990 resultados para Acquisition system
Resumo:
Este proyecto está dividido en dos partes, una de ellas dedicada al estudio del sistema de adquisición NetdB y su aplicación a prácticas de Acústica Arquitectónica y la otra dedicada a la evaluación de la herramienta OneNote 2010 y su aplicación al proceso enseñanza – aprendizaje. Se estructura en cinco secciones bien definidas que se comentan a continuación: La primera sección, fundamentos teóricos, se centrará en explicar los distintos parámetros medidos y su relación con la acústica. Para ello se definirán los conceptos teóricos básicos que ayudarán al seguimiento del proyecto en su totalidad. La segunda sección está dedicada al sistema de adquisición NetdB, y en ella se explican sus características, el conexionado del equipo y la configuración del mismo con el software dBBati. En la tercera sección se describen las medidas realizadas con el sistema de adquisición NetdB, basadas en la normativa nacional e internacional vigente. Estas medidas son: - Medición del tiempo de reverberación en recintos ordinarios, según la Norma UNE-EN ISO 3382-2. - Medición del coeficiente de absorción sonora en cámara reverberante, según la Norma UNE-EN ISO 354. - Medición “in situ” del aislamiento a ruido aéreo, según las normas UNE-EN ISO 140-4 y UNE-EN ISO 717-1. En cada una de las medidas se describe el objetivo, los equipos utilizados, la conexión entre los distintos equipos, el ensayo realizado según la norma correspondiente, los cálculos y resultados obtenidos y las conclusiones finales de la medida. En la cuarta sección se describe la herramienta OneNote 2010, detallándose su estructura, configuración y la evaluación de su aplicación al proceso enseñanza – aprendizaje. Por último, se darán unas conclusiones finales, en las que se recapitularán los resultados de las valoraciones obtenidos durante la realización del proyecto. ABSTRACT. This project is divided into two parts, one of them dealing with the study of NetdB acquisition system and its application on Architectural Acoustics practices and the other dedicated to the evaluation of the OneNote 2010 tool and its application on the teaching-learning process. The structure of the project consists of five clearly defined sections as stated hereunder: 1. Theoretical fundamentals, based on the explanation of the different parameters subject to measurement and their relation to acoustics. To this end, basic theoretical concepts will be clearly defined, which will help the follow-up of the project as a whole. 2. NetdB acquisition system: whereby features will be clearly defined, as well as the equipment connection and its configuration within the dBBati software. 3. Description of the measures carried out on the NetdB acquisition system under current regulations both national and international, being those measures as follows: - Reverberation Time measurement in ordinary premises, according to the UNE-EN ISO 3382-2 standard. - Sound absorption ratio measurement in reverberating chamber, according to the UNE-EN ISO 354 standard. - “In situ” sound proofing air traffic, according to UNE-EN ISO 140-4 and UNE-EN ISO 717-1 standards. Each of the measures stated above comprises the description of the following issues: its aim, the equipment in use, the connection among different equipment, the test carried out under the corresponding standard, the calculations and results obtained and finally the conclusions reached at. 4. OneNote 2010 tool: full description detailing its structure, configuration as well as the evaluation of its application on the teaching-learning process. Finally, the report will give the final conclusions by means of recapitulating the results of the different assessments obtained along the process.
