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Sökning: WFRF:(Andersson Mike)

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1.
  • Adams, Mike, et al. (författare)
  • Commercial banking, insurance and economic growth in Sweden between 1830 and 1998
  • 2009
  • Ingår i: Accounting Business and Financial History. - : Taylor & Francis. - 0958-5206 .- 1466-4275. ; 19:1, s. 21-39
  • Tidskriftsartikel (refereegranskat)abstract
    • We examine empirically the dynamic historical relation between commercial bank lending, insurance and economic (income) growth in Sweden using time-series data from 1830 to 1998 and performing tests for Granger causality. Because of the non-stationary nature of the time series examined the procedure of Toda andYamamoto (1995) is used. Our results, which have accounted for possible regime changes due to different exchange rate mechanisms over time, indicate that insurance has Granger-caused economic growth and bank lending. Therefore, we conclude that insurance is an important prerequisite for stimulating economic growth and that this could have important implications for contemporary developing economies.
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3.
  • Abrahamsson, Mats, 1960-, et al. (författare)
  • Inside the Core : Managing risks in Business Critical Outsourcing
  • 2011
  • Ingår i: Proceedings of the 20th Annual IPSERA Conference, Vision 20/20 – Preparing Today for Tomorrow’s Challenges. - 9789461780010 ; , s. 1092-1101
  • Konferensbidrag (refereegranskat)abstract
    • Organizations are increasingly outsourcing business critical activities, which increases the risk of substantial negative impact on the financial and strategic business performance. The aim of this paper is to show how outsourcer and supplier seek to mitigate the risks during the negotiations and the ongoing operations of the outsourced activities. The conclusion is that risk mitigating dimensions are directional and operates at different organizational levels, and secondly, that the dimension operates sequentially as a means to mitigate performance and relational risks. It is also concluded that goodwill trust and a cooperative stance have substantial impact on the success of the outsourcing.
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4.
  • Abrahamsson, Mats, 1960-, et al. (författare)
  • Managing risk in complex and business critical outsourcing of services
  • 2011
  • Ingår i: Proceedings of 18th International Annual Conference of the European Operations Management Association. EurOMA. - 9781902546940 - 9781902546933
  • Konferensbidrag (refereegranskat)abstract
    • Over the past two decades the phenomenon of outsourcing of resources and activities has emerged as an important trend in a wide range of organizations and many companies are today outsourcing complex and business critical resources and activities. This increase in business criticality also increases the risk of substantial and negative impact on the financial and strategic performance. The proposition is that business critical outsourcing is approached with a joint risk perspective and that an understanding of the decision process is essential for success. Further, it is important to view outsourcing as an ongoing process with a number of key stages.
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5.
  • Adams, Mike, et al. (författare)
  • Firm size and growth in Sweden's life insurance market between 1855 and 1947 : A test of Gibrat's law
  • 2014
  • Ingår i: Business History. - : Informa UK Limited. - 0007-6791 .- 1743-7938. ; 56:6, s. 956-974
  • Tidskriftsartikel (refereegranskat)abstract
    • Using data for the period from 1855 to 1947 and the two sub-periods, 1855-1902 and 1903-47, the article examines whether the organic growth rates of 38 Swedish life insurance firms are independent of size, as predicted by Gibrat's (1931) Law of Proportionate Effects. Using panel unit root tests and panel Generalised Method of Moments (GMM) regression, the article finds a significant difference between the growth rates of small and large Swedish life insurance firms (with smaller firms tending to grow faster than larger firms), a result that clearly contradicts Gibrat's Law as a long-run tendency in the Swedish life insurance sector. significant influences were also found on firm growth from profitability, organisational form, reinsurance, the real rate of interest and the Swedish regulatory environment.
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6.
  • Adams, Mike, et al. (författare)
  • Managing policy lapse risk in Sweden's life insurance market between 1915 and 1947
  • 2020
  • Ingår i: Business History. - : Routledge. - 0007-6791 .- 1743-7938. ; 62:2, s. 222-239
  • Tidskriftsartikel (refereegranskat)abstract
    • We examine the challenges that Swedish life insurers faced in managing the lapse risk of policies written on the lives of the industrial urban working class between 1915 and 1947. We observe that with the threat of State socialisation of insurance in the 1930s, industrial life insurers modified their business practices to better control policy lapses. Using firm-level data, we also analyse the effect of socio-economic changes, such as rising real wages, interest rate fluctuations and unemployment on life insurance policy lapses. Our results support contemporary tests of the emergency fund and interest rate explanations for the voluntary premature termination of life insurance policies.
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7.
  • Adams, Mike, et al. (författare)
  • Mutuality as a control for information asymmetry : a historical analysis of the claims experience of mutual and stock fire insur ance companies in Sweden, 1889 to 1939
  • 2011
  • Ingår i: Business History. - Ilford, Essex : Cass. - 0007-6791 .- 1743-7938. ; 53:7, s. 1074-1091
  • Tidskriftsartikel (refereegranskat)abstract
    • We test two competing arguments regarding the influence of organisational form onunderwritingperformance usingdatafromtheSwedish fireinsuranceindustry for the years 1889 to 1939 – a period of both economic growth and stagnation. Since mutuality is a response to information asymmetry problems, mutual insurers are expected to report lower annual claims relative to premiums than stock insurance companies. However, an alternative view is that stock insurers seek to reduce information asymmetry problems by issuing non-participatory rights insurance contracts with high deductibles that induce risk-sharing between the insurer’s shareholders and policyholders. This implies that stock insurers are likely to report lower annual claims than mutual insurers. Our results show that organisational form is an important determinant of the claims experience of Swedish fire insurers, suggesting that mutuality acts as an effective control for information asymmetries in the market.
