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111.
Venkat Anantharam 《Queueing Systems》2006,52(3):185-188
Given n−1 points
on the real line and a set of n rods of strictly positive lengths
, we get to choose an n-th point xn anywhere on the real line and to assign the rods to the points according to an arbitrary permutation π. The rod
is thought of as the workload brought in by a customer arriving at time xk into a first in -first out queue which starts empty at − ∞. If any xi equals xj for i < j, service is provided to the rod assigned to xi before the rod assigned to xj.
Let
denote the set of departure times of the customers (rods). Let
denote the number of choices for the location of xn for which
. Rybko and Shlosman proved that
for Lebesgue almost all
.
Let
denote the departure point of the rod λk. Let Nπ, k(y) denote the number of choices for the location of xn for which
and let
. In this paper we prove that for every
and every k we have
for all but finitely many y. This implies (and strengthens) the rod placement theorem of Rybko and Shlosman.
AMS Subject Classifications: 60G55, 05A05, 60C05, 60K25
Research supported by ONR MURI N00014-1-0637, NSF ECS-0123512, Marvell Semiconductor, and the University of California MICRO
program. 相似文献
112.
113.
A key issue for high integration circuit design in the semiconductor industry are power constraints that stem from the need for heat removal and reliability or battery lifetime limitations. As the power consumption depends heavily on the capacitances between adjacent wires, determining the optimal ordering and spacing of parallel wires is an important issue in the design of low power chips. As it turns out, optimal wire spacing is a convex optimization problem, whereas the optimal wire ordering is combinatorial in nature, containing (a special class of) the Minimum Hamilton Path problem. While the latter is ${\mathcal{NP}}A key issue for high integration circuit design in the semiconductor industry are power constraints that stem from the need
for heat removal and reliability or battery lifetime limitations. As the power consumption depends heavily on the capacitances
between adjacent wires, determining the optimal ordering and spacing of parallel wires is an important issue in the design
of low power chips. As it turns out, optimal wire spacing is a convex optimization problem, whereas the optimal wire ordering
is combinatorial in nature, containing (a special class of) the Minimum Hamilton Path problem. While the latter is -hard in general, the present paper provides an algorithm that solves the coupled ordering and spacing problem for N parallel wires to optimality.
Dedicated to Prof. Martin Gr?tschel on the occasion of his 60th birthday. 相似文献
114.
This paper deals with the pole placement of the singular system Ex~.=Ax(t) Dx(t-(?)) Bu, y=Cx, where x∈R~n,u∈R~m,and y∈R~n are its state,control input and measure output respectively;E,A∈R~(n×n),B∈R~(n×m),and C∈R~((?)×n) are constant matrices.It is also assumed that rankE相似文献
115.
116.
117.
Gregory J. Gallivan 《Journal of voice》1991,5(4):338-348
Severe damage to the vocal folds and upper airways after translaryngeal endotracheal intubation occurs with greater frequency and to a greater extent than is usually surmised. Videolaryngoscopic techniques have led to prompt recognition of endolaryngeal/endotracheal lesions in the critical care setting. Traditionally, surgeons have treated obstructive sequelae such as glottic, subglottic, and tracheal stenosis by major transcervical and/or transthoracic resective and reconstructive surgery. Endolaryngeal core molds and endotracheal stents have conventionally been inserted by open surgical techniques. As a prototypic case illustrates, evolutional methods of endoscopic placement of prosthetic molds and stents combined with endoscopic optical/suction instrumentation and laser photoresection allow the physician to restore upper airway patency and phonatory vocal fold function without resorting to major surgery. Delta scan topograms provide radiographic imaging of the major airways. 相似文献
118.
A. Albrecht S.K. Cheung K.S. Leung C.K. Wong 《Computational Optimization and Applications》2001,19(2):179-208
This paper deals with the minimization of local forces in two-dimensional placements of flexible objects within rigid boundaries. The objects are disks of the same size but, in general, of different materials. Potential applications include the design of new amorphous polymeric and related granular materials as well as the design of package cushioning systems. The problem is considered on a grid structure with a fixed step size w and for a fixed diameter of the discs, i.e., the number of placed disks may increase as the size of the placement region increases. The near-equilibrium configurations have to be calculated from uniformly distributed random initial placements. The final arrangements of disks must ensure that any particular object is deformed only within the limits of elasticity of the material. The main result concerns -approximations of the probability distribution on the set of equilibrium placements. Under a natural assumption about the configuration space, we prove that a run-time of n+logO(1)(1/} is sufficient to approach with probability 1 – the minimum value of the objective function, where depends on the maximum of the escape depth of local minima within the underlying energy landscape. The result is derived from a careful analysis of the interaction among probabilities assigned to configurations from adjacent distance levels to minimum placements. The overall approach for estimating the convergence rate is relatively independent of the particular placement problem and can be applied to various optimization problems with similar properties of the associated landscape of the objective function. 相似文献
119.
Thomas L. Magnanti Zuo-Jun Max Shen David Simchi-Levi Chung-Piaw Teo 《Operations Research Letters》2006,34(2):228-238
By adding a set of redundant constraints, and by iteratively refining the approximation, we show that a commercial solver is able to routinely solve moderate-size strategic safety stock placement problems to optimality. The speed-up arises because the solver automatically generates strong flow cover cuts using the redundant constraints. 相似文献
120.
Focusing performance of a multilayer Laue lens with layer placement error described by dynamical diffraction theory
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The multilayer Laue lens (MLL) is essentially a linear zone plate with large aspect ratio, which can theoretically focus hard X‐rays to well below 1 nm with high efficiency when ideal structures are used. However, the focusing performance of a MLL depends heavily on the quality of the layers, especially the layer placement error which always exists in real MLLs. Here, a dynamical modeling approach, based on the coupled wave theory, is proposed to study the focusing performance of a MLL with layer placement error. The result of simulation shows that this method can be applied to various forms of layer placement error. 相似文献