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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.
121

Manometric determination of the biochemical oxygen demand of sulfite paper mill wastes

Ketner, Samuel Edgar January 1951 (has links)
In nearly all chemical industries the problem of wastes is one of importance, and in any scientific study of waste disposal, the concept of the B.O.D. of the waste is vital. The B.O.D. is usually measured by an arbitrary standard test procedure, but may be determined by manometric measurement of the free oxygen utilized. In either case, the B.O.D. determination requires at least 24 hours. Since the free oxygen involved in the B.O.D. of a waste is utilized in metabolic processes of various microorganisms present, an increase in the number of microorganisms lowers the time required for oxidation of the wastes. In this investigation, the B.O.D. of several wastes was determined by measuring the change in the oxygen uptake of high concentrations of microorganisms because of the presence of the waste. These determinations involved a modification of the resting cell technic used in conjunction with direct Warburg technics. High concentrations of washed cells were prepared and small amounts of the waste added. A control was prepared with distilled water. The effects of waste concentration, bacterial concentration, and temperature were studied. The wastes studied included raw sewage, blowdown liquor and total mill wastes from a semichemical pulp mill, and effluent from an anaerobic, sewage-blowdown liquor digester. The concentrations of microorganisms used ranged from 3.4 to 17.0 milligrams of dry bacterial cells in a total volume of 2.5 milliliters of a 0.05 molar phosphate buffer at a pH of 6.8. The manometric B.O.D. was determined at 30°C. The manometric B.O.D. remained constant at 1,785 parts per million for 1:50 and 1:125 volumetric dilutions of the effluent. The manometric B.O.D. remained constant at 10,200 parts per million for volumetric dilutions ranging from 1:125 to 1:1000 for a sample of the blowdown liquor. The manometric B.O.D. of sewage, blowdown liquor, and mixtures of the two wastes was determined. The values obtained were compared with the standard five-day B.O.D. The manometric B.O.D. of the sewage and the blowdown liquor was 413 parts per million and 13,760 parts per million, respectively. The standard five-day B.O.D. of the sewage and the blowdown liquor was 495 parts per million and 37,800 parts per million, respectively. The manometric B.O.D. of 1:1 by volume mixture of the two wastes was 9,900 parts per million, while the standard five-day B.O.D. was 31,200 parts per million. / Master of Science
122

Foulant adsorption onto ion exchange membranes

Watkins, E. James 16 June 1999 (has links)
No description available.
123

Equações de difusão para objetos unidimensionais no contexto das teorias de Yang-Mills

Teixeira, Bruno Fernando Inchausp 07 March 2017 (has links)
Submitted by Biblioteca do Instituto de Física (bif@ndc.uff.br) on 2017-03-07T18:35:27Z No. of bitstreams: 1 TESE.pdf: 797081 bytes, checksum: 36b77c687969ac7b12aeef2589d1d766 (MD5) / Made available in DSpace on 2017-03-07T18:35:27Z (GMT). No. of bitstreams: 1 TESE.pdf: 797081 bytes, checksum: 36b77c687969ac7b12aeef2589d1d766 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / O confinamento de quarks e glúons continua sendo um dos maiores problemas da Física atual, mesmo depois de passados 50 anos da criação da cromodinâmica quântica. Existem diversas abordagens que procuram uma explicação para este comportamento. Um destes cenários consiste na supercondutividade dual, proposta por G. t’Hooft em 1978. Aqui, ele discute como a condensação de objetos cromomagnéticos poderia originar um potencial linear entre cargas cromoelétricas. Este mecanismo é um dos mais aceitos atualmente e nos dirige à algumas perguntas cruciais: como estes objetos poderiam se tornar relevantes em teorias de Yang-Mills puras? quais os tipos de objetos que devemos levar em consideração para gerar as propriedades do potencial confinante? Embora a primeira pergunta seja difícil de responder, a segunda pode ser atacada por técnicas diferentes, suportadas pelas descrições na rede e por descrições efetivas de ensembles 1. Nesta tese, me dedico a estudar uma classe de objetos que s˜ao bons candidatos a resolverem a segunda questão: monopólos e vórtices de centro. Quando estamos lidando com as teorias de Yang-Mills puras SU(N), o problema consiste que, em nível clássico, estes defeitos são singulares. Porém, recebendo suporte da rede (nosso laboratório em teoria quântica de campos), podemos imaginar que, devido a flutuações quânticas do vácuo, estes objetos poderiam adquirir algumas propriedades dimensionais, como tensão,rigidez e interações que ajudariam a caracterizar o ensemble magnético nos levando a descrições de campos efetivas, que podem ser utilizadas para extrair a corda elétrica confinante. Utilizando técnicas oriundas da física de polímeros obtivemos equações de difusão que representam objetos unidimensionais, como vórtices de centro em 3D ou monopólos em 4D. O surgimento de uma derivada covariante abeliana, no caso do ensemble de vórtices de centro e instantons correlacionados em 3D, e de uma derivada covariante não abeliana, no caso do ensemble de monopólos coloridos em 4D, foi fundamental paragerar os modelos efetivos correspondentes. Acreditamos que estas equações de difusão poderão ser úteis, no futuro, para relacionar as propriedades do potencial entre quarks e aquelas de seus possíveis ensembles correspondentes. / Nowadays, quark and gluon confinement continues to be one of the most important problems in Physics. It remains unsolved, although 50 years have passed since the foundations of quantum chromodynamics. There are various approaches aimed at explaining this behaviour. One of them is the dual superconductor scenario proposed by G. t’Hooft in 1978. The general idea is that the condensation of chromomagnetics objects could originate a linear potential between chromoelectric charges. This is a promising mechanism that posses some crucial questions: how could these objects be relevant in pure YangMills? what type of object would be needed in order to generate the properties of the confining potential? While the first question is very difficult, the second one can be approached by different techniques, guided by the lattice and effective ensemble descriptions. In this thesis, I’ve been working on some good candidates to solve the second question: monopoles and center vortices. When dealing with pure SU(N) Yang-Mills theory, the problem is that at the classical level these magnetic defects are singular. Nevertheless, supported by the lattice (our laboratory in quantum field theory), we can imagine that, due to quantum vacuum fluctuations, they could acquire dimensionful properties. The tension, stiffness, as well as possible interactions that characterize the magnetic ensemble lead to effective field descriptions, that could be used to extract the corresponding confining electric string. Based on techniques borrowed from the physics of polymers, we obtained diffusion equations that describe magnetic one-dimensional objects, such as center vortices in 3D and monopoles in 4D. The appearance of an Abelian covariant derivative, for an ensemble of chains in 3D, and a non Abelian one, in the case of coloured loops in 4D, was essential to generate the corresponding effective descriptions. We believe that these diffusion equations could be helpful in the future, to relate the properties of the interquark potential and those of the possible underlying ensembles.
124