Resumo:
La verificación de la seguridad estructural, tanto de estructuras que permitan un cierto grado de deterioro en su dimensionado como de estructuras existentes deterioradas, necesita disponer de modelos de resistencia que tengan en cuenta los efectos del deterioro. En el caso de la corrosión de las armaduras en las estructuras de hormigón armado, la resistencia depende de múltiples factores tales como la sección del acero corroído, el diagrama tensión-deformación del acero corroído, la adherencia hormigón-acero corroído, la fisuración o desprendimiento del hormigón debido a la expansión de los productos de corrosión. En este sentido, la transferencia de las fuerzas a través de la superficie de contacto entre el hormigón y el acero, la adherencia, es uno de los aspectos más importantes a considerar y es la base del comportamiento del hormigón armado como elemento estructural. La adherencia debe asegurar el anclaje de las armaduras y transmitir la tensión tangencial que aparece en las mismas como consecuencia de la variación de las solicitaciones a lo largo de un elemento estructural. Como consecuencia de la corrosión de las armaduras, el desarrollo de la adherencia se altera y, por tanto, la transferencia de la tensión longitudinal. Esta Tesis Doctoral aborda el comportamiento en estado límite último de la adherencia en el hormigón estructural con armaduras corroídas. El objetivo principal es la obtención de un modelo suficientemente realista y fiable para la evaluación de la adherencia con armaduras corroídas en el marco de la verificación de la seguridad estructural de elementos de hormigón armado con armaduras corroídas. Para ello se ha llevado a cabo un programa experimental de ensayos tipo pull-out excéntricos, con diferentes probetas, unas sin corrosión y otras sometidas tanto a procesos de corrosión natural como a procesos de corrosión acelerada, con diferentes grados de deterioro. Este tipo de ensayo de adherencia representa de forma realista y fiable realista los esfuerzos de adherencia en la zona de anclaje. Por otra parte, para la realización de estos ensayos se ha puesto a punto, además del procedimiento de ensayo, un sistema de adquisición de datos entre los que se incluye el empleo de sensores de tipo fibra óptica con redes de Bragg embebidos en la armadura para determinar los parámetros representativos de la adherencia en el hormigón estructural con armaduras corroídas. Por otra parte, la recopilación de los datos de los estudios de adherencia con armaduras corroídas procedentes de la literatura científica, además de los resultados de la presente investigación, junto con la identificación de las variables relevantes en el comportamiento de la adherencia con armaduras sanas y corroídas ha servido para la obtención de una formulación realista y fiable para la evaluación conjunta de la adherencia con armaduras sanas y corroídas a partir de modelos de regresión múltiple. La formulación propuesta ha sido validada mediante criterios estadísticos y comparada con otras formulaciones propuestas en la literatura científica. Además se ha realizado un análisis de las variables influyentes de la formulación propuesta. También se ha obtenido un modelo numérico simple y eficiente, validado con alguno de los ensayos realizados en esta tesis, para simular la adherencia con armaduras sanas y corroídas. Finalmente, se presenta un procedimiento para realizar la evaluación de vigas deterioradas por corrosión mediante el método de los campos de tensiones que incluye la evaluación de la adherencia mediante la formulación sugerida en esta Tesis Doctoral. Las conclusiones alcanzadas en este trabajo han permitido evaluar la adherencia con armaduras corroídas de forma realista y fiable. Asimismo, se ha podido incluir la evaluación de la adherencia en el marco de la verificación de la seguridad estructural en elementos de hormigón armado deteriorados por corrosión. ABSTRACT Structural safety verification of both structures allowing a certain degree of deterioration in design and deteriorated existing structures needs strength models that factor in the effects of deterioration. In case of corrosion of steel bars in reinforced concrete structures, the resistance depends on many things such as the remaining cross-section of the corroded reinforcement bars, the stress-strain diagrams of steel, the concrete-reinforcement bond and corrosion-induced concrete cracking or spalling. Accordingly, the force transfer through the contact surface between concrete and reinforcement, bond, is one of the most important aspects to consider and it is the basis of the structural performance of reinforced concrete. Bond must assure anchorage of reinforcement and transmit shear stresses as a consequence of the different stresses along a structural element As a consequence of corrosion, the bond development may be affected and hence the transfer of longitudinal stresses. This PhD Thesis deals with ultimate limit state bond behaviour in structural concrete with corrode steel bars. The main objective is to obtain a realistic and reliable model for the assessment of bond within the context of structural safety verifications of reinforced concrete members with corroded steel bars. In that context, an experimental programme of eccentric pull-out tests were conducted, with different specimens, ones without corrosion and others subjected to accelerated or natural corrosion with different corrosion degrees. This type of bond test reproduces in a realistic and reliable way bond stresses in the anchorage zone. Moreover, for conducting these tests it was necessary to develop both a test procedure and also a data acquisition system including the use of an embedded fibre-optic sensing system with fibre Bragg grating sensors to obtain the representative parameters of bond strength in structural concrete with corroded steel bars. Furthermore, the compilation of data from bond studies with corroded steel bars from scientific literature, including tests conducted in the present study, along with the identification of the relevant variables influencing bond behaviour for both corroded and non-corroded steel bars was used to obtain a realistic and reliable formulation for bond assessment in corroded and non-corroded steel bars by multiple linear regression analysis. The proposed formulation was validated with a number of statistical criteria and compared to other models from scientific literature. Moreover, an analysis of the influencing variables of the proposed formulation has been performed. Also, a simplified and efficient numerical model has been obtained and validated with several tests performed in this PhD Thesis for simulating the bond in corroded and non-corroded steel bars. Finally, a proposal for the assessment of corrosion-damaged beams with stress field models including bond assessment with the proposed formulation is presented. The conclusions raised in this work have allowed a realistic and reliable bond assessment in corroded steel bars. Furthermore, bond assessment has been included within the context of structural safety verifications in corrosion-damaged reinforced concrete elements.
