Today in the 21st century, Science and technology (S&T)develops by leaps and bounds. Such progress has fundamentally changed the development pace of history, becoming the principal driving force for the progre... Today in the 21st century, Science and technology (S&T)develops by leaps and bounds. Such progress has fundamentally changed the development pace of history, becoming the principal driving force for the progress of human civilization.……展开更多
为了探究裂缝扩展路径及在不同条件下的扩展规律,该文基于ABAQUS软件中扩展有限元方法(extended finite element method,XFEM)模拟分析沥青混凝土半圆弯曲断裂试验中的裂缝扩展规律。通过对比他人试验及数值模型数据,验证了基于XFEM的...为了探究裂缝扩展路径及在不同条件下的扩展规律,该文基于ABAQUS软件中扩展有限元方法(extended finite element method,XFEM)模拟分析沥青混凝土半圆弯曲断裂试验中的裂缝扩展规律。通过对比他人试验及数值模型数据,验证了基于XFEM的有限元模型分析裂缝扩展的有效性。此外,该文建立干法油石分离再生复合路面二维模型,研究模型中施工缝宽度、预埋裂缝长度、偏转角及预设位置对裂缝尖端应力影响,结果表明尖端应力随着裂缝长度、偏转角增加而增大,而随着施工缝宽度增大呈现先减小后增大趋势,随着偏移距离变大则先增大后减小。该文研究结果有助于复合路面反射裂缝定量分析与表征,为复合路面设计及后期养护提供了参考与依据。展开更多
This paper investigates the reflection of normal incident waves produced by absorbing-type breakwaters. The absorbing-type breakwaters in this study consist of a vertical porous plate, a submerged permeable caisson, a...This paper investigates the reflection of normal incident waves produced by absorbing-type breakwaters. The absorbing-type breakwaters in this study consist of a vertical porous plate, a submerged permeable caisson, and an impermeable back wall. The flow field is divided into four regions： a porous caisson region, and three pure water regions. Under the assumptions of linear wave theory, Darcy＇s law in the perforated wall, and the pore velocity potential theory of Sollitt and Cross （1972） in the porons caisson region, this study creates a 2-D BEM model to calculate the reflection coefficients of water waves using several breakwater properties. This numerical model is calibrated by previous numerical studies and limiting cases for a partially perforated-wall caisson breakwater and a vertical porous breakwater with an impermeable back wall. Generally speaking, the wave dissipation in absorbing-type breakwaters is bigger than that for a partially perforatedwall caisson breakwater. The reflection coefficient values imply the performance of wave absorbers in this study. Therefore, we examine the major factors that affect the reflection coefficient.展开更多
In this paper, we have calculated the angle of refraction that light travels approaching to the strong gravitational field like a black hole by combining the general relativity and the classical Snell’s law, assuming...In this paper, we have calculated the angle of refraction that light travels approaching to the strong gravitational field like a black hole by combining the general relativity and the classical Snell’s law, assuming that the gravitational field can act as a non-vacuum filled with medium of some coefficients. We have found that the value of refracted angle exactly coincides with the value from the Einstein’s relativity theory in a weak gravitational field. From this optical interpretation of the traveling of light near a black hole, we have suggested that there might have the reflection phenomenon and investigated that the total reflection occurs at the surface of a black hole. Regardless this might cause controversy, we can explain the recent observation that light reflects from a black hole.展开更多
文摘 Today in the 21st century, Science and technology (S&T)develops by leaps and bounds. Such progress has fundamentally changed the development pace of history, becoming the principal driving force for the progress of human civilization.……
文摘为了探究裂缝扩展路径及在不同条件下的扩展规律,该文基于ABAQUS软件中扩展有限元方法(extended finite element method,XFEM)模拟分析沥青混凝土半圆弯曲断裂试验中的裂缝扩展规律。通过对比他人试验及数值模型数据,验证了基于XFEM的有限元模型分析裂缝扩展的有效性。此外,该文建立干法油石分离再生复合路面二维模型,研究模型中施工缝宽度、预埋裂缝长度、偏转角及预设位置对裂缝尖端应力影响,结果表明尖端应力随着裂缝长度、偏转角增加而增大,而随着施工缝宽度增大呈现先减小后增大趋势,随着偏移距离变大则先增大后减小。该文研究结果有助于复合路面反射裂缝定量分析与表征,为复合路面设计及后期养护提供了参考与依据。
基金supported by the Science Council under Project No.NSC96-2221-E-019-063
文摘This paper investigates the reflection of normal incident waves produced by absorbing-type breakwaters. The absorbing-type breakwaters in this study consist of a vertical porous plate, a submerged permeable caisson, and an impermeable back wall. The flow field is divided into four regions： a porous caisson region, and three pure water regions. Under the assumptions of linear wave theory, Darcy＇s law in the perforated wall, and the pore velocity potential theory of Sollitt and Cross （1972） in the porons caisson region, this study creates a 2-D BEM model to calculate the reflection coefficients of water waves using several breakwater properties. This numerical model is calibrated by previous numerical studies and limiting cases for a partially perforated-wall caisson breakwater and a vertical porous breakwater with an impermeable back wall. Generally speaking, the wave dissipation in absorbing-type breakwaters is bigger than that for a partially perforatedwall caisson breakwater. The reflection coefficient values imply the performance of wave absorbers in this study. Therefore, we examine the major factors that affect the reflection coefficient.
文摘In this paper, we have calculated the angle of refraction that light travels approaching to the strong gravitational field like a black hole by combining the general relativity and the classical Snell’s law, assuming that the gravitational field can act as a non-vacuum filled with medium of some coefficients. We have found that the value of refracted angle exactly coincides with the value from the Einstein’s relativity theory in a weak gravitational field. From this optical interpretation of the traveling of light near a black hole, we have suggested that there might have the reflection phenomenon and investigated that the total reflection occurs at the surface of a black hole. Regardless this might cause controversy, we can explain the recent observation that light reflects from a black hole.
