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991.
Bernhard Krötz 《Functional Analysis and Its Applications》2009,43(1):30-43
In this paper, we define a horospherical transform for a semisimple symmetric space Y. A natural double fibration is used to assign a more geometrical space Ξ of horospheres to Y. The horospherical transform relates certain integrable analytic functions on Y to analytic functions on Ξ by fiber integration. We determine the kernel of the horospherical transform and establish that the transform is injective on functions belonging to the most continuous spectrum of Y. 相似文献
992.
Dieter Fiems Stijn De Vuyst Sabine Wittevrongel Herwig Bruneel 《Annals of Operations Research》2009,170(1):113-131
In this contribution we investigate higher-order loss characteristics for M/G/1/N queueing systems. We focus on the lengths of the loss and non-loss periods as well as on the number of arrivals during these
periods. For the analysis, we extend the Markovian state of the queueing system with the time and number of admitted arrivals
since the instant where the last loss occurred. By combining transform and matrix techniques, expressions for the various
moments of these loss characteristics are found. The approach also yields expressions for the loss probability and the conditional
loss probability. Some numerical examples then illustrate our results. 相似文献
993.
Falk M. Hante Günter Leugering Thomas I. Seidman 《Applied Mathematics and Optimization》2009,59(2):275-292
We consider networked transport systems defined on directed graphs: the dynamics on the edges correspond to solutions of transport
equations with space dimension one. In addition to the graph setting, a major consideration is the introduction and propagation
of discontinuities in the solutions when the system may discontinuously switch modes, naturally or as a hybrid control. This
kind of switching has been extensively studied for ordinary differential equations, but not much so far for systems governed
by partial differential equations. In particular, we give well-posedness results for switching as a control, both in finite
horizon open loop operation and as feedback based on sensor measurements in the system. 相似文献
994.
Illarion Dorofeyev Harald Fuchs Katja Sobakinskaya 《Central European Journal of Physics》2005,3(3):351-375
Spectral characteristics of stochastic fields and their spatial derivatives in various planar structures composed by lossy
materials described by realistic dielectric functions are numerically calculated based on solutions to the problems of multipolar
electromagnetic fields in a plane layered geometry. A displacement of the maximum of the spectral power densities for spatial
derivatives of fluctuating fields to the high-frequency domain, a resonant increase in the density of states of the fluctuating
fields at the frequencies of interface excitations and interference modes for the radiative part of the spectra, the influence
of geometry on the density of states, and other peculiarities are found by numerical calculations and graphically demonstrated.
Interpretations of the above effects are provided. 相似文献
995.
Classical (Heisenberg) simulations show that the total magnetization of the lowest-energy states of clusters made of antiferromagnetically
coupled chromium atoms is planar, rather than collinear, depending on the arrangement of the atoms. Although the model Hamiltonian
is not restrictive, many cluster configurations of various numbers of atoms do not use all three directions for the spins.
This result confirms the conclusion drawn from the local-spin DFT calculation by Kohl and Bertsch that clusters of N≤13 have non-collinear magnetic moments. The present simulations show non-collinear spin ordering also for bigger clusters,
designed to be as spherical as possible following the bcc arrangement, when atoms interact both with the nearest and next-nearest neighbours. Depending on the signs of the coupling
constants frustration appears. The advantage of the discrete model, despite the simplicity, is that very large clusters and
magnetization at finite temperatures can be studied. This model predicts that clusters with specific numbers of atoms interacting
only with the nearest neighbours have collinear spins as in the bulk. We also apply the model to simulate the destruction
of the anti-ferromagnetic ordering by thermal fluctuations. This model shows no unique magnetization of mixed Fe
0.33
Cr
0.67, which is consistent with experimental observations. 相似文献
996.
