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51.
A server needs to compute a broadcast schedule for n pages whose request times are known in advance. Outputting a page satisfies all outstanding requests for the page. The goal is to minimize the average waiting time of a client. In this paper, we show the equivalence of two apparently different relaxations that have been considered for this problem. 相似文献
52.
Robust linear optimization under general norms 总被引:1,自引:0,他引:1
We explicitly characterize the robust counterpart of a linear programming problem with uncertainty set described by an arbitrary norm. Our approach encompasses several approaches from the literature and provides guarantees for constraint violation under probabilistic models that allow arbitrary dependencies in the distribution of the uncertain coefficients. 相似文献
53.
The results of experimental investigation into the mechanical properties of blends of low-density polyethylene (LDPE) with chlorinated polyethylene (CPE) in tension are presented. The specimens of pure LDPE, CPE, and nine types of LDPE/CPE blends, with different content of components at 10 wt.% intervals, were examined. Data on the influence of blend composition on the tensile stress-strain diagram, elastic modulus, yield stress, breaking stress, and ultimate elongation are obtained. The results of investigations of creep are also reported. It is found that the creep compliance (the total current compliance minus the elastic compliance) obeys the power law of creep.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 3, pp. 391–404, May–June, 2005. 相似文献
54.
The projective method for solving linear matrix inequalities 总被引:2,自引:0,他引:2
Numerous problems in control and systems theory can be formulated in terms of linear matrix inequalities (LMI). Since solving
an LMI amounts to a convex optimization problem, such formulations are known to be numerically tractable. However, the interest
in LMI-based design techniques has really surged with the introduction of efficient interior-point methods for solving LMIs
with a polynomial-time complexity. This paper describes one particular method called the Projective Method. Simple geometrical
arguments are used to clarify the strategy and convergence mechanism of the Projective algorithm. A complexity analysis is
provided, and applications to two generic LMI problems (feasibility and linear objective minimization) are discussed. 相似文献
55.
Lai Chunhui 《东北数学》1997,(1)
SomePropertiesofQuasi┐keep┐rangeOperatorsandTheirApplicationsLaiChunhui(赖春晖)(DepartmentofMathematics,ZhangzhouTeachersColege,... 相似文献
56.
In [5] Phillips proved that one can obtain the additive group of any nonstandard model *? of the ring ? of integers by using a linear mod 1 function h : F ?, where F is the α-dimensional vector space over ? when α is the cardinality of *?. In this connection it arises the question whether there are linear mod 1 functions which are neither addition nor quasi-linear. We prove that this is the case. 相似文献
57.
Kurt M. Anstreicher 《Mathematical Programming》1997,76(1):245-263
We consider the construction of small step path following algorithms using volumetric, and mixed volumetric-logarithmic, barriers.
We establish quadratic convergence of a volumetric centering measure using pure Newton steps, enabling us to use relatively
standard proof techniques for several subsequently needed results. Using a mixed volumetric-logarithmic barrier we obtain
an O(n
1/4
m
1/4
L) iteration algorithm for linear programs withn variables andm inequality constraints, providing an alternative derivation for results first obtained by Vaidya and Atkinson. In addition,
we show that the same iteration complexity can be attained while holding the work per iteration to O(n
2
m), as opposed to O(nm
2), operations, by avoiding use of the true Hessian of the volumetric barrier. Our analysis also provides a simplified proof
of self-concordancy of the volumetric and mixed volumetric-logarithmic barriers, originally due to Nesterov and Nemirovskii.
This paper was first presented at the 1994 Faculty Research Seminar “Optimization in Theory and Practice”, at the University
of Iowa Center for Advanced Studies. 相似文献
58.
59.
L.-H. Tang P. Smilauer D.D. Vvedensky 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(3):409-412
Two types of mechanisms are proposed for mound coarsening during unstable epitaxial growth: stochastic, due to deposition
noise, and deterministic, due to mass currents driven by surface energy differences. Both yield the relation H=(RWL)2 between the typical mound height W, mound size L, and the film thickness H. An analysis of simulations and experimental data shows that the parameter R saturates to a value which discriminates sharply between stochastic () and deterministic () coarsening. We derive a scaling relation between the coarsening exponent 1/z and the mound-height exponent which, for a saturated mound slope, yields .
Received: 11 November 1997 / Revised in final form: 28 November 1997 /
Accepted: 28 November 1997 相似文献
60.
An analytic and numerical study of the behavior of the linear nonhomogeneous wave equation of the form ε2utt = Δu + tf with high wave speed (ε 1) is carried out. This study was initially motivated by meteorological observations which have indicated the presence of large spatial scale gravity waves in the neighborhood of a number of summer and winter storms, mainly from visible images of ripples in clouds in satellite photos. There is a question as to whether the presence of these waves is caused by the nearby storms. Since the linear wave equation is an approximation to the full system describing pressure waves in the atmosphere, yet is considerably more tractable, we have chosen to analyze the behavior of the linear nonhomogeneous wave equation with high wave speed. The analysis is shown to be valid in one, two, and three space dimensions. Partly because of the high wave speed, the solution is known to consist of behavior which changes on two different time scales, one rapid and one slow. Additionally, because of the presence of the nonhomogeneous forcing term tf, we show that there is a component of the solution which will vary only on a very large spatial scale. Since even the linearized wave equation can give rise to persistent large spatial scale waves under the right conditions, the implication is that certain storms could be responsible for the generation of large-scale waves. Numerical simulations in one and two dimensions confirm analytic results. 相似文献