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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

Template Based Image Watermarking In The Fractional Fourier Domain

Gokozan, Tolga 01 February 2005 (has links) (PDF)
One of the main features of digital technology is that the digital media can be duplicated and reproduced easily. However, this allows unauthorized and illegal use of information, i.e. data piracy. To protect digital media against illegal attempts a signal, called watermark, is embedded into the multimedia data in a robust and invisible manner. A watermark is a short sequence of information, which contains owner&rsquo / s identity. It is used for evidence of ownership and copyright purposes. In this thesis, we use fractional Fourier transformation (FrFT) domain, which combines space and spatial frequency domains, for watermark embedding and implement well-known secure spread spectrum watermarking approach. However, the spread spectrum watermarking scheme is fragile against geometrical attacks such as rotation and scaling. To gain robustness against geometrical attacks, an invisible template is inserted into the watermarked image in Fourier transformation domain. The template contains no information in itself but it is used to detect the transformations undergone by the image. Once the template is detected, these transformations are inverted and the watermark signal is decoded. Watermark embedding is performed by considering the masking characteristics of the Human Visual System, to ensure the watermark invisibility. In addition, we implement watermarking algorithms, which use different transformation domains such as discrete cosine transformation domain, discrete Fourier transformation domain and discrete wavelet transformation domain for watermark embedding. The performance of these algorithms and the FrFT domain watermarking scheme is experimented against various attacks and distortions, and their robustness are compared.
22

Instrumented Monitoring And Dynamic Testing Of Metu Cable Stayed Pedestrian Bridge And Comparisons Against The Analytical Model Simulations

Ozerkan, Taner 01 July 2005 (has links) (PDF)
This study includes structural instrumentation and monitoring of a 48.5 meters long cable-stayed pedestrian bridge located on EskiSehir road near METU campus. The objectives of the study are (1) to monitor the bridge responses during erection and operation stages so that the strain changes are determined during important events such as transportation, lifting, cabling, mid-support removal, slab concrete pouring and tile placement, (2) to determine existing cable forces using vibration frequencies, and (3) comparison of the experimental and analytical results for model updating. A total of 10 vibrating wire type strain gages were used for strain readings in steel members. The readings are taken at various stages of construction at every 10 to 30 minutes intervals. The bridge responses were monitored about three months and large strain changes in the order of 300 to 500 micro-strain were recorded during important events (e.g., transportation, lifting, cabling, mid-support removal, deck cover placement). The deck and tower natural vibration frequency measurements are conducted in two main directions. Two different FE models are constructed using two levels of complexity. FEM analysis results are compared against measured natural frequencies of the bridge and tower. Simplistic analytical model is modified to include temporary support removal in order to perform staged construction simulation and investigate cable force variations. Actual cable tensile forces are obtained using measured cable natural vibration frequencies. The cable frequencies are measured using a CR10X data logger and a PCB 393C accelerometer. Existing cable forces are compared against analytical simulations and symmetrically placed cables
23

Bezdrátový zvonek s digitálním přenosem hlasu / Wireless doorbell with voice transmission

Papež, Josef January 2008 (has links)
This diploma thesis deals with wireless doorbell realisation. The doorbell is battery-powered and supports half duplex voice transferring. The general aim is to design system circuitry, PCB and to create microcontroller firmware.
24

Lokalisering av skidor i lössnö : Självständigt arbete i Teknisk Fysik / Positioning of skis in powder snow : Independent Project in Engineering Physics

Trella, Fredrik January 2011 (has links)
This report studies the possibility of using some sort of radio sender and transmitter in order to position skis lost in powder snow. It is concluded that a RF-solution on the 433 MHz frequency should be the most efficient. Different forms of directional antennas are examined and studies show that in theory the best suited is the so called “Yagi-Uda antenna”. A solution based on using a Receive Signal Strength Indicator value together with the above mentioned directional antenna is developed. To control these different components microprocessors from Atmel is used. These are programmed in C and compiled with Atmel’s own compiler AVR Studio. Despite all efforts it is proven that the prototype does not perform in an adequate way. An alternative solution based on “byte-loss-rate” is then developed and the results are slightly improved. Nevertheless, the directional properties of the antenna are still too poor why other alternatives are discussed. No fully functioning prototype is achieved but good grounds for further development of the prototype into something that fulfills the specifications are produced.
25

