高阶模糊控制器在网络控制系统中的应用

当网络控制系统存在非线性随机延迟时，不能直接使用传统的控制方法。针对这种随机延迟该文提出了高阶模糊控制方法。该方法在经典PID控制器的理论基础上进行改进，增加了系统输出的高阶信息，同时利用模糊控制理论对控制器参数进行在线自适应调节。为此该文首先简要地介绍了网络控制系统中存在的随机延迟，然后分析了延迟引起的非线性特征。结合该文的算法思想和模糊控制器的设计原理给出模糊控制器的设计过程。最后给出了应用此方法的一个仿真实例。     

保留非线性的两级快速P-Q分解状态估计法

提出了一种新的状态估计算法,既保留了量测方程非线性又利用了快速P-Q分解方法,因此数学模型精度高且保留了快速P-Q分解的优点,提高了状态估计的计算精度和速度.采用系统分割方法将大系统分割为多个小系统,分别对每个小系统进行状态估计,然后对各小系统的状态估计结果进行协调,得到整个系统具有同一参考节点的状态估计结果,这样可大大提高状态估计的计算速度,有利于进行大电网的状态估计.在18节点系统上进行的数字仿真实验验证了该方法的有效性.     

Toward a unified description of nonlinearity and frequency dispersion of piezoelectric and dielectric responses in Pb(Zr,Ti)O3

A phenomenological approach is proposed describing both nonlinearity and frequency dispersion in dielectric and piezoelectric properties of lead zirconate titanate, Pb(Zr,Ti)O₃ (PZT), thin films and ceramics. The approach couples the frequency dependent response in form of the power law, 1/ω^β, with the rate-independent nonlinear response described by the Rayleigh law. The main experimental trends are well described by the model.     

pH过程的模糊控制仿真研究

pH过程广泛存在于化工、生物工艺、污水处理、发电等工业过程中，对这一过程进行良好的控制有着十分重要的意义。由于pH过程是一个具有严重非线性及滞后性的被控对象，传统的PID控制难以达到理想的控制效果。本文使用模糊控制技术，设计采用了带有自调整因子的模糊控制器，不仅能较好地处理pH过程的严重非线性和滞后性，而且具有较强的鲁棒性和抗干扰能力。     

Passat B5密封条大变形非线性有限元分析

利用非线性有限元分析软件MARC对Passat B5的车门密封条进行仿真分析,并借助测试装置对实际产品材料参数进行准确测定,解决了该复杂结构的几何非线性、材料非线性和压缩过程边界非线性的有限元分析难点,获得良好的定量分析结果。     

温度传感器非线性补偿电路

通过对一些非线性补偿方法进行实践,本文将对几种简单、实用的非线性补偿电路进行讨论,以供仪表设计、制造及使用的技术人员参考.     

Development of PCA-based cluster quantile regression (PCA-CQR) framework for streamflow prediction: Application to the Xiangxi river watershed,China

In this study, a PCA-based cluster quantile regression (PCA-CQR) method was proposed through integrating principal component analysis and quantile regression approaches into a stepwise cluster analysis framework. In detail, the principal component analysis was adopted to overcome the multicollinearity among the explanatory variables, while the quantile regression approach was used to provide probabilistic information in prediction. The proposed PCA-CQR method can effectively capture discrete and nonlinear relationships between explanatory and response variables. The applicability of PCA-CQR was demonstrated by a case study of monthly streamflow prediction in the Xiangxi River, China. The nonlinearity between the hydro-meteorological variables and the streamflow measurements was characterized through the measure of maximal information coefficient (MIC), which demonstrated the need of the proposed PCA-CQR method. The results showed that the previous monthly streamflow and precipitation, as well as potential evapotranspiration in current month posed significant nonlinear impacts on the streamflow in current month. Three components could well reflect the total variance of the input variables. Comparison between traditional SCA and PCA-CQR showed that the proposed approach could provide more accurate predictions than traditional SCA methods. Moreover, probabilistic forecasts could be provided by PCA-CQR, and the 90% predictive intervals could well bracket the observations in both calibration and validation periods. Also, sensitivity analysis was performed to identify the impacts of the control parameters in PCA-CQR on the performance of the proposed model. The results showed the proposed PCA-CQR improved the robustness of traditional SCA. Finally, comparison among PCA-CQR, GRNN and MLR also showed the effectiveness of the proposed method.     

Multiple-tapped-delay-line hardware-linearisation technique based on wire load regulation

This article describes designing, implementation and tuning processes of multiple-tapped-delay-line (MTDL). Obtained MTDL can be implemented in various field-programmable-logic-devices (FPGA) devices and applied for time-to-digital-converters (TDC) construction. The task of tuning process is the tapped-delay-line (TDL) linearisation, and consists of two stages. The first stage depends on selecting an appropriate configurable-logic-block (CLB) for particular delay-segment realization and selecting proper connection between these blocks. The second tuning stage, that is essential from this article viewpoint, depends on inter CLBs connecting wires delay regulation realized directly by load regulation. The Load regulation depends on connecting an appropriate number of unused three-state-buffers or CLB inputs to the wire which delay is adjusted. Depending on the number of inputs connected to the wire its capacitance changes that influences its time-constant and finally changes its time-delay.The MTDL mathematical model, obtained characteristics and results of time-interval (TI) measurements are also presented. The derived TDL model provides information about how the particular wire delay should be changed and in which order the changes should be executed. This makes the designing process predictable and easy to carry out. Presented characteristics confirm the proper operation of presented linearisation technique. The proper operation of the whole measuring module is confirmed by obtained TIs histograms presentation.     

A new algorithm of the nonlinear adaptive interpolation

The paper presents a new algorithm of NonLinearly Adaptive Interpolation （NLAI）. NLAI is based on both the gradients and the curvature of the signals with the predicted subsection, it is characterized by adaptive nonlinear interpolation method with extracting the characteristics of signals, Experimental research testifies the validity of the algorithm using the echoes of the Ground Penetrating Radar （GPR）. A comparison of this algorithm with other traditional algorithms demonstrates that it is feasible.     

半挂车用空气弹簧弹性特性分析

利用有限元软件和实验方法对空气弹簧的弹性特性进行研究.在前处理软件Hypermesh建立空气弹簧的模型并对其进行网格划分,采用Abaqus/Standard模块对空气弹簧载荷-位移特性进行仿真计算,并利用台架试验测试空气弹簧的弹性特性.结果表明:空气弹簧具有变刚度特性,能有效提高车辆的行驶平顺性;两种方法结果基本一致,验证了有限元分析模型的正确性,为该类型空气弹簧的设计开发提供了可靠的理论依据.