82 research outputs found

    Empleo de transformadores de un proceso "step down" para la calibración de aparatos de medida

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    Desde un punto de vista general se resume en la figura 7 las relaciones entre los usuarios, institutos de metrología y servicios de calibración. Los usuarios en general demandan calidad tanto en productos como servicios, las empresas a su vez demandan lo mismo de sus proveedores, así que al igual que las normas ISO por ejemplo se han convertido en una garantía, la acreditación electrométrica en este caso es una garantía de calidad, precisión y sobre todo trazabilidad. Tanto los fabricantes de instrumentación o servicios técnicos, los fabricantes de dispositivos eléctricos y electrónicos, laboratorios científicos, etc. , aseguran así que su instrumentación y todo los datos que se derivan, los dispositivos y material utilizados provenientes de otras marcas, etc., están en concordancia con los propios, tanto por la utilización del Sistema Internacional como por la precisión requerida. Los encargados de emitir estos certificados administrativos son los servicios de calibración de cada país, SIT en Italia y ENAC en el caso de España. Ambos actúan de modo paralelo realizando análogas actividades y acuerdan a nivel europeo a través de la EA el reconocimiento mutuo, aunque lo puedan hacer también con terceros países particularmente, y mantienen relaciones bilaterales con cada entidad de acreditación. De forma muy parecida los Institutos científicos de cada país, IEN en Italia y CEM en España, son los encargados de emitir los certificados técnicos de la instrumentación y procedimientos sirviendo de este modo de referencia científica a las entidades de acreditación. Mantienen relaciones bilaterales con otros Institutos aunque los puntos comunes y de encuentro sean la Conferencia General de Pesas y Medidas, Organización Internacional de Metrología Legal, European Collaboration in Measurement Standards, International Measurement Confederation y la Western European Legal Metrology Cooperation.Escuela Técnica Superior de Ingeniería Industria

    Modeling and Analysis of Power Processing Systems

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    The feasibility of formulating a methodology for the modeling and analysis of aerospace electrical power processing systems is investigated. It is shown that a digital computer may be used in an interactive mode for the design, modeling, analysis, and comparison of power processing systems

    ULTRA LOW POWER FSK RECEIVER AND RF ENERGY HARVESTER

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    This thesis focuses on low power receiver design and energy harvesting techniques as methods for intelligently managing energy usage and energy sources. The goal is to build an inexhaustibly powered communication system that can be widely applied, such as through wireless sensor networks (WSNs). Low power circuit design and smart power management are techniques that are often used to extend the lifetime of such mobile devices. Both methods are utilized here to optimize power usage and sources. RF energy is a promising ambient energy source that is widely available in urban areas and which we investigate in detail. A harvester circuit is modeled and analyzed in detail at low power input. Based on the circuit analysis, a design procedure is given for a narrowband energy harvester. The antenna and harvester co-design methodology improves RF to DC energy conversion efficiency. The strategy of co-design of the antenna and the harvester creates opportunities to optimize the system power conversion efficiency. Previous surveys have found that ambient RF energy is spread broadly over the frequency domain; however, here it is demonstrated that it is theoretically impossible to harvest RF energy over a wide frequency band if the ambient RF energy source(s) are weak, owing to the voltage requirements. It is found that most of the ambient RF energy lies in a series of narrow bands. Two different versions of harvesters have been designed, fabricated, and tested. The simulated and measured results demonstrate a dual-band energy harvester that obtains over 9% efficiency for two different bands (900MHz and 1800MHz) at an input power as low as -19dBm. The DC output voltage of this harvester is over 1V, which can be used to recharge the battery to form an inexhaustibly powered communication system. A new phase locked loop based receiver architecture is developed to avoid the significant conversion losses associated with OOK architectures. This also helps to minimize power consumption. A new low power mixer circuit has also been designed, and a detailed analysis is provided. Based on the mixer, a low power phase locked loop (PLL) based receiver has been designed, fabricated and measured. A power management circuit and a low power transceiver system have also been co-designed to provide a system on chip solution. The low power voltage regulator is designed to handle a variety of battery voltage, environmental temperature, and load conditions. The whole system can work with a battery and an application specific integrated circuit (ASIC) as a sensor node of a WSN network

    OGO-E-16 search coil magnetometer

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    Design of coil magnetometer for measuring geomagnetic and interplanetary field fluctuations by triaxial spectrum analysi

    The Investigation and Implementation of electrical Impedance Tomography Hardware System

