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Koob, Christopher E. "High temperature fiber optic strain sensing." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-02132009-171339/.
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Frazier, Janay Amber Wright. "High-Definition Raman-based Distributed Temperature Sensing." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/95934.
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Distributed Temperature Sensing (DTS) has been used in a variety of different applications. Its ability to detect temperature fluctuations along fiber optic lines that stretch for several kilometers has made it a popular topic in various fields of science, engineering, and technology. From pre-fire detection to ecological monitoring, DTS has taken a vital role in scientific research. DTS uses the principle of backscattering by three different spectral components, e.g., Rayleigh scattering, Brillouin scattering, and Raman scattering. Although there have been various improvements to DTS, its slow response time and poor spatial resolution have been hard to overcome. Its repetition rate is low because the pulse must travel the distance of the fiber optic line and return to the detector to record the temperature change along the fiber. A spatial resolution of 7.4 cm with a response time as low as 1 second and a temperature resolution of the 0.196 ℃ is achieved from the current Raman-based DTS system. This research proves that high-spatial resolution can be obtained with the use of a Silicon Avalanche Photodetector with a 1 GHz bandwidth.MS
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Liu, Bo. "Sapphire Fiber-based Distributed High-temperature Sensing System." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82741.
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From the monitoring of deep ocean conditions to the imaging and exploration of the vast universe, optical sensors are playing a unique, critical role in all areas of scientific research. Optical fiber sensors, in particular, are not only widely used in daily life such as for medical inspection, structural health monitoring, and environmental surveillance, but also in high-tech, high-security applications such as missile guidance or monitoring of aircraft engines and structures. Measurements of physical parameters are required in harsh environments including high pressure, high temperature, highly electromagnetically-active and corrosive conditions. A typical example is fossil fuel-based power plants. Unfortunately, current optical fiber sensors for high-temperature monitoring can work only for single point measurement, as traditional fully-distributed temperature sensing techniques are restricted for temperatures below 800°C due to the limitation of the fragile character of silica fiber under high temperature.
In this research, a first-of-its-kind technology was developed which pushed the limits of fully distributed temperature sensing (DTS) in harsh environments by exploring the feasibility of DTS in optical sapphire waveguides. An all sapphire fiber-based Raman DTS system was demonstrated in a 3-meters long sapphire fiber up to a temperature of 1400°C with a spatial resolution of 16.4cm and a standard deviation of a few degrees Celsius.
In this dissertation, the design, fabrication, and testing of the sapphire fiber-based Raman DTS system are discussed in detail. The plan and direction for future work are also suggested with an aim for commercialization.Ph. D.
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Szajda, Kenneth S. (Kenneth Stanley). "A high resolution integrated circuit biomedical temperature sensing system." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11846.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Vita.
Includes bibliographical references (p. 226-235).
by Kenneth S. Szajda.
Ph.D.
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Wang, Jiajun. "Sapphire Fiber Based Sensing Technologies for High Temperature Applications." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77149.
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Sapphire fiber has been studied intensively for harsh environment sensing in the past two decades due to its supreme mechanical, physical and optical properties. It is by far the most reported and likely the best optical fiber based sensing technology for sensing applications in temperature beyond 1000°C.
Several sensing schemes have been proposed and studied to date including sapphire fiber extrinsic and intrinsic Fabry-Perot interferometers, fiber Bragg gratings and long period gratings inscribed in sapphire fibers. Lacking the cladding, sapphire fiber is highly multi-moded which renders sapphire fiber based sensor fabrication much more difficult than those based on silica fibers. Among all the reported work on sapphire fiber sensing, the vast majority is for single point temperature measurement.
In this work, different sensing schemes are proposed to enhance the capability of the sapphire fiber based sensing technology. For the single point sensing, a miniaturized sapphire fiber temperature sensor for embedded sensing applications was proposed and studied. The sensors are no more than 75 µm in diameter and are ideal for non-invasive embedded sensing applications. Unlike existing sapphire fiber sensors, the thin film sensors are batch-fabrication oriented and thus have a potential to permit mass production with low cost. In addition to single point sensors, multiplexed sapphire fiber sensing systems are investigated for the first time. Two multiplexed sensing solutions, named frequency-multiplexing and spatial-multiplexing, are proposed and studied to achieve multiplexed sensing based on sapphire fibers.Ph. D.
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Wang, Jing. "Distributed Pressure and Temperature Sensing Based on Stimulated Brillouin Scattering." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/78066.
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Brillouin scattering has been verified to be an effective mechanism in temperature and strain sensing. This kind of sensors can be applied to civil structural monitoring of pipelines, railroads, and other industries for disaster prevention. This thesis first presents a novel fiber sensing scheme for long-span fully-distributed pressure measurement based on Brillouin scattering in a side-hole fiber. After that, it demonstrates that Brillouin frequency keeps linear relation with temperature up to 1000°C; Brillouin scattering is a promising mechanism in high temperature distributed sensing.
A side-hole fiber has two longitudinal air holes in the fiber cladding. When a pressure is applied on the fiber, the two principal axes of the fiber birefringence yield different Brillouin frequency shifts in the Brillouin scattering. The differential Brillouin scattering continuously along the fiber thus permits distributed pressure measurement. Our sensor system was designed to analyze the Brillouin scattering in the two principal axes of a side-hole fiber in time domain. The developed system was tested under pressure from 0 to 10,000 psi for 100m and 600m side-hole fibers, respectively. Experimental results show fibers with side holes of different sizes possess different pressure sensitivities. The highest sensitivity of the measured pressure induced differential Brillouin frequency shift is 0.0012MHz/psi. The demonstrated spatial resolution is 2m, which maybe further improved by using shorter light pulses.Master of Science
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OLIVEIRA, LUIZ HENRIQUE PARAGUASSÚ DE. "METROLOGICAL ANALYSIS OF HIGH TEMPERATURE FIBER BRAGG GRATINGS FOR SENSING APPLICATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18805@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA presente tese tem por objetivo estabelecer uma metodologia de caracterização metrológica de redes de Bragg do tipo I, tipo II e tipo regenerada estimando e validando estatisticamente o resultado de medição para medições de altas temperaturas voltadas para aplicações em sensoriamento. Além das telecomunicações, as fibras óticas estão sendo empregadas em aplicações de sensoriamento, visto que, a sílica que as compõem apresenta grande eficiência como meio de transmissão de dados. A crescente demanda por medição em alta temperatura nos processos industriais possibilitou o desenvolvimento de novas tecnologias de medição além das tecnologias tradicionais já utilizadas atualmente. Desta forma, criaram-se as condições necessárias para se introduzir uma nova tecnologia de medição de temperatura com redes de Bragg que apresenta algumas vantagens se comparadas com as tecnologias tradicionais de medição. Apesar de já existirem várias pesquisas a respeito de medição de temperatura com redes de Bragg, nenhuma delas aprofundou as questões metrológicas com as respectivas estimativas das incertezas de medição que envolve todo o processo de medição e caracterização de redes de Bragg em alta temperatura. A adaptação de um sistema tradicional de calibração de instrumentos de medição de temperatura foi projetado e desenvolvido, de tal forma que possibilitou a caracterização dos diferentes tipos de redes. Observou-se que os resultados de medição e as estimativas das incertezas de medição obtidos para todas as redes, se aproximaram satisfatoriamente dos modelos teóricos utilizados, confirmando a adequação dos sistemas de medição de temperatura e sensoriamento ótico.