Resumo:
El Grupo de Diseño Electrónico y Microelectrónico de la Universidad Politécnica de Madrid -GDEM- se dedica, entre otras cosas, al estudio y mejora del consumo en sistemas empotrados. Es en este lugar y sobre este tema donde el proyecto a exponer ha tomado forma y desarrollo. Según un artículo de la revista online Revista de Electrónica Embebida, un sistema empotrado o embebido es aquel “sistema controlado por un microprocesador y que gracias a la programación que incorpora o que se le debe incorporar, realiza una función específica para la que ha sido diseñado, integrando en su interior la mayoría de los elementos necesarios para realizar dicho función”. El porqué de estudiar sobre este tema responde a que, cada vez, hay mayor presencia de sistemas empotrados en nuestra vida cotidiana. Esto es debido a que se está tendiendo a dotar de “inteligencia” a todo lo que puedan hacer nuestra vida un poco más fácil. Nos podemos encontrar dichos sistemas en fábricas, oficinas de atención a los ciudadanos, sistemas de seguridad de hogar, relojes, móviles, lavadoras, hornos, aspiradores y un largo etcétera en cualquier aparato que nos podamos imaginar. A pesar de sus grandes ventajas, aún hay grandes inconvenientes. El mayor problema que supone a día de hoy es la autonomía del mismo sistema, ya que hablamos de aparatos que muchas veces están alimentados por baterías -para ayudar a su portabilidad–. Por esto, se está intentando dotar a dichos sistemas de una capacidad de ahorro de energía y toma de decisiones que podrían ayudar a duplicar la autonomía de dicha batería. Un ejemplo claro son los Smartphones de hoy en día, unos aparatos casi indispensables que pueden tener una autonomía de un día. Esto es poco práctico para el usuario en caso de viajes, trabajo u otras situaciones en las que se le dé mucho uso y no pueda tener acceso a una red eléctrica. Es por esto que surge la necesidad de investigar, sin necesidad de mejorar el hardware del sistema, una manera de mejorar esta situación. Este proyecto trabajará en esa línea creando un sistema automático de medida el cual generará las corrientes que servirán como entrada para verificar el sistema de adquisición que junto con la tarjeta Beagle Board permitirá la toma de decisiones en relación con el consumo de energía. Para realizar este sistema, nos ayudaremos de diferentes herramientas que podremos encontrar en el laboratorio del GDEM, como la fuente de alimentación Agilent y la Beagle Board –como principales herramientas de trabajo- . El objetivo principal será la simulación de unas señales que, después de pasar un proceso de conversión y tratado, harán la función de representación del consumo de cada una de las partes que pueden formar un sistema empotrado genérico. Por lo tanto, podemos decir que el sistema hará la funcionalidad de un banco de pruebas que ayudará a simular dicho consumo para que el microprocesador del sistema pueda llegar a tomar alguna decisión. ABSTRACT. The Electronic and Microelectronic Design Group of Universidad Politécnica de Madrid -GDEM- is in charge, between other issues, of improving the embedded system’s consumption. It is in this place and about this subject where the exposed project has taken shape and development. According to an article from de online magazine Revista de Electronica Embebida, an embedded system is “the one controlled by a microprocessor and, thanks to the programing that it includes, it carries out a specific function what it has been designed for, being integrated in it the most necessary elements for realizing the already said function”. The because of studying this subject, answers that each time there is more presence of the embedded system in our daily life. This is due to the tendency of providing “intelligence” to all what can make our lives easier. We can find this kind of systems in factories, offices, security systems, watchers, mobile phones, washing machines, ovens, hoovers and, definitely, in all kind of machines what we can think of. Despite its large vantages, there are still some inconveniences. Nowadays, the most important problem is the autonomy of the system itself when machines that have to be supplied by batteries –making easier the portability-. Therefore, this project is going after a save capacity of energy for the system as well as being able to take decisions in order to duplicate batteries’ autonomy. Smartphones are a clear example. They are a very successful product but the autonomy is just one day. This is not practical for users, at all, if they have to travel, to work or to do any activity that involves a huge use of the phone without a socket nearby. That is why the need of investigating a way to improve this situation. This project is working on this line, creating an automatic system that will generate the currents for verifying the acquisition system that, with the beagle board, will help taking decisions regarding the energy’s consumption. To carry out this system, we need different tools that we can find in the laboratory of the group previously mentioned, like power supply Agilent and the Beagle Board – as main working tools –. The main goal is the simulation of some signals that, after a conversion process, will represent de consumption of each of the parts in the embedded generic system. Therefore, the system will be a testing ground that simulate the consumption, once sent to the processor, to be processed and so the microprocessor system might take some decision.
