| 1. |
- Sundqvist, Bertil, et al.
(author)
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Physical properties of pressure polymerized C60
- 1996
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In: Fullerenes: Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials, volume 3. - Pennington, NJ : The Electrochemical Society. - 1566771625 ; , s. 1014-1028
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Conference paper (peer-reviewed)abstract
- We present in this paper an overview of the physical properties of the high pressure polymerized C60 phase commonly known as "soft fcc". This phase has been studied by several methods over wide ranges in temperature T and/or pressure, p. We present here experimental information about the specific heat capacity, the thermal expansion coefficient, the lattice structure, and the thermal conductivity, and we also show results obtained by NMR and Raman spectroscopy. All data presented agree with the accepted model that the individual molecules in this phase are covalently bound to form linear molecular chains. In particular, the NMR data show clearly the presence of covalent bonds, and the Raman data exhibit several new lines at very low energies connected with chain vibrations. Thermal conductivity data obtained during polymerization show both the time dependence of the process and that polymerization occurs at lower p and T than observed previously for this phase.
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| 2. |
- Berndtsson, Ronny, et al.
(author)
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Soil water and temperature patterns in an arid desert dune sand
- 1996
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In: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 185:1-4, s. 221-240
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Journal article (peer-reviewed)abstract
- Under arid natural conditions, soil water content governs and limits the number and size of perennial plant species. Thus, plant-available soil water is the main constraint for sustainable control of desert encroachment. To evaluate possibilities for re-vegetation of bare sand surfaces, soil water and temperature patterns for typical sand dunes in a desert climate were investigated. Bare and vegetated soil transects were selected for observation of soil water content and temperature. The investigated soil transects covered crest-to-crest spacings (about 60 m horizontally and 15 m vertically) in a shifting sand dune area. Observations were made at Shapotou field research station bordering the Tengger Desert in Northwestern China. The paper presents two-dimensional properties of soil water content (0.1-3.0 m depth) and temperature (0-1.0 m depth) before and after rainfall. Rainfall (15-22 mm) affected soil water distribution down to 1.5-2.0 m and temperature distribution down to 1.0 m. Soil water appeared to be transported through the apparently highly pervious and homogeneous sand along the dune slopes. High water contents and, thus, infiltration occurred mainly at the non-sloping parts, i.e. the dune crests and bottoms. Rainfall changed the temperature patterns from a mainly horizontally layered appearance before the rainfall to increasingly vertically shaped patterns.
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| 3. |
- Juslin, Peter, et al.
(author)
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Can overconfidence be used as an indicator of reconstructive rather than retrieval processes?
- 1995
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In: Cognition. - 0010-0277 .- 1873-7838. ; 54:1, s. 99-130
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Journal article (peer-reviewed)abstract
- In a recent paper Wagenaar (1988) suggested that overconfidence can be used as an indicator of reconstructive processes which allow responses based on inference to be distinguished from responses based on retrieval. The ecological models (Björkman, in press; Gigerenzer, Hoffrage, & Kleinbölting, 1991; Juslin, 1993a, 1993b, 1994) provide a more positive view of the calibration of reconstructive responses. In this paper we compare these two views and argue that overconfidence cannot be considered a reliable indicator of reconstructive processes since people may be well calibrated for tasks that require inference, provided that tasks are selected in an unbiased manner. Instead, we discuss two different models: the response-independence model which is appropriate to retrieval, and the response-dependence model which applies to inference. These two models predict different distributions of solution probabilities and they therefore provide a criterion by which we can distinguish between direct retrieval and reconstruction. In two empirical studies modelled after Experiment 1 in Wagenaar's (1988) paper it is shown that calibration can be very similar and quite reasonable both for tasks that are dominated by inference and tasks that are dominated by retrieval processes. In Experiment 2 we show that the two conditions nevertheless differ in regard to the distributions of solution probabilities in the manner predicted by the two response models presented in the paper. It is proposed that the issue of which is the most appropriate interpretation of solution probabilities is neglected, and that the criterion should be of interest also to applications outside the domain of calibration research.
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| 4. |
- Lagö, Thomas L, et al.
(author)
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Active vibration reduction in a light high speed train bogie
- 1998
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Conference paper (peer-reviewed)abstract
- Vibration induced sound in the car of a light high speed train is of great interest since the light structure makes it more resonant. Low weight is important and and the aim is to decrease the weight of future trains significantly, compared to the X2000. Classical sound attenuation techniques are good for higher frequencies but active techniques are more suitable when lowering the low frequency induced noise in the car. This work therefore addresses a problem that is likely to occur in future trains, due to the decreased weight. The sleepers are a dominant excitation source for this case, and this implies a periodic excitation of 85 Hz when the train is running at 200 km/h. The sleeper frequency excitation will be an even larger problem when the car has a lower weight as well. This paper describes an active vibration isolation, or damping, where the goal is to reduce the sound inside the car due to the sleeper frequency excitation not the vibrations levels. Four actuators have been used and both an AVC as well as an ASAC control strategy has been tested and the results are presented. Tests have been performed on a full scale train in a lab as well as on track at approximately 200 km/h.
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| 5. |
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| 6. |
- Persson, Per-Axel, et al.
(author)
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The physical properties of high-pressure polymerized C60
- 1997
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In: Journal of Physics and Chemistry of Solids, volume 58, issue 11. - : Elsevier B.V.. ; 58:11, s. 1881-1885
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Conference paper (peer-reviewed)abstract
- We have studied the structural, thermophysical, and spectroscopic properties of polymeric C60 obtained by high pressure treatment at pressures and temperatures near 1 GPa and 600 K. We present here a brief overview of our results for the structural and thermophysical properties and a more detailed report on recent results obtained by Raman spectroscopy on both thin films, polycrystalline, and single crystal material. The results presented include a comparison between Raman results for photopolymerized and pressure polymerized thin films and a preliminary estimate of the binding energy of polymeric C60.
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| 7. |
- Persson, Per, et al.
(author)
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Active Control of Sleeper-induced Sound in a High Speed Train
- 1999
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Conference paper (peer-reviewed)abstract
- Vibration-induced noise in train cars is an area that receives a great deal of interest at the moment. Due to economical and environmental issues, manufacturers are cutting the weight-budget for future trains to achieve a lower total life-cycle cost. This has a negative impact on the interior noise and passenger comfort and to be competitive new methods to reduce the negative side effect are sought. This paper describes an active control approach to isolating the car from bogie vibrations in such a way that the noise inside the car is reduced. An active control system with four inertial mass actuators fitted to an experimental light weight bogie were used to control bogie vibrations and noise inside the car. Several tests were performed in both a lab environment and on track at full speed.
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| 8. |
- Persson, Per, et al.
(author)
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Active vibration reduction in a light weight high speed train bogie
- 1999
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Conference paper (peer-reviewed)abstract
- Vibration-induced noise in the car of train is of great interest since low weight is important, but makes the structure more resonant. One excitation source is the sleeper frequency which gives rise to a periodic excitation. This paper describes an approach to isolate the vibrations caused by the sleepers in such a way that the noise inside the cabin is reduced. An LMS algorithm with four inertial mass actuators fitted to the bogie with control microphones placed in the cabin. The tests were performed on an experimental light weight bogie fitted to a test car, in both lab environment and in full scale tests on track at full speed (200 km/h).
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