共查询到20条相似文献,搜索用时 15 毫秒
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A stationary cosmological model with rotation is constructed for the Ozsvath–Schucking metric where perfect fluid which is not comoving with the system is a source of the gravitational field. A nonstationary cosmological model for the Bianchi metric of type IX is also developed. This is characterized by expansion, rotation and acceleration. A co-moving with the system anisotropic liquid is a source of the gravitational field in this model. 相似文献
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A linear algebraic theory called the 'multiple Arnoldi method' is presented and realizes large-scale (order-N) electronic structure calculations with generalized eigenvalue equations. A set of linear equations, in the form of (zS - H)x = b, are solved simultaneously with multiple Krylov subspaces. The method is implemented in a simulation package ELSES (www.elses.jp) with tight-binding-form Hamiltonians. A finite-temperature molecular dynamics simulation is carried out for metallic and insulating materials. A calculation with 10(7) atoms was realized by a workstation. The parallel efficiency is shown up to 1024 CPU cores. 相似文献
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Beloslav Riečan 《Foundations of Physics》2000,30(10):1679-1686
A general algebraic system M is considered with two binary operations. The family of all measurable functions with values in the unit interval is a motivating example. A state is a morphism from M to the unit interval, an observable is a morphism from the family of Borel sets to M. A joint distribution of two observables is constructed. It is applied for the construction of the sum of observables and for a representation of conditional probability. 相似文献
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A model problem is considered for a radiator in the form of a circular disk with a given pressure jump at its surface. The radiator is inserted in a soft screen coinciding with the upper boundary of the Pekeris waveguide. A series expansion of the sound field in normal modes is obtained. A numerical analysis of the radiation impedance and its components that are responsible for the radiation into the waveguide and into the halfspace is carried out. 相似文献
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Yu. V. Vladimirova B. A. Grishanin V. N. Zadkov V. Biancalana G. Bevilacqua Y. Dancheva L. Moi 《Journal of Experimental and Theoretical Physics》2006,103(4):528-538
The interaction of a three-level atom in the A configuration with a frequency-modulated (FM) field is analyzed theoretically for the first time. The two-frequency model for solving the problem of frequency modulation spectroscopy of coherent dark resonances is described and analyzed for a three-level A system. The effectiveness of the two-frequency model is demonstrated by comparing the results obtained using this model with the results of solving the exact problem of interaction of a A system with an FM field, which can be solved by the density matrix method. It is shown that the simple two-frequency model corresponds to the exact solution and is in qualitative agreement with experimental data. 相似文献
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A novel interference microscope for three-dimensional (3D) imaging based on a wavelength-to-depth encoding technique is presented. Wavelength-to-depth encoding is realized by use of a diffractive lens and wavelength tuning. A high depth resolution of 0.71 mum is obtained with 0.90-N.A. objective lenses. Experimental measurements of a four-level grating are presented, and the results are found to be comparable with those obtained with a Dektak profilometer and a similar interference microscope that uses mechanical depth scanning. The system is promising for fast, noncontact, high-resolution 3D imaging. 相似文献
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A secondary ion mass spectrometer built around a modified high-dose ion implanter is used to study secondary ion emission in metals over a wide range of primary beam energies. The implanter generates ion beams with energies of up to 150 keV and a substrate current to 30 μA. A modified MX7304A monopole mass spectrometer is applied as an analyzer of secondary ions with mass numbers of up to 400 with a resolution of 1 M at a level of 10% of the peak height. The detection limit for iron is 6.5 ppm. The analyzer is equipped with a small-size filter separating secondary ions in energy. The relative emission intensities of the secondary monatomic and cluster ions of copper for different primary ion beam parameters are studied. 相似文献
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利用软件EVAP-COND,模拟对比了在室内换热器中分别采用R22与R410A制冷剂时冷凝器的性能随支路数的变化,结果表明:室内换热器作为冷凝器时,R410A的换热量比R22的要大,换热量的差别是由两排管共同造成的,两排管中R410A的换热量都比R22的要大;随支路数的增多,第一排管对冷凝器换热量差值的影响越来越显著,而第二排管的影响逐渐减弱;第一排管换热量的差别主要受传热系数的影响,而第二排管受传热温差和传热系数的综合影响。因此,支路增多时制约R410A和R22冷凝器换热量差别的因素,从传热温差和传热系数共同作用逐渐转变为传热系数起主导作用。 相似文献
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A low-truncation-error scheme for a step-index profile is applied to analysis of a three-dimensional waveguide with the aid of the alternating-direction implicit method. The propagation constants of a single and a coupled rib waveguide are analyzed by use of the imaginary distance procedure. A fast convergence rate, which is not obtainable with the conventional second-order schemes, is realized, leading to highly accurate evaluation of the coupling length. A reduction in discretization error is also demonstrated in the beam-propagation analysis of a tilted rib-waveguide coupler. 相似文献
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A crisis in a Duffing--van del Pol system with fuzzy
uncertainties is studied by means of the fuzzy generalised cell
mapping (FGCM) method. A crisis happens when two fuzzy attractors
collide simultaneously with a fuzzy saddle on the basin boundary as
the intensity of fuzzy noise reaches a critical point. The two fuzzy
attractors merge discontinuously to form one large fuzzy attractor
after a crisis. A fuzzy attractor is characterized by its global
topology and membership function. A fuzzy saddle with a complicated
