Дисертації з теми "Temperature and RH sensors"
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1
Taguett, Amine. "Synthèse et étude thermodynamique d’alliages Ir-Rh à l’état massif et en films minces pour la réalisation de capteurs SAW fonctionnant à haute température (700°C-1000°C) dans l’air." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAA016/document.
Повний текст джерелаАнотація:
La technologie des capteurs à ondes élastiques de surface, appelés SAW pour Surface acoustic waves, existe depuis une cinquantaine d’années. Cette technologie est largement utilisée dans l’industrie des télécommunications et en perpétuelle évolution pour la réalisation de microcapteurs dans des secteurs à fortes contraintes tels que l’aéronautique, l’automobile, la métallurgie ou encore dans le domaine du médical. Leur forte sensibilité aux conditions environnementales, leur taille réduite et la possibilité de les interroger à distance sans aucune électronique embarquée (capteurs passifs), confèrent à cette technologie un fort potentiel d’innovation pour une utilisation en environnements extrêmement hostiles, et notamment comme capteurs de températures, de pressions, de déformations, de concentrations d'espèces chimiques ou biologiques… Une voie d’innovation réside dans l’optimisation des électrodes de ces capteurs appelés IDTs pour InterDigital Transducers. Ces électrodes métalliques d’une centaine de nanomètres d’épaisseur sont structurées sous forme de peignes interdigités sur un substrat piézoélectrique. Nos travaux se sont focalisés sur le choix des matériaux pour la réalisation des IDTs pour une utilisation à très hautes températures. Cela impose de trouver un matériau conducteur, stable physiquement et chimiquement, dont la mise en forme en film mince (100 nm d'épaisseur typique) n’altère pas son fonctionnement dans ces conditions d’usage extrêmes : températures voisines de 1000°C sous atmosphère oxydante. Une étude récente a mis en évidence la pertinence de l’utilisation d’alliages binaires Ir-Rh massifs pour des applications connexes de celles visées. L’objectif de ce projet est de transposer les propriétés des alliages Ir-Rh massifs à des films minces de même nature, en collectant de nouvelles données thermodynamiques relatives au système métallique Ir-Rh. Malgré les difficultés des analyses thermiques qui ont été menées jusqu’à 2300 °C, nous avons pu réaliser les premières mesures expérimentales des températures d’équilibres solide-liquide (solidus et liquidus) de quelques alliages Ir-Rh. Une part importante du travail a ensuite été consacrée à la réalisation de campagnes de dépôts de films minces Ir Rh afin d’optimiser les paramètres clés du dépôt permettant l’obtention de films présentant les stœchiométries et microstructures recherchées. Enfin, l’évaluation des performances des dispositifs SAW, élaborés à partir des films minces optimisés, a donné des résultats très prometteurs : après une phase de stabilisation dans les premières heures de recuit, le signal SAW s’est montré constant tout au long d’une période de 2 mois dans l’air à 800 °CThe surface acoustic waves (SAW) technology was invented approximately fifty years ago. This technology is currently widely used in the telecommunication industry to make, among others, GHz-range filters. Another very active development axis for the SAW technology is related to the achievement of micro sensors (to measure temperatures, pressures, deformations, concentrations of chemical or biological species) for industrial sectors with strong constraints such as aerospace, automotive, metallurgy, or medical sectors. Their high sensitivity to environmental conditions, their small size and the possibility to interrogate them remotely without adding any embedded electronics (passive sensors), provides SAW sensors a high innovation potential, in particular for applications taking place in hostile environments. SAW devices are constituted by a piezoelectric substrate on which are patterned electrodes from a conductive film. These electrodes are typically 100 nm-thick and are called, because of their shape, interdigital transducers (IDT). Our work was mainly focused on the choice of materials for the realization of IDTs to be used at very high temperatures, in air, for weeks periods, the current state-of-the-art operating temperature being close to 850 °C. Achieving high temperature IDTs requires finding a conductive material, physically and chemically stable under oxidizing conditions up to 1000°C, which retains its properties when grown as a thin layer. A recent study has highlighted the relevance of bulk Ir-Rh binary alloys for applications closely related to the targeted ones. The objective of this project is to transfer the properties of bulk Ir-Rh alloys to Ir-Rh thin layers, by collecting new thermodynamic data for the Ir-Rh binary system. Despite the difficulties of thermal analyses which were conducted up to 2300 °C, we have been able to carry out the first experimental measurements of solid-liquid temperatures equilibria (solidus and liquidus) of some Ir-Rh alloys. An important part of the work was afterwards devoted to the realization of Ir-Rh thin films deposition campaigns to optimize the key parameters and obtain films having the relevant stoichiometry and microstructure. Finally, the performance of SAW devices, made from optimized thin films, was evaluated. Very promising results were obtained: after a stabilization phase in the early hours of annealing, the SAW signal was unchanged throughout a 2 months period at 800 °C in air atmosphere
2
Hout, S. R. in't. "High-temperature silicon sensors." Delft, the Netherlands : Delft University Press, 1996. http://books.google.com/books?id=dApTAAAAMAAJ.
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3
Hashmi, А., and А. Kalashnikov. "Comparison of the responsiveness of ultrasonic oscillating temperature sensors (UOTSes) and conventional sensors to temperature inflection." Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/55751.
Повний текст джерелаАнотація:
Ultrasonic oscillating temperature sensors
(UOTSes), in distinction to conventional temperature
sensors, feature almost negligible settling time. This
property can be useful for detecting malfunctions, failures
and misuses of heat exchangers. However, most exchangers
handle substantial thermal masses, which obscure the
detection of any temperature changes.
We compared the responsiveness of conventional
DS18B20 sensors and an UOTS to the change in the
temperature gradient of over 3.5 kg of water using a
posteriori records. Temperature inflection points were
estimated by extending the curves for separate distinct
heating and cooling intervals that fit best and finding their
interception. For the UOTS, the interception occurred about
100 seconds sooner, making it a potential candidate for
detecting heat exchangers’ irregularities.
4
Yerochin, S. Yu, A. N. Demenskiy, V. A. Krasnov, and S. V. Shutov. "Diode temperature sensors with tunable sensitivity." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45971.
Повний текст джерелаАнотація:
We investigated the possibility of using of AlGaInP heterostructures with p-n junction as diode temperature sensors having quasi-linear dependence of the forward voltage drop on the ambient temperature at the fixed direct current. Thus we measured the current-voltage characteristics of the p-n structures in the temperature range 293-550 K. Using the data obtained we calculated the differential current thermal sensitivity of the structures mentioned. A semilogarithmic plot of the thermal sensitivity vs. forward current dependence is presented in the figure.
5
Selli, Raman Kumar. "Fibre optic temperature sensors using fluorescent phenomena." Thesis, City University London, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236641.
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6
Banim, Robert Seamus. "Improved temperature sensors for the process industry." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245572.
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7
Birley, Joseph Leonard Mark. "An investigation of temperature controlled humidity sensors." Thesis, De Montfort University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393232.
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8
Cederlund, Jacob. "Radiated Susceptibility Measurements on Analogue Temperature Sensors." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279959.
