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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.
21

Applications of source signature deconvolution to airgun seismic profiling and the measurement of attenuation from reflection seismograms

Wrolstad, Keith H. 04 August 1978 (has links)
Deterministic source signature deconvolution is applied to the processing of marine wide angle and vertical profiler data with air-gun sources. Optimum results are obtained with a source signature measured by stacking the signal reflected from a relatively homogeneous abyssal plain sedimentary environment. This eliminates the need for the unstable inverse source-receiver ghost filter. Improved resolution of reflection event timing allows the computation of more reliable interval velocities by the T² - X² method, provided the layer thickness limitation of the method is not exceeded. Accurate timing of primary reflection events in the deconvolved vertical profiler data permits computation of frequency dependent attenuation by univariate least-squares regression in the Fourier transform domain. The technique successfully extracts input amplitude attenuation functions from model reflection coefficient sequences with additive random noise. This success is attributed to the stability of singular value analysis in solving the least-squares regression model. Statistical tests on the solution vectors for model and field data give criteria for evaluating their reliability. The model data studies suggest that multiple and primary events not included in the regression may be considered part of the noise term without seriously affecting the accuracy of the computed spectral ratios. The method is tested on field data from the following sedimentary environments off the coast of Oregon and northern California: a continental shelf basin, an abyssal plain environment, the base of the continental slope and two locations on the Astoria sea fan, one near the Cascadia sea channel and one north of DSDP site 174. Velocity versus depth and frequency dependent spectral ratio plots are determined for each environment. The computed surface layer interval velocity of 1.77 km/sec over a thickness of 455 m for the station north of DSDP site 174 is in good agreement with the average material type found in the drill core (sandy-silt with greater than 60% sand). Maximum attenuation coefficients are estimated from the spectral ratios for the upper sediment intervals of the study areas using typical acoustic impedance values of surface sediment types determined from nearby piston cores. Some maximum attenuation coefficients are too high suggesting the possibility of a stratigraphic component. The maximum attenuation in the upper interval for SB 46 over the Tufts abyssal plain where fine-grained material (silts and clays) is expected is 0.025 dB/m at 127 Hz compared with 0.004 dB/m at 80 Hz for the upper interval of the turbidite environment north of DSDP site 174. / Graduation date: 1979 / Best scan available for figures.
22

Rural farmers' experience in living with prostate cancer following diagnosis and treatment

Gronvold, Darren Philip 31 May 2004
In Canada, prostate cancer is the most frequently diagnosed cancer among men. The incidence continues to rise. Although there is a growing empirical literature on the prostate cancer experience of men who live and work in urban areas, little is known about the experience of men who live and work in rural settings where access to treatment and support may present unique challenges. The purpose of this qualitative research was to explore the experiences of men diagnosed and treated for prostate cancer who live and work (farm) in rural Saskatchewan. Using a Naturalistic Inquiry approach and methods of Grounded Theory Analysis, six participants were recruited through a physicians office, advertisements, and cancer support groups, and interviewed. The interview data were audio-taped, transcribed verbatim, and analyzed. Data analysis revealed five common themes: farming and rural life, physical and emotional concerns, sexuality, masculinity, thoughtfulness and reflection, helping others and being helped. There was no evidence of rural isolation or concern with travelling to the cities for treatment. Depression and anxiety were not reported as major concerns. Participants explained that while continuing to farm helped them cope, fatigue reduced their ability to farm and increasingly they relied on help from family and neighbours. Participants experienced a sense of urinary urgency and/or incontinence following treatment and managed their daily activities to lesson the impact. All were impotent following treatment. They coped with loss of sexual function through a renewed life perspective or use of medication to restore sexual function. Traditional masculine behaviours can be a barrier to health screening for men with prostate cancer. Participants used their prostate cancer experience to engage in activities of new learning, new meaning, and new perspectives and to educate and support other men with prostate cancer. This study highlights the need for further research on the health experiences of farmers and other rural men, and to uncover the variety of masculine and behavioural responses with respect to mens health issues. Although the range of health issues may be similar from one man to another, it is important for health care providers to understand individual differences.
23

