| 1. |
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| 2. |
- Andersson, Matilda, et al.
(författare)
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Deposition and characterization of magnetron sputtered amorphous Cr-C films
- 2012
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 86:9, s. 1408-1416
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Tidskriftsartikel (refereegranskat)abstract
- Thin films in the Cr-C system with carbon content of 25-85 at.% have been deposited using non-reactive DC magnetron sputtering from elemental targets. Analyses with X-ray diffraction and transmission electron microscopy confirm that the films are completely amorphous. Also, annealing experiment show that the films had not crystallized at 500 degrees C. Furthermore, X-ray spectroscopy and Raman spectroscopy show that the films consist of two phases, an amorphous CrCx phase and an amorphous carbon (a-C) phase. The presence of two amorphous phases is also supported by the electrochemical analysis, which shows that oxidation of both chromium and carbon contributes to the total current in the passive region. The relative amounts of these amorphous phases influence the film properties. Typically, lower carbon content with less a-C phase leads to harder films with higher Young's modulus and lower resistivity. The results also show that both films have lower currents in the passive region compared to the uncoated 316L steel substrate. Finally, our results were compared with literature data from both reactively and non-reactively sputtered chromium carbide films. The comparison reveals that non-reactive sputtering tend to favour the formation of amorphous films and also influence e.g. the sp(2)/sp(3) ratio of the a-C phase.
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| 3. |
- Auvray, Xavier, 1986, et al.
(författare)
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Comparative Study of SO 2 and SO 2 /SO 3 Poisoning and Regeneration of Cu/BEA and Cu/SSZ-13 for NH 3 SCR
- 2021
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Ingår i: Emission Control Science and Technology. - : Springer Science and Business Media LLC. - 2199-3629 .- 2199-3637. ; 7:4, s. 232-246
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Tidskriftsartikel (refereegranskat)abstract
- Two copper-exchanged zeolites, Cu/SSZ-13 and Cu/BEA, were studied as catalysts for the selective reduction of NOx by NH3 (NH3-SCR). Their activities for standard SCR (NOx = NO) and fast SCR (NOx = 50% NO + 50% NO2) were measured before and after sulfur poisoning at 250 °C. The effect of 30 ppm SO2 and a mixture of 24 ppm SO3 + 6 ppm SO2 was evaluated. The repetition of subsequent activity measurements served as regeneration method in SCR conditions. SO2 deactivated Cu/SSZ-13 whereas Cu/BEA was only moderately affected. SO3 led to stronger deactivation of both catalysts than SO2. However, also for this case, the Cu/BEA was significantly less affected than Cu/SSZ-13, even though Cu/BEA contained larger amount of stored sulfur. One possible reason for this could be the large pores of Cu/BEA, where the sulfur species possibly resulted in less sterical hindrance than in the small pore SSZ-13 structure. NH3 temperature-programmed desorption (NH3-TPD) showed no loss of storage sites upon sulfur treatment and subsequent regeneration. Partial activity recovery was observed after a period in SCR conditions at 400 °C and 500 °C. Temperature at 300 °C was insufficient to regenerate the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of NO adsorption suggested that SO2 interacts with the ZCuOH sites on Cu/SSZ-13, causing the strong poisoning.
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| 4. |
- Forsman, Åsa, 1972-, et al.
(författare)
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Detektion av narkotikapåverkan med hjälp av automatisk avläsning av ögonrörelser : ett pilotprojekt för att bedöma metodens potential
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige har en nollgräns för narkotika i trafiken. Om polisen påträffar en förare som de misstänker är narkotikapåverkad har de rätt att utföra en ögonundersökning och om undersökningen stärker misstanken tas personen med för att lämna blod- och urinprov. Dagens metod med ögonunder[1]sökningar lägger ett stort ansvar på den enskilde polismannen, även med adekvat utbildning finns risk för felbedömningar. Det finns därför ett behov av ett sållningsinstrument som kan användas för att detektera narkotikapåverkade förare. Ett sådant instrument behöver vara tillförlitligt och snabbt men också värna förarnas personliga integritet. I det här PM:et presenteras ett pilotprojekt med syftet att bedöma potentialen i automatisk avläsning av ögonrörelser för att detektera narkotikapåverkan. Avläsningen gjordes med en så kallad eyetracker som spelar in en sekvens av ögonrörelser. Ögonrörelsedata samlades in från två grupper, misstänkta för drograttfylleribrott (88 personer) och polisanställda (88 personer). Indelningen i dessa grupper användes som proxy för om personerna faktiskt var narkotikapåverkade eller inte. Utifrån ögonrörelsedata utvecklades en klassificeringsalgoritm som predikterade grupptillhörighet. Resultaten visar att andel korrekt klassificerade av de misstänkta (sensitiviteten) var 73 procent och av de anställda (specificiteten) 63 procent. Total andel korrekt klassificerade var 68 procent (konfidensintervall 56–80 procent). Blodprov från de misstänkta visade vilka som faktiskt var påverkade. En analys visade att grupperna med positivt respektive negativt blodprov var mer lika varandra än vad de med negativt prov liknade de anställda, med avseende på ögonrörelsemått. Det visar att det krävs fortsatt utveckling av metoden.
