12 research outputs found
An Object Detection and Identification System for a Mobile Robot Control
The one of the features of mobile robot control is to detect and to identify objects in workspace. Especially, autonomous systems must detect obstacles and then revise actual trajectories according to new conditions. Hence, many solutions and approaches can be found in literature. Different sensors and cameras are used to solve problem by many researchers. Different type sensors usage can affect not only system performance but also operational cost. In this study, single camera based obstacle detection and identification algorithm was developed to control omni-drive mobile robot systems. Objects and obstacles, which are in robot view, are detected and identified their coordinates by using developed algorithms dynamically. Developed algorithm was tested on Festo Robotino mobile robot. Proposed approach offers not only cost efficiency but also short process time
Sequential Monte Carlo Samplers For Nonparametric Bayesian Mixture Models
Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2012Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2012Bu çalışmanın temel amacı, parametrik olmayan Bayesçi model seçim teknikleri içinde önemli bir yere sahip olan Dirichlet süreci karışım modelleri (DPM) için etkin ardışık Monte Carlo (SMC) örnekleyiciler tasarlamaktır. Tasarlanan algoritmalar, önerilen sınıf güncelleme metotları sayesinde, yeni gelen gözlemlerin ışığında parçacık gezingelerinde değişiklik yaparak gerçek DPM sonsal dağılımına daha iyi bir yaklaşıklık sağlamaktadır. Önerilen metot, DPM sonsal dağılımının çözümünde kullanılan diğer ardışık Monte Carlo örnekleyicileri genelleme özelliğe sahiptir. Tek ve çok boyutlu olasılık dağılımı kestirim problemlerinde yapılan değerlendirmelerde, özellikle sonsal dağılımın izole modlara sahip olduğu koşullarda, önerilen metodun klasik metotlara göre çok daha yüksek doğrulukta sonuca yakınsayabildiği görülmüştür. Ayrıca, manevralı hedeflerin takibinde ortaya atılan en yenilikçi modellerden biri olan değişken oranlı parçacık süzgeçleri (VRPF) tezde ele alınmış ve çoklu model yaklaşımları değişken oranlı modeller ile birleştirilerek, takip başarımını arttıran çoklu model değişken oranlı parçacık süzgeçleri (MM-VRPF) önerilmiştir. Çoklu model yaklaşımının manevralı hedef gezingelerini daha iyi modellediği benzetim sonuçları ile gösterilmiştir.In this thesis, we developed a novel online algorithm for posterior inference in Dirichlet Process Mixture (DPM) models that is based on the sequential Monte Carlo (SMC) samplers framework. The proposed method enables us to design new clustering update schemes, such as updating past trajectories of the particles in light of recent observations, and still ensures convergence to the true DPM posterior distribution asymptotically. Our method generalizes many sequential importance sampling based approaches and provides a computationally efficient improvement to particle filtering that is less prone to getting trapped in isolated modes. Performance has been evaluated in univariate and multivariate infinite Gaussian mixture density estimation problems. It is shown that the proposed algorithm outperforms conventional Monte Carlo approaches in terms of estimation variance and average log-marginal. Moreover, in this thesis we dealt with the maneuvering target tracking problem. We incorporated multiple model approach with the recently introduced variable rate particle filters (VRPF) in order to improve the tracking performance. The proposed variable rate model structure, referred as Multiple Model Variable Rate Particle Filter (MM-VRPF) results in a much more accurate tracking.DoktoraPh
Calibration of a 3D environmet scanner with a pair of line lasers
20th Signal Processing and Communications Applications Conference, SIU 2012; Fethiye, Mugla; Turkey; 18 April 2012 through 20 April 20123B lazer tarayıcılar yüzey geometrisinin yakalanması için yaygın olarak kullanılan sistemlerdir. Geleneksel lazer tarayıcı sistemler bir adet lazer ışık kaynağına sahiptir. Bu çalışmada iki adet lazer ışık kaynağına sahip bir 3B lazer tarayıcı ele alınmıştır. Bu tarayıcı özellikle sahnelerdeki örtme etkisinin en küçüklenebilmesini sağlamaktadır. Ancak birden fazla lazer kaynağına sahip lazer tarayıcılar için kalibrasyon önemli bir problem olmaktadır. Çalışmamızda bu sistemlerde karşılaşılan kalibrasyon problemi tanımlanmıştır. Bu problemin çözümü için taranan sahnelerdeki dikgenlik, eş-düzlemsellik bilgileri kullanılmıştır.3D laser scanners are widely used systems to capture surface geometry. Conventional laser scanners have one laser source. In this study, a laser scanner systems with two laser sources is considered. The scanner is capable of minimizing the effect of occlusion in the scene. But the calibration issue becomes more complicated for scanners having more than one laser source. In our study the calibration problem of such scanners are defined. Some scene specific informations like orthogonalities, co-planarities are used for solving this problem. © 2012 IEEE
Spatial and Temporal Sentiment Analysis of Twitter data