This thesis aims to establish a methodology for the metrological characterization of Bragg gratings type I, type II and type regenerated statistically thereby estimating and validating the measurement results for high temperature sensing applications. Beyond telecommunications applications, optical fibers are still used for optical sensing, since the silica fiber has great optical efficiency for data transmission. The growing demand for high-temperature measurements in industrial processes has enabled the development of new measurement technologies beyond the traditional technologies already in use today. Thus were created the conditions necessary to introduce a new technology of temperature measurement with Bragg gratings which presents some advantages compared with traditional technologies of measurement. Although there are several prior studies none of those examined the by others about temperature measurement with Bragg gratings, metrological issues, and is particular, the estimate of the measurement uncertainties surrounding the whole process of measurement and characterization of Bragg gratings at high temperature. The adaptation of a traditional system of calibration instruments for temperature measurement was developed and designed in such a way that allowed the characterization of different types of gratings. It was observed that the measurement results and the estimated uncertainties of the measurements obtained for all gratings, successfully approached the theoretical models used, confirming the adequacy of the measurement of temperature and optical sensing.
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White, Julia. "OPTIC FIBER SENSOR FOR STRAIN MEASUREMENTS IN HIGH TEMPERATURE SENSING APPLICATIONS." International Foundation for Telemetering, 2017. http://hdl.handle.net/10150/626969.
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Optic fiber sensors are employed in a variety of applications for the remote measurement of various parameters such as strain, pressure, or temperature. These sensors offer an array of benefits as well including light weight, compactness, and high resolution. In particular, Fabry-Perot interferometers (FPIs) maintain these benefits and can also be made to withstand extremely high temperatures. This advantage of the FPI allows it to be used in harsh environments where many other tools for parameter measurement could not survive. An FPI strain sensor is constructed and tested which has the capabilities to be used at high temperatures of over 1000°C for applications in gas turbine engine testing. This paper discusses the need for high temperature strain sensors in engine testing and this sensor’s capabilities in this application.
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Yu, Guo. "Sapphire Based Fiber-Optic Sensing for Extreme High Temperatures." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76982.
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Temperature sensing is one of the most common and needed sensing technique, especially in harsh environment like a coal gasifier or an airplane engine. Single crystal sapphire has been studied in the last two decades as a candidate for harsh environment sensing task, due to its excellent mechanical and optical properties under extreme high temperature (over 1000°C).
In this research, a sapphire wafer based Fabry-Perot (FP) interferometer sensor has been proposed, whose functional temperature measurement can go beyond 1600°C. The size of the sensors can be limited to a 2cm-length tube, with 2mm outer diameter, which is suitable for a wide range of harsh environment applications. The sensors have shown linear sensing response during 20~1200°C temperature calibration, with high sensitivity and resolution, and strong robustness, which are ready for the field test in real-world harsh environment.Master of Science
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Rabhiou, Abderahman. "Phosphorescent thermal history sensing for advanced condition monitoring in high temperature environment." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/39125.
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Knowledge of the temperatures surfaces are exposed to is crucial in many processes, particularly above 300°C. It is often not possible to measure temperature of all surfaces of interest in real-time. Off-line temperature measurement techniques can be used to record exposure temperatures in such a way that these can be retrieved later off-line, at room temperature. Thermal paint changes colour or surface properties permanently, depending on the maximum temperature they have been exposed to. Thermal paints have been a valuable tool of engine developers for many years, but the use of the existing paints presents a number of challenges if reliable results are to be obtained. Feist et al. [1] proposed a thermal history sensor based on phosphors that undergo permanent changes in their luminescence properties when exposed to high temperatures. These luminescence properties can be interrogated with a light source and measured with standard spectroscopic instrumentation. Phosphorescent thermal history sensors might be applied as paint, coating or as point-sensors. The proposed concept has several advantages over the existing sensors. As the main embodiment is a paint or coating, the proposed sensor would be a direct competing technology to thermal paints. The present study reports on the three main concepts responsible for the permanent changes in some phosphors that have been identified. The mechanisms behind these concepts are outlined and examples are given of phosphors which could be used as sensors. The amorphous-to-crystalline and the thermal damaging concepts were demonstrated in laboratory tests in this work. An extensive characterisation of the luminescence properties dependency on thermal history was conducted on several phosphors: BAM : Eu, BAM : Eu;Mn, Y2O2S : Eu, SrAl2O4 : Eu, Y2SiO5 : Tb, Y AG : Dy and Y SZ=Y AG : Dy. Calibration curves of powder, paint and/or coating embodiments of these phosphors are presented. The amorphous-to-crystalline concept revealed to be the most promising for the application as thermal history sensor, covering a temperature range from 300°C to 1300°C. The amorphous-to-crystalline phosphor Y2SiO5 : Tb was synthesised by sol-gel technique and applied as a paint on a stainless steel disk, which was subsequently exposed to a jet impinging flame. A luminescence readout of the paint after the exposure to the flame revealed a map of temperatures between 300°C and 800°C. The paint was able to highlight the asymmetrical set-up of the impinging flame. The phosphor Y SZ=Y AG : Dy was APS-coated on a rotating turbine blade and inner flame tube of a Rolls-Royce Viper 201 jet engine, which was operated for several hours. Temperature profile maps were obtained after interrogation of the luminescence changes of the coating. These revealed that the probed surface of inner flame tube was exposed to temperatures generally not exceeding than 500°C, apart from local hotspots of 700°C located above the dilution holes. The interrogation of the turbine blade indicated the areas cooled by air streams and maximum temperatures in excess of 800°C.
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Benn, Gregory (Gregory Scott) 1977. "Design of a silicon carbide micro-hotplate geometry for high temperature chemical sensing." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/17535.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.Includes bibliographical references (p. 127-129).
Silicon carbide, high temperature, chemical sensors are the next step in chemical detection technology; allowing for the development of low cost, robust, lower power, and widely applicable chemical sensors. SiC offers the thermal conductivity, electrical properties, and operating temperatures not currently available in silicon sensors. Boston Micro Systems, a Wobum, Massachusetts based company, has developed technologies for bulk manufacturing of single crystal SiC material. Using this technology, geometries optimizing thermal and electrical performance have been developed to create a SiC micro-hotplate for chemical sensors. Under etching allows for the manufacturing of micro-hotplates. Micro hotplates allow sensors to discriminate between chemical species by controlling absorption and desorption of chemicals. Optimization of the performance of such a device is achieved by developing hotplates that are suspended by necked tethers. Tether designs minimize heat lose from the hotplate and necking creates heat generation regions. The excellent thermal properties of SiC allow heat to be transferred from the necked tethers to the hotplate; producing a hotplate with a uniform temperature distribution, important to the sensitivity and accuracy of the sensing film. Testing of tethered and necked hotplates identified several areas of improvement in hotplate design. These include under etching, improvement in the plates response to thermal stresses, and p-n junction performance improvements. Using such design improvements as tethers and necking the thermal performance of SiC micro-hotplates has improved by two orders of magnitude. This thesis discusses the design, modeling, and testing of single crystal SiC micro-hotplates.