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| 5. |
- Högström, Jonas, et al.
(författare)
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Cation profiling of passive films on stainless steel bydeconvolution of angle-resolved X-ray photoelectronspectroscopy data
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A novel way of deconvoluting angle-resolved x-ray photoelectron spectroscopy (ARXPS) data to determine cation depth profiles in oxide films on stainless steels for a ternarysystem is presented. The passive films investigated were formed on AISI 316L EN 1.4432 stainless steel at the open circuit potential (OCP) in deionized water and at potentialsfrom −1.5 to +1.5V vs. Ag/AgCl in two acidic electrolytes: 0.5m H2SO4 and acetic acidcontaining 0.02m Na2B4O7 · 10H2O and 1m H2O. The passive films were about 1–2nmthick and contained concentration gradients of iron, chromium and molybdenum. Ironwas found to be present on the surface, chromium was mainly enriched in the middle, andmolybdenum was only present and strongly enriched in the inner region of the passivefilm. The ability to determine cation profiles in nanometer-thin oxide films provides newpossibilities for tailoring the properties of passive films on stainless steels.
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| 6. |
- Högström, Jonas, et al.
(författare)
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Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra
- 2013
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 284, s. 700-714
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Tidskriftsartikel (refereegranskat)abstract
- An approach for determining depth gradients of metal-ion concentrations in passive films on stainlesssteel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method,which is based on analyses of the oxidised metal peaks, provides increased precision and hence allowsfaster ARXPS measurements to be carried out. The method was used to determine the concentrationdepth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steelsamples oxidised in 0.5 M H2SO4 and acetic acid diluted with 0.02 M Na2B4O7 · 10H2O and 1 M H2O,respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface andthe films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer.Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes,the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution.The differences in the layer composition, found for the two electrolytes as well as different oxidationconditions, can be explained based on the oxidation potentials of the metals and the dissolution rates ofthe different metal ions.
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| 7. |
- Högström, Jonas
(författare)
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Corrosion and Surface Studies of Stainless Steel and Chromium Carbide Thin-Films
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although the passive films that form on stainless steels have been extensively studied, the concentration depth profiles are not fully understood. Their thinness makes passive films hard to study, but angle-resolved X-ray photoelectron spectroscopy (ARXPS) is a non-destructive technique that can be used to obtain depth information. An iterative approach to deconvolute ARXPS measurements into depth profiles is discussed, and the chemistry of passive films on a molybdenum-containing 316L stainless steel is investigated. Bipolar electrochemistry, in which the sample is placed along an electric field created by two driving electrodes in an electrolyte, is investigated as a screening tool. It is shown that the method is useful to create corrosion gradients on 304 stainless steel, both under pitting and non-pitting conditions. Chromium carbide thin films were deposited by magnetron sputtering with a variety of deposition parameters on stainless steel, and subsequently analyzed. It is shown that these films present a promising material system for protective coatings to improve the corrosion resistance of stainless steels while also maintaining other useful properties, such as low interfacial contact resistance. Particular attention is given to the electrochemical evaluation of the films, whose high carbon concentrations necessitates different interpretations of the electrochemical results compared to for stainless steels.
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| 8. |
- Högström, Jonas, et al.
(författare)
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On the evaluation of corrosion resistances of amorphous chromium carbide thin-films
- 2014
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 122:SI, s. 224-233
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Tidskriftsartikel (refereegranskat)abstract
- The possibilities of evaluating the corrosion resistance of amorphous chromium carbide (Cr-C) films containing nanometre-sized carbide grains embedded in an amorphous carbon matrix on the basis of polarization curves, voltammograms and the oxidation charge have been studied for Cr-C films with different carbon concentrations. The films, which were manufactured by non-reactive directcurrent magnetron sputtering, were studied in 1.0 mM H2SO4 at both 22 °C and 80 °C, and with scanning electron microscopy and X-ray photoelectron spectroscopy prior to and after the electrochemical experiments. It is demonstrated that the oxidation of these Cr-C films gives rise to a surface composed of Cr2O3 and partially oxidized carbon and that the non-corroding oxidation current due to the carbon oxidation increases with increasing carbon concentration in the films as well as with the electrolyte temperature. Since the oxidation current is composed of contributions from both Cr-C and carbon oxidation it is not straightforward to evaluate the corrosion resistances of these films based on the current in the passive region, the mixed potential (i.e., the corrosion potential) or the open circuit potential. The present results in fact indicate that Cr-C films with high carbon concentrations may have better corrosion resistances than the corresponding films with lower carbon concentrations although larger currents in the passive region can be seen in polarization curves.
