604 research outputs found
Some Theoretical Results on the Progeny of a Bisexual Galton-Watson Branching Process
A Superadditive Bisexual Galton-Watson Branching Process
is considered and the total number of mating units, females and males,
until the n-th generation, are studied. In particular some results about
the stochastic monotony, probability generating functions and moments are
obtained. Finally, the limit behaviour of those variables suitably normed is
investigated
Rapid Prototyping for Evaluating Vehicular Communications
[Abstract] This Thesis details the different elements of a rapid prototyping system able to
implement and evaluate vehicular communications fast, according to the continuously
evolving requirements of the industry. The system is basically composed of a testbed
and a channel emulator, which allow evaluating communication transceivers in realistic
vehicular scenarios.
Two different testbeds are introduced: a generic 2x2 system and a vehicular platform.
The former is used to compare and study space-time block coding (STBC) transmissions
at 2.4 GHz over different indoor channels. The latter makes use of software
transceivers whose performance is evaluated when they work under artificial high-speed
Rayleigh-fading scenarios.
To show the capabilities of both platforms, three software transceivers have been
developed following the specifications for the physical layers of the standards IEEE
802.11p, IEEE 802.11a and IEEE 802.16e (Mobile WiMAX). The present work details
the different elements that make up each transceiver and indicates how to connect them
to the rest of the system to perform evaluation measurements.
Finally, single-antenna and multi-antenna performances are measured thanks to the
design and implementation of three FPGA-based channel emulators that are able to
recreate up to seven different vehicular scenarios that include urban canyons, suburban
areas and highways[Resumo] A presente Tese detalla os elementos necesarios para constituir un sistema basado en
prototipado rápido capaz de levar a cabo e avaliar comunicacións vehiculares. O hardware
do sistema está composto básicamente por unha plataforma de probas (testbed)
e un emulador de canal, os cales permiten avaliar o rendemento de transceptores
inartiamicos recreando diferentes escenarios vehiculares.
Inicialmente, este traballo céntrase na descripción do hardware do sistema, detallando
a construcción e proba dunha plataforma multi-antena e un testebed vehicular.
Estos sistemas permitiron, respectivamente, estudar o comportamento de códigos STBC
(space-time block codes) en interiores e medir o rendemento de tranceptores software
ao traballar a distintas velocidades vehiculares en canais con desvaecemento Rayleigh.
Tres transceptores software foron creados seguindo as especificacións das capas
físicas dos estándares IEEE 802.11p, IEEE 802.11a e IEEE 802.16e (Mobile WiMAX).
Este traballo detalla os diferentes componentes de cada transceptor, indicando cómo
conectalos ao resto do sistema para realizar a avaliacition do seu rendemento. Dita
avaliación realizouse coa axuda de tres emuladores de canal basados en tecnoloxía
FPGA (Field Programmable Gate Array), os cales son capaces de recrear ata sete
escenarios vehiculares distintos, incluindo cañóns urbanos, zonas suburbanas e autopistas.[Resumen] La presente Tesis detalla los elementos necesarios para constituir un sistema basado
en prototipado rtiapido capaz de llevar a cabo y evaluar comunicaciones vehiculares.
El hardware del sistema está compuesto por una plataforma de pruebas (testbed) y
un emulador de canal, los cuales permiten evaluar el rendimiento de transceptores
inaltiambricos recreando diferentes escenarios vehiculares.
Inicialmente, este trabajo se centra en la descripcition del hardware del sistema,
detallando la construccition y prueba de una plataforma multi-antena y un testebed
vehicular. Estos sistemas han permitido, respectivamente, estudiar el comportamiento
de ctiodigos STBC (space-time block codes) en interiores y medir el rendimiento en
canal con desvanecimiento Rayleigh de tranceptores software a distintas velocidades
vehiculares.
Tres transceptores software han sido creados siguiendo las especificaciones de las
capas físicas de los estandares IEEE 802.11p, IEEE 802.11a e IEEE 802.16e (Mobile
WiMAX). Este trabajo detalla los diferentes componentes de cada transceptor,
indicando ctiomo conectarlos al resto del sistema para realizar la evaluacition de su
rendimiento. Dicha evaluacition se realiztio con la ayuda de tres emuladores de canal
basados en FPGAs (Field Programmable Gate Array), los cuales son capaces de recrear
comunicaciones multi-antena en hasta siete escenarios vehiculares distintos, incluyendo
cañones urbanos, zonas suburbanas y autopistas
Myositis and Cancer
The idiopathic inflammatory myopathies (IIM), classically dermatomyositis (DM),
polymyositis (PM), and inclusion body myositis (IBM), are acquired systemic autoimmune
disorders defined by chronic muscle weakness and inflammation of unknown aetiology.
