共查询到20条相似文献,搜索用时 46 毫秒
1.
Scott W. Weeks Graham C. Sander Ian G. Lisle Jean-Yves Parlange 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1994,45(6):841-853
When both the diffusivityD and fractional flow functionf have a power law dependence on the water content , i.e.D=D
o andf=+1, the nonlinear transport equation for radially symmetric two phase flow can, in certain circumstances, be reduced to a weakly coupled system of two first order nonlinear ordinary differential equations. Numerical solutions of these equations for a constant flux boundary conditionV
wo and comparison with experimental data are given. In particular, when the fluxV
wo and a are related byV
wo( + 1)/D
o=2, a new fully explicit analytical solution is found as (r, t)=(1 – r
2/4D
ot)1/ forr
2 < 4D
ot/ and (r, t)=0 forr
2 4D
ot/ We show that the existence of this exact soution is due to the presence of a Lagrangian symmetry. 相似文献
2.
Manabu Iwasa 《Annals of the Institute of Statistical Mathematics》1991,43(4):657-665
This paper discusses -admissiblility and d-admissiblity which are important concepts in studying the performance of statistical tests for composite hypotheses. A sufficient condition for -admissibility is presented. When =1/m, the Nomakuchi-Sakata test, which is uniformly more powerful than the likelihood ratio test for hypotheses min (1, 1) = 0 versus min (1, 1) > 0, is generalized for a class of distributions in an exponential family, and its unbiasedness and -admissibility are shown. Finally, the case of 1/m is discussed in brief. 相似文献
3.
G. S. Karkarashvili 《Journal of Mathematical Sciences》1993,66(3):2236-2242
We consider numerical solution of an integro-differential equation with nonsmooth initspaial values. Unique solvability in Sobolev spaceW
2
(0, 1), =1,2, is proved. We establish the rate of convergence of the approximate solution to the exact solution in fractional spacesW
2
+1
, 01, with approximation order O(h
++1/2
) for 01/2 andO(h
+1
|ln h|1/2, for 1/2 #x2264;1.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 64, pp. 8–16, 1988. 相似文献
4.
A. B. Aleksandrov 《Journal of Mathematical Sciences》1993,63(2):115-129
Let be an inner function, let C, ¦¦=1. Then the harmonic function [(+)]/(–)] is the Poisson integral of a singular measure
D. N. Clark's known theorem enables us to identify in a natural manner the space H2 H2 with the space L2
(
).Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 170, pp. 7–33, 1989. 相似文献
5.
In-Suk Wee 《Probability Theory and Related Fields》1990,85(4):469-488
Summary Let {X
t
} be a 1 process with stationary independent increments and its Lévy measurev be given byv{yy>x}=x
–L
1
(x), v{yy<–x}=x
–L
2
(x) whereL
1,L
2 are slowly varying at 0 and and 0<1. We construct two types of a nondecreasing functionh(t) depending on 0<<1 or =1 such that lim inf
a.s. ast 0 andt for some positive finite constantC.This research is partialy supported by a grant from Korea University 相似文献
6.
Summary We prove the following theorem: «Given 0<1, the (C, )-means of a sequence of i.i.d. random variables X
n converge a.s. iff E|X
n|1/<.» For 1/2<1 and 0<<1/2 this result is essentially known. We give here a proof of the case =1/2; an important tool is a theorem of Hsu and Robbins [5]. 相似文献
7.
Julien Barral 《Journal of Theoretical Probability》2000,13(4):1027-1060
Until now [see Kahane;(19) Holley and Waymire;(16) Falconer;(14) Olsen;(29) Molchan;(28) Arbeiter and Patzschke;(1) and Barral(3)] one determines the multifractal spectrum of a statistically self-similar positive measure of the type introduced, in particular by Mandelbrot,(26, 27) only in the following way: let be such a measure, for example on the boundary of a c-ary tree equipped with the standard ultrametric distance; for 0, denote by E
the set of the points where possesses a local Hölder exponent equal to , and dim E
the Hausdorff dimension of E
; then, there exists a deterministic open interval I
*+ and a function f: I
*+ such that for all in I, with probability one, dim E
=f(). This statement is not completely satisfactory. Indeed, the main result in this paper is: with probability one, for all I, dim E
=f(). This holds also for a new type of statistically self-similar measures deduced from a result recently obtained by Liu.(22) We also study another problem left open in the previous works on the subject: if =inf(I) or =sup(I), one does not know whether E
is empty or not. Under suitable assumptions, we show that E
ø and calculate dim E
. 相似文献
8.
