共查询到20条相似文献,搜索用时 46 毫秒
1.
S. S. P. Shen 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1991,42(1):122-138
Critical long surface waves forced by locally distributed external pressure applied on the free surface in channels of arbitrary cross section are studied in this paper. The fluid under consideration is inviscid and has constant density. The upstream flow is uniform and the upstream velocity is assumed to be near critical, i.e.,u
0=u
c
++0(2), where 0<1 andu
c
is the critical velocity determined by the geometry of the channel. The external pressure applied on the free surface as the forcing is
2
P(x). Then the first order perturbation of the free surface elevation satisfies a forced Korteweg-de Vries equation (fK-dV). It is shown in this paper that: (i) If
(supercritical), the stationaryfK-dV has two cusped solitary wave solutions; (ii) if
(subcritical), the stationaryfK-dV has a downstream cnoidal wave solution; (iii) when=
L
, the unique stationary solution of thefK-dV is a wave free hydraulic fall; (iv) if=
d
=–
L
, thefK-dV has a jump solution; and (v) if
L
<<
c
, thefK-dV does not have stationary solutions. Some free surface profiles and bifurcation diagrams are presented. 相似文献
2.
Sharad Sane 《Designs, Codes and Cryptography》2001,23(3):291-296
A proof of the following conjecture of Jungnickel and Tonchev on quasi-multiple quasi-symmetric designs is given: Let D be a design whose parameter set (v,b,r,k,) equals (v,sv,sk,k, s) for some positive integer s and for some integers v,k, that satisfy (v-1) = k(k-1) (that is, these integers satisfy the parametric feasibility conditions for a symmetric (v,k,)-design). Further assume that D is a quasi-symmetric design, that is D has at most two block intersection numbers. If (k, (s-1)) = 1, then the only way D can be constructed is by taking multiple copies of a symmetric (v,k, )-design. 相似文献
3.
For the general fixed effects linear model:Y=X+, N(0,V),V0, we obtain the necessary and sufficient conditions forLY+a to be admissible for a linear estimable functionS in the class of all estimators under the loss function (d -S)D(d -S), whereD0 is known. For the general random effects linear model:
=XV
11
X+XV
12+V
21
X+V
220, we also get the necessary and sufficient conditions forLY+a to be admissible for a linear estimable functionS+Q in the class of all estimators under the loss function (d -S -Q)D(d -S -Q), whereD0 is known. 相似文献
4.
Andrea Del Centina 《Annali di Matematica Pura ed Applicata》1985,142(1):49-55
Sunto
Sia : YY un rivestimento doppio non diramato di una curva di genere quattro definita su
C
e a moduli generali. Sia il punto di 2-divisione associate a . In questa nota si studia il sistema 2 delle quardriche di contatto al modello canonico di Y, associato al dato rivestimento.e si esplicita una biezione tra l'insieme delle theta-caratteristiche dispari di Y che diffeiscono per e l'insieme dell theta caratteristiche dispari dell curve di genere tre la cui Jacobiana e isomorfa (come v.a.p.p.) alla varieta di Prym P(f Y Y) 相似文献
5.
Wolfgang Arendt 《manuscripta mathematica》1982,40(2-3):277-298
Let A be the generator of a C0-semigroup {T(t); t0} defined on a Banach lattice E. It is shown that T(t) is a lattice homomorphism for all t>0 if and only if A satisfies <¦x¦, Ax>= (xD(A), x D(A)) (where q: EE is the evaluation mapping). This equality is used to obtain a spectral decomposition for generators of positive groups. 相似文献
6.
V. V. Sergeichuk 《Ukrainian Mathematical Journal》1990,42(4):487-491
Up to the classification of Hermitian forms a classification has been given of triplesP=(VF; U1, U2), consisting of a finite dimensional vector space V over a field of characteristic 2 with a symmetric, or a skew-symmetric, or Hermitian form F and two subspaces U1, U2. Two triplesP andP are identified with each other if there exists an isometry Vf Vf such that (Ui)=Ui, i=1, 2.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 4, pp. 549–554, April, 1990. 相似文献
7.
Czesław Stępniak 《Annals of the Institute of Statistical Mathematics》1997,49(3):569-584
Let X and Y be observation vectors in normal linear experiments =N(A, V) and F = N(B, W). We write > Fif for any quadratic form YGY there exists a quadratic formXHX such that E(XHX) = E(Y'GY) and var(X'HX) var(Y'GY).The relation > is characterized by the matrices A, B, V and W. Moreoversome connections with known orderings of linear experiments are given. 相似文献
8.
