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[en] This paper proposes the principle of SMES capacity determination for power system stable operation. Adopting the energy function method, the mechanism of SMES damping power oscillation in the classical single-machine infinite-bus (SMIB) system is analyzed. The released kinetic energy during disturbance is the original of power system oscillation, which is taken as the principle of SMES capacity determination. Then, the influence of fault type, fault position, and fault clearing time on the SMES capacity determination are discussed. Using MATLAB simulation, the principle of SMES capacity determination is evaluated.
[en] In this paper the authors' recently developed non-perturbative open-shell theory (MuKherjee et al. Molec. Phys; 30: 1861(1975) and Pramana; 4: 247(1975)) is adapted for 'direct' evaluation of ionisation potential and excitation energies. Separating the 'core' contribution from the 'valence' part through the use of a multiple-cluster-expansion operator, the method provides a systematic way of including various core-valence interaction and core relaxation components. MF orbitals have been used as the basis for facilitating detailed comparison of the method with perturbative and propagator techniques. It has been shown that the method encompasses all the important second-order contributions of the latter formalisms and certain other classes of diagrams in a compact manner. An application to a simple 4π electronic problem is discussed to illustrate how this method works for real systems. (author)
[en] Full text: The line width of angle resolved photoemission spectra from 2D-and 3D-valence bands in Bi(111) have been analyzed for excitation energies ranging from 8 eV to 100 eV. Model calculations show that the 2D- line width is independent of the final state broadening while the energy widths of transitions from a 3D-band are a function of the initial and final state widths as well as the respective band velocities. Thus detailed information about the band structure can be extracted from a line width analysis. Fig. 1 shows the spectral width of transitions from a 2D-band (filled circles) located at 0.4 eV and a 3D-band (open circles) located at ∼ 2.5 eV binding energy in Bi(111) as a function of final state energy. The minima in the measured line widths of the 3D-band coincide with the high symmetry points of the bulk Brillouin zone reflecting the fact that the initial state band velocity is zero there which minimizes the contributions to the measured line width. At these points the line width approaches the extrapolated values of the monotonically increasing line widths of the 2D-band. Additional variations in the line widths between symmetry points, indicated by the vertical arrows, are associated with avoided crossings in the final state band structure, which can be observed as primary and as secondary cone emission feature in the spectra. These results and the ramifications of the linear increase in the 2D-line width with the final sate energy will be discussed
[en] Vibrational excitation: The previous evaluation by Itikawa was based on an earlier evaluation by Brunger, Buckman, and Elford. Since these evaluations, new and more accurate experimental data have been published. For the vibrational excitation from the ground v=0 to the first excited level v=1 of N2, the recommended differential cross-sections are the ones measured by M. Allan. In this study, the differential cross-section for the v=0 → v=1 excitation was measured for scattering angles q=45o, 135o, and 180o for energies between 0.3 and 5.5 eV. The measured cross-section was not resolved rotationally, i.e. a sum over all rotational levels has been measured. The region of resonances between 1.9 and 3.7 eV is well resolved. The same study gave also the differential cross sections for the v=0 → v=1 excitation as a function of the scattering angle for several values of scattering energies, E=0.8, 1.988, and 5 eV. Rotational excitation: The previous evaluation by Itikawa for rotational excitation from j=0 → j=2 and from j=0 → j=4 used the data from an earlier evaluation by Brunger, Buckman, and Elford, which was based on swarm experiment data. Since these evaluations, another accurate theoretical calculation by Sulc et al. has been published. The resulting cross section for the j=0 → j=2 transition is in good agreement with the previous evaluation for energies <1 eV. Therefore, we recommend to keep the data recommended by Itikawa for the j=0 → j=2 and j=0 → j=4 transition. New measurements and/or theoretical calculations of the rotational excitation of N2 are needed for low (<1 eV) and higher (>1 eV) energies starting with ground and excited rotational level of N2
[en] The Kitaev-Heisenberg model is source of a topological quantum spin liquid with Majorana fermions and gauge flux excitations as fractional quasiparticles. The material -RuCl is composed of weakly van der Waals bound honeycomb layers of edge sharing RuCl octahedra which has recently emerged as a prime candidate for realising such physics. We studied -RuCl by means of thermal transport measurements, a valuable tool to probe elementary excitations of systems with low dimensional spin structure. While the in-plane, longitudinal heat transport is governed by heat conduction of phonons that strongly scatter off the magnetic excitations present in the system, studying the thermal Hall effect (Rhighi-Leduc effect) opens up a new path towards detecting a direct contribution of unconventional magnetic excitations to entropy transport. We have observed a sizeable transversal heat conductivity , the agreement of which with the theoretical predictions for the pure Kitaev model being suggestive of heat transport by fractionalised quasiparticles in -RuCl.
[en] We investigate the influence of low-energy recoils with respect to the electronic excitation of solids generated in atomic collision cascades. It is found that the electronic friction experienced by recoil atoms moving with kinetic energies below 10 eV contributes substantially to the total excitation energy dissipated into electronic degrees of freedom. The collision dynamics, on the other hand, remain virtually unchanged if the friction loss of these particles is switched on or off. This is illustrated by looking at the yield, emission sites and energies of sputtered surface atoms
[en] The International conference dedicated to the ninetieth anniversary of academician S.A. Azimov 'Fundamental and applied problems of physics' was held on 18-19 November, 2004 in Tashkent, Uzbekistan. Specialists discussed various aspects of modern problems of relativistic nuclear physics and physics of atomic nuclei, solid state physics, various applications of new materials. More than 150 talks were presented in the meeting. (k.m.)
[en] The hole-pairing problem at the dilute limit on low-dimensional bipartite and non-bipartite lattices is studied by means of the generalized Hubbard model, in which on-site (U), nearest-neighbor (V), and assited-hopping (Δt) terms are considered. The problem is [dressed by mapping the original many-body problem onto a tight-binding one in a higher-dimensional space. It is found that there is a small region around Δt/t0 = 0.5, where the pairing of holes is enhanced and non-pairing of electrons exists. Pairing phase diagrams are analyzed for linear, square and triangular lattices, in comparison with those results obtained from the extended Hubbard model. (orig.)
[en] The conference 'Optical research methods in modern physics' was held on 7-8 May, 2008 in Tashkent, Uzbekistan. The conference was dedicated to such issues as theory and experimental study of scattering in various media, generation and transformation of laser radiation, magnetooptical phenomena, interferometry and solid state physics improving the efficiency of photoelectric cells, obtaining new semiconductor materials for optical and photo-electronic devices and detectors etc. Over 90 talks were presented in the meeting. (k.m.)