Gregory Benn.
S.M.
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Connolly, William John Cleveland. "An investigation into the use of β-aluminas for high temperature sulphur sensing." Thesis, University of Cambridge, 2000. https://www.repository.cam.ac.uk/handle/1810/251711.
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Over three quarters of the world's flat glass is produced by the float method, in which molten glass is solidified on large baths of liquid tin. Sulphur is a major contaminant in these baths, causing a defect known as top speck. This dissertation describes the design, construction and evaluation of a sensor based upon a solid electrolyte, intended for use in the detection of this sulphur. Three solid electrolytes were produced: strontium and sodium β-alumina by direct methods, and silver β-alumina by ion exchange. The effects of material composition and sintering cycle on density were investigated, and conductivities, atomic structures and microstructures were characterised and shown to agree with published data. A number of cell designs were constructed to investigate the electrolytes' responses to different partial pressures of sulphur and oxygen, which were produced using mixtures of the metals copper, iron and molybdenum with their respective sulphides and oxides. A non-equilibrium electrolyte response was observed, caused by slow interaction between the electrolyte and the metals. A mixture of molten tin and solid tin sulphide was investigated using a silver-referenced, silver β-alumina cell, and reproducible emfs corresponding to thermodynamic expectations were observed. A non-unity value was determined for the activity of a proposed silver sulphide auxiliary layer at the surface of the β-alumina and shown to be in agreement with a theoretically-calculated value. Experiments were carried out using this cell in molten tin baths of varying sulphur content. Results were generally consistent with the previously-determined values of silver sulphide activity; however, at low sulphur values this activity was not constant and decreased to zero. The minimum level of sulphur which could be detected by this technique was calculated and tested both in laboratory molten tin and in industrial trials.
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Raheem-Kizchery, Ayesha Rubiath. "Ceramic coatings for silica and sapphire optical waveguides for high temperature embedding and sensing." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09052009-040217/.
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Pal, Suchandan. "Characterisation and high-temperature sensing potential of fibre Bragg gratings in specialised optical fibres." Thesis, City University London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407547.
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Wooster, Martin John. "Spaceborne monitoring of high temperature volcanic thermal features : studies using the ERS Along Track Scanning Radiometer." Thesis, Open University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264468.
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Kubina, Bernd [Verfasser], Rolf [Akademischer Betreuer] Jakoby, and Martin [Akademischer Betreuer] Vossiek. "Chipless Wireless High-Temperature Sensing in Time-Variant Environments / Bernd Kubina ; Rolf Jakoby, Martin Vossiek." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1140166239/34.
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Song, Junghui. "Fabrication and Characterization of AlGaN/GaN Heterostructure Devices for Hydrogen Gas Sensing at High Temperature." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250296506.
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Prasad, Ravi Mohan. "Polymer-Derived Microporous Ceramics for Membranes and Sensors for High Temperature Hydrogen Purification and Sensing." Phd thesis, tuprints, 2012. http://tuprints.ulb.tu-darmstadt.de/3181/1/PhD_Dissertation_Ravi_Mohan_Prasad_%28TU_Darmstadt%29.pdf.
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The growing interest in the use of hydrogen as main fuel has increased the need for pure hydrogen (H2) production and purification. There are several by-products (CO, H2O, CO2) associated with the production of hydrogen which might damage the production rate. Therefore, separation of hydrogen from other gases is an important step in the hydrogen production process. If H2 can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single-step under high temperature conditions.
The main goal of the present work is the high temperature H2 purification and sensing by applying polymer-derived ceramics. To prove the concept, the microporous SiBCN, Si3N4 and SiCN ceramic membranes have been synthesized by the polymer-pyrolysis route and their performance for the hydrogen separation have been evaluated in tubular membranes as well as in planar chemiresistors.
The synthesis of amorphous SiBCN ceramics has been realized through pyrolysis of poly(organoborosilazanes) in argon. Multilayered amorphous SiBCN/γ-Al2O3/α-Al2O3 membranes with gradient porosity have been realized and assessed with respect to the thermal stability, pore-size distribution and H2/CO permeance. N2-adsorption measurement indicates micropores in the range of 0.68-0.73 nm for three-fold SiBCN/γ-Al2O3/α-Al2O3 membrane. SEM characterization of three-fold SiBCN/γ-Al2O3/α-Al2O3 membrane shows the thickness of SiBCN membrane layer is 2.8 μm; gas permeance measurements of the membrane shows H2/CO selectivity of about 10.5 and the H2 permeance of about 1.05x10-8 mol m-2 s-1 Pa-1. The observed gas permeation properties point out that the transportation of gas molecules through the membrane is governed by both activated and Knudsen diffusion.
The stability and sensing characteristics of SnO2 sensors coated with amorphous microporous SiBCN layers have been studied in oxygen-free atmospheres. The SiBCN layers coated on SnO2 sensors are amorphous, crack-free and microporous. The diameter of micropores (about 0.70 nm) is larger than the kinetic diameter of H2 (0.289 nm) and CO (0.376 nm) molecules, allowing in this way their diffusion towards the bottom SnO2 sensing layer. Transient response characteristics and sensor signals of uncoated SnO2, three-fold and five-fold SiBCN-coated SnO2 sensors exposed to CO (10, 20 and 120 ppm) and H2 (40, 400 and 900 ppm) in nitrogen at 350 and 530 °C are obtained. Uncoated SnO2 sensor is reduced at 530 °C in H2 to tin while SiBCN-coated SnO2 sensors show reversible resistance changes while exposed to CO and H2.
Si3N4-ceramics have been synthesized via a dry ammonia pyrolysis of commercially available polysilazane (KiON HTT 1800). Amorphous microporous-Si3N4 ceramic layers deposited on the top of GaN sensing layer followed by dry ammonia treatment leads to the improved H2 to CO selectivity of Si3N4/GaN sensors in the oxygen-free atmosphere. Transient response of the uncoated-, three-fold Si3N4 coated- and ammonia treated-GaN sensors exposed to CO (10, 20 and 120 ppm) and H2 (40, 400 and 900 ppm) in pure nitrogen at 350 and 530 °C are investigated. The results indicate that uncoated-GaN sensor shows high response towards both CO and H2 whereas for microporous Si3N4 coated- and ammonia treated-GaN gas sensors the sensitivity towards the interfering gas CO is significantly reduced.
High-surface area micro- and mesoporous carbon-rich SiCN ceramics have been obtained by controlled thermolysis of a carbon-rich poly(diphenylsilylcarbodiimide) precursor under argon. The formation of porous SiCN ceramics is due to the carbothermal reaction of amorphous silicon nitride phase with excess carbon, which leads to materials with high specific surface area of about 500-600 m2 g−1. High-resolution Transmisson Electron Microscopy indicates that pores are embedded only in the free carbon phase. The transformation from micro- to mesoporous ceramics after heat treatment between 1600 and 1700 °C, due to the organization of graphene-like free carbon phase, is discussed.
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Aslan, Hatice. "Using remote sensing in soybean breeding: estimating soybean grain yield and soybean cyst nematode populations." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/18830.
