• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 31
  • 14
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 61
  • 12
  • 12
  • 12
  • 12
  • 12
  • 12
  • 12
  • 12
  • 12
  • 12
  • 10
  • 8
  • 8
  • 7
  • 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.
31

Improved implementation strategies to sustain energy saving measures on mine cooling systems / Philip Mare

Maré, Philip January 2015 (has links)
Reliable, efficient and cost-effective energy supply is crucial for economic and social development. Mining and industrial sectors consumed close to 37% of the total energy produced in the world during 2013. The South African power network is strained by the rapid expansion of mining, industrial and public sectors. Generation, transmission and distribution of electrical energy are in progress, but supply will not meet demand in the near future. The South African electricity supplier needs capital for expansion. Electricity price increases have been significantly higher than increases in the gold price over the last few years. Mining companies are under pressure from government to improve their labour relations. They are obligated to spend money on local infrastructure development. Therefore, cost efficiency receives higher priority than ever before and requires an implementation strategy. Cooling systems on mines proved to be significant electricity consumers. These systems lack integrated management and efficient and optimised control. Electricity demand can be reduced through implementation of energy saving measures on these cooling systems. Energy saving measures reduce the operational costs of mining to ensure that mines stay globally competitive. The identification of long-term challenges for energy saving measures is crucial. Successful implementation of energy saving measures results in improved utilisation and performance of mine cooling systems. These measures must be maintained to ensure a constant positive impact on reduced electrical energy consumption. The electrical energy savings are dependent on external factors, such as ambient conditions. Improved implementation strategies of energy saving measures will prevent deterioration of utilisation and performance of the mine cooling systems. Monitoring and reporting of key performance indicators are crucial. Lack of integrated maintenance can lead to lost opportunities and the deterioration of equipment and machines. The improved implementation strategies in two separate case studies proved sustainable savings of 1.73 MW and 0.66 MW respectively. The electricity cost savings for Mine A and Mine B are R8.8 million and R2.9 million respectively. These savings have been sustained for periods of seventeen and seven months respectively, indicating the value of the study. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015
32

Aspektuella hjälpverb i svenskan / Aspectual auxiliaries in Swedish

Bylin, Maria January 2013 (has links)
This thesis tells the tales of auxiliation in Swedish. It describes how the auxiliary features of the aspectual auxiliaries bruka ‘use to’, tendera ‘tend to’, börja ‘begin, start’, fortsätta ‘continue’, sluta ‘stop, cease’ och hota ‘threaten’ evolve, as seen in a text corpora covering the 11th to the 21st century. A grammaticalization perspective is employed, which not unexpectedly has implications for the way data is interpreted and presented, but also less expectedly for how the method is understood and applied. The method consists of Swedish auxiliary tests, designed to reveal auxiliary features. The discussion of their validity involves auxiliation theory as well as a more general theoretical discussion of how the category and the function of auxiliaries have been conceived. The main point made is that a valid test should have an explicit link to auxiliary function. Establishing the nature of such a link, however, is no trivial matter and so the plausibility of the link turns out to be the main factor in judging the validity of auxiliary tests. In the early stages of the auxiliation processes, action nominals were often used as complements of the verbs under study. Later on these verbs started taking infinitive complements, lost their semantic restrictions on their subjects and started occurring in a type of passive construction where the nonfinite verb carries the semantic relationship to the arguments of the clause. The occurrence in this type of passive construction is perceived as the most plausible indication of auxiliary function available for subject raising auxiliaries, since the auxiliary and the nonfinite verb in these clauses do function together as one single predicate. The evolution of these aspectual auxiliaries essentially follows the predictions made by auxiliation theory. That said, they all show individual deviations from those predictions, depending on such factors as their semantics, their source construction and during which period in the history of Swedish their auxiliation took place.
33

"Componente educativo na formação e prática profissional do pessoal auxiliar odontológico" / Educative component in the formation and professional activity of the auxiliary personnel in odontology

