• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 221
  • 57
  • 47
  • 44
  • 17
  • 15
  • 12
  • 12
  • 9
  • 6
  • 4
  • 4
  • 2
  • 2
  • 2
  • Tagged with
  • 540
  • 181
  • 156
  • 97
  • 67
  • 58
  • 50
  • 41
  • 39
  • 38
  • 37
  • 37
  • 36
  • 36
  • 35
  • 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.
51

Comparing Optical Coherence Tomography Radial and Cube Scan Patterns for Measuring Bruch’s Membrane Opening Minimum Rim Width (BMO-MRW) in Glaucoma and Healthy Eyes: Cross-sectional and Longitudinal Analysis

Kabbara, Sami 02 April 2018 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Background and Significance: Spectral Domain-Optical Coherence Tomography (OCT) is one of the most widely used imaging modality in Ophthalmology. It utilizes light waves to visualize the various layers of the retina. The OCT machines offer two different scan patterns, the circular and the cube scan patters. It is important to compare these scan pattern to see if any discrepancy exist in quantifying retinal indices. One of the newer indices is the Bruch’s membrane opening minimum rim width (BMO-MRW), which is the minimum distance between from the BMO to the inner limiting membrane (ILM). The BMO-MRW is being used in the diagnosis of glaucoma. Hypothesis: To compare the cube and radial scan patterns of the SD-OCT for quantifying the BMO-MRW. We hypothesis that there might be some differences between the two scan patterns.
52

Calculation of the efficiency of PWM inverter-fed induction motor drives

Cann, Roy Geoffrey January 1983 (has links)
No description available.
53

Thin position, bridge structure, and monotonic simplification of knots

Zupan, Alexander Martin 01 July 2012 (has links)
Since its inception, the notion of thin position has played an important role in low-dimensional topology. Thin position for knots in the 3-sphere was first introduced by David Gabai in order to prove the Property R Conjecture. In addition, this theory factored into Cameron Gordon and John Luecke's proof of the knot complement problem and revolutionized the study of Heegaard splittings upon its adaptation by Martin Scharlemann and Abigail Thompson. Let h be a Morse function from the 3-sphere to the real numbers with two critical points. Loosely, thin position of a knot K in the 3-sphere is a particular embedding of K which minimizes the total number of intersections with a maximal collection of regular level sets, where this number of intersections is called the width of the knot. Although not immediately obvious, it has been demonstrated that there is a close relationship between a thin position of a knot K and essential meridional planar surfaces in its exterior E(K). In this thesis, we study the nature of thin position under knot companionship; namely, for several families of knots we establish a lower bound for the width of a satellite knot based on the width of its companion and the wrapping or winding number of its pattern. For one such class of knots, cable knots, in addition to finding thin position for these knots, we establish a criterion under which non-minimal bridge positions of cable knots are stabilized. Finally, we exhibit an embedding of the unknot whose width must be increased before it can be simplified to thin position.
54

A Comparison of Mednick's Remote Associates Test and Pettigrew's Category-Width Test

Sesney, John W. 01 May 1968 (has links)
The present study was designed to examine the relationship between Mednick's Remote Associates Test and Pettigrew's Category-Width Test. The sample was made up of 36 educational psychology students enrolled in the Utah State Summer School. The correlation for males and females was made independently. Although the males showed a higher correlation between the two tests than did the females (males, .296 and females, .058), the correlations were not statistically significant. No full explanation was given for the lack of correlation between the category-width scores and the RAT scores except for the qualification that the RAT may be measuring a different type of creativity than what the category-width test is measuring.
55

Service and Ultimate Limit State Flexural Behavior of One-Way Concrete Slabs Reinforced with Corrosion-Resistant Reinforcing Bars

Bowen, Galo Emilio 11 June 2013 (has links)
This paper presents results of an experimental investigation to study the structural performance and deformability of a concrete bridge deck reinforced with corrosion resistant reinforcing (CRR) bars, i.e., bars that exhibit improved corrosion resistance when embedded in concrete as compared to traditional black steel. Flexural tests of one-way slabs were conducted to simulate negative transverse flexure over a bridge girder as assumed in the commonly employed strip design method. The bar types studied were Grade 60 (uncoated), epoxy-coated reinforcing (ECR, Grade 60), Enduramet 32 stainless steel, 2304 stainless steel, MMFX2, and glass fiber reinforced polymer (GFRP). The experimental program was designed to evaluate how a one-to-one replacement of the Grade 60 with CRR, a reduction of concrete top clear cover, and a reduction in bar quantities in the bridge deck top mat influences flexural performance at service and ultimate limit states. Moment-curvature predictions from the computer-based sectional analysis program Response 2000 were consistent with the tested results, demonstrating its viability for use with high strength and non-metallic bar without a defined yield plateau.    Deformability of the concrete slab-strip specimens was defined with ultimate-to-service level ratios of midspan deflection and curvature. The MMFX2 and Enduramet 32 one-to-one replacement specimens had deformability consistent with the Grade 60 controls, demonstrating that bridge deck slabs employing high strength reinforcement without a defined yield plateau can still provide sufficient ductility at an ultimate limit state. A reduction in bar quantity and cover provided acceptable levels of ductility for the 2304 specimens and MMFX2 reinforced slabs. / Master of Science
56

