| 1. |
- Filla, Reno, 1973-
(författare)
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Operator and Machine Models for Dynamic Simulation of Construction Machinery
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- VIRTUAL PROTOTYPING has been generally adopted in product development in order to minimise the traditional reliance on testing of physical prototypes. It thus constitutes a major step towards solving the conflict of actual increasing development cost and time due to increasing customer demands on one side, and the need to decrease development cost and time due to increasing competition on the other. Particularly challenging for the off-road equipment industry is that its products, working machines, are complex in architecture. Tightly coupled, non-linear sub-systems of different technical domains make prediction and optimisation of the complete system’s dynamic behaviour difficult.Furthermore, in working machines the human operator is essential for the performance of the total system. Properties such as productivity, fuel efficiency, and operability are all not only dependent on inherent machine properties and working place conditions, but also on how the operator uses the machine. This is an aspect that is traditionally neglected in dynamic simulations, because the modelling needs to be extended beyond the technical system.The research presented in this thesis focuses on wheel loaders, which are representative for working machines. The technical system and the influence of the human operator is analysed, and so-called short loading cycles are described in depth. Two approaches to rule-based simulation models of a wheel loader operator are presented and used in simulations. Both operator models control the machine model by means of engine throttle, lift and tilt lever, steering wheel, and brake only – just as a human operator does. Also, only signals that a human operator can sense are used in the models. It is demonstrated that both operator models are able to adapt to basic variations in workplace setup and machine capability. Thus, a “human element” can be introduced into dynamic simulation of working machines, giving more relevant answers with respect to operator-influenced complete-machine properties such as productivity, fuel efficiency, and operability already in the concept phase of the product development process.
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| 2. |
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| 3. |
- Beattie, D.A., et al.
(författare)
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In situ total internal reflection Raman spectroscopy of surfactant adsorption at a mineral surface
- 2006
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Ingår i: Vibrational Spectroscopy. - : Elsevier BV. - 0924-2031 .- 1873-3697. ; 41:2, s. 198-204
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Tidskriftsartikel (refereegranskat)abstract
- We present the first attempt to characterise surfactant adsorption from solution onto a particle film using total internal reflection Raman spectroscopy. Three surfactant collectors of interest to the mineral processing industry were studied in their adsorption onto sphalerite: heptyl xanthate, 2-mercaptobenzothiazole (MBT), and O,O-dibutyldithiophosphate (DTP). All three surfactants adsorbed to the surface of the sphalerite. Adsorption of heptyl xanthate was monitored as a function of time and increasing concentration. The spectrum of heptyl xanthate indicated the presence of a small amount of dixanthogen on the surface of the sphalerite. MBT adsorption studies were complicated due to the fluorescence of the adsorbed layer. However, peaks due to the adsorbed MBT were observed on top of the fluorescent background, allowing the identification of the adsorbed species to be confirmed as the oxidised dimer species. Spectra obtained from MBT and DTP co-adsorption studies did not display the strong adsorbate layer fluorescence, indicating that the fluorescence spectrum of the adsorbed MBT is most likely affected by ring-ring interactions.
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| 4. |
- Fredriksson, Andreas, et al.
(författare)
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n-Heptyl xanthate adsorption on a ZnS layer synthesized on germanium : an in situ attenuated total reflection IR study
- 2005
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 286:1, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of n-heptyl xanthate on synthesized zinc sulfide was followed in situ by monitoring the methylene absorption band at 2925 cm-1. The zinc sulfide surface used in the adsorption experiments was synthesized on a germanium internal reflection element using the chemical bath deposition method. Characterization of the adsorbent surface was performed by X-ray photoelectron spectroscopy. The time needed to reach adsorption equilibrium varied with the initial concentration of the aqueous potassium heptyl xanthate solution. The amount of adsorbed xanthate ions increased with the concentration of the solution within the range studied (10 μM-50 mM). The experimental data are reasonably well described by the Langmuir adsorption isotherm. Polarized infrared attenuated total reflection (ATR) was used to determine the average orientation of the heptyl chains by measuring the absorbance of the infrared beam polarized perpendicularly and parallely to the plane of incidence. Measured absorbances were corrected for contribution from heptyl xanthate in bulk solution.
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| 5. |
- Grahn, Mattias, et al.
(författare)
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Silicalite-1 coated ATR elements as sensitive chemical sensor probes
- 2005
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 81:1-3, s. 357-363
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Tidskriftsartikel (refereegranskat)abstract
- A novel sensitive chemical sensor probe has been fabricated. The sensor principle is based on silicalite-1 coated ATR (attenuated total reflection) elements and FTIR spectroscopy. The microporous silicalite-1 film enriches the analyte to the probe surface, thus increasing the sensitivity. At a relative pressure of n-hexane in helium of 6 × 10−5 the sensitivity of the probe is approximately 85 times higher for the silicalite-1 coated element compared to a 10 cm transmission gas cell and ca. 180 times higher compared to an uncoated element. The performance of the probe is illustrated by determination of an adsorption isotherm for n-hexane in silicalite-1.
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| 6. |
- Hellström, Pär, et al.
(författare)
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Study of potassium O,O′-dibutyldithiophosphate combining DFT, 31P CP/MAS NMR and infrared spectroscopy
- 2008
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 112:46, s. 11777-11783
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Tidskriftsartikel (refereegranskat)abstract
- Dithiophosphates are used in many different industrial applications. To explain their functions and properties in these applications, a fundamental understanding on a molecular level is needed. Potassium O,O′-Dibutyldithiophosphate and its anion have been investigated by means of a combination of DFT and 31P CP/MAS NMR and infrared spectroscopy. Several low-energy conformations were studied by DFT. Three different conformations with significantly different torsion angles of the O-C bond relative to the O-P-O plane were selected for further studies of infrared frequencies and 31P NMR chemical-shift tensors. A good agreement between theoretical and experimental results was obtained, especially when the IR spectra or 31P chemical shift tensor parameters of all three conformations were added, indicating that, because of the low energy difference between the conformations, the molecules are rapidly fluctuating between them.
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| 7. |
- Wang, Zheng, et al.
(författare)
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Zeolite coated ATR crystal probes
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 115:2, s. 685-690
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Tidskriftsartikel (refereegranskat)abstract
- Thin and well-defined MFI type molecular sieve films were grown on a range of ATR crystals by employing a seeding method. The type of ATR crystal does not influence film morphology. FTIR spectroscopy was used to evaluate the coated ATR crystals as sensor probes. These novel sensor probes could be used to detect low concentrations of organic molecules in a gas flow.
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