Background The interaction of gas and liquid can produce many interesting phenomena,such as bubbles rising from the bottom of the liquid.The simulation of two-phase fluids is a challenging topic in computer graphics.T...Background The interaction of gas and liquid can produce many interesting phenomena,such as bubbles rising from the bottom of the liquid.The simulation of two-phase fluids is a challenging topic in computer graphics.To animate the interaction of a gas and liquid,MultiFLIP samples the two types of particles,and a Euler grid is used to track the interface of the liquid and gas.However,MultiFLIP uses the fluid implicit particle(FLIP)method to interpolate the velocities of particles into the Euler grid,which suffer from additional noise and instability.Methods To solve the problem caused by fluid implicit particles(FLIP),we present a novel velocity transport technique for two individual particles based on the affine particle-in-cell(APIC)method.First,we design a weighed coupling method for interpolating the velocities of liquid and gas particles to the Euler grid such that we can apply the APIC method to the simulation of a two-phase fluid.Second,we introduce a narrowband method to our system because MultiFLIP is a time-consuming approach owing to the large number of particles.Results Experiments show that our method is well integrated with the APIC method and provides a visually credible two-phase fluid animation.Conclusions The proposed method can successfully handle the simulation of a two phase fluid.展开更多
A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansi...A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansion and low efficiency when applied to an AND.This then leads to errors of interval power flow data sources in the cyber physical system(CPS)of an ADN.In order to improve the accuracy of interval power flow data in the CPS of an ADN,an affine power flow method of an ADN for restraining interval expansion is proposed.Aiming at the expansion of interval results caused by the approximation error of non-affine operations in an affine power flow method,the approximation method of the new noise source coefficient is improved,and it is proved that the improved method is superior to the classical method in restraining interval expansion.To overcome the decrease of computational efficiency caused by new noise sources,a novel merging method of new noise sources in an iterative process is designed.Simulation tests are conducted on an IEEE 33-bus,PG&E 69-bus and an actual 1180-bus system,which proves the validity of the proposed affine power flow method and its advantages in terms of computational efficiency and restraining interval expansion.展开更多
由于传统的梯度光流法当运动不连续时运动场估计值与真实值有较大偏差,因而不能直接应用于稳像系统中。引入金字塔多分辨率分层技术对传统的梯度光流法进行改进。首先,在视频序列中选定细节丰富的区域作为计算区域;其次,利用结合金字塔...由于传统的梯度光流法当运动不连续时运动场估计值与真实值有较大偏差,因而不能直接应用于稳像系统中。引入金字塔多分辨率分层技术对传统的梯度光流法进行改进。首先,在视频序列中选定细节丰富的区域作为计算区域;其次,利用结合金字塔多分辨率分层技术的光流法迭代求解相邻帧间的仿射参数;最后,采用帧间补偿方式,并增加控制累积错误传播的措施,在不丢失过多原有信息基础上,实现了长时间稳像。实验表明:改进的方法能够检测出剧烈的复杂抖动,并能达到旋转精度小于0.09°、平移精度小于0.07个像素,缩放精度小于0.02的高精度估计,且补偿序列平均峰值信噪比值提高了2.36 d B以上。展开更多
基金National High Technology R&D Program of China(2017YFB1002701,M2019YFB1600702)NSFC(62072449)+1 种基金Science and Technology Development Fund,Macao SAR(0018/2019/AKP,0008/2019/AGJ,SKL-IOTSC-2018-2020)University of Macao Grant(MYRG2019-00006-FST).
文摘Background The interaction of gas and liquid can produce many interesting phenomena,such as bubbles rising from the bottom of the liquid.The simulation of two-phase fluids is a challenging topic in computer graphics.To animate the interaction of a gas and liquid,MultiFLIP samples the two types of particles,and a Euler grid is used to track the interface of the liquid and gas.However,MultiFLIP uses the fluid implicit particle(FLIP)method to interpolate the velocities of particles into the Euler grid,which suffer from additional noise and instability.Methods To solve the problem caused by fluid implicit particles(FLIP),we present a novel velocity transport technique for two individual particles based on the affine particle-in-cell(APIC)method.First,we design a weighed coupling method for interpolating the velocities of liquid and gas particles to the Euler grid such that we can apply the APIC method to the simulation of a two-phase fluid.Second,we introduce a narrowband method to our system because MultiFLIP is a time-consuming approach owing to the large number of particles.Results Experiments show that our method is well integrated with the APIC method and provides a visually credible two-phase fluid animation.Conclusions The proposed method can successfully handle the simulation of a two phase fluid.
基金supported by International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52061635104).
文摘A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansion and low efficiency when applied to an AND.This then leads to errors of interval power flow data sources in the cyber physical system(CPS)of an ADN.In order to improve the accuracy of interval power flow data in the CPS of an ADN,an affine power flow method of an ADN for restraining interval expansion is proposed.Aiming at the expansion of interval results caused by the approximation error of non-affine operations in an affine power flow method,the approximation method of the new noise source coefficient is improved,and it is proved that the improved method is superior to the classical method in restraining interval expansion.To overcome the decrease of computational efficiency caused by new noise sources,a novel merging method of new noise sources in an iterative process is designed.Simulation tests are conducted on an IEEE 33-bus,PG&E 69-bus and an actual 1180-bus system,which proves the validity of the proposed affine power flow method and its advantages in terms of computational efficiency and restraining interval expansion.
文摘由于传统的梯度光流法当运动不连续时运动场估计值与真实值有较大偏差,因而不能直接应用于稳像系统中。引入金字塔多分辨率分层技术对传统的梯度光流法进行改进。首先,在视频序列中选定细节丰富的区域作为计算区域;其次,利用结合金字塔多分辨率分层技术的光流法迭代求解相邻帧间的仿射参数;最后,采用帧间补偿方式,并增加控制累积错误传播的措施,在不丢失过多原有信息基础上,实现了长时间稳像。实验表明:改进的方法能够检测出剧烈的复杂抖动,并能达到旋转精度小于0.09°、平移精度小于0.07个像素,缩放精度小于0.02的高精度估计,且补偿序列平均峰值信噪比值提高了2.36 d B以上。
