| 1. |
- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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Gas sensor arrays for combustion control
- 2005
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Ingår i: Encyclopedia of Sensors, eds.. - California : American Scientific Publishers. - 158883056X ; , s. 139-154
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The applications of sensors range from medical diagnostics to industrial manufacturing and to defense and national security applications. When an area spans such a large diversity of research, and where research from many different countries is also involved, a review of these developments becomes especially useful. Because it bridges science and technology the field also provides a desired interaction between researchers and research in technologically advanced and developing countries. The present series of volumes, "The Encyclopedia of Sensors" , the first of its kind, is intended to provide a timely compendium of the entire field. As such it can be expected to play a significant role in worldwide future progress and understanding."
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| 2. |
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| 3. |
- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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MISiC-FET NH3 sensors for SCR control in exhaust and flue gases
- 2005
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Ingår i: Encyclopedia of Sensors, eds.. - California : American Scientific Publishers. - 158883056X ; , s. 205-218
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The applications of sensors range from medical diagnostics to industrial manufacturing and to defense and national security applications. When an area spans such a large diversity of research, and where research from many different countries is also involved, a review of these developments becomes especially useful. Because it bridges science and technology the field also provides a desired interaction between researchers and research in technologically advanced and developing countries. The present series of volumes, "The Encyclopedia of Sensors" , the first of its kind, is intended to provide a timely compendium of the entire field. As such it can be expected to play a significant role in worldwide future progress and understanding."
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| 4. |
- Nakagomi, Shinji, et al.
(författare)
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Influence of gate bias of MISiC-FET gas sensor device on the sensing properties
- 2005
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 108, s. 501-507
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Tidskriftsartikel (refereegranskat)abstract
- The influence of gate bias on the gas sensing properties of SiC-based field effect transistors with catalytic gate and a buried short channel has been studied. The drain current-voltage (I-d-V-D) characteristics of the device reveal non-saturation property, which is a consequence of the short channel design. The drain current is larger in hydrogen ambient than in oxygen ambient at the same drain voltage. The threshold voltage decreases with increasing positive gate bias, and increases with increasing negative gate bias. When a positive bias is applied to the gate, the I-d-V-D characteristics reveal a tendency to saturate. A positive gate bias increases the drain voltage response to hydrogen, as compared with a negative applied gate bias. However, a positive gate bias decreases the stability of the device signal. A change in the channel resistivity is the main reason for the change in the electrical properties when a positive gate bias is applied. A physical model that explains the influence of the gate bias has been studied, and the behavior of the barrier height in the channel was estimated by using the temperature dependence of the I-d-V-D characteristics.
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| 5. |
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| 6. |
- Andersson, Mike, 1977-, et al.
(författare)
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Detecting non-hydrogen containing species with field effect devices
- 2008
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Ingår i: IEEE Sensors,2008. - : IEEE. - 9781424425815 - 9781424425808 ; , s. 1320-1323
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Konferensbidrag (refereegranskat)abstract
- An investigation of the influence and role of oxygen in the detection of non-hydrogen containing substances with Pt/SiO2/SiC based MOS field effect sensors, employing new model systems, has been carried out. With the use of a novel intermediate layer, by which the direct influence of hydrogen on the sensor response can be markedly reduced, the part of the sensor response which is not directly related to hydrogen (which to a small extent is always present in any gas mixture) could be resolved. The Pt/SiO2 NO reduction/oxidation model system has also been studied from a sensor perspective and the results compared to spectroscopic and mass spectrometry studies of the surface reactions from the field of catalysis. The results support the hypothesis from earlier work that the removal of oxygen from the sensor surface (e.g. by oxidation reactions with CO or NO) to a certain extent directly is involved in the detection of non-hydrogen containing species.