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| 9. |
- Högström, Tomas, et al.
(författare)
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Telecommands for Remotely Operated Vehicles
- 1995
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. - 0080423663 ; 28:11, s. 301-306
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Tidskriftsartikel (refereegranskat)abstract
- The problem addressed is controlling a robot over a communication channel with low bandwidth, a non-neglectable time delay and time jitters. The external sensors on the robot are a time-of-flight range measuring laser and a video camera. Video images are used by the operator for interpreting the scene and are only sent at “fax rate”. The operator is thus interpreting the workspace around the vehicle, making plans for the individual operations in a composite task and is giving high level commands. The telecommands are to be executed autonomously by the robot. Inside the robot the control loop is closed with full bandwidth when each command is executed.This paper reports on work in progress and focus on:1. Incremental map building, especially simplifications for large buildings and robustness when the vehicle returns to a previously mapped area. This is a very useful support function for the operator.2. Tests of telecommands on a mobile robot available for experiments over the Internet. Available sensors are inclinometers, odometry, CCD intensity images and range measuring laser data.Other needed telecommands studied previously are:Travelling along corridors, follow walls etc. The operation is based on the range weighted Hough transform and is both robust and precise. The repeatability is about 1 cm at 1 m/s. The robot is not disturbed by people passing in the corridor.Commands for passage through an open door works within 1 cm and 0.5 degrees at a speed of 0.5 m/s. Passing between irregular obstacles is less accurate.Using rate gyros, lock the heading of the robot when driving on a straight line. Also preprogrammed 90- and 180-degrees turns.Automatically enter a camera defined line. The direction of the camera can be used to drop a new coordinate frame at any time (using a button on the keyboard). The robot will automatically enter this new line and also compensate for the overshoot.To integrate these different commands into a complete system is a resource demanding task for the future.
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| 10. |
- Munktell, Sara, et al.
(författare)
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Bipolar electrochemistry for high-throughput corrosion screening
- 2013
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Ingår i: Electrochemistry communications. - : Elsevier BV. - 1388-2481 .- 1873-1902. ; 34, s. 274-277
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Tidskriftsartikel (refereegranskat)abstract
- It is demonstrated that bipolar electrochemistry can be used for high-throughput corrosion testing covering a wide potential range in one single experiment and that this, combined with rapid image analysis, constitutes a simple and convenient way to screen the corrosion behaviour of conducting materials and corrosion protective coatings. Stainless steel samples (SS304), acting as bipolar electrodes, were immersed in sulphuric and hydrochloric acid and exposed to an electric field to establish a potential gradient along the surface. In this way, the same steel sample was exposed to a wide range of cathodic and anodic conditions, ranging from potentials yielding hydrogen evolution to potentials well into the transpassive region. This wireless approach enables rapid simultaneous comparison of numerous samples, and also provides the opportunity to perform experiments on samples that are of a complex shape, or which otherwise are difficult to employ in standard electrochemical corrosion tests.
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| 11. |
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| 12. |
- Nygren, Kristian, et al.
(författare)
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Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Cr-C films
- 2014
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 305, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Cr C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Cr C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 degrees C were X-ray amorphous and 500 C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl(sat. KG) in hot 1 mM H-2 SO4 resulted in oxidation of Cr C, yielding Cr203 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Cr C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes. (C) 2014 Elsevier B.V. All rights reserved.
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| 13. |
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| 14. |
- Wernersson, Åke, et al.
(författare)
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Telecommands for semiautonomous operations
- 1995
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Ingår i: Telemanipulator and telepresence technologies. - Bellingham, Wash : SPIE - International Society for Optical Engineering. - 081941686X ; , s. 2-12
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Konferensbidrag (refereegranskat)abstract
- The problem addressed is controlling the relative position between the robot and an object using a sequence of operations specified at a high level. The goal is telecommands for robots to operate over a communication net with low bandwidth, a non-neglectable time delay and time jitter. Using an eye in hand range sensor, motion commands can be entered and executed relative to a range map generated from measurements. The ratio of task relevant information/bandwidth is high for this sensor (it returns range in a plane between fingers in the gripper). Conventional images are only sent to the operator at "fax rate"
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