572 research outputs found
Organic semiconductors: The effect of small modifications on device performance
Invited oral presentationIn the search on new high-mobiliity semiconductors with ambipolar performances, good processability and excellent environmental stability, diverse synthetic strategies have been approached. One of the most widely used consists in the alternation of donor and acceptor moieties in the conjugated skeleton, which allows fine tuning of the frontier molecular orbitals. For OTFT applications,low-lying HOMOs are essential to resist air oxidation and thus increase device stability. However, if the HOMO energy is too low, the resulting barrier to hole injection may compromise the transistor performance. Thus, a delicate balance between these two effects is needed. Furthermore, high performance solution-processable materials require the correct selection and positioning of the specific solubilizing substituents in order to achieve proper HOMO and LUMO energy levels, planar molecular conformations, close intermolecular pi-pi stacking, and proper thin film crystallinity. In this communication, several examples of molecular and polymeric materials where modifications on their conjugated skeletons, donor/acceptor subunits ratio and/or the selection of proper alkyl solubilizing chains induce noticeable changes in their electronic performances.Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tec
A WiMAX Conformal Broad-Beam Antenna
[Abstract] The numerical model of a very simple conformal antenna, prepared to work in the 3.4 to 3.6 GHz WiMAX range, is presented. The pattern radiated by the proposed antenna displays high gain and excellent linear polarization within the broad coverage zone.Xunta de Galicia; 09TIC008105PRXunta de Galicia; 07TIC002206PRMinisterio de Ciencia e Innovación; TEC2007-68020-C04-01Ministerio de Ciencia e Innovación; TEC2008-04485Ministerio de Ciencia e Innovación; CSD2008-00010
A challenging coexistence of central diabetes insipidus and cerebral salt wasting syndrome: A case report
Background: Combined central diabetes insipidus and cerebral salt wasting syndrome is a rare clinical finding. However, when this happens, mortality is high due to delayed diagnosis and/or inadequate treatment. Case presentation: A 42-year-old white man was referred to neurosurgery due to a non-functional pituitary macroadenoma. He underwent a partial resection of the tumor on July 2, 2015. On the day following surgery he presented polyuria with sodium 149 mEq/L, plasma osmolality 301 mOsm/kg, and urine osmolality 293 mOsm/kg. He started nasal desmopressin 0.05 mg/day with good response. He was already on dexamethasone 4 mg and levothyroxine 75 mcg due to hypopituitarism after surgery. On July 9 he became confused. Cerebral computed tomography was performed with no significant changes. His natremia dropped to 128 mEq/L with development of polyuria despite maintenance of desmopressin dose. His hemoglobin and hematocrit rose from 9.1 g/L to 11.6 g/L and 27.5 to 32.5, respectively. His thyroid function was normal and he was on hydrocortisone 30 mg/day. At 12 p.m. 150 mg/hydrocortisone infusion was initiated, but sodium did not increase. Plasma and urine osmolality were 264 mOsm/kg and 679 mOsm/kg, respectively. At 4 p.m. hydrocortisone was increased and hypertonic saline replacement started. Two hours later he was dehydrated with polyuria and vomiting, and natremia of 124 mEq/L. Hyponatremia was very resistant to treatment despite hypertonic saline replacement, hence desmopressin was suspended. The following day, urine spot analysis showed that natriuresis was 63 mEq/L with serum sodium 132 mEq/L. This was interpreted as a cerebral salt wasting syndrome and control was achieved with aggressive hypertonic saline replacements and fludrocortisone 0.1 mg/three times a day. Conclusions: We present a rare case of a patient with diabetes insipidus and cerebral salt wasting syndrome, who was successfully treated. Hyponatremia in a patient with diabetes insipidus may erroneously be interpreted as inadequate diabetes insipidus control or as syndrome of inappropriate antidiuretic hormone secretion, leading to therapeutic errors. Thus, all clinical and analytical data should be evaluated together for early and correct diagnosis
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
Alternatives for Locating People Using Cameras and Embedded AI Accelerators: A Practical Approach
