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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.
1

Accurate Target Geolocation and Vision-Based Landing with Application to Search and Engage Missions for Miniature Air Vehicles

Barber, Duncan B. 22 February 2007 (has links) (PDF)
Miniature air vehicles (MAVs) have attracted a large amount of interest recently both from the research community and from the public. New battery technologies as well as rapid developments in embedded processing and MEMS sensor technologies have greatly increased the potential of these vehicles. MAVs have been envisioned playing significant roles in both civil and military applications. Examples include: fire monitoring, search and rescue, traffic monitoring, crop monitoring, convoy protection, border surveillance, troop support, law enforcement, natural disaster relief, and aerial photography. The application of MAVs tends to center on the ability of the MAV to collect and deliver visual information to the user. In many applications it is important to be able to accurately geolocate items of interest in the visual data. However, the inaccuracies associated with MAV platforms have led to relatively large errors in previous attempts at geolocation. The first half of this thesis focuses on increasing the accuracy of geolocation estimates achievable using a hand-launchable MAV. To accomplish this, methods are presented for bias estimation, wind estimation, recursive least squares filtering, and optimal flight path generation. Hardware results are presented which demonstrate the ability to consistently localize targets to within 5 m regardless of wind conditions. The second half of this thesis focuses on using the high accuracy geolocation estimates to complete a search and engage mission. This is a mission in which the MAV not only locates the target, but also accurately delivers a payload to the target site. The focus is on delivering an attached payload via accurate landing at the target site. A vision-based landing approach is presented which is robust to both wind and moving targets. Simulation results are presented which demonstrate the effectiveness of the control.
2

Implementace BI v oblasti geolokačních dat / Implementation of BI in the field of geolocation data

Rosenberger, Tomáš January 2014 (has links)
The thesis deals with the theoretical and practical aspects of implementation of Business Intelligence in a field of geo-location data with emphasis on the design and implementation of data architecture and the development of dynamic dashboards. The whole issue is described on the development of a tool for the analysis of geo-location data, on which the author participated with other members of the Competence Center Retail Analytics - Ondrej Funiok, Vilem Kalus and Martin Matejka. The first part of the thesis describes the theoretical bases of Business and Location Intelligence, which is followed by a description of the basic tasks of working with geo-location data - data storage in relational database management systems, data processing by map servers and data presentation. Individual tasks are described with practical examples and use software tools to support these tasks. The next section presents the project of development tool for the analysis of geo-location data that is created in the Retail Analytics Competence Center at the University of Economics, Prague. The second part of the thesis describes the design and implementation of the data architecture of developed tool, which is followed by a description of the frontend portion of the tool consisting of the implementation of a library for creating dynamic Dashboards to present geo-location data.
3

Indoor Geo-location And Tracking Of Mobile Autonomous Robot

Ramamurthy, Mahesh 01 January 2005 (has links)
The field of robotics has always been one of fascination right from the day of Terminator. Even though we still do not have robots that can actually replicate human action and intelligence, progress is being made in the right direction. Robotic applications range from defense to civilian, in public safety and fire fighting. With the increase in urban-warfare robot tracking inside buildings and in cities form a very important application. The numerous applications range from munitions tracking to replacing soldiers for reconnaissance information. Fire fighters use robots for survey of the affected area. Tracking robots has been limited to the local area under consideration. Decision making is inhibited due to limited local knowledge and approximations have to be made. An effective decision making would involve tracking the robot in earth co-ordinates such as latitude and longitude. GPS signal provides us sufficient and reliable data for such decision making. The main drawback of using GPS is that it is unavailable indoors and also there is signal attenuation outdoors. Indoor geolocation forms the basis of tracking robots inside buildings and other places where GPS signals are unavailable. Indoor geolocation has traditionally been the field of wireless networks using techniques such as low frequency RF signals and ultra-wideband antennas. In this thesis we propose a novel method for achieving geolocation and enable tracking. Geolocation and tracking are achieved by a combination of Gyroscope and encoders together referred to as the Inertial Navigation System (INS). Gyroscopes have been widely used in aerospace applications for stabilizing aircrafts. In our case we use gyroscope as means of determining the heading of the robot. Further, commands can be sent to the robot when it is off balance or off-track. Sensors are inherently error prone; hence the process of geolocation is complicated and limited by the imperfect mathematical modeling of input noise. We make use of Kalman Filter for processing erroneous sensor data, as it provides us a robust and stable algorithm. The error characteristics of the sensors are input to the Kalman Filter and filtered data is obtained. We have performed a large set of experiments, both indoors and outdoors to test the reliability of the system. In outdoors we have used the GPS signal to aid the INS measurements. When indoors we utilize the last known position and extrapolate to obtain the GPS co-ordinates.
4

Wireless Communications and Spectrum Characterization in Impaired Channel Environments