Rural farmers' experience in living with prostate cancer following diagnosis and treatment

Gronvold, Darren Philip 31 May 2004 (has links)
In Canada, prostate cancer is the most frequently diagnosed cancer among men. The incidence continues to rise. Although there is a growing empirical literature on the prostate cancer experience of men who live and work in urban areas, little is known about the experience of men who live and work in rural settings where access to treatment and support may present unique challenges. The purpose of this qualitative research was to explore the experiences of men diagnosed and treated for prostate cancer who live and work (farm) in rural Saskatchewan. Using a Naturalistic Inquiry approach and methods of Grounded Theory Analysis, six participants were recruited through a physicians office, advertisements, and cancer support groups, and interviewed. The interview data were audio-taped, transcribed verbatim, and analyzed. Data analysis revealed five common themes: farming and rural life, physical and emotional concerns, sexuality, masculinity, thoughtfulness and reflection, helping others and being helped. There was no evidence of rural isolation or concern with travelling to the cities for treatment. Depression and anxiety were not reported as major concerns. Participants explained that while continuing to farm helped them cope, fatigue reduced their ability to farm and increasingly they relied on help from family and neighbours. Participants experienced a sense of urinary urgency and/or incontinence following treatment and managed their daily activities to lesson the impact. All were impotent following treatment. They coped with loss of sexual function through a renewed life perspective or use of medication to restore sexual function. Traditional masculine behaviours can be a barrier to health screening for men with prostate cancer. Participants used their prostate cancer experience to engage in activities of new learning, new meaning, and new perspectives and to educate and support other men with prostate cancer. This study highlights the need for further research on the health experiences of farmers and other rural men, and to uncover the variety of masculine and behavioural responses with respect to mens health issues. Although the range of health issues may be similar from one man to another, it is important for health care providers to understand individual differences.
24

A Study of Preservice Teachers' on Teaching Beliefs and Teaching Reflective Behavior During Teaching Practicum Courses

Tsai, Feng-chih 26 January 2005 (has links)
The major purpose of this study is to explore the preservice teachers¡¦ teaching beliefs, its influential factors and teacher belief changes after teaching practicum courses and teaching reflection. There are two main purposes of this study: (1)To explore preservice teachers¡¦ teaching beliefs and its influential factors. (2)To explore preservice teachers¡¦ teaching reflection during teaching practicum courses. For achieving the above purposes of the study, it took one semester to collect data and interviews for exploring teaching beliefs, classroom observation, microteaching, field experiences and teaching reflection and analyzing preservice teachers¡¦ teaching beliefs, influential factors and teaching reflection in concept mapping, assignments and interviews. The final provides some suggestions for teaching professional growth and the improvement of teacher education. The results indicated that preservice teacher¡¦s teaching beliefs are through single to diversification and progress substitute for traditions in the varied age. After a series of teaching practicum courses, teaching beliefs cannot practice teaching behavior. There are three main factors: (1)The classroom observation: according to mentor¡¦s pedagogy, it is back to traditional teaching. (2)The external factor: under the pressure of obtaining high degrees, on the basis of the premise that the grade of the student was improved results in a learning instruction style which teachers are active but the students are passive. (3)The internal factor: unfamiliar teaching experience and lack of professional knowledge result in differences between teaching beliefs and teaching behaviors. Reflective behavior of the preservice teacher has three stages: (1)The optimistic teaching beliefs for field experiences: to understand curriculum planning is difficult. (2)Unexpected problems in field experiences: even though preservice teachers understand the problem in confused classroom, they can not improve their teaching behaviors immediately. (3)Face to reality situation of teaching on field experiences: preservice teachers are conscious of curriculum planning imperfect , lack of explanation ability , to ¡§guess¡¨ students¡¦ prior knowledge, lack of the ability of classroom management and professional knowledge for teaching.
25

An Action research on Reflection and Listening: Learning History of a Group of Partner

