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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

Analysis And Comparison Of The Contrast Enhancement Techniques For Infrared Images

Turan, Arif Ergun 01 February 2012 (has links) (PDF)
Today, infrared cameras are used especially for target tracking and surveillance operations. However, they have a high dynamic range output, and the standard display devices cannot handle them. In order to show them on common devices, the dynamic range is cropped. Thus, the contrast of the image is reduced. This is called as the High Dynamic Range (HDR) Compression. Although several algorithms have been proposed for preserving details during the HDR compression process, it cannot be used to enhance the local contrasts of image contents. In this thesis, we compare the performances of contrast enhancement techniques, which are suitable for real time applications. The methods experimented are generally histogram based methods. Some modifications are also proposed in order to reduce computational complexity of the process. Performances of these methods are compared with common objective quality metrics on different image sets.
22

Terrain Modeling And Atmospheric Turbulent Flowsolutions Based On Meteorological Weather Forecast Data

Leblebici, Engin 01 February 2012 (has links) (PDF)
In this study, atmospheric and turbulent flow solutions are obtained using meteorological flowfield and topographical terrain data in high resolution. The terrain topology of interest, which may be obtained in various resolution levels, is accurately modeled using structured or unstructured grids depending on whether high-rise building models are present or not. Meteorological weather prediction software MM5, is used to provide accurate and unsteady boundary conditions for the solution domain. Unsteady turbulent flow solutions are carried out via FLUENT with the help of several User Defined Functions developed. Unsteady flow solutions over topographical terrain of METU campus are computed with 25m x 25m x 15m resolution using structured grids. These FLUENT solutions are compared with the MM5 solutions. Also, the accuracy of the boundary layer velocity profiles is assessed. Finally, effects of surface roughness model extracted from MM5 for the region of interest is investigated. In addition, unsteady flow solutions over METU campus are repeated in presence of high-rise building models using unstructured grids with resolution varying from 5 meters around buildings to 80 meters further away. The study shows that unsteady, turbulent flow solutions can be accurately obtained using low resolution atmospheric weather prediction models and high resolution Navier-Stokes solutions over topographical terrains.
23

A Workflow Based Online Software Review System

Cifci, Hasan 01 July 2004 (has links) (PDF)
Software review is an effective and efficient way for detecting defects in software artifacts. To improve the effectiveness and the efficiency of software review, a variety of software review techniques have been developed. Furthermore, computer support has been used to facilitate the software review process. Accordingly, several software review tools have been developed. Although existing tools provide new solutions to support software review, in general they suffer from a number of shortcomings. In this study, a brief description about major software review techniques is given along with the summary of the process. Additionally, existing tools and their features are briefly explained and a comparison between them is done. This study focuses on the development of a Web based review tool that has a workflow definition capability in order to support every kind of software review processes.
24

A Geographical Information System Application For Ambulance Routing Services:a Prototype

Gulden, Birsen 01 July 2004 (has links) (PDF)
In public safety, geography plays a significant role. One of the most important front-line elements of public safety is an efficient emergency transport and care system. The capacity to access and process information rapidly and organize resources where needed can be critically important in an emergency situation. Information about the locality of an event or a disaster is often vital in knowing how to respond. A significant operation in handling emergency situations is the routing of ambulances to incident sites and then to the closest appropriate hospitals. One of the important steps to survival in an emergency is quick response time. The aim of this thesis study is to build an immediate, rapid and efficient emergency medical transport system prototype, called Ambulance Routing Service Application Prototype (ARSAP), to be used in Middle East Technical University (METU) Emergency Service, Ankara, Turkey. In the study, geographical information systems (GIS) technology is used in assisting the development and implementation of an emergency medical service (EMS) response system. In this prototype, while choosing a proper facility, the available quantity of beds, respiratory equipments and doctors in a hospital&#039 / s intensive care room and the best traffic routes to the hospital in hand are also considered. The ARSAP is expected to shorten the commuting time and hence to reduce the damage to the patient to the lowest level and allow the ambulance staff to perform their task better. The results generated using the ARSAP are validated and analyzed by comparing with currently practiced emergency call paths data collected with the help of METU Emergency Service ambulance drivers.
25

