基于GPU加速的Boussinesq类波浪传播变形数值模型

Boussinesq波浪模型是一类相位解析模型,在时域内求解需要较高的空间和时间分辨率以保证计算精度。为提高计算效率,有必要针对该类模型开展并行算法的研究。与传统的中央处理器(CPU)相比,图形处理器(GPU)有大量的运算器,可显著提高计算效率。基于统一计算设备架构CUDA C语言和图形处理器,实现了Boussinesq模型的并行运算。将本模型的计算结果同CPU数值模拟结果和解析解相比较,发现得到的结果基本一致。同时也比较了CPU端与GPU端的计算效率,结果表明,GPU数值模型的计算效率有明显提升,并且伴随数值网格的增多,提升效果更为明显。     

防浪建筑物影响下珊瑚礁海岸波浪传播变形试验

通过测试一系列不规则波工况研究了防浪建筑物存在下珊瑚礁海岸附近短波、低频长波和增水的变化规律,并对比了防浪建筑物的不同位置情况。分析结果表明：波浪在沿礁传播过程中,短波波高沿礁坪持续衰减,低频长波波高沿礁坪逐渐增大,波浪增水则沿礁坪基本保持不变;海岸附近短波随着防浪建筑物与礁缘距离的变大而减小,低频长波则在防浪建筑物处于礁坪后部时达到最大,防浪建筑物位置的变化对于礁坪波浪增水的影响可以忽略。通过理论分析证明了珊瑚礁地形上低频长波是由于群波破碎造成的破碎点移动而产生的;当特定波况作用于特定位置的防浪建筑物时,低频长波在礁坪上会发生一阶共振效应导致其能量在海岸附近达到最大值。     

基于离散颗粒模型的岩体结构面动-静态刚度系数对比的数值模拟研究

岩体工程计算分析中结构面刚度系数是至关重要的力学参数,计算分析的精度和可靠程度与这个参数密不可分,结构面刚度系数取值仍然是一个难点.岩体中应力波传播至结构面处将会发生反射和透射现象,利用应力波透射系数可反演结构面动态刚度系数.本文从细观力学角度运用颗粒离散元方法,开发分段线性接触模型及应力波吸收边界模型,开展宏观岩体中...     

Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates

Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.     

高阶非线性完全频散性波浪数值模型及应用

为更精确地模拟强非线性完全频散性波浪的传播,采用长波上非线性重力表面波传播高阶数学模型,综合参考此模式已有的研究成果,建立了一个高达五阶的完全频散性非线性数值模型。应用该五阶模式对斜坡地形、潜堤地形及正弦沙链地形进行模拟计算,并与已有的实验资料进行对比,结果显示五阶模式较低阶模式模拟结果的精度上有了明显提高,模拟波形与实验结果吻合度良好,证明高阶模式更适用于高频散高非线性波浪传播的数值模拟。     

季节因素对大西洋声传播的影响分析

以分析季节对大西洋声传播的影响为研究目的,应用WOA13季节平均数据和Mackenzie声速经验公式,分析了大西洋声道轴和表层声速值的四季分布情况,再利用BELLHOP水声学数值模型,在设定的声源频率1 000 Hz和掠射角15°～-15°情况下,仿真计算选用位置点5 m深度声源的四季声传播情况,研究结果表明:按照实际的季节,大西洋会聚区波导的反转深度,冬季最小,春季增大,夏季最大,秋季再减小.在中低纬度的典型声速剖面下,夏季会聚区跨度最大,秋季和冬季递减,春季最小,第一会聚区的四季跨度差在1 km内.在高纬度的正梯度声速剖面下,夏季声传播距离最远,秋季减小,冬季最近,春季增大,且传播距离的差别较大.各变化规律均以四季循环更替的形式出现.     

关于中医药文化国际传播的调查与思考

通过问卷和访谈的方式,以在天津的国际学生及外教为调查对象,调查了新形式下中医药文化国际传播的现状,发现中医药文化国际传播中存在传播路径狭窄、文化层面传播较少、中医药合法地位没有彻底解决等问题,提出获得政府支持、创新传播方式、发展中医药文化产业和重视海外中医人等对策。     

(2+1)维 Korteweg-de Vries 方程的传播孤子及混沌行为

利用一个投射方程和变量分离法,得到了(2+1)维 Korteweg-de Vries (KdV) 方程的新显式精确解.根据得到的孤立波解,构造出 KdV 方程的传播孤子结构. 利用一个新的混沌系统研究了孤子的混沌行为.     

Experimenta l study on ultrasonic propagation in water-based bentonite slurry

Drilling fluid is a common flushingmedium used in pile foundation, geological drilling and petroleum drilling. Study on ultrasonic propagation properties in drilling fluid is of vital importance, not only for developing equipments to non-contact measuring concrete casting level for bored pile, but also for developing equipments considering drilling fluid as signal channel. The existence of clay particlesmakes the ultrasonic propagation and attenuation in drilling fluid much different from pure water. In order to know the relation among ultrasound frequency, slurry density and depth, a series of laboratory experiments about ultrasound propagation in water-based bentonite slurry were finished. Wavelet method was adopted to process the gained original waves of ultrasonic propagation in slurry, so we knew the velocity and attenuation coefficient of ultrasound propagated in different drilling fluids with different density. The first group experiments shows that with density of drilling fluid increase, ultrasonic velocity will decrease but attenuation coefficient will increase if ultrasonic frequency keep constant. The second group experiments shows that the power of ultrasound will intensify in small bore hole, the attenuation coefficient ismuch smaller than theoretical value.     

IDM模型分析及其影响力改进算法

影响力传播模型IDM用于挖掘和分析BBS上观点领袖以及热门话题,它主要以影响力作为衡量标准。通过简化影响力运算法则,对IDM模型进行改进,使其更加直观。此改进后的IDM模型可运用到社会网络中,能更深刻的揭示出社会网络中各通信个体间的相互影响和距离,从而更好地了解和研究社会网络。