分数阶Buck变换器的混沌分析与控制

基于电感与电容的分数阶事实,在Matlab/Simulink下建立了电压控制型Buck变换器的分数阶数学仿真模型及对应的电路仿真模型,分析验证了模型的正确性。基于建立的分数阶数学仿真模型,少有文献研究的以参考电压作为混沌控制变量的Buck变换器混沌行为,绘制了以参考电压为混沌变量的Buck变换器V-I混沌相图与对应的分岔图,得出较小的参考电压易引起Buck变换器进入混沌状态。最后,采用参数扰动法实现了混沌控制,得到了新的分岔图,与混沌控制前的分岔图形成了鲜明的对比。同时,通过选定特定的参考电压值,经分析混沌控制前后电感电流的时域波形图,验证了该控制算法的有效性。     

基于CATIA二次开发的月牙肋钢岔管辅助设计系统开发与应用

利用自动化对象编程,针对水电站月牙肋钢岔管设计繁琐、工作量大、有限元计算前处理耗时长的缺点,开发出基于CATIA二次开发的辅助设计系统.该系统实现了月牙肋钢岔管在CATIA中的快速建模和网格自动剖分,最终在有限元软件ANSYS中完成有限元计算.以蟠龙抽水蓄能电站工程月牙肋钢岔管为例进行了计算,并与设计院的计算结果进行了对比与分析,结果表明该系统具有设计速度快、精度较高等优点,具有较高的实用价值.     

PUBLICATIONS ON THERMAL STRESSES

The study of the nonlinear response of sandwich flat panels exposed to thermomechanical loading systems is the topic of this article. The sandwich structure considered in this article consists of a thick core layer bonded by the face layers, which are assumed to be symmetrically located with respect to the midplane of the overall structure. The loads involved in this analysis consist of biaxial compressive edge loads, a lateral pressure, and a nonuniform temperature field. The effects of the unavoidable initial geometric imperfections and the character of tangential boundary conditions are incorporated, and their implications upon the structural response are explored. In short, the results of this study are intended to provide pertinent information on the thermomechanical load-carrying capacity of flat sandwich structures.     

右-右缠绕模范畴M_A~C(Ψ)中的扭曲

主要推广了关于相关Hopf模的扭曲理论到缠绕模上,证明(A,C,Ψ)上的右-右缠绕模范畴MCA(Ψ)同构于(Aτ,C,Ψ)上的右-右缠绕模范畴MACτ(Ψ),从而发展了缠绕模的理论。     

电力系统中的全局分支现象

根据多重尺度法理论推导出在周期性负荷扰动下,电力系统中Hopf分支型小振荡解的 一致渐进解析式,并在此基础上,详细地分析了该小振荡解中出现的同宿轨道型 及其它全局分支现象,为电力系统中出现的复杂的小振荡现象的原因提供了一种新 的解释。     

光学多峰映象的混沌及其分岔结构

用定态失稳系统与分岔图的对应方法,研究了光学多峰映象的混沌及其分岔结构.用这种方法可以方便地预言和辨认出系统失稳、合并以及切分岔的出现.     

具有二阶细焦点的二次系统

文[1-3]证明了三阶细焦点外围无环。具细焦点的二次系统在非奇异线性变换下可以化成[4] ax/dt=-y+ax~2+bxy,dy/dt=x+lx~2+mxy+ny~2 (1)原点为二阶细焦点的充要条件为[5]: W_1=a(b-2l)-m(l+n)=0, W_2=a(2a+m)(3a-m)[a~2(b-2l-n)+(n+l)~2(n-b)]≠0 (2)[6]研究b=0的情形,证明了W_2W_3>0时二阶细焦点外围无环(此处W_3=a~2l(2a+m)(2l+n)[a~2(b-2l-n)+(l+n)~2(n-b)])。b≠0时可设b=1,此时文[7-8]研究了n=0,±1,±1/2的情形,也证明了当W_2W_3>0时二阶细焦点外围无环。本文考虑较为一般的情形:b=1,n>1,也证明了W_2W_3>0时二阶细焦点外围无环。     

Fracture Process in ± θ Laminates Subjected to Mode II Loading

This work studies the behavior of a multidirectional laminate under Mode II loading. We describe the process of delamination in a reinforced composite of glass/epoxy. The stacking sequence (plies orientation [± ] was selected to minimize the coupling effects. The Mode II interlaminar test under three-point bending and cantilever flexure using ENF (End Notch Flexure) and ELS (End Load Split) specimens, respectively, was performed and analyzed. The test procedures and the results of strain-energy-release rate study for crack initiation are presented. The fracture process and the mechanical behavior of the two types of specimens are analyzed. The analysis clearly shows a close link between the angle , the ratio a/L, and the thickness h of the specimen. Fracture by delamination can be obtained only with an optimal choice of these parameters. The analysis of the states of stresses at the tip of crack allows us to explain the phenomenon of bifurcation between plies and is confirmed by the experimental results.     

鞍结分岔与极限诱导分岔的电压稳定性评估

提出了一个改进的约束优化方法来计算电压稳定性评估指标——负荷裕度，并以此来评估新型的电压崩溃现象——极限诱导分岔和传统的鞍结分岔。为了和现有的一些电压评估算法保持一致性，发电机无功极限约束被引进到了优化问题的约束条件中，并以此来判定无功，电压约束转换点和判断系统的电压崩溃类型。针对不同的系统模型，文中给出了各个系统的电压崩溃类型和负荷裕度。算法的有效性通过IEEE30，57，118母线系统、西日本（West-J）27母线系统和1个1047母线系统模型的仿真的得到了验证。该方法可有效地应用于电力系统电压稳定分析与评估领域。