Comparing Downlink Capacity between Super Wi-Fi and Wi-Fi in Multi-Floored Indoor Environments

Department of Electrical EngineeringSuper Wi-Fi is a Wi-Fi-like service exploiting TV white spaces (WS) via the cognitive radio technology which is expected to achieve larger coverage than today???s Wi-Fi thanks to its superior propagation characteristics. Super Wi-Fi is currently being materialized as an international standard, IEEE 802.11af, targetting indoor and outdoor applications. This thesis demonstrates the potential of Super Wi-Fi in indoor environments by measuring its signal propagation characteristics and comparing them with those of Wi-Fi in the same indoor structure. Specifically, this thesis measures the wall and floor attenuation factors and path-loss distribution in 770 MHz and 2.4 GHz, and estimates the downlink capacity of Super Wi-Fi and Wi-Fi according to wide-accepted indoor path loss models. The experimental results reveal that TVWS signals can penetrate up to two floors and provide favorable coverage up to one floor above and below. In addition, TVWS can not only extend the coverage of Wi-Fi but also significantly mitigate shaded regions of Wi-Fi while achieving almost homogeneous data rates in the Wi-Fi???s coverage. The observed phenomena imply that Super Wi-Fi may be suitable for indoor applications with requirements of low-to-moderate data rates, extended horizontal and vertical coverage, and fair rate distribution within the service coverage.ope

Complete and versatile remote controller for PV systems

The promotion of the distributed generation and the photovoltaic (PV) energy great potential put this technology in the spotlight of investors. Thus, the optimization of its efficiency is made a priority. In this paper, a complete and versatile remote controller (C&VRC) for PV systems is presented, scalable to any kind and size of installations (with or without partial shading, with or without connection to the grid, housing, small plants or even large-scale solar plants) and valid for any weather conditions. The C&VRC involves the controller itself, which is constituted by a set of sensors and actuators connected to the converters Direct Current (DC)/DC and DC/Alternating Current (AC), if necessary, and a control unit communicated with them through the third-generation mobile telecommunications technology (3G) network. The control strategies can be changed according to the different weather conditions and installations characteristics, which guaranties the optimum performance of the system. The use of the 3G network as communication platform makes the C&VRC useful in remote and low accessibility places, because it is the most extended worldwide. The C&VRC is also based on free software, open hardware and low-cost electronic devices. Experimental results are presented in this paper to show the C&VRC optimum usability.This paper is framed in the project “Integral control system to optimize the microgrids energy demand” funded by the Spanish Ministry of Science and Innovation, call for Scientific and Technical Research and Innovation 2020-2023. Funding for open access charge: Universidad de Huelva / CBUA.This paper is framed in the project “Integral control system to optimize the microgrids energy demand” funded by the Spanish Ministry of Science and Innovation, call for Scientific and Technical Research and Innovation 2020-2023. Funding for open access charge: Universidad de Huelva / CBUA

Measurement and Comparison of Wi-Fi and Super Wi-Fi Indoor Propagation Characteristics in a Multi-Floored Building

Super Wi-Fi is a Wi-Fi-like service exploiting TV white space (WS) which is expected to achieve larger coverage than today???s Wi-Fi thanks to its superior propagation characteristics. Super Wi-Fi has been materialized as an international standard, IEEE 802.11af, targeting indoor and outdoor applications, and is undergoing worldwide field tests. This paper demonstrates the true potential of indoor Super Wi-Fi, by experimentally comparing the signal propagation characteristics of Super WiFi and Wi-Fi in the same indoor environment. Specifically, we measured the wall and floor attenuation factors and the pathloss distribution at 770 MHz, 2.401 GHz, and 5.540 GHz, and predicted the downlink capacity of Wi-Fi and Super Wi-Fi. The experimental results have revealed that TVWS signals can penetrate up to two floors above and below, whereas Wi-Fi signals experience significant path loss even through a single floor. It has been also shown that Super Wi-Fi mitigates shaded regions of Wi-Fi by providing almost-homogeneous data rates within its coverage, performs comparable to Wi-Fi utilizing less bandwidth, and always achieves better spectral efficiency than Wi-Fi. The observed phenomena imply that Super Wi-Fi is suitable for indoor applications and has the potential of extending horizontal and vertical coverage of today???s Wi-Fi.clos

Flexible skin-contact antenna with artifical magnetic conductor for health monitoring application

