Documents disponibles chez cet éditeur

Compactness in modules / Abdallah Laradji 

Public ISBD Titre : Compactness in modules Type de document : texte imprimé Auteurs : Abdallah Laradji, Auteur Editeur : Sheffield : University of Sheffield Année de publication : 1985 Importance : 126 f. Format : 27 cm. Note générale : Thèse de Doctorat : Mathématique Appliqués : Royaume-Uni, University of Sheffield : 1985 Annexe f. 127 - 133 . Bibliogr. f. 134 - 136 Langues : Anglais (eng) Mots-clés : Mathématique  ;  Algebraic  compactness  ;  Purity  ;  Pure  injectivity  ;  Filters  ;  Regressive  functions Index. décimale : D002285 Résumé : This thesis is concerned with the study of algebraic compactness for modules using systems of equations. The first two chapters provide an introduction to the subject via purity and pure-injectivity. In chapter 3 and 4, we discuss the various types of algebraic compactness and give some charcterizations of Σ-algebraic compact modules. Filters are used in chaptre 5 to genrralize results on χ₀-compact quotients to higher cardinals. In chapter 6, we show that the proof of a theorem of Mycielski on filter quotients is incorrect by using regressive functions. The results of chapter 5 are applied to prove weaker versions of his theorem. In the last chapter, we construct for each n Є IN a finitely solvable system of equations which is χn₋₁-solvable but not χn-solvable, and a module which is χn₋₁-compact but not χn-compact. Finally, an appendix on ordinals and cardinals with definitions and statements of the properties used in this thesis is given. Compactness in modules [texte imprimé] / Abdallah Laradji, Auteur . - Sheffield : University of Sheffield, 1985 . - 126 f. ; 27 cm. Thèse de Doctorat : Mathématique Appliqués : Royaume-Uni, University of Sheffield : 1985 Annexe f. 127 - 133 . Bibliogr. f. 134 - 136 Langues : Anglais (eng) Mots-clés : Mathématique  ;  Algebraic  compactness  ;  Purity  ;  Pure  injectivity  ;  Filters  ;  Regressive  functions Index. décimale : D002285 Résumé : This thesis is concerned with the study of algebraic compactness for modules using systems of equations. The first two chapters provide an introduction to the subject via purity and pure-injectivity. In chapter 3 and 4, we discuss the various types of algebraic compactness and give some charcterizations of Σ-algebraic compact modules. Filters are used in chaptre 5 to genrralize results on χ₀-compact quotients to higher cardinals. In chapter 6, we show that the proof of a theorem of Mycielski on filter quotients is incorrect by using regressive functions. The results of chapter 5 are applied to prove weaker versions of his theorem. In the last chapter, we construct for each n Є IN a finitely solvable system of equations which is χn₋₁-solvable but not χn-solvable, and a module which is χn₋₁-compact but not χn-compact. Finally, an appendix on ordinals and cardinals with definitions and statements of the properties used in this thesis is given.

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Documents numériques

LARADJI.Abdellah.pdf URL

An investigation of the loss distribution in induction motors fed from nonsinusoidal supplies / Nacereddine Benamrouche 