Повний текст джерелаАнотація:
The need for electromagnetic compatibility is growing steadily as the usage of electronics in our daily lives is increasing more than ever. A common issue encountered in electromagnetic compatibility testing is analogue sensors that fail when exposed to electromagnetic fields. Testing how well electronics do when exposed to electromagnetic fields is called susceptibility testing, and standards for how to do these tests have been developed to ensure that the results of the tests can be reproduced. In this thesis work, analogue temperature sensors have been shielded using a few common techniques. The susceptibility of the sensors has been analysed by looking at their output voltage when the sensors were exposed to electro- magnetic fields of different field strengths. The output of the sensors was read by an Arduino that was shielded and tested to make sure it would not be affected by the electromagnetic fields used in the sensor tests. The result of the first set of sensor tests shows that shielding the cables running to the analogue temperature sensors and filtering away disturbances using ferrites gives a considerable decrease in susceptibility against electro- magnetic fields, while twisted cables and RC-filters did not. The results also showed that the introduction of a ground plane increased the susceptibility of the sensors, which most likely was due to it not providing the current with a path of less impedance and only served to increase the length of the unintentional antenna, which made it couple to the electromagnetic field more easily. However, during a second round of testing, the results of all the tests were hard to reproduce exactly, which calls into question how trustable the results of standardised susceptibility tests are. Therefore, when designing for the electromagnetic susceptibility of a product, a rather wide margin should be used in order to make sure that the product can reliably pass susceptibility tests.Användningen av elektronik ökar i samhället och därför även nödvändigheten för testning av elektromagnetisk kompatibilitet. Ett vanligt problem inom elektromagnetisk kompatibilitet är att analoga sensorer lätt blir utstörda av elektromagnetiska fält. Hur man ska testa en elektronisk produkts känslighet mot elektromagnetiska fält styrs av standarder som ser till att resultaten av testerna går att återskapa. I detta examensarbete har analoga temperatursensorer skärmats med ett par vanliga metoder. Sensorernas känslighet har analyserats genom att undersöka hur deras utspänning påverkas när sensorn blir utsatt för elektromagnetiska fält med olika fältstyrkor. Sensorernas utspänning lästes av en Arduino som skärmades och testades för att se till all att den inte påverkades av de elektromagnetiska fälten som användes under testandet av sensorerna. Resultaten från de första sensortesterna visar att använda skärmade kablar till de analoga temeperatursensorerna och att filtrera bort störningar med ferriter sänkte sensorernas känslighet mot elektromagnetiska fält betydligt medan tvinnade kablar och RC filter inte gjorde det. Testerna visade också att jord- plan i detta fall ökade sensorernas känslighet då de inte erbjöd en bättre väg för strömmen att gå utan endast skapade en längre oavsiktlig antenn, vilket gjorde att den lättare kunde koppla till det elektromagnetiska fältet. Däremot visade det sig i en andra testomgång, att resultaten inte gick att återskapa ex- akt. Detta ifrågasätter hur tillförlitliga dessa standardiserade tester är och visar att man bör ha en ganska bred marginal när man designar för att minska en produkts känslighet mot elektromagnetiska fält, så att den på ett tillförlitligt sätt kommer kunna klara av känslighetstester.
9
Rashidi, Mohammadi Abdolreza. "MEMS pressure, temperature and conductivity sensors for high temperature and harsh environments." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33783.
Повний текст джерелаАнотація:
Kraft pulp digesters have been used to convert wood chips into pulp for manufacturing a wide variety of paper products. Inside a kraft digester, chemical reactions remove lignin from their wood matrix in a caustic environment (pH~13.5, 170°C, 2MPa). Data on actual internal operating conditions in a kraft digester is needed to optimize kraft digester operation and obtain maximum production quality. Currently, this information is limited to selected static locations on the periphery of the digester. The objective of this thesis is to develop miniature temperature, pressure, and liquid conductivity sensors for use in autonomous flow-following SmartChips to measure kraft process variables within the digester during their passage through the process.
Combined capacitive pressure and temperature sensors were fabricated by bonding silicon and Pyrex chips using a new polymeric gap-controlling layer and a high temperature adhesive. A simple chip bonding technique involving insertion of the adhesive into the gap between two chips was developed. A silicon dioxide layer and a thin layer of Parylene were deposited to passivate the pressure sensor diaphragm against the caustic environment in kraft digesters. The sensors were characterized at both high temperatures and pressures and no signs of corrosion could be identified on the sensors.
Integrated piezoresistive pressure and temperature sensors consisting of a square silicon diaphragm and high resistance piezoresistors were developed. A new Parylene and silicone conformal coating process were developed to passivate the pressure sensors against the caustic environment. The sensors were characterized up to 2MPa and 180°C in an environmental chamber. The sensors’ resistances were measured before and after testing in a kraft pulping cycle and showed no change in their values. SEM pictures and topographical surface analyses were also performed before and after pulp liquor exposure and showed no observable changes.
Combined liquid conductivity and temperature sensor packages consisting of a platinum resistance temperature detector (RTD) and a four-electrode conductivity sensor formed by stainless steel electrodes and installed on a polyetheretherketone (PEEK) enclosure were developed. The sensors were characterized up to 180°C at NaOH concentrations of 10-100g/l in the presence of wood chips and survived with no signs of corrosion.
10
Spirig, John Vincent. "A new generation of high temperature oxygen sensors." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1188570727.
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11
Zhao, Weizhong. "Optical fibre high temperature sensors and their applications." Thesis, City University London, 2011. http://openaccess.city.ac.uk/1190/.
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12
Häggmark, Ilian. "Fiber Bragg Gratings in Temperature and Strain Sensors." Thesis, KTH, Tillämpad fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145741.
Повний текст джерелаАнотація:
ROYAL INSTITUE OF TECHNOLOGY Abstract Laser Physics Group Department of Applied Physics SA104X Degree Project in Engineering Physics, First Cycle Fiber Bragg Gratings in Temperature and Strain Sensors by Ilian Haggmark Supervisor: Michael Fokine A Fiber Bragg Grating (FBG) is a periodic variation of the refractive index in an optic ber. It works as a wavelength selective lter and is used in several dierent applications such as telecommunication and sensor technology. Fiber sensors are based on a simple principle; the ber is aected by strain, temperature etc. due to which the selection of wavelengths in the FBG change. With an optical spectrum analyzer the changes in wavelength reection can be observed and converted to the physical quantity measured. In this thesis the properties of FBGs used in temperature and strain sensors are tested. Experiments to improve the precision of the sensors by embedding FBGs in metal are also carried out.KUNGLIGA TEKNISKA HOGSKOLAN Sammanfattning Laserfysikgruppen Institutionen for Tillampad Fysik SA104X Examensarbete inom Teknisk Fysik, Grundniva Fiberbraggitter i Temperatur- och Spanningssensorer av Ilian Haggmark Handledare: Michael Fokine Ett berbraggitter (FBG) ar en periodisk variation av brytningsindex i en optisk ber. FBG fungerar som ett vaglangdsselektivt lter och har era olika tillampningar inom bland annat telekomunikation och sensorerteknik. Fibersensorer bygger pa en enkel princip; bern paverkas av temperatur, spanning m.m. och da forandras ltreringen av vaglangder i FBG. Med en optisk spektrumanalysator kan forandringar i vaglangd registreras och konverteras till den storhet som mats. In detta examensarbete testas de egenskaper hos FBG som utnyttjas i temperatur- och spanningssensorer. Experiment for att forbattra precisionen hos sensorerna genom att gjuta in FBG i metall utfors ocksa.
13
Jones, Alexander R. "The application of temperature sensors into fabric substrates." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/11991.
Повний текст джерелаАнотація:
Master of ScienceDepartment of Apparel, Textiles, and Interior Design
Diana Sindicich
With continuing advancements in the area of electronics, there are more ways in which they are utilized in order to improve the lives of humans. These advancements have to led to the incorporation of electronic components into fabric structures, creating electronic textiles (e-textiles). As it has become possible to place small electrical components within clothing without the performance of the electronics being hampered, research has been conducted in the use of e-textiles in measuring aspects of the human body, such as the heart rate and perspiration rate. In the area of skin temperature, research has been conducted in the past using e-textiles for skin temperature measurement, but past efforts have been unsuccessful in incorporating useable temperature sensors into a fabric substrate. This study compared three types of sensors incorporated into woven and knitted fabrics, using insulated thermocouples, un-insulated thermocouples, and resistance temperature directors (RTDs). Three incorporation methods (weaving, interlacing into knit, and stitching) were used in six fabric samples, with the three sensor types woven and stitched into three woven fabric samples, while the sensors were interlaced into knitted fabric and stitched into the three knitted samples. Fabric hand washing and temperature measurement tests were conducted, and the temperature readings were analyzed statistically for comparison. The analysis conducted showed that the thermocouples that were interlaced or stitched onto the knitted fabric samples were best for temperature measurement due to their accuracy and durability, while the RTDs were unusable as a temperature sensor, as the removal of the electrical connectors during washing eliminated the calibration that was established before washing. This research was supported in part by the Institute for Environmental Research at Kansas State University.