Flexible antenna plays a significant role to ensure efficient wireless communication in wearable devices. The choice of the dielectric substrate material of the antenna is one of the important factors to ensure good antenna performance while being tolerant to mechanical deformation. In addition, the size of the antenna becomes the main issue in designing the antenna for on-body applications. Furthermore, the radiation and transmissions performance of the on-body antenna suffers from performance degradation due to several factors such as dielectric properties of the human body as well as line of sight (LOS) and non line of sight (NLOS) transmission conditions. Therefore, this study presents a flexible Skin-Contact Antenna with Artificial Magnetic Conductor surface (SCA-AMC) made from medical-friendly material. Initially, three different types of medical materials which include transdermal cotton patch, semi-transparent film, and self-adhesive bandage were proposed for investigation as the antenna’s dielectric substrate. The dielectric properties of the proposed materials were measured prior to the antenna design. For preliminary design investigation, a conventional bowtie antenna was designed using the proposed medical materials and optimized to operate at frequency of 2.4 GHz. To achieve the objectives, the feasibility of medical material usage for the antenna’s substrate was explored based on wetness and repeatability test. The proposed SCA is intended for on-body wireless communication devices where there is a significant limitation on the overall size of the antenna. In order to develop a compact flexible antenna, a meandering technique is applied to the conventional bowtie antenna. By employing the meandering technique, the total length of the antenna can be reduced by 20 %. As the body protection against electromagnetic absorption is important, a dipole-like AMC structure was designed at frequency of 2.4 GHz and integrated with the meandered bowtie antenna. The proposed SCA-AMC is made of flexible material for the substrate and conducting parts, making it suitable for wearable applications. Furthermore, the factors that influence the antenna’s radiation and transmission performance have been determined. The experiments have been carried out considering various conditions such as body movements and the presence of either human body or obstacle in between the SCAAMC transmitter and the receiver. The results indicate that the human body introduces an additional 20 dBm power loss when present between the transmitter and receiver. Also, the presence o f the book causes 6 dBm reduction in received power while sweatshirts and cotton polo shirts contribute to a small variation of approximately from 0.5 to 1 dBm. Besides, wetness measurements were also carried out using tap water and sweat-like solution. The sweat-like solution had been developed using a mixture of sodium chloride, sodium bicarbonate, and water. The material characterization of the developed sweat-like solution was then performed. The developed sweat-like solution has a measured permittivity and loss tangent of 75.8 and 0.13, respectively at the frequency of 2.4 GHz. The proposed SCA-AMC was also tested in a real-life situation by merging it with an electrocardiogram (ECG) sensor node. The results obtained show that the wireless ECG pattern is comparable to the ECG pattern measured using a conventional ECG machine. The findings in this research have profound implications for future studies to develop an efficient wireless device, especially for on-body applications

Applications across Co-located Devices

We live surrounded by many computing devices. However, their presence has yet to be fully explored to create a richer ubiquitous computing environment. There is an opportunity to take better advantage of those devices by combining them into a unified user experience. To realize this vision, we studied and explored the use of a framework, which provides the tools and abstractions needed to develop applications that distribute UI components across co-located devices. The framework comprises the following components: authentication and authorization services; a broker to sync information across multiple application instances; background services that gather the capabilities of the devices; and a library to integrate web applications with the broker, determine which components to show based on UI requirements and device capabilities, and that provides custom elements to manage the distribution of the UI components and the multiple application states. Collaboration between users is supported by sharing application states. An indoor positioning solution had to be developed in order to determine when devices are close to each other to trigger the automatic redistribution of UI components. The research questions that we set out to respond are presented along with the contributions that have been produced. Those contributions include a framework for crossdevice applications, an indoor positioning solution for pervasive indoor environments, prototypes, end-user studies and developer focused evaluation. To contextualize our research, we studied previous research work about cross-device applications, proxemic interactions and indoor positioning systems. We presented four application prototypes. The first three were used to perform studies to evaluate the user experience. The last one was used to study the developer experience provided by the framework. The results were largely positive with users showing preference towards using multiple devices under some circumstances. Developers were also able to grasp the concepts provided by the framework relatively well.Vivemos rodeados de dispositivos computacionais. No entanto, ainda não tiramos partido da sua presença para criar ambientes de computação ubíqua mais ricos. Existe uma oportunidade de combiná-los para criar uma experiência de utilizador unificada. Para realizar esta visão, estudámos e explorámos a utilização de uma framework que forneça ferramentas e abstrações que permitam o desenvolvimento de aplicações que distribuem os componentes da interface do utilizador por dispositivos co-localizados. A framework é composta por: serviços de autenticação e autorização; broker que sincroniza informação entre várias instâncias da aplicação; serviços que reúnem as capacidades dos dispositivos; e uma biblioteca para integrar aplicações web com o broker, determinar as componentes a mostrar com base nos requisitos da interface e nas capacidades dos dispositivos, e que disponibiliza elementos para gerir a distribuição dos componentes da interface e dos estados de aplicação. A colaboração entre utilizadores é suportada através da partilha dos estados de aplicação. Foi necessário desenvolver um sistema de posicionamento em interiores para determinar quando é que os dispositivos estão perto uns dos outros para despoletar a redistribuição automática dos componentes da interface. As questões de investigação inicialmente colocadas são apresentadas juntamente com as contribuições que foram produzidas. Essas contribuições incluem uma framework para aplicações multi-dispositivo, uma solução de posicionamento em interiores para computação ubíqua, protótipos, estudos com utilizadores finais e avaliação com programadores. Para contextualizar a nossa investigação, estudámos trabalhos anteriores sobre aplicações multi-dispositivo, interação proxémica e sistemas de posicionamento em interiores. Apresentámos quatro aplicações protótipo. As primeiras três foram utilizadas para avaliar a experiência de utilização. A última foi utilizada para estudar a experiência de desenvolvimento com a framework. Os resultados foram geralmente positivos, com os utilizadores a preferirem utilizar múltiplos dispositivos em certas circunstâncias. Os programadores também foram capazes de compreender a framework relativamente bem

