selectivity and capacity at infinite dilution. The results obtained in this study indicate that the use of a long carbon chain HBDs greatly decreases miscibility of DESs with organic solutes. For systems such as n-heptane - toluene, acetone - ethanol, cyclohexane - benzene and n-hexane - benzene systems, DES4 was the best solvent regarding the separation performance index. However, further investigation for DES4 by measurements of vapour-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) data is suggested, as these data would provide additional pertinent information regarding the separation of such mixtures using DES4. The data produced from this study can be used to extend the applicability range of predictive models such as Universal Quasi- Chemical Functional Group Activity Coefficients (UNIFAC) and modified UNIFAC (Do) which are already incorporated in some chemical engineering process simulators. / M

No description available.

The nature of diffusion along thin evaporated films has been studied by optical and transmission electron microscopy. The thicknesses of the films were measured by multiple-beam interferometry. A preliminary survey of some 22 binary metal systems showed that only four - Ag-Se, Cu-Se, Cu-Te, and Ag-Te - diffused measurably at room temperature. In these four systems it was found possible to study only the diffusion of Cu or Ag into Se and Te; the reverse diffusion experiments failed, presumably because of extensive Kirkendall porosity which developed on the Se or Te side of the diffusion couples, impeding the motion of these atoms. The room temperature growth rates in each system were observed to be higher when the structure of the Se or Te consisted of isolated islands with a highly disordered inter-island network. This effect was attributed to a short circuit diffusion process analogous to grain boundary diffusion which took place in the inter-island channels. The effect was more pronounced in Cu-Te and Ag-Te where electron microscopy observations of the phase boundary interfaces showed a marked tendency for grain boundary diffusion to occur at all Se and Te thicknesses. For continuous films of Se and Te, the growth rates were found to be independent of the absolute thickness. Because of the evaporation geometry used in depositing the couples, there was a critical thickness ratio of Ag or Cu to Se or Te that had to be exceeded in order for diffusion to proceed. Theoretical treatment of the problem, based on the stoichiometry of the phases formed during diffusion, gave predictions of the critical ratio that were generally in good agreement with the experimental values obtained. In each system the critical ratio was found to be independent of the absolute Se or Te thickness. It was also possible to predict the composition of the phase formed during diffusion using the critical ratio. In every system but Cu-Te, the composition determined in this way was in agreement with that given by electron diffraction analysis of the diffusion zone. The activation energies for diffusion in Ag-Se, Cu-Te, and Ag-Te were fairly low suggesting that short circuit diffusion was the predominant mechanism in these systems. The activation energy in Cu-Se was quite large (23 kcal/mole), and it appears that the diffusion mechanism in this case is not consistent with that in the other systems. An interesting observation made during electron microscopy studies in Cu-Se was the formation of a second phase when high electron beam intensities were used. This phase (Cu₃Se₂), not observed in normal diffusion experiments up to 5 0°C, grew dendritically in the presence of the electron beam. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

Nowadays, still images are used everywhere in the digital world. The shortages of storage capacity and transmission bandwidth make efficient compression solutions essential. A revolutionary mathematics tool, wavelet transform, has already shown its power in image processing. Minimage, the major topic of this paper, is an application that compresses still images by wavelets. Minimage is used to compress grayscale images and true color images. It implements the wavelet transform to code standard BMP image files to LET wavelet image files, which is defined in Minimage. The code is written in C++ on the Microsoft Windows NT platform. This paper illustrates the design and implementation details in MinImage according to the image compression stages. First, the preprocessor generates the wavelet transform blocks. Second, the basic wavelet decomposition is applied to transform the image data to the wavelet coefficients. The discrete wavelet transforms are the kernel component of MinImage and are discussed in detail. The different wavelet transforms can be plugged in to extend the functionality of MinImage. The third step is the quantization. The standard scalar quantization algorithm and the optimized quantization algorithm, as well as the dequantization, are described. The last part of MinImage is the entropy-coding schema. The reordering of the coefficients based on the Peano Curve and the different entropy coding methods are discussed. This paper also gives the specification of the wavelet compression parameters adjusted by the end user. The interface, parameter specification, and analysis of MinImage are shown in the final appendix.

We impose a monotonicity condition with several reversals on the moduli of the coefficients of a polynomial. We then consider three types of polynomials: (1) those satisfying the condition on all of the coefficients, (2) those satisfying the condition on the even indexed and odd indexed coefficients separately, and (3) polynomials of the form P(z) = a0+ Σnj=µ ajzj where µ ≥ 1 with the coefficients aµ; aµ+1;…; an satisfying the condition. For each type of polynomial, we give a result which puts a bound on the number of zeros in a disk (in the complex plane) centered at the origin. For each type, we give an example showing the results are best possible.

We put restrictions on the coefficients of polynomials and give bounds concerning the number of zeros in a specific region. The restrictions involve a monotonicity-type condition on the coefficients of the even powers of the variable and on the coefficients of the odd powers of the variable (treated separately). We present results by imposing the restrictions on the moduli of the coefficients, the real and imaginary parts of the coefficients, and the real parts (only) of the coefficients.

(Page numbers are given in brackets after sub-headings.) Chapter 1 :-Application of operational methods of solution to ordinary differential equations with constant coefficients. Motion of helical springs --- Free vibration ( p.2 ) --- Forced vibration ( p.7 ) --- Resonance ( p.10 ) ----- Linked springs ( p.12 ) --- Analogous electrical problems ( P. 15 ). Appendix A :-Laplace Transformations. ( p.18 ) Appendix B :- Brief explanation of the operational methods of solution used in the chapter. ( p.19 ) Appendix C :- Example of partial fraction working. ( p.21a) Chapter 2 :- Application of Fourier Series and of operational methods of solution to partial differential equations. Small transverse vibrations of a light elastic string ( p.22 ) Vibration of a string initially plucked at its middle point ( p.28 ) --- Alternative method of solution of the preceeding problem by operational methods ( p.31 ) --- Discussion of the shape assumed by the string at any time ( p.36 ) Chapter 3 :- Application of Bessel Functions to the solution of partial differential equations of the second order. Small vibrations of a light circular membrane ( p.39 ) Appendix A :- Transformation of the differential equation of motion from Cartesian to cylindrical coordinates. ( p.46 ). Appendix B :- Note on roots of Bessel Functions. ( p.47 ) Appendix C :- Bessel Functions - Some important results applied in the chapter. p.48 ). Chapter 4 :- Application of Legendre Polynomials to the solution of partial differential equations of the second order. Conduction of heat in a solid body ( p.50 ) ---------- Flow of heat in a solid sphere ( p.53 ). Appendix :-Statement of the Divergence Theorem used in the chapter. ( p.61 ). Chapter 5 :- Example of Simultaneous Partial Differential Equations. The flow of electricity in a long imperfectly insulated cable ( p.62 ) ---- Analogous problem of the flow of heat in rod of small uniform cross section ( p.69 ). / Thesis / Master of Arts (MA)