14
Hadeler, Oliver. "Distributed feedback fibre laser strain and temperature sensors." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/46100/.
Повний текст джерелаАнотація:
This thesis presents the development of two new types of polarimetric distributed feedback (DFB) fibre laser sensors for simultaneous strain and temperature measurements. These fibre Bragg grating (FBG) based sensors offer strain and temperature measurement accuracies of ±0.3 - ±15 με and ±0.04 - ±0.2°C which are suitable for many applications. The main advantage of these DFB fibre laser sensors over other FBG based sensors is the simplicity of their interrogation system. The first type of sensor operates stably in a single longitudinal mode which splits into two orthogonally polarised modes. This sensor utilises the wavelength of one polarisation mode and the RF beat frequency between the two polarisation modes. The system complexity is reduced to a minimum in the dual longitudinal mode polarirnetric DFB fibre laser sensor which utilises the RF beat frequencies between two longitudinal modes and their associated orthogonal polarisations, therefore requiring only a simple and cost effective frequency counter. -ions and pump excited state absorption into account. An extended version of this model incorporates, for the first time, self-heating in DFB fibre lasers which is caused by non-radiative decays. The performance of DFB fibre lasers employed in telecommunication applications is likely to benefit from these modelled results, which are also verified by experimental data.
15
Xu, Juncheng. "High Temperature High Bandwidth Fiber Optic Pressure Sensors." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/25988.
Повний текст джерелаАнотація:
Pressure measurements are required in various industrial applications, including extremely harsh environments such as turbine engines, power plants and material-processing systems. Conventional sensors are often difficult to apply due to the high temperatures, highly corrosive agents or electromagnetic interference (EMI) noise that may be present in those environments. Fiber optic pressure sensors have been developed for years and proved themselves successfully in such harsh environments. Especially, diaphragm based fiber optic pressure sensors have been shown to possess advantages of high sensitivity, wide bandwidth, high operation temperature, immunity to EMI, lightweight and long life.
Static and dynamic pressure measurements at various locations of a gas turbine engine are highly desirable to improve its operation and reliability. However, the operating environment, in which temperatures may exceed 600 °C and pressures may reach 100 psi (690 kPa) with about 1 psi (6.9kPa) variation, is a great challenge to currently available sensors. To meet these requirements, a novel type of fiber optic engine pressure sensor has been developed. This pressure sensor functions as a diaphragm based extrinsic Fabry-Pérot interferometric sensor. One of the unique features of this sensor is the all silica structure, allowing a much higher operating temperature to be achieved with an extremely low temperature dependence. In addition, the flexible nature of the sensor design such as wide sensitivity selection, and passive or adaptive temperature compensation, makes the sensor suitable for a variety of applications
An automatically controlled CO2 laser-based sensor fabrication system was developed and implemented. Several novel bonding methods were proposed and investigated to improve the sensor mechanical ruggedness and reduce its temperature dependence.
An engine sensor testing system was designed and instrumented. The system generates known static and dynamic pressures in a temperature-controlled environment, which was used to calibrate the sensor.
Several sensor signal demodulation schemes were used for different testing purposes including a white-light interferometry system, a tunable laser based component test system (CTS), and a self-calibrated interferometric-intensity based (SCIIB) system. All of these sensor systems are immune to light source power fluctuations, which offer high reliability and stability.
The fiber optic pressure sensor was tested in a F-109 turbofan engine. The testing results prove the sensor performance and the packaging ruggedization. Preliminary laboratory and field test results have shown great potential to meet not only the needs for reliable and precise pressure measurement of turbine engines but also for any other pressure measurements especially requiring high bandwidth and high temperature capability.Ph. D.
16
Jin, Sheng. "Silicon carbide pressure sensors for high temperature applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1296096110.
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17
Almutairi, Fajhan Hilal Hamad. "Fibre optic distributed temperature sensors applications and temperature modelling in intelligent wells environments." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/63.
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18
Smith, Stephen Roy Walter. "Remote optical fibre temperature and groundwater sensing." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266224.
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19
Kennedy, Jermaine L. "Investigations of fiber optic temperature sensors based on Yb:Y3Al5O12." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001566.
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20
Wang, Jun. "Packing design of MEMS pressure, temperature and other sensors." Mémoire, École de technologie supérieure, 2008. http://espace.etsmtl.ca/623/1/WANG_Jun.pdf.
Повний текст джерелаАнотація:
Dans certaines recherches précédentes, la fabrication des capteurs de pression se basait
sur les puces MEMS à base de SiC (Silicon Carbide). Cependant, des chercheurs de
l'Université Concordia ont démontré récemment que SiCN (Silicon Carbide Nitride) avait
un avantage plus important par rapport au Si (Silicon) ou SiC à haute température. Il
serait donc un matériel potentiel dans un environnement hostile. Dans ce mémoire, un
bref historique sur les capteurs MEMS à haute température sera introduit. Certaines
questions dont le choix du matériel, la fabrication, l'empaquetage, et l'application des
capteurs de température MEMS seront discutées. Une approche pour le conditionnement
des capteurs de pression à haute température sera présentée et quelques prototypes seront
créés avec succès. En outre, certaines simulations pour ces prototypes seront étudiées et
les résultats des simulations seront examinés.
21
Agbor, N. E. "Gas sensors using organic thin films at room temperature." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5694/.
Повний текст джерелаАнотація:
The thesis describes work on the thin film deposition, characterization and gas sensing of three groups of organic materials: polyaniline, lutetium bisphthalocyanine and metallotetraphenylporphyrins. These materials were deposited by evaporation, spinning and using the Langmmr-Blodgetttechnique. Film characterization by dc conductivity, scanning electronmicroscopy, surface plasmon resonance, ultraviolet/visible and infrared spectroscopy is described. Gas-induced changes in devices coated with the thinorganic films were monitored at the molecxilar level using Fourier transform infrared spectroscopy and at the macroscopic level using a chemiresistor and surface plasmon resonance. The gases used have included NO(_x), H(_2)S, SO(_2), COand CH(_4) at room temperature and pressure. Devices made with the thinorganic films were reversibly sensitive to some of the gases at low concentrations (<10ppm), but the reactions were irreversible at high concentrations (>100ppm). Polyaniline is shown to exhibit a different chemical structure, reflecting the conditions of its deposition. Spun films were found to be in the emeraldine baseform, the evaporated films were physically and chemically similar toleucoemeraldine base while the Langmuir-Blodgett films were closer topemigraniline, the completely oxidized form of polyaniline. All the types of polyaniline films were sensitive to H(_2)S and NO(_x) concentrations down to4ppm. Only spun and evaporated films were responsive to SO(_2). The spun layers were most sensitive to SO2 and least sensitive to NO(_x)- In contrast, the evaporated layers were most sensitive to NO(_x)- The changes recorded in these measurements occurred after a delay time of few seconds, but were complete lyirreversible for exposure to high gas concentrations. However, no response was observed when exposed to CO or CH(_4) even at very high concentrations. Infrared spectroscopy studies indicated the irreversible changes, for example when exposed to NO(_x), are due oxidation of benzoid rings into quinoid structures. Lutetium bisphthalocyanine has been deposited by the Langmuir-Blodgett technique. Using changes in conductivity, LB layers of lutetium bisphthalocyanine showed responses to NO(_x), H(_2)S and SO(_2) at concentrations below l00ppm. However, using surface plasmon resonance, only the NO(_x), induced changes could be measured at concentrations below l00ppm. These responses- occurred after a delay time of a few seconds and were partially reversible. Cobalt (II) methoxyltetraphenyl porphyrin has been deposited mainly by the Langmuir-Blodgett technique. Gas induced changes in the film were monitored using changes in dc conductivity and surface plasmon resonance. In all cases, NO(_x) was reversibly detected, but at a much higher concentration (>100ppm)than for the other materials in this thesis.
22
Page, Julian. "Factors affecting low temperature performance of zirconia gas sensors." Thesis, Middlesex University, 2001. http://eprints.mdx.ac.uk/8007/.