The combination of clinical, laboratory, electromyographic, and histological features is the
basis of diagnosis, as well as exclusion of several mimicking conditions (Bohan & Peter,
1975; Dalakas & Hohlfeld, 2003; Mann et al, 2010; Mastaglia & Phillips, 2002). IIM are the
most common causes of acquired muscle disease in adults, but are still rare conditions with
an estimated overall prevalence of 50 to 100 cases per million (Oddis et al., 1990; Prieto &
Grau 2010; Wilson et al., 2008).
In recent years, taking into account additional clinical, immunological and histological
features, new phenotypes among IIM, such as antisynthetase syndrome, autoimmune
necrotizing myopathy, connective tissue disorder-associated myositis, or cancer-associated
myositis (CAM), have been described (Cox et al., 2010; Dalakas, 2010; Dimachkie, 2011;
Rider & Miller, 2011; Targoff, 2008).
The association between cancer and IIM has been widely reported in the medical literature,
particularly in DM patients (Buchbinder et al., 2001; Sigurgeirsson et al., 1992). Cancer
screening is a common practice in patients recently diagnosed with IIM, but there is not
consensus about how, and how often screening should be performed. The aim of this
chapter is to describe the epidemiological, clinical, laboratory, and histological reported
features about CAM, to analyze the current potentially approach to preclude malignancy in
IIM, and to provide an advisable algorithm in the diagnosis of occult cancer in myositis
Interferometric inverse synthetic aperture radar experiment using an interferometric linear frequency modulated continuous wave millimetre-wave radar
D. Felguera-Martín,1 J.-T. González-Partida,1 P. Almorox-González,1 M. Burgos-García,1 and B.-P. Dorta-Naranjo2
1Universidad Politécnica de Madrid, Ciudad Universitaria s/n, Grupo de Microondas y Radar. Departamento de Señales, Sistemas y Radiocomunicaciones, Madrid, Spain
2Universidad de Las Palmas de Gran Canaria, Departamento de Señales y Comunicaciones, Las Palmas de Gran Canaria, Spain
An interferometric linear frequency modulated continuous wave (LFMCW) millimetre-wave radar is presented, along with the results of an experiment conducted to study the feasibility of using it in a future millimetre-wave interferometric inverse synthetic aperture radar (InISAR) system. First, a description of the radar is given. Then, the signal processing chain is described, with special attention to the phase unwrapping technique. The interferometric phase is obtained by unwrapping the prominent target's phase in each antenna using a sliding frame processing technique. Cell migration issues in this method are also addressed. Simulations were carried out to illustrate and assess the processing chain and to show the effects of multipath echoes on the height measurement. In the real experiment, the range, speed and height of a moving target were tracked over consecutive inverse synthetic aperture radar (ISAR) image frames, verifying the performance of the whole system
Ferromagnetism in bulk Co-Zn-O
The origin of ferromagnetism in diluted magnetic semiconductors is still an open question, yielding a great deal of research across the world. This work focuses on the Co-Zn-O system. Room-temperature ferromagnetism is observed after a partial reaction of Co_3O_4 and ZnO, which can be ascribed neither to carrier mediation nor segregated cobalt metallic clusters. Another mechanism is yielding room-temperature ferromagnetism. This mechanism is associated with a partial reaction of ZnO and Co_3O_4 grains, and always appears when the starting phases (Co_3O_4 and ZnO) are present in the sample, suggesting that interfaces are involved in the origin of the observed ferromagnetism
Electronically Tunable Phase Response for Phased array Patches
The design and prototyping of radiating elements with tunable phase response, for reconfigurable patch array antennas, is presented. Different options are found in the technical literature to obtain feasible reconfigurable array antennas: placing the active circuitry in the transmission lines or directly over the radiating element, obtaining the desired phase shift for each radiating element of the array. In this reported work, the second option is selected and active radiating elements at 12 GHz are designed and prototyped
- …