NLFXLMS and THF‐NLFXLMS Algorithms for Wiener‐Hammerstein Nonlinear Active Noise Control

Nonlinear Filtered‐X LMS (NLFXLMS) is an indirect adaptive control algorithm for nonlinear active noise control (NANC) system. The algorithm has been developed for both Hammerstein and Wiener secondary paths where the nonlinearity is represented by scaled error function (SEF) and tangential hyperbolic function (THF). NLFXLMS algorithm is limited in practical application because the degree of nonlinearity has to be known in advance. This limitation leads to the development of the THF‐NLFXLMS algorithm where the degree of nonlinearity is estimated by modelling the secondary path. In this work, the NLFXLMS and THF‐NLFXLMS are extended to Wiener‐Hammerstein system. The performance of the proposed Wiener‐Hammerstein THF‐NLFXLMS is compared with NLFXLMS algorithm which is considered as the benchmark and second order Volterra algorithm of comparable computational complexity. Simulation results show that the THF‐NLFXLMS has a similar performance to NLFXLMS and outperforms the second order Volterra algorithm as the system becomes more nonlinear.     

Synthesis of core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s by electrostatic self-assembly and covalent fixation (ESA–CF) protocol

A pair of four-armed star and dicyclic 8-shaped poly(tetrahydrofuran)s, poly(THF)s, possessing a perylene diimide group at the core position (Ia and Ib, respectively) were synthesized by means of an electrostatic self-assembly and covalent fixation (ESA–CF) protocol. Mono- and bifunctional poly(THF)s having N-phenylpiperidinium salt end groups accompanying a perylene diimide tetracarboxylate as a counteranion were prepared by the ion-exchange reaction, and the subsequent covalent conversion by reflux in toluene afforded the corresponding core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s, (Ia and Ib, respectively) for the use of single-molecule fluorescence microscopy measurements.     

鄂尔多斯煤二硫化碳/四氢呋喃萃取物的初步分析

温和条件下用等体积的二硫化碳/四氢呋喃(CS2/THF)混和溶剂萃取鄂尔多斯煤,采用傅立叶变换红外光谱(FTIR)和气相色谱/质谱联用技术(GC/MS)分析了萃取物的化学成分和结构特征。结果表明:经过5次新鲜溶剂萃取,总萃取率为6.6%。第1次萃取物的质量最大,占萃取物总量的68%。各次萃取物的FTIR谱图含有较丰富的官能团信息,推测其中含有脂肪族、芳香族和含杂原子化合物。将5次萃取物分别用GC/MS进行检测,只有第1次萃取物可测,共检测出7种化合物且均为芳香族化合物,其中相对含量较大的3种化合物分别为惹烯、7-丁基-1-己基萘和西蒙内利烯。     

添加剂对水合物法回收烟气中二氧化碳影响的研究进展

阐述了目前基于添加剂环境下水合物法分离烟气中CO2的研究进展,主要对烟气水合物热力学、动力学、分离效果3个方面的研究状况进行了总结。重点对当前应用于烟气体系研究较多的几类添加剂——四正丁基溴化铵(TBAB)、四氢呋喃(THF)、环戊烷(CP)的性质、原理、优势及不足进行了介绍和对比,对一级水合物法处理烟气的研究现状进行了分析和评价,并预测了有效提高水合物法分离效果的可行方法。     

三正丁基膦的合成和表征

研究了以四氢呋喃为溶剂、格氏试剂合成法合成三正丁基膦的方法,对合成条件进行了优化,对合成产物进行了分析鉴定。结果表明:在镁、溴代正丁烷和三氯化磷的摩尔配比为1.05∶1.0∶0.27,格氏试剂制备的温度控制为回流温度,烷基化的温度控制在-3～0℃,反应时间分别为1.0、2.0h,三正丁基膦的收率最高,以溴代正丁烷计收率为53.1%。经折光和NMR分析确证为目标产品,GC归一化法分析质量分数为96.7%。     

Purification of tetrahydrofuran from its aqueous azeotrope by extractive distillation: Validation of model and simulation

Tetrahydrofuran (THF) purification by distillation is difficult due to the existence of its homogeneous, minimum boiling azeotrope with water. Previously conducted extractive distillation runs were used in this work to validate a rigorous model.

The validated model was then used to arrive at a feasible range of operating parameters by performing sensitivity analysis. It is shown through simulations that with the correct operating parameters, use of dimethyl sulfoxide can help obtain almost pure THF.     

Novel developments in the multidimensional characterization of segmented copolymers

Controlled radical polymerization (CRP) provides the polymer chemist with the ability to produce tailor-made polymers with controlled molar masses, molar mass distributions, chemical compositions and macromolecular architectures. Segmented copolymers can be synthesized having polymer segments arranged in a linear fashion (linear block copolymers), however, polymer segments can also be attached to pre-synthesized macromolecules or to multifunctional core molecules to produce branched (graft) copolymers, polymer stars or dendrimers. Although there are many ways to control the chain growth and the architecture of the target macromolecules, side reactions cannot be completely avoided. Accordingly, even with CRP, obtained products exhibit chemical composition and topology distributions along with the molar mass distribution.     

不同煤种热解反应性的简易评价

以蒽油为供氢溶剂、四氢呋喃(THF)抽提率作为评价指标,采用1L高压反应釜分别对许厂煤(XCM)、岱庄煤(DZM)、葛亭煤(GTM)和唐口煤(TKM)这四种煤进行了加氢热解试验。结果显示,在较低的氢初压(4.0MPa或6.0MPa)下,DZM的转化率相对最高,达到47.45%,且体系的压力最低,而且延长热解时间DZM的转化率增幅最大,说明DZM的热解反应性最好。煤热解物的THF抽提率可以作为煤热解性能的快速评价指标。     

PBT切片中THF的检测

通过单因素实验,运用顶空气相色谱法,优化检测PBT切片中THF含量的条件。在实验的基础上得到样品前处理的最佳条件,并发现工艺的调整对THF生成有一定的影响。     

BF3-H2O催化环氧乙烷阳离子开环均聚的量子化学

 探讨了BF3-H2O催化剂和四氢呋喃(THF)、二氯乙烷(EDC) 2种溶剂的加入对环氧乙烷(EO)阳离子开环聚合量子化学计算的影响,以及BF3-H2O催化EO开环聚合的微观机理。应用Gaussian03软件,采用DFT中的B3LYP/6-311++(d,p)基组,分别对气相和2种溶剂中2种可能的BF3-H2O催化EO开环聚合反应路径产生的各物种的构型进行了几何构型全优化,得到了它们的结构、键级和能量等参数。7计算结果表明,各物种在溶剂中的能量比气相中低,且溶剂介电常数越大,能量越低。BF3-H2O催化剂体系存在络合和电离2种形式,由于BF3-H2O电离能很高,故以络合物形式催化EO的开环聚合反应为主。计算结果与实验结果吻合很好。