热处理对PVDF复合体系形态及性能的影响

利用ＤＳＣ、ＷＡＸＤ和ＳＥＭ等测试手段，研究了不同热处理条件下聚偏二氯乙烯合金／炭黑导电复合体系的结晶形态及正温度系数效应特性。结果表明，热处理可以改善基体结晶行为。使结晶度提高，从而使导电复合体系的室温电阻率下降、ＰＴＣ强度提高、ＰＴＣ曲线的重复稳定性变好。     

Cellulose acetate reverse osmosis membranes: Optimization of preparation parameters

Asymmetric cellulose acetate based membranes usually employed in reverse osmosis as well as in separations in aqueous systems can possibly be applied in the so‐called salinity process of energy generation. For these applications, membranes with a relatively high water permeability (sometimes also called water flux) and low salt permeability (or high salt rejection) are required. In this study the authors present the optimization of such membranes, which concerns the preparation parameters. The membranes studied were prepared from a solution whose composition were previously optimized.⁴ The authors concluded that the optimum preparation parameters are as follows: thickness of the liquid film of 100 μm; 30 s allowed for evaporation of the solvent; and temperature of coagulation bath of 0–4°C and 80–85°C as annealing temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 134–139, 2007     

Effect of process variables on bulk development of air‐textured poly(trimethylene terephthalate) bulk continuous filaments

Bulk development of air‐textured poly(trimethylene terephthalate) (PTT) bulk continuous filaments was studied by varying two texturing parameters, yarn preheating and texturing hot air temperatures. The yarns were subsequently heat treated from 80 to 160°C. Bulk was found to go through a maximum with increasing heat‐treatment temperature because of two competing mechanisms. Upon heat treatment, the fiber shrunk and developed bulk; heat treatment also simultaneously induced structural reorganization through annealing and stabilized the fiber against shrinkage. When the later mechanism became dominant, bulk development decreased with further increase of heat‐treatment temperature. The temperature at which the maximum occurred increased when the yarn preheating or texturing air temperatures were increased. Depending on the extent of annealing and structural reorganization during yarn preheating and during texturing, fibers with equivalent bulk measured at a single temperature did not behave the same way over a range of heat‐treatment temperatures. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1011–1017, 2004     

药品冷冻干燥过程的退火机理分析

运用热力学和动力学理论分析了药品冷冻干燥过程中的退火操作改变冻结药品结构的机理。通过对化学势随晶粒曲率半径变化、重结晶过程中冰晶半径随时间变化、非晶态基质的粘度随温度变化几个关系式的分析,得出退火温度必须要高于冻结药品的玻璃化转变温度;最佳退火持续时间与重结晶的速率紧密相关,且是退火温度的函数;退火后再冷却过程的冷却速率不影响升华干燥速率等结论。     

Low‐frequency sound absorption of organic hybrid comprised of chlorinated polyethylene and N,N′‐dicyclohexyl‐2‐benzothiazolyl sulfenamide

We investigated the sound absorption characteristics of an organic hybrid material comprised of chlorinated polyethylene (CPE) as the matrix polymer and N,N′‐dicyclohexyl‐2‐benzothiazolyl sulfenamide (DBS) as the second component of an organic low‐molecular‐weight compound. We found specific crystallites, obtained by annealing, that generated new absorption for a low‐frequency sound in a CPE/DBS blend. We observed two sound absorption peaks, around 300 and 1000 Hz, in the annealed CPE/DBS (50 : 50 w/w) blends, whereas those peaks were not observed in the untreated sample. There were two kinds of crystals with different melting points in the annealed samples. It was confirmed that the crystals with the lower melting point brought about sound absorption at a low frequency. The crystals that had the lower melting point were smaller and/or more disordered than the crystals that had the higher melting point. We calculated the fraction of these two types of crystals from differential scanning calorimetry and wide‐angle X‐ray diffraction measurements. The annealing or reannealing temperature specified the fraction of the crystal with the lower melting point, and the obtained crystal fraction characterized sound absorption frequency. Therefore, it is possible to control the sound absorption frequency of an organic hybrid by heat treatment such as annealing. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

