949 resultados para Sensors and actuators
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Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Automação e Eletrotécnica Ramo de Automação e Eletrónica Industrial
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Atualmente, sensores remotos e computadores de alto desempenho estão sendo utilizados como instrumentos principais na coleta e produção de dados oceanográficos. De posse destes dados, é possível realizar estudos que permitem simular e prever o comportamento do oceano por meio de modelos numéricos regionais. Dentre os fatores importantes no estudo da oceanografia, podem ser destacados àqueles referentes aos impactos ambientais, de contaminação antrópica, utilização de energias renováveis, operações portuárias e etc. Contudo, devido ao grande volume de dados gerados por instituições ambientais, na forma de resultados de modelos globais como o HYCOM (Hybrid Coordinate Ocean Model) e dos programas de Reanalysis da NOAA (National Oceanic and Atmospheric Administration), torna-se necessária a criação de rotinas computacionais para realizar o tratamento de condições iniciais e de contorno, de modo que possam ser aplicadas a modelos regionais como o TELEMAC3D (www.opentelemac.org). Problemas relacionados a baixa resolução, ausência de dados e a necessidade de interpolação para diferentes malhas ou sistemas de coordenadas verticais, tornam necessária a criação de um mecanismo computacional que realize este tratamento adequadamente. Com isto, foram desenvolvidas rotinas na linguagem de programação Python, empregando interpoladores de vizinho mais próximo, de modo que, a partir de dados brutos dos modelos HYCOM e do programa de Reanalysis da NOAA, foram preparadas condições iniciais e de contorno para a realização de uma simulação numérica teste. Estes resultados foram confrontados com outro resultado numérico onde, as condições foram construídas a partir de um método de interpolação mais sofisticado, escrita em outra linguagem, e que já vem sendo utilizada no laboratório. A análise dos resultados permitiu concluir que, a rotina desenvolvida no âmbito deste trabalho, funciona adequadamente para a geração de condições iniciais e de contorno do modelo TELEMAC3D. Entretanto, um interpolador mais sofisticado deve ser desenvolvido de forma a aumentar a qualidade nas interpolações, otimizar o custo computacional, e produzir condições que sejam mais realísticas para a utilização do modelo TELEMAC3D.
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This work presents an application of optical fiber sensors based on Bragg gratings integrated to a transtibial prosthesis tube manufactured with a polymeric composite systrem of epoxy resin reinforced with glass fiber. The main objective of this study is to characterize the sensors applied to the gait cycle and changes in the gravity center of a transtibial amputee, trough the analysis of deformation and strengh of the transtibial prosthesis tube. For this investigation it is produced a tube of the composite material described above using the molding method of resin transfer (RTM) with four optical sensors. The prosthesis in which the original tube is replaced is classified as endoskeletal, has vacuum fitting, aluminium conector tube and carbon fiber foot cushioning. The volunteer for the tests was a man of 41 years old, 1.65 meters tall, 72 kilograms and left-handed. His amputation occurred due to trauma (surgical section is in the medial level, and was made below the left lower limb knee). He has been a transtibial prosthesis user for two years and eight months. The characterization of the optical sensors and analysis of mechanical deformation and tube resistance occurred through the gait cycle and the variation of the center of gravity of the body by the following tests: stand up, support leg without the prosthesis, support in the leg with the prosthesis, walk forward and walk backward. Besides the characterization of optical sensors during the gait cycle and the variation of the gravity center in a transtibial amputated, the results also showed a high degree of integration of the sensors in the composite and a high mechanical strength of the material.