Public ISBD Titre : An investigation of the loss distribution in induction motors fed from nonsinusoidal supplies Type de document : texte imprimé Auteurs : Nacereddine Benamrouche, Auteur ; M. McCormick, Directeur de thèse Editeur : Sheffield : University of Sheffield Année de publication : 1991 Importance : 133 f. Présentation : ill. Format : 30 cm. Note générale : thèse de Doctorat : Électrotechnique : Angleterre, University of Sheffield : 1991 Bibliogr. f. 134 - 143 . Annexe f. 144 - 151 Langues : Anglais (eng) Mots-clés : Losses Induction  motors  fed Nonsinusoidal  supplies Mainstream  models Time-temperature  technique Index. décimale : D001391 Résumé : Many authors have examined the calculation of losses in induction motors fed from nonsinusoidal supplies using lumped circuit models. In published literature considerable controversy still exists as to the efficacy of a perticular model. In this thesis three mainstream models are independently examined in a systematic objective manner and their ability to predict the losses in two 4 KW, 415 V, 3 phase squirrel cage induction motors is assessed. Analysis of experimental and theoretical results confirms that the uncertainties and differences existing are due to the difficulties involved in accurately estimating the different iron loss components. A further weakness of lumped circuit methods is their inability to predict the spacial distribution of losses which is particularly important with respect to the temperature rise. To overcome this deficiency the time-temperature teccnique was examined. In order to carry out this investigation a specialised experimental rig was constructed. The experimental results are discussed and using the well known least-squares interpolation technique temperature and loss density information throughout the volume of the machine was generated. A computer program was developed which allows the information to be presented in colour coded form tomographically. To the best knowledge of the author non such information has hitherto been available. Finally, it should be noted that all aspects of the experimental and theoretical work are appropriately supported by customisied software. An investigation of the loss distribution in induction motors fed from nonsinusoidal supplies [texte imprimé] / Nacereddine Benamrouche, Auteur ; M. McCormick, Directeur de thèse . - Sheffield : University of Sheffield, 1991 . - 133 f. : ill. ; 30 cm. thèse de Doctorat : Électrotechnique : Angleterre, University of Sheffield : 1991 Bibliogr. f. 134 - 143 . Annexe f. 144 - 151 Langues : Anglais (eng) Mots-clés : Losses Induction  motors  fed Nonsinusoidal  supplies Mainstream  models Time-temperature  technique Index. décimale : D001391 Résumé : Many authors have examined the calculation of losses in induction motors fed from nonsinusoidal supplies using lumped circuit models. In published literature considerable controversy still exists as to the efficacy of a perticular model. In this thesis three mainstream models are independently examined in a systematic objective manner and their ability to predict the losses in two 4 KW, 415 V, 3 phase squirrel cage induction motors is assessed. Analysis of experimental and theoretical results confirms that the uncertainties and differences existing are due to the difficulties involved in accurately estimating the different iron loss components. A further weakness of lumped circuit methods is their inability to predict the spacial distribution of losses which is particularly important with respect to the temperature rise. To overcome this deficiency the time-temperature teccnique was examined. In order to carry out this investigation a specialised experimental rig was constructed. The experimental results are discussed and using the well known least-squares interpolation technique temperature and loss density information throughout the volume of the machine was generated. A computer program was developed which allows the information to be presented in colour coded form tomographically. To the best knowledge of the author non such information has hitherto been available. Finally, it should be noted that all aspects of the experimental and theoretical work are appropriately supported by customisied software.

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BENAMROUCHE.Nacereddine.pdf URL

Investigation of multi-oscillator of electrical behaviour of the digestive tract / M. Khelfa 

