六自由度(Six Degrees of Freedom,6DoF)视频允许用户从全方位、任意视角身临其境体验场景,是下一代沉浸式视频产业的发展方向.部分自由度受限的窗口6DoF视频近年来成为研究热点,本文提出面向窗口6DoF合成视频的主观数据库和客观质量评...六自由度(Six Degrees of Freedom,6DoF)视频允许用户从全方位、任意视角身临其境体验场景,是下一代沉浸式视频产业的发展方向.部分自由度受限的窗口6DoF视频近年来成为研究热点,本文提出面向窗口6DoF合成视频的主观数据库和客观质量评价方法.在主观数据库方面,构建了包含两种交互路径不适性失真、四种绘制失真和四种压缩失真的窗口6DoF合成视频主观质量数据库Windowed-6DoF,并开展主观质量测试及结果分析.在客观质量评价方法方面,设计了一种融合多层特征的窗口6DoF合成视频无参考客观质量评价方法.采用切比雪夫矩提取视频时域切片上的底层形状特征;采用Resnet-50网络提取视频的时域、空域高层语义特征并进行降维处理;最后采用随机森林将底层形状特征和高层语义特征进行融合,且训练得到窗口6DoF合成视频的客观质量评价模型.在提出的数据库Windowed-6DoF和公共数据库IRCCyN/IVC DIBR的测试结果表明,本文提出的客观质量评价方法预测分数的皮尔逊线性相关系数分别达到0.9327和0.8581,与主观评价分数具有较好的一致性.展开更多
Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteris...Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation accuracy.However,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for NCS.The TdisULAs structure generally consists of three ULAs,which are appropriately placed.The proposed antenna array approach fully exploits the non-circular characteristics of the sources.Given the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors.Advantageously,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form expressions.Moreover,the proposed array also produces a filled resulting co-array.Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.展开更多
A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were c...A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF.展开更多
为了确定弹塑性单自由度(single degree of freedom,SDOF)体系地震输入能,分析了中美场地土剪切波速转换关系,将从美国PEER地震记录数据库选取的220条强震记录按中国场地土类型进行分类,基于能量平衡原理,采用归一化方法,建议了一种基...为了确定弹塑性单自由度(single degree of freedom,SDOF)体系地震输入能,分析了中美场地土剪切波速转换关系,将从美国PEER地震记录数据库选取的220条强震记录按中国场地土类型进行分类,基于能量平衡原理,采用归一化方法,建议了一种基于复合强度指标的弹性SDOF体系三段式等效速度谱.分析了5类场地土条件下SDOF体系系统参数对地震输入等效速度谱的影响.研究结果表明:刚度折减系数对等效速度谱无明显影响;延性系数和阻尼比增大均对等效速度谱峰值和下降段衰减速度有削弱作用.综合考虑各类影响因素,通过参数多次拟合,得出弹性SDOF体系归一化等效速度谱峰值段及下降段修正系数,提出了一种适用于我国场地土类型、可直接供设计使用的弹塑性SDOF体系归一化等效速度谱确定方法,并验证了其有效性.展开更多
合理的地震动设计输入能量谱是推动能量法走向工程应用的重要基础。选取3种场地条件下259条地震动记录,针对弹性单自由度体系(Single Degree of Freedom)的输入能量进行研究。采用归一化方法,将输入能量谱表征为输入能量谱峰值(Elmax)...合理的地震动设计输入能量谱是推动能量法走向工程应用的重要基础。选取3种场地条件下259条地震动记录,针对弹性单自由度体系(Single Degree of Freedom)的输入能量进行研究。采用归一化方法,将输入能量谱表征为输入能量谱峰值(Elmax)与归一化输入能量谱的乘积;根据相关性分析,提出输入能量谱峰值的影响参数及估算方法;基于3种场地条件下归一化输入能量谱特征,通过拟合建立三段式归一化输入能量谱,提出阻尼比为0.05时,弹性SDOF体系设计输入能量谱的计算方法,并验证了该方法的可行性。展开更多
文摘六自由度(Six Degrees of Freedom,6DoF)视频允许用户从全方位、任意视角身临其境体验场景,是下一代沉浸式视频产业的发展方向.部分自由度受限的窗口6DoF视频近年来成为研究热点,本文提出面向窗口6DoF合成视频的主观数据库和客观质量评价方法.在主观数据库方面,构建了包含两种交互路径不适性失真、四种绘制失真和四种压缩失真的窗口6DoF合成视频主观质量数据库Windowed-6DoF,并开展主观质量测试及结果分析.在客观质量评价方法方面,设计了一种融合多层特征的窗口6DoF合成视频无参考客观质量评价方法.采用切比雪夫矩提取视频时域切片上的底层形状特征;采用Resnet-50网络提取视频的时域、空域高层语义特征并进行降维处理;最后采用随机森林将底层形状特征和高层语义特征进行融合,且训练得到窗口6DoF合成视频的客观质量评价模型.在提出的数据库Windowed-6DoF和公共数据库IRCCyN/IVC DIBR的测试结果表明,本文提出的客观质量评价方法预测分数的皮尔逊线性相关系数分别达到0.9327和0.8581,与主观评价分数具有较好的一致性.
基金supported by the National Natural Science Foundation of China(62031017,61971221)the Fundamental Research Funds for the Central Universities of China(NP2020104)。
文摘Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation accuracy.However,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for NCS.The TdisULAs structure generally consists of three ULAs,which are appropriately placed.The proposed antenna array approach fully exploits the non-circular characteristics of the sources.Given the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors.Advantageously,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form expressions.Moreover,the proposed array also produces a filled resulting co-array.Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.
基金Project(51221462)supported by the National Natural Science Foundation of China for Innovative Research GroupProject(20120095110001)supported by the Doctoral Fund of Ministry of Education of China+1 种基金Project supported by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,ChinaProject(CXJJ201303)supported by the Innovation Foundation of Xuyi Research and Development Center of Mining Equipment and Materials,China University of Mining and Technology,China
文摘A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF.
文摘为了确定弹塑性单自由度(single degree of freedom,SDOF)体系地震输入能,分析了中美场地土剪切波速转换关系,将从美国PEER地震记录数据库选取的220条强震记录按中国场地土类型进行分类,基于能量平衡原理,采用归一化方法,建议了一种基于复合强度指标的弹性SDOF体系三段式等效速度谱.分析了5类场地土条件下SDOF体系系统参数对地震输入等效速度谱的影响.研究结果表明:刚度折减系数对等效速度谱无明显影响;延性系数和阻尼比增大均对等效速度谱峰值和下降段衰减速度有削弱作用.综合考虑各类影响因素,通过参数多次拟合,得出弹性SDOF体系归一化等效速度谱峰值段及下降段修正系数,提出了一种适用于我国场地土类型、可直接供设计使用的弹塑性SDOF体系归一化等效速度谱确定方法,并验证了其有效性.
文摘合理的地震动设计输入能量谱是推动能量法走向工程应用的重要基础。选取3种场地条件下259条地震动记录,针对弹性单自由度体系(Single Degree of Freedom)的输入能量进行研究。采用归一化方法,将输入能量谱表征为输入能量谱峰值(Elmax)与归一化输入能量谱的乘积;根据相关性分析,提出输入能量谱峰值的影响参数及估算方法;基于3种场地条件下归一化输入能量谱特征,通过拟合建立三段式归一化输入能量谱,提出阻尼比为0.05时,弹性SDOF体系设计输入能量谱的计算方法,并验证了该方法的可行性。
