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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.
381

Building and Evaluating a 3D Scanning System for Measurementsand Estimation of Antennas and Propagation Channels

Aagaard Fransson, Erik Johannes, Wall-Horgen, Tobias January 2012 (has links)
Wireless communications rely, among other things, on theunderstanding of the properties of the radio propagationchannel, the antennas and their interplay. Adequate measurementsare required to verify theoretical models and togain knowledge of the channel behavior and antenna performance.As a result of this master thesis we built a 3D fieldscanner measurement system to predict multipath propagationand to measure antenna characteristics. The 3Dscanner allows measuring a signal at the point of interestalong a line, on a surface or within a volume in space. In orderto evaluate the system, we have performed narrowbandchannel sounding measurements of the spatial distributionof waves impinging at an imaginary spherical sector. Datawas used to estimate the Angle-of-Arrivals (AoA) and amplitudeof the waves. An estimation method is presented tosolve the resulting inverse problem by means of regularizationwith truncated singular value decomposition. The regularizedsolution was then further improved with the helpof a successive interference cancellation algorithm. Beforeapplying the method to measurement data, it was testedon synthetic data to evaluate its performance as a functionof the noise level and the number of impinging waves. Inorder to minimize estimation errors it was also required tofind the phase center of the horn antenna used in the channelmeasurements. The task was accomplished by directmeasurements and by the regularization method, both resultsbeing in good agreement.
382

Rekonstrukce 3D objektu z obrazových dat / 3D Objects Reconstruction from Image Data

Cír, Filip January 2008 (has links)
This paper deals with 3D reconstruction of objects from image data. There is describes theoretical basis of the 3D optical scanning. Handheld 3D optical scanner setup is described composed of a single camera and a line laser whose position is fixed with respect to the camera. Set of image markers and a simple real-time detection algorithm are proposed. Detected markers are used to estimate position and orientation of the camera. Finally, laser detection and triangulation of points lying on object surface are discussed.
383

Kalibrace snímačů pro multispektrální datovou fúzi v mobilní robotice / Sensor Calibration for Multispectral Data Fusion in Mobile Robotics

Kalvodová, Petra January 2015 (has links)
Thesis deals with data fusion and calibration of sensory system of Orpheus-X3 robot and EnvMap mapping robot. These robots are parts of Cassandra robotic system that is used for exploration of hazardous or inaccessible areas. Corrections of measured distances are determined for used laser scanners Velodyne HDL-64, Velodyne HDL-32 and range camera SwissRanger SR4000. Software MultiSensCalib has been created and is described. This software is used for determination of intrinsic parameters of heterogeneous cameras of the sensory head and for determination of mutual position and orientation of these sensors. Algorithm for data fusion of CCD camera stereo pair, thermal imager stereo pair and range camera is proposed. Achieved calibration and data-fusion parameters are evaluated by several experiments.
384

Contribution à la validation d’un outil informatique pour l’évaluation des surfaces corporelles brûlées

