• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 68
  • 16
  • 16
  • 16
  • 16
  • 16
  • 16
  • 7
  • 5
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 128
  • 128
  • 19
  • 15
  • 13
  • 12
  • 11
  • 10
  • 10
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • 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.
81

Enhancing Petroleum Recovery From Heavy Oil Fields By Microwave Heating

Acar, Cagdas 01 June 2007 (has links) (PDF)
There are many heavy oil reservoirs with thin pay zones (less than 10 m) in the world and in Turkey. Conventional steam injection techniques are not costeffective for such reservoirs, due to excessive heat loss through the overburden. Heat losses can be minimized through controlled heating of the pay zone. One such way is to introduce heat to the reservoir in a controlled manner is microwave heating. Laboratory studies on microwave heating of a scaled model of a heavy oil reservoir with a thin pay zone are presented with an economical feasibility of the method. In this thesis, three different conceptual oil reservoirs from south east Turkey are evaluated: Bati Raman (9.5 API) and &Ccedil / amurlu (12 API) heavy crude oils and paraffinic Garzan (26 API)crude oil. Using a graphite core holder packed with crushed limestone with crude oil and water microwave effects of operational parameters like heating time and waiting period as well as rock and fluid properties like permeability, porosity, wettability, salinity, and initial water saturation are studied. The main recovery mechanisms for the experiments are viscosity reduction and gravity drainage. An analytical model is developed by coupling heat equation with the electromagnetic dissipated power per unit of volume based in Maxwell&#039 / s equation successfully models the experiments for temperatures less than the pyrolysis temperature is presented. Also the experiments are scaled to the model by geometric similarity concept. In economic evaluation, the cost of oil is calculated based on domestic electricity prices.
82

Analysis of di(2-ethylhexyl) phthalate in polyvinyl chloride and monosodium glutamate in foodstuff using high performance liquidchromatography and the investigation of microwave digestion method forpaint analysis

鄧善均, Tang, Shin-kwan, Andrew. January 1989 (has links)
published_or_final_version / Chemistry / Master / Master of Philosophy
83

Integrated dual frequency permittivity analyzer using cavity perturbation concept

Meda, Venkatesh. January 2002 (has links)
Optimal utilization of microwave energy requires more basic knowledge of the dielectric properties of the material under investigation. The dielectric properties of materials subjected to microwaves are known to depend on moisture content, temperature and density of the material as well as the frequency of the applied microwave field. This thesis is focussed on the development and evaluation of the new Permittivity Analyser to measure the dielectric properties of agri-food materials at 915 and 2450 MHz using cavity perturbation concept. / In this study, the dielectric properties measuring system was designed and developed using cavity perturbation concept to measure the essential and fundamental parameters of microwave-material interaction; dielectric constant and dielectric loss factor of selected agri-food substances and organic solvents. The TM010 mode of electromagnetic energy was selected and configured to operate at the peakresonant condition for both ISM (Industrial, Scientific and Medical) approved frequencies of .915 and 2450 MHz frequencies. The resonant perturbation cavities were designed, fabricated and tested using the network analyser and the permittivity analyser. High Q (ratio of energy supplied to absorbed) values were reported for both frequencies. Basic calibration of the measurement system was performed using standard media such as air, water and alcohol. Necessary mathematical steps and algorithms were written and integrated into a user-friendly software program (Visual basic 6.0) to carry out the entire measurement. / The dielectric properties (epsilon' & epsilon ″) of materials such as; edible oils---canola, soya and sunflower oils, neem oil/pulp, homogenized milk (1, 2 and 3.25% fat), organic solvents such as ethanol, hexane and their mixtures were determined at various temperatures and frequency (915, 2450 MHz) combinations, using cavity perturbation technique. Linear relationships between the dielectric properties and temperature found in the literature were confirmed to be valid for certain ranges in case of edible oils, organic solvents and milk samples tested with the cavity perturbation method. Repeatibility and variability aspects of the permittivity analyzer at both the frequencies are presented.
84

High pressure and microwave assisted generation and pyrolysis-GCMS analysis of glycated proteins