A scheduling model for production in a hot strip mill

Hamman, Gert J. M. 06 December 2011 (has links)
M.Ing. / This research dissertation highlights the important role of scheduling in a production environment. The functioning of an integrated iron and steel works is discussed. The importance of production scheduling in this environment is shown, followed by a literature survey of strip mill production scheduling models. Thereafter a model is introduced that aids in the production scheduling of plate via coil in a hot strip mill. Finally the benefits of the scheduling model are shown.
125

Steady state sifting of first break wheat stock

Ferrer, Alonso Parrague January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
126

ANTENNA CONTROL FOR TT&C ANTENNA SYSTEMS

Kaiser, Julius A., Herold, Fredrick W. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / A thinned array sensor system develops error voltages for steering dish antennas from signals arriving over a broad range of angles, thereby eliminating need for a priori knowledge of signal location.
127

A compact expression for periodic instantons

Cherkis, Sergey A., O’Hara, Clare, Zaitsev, Dmitri 12 1900 (has links)
Instantons on various spaces can be constructed via a generalization of the Fourier transform called the ADHM-Nahm transform. An explicit use of this construction, however, involves rather tedious calculations. Here we derive a simple formula for instantons on a space with one periodic direction. It simplifies the ADHM-Nahm machinery and can be generalized to other spaces.
128

Exact global symmetry generators for restricted Schur polynomials

Bornman, Nicholas January 2016 (has links)
A dissertation submitted in fulfillment of the requirements for the degree of Master of Science. August 2016. / The six scalar fields in N = 4 super Yang-Mills theory enjoy a global SO(6) symmetry, and large N but non-planar limits of this theory are well-described by adopting a group representation approach. Studies have shown that the one-loop dilatation operator is highly determined by the action of the su(2)=su(3) subalgebras on restricted Schur polynomials. These actions involve the traces of products of projection operators. In this dissertation, exact analytical formulae for these traces are found which in turn are used to find the exact action of these algebras on restricted Schur polynomials. The potential of the su(2) algebra to determine the one-loop dilatation operator is also explored. This is done by exploiting necessary symmetry conditions and moving to a continuum limit in order to derive a number of partial differential equations which determine the dilatation operator. The ultimate goal of this work is to provide tools to find the exact one-loop dilatation operator in the non-planar limit. / LG2017
129

Giant graviton oscillators

Mathwin, C. R. 30 July 2013 (has links)
A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. 14 May 2013 / We study the action of the dilatation operator on restricted Schur polynomials labeled by Young diagrams with p long columns or p long rows. A new version of Schur-Weyl duality provides a powerful approach to the computation and manipulation of the symmetric group operators appearing in the restricted Schur polynomials. Using this new technology, we are able to evaluate the action of the one loop dilatation operator. The result has a direct and natural connection to the Gauss Law constraint for branes with a compact world volume. Generalzing previous results, we find considerable evidence that the dilatation operator reduces to a decoupled set of harmonic oscillators. This strongly suggests that integrability in N = 4 super Yang-Mills theory is not just a feature of the planar limit, but extends to other large N but non-planar limits.
130

Non-planar Ads/CFT from group representation theory

Smith, Stephanie 12 June 2014 (has links)
In this thesis we explore certain limits of the AdS/CFT correspondence for integrability. This is done by calculating the action of the dilatation operator on operators known as restricted Schur polynomials, which are AdS/CFT dual to D3-branes known as giant gravitons. We focus on operators in N = 4 super-Yang-Mills theory, which is dual to type IIB string theory on an AdS5×S5 background. We find that, in various cases, this theory is integrable in a large N non-planar limit.

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