• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 220
  • 113
  • 66
  • 35
  • 29
  • 22
  • 16
  • 16
  • 16
  • 11
  • 10
  • 2
  • 2
  • 1
  • Tagged with
  • 624
  • 117
  • 68
  • 61
  • 60
  • 58
  • 53
  • 50
  • 48
  • 48
  • 44
  • 38
  • 38
  • 36
  • 36
  • 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.
221

THE USE OF A WHOLE GENOME SCAN TO FIND A GENETIC MARKER FOR DEGENERATIVE SUSPENSORY LIGAMENT DESMITIS IN THE PERUVIAN PASO HORSE

Strong, Diane I. 01 January 2005 (has links)
Degenerative suspensory ligament desmitis (DSLD) is a debilitating disease of connective tissues seen in many breeds but has become prevalent in the Peruvian Pasohorse. DSLD is believed to be a genetic disorder caused by one primary founder and most likely has a recessive mode of inheritance although a dominant or co-dominant mode of inheritance has not been ruled out. A genome scan using 259 microsatellite markers was used to test for linkage disequilibrium between one or more markers and DSLD. Two groups of Peruvian Pasohorses were selected from one population including the US and Canada. The only difference between the two groups of horses besides the size of the two groups was the presence of DSLD in the affected group and the absence of DSLD in the unaffected group. It was assumed that differences seen between the two groups in homozygosity and or common allele frequency could be an indication of linkage to DSLD. As a connective tissue disorder, there were a large number of candidate genes forDSLD to consider, yet no identical human or animal model exists. The genome scan identified five chromosomal regions where statistically significant differences were seen between affected and unaffected sample populations that could be indications of linkage to DSLD. Those chromosomes were: ECA 6, 7, 11, 14, and 26. Sequencing of a portion of the G domain in the Chondroitin Sulfate Proteoglycan2 (CSPG2) gene has mostly ruled out that segment of chromosome 14 as having linkage to DSLD. Further research needs to be conducted in the regions of ECA 6,7,11 and 26 where statistically significant differences were seen between the affected and unaffected groups, especially on ECA 6 and 11 since possible candidate genes are located in those regions based on the human comparative map.
222

Scan Registration Using the Normal Distributions Transform and Point Cloud Clustering Techniques

Das, Arun January 2013 (has links)
As the capabilities of autonomous vehicles increase, their use in situations that are dangerous or dull for humans is becoming more popular. Autonomous systems are currently being used in several military and civilian domains, including search and rescue operations, disaster relief coordination, infrastructure inspection and surveillance missions. In order to perform high level mission autonomy tasks, a method is required for the vehicle to localize itself, as well as generate a map of the environment. Algorithms which allow the vehicle to concurrently localize and create a map of its surroundings are known as solutions to the Simultaneous Localization and Mapping (SLAM) problem. Certain high level tasks, such as drivability analysis and obstacle avoidance, benefit from the use of a dense map of the environment, and are typically generated with the use of point cloud data. The point cloud data is incorporated into SLAM algorithms with scan registration techniques, which determine the relative transformation between two sufficiently overlapping point clouds. The Normal Distributions Transform (NDT) algorithm is a promising method for scan registration, however many issues with the NDT approach exist, including a poor convergence basin, discontinuities in the NDT cost function, and unreliable pose estimation in sparse, outdoor environments. This thesis presents methods to overcome the shortcomings of the NDT algorithm, in both 2D and 3D scenarios. To improve the convergence basin of NDT for 2D scan registration, the Multi-Scale k-Means NDT (MSKM-NDT) algorithm is presented, which divides a 2D point cloud using k-means clustering and performs the scan registration optimization over multiple scales of clustering. The k-means clustering approach generates fewer Gaussian distributions when compared to the standard NDT algorithm, allowing for evaluation of the cost function across all Gaussian clusters. Cost evaluation across all the clusters guarantees that the optimization will converge, as it resolves the issue of discontinuities in the cost function found in the standard NDT algorithm. Experiments demonstrate that the MSKM-NDT approach can be used to register partially overlapping scans with large initial transformation error, and that the convergence basin of MSKM-NDT is superior to NDT for the same test data. As k-means clustering does not scale well to 3D, the Segmented Greedy Cluster NDT (SGC-NDT) method is proposed as an alternative approach to improve and guarantee convergence using 3D point clouds that contain points corresponding to the ground of the environment. The SGC-NDT algorithm segments the ground points using a Gaussian Process (GP) regression model and performs clustering of the non ground points using a greedy method. The greedy clustering extracts natural features in the environment and generates Gaussian clusters to be used within the NDT framework for scan registration. Segmentation of the ground plane and generation of the Gaussian distributions using natural features results in fewer Gaussian distributions when compared to the standard NDT algorithm. Similar to MSKM-NDT, the cost function can be evaluated across all the clusters in the scan, resulting in a smooth and continuous cost function that guarantees convergence of the optimization. Experiments demonstrate that the SGC-NDT algorithm results in scan registrations with higher accuracy and better convergence properties than other state-of-the-art methods for both urban and forested environments.
223

