• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 359
  • 54
  • 47
  • 45
  • 37
  • 19
  • 16
  • 6
  • 6
  • 6
  • 3
  • 3
  • 3
  • 3
  • 2
  • Tagged with
  • 727
  • 318
  • 113
  • 77
  • 74
  • 66
  • 57
  • 54
  • 54
  • 51
  • 41
  • 41
  • 41
  • 37
  • 35
  • 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.
691

物件導向分類法於DMC航照影像萃取崩塌地之研究 / Object-oriented Classification for Extracting Landslides Using DMC Aerial Images

孔繁恩, Kung, Fan En Unknown Date (has links)
台灣位於環太平洋地震帶上,地形為山地居多,且地質脆弱,加上位於西太平洋副熱帶地區,使得山區常受到颱風的侵擾而發生崩塌,導致土石流和洪水等災害發生,進而影響人民的生命和財產安全。因此,如何有效地建置崩塌地區域資料庫,成為國土保育與災害防治的重要課題。以往利用遙測與航測技術於崩塌地萃取的研究中,大多是於幾何糾正後衛星影像或是航測正射影像上分析崩塌地,但產製正射影像或是糾正衛星影像時,都需要花費較多的時間,對於講求時效性的救災行動而言頗為不利。本研究之目的為發展一套不需使用正射影像萃取崩塌地的方法,以物件導向影像分類法,於DMC(Digital Mapping Camera)航測原始影像上直接萃取崩塌地資訊。首先採取多重解析影像分割的技術,將航測影像依像元光譜和形狀同質性分割成不同區塊(物件),接著利用影像光譜統計值搭配區域成長法,偵測影像中的雲覆蓋地區並過濾。其次,根據光譜亮度統計特徵值,將影像區分成陰暗地區、正常地區以及較亮地區之三種土地覆蓋類型,使用線性相關糾正法(Linear-correlation Correction)將陰暗地區光譜亮度值轉換至正常地區,並利用物件的特徵值,如光譜、面積、形狀以及相關性依序萃取此三種土地覆蓋類型內的崩塌地。最後,使用光線追蹤法 (Ray-tracing),將崩塌地區塊從影像坐標轉換至地圖坐標,使其可以套疊地形資料如坡度、坡向,並進行空間分析以提升崩塌地的判釋精度。研究結果顯示,崩塌地萃取之使用者精度和生產者精度,均有82%以上,並且整個實驗可大量批次處理影像,及快速建立崩塌地資料庫,本研究之方法和崩塌地資料庫將有助於國土保育與崩塌地的災害防治。 / Being located in a subtropical and seismic zone of the West Pacific, the geology is fragile and topography is mountainous in Taiwan. Landslides, floods and other disasters induced by typhoons occur frequently, and it cause the life-threatening and property loss of human beings in Taiwan. Therefore, how to establish landslides data effectively become an important issue of land conservation and disasters management. In recently years, most of the researchers used aerial ortho-images or satellite georeferencing images to detect landslides sites. However, it spent a lot of time generating aerial ortho-images and rectifying satellite images, and it also reduced the efficiency of landslides analysis. Thus, this study developed an object-oriented classification method, which can be directly applied in raw image data, to detect landslides sites. Firstly, this study used multi-resolution image segmentation technique to segment images acquired by Z/I DMC(Digital Mapping Camera) into individual regions (objects) according to the homogeneity of spectral and shape features, and then removed cloud areas by using brightness features depended on the spectral information of images. Secondly, the study divided the entire image into three areas, which are darker area, normal area and lighter area, according to brightness value. Next, Linear-correlation correction (LCC) method was used in this study to transform darker area to normal area so that it can easily detect the landslides sites in darker area, and the object features, such as spectral, area, shape and space correlation indices, were used to extract landslide sites in images. Finally, in order to enhance the accuracy of landslide, the initial landslides were converted from image coordinate system to map coordinate system by ray-tracing method, so the initial landslides data can be further extracted by using topographic data, including slope and aspect data. The results of this study showed that the user and producer accuracies of detecting landslides can reach up to 82%. Moreover, the entire experiments process of this study can batch analyze automatically and establish landslides database quickly. It is expected that the method and landslides data of this study may have contribution to land conservation and disasters management.
692