Exploring space situational awareness using neuromorphic event-based cameras

The orbits around earth are a limited natural resource and one that hosts a vast range of vital space-based systems that support international systems use by both commercial industries, civil organisations, and national defence. The availability of this space resource is rapidly depleting due to the ever-growing presence of space debris and rampant overcrowding, especially in the limited and highly desirable slots in geosynchronous orbit. The field of Space Situational Awareness encompasses tasks aimed at mitigating these hazards to on-orbit systems through the monitoring of satellite traffic. Essential to this task is the collection of accurate and timely observation data. This thesis explores the use of a novel sensor paradigm to optically collect and process sensor data to enhance and improve space situational awareness tasks. Solving this issue is critical to ensure that we can continue to utilise the space environment in a sustainable way. However, these tasks pose significant engineering challenges that involve the detection and characterisation of faint, highly distant, and high-speed targets. Recent advances in neuromorphic engineering have led to the availability of high-quality neuromorphic event-based cameras that provide a promising alternative to the conventional cameras used in space imaging. These cameras offer the potential to improve the capabilities of existing space tracking systems and have been shown to detect and track satellites or ‘Resident Space Objects’ at low data rates, high temporal resolutions, and in conditions typically unsuitable for conventional optical cameras. This thesis presents a thorough exploration of neuromorphic event-based cameras for space situational awareness tasks and establishes a rigorous foundation for event-based space imaging. The work conducted in this project demonstrates how to enable event-based space imaging systems that serve the goals of space situational awareness by providing accurate and timely information on the space domain. By developing and implementing event-based processing techniques, the asynchronous operation, high temporal resolution, and dynamic range of these novel sensors are leveraged to provide low latency target acquisition and rapid reaction to challenging satellite tracking scenarios. The algorithms and experiments developed in this thesis successfully study the properties and trade-offs of event-based space imaging and provide comparisons with traditional observing methods and conventional frame-based sensors. The outcomes of this thesis demonstrate the viability of event-based cameras for use in tracking and space imaging tasks and therefore contribute to the growing efforts of the international space situational awareness community and the development of the event-based technology in astronomy and space science applications

Quiet Supersonic Flights 2018 (QSF18) Test: Galveston, Texas Risk Reduction for Future Community Testing with a Low-Boom Flight Demonstration Vehicle

The Quiet Supersonic Flights 2018 (QSF18) Program was designed to develop tools and methods for demonstration of overland supersonic flight with an acceptable sonic boom, and collect a large dataset of responses from a representative sample of the population. Phase 1 provided the basis for a low amplitude sonic boom testing in six different climate regions that will enable international regulatory agencies to draft a noise-based standard for certifying civilian supersonic overland flight. Phase 2 successfully executed a large scale test in Galveston, Texas, developed well documented data sets, calculated dose response relationships, yielded lessons, and identified future risk reduction activities

On Improving Generalization of CNN-Based Image Classification with Delineation Maps Using the CORF Push-Pull Inhibition Operator