Resumo:
Dynamic measurements will become a standard for bridge monitoring in the near future. This fact will produce an important cost reduction for maintenance. US Administration has a long term intensive research program in order to diminish the estimated current maintenance cost of US$7 billion per year over 20 years. An optimal intervention maintenance program demands a historical dynamical record, as well as an updated mathematical model of the structure to be monitored. In case that a model of the structure is not actually available it is possible to produce it, however this possibility does not exist for missing measurement records from the past. Current acquisition systems to monitor structures can be made more efficient by introducing the following improvements, under development in the Spanish research Project “Low cost bridge health monitoring by ambient vibration tests using wireless sensors”: (a) a complete wireless system to acquire sensor data, (b) a wireless system that permits the localization and the hardware identification of the whole sensor system. The applied localization system has been object of a recent patent, and (c) automatization of the modal identification process, aimed to diminish human intervention. This system is assembled with cheap components and allows the simultaneous use of a large number of sensors at a low placement cost. The engineer’s intervention is limited to the selection of sensor positions, probably based on a preliminary FE analysis. In case of multiple setups, also the position of a number of fixed reference sensors has to be decided. The wireless localization system will obtain the exact coordinates of all these sensors positions. When the selection of optimal positions is difficult, for example because of the lack of a proper FE model, this can be compensated by using a higher number of measuring (also reference) points. The described low cost acquisition system allows the responsible bridge administration to obtain historical dynamic identification records at reasonable costs that will be used in future maintenance programs. Therefore, due to the importance of the baseline monitoring record of a new bridge, a monitoring test just after its construction should be highly recommended, if not compulsory.
Resumo:
El presente trabajo tiene como objetivo el desarrollo de un patrón primario para la calibración de sensores de fuerza bajo excitaciones sinusoidales. Con consecuencia de dicho desarrollo se establecerá un método de calibración de sensores de fuerza en condiciones dinámicas que permitirá la caracterización de estos sensores en dichas condiciones y determinar la incertidumbre asociada. Este patrón se basa en la definición directa de fuerza como masa por aceleración. Para ello se carga el sensor con distintas cargas calibradas y se somete a distintas aceleraciones mediante un excitador de vibraciones. Dichas aceleraciones se generan para frecuencias desde 5 Hz a 2400 Hz. La aceleración se mide mediante un vibrómetro láser con trazabilidad a la unidad de longitud (longitud de onda del láser). Al ser una medición completamente dinámica se necesita un sistema de adquisición de datos multicanal para la toma de datos en tiempo real. Este sistema adquiere las señales eléctricas provenientes del vibrómetro láser, del sensor a caracterizar y del acelerómetro para mediciones auxiliares. Se ha dispuesto de cuatro sensores de fuerza para realizar ensayos, un sensor piezoeléctrico y tres sensores resistivos. En este trabajo se han estudiado los factores de influencia y se ha implementado un método de calibración para minimizar los mismos, así como también se han establecido las correcciones a realizar. Para la caracterización dinámica del sensor se ha partido de un modelo de oscilador armónico amortiguado forzado, se ha establecido la metodología para la determinación de sus parámetros de caracterización y se ha estudiado su validez. También se ha realizado una comparación entre los resultados obtenidos para condiciones estáticas y dinámicas. ABSTRACT The aim in the current work is the development of a primary standard for force sensors calibration under sinusoidal excitations. As consequence of this development a method for force sensors calibration under dynamic conditions will be established that will allow these sensors characterization for such conditions and the determination of their associated uncertainty. This standard is based on the direct definition of force as mass multiplied by acceleration. To do so, the sensor is loaded with different calibrated loads and is maintained under different accelerations by means of a vibration shaker. These accelerations are generated with frequencies from 5 Hz up to 2400 Hz. The acceleration is measured by means of a laser vibrometer with traceability to the unit of length (laser wavelength). As the measurement is totally dynamic a multiple channel data acquisition system is required for data acquisition in real time. This system acquires the electrical signals outputs coming from the laser vibrometer, the sensor to be characterised and two accelerometers for additional measurements. Four force sensors, one piezoelectric sensor and three resistive sensors, have been available to perform the tests. During this work the influence factors have been studied and a calibration method to minimise these factors have been implemented as well as the corrections to be performed have been established. As the starting point for the sensor dynamic characterization, a model for a forced damped harmonic oscillator has been used, a method for the characterizing parameters determination has been established and its validity has been studied. A comparison between results for static and dynamic conditions has been performed as well.