Vibration Transmission and Support Loss in MEMS Sensors

Chouvion, Benjamin 23 April 2010 (has links) (PDF)
Micro-Electro-Mechanical Systems (MEMS) sensors are used in an increasing range of applications such as inertial guidance or automotive safety systems, in which damping has a significant and negative effect on the device performances. Support loss, which governs the losses from the resonator to its foundation through the supporting structure, is an important source of damping in MEMS resonators. This thesis focuses on improving an understanding of this particular damping mechanism so that efficient models can be developed to predict the amount and relative importance of support loss at the design stage. The coupling between resonator and support is of principal interest to evaluate the interaction and energy transmission between them. To quantify the stresses acting on the support, a model that predicts vibration transmission through common MEMS structures is first developed. A general wave propagation approach for the vibration analysis of networks consisting of slender, straight and curved beam elements and complete ring is presented. The analysis is based on a ray tracing method and a procedure to predict the natural frequencies and mode shapes of complex ring/beam structures is demonstrated. An analytical method is then used to model the support, approximated to a semi-infinite domain, and quantify support losses. The work focuses mainly on in-plane vibrations for single-axis gyroscopes. However, new generation of multi-axis resonators is being currently developed, and the in-plane models are extended to cope with out-of-plane vibration transmission and support loss. To illustrate the effectiveness of the models, several numerical examples are presented, by applying them first to simple beam-like structures and subsequently to structures of increasing complexity. Strategies for improving the quality factor of common MEMS sensors, and specific ring-based resonators designs that minimise support losses, are also considered.
693

What Does it Take to Get your Attention? : The influence of In-Store and Out-of-Store Factors on Visual Attention and Decision Making for Fast-moving Consumer Goods

Shams, Poja January 2013 (has links)
Decision making for fast-moving consumer goods involves a choice between numerous similar alternatives. Under such demanding circumstances, a decision is made for one product. The decision is dependent on the interaction between the environment and the mind of the consumer, both of which are filled with information that can influence the outcome. The aim of this dissertation is to explore how the mind and the environment guides attention towards considered and chosen products in consumer decision making at the point-of-purchase. Consumers are equipped with several effort reduction strategies to simplify complex decision making. The selection of strategies can be conscious or automatic and driven by information in the environment or the mind of the decision maker. The selected decision strategy reduces the set of options to one alternative in an iterative process of comparisons that are fast and rely on perceptual cues to quickly exclude irrelevant products. This thesis uses eye-tracking to explore this rapid processing that lacks conscious access or control. The purpose is to explore how product packaging and placement (as in-store factors), and recognition, preferences, and choice task (as out-of-store factors) influence the decision-making process through visual attention. The results of the 10 experiments in the five papers that comprise this thesis shed new light on the role of visual attention in the interaction between the environment and the mind, and its influence on the consumer. It is said that consumers choose with their eyes, which means that unseen is unsold. The results of this thesis show that it is just as important to be comprehended as it is to be seen. In split-second decision making, the ability to recognize and comprehend a product can significantly impact preferences. Comprehension stretches beyond perception as consumers infer value from memory structures that influence attention. Hence, the eye truly sees what the mind is prepared to comprehend.
694

非國家行為者之跨國運作--以國際透明組織之全球反貪運動為例 / Transnational Advocacy of Non-State Actors--A Case Study on Transparency International's Global Anti-corruption Movement

