The properties of irreducible character kernels heavily influence the structure of finite groups.The structure of finite nilpotent groups having at most two nonlinear non-faithful irreducible characters is characterized.
In this paper, we investigate the dynamics of stochastic plate equations with memory in unbounded domains. More specifically, we obtain the uniform time estimates for solutions of the problem. Based on the estimates above, we prove the existence and uniqueness of random attractors in unbounded domains.
AbstractFor a non-empty setXX, denote the full transformation semigroup onXXbyT(X)T\left(X)and suppose thatEEis an equivalence relation onXX. Evidently,TE∗(X)={α∈T(X)∣(x,y)∈Eif and only if(xα,yα)∈Efor allx,y∈X}{T}_{{E}^{\ast }}\left(X)=\left\{\alpha \in T\left(X)| \left(x,y)\in E\hspace{0.33em}\hspace{0.1em}\text{if and only if}\hspace{0.1em}\hspace{0.33em}\left(x\alpha ,y\alpha )\in E\hspace{0.33em}\hspace{0.1em}\text{for all}\hspace{0.1em}\hspace{0.33em}x,y\in X\right\}is a subsemigroup ofT(X)T\left(X). In this article, we investigate Green relations, Green∗\ast-relations and Green∼\sim-relations, various kinds of regularities,ℱ{\mathcal{ {\mathcal F} }}-abundant andG{\mathcal{G}}-abundant elements and left and right magnifying elements inTE∗(X){T}_{{E}^{\ast }}\left(X). More specifically, we first obtain the necessary and sufficient conditions under whichℒ{\mathcal{ {\mathcal L} }}(respectively,ℒ∗{{\mathcal{ {\mathcal L} }}}^{\ast },ℒ˜\widetilde{{\mathcal{ {\mathcal L} }}},ℛ{\mathcal{ {\mathcal R} }},ℛ∗{{\mathcal{ {\mathcal R} }}}^{\ast }, andℛ˜\widetilde{{\mathcal{ {\mathcal R} }}}) is (left, right) compatible,ℛ=ℛ∗{\mathcal{ {\mathcal R} }}={{\mathcal{ {\mathcal R} }}}^{\ast }orℒ=ℒ˜{\mathcal{ {\mathcal L} }}=\widetilde{{\mathcal{ {\mathcal L} }}}. Then, we give the sufficient and necessary conditions such thatTE∗(X){T}_{{E}^{\ast }}\left(X)is left regular (respectively, right regular, completely regular, intra-regular, and completely simple). Finally, we characterize theℱ{\mathcal{ {\mathcal F} }}-abundant (respectively,G{\mathcal{G}}-abundant) and left (respectively, right) magnifying elements inTE∗(X){T}_{{E}^{\ast }}\left(X).
针对太阳能热发电过程中广泛存在的随机性和不确定性问题,文中采集实测的数据进行聚类后建立多模型,设计了多模型加权预测控制器.首先,采用模糊聚类算法对实测的太阳能热发电数据进行分类,再用递推最小二乘法建立系统的多模型作为预测模型;其次,取集热器入口温度、太阳辐照强度以及环境温度为扰动信号,以导热熔盐的流速为控制量控制集热器的出口温度,并针对不同的子模型设计预测控制器;第三,按照子控制器的加权策略得到最小的控制增量并对系统进行稳定性分析;最后,进行试验仿真分析,和目前多采用的单模型预测控制结果比较,加权多模型预测控制精度更高.滞后时间更短.
以直流电源为驱动,锥形铂棒为阳极,铂丝环绕的毛细管顶端溢出的液体为阴极,利用外加磁场增强元素的信号强度,构建了一种磁场辅助的溶液阴极辉光放电(MF-SCGD)原子发射光谱微分析系统.研究发现,在磁场作用下,等离子体中的带电离子受到磁约束,使得其运动路径发生变化,进而减缓了等离子体的膨胀,增加了等离子体的温度、密度以及碰撞频率,从而提高了 Pb的激发效率和原子化效率;磁场的引入可以提高溶液的蒸发率,降低阳极铂棒的红热程度.在放电电压为650 V、溶液流速为2.4 mL·min-1、pH=1.0的HNO3为电解质时,加入0.5 T的磁场可以使Pb的信号增强1.5倍,灵敏度提高1.4倍,放电功率低于25 W,检出限(LOD)降低到0.17mg·L-1.用MF-SCGD对环境标准样品(BW0610)和中药材中的Pb进行测试,发现测定值与标准值以及加标值基本一致,回收率为101％～105％,说明该方法对铅的测定准确可靠.MF-SCGD具有仪器紧凑、成本低、功率小、放电稳定性高等优点,是一种很有前景的微分析技术.