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| 7. |
- Andersson, Mike, 1977-
(författare)
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Development and characterization of SiC based field effect gas sensors and sensor systems for emissions monitoring and control of biomass combustion
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Increasing oil prices and environmental levies have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets in water based heating systems. The combustion process itself proceeds through three elementarysteps; drying, where fuel moisture is driven off, followed by pyrolysis and finally combustion of the remaining charcoal. Given the sufficient amount of air, good mixing and long enough residence time at elevated temperatures, the short-chained hydrocarbons and carbon monoxide formed during pyrolysis andchar combustion will burn to completion leaving only CO2 and H2O in the flue gases.In case of air deficiency, combustion will be incomplete, leaving noxious compounds, like certain hydrocarbons and CO, behind. Too much of excess air, on the other hand, will lower the temperature of the combustion chamber, giving rise to both emissions of unburned material and, due to the forcedconvection of heat out the chimney, an impaired boiler efficiency. The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the airflows during combustion. The amount of air needed for complete oxidation of the fuel varies with the phase of combustion, fuel, fuel quality and load, however, why an active control of the airflows is considered a prerequisite. So far, nocontrol schemes have been applied to small- and medium-sized combustors, though, mainly dependent on the lack of cheap and simple means to measure basic flue gas parameters, like oxygen, hydrocarbons and CO.Here is reported about the possible use of a system comprising SiC based field effect sensors to monitor the state of combustion, applicable to domestic heating systems, where only a rough picture of the air to fuel relationship is needed. Furthermore, it has been shown possible to obtain a multivariate linear regression model for propene (a model hydrocarbon) by the application of an array of SiC field effect sensors in a varying background of typical flue gas constituents, as long as thevariation is not too large. This model could possibly be applied to a control scheme for medium sized boilers, where smaller variations of flue gas constituents are encountered, and the possibility of simultaneous ammonia estimations has also opened up the field of flue gas after-treatment controlapplications, monitoring ammonia slip from selective noncatalytic reduction of nitrogen oxides by ammonia. The quantitative estimation of hydrocarbons over a wider range of concentrations and backgrounds, as well as of minor flue gasspecies, NO and CO, is however not possible with the SiC sensors currently comprising the sensor system.
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| 8. |
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| 9. |
- Andersson, Mike, 1977-, et al.
(författare)
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In situ DRIFT study of the CO response mechanism of MISFET sensors using Pt/SiO2 model sensor
- 2008
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Ingår i: Proceedings of IEEE Sensors. - : IEEE. - 9781424425815 - 9781424425808 ; , s. 1309-1312
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Konferensbidrag (refereegranskat)abstract
- The temperature dependence of the sensor response towards CO of SiC-FET sensors has been studied by combining in situ DRIFT spectroscopy and sensor response measurements. The DRIFT spectroscopy studies have been performed on a model sensor representing the top layer of a SiC-FET sensor with porous Pt gate. Adsorbates on the model sensor have been studied at varying temperatures and gas concentrations, and correlated to sensor response measurements at similar experimental conditions. The results show that the temperature dependence partly can be correlated to the CO coverage of the surface. The switching point of the sensor response, observed at different temperatures depending on the CO and oxygen concentrations is well in accordance with the kinetics of the CO oxidation reaction.
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| 10. |
- Andersson, Mike, 1977-, et al.
(författare)
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Recent progress in silicon carbide field effect gas sensors
- 2020. - 2
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Ingår i: Semiconductor gas sensors. - Oxford : Woodhead Publishing Limited. - 9780081025598 ; , s. 309-346
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Bokkapitel (refereegranskat)abstract
- The introduction of silicon carbide as the semiconductor in gas-sensitive field effect devices has disruptively improved this sensor platform extending the operation temperature to more than 600 °C with an increased number of detectable gases. Here, we review recent progress in research and applications, starting with transducer and detection mechanisms, presenting new material combinations as sensing layers for improved selectivity and detection limits down to subparts per billion. We describe how temperature cycled operation combined with advanced data evaluation enables one sensor to act as a sensor array thereby vastly improving selectivity. Field tests require advanced packaging, which is described, and examples of possible applications like selective detection of ammonia for urea injection control in diesel exhausts and toxic volatile organic compounds for indoor air quality monitoring and control are given.
