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排序方式: 共有363条查询结果,搜索用时 31 毫秒
201.
Xia Wang 《Journal of Computational and Applied Mathematics》2010,234(5):1611-4927
In this paper, three new families of eighth-order iterative methods for solving simple roots of nonlinear equations are developed by using weight function methods. Per iteration these iterative methods require three evaluations of the function and one evaluation of the first derivative. This implies that the efficiency index of the developed methods is 1.682, which is optimal according to Kung and Traub’s conjecture [7] for four function evaluations per iteration. Notice that Bi et al.’s method in [2] and [3] are special cases of the developed families of methods. In this study, several new examples of eighth-order methods with efficiency index 1.682 are provided after the development of each family of methods. Numerical comparisons are made with several other existing methods to show the performance of the presented methods. 相似文献
202.
In this paper, we present simulation results for Reed-Muller (RM) turbo codes over AWGN and Rayleigh fading channels. We also compare the simulation results of turbo product codes and block turbo codes with RM component codes over an AWGN channel. We show that minimum distance is not important as far as the BER performance of long codes is concerned. The weight distribution of RM codes of different lengths and turbo product codes with first-order RM component codes are obtained and analyzed for their good performance. We show that the weight distribution asymptotically approaches that of random coding as the code length increases. 相似文献
203.
Bicheng Yang 《Journal of Mathematical Analysis and Applications》2002,272(1):187-199
In this paper, by introducing three parameters A, B, and λ, and estimating the weight coefficient, we give a generalization of the extended Hardy-Hilbert's inequality with a best possible constant factor, involving the β function. We also consider its equivalent inequality and the associated double series form. 相似文献
204.
Finite Projective Geometries and Classification of the Weight Hierarchies of Codes (Ⅰ) 总被引:1,自引:0,他引:1
WenDeCHEN TorleivKLφVE 《数学学报(英文版)》2004,20(2):333-348
The weight hierarchy of a binary linear [n,κ] code C is the sequence (d1,d2,...,dκ), where dr is the smallest support of an r-dimensional subcode of C. The codes of dimension 4 are collected in classes and the possible weight hierarchies in each class is determined by finite projective geometries.The possible weight hierarchies in class A, B, C, D are determined in Part (Ⅰ). The possible weight hierarchies in class E, F, G, H, I are determined in Part (Ⅱ). 相似文献
205.
Let 0<α<1 and , x?0. A factorization theorem is given, which provides a weight characterization of the space of all positive functions f such that Tαf belongs to Lpw, 1<p<∞, w a weight function. This theorem yields a two-sided estimate for the norm of Tαf. An analogous result holds for α=0. In the latter case, it is also shown that the averaging Hardy operator T0 and its dual are comparable in Lpw, 1<p<∞, if w belongs to the Muckenhoupt weight class Ap. 相似文献
206.
《Arabian Journal of Chemistry》2021,14(12):103423
BackgroundThe environmental and economic benefits have been the driving force in search of efficient corrosion inhibitors for iron/steel used in industrial acidic medium. This study reports on berberine isolated from methanol extract of high-altitude (1347 m) shrub Mahonia nepalensis as a highly efficient and thermally stable corrosion inhibitor for mild steel (MS) in 1.0 M H2SO4 simulating acid pickling condition.MethodsThe weight-loss and electrochemical methods revealed the fast adsorption of berberine.Significant Findings: It achieved above 91% inhibition efficiency (IE) in 0.25 h and reached 94% in 6 h for 1000 ppm berberine. The IE increased with concentration and temperature, giving an IE of 97.2% at 328 K, which makes it a promising candidate for industrial application. It behaved as a mixed type of inhibitor as revealed by open circuit potential and polarization curves. The results indicated suppression of the corrosion by effectively forming an adsorbed berberine layer on the MS surface. Adsorption of the berberine followed a Langmuir adsorption isotherm. The thermodynamic parameters such as activation energy (43.19 kJ/mol), free energy (−35.05 kJ/mol), enthalpy (40.55 kJ/mol), and entropy (−97.83 J/molK) of adsorption supported both physical and chemical interactions of berberine with MS surface. The obtained results also revealed that the adsorption process was endothermic and spontaneous in nature. 相似文献
207.
Ana Portilla Yamilet Quintana Eva Tourís 《Journal of Mathematical Analysis and Applications》2007,334(2):1167-1198
We characterize the set of functions which can be approximated by continuous functions with the norm ‖f‖L∞(w) for every weight w. This fact allows to determine the closure of the space of polynomials in L∞(w) for every weight w with compact support. We characterize as well the set of functions which can be approximated by smooth functions with the norm
‖f‖W1,∞(w0,w1):=‖f‖L∞(w0)+‖f′‖L∞(w1), 相似文献
208.
较为精密的Hardy-Hilbert等式的一个加强 总被引:12,自引:2,他引:10
本文证明了如下权系数的不等式:这里,(C为Euler常数).从而建立了一个加强的Hardy-Hilbert不等式,并建立了一个新的Hardy-Hilbert类不等式及其加强式. 相似文献
209.
扩充的Hermite-Fejér插值算子平均收敛性 总被引:3,自引:0,他引:3
讨论了以Jacobi正交多项式零点为插值结点的扩充Hermite-Fejer插值算子在Lpu空间的平均收敛性。首先给出了算子加权平均收敛的条件,进一步得到了收敛阶。 相似文献
210.