Robotique coopérative aéro-terrestre : Localisation et cartographie hétérogène / Air-ground cooperation : Navigation and heterogeneous mapping

Renaudeau, Brice 07 March 2019 (has links)
Les travaux de cette thèse adressent la problématique de la coopération aéro-terrestre pour la cartographie de l’espace navigable. La nécessité d’une carte pour la navigation et la planification de chemins pour les robots terrestres n’est plus à prouver. L’utilisation d’une coopération aéro-terrestre pour créer une carte navigable à destination du robot terrestre a plusieurs intérêts. Premièrement, le drone peut cartographier rapidement une zone grâce à son champ de vision étendu et ses capacités de déplacement. Deuxièmement, la fusion des cartes créées par ces deux agents permet de tirer le meilleur profit des deux points de vue : la cohérence de la vue aérienne globale et la précision de la vue terrestre locale. Pour répondre à cette problématique, nous proposons une méthode qui s’appuie sur la création de cartes hybrides et leur fusion. Les cartes sont construites en utilisant le squelette de l’espace navigable terrestre comme support d’un graphe contenant également des informations métriques locales de l’environnement. La mise en correspondance des cartes aérienne et terrestre s’effectue à l’aide d’un appariement point à point déterminé grâce à une mesure de dissimilarité appropriée. Cette dernière est définie pour répondre aux critères d’invariance et de discriminance dans ce contexte. La mise en correspondance est ensuite utilisée pour fusionner les cartes entre elles. Les cartes fusionnées peuvent être utilisées par le robot au sol pour effectuer sa mission. Elles permettent également de propager des informations telles que des coordonnées GPS à des robots et dans des lieux où ce dispositif n’est pas disponible. Des expérimentations en environnements virtuels et réels sont réalisées pour valider cette approche et en tracer les perspectives. / This work aims to study the problem of air-ground robotic cooperation for collaborative traversability mapping. The need for a map for navigation and path planning for terrestrial robots is no longer to be proven. The use of air-ground cooperation to create a navigable map for the ground robots has several interests. First, the drone can quickly map an area through its large field of vision and traveling capabilities. Second, the fusion of maps based on these two agents makes it possible to draw the best benefits from both points of views: the coherence of the global aerial view and the accuracy of the local ground view. To answer this problem, we propose a method that relies on the construction of a unified model of hybrid maps and their fusion.The maps are built using the skeleton of the traversability space as a support for graphs also containing local metric and potentialy semantic information of the environment. The maching of aerial and ground maps is done using a point to point correlation based on an appropriate dissimilarity measure. This measure is defined to meet invariance and discriminance criteria. The matching is then used to merge the maps into an augmented traversability map. The merged maps can be used by the ground robot to perform its mission. They also make it possible to deploy information such as GPS coordinates to robots in GPS denied environments. Experiments in virtual and real world environments have been carried out to validate this approach and map out future perspetives.
26

一傍詩史 : 謝靈運詩楚辭典故硏究 = A study on literary quotation of Chu Ci in the poetry of Xie Ling-yun

簡漢乾, 01 January 2002 (has links)
No description available.
27

Predicting The Disease Of Alzheimer (ad) With Snp Biomarkers And Clinical Data Based Decision Support System Using Data Mining Classification Approaches

