A minimax optimal control strategy for uncertain quasi-Hamiltonian systems

A minimax optimal control strategy for quasi-Hamiltonian systems with bounded parametric and/or external disturbances is proposed based on the stochastic averaging method and stochastic differential game. To conduct the system energy control, the partially averaged Ito stochastic differential equations for the energy processes are first derived by using the stochastic averaging method for quasi-Hamiltonian systems. Combining the above equations with an appropriate performance index, the proposed strategy is searching for an optimal worst-case controller by solving a stochastic differential game problem. The worst-case disturbances and the optimal controls are obtained by solving a Hamilton-Jacobi-Isaacs （HJI） equation. Numerical results for a controlled and stochastically excited DulTlng oscillator with uncertain disturbances exhibit the efficacy of the proposed control strategy.     

Analytical Method Determining Resonant Response of Blade with Dry Friction Damper

Service failures of turbine blades in many instancescan be attributedto highcyclefatigue caused bylarge reso-nance stress .As dryfrictioninterface may be the most im-portant source of energy dissipation,thefriction damperis atypical devicetoreduce vibrati…     

An electricity price model with consideration to load and gas price effect

INTRODUCTIONInanelectricitymarket,theelectricitypriceshaveimportantimpactonsuchdiverseis suesasassetpricing ,contracting ,planning ,andchoiceofoperationpoliciesforgenerationandtransmissionofelectricity .Analysisofthehistor icalelectricitypricessuggestedth…     

MRS study on lentiform nucleus in idiopathic Parkinson''s disease with unilateral symptoms

Objective: To investigate changes in magnetic resonance spectroscopy (MRS) of lentiform nucleus during the early stage of Parkinson's disease. Methods: Twenty-five patients with idiopathic Parkinson disease with unilateral symptoms (IPDUS) and 25 healthy volunteers were enrolled in this study. MRS of the lentiform nucleus in each patient was taken and then concentrations of N-acetylaspartate (NAA), Creatine (Cr) and Choline (Cho) were calculated. Results: Compared to that in the control, NAA/(Cho Cr) was significantly lower in the lentiform nucleus contralateral to symptoms and even that in the ipsilateral side in IPDUS patients (all P＜0.05); while there was no difference between the two sides in the healthy volunteer (P＞0.05). The ratio of NAA/(Cho Cr) ipsilateral to the sympatomatic side of the patient was also lower than that of the control (P＜0.05). Conclusions: there might be some changes with MRS on the lentiform nucleus during the early stage of idiopathic Parkinson's disease with unilateral symptom. MRS may be one of the reliable methods for early or even sub-clinical diagnosis.     

美声通俗民族唱法之间的关系及其发声原理

作者通过分析美声、通俗、民族三种唱法在发声原理上的异同,进一步认识和理解三者之间的共性与个性.作为歌唱者要不断地开拓自己的演唱路子,提高自己的发声技术水平,以丰富自己的歌唱.     

关于电子镇流器的两个理论问题

电子镇流器是集点燃与限流为一体的电子装置。建立气体放电灯不加功率因数补偿,荧光灯电子镇流器串联电压谐振的数学模型。采用串联电压谐振产生高压起辉,必须采取过流保护措施。电子镇流器高次谐波的产生及其所带来的危害。     

原理性和研究性核磁共振实验教学探索与实践

实践了原理性和研究性核磁共振实验的教学改革,从推进实验室开放、允许自主设计实验方案、自主开展实验等方面,为学生创造自主探索的环境和条件,对学生进行系统性的科学研究训练,激发学习兴趣,培养独立分析问题、解决问题的能力,总体上提高了核磁共振实验教学质量以及仪器设备的利用率,效果良好。     

微波综合实验仪的设计

设计了一种微波综合性学生实验仪器,能进行电子自旋共振、微波特性研究和光速的精确测量。设备由微波振荡源、晶体检波器、微波频率计、驻波测量线、示波器、全反射铜板、多孔径铜质反射器等元器件组成,介绍了微波电子综合实验仪的工作原理及制作方法。该设计节约了资源,提高了仪器的利用效率,在近代物理实验应用中有着良好的发展前景。     

一类分数阶边值问题积分共振条件解的存在性

利用Mawhin的连续性定理及迭合度理论,讨论了一类分数阶非线性微分方程带积分共振边界条件解的存在性,得到了解存在的充分条件.     

Construction of hollow mesoporous silica nanoreactors for enhanced photo-oxidations over Au-Pt catalysts

It is highly desirable to design hollow structures with multi-scale functions by mimicking cells for the construction of micro/nanoreactors. Herein, we report the construction of hollow-structured submicrometer-photoreactors with bimetallic catalysts loaded within mesoporous silicas. The synthesis parameters are optimized to study the evolution of hollow structure through hydrothermal treatment and an ‘adhesive-contraction’ formation mechanism is proposed. AuPt@HMZS catalysts exhibited a broader absorbance region under visible light and the adsorption edge displayed a red-shift, indicating the strong metal–metal interactions at the alloy interface. The reaction performance of the coupled Au-Pt catalysts can be tuned to achieve excellent catalytic activity in cinnamyl alcohol oxidation to cinnamic acid for 3.1 mmol g⁻¹ with 99% selectivity. The proposed strategy to build hollow structures as multifunctional micro/nanoreactors is promising for the design of high-performance and sustainable catalysts for chemical synthesis.