Second-Order Consensus of Multiple Agents with Bounded Control Inputs and Preserved Network Connectivity

This paper investigates second-order consensus of multi-agent systems with a virtual leader of varying velocity while preserving network connectivity.We propose a novel second-order consensus algorithm with bounded control inputs.Under the condition that the initial network is connected,the network will be connected all the time and all agents and the virtual leader can attain the same position and move with the same velocity.A simulation example is proposed to illustrate the effective of the proposed algorithm.     

带根部间隙压气机静叶流道流动结构研究

本文采用数值模拟的方法对某低速压气机静叶流道内的流动结构进行了研究。设计工况下,带根部间隙的静叶流道中主要存在三个大尺度旋涡结构,分别为上通道涡、刮削涡和集中脱落涡,这些涡系在生成和发展过程中相互作用,流道内总奇点数先增加后减小,但都严格遵循了流道奇点数拓扑法则。     

Properties of nonadiabatic combustion waves in competitive exothermic reactions

We study the properties of travelling combustion waves in a diffusional thermal model with a two-step competitive exothermic reaction mechanism considering the system in one spatial dimension under nonadiabatic conditions. Based on the notion of the crossover temperature, the model is first examined analytically to predict the behaviour of travelling combustion waves in the limit of large activation energies. It is then studied numerically over a wide range of parameter values, such as those describing the ratios of the enthalpies, pre-exponential factors and activation energies. It is demonstrated that the nonadiabatic flame speed as a function of these parameters is a single-valued monotonic function with two flame regimes identified, each of which represents the region of the parameter values when one reaction dominates the other, while the flame speed as a function of the activation energy of the reaction R2 (the exothermicity parameter) is either a c- or m-shaped. The extinction conditions for these two flame regimes are investigated analytically.     

K荧光辐射场MC模拟与能谱测量分析

K荧光辐射装置可填补国内超大型测量面积核辐射探测器计量检定需求,该装置具通量高、能量点多、单色性好、有成本低、即开即用等优势。其原理是X射线光机发射出的X射线轰击辐射体材料产生多种特征X射线即荧光射线,在荧光射线出射路径上加入次级过滤器吸收掉多余的射线以提高荧光纯度,辐射体以及次级过滤器的材料厚度值与荧光产额、纯度直接相关。通过MC(Monte Carlo)程序计算荧光装置各项指标参数结果,指导后期试验装置的建立和研究,MCNP5(Monte Carlo N Particle Transport Code)软件模拟Cs₂SO₄辐射体数据表明：荧光装置具有良好的屏蔽和准直的效果,荧光以辐射体中心垂直面呈对称逐渐减小分布;荧光产额随着辐射体厚度的增加逐渐增大,但存在相对饱和厚度值,即辐射体达到一定厚度值以后,荧光产额不再随辐射体厚度的增加而增大,而是趋于饱和状态;为获取单一能量荧光辐射场,在荧光出射束方向增加次级过滤器TeO₂材料,其吸收L,K_β射线会远远大于K_α射线,以达到消除L...     

Stability of strongly nonlinear normal modes

It is shown that a transformation of time can allow the periodic solution of a strongly nonlinear oscillator to be written as a simple cosine function. This enables the stability of strongly nonlinear normal modes in multidegree of freedom systems to be investigated by standard procedures such as harmonic balance.     

大长径比、高密实火药床点火管点传火特性的影响因素

利用计算程序对影响大长径比、高密实火药床点火管点火性能的主要因素进行了对比模拟,讨论了不同结构尺寸和装填条件下的点传火性能,通过对计算结果的分析,总结了结构参数和装填条件对大长径比、高密实火药床点火管点传火性能的影响规律：小孔直径、首孔高度、单位长度小孔面积及装填密度显著影响点火压力及点传火性能;小孔直径、首孔高度及单位长度小孔面积是影响破膜后泄压速度的主要因素,而装填密度会影响药床的透气性及火焰传播的通畅性,均对点火安全性、瞬时性及一致性产生重要影响作用。

     

Simulation of roll grinding system dynamics with rotor equations and speed control

A nonlinear dynamical model for paper machine roll grinding process is investigated through a group of delay differential equations with one constant time-delay. In this model, the time-delay effect is originated from shape error traces on the surface of the roll. The contact interaction of the roll and the grindstone is based on the wear theory, and the lateral deformations of the roll as a simply supported continuous beam element inside a rotational coordinate frame and the rotational rigid body vibration system are considered. The PD-controllers of the roll and the grindstone drives are also included. The numerical simulations for time-history responses provide a view of the stability of this grinding process for the design, analysis and verification of industrial roll grinding measurements in future.     

Dispersion and attenuation of gravity waves in ice: a two-layer viscous fluid model with experimental data validation

A theoretical model describing the propagation of gravity waves on ice-covered waters is developed. The ice–water system is approximated as a two-layer viscous and immiscible Newtonian fluid. The model is validated against existing viscous models by using laboratory and in situ collected wave data.     

Nonlinear flexural response of laminated composite plates under hygro-thermo-mechanical loading

The paper deals with Chebyshev series based analytical solution for the nonlinear flexural response of the elastically supported moderately thick laminated composite rectangular plates subjected to hygro-thermo-mechanical loading. The mathematical formulation is based on higher order shear deformation theory (HSDT) and von-Karman nonlinear kinematics. The elastic foundation is modeled as shear deformable with cubic nonlinearity. The elastic and hygrothermal properties of the fiber reinforced composite material are considered to be dependent on temperature and moisture concentration and have been evaluated utilizing micromechanics model. The quadratic extrapolation technique is used for linearization and fast converging finite double Chebyshev series is used for spatial discretization of the governing nonlinear equations of equilibrium. The effects of Winkler and Pasternak foundation parameters, temperature and moisture concentration on nonlinear flexural response of the laminated composite rectangular plate with different lamination scheme and boundary conditions are presented.