G. I. Gusev 《Mathematical Notes》1973,14(3):817-822
Let F(x1,..., xm) (m1) be a polynomial with integral p-adic coefficients, and let N, be the number of solutions of the congruence F(x1,..., Xm)=0 mod A proof is given that the Poincaré series (t) =
0
N
t
is rational for a class of isometrically-equivalent polynomials of m variables (m2) containing a form of degree n2 of two variables.Translated from Matematicheskie Zametki, Vol. 14, No. 3, pp. 453–463, September, 1973.The author wishes to thank N. G. Chudakov for discussing this paper and for his helpful advice. 相似文献
9.
Augustin Banyaga 《Annals of Global Analysis and Geometry》1996,14(4):427-441
We exhibit new invariants of the contact structure E(), the contact flow F
and the transverse symplectic geometry of a contact manifold (M, ). The invariant of contact structures generalizes to transversally oriented foliations. We focus on the particular cases of orientations of smooth manifolds and transverse orientations of foliations. We define the transverse Calabi invariants and determine their kernels.Supported in part by NSF grants DMS 90-01861 and DMS 94-03196. 相似文献
10.
For a cardinal , we say that a subset B of a space X is C
-compact in X if for every continuous function
is a compact subset of
. If B is a C-compact subset of a space X, then (B, X) denotes the degree of C
-compactness of B in X. A space X is called -pseudocompact if X is C
-compact into itself. For each cardinal , we give an example of an -pseudocompact space X such that X × X is not pseudocompact: this answers a question posed by T. Retta in Some cardinal generalizations of pseudocompactness Czechoslovak Math. J. 43 (1993), 385–390. The boundedness of the product of two bounded subsets is studied in some particular cases. A version of the classical Glicksberg's Theorem on the pseudocompactness of the product of two spaces is given in the context of boundedness. This theorem is applied to several particular cases. 相似文献
11.
D. J. Daley 《Probability Theory and Related Fields》1977,41(2):139-143
Summary For a non-negative random variable X and 1 such that EX<, E(X-Y)
+
/{E(X-y)
+}+ is monotonic-decreasing in y, and hence no smaller than EX
. Inequalities for E(X-Y)
+
E(, 1, y, z0) are also given. This relation enables an inequality of Kingman for the mean waiting time in a stationary GI/G/1 queue to be sharpened.Work done as Visiting Fellow, Department of Statistics, University of Melbourne 相似文献
12.
Horst Elmar Winkelnkemper 《Annals of Global Analysis and Geometry》1992,10(3):209-218
Let
t
be the flow (parametrized with respect to arc length) of a smooth unit vector field v on a closed Riemannian manifold M
n
, whose orbits are geodesics. Then the (n-1)-plane field normal to v, v, is invariant under d
t
and, for each x M, we define a smooth real function
x
(t) : (1 +
i
(t)), where the i(t) are the eigenvalues of AA
T, A being the matrix (with respect to orthonormal bases) of the non-singular linear map d2t
, restricted to v at the point x
-t M
n.Among other things, we prove the
Theorem (Theorem II, below). Assume v is also volume preserving and that
x
'
(t) 0 for all x M and real t; then, if
x
t
: M M is weakly missng for some t, it is necessary that vx 0 at all x M. 相似文献
13.
Kevin E. Osondu 《Semigroup Forum》1979,17(1):139-152
Let S be a cancellative semigroup which is a semilattice of left reversible semigroups S, . This article studies the relationship between the group of quotients G of S and the groups of quotients G of S, . It is shown that G is the maximum group homomorphic image of an inverse semigroup which is a semilattice of groups G (up to isomorphism).The technique used here which involves the use of Ore's quotients also applies to the study of the maximum group homomorphic image of a semigroup which is a semilattice of inverse semigroups. 相似文献
14.
