Compatibility of PVC-chlorinated PVC mixtures

This study deals with the compatibility of a poly(vinyl chloride) mixed separately with two industrial chlorinated poly(vinyl chlorides), denoted PVC/C1 and PVC/C2 (chlorine contents of 65.2 and 67.5%, respectively). The technique of mixing, examined for different compositions, is the main parameter for the compatibility of the resins. The mixtures were prepared either with a Brabender plastograph, with a milling cylinder at 190°C (the mixture being fluid), or by sintering at a temperature between 180 and 200°C under pressure. We determined the complex components of the elasticity modulus as a function of temperature (from 50 to 170°C at a frequency of 110 Hz) for each mixture, using a Rheovibron viscoelastometer. The study of the structure of the mixtures, based on the variation of the tangent of the loss modulus, allows us to say that the compatibility of polymers depends on the chlorine contents in chlorinated PVC; thus, at 65.2% the chlorinated polymer seems to be compatible with PVC, but at 67.5% the mixture shows the characteristics of a two-phase system. The compatibility is also dependent on processing methods.     

Oscillating solitons of the driven,damped nonlinear SchrÖdinger equation

We obtain time-periodic solitons of the parametrically driven, damped nonlinear Schrödinger equation as solutions of the boundary value problem on a two-dimensional domain. We classify the stability and bifurcations of singly and doubly periodic solutions.     

Growth and properties of digitally-alloyed AlGaInP by solid source molecular beam epitaxy

Digital alloying using molecular beam epitaxy (MBE) was investigated to produce AlGaInP quaternary alloys for bandgap engineering useful in 600-nm band optoelectronic device applications. Alternating Ga_0.51In_0.49P/Al_0.51In_0.49P periodic layers ranging from 4.4 monolayers (ML) to 22.4 ML were used to generate 4,000-Å-thick (Al_0.5Ga_0.5)_0.51In_0.49P quaternary materials to understand material properties as a function of constituent superlattice layer thickness. High-resolution x-ray diffraction (XRD) analysis exhibited fine satellite peaks for all the samples confirming that digitally-alloyed (Al_0.5Ga_0.5)_0.51In_0.49P preserved high structural quality consistent with cross-sectional transmission electron microscopy (X-TEM) images. Low-temperature photoluminescence (PL) measurements showing a wide span of luminescence energies ～ 170 meV can be obtained from a set of identical composition digitally-alloyed (Al_0.5Ga_0.5)_0.51In_0.49P with different superlattice periods, indicating the bandgap tunability of this approach and its viability for III-P optoelectronic devices grown by MBE.     

Initialization behavior at various target molecular weight RAFT‐mediated methyl acrylate polymerizations

In the reversible addition‐fragmentation chain transfer (RAFT) mediated polymerization of methyl acrylate, a selective reaction is observed in the early stages of the polymerization. This initialization process was earlier observed in in situ ¹H NMR spectroscopy experiments where extremely low target molar masses were chosen (around DP = 5). Here, for the first time, the presence of the initialization process is identified as the cause of an induction period under typical conditions of a RAFT‐mediated polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2500–2509, 2008     

修理设备可更换且修理延迟的两相同部件冷储备可修系统(Ⅱ)

在文[1]的基础上,本文研究了修理有延迟和修理设备可更换的两单元冷储备可修系统.在假定单元的寿命服从指数分布、修理时间和延迟时间服从一般分布、修理设备的寿命和故障后的更换时间服从指数分布下,通过定义修理设备的"广义忙期",使用更新过程理论和全概率分解技术,提出一种新的分析技巧,讨论了修理设备的一些可靠性指标,获得了如修理设备的可用度和故障次数等可靠性结果.     

广义Fibonacci等距子列关于模L_m的模数列的周期

给出广义Fibonacci等距子列的定义,推导出此类等距子列的统一递推公式,并由此得出其关于Lucas数为模的模数列的周期规律.     

一类二次可逆系统周期函数的单调性

利用Picard-Fuchs方程,研究了一类二次可逆系统周期函数的单调性问题,获得了在首次积分曲线是亏格1时的二次可逆系统周期函数单调的结论.     

基于缓变上升沿泵浦光的布里渊慢光研究

为了增加布里渊慢光的时间延迟,减小脉冲展宽,利用迎风格式的有限差分法对光纤中受激布里渊散射耦合方程组进行数值求解,分析了具有缓慢变化上升沿的连续光作为泵浦光时,光纤输出端斯托克斯光的时间延迟和脉冲展宽因子随增益的变化情况。数值结果表明:具有缓慢变化上升沿的泵浦光可使高斯长脉冲FWHM(半宽全高)为120ns的时间延迟增加到52ns,高斯短脉冲(FWHM为20ns)的时间延迟增加到64ns,同时可减小高斯长短脉冲的展宽。     

G.729A声码器高效基音搜索算法研究

为了进一步降低G.729A复杂度,提出了一种高效的基音搜索算法。在对基音搜索的两个环节开环基音分析和闭环搜索进行研究的基础上,分别采用了4：1抽取来减少开环基音分析的搜索范围和改进闭环基音搜索模型的方法。该算法降低了基音搜索时所需要的运算量,在总体上降低了原算法的复杂度。最后通过仿真实验,验证了所提方法的有效性。     

Sounding配置对TD-LTE网络性能的测试和分析

实验目的主要是考察Sounding在不同周期、带宽配置下对TD-LTE网络性能的影响。文章首先从理论上进行了细致的分析,并采用真实环境进行测试验证,从而可靠评估了Sounding配置对TD-LTE网络性能的影响。