葛傳宇, Ko, Chuan Yu Unknown Date (has links)
跨國公司與開發中國家官員之賄賂關係被稱為骯髒聯盟。非國家行為者是形塑與改變國際規範之重要參與者,本研究檢視重點在於國際透明組織為切斷骯髒聯盟之供需關係,如何運用其獨特之跨國倡議網絡模式,透過建立聯盟(coalition-building)途徑,促成國際公約並且改變簽署國之國家行為。該非政府組織影響國際關係之具體成果為1997年簽署之OECD反賄公約,該公約是第一個從供應方(supply-side)切斷跨國商業賄賂鏈之國際規範,其立法歷程與會員國之國家偏好改變足以證明國際透明組織之影響力。 主流學派之結構現實主義者主張國際關係是結構決定論,以強權國家為主要的、具決定性之行為者,國家偏好是外生給定的利益排序。本研究主張以建構主義為基礎之全球反貪運動則是反其道而行,國際透明組織建構之跨國倡議網絡,擅用人氣政治與切身性政治,以合作取代對抗,有效促成已開發國家採取集體行動,簽署OECD反賄公約。當強權之間拒絕改變現狀時,非國家行為者之理念說服行動可以逐一改變國家偏好,進而改變國際規範。在倡議國際反貪議題上,國際透明組織的確是國際新規範之催生者。 本文採案例研究,主體為國際透明組織,客體為OECD反賄公約,交叉運用深度訪談與調查式過程追蹤研究,密集而深入取得相關當事人提供之第一手資料,彌補既有文獻靜態分析之不足。 / Non-state actors are essential participants in shaping and changing international norms. There has been a long-standing practice of a tacit “dirty alliance” between multinational corporations and developing countries officials. This research focuses on Transparency International(TI), which seeks to sever the supply and demand chain relationships of the dirty alliance by mobilizing a unique model of transnational advocacy network (TAN), engaging coalition-building, lobbying for a new set of international norms and persuading the changes of signatory states’ behavior. The fruits are the adoption of the 1997 OECD Anti-Bribery Convention, which is the first supply-side norm to cut off transnational business bribery chain. Both the key events of the legislative process and the changes of state preferences among the signatories validify the argument for the TI’s significant influence. Contrary to mainstream international relations theories such as structural realism claiming structural determinism, predominant role of powerful states, and exogenously given nature of state preferences, this research proves constructivism prevails. TI’s TAN model artistically exercises popularity politics as well as proximity politics, advocates cooperation instead of confrontation against bribe-givers and bribe-takers, and effectively persuades developed countries to take collective actions by adopting and ratifying the OECD Anti-Bribery Convention. While powerful states resist changing the status quo, non-state actors indeed demonstrate their capability of persuading states to change their preferences. TI is entitled to be the midwife in formulating new international norms against transnational corruption. This research applies case study methodology, making TI as the subject and the OECD Anti-Bribery Convention as the object. Diligent analysis and interpretations are based on the cross-references of in-depth interviews and investigative process-tracing method to extract the primary data from relevant parties so as to supplement the deficiencies of the available literatures.
695

Significance of bank records analysis as a technique in tracing fraud suspects

Myeza, Nkosinathi Wonderboy 12 1900 (has links)
Text in English / The research attempts to establish the significance of bank records analysis as a technique in tracing fraud suspects. The purposes of conducting this research was to establish the current approach by the investigators of the SAPS in respect of bank records analysis in tracing fraud suspects; to explore and report on the findings of national and international literature in an attempt to find new information thereby improving the current method of bank records analysis and its specific use in tracing fraud suspects; and to make new information, in the form of written articles and this dissertation, available to the SAPS to be considered for inclusion in the training curriculum for their investigators. In collecting data, the researcher used literature study, interviews with individual participants and case dockets analysis. Essentially, the recommendations were drawn from the conclusions of the data obtained. These recommendations may offer solutions to the problem identified. / Criminology and Security Science / M. Tech. (Forensic Investigation)
696

Arcabouço para análise de eventos em vídeos. / Framework for analyzing events in videos.

SILVA, Adson Diego Dionisio da. 07 May 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-07T15:29:04Z No. of bitstreams: 1 ADSON DIEGO DIONISIO DA SILVA - DISSERTAÇÃO PPGCC 2015..pdf: 2453030 bytes, checksum: 863c817f9714377b827d4d6fa0770c51 (MD5) / Made available in DSpace on 2018-05-07T15:29:04Z (GMT). No. of bitstreams: 1 ADSON DIEGO DIONISIO DA SILVA - DISSERTAÇÃO PPGCC 2015..pdf: 2453030 bytes, checksum: 863c817f9714377b827d4d6fa0770c51 (MD5) Previous issue date: 2015-08-31 / O reconhecimento automático de eventos de interesse em vídeos envolvendo conjuntos de ações ou de interações entre objetos. Pode agregar valor a sistemas de vigilância,aplicações de cidades inteligentes, monitoramento de pessoas com incapacidades físicas ou mentais, dentre outros. Entretanto, conceber um arcabouço que possa ser adaptado a diversas situações sem a necessidade de um especialista nas tecnologias envolvidas, continua sendo um desafio para a área. Neste contexto, a pesquisa realizada tem como base a criação de um arcabouço genérico para detecção de eventos em vídeo com base em regras. Para criação das regras, os usuários formam expressões lógicas utilizando Lógica de Primeira Ordem e relacionamos termos com a álgebra de intervalos de Allen, adicionando assim um contexto temporal às regras. Por ser um arcabouço, ele é extensível, podendo receber módulos adicionais para realização de novas detecções e inferências Foi realizada uma avaliação experimental utilizando vídeos de teste disponíveis no site Youtube envolvendo um cenário de trânsito, com eventos de ultrapassagem do sinal vermelho e vídeos obtidos de uma câmera ao vivo do site Camerite, contendo eventos de carros estacionando. O foco do trabalho não foi criar detectores de objetos (e.g. carros ou pessoas) melhores do que aqueles existentes no estado da arte, mas propor e desenvolver uma estrutura genérica e reutilizável que integra diferentes técnicas de visão computacional. A acurácia na detecção dos eventos ficou no intervalo de 83,82% a 90,08% com 95% de confiança. Obteve acurácia máxima (100%) na detecção dos eventos, quando substituído os detectores de objetos por rótulos atribuídos manualmente, o que indicou a eficácia do motor de inferência desenvolvido para o arcabouço. / Automatic recognition of relevant events in videos involving sets of actions or interactions between objects can improve surveillance systems, smart cities applications, monitoring of people with physical or mental disabilities, among others. However, designing a framework that can be adapted to several situations without an expert in the involved technologies remains a challenge. In this context, this work is based on the creation of a rule-based generic framework for event detection in video. To create the rules, users form logical expressions using firstorder logic (FOL) and relate the terms with the Allen’s interval algebra, adding a temporal context to the rules. Once it is a framework, it is extensible, and may receive additional modules for performing new detections and inferences. Experimental evaluation was performed using test videos available on Youtube, involving a scenario of traffic with red light crossing events and videos from Camerite website containing parking car events. The focus of the work was not to create object detectors (e.g. cars or people) better than those existing in the state-of-the-art, but, propose and develop a generic and reusable framework that integrates differents computer vision techniques. The accuracy in the detection of the events was within the range of 83.82% and 90.08% with 95% confidence. Obtained maximum accuracy (100 %) in the detection of the events, when replacing the objects detectors by labels manually assigned, what indicated the effectiveness of the inference engine developed for this framework.
697

