查询词典 implicit differential equation

No reasonable scientific or theoretical basis is given to explain the jump from difference equation to differential equation till now.

从差分方程到微分方程的跨越，缺乏充分的科学基础和理论依据。

Then, we examine the general random walk model in mathematics and derive a two-order difference equation and its corresponding differential equation.

为了得到可与生物试验加以比较的结论，需要求解在给定边界条件下的关于随机荡步模型的二阶差分方程。

Through the limit difference method,the partial differential equation of the semiconductor device is transformed into a difference equation,and the corresponding boundary condition is discretized with high accuracy.

采用有限差分法把器件工作的偏微分方程转化为差分方程，并将相应的边界条件转化为精度较高的离散化形式。

Sales, in turn, is related to advertising expenditures via a differential or difference equation termed a state equation.I...

本文仅介绍其中两类最重要的广告动态最优控制模型，并在此基础上对所介绍的模型进行评析，同时指出进一步研究的方向。

Transpiration ; mathematical analysis ; heat transfer ; differential equation ; difference equation.

发汗；数学分析；热传导；微分方程；差分方程

It is known theoretically that to the variational problem with weak constraints in cost functional J, its Euler equation can be discreted into difference format, by using matrix theory and difference method of partial differential equation we know that there exists optimal selection of weight factors in the cost functional under the condition of minimal variance between analysis field and ideal field.

从理论上可知，对于目标泛函J带有约束条件的变分问题，将其Euler方程离散成差分形式，利用矩阵理论和偏微分方程的差分方法，则目标泛函的权重因子，在分析场和理想场的最小方差意义下存在最优选取。

It's proved that the long duration response is stable under stationary random excitation, when the mean equation of the temperature in all parts of heat conductor shows no difference with the heat conduction differential equation under classical stationary heat conduction condition.

研究表明，在平稳随机激励下，导热系统的长时间响应也是平稳的。

The dynamic model of flexible multibody system is derived by first kind of Lagrange equation and also the constraint equations for velocity are obtained, the final expression of the dynamic equation is hybrid one of algebra and differential.

首先利用第一类Lagrange方程建立了多柔体系统的动力学模型，并建立了速度意义下的约束方程，方程的最终表现形式为微分／代数混合方程组。

To obtain state matrix A of linear differential algebra equation, the equation set of the model, then the eigenvalue of state matrix A and its effection on sensitivity of excition system are calculated by QR method.

对模型方程组进行线性化，得到线性微分-代数方程的状态矩阵A；使用QR法，计算状态矩阵A的特征值及特征值对发电机励磁系统参数灵敏度。

Among used machine learning methods, the gradient descent method is widely used to train various classifiers, such as Back-propagation neural network and linear text classifier. However, the gradient descent method is easily trapped into a local minimum and slowly converges. Thus, this study presents a gradient forecasting search method based on prediction methods to enhance the performance of the gradient descent method in order to develop a more efficient and precise machine learning method for Web mining.However, a prediction method with few sample data items and precise forecasting ability is a key issue to the gradient forecasting search method. Applying statistic-based prediction methods to implement GFSM is unsuitable because they require a large number of data items to model a prediction model. In the contrast with statistic-based prediction methods, GM(1,1) grey prediction model does not need a large number of data items to build a prediction model, and it has low computational load. However, the original GM(1,1) grey prediction model uses a mathematical hypothesis and approximation to transform a continuous differential equation into a discrete difference equation in order to model a forecasting model.

其中梯度法是一个最常被使用来实现机器学习的方法之一，然而梯度法具有学习速度慢以及容易陷入局部最佳解的缺点，因此，本研究提出一个梯度预测搜寻法则(gradient forecasting search method， GFSM)来改善传统梯度法的缺点，用来提升一些以梯度学习法则为基础的分类器在资讯探勘上的效率与正确性；而一个所需资料量少、计算复杂度低且精确的预测模型是梯度预测搜寻法能否有效进行最佳解搜寻之关键因素，传统统计为基础之预测方法的缺点是需要较大量的数据进行预测，因此计算复杂度高，灰色预测模型具有建模资料少且计算复杂度低等优点，然而灰色预测理论以连续之微分方程式为基础，并且透过一些数学上的假设与近似，将连续之微分方程式转换成离散之差分方程式来对离散型资料进行建模及预测，这样的作法不尽合理，且缺乏数学理论上的完备性，因为在转换过程中已经造成建模上的误差，且建模过程仅考虑相邻的两个资料点关系，无法正确反应数列未来的变化趋势。

There had been a moment during the breakfast meeting, though, after the backslapping and the small talk and when all of us were seated, with Vice President Cheney eating his eggs Benedict impassively and Karl Rove at the far end of the table discreetly checking his BlackBerry, that I witnessed a different side of the man.

那次早餐会期间，在表示过关心和寒暄以后，我们所有人坐了下来，我注意观察了一下，副总统切尼面无表情地吃着班尼迪克蛋（Eggs benedict，源自美国，以英式松饼、火腿、水煮蛋以及荷兰酱组合而成），卡尔。罗夫在餐桌的远端谨慎地经常查看他的黑莓手机，我目睹了他所不为人知的一面。

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