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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.
51

Grain Reduction in Scanned Image Sequences under Time Constraints

Stuhr, Lina January 2009 (has links)
<p>This thesis is about improving the image quality of image sequences scanned by the film scanner GoldenEye. Film grain is often seen as an artistic effect in film sequences but scanned images can be more grainy or noisy than the intention. To remove the grain and noise as well as sharpen the images a few known image enhancement methods have been implemented, tested and evaluated. An own idea of a thresholding method using the dyadic wavelet transform has also been tested. As benchmark has MATLAB been used but one method has also been implemented in C/C++. Some of the methods works satisfactory when it comes to the image result but none of the methods works satisfactory when it comes to time consumption. To solve that a few speed up ideas are suggested in the end of the thesis. A method to correct the color of the sequences has also been suggested.</p>
52

Pipe and Ductwork Progress Tracking using 3D Sensing Technologies

Guillemet, Adrien 24 April 2012 (has links)
Automated construction progress tracking is becoming critical to efficient and effective construction management. More and more construction companies are putting aside the old way of tracking progress, which was mainly based on foremen daily reports and visual inspections, and are adopting 3D sensing technologies as a new and modern way of tracking progress. Technologies such as 3D laser scanners (LADARs) are investigated as a means to acquire comprehensive 3D point-cloud data which can then be studied by management to determine the progress of construction. Although being much more accurate and efficient than visual inspections, this new progress tracking approach can be improved by applying object recognition algorithms that enable an automated progress tracking. This new approach has been investigated by other researchers, but only for progress tracking of structural elements. This study focuses on mechanical objects such as pipes and ducts, which would give the progress tracking a better level of detail and a wider scope. The investigation is carried out on a field database acquired during the construction of the Engineering VI Building at the University of Waterloo. It was found that the laser scanning technology is a suitable method for acquiring point-clouds of pipes and ductwork, and also that the object recognition algorithm used in this study allows a progress tracking as well as a quality tracking of the HVAC system installation.
53

Design of Mission Controller for Autonomous Underwater Vehicle

Lin, Yu-Ren 04 December 2012 (has links)
The different between Remotely Operated Vehicle (ROV) and Autonomous Underwater Vehicle (AUV) is that ROV is connected with the main computer by the electronic cable, so the operator can control the vehicle depending on the environment showing on the monitor; However, AUV is dependent on the received data to autonomously respond the condition via controlling program. In our research, we wanted to use the General Purpose Controller, which had been developed in the previous experiment, in the mission-mode to construct our AUV system for remaining the original ROV controlling system and switching mode between AUV system and ROV system. The mission was divided into primary and secondary mission written by the txt file which is known as mission script, including execute time, target, and mission type etc. In addition, we used the Watch Dog Timer (WDT) in our AUV for the security procedure. When the mission is failed or over the setting time, the AUV will change to the security mode and go forward to the water surface. The other topic in this research wanted to use the Seafloor Laser Scanner (SLS), which was mounted on the AUV, to improve the scanning efficiency. However, when the scanner was working, the AUV had to maintain the stable altitude to the sea floor, so the accurately output power of thruster is needed to be considered and tested. In this part, we found out the properly controlling way in the small water tank first, and then checked the attitude and scanning system in the swimmer pool and towing tank in NCKU respectively, to prove the ability of SLS of AUV system.
54

Development of Post-Processing Software for Seabed Roughness Laser Scanner

Chen, Po-Chi 13 July 2006 (has links)
This work reports the system integration of the underwater seafloor laser scanner, designed and fabricated by Institute of Undersea Technology, National Sun Yat-sen University, with the in situ porosity measurement system, known as IMP2, developed by Applied Physics Lab, University of Washington. Our original prototype underwater seafloor laser scanner worked more like an indoor experimental setup rather than an instrument. It is the goal of this work to modify the detail design of hardware and software of the system such that the operation of the scanner and the data analysis of the results can be done like a commercial instrument. Our laser scanning module adopts structural light method with a single camera approach. The calibration of the camera is achieved with a template board on which sets of grid points are laid with numerical control milling machine. These grid points are used to create longitudinal and latitudinal lines for pixel-to-coordinate conversion. Three sub-pixel sampling methods, namely, intensity weighted centroid, second order polynomial intensity fitting and Gaussian intensity fitting, are developed to locate the center of the laser light strip on pixel plane and to be converted into engineering coordinates. For the convenience of post-processing, grid point meshing and spectrum analysis packages are built-in to provide standard output for further studies. The overall performance of the system was validated by four tests in indoor tanks and field as well. One scanning in air was undertaken to verify if synchronization signal between the laser scanner and the motion of the linear track was correct; several models of known dimension were placed in the water tank for scanning to see if the system reaches the desired accuracy; an integration of the laser scanner and the IMP2 was tested prior to the deployment in the sea, and a scanning a artificial seafloor model of known spatial spectra indicated the proper functioning of the combined system; finally a successful 20-meter deep field deployment and retrieve assured the bases for the acquisition of seafloor roughness field for acoustics related research.
55