Li, Pik Kei, 1978- January 2002 (has links)
The extent of denaturation and glycation of lysozyme and BSA with the application of high hydrostatic pressure (HHP) at 400 MPa at 30°C from 8 to 48 hours and focused microwave irradiation at 50°C under varying microwave power and from 10 to 60 minutes was investigated in the presence and absence of D-glucose. The HHP treatment caused 10 to 20% denaturation of lysozyme whereas microwave irradiation caused 20 to 40% denaturation, with more destruction to the lysozyme in the presence of glucose compared to the control. The extent of glycation was also higher with the high pressure samples, causing 60% glycation upon 8 hours of high pressure exposure, but decreasing to around 40% thereafter. Microwave irradiation brought about 40% glycation to the lysozyme samples upon 20 min of irradiation. BSA, on the other hand, was more susceptible to damage by high energy exposures. BSA samples were denatured to a greater extent compared to lysozyme, up to 80% upon the prolonged exposures, but in all treatments, glucose seemed to act as a protectant contrary to the case of lysozyme. The extent of glycation detected was also minimal, ranging from 8 to 20%. / The feasibility of analyzing glycated proteins using pyrolysis-GC/MS was also investigated. Taking advantage of the formation of a diagnostic marker---2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one---upon pyrolysis of glycated proteins, the intensity of this peak was used to correlate the extent of glycation. The intensity of this peak in the pyrograms of glycated lysozymes was found to increase linearly with increasing incubation times and subsequently with the sugar loads of the glycated lysozyme. In addition, using the pyrograms as unique fingerprints, the extent of structural changes between modified and unmodified proteins were also assessed.
85

Microwave-assisted extraction and synthesis studies and the scale-up study with the aid of FDTD simulation

Dai, Jianming. January 2006 (has links)
The research undertaken in this thesis includes microwave-assisted extraction (MAE), synthesis, and the investigation of the scale-up of the microwave-assisted processes with the numerical aid. / The main goal of this research is to study the various problems associated with the scale-up of the microwave-assisted extraction and synthesis processes. Laboratory studies were carried out to investigate the microwave-assisted extraction of known components from peppermint leaves and American ginseng. Various factors that influence the extraction processes were studied. Microwave-assisted extraction method was compared with conventional heating and room temperature extraction methods on the extraction of ginsenosides from American ginseng. Microwave-assisted extraction method was determined to have higher extraction rate than both room temperature extraction and reflux temperature extraction using hotplate heating indicating that there is acceleration factor in enhancing the extraction rate beyond the temperature influence. / In the study of synthesizing n-butyl paraben, microwave-assisted synthesis was observed to greatly increase the yield of n-butyl paraben in much shorter period of time compared to the classic synthesis method. A transition state theory was proposed to explain this rate enhancement. The study of the synthesis of parabens with different alcohol and the influencing factors on the synthesis of n-butyl paraben yield were also studied. / A visualization method was developed to determine the microwave distribution in a domestic microwave cavity. The method uses gypsum plate as carrier and cobalt chloride as indictor. A simulation program was developed using the finite difference time domain (FDTD) approach and written in C programming language. The program was proved to be very versatile in different type of cavity simulation. Not only cavities with different dimensions and geometrical designs can be simulated, multiple magnetrons and various ways of magnetron placement can also be integrated into the simulation program. The detailed power distribution can be visualized in a 3-D plot, and the power distribution in each layer can be analyzed using the simulation result. The power distribution information will be very useful and necessary before any real equipment development.
86

Analysis of di(2-ethylhexyl) phthalate in polyvinyl chloride and monosodium glutamate in foodstuff using high performance liquid chromatography and the investigation of microwave digestion method for paint analysis /

Tang, Shin-kwan, Andrew. January 1989 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1990.
87

Nontraditional synthesis of organometallic compounds and allylic alcohols /

Hesse, Andrew J. January 2007 (has links)
Thesis (B.S.) Magna Cum Laude--Butler University, 2007. / Includes bibliographical references (leaves 26-27).
88

An annotated bibliography on microwaves: their properties, production, and applications to food processing

January 1973 (has links)
[by] Samuel A. Goldblith and Robert V. Decareau.
89

Aplicacao de diferentes metodologias na preparacao de matrizes organicas para a determinacao voltametrica de elementos traco

SISTI, CRISTINA 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:45:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:26Z (GMT). No. of bitstreams: 1 07287.pdf: 2056507 bytes, checksum: 770280526de75f4fc2cf87a5aa34f1e9 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
90

Aplicacao de diferentes metodologias na preparacao de matrizes organicas para a determinacao voltametrica de elementos traco

SISTI, CRISTINA 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:45:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:26Z (GMT). No. of bitstreams: 1 07287.pdf: 2056507 bytes, checksum: 770280526de75f4fc2cf87a5aa34f1e9 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Page generated in 0.0783 seconds