基于遗传模拟退火的QoS单播路由算法

针对QoS的问题,设计了一种融合遗传算法和模拟退火算法的QoS路由算法,在遗传算法选择算子上借鉴了小生境的思想,避免了遗传初期有效基因的丢失;在遗传算法交叉算子和变异算子方面使用了自适应算子,使之能更好地适应网络的变化。通过与传统遗传算法进行比较,进一步说明了本算法的有效性。     

基于模拟退火的自适应粒子群优化算法的改进策略

针对PSO算法在求解问题的优化问题中易陷入局部收敛且收敛速度较慢等缺陷,引入一种初始化改进策略,并将模拟退火算法与PSO算法相结合,提出了一种全新的算法。该算法将寻优过程分为两个阶段:为了提高算法的执行速度,前期使用标准PSO算法进行寻优,后期运用模拟退火思想对PSO中的参数进行优化搜索最优解。最后将该算法应用于八个经典的单峰/多峰函数中。模拟结果表明,该算法有效地避免了早熟收敛现象,并提高了收敛速度,从而提高了PSO算法解决全局优化的性能。     

On-line estimation of vapour pressure of stabilized gasoline via ANN’s

The use of artificial neural network based model for the on-line estimation of the Reid Va-por Pressure of stabilized gasoline in a stabilizer after the stripper-reabsorber in the fluid catalyticcracking unit is investigated.The quadratic basis function network(QBFN)which uses a simplequadratic function instead of sigmoid function typically used in back-propagation network is em-ployed.180 sets of historical operation data have been selected for training and testing the QBFN.To overcome the local minimum point which often occurs during the training phase,a new algorithmcombining the simulated annealing approach with the improved GDR has been applied.Furthermore,the developed model has been installed on-line in a refinery for on-line testing.Thetesting results show that the model is sufficiently accurate and it can be used on site as an on-lineanalyzer.     

基于松散式代理模型管理框架的亚音速机翼优化设计方法研究

基于N-S方程的三维气动外形的优化设计一直以来都因为存在众多的设计变量和庞大的计算量问题而无法实现,为了解决这些问题,文中发展了一套机翼气动优化设计系统,该系统基于模拟退火粒子群优化算法、松散式代理模型以及动网格和改进的HicksHenne函数变形技术,选取翼根、翼梢各18个设计变量进行参数化。按某型飞机设计要求,在给定设计指标下进行优化设计,研究了基于松散式代理模型管理框架下,训练样本采用拉丁超立方方法对Kriging代理模型的预测能力进行评估,以及应用该代理模型框架进行了亚音速机翼的气动外形优化设计,结果显示,优化后机翼的气动特性有着显著提高。     

Crystallization and crosslinking of polyamide‐1010 under elevated pressure

The structure and thermal properties of polyamide‐1010 (PA1010), treated at 250°C for 30 min under pressures of 0.7–2.5 GPa, were studied with wide‐angle X‐ray diffraction (WAXD), infrared (IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Crystals were formed when the pressures were less than 1.0 GPa or greater than 1.2 GPa. With increasing pressure, the intensity of the diffraction peak at approximately 24° was enhanced, whereas the peak at approximately 20° was depressed. The triclinic crystal structure of PA1010 was preserved. The highest melting temperature of the crystals obtained in this work was 208°C for PA1010 treated at 1.5 GPa. Crosslinking occurred under pressures of 1.0–1.2 GPa. Only a broad diffraction peak centered at approximately 20° was observed on WAXD patterns, and no melting and crystallization peaks were found on DSC curves. IR spectra of crosslinked PA1010 showed a remarkable absorption band at 1370 cm^?1. The N? H stretching vibration band at 3305 cm^?1 was weakened. Crystallized PA1010 had a higher thermal stability than crosslinked PA1010, as indicated on TGA curves by a higher onset temperature of decomposition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2522–2527, 2002