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861.
We consider biased random walk on supercritical percolation clusters in ℤ2. We show that the random walk is transient and that there are two speed regimes: If the bias is large enough, the random
walk has speed zero, while if the bias is small enough, the speed of the random walk is positive.
Received: 20 November 2002 / Revised version: 17 January 2003
Published online: 15 April 2003
Research supported by Microsoft Research graduate fellowship.
Research partially supported by the DFG under grant SPP 1033.
Research partially supported by NSF grant #DMS-0104073 and by a Miller Professorship at UC Berkeley.
Mathematics Subject Classification (2000): 60K37; 60K35; 60G50
Key words or phrases: Percolation – Random walk 相似文献
862.
The effect of solar features on geospheric conditions leading to geomagnetic storms (GMSs) with planetary index,A
P ≥ 20 and the range of horizontal component of the Earth’s magnetic fieldH such that 250γ <H < 400γ has been investigated using interplanetary magnetic field (IMF), solar wind plasma (SWP) and solar geophysical data
(SGD) during the period 1978–99. Statistically, it is observed that maximum number of GMSs have occurred during the maximum
solar activity years of 21st and 22nd solar cycles. A peculiar result has been observed during the years 1982, 1994 when sunspot
numbers (SSNs) decrease very rapidly while numbers of GMSs increase. No distinct association between yearly occurrence of
disturbed days and SSNs is observed. Maximum number of disturbed days have occurred during spring and rainy seasons showing
a seasonal variation of disturbed days. No significant correlation between magnitude (intensity) of GMSs and importance ofH
α
, X-ray solar flares has been observed. Maximum number of GMSs is associated with solar flares of lower importance, i.e.,
SF during the period 1978-93.H
α
, X-ray solar flares occurred within lower helio-latitudes, i.e., (0–30)°N to (0–30)°S are associated with GMSs. NoH
α
, X-ray solar flares have occurred beyond 40°N or 40°S in association with GMSs. In helio-latitude range (10–40)°N to (10–40)°S,
the 89.5% concentration of active prominences and disappearing filaments (APDFs) are associated with GMSs. Maximum number
of GMSs are associated with solar flares. Coronal mass ejections (CMEs) are related with eruptive prominences, solar flares,
type IV radio burst and they occur at low helio-latitude. It is observed that CMEs related GMS events are not always associated
with high speed solar wind streams (HSSWSs). In many individual events, the travel time between the explosion on the Sun and
maximum activity lies between 58 and 118 h causing GMSs at the Earth. 相似文献
863.
Victor Alexandrov 《Geometriae Dedicata》2004,107(1):169-186
Classical H. Minkowski theorems on existence and uniqueness of convex polyhedra with prescribed directions and areas of faces as well as the well-known generalization of H. Minkowski uniqueness theorem due to A.D. Alexandrov are extended to a class of nonconvex polyhedra which are called polyhedral herissons and may be described as polyhedra with injective spherical image. 相似文献
864.
The facility layout problem is concerned with finding the most efficient arrangement of a given number of departments with unequal area requirements within a facility. The facility layout problem is a hard problem, and therefore, exact solution methods are only feasible for small or greatly restricted problems. In this paper, we propose a spring-embedding approach that unlike previous approaches results in a model that is convex. Numerical results demonstrating the potential of our model and the efficiency of our solution procedure are presented. 相似文献
865.
R Teunter E van der Laan D Vlachos 《The Journal of the Operational Research Society》2004,55(5):475-484
We describe hybrid manufacturing/remanufacturing systems with a long lead time for manufacturing and a short lead time for remanufacturing. We review the classes of inventory strategies for hybrid systems in the literature. These are all based on equal lead times. For systems with slow manufacturing and fast remanufacturing, we propose a new class. An extensive numerical experiment shows that the optimal strategy in the new class almost always performs better and often much better than the optimal strategies in all other classes. 相似文献
866.
OR methods and tools are being increasingly applied within the health services domain to support objective decision-making for the effective and efficient provision of resources. Healthcare modelling, however, is beset with many challenges and this paper examines a number of issues that define the primary challenges faced by the modeller in this field. It is fair to say that their resolution determines the likely success or failure of healthcare modelling in general. Working with a number of participating health service organizations, a proposed framework towards successful implementation has evolved and is presented in this paper 相似文献
867.
Ruili?ZhangEmail author Jianming?Dai Wenhai?Song Yongqing?Ma Jie?Yang Yuping?Sun 《中国科学G辑(英文版)》2004,47(1):113-120
It is helpful to study the photo-induced effect in the perovskite manganites not only for elucidating the mechanism of colossal
magnetoresistance (CMR) effect but also for potential applications in technology. The laser-induced effect in the Co doping
layered perovskite manganites La1.2Sr1.8Mn1.8Co0.2O7, is studied in this paper and the obtained results are also compared with that gained in the Nd-doping manganites with cubic
perovskite structure. 相似文献
868.
869.
Three mechanisms to reduce threading dislocations(TDs) in GaN films as the epitaxial films grow thicker are suggested by SEM and TEM 相似文献
870.
Sergio A. Celani 《Central European Journal of Mathematics》2003,1(4):561-572
In this paper we shall give a topological representation for Hilbert algebras that extend the topological representation given
by A. Diego in [4]. For implicative semilattices this representation gives a full duality. We shall also consider the representation
for Boolean ring. 相似文献