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Master of ScienceDepartment of Agronomy
William T. Schapaugh
Remote sensing technologies might serve as indirect selection tools to improve phenotyping to differentiate genotypes for yield in soybean breeding program as well as the assessment of soybean cyst nematode (SCN), Heterodera glycines. The objective of these studies were to: i) investigate potential use of spectral reflectance indices (SRIs) and canopy temperature (CT) as screening tools for soybean grain yield in an elite, segregating population; ii) determine the most appropriate growth stage(s) to measure SRI’s for predicting grain yield; and iii) estimate SCN population density among and within soybean cultivars utilizing canopy spectral reflectance and canopy temperature. Experiment 1 was conducted at four environments (three irrigated and one rain-fed) in Manhattan, KS in 2012 and 2013. Each environment evaluated 48 F4- derived lines. In experiment 2, two SCN resistant cultivars and two susceptible cultivars were grown in three SCN infested field in Northeast KS, in 2012 and 2013. Initial (Pi) and final SCN soil population (Pf) densities were obtained. Analyses of covariance (ANCOVA) revealed that the green normalized vegetation index (GNDVI) was the best predictive index for yield compared to other SRI’s and differentiated genotype performance across a range of reproductive growth stages. CT did not differentiate genotypes across environments. In experiment 2, relationships between GNDVI, reflectance at single wavelengths (675 and 810 nm) and CT with Pf were not consistent across cultivars or environments. Sudden death syndrome (SDS) may have confounded the relationships between remote sensing data and Pf. Therefore, it would be difficult to assess SCN populations using remote sensing based on these results.
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Mullen, Max Robertson. "Electrochemical Sensing for a Rapidly Evolving World." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440408652.
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Lowder, Tyson Lee. "Surface Relief D-Fiber Bragg Gratings for Sensing Applications." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2644.pdf.
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Ziegler, Silvio. "New current sensing solutions for low-cost high-power-density digitally controlled power converters." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0077.
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[Truncated abstract] This thesis studies current sensing techniques that are designed to meet the requirements for the next generation of power converters. Power converters are often standardised, so that they can be replaced with a model from another manufacturer without an expensive system redesign. For this reason, the power converter market is highly competitive and relies on cutting-edge technology, which increases power conversion efficiency and power density. High power density and conversion efficiency reduce the system cost, and thus make the power converter more attractive to the customer. Current sensing is a vital task in power converters, where the current information is required for monitoring and control purposes. In order to achieve the above-mentioned goals, existing current sensing techniques have to be improved in terms of cost, power loss and size. Simultaneously, current information needs to be increasingly available in digital form to enable digital control, and to allow the digital transmission of the current information to a centralised monitoring and control unit. All this requires the output signal of a particular current sensing technique to be acquired by an analogue-to-digital converter, and thus the output voltage of the current sensor has to be sufficiently large. This thesis thoroughly reviews contemporary current sensing techniques and identifies suitable techniques that have the potential to meet the performance requirements of the next-generation of power converters. After the review chapter, three novel current sensing techniques are proposed and investigated: 1) The usefulness of the resistive voltage drop across a copper trace, which carries the current to be measured, to detect electrical current is evaluated. Simulations and experiments confirm that this inherently lossless technique can measure high currents at reasonable measurement bandwidth, good accuracy and low cost if the sense wires are connected properly. 2) Based on the mutual inductance theory found during the investigation of the copper trace current sense method, a modification of the well-known lossless inductor current sense method is proposed and analysed. This modification involves the use of a coupled sense winding that significantly improves the frequency response. Hence, it becomes possible to accurately monitor the output current of a power converter with the benefits of being lossless, exhibiting good sensitivity and having small size. 3) A transformer based DC current sense method is developed especially for digitally controlled power converters. This method provides high accuracy, large bandwidth, electrical isolation and very low thermal drift. Overall, it achieves better performance than many contemporary available Hall Effect sensors. At the same time, the cost of this current sensor is significantly lower than that of Hall Effect current sensors. A patent application has been submitted. .... The current sensing techniques have been studied by theory, hardware experiments and simulations. In addition, the suitability of the detection techniques for mass production has been considered in order to access the ability to provide systems at low-cost.
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Prasad, Ravi Mohan [Verfasser], Ralf [Akademischer Betreuer] Riedel, Christina [Akademischer Betreuer] Roth, Wolfgang [Akademischer Betreuer] Ensinger, and Jörg [Akademischer Betreuer] Schneider. "Polymer-Derived Microporous Ceramics for Membranes and Sensors for High Temperature Hydrogen Purification and Sensing / Ravi Mohan Prasad. Betreuer: Ralf Riedel ; Christina Roth ; Wolfgang Ensinger ; Jörg Schneider." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2012. http://d-nb.info/110625709X/34.
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Ferré, Marcel. "Developpement de methodes numeriques et experimentales pour la restitution des profils de temperature dans les verres par teledetection infrarouge." Poitiers, 1988. http://www.theses.fr/1988POIT2289.
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Les profils de temperature sont etablis dans un verre semi-transparent par teledetection et inversion des donnees d'emission du rayonnement thermique spectral infra-rouge. Deux procedes mathematiques ont ete utilises: la methode non lineaire de chabine et la methode lineaire de regularisation de tikhonov. L'identification du profil de temperature dans un verre flotte et dans l'anhydride borique a ete realise par sondage a distance a partir d'un niveau de temperature de l'ordre de 1000 k
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Amazirh, Abdelhakim. "Monitoring crops water needs at high spatio-temporal resolution by synergy of optical/thermal and radar observations." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30101.
