Effects of irregUlar topography on ground motion for incident P, SV and the propagation of Rayleigh waves are studied by combining finite element method with modified transmitting boundary. TheoretiCal models include ...Effects of irregUlar topography on ground motion for incident P, SV and the propagation of Rayleigh waves are studied by combining finite element method with modified transmitting boundary. TheoretiCal models include isolated protrUding topography and similar adjacent Protruding topography. The concluaion drawn from thisstudy is that the effects Of isolated protruding topography are remarkably larger for Rayleigh wave propagation than for P and SV they waves; Considering adjacent irregUlar toography ground motion is amplified, the duration of ground motion becomes longer and the speCtral ratios exhibit narrowband peaks Considering adjacent irregular topography and Rayleigh wave Propagation, the theoretical results wb more approach the results obtained in practice.展开更多
Through a higher-order boundary element method based on NURBS （Non-uniform Rational B-splines）, the calculation of second-order low-frequency forces and slow drift motions is conducted for floating bodies. In the fl...Through a higher-order boundary element method based on NURBS （Non-uniform Rational B-splines）, the calculation of second-order low-frequency forces and slow drift motions is conducted for floating bodies. In the floating body＇s inner domain, an auxiliary equation is obtained by applying a Green function which satisfies the solid surface condition. Then, the auxiliary equation and the velocity potential equation are combined in the fluid domain to remove the solid angle coefficient and the singularity of the double layer potentials in the integral equation. Thus, a new velocity potential integral equation is obtained. The new equation is extended to the inner domain to reheve the irregular frequency effects; on the basis of the order analysis, the comparison is made about the contribution of all integral terms with the result in the second-order tow-frequency problem; the higher-order boundary element method based on NURBS is apphed to calculate the geometric position and velocity potentials; the slow drift motions are calculated by the spectrum analysis method. Removing the solid angle coefficient can apply NURBS technology to the hydrodynamic calculation of floating bodies with complex surfaces, and the extended boundary integral method can reduce the irregular frequency effects. Order analysis shows that free surface integral can be neglected, and the numerical results can also prove the correctness of order analysis. The results of second-order low-frequency forces and slow drift motions and the comparison with the results from references show that the application of the NURBS technology to the second-order low-frequency problem is of high efficiency and credible results.展开更多
Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combinat...Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combination of a primary circle and a secondary circle. An inverse Magnus force originating from the spin of the irregular grain gives rise to the primary circle. Radial confinement resulting from the electrostatic force and the ion drag force, together with inverse Magnus force, plays an important role in the formation of the secondary circle. In addition, the cyclotron radius is seen to change periodically during the cycloid motion. Force analysis and comparison experiments have shown that the cycloid motions are distinctive features of an irregular grain immersed in a plasma.展开更多
The nonlinear response of structures is usually evaluated by considering two accelerograms acting simultaneously along the orthogonal directions. In this study, the infl uence of the earthquake direction on the seismi...The nonlinear response of structures is usually evaluated by considering two accelerograms acting simultaneously along the orthogonal directions. In this study, the infl uence of the earthquake direction on the seismic response of building structures is examined. Three multi-story RC buildings, representing a very common structural typology in Italy, are used as case studies for the evaluation. They are, respectively, a rectangular plan shape, an L plan shape and a rectangular plan shape with courtyard buildings. Nonlinear static and dynamic analyses are performed by considering different seismic levels, characterized by peak ground acceleration on stiff soil equal to 0.35 g, 0.25 g and 0.15 g. Nonlinear dynamic analyses are carried out by considering twelve different earthquake directions, and rotating the direction of both the orthogonal components by 30° for each analysis(from 0° to 330°). The survey is carried out on the L plan shape structure. The results show that the angle of the seismic input motion signifi cantly infl uences the response of RC structures; the critical seismic angle, i.e., the incidence angle that produces the maximum demand, provides an increase of up to 37% in terms of both roof displacements and plastic hinge rotations.展开更多
针对由于目标频繁遮挡、不规则运动导致的外观特征不可靠和运动特征难以获取的问题,提出一种基于膨胀交并比区域(dilatation intersection over union,DIOU)匹配和自适应轨迹管理策略的多目标跟踪算法。DIOU模块通过膨胀匹配区域,提升...针对由于目标频繁遮挡、不规则运动导致的外观特征不可靠和运动特征难以获取的问题,提出一种基于膨胀交并比区域(dilatation intersection over union,DIOU)匹配和自适应轨迹管理策略的多目标跟踪算法。DIOU模块通过膨胀匹配区域,提升轨迹级联匹配的精度。自适应轨迹管理策略利用目标检测置信度动态调整轨迹生命周期,显著减少了异常跟踪和身份跳变。在公开数据集MOT17、MOT20和DanceTrack上进行了验证与测试,其在测试集上的高阶跟踪精度平均提升了2.4%,实验结果证明了所提方法的有效性。展开更多
文摘Effects of irregUlar topography on ground motion for incident P, SV and the propagation of Rayleigh waves are studied by combining finite element method with modified transmitting boundary. TheoretiCal models include isolated protrUding topography and similar adjacent Protruding topography. The concluaion drawn from thisstudy is that the effects Of isolated protruding topography are remarkably larger for Rayleigh wave propagation than for P and SV they waves; Considering adjacent irregUlar toography ground motion is amplified, the duration of ground motion becomes longer and the speCtral ratios exhibit narrowband peaks Considering adjacent irregular topography and Rayleigh wave Propagation, the theoretical results wb more approach the results obtained in practice.
