配电网中的电力电子变压器技术的综述(下)

电力电子变压器(PET)是一种采用电力电子变换器和高频开关变压器的电能传输装置,随着智能电网的发展,在电力系统配电网中具有潜在的应用价值,因而日益受到广泛的研究。本文对电力电子变压器发展当中的几个关键方面进行了归纳总结,其中包括器件制造、电路拓扑、工作原理以及变换功能等,随后提出了采用单相-单相矩阵变换器、功率因数校正器的一类电力电子变压器,具有结构简单、换流安全、单位输入功率因数、双向功率流动以及便于级联等特征,简单地给出了理论分析和MATLAB/SIMULINK仿真分析,结果表明:这类电力电子变压器具有实用价值。     

基于二象限APF的单相功率因数校正器

为消除单相整流装置产生的谐波,提出了一种基于二象限有源滤波器(APF)的单相功率因数校正器,包括其主回路拓扑与控制策略。使用T型拓扑可滤除高次谐波,在主回路加装二极管可削减有源滤波器电流峰值,并在控制回路中使用双前馈以实现快速响应。对该拓扑和控制方案进行了Matlab仿真,并设计了基于dsPIC33F系列数字控制器的实验样机。仿真和实验结果均表明该技术可在降低成本的情况下,仍将功率因数提升至99%。     

液晶波前校正器特性研究

利用808 nm大功率连续激光器研究了液晶的光功率承受特性结果表明,当功率密度为133 W/cm2时,液晶还能保持原有的光学调制特性,而且可以长时间稳定工作测定了液晶的波长色散特性,发现,随着波长的增加Δn值逐渐减少,近紫外300~400 nm波段Δn变化47％,而在400~780 nm变化量为28％,在780~900 nm Δn变化了2％还研究了温度对液晶波前校正器衍射效率的影响,随着温度的升高Δn逐渐减小,当温度从10℃升到90℃时,对于16台阶菲涅耳透镜,衍射效率下降了70%;但当温度在20℃变化10℃时,对4台阶菲涅耳透镜衍射效率最大变化量为1.7%,而对16台阶菲涅耳透镜,衍射效率降低了1.2%.     

Evaluation of 1,2,3-Triazoles as Amide Bioisosteres In Cystic Fibrosis Transmembrane Conductance Regulator Modulators VX-770 and VX-809

The 1,2,3-triazole has been successfully utilized as an amide bioisostere in multiple therapeutic contexts. Based on this precedent, triazole analogues derived from VX-809 and VX-770, prominent amide-containing modulators of the cystic fibrosis transmembrane conductance regulator (CFTR), were synthesized and evaluated for CFTR modulation. Triazole 11 , derived from VX-809, displayed markedly reduced efficacy in F508del-CFTR correction in cellular TECC assays in comparison to VX-809. Surprisingly, triazole analogues derived from potentiator VX-770 displayed no potentiation of F508del, G551D, or WT-CFTR in cellular Ussing chamber assays. However, patch clamp analysis revealed that triazole 60 potentiates WT-CFTR similarly to VX-770. The efficacy of 60 in the cell-free patch clamp experiment suggests that the loss of activity in the cellular assay could be due to the inability of VX-770 triazole derivatives to reach the CFTR binding site. Moreover, in addition to the negative impact on biological activity, triazoles in both structural classes displayed decreased metabolic stability in human microsomes relative to the analogous amides. In contrast to the many studies that demonstrate the advantages of using the 1,2,3-triazole, these findings highlight the negative impacts that can arise from replacement of the amide with the triazole and suggest that caution is warranted when considering use of the 1,2,3-triazole as an amide bioisostere.     

共形光学头罩及其像差校正方法研究——综述

为了使高速红外光电制导导弹拥有良好的空气动力学性能,可以采用共形头罩来代替传统的球形头罩。根据共形光学校正元件的不同,归纳整理了七种不同的校正方案。其中,轴向平移相位板、反向旋转相位板、尼克泽楔形板和变形镜属于动态校正;固定式校正和拱形校正属于静态校正;还有一种为静态和动态相结合的校正方案。着重讨论了固定式校正方法,并给出了几种常用的校正表面类型。共形光学是高速红外光电主动制导导弹发展的关键技术之一,对其研究工作具有重要的现实意义。     

含特殊整流罩的红外光学系统设计

提出了一种有效的特殊整流罩及其像差校正器的设计方法,运用Wassermann-Wolf微分方程组(W-W方程组)的原理,通过在商业光学设计软件中编译宏程序曲面拟合的方法得到校正器最佳面形,从而可以校正整流罩引入的球差、彗差,使系统成像质量得到较大的改善.文章在基于W-W方程的基础上,针对应用于红外系统的特殊整流罩做了实际方案设计,研究的光学系统工作谱段为中波红外,视场大于3.5度,F数F/1～F/2.5,系统采用了复杂化的R-C系统,最终成像质量达到衍射极限,可以满足特殊条件下的红外谱段成像要求,具有较高的实用价值.     