The public have used Twitter world wide for expressing opinions. This study focuses on spatio-temporal variation of georeferenced Tweets’ sentiment polarity, with a view to understanding how opinions evolve on Twitter over space and time and across communities of users. More specifically, the question this study tested is whether sentiment polarity on Twitter exhibits specific time-location patterns. The aim of the study is to investigate the spatial and temporal distribution of georeferenced Twitter sentiment polarity within the area of 1 km buffer around the Curtin Bentley campus boundary in Perth, Western Australia. Tweets posted in campus were assigned into six spatial zones and four time zones. A sentiment analysis was then conducted for each zone using the sentiment analyser tool in the Starlight Visual Information System software. The Feature Manipulation Engine was employed to convert non-spatial files into spatial and temporal feature class. The spatial and temporal distribution of Twitter sentiment polarity patterns over space and time was mapped using Geographic Information Systems (GIS). Some interesting results were identified. For example, the highest percentage of positive Tweets occurred in the social science area, while science and engineering and dormitory areas had the highest percentage of negative postings. The number of negative Tweets increases in the library and science and engineering areas as the end of the semester approaches, reaching a peak around an exam period, while the percentage of negative Tweets drops at the end of the semester in the entertainment and sport and dormitory area. This study will provide some insights into understanding students and staff ’s sentiment variation on Twitter, which could be useful for university teaching and learning management
Zuverlässigkeitsbewertung von Fahrzeug-zu-Fahrzeug Kommunikation
V2V communication enables a plethora of cooperative applications aimed at reducing road hazard situations as well as enhancing traffic efficiency and individual driving
comfort, expanding therewith the boundaries of Advanced Driver Assistance Systems (ADAS). These applications will be supported by IEEE 802.11p, a standard operating in the 5.9GHz frequency band and adapted for the highly dynamic vehicular environment.
The focus of this work is V2V safety applications, which have already gained a major attention from the industry, academia, as well as standardization bodies. Being a subject of wireless communication the performance of V2V applications directly depends on the communication link quality and the packet distribution pattern. Therefore, the main purpose of this thesis is to develop an effective communication link reliability assessment method and analyze to what extent V2V communication is feasible to satisfy the reliability requirements of safety applications. Furthermore, we investigate the effectiveness of the proposed assessment method when applied for real-time communication link reliability prediction.
In particular, in this work we establish the link between classical network performance metrics and specific application reliability requirements and derive a set of
advanced assessment metrics. Afterwards, we investigate through these metrics how different environmental factors affect application reliability based on the measurement
data, which was obtained in elaborated real-world measurement campaigns and in different non-line-of-sight scenarios. Using the suggested metrics further in this work we additionally analyze the achievable application reliability of the V2V safety applications in congested network scenarios through the simulation study. Based on these
results we also define the most favorable combinations of the network parameters to support reliable operation of these applications.
Finally, in this thesis we examine to what extent the suggested metrics are suitable for applications while operating in real time. We develop and implement two frameworks for prediction of the communication link reliability, based on the data that was obtained over the 4.5 months of the simTD project field trials. Furthermore, we apply both frameworks to other measurement data, which was obtained outside the simTD project and assess the effectiveness of both frameworks under independent realistic conditions.Car2Car-Kommunikation ermöglicht eine Vielzahl von kooperativen Anwendungen, welche auf die Unfallverminderung, Verbesserung der Verkehrseffizienz sowie den individuellen Fahrkomfort abzielen und damit die Grenzen von aktiven Fahrerassistenzsystemen erweitern. Im Fokus dieser Dissertation stehen Car2Car-Sicherheitsanwendungen, denen heutzutage bereits große Aufmerksamkeit von Seiten der Industrie, Forschung und diversen Normierungsgremien geschenkt wird. Da alle diese Anwendungen auf drahtloser Kommunikation basieren, ist ihre Leistungsfähigkeit direkt von der Qualität der Kommunikationsverbindung sowie dem Paketverteilungsmuster abhängig. Daher liegt der Hauptfokus dieser Arbeit in der Entwicklung effektiver Methoden zur Bewertung der Kommunikationszuverlässigkeit und der Analyse, inwieweit Car2Car-Kommunikation im Allgemeinen die Anforderungen von Sicherheitsanwendungen erfüllt. Darüber hinaus untersucht diese Doktorarbeit die Effektivität der hier vorgeschlagenen Bewertungsmethoden in Bezug auf die Vorhersage der Kommunikationszuverlässigkeit in Echtzeit-Szenarien.
