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281.
本文研究n阶非线性过值问题(NB)的奇异摄动。在较一般的条件下,应用高阶微分不等式理论证明了摄动解的存在性,并给出了摄动解直到n阶导函数的一致有效渐近展开式,推广和改进了已有的结果。 相似文献
282.
Experimental investigations of the phenomena occurring when low density electron and plasma beams are injected into a nonadiabatic
magnetic mirror are presented. Effects of nonadiabaticity and mirror ratio on the reflectivity of the magnetic mirror are
measured. Transition of the mirror from adiabatic to strongly nonadiabatic results in setting up of a potential barrier which
enhances the reflectivity. 相似文献
283.
R. G. Stoneham 《BIT Numerical Mathematics》1970,10(4):481-500
In the computing literature, there are few detailed analytical studies of the global statistical characteristics of a class of multiplicative pseudo-random number generators.We comment briefly on normal numbers and study analytically the approximately uniform discrete distribution or (j,)-normality in the sense of Besicovitch for complete periods of fractional parts {x
0
1
i
/p} on [0, 1] fori=0, 1,..., (p–1)p–1–1, i.e. in current terminology, generators given byx
n+1
1
x
n mod p wheren=0, 1,..., (p–1)p
–1–1,p is any odd prime, (x
0,p)=1,
1 is a primitive root modp
2, and 1 is any positive integer.We derive the expectationsE(X, ),E(X
2, ),E(X
nXn+k); the varianceV(X, ), and the serial correlation coefficient k. By means of Dedekind sums and some results of H. Rademacher, we investigate the asymptotic properties of k for various lagsk and integers 1 and give numerical illustrations. For the frequently used case =1, we find comparable results to estimates of Coveyou and Jansson as well as a mathematical demonstration of a so-called rule of thumb related to the choice of
1 for small k.Due to the number of parameters in this class of generators, it may be possible to obtain increased control over the statistical behavior of these pseudo-random sequences both analytically as well as computationally. 相似文献
284.
Let FX,Y(x,y) be a bivariate distribution function and Pn(x), Qm(y), n, m = 0, 1, 2,…, the orthonormal polynomials of the two marginal distributions FX(x) and FY(y), respectively. Some necessary conditions are derived for the co-efficients cn, n = 0, 1, 2,…, if the conditional expectation E[Pn(X) ∥ Y] = cnQn(Y) holds for n = 0, 1, 2,…. Several examples are given to show the application of these necessary conditions. 相似文献
285.
The method of molecular dynamics is applied to investigate the stability of water clusters containing up to 90 molecules. With increasing size of aggregates, (H2O)n≥10 10, their thermal stability strengthens. Mechanical stability of great clusters keeps the quickly reached level, and the coefficient of dielectric stability passes through the maximum at n = 50. 相似文献
286.
Swetlana G. Shevchenko Yulii L. Frolov Alekcei V. Abramov Mikhail G. Voronkov 《Journal of organometallic chemistry》2005,690(12):2922-2933
The characteristics of (benzoyloxymethyl)trifluorosilane C6H5C(O)OCH2SiF3 containing a five-membered heterocycle closed by intramolecular coordination O → Si bond (Ia) and its most stable acyclic isomer (Ib) have been calculated by HF, MP2(Full) non-empirical methods, and DFT(B3LYP) using 6-311G(d) and 6-311 + G(2d,p) basis sets. The (C8H18, C6H6, (C4H9)2O, CHCl3, (CH2)4O, CH2Cl2, CH3CN) medium effect on the energy and structural characteristics, dipole moments, and vibrational spectra of Ia and Ib isomers was calculated by the DFT(B3LYP)/6-311 + G(2d,p) method in the Onsager SCRF model approximation. The DFT(B3LYP)/6-311 + G(2d,p) calculation reasonably reproduces the medium effect on coordination energy, geometry, dipole moments, and band frequencies in the vibrational spectrum of Ia. 相似文献
287.
288.
Summary Let <InlineEquation ID=IE"1"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"2"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"3"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"4"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"5"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"6"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"7"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"8"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"9"><EquationSource Format="TEX"><![CDATA[$]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>{\cal
{X}}_{n} =(X_1,\ldots,X_n)$ be a random vector. Suppose that the random variables $(X_i)_{1\leq i\leq n}$ are stationary and
fulfill a suitable dependence criterion. Let $f$ be a real valued function defined on $\mathbbm{R}^n$ having some regular
properties. Let ${\cal {Y}}_{n}$ be a random vector, independent of ${\cal {X}}_{n}$, having independent and identically distributed
components. We control $\left|\mathbbm{E}(f({\cal {X}}_{n}))-\mathbbm{E} (f({\cal {Y}}_{n}))\right|$. Suitable choices of
the function $f$ yield, under minimal conditions, to rates of convergence in the central limit theorem, to some moment inequalities
or to bounds useful for Poisson approximation. The proofs are derived from multivariate extensions of Taylor's formula and
of the Lindeberg decomposition. In the univariate case and in the mixing setting the method is due to Rio (1995). 相似文献
289.
The anomalous magnetic moment of muon is calculated in anSU(3)×U(1) gauge model proposed by Gupta and Mani. We find the contribution due to the intermediate gauge bosons to be of the same
order of magnitude as in Weinberg. Salam model. The deep-inelastic structure functions are also analysed in the same model
and inequalities for the structure functions are obtained in the light-cone algebra approach. 相似文献
290.
A comparative study of seven discretization schemes for the equations describing convection-diffusion transport phenomena is presented. The (differencing) schemes considered are the conventional central- and upwind-difference schemes, together with the Leonard,1 Leonard upwind1 and Leonard super upwind difference1 schemes. Also tested are the so called locally exact difference scheme2 and the quadratic-upstream difference scheme.3,4 In multidimensional problems errors arise from ‘false-diffusion’ and function approximations. It is asserted that false diffusion is essentially a multidimensional source of error. No mesh constraints are associated with errors in function approximation and discretization. Hence errors associated with discretization only may be investigated via one-dimensional problems. Thus, although the above schemes have been tested for one- and two-dimensional flows with sources, only the former are presented here. For 1D flows, the Leonard super upwind difference scheme and the locally exact scheme are shown to be far superior in accuracy to the others at all Peclet numbers and for most source distributions, for the test cases considered. Furthermore, the latter is shown to be considerably cheaper in computational terms than the former. The stability of the schemes and their CPU time requirements are also discussed. 相似文献