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8.
  • Afzal, Adeel, et al. (författare)
  • Electrochemical deposition of gold on indium zirconate (InZrOx with In/Zr atomic ratio 1.0) for high temperature automobile exhaust gas sensors
  • 2015
  • Ingår i: Journal of Solid State Electrochemistry. - : SPRINGER. - 1432-8488 .- 1433-0768. ; 19:9, s. 2859-2868
  • Tidskriftsartikel (refereegranskat)abstract
    • Automobile exhaust gas emissions are causing serious damage to urban air quality in and around major cities of the world, which demands continuous monitoring of exhaust emissions. The chief components of automobile exhaust include carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons. Indium zirconate (InZrOx) and gold/indium zirconate (Au/InZrOx) composite nanopowders are believed to be interesting materials to detect these substances. To this end, characterization and gas sensing properties of InZrOx and Au/InZrOx composite nanopowders are discussed. InZrOx nanoparticles with In/Zr atomic ratio of 1.00 (+/- 0.05) are synthesized via pH-controlled co-precipitation of In and Zr salts in aqueous ammonia. Gold (Au) nanoparticles are subsequently deposited on InZrOx using an in situ sacrificial Au electrolysis procedure. The products are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing performance of Au/InZrOx composite nanopowder is studied by depositing a thick powder film on interdigitated electrode structures patterned on SiC substrate to facilitate high temperature operation. The resistivity of the Au/InZrOx layer is the sensor signal, and the sensors could be operated at 500-600 A degrees C, which is a suitable temperature range for engine exhaust measurements. The control sensing measurements reveal that Au/InZrOx composite nanopowder exhibits higher response towards 2-20 % O-2 gas as compared to pristine InZrOx nanoparticles. Further studies show that when applied to exhaust gases such as CO and nitric oxide (NO), the response of Au/InZrOx sensors is significantly higher towards NO in this temperature range. Thus, sensor performance characteristics of Au/InZrOx composite nanopowder are promising in terms of their applications in automobile exhaust emission control.
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9.
  • Anders, Andre, et al. (författare)
  • High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition
  • 2010
  • Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:12, s. 3313-3319
  • Tidskriftsartikel (refereegranskat)abstract
    • Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide. In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200 degrees C, have resistivities in the low to mid 10(-4) Omega cm range with a transmittance better than 85% in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.
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10.
  • Andersson, Lars-Fredrik, 1974-, et al. (författare)
  • The determinants of investment returns in the fire insurance industry : the case of Sweden, 1903-1939
  • 2013
  • Ingår i: Financial History Review. - Cambridge : Cambridge University Press. - 0968-5650 .- 1474-0052. ; 20:1, s. 73-89
  • Tidskriftsartikel (refereegranskat)abstract
    • Weemploy a panel data research design to examine the determinants of investmentreturns in the Swedish property fire insurance industry from 1903 to 1939 – aperiod of great economic and political uncertainty. Contrary to expectations,we find that mutual fire insurers generated systematically higher investmentreturns than stock fire insurers. Investment returns are inversely related toleverage but positively related to liquidity, showing that firms adopting amore precautionary investment strategy attain higher returns.
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13.
  • Andersson, Mike, 1977-, et al. (författare)
  • Detecting non-hydrogen containing species with field effect devices
  • 2008
  • Ingår i: IEEE Sensors,2008. - : IEEE. - 9781424425815 - 9781424425808 ; , s. 1320-1323
  • 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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14.
  • Andersson, Mike, 1977- (författare)
  • Development and characterization of SiC based field effect gas sensors and sensor systems for emissions monitoring and control of biomass combustion
  • 2005
  • 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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15.
  • Andersson, Mike, et al. (författare)
  • Development of a ChemFET sensor with molecular films of porphyrins as sensitive layer
  • 2001
  • Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 567-571
  • Tidskriftsartikel (refereegranskat)abstract
    • The interaction of chemical species with molecular films of porphyrins causes variations of the work function of the film itself, as it has been recently demonstrated by using the Kelvin probe technique. This characteristic makes porphyrins films suitable to be used as sensitive layers in ChemFET sensors. In this paper, we present a preliminary report about the fabrication and testing of such gas sensitive devices. The technological solutions towards an optimised device are also illustrated and discussed. © 2001 Elsevier Science B.V.
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16.
  • Andersson, Mike, et al. (författare)
  • Field Effect Based Gas Sensors, from Basic Mechanisms to the Latest Commercial Device Designs
  • 2016
  • Ingår i: SENSORS AND ELECTRONIC INSTRUMENTATION ADVANCES (SEIA). - : INT FREQUENCY SENSOR ASSOC-IFSA. - 9788460899631 ; , s. 19-21
  • Konferensbidrag (refereegranskat)abstract
    • This contribution treats the latest developments in the understanding of basic principles regarding device design, transduction mechanisms, gas-materials-interactions, and materials processing for the tailored design and fabrication of SiC FET gas sensor devices, mainly intended as products for the automotive sector.
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18.