Public ISBD Titre : Investigation of multi-oscillator of electrical behaviour of the digestive tract Type de document : texte imprimé Auteurs : M. Khelfa, Auteur ; D. A. Linbeus, Directeur de thèse Editeur : Sheffield : University of Sheffield Année de publication : 1983 Importance : 26 f. Présentation : ill. Format : 27 cm. Note générale : Mémoire de Master : Electronique : Angleterre, University of Sheffield : 1983 Annexe [68] f. Bibliogr. [1] f Langues : Anglais (eng) Mots-clés : Oscillators Electrical  activity Gastrointestinal  tract Electronic  implementation Hodgkin-Huxley  squid  axon  membrane Index. décimale : Ms00283 Résumé : The main objective of this thesis is to provide support of linked oscillators model of electrical activity in gastrointestinal tract. Chapter 2 explains the work done by Alvarez in 'Currents in stomac and intestine'. Chapter 3, a general background to the project. Chapter 4 the modelling of the small intestine by using analogue computer. The description of the membrane current is given in chapter 5. Chapter 6 contains the explanation of the electronic implementation where the model of the intestine comprising 64 coupled Hodgkin-Huxley type non-linear oscillators. The individual oscillator units are based on a modified version of an analogue of the Hodgkin-Huxley squid axon membrane due to Roy. Investigation of multi-oscillator of electrical behaviour of the digestive tract [texte imprimé] / M. Khelfa, Auteur ; D. A. Linbeus, Directeur de thèse . - Sheffield : University of Sheffield, 1983 . - 26 f. : ill. ; 27 cm. Mémoire de Master : Electronique : Angleterre, University of Sheffield : 1983 Annexe [68] f. Bibliogr. [1] f Langues : Anglais (eng) Mots-clés : Oscillators Electrical  activity Gastrointestinal  tract Electronic  implementation Hodgkin-Huxley  squid  axon  membrane Index. décimale : Ms00283 Résumé : The main objective of this thesis is to provide support of linked oscillators model of electrical activity in gastrointestinal tract. Chapter 2 explains the work done by Alvarez in 'Currents in stomac and intestine'. Chapter 3, a general background to the project. Chapter 4 the modelling of the small intestine by using analogue computer. The description of the membrane current is given in chapter 5. Chapter 6 contains the explanation of the electronic implementation where the model of the intestine comprising 64 coupled Hodgkin-Huxley type non-linear oscillators. The individual oscillator units are based on a modified version of an analogue of the Hodgkin-Huxley squid axon membrane due to Roy.

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Documents numériques

KHELFA.M.pdf URL

Cycloaddition reactions of ketens / Ahmed Lakoues 

Public ISBD Titre : Cycloaddition reactions of ketens Type de document : texte imprimé Auteurs : Ahmed Lakoues, Auteur ; G. A. Taylor, Directeur de thèse Editeur : Sheffield : University of Sheffield Année de publication : 1983 Importance : 105 f. Présentation : ill. Format : 30 cm. Note générale : Mémoire de Master : Génie Chimique : Royaume-Uni, University of Sheffield : 1983 Bibliogr. f. 121 - 123 Langues : Anglais (eng) Mots-clés : Ketenes Cyclobutanone  ring Spectroscopic  studies t-butylcyanoketene Index. décimale : Ms00583 Résumé : Ketenes have been reacted with a number of polyenes to give the 1 : 1 and 2 : 1 adducts. The influence of the first formed cyclobutanone ring on the regioselectivity and stereoselectivity of the second ketene addition was studied. From the reaction of the 1 : 1 adduct (cyclohexadiene : diphenylketene) with diphenylketene and t-butylcyanoketene, the only isolated products were the 2. The only isolated product from the reaction of the 1 : 14 adduct (cyclopentadiene : diphenylketene) with t-butylcyanoketene, was the 2. The only isolated product from the reaction of cycloheptatriene with diphenylketene, was the 1. The 1 : 1 adduct (butadiene : diphenylketene) failed to react with diphenylketene and t-butylcyanoketene. Cycloaddition reactions of ketens [texte imprimé] / Ahmed Lakoues, Auteur ; G. A. Taylor, Directeur de thèse . - Sheffield : University of Sheffield, 1983 . - 105 f. : ill. ; 30 cm. Mémoire de Master : Génie Chimique : Royaume-Uni, University of Sheffield : 1983 Bibliogr. f. 121 - 123 Langues : Anglais (eng) Mots-clés : Ketenes Cyclobutanone  ring Spectroscopic  studies t-butylcyanoketene Index. décimale : Ms00583 Résumé : Ketenes have been reacted with a number of polyenes to give the 1 : 1 and 2 : 1 adducts. The influence of the first formed cyclobutanone ring on the regioselectivity and stereoselectivity of the second ketene addition was studied. From the reaction of the 1 : 1 adduct (cyclohexadiene : diphenylketene) with diphenylketene and t-butylcyanoketene, the only isolated products were the 2. The only isolated product from the reaction of the 1 : 14 adduct (cyclopentadiene : diphenylketene) with t-butylcyanoketene, was the 2. The only isolated product from the reaction of cycloheptatriene with diphenylketene, was the 1. The 1 : 1 adduct (butadiene : diphenylketene) failed to react with diphenylketene and t-butylcyanoketene.

