Technology evaluation of heating, ventilation, and air conditioning for MIUS application

Potential ways of providing heating, ventilation, and air conditioning for a building complex serviced by a modular integrated utility system (MIUS) are examined. Literature surveys were conducted to investigate both conventional and unusual systems to serve this purpose. The advantages and disadvantages of the systems most compatible with MIUS are discussed

Thermal characterisation of miniature hotplates used in gas sensing technology

The reliability of micro-electronic devices depends on the device operating temperature and therefore self-heating can have an adverse effect on the performance and reliability of these devices. Hence, thermal measurement is crucial including accurate maximum operating temperature measurements to ensure optimum reliability and good electrical performance. In the research presented in this thesis, the high temperature thermal characterisation of novel micro-electro-mechanical systems (MEMS) infra-red (IR) emitter chips for use in gas sensing technology for stable long-term operation were studied, using both IR and a novel thermo-incandescence microscopy. The IR emitters were fabricated using complementary-metal-oxide semiconductor (CMOS) based processing technology and consisted of a miniature micro-heater, fabricated using tungsten metallisation. There is a commercial drive to include MEMS micro-heaters in portable electronic applications including gas sensors and miniaturised IR spectrometers where low power consumption is required. IR thermal microscopy was used to thermally characterise these miniature MEMS micro-heaters to temperatures approaching 700 °C. The research work has also enabled further development of novel thermal measurement techniques, using carbon microparticle infra-red sensors (MPIRS) with the IR thermal microscopy. These microparticle sensors, for the first time, have been used to make more accurate high temperature (approaching 700 °C) spot measurements on the IR transparent semiconductor membrane of the micro-heater. To substantially extend the temperature measurement range of the IR thermal microscope, and to obtain the thermal profiles at elevated temperatures (> 700 °C), a novel thermal measurement approach has been developed by calibrating emitted incandescence radiation in the optical region as a function of temperature. The calibration was carried out using the known melting point (MP) of metal microparticles. The method has been utilised to obtain the high temperature thermo-optical characterisation of the MEMS micro-heaters to temperatures in excess of 1200 °C. The measured temperature results using thermo-incandescence microscopy were compared with calculated electrical temperature results. The results indicated the thermo-incandescence measurements are in reasonable agreement (± 3.5 %) with the electrical temperature approach. Thus, the measurement technique using optical incandescent radiation extends the range of conventional IR microscopy and shows a great potential for making very high temperature spot measurements on electronic devices. The high power (> 500mW) electrical characterisation of the MEMS micro-heaters were also analysed to assess the reliability. The electrical performance results on the MEMS micro-heaters indicated failures at temperatures greater than 1300 °C and Scanning Electron Microscope (SEM) was used to analyse the failure modes

The NASA SBIR product catalog

The purpose of this catalog is to assist small business firms in making the community aware of products emerging from their efforts in the Small Business Innovation Research (SBIR) program. It contains descriptions of some products that have advanced into Phase 3 and others that are identified as prospective products. Both lists of products in this catalog are based on information supplied by NASA SBIR contractors in responding to an invitation to be represented in this document. Generally, all products suggested by the small firms were included in order to meet the goals of information exchange for SBIR results. Of the 444 SBIR contractors NASA queried, 137 provided information on 219 products. The catalog presents the product information in the technology areas listed in the table of contents. Within each area, the products are listed in alphabetical order by product name and are given identifying numbers. Also included is an alphabetical listing of the companies that have products described. This listing cross-references the product list and provides information on the business activity of each firm. In addition, there are three indexes: one a list of firms by states, one that lists the products according to NASA Centers that managed the SBIR projects, and one that lists the products by the relevant Technical Topics utilized in NASA's annual program solicitation under which each SBIR project was selected

Smart Platform for Low-Cost MEMS Sensors – Pressure, Flow and Thermal Conductivity