  • Andersson, Mike, 1977-, et al. (författare)
  • In situ DRIFT study of the CO response mechanism of MISFET sensors using Pt/SiO2 model sensor
  • 2008
  • Ingår i: Proceedings of IEEE Sensors. - : IEEE. - 9781424425815 - 9781424425808 ; , s. 1309-1312
  • 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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19.
  • Andersson, Mike, et al. (författare)
  • Investigations on the possibilities of a MISiCFET sensor system for OBD and combustion control utilizing different catalytic gate materials
  • 2004
  • Ingår i: Topics in catalysis. - 1022-5528 .- 1572-9028. ; 30-31:1, s. 365-368
  • Tidskriftsartikel (refereegranskat)abstract
    • Different catalytic materials, like Pt and Ir, applied as gate contacts on metal insulator silicon carbide field effect transistors — MISiCFET—facilitate the manufacture of gas sensor devices with differences in selectivity, devices which due to the chemical stability and wide band gap of SiC are suitable for high temperature applications. The combination of such devices in a sensor system, utilizing multivariate analysis/modeling, have been tested and some promising results in respect of monitoring a few typical exhaust and flue gas constituents, in the future aiming at on board diagnostics (OBD) and combustion control, have been obtained.
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20.
  • Andersson, Mike, et al. (författare)
  • New generation SiC based field effect transistor gas sensors
  • 2013
  • Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 179:SI, s. 95-106
  • Tidskriftsartikel (refereegranskat)abstract
    • With the advances in SiC processing and high temperature packaging technology over the past few years as well as the accumulation of knowledge regarding the sensing characteristics of different gate metal/insulator material combinations for different gaseous substances SiC based field effect high temperature sensors are moving towards commercial maturity. The route towards commercialization has, however, also led to the necessity of making new considerations regarding the basic transducer design and operation. The focus of this paper is thus the investigation of some basic transducer related parameters influence on sensor device performance, e.g. sensitivity and long-term stability, and characteristics to exemplify the importance of taking design, processing and operation parameters into account when developing field effect sensor devices for commercial applications. less thanbrgreater than less thanbrgreater thanTwo different types of devices, enhancement and depletion type MISFET sensors, with different gate dimensions and two different gate metallisations, Pt and Ir, have been processed. I/V-characteristics have been obtained under exposure to various concentrations of H-2, NH3, CO and O-2 and different bias conditions and the influence of gate dimensions and bias conditions on the sensitivity and dynamic range investigated. The long-term stability has also been studied and compared between different devices and bias conditions for conceptually different gas compositions. The results show that the type of basic transducer device, its design and mode of operation has a large influence on sensor performance. Depletion type devices offer better possibilities for tuning of sensitivity and dynamic range as well as improved longterm stability properties, whereas enhancement type devices require much less control of the processing to ensure good repeatability and yield. Some results have also been verified for two possible applications of SiC based field effect sensors, ammonia slip monitoring for the control of SCR/SNCR and combustion control in domestic/district heating facilities.
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21.
  • Andersson, Mike, et al. (författare)
  • On the applicability of MISiCFET gas sensors regarding ammonia slip monitoring in small-scale boilers running SNCR
  • 2007
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Gas sensitive Metal Insulator Silicon Carbide Field Effect Transistor – MISiCFET – devices have shown good possibilities of realizing sensors for high temperature applications. One such application could be the monitoring of ammonia slip from boilers running SNCR – Selective Non-Catalytic Reduction of nitrogen oxides (NOx) with ammonia (NH3). In this study a number of MISiCFET gas sensors operated at different temperatures and with both platinum (Pt) and iridium (Ir) as the gate contact have been tested for their ability to detect and quantify ammonia slip in flue gases from a 5.6 MW wood fired boiler during a test of a new SNCR-system. The individual sensors have been evaluated and compared to each other for the sensitivity towards NH3 and possible cross-sensitivities to other flue gas species through the comparison of the sensor signals with the signals from analytical instruments like FTIR – Fourier Transform Infrared spectroscopy – for nitrogen oxides (NO + NO2), NH3, and carbon monoxide (CO) and an FID – Flame Ionization Detector – for the Total Hydrocarbon Concentration (THC). The ability of a combination of sensors to provide extra or more accurate information about the NH3 concentration was also evaluated through the construction and validation of a Partial Least Squares – PLS – regression model based on all the sensor signals. Under the assumption that the sensors’ responses follow a logarithmic dependence on NH3 concentration the results regarding  ammonia slip quantification were promising both for a single Ir sensor and for the system based on all sensors. There is still a question mark for the long-term stability of the devices in real flue gases, however.
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22.
  • Andersson, Mike, et al. (författare)
  • On the CO response mechanism of SiC based field effect gas sensors
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards carbon monoxide (CO) at varying oxygen (O2) concentrations and over a wide range of temperatures have been investigated in detail at atmospheric pressure. The influence of hydrogen (H2) on the CO response was also studied. Sensor devices with thin, porous as well as dense, homogeneous Pt films on top of both silicon dioxide (SiO2) and magnesium oxide (MgO) as insulator materials were investigated in this study. The reaction products generated on the sensor surfaces were also monitored with a mass spectrometer connected to the gas flow just downstream of the sensor location and the results compared to CO oxidation characteristics over Pt/SiO2 and to some extent Pt/MgO catalysts as reported in literature. By correlating the response characteristics of these devices with CO2 formation and hydrogen consumption on the sensor surfaces, strong indications for a CO response mechanism involving a CO induced increased sensitivity to background hydrogen have been obtained, this mechanism being hypothesized to be the only one behind the CO sensitivity of devices with dense Pt metal contacts. The results also give further support to the idea that also other processes than an increased sensitivity to background hydrogen contribute to the CO response of sensor devices with a porous platinum film as the metal contact, one candidate being the removal of oxygen anions from the surface of exposed oxide areas through the oxidation reaction with CO.