Michael Klemm 《Journal of Geometry》1991,41(1-2):114-123
BOSE and CONNOR [2] proved that a symmetric regular divisible design with w classes of sizes g and joining numbers 1 and 2 must satisfy for every prime p the arithmetic condition (d1, (–1)sw)p(d2,(–l)tgw)p=1, where d1=k2–v2, d2= k–1 s=(w-1)(w-2)/2, t=(v-w)(v-w-1)/2 and (*,*) is the Hilbert symbol. We show that if in addition 1 2 and the design is fully symmetric divisible then (d1, (–1)s w)p=(d2, (–1)tgw)=1. Our assumption is by a result of CONNOR [5] fulfilled, if d1 and 1–2 are relatively prime. Thus, we can exclude parameters not accessible to the Bose-Connor-Theorem. Our result can be derived from a theorem of RAGHAVARAO [9], and we give the precise assumptions of this theorem. We also discuss arithmetic restrictions for divisible designs which satisfy diverse other rules for the intersection numbers and generalize a result of DEMBOWSKI [6; 2.1.11].Dedicated to Professor Benz on occasion of his sixtieth birthday 相似文献
9.
Qiguang Wu 《应用数学学报(英文版)》1993,9(3):281-288
LetY be distributed according to ann-variate normal distribution with a meanX and a nonsingular covariance matrix
2
V, where bothX andV are known, R
p
is a parameter, > 0 is known or unknown. Denote
and
. Assume thatF is linearly estimable. When is known, it is proved that the unbiased loss estimator
2tr(F(XV
–1
X)–
F) of
is admissible for rank (F)=k4 and inadmissible fork 5 with the squared error loss
. When is unknown and rank (X) <n, it is established that the loss estimatorcS
2, wherec is any nonnegative constant, of
is inadmissible and that the unbiased loss estimator tr(F(XV
–1
X)–
F) of
is admissible fork 4, and inadmissible fork 5 with squared error loss.This project is supported by the National Natural Science Foundation of China. 相似文献
10.
Difference Sets with n = 2pm 总被引:1,自引:0,他引:1
Mikhail Muzychuk 《Journal of Algebraic Combinatorics》1998,7(1):77-89
Let D be a (v,k,) difference set over an abelian group G with even n = k - . Assume that t N satisfies the congruences t q
i
fi
(mod exp(G)) for each prime divisor qi of n/2 and some integer fi. In [4] it was shown that t is a multiplier of D provided that n > , (n/2, ) = 1 and (n/2, v) = 1. In this paper we show that the condition n > may be removed. As a corollary we obtain that in the case of n= 2pa when p is a prime, p should be a multiplier of D. This answers an open question mentioned in [2]. 相似文献
11.
B. T. Rumov 《Mathematical Notes》1974,16(1):686-692
We prove imbedding theorems for block designs balanced with respect to pairs, and with the aid of these theorems we establish the existence of (v, k, )-resolvable BIB block designs with parameters v, k, such that =k–1 [and also such that =(k–l)/2 if k is odd], k ¦(p–1) for each prime divisor p of the number v/k; we also establish an imbedding theorem for Kirkman triple systems.Translated from Matematicheskie Zametki, Vol. 16, No. 1, pp. 173–184, July, 1974. 相似文献
12.
Cs. Vincze 《Acta Mathematica Hungarica》2000,89(1-2):111-133
Let (M, E) be a Finsler manifold. A triplet (¯D, ¯h, ) is said to be a Wagner connection on M if (¯D, ¯h) is a Finsler connection, C
(M) and the axioms (W1)–(W4), formulated originally by M. Hashiguchi, are satisfied. Then ¯h is called a Wagner endomorphism on M. We establish an explicit relation between the (canonical) Barthel endomorphism of (M, E) and a Wagner endomorphism ¯h. We show that the second Cartan tensors ¯C, ¯C
b
belonging to ¯h are symmetric and totally symmetric, respectively. An explicit relation between the "canonical" tensors C, C
b
and the "Wagnerian" ones is also derived. We can conclude that the rules of calculation with respect to a Wagner connection are formally the same as those with respect to the classical Cartan connection. We establish some basic curvature identities concerning a Wagner connection, including Bianchi identities. Finally, we present a new, intrinsic definition as well as several tensorial characterizations of Wagner manifolds. 相似文献
13.
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
14.
Riaz A. Usmani 《BIT Numerical Mathematics》1987,27(4):615-622
Using the quadratic spline interpolates(x) fitting the data (x
i,y
i), 0in and satisfying the end conditionso=yo, we give formulae approximatingy andy at selected knots by orders up toO(h
4). 相似文献
15.