pattern of several disjoint segments is observed in phase space. It
leads to a discontinuous merging crisis of fuzzy attractors. We
illustrate this crisis event by considering a fixed point under
additive and multiplicative fuzzy noise. Such a crisis is fuzzy
noise-induced effects which cannot be seen in deterministic
systems. 相似文献
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在生命活动中,金属离子扮演了非常重要的角色.微丝切割蛋白(adseverin)需要钙离子的活化才能行使其切割肌动蛋白微丝的功能.本文通过基于原子力显微镜的单分子力谱研究了微丝切割蛋白C端末的A6亚基在结合钙离子前后的力学解折叠机理.实验结果显示:在未结合钙离子时,A6的解折叠表现为两态过程;在结合钙离子后A6力学稳定性显著提高;同时,钙离子的结合使得A6解折叠过程中出现稳定的中间态.通过对中间态的链长的分析,我们推测了中间态对应着A6的N端部分解折叠.而这一部分的解折叠可以使得掩藏在该结构后的A5亚基中肌动蛋白微丝结合位点暴露,从而促使微丝切割蛋白执行功能.我们的实验结果为理解微丝切割蛋白的工作原理提供了新的实验证据. 相似文献
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V. P. Maslov 《Physics of Wave Phenomena》2015,23(2):81-95
A distribution corresponding to classical thermodynamics is constructed. The concept of degrees of freedom is generalized and a concept of temperature-dependent number of collective degrees of freedom is introduced. A relationship between the theory of numbers and mesoscopic physics is established. A geometric interpretation of spinodal as a curve of maximum entropy and as a catastrophe in a quasi-static Caratheodory process is given. A concept of local ideal gas is introduced. The phase transition of fluids to a dispersed system is determined. The distribution obtained is numerically compared with the distribution for a van der Waals gas in the Hougen-Watson diagram. 相似文献
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Yu. B. Kudasov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(2):172-175
A model for electron transport through a single molecule with two electronic states, one of which is strongly hybridized with contacts and the other is localized, has been investigated. A solution for this model in the limit of strong intramolecular Coulomb interaction is found. A mechanism of negative differential resistance caused by strong intramolecular correlations is revealed. 相似文献
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Hongfu Li Zhong-Lian Xie Wenxiang Wang Yong Luo Pinzhong Du Xue Den Huajun Wang Sheng Yu Xinjian Niu Li Wang Shenggang Liu 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2003,31(2):264-271
A systematic theoretical and experimental study on a 35-GHz 45-kV third-harmonic gyrotron with a permanent magnet system is presented in this paper. A complex cavity with gradual transition and a diode magnetron injection gun (MIG) are employed in the gyrotron. A self-consistent field nonlinear theoretical investigation and numerical simulation for electron beam interaction with RF fields are given. The diode MIG is simulated numerically utilizing our code in detail. The permanent magnet system provided the maximum axial magnetic field of about 4.5 kG in the cavity region of the gyrotron. The Ka band third-harmonic complex cavity gyrotron with a permanent magnet system has been designed, constructed, and tested. A pulse output power of 147.3 kW was obtained at a beam voltage of 45 kV with beam current of 32.2 A, corresponding to an efficiency of 10.2%. 相似文献
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It is widely believed that when two discrete time chaotic systems are coupled together then there is a contraction in the phase space (where the essential dynamics takes place) when compared with the phase space in the uncoupled case. Contrary to such a popular belief, we produce a counter example--we consider two discrete time chaotic systems both with an identical attractor A, and show that the two systems could be nonlinearly coupled in a way such that the coupled system's attractor persists strongly, i.e., it is A?×?A despite the coupling strength is varied from zero to a nonzero value. To show this, we prove robust topological mixing on A?×?A. Also, it is of interest that the studied coupled system can exhibit a type of synchronization called generalized partial synchronization which is also robust. 相似文献
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A. A. Parshintsev E. S. Soldatov V. V. Kashin V. V. Kolesov S. V. Krupenin A. N. Reshetilov 《Bulletin of the Russian Academy of Sciences: Physics》2014,78(2):144-148
A planar topology for a nanoelectronic transducer based on glucose oxidase is designed for use in an enzymatic biosensor. Electromigration is used to create 5-nm gaps in Au nanowires. A method for the chemical modification of a silica surface with epoxysilane is developed and glucose oxidase is immobilized on the surface of a support by means of linking molecules. A technique for biochemical signal registration is developed. The eelectric response of the biosensor with glucose in a test solution and the dependence of this response on the glucose concentration are investigated. 相似文献
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Alessandra Berretta Paolo Cristarella Orestano Sara Cutini Stefano Germani Isabella Mereu Michele Punturo Gino Tosti 《Annalen der Physik》2024,536(2):2200144
The discovery of a short gamma-ray burst (GRB), GRB170817A, in association with a gravitational wave (GW) and a bright kilonova started a new era in the high-energy astrophysics. The observation of GRB170817A and more recently, GRB200826A and GRB211211A, a short and a long burst, respectively, with a possible kilonova, reinforce the concern about new ways of classification. For this reason, a new machine learning technique is applied to Swift-BAT data, searching for morphological similarities in the light curves. The resulting map is characterized by two distinct groups, although still correlated with standard T90 duration. Since a jet viewed off-axis could explain the emission from GRB170817A, the modeling of this kind of sources is of great importance. A public code called JetFit, based on the “boosted fireball” model, is applied to fit Swift-XRT afterglow light curves of short and long GRBs, with known red-shift, from 2005 to 2021. JetFit does not model the flaring activity. For this purpose, a new technique to remove the time flaring phases, is developed. This analysis provides a comprehensive study of the prompt and of the afterglow phase, trough the study of the best-fit parameters. 相似文献