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23.
  • Andersson, Mike, et al. (författare)
  • On the response mechanism of SiC based field effect gas sensors towards non-hydrogen containing species and specifically NO
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards nitrogen oxide (NO) for both low as well as relatively high background oxygen (O2) concentrations and different temperatures have been investigated at atmospheric pressure. Devices with both porous and dense Pt metal gate contacts have been investigated and the results seem to confirm the theories and results from earlier measurements regarding the requirement of porous metal films for the existence of a response to NO for this kind of sensor device. The results also suggest that no NO induced increased sensitivity to background hydrogen exists, at least it does not play any role in the observed NO sensitivity, as opposed to what has been suggested in the case of CO. The obtained results are also discussed in relation to some of the proposed sensing mechanisms for non-hydrogen containing substances and in comparison to NO reduction characteristics on Pt/SiO2 catalysts, as reported in literature. The results further give some indications about also some other process/ processes being important for the response of SiC based field effect sensors towards NO than just adsorption/desorption.
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25.
  • Andersson, Mike, 1977-, et al. (författare)
  • Recent progress in silicon carbide field effect gas sensors
  • 2020. - 2
  • Ingår i: Semiconductor gas sensors. - Oxford : Woodhead Publishing Limited. - 9780081025598 ; , s. 309-346
  • 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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26.
  • Andersson, Mike, et al. (författare)
  • Recent trends in Silicon Carbide (SiC) and Graphene based gas sensors
  • 2013
  • Ingår i: Semiconductor Gas Sensors. - : Woodhead Publishing Limited. - 9780857092366 - 9780857098665 ; , s. 117-158
  • Bokkapitel (refereegranskat)abstract
    • The introduction of silicon carbide (SiC) as the semiconductorin gas sensitive field effect devices has tremendously improved this sensor platform extending the temperature range and number of detectable gases. Here we review the recent trends in research, starting with transducer mechanisms, latest findings regarding the detection mechanism, and present new material combinations as sensing layers and smart operation of the field effect sensors enabling one sensor to act as a sensor array. Introducing epitaxially-grown graphene on SiC as gas sensing layer shows the potential of ppb detection of NO2 .
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27.
  • Andersson, Mike, 1977- (författare)
  • SiC based field effect sensors and sensor systems for combustion control applications
  • 2007
  • 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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28.
  • Andersson, Mike, et al. (författare)
  • SiC-FE gas sensor based combustion control in domestic heating systems, characteristics and utility
  • 2007
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • SiC based field effect gas sensors have been evaluated for future possible use in combustion control schemes for domestic heating systems. Emphasis has been on the possibility to monitor the state of combustion and follow the development of the combustion process from an emissions point of view and to determine its cause. The sensor signals have been compared to true emissions data – CO and total hydrocarbon concentration – as obtained by an IR spectrometer and a flame ionization detector (FID) as well as flue gas concentration of oxygen as obtained by a paramagnetic cell. The sensor characteristics have been evaluated using multivariate statistics and the results suggest that, by using the signals from one or more SiC-based field effect sensors and a thermocouple, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.
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29.
  • Andersson, Mike, et al. (författare)
  • SiC-FET sensors for selective and quantitative detection of VOCs down to ppb level
  • 2016
  • Ingår i: Procedia Engineering. - : Elsevier. - 1877-7058. ; 168, s. 216-220
  • Tidskriftsartikel (refereegranskat)abstract
    • With the increased interest in development of cheap, simple means for indoor air quality monitoring, and specifically in relation to certain well-known pollutant substances with adverse health effects even at very low concentrations, such as different Volatile Organic Compounds (VOCs), this contribution aims at providing an overview of the development status of the silicon carbide field effect transistor (SiC FET) based sensor platform for ppb level detection of VOCs. Optimizing the transducer design, the gas-sensitive material(s) composition, structure and processing, its mode of operation - applying temperature cycled operation in conjunction with multivariate data evaluation - and long-term performance it has been possible to demonstrate promising resultsregarding the sensor technology’s ability to achieve both single-digit ppb sensitivity towards e.g. naphthalene as well as selective detection of individual substances in a mixture of different VOCs.
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31.
  • Andersson, Mike, et al. (författare)
  • Tailoring of field effect gas sensors for sensing of non-hydrogen containing substances from mechanistic studies on model systems
  • 2009
  • Konferensbidrag (refereegranskat)abstract
    • To gain knowledge about the transduction mechanisms involved in the sensitivity of field effect gas sensors towards non-hydrogen containing substances, such as O-2, NO and CO, the sensor signal characteristics during exposure of some conceptually different model sensors to these as well as hydrogen containing gases have been investigated. The MOS capacitor based model sensors employ different combinations of insulator and contact materials, such as MgO, LaF3, IrO2 etc. The gas composition downstream of the sensor during test gas exposure at various conditions has also been studied by mass spectrometry (MS) and compared for the different model systems. The results have been compared to the characteristics of ordinary SiC/SiO2/Pt structures and from the information obtained a tailor made field effect sensor structure for oxygen sensing, to our knowledge for the first time with minimal interference from H-2, CO, and hydrocarbons, has been tested with promising results.
