The contact angle is one of important parameters to simulate droplet spreading and impingement phenomena on the surface. In the most numerical research, it is assumed constant value and it is implemented as boundary c...The contact angle is one of important parameters to simulate droplet spreading and impingement phenomena on the surface. In the most numerical research, it is assumed constant value and it is implemented as boundary condition. However, contact angle is changed according to contact line velocity and time. Hence, for accurate simulation, dynamic contact angle which has various values as time elapsed is adopted. In the present study, the numerical analysis is performed on the droplet spreading phenomena considering dynamic contact angle function which is obtained from single droplet spreading experiment on the flat and bare surface. The CIP （cubic interpolated pseudo-particle） method by Yabe is used for analysis of interface between liquid and gas phases. The numerical results considering contact angle function which newly modeled as time and contact angle are compared with numerical results considering Hoffman＇s function and experimental data for range of Weber number which are 4.427 and 11.334. In contrast of numerical result considering Hoffman＇s function, the numerical result shows good agreement with experimental data as time elapsed in contact angle evolution, deformation of droplet spreading radius and height. Indeed, overall, the results display the increasing maximum spreading radius and the decreasing height as Weber numbers increased.展开更多
We investigate the light deflection in the weak field approximation from the accelerating charged AdS black hole.For this purpose,we apply the Gauss–Bonnet theorem to calculate the light deflection in the weak field ...We investigate the light deflection in the weak field approximation from the accelerating charged AdS black hole.For this purpose,we apply the Gauss–Bonnet theorem to calculate the light deflection in the weak field area and use the Gibbons–Werner approach to analyze the optical geometry of the accelerating charged AdS black hole in the non-magnetic plasma absence/presence of a non-magnetic medium.We also represent the graphical behavior of the light deflection angle w.r.t.the impact parameter.We also compute the light deflection angle using Keeton and Petters approximations under the impact of accelerating charged AdS black hole geometry.Furthermore,by using the ray-tracing approach,we determine the shadow in the nonmagnetic plasma presence and also demonstrate that graphical shadow has an impact on the gauge potential,non-magnetic plasma frequencies and charge.展开更多
The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resista...The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.展开更多
针对当前无人机航空影像阴影角度校正方法存在校正精度和召回率较低,导致无人机航空影像信息的利用价值降低的问题,本文提出了立体测绘型双翼无人机航空影像阴影角度校正方法。以无人机检测到的影像阴影边缘为基础点,计算航空影像色彩...针对当前无人机航空影像阴影角度校正方法存在校正精度和召回率较低,导致无人机航空影像信息的利用价值降低的问题,本文提出了立体测绘型双翼无人机航空影像阴影角度校正方法。以无人机检测到的影像阴影边缘为基础点,计算航空影像色彩空间的色调差参照值和阴影区域的色调分量,根据阴影区域的纹理特征,去除无人机航空影像的阴影;考虑双翼无人机航行的空间位置,将无人机航空影像的RGB(red green blue)色彩空间转换为HSV(hue saturation value)色彩空间,通过无人机航空影像阴影角度的平滑处理,控制无人机航空影像阴影角度;利用灰度线性变化算法与自适应阈值计算法,对无人机航空影像阴影角度进行校正处理,实现对无人机航空影像阴影角度的精确校正,完成无人机航空影像阴影角度的控制与校正算法设计。结果表明:采用本文方法在Txcet-M数据集和Nfteg-H数据集进行航空影像测试,校正精度最高可达99%,召回率最高为98%;在GIswu-K数据集进行测试,得到的校正精度和召回率均在75%以上。这说明利用本文方法可以较好地优化航空影像阴影角度校正性能。展开更多
文摘The contact angle is one of important parameters to simulate droplet spreading and impingement phenomena on the surface. In the most numerical research, it is assumed constant value and it is implemented as boundary condition. However, contact angle is changed according to contact line velocity and time. Hence, for accurate simulation, dynamic contact angle which has various values as time elapsed is adopted. In the present study, the numerical analysis is performed on the droplet spreading phenomena considering dynamic contact angle function which is obtained from single droplet spreading experiment on the flat and bare surface. The CIP （cubic interpolated pseudo-particle） method by Yabe is used for analysis of interface between liquid and gas phases. The numerical results considering contact angle function which newly modeled as time and contact angle are compared with numerical results considering Hoffman＇s function and experimental data for range of Weber number which are 4.427 and 11.334. In contrast of numerical result considering Hoffman＇s function, the numerical result shows good agreement with experimental data as time elapsed in contact angle evolution, deformation of droplet spreading radius and height. Indeed, overall, the results display the increasing maximum spreading radius and the decreasing height as Weber numbers increased.
基金funded by the National Natural Science Foundation of China 11975145。
文摘We investigate the light deflection in the weak field approximation from the accelerating charged AdS black hole.For this purpose,we apply the Gauss–Bonnet theorem to calculate the light deflection in the weak field area and use the Gibbons–Werner approach to analyze the optical geometry of the accelerating charged AdS black hole in the non-magnetic plasma absence/presence of a non-magnetic medium.We also represent the graphical behavior of the light deflection angle w.r.t.the impact parameter.We also compute the light deflection angle using Keeton and Petters approximations under the impact of accelerating charged AdS black hole geometry.Furthermore,by using the ray-tracing approach,we determine the shadow in the nonmagnetic plasma presence and also demonstrate that graphical shadow has an impact on the gauge potential,non-magnetic plasma frequencies and charge.
基金the organizations that have funded this project:the Natural Sciences and Engineering Research Council of Canada(Grant No.498020-16)Hydro-Quebec(NC-525700)Mitacs Accelerate Program(Grant Ref.IT10008)
文摘The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.
文摘针对当前无人机航空影像阴影角度校正方法存在校正精度和召回率较低,导致无人机航空影像信息的利用价值降低的问题,本文提出了立体测绘型双翼无人机航空影像阴影角度校正方法。以无人机检测到的影像阴影边缘为基础点,计算航空影像色彩空间的色调差参照值和阴影区域的色调分量,根据阴影区域的纹理特征,去除无人机航空影像的阴影;考虑双翼无人机航行的空间位置,将无人机航空影像的RGB(red green blue)色彩空间转换为HSV(hue saturation value)色彩空间,通过无人机航空影像阴影角度的平滑处理,控制无人机航空影像阴影角度;利用灰度线性变化算法与自适应阈值计算法,对无人机航空影像阴影角度进行校正处理,实现对无人机航空影像阴影角度的精确校正,完成无人机航空影像阴影角度的控制与校正算法设计。结果表明:采用本文方法在Txcet-M数据集和Nfteg-H数据集进行航空影像测试,校正精度最高可达99%,召回率最高为98%;在GIswu-K数据集进行测试,得到的校正精度和召回率均在75%以上。这说明利用本文方法可以较好地优化航空影像阴影角度校正性能。