Deployed image classification pipelines are typically dependent on the images captured in real-world environments. This means that images might be affected by different sources of perturbations (e.g. sensor noise in low-light environments). The main challenge arises by the fact that image quality directly impacts the reliability and consistency of classification tasks. This challenge has, hence, attracted wide interest within the computer vision communities. We propose a transformation step that attempts to enhance the generalization ability of CNN models in the presence of unseen noise in the test set. Concretely, the delineation maps of given images are determined using the CORF push-pull inhibition operator. Such an operation transforms an input image into a space that is more robust to noise before being processed by a CNN. We evaluated our approach on the Fashion MNIST data set with an AlexNet model. It turned out that the proposed CORF-augmented pipeline achieved comparable results on noise-free images to those of a conventional AlexNet classification model without CORF delineation maps, but it consistently achieved significantly superior performance on test images perturbed with different levels of Gaussian and uniform noise

Localización de interiores mediante radiofrecuencia: Estudio, análisis y propuestas de mejora

El sistema de posicionamiento global (GPS) es el sistema más utilizado en aplicaciones de localización en exteriores, pero es ineficiente para la localización en interiores. En los últimos años, los sistemas de posicionamiento en interiores se han desarrollado ampliamente. Para ello se han utilizado varias tecnologías inalámbricas, como ZigBee, WLAN y banda ultra ancha (UWB). Los principales métodos de medición de la señal inalámbrica en los sistemas de localización en interiores son el tiempo de llegada (TOA), la diferencia de tiempo de llegada (TDOA), el ángulo de llegada (AOA) y la indicación de intensidad de señal recibida (RSSI). Los sistemas de posicionamiento TOA, TDOA y AOA requieren una sincronización de tiempo precisa o un conjunto de antenas, lo que puede aumentar el coste del sistema. Por otro lado, un sistema de posicionamiento basado en RSSI utiliza características de la intensidad de la señal inalámbrica en el espacio y no requiere sincronización de tiempo ni mediciones de ángulos. Además, la medición de RSSI es relativamente sencilla y puede emplear tecnologías inalámbricas existentes sin ningún dispositivo de hardware adicional, lo que elimina el coste adicional y el consumo de energía. La mayoría de los trabajos de investigación de posicionamiento basados ​​en RSSI utilizan la técnica fingerprinting y una amplia variedad de algoritmos para mejorar la precisión de la localización . Sin embargo, la construcción de una extensa base de datos de puntos de referencia durante la llamada fase de calibración hace que la técnica fingerprinting requiere mucho tiempo y esfuerzo. Además, la flexibilidad de los dispositivos, ha permitido la toma de medidas de RSSI en diferentes canales de frecuencia y niveles de potencia, lo que ha posibilitado que se incremente el número de medidas RSSI para cada punto de referencia. Ello ha aumentado la precisión de la localización a costa de una base de datos mayor, lo que implica un mayor coste de tiempo y computación. En esta tesis, tras el planteamiento inicial del problema de la localización en interiores y un estudio de las diversas técnicas y soluciones propuestas, haciendo hincapié la técnica de fingerprinting, se presentan diferentes opciones para reducir la base de datos durante la fase de calibración. La primera de ellas, consistente en un análisis de dichos niveles de potencias y canales utilizados, disminuyendo su número, estudiando posibles combinaciones y viendo su influencia en la precisión de la localización. De igual modo, se puede reducir el esfuerzo en la construcción de la base de datos utilizando técnicas de interpolación. De esta manera, se reduce el número de puntos de referencia que necesitan ser tomados y se sustituyen por puntos generados mediante diversas funciones de interpolación. Se han evaluado diversos mapas de distribución de puntos y analizado su influencia en la precisión. Desde otro punto de vista, se ha analizado el coste temporal de la creación de la base datos y se ha propuesto un nuevo algoritmo que utiliza diferentes canales de frecuencia para evitar los periodos de contención de acceso al medio y permite a diversos dispositivos móviles acceder al canal para intercambiar paquetes con el mismo o con otras balizas al mismo tiempo. De esta manera, se reduce el tiempo empleado en la construcción de la base de medidas pero se mantiene el tamaño de dicha base con lo que la precisión del sistema no se ve alterada. Por último, se presenta un nuevo algoritmo TDOA para dispositivos UWB. El método implementa un algoritmo de transmisión de una sola dirección para medir las diferencias del tiempo de