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As azeitonas de mesa são consumidas e apreciadas em todo o mundo e, embora a sua classificação comercial não seja legalmente exigida, o Conselho Oleícola Internacional sugere que seja regulamentada com base na avaliação sensorial por um painel de provadores. A implementação de tal requer o cumprimento de diretrizes estabelecidas pelo Conselho Oleícola Internacional, resultando numa tarefa complexa, demorada e cujas avaliações não estão isentas de subjetividade. Neste trabalho, pela primeira vez, uma língua eletrónica foi utilizada com o intuito de classificar azeitonas de mesa em categorias comerciais, estipuladas com base na presença e na mediana das intensidades do defeito organolético predominante percebido pelo painel de provadores. Modelos de discriminação lineares foram estabelecidos com base em subconjuntos de sinais potenciométricos de sensores da língua eletrónica, selecionados recorrendo ao algoritmo de arrefecimento simulado. Os desempenhos qualitativo de previsão dos modelos de classificação estabelecidos foram avaliados recorrendo à técnica de validação cruzada leave-one-out e à técnica de validação cruzada K-folds com repetição, que permite minimizar o risco de sobreajustamento, permitindo obter resultados mais realistas. O potencial desta abordagem qualitativa, baseada nos perfis eletroquímicos gerados pela língua eletrónica, foi satisfatoriamente demonstrado: (i) na classificação correta (sensibilidades ≥ 93%) de soluções padrão (ácido n-butírico, 2-mercaptoetanol e ácido ciclohexanocarboxílico) de acordo com o defeito sensorial que mimetizam (butírico, pútrido ou sapateira); (ii) na classificação correta (sensibilidades ≥ 93%) de amostras de referência de azeitonas e salmouras (presença de um defeito único intenso) de acordo com o tipo de defeito percebido (avinhado-avinagrado, butírico, mofo, pútrido ou sapateira), e selecionadas pelo painel de provadores; e, (iii) na classificação correta (sensibilidade ≥ 86%) de amostras de azeitonas de mesa com grande heterogeneidade, contendo um ou mais defeitos organoléticos percebidos pelo painel de provadores nas azeitona e/ou salmouras, de acordo com a sua categoria comercial (azeitona extra sem defeito, extra, 1ª escolha, 2ª escolha e azeitonas que não podem ser comercializadas como azeitonas de mesa). Por fim, a capacidade língua eletrónica em quantificar as medianas das intensidades dos atributos negativos detetados pelo painel nas azeitonas de mesa foi demonstrada recorrendo a modelos de regressão linear múltipla-algoritmo de arrefecimento simulado, com base em subconjuntos selecionados de sinais gerados pela língua eletrónica durante a análise potenciométrica das azeitonas e salmouras. O xii desempenho de previsão dos modelos quantitativos foi validado recorrendo às mesmas duas técnicas de validação cruzada. Os modelos estabelcidos para cada um dos 5 defeitos sensoriais presentes nas amostras de azeitona de mesa, permitiram quantificar satisfatoriamente as medianas das intensidades dos defeitos (R² ≥ 0,97). Assim, a qualidade satisfatória dos resultados qualitativos e quantitativos alcançados permite antever, pela primeira vez, uma possível aplicação prática das línguas eletrónicas como uma ferramenta de análise sensorial de defeitos em azeitonas de mesa, podendo ser usada como uma técnica rápida, económica e útil na avaliação organolética de atributos negativos, complementar à tradicional análise sensorial por um painel de provadores.
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Los sistemas fotovoltaicos son fuentes emergentes de energías renovables que generan electricidad a partir de la radiación solar. El monitoreo de los sistemas fotovoltaicos aislados proporciona información necesaria que permite a sus propietarios mantener, operar y controlar estos sistemas, reduciendo los costes de operación y evitando indeseadas interrupciones en el suministro eléctrico de zonas aisladas. En este artículo, se propone el desarrollo de una plataforma para el monitoreo de sistemas fotovoltaicos aislados en el Ecuador con el objetivo fundamental de desarrollar una solución escalable, basada en el uso de software libre, en el empleo de sensores de bajo consumo y en el desarrollo de servicios web en la modalidad ‘Software as a Service’ (SaaS) para el procesamiento, gestión y publicación de información registrada y la creación de un innovador centro de control solar fotovoltaico en el Ecuador.