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| 11. |
- Andersson, Mike, 1977-
(författare)
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SiC based field effect sensors and sensor systems for combustion control applications
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Increasing oil prices and concerns about global warming have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets. Combustion at non-optimal conditions can, however, lead to substantial emissions of noxious compounds like unburned hydrocarbons, carbon monoxide, and nitrogen oxides as well as the generation of soot.Depending on the rate of combustion more or less air is needed per unit time to completely oxidize the fuel; deficiency of air leading to emissions of unburned matter and too much of excess air to slow combustion kinetics and emissions of mainly carbon monoxide. The rate of combustion is influenced by parameters like fuel quality – moisture and ash content etc. – and in what phase the combustion takes place (in the gas phase through combustion of evaporated substances or on the surface of char coal particles), none of which is constant over time.The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the air supply throughout the combustion process. So far, no control schemes have been applied to small-scale combustors, though, mainly due to the lack of cheap and simple means to measure basic flue gas parameters like oxygen, total hydrocarbon, and carbon monoxide concentrations.This thesis reports about investigations on and characterization of silicon carbide (SiC) based Metal Insulator Semiconductor (MIS) field effect gas sensors regarding their utility in emissions monitoring and combustion control applications as well as the final development of a sensor based control system for wood fired domestic heating systems.From the main sensitivity profiles of such sensor devices, with platinum (Pt) and iridium (Ir) as the catalytic metal contacts (providing the gas sensing ability), towards some typical flue gas constituents as well as ammonia (NH3), a system comprising four individual sensors operated at different temperatures was developed, which through the application of Partial Least Squares (PLS) regression, showed good performance regarding simultaneous monitoring of propene (a model hydrocarbon) and ammonia concentrations in synthetic flue gases of varying content. The sensitivity to CO was, however, negligible. The sensor system also performed well regarding ammonia slip monitoring when tested in real flue gases in a 5.6 MW boiler running SNCR (Selective Non-Catalytic reduction of nitrogen oxides with ammonia).When applied to a 200 kW wood pellet fuelled boiler a similar sensor system was, however, not able to follow the flue gas hydrocarbon concentration in all encountered situations. A PCA (Principal Components Analysis) based scheme for the manipulation of sensor and flue gas temperature data, enabling monitoring of the state of combustion (deficiency or too much of excess air), was however possible to develop. The discrepancy between laboratory and field test results was suspected and later on shown to depend on the larger variation in CO and oxygen concentrations in the flue gases as compared to the laboratory tests.Detailed studies of the CO response characteristics for Pt gate MISiC sensors revealed a highly non-linear sensitivity towards CO, a large response only encountered at high CO/O2 ratios or low temperatures. The response exhibits a sharp switch between a small and a large value when crossing a certain CO/O2 ratio at constant operating temperature, correlated to the transition from an oxygen dominated to an almost fully CO covered Pt surface, originating from the difference in adsorption kinetics between CO and O2. Indications were also given pointing towards an increased sensitivity to background hydrogen as being the mediator of at least part of the CO response. Some general characteristics regarding the response mechanism of field effect sensors with differently structured metal contacts were also indicated.The CO response mechanism of Pt metal MISiC sensors could also be utilized in developing a combustion control system based on two sensors and a thermocouple, which when tested in a 40 kW wood fired boiler exhibited a good performance for fuels with extremely low to normal moisture content, substantially decreasing emissions of unburned matter.
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| 12. |
- Bastuck, Manuel, 1990-
(författare)
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Improving the Performance of Gas Sensor Systems with Advanced Data Evaluation, Operation, and Calibration Methods
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In order to facilitate the widespread use of gas sensors, some challenges must still be overcome. Many of those are related to the reliable quantification of ultra-low concentrations of specific compounds in a background of other gases. This thesis focuses on three important items in the measurement chain: sensor material and operating modes, evaluation of the resulting data, and test gas generation for efficient sensor calibration.New operating modes and materials for gas-sensitive field-effect transistors have been investigated. Tungsten trioxide as gate oxide can improve the selectivity to hazardous volatile organic compounds like naphthalene even in a strong and variable ethanol background. The influence of gate bias and ultraviolet light has been studied with respect to the transport of oxygen anions on the sensor surface and was used to improve classification and quantification of different gases.DAV3E, an internationally recognized MATLAB-based toolbox for the evaluation of cyclic sensor data, has been developed and published as opensource. It provides a user-friendly graphical interface and specially tailored algorithms from multivariate statistics.The laboratory tests conducted during this project have been extended with an interlaboratory study and a field test, both yielding valuable insights for future, more complex sensor calibration. A novel, efficient calibration approach has been proposed and evaluated with ten different gas sensor systems.
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| 13. |
- Bastuck, Manuel, et al.
(författare)
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Low-cost chemical gas sensors for selective formaldehyde quantification at ppb-level in field tests
- 2017
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Konferensbidrag (refereegranskat)abstract
- Data from a silicon carbide based field-effect transistor were recorded over a period of nine days in a ventilated school room. For enhanced sensitivity and selectivity especially to formaldehyde, porous iridium on pulsed laser deposited tungsten trioxide was used as sensitive layer, in combination with temperature cycled operation and subsequent multivariate data processing techniques. The sensor signal was compared to reference measurements for formaldehyde concentration, CO2 concentration, temperature, and relative humidity. The results show a distinct pattern for the reference formaldehyde concentration, arising from the day/night cycle. Taking this into account, the projections of both principal component analysis and partial least squares regression lead to almost the same result concerning correlation to the reference. The sensor shows cross-sensitivity to an unidentified component of human activity, presumably breath, and, possibly, to other compounds appearing together with formaldehyde in indoor air. Nevertheless, the sensor is able to detect and partially quantify formaldehyde below 40 ppb with a correlation to the reference of 0.48 and negligible interference from ambient temperature or relative humidity.