Nonlinear self-focusing and beam propagation using gaussian laguerre mode decomposition

Rodney Mcduff Unknown Date (has links)
This thesis descibes a theoretical study of nonlinear self-focusing as applied to the metrology of the nonlinear optical parameters of a medium. It also studies the phe- nomenon of optical power limiting which utilizes self-focusing e ects. As an analytical tool, a mode decomposition method which uses an orthogonal and complete set of Gaussian-Laguerre modes as a basis set is used to treat these problems. Nonlinear media both in the thin and thick limits are investigated. For thin media, a closed form expression is derived which describes the optical eld of an initally Gaussian beam that is perturbed by a thin nonlinear material which exhibits nonlinear absorption as well as nonlinear refraction. This result is valid for any regime of nonlinearity in the thin medium approximation. Thick media are treated using a numerical extension of the Gaussian-Laguerre Mode Decomposition technique. Spatial scanning techniques such as the Z-scan that rely on self-focusing e ects and that are used to measure the nonlinear optical parameters of a material are studied in detail. Optical limiting in both thick and thin media is also investigated.
224

Quantitative Line-Scan Thermographic Evaluation of Composite Structures

Kaltmann, Deena, s8907403@student.rmit.edu.au January 2009 (has links)
This MEng (Master of Engineering) research thesis evaluates the capabilities and limitations of line-scan thermography for the non-destructive evaluation of composite structures containing hidden defects. In simple terms, line-scan thermography is a state-of-the-art technique in which a focused line of thermal energy is transmitted into a material. Line-scan thermography has great potential for the rapid and low cost non-destructive inspection of composite structures for aircraft, automobiles and ships. In this project, theoretical research exploring the heat transfer physics was undertaken in conjunction with experimental studies to develop an optimum inspection regime for line-scan thermography. The capability of line-scan thermography to detect impact damage in carbon/epoxy laminates was experimentally investigated in Chapter 3. From the impact side, in all materials, line-scan thermography overestimated the size of the impact damage whereas flash thermography underestimated the size. There was a close relationship between the ultrasonic profile and the line-scan thermographic thermal response curve. New experimental data has been produced and analysed for the ability of line-scan thermography to determine the defect as well as the defect size. It was found that line-scan thermography was able to distinguish back drilled holes, but it was not possible to determine accurate defect sizing due to the depth of the holes from the inspected surface and the limitations associated with the line-scan thermographic apparatus itself. There was excellent correlation between the C-scan ultrasonics intensity curves and the line-scan thermographs as well as excellent correlation with the theoretical results. The relationship between line-scan thermography and foreign body objects were experimentally investigated for carbon/epoxy composites. A major limitation found with line-scan thermography is its limited depth penetration, which is highlighted in the foreign object study using 6 mm and 13 mm diameter Teflon® discs and 13 mm Teflon® strips embedded in carbon/epoxy laminates. Depth penetration allowed only 2 mm resolution for the 13 mm diameter discs and 1.5 mm resolution for the 6 mm discs in a composite panel. The results of the investigation of stainless steel shim objects in carbon/epoxy laminates reveal that line-scan thermography is capable of determining their presence and size close to the surface. There was also excellent correlation between the ultrasonic response curve and the line-scan thermographic intensity curve. The results of the investigation of thermoplastic film foreign body objects in carbon/epoxy laminates show that at present line-scan thermography does not have the capability to determin e such defects. Experimental results show that line-scan thermography is capable of detecting large voids, back drilled holes, some foreign body objects, and impact damage. However, the ability of line-scan thermography to measure the defect dimensions is dependent on the size and type of damage, the distance from the line source, the depth of the defect, and the type of composite material.
225

NONLINEAR SELF-FOCUSING AND BEAM PROPAGATION USING GAUSSIAN LAGUERRE MODE DECOMPOSITION

Dr Rodney Mcduff Unknown Date (has links)
This thesis descibes a theoretical study of nonlinear self-focusing as applied to the metrology of the nonlinear optical parameters of a medium. It also studies the phe- nomenon of optical power limiting which utilizes self-focusing e ects. As an analytical tool, a mode decomposition method which uses an orthogonal and complete set of Gaussian-Laguerre modes as a basis set is used to treat these problems. Nonlinear media both in the thin and thick limits are investigated. For thin media, a closed form expression is derived which describes the optical eld of an initally Gaussian beam that is perturbed by a thin nonlinear material which exhibits nonlinear absorption as well as nonlinear refraction. This result is valid for any regime of nonlinearity in the thin medium approximation. Thick media are treated using a numerical extension of the Gaussian-Laguerre Mode Decomposition technique. Spatial scanning techniques such as the Z-scan that rely on self-focusing e ects and that are used to measure the nonlinear optical parameters of a material are studied in detail. Optical limiting in both thick and thin media is also investigated.
226

Interoperative Struktur- und Geometrieerfassung mittels A-Mode-Ultraschall in der computerunterstützten Chirurgie ein Beitrag aus dem Lehrstuhl für Medizintechnik der RWTH Aachen

