Now showing items 236-255 of 346

    Opportunistic communications in large uncoordinated networks 

    Borràs Pino, Jordi (Date of defense: 2023-01-25)

    (English) The increase of wireless devices offering high data rate services limits the coexistence of wireless systems sharing the same resources in a given geographical area because of inter-system interference. Therefore, ...

    Optical solitons in quadratic nonlinear media and applications to all-optical switching and routing devices 

    Santos Blanco, María Concepción (Date of defense: 1998-03-02)

    Esta tesis constituye un estudio detallado y exhaustivo de las propiedades de una variedad específica de ondas ópticas solitarias. Observadas experimentalmente por primera vez en 1995, estas ondas estan formadas por un ...

    Optimal sizing and operation planning of microgrids and operation analysis of charging stations for electric vehicles 

    Zenginis, Ioannis (Date of defense: 2018-12-20)

    Energy and transportation sectors are going through major changes as a result of technological advances, depletion of fossil fuels and climate change. With regard to the energy sector, the future smart grid is expected to ...

    Optimization and generalization of lifting schemes: application to lossless image compression 

    Solé Rojals, Joel (Date of defense: 2006-06-29)

    This Ph.D. thesis dissertation addresses multi-resolution image decomposition, a key issue in signal processing that in recent years has contributed to the emergence of the JPEG2000 image compression standard. JPEG2000 ...

    Optimization of emerging extended FTTH WDM/TDM PONs and financial overall assessment 

    Chatzi, Sotiria (Date of defense: 2013-11-26)

    Optical access technology has experienced a boost in the last years, thanks to the continuously migrating multimedia services that are offered over the internet. Though the technologies used for deploying Fiber-To-The-x ...

    Optimization of positioning capabilities in wireless sensor networks : from power efficiency to medium access 

    Moragrega Estrany, Anna (Date of defense: 2016-02-04)

    In Wireless Sensor Networks (WSN), the ability of sensor nodes to know its position is an enabler for a wide variety of applications for monitoring, control, and automation. Often, sensor data is meaningful only if its ...

    Optimization of Segmentation-Based Video Sequence Coding Techniques. Application to content based functionalities 

    Morros Rubió, Josep Ramon (Date of defense: 2004-12-23)

    En aquest treball s'estudia el problema de la compressió de video utilitzant funcionalitats basades en el contingut en el marc teòric dels sistemes de codificació de seqüències de video basats en regions. Es tracten ...

    Optimized content caching strategies for multi-access edge computing (MEC)-assisted future cellular networks 

    Ayenew, Tadege Mihretu (Date of defense: 2023-11-21)

    (English) Handling the tsunami of multimedia content is a big challenge for heterogeneous cellular networks. Serving large volumes of content from the central system to end-users, through a bandwidth-limited network, at ...

    Orbital differential SAR interferometry with polarimetric data 

    Monells Miralles, Daniel (Date of defense: 2017-01-18)

    Space-borne Synthetic Aperture Radar (SAR) systems have demonstrated great effectiveness to survey wide areas, independently of the weather conditions and the day/night cycle. One of the most exploited applications is ...

    Parallel scalability of face detection in heterogeneous multithreaded architectures 

    Oro García, David (Date of defense: 2020-11-17)

    Recently, facial recognition systems have become extremely popular and deployments of this technology are now ubiquitous. Applications ranging from access control to automated surveillance of video feeds rely on facial ...

    Parametric region-based foreround segmentation in planar and multi-view sequences 

    Gallego Vila, Jaime (Date of defense: 2013-10-14)

    Foreground segmentation in video sequences is an important area of the image processing that attracts great interest among the scientist community, since it makes possible the detection of the objects that appear in the ...

    Part-based object retrieval with binary partition trees 

    Giró i Nieto, Xavier (Date of defense: 2012-05-31)

    This thesis addresses the problem of visual object retrieval, where a user formulates a query to an image database by providing one or multiple examples of an object of interest. The presented techniques aim both at finding ...

    Pau-synthetic aperture: a new instrument to test potential improvements for future interferometric radiometers 

    Ramos Pérez, Isaac (Date of defense: 2012-02-27)

    The Soil Moisture and Ocean Salinity (SMOS) mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA). It was a direct response to the global observations of soil moisture and ocean salinity. ...

    Perfomance limits of spatial multiplexing mimo systems 

    García Ordoñez, Luis (Date of defense: 2009-05-06)

    Los canales multiple-input multiple-output (MIMO) proporcionan una forma abstracta y general de modelar un gran número de sistemas de comunicaciones. Los canales MIMO inalámbricos, en concreto, han despertado un gran interés ...

    Phase synchronization scheme for very long baseline coherent arrays 

    Merlano Duncan, Juan Carlos (Date of defense: 2012-07-26)

    Precise phase synchronization of clock or local oscillator signals over distributed systems is a recurring requirement in the design of a wide range of systems, with applications in telecommunications and, for example, in ...

    Photonic devices for next generation fiber-to-the-home access network 

    Chu, Guang Yong (Date of defense: 2016-02-22)

    It would be unaffordable if the WDM-PON technologies were directly applied for massive deployment. Hence, the potential WDM-PON is to be integrated and improved in order to adapt it for NGPON and the future 5G. The UDWDM-PON ...

    Polar coding for the wiretap broadcast channel 

    Olmo Alòs, Jaume del (Date of defense: 2019-10-22)

    In the next era of communications, where heterogeneous, asynchronous and ultra-low latency networks are drawn on the horizon, classical cryptography might be inadequate due to the excessive cost of maintaining a public-key ...

    Polarimetric differential SAR Interferometry with ground-based sensors 

    Pipia, Luca (Date of defense: 2009-09-18)

    Las técnicas de Interferometría Diferencial se basan en la combinación de varias imágenes SAR con distinta separación temporal y permiten la recuperación de las componentes lineales y no-lineales del proceso de deformación ...

    Polarization and index modulations : a theoretical and practical perspective 

    Henarejos Hernández, Pol (Date of defense: 2017-07-19)

    Radiocommunication systems have evolved significantly in recent years in order to meet present and future demands. Historically, time, frequency and more recently, spatial dimensions have been used to improve capacity and ...

    Post-processing methods for ocean monitoring in sar images 

    Tello Alonso, Maria Victoria (Date of defense: 2011-02-07)

    In the recent years, a wide interest has been focused on research and development for the operational use of satellite remote sensing tools for Earth observation. Among different types of sensors, Synthetic Aperture Radars ...