查询词典 gradient

The diffusion of mass or heat across two phases is extensively involved in chemical processes. Because of the effect of this kind of diffusion, there will be a inhomogeneous distribution of material concentration and then a gradient of interfacial tension will be occured on the interface of the two phases. When the gradient tends to a certain value, the natural convection would be induced derivatively, and orderly convective cells would appear in the system simultaneously. This is the so-called Marangoni phenomenon.

在化工过程中，广泛涉及到两相间的质量或热量扩散，由于这种扩散的作用，将在相界面处产生物质浓度的不均匀分布，从而出现界面张力梯度，这种梯度达到一定值以后，将出现派生的自然对流运动，并且在系统中呈现有序的对流胞结构，这就是所谓的Marangoni现象。

Taking the gradient property of piezoelectric parameters g-(31),elastic compliance parameters S-(33) and density ρ along z direction into account,some parameter identification methods for a functionally gradient piezoelectric material are studied in the present analysis.

当考虑压电材料的压电参数g31，弹性参数S33和材料密度ρ沿厚度呈梯度变化时，通过测量压电材料悬臂梁在电场或横向集中力作用下梁的宏观反映，给出了确定这些参数分布的公式，包括g31、S33的单参数识别及体积力与联合参数识别的方法。

The system parameters are determined by optimizing an output-error cost function. To deal with the non-uniqueness of the fully parameterized state-space system, a projected gradient search algorithm is presented by restricting the update of the parameters to the tangent space to the manifold of observationally equivalent state-space systems. The sufficient condition to employ L-M algorithm for optimizing parameters is also introduced. The proposed hierarchical optimization identificationmethod includes two steps: First, the parameter search direction is determined by the proposed adaptive L-M projected gradient approach; Second, the optimum step size is computed according to a line search method.

通过极小化输出误差目标函数获得了系统参数估计；提出了正交梯度搜索方法用于解决系统参数的非唯一性问题，正交梯度搜索的本质是在输入-输出等价类相切平面的正交垂空间更新系统参数；给出了用 L-M 算法进行参数优化的充分条件；提出的系统参数递阶优化辨识方法包括两步：首先用给出的自适应 L-M 算子正交梯度方法确定参数优化方向；其次由一维搜索方法计算最佳步长。

While these gradients could all be detected reasonably well,we found a slight shift in discriminability in favour of positive gradients and found that surfaces with no gradient at all were more likely to be judged to have a positive gradient.

让被试辨别表面质地密度变化的方向，结果发现被试能够很好地判别表面质地密度变化的方向，但在判别正向变化的表面时显得更准确；当表面密度没有变化时，被试倾向于判别为正向变化。

Due to its good effect in the reservation of information of signal abrupt change, mathematical morphology is often applied in the detection and location of short-term power quality disturbance, however, there is still a defect of invalid detection existing in partial detection methods based on mathematical morphology while some zero-crossing disturbances are detected. In this paper three mathematical morphology based disturbance detection and location methods, i.e., the method based on first-order derivation and morphological gradient, the method based on morphological gradient and soft threshold processing and the method based on dq decomposition and top-hat transform, are analyzed, that is, by means of simulation the adaptability of these methods in the analysis on the signals of voltage sag, voltage swell and electromagnetic transient oscillation is compared.

数学形态学因其在保留信号突变点信息方面有很好的效果，因此常用于短时电能质量扰动的检测和定位，但基于数学形态学的部分方法仍存在对某些过零点扰动检测失效的缺点，文章分析了3种基于数学形态学的扰动检测和定位方法，即基于1阶求导和形态梯度的方法、基于形态梯度和软阈值处理的方法、基于dq分解和高帽变换的方法，通过仿真比较了3种方法在分析电压暂降、电压暂升、电磁暂态振荡等信号方面的适应性，结果发现基于dq分解和高帽变换的方法在检测过零点扰动时具有很好的效果，因此选取这种方法对实测扰动数据进行了检测和定位分析。

Based on a Hopfield neural network mode for combinational circuit test generation, a test generation algorithm with global searching ability is proposed. This algorithm is the combination of chaotic searching with gradient algorithm. By means of the inherent stochastic and ergodic property of chaotic searching, the problem of being trapped in local minimum of gradient algorithm can be solved.

基于组合电路测试生成的离散Hopfield神经网络模型，将混沌搜索与Hopfield网络的梯度算法相结合，利用混沌搜索的内随机性及遍历性来克服梯度算法易于陷于局部极小的缺点，形成一种具有全局搜索能力的测试生成有效算法。

Relative positive temperature-gradient applicable for China is discussed, it proves that positive temperature-gradient can be expressed as exponential curve.

研究了我国公路桥梁混凝土箱梁的正温度梯度，证明其可以用指数函数来表达，并提出了本桥混凝土箱梁的正温度梯度指数函数表达式。

The expression of exponential curve is brought out to describe positive temperature-gradient of this bridge in this dissertation. Moreover, the relation of different factors to positive temperature-gradient is determined quantitatively.

根据计算研究结果，定量地确定了各影响因素与正温度梯度曲线的关系，证明了太阳辐射强度和日气温变化的幅值是影响混凝土箱梁正温度梯度的重要因素。

METHODS: HPMSCs were isolated from placenta of fetation human by density gradient centrifuge. Following bone marrow heparin anticoagulation, human BMSCs were isolated, purified and passaged by density gradient centrifuge.

采用密度梯度离心法从胎盘中分离、纯化和传代培养人胎盘源性间充质干细胞；骨髓肝素抗凝后，采用密度梯度离心法分离、纯化和传代培养人骨髓基质干细胞。

Bone marrow was obtained from healthy adult donors. METHODS: HPMSCs were isolated from placenta of fetation human by density gradient centrifuge. Following bone marrow heparin anticoagulation, human BMSCs were isolated, purified and passaged by density gradient centrifuge.

采用密度梯度离心法从胎盘中分离、纯化和传代培养人胎盘源性间充质干细胞；骨髓肝素抗凝后，采用密度梯度离心法分离、纯化和传代培养人骨髓基质干细胞。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。