Повний текст джерелаАнотація:
A reduction in the operation temperature of zirconia ceramic gas sensors is highly desirable for a number of practical reasons. This work seeks to investigate the factors that prevent a reduction in operation temperature and propose methods by which these may be resolved. A novel approach to sensor fabrication has been developed and employed with the advantage of reduced device complexity that should lead to subsequent cost and reliability benefits. Leakage rates in these devices have been shown to be small and electrochemical in origin. Leakage was greater than reported for gold seal devices, partly due to increased electrode activity. The flexibility of device configuration allows a variety of sensor geometries and functions to be realised. This flexibility led to the characterisation of sensors at the upper and lower ends of measurement range and the identification of deviations from theoretical performance. These deviations have been reconciled with theory extended to cover these limits. Such sensors are known to be sensitive to reducible gas species such as CO2 and H2O with a second limiting plateau allowing quantification of these gases. Such analysis capabilities have been found to be extended by incorporating a second pair of electrodes. These effects have not previously been reported. Sensors have been shown to be more sensitive to H2O than to CO2. To investigate the low temperature response of sensors, a variety of techniques and analyses have been developed and are employed with varying success. Impedance spectroscopy was by far the most useful and revealing tool but this is a function of the highly developed hardware and sophisticated control and analysis software bought as a complete system. Gas step changes and current / voltage sweeps were also useful as comparative techniques but could not separate out component mechanisms. Scanning electron microscopy proved to be a vital tool as it allowed vital information to be obtained concerning electrode and electrolyte microstructure. Again this is a function of a highly developed and sophisticated instrument. The techniques of pressure and concentration modulation were limited in terms of ease of use, measurement range and results interpretation. The main drawbacks were limited frequency ranges and laborious data collection and analysis. They do both however show large potential for improvement. Both amperometric and potentiometric sensors response rates were analysed with a variety of noble metal electrodes using each technique. Electrode material proved to have a marked effect on sensor performance with the best results obtained with silver and electro-deposited platinum. Scanning electron microscopy of silver showed that a finely divided and openly porous electrode was not required for high performance contrary to expectations. This is thought to be due to the solubility of oxygen in this metal. With platinum however, the improved microstructure is thought to be a signifîcant factor in electro-deposited and cermet electrode performance. Response rates in amperometric sensors did not show any significant temperature dependence although a restriction in measurement range was observed. Response rates were suspected to be mainly influenced by sensor geometry whilst measurement range was a function of sensor geometry, electrolyte conductivity and electrode activity. Improved electrolytes will provide improvements and may come in the form of attention to the YSZ system or by employing an alternative ion conductor such as ceria. Close attention to sensor dimensions provides possibility for enhancements. In amperometric devices for instance a long, thin diffusion barrier is required leading to a small internal cavity with a large electrode surface area and a thin electrolyte membrane.
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Mohammadazari, Pejman. "Application of Capacitive Temperature Sensors for Food Processing Applications." Thesis, Southern Illinois University at Edwardsville, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13421017.
Повний текст джерелаАнотація:
This thesis presents the design, analysis and optimization of a MEMS capacitive temperature sensor. The capacitive sensors are utilized in a wide range of applications from industrial and automotive applications to biomedical and food processing. A capacitive sensor has two conductive electrodes and its working principle depends on the change in the position of the electrodes or their effective area, which ultimately results in a change in the capacitance of the device. This thesis describes the modeling and the simulation results of a capacitive temperature sensor with a set of bimorph beams working as thermal actuators. The thermal actuator creates out-of-plane displacements and changes the distance between the electrodes as the ambient temperature changes. The presented bimorph capacitive temperature sensor consists of two bilayer silicon-gold beams and two capacitive electrodes, one of them is fixed to the substrate and the second one is connected to the beams. Different beam sizes and electrode shapes are designed and simulated and the characteristics capacitance-temperature (C-T) response of the sensor is obtained. The goal of this work is to modify and optimize the sensor geometry such that the C-T response is more linear, providing nearly constant sensitivity. ANSYS mechanical APDL is used as the finite element software for simulation and optimization of the sensor design, and coupled-field multiphysics solver is utilized to solve the electrostatic and structural domains. The simulation results show that for a given fabrication process, where the thickness of the structural and sacrificial layers in fabrication process is fixed, it is possible to modify the dimensions and geometry of the sensor such that a C-T response with high linearity is obtained.
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Vysniauskas, Aurimas. "Molecular rotors as sensors of microscopic viscosity and temperature." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/55240.
Повний текст джерелаАнотація:
Microscale viscosity is a key parameter that defines the physical makeup of a system, controlling viscoelastic properties of microscopic objects. Additionally, microviscosity within a living cell controls the rate of mass transport through a cell and is hence intimately linked to the activity of a cell. Therefore, measuring viscosity on a microscale represents an important challenge within both physical and biological sciences. So far, one of the most informative and convenient ways for doing this is to use fluorescent 'molecular rotors', which are the viscosity-sensitive fluorophores. The characterisation and application of several previously unexplored molecular rotors are the main topics explored in this thesis. First, porphyrin dimers are examined and characterised as dual viscosity sensors capable of measuring viscosity using their two photophysical parameters: the ratio of two peaks in the fluorescence spectrum and the fluorescence lifetime. The dimer was thus characterised as an attractive dual viscosity sensor displaying absorption and emission in the tissue optical window. Then the porphyrin dimers are applied for imaging microviscosity in lipid monolayers and bilayers. Finally, the porphyrin dimer is used for sensing dynamic change of microviscosity in lipid monolayers and living cells undergoing oxidation by singlet oxygen. Secondly, the changes in viscosity of model lipid membranes under oxidation are further examined using the molecular rotor Bdp-C10, which fully embeds in the lipid tail region of the lipid bilayer. Changes in viscosity are measured at several different bilayer positions of the oxidant relative to the rotor: on the surface, inside the tail region and outside the bilayer in the aqueous phase. Additionally, we report striking differences in the dynamic viscosity change during Type I and Type II photosensitisations and uncover the mechanistic details of the oxidation utilising the ability of molecular rotors to provide spatially resolved information. In the last two chapters, we examine if molecular rotors are sensitive to temperature, which is an important topic that has not previously investigated. The molecular rotors demonstrate contrasting types of temperature sensitivity. Lastly, the temperature-dependence of molecular rotors was put to use by employing Kiton Red for measuring temperature in laser-heated aerosol particles and by using one of the porphyrin dimers for performing the first ever to our knowledge dual viscosity and temperature measurement on a microscopic scale.
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Loskutova, Ksenia, and Daniel Neuman. "3D-printed temperature sensors based on Fiber Bragg Gratings." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195841.
Повний текст джерелаАнотація:
Fiber Bragg Gratings is a type of optical sensor used to measure temperature in many different fields. They have many advantages in relation to standard electric thermometers. The optical fiber and grating is cheap, these optical fiber sensor systems are expensive mainly due to the spectrum analyzer, so it is preferable to minimize the cost while keeping the accuracy as high as possible. By increasing the thermal response of the fiber it is possible to reduce the overall cost of the sensor system. The thermal response can be increased if a material with greater thermal expansion than the fiber is used as coating. Plastic is a coating material with potential due to its availability, low cost and high coefficient of thermal expansion. With 3Dprinting it is possible to choose from a large range of materials available and customize the functionality of the sensor. In this degree project we examined the functionality of a PLA coated Fiber Bragg Grating sensor where the coating was applied using a 3D-printer. Our findings shows that these type of sensors could meet the requirements if used within a specific temperature range.
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Sving, Andreas. "Investigation of High-Temperature Sensors for Tube Monitoring Applications." Thesis, Uppsala universitet, Solcellsteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-434360.
Повний текст джерелаАнотація:
This report covers the investigation of the next generation of sensors to be used in the sensor based tube system known as SentusysTM. One essential feature of the next generation of sensors is high-temperature endurance. The sensors (strain gauges and thermocouples) have been produced by means of thermal spraying techniques, short-pulse laser ablation and laser cladding. It has been found that the sensors seem to work in general, however, much research and development remain.