  •  
32.
  •  
33.
  • Andersson, Mike, et al. (författare)
  • Technology and application opportunities for SiC-FET gas sensors
  • 2012
  • Ingår i: Solid State Gas Sensors - Industrial Application. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642280924 ; , s. 189-214
  • Bokkapitel (refereegranskat)abstract
    • The development of SiC-FET gas sensors has proceeded for about fifteen years. The maturity of the SiC material and a deeper understanding of the transduction mechanisms and sensor surface processes behind the sensitivity to a number of target substances have recently allowed the development of market-ready sensors for certain applications. Some examples presented below are a sensor system for domestic boiler control, an ammonia sensor for control of the SCR (selective catalytic reduction) and SNCR (Selective Non-Catalytic Reduction) NOx abatement processes as well as other more or less market-ready applications. In parallel, the basic research continues in order to reach more demanding markets/new applications and also to possibly lower the production costs of the sensors. Therefore, current research and future challenges are also treated, such as the development of new types of conducting ceramics for ohmic contacts to SiC in order to increase the operation temperature beyond the present state of the art.
  •  
34.
  • Andersson, Mike, et al. (författare)
  • The characteristics and utility of SiC-FE gas sensors for control of combustion in domestic heating systems [MISFET sensors]
  • 2004
  • Ingår i: Proceedings of IEEE Sensors, 2004.. - 0780386922 ; , s. 1157-1160
  • Konferensbidrag (refereegranskat)abstract
    • The possible utility of MISiCFET gas sensors in the application of combustion control in small-scale boilers has been tested and compared to commercially available resistive-type MOS sensors. The results suggest that by using the signals from one or more MISiCFET sensors, together with the measured temperature of the furnace, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.
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35.
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36.
  • Andersson, Pia, et al. (författare)
  • Marine Acidification : On effects and monitoring of marine acidification in the seas surrounding Sweden
  • 2008. - 2008:92
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Surface waters in the world oceans have already experienced a pH reduction of about 0.1 units (OSPAR, 2006.) The trend indicates further decrease of pH and is most probably due to increased uptake of atmospheric CO2 and less buffering capacity of ocean waters. The trend is similar in the waters surrounding Sweden. RESEARCH NEEDS Since there is an alarming absence of information regarding the effects of near-future levels of ocean acidification on Swedish marine taxa, there is a clear research need on: • investigations of the effects of ocean acidification on the early life-history stages of key ecosystem-structuring species, and commercially important species of fish and shellfish • ecosystem-level mesocosm studies of the impacts of ocean acidification on Swedish marine systems • improved regional-scale modelling of acidification mechanisms in Swedish coastal waters • testable ecosystem-scale food-web models to articulate with regional acidification models • improved definition of chemical equilibrium constants between pH, AT and CO2 in low saline waters. ACTIONS TO IMPROVE MONITORING At present, pH and AT are monitored monthly at standard depths at 7 stations in Skagerrak, Kattegat and Baltic Proper within the national monitoring programme. Of these are 2 located in coastal waters (Halland and Småland; Type 5 and 9). We recommend that Sweden work to improve the status of pH and AT to be Core variables instead of Main variables in HELCOM COMBINE “High frequency Sampling” program taking into account the last 15 years negative trends in pH in waters surrounding Sweden as well as in the global oceans. We recommend that besides the standard para-meters monitored in the national monitoring program, pH, AT and DIC should be monitored. For completeness, primary production should also be monitored. Below are three monitoring recommendations, where the first is divided into a lowest level and a recommended level. 1. Lowest level: Within the national monitoring program, at least one station per open sea area and all costal stations measure acidification parameters on a monthly basis in the entire water column at standardized depths. The national and regional monitoring programmes should be upgraded in the Gulf of Bothnia so that pH and AT is monitored at standard depths at least monthly at one station each in the Bothnian Bay and Bothnian Sea. Also 2 coastal stations in the Gulf of Bothnia should be established. In addition, one coastal station should be established within Type 14 in the Baltic Proper. 1. Recommended level: the national monitoring program should have at least one station per open sea area and if the area is characterized by strong gradients or other features, there should be more than one station. Some of the stations in the regional monitoring programmes should be upgraded with acidification parameters, for a better geographical coverage. The acidification parameters should be measured on a monthly basis in the entire water column at standardized depths. 2. We recommend that an investigative monitoring is established by extending the parameters that are needed to firmly improve the chemical stability constants between pH, AT, DIC and pCO2 in low saline waters. This can be done by just extending the sampling program at selected monitoring stations. Sampling should cover a period of 2 to 3 years. 3. We recommend that direct water measurement of pCO2 for monitoring purposes should be assessed after the recommendation above is evaluated and that ongoing research projects on pCO2 measurements using ferryboxes are finalised. RECOGNISED PROBLEM AREAS • There are only few long time series of acidification parameters. The time period of measurements is rather short. • The geographical coverage of measurements is rather limited in the waters surrounding Sweden. • The chemical stability constants between pH, AT, DIC and pCO2 are not optimized in low saline waters. • pH budgets are difficult to calculate. • Models need to be improved in order to display present and future small and large scale scenarios. • Little is known of the biological, ecological and economical effects of the current and near future marine acidification. Further research is required.
  •  
37.
  • Andersson, Svante, 1962-, et al. (författare)
  • Innovation in Internationalization of Born Global firms
  • 2012
  • Ingår i: 15th McGill International Entrepreneurship Conference.
