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991.
本文讨论了从多目标优化非劣解中求最优解的各种方法及其不足,提出了用灰色关联度解决非劣解各序列间的形状差异问题,用模糊数学中海明距离和贴近度解决非劣解各序列间位置差异问题,然后加以合并,综合衡量两差异得到相似接近度概念,并用以确定最优解。 相似文献
992.
This study aims to correlate the response of pressure transient test to permeability distribution type. For this purpose, correlated permeability distributions in x–y direction are generated using fractional Brownian motion (fBm) as it has been shown in literature that permeability in carbonate reservoirs exhibits an fBm type distribution horizontally. 2-D fBm permeability distributions created using mid point displacement method are employed as data to a black oil simulator. The intermittence exponent, H or fractal dimension of the distribution, D, as defined by D=2 – H, characterizes the distribution type. All permeability distributions are normalized to represent the same arithmetic mean (20, 100, and 500 mD) and uniform variance so that only their fractal dimension that underlies the smoothness of the distribution distinguishes them. Many different realizations of permeability distributions are generated based on the random number seeds used and pressure transient (drawdown) tests are simulated using a black oil simulator package (ECLIPSE 100). Pressure transient analysis is performed using PanSystem package. As a base case and for the comparison purpose, the same procedure is repeated for the totally homogeneous case (the same permeability for all grids) and a random (normally distributed) permeability distribution with the same mean and uniform variance. The effects of permeability distribution type on the pressure response are clarified. A strong impact of heterogeneity is observed as an increase in skin effect with increasing fractal dimension of permeability distribution. This additional (or pseudo) skin effect due to heterogeneity is correlated to the fractal dimension of the permeability distribution. As a further step, the procedure is repeated for different flow rates applied during the drawdown test. The correlation between the fractal dimension of permeability distribution and additional skin is improved by incorporating the rate into it. The methodology followed can be used in the assessment of reservoir heterogeneity quantitatively using pressure transient response. 相似文献
993.
994.
把将MIMO控制系统中的动态结构耦合性分析方法应用于导航系统中,并以平台罗经和惯导系统初始对准方程为例,说明了本方法可以揭示输入、输出变量中的最佳配对关系,为导航系统解耦分析、简化参数设计提供了依据。 相似文献
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996.
997.
根据Floquet理论关于线性周期系数系统解的性质及稳定性条件 ,定义了衡量非线性非自治系统周期解受扰后的衰减速率指标—稳定度。从动力系统流的概念出发 ,给出了利用非线性非自治系统稳态周期解受扰后的瞬态响应信息计算周期解稳定度的方法。以不平衡滑动轴承 弹性转子系统为例 ,说明了该方法的有效性。将稳定度等于零作为临界判据 ,该方法不仅解决了工频周期解失稳边界的确定问题 ,而且解决了渐进稳定域的估计和抗冲击扰动裕度的计算问题 相似文献
998.
For the first time, the fractional order disturbance observer (FO-DOB) is proposed for vibration suppression applications such as hard disk drive servo control. It has been discovered in a recently published US patent application (US20010036026) that there is a tradeoff between phase margin loss and strength of the low frequency vibration suppression. Given the required cutoff frequency of the low pass filter, also known as the Q-filter, it turns out that the relative degree of the Q-filter is the major tuning knob for this tradeoff. The solution in US20010036026 was based on an integer order Q-filter with a variable relative degree. This actually motivated the use of a fractional order Q-filter. The fractional order disturbance observer is based on the fractional order Q-filter. The implementation issue is also discussed. The nice point of this paper is that the traditional DOB is extended to the fractional order DOB with the advantage that the FO-DOB design is now no longer conservative nor aggressive, i.e., given the cutoff frequency and the desired phase margin, we can uniquely determine the fractional order of the low pass filter. 相似文献
999.
为了研究配体能级与稀土离子最低激发态能级的匹配程度对所形成的稀土配合物荧光性能的影响,以邻氟苯甲酸(2-FBA)为第一配体,邻菲咯啉(phen)为第二配体分别制备两种稀土铽配合物Tb(2-FBA)_3·2H_2O和Tb(2-FBA)_3phen。元素分析和红外光谱表征了两种配合物的分子组成。相同浓度的紫外吸收光谱表明,Tb(2-FBA)_3phen的第二配体phen替代第一配体2-FBA吸收了部分紫外光。相同浓度的液体荧光光谱表明,Tb(2-FBA)_3·2H_2O的荧光发射强度高于Tb(2-FBA)_3phen的荧光发射强度。由于Tb(2-FBA)_3·2H_2O分子结晶水中的O—H振动会大大消耗配体所吸收的能量而使荧光强度大幅度下降;2-FBA配体在273 nm的吸收峰所对应的三重态能级必然与能级~5D_4的匹配程度会更差。在这种情况下Tb(2-FBA)_3·2H_2O的发射强度依然高于Tb(2-FBA)_3phen的发射强度,充分说明了第一配体2-FBA与Tb~3的最低激发态能级~5D_4的匹配程度要好于phen与Tb~(3+)的最低激发态能级~5D_4的匹配程度。通过结合紫外吸收光谱和荧光光谱对稀土配合物的配体能级的定性分析,可以初步了解不同类型配体对荧光性能的贡献程度。 相似文献
1000.
Fundamental matrix encapsulates all the geometric information in two views, and it plays an important role in many applications of three-dimensional computer vision. However, some configurations have an inherent ambiguity, namely, degeneracy, and no matter how many matched image points are used, the fundamental matrix could not be determined uniquely. It is well-known that degeneracies occur when all the space points and both the camera centers belong to a ruled quadric. But it is not so well-known how great the degenerate degrees in different configurations are. In this paper, we discuss the degeneracies caused by a quadric cone and give the corresponding degenerate degrees. We parameterize all the points on a quadric cone by a twisted cubic lying on the cone, and obtain a parametric coefficient matrix of the equations for estimating the fundamental matrix. By analyzing the coefficient matrix, we get the rank of it, i.e. the degenerate degree of the given configuration. It gives a more intuitive degeneracy and the degenerate degrees of the configurations, and reveals the full picture of the degeneracies on a cone. 相似文献