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    Electrical impedance tomography (EIT) is a medical imaging technology that provides a tomographic representation of the distribution of electrical impedance within the body. As the electrical impedance varies for different body tissues, it is possible to characterize tissues from the images and to detect physiological events. EIT systems have been developed from applying a single signal frequency to a range of frequencies. Imaging at multiple frequencies significantly improves the ability to characterize and differentiate heterogeneity within the region of interest. Applications of EIT are limited by its poor resolution as a consequence of limited number of electrodes and lack of independently published measurements. In a practical EIT system design the parallel structure is normally adopted as it provides a real time monitoring structure. However, there is a difficulty in expanding to a 2-dimensitional or 3-dimensitional high resolution imaging system, as the number of electrodes increase. In this thesis, a serial structure spectrum EIT system has been investigated and developed. Modelling of the electrical circuit has shown that the system bandwidth is degraded primarily by the signal transmission in the coaxial cable and multiplexer. To remove the capacitive effect of these components, a distribute system concept has been developed. The concept uses active electrodes in which a current source and a front end amplifier are embedded in the electrode which makes direct contact with the tissue being measured. The active electrode is based on the Howland current source. The required high output impedance of Howland current source can be realised by matching the two resistor arms. However, from the electrical equivalent circuit analysis the actual output impedance of this circuit was found to be degraded by the op-amp' s limited open loop gain, especially at higher frequencies. To solve the problem, the author describes in detail a novel method of compensating for the above effects. Subsequent circuit tests showed significant improvement after the compensation. Further, to improve the small signal noise ratio a programmable gain amplifier to adapt the frame data measurement was developed. These developments have led to the feasibility of active electrodes. The thesis describes in detail the development, of the MK2 EIT system which is presented as the output of this research

    Development and fabrication of S-band chip varactor parametric amplifier

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    A noncryogenic, S-band parametric amplifier operating in the 2.2 to 2.3 GHz band and having an average input noise temperature of less than 30 K was built and tested. The parametric amplifier module occupies a volume of less than 1-1/4 cubic feet and weighs less than 60 pounds. The module is designed for use in various NASA ground stations to replace larger, more complex cryogenic units which require considerably more maintenance because of the cryogenic refrigeration system employed. The amplifier can be located up to 15 feet from the power supply unit. Optimum performance was achieved through the use of high-quality unpackaged (chip) varactors in the amplifier design

    Distribution Line Multi-tool

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    Power companies are always interested in the best possible monitoring equipment for their grid. The power line multi-tool developed would aid in the monitoring of the power system’s distribution network. This device assesses the current conditions of distribution power lines. The device is able to measure current, detect downed power lines, as well as recognize fire starting conditions, and have wireless communication for ease of access and installation. Overall this device greatly aids in helping utilities monitor their grid in more detail. With the increase of dry climates yearly, several utility companies are taking measures to aid in the prevention of power line based fires. The use of the distribution line multi-tool gives power companies an additional resource in fire prevention. With accurate data received, power companies can take the necessary precautions to prevent power line based fires. One of the deadliest and most destructive fires of recent history in Paradise California has put power companies on high alert and motivated the state to provide funding to utilities to harden their infrastructure and a product like this fits perfectly into this agenda of fire mitigation. With hundreds of thousands of distribution lines throughout California’s vast terrain, monitoring them has become a cumbersome task yet more necessary in recent years. With a drier than usual climate, the environment has become more prone to fire, especially with areas with distribution lines running through them. With high distribution voltages used and the occurrence of large short circuits on these systems, downed power lines can create fire hazards. A number of factors can cause downed power lines, which includes galloping from winds, impact based falls, and excessive tension on distribution cables or poles. When these poles fall, they have the potential to not only cause a short circuit, which can damage nearby equipment or turn off the power for customers but also cause fires. These high voltages and extreme transient currents mixed in a dry, wilted environment increases the opportunity for a fire to be started but for it to also spread with ease

    Engineering report - OGO-F-22 search coil magnetometer

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    Development of OGO-F-22 triaxial search coil magnetometer for measuring geomagnetic and interplanetary field intensitie

    Study of applications of bio-space technology to patient monitoring systems Progress report

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    Patient monitoring system design and equipment specifications with physiological response display device and warning syste

    Study of applications of bio-space technology to patient monitoring systems Final report

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    Investigation of application of NASA developed technology to cardiovascular and pulmonary patient monitoring to improve availability of data for medical diagnosi
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