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Rapid, sensitive and selective detection of chemical hazards and biological pathogens has shown growing importance in the fields of homeland security, public safety and personal health. In the past two decades, efforts have been focusing on performing point-of-care chemical and biological detections using miniaturized biosensors. These sensors convert target molecule binding events into measurable electrical signals for quantifying target molecule concentration. However, the low receptor density and the use of complex surface chemistry in receptors immobilization on transducers are common bottlenecks in the current biosensor development, adding to the cost, complexity and time. This dissertation presents the development of selective macromolecular Tobacco mosaic virus-like particle (TMV VLP) biosensing receptor, and the microsystem integration of VLPs in microfabricated electrochemical biosensors for rapid and performance-enhanced chemical and biological sensing. Two constructs of VLPs carrying different receptor peptides targeting at 2,4,6-trinitrotoluene (TNT) explosive or anti-FLAG antibody are successfully bioengineered. The VLP-based TNT electrochemical sensor utilizes unique diffusion modulation method enabled by biological binding between target TNT and receptor VLP. The method avoids the influence from any interfering species and environmental background signals, making it extremely suitable for directly quantifying the TNT level in a sample. It is also a rapid method that does not need any sensor surface functionalization process. For antibody sensing, the VLPs carrying both antibody binding peptides and cysteine residues are assembled onto the gold electrodes of an impedance microsensor. With two-phase immunoassays, the VLP-based impedance sensor is able to quantify antibody concentrations down to 9.1 ng/mL. A capillary microfluidics and impedance sensor integrated microsystem is developed to further accelerate the process of VLP assembly on sensors and improve the sensitivity. Open channel capillary micropumps and stop-valves facilitate localized and evaporation-assisted VLP assembly on sensor electrodes within 6 minutes. The VLP-functionalized impedance sensor is capable of label-free sensing of antibodies with the detection limit of 8.8 ng/mL within 5 minutes after sensor functionalization, demonstrating great potential of VLP-based sensors for rapid and on-demand chemical and biological sensing.
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Continuous Synthesis by Solution Combustion was employed in this work aiming to obtain tin dioxide nanostructured. Basically, a precursor solution is prepared and then be atomized and sprayed into the flame, where its combustion occurs, leading to the formation of particles. This is a recent technique that shows an enormous potential in oxides deposition, mainly by the low cost of equipment and precursors employed. The tin dioxide (SnO2) nanostructured has been widely used in various applications, especially as gas sensors and varistors. In the case of sensors based on semiconducting ceramics, where surface reactions are responsible for the detection of gases, the importance of surface area and particle size is even greater. The preference for a nanostructured material is based on its significant increase in surface area compared to conventional microcrystalline powders and small particle size, which may benefit certain properties such as high electrical conductivity, high thermal stability, mechanical and chemical. In this work, were employed as precursor solution tin chloride dehydrate diluted in anhydrous ethyl alcohol. Were utilized molar ratio chloride/solvent of 0,75 with the purpose of investigate its influence in the microstructure of produced powder. The solution precursor flux was 3 mL/min. Analysis with X-ray diffraction appointed that a solution precursor with molar ratio chloride/solvent of 0,75 leads to crystalline powder with single phase and all peaks are attributed to phase SnO2. Parameters as distance from the flame with atomizer distance from the capture system with the pilot, molar ratio and solution flux doesn t affect the presence of tin dioxide in the produced powder. In the characterization of the obtained powder techniques were used as thermogravimetric (TGA) and thermodiferential analysis (DTA), particle size by laser diffraction (GDL), crystallographic analysis by X-ray diffraction (XRD), morphology by scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and electrical conductivity analysis. The techniques used revealed that the SnO2 exhibits behavior of a semiconductor material, and a potentially promising material for application as varistor and sensor systems for gas
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Diseñar y construir un robot acuático que destruya la presencia de larvas o pupas de mosquitos en contenedores de agua. Se construyó y se diseñó un robot con materiales reciclables construido con tubos de cañería PVC, lupa, sensores de luz y barrera, motor de fuente 110 v, resistencias, LCR, cargador 9 v y focos led, para que destruya larvas de mosquitos en un contenedor de agua. Como resultado hay una cero prevalencia de índice larvario porque el robot detecta presencia larvaria con sensores y rayos laser activándose automáticamente con el efecto de succión y destrucción larvas en su interior eliminándolas desechas al utilizar filtros de 10 micras y aspas metálicas, el robot se activa por cinco a diez minutos y se apaga automáticamente hasta esperar la alarma otra vez según disposición de larvas. Conclusión el uso del robot acuático en contenedores de agua no se encuentra índices larvarios, así como pupas, que puede ser utilizado como control antilarvario para el combate transmisor de Dengue, Zika, Chikungunya entre otros.