It is well-known that the algebraic tensor product E Y of a not necessarily locally convex topological vector space E and a locally convex space Y can be identified with a subspace of the so-called -product EY (a space of continuous linear mappings from Y into E). So, whenever EY is complete, even the completed tensor product is (isomorphic to) a subspace of EY. As this occurs in many important cases, it is interesting to remark that, for each continuous linear operator u from a locally convex space F into E, there exists a locally convex U with continuous embedding jUE and a continuous linear map ûFU such that u=j·û. As main applications of a combination of these ideas, we obtain a characterization of the functions in as continuous functions with values in locally convex spaces (this gives new aspects for the intergration theory of Gramsch [5]) and a result extending a theorem in [6] on holomorphic functions with values in non locally convex spaces to arbitrary complex manifolds. 相似文献
16.
Wolfgang Grotz 《Monatshefte für Mathematik》1979,88(3):219-228
LetK be an algebraic number field, and for every integer K let () andd(), respectively, denote the number of relatively prime residue classes and the number of divisors of the principal ideal (). Asymptotic equalities are proved for the sums () and d
2(), where runs through certain finite sets of integers ofK. 相似文献
17.
Thorsten Kröncke 《Integral Equations and Operator Theory》2001,40(1):80-105
Let T- S, be a family of not necessarily bounded semi-Fredholm operators, where T and S are operators acting between Banach spaces X and Y, and where S is bounded with D(S) D(T). For compact sets , as well as for certain open sets , we investigate existence and minimal rank of bounded feedback perturbations of the form F=BE such that min.ind (T-S+F)=0 for all . Here B is a given operator from a linear space Z to Y and E is some operator from X to Z.We give a simple characterization of that situation, when such regularizing feedback perturbations exist and show that for compact sets the minimal rank never exceeds max { min.ind (T-S) }+1. Moreover, an example shows that the minimal rank, in fact, may increase from max {...} to max {...}+1, if the given B enforces a certain structure of the feedbachk perturbation F.However, the minimal rank is equal to max { min.ind (T-S) }, if is an open set such that min.ind (T-S) already vanishes for all but finitely many points . We illustrate this result by applying it to the stabilization of certain infinite-dimensional dynamical systems in Hilbert space. 相似文献
18.
Hermann Engels 《Numerische Mathematik》1977,28(1):49-58
Zusammenfassung Es wird eine von einem Parameter , 01 abhängige Familie von Quadraturformeln vorgestellt, für die auf gewissen Hilberträumen analytischer Funktionen ableitungsfreie Fehlerschdranken existieren. Für =0 erhält man als Spezialfall die Gaußschen Quadraturformeln und für =1 die Wilfschen Quadraturformeln. Sämtliche Formeln haben folgende Eigenschaften: Sie sind interpolatorisch, d.h. hier, sie können durch Integration eines hermiteschen Interpolationsoperators erzeugt werden, sie haben positive Gewichte. Ihre Stützstellen liegen im Innern des Integrationsintervalles. Sie sind auch erzeugbar durch Minimierung des Fehlerkoeffizienten, und sie konvergieren für jede im Integrationsintervall stetige Funktion.
A family of quadrature formulas having error bounds without derivatives
Summary A family of quadrature formulas depending on a parameter , 01 is presented which admits error estimates without derivatives for certain Hilbert spaces of analytic functions. For =0 the Gaussian quadrature formulas are contained as a special case, and for =1 the same is valid for the Wilfian quadrature formulas. The formulas have the following properties: They are interpolatory formulas, that means they may be generated on integration of a Hermitian interpolating operator, they have positive weights. Their nodes are inside the interval of integration, and they also may be produced by minimizing the error coefficient. They are convergent for every function which is continuous between the limits of integration.相似文献
19.
We discuss a classical result in planar projective geometry known as Steiners theorem involving 12 interlocking applications of Pappus theorem. We prove this result using three dimensional projective geometry then uncover the dynamics of this construction and relate them to the geometry of the twisted cubic.Mathematics Subject Classification (2000). Primary 51N15. 相似文献
20.
Ryoichi Shimizu Yasunori Fujikoshi 《Annals of the Institute of Statistical Mathematics》1997,49(2):285-297
Let Z be a random variable with the distribution function G(x) and let s be a positive random variable independent of Z. The distribution function F(x) of the scale mixture X = sZ is expanded around G(x) and the difference between F(x) and its expansion is evaluated in terms of a quantity depending only on G and the moments of the powers of the variable of the form s/gr - 1, where (> 0) and (= ±1) are parameters indicating the types of expansion. For = -1, the bound is sharp under some extra conditions. Sharp bounds for errors of the approximations of the scale mixture of the standard normal and some gamma distributions are given either by analysis ( = -1) or by numerical computation ( = 1). 相似文献