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四边形生成的三种圆锥曲线
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作者 杨炼 《中学数学月刊》 2005年第8期37-38,共2页
关键词 圆锥曲线 面积恒定 平行四边形 高中 数学 解析几何
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三维立体显示中的纹理误差消除
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作者 吕林森 翟正军 +1 位作者 王季 马捷中 《计算机工程与设计》 CSCD 北大核心 2008年第18期4813-4814,4827,共3页
在两步纹理映射算法中,一般以半球面作为中介面来进行立体投影,由于球体的不可延展性,在映射的过程中不可避免的会产生较大的纹理形变,严重影响了立体显示的真实感。分析了传统的基于立体投影映射的方法产生纹理形变的原因,将纹理不变... 在两步纹理映射算法中,一般以半球面作为中介面来进行立体投影,由于球体的不可延展性,在映射的过程中不可避免的会产生较大的纹理形变,严重影响了立体显示的真实感。分析了传统的基于立体投影映射的方法产生纹理形变的原因,将纹理不变形准则与半球面纹理映射技术相结合,并采用了双中心立体投影算法进行三维立体显示,提高了立体显示中纹理映射的质量,有效的消除了立体显示中的纹理误差,具有较好的真实感。 展开更多
关键词 纹理映射 面积恒定 三维立体显示 双中心立体投影算法 真实感
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Study on the propagation law of shock wave resulting from coal and gas outburst 被引量:2
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作者 WANG Kai ZHOU Ai-tao +2 位作者 ZHANG Pin LI Chuan GUO Yan-wei 《Journal of Coal Science & Engineering(China)》 2011年第2期142-146,共5页
According to the formation of shock wave resulting from coal and gas outburst, the gas flow of coal and gas outburst was transformed from an unsteady flow to a steady one based on selected appropriate reference coordi... According to the formation of shock wave resulting from coal and gas outburst, the gas flow of coal and gas outburst was transformed from an unsteady flow to a steady one based on selected appropriate reference coordinates, and the mathematical expressions were then established by applying mass conservation, momentum conservation equation, and energy conservation equation. On this basis, analyzed gas flow mitigation of variable cross-section area and the outburst intensity, and the relations between cross-section area, velocity, and density; the relations between overpressures and outburst intensity were deduced. Furthermore, shock waves resulting from coal and gas outburst and outburst intensity were measured by experimental setup, the overpressure and outburst intensity of different gas pressures were obtained, and the similar conditions of the experiment were numerically simulated. The averaged overpressure and gas flow velocity of variable cross-section under different gas pressures were numerically derived. The results show that the averaged overpressure and outburst intensity obtained from simulation are in good agreement with the experimental results. Moreover, the gas flow velocity of variable cross-sections approximates to the theoretical analysis. 展开更多
关键词 coal and gas outburst shock wave OVERPRESSURE gas flow velocity outburst intensity
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