In a technological world that is trending towards smart and autonomous engineering, the collection of quality data is of unrivalled importance. This has led to a huge market demand for the development of low-cost, small and accurate sensors and thus has resulted in significant research into sensors, with the aim of advancing the price/performance ratio in commercial solutions. Micro Electro Mechanical Systems (MEMS) have recently offered an attractive solution to miniaturise and drastically improve the performance of sensors. In this thesis, MEMS technology is exploited to create a multi-sensor technology platform that is used to fabricate several sensing technologies. Piezo-resistive and piezo-electronic pressure sensors are designed, fabricated and tested. Different doping profiles, stress-engineered structures and electronic devices for pressure transduction are investigated, with focus on their sensitivity and non-linearity. A ring is fabricated in the metal layer around the circumference of the membrane that alleviates the effects of over/under etching. This is achieved by creating a new rigid edge of the membrane in the metal layer, which has tighter fabrication tolerances. A piezo-MOSFET is developed and shown to have greater sensitivity than similar state-of-the-art devices. Flow sensors based on a heated tungsten wire are designed, fabricated, tested and substantiated with numerical modelling. Calorimetric and anemometric driving modes are optimised with regards to device structure. Thermodiodes are also used as the temperature transduction devices and are compared to the traditional resistor method and showed to be preferable when further miniaturising the sensor. Thermal conductivity gas sensors based on a heated tungsten resistor are designed, tested and substantiated with numerical modelling. Holes through the membrane are used to improve the sensitivity to measuring carbon dioxide by 270%. Asymmetric holes are utilised to prove a novel method of measuring thermal conductivity in a calorimetric method. Designs improving this new concept are outlined and substantiated with analytical and numerical models. Linear statistical methods and artificial neural networks are used to differentiate flow rate and gas concentration using three on-membrane resistors. With membrane holes, the discrimination between gases in the presence of flow is improved. Neural networks provide a viable solution and show an increase in the accuracy of both flow rate and gas concentration. The main objective of the work in this thesis was to develop low-cost, low-power, small devices capable of high-volume production and monolithic integration using a single smart technology platform for fabrication. The smart technology platform was used to create pressure sensors, flow sensors and thermal conductivity gas sensors. Within each sensing technology, proof-of-concepts and optimisations have been carried out in order to maximise performance whilst using the low-cost, high-volume fabrication process, ultimately helping towards smart and autonomous engineering solutions driven by data

A review of technology of personal heating garments.

Modern technology makes garments smart, which can help a wearer to manage in specific situations by improving the functionality of the garments. The personal heating garment (PHG) widens the operating temperature range of the garment and improves its protection against the cold. This paper describes several kinds of PHGs worldwide; their advantages and disadvantages are also addressed. Some challenges and suggestions are finally addressed with regard to the development of PHGs

Cumulative index to NASA Tech Briefs, 1963-1965

Annotated bibliography of NASA technical briefs on electrical, energy sources, materials, life sciences, and mechanical informatio

Identification and control of diffusive systems applied to charge trapping and thermal space sensors