Matei, Svetlana 08 1900 (has links)
INTRODUCTION L’évaluation de la surface corporelle brûlée, essentielle pour établir la réanimation volémique et statuer sur le pronostic, se base actuellement sur la transposition des brûlures observées sur des diagrammes en papier représentant des mannequins standard. Le but de ce projet est de contribuer à la validation d’un outil pour l’évaluation des ratios brûlés. Deux outils ont été proposés, un numériseur portable et les mesures anthropométriques. MÉTHODES Quatre mannequins commerciaux avec différentes morphologies ont été sélectionnés. Chaque mannequin a été numérisé 10 fois avec un numériseur portable et une fois avec un numériseur de référence. Les surfaces corporelles totales ont été calculées et comparées. Dans un deuxième temps, 14 volontaires ont estimé la surface coporelle brûlée en utilisant les diagrammes papier et en dessinant sur un logiciel. RÉSULTATS Les valeurs des surfaces corporelles totales obtenues avec le numériseur portable sont 0,812; 1,581; 1,711 et 1,916 m2 pour les mannequins enfant, femme I, femme II et homme. Les résultats du numériseur de référence sont 0,815; 1,588; 1,716 et 1,918 m2. Les ratios des surfaces brûlées des mannequins correspondent à 23,33; 22,67, 32,63 et 26,07 % pour les mannequins. Les estimations des surfaces brûlées obtenues avec les diagrammes en papier représentent 29,9; 32,5; 40,4 et 35,7 %. Les résultats obtenus avec le logiciel sont 23,5; 22,6; 32,1 et 25,1 %. CONCLUSION Le numériseur portable reproduit avec précision et exactitude la surface corporelle totale. L’utilisation des données anthropométriques pour le calcul du pourcentage brûlé représente un outil plus précis et exact que les diagrammes papier. / PURPOSE Total body surface area burned assessment is currently based on the transpositon of burns seen on paper charts representing standard models. The purpose of this project is to contribute to the validation of a tool for TBSA assessment. A handheld 3D scanner and anthropometrical measurements have been proposed. METHODS Four commercial mannequins with different body shapes were selected. Each model was scanned 10 times with a handhed, white light scanner and once with a gold standard scanner. The images were transferred to a modelling software allowing to assess the total body surface. Total body surfaces were calculated and compared. Secondly, 14 volunteers estimated the total burned surface using paper charts and drawing on 3D virtual models. RESULTS Values of the total body surface obtained with the handheld scanner are 0.812; 1.581; 1.711 and 1.916 m2 for the child, female I, female II and male mannequins. The results of the gold standard scanner are 0.815 ; 1.588 ; 1.716 and 1.918 m2. Burn extent ratios correspond to 23.33 ; 22.67 ; 32.63 and 26.07 % for the same mannequins. Estimated burned surfaces obtained with paper diagrams are the following : 29.9 ; 32.5 ; 40.4 and 35.7 %. Results obtained with the software are 23.5 ; 22.6 ; 32.1 and 25.1 %. CONCLUSION The handheld scanner is a precise and accurate tool for the assessment of the total surface. Use of anthropometric data for the calculation of the body burned surface is a more accurate tool and less variable than the conventional paper charts.
385

Can market specialization reduce the entry cost of automated largescale 3D-scanning of movable artifacts for culture and heritage preservation?

