The mechanisms of seismically-induced liquefaction of granular soils underhigh confining stresses are still not fully understood.Evaluation of these mechanisms is generallybased on extrapolation of observed behavior a...The mechanisms of seismically-induced liquefaction of granular soils underhigh confining stresses are still not fully understood.Evaluation of these mechanisms is generallybased on extrapolation of observed behavior at shallow depths.Three centrifuge model tests wereconducted at RPI's experimental facility to investigate the effects of confining stresses on thedynamic response of a deep horizontal deposit of saturated sand.Liquefaction was observed at highconfining stresses in each of the tests.A system identification procedure was used to estimate theassociated shear strain and stress time histories.These histories revealed a response marked byshear strength degradation and dilative patterns.The recorded accelerations and pore pressures wereemployed to generate visual animations of the models.These visualizations revealed a liquefactionfront traveling downward and leading to large shear strains and isolation of upper soil layers.展开更多
While it is very reasonable to use a multigraph consisting of multiple edges between vertices to represent various relationships, the multigraph has not drawn much attention in research. To visualize such a multigraph...While it is very reasonable to use a multigraph consisting of multiple edges between vertices to represent various relationships, the multigraph has not drawn much attention in research. To visualize such a multigraph, a clear layout representing a global structure is of great importance, and interactive visual analysis which allows the multiple edges to be adjusted in appropriate ways for detailed presentation is also essential. A novel interactive two-phase approach to visualizing and exploring multigraph is proposed. The approach consists of two phases： the first phase improves the previous popular works on force-directed methods to produce a brief drawing for the aggregation graph of the input multigraph, while the second phase proposes two interactive strategies, the magnifier model and the thematic-oriented subgraph model. The former highlights the internal details of an aggregation edge which is selected interactively by user, and draws the details in a magnifying view by cubic Bezier curves; the latter highlights only the thematic subgraph consisting of the selected multiple edges that the user concerns. The efficiency of the proposed approach is demonstrated with a real-world multigraph dataset and how it is used effectively is discussed for various potential applications.展开更多
Accurate characterization and visualization of the complex inner structure and stress distribution of rocks are of vital significance to solve a variety of underground engineering problems. In this paper, we incorpora...Accurate characterization and visualization of the complex inner structure and stress distribution of rocks are of vital significance to solve a variety of underground engineering problems. In this paper, we incorporate several advanced technologies, such as CT scan, three-dimensional(3D) reconstruction, and 3D printing, to produce a physical model representing the natural coal rock that inherently contains complex fractures or joints. We employ 3D frozen stress and photoelastic technologies to characterize and visualize the stress distribution within the fractured rock under uniaxial compression. The 3D printed model presents the fracture structures identical to those of the natural prototype. The mechanical properties of the printed model,including uniaxial compression strength, elastic modulus,and Poisson's ratio, are testified to be similar to those of the prototype coal rock. The frozen stress and photoelastic tests show that the location of stress concentration and the stress gradient around the discontinuous fractures are in good agreement with the numerical predictions of the real coalsample. The proposed method appears to be capable of visually quantifying the influences of discontinuous,irregular fractures on the strength, deformation, and stress concentration of coal rock. The method of incorporating3 D printing and frozen stress technologies shows a promising way to quantify and visualize the complex fracture structures and their influences on 3D stress distribution of underground rocks, which can also be used to verify numerical simulations.展开更多
为了清晰梳理并准确把握国际“学习者建模”领域的研究热点与脉络,以Web of Science核心期刊数据库2013-2022年间有关“学习者建模”的载文为研究对象,借助CiteSpace等可视化分析软件,对其进行文献计量分析和知识图谱分析。结果表明:“...为了清晰梳理并准确把握国际“学习者建模”领域的研究热点与脉络,以Web of Science核心期刊数据库2013-2022年间有关“学习者建模”的载文为研究对象,借助CiteSpace等可视化分析软件,对其进行文献计量分析和知识图谱分析。结果表明:“学习者建模”研究在过去10年呈现从平稳发展到急剧上升的趋势;美国、澳大利亚和英国在该研究领域起步较早且持续时间较长,中国则在近3年迈开了研究的步伐;IEEE Access是“学习者建模”领域发文量较多的期刊;研究作者、研究机构之间合作偏少;研究热点主要集中在数据训练、智能导师系统、机器学习、人工智能和学习分析等5个方面;过去10年间“学习者建模”研究分为两个阶段,2013-2019年间热点研究为智能导师系统中学习者模型的构建和应用,2019年至今的前沿热点研究是深度学习在“学习者建模”中的应用。在未来研究中可以重点关注以下方面:“学习者建模”领域要加强技术研究和应用研究合作,形成一个良好的合作循环;研究团队互相间要加强合作,要能够跨领域、交叉学科地进行更深一步的交流;继续聚焦新兴技术,将其应用于学习者建模;在大数据和深度学习技术研究不断深入的过程中,要注意数据安全和隐私问题。展开更多
基金This research was supported by the National Science Foundation,Grant No.CMS-984754(Dr.C.Astill program manager)the US Army Engineer Research and Development Center.
