学术论文写作也应追求形式的完美

学术论文的形式是学术研究成果的载体,它的完美与否直接影响到论文内容的表达与读者对研究成果的接受程度。因此．对论文的形式也必须给予高度的重视。学术论文的结构是其表现形式的重要方面。学术论文从结构上看,主要包括题名、作者署名及工作单位、摘要、关键词、正文、参考文献等组成部分,这些组成部分的撰写既要遵循相应的格式规范,又要追求表达的艺术与技巧。     

高校女生课余体育锻炼现状与对策研究——以华北电力大学为例

运用文献资料、问卷调查、数理统计和访谈等方法,对高校女生课余体育锻炼的现状进行调查分析,了解高校女生课外体育活动的态度、动机、频次、锻炼时间、内容以及影响因素,并提出相应的对策,以期为深化高校体育课程改革提供参考。     

一类非线性发展方程的显式精确解

对文献[8]提出的基于Hopf—Cole变换和试探函数的方法进行了一些扩展,获得了一类非线性发展方程的大量显式精确解,其中包括行波解、孤波解和奇异行波解等显式精确解。     

论高校基层党组织在和谐校园建设中的作用

高校和谐校园建设是构建社会主义和谐社会必不可少的重要组成部分。高校基层党组织在和谐校园建设中的核心作用主要体现在组织领导、班子建设、组织建设和思想政治工作等方面;其战斗堡垒作用主要通过服务群众、凝聚人心、化解矛盾等途径来实现;构建和谐校园的落脚点是充分发挥广大党员特别是学生党员的先锋模范作用。     

Stochastic synchronization of semi-Markovian jump chaotic Lur’e systems with packet dropouts subject to multiple sampling periods

This paper is concerned with the problem of stochastic synchronization for semi-Markovian jump chaotic Lur’e systems. Firstly, packet dropouts and multiple sampling periods are both considered. By input-delay approach and then fully considering the probability distribution characteristic of packet dropouts in the modeling, the original system is transformed to a stochastic time-delay system. Secondly, by getting the utmost out of the usable information on the actual sampling pattern, the probability distribution values of stochastic delay taking values in m given intervals can be explicitly obtained. Then, a newly augmented Lyapunov-Krasovskii functional is constructed. Based on that, some sufficient conditions in terms of linear matrix inequalities (LMIs) are derived to ensure the stochastic stability of the error system, and thus, the master system stochastically synchronize with the slave system. Finally, the effectiveness and potential of the obtained results is verified by a simulation example.     

Threshold behavior in a stochastic delayed SIS epidemic model with vaccination and double diseases

In this paper, we investigate the threshold dynamics of a stochastic delayed SIS epidemic model with vaccination and double diseases which make the research more difficult. We establish sufficient conditions for extinction and persistence in the mean of the two diseases. We also obtain the threshold between persistence in the mean and extinction of the stochastic system. It is shown that: (i) time delay and environmental white noise have important effects on the persistence and extinction of the two diseases; (ii) the two diseases can coexist under certain conditions. Finally, some numerical simulations are provided to demonstrate the analytical results.     

Output feedback based simultaneous stabilization of two Port-controlled Hamiltonian systems with disturbances

In motor system control design, a single controller is usually employed to simultaneously control two or more motors for saving costs, which also achieves the computational simplification of control. In practical Hamiltonian systems control, more systems also need to be stabilized by a single controller under some working conditions. Thus, this paper studies simultaneous stabilization problem of two nonlinear Port-controlled Hamiltonian (PCH) systems with disturbances by a composite controller. Based on the Hamiltonian structure properties, two PCH systems are combined together to generate an augmented PCH system by utilizing output feedbacks firstly. Then, to estimate disturbances effectively, it is essential to design a nonlinear disturbance observer (NDOB) and the estimate is employed to feedforward compensate the effects of disturbances. Next, combining the output feedback part and the disturbance compensation part together, a simultaneous stabilization controller is developed. Subsequently, it is proved that the closed-loop system under the proposed controller is asymptotically stable. Finally, an example with simulations reveals that the proposed method is effective.     

Dynamical analysis and optimal control simulation for an age-structured cholera transmission model

Cholera is an infectious disease caused by the bacterium vibrio cholerae, which can lead to widespread epidemics in the deterioration of public health systems or the associated infrastructure. Vaccination and water sanitation are two well-known methods for the prevention and intervention of cholera epidemics. In this paper, we propose an age-structured cholera model that incorporates both the environment-to-human and human-to-human transmission pathways and that includes host vaccination and water sanitation as disease control measures. We rigorously investigate the threshold dynamics of this model using the basic reproduction number derived from our analysis. Meanwhile, we perform an optimal control study to explore cost-effective intervention strategies for cholera. Our numerical simulation results show that the outcome of the optimal control is shaped by the complex interactions among the age structure of the hosts, the costs of the control measures, the transmission modes of the disease, and the different approaches of cholera intervention.     

Adaptive disturbance attenuation for a class of uncertain nonlinear systems: A double-gain nonlinear observer method

This paper is concerned with the problem of adaptive disturbance attenuation for a class of nonlinear systems. The traditional adaptive methods are almost impossible to compensate the time-varying unknown disturbance by designing parameter adaptive laws without a priori knowledge about the bounds of external disturbances. To solve the problem, a new strategy is proposed by constructing an augmented system where the external disturbance is considered as another component of the augmented state vector. Based on this, a double-gain nonlinear observer is employed to estimate the state of the augmented nonlinear system. Further, an output feedback control strategy is designed, and it is proved that the proposed strategy ensures that all the signals are bounded and the tracking error exponentially converges to an adjustable compact set. Finally, an example is performed to demonstrate the validity of the proposed scheme.     

Sampled observer-based adaptive output feedback fault-tolerant control for a class of strict-feedback nonlinear systems

This paper studies the sampled outputs-based adaptive fault-tolerant control problem for a class of strict-feedback uncertain nonlinear systems, where the nonlinear functions are allowed to include the unmeasured system states. Within the framework, a sampled output observer is introduced to jointly estimate the system states and parameters. By combining the estimated states and the supervisory switching strategy, an adaptive fault-tolerant controller is designed to achieve the desirable tracking performance. By using Lyapunov stability theory, it is proved that all the signals of the closed-loop systems are bounded and the tracking error converges to an adjustable neighbourhood of the origin eventually both in the fault free and faulty cases. Especially, if the outputs are available all the time, the proposed output feedback fault-tolerant control method can ensure the tracking error satisfy the prescribed performance bounds regardless of the faults. Finally, two examples are used to illustrate the effectiveness of the proposed method.