Leksell, Torbjörn January 2018 (has links)
Automated, large-scale 3D-scanning systems are important tools in culture and heritage preservation that allows museums and art institutes to digitize their collections of movable artifacts for the purpose of preservation, research, and exhibition. Unfortunately, the cost of these systems limits their usage to a handful of wealthy museums and art institutes. This thesis explores if it possible to significantly reduce the cost of such a system by presenting a viable automated, large-scale, 3D-scanning system for movable artifacts tailored to the needs of museums and art institutes. To achieve the thesis goal a market analysis was conducted to identify the need and requirements museums and art institutes have for these kinds of systems. The market analysis also explored available systems on the market and how museums and art institutes use them. The result of the market analysis identified a specific type of automated, large-scale, 3D-scanning system design suitable for market specialization. Based on the market analysis requirements for such a system design were specified and developed into a mechanical design and hardware architecture. These were then used to construct and evaluate a limited prototype as a way of validating the mechanical design and hardware architecture. The remainder of the work consisted of a cost analysis which used the hardware architecture and mechanical designs to estimate the material and component cost to produce a single unit of the developed system. The results of this thesis show that it is probable that market specialization significantly reduces the cost for museums and art institutes to purchase an automated, large-scale, 3D-scanning system compared with available market alternatives. / Automatiserade 3D-scanners som kan 3D-scanna stora volymer av konstprodukter är viktiga verktyg inom kulturhistorisk bevaring då det tillåter museum att digitalisera samlingar i syfte att bevara, forska och ställa ut. Tyvärr så är dessa system dyra och bara ett fåtal museer har resurser nog för att köpa in dem. Denna uppsats utforskar ifall det är möjligt att betydligt reducera kostnaden av ett sådant system genom att presentera en fungerande automatiserad 3D-scanner som är specifikt anpassad för museum. Arbetet började med en marknadsanalys som identifierade kraven som museum ställer på denna typ av system samt en analys av tillgängliga system på marknaden och hur museum använder dessa. Resultatet av detta arbete var att en specifik typ av automatiserad 3D-scannar lämplig för anpassning identifierades. Utifrån kraven som identifierades genom marknadsanalysen så utvecklades sedan en mekanisk och elektrisk design för systemet. Dessa användes sedan för att bygga och utvärdera en begränsad prototyp i syfte att validera den mekaniska och elektriska designen. Resterande arbete bestod av en kostnadsanalys som använde den mekaniska och elektriska designen för att utvärdera material och komponentkostnaden för att bygga en enhet av det utvecklade systemet. Slutsatsen av arbetet i denna uppsats är att det är troligt att det blir billigare för museum att köpa denna typ av system ifall de utvecklas utifrån deras specifika behov jämfört med tillgängliga system på marknaden.
386