  • Konferensbidrag (refereegranskat)abstract
    • Globalization and increased liberalization of markets have made it possible for many firms, large or Small and Medium –Sized Firms (SMEs), to be in many foreign markets, especially those in the global industries (Czinkota and Ronkainen, 2007; Doole and Lowe, 2008, 2004). Since trade barriers among markets have fallen dramatically, due to the effects of globalization, intense competition in many markets, and the spread of technological improvements in almost all sectors of any economy, many firms (small or large) seek to establish their presence in many foreign markets (Awuah, et. al., 2011; Doole and Lowe, 2008; Driffield and Love, 2007). Studies abound to shed light on why and how firms internationalize their business activities (Andersson, 2011; Moen, et al., 2004; Knight and Cavusgil, 1996; Johanson and Vahlne, 1990, 1977; Johanson and Wiedersheim-Paul, 1975). Although increased globalization, trade liberalization, and technological improvements do enable many firms (e.g. “Mininationals” or “Born Globals”) to serve several markets (Doole and Lowe, 2008; Czinkota and Ronkainen, 2007), there has emerged an intense competition among firms in all countries (Peng et al., 2008; Czinkota and Ronkainen, 2007; Beamish and Lu, 2004). For many SMEs, a number of factors (e.g. lower trade barriers, increased competition, rapid technological developments, shrinking market opportunities in domestic market, and firm-specific advantages combine to drive their rapid entry into foreign markets (Andersson, 2011; Peng et al., 2008; Moen, et al., 2004). SMEs that have, from the very inception of their establishment, had the drive to internationalize their business activities are termed “Born Global Firms”, in the subsequent sections to be addressed just as born globals (Andersson, 2011; Rialp et al., 2005; Knight and Cavusgil, 1996; Madsen and Servias, 1997). Previous studies about a firm’s internationalization has predominantly concentrated on big multinational firms, where their motives for internationalization, the pace and pattern of their internationalization have been widely studied (Qian and Delios, 2008; Johanson and Vahlne, 1990, 1977; Johanson and Wiedersheim-Paul, 1975; Cavusgil, 1984; Coviello, 2006). In recent times studies have emerged, which have found out that the pace and pattern of the internationalization of big multinational firms are not in line with the pace and pattern, through which born globals, for example, internationalize their business activities (Andersson, 2011; Andersson and Wictor, 2003; Moen, et al., 2004; Rialp, et. al., 2005; Knight and Cavusgil, 1996; Madsen and Servais, 1997).  However, extant literature is virtually silent on what it takes for a born global (a small international player with limited resources, for example) to compete with big and resourceful multinational enterprises in many international markets. Our contention is that born globals’ ability to use innovative solutions to create sustainable competitive advantages as they aspire to expand and grow in international markets will be very crucial. The pace and pattern at which born globals internationalize their businesses, in the face of intense competition in almost all markets, in order to provide innovative solutions that enable them to achieve competitive advantages in the marketplace is under-researched. This has been an important reason for the study of the present phenomenon.   As stressed by Doole and Lowe (2008), products and services offered by firms, these days, are becoming ‘commodities’ (i.e. ‘me too’ products/services), if firms are not able to differentiate the core product benefit or service by offering a bundle of benefits for target customers or users in a target market. For Porter (1985), the competitive advantage of a firm grows fundamentally out of the value the firm can create for its customers, irrespective of the markets in which a firm operates.  Operating across borders, though offers opportunities, dealing with new set of macro-environmental factors (e.g. politics, laws, economics, cultures, and societies) and intense competition, will demand that a born global, for example, differentiates its products and services that will help it to meet similar needs and wants of its transnational customers, while it adapts to meet different market-specific requirements and/or needs of customers (e.g. Doole and Lowe, 2008). And for Doyle and Stern (2006), a firm that is good at satisfying customer needs, better than its competitors can do, has the best opportunities to grow and expand. Hence, Born Globals and their growth and expansion narratives are worth studying.In view of the above, the purpose of the present study is to investigate a born global’s use of innovative solutions to create sustainable competitive advantages as it expands and grows in different international markets. To be able to achieve the above purpose, we seek to address the following research questions:Why and how does a born global firm enter any chosen foreign market?Which strategies does the firm develop and implement in order to provide innovative solutions that will help achieve sustainable competitive advantages as the firm strives to grow and expand in the marketplace?Does the firm use ‘go-alone’ strategies or does it use strategies that influence and are influenced by other actors and the effect thereof? 
  •  
38.