Design and build an aquatic robot to destroy the presence of larvae or pupae of mosquitoes in water containers. It was built and a robot with recyclables built with tubes pipe PVC, magnifier, light sensors and barrier, engine power 110 v, resistors, LCR, charger 9 vy spotlights led, to destroy mosquito larvae was designed in a container of water. As a result there is a zero prevalence Larval rate because the robot detects larval presence sensors and lasers automatically activated with the suction effect and larvae destruction their killing the inner cast off using filters of 10 microns and metal blades, the robot is activated by five to ten minutes to wait automatically turns off the alarm again available as larvae. Conclusion use water in water containers robot is not larval indices and pupae, which can be used as anti larval control for transmitter combat Dengue, Zika, Chikungunya among others.
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Ambipolar organic field-effect transistors (OFETs), which can efficiently transport both holes and electrons, using a single type of electrode, are currently of great interest due to their possible applications in complementary metal oxide semiconductor (CMOS)-like circuits, sensors, and in light-emitting transistors. Several theoretical and experimental studies have argued that most organic semiconductors should be able to transport both types of carrier, although typically unipolar behavior is observed. One factor that can compromise ambipolar transport in organic semiconductors is poor solid state overlap between the HOMO (p-type) or LUMO (n-type) orbitals of neighboring molecules in the semiconductor thin film. In the search of low-bandgap ambipolar materials, where the absence of skeletal distortions allows closer intermolecular π-π stacking and enhanced intramolecular π-conjugation, a new family of oligothiophene-naphthalimide assemblies have been synthesized and characterized, in which both donor and acceptor moieties are directly conjugated through rigid linkers. In previous works we found that oligothiophene-napthalimide assemblies connected through amidine linkers (NDI derivates) exhibit skeletal distortions (50-60º) arising from steric hindrance between the carbonyl group of the arylene core and the sulphur atom of the neighbored thiophene ring (see Figure 1). In the present work we report novel oligo- and polythiophene–naphthalimide analogues NAI-3T, NAI-5T and poly-NAI-8C-3T, in which the connections of the amidine linkage have been inverted in order to prevent steric interactions. Thus, the nitrogen atoms are directly connected to the naphthalene moiety in NAI derivatives while they were attached directly to the thiophene moiety in the previously investigated NDI-3T and NDI-5T. In Figure 1 is depicted the calculated molecular structure of NAI-3T together with that of NDI-3T showing how the steric interactions are not present in the novel NAI derivative. The planar skeletons in these new family induce higher degree of crystallinity and the carrier charge transport can be switched from n-type to ambipolar behaviour. The highest FET performance is achieved for vapor-deposited films of NAI-3T with mobilities of 1.95x10-4cm2V-1s-1 and 2.00x10-4cm2V-1s-1 for electrons and holes, respectively. Finally, these planar semiconductors are compared with their NDI derivates analogues, which exhibit only n-type mobility, in order to understand the origin of the ambipolarity in this new series of molecular semiconductors.
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Sensor networks are becoming popular nowadays in the development of smart environments. Heavily relying on static sensor and actuators, though, such environments usually lacks of versatility regarding the provided services and interaction capabilities. Here we present a framework for smart environments where a service robot is included within the sensor network acting as a mobile sensor and/or actuator. Our framework integrates on-the-shelf technologies to ensure its adaptability to a variety of sensor technologies and robotic software. Two pilot cases are presented as evaluation of our proposal.