KARTAL: Web Application Vulnerability Hunting Using Large Language Models : Novel method for detecting logical vulnerabilities in web applications with finetuned Large Language Models / KARTAL: Jakt på sårbarheter i webbapplikationer med hjälp av stora språkmodeller : Ny metod för att upptäcka logiska sårbarheter i webbapplikationer med hjälp av finjusterade stora språkmodeller

Sakaoglu, Sinan January 2023 (has links)
Broken Access Control is the most serious web application security risk as published by Open Worldwide Application Security Project (OWASP). This category has highly complex vulnerabilities such as Broken Object Level Authorization (BOLA) and Exposure of Sensitive Information. Finding such critical vulnerabilities in large software systems requires intelligent and automated tools. State-of-the-art (SOTA) research including hybrid application security testing tools, algorithmic brute forcers, and artificial intelligence has shown great promise in detection. Nevertheless, there exists a gap in research for reliably identifying logical and context-dependant Broken Access Control vulnerabilities. We modeled the problem as text classification and proposed KARTAL, a novel method for web application vulnerability detection using a Large Language Model (LLM). It consists of 3 components: Fuzzer, Prompter, and Detector. The Fuzzer is responsible for methodically collecting application behavior. The Prompter processes the data from the Fuzzer and formulates a prompt. Finally, the Detector uses an LLM which we have finetuned for detecting vulnerabilities. In the study, we investigate the performance, key factors, and limitations of the proposed method. Our research reveals the need for a labeled Broken Access Control vulnerability dataset in the cybersecurity field. Thus, we custom-generate our own dataset using an auto-regressive LLM with SOTA few-shot prompting techniques. We experiment with finetuning 3 types of decoder-only pre-trained transformers for detecting 2 sophisticated vulnerabilities. Our best model attained an accuracy of 87.19%, with an F1 score of 0.82. By using hardware acceleration on a consumer-grade laptop, our fastest model can make up to 539 predictions per second. The experiments on varying the training sample size demonstrated the great learning capabilities of our model. Every 400 samples added to training resulted in an average MCC score improvement of 19.58%. Furthermore, the dynamic properties of KARTAL enable inferencetime adaption to the application domain, resulting in reduced false positives. / Brutet åtkomstkontroll är den allvarligaste säkerhetsrisken för webbapplikationer enligt Open Worldwide Application Security Project (OWASP). Denna kategori har mycket komplexa sårbarheter såsom Brutet behörighetskontroll på objektnivå (BOLA) och exponering av känslig information. Att hitta sådana kritiska sårbarheter i stora programvarusystem kräver intelligenta och automatiserade verktyg. Senaste tekniken (SOTA)-forskning, inklusive hybridverktyg för säkerhetstestning av applikationer, algoritmiska bruteforcers och artificiell intelligens, har visat stor potential för upptäckt. Trots detta finns det en lucka i forskningen när det gäller tillförlitlig identifiering av logiska och kontextberoende sårbarheter relaterade till Brutet åtkomstkontroll. Vi modellerade problemet som textklassificering och föreslog KARTAL, en ny metod för att upptäcka sårbarheter i webbapplikationer med hjälp av en stor språkmodell (LLM). Den består av 3 komponenter: Fuzzer, Prompter och Detector. Fuzzer ansvarar för att systematiskt samla in applikationsbeteende. Prompter bearbetar data från Fuzzer och formulerar en förfrågan. Slutligen använder Detector en LLM som vi har finjusterat för att upptäcka sårbarheter. I studien undersöker vi prestanda, nyckelfaktorer och begränsningar hos den föreslagna metoden. Vår forskning visar behovet av en märkt dataset för sårbarheter relaterade till Brutet åtkomstkontroll inom cybersäkerhetsområdet. Därför genererar vi anpassade dataset med hjälp av en auto-regressiv LLM med SOTA few-shot-prompting-tekniker. Vi experimenterar med att finjustera 3 typer av endast avkodare transformers som är förtränade för att upptäcka 2 sofistikerade sårbarheter. Vår bästa modell uppnådde en noggrannhet på 87.19% med en F1-poäng på 0.82. Genom att använda hårdvaruacceleration på en bärbar dator för konsumenter kan vår snabbaste modell göra upp till 539 förutsägelser per sekund. Experimenten med varierande storlek på träningsprovet visade på vår modells stora förmåga att lära sig. Varje 400 prover som lades till träningen resulterade i en genomsnittlig förbättring av MCC-poängen med 19.58%. Dessutom möjliggör de dynamiska egenskaperna hos KARTAL anpassning vid inferringstid till applikationsdomänen, vilket resulterar i färre falska positiva resultat.
387

