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高清晰度电视:全数字化时代
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作者 姚庆栋 《科学》 1997年第2期26-29,共4页
彩色电视进入了千家万户,并逐步成为生活必须,为什么又要向高清晰度电视(HDTV,High DefinitionTelevision)发展呢?其目的是为了使人们在观看电视时能享受到与日常生活中景物效果一样的图象。人眼的视野相当广,左右将近180°,上下有6... 彩色电视进入了千家万户,并逐步成为生活必须,为什么又要向高清晰度电视(HDTV,High DefinitionTelevision)发展呢?其目的是为了使人们在观看电视时能享受到与日常生活中景物效果一样的图象。人眼的视野相当广,左右将近180°,上下有60°。为了使人们观看的图象达到接近实际景物的效果,电影先走了一步,从窄银幕电影发展成为宽银幕电影。 展开更多
关键词 电视机 高清晰度电视 全数学化
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Global Optimization Algorithm for Nonlinear Sum of Ratios Problems
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作者 JIAO Hong-wei GUO Yun-rui CHEN Yong-qiang 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2008年第4期499-505,共7页
In this paper, a global optimization algorithm is proposed for nonlinear sum of ratios problem (P). The algorithm works by globally solving problem (P1) that is equivalent to problem (P), by utilizing linearizat... In this paper, a global optimization algorithm is proposed for nonlinear sum of ratios problem (P). The algorithm works by globally solving problem (P1) that is equivalent to problem (P), by utilizing linearization technique a linear relaxation programming of the (P1) is then obtained. The proposed algorithm is convergent to the global minimum of (P1) through the successive refinement of linear relaxation of the feasible region of objective function and solutions of a series of linear relaxation programming. Numerical results indicate that the proposed algorithm is feasible and can be used to globally solve nonlinear sum of ratios problems (P). 展开更多
关键词 global optimization nonlinear sum of ratios linearization technique
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Theoretical Considerations of Laminar Flame Speed as a Function of Initial Conditions and Basic Kinetic Properties with Respect to the Safety Problem
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作者 Jorge Yanez Mike Kuznetsov Alexei Kotchourko Alexander Lelyakin Tomas Jordan 《Journal of Energy and Power Engineering》 2012年第6期849-857,共9页
The Zeldovich-Frank-Kamenetskii solution for the flame velocity of a planar front with one-step overall chemical reaction was enhanced. The assumption that the consumption rate depends exclusively on a chemical compon... The Zeldovich-Frank-Kamenetskii solution for the flame velocity of a planar front with one-step overall chemical reaction was enhanced. The assumption that the consumption rate depends exclusively on a chemical component was removed. Instead, the reaction rate was considered to be dependent on all reactants of an overall reaction. The new formulation was applied to obtain the activation energy and the pre-exponential factor of a set of hydrogen-air mixtures. 展开更多
关键词 Laminar flame velocity activation energy explosion hydrogen safety.
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