Numerical Investigation Of Rotor Wake-stator Interaction

Gurak, Derya 01 October 2004 (has links) (PDF)
iv In this thesis, numerical solutions of a 2D stator compressor cascade at a given inlet Mach number (0.7) and four values of incidence (49&deg / , 51&deg / , 53&deg / and 55&deg / ) are obtained. Reynolds averaged, thin layer, compressible Navier Stokes equations are solved. Different grid types have been generated. Finite differencing approach and LU - ADI splitting technique are used. Three block parallel Euler and Navier Stokes solutions are compared with the experimental results. Baldwin-Lomax turbulence model is used in the turbulent predictions and boundary layer comparisons and numerical results are in good agreement with the experiment. On the last part of the study, a rotor wake in the inlet flow has been introduced in the steady and unsteady analyses. The influence of this wake and the wake location in the inlet flow, to the total force and pressure is presented. The results have been showed that there is a relationship between the wake position and the incidence value of the case.
26

The Tool Transporter Movements Problem In Flexible Manufacturing Systems

Kilinc, Fatma 01 April 2005 (has links) (PDF)
In this study, we address job sequencing and tool switching problem arising in Flexible Manufacturing Systems. We consider a single machine with limited tool slots on its tool magazine. The available tool slots cannot accommodate all the tools required by all jobs, therefore tool switches between jobs are required. A single tool transporter with limited capacity is used in transporting the tools from the storage area to the machine. Our aim is to minimize the number of tool transporter movements. We provide two mixed integer linear programming formulations of the problem, one of which is based on the traveling salesman problem. We develop a Branch-and-Bound algorithm powered with various lower and upper bounding techniques for optimal results. In order to obtain good solutions in reasonable times, we propose Beam Search algorithms. Our computational results reveal the satisfactory performance of the B&amp / B algorithm for moderate sized problems. Moreover, Beam Search techniques perform well for large-sized problems.
27

Mechanical Characterization Of Filament Wound Composite Tubes By Internal Pressure Testing

Karpuz, Pinar 01 May 2005 (has links) (PDF)
The aim of this study is to determine the mechanical characteristics of the filament wound composite tubes working under internal pressure loads, generating data for further investigation with a view of estimating the remaining life cycle of the tubes during service. Data is generated experimentally by measuring the mechanical behavior like strains in hoop direction, maximum hoop stresses that are formed during internal pressure loading. Results have been used to identify and generate the necessary data to be adopted in the design applications. In order to determine these parameters, internal pressure tests are done on the filament wound composite tube specimens according to ASTM D 1599-99 standard. The test tubes are manufactured by wet filament winding method, employing two different fiber types, two different fiber tension settings and five different winding angle configurations. The internal pressure test results of these specimens are studied in order to determine the mechanical characteristics, and the effects of the production variables on the behavior of the tubes. Pressure tests revealed that the carbon fiber reinforced composite tubes exhibited a better burst performance compared to the glass fiber reinforced tubes, and the maximum burst performance is achieved at a winding angle configuration of [&plusmn / 54&deg / ]3[90&deg / ]1. In addition, the tension setting is found not to have a significant effect on the burst performance. The burst pressure data and the final failure modes are compared with the results of the ASME Boiler and Pressure Vessel Code laminate analysis, and it was observed that there is a good agreement between the laminate analysis results and the experimental data. The stress &ndash / strain behavior in hoop direction are also studied and hoop elastic constants are determined for the tubes.
28

Developing A Gis Based Methodology For Decision Making For Multiobjective Recreational Areas, Case Study : Eastern Black Sea Region

