| 1. |
- Bååth, Lars, 1948-
(författare)
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Noise Spectra from Wind Turbines
- 2013
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Ingår i: Renewable energy. - Oxford : Pergamon Press. - 0960-1481 .- 1879-0682. ; 57, s. 512-519
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents observations of audio noise in frequency range 20e20 000 Hz from wind turbines. The observations were performed around the theoretically calculated 40 dBA noise perimeter around the wind turbine farm at Oxhult, Sweden. This paper describes a newly designed and constructed a field qualified data acquisition system to measure spectra and total noise level of sound from wind turbines. The system has been calibrated at SP Borås. It is shown that it has a flat frequency response and is linear with amplitude and time.The total noise level (as integrated 20e20 000 Hz) is shown to be below 35 dBA (below the reference background noise at 36 dBA) at a 10 m altitude wind speed of 4e5 m/s. The measurements were made along the theoretical 40 dBA border at 8 m/s.It is concluded that the theoretical 40 dBA border seems reasonable calculated if the manufacturer specifications are used to extrapolate the sound level to correspond to 8 m/s at 10 m. Our data indicate that a simple sound propagation model is sufficient since the sound level is more affected by the nearby environment than the large scale forest structure. Also, the large scale forestry structure is bound to change with time and the error bars of measurements on total sound level are about 1 dBA, which is larger than any fine tuning with a more sophisticated model. More care should be taken to model the reflections from walls and other obstacles close to the microphones.The distribution of the spectral noise level around the turbine farm suggests that the noise originates from individual wind turbines closest to the measurement location rather than from the wind turbine farm as a whole. The spectra show narrow band spectral line features which do not contribute signifi-cantly to the total noise at this level. The narrow band features are only detectable at very long inte-gration time and at 1 Hz spectral resolution. The spectral features are typical to originate from mechanical noise.The spectral acquisition method described in this paper can be used as a field qualified system for sound measurements in forest areas. The high spectral resolution is a viable remote diagnostic method for mechanical faults in the turbine machinery. Future work will concentrate on these two areas.
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| 2. |
- Lindqvist, Kent, 1948-, et al.
(författare)
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Evaluation of inter-organizational traffic injury prevention in a WHO safe community
- 2001
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Ingår i: Accident Analysis and Prevention. - 0001-4575 .- 1879-2057. ; 33:5, s. 599-607
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study was to examine the effect of a community-based injury prevention program on traffic injuries. A population-based quasi-experimental design was used with pre- and post-implementation measurements in an intervention and a control area. The program was based on inter-organizational participation in detecting and taking action against traffic injuries. The total relative risk for traffic injury in the study area showed only a tendency to decrease following program exposure (odds ratio 0.91, 95% confidence interval 0.81-1.02). No change in relative risk was observed in the control area. The analyses of program impact on injury severity showed that the relative risk for moderate injuries in the study area was reduced by almost half (odds ratio 0.59, 95% confidence interval 0.49-0.69), the risk for severe or fatal injuries remained constant (odds ratio 1.27, 95% confidence interval 0.80-2.02), and the risk for minor injuries increased (odds ratio 1.34, 95% confidence interval 1.13-1.59). The relative risk for moderate injuries was reduced by at least half for mopedists, cyclists, pedestrians, and those leaving or entering a motor vehicle. Community-based injury prevention can be a complement to national traffic safety programs. ⌐ 2001 Elsevier Science Ltd.
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| 3. |
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| 4. |
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| 5. |
- Needham, Paul, 1948-
(författare)
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Hydrogen Bonding : Homing in on a Tricky Chemical Concept
- 2013
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Ingår i: Studies in history and philosophy of science. - : Elsevier BV. - 0039-3681 .- 1879-2510. ; 44:1, s. 51-66
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Tidskriftsartikel (refereegranskat)abstract
- The history of the hydrogen bond provides a good example of the of an important chemical concept. It illustrates the interplay between empirical and theoretical approaches to the problem of delimiting what has proved to be quite an elusive notion, with chemists whittling away at the particular sorts of case with a view to obtaining a precise, unitary concept. Even though there is a return to a more theoretically inspired notion in more recent research, empirical characterisations remain a feature of the report of a Task Group recently set up by the IUPAC to reconsider the definition of the hydrogen bond, and this situation-by no means unusual for chemical concepts and principles-is unlikely to change in the foreseeable future. These developments are reviewed in this paper, which includes an extended discussion of the enormous significance hydrogen bonding has for the philosopher's standard example of a "natural kind", water. There is little to suggest a reduction to what philosophers of physics are pleased to call fundamental principles, and the details raise further questions about what essentialists could possibly have in mind when talking about the microscopic essence of water.
