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排序方式: 共有3143条查询结果,搜索用时 15 毫秒
981.
N. Erdmann V. Sebastian V.N. Fedoseyev M. Hannawald G. Huber T. Kautzsch K.-L. Kratz V.I. Mishin M. Nunnemann G. Passler N. Trautmann 《Applied physics. B, Lasers and optics》1998,66(4):431-433
1 =228.8 nm). Laser light with an average power of 2 mW was obtained after frequency tripling and was successfully used for
RIS test measurements on cadmium with a time-of-flight mass spectrometer. The eight stable Cd isotopes could be identified
unambiguously.
Received: 6 October 1997 相似文献
982.
We consider the exact null controllability problem for the semi- linear heat equation with dissipative nonlinearity in a bounded domain of Rn . The main result of the article asserts that if the nonlinearity is even mildly superlinear, then global null controllability in an arbitrarily short time fails; instead we provide sharp estimates for the controllability time in terms of the size of the initial data. 相似文献
983.
984.
985.
Sebastian Reich 《BIT Numerical Mathematics》1996,36(1):122-134
Recent observations [5] indicate that energy-momentum methods might be better suited for the numerical integration of highly oscillatory Hamiltonian systems than implicit symplectic methods. However, the popular energy-momentum method, suggested in [3], achieves conservation of energy by a global scaling of the force field. This leads to an undesirable coupling of all degrees of freedom that is not present in the original problem formulation. We suggest enhancing this energy-momentum method by splitting the force field and using separate adjustment factors for each force. In case that the potential energy function can be split into a strong and a weak part, we also show how to combine an energy conserving discretization of the strong forces with a symplectic discretization of the weak contributions. We demonstrate the numerical properties of our method by simulating particles that interact through Lennard-Jones potentials and by integrating the Sine-Gordon equation.This work was partly supported by NIH Grant P41RR05969, DOE/NSF Grant DE-FG02-91-ER25099/DMS-9304268, and NSF GCAG/HPCC ASC-9318159. 相似文献
986.
Dirichlet integrals and the associated Dirichlet statistical densities are widely used in various areas. Generalizations of
Dirichlet integrals and Dirichlet models to matrix-variate cases, when the matrices are real symmetric positive definite or
hermitian positive definite, are available [4]. Real scalar variables case of the Dirichlet models are generalized in various
directions. One such generalization of the type-2 or inverted Dirichlet is looked into in this article. Matrix-variate analogue,
when the matrices are hermitian positive definite, are worked out along with some properties which are mathematically and
statistically interesting. 相似文献
987.
Wavelength stabilized 980 nm uncooled pump laser modules for erbium-doped fiber amplifiers 总被引:2,自引:0,他引:2
Tomas Pliska Sebastian Arlt Rainer Bttig Tim Kellner Isabella Jung Nicolai Matuschek Pascal Mauron Bernd Mayer Stefan Mohrdiek Jürgen Müller Susanne Pawlik Hans-Ulrich Pfeiffer Berthold Schmidt Boris Sverdlov Stefan Teodoropol Jrg Troger Bernd Valk Christoph Harder 《Optics and Lasers in Engineering》2005,43(3-5):271
We review the development of wavelength stabilized 980 nm pump laser modules without active temperature stabilization for applications in erbium-doped fiber amplifiers. Operation over a wide temperature range with an output power exceeding 400 mW at an ambient temperature of 70°C is demonstrated. The overall reliability of uncooled modules is estimated to be well below 500 FIT at all operating conditions. Such devices are made possible by continuous development and steady improvement of the pump laser chip, the optimization of the fiber Bragg grating stabilization scheme, careful design of the module package, and extended reliability analysis on the basis of stress tests as well as field data. 相似文献
988.
Sebastian Zeck 《Fluid Phase Equilibria》1991,70(2-3):125-140
Phase equilibrium thermodynamics is one of the most important fundamental sciences for process development in the chemical industry. The outstanding results achieved by thermodynamics in the last decades have let to a profound change in working methods for the development of thermal separation processes. However, there remains a large number of unsolved problems in the field of phase equilibrium thermodynamics which often represent a significant restriction to process development for the chemical engineer. Current deficiencies are illustrated with some significant examples and desired developments for the future are suggested. 相似文献
989.
Maria Martinez-Lara Jose A. Barea-Aranda Laureano-Moreno Real Sebastian Bruque 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(4):287-299
The layered acid solids of formula H3OUO2XO4· 3 H2O (X = As, P) intercalate aniline and benzidine arylamines, by protonation of the guest molecules. The intercalates maintain the original laminar structure.The insertion of aniline and benzidinein the metal derivativesM(UO2XO4)2·n H2O (M = Cu, VO, Fe) requires rather drastic conditions. Near and medium infrared spectra of intercalates in which M = VO2+ and Cu2+, indicate that the polymerization and/or oxidation of sorbed amines occurs; however, the guest-host reactions for Fe2+-derivatives are of the acid-base type. 相似文献
990.
Compositions of saturated vapor and liquid phases at equilibrium were measured for hydrogen + carbon dioxide + 1-methylnaphthalene mixtures at 543 and 704 K over a pressure range of 50–250 atm. Measurements were made at three relative concentrations of hydrogen to carbon dioxide at each condition of temperature and pressure. A significant variation of the K-value of 1-methylnaphthalene with gas composition was observed in the high pressure region. 相似文献