Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. Machine learning techniques ar...Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. Machine learning techniques are often involved in such multi-method fusion metrics so that its output would be more consistent with human visual perceptions. On the other hand, the robustness and generalization ability of these multi-method fusion metrics are questioned because of the scarce of images with mean opinion scores. In order to comprehensively validate whether or not the generalization ability of such multi-method fusion IQA metrics are satisfying, we construct a new image database which contains up to 60 reference images. The newly built image database is then used to test the generalization ability of different multi-method fusion IQA metrics. Cross database validation experiment indicates that in our new image database, the performances of all the multi-method fusion IQA metrics have no statistical significant different with some single-method IQA metrics such as FSIM and MAD. In the end, a thorough analysis is given to explain why the performance of multi-method fusion IQA framework drop significantly in cross database validation.展开更多
The Tianshan orogenic belt is a major part of the southern Central Asian Orogenic Belt（CAOB）,extending from west to east for over 2500 km through Uzbekistan,Tajikistan,Kyrgyzstan and Kazakhstan to Xinjiang in NW Chi...The Tianshan orogenic belt is a major part of the southern Central Asian Orogenic Belt（CAOB）,extending from west to east for over 2500 km through Uzbekistan,Tajikistan,Kyrgyzstan and Kazakhstan to Xinjiang in NW China,and contains the record of multi-phase tectonothermal evolution.Till now.展开更多
摆振会降低起落架的使用寿命,影响乘坐舒适性,甚至会引起机体损坏,导致飞机失事。为了抑制起落架摆振,本文采用时滞反馈非线性能量汇(nonlinear energy sink,NES)对起落架摆振进行多目标优化。以某轻型飞机起落架为研究对象,设计了基于...摆振会降低起落架的使用寿命,影响乘坐舒适性,甚至会引起机体损坏,导致飞机失事。为了抑制起落架摆振,本文采用时滞反馈非线性能量汇(nonlinear energy sink,NES)对起落架摆振进行多目标优化。以某轻型飞机起落架为研究对象,设计了基于NES的时滞反馈半主动控制减摆器,并建立了前起落架摆振系统分析动力学方程。通过线性多步法求解出时滞反馈半主动控制摆振系统的特征根,分析了减摆器可控阻尼系数对特征根最大实部的影响。以时滞量为设计变量,将振幅衰减时间和第四周期振幅的线性加权组合确定为目标函数。采用粒子群算法对该优化目标进行全局搜索,得到相应的最优时滞量,并与遗传算法得到的结果进行对比,验证了最优时滞量的可靠性,并在时域内对减摆器的减摆效果进行了验证。结果表明,与无时滞控制系统相比,采用最优时滞反馈的半主动控制系统的前起落架摆振幅值显著降低。展开更多
基金supported by “the Fundamental Research Funds for the Central Universities” No.2018CUCTJ081
文摘Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. Machine learning techniques are often involved in such multi-method fusion metrics so that its output would be more consistent with human visual perceptions. On the other hand, the robustness and generalization ability of these multi-method fusion metrics are questioned because of the scarce of images with mean opinion scores. In order to comprehensively validate whether or not the generalization ability of such multi-method fusion IQA metrics are satisfying, we construct a new image database which contains up to 60 reference images. The newly built image database is then used to test the generalization ability of different multi-method fusion IQA metrics. Cross database validation experiment indicates that in our new image database, the performances of all the multi-method fusion IQA metrics have no statistical significant different with some single-method IQA metrics such as FSIM and MAD. In the end, a thorough analysis is given to explain why the performance of multi-method fusion IQA framework drop significantly in cross database validation.
基金supported by the Major Basic Research Project of the Ministry of Science and Technology of China(Grant No.2014CB448000)National Science Foundation of China(Grant Nos..41473053 and 41573045)a grant of Chinese Ministry of Land and Resources(Grant No.201211074–05)
文摘The Tianshan orogenic belt is a major part of the southern Central Asian Orogenic Belt（CAOB）,extending from west to east for over 2500 km through Uzbekistan,Tajikistan,Kyrgyzstan and Kazakhstan to Xinjiang in NW China,and contains the record of multi-phase tectonothermal evolution.Till now.
文摘摆振会降低起落架的使用寿命,影响乘坐舒适性,甚至会引起机体损坏,导致飞机失事。为了抑制起落架摆振,本文采用时滞反馈非线性能量汇(nonlinear energy sink,NES)对起落架摆振进行多目标优化。以某轻型飞机起落架为研究对象,设计了基于NES的时滞反馈半主动控制减摆器,并建立了前起落架摆振系统分析动力学方程。通过线性多步法求解出时滞反馈半主动控制摆振系统的特征根,分析了减摆器可控阻尼系数对特征根最大实部的影响。以时滞量为设计变量,将振幅衰减时间和第四周期振幅的线性加权组合确定为目标函数。采用粒子群算法对该优化目标进行全局搜索,得到相应的最优时滞量,并与遗传算法得到的结果进行对比,验证了最优时滞量的可靠性,并在时域内对减摆器的减摆效果进行了验证。结果表明,与无时滞控制系统相比,采用最优时滞反馈的半主动控制系统的前起落架摆振幅值显著降低。