Tomazevic, José Miguel 09 December 2005 (has links)
O presente trabalho teve como objetivo fornecer aspectos históricos da educação profissional e inserção do pessoal auxiliar odontológico no Brasil, utilizando-se como referências o campo da Educação, Trabalho e Saúde. A investigação teve como objetivo o levantamento de ações desenvolvidas pelos Auxiliares de Consultório Dentário e Técnicos em Higiene Dental e compará-las ao que aprenderam no curso profissional de três instituições públicas na Grande São Paulo. A pesquisa contou com a participação de 68 funcionários, sendo que, independente da função, receberam o mesmo questionário. A maioria deles tinha formação profissional (83%), e a resposta mais comum sobre a pergunta: o que não aprenderam no curso, mas aprenderam na prática, diz respeito às atividades consideradas administrativas. E, em relação às atividades educativas, a maioria do pessoal auxiliar as realiza, mas nem sempre as planeja e executa em conjunto com o cirurgião-dentista. Assim, percebeu-se que fatores como inclusão de conhecimentos considerados administrativos nos currículos (teóricos e práticos) dos cursos de Auxiliar de Consultório Dentário e Técnico em Higiene Dental dos centros formadores podem preparar melhor seus alunos para tais ações e contribuir para o do trabalho adequado em equipe, além de estarem de acordo com o preconizado pelo Ministério da Educação: Resolução CEB nº 4/99, Decreto nº 16/99; e documento do Ministério da Saúde: Perfil das Competências Profissionais do Técnico em Higiene Dental e do Auxiliar de Consultório Dentário. / This work had the purpose to supply historical aspects of the professional education and insertion of the personnel auxiliary in odontology in Brazil, using as reference the area of Education, Labor and Health. The investigation had the purpose of gathering information by Dental Assistants and Dental Hygienists and compare them to the one learned in the Professional course in three public institutions in São Paulo and nearby cities. The research had the participation of 68 employess, being that, regardless their function, received the same questionnaire. The majority of them had professional skills (83%), the most common reply to the question on what they had not learned in the course, but in practice, was about the activities considered as administrative. And concerning the educational the majority of the auxiliary personnel carries them out, but they don’t always plan and perform them along with the dentist surgeon. Thus, it was observed that factors such as inclusion of lessons considered administrative in the course (theory and practice) of Dental Assistants and Dental Hygienists of the schools, can prepare better their pupils for such actions and contribute to the proper work in team, besides being in accordance with what the Ministry of Education requires, Resolutions CEB nº 4/99, Decree nº 16/99, and Document of the Health Departament: Profile of Professional Abilities of THD and ACD.
34

The development and use of English modal auxiliaries in Chinese EFL learners.

January 1989 (has links)
by Huang Chenfeng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 175-182.
35

Four Quadrant Computer Based Motor Tests System Develeopmenet

Inan, Tolga 01 October 2003 (has links) (PDF)
Development and research activities about electric motors require realistic feedback about the motor performance and efficiency. This feedback can be supplied by the help of the motor test systems without waiting for the end-user. Throughout this study, a computer based motor test system with four quadrant loading capability is developed. The system is capable of entering user-defined test conditions, performing tests, acquisition of test data and displaying test results. The system has a visual user interface that can handle all tasks from a single computer.
36

Common Mode Voltage And Current Reduction In Voltage Source Inverter Driven Three Phase Ac Motors

Un, Emre 01 January 2008 (has links) (PDF)
In this thesis various reduced common mode voltage (RCMV) pulse width modulation (PWM) techniques and active/passive common mode voltage (CMV) reduction methods for voltage source inverter driven three-phase AC motors are theoretically and practically investigated. A novel RCMV-PWM method, the near state PWM (NSPWM) method is proposed for operation at high modulation index. At low modulation index, a modified version of an existing RCMV-PWM method, AZSPWM1, termed as MAZSPWM, is proposed to mitigate the voltage reflection problem of the method. An optimum modulation algorithm combining NSPWM and MAZSPWM with seamless transition is proposed. The proposed RCMV-PWM methods significantly reduce CMV but they suppress common mode current (CMC) partially. Utilization of a common mode inductor together with RCMV-PWM methods is effective in suppressing the CMC. In the study, in addition to the CMV characteristics, various practical performance characteristics such as voltage linearity, inverter output current ripple, inverter DC-link current ripple, and output line-to-line voltage pulse pattern are also analyzed. The study involves analysis, computer simulations, and detailed laboratory experiments.
37

Synthesis of original fluorinated cyclopropylcarboxylates

Ivashkin, Pavel 22 November 2013 (has links) (PDF)
Organofluorine compounds constitute a large part of all the drugs, crop protection agents and advanced materials produced nowadays. Therefore, there is a great interest in developing the new methods of synthesis of organofluorine compounds. In this thesis we report a novel method of synthesis of monofluorinated cyclopropanes based on the Michael-initiating ring closure (MIRC) reaction. Our method allows obtaining polysubstituted monofluorinated cyclopropanes from ethyl dibromofluoroacetate and various Michael acceptors. We have also implemented the asymetric version of cyclopropanation using a novel oxazolodinone-derived chiral fluorinated reagent. In the final part of this thesis we report the synthesis of a fluorinated analog of L-FAP4, a potent agonist of group II metabotropic glutamate receptors (mGluR II). Incorporation of a fluorine atom is expected to increase the biological activity and bioavailabiblity of this compound.
38

