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1997年, 第6卷, 第11期　刊出日期：1997-11-20 上一期    下一期

GENERAL

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NONLINEAR WAVES PROPAGATING IN AN INHOMOGENEOUS BLOOD VESSEL 段文山, 王本仁, 魏荣爵 1997 (11):  801-810.  doi: 10.1088/1004-423X/6/11/001 摘要 ( 0 )   PDF(271KB) ([an error occurred while processing this directive])   A model for describing blood pressure propagation wave in artery is proposed. Considering blood viscosity, slowly varying arterial parameters and arterial bifurcations, we obtain the dynamical equation of blood flow. We show that the blood viscosity attenuate the nonlinear blood wave amplitude mainly in small artery. On the other hand, the variation of arterial parameters (such as radius and Young's modulus) amplify the amplitude of the nonlinear blood wave in large arteries. We also investigate how the nonlinear blood wave (or a soliton) is reflected and transmitted at the arterial bifurcations. It can be concluded that the parameters at the bifurcation determine whether there is substantial reflection or not, but the transmission in each bifurcation is approximately the same as the incident wave. 相关文章 | 计量指标

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ALTERNATIVE APPROACH TO THE PHASE OPERATOR AND ITS PROPERTIES 段路明, 郭光灿 1997 (11):  811-821.  doi: 10.1088/1004-423X/6/11/002 摘要 ( 0 )   PDF(272KB) ([an error occurred while processing this directive])   By introducing a series of mathematical symbols and phase quantization condition, we give a new approach to the phase operator, which is defined directly in the conventionally-used infinite-dimensional state spaces. Properties of the phase operator and its expressions in some widely-used representations are given. As an example, phase properties of coherent states are analyzed based on this definition. 相关文章 | 计量指标

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A GROUP OF EXACT (3+1) DIMENSIONAL CYLINDRICALLY SYMMETRIC WAVE SOLUTIONS TO THE EINSTEIN GRAVITATIONAL FIELD EQUATION 唐孟希, 区智 1997 (11):  822-828.  doi: 10.1088/1004-423X/6/11/003 摘要 ( 0 )   PDF(181KB) ([an error occurred while processing this directive])   Starting with the diagonal spacetime metric tensor, the Einstein gravitational field equation is solved, and a set of exact (3+1) dimensional cylindrically symmetric wave solutions with two arbitrary functions are found. In these solutions all nonvanishing components of spacetime metric tensor are varying with the same propagating factor (ct-z) while the waves are travelling along z axis. The physical picture and the condition of positive energy density of the wave solutions are discussed. 相关文章 | 计量指标

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STRICT DERIVATION OF MEAN FIELD EQUATION FOR ONE-DIMENSIONAL TRAFFIC FLOW MODEL 王雷, 汪秉宏, 许伯铭 1997 (11):  829-836.  doi: 10.1088/1004-423X/6/11/004 摘要 ( 0 )   PDF(242KB) ([an error occurred while processing this directive])   A new analysis method is presented for the study of Fukui-Ishibashi deterministic one-dimensional traffic flow cellular automaton model of high speed car on highway. By using this method, the exact mean field equation describing the fundamental diagram curve of average traffic speed versus the car density on highway can be derived strictly. 相关文章 | 计量指标

ATOMIC AND MOLECULAR PHYSICS

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METHOD FOR THE STUDY OF FAST VIBRATIONAL RELAXATION OF MOLECULES USING SPECTROPHONE V.A.KAPITANOV, B.A.TIKHOMIROV, O.V.TIKHOMIROVA 1997 (11):  837-840.  doi: 10.1088/1004-423X/6/11/005 摘要 ( 0 )   PDF(126KB) ([an error occurred while processing this directive])   A technique for measuring the vibration translational relaxation time of molecular gases using the spectrophone is described. The technique is based on the measurement of the phase of natural oscillations of the microphone membrane as a function of pressure of the gas under study. These oscillations manifest themselves in a shape of the optoacoustic (OA) signal at low gas pressure in the OA cell when the absorbing molecules are excited by short laser pulses. As an example the results on the relaxation time of the v1+3v3 state of H2O molecule in H2O-H2O and H2O-air collisions obtained using the OA cell of various sizes are presented. 相关文章 | 计量指标

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IONIZATION POTENTIALS OF NICKEL CLUSTERS 罗成林 1997 (11):  841-847.  doi: 10.1088/1004-423X/6/11/006 摘要 ( 0 )   PDF(180KB) ([an error occurred while processing this directive])   The mean coordination numbers of some nickel clusters have been calculated for some proposed geometric structures for them, and their ionization potentials are obtained using an effective coordination-number model. It is shown that the mean effective-coordination number of all atoms of a cluster should be taken as a parameter to describe the d-band width of the cluster instead of mean effective coordination number of surface atoms. 相关文章 | 计量指标

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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EFFECTIVE-MASS THEORY FOR InAs/GaAs STRAINED SUPERLATTICES 李树深, 夏建白 1997 (11):  848-860.  doi: 10.1088/1004-423X/6/11/007 摘要 ( 0 )   PDF(342KB) ([an error occurred while processing this directive])   By using the recently developed exact effective-mass envelope function theory, the electronic structures of InAs/GaAs strained superlattices grown on GaAs (100) oriented substrates are studied. The electron and hole subband structures, distribution of electrons and holes along the growth direction, optical transition matrix elements, exciton states, and absorption spectra are calculated. In our calculations, the effects due to the different effective masses of electrons and holes in different materials and the strain are included. Our theoretical results are in agreement with the available experimental data. 相关文章 | 计量指标

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OPTIMUM DESCRIPTION FOR THE GRAIN ALIGNMENT IN PERMANENT MAGNETIC MATERIALS 高汝伟, 张德恒, 张建成, 李华, 王毅, 孟宪洪 1997 (11):  861-867.  doi: 10.1088/1004-423X/6/11/008 摘要 ( 0 )   PDF(231KB) ([an error occurred while processing this directive])   Two types of Gaussian function for describing the grain a lignment in NdFeB permanent magnetic materials are introduced and compared in this paper. The results show that when the degree of grain alignment is avorable, the theoretical results based on the “θ-type”Gaussian function are in a greement with those based on the “tan θ-type”Gaussian function in the var iation tendency of the distribution coefficients and the distribution curves. When the degree of grain alignment is not good, the two descriptions have a large difference from each other. The theoretical results based on the “tan θ-type” Gaussian function are in good agreement with the experiments in the grain alignment dependence of the coercivity. However, the obtained results based on the “θ-type”Gaussian function are not in agreement with the experiments. The“tan θ-type”Gaussian function can be used to describe the grain alignment of various degrees and is consistent with the common Gaussian function taking x as a variable. So it is an optimum function for describing the grain alignment. 相关文章 | 计量指标