Evaluation of Fused Pyrrolothiazole Systems as Correctors of Mutant CFTR Protein

Cystic fibrosis (CF) is a genetic disease caused by mutations that impair the function of the CFTR chloride channel. The most frequent mutation, F508del, causes misfolding and premature degradation of CFTR protein. This defect can be overcome with pharmacological agents named “correctors”. So far, at least three different classes of correctors have been identified based on the additive/synergistic effects that are obtained when compounds of different classes are combined together. The development of class 2 correctors has lagged behind that of compounds belonging to the other classes. It was shown that the efficacy of the prototypical class 2 corrector, the bithiazole corr-4a, could be improved by generating conformationally-locked bithiazoles. In the present study, we investigated the effect of tricyclic pyrrolothiazoles as analogues of constrained bithiazoles. Thirty-five compounds were tested using the functional assay based on the halide-sensitive yellow fluorescent protein (HS-YFP) that measured CFTR activity. One compound, having a six atom carbocyle central ring in the tricyclic pyrrolothiazole system and bearing a pivalamide group at the thiazole moiety and a 5-chloro-2-methoxyphenyl carboxamide at the pyrrole ring, significantly increased F508del-CFTR activity. This compound could lead to the synthesis of a novel class of CFTR correctors.     

液晶波前校正器过驱动矩阵的测量方法研究

从自适应光学应用的角度,对液晶波前校正器的过驱动矩阵的测量方法进行了系统研究。对量化级次和延迟时间进行了优化,最优量化级次为32级,最优延迟时间为14帧。最后,在延迟时间为14帧时,测量了液晶波前校正器的过驱动矩阵和终到位相矩阵,并对中等强度大气湍流进行了仿真校正,仿真计算结果与理论预期吻合得很好,表明测量方法可行。     

太阳辐射观测仪余弦误差修正方法

为了提高太阳辐射观测仪测量准确度,针对余弦校正器自身漫射特性和菲涅耳反射引起的余弦误差,研究了不同安装形式、不同结构下修正余弦误差的方法.结合太阳辐射特性和余弦误差的产生因素,提出了余弦校正器外露、余弦器外露配合挡光环两种安装形式下的余弦误差修正方法,以及余弦校正器、积分腔两种结构形式下的余弦误差修正方法.根据太阳辐射观测仪的使用要求,利用TracePro对不同安装方式下的余弦误差进行建模仿真,利用高准直性太阳模拟器配合转台和转臂模拟不同方向的准直太阳光,并实测余弦误差.实测结果表明,余弦器外露配合挡光环形式下,入射角小于±80°,余弦误差可优于±6%.该修正方法可有效地减小太阳辐射光大入射角情况下的余弦误差,提高太阳辐射观测准确度.     

Paradox of enrichment: A fractional differential approach with memory

The paradox of enrichment (PoE) proposed by Rosenzweig [M. Rosenzweig, The paradox of enrichment, Science 171 (1971) 385–387] is still a fundamental problem in ecology. Most of the solutions have been proposed at an individual species level of organization and solutions at community level are lacking. Knowledge of how learning and memory modify behavioral responses to species is a key factor in making a crucial link between species and community levels. PoE resolution via these two organizational levels can be interpreted as a microscopic- and macroscopic-level solution. Fractional derivatives provide an excellent tool for describing this memory and the hereditary properties of various materials and processes. The derivatives can be physically interpreted via two time scales that are considered simultaneously: the ideal, equably flowing homogeneous local time, and the cosmic (inhomogeneous) non-local time. Several mechanisms and theories have been proposed to resolve the PoE problem, but a universally accepted theory is still lacking because most studies have focused on local effects and ignored non-local effects, which capture memory. Here we formulate the fractional counterpart of the Rosenzweig model and analyze the stability behavior of a system. We conclude that there is a threshold for the memory effect parameter beyond which the Rosenzweig model is stable and may be used as a potential agent to resolve PoE from a new perspective via fractional differential equations.