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L'optimisation de la gestion de l'eau en agriculture est essentielle dans les zones semi-arides afin de préserver les ressources en eau qui sont déjà faibles et erratiques dues à des actions humaines et au changement climatique. Cette thèse vise à utiliser la synergie des observations de télédétection multispectrales (données radar, optiques et thermiques) pour un suivi à haute résolution spatio-temporelle des besoins en eau des cultures. Dans ce contexte, différentes approches utilisant divers capteurs (Landsat-7/8, Sentinel-1 et MODIS) ont été developpées pour apporter une information sur l'humidité du sol (SM) et le stress hydrique des cultures à une échelle spatio-temporelle pertinente pour la gestion de l'irrigation. Ce travail va parfaitement dans le sens des objectifs du projet REC "Root zone soil moisture Estimates at the daily and agricultural parcel scales for Crop irrigation management and water use impact: a multi-sensor remote sensing approach" (http://rec.isardsat.com/) qui visent à estimer l'humidité du sol dans la zone racinaire (RZSM) afin d'optimiser la gestion de l'eau d'irrigation. Des approches innovantes et prometteuses sont mises en place pour estimer l'évapotranspiration (ET), RZSM, la température de surface du sol (LST) et le stress hydrique de la végétation à travers des indices de SM dérivés des observations multispectrales à haute résolution spatio-temporelle. Les méthodologies proposées reposent sur des méthodes basées sur l'imagerie, la modélisation du transfert radiatif et la modélisation du bilan hydrique et d'énergie et sont appliquées dans une région à climat semi-aride (centre du Maroc). Dans le cadre de ma thèse, trois axes ont été explorés. Dans le premier axe, un indice de RZSM dérivé de LST-Landsat est utilisé pour estimer l'ET sur des parcelles de blé et des sols nus. L'estimation par modélisation de ET a été explorée en utilisant l'équation de Penman-monteith modifiée obtenue en introduisant une relation empirique simple entre la résistance de surface (rc) et l'indice de RZSM. Ce dernier est estimé à partir de la température de surface (LST) dérivée de Landsat, combinée avec les températures extrêmes (en conditions humides et sèches) simulée par un modèle de bilan d'énergie de surface piloté par le forçage météorologique et la fraction de couverture végétale dérivée de Landsat. La méthode utilisée est calibrée et validée sur deux parcelles de blé situées dans la même zone près de Marrakech au Maroc. Dans l'axe suivant, une méthode permettant de récupérer la SM de la surface (0-5 cm) à une résolution spatiale et temporelle élevée est développée à partir d'une synergie entre données radar (Sentinel-1) et thermique (Landsat) et en utilisant un modèle de bilan d'énergie du sol. L'approche développée a été validée sur des parcelles agricoles en sol nu et elle donne une estimation précise de la SM avec une différence quadratique moyenne en comparant à la SM in situ, égale à 0,03 m3 m-3. Dans le dernier axe, une nouvelle méthode est développée pour désagréger la MODIS LST de 1 km à 100 m de résolution en intégrant le SM proche de la surface dérivée des données radar Sentinel-1 et l'indice de végétation optique dérivé des observations Landsat. Le nouvel algorithme, qui inclut la rétrodiffusion S-1 en tant qu'entrée dans la désagrégation, produit des résultats plus stables et robustes au cours de l'année sélectionnée. Dont, 3,35 °C était le RMSE le plus bas et 0,75 le coefficient de corrélation le plus élevé évalués en utilisant le nouvel algorithmeOptimizing water management in agriculture is essential over semi-arid areas in order to preserve water resources which are already low and erratic due to human actions and climate change. This thesis aims to use the synergy of multispectral remote sensing observations (radar, optical and thermal data) for high spatio-temporal resolution monitoring of crops water needs. In this context, different approaches using various sensors (Landsat-7/8, Sentinel-1 and MODIS) have been developed to provide information on the crop Soil Moisture (SM) and water stress at a spatio-temporal scale relevant to irrigation management. This work fits well the REC "Root zone soil moisture Estimates at the daily and agricultural parcel scales for Crop irrigation management and water use impact: a multi-sensor remote sensing approach" (http://rec.isardsat.com/) project objectives, which aim to estimate the Root Zone Soil Moisture (RZSM) for optimizing the management of irrigation water. Innovative and promising approaches are set up to estimate evapotranspiration (ET), RZSM, land surface temperature (LST) and vegetation water stress through SM indices derived from multispectral observations with high spatio-temporal resolution. The proposed methodologies rely on image-based methods, radiative transfer modelling and water and energy balance modelling and are applied in a semi-arid climate region (central Morocco). In the frame of my PhD thesis, three axes have been investigated. In the first axis, a Landsat LST-derived RZSM index is used to estimate the ET over wheat parcels and bare soil. The ET modelling estimation is explored using a modified Penman-Monteith equation obtained by introducing a simple empirical relationship between surface resistance (rc) and a RZSM index. The later is estimated from Landsat-derived land surface temperature (LST) combined with the LST endmembers (in wet and dry conditions) simulated by a surface energy balance model driven by meteorological forcing and Landsat-derived fractional vegetation cover. The investigated method is calibrated and validated over two wheat parcels located in the same area near Marrakech City in Morocco. In the next axis, a method to retrieve near surface (0-5 cm) SM at high spatial and temporal resolution is developed from a synergy between radar (Sentinel-1) and thermal (Landsat) data and by using a soil energy balance model. The developed approach is validated over bare soil agricultural fields and gives an accurate estimates of near surface SM with a root mean square difference compared to in situ SM equal to 0.03 m3 m-3. In the final axis a new method is developed to disaggregate the 1 km resolution MODIS LST at 100 m resolution by integrating the near surface SM derived from Sentinel-1 radar data and the optical-vegetation index derived from Landsat observations. The new algorithm including the S-1 backscatter as input to the disaggregation, produces more stable and robust results during the selected year. Where, 3.35 °C and 0.75 were the lowest RMSE and the highest correlation coefficient assessed using the new algorithm
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Kilic, Lise. "Estimation des paramètres de surface des océans et de la banquise à partir d’observations micro-ondes basses fréquences." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS167.
Full textAbstract:
Les océans et la banquise jouent un rôle important dans le système climatique et météorologique. Une future mission satellite en micro-ondes passives basses fréquences, conçue pour observer les régions polaires est actuellement à l’étude à l’Agence Spatiale Européenne pour l’expansion du programme Copernicus. Les observations satellites en micro-ondes passives permettent une observation de la surface de la Terre par tous temps, aussi bien de jour que de nuit. Dans cette thèse, nous nous intéressons à l’estimation des paramètres de surface de l’océan et de la banquise à partir des observations satellites micro-ondes passives basses fréquences. L’objectif est de développer de nouvelles méthodes d’estimation de ces paramètres qui soient plus efficaces et adaptées à la future mission satellite micro-onde passive CIMR (Copernicus Imaging Microwave Radiometer). La première partie de la thèse traite de l’estimation des paramètres océaniques tels que la température de la surface de la mer, la salinité et la vitesse du vent océanique. La deuxième partie traite de l’estimation des paramètres de la banquise tels que la concentration en glace, l’épaisseur de neige et la température d’interface neige-glace. Enfin, avec les méthodes développées dans cette thèse les performances de la mission CIMR sont évaluées et comparées à celles des missions actuellesThe oceans and sea ice play an important role in the climate and weather system. A future low-frequency passive microwave satellite mission designed to observe the polar regions is currently under study at the European Space Agency for the expansion of the Copernicus programme. Passive microwave satellite observations provide all-weather observation of the Earth surface, both day and night. In this thesis, we are interested in estimating ocean and ice surface parameters from low-frequency passive microwave satellite observations. The objective is to develop new methods for estimating these parameters that are more efficient and adapted to the future passive microwave satellite mission CIMR (Copernicus Imaging Microwave Radiometer). The first part of the thesis deals with the estimation of ocean parameters such as sea surface temperature, salinity and ocean wind speed. The second part deals with the estimation of sea ice parameters such as sea ice concentration, snow depth and snow-ice interface temperature. Finally, with the methods developed in this thesis, the performances of the CIMR mission are evaluated and compared with the current missions
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Thompson, Shanley Dawn. "Mapping mixed and fragmented forest associations with high spatial resolution satellite imagery : capabilities and caveats." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/746.
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Satellite imagery such as Landsat has been in use for decades for many landscape and regional scale mapping applications, but has been too coarse for use in detailed forest inventories where stand level structural and compositional information is desired. Recently available high spatial resolution satellite imagery may be well suited to mapping fine-scale components of ecosystems, however, this remains an area of ongoing research.
