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织物组织几何模型及其在织物外观模拟上的应用 被引量:3
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作者 贺显伟 汪军 《纺织导报》 CAS 2003年第6期114-116,共3页
介绍了4种典型的织物组织几何模型,即圆形理论模型、椭圆形理论模型、跑道形理论模型、透镜形理论模型,并以圆形模型为例,研究其参数间的数学关系及在织物计算机外观模拟仿真上的应用。
关键词 织物组织 几何模型 外观模拟 圆形模型 计算机仿真 椭圆形理论模型 跑道形理论模型 透镜形理论模型
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基于MATLAB的飞船测控系统仿真
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作者 王媛 刘晓鑫 《电子设计工程》 2014年第4期84-87,共4页
为了更好地描述地面监测站对天空中卫星的监测情况,首先建立了椭圆形模型来描述地面监测站的覆盖区域,后来根据飞船轨道的调整逐渐近似为圆形轨道模型。通过对模型的求解,计算出了实现全程监控所需要的测站数量。通过编写MATLAB程序,实... 为了更好地描述地面监测站对天空中卫星的监测情况,首先建立了椭圆形模型来描述地面监测站的覆盖区域,后来根据飞船轨道的调整逐渐近似为圆形轨道模型。通过对模型的求解,计算出了实现全程监控所需要的测站数量。通过编写MATLAB程序,实现了测控站点在飞船运动时的覆盖区域的动态仿真,验证了测控站点与飞船轨道在同一平面内的情况下的分布是合理的。 展开更多
关键词 椭圆形模型 圆形轨道 全程监控 MATLAB 动态仿真
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Numerical Simulation of Nonlinear Wave Force on a Quasi-ellipse Caisson 被引量:4
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作者 YongxueWang Xiaozhong Ren GuoyuWang 《Journal of Marine Science and Application》 2011年第3期265-271,共7页
A three dimensional numerical model of nonlinear wave action on a quasi-ellipse caisson in a time domain was developed in this paper. Navier-Stokes equations were solved by the finite difference method, and the volume... A three dimensional numerical model of nonlinear wave action on a quasi-ellipse caisson in a time domain was developed in this paper. Navier-Stokes equations were solved by the finite difference method, and the volume of fluid (VOF) method was employed to trace the free surface. The partial cell method was used to deal with the irregular boundary typical of this type of problem during first-time wave interaction with the structure, and a satisfactory result was obtained. The numerical model was verified and used to investigate the effects of the relative wave height H/d, relative caisson width kD, and relative length-width ratio B/D on the wave forces of the quasi-ellipse caisson. It was shown that the relative wave height H/d has a significant effect on the wave forces of the caisson. Compared with the non-dimensional inline wave force, the relative length-width ratio BID was shown to have significant influence on the non-dimensional transverse wave force. 展开更多
关键词 quasi-ellipse caisson wave force VOF method partial cell method
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Modeling and prediction of daily gas concentration variation at a mining face based on the elliptic orbit model: A case study 被引量:1
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作者 Yang Zongchang Zhou Shaowu 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2015年第6期1045-1052,共8页
Monitoring and analysis of daily gas concentrations at a mining face is a vital task on safety production and security management in the coal-mining industry. This study addresses modeling and prediction of daily gas ... Monitoring and analysis of daily gas concentrations at a mining face is a vital task on safety production and security management in the coal-mining industry. This study addresses modeling and prediction of daily gas concentration variations based on the elliptic orbit model. The model describes the hourly variation in daily gas concentration by mapping its time-series into the polar coordinates to create its elliptic orbit trace for further analysis. Experiments show workability of the proposed method that daily gas concentration variation at a mining face of one coal mine in China is well described by the elliptic orbit model. Result analysis and performance comparison of the proposed elliptic orbit model with the classical AR model on the same prediction tasks indicate potentiality of the proposed elliptic orbit model,which presents a vivid approach for modeling and forecasting daily gas concentration variations in an intuitive and concise way. 展开更多
关键词 Mining faceGas concentration variationElliptic orbit modelEvaluationPrediction
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多相主动轮廓模型的眼底图像杯盘分割 被引量:9
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作者 郑姗 范慧杰 +1 位作者 唐延东 王琰 《中国图象图形学报》 CSCD 北大核心 2014年第11期1604-1612,共9页