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Zhu, Yizheng. "Miniature Fiber-Optic Sensors for High-Temperature Harsh Environments." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27762.
Повний текст джерелаАнотація:
Measurement of physical parameters in harsh environments (high pressure, high temperature, highly corrosive, high electromagnetic interference) is often desired in a variety of areas, such as aerospace, automobile, energy, military systems, and industrial processes. Pressure and temperature are among the most important of these parameters. A typical example is pressure monitoring in jet engine compressors to help detect and control undesirable air flow instabilities, namely rotating stall and surge. However, the temperatures inside a compressor could reach beyond 600°C for today's large engines. Current fiber-optic sensor can operate up to about 300°C and even the most widely employed semiconductor sensors are limited below 500°C.
The objective of this research is to push the limit of fiber-optic sensing technology in harsh environment applications for both pressure and temperature measurements by developing novel sensing structures, fabrication techniques, and signal processing algorithms. An all-fused-silica pressure sensor has been demonstrated which is fabricated on the tip of a fiber with a diameter no larger than 125μm. The sensor was able to function beyond the current limit and operate into the 600~700°C range. Also a temperature sensor has been developed using sapphire fibers and wafers for ultra-high temperature measurement as high as 1600°C. This effort will generate more understanding regarding sapphire fiber's high temperature properties and could possibly lead to novel designs of pressure sensor for beyond 1000°C. Both sensors have been field tested in real-world harsh environments and demonstrated to be reliably and robust.
In this dissertation, the design, fabrication, and testing of the sensors are discussed in detail. The system and signal processing techniques are presented. The plan and direction for future work are also suggested with an aim of further pushing the operating limit of fiber-optic sensors.Ph. D.
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Hurley, Paul Raymond. "Application of Optical Fiber Sensors for Quenching Temperature Measurement." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99035.
Повний текст джерелаАнотація:
The critical heat flux (CHF) point for a reactor core system is one of the most important
factors to discuss in regards to reactor safety. If this point is reached, standard coolant
systems are not enough to handle the temperature increase in the cladding, and the likelihood
of meltdown greatly increases. While the nucleate boiling and film boiling regimes have
been well-investigated, the transition boiling regime between the point of departure from
nucleate boiling (DNB) and the minimum film boiling temperature (Tmin) remains difficult
to study. This is due to both the complexity of the phenomena, as well as limitations
in measurement, where experiments typically utilize thermocouples for temperature data
acquisition. As a result of technological advancement in the field of fiber optics, it is possible
to measure the quenching temperature to a much higher degree of precision. Optical fiber
sensors are capable of taking many more measurements along a fuel simulator length than
thermocouples, which are restricted to discrete points. In this way, optical fibers can act
as an almost continuous sensor, calculating data at a resolution of less than one millimeter
where a thermocouple would only be able to measure at one point. In this thesis, the results
of a series of quenching experiments performed on stainless steel, Monel k500, and Inconel
600 rods at atmospheric pressure, with different subcooling levels and surface roughnesses,
will be discussed. The rewetting temperature measurement is performed to compare results
between thermocouples and optical fiber sensors in a 30 cm rod. These results are further
discussed with regard to future application in two-phase flow experiments.Master of Science
There are multiple types of boiling that can occur depending on the heat transfer capabilities of the system and the power applied to the coolant. The most common is nucleate boiling, where vapor produced at the surface forms bubbles and move away from the surface due to buoyancy. At a high enough power, the bubbles can coalesce into a film and lead to a point at which the liquid coolant can no longer contact the surface. Since vapor is not as effective at transferring heat from the surface, the temperature will increase drastically. In nuclear reactors, this situation (known as departure from nucleate boiling), can quickly lead to a meltdown of the fuel rods. Another important safety parameter in nuclear reactors is the minimum temperature at which this vapor film can be maintained, Tmin. This parameter is a source of significant concern with regard to accident scenarios such as LOCA (loss of coolant accident), where reintroducing coolant to the rods efficiently is of top priority. While much research has been done on nucleate and film boiling, it has been difficult to study the transition period between the two regimes due to both its transient nature and the lack of continuous measurement capabilities. Typically, temperature is measured using thermocouples, which are point-source sensors that do not allow for high spatial resolution over a large area. This thesis deals with the utilization of optical fibers for temperature measurement, which are capable of calculating data at every millimeter, potentially a much more precise measurement system than with the thermocouples. The experiments performed in this paper are quenching experiments, where a rod embedded with thermocouples and an optical fiber is heated to well above Tmin and quickly plunged into a volume of water, in order to view the transition from film to nucleate boiling.
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Wang, Zhiyong. "Self-Calibrated Interferometric/Intensity Based Fiber Optic Temperature Sensors." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/9690.
Повний текст джерелаАнотація:
To fulfill the objective of providing robust and reliable fiber optic temperature sensors capable of operating in harsh environments, a novel type of fiber optic sensor system titled self-calibrated interferometric/intensity-based (SCIIB) fiber optic temperature sensor system is presented in this thesis including the detailed research work on the principle analysis, design, modeling, implementation and performance evaluation of the system.
The SCIIB fiber optic temperature sensor system shows us an innovative fiber optic sensor system compared with traditional fiber optic sensors. In addition to the general benefits of the traditional fiber optic sensors, the SCIIB fiber optic sensor system possesses several unique advantages. By taking advantage of the Split-Spectrum technique developed in Photonics Lab at Virginia Tech, the SCIIB sensor technology possesses the capability of Self-Calibration that can fully compensate for the fluctuation of optical source power and the variations of fiber losses. It combines the advantages of both the interferometric-based and the intensity-based fiber optic sensors in a single system. A multimode fiber-based SCIIB temperature sensor system is designed and successfully implemented. Comprehensive experiments are performed to evaluate the principle of SCIIB technology and the performance of the multimode fiber-based SCIIB temperature sensor system. The experiment results illustrate that the development of the SCIIB fiber optic temperature sensor system provides a reliable tool for the temperature measurement capable of operation in high temperature harsh environments.Master of Science
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Trontz, Adam J. "Metal-Ceramic Coaxial Cable Sensors for Distributed Temperature Monitoring." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522165065943505.
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Yoo, Seung-jin. "Micromachined wavelength selective microbolometer sensors operating at room temperature /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004406.
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MOISELLO, ELISABETTA. "Integrated Interface Circuits for MEMS Contact-less Temperature Sensors." Doctoral thesis, Università degli studi di Pavia, 2020. http://hdl.handle.net/11571/1370177.
Повний текст джерелаАнотація:
Thermal sensors, exploiting the relation between the thermal radiation emitted by an object and its temperature, as expressed by the Stefan-Boltzmann law, allow realizing contact-less temperature measurements, required in a wide range of applications, ranging from fever measurements to presence detection for security and climate control systems.
With the advent of smart homes and Internet of Things (IoT) and the wide spreading of mobile and wearable devices, the need for low-cost low-power thermal sensors has arisen, therefore moving the focus of the research away from standard bolometers and pyroelectric detectors and towards uncooled infrared (IR) sensors solutions that can be easily integrated. Bolometers and pyroelectric detectors, which are the main types of thermal sensors found nowadays on the market, in fact, do not comply with the low-cost and easy integration specifications.
Integration of thermal sensors is possible through Micro-Electro Mechanical Systems (MEMS) technology, which allows combining on the same substrate or chip both electrical and mechanical structures with dimensions in the micro-meter range, thus providing structures with high thermal isolation and low thermal mass. The micromachining processes that are required to thermally isolate the sensing element from the substrate are versatile and include anisotropic wet etching, dry and wet etching, electrochemical etch stop, or the use of silicon-on-insulator (SOI).
In this scenario, STMicroelectronics has fabricated two different novel thermal sensors, which fulfill the low-cost low-power specifications for smart homes, IoT and mobile and wearable devices, while also being compatible with CMOS processes and thus easily integrated: a polysilicon thermopile and a micromachined CMOS transistor, from now on referred to as TMOS.
