带理性运动极限的序列二次规划算法

序列二次规划(SQP)算法的基本思想是通过一系列的二次规划(QP)子问题来逐次逼近原问题.为了给定QP子问题一个更加合适的求解空间(超多面体),将理性运动极限应用于SQP算法,提出了一种带理性运动极限的序列二次规划算法,从而以较为理性的方式求解搜索方向,而且也有利于确定搜索步长,数值算例表明这一方法是可行且有效的。     

非线性最小二乘数值求解中Hesse矩阵的快速计算方法

非线性最小二乘数值求解过程中，残差函数非线性程度较高时，必须计算Hesse矩阵，而其工作量往往很大的。通常的作法是使用拟牛顿法，用一阶导数信息来逼近二阶导数，不仅不能获得准确的数值，而且计算繁琐。通过对Hesse矩阵结构的分析，采用符号运算求导，编译执行求值和向量化传递参数，达到了快速计算Hesse矩阵的目的．使对于大数据量直接使用牛顿法进行非线性最小二乘数值求解成为可能。数值试验的结果表明了该方法的可行性。     

油气储集层AVO非线性反演方法及应用研究

详细论述了AVO非线性反演方法的原理、反演中目标函数的构造以及海色矩阵的计算,获得了较精确的含气砂岩的泊松比值,直接检测了气层。应用实例表明,AVO非线性反演是一种求解精确解的方法,具有广阔的应用前景。     

改进的DFP神经网络学习算法

传统BP神经网络学习算法有学习速度慢、精度不高、易于陷入局部极小值、不稳定等问题,DFP神经网络学习算法是最优化理论中一类典型的拟牛顿法,具有超线性收敛速度和全局收敛性.但普通DFP算法有数值不稳定的缺陷,在处理大规模网络的学习问题时容易失效;在算法进入到饱和区域、接近最小值的时候,普通DFP算法会产生溢出错误.通过放大权值更新向量和权值导数更新向量,改进拟Hesse逆矩阵的求解,并结合线性搜索和L-M算法,改善了方法的稳定性,解决了算法失效的问题,同时保证了高效的学习速度和较高的学习精度.与目前应用最广泛的BP学习算法L-M 算法相比,改进的DFP算法具有与其相同的学习速度,计算量小,学习精度高,更适用于大残量问题.     

Geothermal resources in the shallow, unsaturated zone of the Wiesbaden spa district, Germany

The geothermal energy potential of the Wiesbaden spa district continues to be largely untapped. Although the thermal water is being utilized, any other activity liable to disturb the hydraulic regime of the thermal springs is prohibited. The geothermal potential of the unsaturated zone in the spa district has been mapped, although the zone must be regarded as a thermal insulator rather than a good conductor. The results of the mapping revealed the presence of a number of heat anomalies that could be exploited in the future; further economic benefits could be gained from installing the heat transfer units during road works. The modelling studies considered two possible scenarios: direct heating and heat pump usage. The results indicate that heat pumps are the more efficient option, yielding a thermal capacity of approximately 100 W/m².     

On the relationship of NDVI with leaf area index in a deciduous forest site

Numerous studies have reported on the relationship between the normalized difference vegetation index (NDVI) and leaf area index (LAI), but the seasonal and annual variability of this relationship has been less explored. This paper reports a study of the NDVI-LAI relationship through the years from 1996 to 2001 at a deciduous forest site. Six years of LAI patterns from the forest were estimated using a radiative transfer model with input of above and below canopy measurements of global radiation, while NDVI data sets were retrieved from composite NDVI time series of various remote sensing sources, namely NOAA Advanced Very High Resolution Radiometer (AVHRR; 1996, 1997, 1998 and 2000), SPOT VEGETATION (1998-2001), and Terra MODIS (2001). Composite NDVI was first used to remove the residual noise based on an adjusted Fourier transform and to obtain the NDVI time-series for each day during each year.The results suggest that the NDVI-LAI relationship can vary both seasonally and inter-annually in tune with the variations in phenological development of the trees and in response to temporal variations of environmental conditions. Strong linear relationships are obtained during the leaf production and leaf senescence periods for all years, but the relationship is poor during periods of maximum LAI, apparently due to the saturation of NDVI at high values of LAI. The NDVI-LAI relationship was found to be poor (R² varied from 0.39 to 0.46 for different sources of NDVI) when all the data were pooled across the years, apparently due to different leaf area development patterns in the different years. The relationship is also affected by background NDVI, but this could be minimized by applying relative NDVI.Comparisons between AVHRR and VEGETATION NDVI revealed that these two had good linear relationships (R²=0.74 for 1998 and 0.63 for 2000). However, VEGETATION NDVI data series had some unreasonably high values during beginning and end of each year period, which must be discarded before adjusted Fourier transform processing. MODIS NDVI had values greater than 0.62 through the entire year in 2001, however, MODIS NDVI still showed an “M-shaped” pattern as observed for VEGETATION NDVI in 2001. MODIS enhanced vegetation index (EVI) was the only index that exhibited a poor linear relationship with LAI during the leaf senescence period in year 2001. The results suggest that a relationship established between the LAI and NDVI in a particular year may not be applicable in other years, so attention must be paid to the temporal scale when applying NDVI-LAI relationships.     

一种基于高斯-牛顿法的光电经纬仪交会测量算法

针对靶场光电测量中使用的双站交会方法需要切换交会公式、交会精度不高的问题,提出了一种在直角发射坐标系中,基于高斯-牛顿法的多站交会方法。通过仿真试验将其与传统双站交会方法进行比较,证明了这种多站交会方法具有良好的收敛性和较高的交会精度。     

STABILITY REGION GRADIENTS

The stability region improvement for nonlinear dynamic systems based on the Lyapunov method is addressed. Emphasis is put on gradients for increasing the radial distance of the point on the stability boundary closest to the origin. Arbitrary analytic complexity in a given structure is admissible for the dynamic system, an additive controller, and the Lyapunov function.     

多维优化问题的一个自适应两点步长算法

给出了克服牛顿算法缺陷的自适应两点步长的算法。利用拟牛顿性质得到包含前两个迭代点有关信息的迭代步长因子解析表达式，无论初始迭代点与最优解之间是否存在Hesse矩阵不正定点、鞍点和广义拐点，迭代点列自动快速逼近最优解，该算法具有自适应性且仍具有二阶收敛速度；证明了算法的收敛性，并给出了算例，利用Mathematics数学软件验证了算法的有效性。     

基于高斯曲面拟合的影像渐晕复原方法

 本文根据影像发生渐晕时灰度分布的特点,提出了一种基于最速下降法的高斯曲面拟合方法,推导了Hesse矩阵的相关参数,较好地解决了不规则高斯曲面拟合的问题,获得了影像整体灰度变化情况,从而实现了影像渐晕现象的复原.仿真结果表明,上述方法能够有效估计出不规则高斯曲面(如渐晕图像灰度值)的相关参数.通过对实际影像的处理结果表明,本文方法能够有效去除影像的渐晕现象,改善图像质量.由于该方法不需要相关的光学和几何参数,因此具有广泛的适用性.