Pagadarai, Srikanth 17 January 2012 (has links)
The demand for sophisticated wireless applications capable of conveying information content represented in various forms such as voice, data, audio and video is ever increasing. In order to support such applications, either additional wireless spectrum is needed or advanced signal processing techniques must be employed by the next-generation wireless communication systems. An immediate observation that can be made regarding the first option is that radio frequency spectrum is a limited natural resource. Moreover, since existing spectrum allocation policies of several national regulatory agencies such as the Federal Communications Commission (FCC) restrict spectrum access to licensed entities only, it has been identified that most of the licensed spectrum across time and frequency is inefficiently utilized. To facilitate greater spectral efficiency, many national regulatory agencies are considering a paradigm shift towards spectrum allocation by allowing unlicensed users to temporarily borrow unused spectral resources. This concept is referred to a dynamic spectrum access (DSA). Although, several spectrum measurement campaigns have been reported in the published literature for quantitatively assessing the available vacant spectrum, there are certain aspects of spectrum utilization that need a deeper understanding. First, we examine two complementary approaches to the problem of characterizing the usage of licensed bands. In the first approach, a linear mixed-effects based regression model is proposed, where the variations in percentage spectrum occupancy and activity period of the licensed user are described as a function of certain independent regressor variables. The second approach is based on the creation of a geo-location database consisting of the licensed transmitters in a specific geographical region and identifying the coverage areas that affect the available secondary channels. Both of these approaches are based on the energy spectral density data-samples collected across numerous frequency bands in several locations in the United States. We then study the mutual interference effects in a coexistence scenario consisting of licensed and unclicensed users. We numerically evaluate the impact of interference as a function of certain receiver characteristics. Specifically, we consider the unlicensed user to utilize OFDM or NOFDM symbols since the appropriate subcarriers can be turned off to facilitate non- contiguous spectrum utilization. Finally, it has been demonstrated that multiple-input and multiple-output (MIMO) antennas yield significant throughput while requiring no increase in transmit power or required bandwidth. However, the separation of spectrally overlapping signals is a challenging task that involves the estimation of the channel. We provide results concerning channel and symbol estimation in the scenario described above. In particular, we focus on the MIMO-OFDM transmission scheme and derive capacity lower bounds due to imperfect channel estimation.
5

Vision-Based Localization and Guidance for Unmanned Aerial Vehicles

Conte, Gianpaolo January 2009 (has links)
The thesis has been developed as part of the requirements for a PhD degree at the Artificial Intelligence and Integrated Computer System division (AIICS) in the Department of Computer and Information Sciences at Linköping University.The work focuses on issues related to Unmanned Aerial Vehicle (UAV) navigation, in particular in the areas of guidance and vision-based autonomous flight in situations of short and long term GPS outage.The thesis is divided into two parts. The first part presents a helicopter simulator and a path following control mode developed and implemented on an experimental helicopter platform. The second part presents an approach to the problem of vision-based state estimation for autonomous aerial platforms which makes use of geo-referenced images for localization purposes. The problem of vision-based landing is also addressed with emphasis on fusion between inertial sensors and video camera using an artificial landing pad as reference pattern. In the last chapter, a solution to a vision-based ground object geo-location problem using a fixed-wing micro aerial vehicle platform is presented.The helicopter guidance and vision-based navigation methods developed in the thesis have been implemented and tested in real flight-tests using a Yamaha Rmax helicopter. Extensive experimental flight-test results are presented. / WITAS
6

Developing business model for geo-location database for the operation of cognitive radio in the TV white space bands / TV spektro tuštumų geografinės duomenų bazės verslo modelis

Sukarevičienė, Gintarė 20 June 2012 (has links)
The aim of this thesis is to analyze how technological, economic, political and social factors can be integrated into Business Model for Geo-location database as a controlling entity for operation of Cognitive Radio devices in the TV White Space spectrum range. Tasks of thesis: to perform an analysis of scientific literature in the context of TVWS and to identify technologies of TVWS management, to find factors influencing Geo-location Database Business Model, to put forward Geo-location Database scenarios, to construct classification of Business Model for the Geo-location Database, to provide experimental study of feasibility to deploy distinct classification of Business Model for the distinct scenarios of Geo-location Database. Qualitative methods chosen for the research: exploratory literature analysis, consultations with experts/specialists and conceptual modelling based on scenarios. The exploratory part of the thesis describes existing spectrum shortage problem and presents potential technologies that can solve this problem. The theoretical part of this work introduces research methodology and the concept and principles of Business Model for technology innovation. Analytical part of the thesis seeks to identify potential Business Model configurations for the operations of Geo-location database in the TV White Space spectrum range. This part ends with presenting experimental study of the feasibility of Geo-location Business Model. The final part of the thesis concludes... [to full text] / Šio darbo tikslas – išanalizuoti, kaip technologiniai, ekonominiai, politiniai ir socialiniai faktoriai gali būti integruoti į verslo modelį, skirtą TV spektro tuštumų geografinei duomenų bazei, naudojančiai sumaniojo radijo ryšio sistemas. Tikslui pasiekti išsikelti uždaviniai: atlikti mokslinės literatūros analizę TV spektro tuštumų tema ir identifikuoti spektro tuštumų valdymo technologijas, nustatyti veiksnius, įtakojančius geografinės duomenų bazės verslo modelį, sudaryti geografinės duomenų bazės verslo scenarijus, sudaryti geografinės duomenų bazės verslo modelių klasifikaciją, nustatyti sudarytos verslo modelių klasifikacijos tinkamumą kiekvienam scenarijui bei nustatyti optimalią verslo modelio konfigūraciją. Uždaviniams įgyvendinti taikyti kokybiniai metodai: mokslinės literatūros analizė, konsultacijos su ekspertais bei specialistais, konceptualus modeliavimas, paremtas scenarijų metodu. Pirmoje darbo dalyje aprašomos egzistuojančios spektro trūkumo problemos ir apžvelgiamos potencialios technologijos, kurios gali išspręsti išanalizuotą problemą. Antroji darbo dalis pristato tyrimo metodus ir nagrinėja verslo modelį bei jo principus, galinčius įtakoti technologijos inovaciją. Trečioji darbo dalis siekia identifikuoti ir įvertinti potencialius TV spektro tuštumų geografinės duomenų bazės verslo modelius. Pateikiamos darbo išvados atsižvelgiant į darbo naudingumą, praktiškumą ir esamus apribojimus. Pagrindiniai darbo rezultatai: nustatyta optimali verslo modelių... [toliau žr. visą tekstą]

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