皮带轮旋压机床用嵌入式开放性数控系统的研究

为了增强机床的柔性,缩短安装和调试的时间,使系统能随时根据用户的要求更新设备的软、硬件,将嵌入式开放性数控系统应用于四工位皮带轮旋压机床,并根据旋压机床的特点对嵌入式开放性数控系统的硬件和软件架构进行了重点分析和研究,结果表明:以PC机为核心的NC嵌入PC型硬件架构使得数控系统有较好的开放性、集成性和可靠性,而上下层型软件架构可以对实时性任务和非实时性任务等多个任务进行并行处理,极大地增加了CPU利用率.最后给出了该数控系统的二轴联动插补和位置控制执行程序.     

碟形容器封头冷旋压过程三维有限元数值分析

依据有限元理论,对冷旋压碟形封头的变形机理进行了分析,应用ANSYS软件对其变形过程进行了数值模拟研究,得出了封头在不同位置成形时应力、应变的分布规律。分析了应力、应变对变形的影响,计算了旋压力,为优化工艺参数提供了有效方法和可靠依据。     

关于涤纶POY纺丝油剂发展问题的思考

本文针对我国涤纶长丝的纺丝技术与生产能力方面所存在的问题,提出了有关POY纺丝油剂发展对策的见解。     

奥氏体不锈钢高精度薄璧管的旋压工艺研究

本文叙述了1Cr18Ni9Ti钢高精度薄壁管的旋压工艺。该薄壁管璧厚为0.35mm,长度600mm,壁厚偏差≤0.01mm,粗糙度Rα0.63～1.25μm。通过试验找出了比较理想的旋压工艺参数,文章还讨论了影响旋压薄璧管精度的主要因素。     

水电站和蓄能电站事故旋转备用效益评估模型

本文提出了水电站和蓄能电站承担事故旋转备用时的效益评估模型和算法，其独特之处是考虑了各台机组故障之间以及机组故障与负荷变化之间的相关性和不同类型机组的技术、经济、可靠性特征，并通过概率生产模拟从生产成本和可靠性指标两方面评价方案的优劣．实例分析表明，结果是合理的，并具有较高的实用价值．     

Vibration analysis of a rotating flexible shaft–disk system

Free vibrations of a spinning disk–shaft system are analysed using the finite-element method. The spinning disk is described by the Kirchhoff plate theory. The shaft is modelled by a rotating beam. Using Lagrange’s principle and including the rigid-body translation and tilting motion, equations of motion of the spinning flexible disk and shaft are derived consistently to satisfying the geometric compatibility conditions on the internal boundaries among the substructures. The finite-element method is then used to discretize the derived governing equations. The method is applied to the shaft–disk spinning system. The sensitivity to the running speed as well as the effect of both disk flexibility and boundary condition on the natural frequencies of the spinning system are numerically investigated.     

Robust Graded Sliding Mode Tracking Control for Low Speed Spinning Ballistic Missiles

The nonlinear dynamic model of spinning ballistic missiles is established during the first boosting phase of the missile. Based on the conventional backstepping sliding mode control and the assumption of a two time-scale separation of missile dynamics, a graded sliding mode controller is designed with two sub-sliding surfaces which have invariability to external disturbances and parameter perturbations, and a matrix which comprises three first order low pass filters is introduced to prevent ＂explosion of terms＂. Owing to the upper bounds of the uncertainties are difficult to obtain in advance, adaptive laws are introduced to estimate the values of the uncertainties in real-time. Eventually, the numerical simulation results given to show the proposed controller can ensure the steady flight of missiles.     

转杯纺纺制竹节纱的工艺研究

在改变喂给罗拉速度纺制竹节 的条件下，对转杯纺纺制竹节纱的基本工艺参数进行了理论研究，得到了关于粗节倍数和竹节长度的模型，并通过实验测试验证了理论的正确性，也证明了彩和改变喂给罗拉速度纺制竹节纱的可行性。     

变频器在纺丝冷却系统中的应用

本文介绍I／A series控制的变频器纺丝冷却系统。本系统通过I／A series、变频器、压力变送器等设备来实现涤纶短纤维纺丝生产的自动控制。文中详细介绍了系统的组成、控制原理及硬件设计。     

Modal dynamics of self-excited azimuthal instabilities in an annular combustion chamber

In this paper we describe the time-varying amplitude and its relation to the global heat release rate of self-excited azimuthal instabilities in a simple annular combustor operating under atmospheric conditions. The combustor was modular in construction consisting of either 12, 15 or 18 equally spaced premixed bluff-body flames around a fixed circumference, enabling the effect of large-scale interactions between adjacent flames to be investigated. High-speed OH^∗ chemiluminescence imaged from above the annulus and pressure measurements obtained at multiple locations around the annulus revealed that the limit cycles of the modes are degenerate in so much as they undergo continuous transitions between standing and spinning modes in both clockwise (CW) and anti-clockwise (ACW) directions but with the same resonant frequency. Similar behaviour has been observed in LES simulations which suggests that degenerate modes may be a characteristic feature of self-excited azimuthal instabilities in annular combustion chambers. By modelling the instabilities as two acoustic waves of time-varying amplitude travelling in opposite directions we demonstrate that there is a statistical prevalence for either standing m = 1 or spinning m = ±1 modes depending on flame spacing, equivalence ratio, and swirl configuration. Phase-averaged OH^∗ chemiluminescence revealed a possible mechanism that drives the direction of the spinning modes under limit-cycle conditions for configurations with uniform swirl. By dividing the annulus into inner and outer annular regions it was found that the spin direction coincided with changes in the spatial distribution of the peak heat release rate relative to the direction of the bulk swirl induced along the annular walls. For standing wave modes it is shown that the globally integrated fluctuations in heat release rate vary in magnitude along the acoustic mode shape with negligible contributions at the pressure nodes and maximum contributions at the pressure anti-nodes.