The hierarchical identification principle is stated, and the hierarchical stochastic gradient (HSG) algorithm for the transfer function matrix (TFM) model for multivariable systems is presented.

阐述了递阶辨识原理，提出了传递函数阵模型参数的递阶随机梯度(hsg)辨识方法。

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To reversely calculate structural parameters by using second-order approximate expression of the gradient matrix and Hessian matrix for optimization function in identified optimization results.

利用优化函数的梯度阵和海森矩阵建立函数的二阶近似表达式在已确定的优化结果反向计算结构参数。

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The gray-gradient co-occurrence matrix of the text region is calculated, and the optimum thresholds of segmented grayscale and gradient are found quickly according to the objective function.

首先计算文本区域的灰度-梯度共生矩阵，并根据目标函数快速地找到分割的灰度和梯度最佳阈值；

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