During my Ph.D. activity I was involved in a cooperation between the STMicroelectronics Analog MEMS and Sensors R&D group and the University of Pavia, that led to the design of two readout circuits specifically tailored on the sensors characteristics, one for the thermopile sensor and one for the TMOS (developed by the Technion-Israel Institute of Technology), which were integrated in two test-chip prototypes and thoroughly characterized through measurements as stand-alone devices and as a system with the sensor they were designed for.Thermal sensors, exploiting the relation between the thermal radiation emitted by an object and its temperature, as expressed by the Stefan-Boltzmann law, allow realizing contact-less temperature measurements, required in a wide range of applications, ranging from fever measurements to presence detection for security and climate control systems. With the advent of smart homes and Internet of Things (IoT) and the wide spreading of mobile and wearable devices, the need for low-cost low-power thermal sensors has arisen, therefore moving the focus of the research away from standard bolometers and pyroelectric detectors and towards uncooled infrared (IR) sensors solutions that can be easily integrated. Bolometers and pyroelectric detectors, which are the main types of thermal sensors found nowadays on the market, in fact, do not comply with the low-cost and easy integration specifications. Integration of thermal sensors is possible through Micro-Electro Mechanical Systems (MEMS) technology, which allows combining on the same substrate or chip both electrical and mechanical structures with dimensions in the micro-meter range, thus providing structures with high thermal isolation and low thermal mass. The micromachining processes that are required to thermally isolate the sensing element from the substrate are versatile and include anisotropic wet etching, dry and wet etching, electrochemical etch stop, or the use of silicon-on-insulator (SOI). In this scenario, STMicroelectronics has fabricated two different novel thermal sensors, which fulfill the low-cost low-power specifications for smart homes, IoT and mobile and wearable devices, while also being compatible with CMOS processes and thus easily integrated: a polysilicon thermopile and a micromachined CMOS transistor, from now on referred to as TMOS. During my Ph.D. activity I was involved in a cooperation between the STMicroelectronics Analog MEMS and Sensors R&D group and the University of Pavia, that led to the design of two readout circuits specifically tailored on the sensors characteristics, one for the thermopile sensor and one for the TMOS (developed by the Technion-Israel Institute of Technology), which were integrated in two test-chip prototypes and thoroughly characterized through measurements as stand-alone devices and as a system with the sensor they were designed for.
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Firebaugh, Samara L. "Investigation of materials for use in high-temperature, thin-film heaters and temperature sensors." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43402.
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Weber, Nicole. "Using landscape metrics to assess traffic noise, air pollution and temperature conditions." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17196.
Повний текст джерелаАнотація:
Urbane Räume sind aufgrund ihrer hohen Bevölkerungsdichtes sowie gesellschaftlichen und wirtschaftlichen Bedeutung besonders exponiert gegenüber äußeren Einflüssen und Umweltbelastungen. Sie sind klimatische Ungunsträume, in welchen sich besonders bei starken Hitzeereignissen eine hohe gesundheitliche Belastung entwickelt. Zudem sind Städte durch eine beträchtliche Lärmbelastung und Luftverschmutzung belastet. In der vorliegenden Dissertation wurde eine umweltbezogene Risikoanalyse anhand von Landschaftsstrukturmaßen umgesetzt, in dem Leipziger Stadtstrukturtypen hinsichtlich ihrer Belastung durch Verkehrslärm, Feinstaub und Oberflächentemperaturen untersucht wurden. Die höchsten Belastungen an Lärm und Feinstaub, als auch die höchsten Oberflächen-temperaturen treten in den Wohngebieten auf. Grünflächen und Kleingartenanlagen bilden dagegen Erholungsräume mit geringeren Oberflächentemperaturen und hohen Anteilen gering belasteter Flächen durch Lärm und Feinstaub. Eine gleichzeitige Analyse der vorhandenen Strukturmerkmale, Bebauungshöhe und Anteil an bebauter Fläche, ermöglichte die Betrachtung der Beeinflussung durch bestimmte Baustrukturen und deren Anordnung. Der Einsatz von Landschaftsstrukturmaßen ermöglicht eine kostengünstige und effiziente Analyse von Umweltbelastungen wie Lärm, Feinstaub und Hitze von unterschiedlichen Stadtstrukturtypen. Anhand von Landschaftsstrukturmaßen können die mit Stadtumbau und Neubau einhergehenden Verbesserungen oder Verschlechterungen der Luftschadstoff- und Lärmbelastung sowie Oberflächentemperaturen identifiziert werden.In cause of their high population-density as well as social and economic importance, urban areas are particularly sensitive to external influences and environmental pollution. Under climate change and high noise and air pollution, green spaces, such as parks and urban forests, become increasingly important. The identification of highly polluted areas within the city or its residential districts can be helpful for city planners to proactively plan these areas and create open spaces. Sustainable effects on well-being and human health will be the outcome. The dissertation implemented an environmental risk analysis has been based on the quantitative concept of the landscape metrics. Typical structure types in Leipzig have been analysed for their exposure to traffic noise, air pollution and surface temperatures. The highest exposures of noise and airborne particles, as well as the highest surface temperatures were found in residential areas. In contrast green spaces and allotments form recreation areas with lower surface temperatures and high percentages of low exposured areas of noise and air pollution. A simultaneous analysis of existing structural features, building height and proportion of built area, allowed the consideration of the influence of certain structural conditions. The use of landscape metrics offered a cost-efficient analysis of the structure types and the prevailing exposure of the three environmental stressors. Bases on metrics such as edge and patch density and diversity indicés, land use structure changes going along with improvements or worsening of air and noise pollution as well as surface temperatures can be straightforward identified.
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Barnes, Adam. "Sapphire fiber in optical sensors." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-09052009-041053/.
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Wu, Zhaohui. "Modeling and characterization of high-temperature silicon-based thermal sensors." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31057652.
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Frood, Andrew J. M. "Thick-film Piezoelectric resonant sensors : MEMS and High Temperature Solutions." Thesis, University of Southampton, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505870.
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Chong, N. "Room-temperature GaAs and polysilicon thermal sensors for infrared radiation." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597637.
Повний текст джерелаАнотація:
GaAs was introduced as a thermoelectric material in a micromachined thermal detector. GaAs/Au thermocouples were fabricated on air-bridges with lengths ranging from 40 to 650 μm by anisotropic etching to undercut the GaAs substrate with photoresist patterns delineated by optical lithography. The devices have been characterized with a 10.6 μm CO2 laser. The responsivity and time constant for various lengths were determined in both air and vacuum conditions. The time constants ranging from 50 μs up to 2.2 ms were among the fastest for micromachined thermal detectors; the lower responsitivities were inevitable trade-offs. An analytical thermal transport model of the air-bridges was used to evaluate the device performance and deduce useful physical parameters from the experimental data such as the heat-transfer coefficient. The spectral response in the wavelength band from 1 to 12 μm, measured by using a monochromator, also highlighted the importance of antireflection coatings on the responsivity. To achieve a fast response time without sacrificing the responsivity of the thermal detectors, antenna-coupled designs were considered. A small free-standing element with a short time constant was coupled to an antenna which collected the incoming radiation and provided gain to the self-heating element. Polysilicon air-bridges, instead of metallic ones, were demonstrated for the first time in such a system and provided a practical level of performance which was measured in the linear-polarized CO2 laser system. Log-periodic and bow-tie antenna designs were chosen to facilitate a broadband response in the mid-infrared regime. The devices were able to operate in both thermocouple and bolometer modes both of which exhibited a higher responsivity than previously reported studies. The time constant was kept as short as 4 μs. Measurements made at 10.2μm wavelength indicated that the linearly polarized antennas had an on-axis cross-polarization ratio of about -4.5 dB and the antenna patterns in free-space had a directivity of approximately 5-9 dB. The deduced coupling efficiency was 34%. Measured frequency responses for modulated optical signals also agreed with the thermal transport models.
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Wu, Zhaohui, and 吳朝暉. "Modeling and characterization of high-temperature silicon-based thermal sensors." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31057652.