The work underlying this Thesis, has contributed to the main study and characterization of diffusive systems. The research work has been focused on the analysis of two kind of systems. On the one hand, the dynamics of thermal anemometers has been deeply studied. These sensors detect the wind velocity by measuring the power dissipated of a heated element due to forced convection. The thermal dynamics of different sensor structures have been analyzed and modeled during the Thesis work. On the other hand, we have dealed with microelectromechanical systems (MEMS). The dynamics of charge trapped in the dielectric layer of these systems has also been studied. It is know, that this undesired effect has been associated to diffusion phenomena. In this Thesis a characterization method based on the technique of Diffusive Representation (DR), for linear and nonlinear time-varying diffusive systems, is presented. This technique allows to describe a system with an arbitrary order state-space model in the frequency domain. The changes in the dynamics of a system over time may come as a result of the own actuation over the device or as a result of an external disturbance. In the wind sensor case, the time variation of the model comes from the wind, which is an external disturbance, whereas in the MEMS case, changes in the actuation voltage generate time-variation in the model. The state-space models obtained from DR characterization have proven to be able to reproduce and predict the behaviour of the devices under arbitrary excitations. Specifically, in the case of wind sensors, the thermal dynamics of these sensors, under constant temperature operation, has been predicted for different wind velocities using Sliding Mode Controllers. As it has been observed, these controllers also help to understand how the time response of a system, under closed loop, can be accelerated beyond the natural limit imposed by its own thermal circuit if the thermal filter associated to the sensor structure has only one significative time constant. The experimental corroboration of the thermal analysis is presented with various prototypes of wind sensors for Mars atmosphere. On one side, the time-varying thermal dynamics models of two different prototypes of a spherical 3-dimensional wind sensor, developed by the Micro and Nano Technologies group of the UPC, have been obtained. On the other side, the engineering model prototype of the wind sensor of the REMS (Rover Environmental Monitoring Station) instrument that it is currently on board the Curiosity rover in Mars has been characterized. For the characterization of the dynamics of the parasitic charge trapped in the dielectric layer of a MEMS device, the experimental validation is obtained through quasi-differential capacitance measurements of a two-parallel plate structure contactless capacitive MEMS.El trabajo que subyace a esta Tesis, ha contribuido principalmente al estudio y la caracterización de los sistemas difusivos. El trabajo de investigación se ha centrado en el análisis de dos tipos de sistemas. Por un lado, la dinámica de los anemómetros térmicos ha sido estudiada en profundidad. Estos sensores detectan la velocidad del viento a través de la medida de la potencia disipada en un elemento caliente debido a la convección forzada. Durante el trabajo de esta Tesis, se ha analizado y modelado la dinámica térmica de diferentes sensores . Por otro lado, se han tratado también los sistemas microelectromecánicos (MEMS). Se ha estudiado la dinámica de la carga atrapada en la capa dieléctrica de estos sistemas. Este fenómeno lento e indeseado está asociado a fenómenos de difusión. En esta Tesis se presenta un método de caracterización basado en la técnica de Representación Difusa (DR), para sistemas difusivos lineales y no lineales que varían en el tiempo. Esta técnica permite describir un sistema con un modelo de variables de estado de orden arbitrario en el dominio frecuencial. Los cambios en la dinámica de un sistema a lo largo del tiempo pueden ser debidos a la propia actuación sobre el dispositivo o como resultado de una perturbación externa. En el caso del sensor de viento, la variación de tiempo del modelo proviene de la propia variación del viento, la cual es una perturbación externa, mientras que en el caso de los dispositivos MEMS, los cambios en la tensión de actuación generan variaciones en el tiempo en el modelo. Los modelos de variables de estado obtenidos a partir de la caracterización con Representación Difusiva tienen la capacidad de reproducir y predecir el comportamiento de dichos dispositivos ante excitaciones arbitrarias. En concreto, en el caso de los sensores de viento, la dinámica térmica de estos sensores, operando a temperatura constante, se ha predicho para diferentes velocidades de viento, usando la teoría de los Sliding Mode Controllers (Controladores de Modo Deslizante). Tal y como se ha observado, estos controladores ayudan también a comprender cómo la respuesta temporal de un sistema, en lazo cerrado, puede acelerarse más allá del límite natural impuesto por su propio circuito térmico si el filtro térmico asociado a la estructura del sensor tiene solo una constante de tiempo significativa. La corroboración experimental del análisis térmico se presenta con varios prototipos de sensores de viento para la atmósfera de Marte. Por un lado, se han obtenido los modelos de la dinámica térmica variable en el tiempo de dos prototipos diferentes de un sensor de viento 3D esférico, desarrollado por el grupo de Micro y Nano Tecnologías de la UPC. Por otro lado, se ha caracterizado el prototipo de modelo de ingeniería del sensor de viento del instrumento REMS (Rover Environmental Monitoring Station) que está actualmente abordo del rover Curiosity en Marte. Para la caracterización de la dinámica de la carga atrapada en la capa dieléctrica de un dispositivo MEMS, la validación experimental se ha obtenido a través de medidas cuasi-diferenciales de la capacidad de un dispositivo MEMS con estructura de dos placas paralelas.Postprint (published version

Identification and control of diffusive systems applied to charge trapping and thermal space sensors