llegada. Ello reduce la complejidad de los dispositivos, ya que sólo tienen que transmitir pero no recibir paquetes. Por otro lado, el algoritmo de localización propuesto no requiere una sincronización de tiempo permanente de los relojes de las balizas y la estimación de los tiempos de offsets se realizan conjuntamente con el cálculo de la posición.El sistema de posicionamiento global (GPS) es el sistema más utilizado en aplicaciones de localización en exteriores, pero es ineficiente para la localización en interiores. En los últimos años, los sistemas de posicionamiento en interiores se han desarrollado ampliamente. Para ello se han utilizado varias tecnologías inalámbricas, como ZigBee, WLAN y banda ultra ancha (UWB). Los principales métodos de medición de la señal inalámbrica en los sistemas de localización en interiores son el tiempo de llegada (TOA), la diferencia de tiempo de llegada (TDOA), el ángulo de llegada (AOA) y la indicación de intensidad de señal recibida (RSSI). Los sistemas de posicionamiento TOA, TDOA y AOA requieren una sincronización de tiempo precisa o un conjunto de antenas, lo que puede aumentar el coste del sistema. Por otro lado, un sistema de posicionamiento basado en RSSI utiliza características de la intensidad de la señal inalámbrica en el espacio y no requiere sincronización de tiempo ni mediciones de ángulos. Además, la medición de RSSI es relativamente sencilla y puede emplear tecnologías inalámbricas existentes sin ningún dispositivo de hardware adicional, lo que elimina el coste adicional y el consumo de energía. La mayoría de los trabajos de investigación de posicionamiento basados ​​en RSSI utilizan la técnica \textit{fingerprinting} y una amplia variedad de algoritmos para mejorar la precisión de la localización . Sin embargo, la construcción de una extensa base de datos de puntos de referencia durante la llamada fase de calibración hace que la técnica \textit{fingerprinting} requiere mucho tiempo y esfuerzo. Además, la flexibilidad de los dispositivos, ha permitido la toma de medidas de RSSI en diferentes canales de frecuencia y niveles de potencia, lo que ha posibilitado que se incremente el número de medidas RSSI para cada punto de referencia. Ello ha aumentado la precisión de la localización a costa de una base de datos mayor, lo que implica un mayor coste de tiempo y computación. En esta tesis, tras el planteamiento inicial del problema de la localización en interiores y un estudio de las diversas técnicas y soluciones propuestas, haciendo hincapié la técnica de \textit{fingerprinting}, se presentan diferentes opciones para reducir la base de datos durante la fase de calibración. La primera de ellas, consistente en un análisis de dichos niveles de potencias y canales utilizados, disminuyendo su número, estudiando posibles combinaciones y viendo su influencia en la precisión de la localización. De igual modo, se puede reducir el esfuerzo en la construcción de la base de datos utilizando técnicas de interpolación. De esta manera, se reduce el número de puntos de referencia que necesitan ser tomados y se sustituyen por puntos generados mediante diversas funciones de interpolación. Se han evaluado diversos mapas de distribución de puntos y analizado su influencia en la precisión. Desde otro punto de vista, se ha analizado el coste temporal de la creación de la base datos y se ha propuesto un nuevo algoritmo que utiliza diferentes canales de frecuencia para evitar los periodos de contención de acceso al medio y permite a diversos dispositivos móviles acceder al canal para intercambiar paquetes con el mismo o con otras balizas al mismo tiempo. De esta manera, se reduce el tiempo empleado en la construcción de la base de medidas pero se mantiene el tamaño de dicha base con lo que la precisión del sistema no se ve alterada. Por último, se presenta un nuevo algoritmo TDOA para dispositivos UWB. El método implementa un algoritmo de transmisión de una sola dirección para medir las diferencias del tiempo de llegada. Ello reduce la complejidad de los dispositivos, ya que sólo tienen que transmitir pero no recibir paquetes. Por otro lado, el algoritmo de localización propuesto no requiere una sincronización de tiempo permanente de los relojes de las balizas y la estimación de los tiempos de \textit{offsets} se realizan conjuntamente con el cálculo de la posición.

Wood handbook : wood as an engineering material

Summarizes information on wood as an engineering material. Presents properties of wood and wood-based products of particular concern to the architect and engineer. Includes discussion of designing with wood and wood-based products along with some pertinent uses.Keywords: wood structure, physical properties (wood), mechanical properties (wood), lumber, wood-based composites, plywood, panel products, design, fastenings, wood moisture, drying, gluing, fire resistance, finishing, decay, preservation, wood-based products, heat sterilization, sustainable us