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11.
12.
王柏懿 《应用数学和力学(英文版)》2003,24(8):928-935
By using Lagrangian method, the flow properties of a dusty-gas point source in a supersonic free stream were studied and the particle parameters in the near-symmetry-axis region were obtained . It is demonstrated that fairly inertial particles travel along oscillating and intersecting trajectories between the bow and termination shock waves . In this region, formation of " mufti- layer structure" in panicle distribution with alternating low- and high density layers is revealed. Moreover, sharp accumulation of particles occurs near the envelopes of particle trajectories . 相似文献
13.
Julie Kerr 《Journal of Algebraic Combinatorics》1999,9(1):47-60
For a fixed positive integer k, consider the collection of all affine hyperplanes in n-space given by xi – xj = m, where i, j [n], i j, and m {0, 1,..., k}. Let Ln,k be the set of all nonempty affine subspaces (including the empty space) which can be obtained by intersecting some subset of these affine hyperplanes. Now give Ln,k a lattice structure by ordering its elements by reverse inclusion. The symmetric group Gn acts naturally on Ln,k by permuting the coordinates of the space, and this action extends to an action on the top homology of Ln,k. It is easy to show by computing the character of this action that the top homology is isomorphic as an Gn-module to a direct sum of copies of the regular representation, CGn. In this paper, we construct an explicit basis for the top homology of Ln,k, where the basis elements are indexed by all labelled, rooted, (k + 1)-ary trees on n-vertices in which the root has no 0-child. This construction gives an explicit Gn-equivariant isomorphism between the top homology of Ln,k and a direct sum of copies of CGn. 相似文献
14.
We define the concept of fuzzy nilpotent algebra, prove that the homomorphic inverse image of a fuzzy nilpotent algebra is also nilpotent and study the intersection and union of fuzzy nilpotent algebras. 相似文献
15.
Let {B
1
d
(t)} and {B
d
2(t)} be independent Brownian motions in R
d
starting from 0 and nx respectively, and let w
d
i
(a,b) ={xR
d
: B
d
i
(t)=x for some t(a,b)}, i=1,2. Asymptotic expressions as n for the probability of dist(w
d
1(n
2
t
1, n
2
t
2), w
2
d
(0,n
2
t
3))1 with d4, respectively for the probability of dist(w
1
4(n
2
t
1,n
2
t
2),w
2
4(0,n
2
t
3))1 are obtained. As an application, an improvement of a result due to M. Aizenman concerning the intersections of Wiener sausages in R
4 is presented. 相似文献
16.
陆相断陷湖盆陡坡带发育各种成围的砂砾岩扇体,其储集性能具有极强的非均质性,已成为高成熟勘探区重要的勘探目标,钻前对有利沉积相带的预测以及钻后对储集性能的分析,已成为提高勘探开发效益的关键.针对胜利油田济阳坳陷陡坡带发育的各种成围的砂砾岩扇体,综合应用测井相、多种测井咱应交会法、储层参数的测井定量解释、含油渗透层的测井判识等多种技术和方法,有效地对砂砾岩扇体的成围类型和储层岩性进行了判识,建立了孔隙度、渗透卑等储层参数解释的理论模型并进行了定量解释,划分了有效渗透层,取得了明显的勘探开发效果.这些新技术的综合运用为其他类似地区砂砾岩扇体的勘探与开发提供了技术支持. 相似文献
17.
Paul Valery A. Bressler 《Compositio Mathematica》2003,135(3):245-278
We consider a fan as a ringed space (with finitely many points). We develop the corresponding sheaf theory and functors, such as direct image R* ( is a subdivision of a fan), Verdier duality, etc. The distinguished sheaf
, called the minimal sheaf plays the role of an equivariant intersection cohomology complex on the corresponding toric variety (which exists if is rational). Using
we define the intersection cohomology space IH(). It is conjectured that a strictly convex piecewise linear function on acts as a Lefschetz operator on IH(). We show that this conjecture implies Stanley's conjecture on the unimodality of the generalized h-vector of a convex polytope. 相似文献
18.
We study the syzygies of a codimension two ideal . Our main result is that the module of syzygies vanishing (scheme-theoretically) at the zero locus is generated by the Koszul syzygies iff is a local complete intersection. The proof uses a characterization of complete intersections due to Herzog. When is saturated, we relate our theorem to results of Weyman and Simis and Vasconcelos. We conclude with an example of how our theorem fails for four generated local complete intersections in and we discuss generalizations to higher dimensions.
19.
Let R be a homogeneous ring over an infinite field, IR a homogeneous ideal, and
I an ideal generated by s forms of degrees d
1,...,d
s
so that codim(
:I)s. We give broad conditions for when the Hilbert function of R/
or of R/(
:I) is determined by I and the degrees d
1,...,d
s
. These conditions are expressed in terms of residual intersections of I, culminating in the notion of residually S
2 ideals. We prove that the residually S
2 property is implied by the vanishing of certain Ext modules and deduce that generic projections tend to produce ideals with this property. 相似文献
20.
A 'chaos expansion' of the intersection local time functional of two independent Brownian motions in R
d
is given. The expansion is in terms of normal products of white noise (corresponding to multiple Wiener integrals). As a consequence of the local structure of the normal products, the kernel functions in the expansion are explicitly given and exhibit clearly the dimension dependent singularities of the local time functional. Their L
p
-properties are discussed. An important tool for deriving the chaos expansion is a computation of the 'S-transform' of the corresponding regularized intersection local times and a control about their singular limit. 相似文献