Im Speziellen verbindet diese Arbeit die Welt der klassischen Netzwerkperformance-Metriken mit Car2Car-Anwendungsspezifischen Zuverlässigkeitsanforderungen und stellt als Ergebnis eine Reihe effektiver Bewertungskennzahlen vor. Mithilfe der vorgeschlagenen Metriken wird des Weiteren untersucht, inwieweit verschiedene Umweltfaktoren die Anwendungszuverlässigkeit beeinflussen können. Diese Untersuchung basiert auf Messdaten, die in ausführlichen Feldversuchen in verschiedenen Non-Line-of-Sight-Szenarien gewonnen wurden. Im nächsten Schritt analysiert diese Doktorarbeit die erreichbare Zuverlässigkeit der Car2Car-Sicherheitsanwendungen in Netzwerküberlastungsszenarien anhand einer Simulationsstudie. Als Ergebnis werden die spezifischen Kombinationen der verschiedenen Netzwerkparameter definiert, die einen zuverlässigen Betrieb der Car2Car-Sicherheitsanwendungen gewährleisten können.
Zum Abschluss untersucht diese Dissertation, inwieweit die vorgeschlagenen Metriken für die im Echtzeit-Modus funktionierenden Anwendungen geeignet sind. Darüber hinaus
werden zwei Frameworks entwickelt und implementiert, welche die Zuverlässigkeit der Kommunikationsverbindung prädizieren. Dies geschieht basierend auf Daten, die während der 4.5 Monate dauernden Feldversuche im Rahmen des simTD Projektes gewonnen wurden. Beide Frameworks werden am Ende anhand unabhängiger Messdaten auf ihre Funktionalität unter realistischen Bedingungen getestet
European Handbook of Crowdsourced Geographic Information
"This book focuses on the study of the remarkable new source of geographic information that has become available in the form of user-generated content accessible over the Internet through mobile and Web applications. The exploitation, integration and application of these sources, termed volunteered geographic information (VGI) or crowdsourced geographic information (CGI), offer scientists an unprecedented opportunity to conduct research on a variety of topics at multiple scales and for diversified objectives. The Handbook is organized in five parts, addressing the fundamental questions: What motivates citizens to provide such information in the public domain, and what factors govern/predict its validity?What methods might be used to validate such information? Can VGI be framed within the larger domain of sensor networks, in which inert and static sensors are replaced or combined by intelligent and mobile humans equipped with sensing devices? What limitations are imposed on VGI by differential access to broadband Internet, mobile phones, and other communication technologies, and by concerns over privacy? How do VGI and crowdsourcing enable innovation applications to benefit human society?
Chapters examine how crowdsourcing techniques and methods, and the VGI phenomenon, have motivated a multidisciplinary research community to identify both fields of applications and quality criteria depending on the use of VGI. Besides harvesting tools and storage of these data, research has paid remarkable attention to these information resources, in an age when information and participation is one of the most important drivers of development.
The collection opens questions and points to new research directions in addition to the findings that each of the authors demonstrates. Despite rapid progress in VGI research, this Handbook also shows that there are technical, social, political and methodological challenges that require further studies and research.
HISTORY URBANISM RESILIENCE VOLUME 03:
The 17th conference (2016, Delft) of the International Planning History Society (IPHS) and its proceedings place presentations from different continents and on varied topics side by side, providing insight into state-of-the art research in the field of planning history and offering a glimpse of new approaches, themes, papers and books to come.
VOLUME 03: Change and Responsive Plannin
Synthesis of new pyrazolium based tunable aryl alkyl ionic liquids and their use in removal of methylene blue from aqueous solution
In this study, two new pyrazolium based tunable aryl alkyl ionic liquids, 2-ethyl-1-(4-methylphenyl)-3,5- dimethylpyrazolium tetrafluoroborate (3a) and 1-(4-methylphenyl)-2-pentyl-3,5-dimethylpyrazolium tetrafluoroborate (3b), were synthesized via three-step reaction and characterized. The removal of methylene blue (MB) from aqueous solution has been investigated using the synthesized salts as an extractant and methylene chloride as a solvent. The obtained results show that MB was extracted from aqueous solution with high extraction efficiency up to 87 % at room temperature at the natural pH of MB solution. The influence of the alkyl chain length on the properties of the salts and their extraction efficiency of MB was investigated