The work underlying this Thesis, has contributed to the main study and characterization of diffusive systems. The research work has been focused on the analysis of two kind of systems. On the one hand, the dynamics of thermal anemometers has been deeply studied. These sensors detect the wind velocity by measuring the power dissipated of a heated element due to forced convection. The thermal dynamics of different sensor structures have been analyzed and modeled during the Thesis work. On the other hand, we have dealed with microelectromechanical systems (MEMS). The dynamics of charge trapped in the dielectric layer of these systems has also been studied. It is know, that this undesired effect has been associated to diffusion phenomena. In this Thesis a characterization method based on the technique of Diffusive Representation (DR), for linear and nonlinear time-varying diffusive systems, is presented. This technique allows to describe a system with an arbitrary order state-space model in the frequency domain. The changes in the dynamics of a system over time may come as a result of the own actuation over the device or as a result of an external disturbance. In the wind sensor case, the time variation of the model comes from the wind, which is an external disturbance, whereas in the MEMS case, changes in the actuation voltage generate time-variation in the model. The state-space models obtained from DR characterization have proven to be able to reproduce and predict the behaviour of the devices under arbitrary excitations. Specifically, in the case of wind sensors, the thermal dynamics of these sensors, under constant temperature operation, has been predicted for different wind velocities using Sliding Mode Controllers. As it has been observed, these controllers also help to understand how the time response of a system, under closed loop, can be accelerated beyond the natural limit imposed by its own thermal circuit if the thermal filter associated to the sensor structure has only one significative time constant. The experimental corroboration of the thermal analysis is presented with various prototypes of wind sensors for Mars atmosphere. On one side, the time-varying thermal dynamics models of two different prototypes of a spherical 3-dimensional wind sensor, developed by the Micro and Nano Technologies group of the UPC, have been obtained. On the other side, the engineering model prototype of the wind sensor of the REMS (Rover Environmental Monitoring Station) instrument that it is currently on board the Curiosity rover in Mars has been characterized. For the characterization of the dynamics of the parasitic charge trapped in the dielectric layer of a MEMS device, the experimental validation is obtained through quasi-differential capacitance measurements of a two-parallel plate structure contactless capacitive MEMS.El trabajo que subyace a esta Tesis, ha contribuido principalmente al estudio y la caracterización de los sistemas difusivos. El trabajo de investigación se ha centrado en el análisis de dos tipos de sistemas. Por un lado, la dinámica de los anemómetros térmicos ha sido estudiada en profundidad. Estos sensores detectan la velocidad del viento a través de la medida de la potencia disipada en un elemento caliente debido a la convección forzada. Durante el trabajo de esta Tesis, se ha analizado y modelado la dinámica térmica de diferentes sensores . Por otro lado, se han tratado también los sistemas microelectromecánicos (MEMS). Se ha estudiado la dinámica de la carga atrapada en la capa dieléctrica de estos sistemas. Este fenómeno lento e indeseado está asociado a fenómenos de difusión. En esta Tesis se presenta un método de caracterización basado en la técnica de Representación Difusa (DR), para sistemas difusivos lineales y no lineales que varían en el tiempo. Esta técnica permite describir un sistema con un modelo de variables de estado de orden arbitrario en el dominio frecuencial. Los cambios en la dinámica de un sistema a lo largo del tiempo pueden ser debidos a la propia actuación sobre el dispositivo o como resultado de una perturbación externa. En el caso del sensor de viento, la variación de tiempo del modelo proviene de la propia variación del viento, la cual es una perturbación externa, mientras que en el caso de los dispositivos MEMS, los cambios en la tensión de actuación generan variaciones en el tiempo en el modelo. Los modelos de variables de estado obtenidos a partir de la caracterización con Representación Difusiva tienen la capacidad de reproducir y predecir el comportamiento de dichos dispositivos ante excitaciones arbitrarias. En concreto, en el caso de los sensores de viento, la dinámica térmica de estos sensores, operando a temperatura constante, se ha predicho para diferentes velocidades de viento, usando la teoría de los Sliding Mode Controllers (Controladores de Modo Deslizante). Tal y como se ha observado, estos controladores ayudan también a comprender cómo la respuesta temporal de un sistema, en lazo cerrado, puede acelerarse más allá del límite natural impuesto por su propio circuito térmico si el filtro térmico asociado a la estructura del sensor tiene solo una constante de tiempo significativa. La corroboración experimental del análisis térmico se presenta con varios prototipos de sensores de viento para la atmósfera de Marte. Por un lado, se han obtenido los modelos de la dinámica térmica variable en el tiempo de dos prototipos diferentes de un sensor de viento 3D esférico, desarrollado por el grupo de Micro y Nano Tecnologías de la UPC. Por otro lado, se ha caracterizado el prototipo de modelo de ingeniería del sensor de viento del instrumento REMS (Rover Environmental Monitoring Station) que está actualmente abordo del rover Curiosity en Marte. Para la caracterización de la dinámica de la carga atrapada en la capa dieléctrica de un dispositivo MEMS, la validación experimental se ha obtenido a través de medidas cuasi-diferenciales de la capacidad de un dispositivo MEMS con estructura de dos placas paralelas

Energy Harvesting Technologies for Achieving Self-Powered Wireless Sensor Networks in Machine Condition Monitoring:A Review

Condition monitoring can reduce machine breakdown losses, increase productivity and operation safety, and therefore deliver significant benefits to many industries. The emergence of wireless sensor networks (WSNs) with smart processing ability play an ever-growing role in online condition monitoring of machines. WSNs are cost-effective networking systems for machine condition monitoring. It avoids cable usage and eases system deployment in industry, which leads to significant savings. Powering the nodes is one of the major challenges for a true WSN system, especially when positioned at inaccessible or dangerous locations and in harsh environments. Promising energy harvesting technologies have attracted the attention of engineers because they convert microwatt or milliwatt level power from the environment to implement maintenance-free machine condition monitoring systems with WSNs. The motivation of this review is to investigate the energy sources, stimulate the application of energy harvesting based WSNs, and evaluate the improvement of energy harvesting systems for mechanical condition monitoring. This paper overviews the principles of a number of energy harvesting technologies applicable to industrial machines by investigating the power consumption of WSNs and the potential energy sources in mechanical systems. Many models or prototypes with different features are reviewed, especially in the mechanical field. Energy harvesting technologies are evaluated for further development according to the comparison of their advantages and disadvantages. Finally, a discussion of the challenges and potential future research of energy harvesting systems powering WSNs for machine condition monitoring is made