文摘The mechanisms of seismically-induced liquefaction of granular soils underhigh confining stresses are still not fully understood.Evaluation of these mechanisms is generallybased on extrapolation of observed behavior at shallow depths.Three centrifuge model tests wereconducted at RPI's experimental facility to investigate the effects of confining stresses on thedynamic response of a deep horizontal deposit of saturated sand.Liquefaction was observed at highconfining stresses in each of the tests.A system identification procedure was used to estimate theassociated shear strain and stress time histories.These histories revealed a response marked byshear strength degradation and dilative patterns.The recorded accelerations and pore pressures wereemployed to generate visual animations of the models.These visualizations revealed a liquefactionfront traveling downward and leading to large shear strains and isolation of upper soil layers.
基金supported by the National Natural Science Fundation of China(61103081)
文摘While it is very reasonable to use a multigraph consisting of multiple edges between vertices to represent various relationships, the multigraph has not drawn much attention in research. To visualize such a multigraph, a clear layout representing a global structure is of great importance, and interactive visual analysis which allows the multiple edges to be adjusted in appropriate ways for detailed presentation is also essential. A novel interactive two-phase approach to visualizing and exploring multigraph is proposed. The approach consists of two phases： the first phase improves the previous popular works on force-directed methods to produce a brief drawing for the aggregation graph of the input multigraph, while the second phase proposes two interactive strategies, the magnifier model and the thematic-oriented subgraph model. The former highlights the internal details of an aggregation edge which is selected interactively by user, and draws the details in a magnifying view by cubic Bezier curves; the latter highlights only the thematic subgraph consisting of the selected multiple edges that the user concerns. The efficiency of the proposed approach is demonstrated with a real-world multigraph dataset and how it is used effectively is discussed for various potential applications.
基金supported by the National Natural Science Foundation for Distinguished Young Scholars of China(51125017)the National Natural Science Foundation of China(51374213)the National Basic Research Program of China(2010CB226804,2011CB201201)
文摘Accurate characterization and visualization of the complex inner structure and stress distribution of rocks are of vital significance to solve a variety of underground engineering problems. In this paper, we incorporate several advanced technologies, such as CT scan, three-dimensional(3D) reconstruction, and 3D printing, to produce a physical model representing the natural coal rock that inherently contains complex fractures or joints. We employ 3D frozen stress and photoelastic technologies to characterize and visualize the stress distribution within the fractured rock under uniaxial compression. The 3D printed model presents the fracture structures identical to those of the natural prototype. The mechanical properties of the printed model,including uniaxial compression strength, elastic modulus,and Poisson's ratio, are testified to be similar to those of the prototype coal rock. The frozen stress and photoelastic tests show that the location of stress concentration and the stress gradient around the discontinuous fractures are in good agreement with the numerical predictions of the real coalsample. The proposed method appears to be capable of visually quantifying the influences of discontinuous,irregular fractures on the strength, deformation, and stress concentration of coal rock. The method of incorporating3 D printing and frozen stress technologies shows a promising way to quantify and visualize the complex fracture structures and their influences on 3D stress distribution of underground rocks, which can also be used to verify numerical simulations.
文摘识别非驾驶行为是提高驾驶安全性的重要手段之一。目前基于骨架序列和图像的融合识别方法具有计算量大和特征融合困难的问题。针对上述问题,本文提出一种基于多尺度骨架图和局部视觉上下文融合的驾驶员行为识别模型(skeleton-image based behavior recognition network,SIBBR-Net)。SIBBR-Net通过基于多尺度图的图卷积网络和基于局部视觉及注意力机制的卷积神经网络,充分提取运动和外观特征,较好地平衡了模型表征能力和计算量间的关系。基于手部运动的特征双向引导学习策略、自适应特征融合模块和静态特征空间上的辅助损失,使运动和外观特征间互相引导更新并实现自适应融合。最终在Drive&Act数据集进行算法测试,SIBBR-Net在动态标签和静态标签条件下的平均正确率分别为61.78%和80.42%,每秒浮点运算次数为25.92G,较最优方法降低了76.96%。
文摘为了清晰梳理并准确把握国际“学习者建模”领域的研究热点与脉络,以Web of Science核心期刊数据库2013-2022年间有关“学习者建模”的载文为研究对象,借助CiteSpace等可视化分析软件,对其进行文献计量分析和知识图谱分析。结果表明:“学习者建模”研究在过去10年呈现从平稳发展到急剧上升的趋势;美国、澳大利亚和英国在该研究领域起步较早且持续时间较长,中国则在近3年迈开了研究的步伐;IEEE Access是“学习者建模”领域发文量较多的期刊;研究作者、研究机构之间合作偏少;研究热点主要集中在数据训练、智能导师系统、机器学习、人工智能和学习分析等5个方面;过去10年间“学习者建模”研究分为两个阶段,2013-2019年间热点研究为智能导师系统中学习者模型的构建和应用,2019年至今的前沿热点研究是深度学习在“学习者建模”中的应用。在未来研究中可以重点关注以下方面:“学习者建模”领域要加强技术研究和应用研究合作,形成一个良好的合作循环;研究团队互相间要加强合作,要能够跨领域、交叉学科地进行更深一步的交流;继续聚焦新兴技术,将其应用于学习者建模;在大数据和深度学习技术研究不断深入的过程中,要注意数据安全和隐私问题。
