Statistical thermodynamics evaluation of polymer–polymer miscibility

The Simha and Somcynsky (S–S) statistical thermodynamics theory was used to compute the solubility parameters as a function of temperature and pressure [δ = δ(T, P)], for a series of polymer melts. The characteristic scaling parameters required for this task, P*, T*, and V*, were extracted from the pressure–temperature–volume (PVT) data. To determine the potential polymer–polymer miscibility, the dependence of δ versus T (at ambient pressure) was computed for 17 polymers. Close proximity of the δ versus T curves for four miscible polymer pairs: PPE/PS, PS/PVME, and PC/PMMA signaled the usefulness of this approach. It is noteworthy, that the tabulated solubility parameters (derived from the solution data under ambient conditions) propounded the immiscibility of the PVC/PVAc pair. The computed values of δ also suggested miscibility for polymer pairs of unknown miscibility, namely PPE/PVC, PPE/PVAc, and PET/PSF. In recognizing the limitations of the solubility parameter approach (the omission of several thermodynamic contributions), these preliminary results are auspicious because they indicate a new route for estimating the miscibility of any polymeric material at a given temperature and pressure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2909–2915, 2004     

爆磁压缩发生器通过脉冲变压器对脉冲形成线充电的理论分析

 将爆磁压缩等效为电流源的方法，对爆磁压缩发生器通过脉冲变压器对脉冲形成线充电进行了理论分析，得出爆磁压缩发生器在负载上产生电流波形（简称负载电流）为直线情况和任意电流波形情况下充电电流和充电电压的表达式。分析表明变压器耦合互感与负载电流随时间变化增长率是脉冲形成线充电的两个重要参数，脉冲形成线第一个充电电压峰值与变压器的耦合互感和负载电流波形斜率成正比，负载电流波形斜率的变化可以改变充电电压峰值的时间，斜率不断增加可以延长第一个充电电压峰值时间，从而可能增加充电电压的幅值，提高爆磁压缩发生器能量的利用效率。     

A note on the necessary conditions for the algebraic Riccati equation

We derive some useful and easily computable necessary conditionsfor the existence of a positive semi-definite solution to thealgebraic Ricatti equation (ARE). A motivating example is givento highlight the usefulness of the conditions for controllerand observer designs for nonlinear systems. Further, an upperbound on the trace of the solution to the ARE is also derived.     

Continuation of travelling‐wave solutions of the Navier–Stokes equations

An efficient way of obtaining travelling waves in a periodic fluid system is described and tested. We search for steady states in a reference frame travelling at the wave phase velocity using a first‐order pseudospectral semi‐implicit time scheme adapted to carry out the Newton's iterations. The method is compared to a standard Newton–Raphson solver and is shown to be highly efficient in performing this task, even when high‐resolution grids are used. This method is well suited to three‐dimensional calculations in cylindrical or spherical geometries. Copyright © 2006 John Wiley & Sons, Ltd.     

因素空间理论与知识表示的数学框架(XⅢ)──描述架中概念的结构(2)

本文是［１，１２］的继续，研究描述架中概念的结构；本文讨论后半部分，内容涉及概念内涵与外延的转换，清晰关系的内投影与内变换，概念的结构＊以及有关问题的注记。     

On a Question of Phillips

In [5] Phillips proved that one can obtain the additive group of any nonstandard model *? of the ring ? of integers by using a linear mod 1 function h : F ?, where F is the α-dimensional vector space over ? when α is the cardinality of *?. In this connection it arises the question whether there are linear mod 1 functions which are neither addition nor quasi-linear. We prove that this is the case.     

Ba（n，x）~（134）Cs，~（134）Ba（n，2n）~（133）Ba，

用中子活化法相对于５４Ｆｅ（ｎ，Ｐ）５４Ｍｎ反应，在１３．５０—１４．８０ＭｅＶ中子能区测量了Ｂａ（ｎ，ｘ）１３４Ｃｓ，１３４Ｂａ（ｎ，２ｎ）１３３Ｂａ，１４０Ｃｅ（ｎ，２ｎ）１３９Ｃｅ，１４２Ｃｅ（ｎ，２ｎ）１４１Ｃｅ和２３Ｎａ（ｎ，２ｎ）２２Ｎａ的反应截面．并将所测的结果和其他作者的结果进行了比较，中子能量是用９０Ｚｒ（ｎ，２ｎ）８９ｍ＋ｇＺｒ反应和９３Ｎｂ（ｎ，２ｎ）９２ｍＮｂ反应截面比法测定的。     

(ΩΩ)0+ Dibaryon Productions in Central Au+Au Collisions at RHIC Energy(SNN)= 130 GeV

Based on the measured transverse mass spectra ofπr-, K-, and p at the RHIC energy s()NN = 130 GeV,di-omega productions from baryon-baryon reactions in hadronic matter are studied. Results about the (ΩΩ)0+ numbershow that the deeply bound state (ΩΩ)o+ can be observed at RHIC energies.     

Miscible blends of modified poly(aryl ether ketones) with aromatic polyimides

The phase behavior of binary blends of poly(ether ether ketone) (PEEK), sulfonated PEEK, and sulfamidated PEEK with aromatic polyimides is reported. PEEK was determined to be immiscible with a poly(amide imide) (TORLON 4000T). Blends of sulfonated and sulfamidated PEEK with this poly(amide imide), however, are reported here to be miscible in all proportions. Blends of sulfonated PEEK and a poly(ether imide) (ULTEM 1000) are also reported to be miscible. Spectroscopic investigations of the intermolecular interactions suggest that formation of electron donoracceptor complexes between the sulfonated/sulfamidated phenylene rings of the PEEKs and the n-phenylene units of the polyimides are responsible for this miscibility. © 1993 John Wiley & Sons, Inc.