Detection of annual rings in wood

Jonsson, Christian January 2008 (has links)
This report describes an annual line detection algorithm for the WoodEye quality control system. The goal with the algorithm is to find the positions of annual lines on the four surfaces of a board. The purpose is to use this result to find the inner annual ring structure of the board. The work was done using image processing techniques to analyze images collected with WoodEye. The report gives the reader an insight in the requirements of quality control systems in the woodworking industry and the benefits of automated quality control versus manual inspection. The appearance and formation of annual lines are explained on a detailed level to provide insight on how the problem should be approached. A comparison between annual rings and fingerprints are made to see if ideas from this area of pattern recognition can be adapted to annual line detection. This comparison together with a study of existing methods led to the implementation of a fingerprint enhancement method. This method became a central part of the annual line detection algorithm. The annual line detection algorithm consists of two main steps; enhancing the edges of the annual rings, and tracking along the edges to form lines. Different solutions for components of the algorithm were tested to compare performance. The final algorithm was tested with different input images to find if the annual line detection algorithm works best with images from a grayscale or an RGB camera.
698

Dynamic sound rendering of complex environments / Rendu sonore dynamique d'environnements complexes

Loyet, Raphaël 18 December 2012 (has links)
De nombreuses études ont été menées lors des vingt dernières années dans le domaine de l’auralisation.Elles consistent à rendre audible les résultats d’une simulation acoustique. Ces études se sont majoritairementfocalisées sur les algorithmes de propagation et la restitution du champ acoustique dans desenvironnements complexes. Actuellement, de nombreux travaux portent sur le rendu sonore en tempsréel.Cette thèse aborde la problématique du rendu sonore dynamique d’environnements complexes selonquatre axes : la propagation des ondes sonores, le traitement du signal, la perception spatiale du son etl’optimisation informatique. Dans le domaine de la propagation, une méthode permettant d’analyser lavariété des algorithmes présents dans la bibliographie est proposée. A partir de cette méthode d’analyse,deux algorithmes dédiés à la restitution en temps réel des champs spéculaires et diffus ont été extraits.Dans le domaine du traitement du signal, la restitution est réalisée à l’aide d’un algorithme optimisé despatialisation binaurale pour les chemins spéculaires les plus significatifs et un algorithme de convolutionsur carte graphique pour la restitution du champ diffus. Les chemins les plus significatifs sont extraitsgrace à un modèle perceptif basé sur le masquage temporel et spatial des contributions spéculaires.Finalement, l’implémentation de ces algorithmes sur des architectures parallèles récentes en prenant encompte les nouvelles architectures multi-coeurs et les nouvelles cartes graphiques est présenté. / During the past twenty years many studies have been conducted in the field of auralization, which aimsat rendering audible the results of an acoustic simulation. These studies have mainly focused on thepropagation algorithms and the sound field audio rendering for complex environments. Currently, muchresearch concentrates on real-time audio rendering.This thesis addresses the problematic of real-time audio rendering of complex environments accordingto four axes: sound propagation, Digital Signal Processing (DSP), spatial perception of sound andcomputational optimizations. In the field of propagation, a method that aims at analyzing the varietyof existing algorithms is proposed. This method yields two algorithms dedicated to the real-time propagationof both specular and diffuse information. In the field of DSP, the auralization is performed withan efficient binaural spatialization module for the most significant specular information, and a GPUconvolution algorithm for the diffuse sound field auralization. The most significant paths are extractedthanks to a perceptive model based on temporal and spatial masking of the specular contributions.Finally, the implementation of these algorithms on recent computer architectures, taking advantage ofthe parallel processing of the new CPUs, and the benefits of GPUs for DSP calculations is presented.
699

