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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.
321

Hybrid Deep Learning Model for Cellular Network Traffic Prediction : Case Study using Telecom Time Series Data, Satellite Imagery, and Weather Data / Hybrid Djupinlärning Modell för Förutsägelse av Mobilnätstrafik : Fallstudie med Hjälp av Telekomtidsseriedata, Satellitbilder och Väderdata

Shibli, Ali January 2022 (has links)
Cellular network traffic prediction is a critical challenge for communication providers, which is important for use cases such as traffic steering and base station resources management. Traditional prediction methods mostly rely on historical time-series data to predict traffic load, which often fail to model the real world and capture surrounding environment conditions. In this work, we propose a multi-modal deep learning model for 4G/5G Cellular Network Traffic prediction by considering external data sources such as satellite imagery and weather data. Specifically, our proposed model consists of three components (1) temporal component (modeling correlations between traffic load values with historical data points via LSTM) (2) computer vision component (using embeddings to capture correlations between geographic regions that share similar landscape patterns using satellite imagery data and state of the art CNN models), and (3) weather component (modeling correlations between weather measurements and traffic patterns). Furthermore, we study the effects and limitations of using such contextual datasets on time series learning process. Our experiments show that such hybrid models do not always lead to better performance, and LSTM model is capable of modeling complex sequential interactions. However, there is a potential for classifying or labelling regions by their urban landscape and the network traffic. / Förutsägelse av mobilnätstrafik är en kritisk utmaning för kommunikation leverantörer, där användningsområden inkluderar trafikstyrning och hantering av basstationsresurser. Traditionella förutsägelsesmetoder förlitar sig främst på historisk tidsseriedata för att förutsäga trafikbelastning, detta misslyckas ofta med att modellera den verkliga världen och fånga omgivande miljö. Det här arbetet föreslår en multimodal modell med djupinlärning förutsägelse av 4G/5G nätverkstrafik genom att beakta externa datakällor som satellitbilder och väderdata. Specifikt består vår föreslagna modell av tre komponenter (1) temporal komponent (korrelationsmodellering mellan trafikbelastningsvärden med historiska datapunkter via LSTM) (2) datorseende komponent (med inbäddningar för att fånga korrelationer mellan geografiska regioner som delar liknande landskapsmönster med hjälp av satelitbilddata och state-of-the-art CNN modeller), och (3) väderkomponent (modellerande korrelationer mellan vädermätningar och trafikmönster). Dessutom studerar vi effekterna och begränsningarna av att använda sådana kontextuella datamängder på tidsserieinlärningsprocessen. Våra experiment visar att hybridmodeller inte alltid leder till bättre prestanda och att LSTM-modellen är kapabel att modellera komplexa sekventiella interaktioner. Det finns dock en potential att klassificera eller märka regioner efter deras stadslandskap och nättrafiken. / La prévision du trafic sur les réseaux cellulaires est un défi crucial pour les fournisseurs de communication, ce qui est important pour les cas d’utilisation tels que la direction du trafic et la gestion des ressources des stations de base. Les méthodes de prédiction traditionnelles reposent principalement sur des données historiques de séries chronologiques pour prédire la charge de trafic, qui échouent souvent à modéliser le monde réel et à capturer les conditions de l’environnement environnant. Dans ce travail, nous proposons un modèle d’apprentissage profond multimodal pour la prédiction du trafic des réseaux cellulaires 4G/5G en considérant des sources de données externes telles que l’imagerie satellitaire et les données météorologiques. Plus précisément, notre modèle proposé se compose de trois composants (1) composant temporel (modélisation des corrélations entre les valeurs de charge de trafic avec des points de données historiques via LSTM) (2) composant de vision par ordinateur (utilisant des incorporations pour capturer les corrélations entre les régions géographiques qui partagent des modèles de paysage similaires à l’aide de données d’imagerie satellitaire et de modèles CNN de pointe) et (3) composante météorologique (modélisation des corrélations entre les mesures météorologiques et les modèles de trafic). De plus, nous étudions les effets et les limites de l’utilisation de tels ensembles de données contextuelles sur le processus d’apprentissage des séries chronologiques. Nos expériences montrent que de tels modèles hybrides ne conduisent pas toujours à de meilleures performances, et le modèle LSTM est capable de modéliser des interactions séquentielles complexes. Cependant, il est possible de classer ou d’étiqueter les régions en fonction de leur paysage urbain et du trafic du réseau.
322