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Bezombes, Frédéric. "Fibre Bragg grating temperature sensors for high-speed machining applications." Thesis, Liverpool John Moores University, 2004. http://researchonline.ljmu.ac.uk/5630/.
Повний текст джерелаАнотація:
In high-speed grinding research, it is required to measure temperature within the workpiece. Present techniques are thermocouple based, and often suffer from excessive electrical noise on the signal. This thesis presents a number of novel and existing optical sensing devices that overcome this limitation and also, in some cases, offer greater performance. The optical sensors are fibre Bragg grating based and the optical techniques used to interrogate that sensor include DWDM, WDM, athermic grating, tuneable grating and coupler. Optical fibre devices are simpler to place in situ prior to the machining tests and they offer faster response and greater sensitivity than was previously possible. Results are presented from machining tests and the new devices are compared with each other and thermocouple based techniques. A method to relate internal measured temperature to machined surface temperature is also demonstrated in the context of high-speed machining.
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Beech, Alison. "An investigation of novel low-temperature carbon monoxide gas sensors." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/33096.
Повний текст джерелаАнотація:
Carbon monoxide (CO) is a colourless and highly toxic gas. The detection of CO is a key requirement for safety and control in combustion processes. A number of sensors are currently available but all have drawbacks with most if not all having questions raised about their effective detection of CO over other gases such as hydrogen and methane. The power consumption of some methods of gas sensing is high as the active material must be heated to 400.600°C in order to function. The aim of this project was to attempt to eliminate this high power requirement and to study the design, fabrication and testing of CO sensors which function at room temperature, based on a supported platinum electrode in combination with a solid polymer electrolyte. It is therefore conceivable that the power source of such a sensor could be a battery, which could power a microcontroller and the relatively simple diagnostic testing equipment in a final commercial product.
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Chalyy, D., and I. Zhidenko. "Fiber-optical temperature sensors for operation in radiation-hazard conditions." Thesis, XII Міжнародна науково-практична конференція молодих вчених, курсантів та студентів «Проблеми та перспективи розвитку системи безпеки життєдіяльності». – Л., 2017. – С.29, 2017. http://hdl.handle.net/123456789/3978.
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Tonks, Michael James. "Modeling and Testing of Fast Response, Fiber-Optic Temperature Sensors." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/26075.
Повний текст джерелаАнотація:
The objective of this work was to design, analyze and test a fast response fiber-optic temperature probe and sensor. The sensor is intended for measuring rapid temperature changes such as produced by a blast wave formed by a detonation. This work was performed in coordination with Luna Innovations Incorporated, and the design is based on extensions of an existing fiber-optic temperature sensor developed by Luna. The sensor consists of a glass fiber with an optical wafer attached to the tip. A basic description of the principles behind the fiber-optic temperature sensor and an accompanying demodulation system is provided.
For experimental validation tests, shock tubes were used to simulate the blast wave experienced at a distance of 3.0 m from the detonation of 22.7 kg of TNT. The flow conditions were predicted using idealized shock tube theory. The temperature sensors were tested in three configurations, flush at the end of the shock tube, extended on a probe 2.54 cm into the flow and extended on a probe 12.7 cm into the flow. The total temperature was expected to change from 300 K to 1130 K for the flush wall experiments and from 300 K to 960 K for the probe experiments. During the initial 0.1 milliseconds of the data the temperature only changed 8 K when the sensors were flush in the end of the shock tube. The sensor temperature changed 36 K during the same time when mounted on a probe in the flow. Schlieren pictures were taken of the flow in the shock tube to further understand the shock tube environment. Contrary to ideal shock tube theory, it was discovered that the flow did not remain stagnant in the end of the shock tube after the shock reflects from the end of the shock tube. Instead, the effects of turbulence were recorded with the fiber-optic sensors, and this turbulence was also captured in the schlieren photographs. A fast-response thermocouple was used to collect data for comparison with the fiber-optic sensor, and the fiber-optic sensor was proven to have a faster response time compared to the thermocouple. When the sensors were extended 12.7 cm into the flow, the fiber-optic sensors recorded a temperature change of 143 K compared to 38 K recorded by the thermocouple during the 0.5 millisecond test. This corresponds to 22% of the change of total temperature in the air recorded by the fiber-optic sensor and only 6% recorded by the thermocouple. Put another way, the fiber-optic sensor experience a rate of temperature change equal to 2.9x105 K/s and the thermocouple changed at a rate of 0.79x105 K/s. The data recorded from the fiber-optic sensor also contained much less noise than the thermocouple data.
An unsteady finite element thermal model was created using ANSYS to predict the temperature response of the sensor. Test cases with known analytical solutions were used to verify the ANSYS modeling procedures. The shock tube flow environment was also modeled with Fluent, a commercially available CFD code. Fluent was used to determine the heat transfer between the shock tube flow and the sensor. The convection film coefficient for the flow was predicted by Fluent to be 27,150 W/m2K for the front of the wafer and 13,385 W/m2K for the side. The Fluent results were used with the ANSYS model to predict the response of the fiber-optic sensor when exposed to the shock tube flow. The results from the Fluent/ANSYS model were compared to the fiber-optic measurements taken in the shock tube. It was seen that the heat flux to the sensor was slightly over-predicted by the model, and the heat losses from the wafer were also over-predicted. Since the prediction fell within the uncertainty of the measurement, it was found to be in good agreement with the measured values.
Inverse heat transfer methods were used to determine the total temperature of the flow from the measured data. Both the total temperature and the film coefficient were determined simultaneously during this process. It was found that for short testing times, there were many possible solutions. In order to obtain ultimate success with this method, the uncertainty of the demodulation system must be improved and/or the simple analytical thermal model used to predict the response of the sensor needs to match the physical sensor. Whenever possible, longer testing times should be employed. Promising suggestions for extending this approach are provided.Ph. D.
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Zhang, Yibing. "Novel Optical Sensors for High Temperature Measurement in Harsh Environments." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/28392.
Повний текст джерелаАнотація:
Accurate measurement of temperature is essential for the safe and efficient operation and control of a vast range of industrial processes. Many of these processes involve harsh environments, such as high temperature, high pressure, chemical corrosion, toxicity, strong electromagnetic interference, and high-energy radiation exposure. These extreme physical conditions often prevent conventional temperature sensors from being used or make them difficult to use. Novel sensor systems should not only provide accurate and reliable temperature measurements, but also survive the harsh environments through proper fabrication material selections and mechanical structure designs.
This dissertation presents detailed research work on the design, modeling, implementation, analysis, and performance evaluation of novel optical high temperature sensors suitable for harsh environment applications. For the first time to our knowledge, an optical temperature sensor based on the broadband polarimetric differential interferometric (BPDI) technology is proposed and tested using single crystal sapphire material. With a simple mechanically structured sensing probe, in conjunction with an optical spectrum-coded interferometric signal processing technique, the proposed single crystal sapphire optical sensor can measure high temperature up to 1600 oC in the harsh environments with high accuracy, corrosion resistance, and long-term measurement stability. Based on the successfully demonstrated sensor prototype in the laboratory, we are confident of the next research step on sensor optimization and scale-up for full field implementations. The goal for this research has been to bring this temperature sensor to a level where it will become commercially viable for harsh environment applications associated with industries.Ph. D.
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Twedt, Jason Christopher. "Fiber-Optics Based Pressure and Temperature Sensors for Harsh Environments." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/42782.
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Monitoring accurate temperature and pressure profiles in harsh environments is currently in high demand in aerospace gas turbine engines and nuclear reactor simulators. Having the ability to measure both quantities continuously over a region, without thermal coupling, using a sensor with a small size (envelope) is also highly desirable. Currently available MEMS (microelectromechanical systems) provide effective small scale pressure and temperature measurement devices, however, they have only been shown to be effective up to 600C and lack the ability to perform distributed measurements unless combined with fiber-optic techniques. In general, fiber-optics provide many advantages over electrical based sensors and are the ideal choice for high temperature regimes and distributed sensing. In this thesis, preliminary designs and suggested future work are presented for a sensor built within an 3.175 mm radius envelope and capable of distributed pressure and temperature sensing up to temperatures reaching 800C. Finite element analysis via ANSYS, along with analytical verification models have been used for the design evolution. Diaphragm based designs, seem to provide easy fabrication methods and good sensitivity, however, for this design to be realized at high temperature operation, a robust bonding method must be chosen to avoid unwanted deformation due to misfit strains.Master of Science
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Crenshaw, Brent R. "PHOTOLUMINESCENT POLYMER MATERIALS WITH BUILT-IN DEFORMATION AND TEMPERATURE SENSORS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1169825895.