Lin, Ming-Dar 13 February 2007 (has links)
The main purpose of this study was to investigate the suitable practice and model of reflection and listening for A Company through the action progress of learning history of partner. This study belongs to action research. The experiment field was A Company. It targeted at the learning of reflection and listening. Through reflection-in-action and reflection-on-action in the process of learning history, the problems and dilemmas encountered by each action plan werereflected to seek for solutions and to revise the action plan. Then the learn procedure was built. From the progress of action plan, it sought for newfindings which can be the reference for A Company to promote learning of reflection and listening continuously. The results of this study were as follows: 1, Find the researcher and job partner's blind spot, listen attentively to through "listener ". 2, Common participation, help to the learning of reflection and listening. 3, Put in order out the learn procedure reflection and listening attentively to from action experience.
26

Low Loss Hybrid Antiresonant Reflection Optical Waveguide Devices At 1.3£gm

Lan, Ying-Che 19 June 2001 (has links)
A low-loss polyimide/Ta2O5/SiO2 antiresonant reflecting optical waveguide (ARROW) at quasi-antiresonant condition is presented for the first time. The ARROW device was fabricated using both the organic and dielectric thin film technologies. It consisted of the fluorinated polyimide, tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) hybrid layers deposited on a Si substrate. For TE polarized light, the propagation loss of the waveguide as low as 0.4 dB/cm was obtained at 1.3 mm. The propagation loss for TM polarized light was 1.5 dB/cm. An ARROW waveguide fabricated using the polyimide/Ta2O5/polyimide material system is also presented for comparison. In addition, anisotropic etching of Si-V grooves were formed using the EDP solution, and room temperature sputtered Ta2O5 was used as the etching mask. At a etching temperature of 1200C, the under cut of the V-groove is 1.6mm
27

Study on Micro/Nano structures of anti-reflective layers used in solar cells

Hu, Chih-Chieh 11 November 2009 (has links)
Recently, the skills to reduce the solar cell reflectance at oblique incidence to enhance the overall efficiency of solar cells attracted much attention. the relationships between geometric structures, aspect ratios (depth over width) and sizes of the anti-reflective film (AR film) with the angles of incidence by using an optical simulation software "TracePro ". Simulation results showed that the anti-reflection effect produced by the trench structure is much lower than that of the plane structure. Structure of the higher aspect ratio and smaller size can also be effective in improving anti-reflection. PDMS was chosen as the material to construct an anti-reflective layer. Then, the study used optic lithography techniques to produce square-column structures with aspect ratios of 0.5 and 2 and also four pyramid structures of sizes 20,40,60,80 microns. Using a solar simulator we measured and calculated efficiency in generation of power with respect to different angles of incidence. At angle of incidence at 60 degrees, structure with aspect ratio of 2 obtained 14.7% higher efficiency in power generation than that of structure with ratio of 0.5. Decrease in size also enhanced efficiency. Also at 60 degrees of incidence, pyramid structure of 20um obtained over 19.6% of generating capacity than that of pyramid structure of 80um . At last, etching of PDMS surface was completed using carbon tetra fluoride (CF4) plasma. The PDMS surface thus became random nano-structure. Using Electron microscopy, the desired feature was discovered to become a micron-level structure if the processing time of plasma etching exceeds 4 hours. Two types of structures were produced by CF4 plasma etching, that by processing time of 2 hours and 4 hours on the AR film, respectively. At a 60-degree angle of incidence, AR film by 4 hours of etching obtained 18.8% greater generating capacity than that of AR film by 2 hours of etching.
28

3D seismic surface multiple attenuation algorithms and analysis /

Alaslani, Abdulaziz Saleh, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.
29

Analysis and modeling of high-resolution multicomponent seismic reflection data

Guy, Erich D., January 2003 (has links)
Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xxxviii, 372 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Jeffrey J. Daniels, Dept. of Geological Sciences. Includes bibliographical references (p. 362-372).
30

Matters of reflection in quality teaching : a study of teachers' reflection in the contexts of their professional lives /

Jay, Joelle K. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 246-250).

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