Mediální obraz krymské krize ve zpravodajství Russia Today, CNN a ČT24 / Media image of the crimean crisis on Russia Today, CNN and ČT24 news

Štěpán, Petr January 2015 (has links)
This thesis analyses how three television stations - Czech ČT24, Russian RT and American CNN - informed about the Crimean crisis which took place in Ukraine in 2014. The first part of the thesis presents theoretical approach and mentions previous similar studies, which focused on examining of medial coverage and framing of war conflicts. Next chapter describes the history of Ukraine briefly and underlines events which could have caused the Crimean crisis. Thereafter the thesis introduces the timeline of the Crimean crisis. In the next part the thesis analyses sources, topics and keywords which appeared in the news of ČT24, RT and CNN. It also describes how particular people and events were visually covered. In the final chapter the approach of the three examined television channels is compared.
323

Super-Resolution for Fast Multi-Contrast Magnetic Resonance Imaging

Nilsson, Erik January 2019 (has links)
There are many clinical situations where magnetic resonance imaging (MRI) is preferable over other imaging modalities, while the major disadvantage is the relatively long scan time. Due to limited resources, this means that not all patients can be offered an MRI scan, even though it could provide crucial information. It can even be deemed unsafe for a critically ill patient to undergo the examination. In MRI, there is a trade-off between resolution, signal-to-noise ratio (SNR) and the time spent gathering data. When time is of utmost importance, we seek other methods to increase the resolution while preserving SNR and imaging time. In this work, I have studied one of the most promising methods for this task. Namely, constructing super-resolution algorithms to learn the mapping from a low resolution image to a high resolution image using convolutional neural networks. More specifically, I constructed networks capable of transferring high frequency (HF) content, responsible for details in an image, from one kind of image to another. In this context, contrast or weight is used to describe what kind of image we look at. This work only explores the possibility of transferring HF content from T1-weighted images, which can be obtained quite quickly, to T2-weighted images, which would take much longer for similar quality. By doing so, the hope is to contribute to increased efficacy of MRI, and reduce the problems associated with the long scan times. At first, a relatively simple network was implemented to show that transferring HF content between contrasts is possible, as a proof of concept. Next, a much more complex network was proposed, to successfully increase the resolution of MR images better than the commonly used bicubic interpolation method. This is a conclusion drawn from a test where 12 participants were asked to rate the two methods (p=0.0016) Both visual comparisons and quality measures, such as PSNR and SSIM, indicate that the proposed network outperforms a similar network that only utilizes images of one contrast. This suggests that HF content was successfully transferred between images of different contrasts, which improves the reconstruction process. Thus, it could be argued that the proposed multi-contrast model could decrease scan time even further than what its single-contrast counterpart would. Hence, this way of performing multi-contrast super-resolution has the potential to increase the efficacy of MRI.
324

Traffic Sign Classification Using Computationally Efficient Convolutional Neural Networks

