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171.
172.
微透镜阵列的铸塑复制技术 总被引:3,自引:0,他引:3
在光刻热熔成型以及电铸复制得到的微透镜阵列镍板基础上,采用静态铸塑技术,得到了高质量的PMMA微透镜阵列。本文介绍了静态铸塑的聚合反应理论基础、模具设计以及工艺过程。最后对微透镜阵列的复制精度进行分析,结果表明复制精度优于0.5μm. 相似文献
173.
This paper constructs a class of Harish-Chandra modules with multiplicity ≤1 of the two parameter deformation of Virasoro algebra and proves a classification theorem. 相似文献
174.
本文推导了自由电子激光器中光脉冲的时间进展方程,数值研究了它的定态解。给出了不同调谐参数和峰值增益参数时的本征值和同步失配的关系,以及不同耦合参数时的光脉冲形状。计算结果与Dattoli的超模理论结果作了比较。 相似文献
175.
混合单调算子的某些不动点定理与锥上的正不动点 总被引:2,自引:0,他引:2
给出在半序距离空间以迭代而得到的某些不动点定理的混合单调算子和在锥上某些非零不动点定理。 相似文献
176.
There're about 10^{11} neurons in the human brain.Through the synaptic junction, neurons have formed a highly complex network.And it is really important to figure out the information expressed in the network, which will contribute to the resolution of the prevention and diagnosis of cognitive disorder of human beings. This paper uses the schizophrenia and healthy controlled subjects' fMRI data to construct the brain network model, in order to explores abnormal topological properties of schizophrenics' brain network based on graph theory. When studying the human brain network information traditionally by the basement of graph theory, it's all assure that the human brain network model has invariance, so it takes the whole period of time series data in constructing human network
model, which is a kind static network. However, it's hard to ensure this because of the nonstationarity of fMRI functional time series data. Thus, when constructing human brain network model, we should take its time-variation into consideration, then construct a dynamic brain network. We can explore
the brain network information better. In this research, we segment the time series data, using time windows, to constructing dynamic brain network model,
then analyze it combined with the knowledge of graph theory, thereby reducing effects that the nonstationarity of fMRI functional time series data will
have. Comparing dynamic brain network of the schizophrenic patients with normal controls subjects' in different level, the results show that there are difference in single node property, group network property of schizophrenic patients and normal control subjects' whole brain dynamic functional connectivity network. The discovery of these difference in network topological properties has provide new clues for the further study on the pathological mechanism of schizophrenia. 相似文献
177.
By applying a cosine change of variable, the numerical solutionof Symm's integral equation on open arcs can be obtained inan effective way so that the influence of the singularitiesat the endpoints is eliminated. Both Galerkin and collocationmethods using a piecewise constant approximating space are analysed.The convergence of the approximate solutions and the superconvergenceof the single layer potential as well as some numerical resultsare presented. 相似文献
178.
An analysis of seismic attenuation in random porous media 总被引:1,自引:0,他引:1
LIU Jiong BA Jing MA JianWei & YANG HuiZhu Institute of Seismic Exploration School of Aerospace Tsinghua University Beijing China Research Institute of Petroleum Exploration & Development PetroChina Beijing 《中国科学:物理学 力学 天文学(英文版)》2010,(4)
The attenuation of seismic wave in rocks has been one of the interesting research topics, but till now no poroelasticity models can thoroughly explain the strong attenuation of wave in rocks. In this paper, a random porous medium model is designed to study the law of wave propagation in complex rocks based on the theory of Biot poroelasticity and the general theory of stochastic process. This model sets the density of grain, porosity, permeability and modulus of frame as random parameters in space, and only one fluid infiltrates in rocks for the sake of better simulation effect in line with real rocks in earth strata. Numerical simulations are implemented. Two different inverse quality factors of fast P-wave are obtained by different methods to assess attenuation through records of virtual detectors in wave field (One is amplitude decay method in time domain and the other is spectral ratio method in frequency domain). Comparing the attenuation results of random porous medium with those of homogeneous porous medium, we conclude that the attenuation of seismic wave of homogeneous porous medium is far weaker than that of random porous medium. In random porous media, the higher heterogeneous level is, the stronger the attenuation becomes, and when heterogeneity σ = 0.15 in simulation, the attenuation result is consistent with that by actual observation. Since the central frequency (50 Hz) of source in numerical simulation is in earthquake band, the numerical results prove that heterogeneous porous structure is one of the important factors causing strong attenuation in real stratum at intermediate and low frequency. 相似文献
179.
针对保参数方向构造过渡曲线曲面方法的不足, 构造了任意参数曲线曲面间既保持参数方向又具有形状可调性的C 1与C 2连续过渡曲线曲面。首先,基于2类带1个自由参数的调配函数,分别构造满足C 1与C 2连续的过渡曲线,并讨论基于能量优化模型的最佳过渡曲线构造问题;然后,将所提出的方法推广到过渡曲面的构造。 实例结果表明,2被过渡曲线曲面为任意参数曲线曲面时,利用该方法构造的过渡曲线曲面不仅与2被过渡曲线曲面的参数方向保持一致,而且可利用所带的自由参数对其形状进行调整。通过能量优化模型确定自由参数的取值,可获得尽可能光顺的过渡曲线曲面。 所提方法弥补了保参数方向构造过渡曲线曲面方法的不足,是一种实用的过渡曲线曲面构造方法。 相似文献
180.