Presented at the 4th XoveTIC Conference, A Coruña, Spain, 7–8 October 2021.[Abstract] Indoor positioning systems usually rely on RF-based devices that should be carried by the targets, which is non-viable in certain use cases. Recent advances in AI have increased the reliability of person detection in images, thus, enabling the use of surveillance cameras to perform person localization and tracking. This paper evaluates the performance of indoor person location using cameras and edge devices with AI accelerators. We describe the video processing performed in each edge device, including the selected AI models and the post-processing of their outputs to obtain the positions of the detected persons and allow their tracking. The person location is based on pose estimation models as they provide better results than do object detection networks in occlusion situations. Experimental results are obtained with public datasets to show the feasibility of the solution.This work has been funded by the Navantia-UDC Joint Research Unit under Grant IN853B-2018/02, the Xunta de Galicia (by grant ED431C 2020/15, and grant ED431G 2019/01 to support the Centro de Investigación de Galicia “CITIC”), the Agencia Estatal de Investigación of Spain (by grants RED2018-102668-T and PID2019-104958RB-C42) and ERDF funds of the EU (FEDER Galicia 2014–2020 & AEI/FEDER Programs, UE).Xunta de Galicia; IN853B-2018/02Xunta de Galicia; ED431C 2020/15Xunta de Galicia; ED431G 2019/0
A feasibility analysis towards the simulation of hysteresis with spin-lattice dynamics
We use spin-lattice dynamics simulations to study the possibility of modeling
the magnetic hysteresis behavior of a ferromagnetic material. The temporal
evolution of the magnetic and mechanical degrees of freedom is obtained through
a set of two coupled Langevin equations. Hysteresis loops are calculated for
different angles between the external field and the magnetocrystalline
anisotropy axes. The influence of several relevant parameters is studied,
including the field frequency, magnetic damping, magnetic anisotropy (magnitude
and type), magnetic exchange, and system size. The role played by a moving
lattice is also discussed. For a perfect bulk ferromagnetic system we find
that, at low temperatures, the exchange and lattice dynamics barely affect the
loops, while the field frequency and magnetic damping have a large effect on
it. The influence of the anisotropy magnitude and symmetry are found to follow
the expected behavior. We show that a careful choice of simulation parameters
allows for an excellent agreement between the spin-lattice dynamics
measurements and the paradigmatic Stoner-Wohlfarth model. Furthermore, we
extend this analysis to intermediate and high temperatures for the perfect bulk
system and for spherical nanoparticles, with and without defects, reaching
values close to the Curie temperature. In this temperature range, we find that
lattice dynamics has a greater role on the magnetic behavior, especially in the
evolution of the defective samples. The present study opens the possibility for
more accurate inclusion of lattice defects and thermal effects in hysteresis
simulation
Construcción de una tarifa de cubicación con clasificación de productos para Pinus radiata D. Don en Galicia basada en una función de perfil del tronco
Seventeen taper functions from six different groups of models (single polynomial, segmented polynomial, power, exponential, variable exponent and trigonometric taper fucntions) were fitted to diameter at different heights data from a sample of 280 trees of Pinus radiata D. Don in Galicia (Northwestern Spain). The equations obtained were compared to evaluate its performance and were validated using an independent sample of 85 trees to determine the best model. A total and merchantable volume equation was calculated by integration of the taper function. This equation is useful to estimate the yield of the stand for the different log qualities.Un total de 17 funciones de perfil del tronco pertenecientes a seis categorías de modelos distintos (polinómicos simples, polinómicos segmentados, potenciales, exponenciales, de exponente variable y trigonométricos) se han ajustado a los datos de diámetros medidos a diferentes alturas obtenidos de una muestra de 280 árboles de Pinus radiata D. Don en Galicia. Las ecuaciones obtenidas se han comparado y validado empleando una muestra independiente de 85 árboles, con el fin de determinar el modelo que mejor se adapta al perfil real del tronco para la especie en esta Comunidad Autónoma. Posteriormente se ha construido una tarifa de cubicación con clasificación de productos mediante integración de la mejor función de perfil. Esta tarifa permite la estimación del volumen del árbol correspondiente a los distintos destinos industriales de la madera y por tanto una mejor valoración económica de la producción de las masas de esta especie
Experimental Evaluation of MIMO Coded Modulation Systems: are Space-Time Block Codes Really Necessary?
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