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961.
A set of invariants describing the limit regimes of braking disk-type wound composite flywheels is suggested. The limit regime is determined by using a linear failure criterion. It is shown that, for generating short-time impulses of very high power, a set of small identical flywheels is more effective than one large flywheel with an equivalent mass. Particular examples illustrating the theory considered are discussed. 相似文献
962.
Abdel Raouf F. Elhefnawy Galal M. Moatimid Abd Elmonem Khalil Elcoot 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,86(2):63-91
The nonlinear electrohydrodynamic stability of
cylindrical interface, supporting surface charge, among two
conducting fluids is investigated. The two fluids are subjected to
a radial electric field. The analysis based on the multiple scale
technique. It is shown that the evolution of the amplitude is
governed by two partial differential equations. These equations
are combined to yield two alternate Schrödinger equations with
cubic nonlinearity. One of which calculates the nonlinear cutoff
electric field, separating stable and unstable disturbances, while
the other is used to analyze the stability of the system. The
stability criteria are analytically discussed and numerically
confirmed. Numerical calculations resulted in set of graphs to
indicate the stability picture of the considered system. 相似文献
963.
First order dynamic inclusions on time scales 总被引:1,自引:0,他引:1
F.Merdivenci Atici D.C. Biles 《Journal of Mathematical Analysis and Applications》2004,292(1):222-237
In this paper, we study existence of solutions of first order dynamic inclusions on time scales with general boundary conditions. Both the ∇-derivative and Δ-derivative cases are considered. Examples are presented to illustrate that the Δ-derivative case needs more restrictive assumptions. 相似文献
964.
L. Fatone M. C. Recchioni F. Zirilli 《Journal of Optimization Theory and Applications》2004,121(2):223-257
In this paper, we consider furtivity and masking problems in time-dependent three-dimensional electromagnetic obstacle scattering. That is, we propose a criterion based on a merit function to minimize or to mask the electromagnetic field scattered by a bounded obstacle when hit by an incoming electromagnetic field and, with respect to this criterion, we drive the optimal strategy. These problems are natural generalizations to the context of electromagnetic scattering of the furtivity problem in time-dependent acoustic obstacle scattering presented in Ref. 1. We propose mathematical models of the furtivity and masking time-dependent three-dimensional electromagnetic scattering problems that consist in optimal control problems for systems of partial differential equations derived from the Maxwell equations. These control problems are approached using the Pontryagin maximum principle. We formulate the first-order optimality conditions for the control problems considered as exterior problems defined outside the obstacle for systems of partial differential equations. Moreover, the first-order optimality conditions derived are solved numerically with a highly parallelizable numerical method based on a perturbative series of the type considered in Refs. 2–3. Finally, we assess and validate the mathematical models and the numerical method proposed analyzing the numerical results obtained with a parallel implementation of the numerical method in several experiments on test problems. Impressive speedup factors are obtained executing the algorithms on a parallel machine when the number of processors used in the computation ranges between 1 and 100. Some virtual reality applications and some animations relative to the numerical experiments can be found in the website http://www.econ.unian.it/recchioni/w10/. 相似文献
965.
966.
Unstable, short-lived BiH3 has been synthesized and investigated by rotational spectroscopy in the range 158 (J=1-0) to 1280 GHz (J=8-7). Quadrupole and spin-rotation hyperfine structures (eQq=584.676(96) MHz), and the A1A2 splitting of the K=3 ground state level, have been resolved. By merging the pure rotational data with 1764 ground state combination differences obtained from the analysis of high resolution Fourier transform infrared spectra of the ν1-ν4 bands [J. Mol. Spectrosc. (2004) (in press)] spanning J and K values up to 16 and 14, respectively, with 0?ΔK?9, the ground state rotational and centrifugal distortion constants up to octic and sextic terms for reductions A and B, respectively, have been determined. Of the reductions of the ground state rovibrational Hamiltonian, reduction B including ε rather than h3 as off-diagonal element is clearly favored. An experimental r0 structure of the very-near spherical oblate symmetric top BiH3, r(BiH)=178.82 pm and α(HBiH)=90.320°, has been deduced from the rotational constants B0=2.64160172(18) and C0=2.6010403(31) cm−1. The derived experimental re structure, re(BiH)=177.834(50) pm and αe(HBiH)=90.321(10)°, was determined. This is in excellent agreement with the most recent ab initio structure, re(BiH)=177.84 pm, and αe(HBiH)=90.12°. 相似文献
967.
A. V. Novikov D. N. Lobanov A. N. Yablonsky Yu. N. Drozdov N. V. Vostokov Z. F. Krasilnik 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):467
The dependence of photoluminescence spectra of structures with GeSi/Si(0 0 1) self-assembled nanoislands on growth temperature has been investigated. It was shown that the redshift of the island-related photoluminescence peak with a decrease of the growth temperature is associated with suppression of Si diffusion in the islands and an increase of Ge content in them. For the first time a photoluminescence signal from SiGe islands was observed at energies much lower than the Ge band gap. The energy position of the island-related photoluminescence peak is well described by the model of optical transition, which is indirect in real space. The photoluminescence signal at 1.55 μm from GeSi/Si(0 0 1) self-assembled islands was obtained up to room temperature. 相似文献
968.
The European Physical Journal C - We present the most recent high p T results from the CDF experiment using $p\overline{p}$ collisions at $\sqrt{s}=1.96~$ TeV produced at the Tevatron Collider at... 相似文献
969.
D. I. T. Fávaro D. Mafra V. A. Maihara L. Cuppari M. B. A. Vasconcellos S. M. F. Cozzolino 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(3):533-536
Having in mind the importance of Fe and Zn content in the diets of nondialyzed patients with chronic renal failure, diets
of 39 patients with ages varying from 18 to 79 years under a conservative treatment were analyzed by INAA. The 24-hour recall
method was used for sample collection. The content of proximate composition was also determined. The average daily dietary
intake was compared to the new recommended values by the Food and Nutrition Board. It was observed that the diets were deficient
for these elements and, therefore, there should be a nutritional follow-up to avoid possible negative effects.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
970.
F. Tercero J. A. López Fernández E. García L. de Haro M. C. Carter A. Barcia B. Galocha J. L. Besada 《International Journal of Infrared and Millimeter Waves》2003,24(5):669-681
The Beam Mode Expansion (BME) approach for corrugated conical feed horn plus meniscus lens is presented. This approach is useful for providing the radiation pattern as it propagates through an optical system. A developed theoretical model has been verified measuring near and far field of a built horn and lens. These results have been used for designing the optical system of a Cassegrain antenna at 100GHz using the fundamental Gaussian beam mode (GBM) of the new approach. Multimode analysis has been performed with the pre-designed system in order to test the fundamental GBM results. 相似文献