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LAKOUES.Ahmed.pdf URL

An experimental study into the operation of a solar chimney used for the improvement of natural ventilation in buildings / Mohammed Bouhedja 

Public ISBD Titre : An experimental study into the operation of a solar chimney used for the improvement of natural ventilation in buildings Type de document : texte imprimé Auteurs : Mohammed Bouhedja, Auteur ; I. C. Ward, Directeur de thèse Editeur : Sheffield : University of Sheffield Année de publication : 1987 Importance : 145 f. Présentation : ill. Format : 30 cm. Note générale : Mémoire de Master : Génie Civil : Sheffield, University of Sheffield : 1987 Annexe f. 146 - 166 . Bibliogr. [8] f Langues : Anglais (eng) Mots-clés : Buildings Ventilation Solar  chimney Cooling  technique Index. décimale : Ms00587 Résumé : In hot countries building densities are usually high, so as to minimize the heat gain from solar radiation. As a result the air motion through and around buildings is reduced. Thus the prime role which natural ventilation can play in cooling buildings is affected. In order to promote natural ventilation and hence induce passive cooling of the buildings the use of a solar chimney has been introduced. The present study is aimed at improving the performance of a solar chimney by increasing the airflow rate using valves to control both the chimney temperature and the flow rate. The author suggests that this method could be applied to buildings in the Southern part of Algeria. First, an analysis of the main meteorological components of the Algerian climate, which enables builders and designers to define the heating and cooling energy resuirements of buildings, is carried out. The results of this analysis are then used to define the boundaries of the different passive coolung strategies recommended for each region. A review of the work done on the use of the different passive cooling techniques related to buildings is then carried out, emphasizing the role which natural ventilation plays in restoring comfortable conditions. The experiments conducted and the adopted techniques are then presented, and the experimental programme implemented to establish the optimum design of a low cost solar air heater, and the effect of alternatively closing and opening of the solar chimney on the airflow rate. Finally, an operating cycle in which the airflow rate is increased above the mean value when the panel is running free is suggested. An experimental study into the operation of a solar chimney used for the improvement of natural ventilation in buildings [texte imprimé] / Mohammed Bouhedja, Auteur ; I. C. Ward, Directeur de thèse . - Sheffield : University of Sheffield, 1987 . - 145 f. : ill. ; 30 cm. Mémoire de Master : Génie Civil : Sheffield, University of Sheffield : 1987 Annexe f. 146 - 166 . Bibliogr. [8] f Langues : Anglais (eng) Mots-clés : Buildings Ventilation Solar  chimney Cooling  technique Index. décimale : Ms00587 Résumé : In hot countries building densities are usually high, so as to minimize the heat gain from solar radiation. As a result the air motion through and around buildings is reduced. Thus the prime role which natural ventilation can play in cooling buildings is affected. In order to promote natural ventilation and hence induce passive cooling of the buildings the use of a solar chimney has been introduced. The present study is aimed at improving the performance of a solar chimney by increasing the airflow rate using valves to control both the chimney temperature and the flow rate. The author suggests that this method could be applied to buildings in the Southern part of Algeria. First, an analysis of the main meteorological components of the Algerian climate, which enables builders and designers to define the heating and cooling energy resuirements of buildings, is carried out. The results of this analysis are then used to define the boundaries of the different passive coolung strategies recommended for each region. A review of the work done on the use of the different passive cooling techniques related to buildings is then carried out, emphasizing the role which natural ventilation plays in restoring comfortable conditions. The experiments conducted and the adopted techniques are then presented, and the experimental programme implemented to establish the optimum design of a low cost solar air heater, and the effect of alternatively closing and opening of the solar chimney on the airflow rate. Finally, an operating cycle in which the airflow rate is increased above the mean value when the panel is running free is suggested.

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Documents numériques

BOUHEDJA.Mohammed.pdf URL