基于混沌理论的弧形闸门支臂振动特性

为了研究弧形闸门支臂的振动问题,采用混沌理论对时间序列进行处理,确定延迟时间τ、嵌入维数m进行相空间重构,并计算时间序列的混沌特征值,进而研究弧形闸门在启闭过程中振动的复杂性。以某水电站弧形闸门支臂振动为研究对象,根据支臂振动加速度原型观测资料,分析不同开度的振动情况,发现启门振动的复杂程度高于闭门工况,小开度的振动复杂程度更高,且支臂振动的复杂程度为与面板连接位置最大,与闸墩连接位置最小,中间位置介于前两者之间。为弧形闸门短期振动预测提供了支持。     

Three-phase four-wire shunt active power filter based on the SOGI filter and Lyapunov function for DC bus control

The three-phase four-wire shunt active power filter (SAPF) was developed to suppress the harmonic currents generated by nonlinear loads, and for the compensation of unbalanced nonlinear load currents, reactive power, and the harmonic neutral current. In this work, we consider instantaneous reactive power theory (PQ theory) for reference current identification based on the following two algorithms: the classic low-pass filter (LPF) and the second-order generalized integrator (SOGI) filter. Furthermore, since an important process in SAPF control is the regulation of the DC bus voltage at the capacitor, a new controller based on the Lyapunov function is also proposed. A complete simulation of the resultant active filtering system confirms its validity, which uses the SOGI filter to extract the reference currents from the distorted line currents, compared with the traditional PQ theory based on LPF. In addition, the simulation performed also demonstrates the superiority of the proposed approach, for DC bus voltage control based on the Lyapunov function, compared with the traditional proportional-integral (PI) controller. Both novel approaches contribute towards an improvement in the overall performance of the system, which consists of a small rise and settling time, a very low or nonexistent overshoot, and the minimization of the total harmonic distortion (THD).     

A CFD-based design scheme for the perforated distributor with the control of radial flow

In the present study, flow homogenization by distributors in chemical apparatus is studied as a process of flow control and its mechanism is reconsidered from the model of resistance to the model of radial flow. This process is composed of four consecutive behaviors: the generation, distribution, conversion of the radial flow and the momentum transfer of axial flow. Based on these flow behaviors, the novel distributor is designed as the combination of perforated plate in the center area and vertical guiding baffles around. Taking the wire-screen catalytic reactor as a case study, numerical simulation is employed to optimize the structure of distributor and a CFD-based design scheme called “flow field analysis scheme” is proposed. Numerical simulation is conducted in the apparatus with a diffuser (inlet D₀ = 500 mm, main part D₁ = 3,000 mm) under the gas velocity of 3.6 m/s (corresponding Re ≈ 12,000). The numerical results from optimized distributor show that compared with the traditional perforated plate, the flow field adjusted by the novel distributor can achieve a better flow uniformity with lower energy consumption. The theoretical analysis and numerical results are also validated and proved by the experimental results.     

免充气塑料轮胎支撑结构对性能的影响

免充气塑料轮胎的支撑结构对轮胎性能有直接影响。本研究提出了一种具有连续支撑结构的免充气轮胎,利用ABAQUS软件,与两种现有免充气轮胎进行应力大小、接地性能以及刚度性能的对比。结果表明:连续支撑结构可改善免充气轮胎的应力,接地压力的分布均匀性;同时,连续支撑结构轮胎的纵向刚度、横向刚度均远好于同规格现有免充气轮胎和子午线轮胎;扭转刚度性能接近同规格子午线轮胎。通过分析可知,连续支撑结构轮胎在复杂工况路面有显著的优势,具有良好的发展前景。     

KJS-Y系列矿用水动力降尘器的改进设计

针对当前KJS-Y系列降尘器效率低的问题,通过调整叶轮轴向间隙与径向间隙参数,分别对不同安装参数的降尘器进行数值模拟,通过数值模拟分析特定截面压力分布情况,确定了叶轮最佳安装参数,大大提高了降尘器的工作效率,同时降低了设计成本。     

基于MASTA的斜齿轮径向剃齿成形仿真分析

以某斜齿轮为研究对象,分析齿轮剃齿加工成形原理,运用MASTA对斜齿轮剃齿加工成形进行仿真分析。仿真结果表明:在斜齿轮径向剃齿成形加工过程中,剃齿刀做径向进给运动和沿自轴旋转运动,对旋转的加工齿轮进行剃齿加工成形;不同半径、齿宽、齿高下加工斜齿轮和剃齿刀齿面变化不同;剃齿加工成形的斜齿轮形状与设计斜齿轮形状基本一致。该研究为斜齿轮加工成形、成形质量和加工效率的提高提供理论依据。     

扩孔钻头在水平定向井中的应用

传统扩孔钻头在长距离水平定向井应用过程中出现泥包问题时,由于钻速变慢易造成钻进轨迹偏离原井眼,而且起钻时由于抽吸压力对井壁的作用易造成井壁压差坍塌,影响井下钻具仪器安全,增加辅助时间和钻井成本。为解决该问题,通过总结施工经验,结合数值模拟理论实验优化改进扩孔钻头,并在山西某井田煤层气水平井钻井工程项目中进行工业性试验,与传统扩孔钻头相比平均钻时减少38.9%,大大减少辅助操作时间,钻进效率提高的同时减少钻井成本。     

基于VMD瞬时能量与GA- RBF的滚动轴承故障诊断

针对滚动轴承早期故障的有效识别,提出了一种基于VMD瞬时能量与GA优化的RBF神经网络的滚动轴承故障诊断方法,可以有效对滚动故障做出诊断。首先,VMD将滚动轴承振动信号进行分解成合适数目的本证模态函数;其次,计算本证模态函数分量的瞬时能量并组成特征向量;最后,将特征向量输入到GA优化的RBF神经网络实现轴承故障识别。通过滚动轴承故障诊断实验对该方法进行验证。结果表明,该方法识别滚动轴承故障的准确率为96.43%,较默认参数的RBF神经网络和EEMD瞬时能量与GA-RBF神经网络有明显的提高,证明了所提方法的可行性。     

水泵转子径向圆跳动检测数据修正

针对应用千分表和电涡流传感器进行水泵转子径向圆跳动检测时,检测结果出现正弦变化规律的现象,分析了安装偏心误差对检测结果的影响原理,建立了相应的数学模型.运用最小二乘拟合法计算出变化曲线的幅值及初相位,从而消除偏心误差实现误差分离.结果表明,当将所提方法应用在水泵转子径向圆跳动检测的工程实践中时,可以有效消除安装偏心引起的误差,从而提高检测精确度.拟合平方和误差约为0. 000 9,所提方法可以广泛应用于轴类工件的检测实践.     

基于机器视觉的轮胎表面缺陷检测系统的研究与应用

在传统的轮胎表面缺陷依靠人工检测,存在劳动强度高、受人的主观影响大以及效率低下的问题。针对这一现象,研究了一种基于机器视觉的轮胎表面缺陷3D检测系统。该系统依靠机器视觉系统获取检测轮胎的表面图像,然后创建3D模型、判定缺陷类型,最终实现实时自动预警,为轮胎生产商提供一种自动化检测方案。系统集成了先进的技术、软件和工具,配套的信息管控系统可以对轮胎型号和生产数据进行采集、存储、分析,以便在生产过程中实现更高效、更可靠的质量控制,具有较高的实际应用推广价值。