目的视盘及视杯的检测对于分析眼底图像和视网膜视神经疾病计算机辅助诊断来说十分重要,利用医学眼底图像中视盘和视杯呈现椭圆形状这一特征,提出了椭圆约束下的多相主动轮廓模型,实现视盘视杯的同时精确分割。方法该算法根据视盘视杯... 目的视盘及视杯的检测对于分析眼底图像和视网膜视神经疾病计算机辅助诊断来说十分重要,利用医学眼底图像中视盘和视杯呈现椭圆形状这一特征,提出了椭圆约束下的多相主动轮廓模型,实现视盘视杯的同时精确分割。方法该算法根据视盘视杯在灰度图像中具有不同的区域亮度,建立多相主动轮廓模型,然后将椭圆形约束内嵌于该模型中。通过对该模型的能量泛函进行求解,得到椭圆参数的演化方程。分割时首先设定两条椭圆形初始曲线,根据演化方程,驱动曲线分别向视盘和视杯方向进行移动。当轮廓线到达视盘、视杯边缘时,曲线停止演化。结果在不同医学眼底图像中对算法进行验证,对算法抗噪性、不同初始曲线选取等进行了实验,并与多种算法进行了对比。实验结果表明,本文模型能够同时分割出视盘及视杯,与其他模型的分割结果相比,本文算法的分割结果更加准确。结论本文算法可以精确分割医学眼底图像中的视盘和视杯,该算法不需要预处理,具有较强的鲁棒性和抗噪性。 展开更多
关键词 眼底图像 杯盘分割 C-V模型 椭圆形约束多相主动轮廓模型 多相水平集函数
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煤层瓦斯流动方程研究及应用 被引量:8
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作者 吴立云 王飞 杨玉中 《采矿与安全工程学报》 EI CSCD 北大核心 2016年第5期951-956,共6页
瓦斯流动方程能够很好地揭示煤层中瓦斯流动的规律,而瓦斯流动规律对瓦斯灾害防治至关重要。运用理论分析对煤层中瓦斯流动模型和流动方程进行了分析与研究。深部岩体的稳定存在状态是球体,而浅部岩体的稳定存在状态为椭球体。在此基础... 瓦斯流动方程能够很好地揭示煤层中瓦斯流动的规律,而瓦斯流动规律对瓦斯灾害防治至关重要。运用理论分析对煤层中瓦斯流动模型和流动方程进行了分析与研究。深部岩体的稳定存在状态是球体,而浅部岩体的稳定存在状态为椭球体。在此基础上,构建了瓦斯流动的椭圆形模型,推导出了二维瓦斯流动方程和三维瓦斯流动方程,并利用建立的瓦斯流动方程解释了煤与瓦斯突出的过程,分析并解释了防突规定中石门揭煤保护岩柱2 m和5 m的理论依据,并将该理论应用于涟邵牛马司矿石门揭煤抽放钻孔的布置设计中,取得了很好的效果。 展开更多
关键词 瓦斯流动方程 椭球体 椭圆形模型 煤与瓦斯突出
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The effect of Lorentz-like force on collective flows of K+in Au+Au collisions at 1.5 Ge V/nucleon 被引量:3
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作者 YuShan Du YongJia Wang +1 位作者 QingFeng Li Ling Liu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2018年第6期24-29,共6页
Producing kaon mesons in heavy-ion collisions at beam energies below their threshold energy is an important way to investigate the properties of dense nuclear matter. In this study, based on the newly updated version ... Producing kaon mesons in heavy-ion collisions at beam energies below their threshold energy is an important way to investigate the properties of dense nuclear matter. In this study, based on the newly updated version of the ultrarelativistic quantum molecular dynamics model, we introduce the kaon-nucleon(KN) potential, including both the scalar and vector(also dubbed Lorentz-like)aspects. We revisit the influence of the KN potential on the collective flow of K+mesons produced in Au+Au collisions at Elab= 1.5 Ge V/nucleon and find that the contribution of the newly included Lorentz-like force is very important, particulary for describing the directed flow of K+. Finally, the corresponding Kao S data of both directed and elliptic flows can be simultaneously reproduced well. 展开更多
关键词 kaon flow heavy-ion collision transport model kaon-nucleon potential
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The Study of “Coulomb Asymmetry” in an Elliptically Polarized Laser Field
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作者 Kai-Yun Huang Yu Hou +2 位作者 Yu-Hua Zhu Hui-Jing Yang Xi-Dong Yang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2018年第10期465-469,共5页
Due to the effect of Coulomb potential, the angular distribution of electron ionized in an elliptically polarized field presents an asymmetric structure, which is called "Coulomb asymmetry". In this paper, w... Due to the effect of Coulomb potential, the angular distribution of electron ionized in an elliptically polarized field presents an asymmetric structure, which is called "Coulomb asymmetry". In this paper, we study how to modulate the asymmetric degree of the electron angular distribution by using a semi-classical simplified tunneling model. It is found that the asymmetric structure is easily affected by three parameters: the ionization potential, the laser ellipticity,and the laser wavelength. However, the laser intensity has little effect on the asymmetric structure. To explain these phenomena we have derived an analytical formula, which clearly demonstrates the relationship between the asymmetric degree and these parameters. Moreover, we find that in elliptically polarized laser field only those electrons that are released in a certain narrow window of initial field phase are greatly effected by the Coulomb potential and play the key role in the formation of asymmetric structure. This study provides some reference values in the development of attoclock technique, which can be used to probe the tunneling process. 展开更多
关键词 Coulomb asymmetry semiclassical model Coulomb correction TUNNELING
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