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| 14. |
- Bastuck, Manuel, et al.
(författare)
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UV-assisted gate bias cycling in gas-sensitive field-effect transistors
- 2018
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Ingår i: Proceedings. - Basel Switzerland : MDPI. - 2504-3900. ; 2:13
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Tidskriftsartikel (refereegranskat)abstract
- Static and dynamic responses of a silicon carbide field-effect transistor gas sensor have been investigated at two different gate biases in several test gases. Especially the dynamic effects are gas dependent and can be used for gas identification. The addition of ultraviolet light reduces internal electrical relaxation effects, but also introduces new, temperature-dependent effects.
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| 15. |
- Erdtman, Edvin, 1981-, et al.
(författare)
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Simulations of the thermodynamics and kinetics of NH3 at the RuO2 (110) surface
- 2017
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Ingår i: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 656, s. 77-85
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Tidskriftsartikel (refereegranskat)abstract
- Ruthenium(IV)oxide (RuO2) is a material used for various purposes. It acts as a catalytic agent in several reactions, for example oxidation of carbon monoxide. Furthermore, it is used as gate material in gas sensors. In this work theoretical and computational studies were made on adsorbed molecules on RuO2 (110) surface, in order to follow the chemistry on the molecular level. Density functional theory calculations of the reactions on the surface have been performed. The calculated reaction and activation energies have been used as input for thermodynamic and kinetics calculations. A surface phase diagram was calculated, presenting the equilibrium composition of the surface at different temperature and gas compositions. The kinetics results are in line with the experimental studies of gas sensors, where water has been produced on the surface, and hydrogen is found at the surface which is responsible for the sensor response.
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| 16. |
- Kashiwaya, Shun, et al.
(författare)
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Synthesis of goldene comprising single-atom layer gold
- 2024
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Ingår i: Nature Synthesis. - : Nature Publishing Group. - 2731-0582.
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of monolayer gold has so far been limited to free-standingseveral-atoms-thick layers, or monolayers confned on or inside templates.Here we report the exfoliation of single-atom-thick gold achieved throughwet-chemically etching away Ti3C2 from nanolaminated Ti3AuC2, initiallyformed by substituting Si in Ti3SiC2 with Au. Ti3SiC2 is a renown MAX phase,where M is a transition metal, A is a group A element, and X is C or N. Ourdeveloped synthetic route is by a facile, scalable and hydrofuoric acid-freemethod. The two-dimensional layers are termed goldene. Goldene layerswith roughly 9% lattice contraction compared to bulk gold are observedby electron microscopy. While ab initio molecular dynamics simulationsshow that two-dimensional goldene is inherently stable, experiments showsome curling and agglomeration, which can be mitigated by surfactants.X-ray photoelectron spectroscopy reveals an Au 4f binding energy increaseof 0.88 eV. Prospects for preparing goldene from other non-van der WaalsAu-intercalated phases, including developing etching schemes,are presented.
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| 17. |
- Khajavizadeh, Lida, 1978-
(författare)
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Materials Design for the Improvement of SiC Field Effect Gas Sensor performance in High Temperature Process Control applications
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Following growing concerns about the effect these last decades of accelerating energy consumption, escalating use of natural (not the least fossil) resources, and waste generation has had on earth’s climate, human health, and the environment, industry is facing mounting pressure to increase the energy-, resource-, and cost-efficiency of both processes and products while drastically reducing pollutant emissions. In response, industry is, besides increasing their utilization of renewable energy and introducing new bio-based products, taking advantage of the rapid development in 5G technology and associated wireless interconnectivity to move towards full automation of production processes and facilities. With the ability to connect and collect information from a large number of instruments and process steps as well as to analyse huge amounts of multi-dimensional data, entire production lines can be automatically controlled and/or adapted, e.g., through the application of machine learning, for optimized efficiency and minimized greenhouse gas and pollutant emissions. In order to fully benefit from this so-called 4th industrial revolution and the Industrial Internet of Things (IIoT), however, access to cost-efficient and long-term reliable means for measuring various process parameters in multiple locations is required.The basis for this thesis is therefore the characterization of silicon carbide-based Metal Oxide Semiconductor Field Effect Transistor (MOSFET) gas sensors for their applicability in real-time monitoring of process gases/ gas mixtures and pollutant emissions