Stochastic optimal control via Bellman''s principle

This paper presents a strategy for finding optimal controls of non-linear systems subject to random excitations. The method is capable to generate global control solutions when state and control constraints are present. The solution is global in the sense that controls for all initial conditions in a region of the state space are obtained. The approach is based on Bellman's principle of optimality, the cumulant neglect closure method and the short-time Gaussian approximation. Problems with state-dependent diffusion terms, non-closeable hierarchies of moment equations for the states and singular state boundary condition are considered in the examples. The uncontrolled and controlled system responses are evaluated by creating a Markov chain with a control dependent transition probability matrix via the generalized cell mapping method. In all numerical examples, excellent controlled performances were obtained.     

晶闸管整流装置的过电压及其抑制

本文主要分析晶闸管整流装置在运行中经常产生的过电压现象，同时对过电压的危害及其抑制等问题进行探讨。     

降低电感接触式测量仪系统误差的方法研究

本文分析了传统电感接触式测量仪的系统误差,提出了一种基于垂直位移扫描工作的表面轮廓综合测量仪的整体设计方案,克服了接触式测量仪的大量程和高精度之间的矛盾,给出了实际测量结果。     

基于最小特征值非线性修正的快速噪声水平估计算法

鉴于从噪声图像上提取的原生图块协方差矩阵的最小特征值与噪声水平值之间具有显著的相关性,提出一种基于多项式回归技术训练非线性映射模型,直接将原生图块最小特征值修正为最终的噪声水平预测值的快速噪声水平估计算法。首先,选择具有代表性且无失真的自然图像作为训练图像集合;然后,对这些图像施以不同程度的高斯噪声构成样本训练图像库。在此基础上,提取各个噪声样本图像的原生图块, 并使用PCA变化得到原生图块协方差矩阵的最小特征值;最后,利用多项式回归技术构建最小特征值与噪声水平值之间的非线性修正模型。实验表明,与现有算法相比,改进算法对高、中、低各级别的噪声都能鲁棒地进行预测,尤其在低水平噪声方面表现出色,在预测准确度和执行效率两方面具有显著的综合优势。     

Efficient control of a 3-link planar rigid manipulator using self-regulated fractional-order fuzzy PID controller

A self-regulated fractional-order fuzzy proportional–integral–derivative (SRFOFPID) controller is proposed to control a highly non-linear, complex and coupled 3-link planar rigid robotic manipulator in a virtual industrial environment. Industrial environment was simulated by introducing different kind of disturbances in the system and sensor noise. Proposed SRFOFPID controller is a direct non-linear adaptive controller having self-regulating feature and has been realized using fractional-order operators i.e. integrator and differentiator in self-regulated integer-order fuzzy PID (SRIOFPID) controller. Gains of SRFOFPID and SRIOFPID controllers are optimized using Backtracking Search Algorithm by minimizing an amalgamation of integral absolute error signal and integral absolute change in control signal as cost function. Performance of SRFOFPID and SRIOFPID controllers are assessed and compared with reference path under virtually simulated industrial environment. Presented intensive simulation studies revealed that both the controllers offered decent reference trajectory tracking performance under nominal operating conditions while SRFOFPID controller offered exceptionally robust performance under industrial scenario and uncertainties. Finally, the stability analysis of overall closed loop system is performed using small gain theorem and necessary and sufficient bounded-input and bounded-output stability conditions are established.     

茂名石化乙苯/苯乙烯精馏塔的改造

茂名石化采用新型高效脉冲规整填料成功对原板波纹填料乙苯/苯乙烯精馏塔进行了改造,取得了很好的效果,塔顶苯乙烯质量分数由原来的5%降至1%以下,苯乙烯质量分数达到99.9%以上,乙苯质量分数小于500×10-6。     

基于键合图模型的新型故障树故障诊断方法

针对传统故障树的生成及应用缺陷,研究了基于键合图模型的新型故障树故障诊断方法.该方法根据系统键合图模型推导出时间因果图,进而建立系统故障树,由此产生一个用于反映系统行为变化的假设故障集合;同时,推理预测每个故障的后效特征,并与观测特征相比较,修正假设故障集,最终定位故障源.仿真结果验证了此故障诊断方法应用的可行性和故障诊断的准确性,具有广泛的应用前景.     

Statistical analysis of the characteristics of some basic mass-produced passive electrical circuits used in measurements

Statistical properties of some basic mass-produced passive electrical circuits used in measurements are analyzed in this paper, using methods for expressing measurement uncertainty of indirectly measured quantities. The focus of this paper is on electrical circuits whose defining parameters are obtained as non-linear functions of component parameters. Variants of voltage divider and Wheatstone bridge circuits significant for measurement practice are investigated in detail. Even if distributions with symmetrical probability density functions (PDFs), such as uniform or normal, are adopted for the parameters of the components comprising a circuit, non-linearity of the circuit function gives rise to asymmetry in the PDF of the circuit’s parameter. The asymmetry of the PDF causes the mean and the nominal value of the circuit parameter to differ.     

Linear and non-linear forced response of a conical, ducted, laminar premixed flame

This paper presents an experimental study on the dynamics of a ducted, conical, laminar premixed flame subjected to acoustic excitation of varying amplitudes. The flame transfer function is measured over a range of forcing frequencies and equivalence ratios. In keeping with previous works, the measured flame transfer function is in good agreement with that predicted by linear kinematic theory at low amplitudes of acoustic velocity excitation. However, a systematic departure from linear behaviour is observed as the amplitude of the velocity forcing upstream of the flame increases. This non-linearity is mostly in the phase of the transfer function and manifests itself as a roughly constant phase at high forcing amplitude. Nonetheless, as predicted by non-linear kinematic arguments, the response always remains close to linear at low forcing frequencies, regardless of the forcing amplitude. The origin of this phase behaviour is then sought through optical data post-processing.     

空分设备调整阶段进塔空气量波动分析及操作

空分设备启动进入调整阶段时,常常会发生进塔空气量周期性波动的现象。文章分析了原因及其对空分设备安全、稳定运行的危害,并从生产实际出发,提出了相应的操作措施。