Alminares mudéjares de la marca superior. Nueva aproximación a su evolución histórica. El caso de la torre de San Pablo en Zaragoza

Molina Sánchez, Susana 13 October 2022 (has links)
[ES] Los ocho siglos de dominio de la cultura islámica en la Península Ibérica motivaron la proliferación de un extenso patrimonio cultural, arquitectónico y artístico. En este contexto, nació el arte mudéjar como una fusión de estilos dada la convivencia entre distintas culturas. Siendo las torres alminares-mudéjares aragonesas el fiel reflejo de este tipo de arquitectura, éstas constituyen el objeto de estudio del presente trabajo. En este sentido, el marco geográfico de la tesis abarca el territorio de la antigua Marca Superior de Al-Andalus, que incluye los valles de los ríos Ebro, Jalón, Jiloca y afluentes, como centros neurálgicos de la esencia del mudéjar (con sus torres como máximo exponente). La inquietud por investigar acerca de la evolución histórico-constructiva de dichas torres nace de su peculiar arquitectura, producto de la síntesis entre Oriente y Occidente. Asimismo, la escasa presencia de documentación de la época unida a los estudios que se han venido realizando hasta el momento, genera todavía una serie de carencias en el conocimiento de dichas torres, especialmente en lo referente a su origen. Por tanto, resulta conveniente abordar dichas necesidades aportando un nuevo enfoque al estudio de su evolución histórico-constructiva. Para ello, se establece una metodología de levantamiento digital (específica para elementos con tipología de torre), mediante la aplicación de las técnicas de fotogrametría y escáner láser, como herramientas de apoyo a la lectura de sus fábricas. El gran potencial a nivel gráfico que ofrecen los resultados obtenidos (modelos tridimensionales hiperrealistas texturizados, con alta precisión geométrica y muy buena definición), permite profundizar en el conocimiento de estas torres. Dichos resultados de la investigación, resultan eficaces y cuentan con el rigor científico adecuado para la posterior formulación de una hipótesis sobre el alminar original, del que procede la torre objeto de estudio, y que se podría extrapolar al resto de torres. / [CA] Els huit segles de domini de la cultura islàmica en la Península Ibèrica van motivar la proliferació d'un extens patrimoni cultural, arquitectònic i artístic. En aquest context, va nàixer l'art mudèjar com una fusió d'estils donada la convivència entre diferents cultures. Sent les torres minarets-mudèjars aragoneses el fidel reflex d'aquesta mena d'arquitectura, aquestes constitueixen l'objecte d'estudi del present treball. En aquest sentit, el marc geogràfic de la tesi comprén el territori de l'antiga Marca Superior d'Al-Andalus, que inclou les valls dels rius Ebro, Jalón, Jiloca i afluents, com a centres neuràlgics de l'essència del mudèjar (amb les seues torres com a màxim exponent). La inquietud per investigar sobre l'evolució històric-constructiva d'aquestes torres naix de la seua peculiar arquitectura, producte de la síntesi entre Orient i Occident. Així mateix, l'escassa presència de documentació de l'època unida als estudis que s'han realitzat fins al moment, genera encara una sèrie de mancances en el coneixement d'aquestes torres, especialment referent al seu origen. Per tant, resulta convenient abordar aquestes necessitats aportant un nou enfocament a l'estudi de la seua evolució històric-constructiva. Per a això, s'estableix una metodologia d'alçament digital (específica per a elements amb tipologia de torre), mitjançant l'aplicació de les tècniques de fotogrametria i escàner làser, com a eines de suport a la lectura de les seues fàbriques. El gran potencial a nivell gràfic que ofereixen els resultats obtinguts (models tridimensionals hiperrealistes texturizados, amb alta precisió geomètrica i molt bona definició), permet aprofundir en el coneixement d'aquestes torres. Aquests resultats de la investigació, resulten eficaces i compten amb el rigor científic adequat per a la posterior formulació d'una hipòtesi sobre el minaret original, del qual procedeix la torre objecte d'estudi, i que es podria extrapolar a la resta de torres. / [EN] The eight centuries of Islamic culture in Iberian Peninsula led to the proliferation of an extensive cultural, architectural and artistic heritage. In this context, Mudejar art was born as a fusion of styles due to the coexistence of different cultures. Aragonese minaret-Mudejar towers are a faithful reflection of this type of architecture, and are the object of study of this work. In this sense, thesis' geographical framework covers the territory of ancient Marca Superior of Al-Andalus, which includes the river valleys of Ebro, Jalón, Jiloca and tributaries, as nerve centres of the essence of Mudejar architecture (with its towers as its maximum exponent). The interest in researching the historical-constructive evolution of these towers stems from their peculiar architecture, a product of the synthesis between East and West. Likewise, the scarce documentation of that period, together with different studies that have been carried out up to now, still generate a series of deficiencies in the knowledge of these towers, especially with regard to their origin. It is therefore advisable to address these needs by providing a new approach to the study of their historical-constructive evolution. For this purpose, a digital survey methodology is established (specifically for tower typology elements), using photogrammetry (SfM) and laser scanner techniques as tools to support the reading of their walls. A great graphic potential offered by the results obtained (reality-based 3D models, with high geometric precision and optimal definition), allows us to deepen our knowledge of these towers. These research results are effective and have an appropriate scientific rigour for the subsequent formulation of a hypothesis about the original minaret, from which the tower under study originates, and which could be extrapolated to the rest of the towers. / Molina Sánchez, S. (2022). Alminares mudéjares de la marca superior. Nueva aproximación a su evolución histórica. El caso de la torre de San Pablo en Zaragoza [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/188135 / TESIS
388

