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91.
Two non-discrete Hausdorff group topologies and on a group G are called transversal if the least upper bound of and is the discrete topology. In this paper, we discuss the existence of transversal group topologies on locally pseudocompact, locally precompact, or locally compact groups. We prove that each locally pseudocompact, connected topological group satisfies central subgroup paradigm, which gives an affrmative answer to a problem posed by Dikranjan, Tkachenko, and Yaschenko [Topology Appl., 2006, 153:3338-3354]. For a compact normal subgroup K of a locally compact totally disconnected group G, if G admits a transversal group topology, then G/K admits a transversal group topology, which gives a partial answer again to a problem posed by Dikranjan, Tkachenko, and Yaschenko in 2006. Moreover, we characterize some classes of locally compact groups that admit transversal group topologies. 相似文献
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Some criteria for achieving the finite-time synchronization of a class of autonomous chaotic systems are derived by the finite-time stability theory and Gerschgorin disc theorem. Numerical simulations are shown to illustrate the effectiveness of the proposed method. 相似文献
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In this paper, synchronization of master–slave Lagrangian systems via intermittent control was developed. Based on the intermittent control, some algebraic criteria are derived to make the slave Lagrangian system synchronize to a master one. Different from the most existing results on control problems of Lagrangian systems, the controller proposed here is not continuous-time control input and is not relied on the knowledge of system models. As a direct application, the obtained results are applied to a typical two-link revolute jointed robot (robot manipulator). Subsequently, numerical simulations demonstrate the effectiveness of the criteria and the robustness of the control strategy. 相似文献
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In this paper, we investigate the problem of Hopf bifurcation and chaos control in a new chaotic system. A hybrid control strategy using both state feedback and parameter control is proposed. Theoretical analysis shows that the Hopf bifurcation critical value can be changed via hybrid control. Meanwhile, this control strategy can also control the chaos state. The direction and stability of bifurcating periodic solutions are determined by the normal form theory and the center manifold theorem. Finally, numerical simulations are carried out to illustrate the effectiveness of the main theoretical results. 相似文献
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结合四环素对碳点(CDs)的荧光猝灭及对铕离子(Eu 3+)的荧光增强作用, 建立了一种肉眼可辨的比率荧光分析方法用于水样中四环素残留的便捷检测. 通过优化CDs/Eu 3+比例、 溶液pH值等实验条件, 使检测体系对四环素的荧光响应呈现由蓝色→粉色→红色的颜色转变过程, 易于通过肉眼进行分辨和半定量分析. 实验结果表明, 2种荧光探针响应比(I618/I440)的对数值与四环素的浓度在20~100 nmol/L范围内呈线性关系, 方法的检出限为1 nmol/L. 将该方法应用于江水样品中四环素的加标检测, 获得了较好结果. 相似文献
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选取十二烷基硫酸钠(SDS),辛基苯基聚氧乙烯醚(OP-10)为复合乳化剂,过硫酸钾(KPS)为引发剂,将2-(全氟己基)乙基甲基丙烯酸酯(PFM)与丙烯酸酯类单体采用预乳化-半连续种子乳液聚合法进行乳液共聚,再将羟基螺吡喃(SPOH)与乳液进行物理共混,制得光致变色含氟丙烯酸酯乳液。 通过多种表征手段研究丙烯酸正丁酯(n-BA)和甲基丙烯酸甲酯(MMA)软硬单体的质量比,SPOH的用量对聚合反应和乳胶膜性能的影响。 结果表明,加入含氟单体后乳胶膜与水、油的接触角提高,热稳定性提高;加入SPOH的质量分数为1.25%时,乳胶膜具有较好的光致变色性能。 相似文献
98.
The development of photocatalysts that can efficiently convert CO2 into other valuable chemicals via photocatalytic and photothermal processes is critical to the current energy and climate change problems. However, low separation of charge carriers, short light absorption, and low activation of CO2 molecules in photocatalysis limit the catalysts’ performance. Designing 1D heterostructures containing multiple materials can be a viable solution as their unique properties, such as high surface area, short diffusion paths of charge carriers, and enhanced light absorption properties, can potentially promote the reaction rate and product selectivity. In this review, we summarize the general features of heterostructures involving nanotubes, nanowires, nanorods, and nanobelts. Next, the main synthesis strategies are briefly highlighted, followed by the most important findings concerning their catalytic activity in the photothermal and photocatalytic CO2 reduction processes. The article concludes with some of the current challenges and potential solutions. 相似文献
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This paper proposes the novel enhanced generalized space shift keying (EGSSK) to improve the spectral efficiency (SE) and energy efficiency (EE). In conventional GSSK, all of antenna combinations are not used because of power-of-two form. To overcome this problem, we suggest to exploit spare antenna combination for cell-edge users (CEUs). Concurrently, we propose the search field based iterative maximum likelihood detector (SFMLD) to reduce the complexity at the receiver. The simulated and analytical results are shown in terms of SE, average bit error rate (ABER), complexity and EE. 相似文献
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Prof. Lei Yang Yawen Wang Hetian Feng Huajie Zeng Prof. Changhui Tan Junjie Yao Dr. Junchang Zhang Prof. Lin Jiang Prof. Yinghui Sun 《化学:亚洲杂志》2021,16(1):34-38
Recently, direct formic acid fuel cells (DFAFCs) which possess superior advantages such as a low operating temperature, light environmental pollution and high energy density, have been considered as one of the power generation technologies with a bright prospect. Herein, bimetallic PdAg nanoparticles (NPs) with different particle sizes were successfully produced via an easy one-pot solvothermal co-reduction synthetic route and their electrocatalytic performance for formic acid oxidation (FAO) were further investigated. In our strategy, the size of PdAg NPs can be easily controlled by only varying the concentration of precursors. The larger sized PdAg alloy (9.5 nm, noted as PdAg−L) was obtained at a low concentration of precursors, while the smaller PdAg alloy (3.7 nm, named as PdAg−S) was separated from the reaction system with higher solubility by centrifugation. The electrocatalytic activity and stability of the obtained PdAg NPs could be well optimized when incorporated with carbon (C), which is owing to a synergetic effect. The PdAg−S/C exhibits the highest mass activity with around 1.6 times that of PdAg−L/C and 2 times that of commercial Pd/C, which can be attributed to its larger ECSA and lower adsorption energy of the intermediate to facilitate the direct oxidation of HCOOH molecule. 相似文献