Erdogan, Onur 01 September 2012 (has links) (PDF)
Single Nucleotide Polymorphisms (SNPs) are the most common DNA sequence variations where only a single nucleotide (A, T, C, G) in the human genome differs between individuals. Besides being the main genetic reason behind individual phenotypic differences, SNP variations have the potential to exploit the molecular basis of many complex diseases. Association of SNPs subset with diseases and analysis of the genotyping data with clinical findings will provide practical and affordable methodologies for the prediction of diseases in clinical settings. So, there is a need to determine the SNP subsets and patients&rsquo / clinical data which is informative for the prediction or the diagnosis of the particular diseases. So far, there is no established approach for selecting the representative SNP subset and patients&rsquo / clinical data, and data mining methodology that is based on finding hidden and key patterns over huge databases. This approach have the highest potential for extracting the knowledge from genomic datasets and to select the number of SNPs and most effective clinical features for diseases that are informative and relevant for clinical diagnosis. In this study we have applied one of the widely used data mining classification methodology: &ldquo / decision tree&rdquo / for associating the SNP Biomarkers and clinical data with the Alzheimer&rsquo / s disease (AD), which is the most common form of &ldquo / dementia&rdquo / . Different tree construction parameters have been compared for the optimization, and the most efficient and accurate tree for predicting the AD is presented.
28

Data Envelopment Analysis And Malmquist Total Factor Productivity (tfp) Index: An Application To Turkish Automotive Industry

Karaduman, Alper 01 September 2006 (has links) (PDF)
This thesis shows how the relative efficiency of automotive companies can be evaluated and how the changes in productivity of these companies by time can be observed. There are 17 companies in the analysis which are the main automotive manufacturers of Turkish automotive industry. A method called stepwise approach is used to determine the input and output factors. The two input variables used are the company&rsquo / s Payment for Raw Materials and Components and Payment for Wages and Insurances of Employees / the three output variables are Domestic Sales, Exports and Capacity Usage. The panel data that covers the time period between years 2001 and 2005 is obtained from OSD (Automotive Manufacturers Association). The efficiency analysis is performed according to basic Data Envelopment Analysis (DEA) models which are Charnes, Cooper and Rhodes (CCR) models and Banker, Charnes and Cooper (BCC) models. The software LINGO 10 is used for solving the linear programming models. After finding the overall efficiency, technical efficiency and scale efficiency of each company for each year, the changes in the efficiencies are analyzed by using Malmquist Total Factor Productivity (TFP) Index. The results are illustrated by the help of many tables and graphs for better understanding. When the results in tables and graphs are analyzed, the negative effect of 2001 economic crisis on automotive industry can be observed. Besides, it is seen that the efficiency changes by time show variance from company to company because they produce 7 types of vehicles and there are important differences between them such as production technology, market, demand, etc.
29

A Method For Robust Design Of Products Or Processes With Categorical Response

Erdural, Serkan 01 December 2006 (has links) (PDF)
In industrial processes decreasing variation is very important while achieving the targets. For manufacturers, finding out optimal settings of product and process parameters that are capable of producing desired results under great conditions is crucial. In most cases, the quality response is measured on a continuous scale. However, in some cases, the desired quality response may be qualitative (categorical). There are many effective methods to design robust products/process through industrial experimentation when the response variable is continuous. But methods proposed so far in the literature for robust design with categorical response variables have various limitations. This study offers a simple and effective method for the analysis of categorical response data for robust product or process design. This method handles both location and dispersion effects to explore robust settings in an effective way. The method is illustrated on two cases: A foam molding process design and an iron-casting process design.
30

Weapon-target Allocation And Scheduling For Air Defense With Time Varying Hit Probabilities

Gulez, Taner 01 June 2007 (has links) (PDF)
In this thesis, mathematical modeling and heuristic approaches are developed for surface-to-air weapon-target allocation problem with time varying single shot hit probabilities (SSHP) against linearly approaching threats. First, a nonlinear mathematical model for the problem is formulated to maximize sum of the weighted survival probabilities of assets to be defended. Next, nonlinear objective function and constraints are linearized. Time varying SSHP values are approximated with appropriate closed forms and adapted to the linear model obtained. This model is tested on different scenarios and results are compared with those of the original nonlinear model. It is observed that the linear model is solved much faster than the nonlinear model and produces reasonably good solutions. It is inferred from the solutions of both models that engagements should be made as late as possible, when the threats are closer to the weapons, to have SSHP values higher. A construction heuristic is developed based on this scheme. An improvement heuristic that uses the solution of the construction heuristic is also proposed. Finally, all methods are tested on forty defense scenarios. Two fastest solution methods, the linear model and the construction heuristic, are compared on a large scenario and proposed as appropriate solution techniques for the weapon-target allocation problems.

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