Resumo:
La seguridad y fiabilidad de los procesos industriales son la principal preocupación de los ingenieros encargados de las plantas industriales. Por lo tanto, desde un punto de vista económico, el objetivo principal es reducir el costo del mantenimiento, el tiempo de inactividad y las pérdidas causadas por los fallos. Por otra parte, la seguridad de los operadores, que afecta a los aspectos sociales y económicos, es el factor más relevante a considerar en cualquier sistema Debido a esto, el diagnóstico de fallos se ha convertido en un foco importante de interés para los investigadores de todo el mundo e ingenieros en la industria. Los principales trabajos enfocados en detección de fallos se basan en modelos de los procesos. Existen diferentes técnicas para el modelado de procesos industriales tales como máquinas de estado, árboles de decisión y Redes de Petri (RdP). Por lo tanto, esta tesis se centra en el modelado de procesos utilizando redes de petri interpretadas. Redes de Petri es una herramienta usada en el modelado gráfico y matemático con la habilidad para describir información de los sistemas de una manera concurrente, paralela, asincrona, distribuida y no determinística o estocástica. RdP son también una herramienta de comunicación visual gráfica útil como lo son las cartas de flujo o diagramas de bloques. Adicionalmente, las marcas de las RdP simulan la dinámica y concurrencia de los sistemas. Finalmente, ellas tienen la capacidad de definir ecuaciones de estado específicas, ecuaciones algebraicas y otros modelos que representan el comportamiento común de los sistemas. Entre los diferentes tipos de redes de petri (Interpretadas, Coloreadas, etc.), este trabajo de investigación trata con redes de petri interpretadas principalmente debido a características tales como sincronización, lugares temporizados, aparte de su capacidad para procesamiento de datos. Esta investigación comienza con el proceso para diseñar y construir el modelo y diagnosticador para detectar fallos definitivos, posteriormente, la dinámica temporal fue adicionada para detectar fallos intermitentes. Dos procesos industriales, concretamente un HVAC (Calefacción, Ventilación y Aire Acondicionado) y un Proceso de Envasado de Líquidos fueron usados como banco de pruebas para implementar la herramienta de diagnóstico de fallos (FD) creada. Finalmente, su capacidad de diagnóstico fue ampliada en orden a detectar fallos en sistemas híbridos. Finalmente, un pequeño helicóptero no tripulado fue elegido como ejemplo de sistema donde la seguridad es un desafío, y las técnicas de detección de fallos desarrolladas en esta tesis llevan a ser una herramienta valorada, desde que los accidentes de las aeronaves no tripuladas (UAVs) envuelven un alto costo económico y son la principal razón para introducir restricciones de volar sobre áreas pobladas. Así, este trabajo introduce un proceso sistemático para construir un Diagnosticador de Fallos del sistema mencionado basado en RdR Esta novedosa herramienta es capaz de detectar fallos definitivos e intermitentes. El trabajo realizado es discutido desde un punto de vista teórico y práctico. El procedimiento comienza con la división del sistema en subsistemas para seguido integrar en una RdP diagnosticadora global que es capaz de monitorear el sistema completo y mostrar las variables críticas al operador en orden a determinar la salud del UAV, para de esta manera prevenir accidentes. Un Sistema de Adquisición de Datos (DAQ) ha sido también diseñado para recoger datos durante los vuelos y alimentar la RdP diagnosticadora. Vuelos reales realizados bajo condiciones normales y de fallo han sido requeridos para llevar a cabo la configuración del diagnosticador y verificar su comportamiento. Vale la pena señalar que un alto riesgo fue asumido en la generación de fallos durante los vuelos, a pesar de eso esto permitió recoger datos básicos para desarrollar el diagnóstico de fallos, técnicas de aislamiento, protocolos de mantenimiento, modelos de comportamiento, etc. Finalmente, un resumen de la validación de resultados obtenidos durante las pruebas de vuelo es también incluido. Un extensivo uso de esta herramienta mejorará los protocolos de mantenimiento para UAVs (especialmente helicópteros) y permite establecer recomendaciones en regulaciones. El uso del diagnosticador usando redes de petri es considerado un novedoso enfoque. ABSTRACT Safety and reliability of industrial processes are the main concern of the engineers in charge of industrial plants. Thus, from an economic point of view, the main goal is to reduce the maintenance downtime cost and the losses caused by failures. Moreover, the safety of the operators, which affects to social and economic aspects, is the most relevant factor to consider in any system. Due to this, fault diagnosis has become a relevant focus of interest for worldwide researchers and engineers in the industry. The main works focused on failure detection are based on models of the processes. There are different techniques for modelling industrial processes such as state machines, decision trees and Petri Nets (PN). Thus, this Thesis is focused on modelling processes by using Interpreted Petri Nets. Petri Nets is a tool used in the graphic and mathematical modelling with ability to describe information of the systems in a concurrent, parallel, asynchronous, distributed and not deterministic or stochastic manner. PNs are also useful graphical visual communication tools as flow chart or block diagram. Additionally, the marks of the PN