Kaya, Zehra Gozde 01 May 2006 (has links) (PDF)
In this study, a method is proposed for decision making for multiobjective recreational areas, by using multi attribute decision making rules within GIS. The method provides integration of ecological, sociocultural and economic considerations of an ecologically valuable area in a systematic way. The first stage of the methodology includes determination of suitable areas for three usages of forest area / outdoor recreation, timber production and protection needed areas. The second stage comprises decision making analyses. In this stage, two of multi attribute decision rule methods / simple additive weighting method and ideal point method, are used. As a result of these analyses alternative proposal maps for study area and ideal areas for recreation and timber production are acquired. Finally, in the third stage these alternative proposal maps and ideal area are compared with each other and with defined protection zone in the study area. Ideal areas for recreation and timber production are defined by also considering the protection needed areas. The methodology is applied on Eastern Black Sea Region. As a result of the study, ideal areas both for recreational usage and timber production are defined. According to these ideal areas, best fitting alternative map is selected. Finally recreation and timber production proposals are compared with protection needed areas. Results of this study provide a general decision for multipurposed areas in regional scale. The suggested protection zones and suitable areas for recreation and timber production should provide a primary information for forest management studies which must be done in more detailed scales.
29

A Hybrid Approach For Full Frame Loss Concealment Of Multiview Video

Bilen, Cagdas 01 August 2007 (has links) (PDF)
Multiview video is one of the emerging research areas especially among the video coding community. Transmission of multiview video over an error prone network is possible with efficient compression of these videos. But along with the studies for efficiently compressing the multiview video, new error concealment and error protection methods are also necessary to overcome the problems due to erroneous channel conditions in practical applications. In packet switching networks, packet losses may lead to block losses in a frame or the loss of an entire frame in an encoded video sequence. In recent years several algorithms are proposed to handle the loss of an entire frame efficiently. However methods for full frame losses in stereoscopic or multiview videos are limited in the literature. In this thesis a stereoscopic approach for full frame loss concealment of multiview video is proposed. In the proposed methods, the redundancy and disparity between the views and motion information between the previously decoded frames are used to estimate the lost frame. Even though multiview video can be composed of more than two views, at most three view are utilized for concealment. The performance of the proposed algorithms are tested against monoscopic methods and the conditions under which the proposed methods are superior are investigated. The proposed algorithms are applied to both stereoscopic and multiview video.
30

Offshore Oil Slick Detection With Remote Sensing Techniques

Akar, Sertac 01 September 2007 (has links) (PDF)
The aim of this thesis is to develop a methodology for detection of naturally occurring offshore oil slicks originating from hydrocarbon seeps using satellite remote sensing techniques. In this scope, Synthetic Aperture Radar (SAR) imagery has been utilized. Case study area was Andrusov High in the Central Black Sea. Hydrocarbon seepage from tectonic or stratigraphic origin at the sea floor causes oily gas plumes to rise up to the sea surface. They form thin oil films on the sea surface called oil slicks. Presence of seeps and surface oil slicks for the offshore basins is a trace of depleted oil traps. Spatial distribution of oil slicks is closely related to sea waves, dominant wind patterns and weathering factors. Even though, there are oil slick detection techniques available with optical remote sensing, laser fluorosensors, and hyperspectral remote sensing, the most efficient results can be obtained from active microwave sensors like synthetic aperture radar (SAR). SAR sensors simply measure the backscattered radiation from the surface and show the roughness of the terrain. Oil slicks dampen the sea waves creating dark patches in the SAR image. In this context an adapted methodology has been proposed, including three levels namely / visual inspection, image filtering and object based fuzzy classification. With visual inspection, targets have been identified and subset scenes have been created. Subset scenes have been categorized into 3 cases based on contrast difference of dark spots to the surroundings. Then object based classification has been utilized with the fuzzy membership functions defined by extracted features of layer values, shape and texture from segmented and filtered SAR subsets. As a result, oil slicks have been discriminated from look-alikes which are the phenomena resembling oil slicks. The overall classification accuracy obtained by averaging three different cases is 83 % for oil slicks and 77 % for look-alikes. The results of this study can considered to be a preliminary work and supplementary information for determining the best operational procedure of offshore hydrocarbon exploration.

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