Code Automation for Vulnerability Scanner

Wu, Ching-Chang 06 July 2003 (has links)
With enormous vulnerability discovered and Internet prevailing in the word, users confront with the more dangerous environment. As a result, the users have to understand the system risk necessarily. The vulnerability scanner provides the functionality that could check if the system is vulnerable. Nessus is a vulnerability scanner. It provides the customization capability that users could defined the security check. It develops a attack language called NASL. By use of NASL, users could write the security check by themselves. But before writing the security check, the users must know the architecture of Nessus and study how to write the security check by NASL. Different vulnerabilities have different the detection approach and communications method. If users don't know about above knowledge, they couldn¡¦t write the security check. In this research, we develop a automatic mechanism of generating code for the Nessus scanner and produce a security check. And we also provide two approaches to produce the security check. The one is the modularization. It takes part of function codes into a module, and combines the modules into a security check. The other one is package. The users can't involve the attack code and just only fill in some of parameters to produce the security check. This research proposes the design above and actually implements a system to generate attack codes. It attempts to decrease the needs of knowledge to users about security check, reduce the error rates by human typos, and enhance the efficiency and correctness for writing the security check
56

Automatisierte Installation von Geräten in Windows XP

Brose, Steffen 10 May 2004 (has links)
Workshop "Netz- und Service-Infrastrukturen" Beschreibung und Bewertung systemeigener Verfahren zur automatisierten Installation von Druckern und Scannern unter Windows XP, daraus Ableitung und Beschreibung der im XP-Administrationsdienst praktizierten Verfahren.
57

REDUCING ACOUSTIC NOISE IN MRI SCANNERS

Li, Gemin 15 November 2010 (has links)
A study of methods for reducing the acoustic noise in magnetic resonance imaging (MRI) scanners is presented in this thesis. The structural-acoustic coupling mechanism of MRI scanners was investigated using a method of structural-acoustic modal analysis. Mathematical expressions of generalized radiation impedances of gradient coil ducts with perforated panel inserts were developed and the effects of the perforated panel inserts on the acoustic noise in the duct were discussed. The possibility of using micro-perforated panel (MPP) absorbers in MRI scanners to reduce the acoustic noise was then investigated through analytical and computational modeling. A comprehensive experimental study was conducted after the analytical and computational investigation. Finally, design methods and procedures were developed specifically for the MPP absorbers in MRI scanners. Design considerations and recommendations were given as well. Several major conclusions can be made from this research. Firstly, the method of structural-acoustic modal analysis is effective for finding the structural-acoustic coupling modes which should be avoided in the design of MRI scanners. Secondly, a perforated panel insert produces significant effects on the radiation impedance of gradient coil ducts and MRI scanner bores. This attribute partly contributes to its capability of reducing the acoustic noise in a duct. Thirdly, the effectiveness of MPP absorbers in MRI scanners can be accurately predicted using a combination of theoretical analysis and computational modeling. Moreover, it has been proved that well designed MPP absorbers are effective in reducing the acoustic noise in MRI scanners. Lastly, the presented design methods and recommendations for the MPP absorbers can be relatively easily used by MRI designers or engineers to tackle the acoustic noise problem in MRI scanners. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2010-07-13 11:46:03.585
58

Validation of 3D Surface Measurements Using Computed Tomography

MORTON, AMY 10 January 2012 (has links)
Objective and accurate surface measurements are important in many clinical disciplines. Non-irradiating and low cost alternatives are available but validation of these measurement tools for clinical application is variable and sparse. This thesis presents a three dimensional (3D) surface measurement method validated by gold standard Computed Tomography (CT). Forty-one 3D surface data sets were acquired by two modalities, a laser scanner and a binocular camera. The binocular camera was tested with three different texture modifiers that increased the colour variability of the imaged surface. A surface area calculation algorithm was created to process the data sets. Relative differences were calculated for each area measurement with respect to its corresponding CT measurement. The laser scanner data sets were affected by movement and specular reflection artefacts. The measurements were statistically equivalent to CT if less than 20% error were considered acceptable. The binocular camera with the slide projected texture modifier was shown to be statistically equivalent to CT gold standard with less than 5% error (p < 0.0005). The surface area measurement method can easily be expanded and customized. By following the protocol outlined by the example in this work, researchers and clinicians would also be able to objectively asses other vision systems' performance and suitability. / Thesis (Master, Computing) -- Queen's University, 2012-01-10 11:37:50.374
59

Pipe and Ductwork Progress Tracking using 3D Sensing Technologies

Guillemet, Adrien 24 April 2012 (has links)
Automated construction progress tracking is becoming critical to efficient and effective construction management. More and more construction companies are putting aside the old way of tracking progress, which was mainly based on foremen daily reports and visual inspections, and are adopting 3D sensing technologies as a new and modern way of tracking progress. Technologies such as 3D laser scanners (LADARs) are investigated as a means to acquire comprehensive 3D point-cloud data which can then be studied by management to determine the progress of construction. Although being much more accurate and efficient than visual inspections, this new progress tracking approach can be improved by applying object recognition algorithms that enable an automated progress tracking. This new approach has been investigated by other researchers, but only for progress tracking of structural elements. This study focuses on mechanical objects such as pipes and ducts, which would give the progress tracking a better level of detail and a wider scope. The investigation is carried out on a field database acquired during the construction of the Engineering VI Building at the University of Waterloo. It was found that the laser scanning technology is a suitable method for acquiring point-clouds of pipes and ductwork, and also that the object recognition algorithm used in this study allows a progress tracking as well as a quality tracking of the HVAC system installation.
60

High performance micro scanners for miniature laser projection displays

Hsu, Shu-Ting January 2009 (has links)
Zugl.: Dresden, Techn. Univ., Diss., 2009

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