in high-temperature applications, e.g., control of flue gas/ exhaust after-treatment systems, as well as investigations performed to gain a better understanding of the corresponding sensing mechanisms and to improve sensor performance in terms of e.g., long-term reliability.Besides demonstrating the general applicability of SiC MOSFET gas sensors in ammonia (NH3) slip detection and control of Selective Catalytic Reduction and similar flue gas/ exhaust emissions abatement systems to minimize the release of nitrogen oxides into the atmosphere from the energy production and transport sectors, sensors for the selective monitoring of nitrogen oxides with negligible interference from (sensitivity/ cross-sensitivity to) ammonia have been developed. Through variation of the gold/ iridium composition of the MOSFET gate contact, the interaction of which with gaseous substances in the ambient determines the sensor signal, sensors selective to ammonia and nitrogen oxides (NOx; NO and NO2), respectively, could be developed. Furthermore, as both sensor-types exhibit decent sensitivity to the respective substance over a common temperature interval, the realization of simultaneous NH3 and NOx monitoring with one and the same sensor probe would be facilitated. In relating the sensor response under different conditions to the composition and micro- (/nano-) structure of the gate contact material another piece in the puzzle towards an understanding of the ammonia sensing mechanism of field effect sensor devices could also be obtained.Through the investigation of co-deposited platinum group metals/ metal oxides in different ratios it was also shown possible to improve the long-term stability of carbon monoxide (CO) sensors intended for emissions monitoring and combustion control in industrial processes. Both the materials composition and structure were thereby evaluated and their effect on other important sensor parameters, e.g., sensitivity and temperature dependence, analysed. To further improve sensitivity and selectivity of CO as well as NH3 sensors for combustion control and ammonia slip monitoring applications, respectively, the sensor characteristics were also studied under different ambient conditions, e.g., variations in oxygen concentration, and related to the microstructure of the deposited gate materials. From the simultaneous tuning of film structure and operating temperatures, the selectivity could be enhanced for both the CO and NH3 sensors.In summary, the obtained research results from this thesis work have contributed to a further understanding of the sensing mechanisms of silicon carbide-based MOSFET sensors for CO, NOx, and NH3 monitoring and through the tuning of materials properties and sensor operation parameters generated improvements in sensor reliability, sensitivity, and selectivity of importance to the further realization of sensors for process control and emissions reduction applications.
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| 18. |
- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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Multisensing by Gas Sensors
- 2006
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Ingår i: Proceedings Eurosensors XX.
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Konferensbidrag (refereegranskat)
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| 19. |
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| 20. |
- Nåbo, Arne, 1958-, et al.
(författare)
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Regeringsuppdrag om elektrifieringen av transporter : rekommendationer för att underlätta datadelning och nyttiggörande av data för planering, utveckling och drift av laddinfrastruktur och affärsmodeller
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Regeringen har uppdragit åt Statens väg- och transportforskningsinstitut (VTI) att ”bidra till kunskapsuppbyggnaden kring en snabb, smart och samhällsekonomiskt effektiv elektrifiering av transportsektorn”. Den här rapporten redovisar den del av uppdraget som handlar om att genomföra pilotprojekt och ta fram modeller för hur data i praktiken på bästa sätt kan tillgängliggöras, delas och nyttiggöras för att optimera planering, utveckling, drift samt affärsmodeller för laddinfrastruktur. I rapporten ges en beskrivning av förekommande tekniker för laddning av elfordon, viktiga användarperspektiv, och hur affärsmodeller och system för laddinfrastruktur kan modelleras. Rapporten fokuserar på datadelning och beskriver hur aktörer idag delar data samt vilka svårigheter de ser med datadelning. Detta omfattar bland annat datatillgänglighet, delning och nyttiggörande, samt hur aktörerna vill att det ska fungera framåt. En stor utmaning handlar om datatillgänglighet, där aktörer dels ser problem med att få tillgång till data och dels är avvaktande till att vilja dela med sig av egna data. Ofta handlar det om integritetsfrågor och reglering enligt GDPR. Betydelsen av en väl fungerande samverkan mellan energi- och transportsektorn har lyfts i tidigare rapporteringar från det här uppdraget. Vikten av en digitalisering och digital infrastruktur som kopplar samman dessa sektorer betonas speciellt i detta arbete. Digitalisering behövs för att effektivisera planering, utveckling och drift av den infrastruktur som ett elektrifierat transportsystem kräver. De modelleringar som gjorts i den här delen av uppdraget handlar om transportmodellering och energimodellering samt utveckling för att få modellerna att samspela.
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| 21. |
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