<b>Forensic Analysis of Images and Documents</b>

Ruiting Shao (18018187) 23 February 2024 (has links)
<p dir="ltr">This thesis involves three topics related to forensic analysis of media data. The first topic is the analysis of images and documents that have been created with a scanner. The goal is to detect and identify scanner model from the scanned images/documents. We propose a deep learning system that can automatically learn the inherent features of the scanned images. This system will produce a scanner model identification and a reliability map for a scanned image. The proposed system has shown promising results in the forensic analysis of scanned images. The second topic is related to forensic integrity of scientific papers. The project is divided into multiple tasks, data collection, image extraction, and manipulation detection. We have constructed a dataset of retracted scientific papers that have been verified to have issues with integrity. We design and maintain a web-based Scientific Integrity System for forensic analysis of the images within scientific publications. The third topic is related to media document analysis. Our goal is to identify the publication style for media document, aiding in the potential document manipulation. We are mainly focusing on image-text consistency check, and synthetic tweets analysis. For image-text inconsistency check, we describe a system that can examine an image in document and the corresponding text caption (or other associated text with the image) to check the image/text consistency. For synthetic tweets analysis, we propose a system to detect and identify the text generation models and paraphrase attack models.</p>
389

由地面光達資料自動重建建物模型之研究 / Automatic Generation of Building Model from Ground-Based LIDAR Data

詹凱軒, Kai-Hsuan,Chan Unknown Date (has links)
地面光達系統可以快速獲取大量且高精度之點雲資料,這些點雲資料不但記錄了被掃描物體之三維資訊,還包含其色彩訊息。但因光達點雲資料量過於龐大,若要直接於電腦上展示其三維模型,必須配合有效的資料處理技術,才能迅速且即時地將資料顯示於螢幕上。 我們針對地面光達系統獲取之建物點雲,提出一套處理方法,期盼透過少數關鍵點雲,就足以表示整個建物的模型。研究流程主要分為三階段,首先採用三維網格資料結構,從地面光達系統獲取之建物點雲中,萃取出關鍵點雲,並利用三維不規則三角網建模方式,進行模型建構工作,產生建物大略模型。其次再逐點判斷是否將剩餘之點加入此模型中,持續更新模型細微之部分。最後將點雲中的色彩資訊轉成影像,敷貼在模型表面上,讓整個模型更為逼真。 我們以政大綜合大樓進行實驗,成功地減少大量冗餘的點雲資料,只需要約原始點雲的1%,就足以將綜合大樓模型建構完成。為了達到可以從不同視角即時瀏覽建物模型,我們採用虛擬實境語言(VRML)來描述處理後的三維模型,遠端使用者只需透過一般網頁瀏覽器,即可即時顯示處理過的三維建物模型。 / Ground-based LIDAR system can be used to detect the surface of the buildings on the earth. In general, it produces large amount of high-precision point cloud data. These data include not only the three-dimensional space information, but also the color information. However, the number of point cloud data is huge and is difficult to be displayed efficiently. It’s necessary to use efficient data processing techniques in order to display these point cloud data in real-time. In this research, we construct the three-dimensional building model using the key points selected from a given set of point cloud data. The major works of our scheme consists of three parts. In the first part, we extract the key points from the given point cloud data through the help of a three-dimensional grid. These key points are used to construct a primitive model of the building. Then, we checked all the remaining points and decided whether these points are essential to the final building model. Finally, we transformed the color information into images and then used the transformed images to represent generic surface material of the three-dimensional model of the building. The goal of the final step is to make the model more realistic. In the experiments, we used the twin-tower of our university as our target. We successfully reduced the required data in displaying the building model and only about one percent of the original point cloud data are used in the final model. Hence, one can see the twin-tower from various view points in real-time. In addition, we use VRML to describe our model and the users can browse the results in real-time on internet.
390

Estudo de porosidade por processamento de imagens aplicada a patologias do concreto / Computer vision system for identification of alkali aggregate in concrete image