simulate the dynamics and concurrence of the systems. Finally, they are able to define specific state equations, algebraic equations and other models that represent the common behaviour of systems. Among the different types of PN (Interpreted, Coloured, etc.), this research work deals with the interpreted Petri Nets mainly due to features such as synchronization capabilities, timed places, apart from their capability for processing data. This Research begins with the process for designing and building the model and diagnoser to detect permanent faults, subsequently, the temporal dynamic was added for detecting intermittent faults. Two industrial processes, namely HVAC (Heating, Ventilation and Air Condition) and Liquids Packaging Process were used as testbed for implementing the Fault Diagnosis (FD) tool created. Finally, its diagnostic capability was enhanced in order to detect faults in hybrid systems. Finally, a small unmanned helicopter was chosen as example of system where safety is a challenge and fault detection techniques developed in this Thesis turn out to be a valuable tool since UAVs accidents involve high economic cost and are the main reason for setting restrictions to fly over populated areas. Thus, this work introduces a systematic process for building a Fault Diagnoser of the mentioned system based on Petri Nets. This novel tool is able to detect both intermittent and permanent faults. The work carried out is discussed from theoretical and practical point of view. The procedure begins with a division of the system into subsystems for further integration into a global PN diagnoser that is able to monitor the whole system and show critical variables to the operator in order to determine the UAV health, preventing accidents in this manner. A Data Acquisition System (DAQ) has been also designed for collecting data during the flights and feed PN Diagnoser. Real flights carried out under nominal and failure conditions have been required to perform the diagnoser setup and verify its performance. It is worth noting that a high risk was assumed in the generation of faults during the flights, nevertheless this allowed collecting basic data so as to develop fault diagnosis, isolations techniques, maintenance protocols, behaviour models, etc. Finally, a summary of the validation results obtained during real flight tests is also included. An extensive use of this tool will improve preventive maintenance protocols for UAVs (especially helicopters) and allow establishing recommendations in regulations. The use of the diagnoser by using Petri Nets is considered as novel approach.
Resumo:
This work presents a systematic process for building a Fault Diagnoser (FD), based on Petri Nets (PNs) which has been applied to a small helicopter. This novel tool is able to detect both intermittent and permanent faults. The work carried out is discussed from theoretical and practical point of view. The procedure begins with a division of the whole system into subsystems, which are the devices that have to be modeled by using PN, considering both the normal and fault operations. Subsequently, the models are integrated into a global Petri Net diagnoser (PND) that is able to monitor a whole helicopter and show critical variables to the operator in order to determine the UAV health, preventing accidents in this manner. A Data Acquisition System (DAQ) has been designed for collecting data during the flights and feeding PN diagnoser with them. Several real flights (nominal or under failure) have been carried out to perform the diagnoser setup and verify its performance. A summary of the validation results obtained during real flight tests is also included. An extensive use of this tool will improve preventive maintenance protocols for UAVs (especially helicopters) and allow establishing recommendations in regulations
Resumo:
Medidas de espectroscopia gama de alta resolução têm diversas aplicações. Aplicações envolvendo medidas de radioisótopos de meia-vida curta podem apresentar problemas de baixa precisão nas contagens quando a fonte radioativa está distante do detector e de perda de acurácia por efeitos de tempo morto e empilhamento de pulsos em situação de altas taxas de contagens. Um modo de minimizar esses problemas é alterando a posição da fonte radioativa durante o processo de medição, aproximando-a do detector conforme sua atividade diminui e assim maximizando o número de contagens medidas. Neste trabalho, foi desenvolvido o Movimentador de Amostras Radioativas Automatizado (MARA), um aparato de baixo custo, feito com materiais de baixo número atômico e leve, projetado e construído para auxiliar nas medidas de espectroscopia gama, capaz de controlar a distância entre a fonte e o detector, permitindo inclusive que ocorra alteração dessa distância durante o processo de medição. Por ser automatizado ele otimiza o tempo do operador, que tem total liberdade para criar suas rotinas de medidas no dispositivo, além de evitar que o mesmo tome uma parcela da dose radioativa. Foi também feita uma interface que permite controle do MARA e a programação do sistema de aquisição de dados. Foram realizados testes para otimização da operação do sistema MARA e foi verificada a segurança de operação do MARA, não apresentando nenhuma falha durante seus testes. Foi aplicado o teste de repetitividade, por meio de medições com uma fonte calibrada de 60Co, e verificou-se que o sistema de movimentação de prateleiras automatizado reproduziu os resultados do sistema estático com confiabilidade de 95%.
