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Overload problem research on aperiodic real-time tasks
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作者 吴悦 唐立三 杨洪斌 《Journal of Shanghai University(English Edition)》 CAS 2009年第2期136-141,共6页
In this paper, a novel scheduling mechanism is proposed to handle the real-time overload problem by maximizing the cumulative values of three types of tasks: the soft, the hard and the imprecise tasks. The simulation... In this paper, a novel scheduling mechanism is proposed to handle the real-time overload problem by maximizing the cumulative values of three types of tasks: the soft, the hard and the imprecise tasks. The simulation results show that the performance of our presented mechanism in this paper is greatly improved, much better than that of the other three mechanisms: earliest deadline first (EDF), highest value first (HVF) and highest density first (HDF), under the same conditions of all nominal loads and task type proportions. 展开更多
关键词 aperiodic real-time tasks tasks overload multi-choice knapsack problem nominal load hit value ratio
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SOME BASIC PROBLEMS IN NUMERICALLY SIMULATING EFFECTIVE PROPERTIFS AND LOCAL FIELDS OF COMPOSITE MATERIALS
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作者 Wen Ming Zheng Quanshui Du Danxu (Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China) 《Acta Mechanica Solida Sinica》 SCIE EI 1999年第4期328-339,共12页
It is pointed out that to numerically estimate the effective properties and local fields of matrix-inclusion composites,a commonly adopted method is accompanied with some serious draw- backs.We call this method the no... It is pointed out that to numerically estimate the effective properties and local fields of matrix-inclusion composites,a commonly adopted method is accompanied with some serious draw- backs.We call this method the nominal loading scheme(NLS),which considers the actual inclusion distribution inside a finite domain,Ω say,treats the external domain of Ω to be of the pure matrix ma- terial,and imposes the actural traction,σ~∞ say on the remote boundary.It thus gives rise to the fol- lowing basic problems:(i)Can NLS be improved remarkably just by adjusting σ~∞?(it)What is the relationship between the size of Ω and the,scale of inclusions?(iii)Which choice is better in calculating the effective properties,the whole domain Ω or an appropriately selected sub-domain of Ω? Targeting these problems,the equivalent loading,scheme (ELS)and equivalent matrix scheme(EMS)are proposed.It is theoretically analyzed that both ELS and EMS can be used to precisely simulating the effective properties and local fields of matrix-inclusion composites,and both ELS and EMS are self-approved. As an application,ELS combined with a m-called pseudo-dislocations method is used to evaluate the effective properties and local fields of two-dimensional two-phase compos- ites with close-packed circular inclusions,or randomly distributed circular inclusions, or randomly distributed mierocracks.The results show that substituting the remote trac- tion σ~∞ with the effective stress field σ~E suggested by IDD scheme is a simple and effec- tive method,and the estimation of the effective properties and local fields is very close to the accurate,solution. 展开更多
关键词 nominal loading scheme equivalent loading scheme equivalent matrix scheme
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