Speed Sensorless Vector Control Of Induction Machine

Ozcelik, Eray 01 June 2005 (has links) (PDF)
Focus of this work is closed-loop speed control of an induction machine based on direct field-oriented control (DFOC) algorithm, using estimates of speed and flux observers which utilize only stator current and voltage. Theoretical bases of the algorithms are explained in detail and their performances are investigated with simulations and experiments. Field Orientated Control is based on projections which transform a threephase time and speed dependent system into a two co-ordinate time invariant system. These projections lead to a structure similar to that of a DC machine control. Transformations are done in synchronous frame alligned to d-axis of rotor flux. So rotor flux position must be known accurately to make these transformations. Degined flux observer, in which voltage model is assisted by current model via a closed-loop to compensate voltage model&rsquo / s disadvantages, estimates the position of the rotor flux. Obtaining adequate torque control via FOC, speed loop is closed using conventional PI regulators. Speed feedback is necessary to complete control loop. Model Reference Adaptive System is studied as a speed estimator. Reactive power scheme is applied to MRAS algorithm to estimate rotor speed. In this study, the direct (rotor) flux oriented control system with flux and speed estimators is described and tested in real-time with the starter kit named TMS320F2812 eZdsp DSK and the Embedded Target for the TI C2000 DSP tool of Matlab
39

Adição de nucleofilos a ions N-aciliminios quirais e reações de ciclização promovidas por Pd(0) / Nucleophilic addition to chiral N-acyliminium ions and palladium(0)-mediated cyclization reactions

Robello, Luis Gustavo, 1975- 14 December 2006 (has links)
Orientador: Ronaldo Aloise Pilli / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-08T04:04:52Z (GMT). No. of bitstreams: 1 Robello_LuisGustavo_D.pdf: 7203530 bytes, checksum: a92a57231d7587b04ebb16da51b52419 (MD5) Previous issue date: 2006 / Doutorado / Quimica Organica / Doutor em Ciências
40

"Componente educativo na formação e prática profissional do pessoal auxiliar odontológico" / Educative component in the formation and professional activity of the auxiliary personnel in odontology

José Miguel Tomazevic 09 December 2005 (has links)
O presente trabalho teve como objetivo fornecer aspectos históricos da educação profissional e inserção do pessoal auxiliar odontológico no Brasil, utilizando-se como referências o campo da Educação, Trabalho e Saúde. A investigação teve como objetivo o levantamento de ações desenvolvidas pelos Auxiliares de Consultório Dentário e Técnicos em Higiene Dental e compará-las ao que aprenderam no curso profissional de três instituições públicas na Grande São Paulo. A pesquisa contou com a participação de 68 funcionários, sendo que, independente da função, receberam o mesmo questionário. A maioria deles tinha formação profissional (83%), e a resposta mais comum sobre a pergunta: o que não aprenderam no curso, mas aprenderam na prática, diz respeito às atividades consideradas administrativas. E, em relação às atividades educativas, a maioria do pessoal auxiliar as realiza, mas nem sempre as planeja e executa em conjunto com o cirurgião-dentista. Assim, percebeu-se que fatores como inclusão de conhecimentos considerados administrativos nos currículos (teóricos e práticos) dos cursos de Auxiliar de Consultório Dentário e Técnico em Higiene Dental dos centros formadores podem preparar melhor seus alunos para tais ações e contribuir para o do trabalho adequado em equipe, além de estarem de acordo com o preconizado pelo Ministério da Educação: Resolução CEB nº 4/99, Decreto nº 16/99; e documento do Ministério da Saúde: Perfil das Competências Profissionais do Técnico em Higiene Dental e do Auxiliar de Consultório Dentário. / This work had the purpose to supply historical aspects of the professional education and insertion of the personnel auxiliary in odontology in Brazil, using as reference the area of Education, Labor and Health. The investigation had the purpose of gathering information by Dental Assistants and Dental Hygienists and compare them to the one learned in the Professional course in three public institutions in São Paulo and nearby cities. The research had the participation of 68 employess, being that, regardless their function, received the same questionnaire. The majority of them had professional skills (83%), the most common reply to the question on what they had not learned in the course, but in practice, was about the activities considered as administrative. And concerning the educational the majority of the auxiliary personnel carries them out, but they don’t always plan and perform them along with the dentist surgeon. Thus, it was observed that factors such as inclusion of lessons considered administrative in the course (theory and practice) of Dental Assistants and Dental Hygienists of the schools, can prepare better their pupils for such actions and contribute to the proper work in team, besides being in accordance with what the Ministry of Education requires, Resolutions CEB nº 4/99, Decree nº 16/99, and Document of the Health Departament: Profile of Professional Abilities of THD and ACD.

Page generated in 0.0481 seconds