Application of pulse width modulation to a Western blotting device

TruongVo, ThucNhi January 2016 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / One of the critical steps in a current Western blot technique is a blotting process, which in general requires one electrophoretic gel for every protein species to be analyzed. In most cases, multiple protein species are analyzed simultaneously and thus it is necessary for a scientist to run multiple gels. In order to make it possible to analyze multiple protein species from a single gel, a novel blotting device, BlotMan, was employed in this study. Designed by Dr. Chien’s group (YC Bioelectric), BlotMan uses pulse width modulation (PWM) for applying a protein size-dependent voltage during a blotting process. In this study, the differential average voltage profile, depending on protein size (e.g. 17 kDa to 140 kDa), was built and enabled BlotMan to transfer all protein species in equal efficiency regardless of the protein size. Furthermore, Blot- Man consists of a user-friendly, custom-made interface box, which can be remotely controlled by a smart phone. BlotMan’s capability was evaluated using standard protein markers, as well as protein samples that were isolated from chondrosarcoma cells (SW1353) and breast cancer cells (MDA-MB-213). The experimental results revealed that BlotMan was capable of generating 5 blotting membranes from a single gel simultaneously. Protein species such as c-Src, eukaryotic translation initiation factor 2 alpha (eIF2α) and its phosphorylated form (p-eIF2α), lamin B, and β-actin were successfully detected. It is also demonstrated that compared to a regular constant voltage, PWM signals improved transfer efficiency and a signal-to-noise ratio. In conclusion, this study demonstrated that BlotMan was able to facilitate Western blotting analysis by generating multiple blotting membranes from a single gel with an improved signal-to-noise ratio. Further analysis is recommended for understanding the mechanism of PWMts action on transfer efficiency and noise reduction.
57

Hybrid 2D-3D Space Vector Modulation For Three-Phase Voltage Source Inverter

Albatran, Saher 17 August 2013 (has links)
Three-phase voltage source inverters are increasingly employed in power systems and industrial applications. Various pulse width modulation strategies have been applied to control the voltage source inverters. This dissertation presents a hybrid 2D-3D space vector modulation algorithm for three-phase voltage source inverters with both three-wire and four-wire topologies. The voltage magnitude and phase angle of the inverters fundamental output phase voltage are precisely controlled under either balanced or unbalanced load conditions, and hence, the space vector algorithm offers synchronization controllability over generation control in distributed generation systems. The numerical efficiency and simplicity of the proposed algorithm are validated through conducting MATLAB/Simulink simulations and hardware experiments. Mathematical description and harmonic analyses of output phase voltages of three-phase voltage source inverter which employs a hybrid 2D-3D SVM are presented in this dissertation. Explicit time domain representation of the harmonic components in addition to the total harmonic distortion of the output phase voltages are given in terms of system and switching parameters. The dissertation also investigates the harmonic characteristics and low total harmonic distortion performance against the linearity of modulation region which helps in the harmonic performance and design studies of such inverters employing the hybrid 2D-3D SVM. Experimental results are used to validate these analyses. In addition, the performance and the harmonic contents of the inverter output phase voltage when applying the proposed hybrid 2D-3D SVM are compared to that obtained from conventional 2D SVM and 3D SVM. As a result, the proposed new algorithm shows advantages in terms of low total harmonic distortion and reduced harmonic contents in both three-wire and four-wire systems.
58

Changes in foot and lower limb coupling due to systematic variations in step width

Pohl, M.B., Messenger, N., Buckley, John 02 November 2005 (has links)
No / Motion at the midfoot joints can contribute significantly to overall foot motion during gait. However, there is little information regarding the kinematic coupling relationship at the midfoot. The purpose of the present study was to determine whether the coupling relationship at the midfoot and subtalar joints was affected when step width was manipulated during running. Twelve subjects ran over-ground at self-selected speeds using three different step widths (normal, wide, cross-over). Coupling at the midfoot (forefoot relative to rearfoot) and subtalar (rearfoot relative to shank) joints was assessed using cross-correlation techniques. Rearfoot kinematics were significantly different from normal running in cross-over running (P < 0.05) but not in wide running. However, coupling between rearfoot eversion/inversion and shank rotation was consistently high (r > 0.917), regardless of step width. This was also the case for coupling between rearfoot frontal plane motion and forefoot sagittal plane (r < 0.852) and forefoot transverse plane (r > 0.946) motion. There was little evidence of coupling between rearfoot frontal plane motion and forefoot frontal plane motion in any of the conditions. Forefoot frontal plane motion appeared to have little effect on rearfoot frontal plane motion and thus, had no effect on motion at the subtalar joint. The strong coupling of forefoot sagittal and transverse plane motions with rearfoot frontal plane motion suggests that forefoot motion exerts an important influence on subtalar joint kinematics.
59

Episode 1.4 – Pulse Width Modulation

Tarnoff, David 01 January 2020 (has links)
In this episode, we show how a binary signal can be used to give the appearance of an analog output. We then use this understanding to show how to dim an LED on the Arduino open source platform.
60

An invesitigation into the factors involved in preparation and weaving affecting the length and width of woven cloth. Effect of warping and weaving tensions, warp control devices, and relaxation processes on warp and weft modular length and thread spacings. The influence of beat-up force and cloth-fell distance.

Basu, Asok K. January 1980 (has links)
So far the theoretical approach to weaving resistance and fabric geometry and the factors affecting it have been made for such weaves as plain, hop-sack and warp and weft faced ribs. In this work theoretical models were adopted to determine the fabric geometry and weaving resistance. Experimental and theoretical findings are in agreement. The trends of the effects on values of weaving resistance of such factors as warp elastic constant, weft tension, warp tension, the coefficient of friction of yarn against. yarn agree with the trends obtained by other workers by showing that weaving resistance increases with these factors. The results-also show that-the fabric geometry depends on warp and weft tension at-the moment of beat-up. Additionally, the change of fabric geometry across the fabric, the effect of two different let-off mechanisms,, Hattersley and WIRA/Poole, and the beaming CO processes on weaving resistance and fabric geometry were investigated. It was found that the fabric width-depends on the dynamics of fabric formation before and at the moment of beat-up. / Wool Industries Research Association

Page generated in 0.0454 seconds