The first goal of this thesis was to assess the capacity of high spatial resolution satellite imagery to detect the variability in late seral coastal temperate rainforests in British Columbia, Canada. Using an object-based classifier, two hierarchical classification schemes are evaluated: a broad classification based on structural (successional) stage and a finer classification of late seral vegetation associations. The finer-scale classification also incorporates ancillary landscape positional variables (elevation and potential soil moisture) derived from Light Detection and Ranging (LiDAR) data, and the relative contribution of spectral, textural and landscape positional data for this classification is determined. Results indicate that late seral forests can be well distinguished from younger forests using QuickBird spectral and textural data. However, discrimination among late seral forest associations is challenging, especially in the absence of landscape positional variables.
Classification accuracies were particularly low for rare forest associations. Given this finding, the objective of the third chapter was to explicitly examine the caveats of using high spatial resolution imagery to map rare classes. Classification accuracy is assessed in several different ways in order to examine the impact on perceived map accuracy. In addition, the effects on habitat extent and configuration resulting from post-classification implementation of a minimum mapping unit are examined. Results indicate that classification accuracies may vary considerably depending on the assessment technique used. Specifically, ignoring the presence of fine-scale heterogeneity in a classification during accuracy assessment falsely lowered the accuracy estimates. Further, post-classification smoothing had a large effect on the spatial pattern of rare classes. These findings suggest that routinely used image classification and assessment techniques can greatly impact mapping of rare classes.
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Lukacs, Mathew Walter. "Wirelessly sensing resonate frequency of passive resonators with different Q values." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4970.
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Numerous techniques exist for measuring temperature using passive devices such as SAW filters. However, SAW filters have a significant limitation regarding high temperature environments exceeding 1000??C. There are several applications for a high temperature sensor in this range, most notably heat flux or temperature in turbine engines. For these environments, an alternative to SAW filters is to use a passive resonator. The resonate frequency will vary depending on the environment temperature. Understanding how the frequency changes with temperature will allow us to determine the environmental temperature. In order for this approach to work, it is necessary to induce resonance in the device and measure the resonance frequency. However, the extreme high temperature makes wired connections impractical, therefore wireless interrogation is necessary. To be practical a system of wireless interrogation of up to 20cm is desired.ID: 029809938; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.E.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 80-81).
M.S.E.E.
Masters
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Kandasamy, Sasikaran, and s3003480@student rmit edu au. "Investigation of SiC Based Field Effect Sensors with Gas Sensitive Metal Oxide Layers for Hydrogen and Hydrocarbon Gas Sensing at High Temperatures." RMIT University. Electrical and Computer Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080724.142015.
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This PhD thesis sets out to investigate novel Silicon Carbide (SiC) based field effect devices (Schottky and transistor structures), with gas sensitive layers for monitoring hydrogen and propene gases at high temperatures. The devices developed by the author were shown to exhibit sensitivities at least 1~2 orders of magnitude (voltage shift, ¢V) higher than those reported in literature. Not only did the author seek to investigate the gas sensing potential of such devices, but also he set out to study, analyse and establish the gas interaction mechanism of these novel sensors. High temperature tolerant hydrogen and hydrocarbon sensors are required in numerous applications such as: aerospace, nuclear power plant, space exploration and exhaust monitoring in automobiles. Monitoring these gases in a reliable and efficient manner is of great value in these applications, not only from a safety point of view but also for economical reasons. Hence there is an absolute necessity for simple, efficient and high performance sensors not only for monitoring and leak detection but also to function as part of a safety device to prevent accidents. The proposed sensor structure of combining SiC with gas sensitive oxide layers allow them to be operated at high temperatures, making them extremely appealing for direct or in-situ monitoring applications. The microstructural analysis performed using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Rutherford Backscattering Spectroscopy (RBS) provides no evidence of inter-diffusion between different layers, in spite of the sensors being annealing at 650 in O2, H2 and C3H6 atmospheres for approximately 50hrs. Samples in different conditions (as deposited, annealed and tested) were compared. The electrical properties of the MROSiC (current-voltage, I-V and capacitance-voltage, C-V characteristics) and MESFET (drain current-source drain voltage (ID-VSD) and transfer, (ãID-H2 concentration) characteristics) devices were measured in the presence and absence of H2 and C3H6. Several parameters such as barrier height, saturation currents, pinch-off voltages and channel conductance were determined from the electrical characteristics, and their influence on the device performance was studied. The authorfs proposed gas interaction model based on energy band diagram is well supported by the experimental data obtained.
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Kubina, Bernd. "Chipless Wireless High-Temperature Sensing in Time-Variant Environments." Phd thesis, 2017. https://tuprints.ulb.tu-darmstadt.de/6785/13/diss_Kubina.pdf.
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The wireless sensing of various physical quantities is demanded in numerous applications. A usual wireless sensor is based on the functionality of semiconductor Integrated Circuits (ICs), which enable the radio communication. These ICs may limit the application potential of the sensor in certain specific applications. One of these applications stands in the focus of this thesis: the operation in harsh environments, e.g., at high temperatures above 175°C, where most available sensors fail. Chipless wireless sensors are researched to exceed such chip-based limitations.
A chipless sensor is setup as an entirely electro-magnetic circuit, and uses passive Radio Frequency (RF) backscatter principles to encode and transmit the measured value. Chipless sensors that target harsh environment operation are facing two important challenges: First, the disturbance by clutter, caused by time-variant reflections of the interrogation signal in the sensor environment and second, the design of suitable measurand transducers. These challenges are addressed in the thesis. To overcome the first challenge, three basic chipless sensor concepts feasible for operation in clutter environments are introduced. The concepts are realized by demonstrator designs of three temperature sensors and are proofed by wireless indoor measurements. A
channel estimation method is presented that dynamically estimates and suppresses clutter signals to reduce measurement errors. To overcome the second challenge, measurand-sensitive dielectric materials are used as measurement transducers, and are being characterized by a novel high-temperature microwave dielectric characterization method. Complex permittivity characterization results in temperatures up to 900°C are presented.
Finally, in-depth description and discussion of the three chipless concepts is given as well as a performance comparison in wireless indoor measurement scenarios. The first concept is based on polarization separation between the wanted sensor backscatter signal and unwanted clutter. The second concept separates tag and clutter signals in the frequency domain by using harmonic radar. The third concept exploits the slow decay of high-Q resonances in order to achieve the desired separation in time domain. This concept’s realization is based on dielectric resonators and has demon-
strated the capability of wirelessly measuring temperatures up to 800°C without requiring an optical line-of-sight. This performance significantly exceeds temperature- and detection-limitations of commercially available sensors at the current state-of-the-art.
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Su, Yao-sian, and 蘇耀賢. "High-Sample Rate Bus Topology Embedded Temperature Sensing System Design." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/93306801335757131251.