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Abeysinghe, Don Chandana. "Novel MEMS Pressure and Temperature Sensors Fabricated on Optical Fibers." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997987327.
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Patil, Amita C. "Silicon Carbide JFET Integrated Circuit Technology for High-Temperature Sensors." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238786695.
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KRIK, Soufiane. "Low-operating temperature chemiresistive gas sensors: Fabrication and DFT calculations." Doctoral thesis, Università degli studi di Ferrara, 2021. http://hdl.handle.net/11392/2488099.
Повний текст джерелаАнотація:
Despite advantages highlighted by Metal OXides (MOX) based gas sensors, these devices still present drawbacks in their performances (e.g. selectivity, stability and high operating temperature), so further investigations are necessary. Researchers tried to address these problems in several ways, which includes new synthesis methods for innovative materials based on MOX, such as solid solutions, addition of catalysts and doping of MOX by using external atoms or oxygen vacancies. Concerning this last issue, literature presents a lack of studies on how the arrangement and number of oxygen vacancies affect the sensing performance and only a few preliminary works highlighted interesting results. Another way to overcome MOX sensor drawbacks is to investigate novel class of materials, such as metal organic framework or 2D materials. Among these, phosphorene is one of the best candidates for such technological application, since it shows a chemoresistive activity at room temperature.
The goal of this work is to decrease the operating temperature of SnO2 based gas sensors by exploiting the oxygen vacancies. First, a theoretical investigation was done in the framework of Density Functional Theory (DFT) to investigate, on the atomic scale, how oxygen vacancies influence the physical and chemical properties of the material. The effect of oxygen vacancies on the structural, electronic and electrical properties of bulk SnO2 at two different concentrations was studied, then the formation of surface oxygen vacancies was investigated in order to study the adsorption of oxygen molecules from the surrounding atmosphere on the stoichiometric and reduced SnO2 surface. Then, reduced SnO2-x was synthesized and devices based on the produced material were fabricated and tested. The results showed a high response of the sensors towards low concentrations of nitrogen dioxide NO2 (500 ppb) at 130°C instead of the typical operating temperature of 450°C for SnO2-based gas sensors. This decrease in the operating temperature results in a decrease of the power consumption of the device, opening up to its possible employment on portable devices like mobile phones. The results were interpreted characterizing the material by mean of X-ray Powder Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM) and Ultraviolet–visible spectroscopy (UV-visible) analysis. In the end, the experimental results were compared to the DFT outputs obtained.
As mentioned before, phosphorene is one of the promising 2D materials for gas sensing applications, but it still presents some drawbacks, mainly due to the material degradation over the time when exposed to ambient conditions. Many investigations were done on decorating phosphorene with metal atoms in order to enhance its performance for different technological applications. Nickel is one of metals proposed for such purpose, but few studies were done on nickel decorated phosphorene for gas sensing applications, especially for gas sensing application. In the innovative work here proposed, DFT calculations were carried out to explain how nickel influences the electronic properties of phosphorene since the decoration with nickel showed better stability of the sensor and high response towards NO2 at room temperature. The theoretical results explained this behavior by studying the adsorption of oxygen molecules on pristine and nickel loaded phosphorene. The DFT calculations showed that oxygen molecules dissociate on the layer of pristine phosphorene and react with phosphorus atoms (oxidation of the material), while in the presence of the nickel atoms the later play the role of acceptors and interact with the oxygen molecules. Finally, the sensing mechanism towards NO2 was investigated theoretically by studying the charge transfer occurring at the surface of the material during the adsorption process.I sensori di gas basati sugli ossidi metallici semiconduttori (MOX) si sono rivelati negli ultimi anni una tecnologia estremamente vantaggiosa. Nonostante i progressi fatti in questo campo, questi dispositivi presentano ancora alcuni punti deboliche spingono la ricerca ad effettuare ulteriori indagini per perfezionare il loro funzionamento. I ricercatori hanno cercato di risolvere questi svantaggi in diversi modi, focalizzandosi sullo sviluppo di MOX innovativi, tra cui il drogaggio tramite l’utilizzo di additivi o l’introduzione nel materiale di vacanze di ossigeno a concentrazione controllata. Questa’alternativa sta attirando l’attenzione di molti gruppi di ricerca, anche se, ad oggi, la letteratura scientifica presenta una mancanza di studi su come la disposizione e concentrazione di vacanze di ossigeno influenzano le performance di sensing e solo alcuni lavori preliminari hanno portato a risultati interessanti. Per cercare di ovviare ai limiti dei sensori MOX, una seconda via è stata lo sviluppo e di materiali 2D basati su solfuri metallici, grafene o similari. Il fosforene è uno dei migliori candidati per tale applicazione tecnologica, poiché mostra un'attività elettrica anche a temperatura ambiente, anche se studi preliminari hanno evidenziato un alto tasso di degradazione nel tempo del materiale durante il suo utilizzo. L'obiettivo di questo lavoro è quello di diminuire la temperatura di funzionamento di sensori di gas basati su SnO2 sfruttando il controllo delle vacanze di ossigeno. A tale scopo, è stato fatto inizialmente uno studio della letteratura e un’analisi analitica nell’ambito della DFT per indagare come le vacanze di ossigeno influenzano le proprietà fisico-chimiche del materiale. È stato studiato l'effetto di due diverse concentrazioni di vacanze di ossigeno sulle proprietà chimico-fisiche dello SnO2 bulk. Successivamente è stata studiata la formazione della vacanze in superficie per investigare l'adsorbimento di molecole di ossigeno dall'atmosfera circostante sulla superficie dello SnO2 è stato sintetizzato tramite sintesi sol-gel e la riduzione è stata ottenuta tramite trattamento termico in presenza di H2 a diverse temperature. I risultati hanno mostrato un'alta risposta dei sensori basati su SnO2-x in presenza di basse concentrazioni di NO2 spostando a 130 °C la temperatura ottimale di funzionamento del dispositivo. Questa diminuzione della temperatura operativa implica una diminuzione del consumo energetico del dispositivo Come menzionato precedentemente, il fosforene è uno dei materiali 2D più promettenti per lo sviluppo di sensori di gas chemoresistivi, ma presenta ancora alcuni svantaggi. Molti studi sono stati sviluppati sulla decorazione del fosforene con atomi metallici al fine di migliorare le sue prestazioni per diverse applicazioni tecnologiche, ma non sono stati ancora condotti studi specifici su questa particolare forma di fosforene decorato per applicazioni di sensoristica gassosa. Nello studio qui proposto, sono stati eseguiti calcoli DFT per spiegare come il nichel influenzi le proprietà elettroniche del fosforene, poiché la decorazione con nichel ha mostrato una migliore stabilità del sensore e un’alta sensibilità all’NO2. Tramite simulazione DFT è stato possibile investigare l'adsorbimento delle molecole di ossigeno sul Fosforene tal quale e decorato con nichel. I risultati hanno evidenziato che le molecole di ossigeno si dissociano sullo strato di fosforene tal quale e reagiscono con gli atomi di fosforo, ossidandolo, mentre in presenza dei cluster di nichel è quest’ultimo a svolgere il ruolo di catalizzatore, interagendo con le molecole di ossigeno. Infine, il meccanismo di interazione tra NO2 e la superficie del fosforene tal quale e funzionalizzato è stato caratterizzato teoricamente studiando il trasferimento di carica che avviene sulla superficie del materiale in esame.
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Khalil, Nahla Mahmood. "Novel optoelectronic temperature sensor having application in the biomedical field." Thesis, City University London, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328417.
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