  • Andersson, Svante, 1962-, et al. (författare)
  • Success Factors in Western and Chinese Born Global Companies
  • 2015
  • Ingår i: iBusiness. - Irvine, CA : Scientific Research Publishing. - 2150-4075 .- 2150-4083. ; 7:1, s. 25-38
  • Tidskriftsartikel (refereegranskat)abstract
    • Born Global firms are becoming increasingly more important in terms of internationalization, innovation, ability to grow and providing employment. Most of the previous research about BornGlobals is done in North America, Europe or Australia, all these being developed industrialized countries but not developing countries or emerging markets. However, the emerging markets in general, and the Chinese in particular, have become very important for the world economy. Our aim is to investigate the differences between Western literature and literature from emerging markets, regarding internationalization process of Born Global firms. We also aim to discuss the various success factors, which underlie Born Globals’ internationalization process, particularly focusing on Born Globals firms in the China. Our methodology in this research has been literature review and interviews with Chinese CEOs of Born Global firms. However, this paper is only based on the litterateur part of our research. Our analysis shows that most of the Chinese Born Globals publications about the internationalization success factors are based on the Western literature and use them as the theoretical platform in the design of their own research strategy and research questions design. The consequence of this observation is important as it indicates that Chinese researchers are reproducing research under different contextual and situational conditions that might lead to unclear conclusions or maybe even wrong conclusions. Furthermore, compared to most Western Born Global companies, which treat innovation as core competence, the innovation culture becomes one of the biggest weaknesses of Chinese manufacturing Born Globals’ internationalization. China has special economic environment. Chinese manufacturing Born Globals not only need to follow the market but also the government policies, since the government greatly influences the industries and the whole economy. To foreign investors who want to exploit Chinese market, they also should take Chinese economic background and government policies into consideration. One important aspect of Chinese born Globals, neglected in previous research on Born Globals, that has been identified in our research, is the critical success factor of Chinese manufacturing Born Globals—the political and economic background and the role of the Chinese Government in the transformation process of Chinese business life, and the Guanxi network.
  •  
39.
  • Andersson, Sandra, 1978- (författare)
  • Validation of antibodies for tissue based immunoassays
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In situ protein detection in human tissues using antibodies reveals the cellular protein localization, and affinity-based proteomic studies can help to discover proteins involved in the development of diseases. However, antibodies often suffer from cross-reactivity, and the lack of positive and negative tissue controls for uncharacterized proteins complicates the mapping of the proteome. The aim of this thesis is thus to improve the methodology for validating antibodies used for immunostaining on formalin-fixed paraffin-embedded tissues.Two of the papers include comparisons between mRNA-expression and immunostaining of corresponding protein. In paper I, ISH and IHC staining patterns were compared on consecutive TMA-slides. The study of well-characterized genes showed that ISH could be used for validation of antibodies. ISH was further used for antibody evaluation, and could validate four out of nine antibodies showing potentially interesting staining patterns. In paper III, transcriptomic data generated by RNA-sequencing were used to identify tissue specific expression in lymphohematopoietic tissues. An increased expression in one or more of these tissues compared to other tissue types was seen for 693 genes, and these were further compared to the staining patterns of corresponding proteins in tissues.Antibody labeling is necessary for many immunoassays. In paper II, two techniques for antibody-biotinylation were compared, aiming to find a stringent labeling method for antibodies used for immunostaining on TMAs. The ZBPA-method, binding specifically to Fc-part of antibodies, was found to be superior to the Lightning Link-biotinylation kit targeting amine groups, since labeling of amine groups on stabilizing proteins in the antibody buffer causes unspecific staining.The localization of the estrogen receptor beta (ERβ) in human normal and cancer tissues was studied in paper IV. Thorough evaluation of 13 antibodies using positive and negative control cell lines showed that only one antibody, PPZ0506, is specific for ERβ in all three immunoassays used. Contradictory to previously published data, tissue profiling using PPZ0506 showed that ERβ is expressed in a limited number of normal and cancer tissues.In conclusion, the present investigations present tools for validation of antibodies used for large-scale studies of protein expression in tissues.
  •  
40.
  • Angelstam, Per, et al. (författare)
  • Solving Problems in Social-Ecological Systems : Definition, Practice and Barriers of Transdisciplinary Research
  • 2013
  • Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 42:2, s. 254-265
  • Tidskriftsartikel (refereegranskat)abstract
    • Translating policies about sustainable development as a social process and sustainability outcomes into the real world of social-ecological systems involves several challenges. Hence, research policies advocate improved innovative problem-solving capacity. One approach is transdisciplinary research that integrates research disciplines, as well as researchers and practitioners. Drawing upon 14 experiences of problem-solving, we used group modeling to map perceived barriers and bridges for researchers' and practitioners' joint knowledge production and learning towards transdisciplinary research. The analysis indicated that the transdisciplinary research process is influenced by (1) the amount of traditional disciplinary formal and informal control, (2) adaptation of project applications to fill the transdisciplinary research agenda, (3) stakeholder participation, and (4) functional team building/development based on self-reflection and experienced leadership. Focusing on implementation of green infrastructure policy as a common denominator for the delivery of ecosystem services and human well-being, we discuss how to diagnose social-ecological systems, and use knowledge production and collaborative learning as treatments.
  •  
41.
  • Bastuck, Manuel, et al. (författare)
  • Characterizing the Influence of Gate Bias on Electrical and Catalytical Properties of a Porous Platinum Gate on Field Effect Gas Sensors
  • 2016
  • Ingår i: 2016 IEEE SENSORS. - : IEEE. - 9781479982875
  • Konferensbidrag (refereegranskat)abstract
    • In this work, we exposed an MIS capacitor with porous platinum as gate material to different concentrations of CO and NH3. Its capacitance and typical reaction products (water, CO2 and NO) were monitored at high and low oxygen concentration and different gate bias voltages. We found that the gate bias influences the switch-point of the binary CO response usually seen when either changing the temperature at constant gas concentrations or the CO/O-2 ratio at constant temperature. For NH3, the sensor response as well as product reaction rates increase with bias voltages up to 6 V. A capacitance overshoot is observed when switching on or off either gas at low gate bias, suggesting increasing oxygen surface coverage with decreasing gate bias.
  •  
42.