Ekman, Carl January 2019 (has links)
Traffic sign recognition is an important problem for autonomous cars and driver assistance systems. With recent developments in the field of machine learning, high performance can be achieved, but typically at a large computational cost. This thesis aims to investigate the relation between classification accuracy and computational complexity for the visual recognition problem of classifying traffic signs. In particular, the benefits of partitioning the classification problem into smaller sub-problems using prior knowledge in the form of shape or current region are investigated. In the experiments, the convolutional neural network (CNN) architecture MobileNetV2 is used, as it is specifically designed to be computationally efficient. To incorporate prior knowledge, separate CNNs are used for the different subsets generated when partitioning the dataset based on region or shape. The separate CNNs are trained from scratch or initialized by pre-training on the full dataset. The results support the intuitive idea that performance initially increases with network size and indicate a network size where the improvement stops. Including shape information using the two investigated methods does not result in a significant improvement. Including region information using pretrained separate classifiers results in a small improvement for small complexities, for one of the regions in the experiments. In the end, none of the investigated methods of including prior knowledge are considered to yield an improvement large enough to justify the added implementational complexity. However, some other methods are suggested, which would be interesting to study in future work.
325

Structural priors in deep neural networks

Ioannou, Yani Andrew January 2018 (has links)
Deep learning has in recent years come to dominate the previously separate fields of research in machine learning, computer vision, natural language understanding and speech recognition. Despite breakthroughs in training deep networks, there remains a lack of understanding of both the optimization and structure of deep networks. The approach advocated by many researchers in the field has been to train monolithic networks with excess complexity, and strong regularization --- an approach that leaves much to desire in efficiency. Instead we propose that carefully designing networks in consideration of our prior knowledge of the task and learned representation can improve the memory and compute efficiency of state-of-the art networks, and even improve generalization --- what we propose to denote as structural priors. We present two such novel structural priors for convolutional neural networks, and evaluate them in state-of-the-art image classification CNN architectures. The first of these methods proposes to exploit our knowledge of the low-rank nature of most filters learned for natural images by structuring a deep network to learn a collection of mostly small, low-rank, filters. The second addresses the filter/channel extents of convolutional filters, by learning filters with limited channel extents. The size of these channel-wise basis filters increases with the depth of the model, giving a novel sparse connection structure that resembles a tree root. Both methods are found to improve the generalization of these architectures while also decreasing the size and increasing the efficiency of their training and test-time computation. Finally, we present work towards conditional computation in deep neural networks, moving towards a method of automatically learning structural priors in deep networks. We propose a new discriminative learning model, conditional networks, that jointly exploit the accurate representation learning capabilities of deep neural networks with the efficient conditional computation of decision trees. Conditional networks yield smaller models, and offer test-time flexibility in the trade-off of computation vs. accuracy.
326

Reconfigurable hardware acceleration of CNNs on FPGA-based smart cameras / Architectures reconfigurables pour l’accélération des CNNs. Applications sur cameras intelligentes à base de FPGAs

Abdelouahab, Kamel 11 December 2018 (has links)
Les Réseaux de Neurones Convolutifs profonds (CNNs) ont connu un large succès au cours de la dernière décennie, devenant un standard de la vision par ordinateur. Ce succès s’est fait au détriment d’un large coût de calcul, où le déploiement des CNNs reste une tâche ardue surtout sous des contraintes de temps réel.Afin de rendre ce déploiement possible, la littérature exploite le parallélisme important de ces algorithmes, ce qui nécessite l’utilisation de plate-formes matérielles dédiées. Dans les environnements soumis à des contraintes de consommations énergétiques, tels que les nœuds des caméras intelligentes, les cœurs de traitement à base de FPGAs sont reconnus comme des solutions de choix pour accélérer les applications de vision par ordinateur. Ceci est d’autant plus vrai pour les CNNs, où les traitements se font naturellement sur un flot de données, rendant les architectures matérielles à base de FPGA d’autant plus pertinentes. Dans ce contexte, cette thèse aborde les problématiques liées à l’implémentation des CNNs sur FPGAs. En particulier, ces travaux visent à améliorer l’efficacité des implantations grâce à deux principales stratégies d’optimisation; la première explore le modèle et les paramètres des CNNs, tandis que la seconde se concentre sur les architectures matérielles adaptées au FPGA. / Deep Convolutional Neural Networks (CNNs) have become a de-facto standard in computer vision. This success came at the price of a high computational cost, making the implementation of CNNs, under real-time constraints, a challenging task.To address this challenge, the literature exploits the large amount of parallelism exhibited by these algorithms, motivating the use of dedicated hardware platforms. In power-constrained environments, such as smart camera nodes, FPGA-based processing cores are known to be adequate solutions in accelerating computer vision applications. This is especially true for CNN workloads, which have a streaming nature that suits well to reconfigurable hardware architectures.In this context, the following thesis addresses the problems of CNN mapping on FPGAs. In Particular, it aims at improving the efficiency of CNN implementations through two main optimization strategies; The first one focuses on the CNN model and parameters while the second one considers the hardware architecture and the fine-grain building blocks.
327