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Mobile sensor networks have unique advantages compared with wireless sensor networks. The mobility enables mobile sensors to flexibly reconfigure themselves to meet sensing requirements. In this dissertation, an adaptive sampling method for mobile sensor networks is presented. Based on the consideration of sensing resource constraints, computing abilities, and onboard energy limitations, the adaptive sampling method follows a down sampling scheme, which could reduce the total number of measurements, and lower sampling cost. Compressive sensing is a recently developed down sampling method, using a small number of randomly distributed measurements for signal reconstruction. However, original signals cannot be reconstructed using condensed measurements, as addressed by Shannon Sampling Theory. Measurements have to be processed under a sparse domain, and convex optimization methods should be applied to reconstruct original signals. Restricted isometry property would guarantee signals can be recovered with little information loss. While compressive sensing could effectively lower sampling cost, signal reconstruction is still a great research challenge. Compressive sensing always collects random measurements, whose information amount cannot be determined in prior. If each measurement is optimized as the most informative measurement, the reconstruction performance can perform much better. Based on the above consideration, this dissertation is focusing on an adaptive sampling approach, which could find the most informative measurements in unknown environments and reconstruct original signals. With mobile sensors, measurements are collect sequentially, giving the chance to uniquely optimize each of them. When mobile sensors are about to collect a new measurement from the surrounding environments, existing information is shared among networked sensors so that each sensor would have a global view of the entire environment. Shared information is analyzed under Haar Wavelet domain, under which most nature signals appear sparse, to infer a model of the environments. The most informative measurements can be determined by optimizing model parameters. As a result, all the measurements collected by the mobile sensor network are the most informative measurements given existing information, and a perfect reconstruction would be expected. To present the adaptive sampling method, a series of research issues will be addressed, including measurement evaluation and collection, mobile network establishment, data fusion, sensor motion, signal reconstruction, etc. Two dimensional scalar field will be reconstructed using the method proposed. Both single mobile sensors and mobile sensor networks will be deployed in the environment, and reconstruction performance of both will be compared.In addition, a particular mobile sensor, a quadrotor UAV is developed, so that the adaptive sampling method can be used in three dimensional scenarios.
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Wireless Sensor Networks (WSNs) are widely used for various civilian and military applications, and thus have attracted significant interest in recent years. This work investigates the important problem of optimal deployment of WSNs in terms of coverage and energy consumption. Five deployment algorithms are developed for maximal sensing range and minimal energy consumption in order to provide optimal sensing coverage and maximum lifetime. Also, all developed algorithms include self-healing capabilities in order to restore the operation of WSNs after a number of nodes have become inoperative. Two centralized optimization algorithms are developed, one based on Genetic Algorithms (GAs) and one based on Particle Swarm Optimization (PSO). Both optimization algorithms use powerful central nodes to calculate and obtain the global optimum outcomes. The GA is used to determine the optimal tradeoff between network coverage and overall distance travelled by fixed range sensors. The PSO algorithm is used to ensure 100% network coverage and minimize the energy consumed by mobile and range-adjustable sensors. Up to 30% - 90% energy savings can be provided in different scenarios by using the developed optimization algorithms thereby extending the lifetime of the sensor by 1.4 to 10 times. Three distributed optimization algorithms are also developed to relocate the sensors and optimize the coverage of networks with more stringent design and cost constraints. Each algorithm is cooperatively executed by all sensors to achieve better coverage. Two of our algorithms use the relative positions between sensors to optimize the coverage and energy savings. They provide 20% to 25% more energy savings than existing solutions. Our third algorithm is developed for networks without self-localization capabilities and supports the optimal deployment of such networks without requiring the use of expensive geolocation hardware or energy consuming localization algorithms. This is important for indoor monitoring applications since current localization algorithms cannot provide good accuracy for sensor relocation algorithms in such indoor environments. Also, no sensor redeployment algorithms, which can operate without self-localization systems, developed before our work.
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In recent years, there has been an enormous growth of location-aware devices, such as GPS embedded cell phones, mobile sensors and radio-frequency identification tags. The age of combining sensing, processing and communication in one device, gives rise to a vast number of applications leading to endless possibilities and a realization of mobile Wireless Sensor Network (mWSN) applications. As computing, sensing and communication become more ubiquitous, trajectory privacy becomes a critical piece of information and an important factor for commercial success. While on the move, sensor nodes continuously transmit data streams of sensed values and spatiotemporal information, known as ``trajectory information". If adversaries can intercept this information, they can monitor the trajectory path and capture the location of the source node. This research stems from the recognition that the wide applicability of mWSNs will remain elusive unless a trajectory privacy preservation mechanism is developed. The outcome seeks to lay a firm foundation in the field of trajectory privacy preservation in mWSNs against external and internal trajectory privacy attacks. First, to prevent external attacks, we particularly investigated a context-based trajectory privacy-aware routing protocol to prevent the eavesdropping attack. Traditional shortest-path oriented routing algorithms give adversaries the possibility to locate the target node in a certain area. We designed the novel privacy-aware routing phase and utilized the trajectory dissimilarity between mobile nodes to mislead adversaries about the location where the message started its journey. Second, to detect internal attacks, we developed a software-based attestation solution to detect compromised nodes. We created the dynamic attestation node chain among neighboring nodes to examine the memory checksum of suspicious nodes. The computation time for memory traversal had been improved compared to the previous work. Finally, we revisited the trust issue in trajectory privacy preservation mechanism designs. We used Bayesian game theory to model and analyze cooperative, selfish and malicious nodes' behaviors in trajectory privacy preservation activities.
