| 1. |
- Bengtsson, Per Erik, et al.
(författare)
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Dual-broadband rotational cars measurements in an IC engine
- 1994
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Ingår i: Symposium (International) on Combustion. - 0082-0784. ; 25:1, s. 1735-1742
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Tidskriftsartikel (refereegranskat)abstract
- This is the first report of pure rotational coherent anti-Stokes Raman spectroscopy (CARS) measurementsin an internal combustion (IC) engine. Single-shot, dual-broadband rotational CARS (DB-RCARS) spectra were recorded both prior to ignition and in the postcombustion gases. From these spectra, both temperature and relative oxygen concentrations were evaluated. The pressure was registered simultaneously with the CARS measurements in the spark-ignition engine burning natural gas and air. Prior to ignition, normally at temperatures below 1000 K and pressures below 2 MPa, a rotational CARS spectrum is very temperature sensitive, and the technique can be used for temperature measurements with high accuracy. Evaluated temperatures show a negligible dependence on uncertainties in parameters such as the nonresonant susceptibility of the gas and the slit width. Moreover, no collisional narrowing of the lines has to be taken into account. The relative standard deviation of evaluated temperatures and of relative oxygen concentrations from single-shot measurements were as low as 1, and 1.4-1.9%, respectively. In the postcombustion gases at temperatures above 2000 K and pressures above 1.5 MPa, the nonresonant CARS background gave a large contribution to the total spectrum. In this temperature and pressure range, the evaluated values of temperature and nonresonant susceptibility are not independent, and the nonresonant susceptibility had to be fixed at a precalculated value to get a reliable temperature evaluation. The avantages and disadvantages of rotational CARS in comparison with vibrational CARS for IC engine measurements are discussed.
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| 2. |
- Bengtsson, Per Erik, et al.
(författare)
-
Rotational cars thermometry in sooting flames
- 1992
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Ingår i: Combustion Science and Technology. - : Informa UK Limited. - 0010-2202 .- 1563-521X. ; 81:1-3, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- Coherent anti-Stokes Raman scattering of pure rotational transitions, rotational CARS, is demonstrated as an efficient method for temperature determination in sooting flames. The dual broadband CARS approach was used to measure temperature profiles in premixed, sooting ethylene flames at atmospheric pressure by probing the nitrogen gas. The recorded spectra were of equally high quality in non-sooting and sooting flames with volume fractions of soot of up to 7 x 10 7 cm3 soot/cm3The advantages of rotational CARS in comparison with several other techniques for the measurement of temperatures in sooting flames, and the general applicability of the technique to different combustion conditions, are discussed. Potential limitations in the application of rotational CARS to sooting flames that are more heavily sooting than the ones investigated in this study, are outlined.
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| 3. |
- Marcus, Lars, 1962-, et al.
(författare)
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Ankeborgsvisioner
- 1994
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Ingår i: MAMA : magasin för modern arkitektur. - 1102-5409. ; :9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Marcus, Lars, 1962-
(författare)
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Ett liv i parodi
- 1992
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Ingår i: MAMA : magasin för modern arkitektur. - 1102-5409. ; :4
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
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| 6. |
- Marcus, Lars, 1962-
(författare)
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I stadens sken
- 1992
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Ingår i: MAMA : magasin för modern arkitektur. - 1102-5409. ; :2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Marcus, Lars, 1962-
(författare)
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I stadens våld
- 1991
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Ingår i: Nordisk arkitekturforskning. - 1102-5824. ; 1:1
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Tidskriftsartikel (refereegranskat)
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| 8. |
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| 9. |
- Marcus, Lars, 1962-
(författare)
-
Var skall samtalet få rum?
- 1993
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Ingår i: Aftonbladet.
-
Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Martinsson, Lars, et al.
(författare)
-
A test of different rotational Raman linewidth models: Accuracy of rotational coherent anti-Stokes Raman scattering thermometry in nitrogen from 295 to 1850 K
- 1993
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 99:4, s. 2466-2477
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Tidskriftsartikel (refereegranskat)abstract
- Rotational Raman linewidths calculated from three different models have been used in temperature measurements by rotational coherent anti-Stokes Raman scattering (CARS)—a semiclassical ab initio model, the modified exponential energy gap model (MEG), and the energy corrected sudden scaling law (ECS). Experimental rotational CARS spectra were generated, using the dual-broadband approach, in pure nitrogen at atmospheric pressure in a heat pipe in the temperature range from 295 to 1850 K. Below 1500 K, the temperatures evaluated using the ECS linewidths agreed with the heat-pipe temperatures to within 20 K. Above 1500 K, the errors in the evaluated temperatures increased steeply for all linewidth models, reaching errors of several hundreds of Kelvins at 1850 K. This behavior of the evaluated temperature is probably caused by the uncertainty in the values of the rotational Raman linewidths for high rotational states at high temperatures. This work therefore illustrates that rotational CARS can be used for experimentally studying Raman linewidths and in particular their dependence on temperature and rotational quantum number. The influence of different experimental parameters on the evaluated temperatures is discussed, and the spectral synthesis program is presented. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.
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