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| 6. |
- Needham, Paul, 1948-
(författare)
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Nagel’s Analysis of Reduction : Comments in Defence as Well as Critique
- 2010
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Ingår i: Studies in history and philosophy of modern physics. - : Elsevier BV. - 1355-2198 .- 1879-2502. ; 41:2, s. 163-170
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Tidskriftsartikel (refereegranskat)abstract
- Despite all the criticism showered on Nagel's classic account of reduction, it meets a fundamental desideratum in an analysis of reduction that is difficult to question, namely of providing for a proper identification of the reducing theory. This is not clearly accommodated in radically different accounts. However, the same feature leads me to question Nagel's claim that the reducing theory can be separated from the putative bridge laws, and thus to question his notion of heterogeneous reduction. A further corollary to the requirement that all the necessary conditions be incorporated in an adequate formulation of the putative reducing theory is that the standard example of gas temperature is not reducible to average molecular kinetic energy. As originally conceived, Nagel's conception of reduction takes no account of approximate reasoning and this failure has certainly restricted its applicability, perhaps to the point of making it unrealistic as a model of reduction in science. I suggest approximation can be accommodated by weakening the original requirement of deduction without jeopardizing the fundamental desideratum. Finally, I turn to briefly consider the idea sometimes raised of the ontological reducibility of chemistry.
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| 7. |
- Needham, Paul, 1948-
(författare)
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The Source of Chemical Bonding
- 2014
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Ingår i: Studies in history and philosophy of science. - : Elsevier BV. - 0039-3681 .- 1879-2510. ; 45, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Developments in the application of quantum mechanics to the understanding of the chemical bond are traced with a view to examining the evolving conception of the covalent bond. Beginning with the first quantum mechanical resolution of the apparent paradox in Lewis's conception of a shared electron pair bond by Heitler and London, the ensuing account takes up the challenge molecular orbital theory seemed to pose to the classical conception of the bond. We will see that the threat of delocalisation can be overstated, although it is questionable whether this should be seen as reinstating the issue of the existence of the chemical bond. More salient are some recent developments in a longstanding discussion of how to understand the causal aspects of the bonding interaction the nature of the force involved in the covalent link which are taken up in the latter part of the paper.
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| 8. |
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| 9. |
- Oliw, E, 1948-
(författare)
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Polyunsaturated C-18 fatty acids derivatized with Gly and Ile as an additional tool for studies of the catalytic evolution of fungal 8-and 9-dioxygenases
- 2018
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Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : ELSEVIER SCIENCE BV. - 1388-1981 .- 1879-2618. ; 1863:11, s. 1378-1387
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Tidskriftsartikel (refereegranskat)abstract
- The fungal linoleate diol synthase (LDS) family contains over twenty characterized 8-, 9-, and 10-dioxygenases (DOX), usually fused to catalytically competent cytochromes P450. Crystal structures are not available, but indirect evidence suggests that linoleic acid enters the active site of 8R-DOX-LDS headfirst and enters 9S-DOX-allene oxide synthase (AOS) with the omega-end (tail) first. Fatty acids derivatized with amino acids can conceivably be used to study oxidation in tail first position by enzymes, which bind natural fatty acids headfirst. The results might reveal catalytic similarities of homologous enzymes. 8R-DOX-5,8-LDS oxidize 18:2n-6-Ile and 18:2n-6-Gly in tail first position to 9S-hydroperoxy metabolites, albeit with less position and stereo specificity than 9S-DOX-AOS. The oxygenation mechanism of 9S-DOX-AOS with antarafacial hydrogen abstraction at C-11 and oxygen insertion at C-9 was also retained. Two homologues, 8R-DOX-7,8-LDS and 8R-DOX-AOS, oxidized 18:2n-6-Ile and 18:2n-6-Gly at C-9, suggesting a conserved feature of 8R-DOX domains. 9R-DOX-AOS, with 54% sequence identity to 9S-DOX-AOS, did not oxidize the derivatized C-18 fatty acids. 9Z,12Z-16:2, two carbon shorter than 18:n-6 from the omega-end, was rapidly metabolized to an alpha-ketol, but 7Z,10Z-16:2 was not a substrate. An unsaturated carbon chain from C-1 to C-8 was apparently more important than the configuration at the omega-end. 8R-DOX-LDS and 9R-DOX-AOS may thus bind 18:2n-6 in the same orientation. The oxidation of 18:2n-6 in straight or reverse head-to-tail positions illustrates evolutionary traits between 8- and 9-DOX domains. Fatty acids derivatized with amino acids provide a complementary tool for the analysis of evolution of enzymes.
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| 10. |
- Rahm, Lars, 1948-
(författare)
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On the thermal adjustment of an almost-enclosed fluid region with through-flow
- 1986
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310 .- 1879-2189. ; 29:10, s. 1479-1485
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of a heat-up process in a horizontally enclosed fluid region, with an imposed through-flow and subject to weak thermal forcing, is investigated. Based on a boundary layer approach, a simple one-dimensional model for the interior fluid region is derived. The predicted response of the temperature field agrees well with numerical solutions of the corresponding undegenerate one-dimensional problem. The analytical results are in reasonably close agreement with numerical results presented in a companion paper by Hyun and Hyun (Int. J. Heat Mass Transfer 29, 1487–1493 (1986)).
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