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With the eye-catching advances in sensing technologies, smart water networks have been attracting immense research interest in recent years. One of the most overarching tasks in smart water network management is the reduction of water loss (such as leaks and bursts in a pipe network). In this paper, we propose an efficient scheme to position water loss event based on water network topology. The state-of-the-art approach to this problem, however, utilizes the limited topology information of the water network, that is, only one single shortest path between two sensor locations. Consequently, the accuracy of positioning water loss events is still less desirable. To resolve this problem, our scheme consists of two key ingredients: First, we design a novel graph topology-based measure, which can recursively quantify the "average distances" for all pairs of senor locations simultaneously in a water network. This measure will substantially improve the accuracy of our positioning strategy, by capturing the entire water network topology information between every two sensor locations, yet without any sacrifice of computational efficiency. Then, we devise an efficient search algorithm that combines the "average distances" with the difference in the arrival times of the pressure variations detected at sensor locations. The viable experimental evaluations on real-world test bed (WaterWiSe@SG) demonstrate that our proposed positioning scheme can identify water loss event more accurately than the best-known competitor.
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Axle bearing damage with possible catastrophic failures can cause severe disruptions or even dangerous derailments, potentially causing loss of human life and leading to significant costs for railway infrastructure managers and rolling stock operators. Consequently the axle bearing damage process has safety and economic implications on the exploitation of railways systems. Therefore it has been the object of intense attention by railway authorities as proved by the selection of this topic by the European Commission in calls for research proposals. The MAXBE Project (http://www.maxbeproject.eu/), an EU-funded project, appears in this context and its main goal is to develop and to demonstrate innovative and efficient technologies which can be used for the onboard and wayside condition monitoring of axle bearings. The MAXBE (interoperable monitoring, diagnosis and maintenance strategies for axle bearings) project focuses on detecting axle bearing failure modes at an early stage by combining new and existing monitoring techniques and on characterizing the axle bearing degradation process. The consortium for the MAXBE project comprises 18 partners from 8 member states, representing operators, railway administrations, axle bearing manufactures, key players in the railway community and experts in the field of monitoring, maintenance and rolling stock. The University of Porto is coordinating this research project that kicked-off in November 2012 and it is completed on October 2015. Both on-board and wayside systems are explored in the project since there is a need for defining the requirement for the onboard equipment and the range of working temperatures of the axle bearing for the wayside systems. The developed monitoring systems consider strain gauges, high frequency accelerometers, temperature sensors and acoustic emission. To get a robust technology to support the decision making of the responsible stakeholders synchronized measurements from onboard and wayside monitoring systems are integrated into a platform. Also extensive laboratory tests were performed to correlate the in situ measurements to the status of the axle bearing life. With the MAXBE project concept it will be possible: to contribute to detect at an early stage axle bearing failures; to create conditions for the operational and technical integration of axle bearing monitoring and maintenance in different European railway networks; to contribute to the standardization of the requirements for the axle bearing monitoring, diagnosis and maintenance. Demonstration of the developed condition monitoring systems was performed in Portugal in the Northern Railway Line with freight and passenger traffic with a maximum speed of 220 km/h, in Belgium in a tram line and in the UK. Still within the project, a tool for optimal maintenance scheduling and a smart diagnostic tool were developed. This paper presents a synthesis of the most relevant results attained in the project. The successful of the project and the developed solutions have positive impact on the reliability, availability, maintainability and safety of rolling stock and infrastructure with main focus on the axle bearing health.