Reconstruction of trees from 3D point clouds

Stålberg, Martin January 2017 (has links)
The geometrical structure of a tree can consist of thousands, even millions, of branches, twigs and leaves in complex arrangements. The structure contains a lot of useful information and can be used for example to assess a tree's health or calculate parameters such as total wood volume or branch size distribution. Because of the complexity, capturing the structure of an entire tree used to be nearly impossible, but the increased availability and quality of particularly digital cameras and Light Detection and Ranging (LIDAR) instruments is making it increasingly possible. A set of digital images of a tree, or a point cloud of a tree from a LIDAR scan, contains a lot of data, but the information about the tree structure has to be extracted from this data through analysis. This work presents a method of reconstructing 3D models of trees from point clouds. The model is constructed from cylindrical segments which are added one by one. Bayesian inference is used to determine how to optimize the parameters of model segment candidates and whether or not to accept them as part of the model. A Hough transform for finding cylinders in point clouds is presented, and used as a heuristic to guide the proposals of model segment candidates. Previous related works have mainly focused on high density point clouds of sparse trees, whereas the objective of this work was to analyze low resolution point clouds of dense almond trees. The method is evaluated on artificial and real datasets and works rather well on high quality data, but performs poorly on low resolution data with gaps and occlusions.
700

[en] TECHNIQUE OF LAUNCHING OF RAYS IN THREE DIMENSIONS FOR THE PREVISÃO DE COBERTURA IN MICRO-CELULARES ENVIRONMENTS / [pt] TÉCNICA DE LANÇAMENTO DE RAIOS EM TRÊS DIMENSÕES PARA A PREVISÃO DE COBERTURA EM AMBIENTES MICRO-CELULARES

LUIS ALBERTO RABANAL RAMIREZ 22 May 2003 (has links)
[pt] O estágio atual das comunicações móveis é caracterizado por um crescimento espetacular da demanda em todos os tipos de ambientes, tanto urbanos densos como suburbanos e rurais . Os planejadores destes sistemas necessitam ferramentas eficientes e economicamente viáveis para a caracterização e projeto deles. O grande objetivo de um bom planejamento é uma boa cobertura, e um dos parâmetros de qualidade é a perda média de propagação. A principal técnica determinística utilizada para o cálculo da perda média de propagação em micro-células em áreas fortemente edificadas é o traçado de raios, a través de um de dois métodos alternativos: o método das imagens e o método de lançamento de raios. Este trabalho apresenta uma formulação detalhada do método de lançamento de raios e dos métodos assintóticos que foram usados afim de calcular os campos eletromagnéticos (direto, refletido e difratado) que permitem calcular a Perda Média de Propagação. Além do mais apresenta-se o método de discriminação espacial usado para acelerar o processo de cálculo. A metodologia proposta foi implementada em programa de computador e são apresentados alguns estudos de caso para ambientes específicos. / [en] The current period of the mobile communications is characterized by a spectacular growth of the demand in all the types of environments, not only in density urbanized cities as suburban and rural. The planners of these systems need efficient and economically viable tools for the design of these systems. The main goal of good planning is a good coverage, and one of the most adopted quality indicators is the path loss of propagation. The mostly used deterministic technique for calculation it in strongly built micro-cells is the tracing of rays, whether the method of the images or the method of launching of rays. This work presents a detailed formularization of the method of launching of rays and of the asymptotic methods which have been used in order to calculate the electromagnetic fields (direct, reflected and diffracted) which allow to calculate the Path Loss of Propagation. Besides it this shown the used method of space discrimination, which was employed to speed up the calculation. The methodology proposal was implemented in computer program and is presented some studies of case for specific environments.

Page generated in 0.0774 seconds