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Esta dissertação apresenta o desenvolvimento de uma plataforma inercial autônoma com três graus de liberdade para aplicação em estabilização de sensores - por exemplo, gravimétricos estacionários e embarcados - podendo ser utilizada também para estabilização de câmeras. O sistema é formado pela Unidade de Medida Inercial, IMU, desenvolvida utilizando um sensor micro eletromecânico, MEMS - que possui acelerômetro, giroscópio e magnetômetros nos três eixos de orientação - e um microcontrolador para aquisição, processamento e envio dos dados ao sistema de controle e aquisição de dados. Para controle dos ângulos de inclinação e orientação da plataforma, foi implementado um controlador PID digital utilizando microcontrolador. Este recebe os dados da IMU e fornece os sinais de controle utilizando as saídas PWM que acionam os motores, os quais controlam a posição da plataforma. Para monitoramento da plataforma foi desenvolvido um programa para aquisição de dados em tempo real em ambiente Matlab, por meio do qual se pode visualizar e gravar os sinais da IMU, os ângulos de inclinação e a velocidade angular. Testou-se um sistema de transmissão de dados por rádio frequência entre a IMU e o sistema de aquisição de dados e controle para avaliar a possibilidade da não utilização de slip rings ou fios entre o eixo de rotação e os quadros da plataforma. Entretanto, verificou-se a inviabilidade da transmissão em razão da baixa velocidade de transmissão e dos ruídos captados pelo receptor de rádio frequência durante osmovimentos da plataforma. Sendo assim, dois pares de fios trançados foram utilizados fios para conectar o sensor inercial ao sistema de aquisição e processamento.
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In this project, we propose the implementation of a 3D object recognition system which will be optimized to operate under demanding time constraints. The system must be robust so that objects can be recognized properly in poor light conditions and cluttered scenes with significant levels of occlusion. An important requirement must be met: the system must exhibit a reasonable performance running on a low power consumption mobile GPU computing platform (NVIDIA Jetson TK1) so that it can be integrated in mobile robotics systems, ambient intelligence or ambient assisted living applications. The acquisition system is based on the use of color and depth (RGB-D) data streams provided by low-cost 3D sensors like Microsoft Kinect or PrimeSense Carmine. The range of algorithms and applications to be implemented and integrated will be quite broad, ranging from the acquisition, outlier removal or filtering of the input data and the segmentation or characterization of regions of interest in the scene to the very object recognition and pose estimation. Furthermore, in order to validate the proposed system, we will create a 3D object dataset. It will be composed by a set of 3D models, reconstructed from common household objects, as well as a handful of test scenes in which those objects appear. The scenes will be characterized by different levels of occlusion, diverse distances from the elements to the sensor and variations on the pose of the target objects. The creation of this dataset implies the additional development of 3D data acquisition and 3D object reconstruction applications. The resulting system has many possible applications, ranging from mobile robot navigation and semantic scene labeling to human-computer interaction (HCI) systems based on visual information.
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The commercial data acquisition systems used for seismic exploration are usually expensive equipment. In this work, a low cost data acquisition system (Geophonino) has been developed for recording seismic signals from a vertical geophone. The signal goes first through an instrumentation amplifier, INA155, which is suitable for low amplitude signals like the seismic noise, and an anti-aliasing filter based on the MAX7404 switched-capacitor filter. After that, the amplified and filtered signal is digitized and processed by Arduino Due and registered in an SD memory card. Geophonino is configured for continuous registering, where the sampling frequency, the amplitude gain and the registering time are user-defined. The complete prototype is an open source and open hardware system. It has been tested by comparing the registered signals with the ones obtained through different commercial data recording systems and different kind of geophones. The obtained results show good correlation between the tested measurements, presenting Geophonino as a low-cost alternative system for seismic data recording.
