| 1. |
- Hegelund, F, et al.
(author)
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The infrared spectrum of isothiazole in the range 600-1500 cm(-1), including a high-resolution study of the v(11)(A ') band at 818cm(-1) and the v(16)(A '') band at 727cm(-1), together with ab initio studies of the full spectrum
- 2004
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In: Molecular Physics. - : Informa UK Limited. - 1362-3028 .- 0026-8976. ; 102:14-15, s. 1583-1595
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Journal article (peer-reviewed)abstract
- The gas-phase high-resolution infrared spectrum of isothiazole in the range 600-1500 cm(-1) has been recorded, and revised band centres obtained for a number of vibrations. An analysis of the nu(11)(A') band at 818 cm(-1) and the nu(16)(A") band at 727cm(-1) has been performed, using the Watson Hamiltonian, A-reduction, IIIr representation. These were combined with previous microwave spectral data to provide combined analyses for rotational constants and quartic centrifugal distortion constants Delta(J), Delta(JK), Delta(K), delta(J) and delta(K). These extend the knowledge derived from previous microwave and IR spectral studies. The equilibrium structures and the derived harmonic frequencies were calculated by ab initio methods, using a variety of basis sets with MP2, MP4 and CCSD(T) methods, and a comparison of these with experimental data is discussed. At a pragmatic level, the closest correlation of the rotational constants with experiment is not obtained with the most sophisticated methodology. Similarly, the vibration frequencies and intensities also vary strongly with the procedure. In particular, we found that the cc-pVTZ + MP2 results probably provide the best numerical comparison with experimental IR data for this molecule.
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| 2. |
- Aleksandrov, D., et al.
(author)
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Halo excitations in fragmentation of He-6 at 240 MeV/u on carbon and lead targets
- 2000
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In: Nuclear Physics A. - 0375-9474. ; 669:1-2, s. 51-64
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Journal article (peer-reviewed)abstract
- Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while the dipole mode is dominating in Coulomb dissociation. Neither theoretically predicted new resonance states in He-6 nor nuclear excitation of a dipole mode were found. Direct evidence has been obtained for strong suppression of Coulornb post-acceleration in direct Coulomb breakup in a lead target.
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| 3. |
- Sjöberg, Jonas, 1964, et al.
(author)
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Iterative controller optimization for nonlinear systems
- 2003
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In: Control Engineering Practice. - 0967-0661. ; 11:9, s. 1079-86
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Journal article (peer-reviewed)abstract
- Recently, a data-driven model-free control design method has been proposed in Hjalmarsson et al. (Proceedings of the Conference on Decision and Control, Orlando, FL, 1994, pp. 1735–1740; IEEE Control Systems Mag. 18 (1998) 26) for linear systems. It is based on the minimization of a control criterion with respect to the controller parameters using an iterative gradient technique. In this paper, we extend this method to the case where both the plant and the controller can be nonlinear. It is shown that an estimate of the gradient of the control criterion can be constructed using only signal-based information obtained from closed-loop experiments. The obtained estimate contains a bias which depends on the local nonlinearity of the noise description of the closed-loop system which can be expected to be small in many practical situations. As a side effect the linear model-free control design method is reobtained in a new way.
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