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941.
Each convex planar set K has a perimeter C, a minimum width E, an area A, and a diameter D. The set of points (E,C, A1/2, D) corresponding to
all such sets is shown to occupy a cone in the non-negative orthant of R4with its vertex at the origin. Its three-dimensional cross section S in the
plane D = 1 is investigated. S lies in a rectangular parallelepiped in R3. Results of Lebesgue, Kubota, Fukasawa, Sholander, and Hemmi are used to
determine some of the boundary surfaces of S, and new results are given for the other boundary surfaces. From knowledge of S, all inequalities among
E, C ,A, and D can be found. 相似文献
942.
L. Martinovič 《Few-Body Systems》2005,36(1-4):167-171
We study three problems of the light-front field theory quantized in a finite volume with fields (anti-)periodic in x−: (a) microcausality by deriving an integral representation for the discrete Pauli-Jordan function; (b) surface terms violating Poincaré algebra; (c) a LF version of the Goldstone theorem. The first two problems are resolved by careful mathematical treatment. The third one illustrates the usefulness of DLCQ as an analytical scheme. 相似文献
943.
A. E. Mironov 《Functional Analysis and Its Applications》2005,39(3):240-243
We construct commuting rank 2 formally self-adjoint ordinary differential operators corresponding to a curve of genus 2. 相似文献
944.
A generalization of the Bloembergen-Shen model to Raman active molecules with an arbitrary number of normal modes was suggested. The generalized model was used to study Raman echo signal characteristics when a system of molecules was excited by pulses of widths up to one period of optical oscillations. It was shown that a large number of echo responses on Stokes and anti-Stokes components could arise even under a two-pulse action in a continuous monochromatic pumping field. The number of echo responses depended on the number of molecular normal modes and the geometry of measurements. At small exciting pulse “areas,” the echo responses whose Stokes and anti-Stokes components corresponded to normal vibrational modes of a molecule had the highest intensity, whereas the components formed by normal mode combinations were strongly suppressed. 相似文献
945.
M. De Falco F. De Giovanni C. Musella R. Schmidt 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):70-76
A subgroupH of a groupG is said to bepermutable ifHX=XH for every subgroupX ofG. In this paper the structure of groups in which every subgroup either is abelian or permutable is investigated.
This work was done while the last author was visiting the University of Napoli Federico II. He thanks the “Dipartimento di
Matematica e Applicazioni” for its financial support. 相似文献
946.
In this article, we define stochastic dynamics for a system coupled to reservoirs. The rules for forward and backward transitions are related by a generalized detailed balance identity involving the system and its reservoirs. We compare the variation of information and of entropy. We define the Carnot dissipation and prove that it can be expressed in terms of cyclic transformations. Lower bounds for partial dissipations are also studied, as well as the effect of switching off certain reservoirs. We also study the near degeneracy of the stochastic matrix, relate it to phase transitions and we show that the reduced dynamics on the set of phases is a permutation. Finally, we relate these concepts to heat, work and more generally to the dissipation and creation of resources, in general systems. 相似文献
947.
We prove that given a simply connected compact manifold M and a
closed manifold N, any map in the Sobolev space W
1,2(M,N) can be
approximated weakly by smooth maps between M and N.
Submitted: September 2002, Final version: November 2002. 相似文献
948.
V. P. Belousov I. M. Belousova A. S. Grenishin O. B. Danilov V. M. Kiselev A. V. Kris’ko A. A. Mak T. D. Murav’eva V. N. Sosnov 《Optics and Spectroscopy》2003,95(6):830-832
The possibility of lasing in the fullerene-oxygen-iodine system with optical excitation of fullerene is studied. Laser radiation with an energy of 25 mJ and a pulse duration of 5–10 ms is obtained. 相似文献
949.
M.B. Xu 《Applied Acoustics》2003,64(7):731-752
The forced vibration of an infinite elastic circular cylindrical shell filled with fluid is studied. Three methods are employed to analyze the forced vibration problem of this shell-fluid coupled system, that is, wave propagation approach (wave mode superposition), theorem of residues and a numerical integral method. In order to explain these methods more explicitly, before being used to investigate the vibration of an infinite fluid-filled elastic circular cylindrical shell, all these three methods are employed firstly to analyze the forced vibration problem of an infinite beam and an infinite elastic circular cylindrical shell in vacuo. Advantage and disadvantage of these three methods are discussed and their interesting relationship is revealed. That is, to any circumferential wavenumber and frequency of the external force, there is an unchangeable relationship between the general coordinates of various waves in the wave propagation approach and the residuals in the theorem of residues. 相似文献
950.
B. H. Schoch 《Progress in Particle and Nuclear Physics》2003,50(2):523-531
Experimental studies of the photomeson production on the nucleon provide an abundant amount of data to address key issues of its structure. Depending on the selected channels and kinematics, different aspects can be investigated. The measurements of charged channels at low t constitute a large part of the cross section and exhibit a special sensitivity of the meson cloud. These contributions can be strongly suppressed by using a polarized beam and target. Instead, the excitation of resonances are emphasized in this case. The choice of neutral channels in the final state shows also dominant sensitivities for resonance excitation. The sequential decay of resonances can be studied systematically for the first time. 相似文献