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碩士雲林科技大學
電子與資訊工程研究所
99
With the progress of integrated circuit technology, the number of transistors in monolithic IC has been increased, and the circuit operation speed has been enhanced so that the power density in a chip is rapidly increased. Similarly, the temperature inside the chip is increased that the high temperature in the chip could easily result in errors or permanent damage. Aiming at large system chip temperature, this study proposes the embedded temperature sensing system transmitted by bus. It is applied to monitor the various functional blocks in the chip of the sensing system so as to prevent the system chip from overheat. According to literature review, conventional temperature sensors have achieved the advantages of low power consumption, small area, and complete digitalization. Nevertheless, most of these conventional temperature sensors are single-point sensing; few of them consider the wire routing and the sampling rate between the embedded sensor and the system circuits. They are particularly applied to the situation when several temperature sensors need to be linked. With the self-defined bus transmission protocol, the proposed embedded temperature sensing system transmitted with bus reduces the wire routing complexity when several temperature sensors are linked. Regarding circuit design, previously developed latch based differential ring oscillator temperature sensor with an identity circuit is applied to control the resistance state on bus. When the system is ready to read the remote temperature sensors, all temperature sensors on bus would remain listening; when the control circuit actively sends identity signals, the corresponding temperature sensors would be started. With the same bus, the sensed pulsewidth would be transmitted back to the control circuit. Because of the accurate digital sequential control, the sampling speed would be enhanced 58% comparing to conventional temperature sensing circuits. Both the circuits and the chips in this study successfully implement 0.18 ?慆 COMS technology. Within the supply voltage 1.8V with ±10% variation, the error of the voltage change does not exceed ±6°C, and the temperature sampling rate on bus is 24.5K Sample/Sec. Moreover, adding the calibration circuit in the system circuits could proceed calibration at known temperature (such as 0°C) to make it an absolute temperature sensor. After calibration, the resolution between 0°C~100°C is 0.2°C, the linear error less than ±4°C, the power loss 221?巰, and the total wasted energy 9 nJ.
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Chu, Chung-Hao, and 朱崇豪. "The Research of cytochrome c with high temperature coefficient of resistance for infrared sensing application." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/96698217991732583841.
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碩士國立臺灣大學
光電工程學研究所
99
With the development of thermal imaging, more and more applications are mentioned not in military, but also commercial such as industry monitoring, automobile nightvision, far distance medicine care etc. In infrared thermal imaging, infrared optics system, sensing focal plane arrays and signal processing circuit are intensively researched. The sensing focal plane is very important one. Generally, focal plane arrays are classified as cooled and uncooled. Due to the advantages of low cost and small volume, and the performance is afford to generally commercial applications, we focus on uncooled infrared sensing focal plane array. In all type of uncooled infrared technique, microbolometer is an important one. The microbolometer generates the signals with the resistance changed by temperature difference, hence, the thin film sensing material needs high temperature coefficient of resistance to get larger signal from small temperature difference. In this thesis, we investigated a new sensing material – cytochrome c. By measuring the resistance varies with temperature, we proved the high temperature coefficient of resistance of thin film. And we proposed a new structure composed by SU8 and simulated the responsivity of it. We hoped this method provides a solution for low cost thermal imaging system.
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LIU, JUNG-HSUAN, and 劉榮軒. "Development of Carbon Thin Films on Oxidized Porous-Si for High-Temperature Optical Sensing Applications." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/n2795a.
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碩士南臺科技大學
光電工程系
104
Carbon (C), currently one of the most mature wide-bandgap semiconductors due to its many excellently properties, including a wide bandgap , high electron mobility , high breakdown electric field , high thermal conductivity , as well as good mechanical and chemical stability. In this project , Carbon thin films were prepared on Si substrates with nano-porous Si (NPS) buffer layers. C-based photodetectors were fabricated to explore the potential applications of developed technologies. NPS thin films with uniformly distributed Si nano-crystallites were prepared on heavily doped p+type(100) Si wafers by anodic etching processes with low etching current density of 20mA/cm2. Secondly , the passivation layer of Carbon films were prepared by sputtering on NPS layers. To improve the devices’ performance, Carbon films were also prepared upon oxidized NPS (ONPS) layers that were formed by rapid-thermal oxidizing (RTO) processes from the NPS layers. Finally, inter-digitated nickel (Ni) electrodes were deposited on the front sides of the devices to complete the MSM photodiode structures. The results showed that Carbon films on Si with NPS and ONPS buffer layers had quite good crystallinity and high UV responses. The deposited Carbon films on ONPS exhibited high photo-responsivity for incident wavelengths between 300nm and 500nm, corresponding to the near UV ranges. The developed C/ONPS photodiodes achieved high photo-to-dark current ratio up to about 443 at 350-nm incident light. Although the photo-to-dark current ratio fell to 42.1 when temperature raised to 250℃, but still better than the device that without carbon films. Those results demonstrated that Carbon-on-ONPS photo detectors had high UV sensitivity, thus indicating their high potential in UV-sensing applications.
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Chen, Kuan-Wei, and 陳冠位. "High-performance metal–oxide–semiconductor gas sensors with low-power consumption for room temperature sensing applications." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/unpjnr.
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"Temperature Compensated, High Common Mode Range, Cu-Trace Based Current Shunt Monitors Design and Analysis." Doctoral diss., 2011. http://hdl.handle.net/2286/R.I.9189.
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abstract: Sensing and controlling current flow is a fundamental requirement for many electronic systems, including power management (DC-DC converters and LDOs), battery chargers, electric vehicles, solenoid positioning, motor control, and power monitoring. Current Shunt Monitor (CSM) systems have various applications for precise current monitoring of those aforementioned applications. CSMs enable current measurement across an external sense resistor (RS) in series to current flow. Two different types of CSMs designed and characterized in this paper. First design used direct current reading method and the other design used indirect current reading method. Proposed CSM systems can sense power supply current ranging from 1mA to 200mA for the direct current reading topology and from 1mA to 500mA for the indirect current reading topology across a typical board Cu-trace resistance of 1 ohm with less than 10 µV input-referred offset, 0.3 µV/°C offset drift and 0.1% accuracy for both topologies. Proposed systems avoid using a costly zero-temperature coefficient (TC) sense resistor that is normally used in typical CSM systems. Instead, both of the designs used existing Cu-trace on the printed circuit board (PCB) in place of the costly resistor. The systems use chopper stabilization at the front-end amplifier signal path to suppress input-referred offset down to less than 10 µV. Switching current-mode (SI) FIR filtering technique is used at the instrumentation amplifier output to filter out the chopping ripple caused by input offset and flicker noise by averaging half of the phase 1 signal and the other half of the phase 2 signal. In addition, residual offset mainly caused by clock feed-through and charge injection of the chopper switches at the chopping frequency and its multiple frequencies notched out by the since response of the SI-FIR filter. A frequency domain Sigma Delta ADC which is used for the indirect current reading type design enables a digital interface to processor applications with minimally added circuitries to build a simple 1st order Sigma Delta ADC. The CSMs are fabricated on a 0.7µm CMOS process with 3 levels of metal, with maximum Vds tolerance of 8V and operates across a common mode range of 0 to 26V for the direct current reading type and of 0 to 30V for the indirect current reading type achieving less than 10nV/sqrtHz of flicker noise at 100 Hz for both approaches. By using a semi-digital SI-FIR filter, residual chopper offset is suppressed down to 0.5mVpp from a baseline of 8mVpp, which is equivalent to 25dB suppression.Dissertation/Thesis
Ph.D. Electrical Engineering 2011
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Lee, Ou-Hsiang, and 李翺翔. "Synthesis of Pearl-like NiO Nanoparticles-Functionalized In2O3 Nanonicicles with High Humidity Gas Sensing Property for Room Temperature Gas Sensor Application." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/25569591660908453809.