Joanna Janczewska 《Geometriae Dedicata》2002,91(1):7-21
The aim of this paper is to illustrate the use of topological degree for the study of bifurcation in von Kármán equations with two real positive parameters and for a thin elastic disk lying on the elastic base under the action of a compressing force, which may be written in the form of an operator equation F(x, , ) = 0 in some real Banach spaces X and Y. The bifurcation problem that we study is a mathematical model for a certain physical phenomenon and it is very important in the mechanics of elastic constructions. We reduce the bifurcation problem in the solution set of equation F(x, , ) = 0 at a point (0, 0, 0) X × IR
+
2 to the bifurcation problem in the solution set of a certain equation in IR
n
at a point (0, 0, 0) IR
n
× IR
+
2, where n = dim Ker F
x
(0, 0, 0) and F
x
(0, 0, 0): X Y is a Fréchet derivative of F with respect to x at (0, 0, 0). To solve the bifurcation problem obtained as a result of reduction, we apply homotopy and degree theory. 相似文献
15.
K. Väänänen 《Monatshefte für Mathematik》1989,108(2-3):219-227
We shall give a further application of Hermite-Mahler polynomials to the consideration ofp-adic exponential function. An effective lower bound is obtained for max {| – |
p
,P(e
)|
p
}, where is an algebraic number satisfying ||
p
<p
–/(p–1), and 0 is ap-adic number with | |
p
depending on the degree of the polynomialPZ[y]. The bound obtained implies the transcendence ofe
if ap-adic number satisfying 0 < ||
p
<p
–/(p–1) is algebraic or can be well approximated by algebraic numbers.This work was carried out while the author was a research fellow of the Alexander von Humboldt Foundation. 相似文献
16.
M. B. Nathanson 《Acta Mathematica Hungarica》2000,87(3):179-195
Let A be a set of positive integers with gcd (A) = 1, and let p
A
(n) be the partition function of A. Let c
0 = 2/3. If A has lower asymptotic density and upper asymptotic density , then lim inf log p
A
(n)/c
0 n and lim sup log p
A
(n)/c
0 n . In particular, if A has asymptotic density > 0, then log p
A
(n) c0n. Conversely, if > 0 and log p
A
(n) c
0 n, then the set A has asymptotic density . 相似文献
17.
A. G. Pinus 《Mathematical Notes》1972,11(1):54-57
It is shown that if a linearly ordered set B does not contain as subsets sets of order type
and
*
then B can be embedded in 2
. We construct an example of a set satisfying the above conditions which cannot be embedded in any 2
if <
. Simultaneously we show that for any ordinal, 2
+1
cannot be embedded in 2
and that there exists at least
+1
distinct dense order types of cardinality 2
.Translated from Matematicheskie Zametki, Vol. 11, No. 1, pp. 83–88, January, 1972.In conclusion, I wish to take the opportunity to thank Yu. L. Ershov for kindness and assistance in this work. 相似文献
18.
Let P be a probability distribution on a separable metric space (S,d). We study the following problem of approximation of a distribution P by a set from a given class A2
S
: W(A,P)
S
(d(x,A))P(dx)min
AA
, where is a nondecreasing function. A special case where A is a parametric class A={A():T} is considered in detail. Our main interest is to obtain convergence results for sequences {A
*
n
}, where A
*
n
is an optimal set for a measure P
n
satisfying P
n
P, as n. 相似文献
19.
On problems with bounded state variables 总被引:1,自引:0,他引:1
I. Bert Russak 《Journal of Optimization Theory and Applications》1970,5(2):114-157
A set of first-order necessary conditions is obtained for the general control problem of Bolza with bounded state constraints of the form
(t, x)0, =1,...,m. With the solution required to satisfy the vector differential equationsx=f(t, x, u), whereu is control, an important feature of this paper is in relaxing the assumption on the rank of the matrix
x
f
u generally made in attacking problems of this type. This is accomplished even though the solution may have an infinite number of intervals satisfying
(t, x)=0 for various .The preparation of this paper was sponsored in part by the US Army Research Office, Grant No. DA-31-214-ARO(D)-355. 相似文献
20.
The variational inequality problem (VIP) can be reformulated as an unconstrained minimization problem through the generalized D-gap function. Recently, a hybrid Newton-type method was proposed by Peng and Fukushima for minimizing a special form of the generalized D-gap function. In this paper, the hybrid Newton-type algorithm is extended to minimize the general form g
of the generalized D-gap function. It is shown that the algorithm has nice convergence properties. Under some reasonable conditions, it is proved that the algorithm is locally and globally convergent. Moreover, it is proved that the function g
has bounded level sets for strongly monotone VIP. An error bound of the algorithm is obtained. 相似文献