Heger, Stefan January 2008 (has links)
Zugl.: Aachen, Techn. Hochsch., Diss., 2008
227

Delay Test Scan Flip-Flop c(DTSFF) design and its applications for scan based delay testing

Xu, Gefu, Singh, Adit D. January 2007 (has links) (PDF)
Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (p.107-111).
228

An investigation into the relationship between static and dynamic gait features : a biometrics perspective

Alawar, Hamad Mansoor Mohd Aqil January 2014 (has links)
Biometrics is a unique physical or behavioral characteristic of a person. This unique attribute, such as fingerprints or gait, can be used for identification or verification purposes. Gait is an emerging biometrics with great potential. Gait recognition is based on recognizing a person by the manner in which they walk. Its potential lays in that it can be captured at a distance and does not require the cooperation of the subject. This advantage makes it a very attractive tool for forensic cases and applications, where it can assist in identifying a suspect when other evidence such as DNA, fingerprints, or a face were not attainable. Gait can be used for recognition in a direct manner when the two samples are shot from similar camera resolution, position, and conditions. Yet in some cases, the only sample available is of an incomplete gait cycle, low resolution, low frame rate, a partially visible subject, or a single static image. Most of these conditions have one thing in common: static measurements. A gait signature is usually formed from a number of dynamic and static features. Static features are physical measurements of height, length, or build; while dynamic features are representations of joint rotations or trajectories. The aim of this thesis is to study the potential of predicting dynamic features from static features. In this thesis, we have created a database that utilizes a 3D laser scanner for capturing accurate shape and volumes of a person, and a motion capture system to accurately record motion data. The first analysis focused on analyzing the correlation between twenty-one 2D static features and eight dynamic features. Eleven pairs of features were regarded as significant with the criterion of a P-value less than 0.05. Other features also showed a strong correlation that indicated the potential of their predictive power. The second analysis focused on 3D static and dynamic features. Through the correlation analysis, 1196 pairs of features were found to be significantly correlated. Based on these results, a linear regression analysis was used to predict a dynamic gait signature. The predictors chosen were based on two adaptive methods that were developed in this thesis: "the top-x" method and the "mixed method". The predictions were assessed for both for their accuracy and their classification potential that would be used for gait recognition. The top results produced a 59.21% mean matching percentile. This result will act as baseline for future research in predicting a dynamic gait signature from static features. The results of this thesis bare potential for applications in biomechanics, biometrics, forensics, and 3D animation.
229

AN EFFICIENT APPROACH TO REDUCE TEST APPLICATION TIME THROUGH LIMITED SHIFT OPERATIONS IN SCAN CHAINS

Kuchi, Jayasurya 01 August 2017 (has links)
Scan Chains in DFT has gained more prominence in recent years due to the increase in the complexity of the sequential circuits. As the test time increases along with the number of memory elements in the circuit, new and improved methods came in to prominence. Even though scan chain increases observability and controllability, a big portion of the time is wasted while shifting in and shifting out the test patterns through the scan chain. This thesis focus on reducing the number of clock cycles that are needed to test the circuit. The proposed Algorithm uses modified shift procedures based on 1) Finding hard to detect faults in the circuit. 2) Productive way to generate test patterns for the combinational blocks in between the flip flops. 3) Rearranging test patterns and changing the shift procedures to achieve fault coverage in reduced number of clock cycles. In this model, the selection process is based on calculating the fault value of a fault and total fault value of the vector which is used to find the hard faults and the order in which the vectors are applied. This method reduces the required number of shifts for detecting the faults and thereby reducing the testing time. This thesis concentrates on appropriate utilization of scan chains for testing the sequential circuits. In this context, the proposed method shows promising results in reduction of the number of shifts, thereby reducing the test time. The experimental results are based on the widely cited ISCAS 89 benchmark circuits.
230

Holographic Metasurface Leaky Wave Antennas

January 2017 (has links)
abstract: Articially engineered two-dimensional materials, which are widely known as metasurfaces, are employed as ground planes in various antenna applications. Due to their nature to exhibit desirable electromagnetic behavior, they are also used to design waveguiding structures, absorbers, frequency selective surfaces, angular-independent surfaces, etc. Metasurfaces usually consist of electrically small conductive planar patches arranged in a periodic array on a dielectric covered ground plane. Holographic Articial Impedance Surfaces (HAISs) are one such metasurfaces that are capable of forming a pencil beam in a desired direction, when excited with surface waves. HAISs are inhomogeneous surfaces that are designed by modulating its surface impedance. This surface impedance modulation creates a periodical discontinuity that enables a part of the surface waves to leak out into the free space leading to far-eld radia- tion. The surface impedance modulation is based on the holographic principle. This dissertation is concentrated on designing HAISs with Desired polarization for the pencil beam Enhanced bandwidth Frequency scanning Conformity to curved surfaces HAIS designs considered in this work include both one and two dimensional mod- ulations. All the designs and analyses are supported by mathematical models and HFSS simulations. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017

Page generated in 0.0349 seconds