Pruning Convolution Neural Network (SqueezeNet) for Efficient Hardware Deployment

Akash Gaikwad (5931047) 17 January 2019 (has links)
<p>In recent years, deep learning models have become popular in the real-time embedded application, but there are many complexities for hardware deployment because of limited resources such as memory, computational power, and energy. Recent research in the field of deep learning focuses on reducing the model size of the Convolution Neural Network (CNN) by various compression techniques like Architectural compression, Pruning, Quantization, and Encoding (e.g., Huffman encoding). Network pruning is one of the promising technique to solve these problems.</p> <p>This thesis proposes methods to prune the convolution neural network (SqueezeNet) without introducing network sparsity in the pruned model. </p> <p>This thesis proposes three methods to prune the CNN to decrease the model size of CNN without a significant drop in the accuracy of the model.</p> <p>1: Pruning based on Taylor expansion of change in cost function Delta C.</p> <p>2: Pruning based on L<sub>2</sub> normalization of activation maps.</p> <p>3: Pruning based on a combination of method 1 and method 2.</p><p>The proposed methods use various ranking methods to rank the convolution kernels and prune the lower ranked filters afterwards SqueezeNet model is fine-tuned by backpropagation. Transfer learning technique is used to train the SqueezeNet on the CIFAR-10 dataset. Results show that the proposed approach reduces the SqueezeNet model by 72% without a significant drop in the accuracy of the model (optimal pruning efficiency result). Results also show that Pruning based on a combination of Taylor expansion of the cost function and L<sub>2</sub> normalization of activation maps achieves better pruning efficiency compared to other individual pruning criteria and most of the pruned kernels are from mid and high-level layers. The Pruned model is deployed on BlueBox 2.0 using RTMaps software and model performance was evaluated.</p><p></p>
328

Efficiency of CNN on Heterogeneous Processing Devices

Ringenson, Josefin January 2019 (has links)
In the development of advanced driver assistance systems, computer vision problemsneed to be optimized to run efficiently on embedded platforms. Convolutional neural network(CNN) accelerators have proven to be very efficient for embedded camera platforms,such as the ones used for automotive vision systems. Therefore, the focus of this thesisis to evaluate the efficiency of a CNN on a future embedded heterogeneous processingdevice. The memory size in an embedded system is often very limited, and it is necessary todivide the input into multiple tiles. In addition, there are power and speed constraintsthat needs to be met to be able to use a computer vision system in a car. To increaseefficiency and optimize the memory usage, different methods for CNN layer fusion areproposed and evaluated for a variety of tile sizes. Several different layer fusion methods and input tile sizes are chosen as optimal solutions,depending on the depth of the layers in the CNN. The solutions investigated inthe thesis are most efficient for deep CNN layers, where the number of channels is high.
329

Utrikesbevakning : – påverkar media agerandet i internationella kriser?