文摘Through a higher-order boundary element method based on NURBS （Non-uniform Rational B-splines）, the calculation of second-order low-frequency forces and slow drift motions is conducted for floating bodies. In the floating body＇s inner domain, an auxiliary equation is obtained by applying a Green function which satisfies the solid surface condition. Then, the auxiliary equation and the velocity potential equation are combined in the fluid domain to remove the solid angle coefficient and the singularity of the double layer potentials in the integral equation. Thus, a new velocity potential integral equation is obtained. The new equation is extended to the inner domain to reheve the irregular frequency effects; on the basis of the order analysis, the comparison is made about the contribution of all integral terms with the result in the second-order tow-frequency problem; the higher-order boundary element method based on NURBS is apphed to calculate the geometric position and velocity potentials; the slow drift motions are calculated by the spectrum analysis method. Removing the solid angle coefficient can apply NURBS technology to the hydrodynamic calculation of floating bodies with complex surfaces, and the extended boundary integral method can reduce the irregular frequency effects. Order analysis shows that free surface integral can be neglected, and the numerical results can also prove the correctness of order analysis. The results of second-order low-frequency forces and slow drift motions and the comparison with the results from references show that the application of the NURBS technology to the second-order low-frequency problem is of high efficiency and credible results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11205044 and 11405042)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2011201006 and A2012201015)+2 种基金the Research Foundation of Education Bureau of Hebei Province,China(Grant No.Y2012009)the Program for Young Principal Investigators of Hebei Provincethe Midwest Universities Comprehensive Strength Promotion Project
文摘Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combination of a primary circle and a secondary circle. An inverse Magnus force originating from the spin of the irregular grain gives rise to the primary circle. Radial confinement resulting from the electrostatic force and the ion drag force, together with inverse Magnus force, plays an important role in the formation of the secondary circle. In addition, the cyclotron radius is seen to change periodically during the cycloid motion. Force analysis and comparison experiments have shown that the cycloid motions are distinctive features of an irregular grain immersed in a plasma.
基金partially funded by Italian Department of Civil Protection in the frame of the National ReLUIS Project 2005-2008 line 2-Theme 2
文摘The nonlinear response of structures is usually evaluated by considering two accelerograms acting simultaneously along the orthogonal directions. In this study, the infl uence of the earthquake direction on the seismic response of building structures is examined. Three multi-story RC buildings, representing a very common structural typology in Italy, are used as case studies for the evaluation. They are, respectively, a rectangular plan shape, an L plan shape and a rectangular plan shape with courtyard buildings. Nonlinear static and dynamic analyses are performed by considering different seismic levels, characterized by peak ground acceleration on stiff soil equal to 0.35 g, 0.25 g and 0.15 g. Nonlinear dynamic analyses are carried out by considering twelve different earthquake directions, and rotating the direction of both the orthogonal components by 30° for each analysis(from 0° to 330°). The survey is carried out on the L plan shape structure. The results show that the angle of the seismic input motion signifi cantly infl uences the response of RC structures; the critical seismic angle, i.e., the incidence angle that produces the maximum demand, provides an increase of up to 37% in terms of both roof displacements and plastic hinge rotations.
文摘针对由于目标频繁遮挡、不规则运动导致的外观特征不可靠和运动特征难以获取的问题,提出一种基于膨胀交并比区域(dilatation intersection over union,DIOU)匹配和自适应轨迹管理策略的多目标跟踪算法。DIOU模块通过膨胀匹配区域,提升轨迹级联匹配的精度。自适应轨迹管理策略利用目标检测置信度动态调整轨迹生命周期,显著减少了异常跟踪和身份跳变。在公开数据集MOT17、MOT20和DanceTrack上进行了验证与测试,其在测试集上的高阶跟踪精度平均提升了2.4%,实验结果证明了所提方法的有效性。