Carlos Castro 《Foundations of Physics》2005,35(6):971-1041
We construct the Extended Relativity Theory in Born-Clifford-Phase spaces with an upper R and lower length λ scales (infrared/ultraviolet cutoff). The invariance symmetry leads naturally to the real Clifford algebra Cl (2, 6, R) and complexified Clifford ClC (4) algebra related to Twistors. A unified theory of all Noncommutative branes in Clifford-spaces is developed based on the Moyal-Yang star product deformation quantization whose deformation parameter involves the lower/upper scale
. Previous work led us to show from first principles why the observed value of the vacuum energy density (cosmological constant) is given by a geometric mean relationship
, and can be obtained when the infrared scale R is set to be of the order of the present value of the Hubble radius. We proceed with an extensive review of Smith’s 8D model based on the Clifford algebra Cl (1, 7) that reproduces at low energies the physics of the Standard Model and Gravity, including the derivation of all the coupling constants, particle masses, mixing angles, ....with high precision. Geometric actions are presented like the Clifford-Space extension of Maxwell’s Electrodynamics, and Brandt’s action related to the 8D spacetime tangent-bundle involving coordinates and velocities (Finsler geometries). Finally we outline the reasons why a Clifford-Space Geometric Unification of all forces is a very reasonable avenue to consider and propose an Einstein-Hilbert type action in Clifford-Phase spaces (associated with the 8D Phase space) as a Unified Field theory action candidate that should reproduce the physics of the Standard Model plus Gravity in the low energy limit. 相似文献
997.
Guido Gentile Vieri Mastropietro Michela Procesi 《Communications in Mathematical Physics》2005,256(2):437-490
We consider the nonlinear string equation with Dirichlet boundary conditions utt–uxx=(u), with (u)=u3+O(u5) odd and analytic, 0, and we construct small amplitude periodic solutions with frequency for a large Lebesgue measure set of close to 1. This extends previous results where only a zero-measure set of frequencies could be treated (the ones for which no small divisors appear). The proof is based on combining the Lyapunov-Schmidt decomposition, which leads to two separate sets of equations dealing with the resonant and non-resonant Fourier components, respectively the Q and the P equations, with resummation techniques of divergent powers series, allowing us to control the small divisors problem. The main difficulty with respect to the nonlinear wave equations utt–uxx+Mu=(u), M0, is that not only the P equation but also the Q equation is infinite-dimensional. 相似文献
998.
M. V. Yakunin G. A. Al’shanskii Yu. G. Arapov V. N. Neverov G. I. Harus N. G. Shelushinina O. A. Kuznetsov A. de Visser L. Ponomarenko 《Physics of the Solid State》2005,47(1):49-53
The structure of the quantum-well valence band in a Ge(111) two-dimensional layer is calculated by the self-consistent method. It is shown that the effective mass characterizing the motion of holes along the germanium layer is almost one order of magnitude smaller than the mass for the motion of heavy holes along the [111] direction in a bulk material (this mass is responsible for the formation of quantum-well levels). This creates a unique situation in which a large number of subbands appear to be populated at moderate values of the layer thickness d w and the hole concentration p s . The depopulation of two or more upper subbands in a 38-nm-thick germanium layer at a hole concentration p s = 5 × 1015 m?2 is revealed from the results of measuring the magnetoresistance in a strong magnetic field aligned parallel to the germanium layers. The destruction of the quantum Hall state at a filling factor ν = 1 indicates that the two lower subbands merge together in a self-formed potential profile of the double quantum well. It is demonstrated that, in a quasi-two-dimensional hole gas, the latter effect should be sensitive to the layer strain. 相似文献
999.
1000.
Antonino Marciano 《Czechoslovak Journal of Physics》2005,55(11):1479-1485
I summarize results recently obtained in collaboration with Amelino-Camelia, Bruno and Mandanici (preprint University of Rome
“La Sapienza”, August, 2005) that concern an analysis of the path of a massless particle in a q-de Sitter space-time and an approximation scheme suitable for the corresponding analysis in a quantum FRW Universe. On the
basis of some arguments in the quantum-gravity literature, the q deformation parameter is assumed to depend on both the Planck scale and the curvature, leading to results that are significantly
different from those of other studies of Planck-scale effects in cosmology, where the possibility of an interplay between
curvature and Planck scale was ignored.
Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005. 相似文献