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碩士國立中興大學
材料科學與工程學系所
103
Conquering humidity influence on the gas sensing property at room temperature has been a major challenge in applied gas sensor device. Herein, we report a multi-functional hybrid system consisting of pearl-like NiO nanoparticles funtionalized on In2O3 nanoicicles by thermal vapor transport and chemical wet approach with tailored sensing properties. In this report, we demonstrate a novel structure of In2O3 nanoicicles with intrigued and sophisticated morphology. The growth mechanism of the In2O3 nanoicicles was investigated and discussed by observing structural evolution during the synthesis processes. The growth mechanism of the In2O3 nanoicicles can be ascribed to Au-catalytic VLS mechanism along [123] direction for the axial growth and VS mechanism for the lateral growth. As the axial growth rate was much faster than the lateral growth, resulted in the evolution of tapered nanoicicles. Pearl-like NiO, on the other side, was controlled and synthesized successfully with a radius 5 nm well distributed on the In2O3 backbone via chemical wet approach. The NiO-functionalized In2O3 nanoicicles (NiO/In2O3) with p-n junction on the contact bridge enhanced surface area and exhibited a remarkable sensing property as well as a selective detection toward NO2 gases owing to the transport behavior of the electron conduction channel. When exposed to NO2 gases with concentration of 30, 15, and 3 ppm, NiO/In2O3 exhibited a remarkable sensing performance with response of 46.6, 8.5, and 3.35 at 100˚C, and a room temperature sensing performance with response of 4.34, 2.1 and 1.76 respectively. In2O3 nanoicicles on the other hand, changed the resistance followed the same trend but with the response of 6.7, 3.56 and 3.01 at 100˚C, and a room temperature sensing performance with response of 2.51, 2.01 and 1.4 respectively. Furthermore, humidity dependence of the gas sensing property was reduced since the presense of NiO can minimize the humidity influence and eventually provided a promising gas sensing property for the application of room temperature gas sensor device.
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You-ChiChen and 陳有錡. "The Study Of A Novel Pd/MOX/Diamond /P-SiPIN Diode With All Nanorods Structure For High Temperature CO Sensing Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/13166510233606720084.
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Payne, Meredith C. "Development and use of satellite-derived sea-surface temperature data for the nearshore North Pacific and Arctic Oceans : temperature pattern analysis and implications for climate change at ecoregional scale." Thesis, 2012. http://hdl.handle.net/1957/28626.
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The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. Recent research indicates that there has been a warming trend in ocean temperatures over the last 50 years. Hence, we sought to identify and demonstrate how a particularly germane SST dataset can be used within the scope of global climate change research. For this project we assembled a 29-year nearshore time series of mean monthly SSTs along the North Pacific coastline, as well as mean monthly SSTs for ice-free regions of the Arctic, using remotely-sensed satellite data collected with the Advanced Very High Resolution Radiometer (AVHRR) instrument. By providing detailed information concerning both dataset generation and data limitations, we aimed to make these data comprehensible to an expanded audience concentrating on life sciences rather than the traditionally physical science-based community. Furthermore, by making these data freely and publically available in multiple formats, including GIS (geographic information systems) layers, we expand their visibility and the extent of their use. We then used the dataset to describe SST patterns of nearshore (< 20 km offshore) regions of 16 North Pacific ecoregions, and of ice-free regions of 20 Arctic ecoregions, as delineated by the Marine Ecoregions of the World (MEOW) hierarchical schema. Our work creates a better understanding of present temperature regimes in these critically sensitive areas, from which we can draw several basic conclusions. 1) AVHRR SST measurements alone are sufficient to identify temperature patterns pertinent to determining health of ecosystems; 2) Within the nearshore North Pacific, ecoregions along the California Current System are most vulnerable to habitat-altering SST changes; 3) sea ice distribution is a major factor affecting SSTs in Arctic ecoregions, causing concern for the welfare of Arctic species.Graduation date: 2012
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"High-Resolution Martian Soil Thickness Derived from Yearly Surface Temperatures." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.17871.
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abstract: The temperature of a planet's surface depends on numerous physical factors, including thermal inertia, albedo and the degree of insolation. Mars is a good target for thermal measurements because the low atmospheric pressure combined with the extreme dryness results in a surface dominated by large differences in thermal inertia, minimizing the effect of other physical properties. Since heat is propagated into the surface during the day and re-radiated at night, surface temperatures are affected by sub-surface properties down to several thermal skin depths. Because of this, orbital surface temperature measurements combined with a computational thermal model can be used to determine sub-surface structure. This technique has previously been applied to estimate the thickness and thermal inertia of soil layers on Mars on a regional scale, but the Mars Odyssey Thermal Emission Imaging System "THEMIS" instrument allows much higher-resolution thermal imagery to be obtained. Using archived THEMIS data and the KRC thermal model, a process has been developed for creating high-resolution maps of Martian soil layer thickness and thermal inertia, allowing investigation of the distribution of dust and sand at a scale of 100 m/pixel.Dissertation/Thesis
M.S. Geological Sciences 2013
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Lukic, Zdravko. "Design and Practical Implementation of Advanced Reconfigurable Digital Controllers for Low-power Multi-phase DC-DC Converters." Thesis, 2012. http://hdl.handle.net/1807/33855.
Full textAbstract:
The main goal of this thesis is to develop practical digital controller architectures for multi-phase dc-dc converters utilized in low power (up to few hundred watts) and cost-sensitive applications. The proposed controllers are suitable for on-chip integration while being capable of providing advanced features, such as dynamic efficiency optimization, inductor current estimation, converter component identification, as well as combined dynamic current sharing and fast transient response.
The first part of this thesis addresses challenges related to the practical implementation of digital controllers for low-power multi-phase dc-dc converters. As a possible solution, a multi-use high-frequency digital PWM controller IC that can regulate up to four switching converters (either interleaved or standalone) is presented. Due to its configurability, low current consumption (90.25 μA/MHz per phase), fault-tolerant work, and ability to operate at high switching frequencies (programmable, up to 10 MHz), the IC is suitable to control various dc-dc converters. The applications range from dc-dc converters used in miniature battery-powered electronic devices consuming a fraction of watt to multi-phase dedicated supplies for communication systems, consuming hundreds of watts.
A controller for multi-phase converters with unequal current sharing is introduced and an efficiency optimization method based on logarithmic current sharing is proposed in the second part. By forcing converters to operate at their peak efficiencies and dynamically adjusting the number of active converter phases based on the output load current, a significant improvement in efficiency over the full range of operation is obtained (up to 25%). The stability and inductor current transition problems related to this mode of operation are also resolved.
At last, two reconfigurable digital controller architectures with multi-parameter estimation are introduced. Both controllers eliminate the need for external analog current/temperature sensing circuits by accurately estimating phase inductor currents and identifying critical phase parameters such as equivalent resistances, inductances and output capacitance. A sensorless non-linear, average current-mode controller is introduced to provide fast transient response (under 5 μs), small voltage deviation and dynamic current sharing with multi-phase converters. To equalize the thermal stress of phase components, a conduction loss-based current sharing scheme is proposed and implemented.