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101.
102.
Jeffrey M. Stubbs Donald C. Sundberg 《Journal of Polymer Science.Polymer Physics》2005,43(19):2790-2806
The morphological features of composite latex particles predominantly develop during the polymerization process and depend upon a significant number of variables. In this study, we have concentrated on the relative polarities of the two polymers in the particles and the rate at which we added the monomers during semibatch reactions containing the seed polymer latex. Our particular interest was to develop data that could reveal the extent of polymer phase separation as a function of the amount of monomer fed, and to characterize the morphology resulting from it. While TEM is the most common analytical technique employed, we show in this paper that modulated temperature DSC can generate data that allows us to follow the phase separation process as the monomer feed progresses. By considering the possibilities of having “phases” within the particles of pure polymer, homogeneously mixed (but nonequilibrium) polymers, gradient and interfacial polymer, we have been able to quite successfully simulate the DSC data. This results in quantitative estimates of the relative amounts of these “phases” and their polymer compositions. Combining these results with TEM photos showing the spatial characteristics of the morphology, we can achieve a much greater understanding of the physical structure of the composite latex particles. In many cases we find that phase separation is far from complete at the end of the reaction process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2790–2806, 2005 相似文献
103.
在数字信号传输系统中,正交复用QAM(OMQAM)是目前最有效的一种抗信道失真传输技术,但它对系统的定时偏移和载波相位误差非常敏感。本文基于高阶累积量技术,导出了一种新的OMQAM系统定时和载波相位的跟踪算法。计算机仿真证实了这一理论分析结果,并同原有的Hirosaki算法做了比较 相似文献
104.
We extend the geometrical theory of aberration for a self-imaging system to the case of two-dimensional oblique lattices. In our approach, the fundamental translation vectors of the lattice are not restricted in both length and orientation. Evaluating the disturbance of light through the oblique lattice under coherent illumination, we find the conditions of constraint which limit the self-imaging of the oblique lattice. Various types of oblique lattices are shown to obey the self-imaging conditions. We derive the equations to trace the optical paths of self-imaging rays and then analyze the ray aberrations which arise from the difference between the optical paths of a self-imaging ray and of the corresponding actual ray. The ray aberrations are shown to disappear when the periods of the lattice are large compared with the wavelength of light. We find that the ray aberrations carried by self-imaged oblique lattices are totally undercorrected and the aberrated image patches are displaced along the direction tangent vector of a chief ray. 相似文献
105.
有线数字电视DVB-C系统 总被引:1,自引:0,他引:1
介绍有线数字电视DVB-C系统的结构及其IRD,分析该系统前端和接收端的工作原理,并与数字卫星电视接收DVB-S系统进行比较. 相似文献
106.
107.
A calculation is presented of the long-time behavior of various random walk properties (moments, probability of return to the origin, expected number of distinct sites visited) formultistate random walks on periodic lattices. In particular, we consider inhomogeneous periodic lattices, consisting of a periodically repeated unit cell which contains a finite number of internal states (sites). The results are identical to those for perfect lattices except for a renormalization of coefficients. For walks without drift, it is found that all the asymptotic random walk properties are determined by the diffusion coefficients for the multistate random walk. The diffusion coefficients can be obtained by a simple matrix algorithm presented here. Both discrete and continuous time random walks are considered. The results are not restricted to nearest-neighbor random walks but apply as long as the single-step probability distributions associated with each of the internal states have finite means and variances. 相似文献
108.
介绍了基于SIMULINK软件对多种通信信号解调的通用解调器的建模。为了便于指导硬件实现,采用了定点数据进行仿真,通过大量实际数据的测试,验证了该仿真结构的有效性,并给出了部分仿真结果图。 相似文献
109.
M. S. Cao 《Journal of statistical physics》1993,71(1-2):51-59
The directed polymer on disordered hierarchical lattices is studied using an exact renormalization scheme. The phase transition is studied and a hyperscaling relation is derived. The fixed distributions of the renormalized energies are obtained numerically. The specific heat and associated exponents are computed from the fixed distributions. 相似文献
110.