  • Bastuck, Manuel, et al. (författare)
  • Exploring the selectivity of WO3 with iridium catalyst in an ethanol/naphthalene mixture using multivariate statistics
  • 2016
  • Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 618, s. 263-270
  • Tidskriftsartikel (refereegranskat)abstract
    • Temperature cycled operation and multivariate statistics have been used to compare the selectivity of two gate (i.e. sensitive) materials for gas-sensitive, silicon carbide based field effect transistors towards naphthalene and ethanol in different mixtures of the two substances. Both gates have a silicon dioxide (SiO2) insulation layer and a porous iridium (Ir) electrode. One of it has also a dense tungsten trioxide (WO3) interlayer between Ir and SiO2. Both static and transient characteristics play an important role and can contribute to improve the sensitivity and selectivity of the gas sensor. The Ir/SiO2 is strongly influenced by changes in ethanol concentration, and is, thus, able to quantify ethanol in a range between 0 and 5 ppm with a precision of 500 ppb, independently of the naphthalene concentrations applied in this investigation. On the other hand, this sensitivity to ethanol reduces its selectivity towards naphthalene, whereas Ir/WO3/SiO2 shows an almost binary response to ethanol. Hence, the latter has a better selectivity towards naphthalene and can quantify legally relevant concentrations down to 5 ppb with a precision of 2.5 ppb, independently of a changing ethanol background between 0 and 5 ppm. (C) 2016 Elsevier B.V. All rights reserved.
  •  
43.
  • Bastuck, Manuel, 1990- (författare)
  • Improving the Performance of Gas Sensor Systems with Advanced Data Evaluation, Operation, and Calibration Methods
  • 2019
  • 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. 
  •  
44.
  • Bastuck, Manuel, et al. (författare)
  • Low-cost chemical gas sensors for selective formaldehyde quantification at ppb-level in field tests
  • 2017
  • 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.
  •  
45.
  • Bastuck, Manuel, et al. (författare)
  • UV-assisted gate bias cycling in gas-sensitive field-effect transistors
  • 2018
  • Ingår i: Proceedings. - Basel Switzerland : MDPI. - 2504-3900. ; 2:13
  • 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.
  •  
46.
  • Bastuk, Emanuel, et al. (författare)
  • Identification of ammonia and carbon monoxide based on the hysteresis of a gas sensitive silicon carbide field effect transistor
  • 2013
  • Ingår i: Transducers 2013 & Eurosensors XXVII. - : IEEE. - 9781467359832 ; , s. 250-253
  • Konferensbidrag (refereegranskat)abstract
    • In this work gate bias cycled operation (GBCO) is used on a gas-sensitive SiC field effect transistor(“GasFET”) to increase the sensitivity and selectivity. Gate bias ramps introduce strong hysteresis in the sensor signal. The shape of this hysteresis is shown to be an appropriate feature both for the discrimination of various gases (NH3, CO, NO, CH4) and also different gas concentrations (250 and 500 ppm). The shape is very sensitive to ambient conditions. Thus, the influence of oxygen concentration and relative humidity as well as sensor temperature is investigated and reasons for the observed signal changes are discussed.
  •  
47.
  • Bastuk, Manuel, et al. (författare)
  • Gas identification based on bias induced hysteresis of a gas-sensitive SiC field effect transistor
  • 2014
  • Ingår i: Journal of Sensors and Sensor Systems. - : Copernicus GmbH. - 2194-8771 .- 2194-878X. ; 3, s. 9-19
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work dynamic variation of gate bias is used on a gas-sensitive SiC field effect transistor ("GasFET") to optimize its sensitivity and increase its selectivity. Gate bias ramps introduce strong hysteresis in the sensor signal. The shape of this hysteresis is shown to be an appropriate feature both for the discrimination of various gases (ammonia, carbon monoxide, nitrogen monoxide and methane) as well as for different gas concentrations (250 and 500 ppm). The shape is very sensitive to ambient conditions as well as to the bias sweep rate. Thus, the influences of oxygen concentration, relative humidity, sensor temperature and cycle duration, i.e., sweep rate, are investigated and reasons for the observed signal changes, most importantly the existence of at least two different and competing processes taking place simultaneously, are discussed. Furthermore, it is shown that even for very fast cycles, in the range of seconds, the gas-induced shape change in the signal is strong enough to achieve a reliable separation of gases using gate bias cycled operation and linear discriminant analysis (LDA) making this approach suitable for practical application.
  •  
48.
  •  
49.
  • Becker, Elin, 1981, et al. (författare)
  • In situ DRIFT study of hydrogen and CO adsorption on Pt/SiO2 model sensors
  • 2007
  • Ingår i: 2007 IEEE Sensors. - 1930-0395. - 9781424412617 ; 1-3, s. 1028-1031
  • Konferensbidrag (refereegranskat)abstract
    • The sensing mechanism towards carbon monoxide of Metal Insulator Silicon Carbide (MISiC) Field Effect devices used as sensors, has been studied by in situ FTIR spectroscopy in diffuse reflectance mode (DRIFT). The infrared studies were performed using a model sensor, where adsorption of CO in presence of oxygen and hydrogen has been studied. The results show that the CO adsorption on Pt varies with varying oxygen concentration, CO concentration, hydrogen exposure and temperature. When correlating the DRIFT spectroscopy with sensor signal measurements, the CO response or MISiC field effect devices appears to be connected to the CO coverage of the sensor surface.
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50.
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