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991.
Jan G. Wesseling Coen J. Ritsema Jannes Stolte Klaas Oostindie Louis W. Dekker 《Transport in Porous Media》2008,71(3):289-309
The Mualem-Van Genuchten equations have become very popular in recent decades. Problems were encountered fitting the equations’
parameters through sets of data measured in the laboratory: parameters were found which yielded results that were not monotonic
increasing or decreasing. Due to the interaction between the soil moisture retention and the hydraulic conductivity relationship,
some data sets yield a fit that seems not to be optimal. So the search for alternatives started. We ended with the cubical
spline approximation of the soil physical characteristics. Software was developed to fit the spline-based curves to sets of
measured data. Five different objective functions are tested and their results are compared for four different data sets.
It is shown that the well-known least-square approximation does not always perform best. The distance between the measured
points and the fitted curve, as can be evaluated numerically in a simple way, appears to yield good fits when applied as a
criterion in the optimization procedure. Despite an increase in computational effort, this method is recommended over the
least square method. 相似文献
992.
M. Giulietti J.W.P. Hirschfeld G. Korchmros F. Torres 《Finite Fields and Their Applications》2006,12(4):539-564
A family of maximal curves is investigated that are all quotients of the Hermitian curve. These curves provide examples of curves with the same genus, the same automorphism group and the same Weierstrass semigroup at a generic point, but that are not isomorphic. 相似文献
993.
在研究了椭圆曲线y2≡x3+ax+b(modp)上的点的一些性质后,提出了基的计算、验证、选择等算法,同时研究了基的选择、点积效率、安全性三者之间的关系.最后实现了以椭圆曲线基的选择. 相似文献
994.
995.
We present a detailed analysis of the dependences of the absorption contours and concentration curves on various parameters
in atomic absorption spectrometry with a continuous radiation source. We have developed a multifunctional application software
package allowing us to calculate the emission and absorption line profiles for different elements under different physical
conditions. We take into account Doppler and collisional broadening of the absorption lines, which have a complex structure
as a result of the isotopic shift, hyperfine splitting of the components, and also instrumental distortion of these lines.
We consider two different procedures for calculating the absorbance and do a comparative analysis of the two procedures. For
all the listed cases, we can plot concentration curves and find the absorbance within the classical definition and plot the
concentration curve using only a portion of the spectral width of the profile rather than the entire width.
We have modeled the instrumental distortions of the spectral profile due to spectral selection, and we have analyzed their
effect on the shape of the absorption contour.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 285–289, May–June, 2006. 相似文献
996.
Thermodynamic data are suitable subject for investigating strategies and concepts for the evaluation of complete measurement uncertainty budgets in situations where the measurand cannot be expressed in a mathematical formula. Some suitable approaches are the various forms of Monte Carlo simulations in combination with computer-intensive statistical methods that are directed to an evaluation of empirical distribution curves for the uncertainty budget. Basis of the analysis is a cause-and-effect diagram. Some experience is available with cause-and-effect analysis of thermodynamic data derived from spectrophotometric data. Another important technique for the evaluation of thermodynamic data is glass-electrode potentiometry. On basis of a newly derived cause-and-effect diagram, a complete measurement uncertainty budget for the determination of the acidity constants of phosphoric acid by glass-electrode potentiometry is derived. A combination of Monte Carlo and bootstrap methods is applied in conjunction with the commercially available code SUPERQUAD. The results suggest that glass-electrode potentiometry may achieve a high within-laboratory precision because major uncertainty contributions become evident via interlaboratory comparisons. This finding is further underscored by analysing available literature data. 相似文献
997.
提出一种求解无约束优化问题的非单调多步曲线搜索方法.此方法具有如下特点:(1)算法在产生下一个迭代点时不仅利用了当前迭代点的信息,而且还可能利用前m个迭代点的信息.这就是多步法;(2)下降方向和步长同时确定,而不是先找到方向,再由线性搜索寻找步长.这就是曲线搜索技术;(3)采用非单调搜索技巧.在较弱的条件下,我们证明了此方法的收敛性. 相似文献
998.
N.P. Smart 《Discrete Applied Mathematics》2007,155(4):538-547
In this paper, we examine the hard problems underlying asymmetric pairings, their precise relationships and how they affect a number of existing protocols. Furthermore, we present a new model for the elliptic curve groups used in asymmetric pairings, which allows both an efficient pairing and an efficiently computable isomorphism. 相似文献
999.
Tadashi Sugiyama 《Geometriae Dedicata》2007,125(1):53-61
In this paper, we characterize of totally geodesic Kähler immersions by extrinsic shapes of some curves having points of order 2. 相似文献
1000.
In the context of scattering of light, we determine the extent of randomness within which a hidden periodic part can still
be detected. The detection is carried out using a technique called the extended matched filtering, first introduced by us
in this context. The earlier prediction, before our technique was introduced, had placed the limit of detection, by intensity
measurements alone, at (r
0/Λ) ∼ 0.33, where r0 is the coherence length of light for scattering by the rough part of the surface and Λ is the wavelength of the periodic
part of the surface. In our earlier works we have shown that by intensity measurements alone, the limit of detection can be
taken to a much lower value of (r
0/Λ), when the extended matched filtering method is employed. In this paper we follow the extended matched filtering method,
and try to reach the lowest possible value of detection in (r
0/Λ) by fitting the data to a polynomial. It is concluded by our numerical work that the lowest possible limit for detection
from intensity measurements alone is (r
0/Λ) = 0.11. 相似文献