Andrésson, Charlotta January 2007 (has links)
<p>Abstract</p><p>Title: Foreign news coverage. Does the media influence the action in international crises? (Utrikesbevakning. Påverkar media agerandet i internationella kriser?)</p><p>Number of pages: 39</p><p>Author: Charlotta Andrésson</p><p>Tutor: Professor Lowe Hedman</p><p>Course: Media and Communication Studies C</p><p>University: Division of Media and Communication, Department of Information Science, Uppsala University.</p><p>Date of submission: 2007-01-03, autumn term of 2006</p><p>Purpose/Aim</p><p>The purpose of the essay is partly to examine if foreign news coverage influence the political agenda setting and the incentives of the public’s willingness to give charity for humanitarian crises. It is also to answer if the media are responsible for the possible consequences of the news coverage. My main questions at issue are:</p><p>1. Does the foreign news coverage influence the political agenda setting and the incentives of the public’s willingness to give charity for humanitarian crises?</p><p>2. Is media responsible for the possible consequences of their foreign news coverage?</p><p>I also ask a question at issue in a research of Swedish foreign news coverage in my essay to get a clearer picture of the foreign news coverage:</p><p>3. How does Swedish foreign news coverage relate to prior research?</p><p>Method:</p><p>The second chapter of the essay is a literature research of news selection and news values. The third chapter of the essay is a research of media’s influence on the world politics and humanitarian aid. These two chapters are literature studies based on prior research, theories and debates. The fourth chapter is an empirical study of a news programme on a Swedish TV-channel during a five months period between 2004 and 2005. My interest in the empirical study was to examine how the material was divided geographically and as regards contents. The fifth and sixth chapter of the essay consists of an analysis and a discussion.</p><p>Main results:</p><p>As my main result I concluded that the media influence the political agenda setting and the the incentives of the public’s willingness to give charity for humanitarian crises. The media throw light upon which crises that should be given priority to. The theories for news selection and news value agrees with the result of my research of Swedish foreign news coverage. I also concluded that the media alone was not responsible for the possible consequences for their foreign news coverage but that they are the premier channel of information about the world for most people.</p><p>Keywords: Foreign news, news selection and news value, CNN-effect, Media and political agenda setting, Media influence of humanitarian aid.</p>
330

Utrikesbevakning : – påverkar media agerandet i internationella kriser?

Andrésson, Charlotta January 2007 (has links)
Abstract Title: Foreign news coverage. Does the media influence the action in international crises? (Utrikesbevakning. Påverkar media agerandet i internationella kriser?) Number of pages: 39 Author: Charlotta Andrésson Tutor: Professor Lowe Hedman Course: Media and Communication Studies C University: Division of Media and Communication, Department of Information Science, Uppsala University. Date of submission: 2007-01-03, autumn term of 2006 Purpose/Aim The purpose of the essay is partly to examine if foreign news coverage influence the political agenda setting and the incentives of the public’s willingness to give charity for humanitarian crises. It is also to answer if the media are responsible for the possible consequences of the news coverage. My main questions at issue are: 1. Does the foreign news coverage influence the political agenda setting and the incentives of the public’s willingness to give charity for humanitarian crises? 2. Is media responsible for the possible consequences of their foreign news coverage? I also ask a question at issue in a research of Swedish foreign news coverage in my essay to get a clearer picture of the foreign news coverage: 3. How does Swedish foreign news coverage relate to prior research? Method: The second chapter of the essay is a literature research of news selection and news values. The third chapter of the essay is a research of media’s influence on the world politics and humanitarian aid. These two chapters are literature studies based on prior research, theories and debates. The fourth chapter is an empirical study of a news programme on a Swedish TV-channel during a five months period between 2004 and 2005. My interest in the empirical study was to examine how the material was divided geographically and as regards contents. The fifth and sixth chapter of the essay consists of an analysis and a discussion. Main results: As my main result I concluded that the media influence the political agenda setting and the the incentives of the public’s willingness to give charity for humanitarian crises. The media throw light upon which crises that should be given priority to. The theories for news selection and news value agrees with the result of my research of Swedish foreign news coverage. I also concluded that the media alone was not responsible for the possible consequences for their foreign news coverage but that they are the premier channel of information about the world for most people. Keywords: Foreign news, news selection and news value, CNN-effect, Media and political agenda setting, Media influence of humanitarian aid.

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