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A detailed investigation has been undertaken into the field induced electron emission (FIEE) mechanism that occurs at microscopically localised `sites' on uncoated and dielectric coated metallic electrodes. These processes have been investigated using two dedicated experimental systems that were developed for this study. The first is a novel combined photo/field emission microscope, which employs a UV source to stimulate photo-electrons from the sample surface in order to generate a topographical image. This system utilises an electrostatic lens column to provide identical optical properties under the different operating conditions required for purely topographical and combined photo/field imaging. The system has been demonstrated to have a resolution approaching 1m. Emission images have been obtained from carbon emission sites using this system to reveal that emission may occur from the edge triple junction or from the bulk of the carbon particle. An existing UHV electron spectrometer has been extensively rebuilt to incorporate a computer control and data acquisition system, improved sample handling and manipulation and a specimen heating stage. Details are given of a comprehensive study into the effects of sample heating on the emission process under conditions of both bulk and transient heating. Similar studies were also performed under conditions of both zero and high applied field. These show that the properties of emission sites are strongly temperature and field dependent thus indicating that the emission process is `non-metallic' in nature. The results have been shown to be consistent with an existing hot electron emission model.
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Computer integrated monitoring is a very large area in engineering where on-line, real time data acquisition with the aid of sensors is the solution to many problems in the manufacturing industry as opposed to the old data logging method by graphics analysis. The raw data which is collected this way however is useless in the absence of a proper computerized management system. The transfer of data between the management and the shop floor processes has been impossible in the past unless all the computers in the system were totally compatible with each other. This limits the efficiency of the systems because they get governed by the limitations of the computers. General Motors of U.S.A. have recently started research on a new standard called the Manufacturing Automation Protocol (MAP) which is expected to allow data transfer between different types of computers. This is still in early development stages and also is currently very expensive. This research programme shows how such a shop floor data acquisition system and a complete management system on entirely different computers can be integrated together to form a single system by achieving data transfer communications using a cheaper but a superior alternative to MAP. Standard communication character sets and hardware such as ASCII and UARTs have been used in this method but the technique is so powerful that totally incompatible computers are shown to run different programs (in different languages) simultaneously and yet receive data from each other and process in their own CPUs with no human intervention.
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With the competitive challenge facing business today, the need to keep cost down and quality up is a matter of survival. One way in which wire manufacturers can meet this challenge is to possess a thorough understanding of deformation, friction and lubrication during the wire drawing process, and therefore to make good decisions regarding the selection and application of lubricants as well as the die design. Friction, lubrication and die design during wire drawing thus become the subject of this study. Although theoretical and experimental investigations have been being carried out ever since the establishment of wire drawing technology, many problems remain unsolved. It is therefore necessary to conduct further research on traditional and fundamental subjects such as the mechanics of deformation, friction, lubrication and die design in wire drawing. Drawing experiments were carried out on an existing bull-block under different cross-sectional area reductions, different speeds and different lubricants. The instrumentation to measure drawing load and drawing speed was set up and connected to the wire drawing machine, together with a data acquisition system. A die box connected to the existing die holder for using dry soap lubricant was designed and tested. The experimental results in terms of drawing stress vs percentage area reduction curves under different drawing conditions were analysed and compared. The effects on drawing stress of friction, lubrication, drawing speed and pressure die nozzle are discussed. In order to determine the flow stress of the material during deformation, tensile tests were performed on an Instron universal test machine, using the wires drawn under different area reductions. A polynomial function is used to correlate the flow stress of the material with the plastic strain, on which a general computer program has been written to find out the coefficients of the stress-strain function. The residual lubricant film on the steel wire after drawing was examined both radially and longitudinally using an SEM and optical microscope. The lubricant film on the drawn wire was clearly observed. Therefore, the micro-analysis by SEM provides a way of friction and lubrication assessment in wire drawing.
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This paper addresses the problem of obtaining complete, detailed reconstructions of textureless shiny objects. We present an algorithm which uses silhouettes of the object, as well as images obtained under changing illumination conditions. In contrast with previous photometric stereo techniques, ours is not limited to a single viewpoint but produces accurate reconstructions in full 3D. A number of images of the object are obtained from multiple viewpoints, under varying lighting conditions. Starting from the silhouettes, the algorithm recovers camera motion and constructs the object's visual hull. This is then used to recover the illumination and initialize a multiview photometric stereo scheme to obtain a closed surface reconstruction. There are two main contributions in this paper: First, we describe a robust technique to estimate light directions and intensities and, second, we introduce a novel formulation of photometric stereo which combines multiple viewpoints and, hence, allows closed surface reconstructions. The algorithm has been implemented as a practical model acquisition system. Here, a quantitative evaluation of the algorithm on synthetic data is presented together with complete reconstructions of challenging real objects. Finally, we show experimentally how, even in the case of highly textured objects, this technique can greatly improve on correspondence-based multiview stereo results.