Rodrigo Erthal Wilson 11 August 2015 (has links)
A reação álcali-agregado - RAA é uma patologia de ação lenta que tem sido observada em construções de concreto capaz de comprometer suas estruturas. Sabe-se que a reação álcali-agregado é um fenômeno bastante complexo em virtude da grande variedade de rochas na natureza que são empregadas como agregados no preparo do concreto, podendo cada mineral utilizado afetar de forma distinta a reação ocorrida. Em função dos tipos de estrutura, das suas condições de exposição e dos materiais empregados, a RAA não se comporta sempre da mesma forma, em virtude disto a pesquisa constante neste tema é necessária para o meio técnico e a sociedade. Pesquisas laboratoriais, empíricas e experimentais tem sido rotina em muitos dos estudos da RAA dada ainda à carência de certas definições mais precisas a respeito dos métodos de ensaio, mas também em função da necessidade do melhor conhecimento dos materiais de uso em concretos como os agregados, cimentos, adições, aditivos entre outros e do comportamento da estrutura. Embora técnicas de prevenção possam reduzir significativamente a incidência da RAA, muitas estruturas foram construídas antes que tais medidas fossem conhecidas, havendo no Brasil vários casos de estruturas afetadas, sendo custosos os reparos dessas estruturas. Em estudos recentes sobre o tamanho das partículas de álcali-agregado e sua distribuição foi concluído que o tamanho do agregado está relacionado com o potencial danoso da RAA. Existem ainda indícios de que o tamanho e a distribuição dos poros do concreto também sejam capazes de influenciar o potencial reativo do concreto. Neste trabalho desenvolvemos um Sistema de Visão Artificial (SVA) que, com o uso de técnicas de Processamento de Imagens, é capaz de identificar em imagens de concreto, agregado e poros que atendam em sua forma, às especificações do usuário, possibilitando o cálculo da porosidade e produzindo imagens segmentadas à partir das quais será possível extrair dados relativos à geometria desses elementos. Serão feitas duas abordagens para a obtenção das imagens, uma por Escâner Comercial, que possui vantagens relacionadas à facilidade de aquisição do equipamento, e outra por micro tomógrafo. Uma vez obtidas informações sobre as amostras de concreto, estas podem ser utilizadas para pesquisar a RAA, comparar estruturas de risco com estruturas antigas de forma a melhorar a previsão de risco de ocorrência, bem como serem aplicadas a outras no estudo de outras patologias do concreto menos comuns no nosso país, como o efeito gelo/degelo. / The alkali-aggregate reaction - RAA is a condition of slow action that has been observed in concrete constructions that could affect their structures. It is known that the alkali-aggregate reaction is a very complex phenomenon because of the great variety of rocks in nature that are used as aggregates for concrete, and each mineral used differently affects the reaction occurred. Depending on the type of structure, its exposure conditions and the materials used, this phenomenon does not always behaves the same way, because of this, constant research in this area is needed for the technical means and the society. Laboratory, empirical and experimental research has been routine in many of the RAA studies still given the lack of certain more precise definitions concerning the testing methods, but also because of the need for better understanding of the use of materials in concrete as aggregate, cement, additions, additives etc. and structure behavior. Prevention techniques could significantly reduce the incidence of RAA. Still, many structures were built before such measures were known, several cases of affected structures were discovered in Brazil, all with large spending on repairs of the affected structures. In recent studies on the particle size of the alkaliaggregate and its distribution was concluded that the aggregate size is related to the damaging potential of the RAA. There are also indications that the size and distribution of concrete pores are also capable of influencing the reactive potential of the concrete. In the present work we developed an Artificial Vision System ( VAS ) that uses image processing techniques to identify aggregate and pores in hardened concrete images, enabling the calculation of porosity and producing segmented images that can be used to investigate data about the geometry of these elements. Were made two approaches for obtaining the images, one by Scanner Commercial, which has related advantages will ease the acquisition of equipment, and other micro CT scanner. Once obtained information on the concrete samples, these can be used to search the AAR compared risk structures with old structures so as to enhance the occurrence of risk prediction, as well as be applied to other concrete in the study of other pathologies less common in our country, as ice effect / thaw.

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