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991.
Miodrag M. Spalević 《Numerical Algorithms》2007,46(3):253-264
We have recently proposed a very simple numerical method for constructing the averaged Gaussian quadrature formulas. These
formulas exist in many more cases than the real positive Gauss–Kronrod formulas. In this note we try to answer whether the
averaged Gaussian formulas are an adequate alternative to the corresponding Gauss–Kronrod quadrature formulas, to estimate
the remainder term of a Gaussian rule. 相似文献
992.
Yang H. C. 《显形杂志》2007,10(1):83-89
Motionless mixers have found a large range of applications, including blending, reaction, dispersion, heat transfer and mass
transfer. Understanding the mixing processes that occur in these diverse systems is essential for predicting many aspects
of practical importance. The objective of this study is to perform the experimental investigations of mixing characteristics
for three different motionless mixers. The red color dye tracer was mixed in the main stream of green hair styling gel, and
then the mixing efficiency was quantified by calculating the percentage area concentration of red color at the outlet cross
section using a digital image processing technique. In the Sulzer SMX and YHC mixer, a single element mixes the fluid nearly
in two dimensions, and three-dimensional mixing is accomplished by the next elements aligned at 90o to their former one. In
the Sulzer SMX mixer, the flow appears to be globally well mixed after 5 elements, while in the YHC and YNU mixers, it is
necessary to globally well mix more than 1 and 2 elements. 相似文献
993.
B Karimi S M T Fatemi Ghomi J M Wilson 《The Journal of the Operational Research Society》2006,57(2):140-147
In this paper, the multi-item, single-level, capacitated, dynamic lot sizing problem with set-up carry-over and backlogging, abbreviated to CLSP+, is considered. The problem is formulated as a mixed integer programming problem. A heuristic method consisting of four elements: (1) a demand shifting rule, (2) lot size determination rules, (3) checking feasibility conditions and (4) set-up carry-over determination, provides us with an initial feasible solution. The resulting feasible solution is improved by adopting the corresponding set-up and set-up carry-over schedule and re-optimizing it by solving a minimum-cost network flow problem. Then the improved solution is used as a starting solution for a tabu search procedure, with the value of moves assessed using the same minimum-cost network problem. Computational results on randomly generated problems show that the algorithm, which is coded in C++, is able to provide optimal solutions or solutions extremely close to optimal. The computational efficiency makes it possible to solve reasonably large problem instances routinely on a personal computer. 相似文献
994.
We investigate traces of functions, belonging to a class of functions with dominating mixed smoothness in ℝ3, with respect to planes in oblique position. In comparison with the classical theory for isotropic spaces a few new phenomenona
occur. We shall present two different approaches. One is based on the use of the Fourier transform and restricted to p = 2. The other one is applicable in the general case of Besov-Lizorkin-Triebel spaces and based on atomic decompositions. 相似文献
995.
In the present paper, we solve three boundary value problems related to the temperature field in oil strata — the fractional
extensions of the incomplete lumped formulation and lumped formulation in the linear case and the fractional generalization
of the incomplete lumped formulation in the radial case. By using the Caputo differintegral operator and the Laplace transform,
the solutions are obtained in integral forms where the integrand is expressed in terms of the convolution of some auxiliary
functions of Wright function type. A generalization of the Laplace transform convolution theorem, known as Efros’ theorem
is widely used. 相似文献
996.
We examine the resource allocation problem of partitioning identical servers into two parallel pooling centers, and simultaneously
assigning job types to pooling centers. Each job type has a distinct Poisson arrival rate and a distinct holding cost per
unit time. Each pooling center becomes a queueing system with an exponential service time distribution. The goal is to minimize
the total holding cost. The problem is shown to be polynomial if a job type can be divided between the pooling centers, and
NP-hard if dividing job types is not possible. When there are two servers and jobs cannot be divided, we demonstrate that
the two pooling center configuration is rarely optimal. A heuristic which checks the single pooling center has an upper bound
on the relative error of 4/3. The heuristic is extended for the multiple server problem, where relative error is bounded above
by the number of servers.
相似文献
997.
Prior studies have shown that inventories in a one vendor, multi-buyer supply chain with deterministic demands can be coordinated effectively through the use of common replenishment epochs (CRE). In this paper, we study the impact of demand uncertainty on the effectiveness of coordinating such a supply chain. We develop a model to analyse the coordination mechanism using CRE in a one-vendor, multi-buyer supply chain, when the demand faced by the buyers is stochastic. Our numerical study based on the model found that coordination through CRE may not always be beneficial when the demand variance is high. We also investigate a strategy of advance order processing by the vendor to improve the effectiveness of coordination through CRE. 相似文献
998.
999.
There is a general interest in ranking schemes applied to complex entities described by multiple attributes. Published rankings
for universities are in great demand but are also highly controversial. We compare two classification and ranking schemes
involving universities; one from a published report, ‘Top American Research Universities’ by the University of Florida's TheCenter and the other using DEA. Both approaches use the same data and model. We compare the two methods and discover important equivalences.
We conclude that the critical aspect in classification and ranking is the model. This suggests that DEA is a suitable tool
for these types of studies. 相似文献
1000.
N J Curtis P J Dortmans J Ciuk 《The Journal of the Operational Research Society》2006,57(11):1300-1312
The essential first step of any OR investigation is to ensure that the ‘right problem’ is studied. Our approach is to propose a set of six ‘rights’ or questions whereby achievement against particular aspects of a problem space is made and these provide the basis for scoping the context, understanding the system, and proposing sound options to the decision-maker. This style of problem structuring is an essential element of the Defence problem domain, and especially so for the Land Force, where there exist multiple degrees of freedom for poorly defined problems in an environment of uncertainty and ambiguity. Central to this is performing conceptual rather than analytical modelling, as perturbations then provide a basis for exploring a space, rather than solving a problem. 相似文献