共查询到20条相似文献，搜索用时 31 毫秒
1.
郑云英 《淮南师范学院学报》2007,9(3):93-95
文章主要讨论了自由边界上平面横波的反射问题,得到了非均匀反射横波的波速、反射系数、衰减率等物理量的解析表达式。数值结果揭示了入射横波的频率、孔隙流体与固相骨架的耦合系数和固相骨架粘性等对波速、衰减率等物理量的影响。 相似文献
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Wave breaking plays an important role in sedi- ment transport and beach profile change. Breaking waves exhibit various patterns, principally depending on the incident wave steepness and the beach slope. The breaking patterns range from the relatively con- trolled spilling type to the violent and sudden plunging breaker type. The breaker patterns are classified into 3 or 4 categories. Some criteria for breaker pat- terns[1] are given in Tab. 1. Several wave decay models have been proposed to d… 相似文献
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矩形隧道中无线电波的衰减特性分析 总被引：1，自引：0，他引：1
周玉坤 《廊坊师范学院学报(自然科学版)》2011,11(5):37-38,41
通过数值仿真研究了矩形隧道中的电磁场损耗问题。分析了电磁波衰减受相对介电常数、隧道壁粗糙程度、隧道壁的倾斜程度的影响。随着无线通信系统频率的变大,无线电波在巷道内传输的衰减越小,巷道壁粗糙所引起的损耗也越小,但巷道壁倾斜引起的损耗因素将加大。在实际应用中要综合考虑这些因素对电磁波损耗的影响。 相似文献
4.
周玉坤 《河北职业技术学院学报》2011,(5)
通过数值仿真研究了矩形隧道中的电磁场损耗问题。分析了电磁波衰减受相对介电常数、隧道壁粗糙程度、隧道壁的倾斜程度的影响。随着无线通信系统频率的变大,无线电波在巷道内传输的衰减越小,巷道壁粗糙所引起的损耗也越小,但巷道壁倾斜引起的损耗因素将加大。在实际应用中要综合考虑这些因素对电磁波损耗的影响。 相似文献
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A flap-type wave energy converter (WEC) is combined with a nearshore breakwater to expand the application of WECs both economically and environmentally. Based on the linear potential theory, an eigenfunction expansion solution is developed for a periodic row of bottom-hinged flap-type WECs exposed to normal waves. Additionally, the viscous effect is considered using the ship rolling solution method with a viscous damping term included in the equation of motion, and the viscous damping expression is also described. The proposed solution is verified by comparison with published literatures. The results including the wave energy conversion efficiency, the reflected and transmitted proportion of the incident wave energy are presented for a range of wave periods and geometric ratios. It is demonstrated that better wave protection effects can be attained with smaller gaps between the WECs, where the transmitted proportion of the incident wave energy is lower. An optimal geometric ratio thus exists for a given wave power absorption and a specific wave period. 相似文献
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通过对开边界、入射边界、自由表面边界以及底边界的合理处理,用有限元法建立了基于Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程的二维数值波浪水槽．利用这一数值模型,计算了波浪在台阶地形上的传播变形．基于运动学指标判断了波浪破碎的发生,并给出了临界破碎波高．实验结果证实了本文模型的可靠性,并给出了破碎后波高的衰减规律． 相似文献
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通过分析正弦波、方波和最优化过零方波作为激励信号源的优点和不足,设计了集合这三种激励信号源优点的优化过零梯形波,以满足主动型邻井定位技术的测距范围和精度需要。同时提出了基于优化过零梯形波信号源的多频信号检测算法:首先,把接收端的三频含噪信号进行DFT算法处理,找出三个最大幅值对应的频率,求出对应频率的恢复信号幅值;其次,进行幅值校正得到三个频率原始激励信号的真实幅值;最后,对计算出的每个信号的频率及幅值进行重新构造,得到重构信号。仿真实验表明,优化过零梯形波的基波能量占比接近于正弦波,高于最优化过零方波,便于其扩大测距范围、增加测距精度,而且优化过零梯形波作为激励信号源容易在工程上实现。 相似文献
9.
Wan Decheng 《上海大学学报(英文版)》1999,(1)
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｐｒｏｂｌｅｍｏｆｔｈｅｉｎｔｅｒａｃｔｉｏｎｂｅｔｗｅｅｎｒｅｇｕｌａｒｗａｔｅｒｗａｖｅｓａｎｄａｓｕｂｍｅｒｇｅｄｏｂｓｔａｃｌｅｉｓｒｅｌｅｖａｎｔｔｏｔｈｅｄｅｓｉｇｎａｎｄｏｐｅｒａｔｉｏｎｏｆｏｆｆｓｈｏｒｅａｎｄｃｏａｓｔａｌｓｔｒｕｃｔｕｒｅｓ．Ａｋｎｏｗｌｅｄｇｅｏｆｔｈｅｆｒｅｅｓｕｒｆａｃｅｄｅｆｏｒｍａｔｉｏｎｓａｎｄｖｏｒｔｅｘｆｌｏｗｉｓｎｅｃｅｓｓａｒｙｆｏｒｅｓｔｉｍａｔｉｏｎｏｆｄｒｉｆｔｆｏｒｃｅｓａｎｄｓｕｐｅｒｈａｒ… 相似文献
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万德成 《上海大学学报(英文版)》1999,3(1):30-35
The interaction between regular water waves and a submerged obstacle in a channel is studied numerically. The fluid viscosity is taken into account and the volume of fluid method is used to deal with the free surface. The incident regular waves are generated by use of numerical absorbing wave maker paddle. The present method can be used to predict the nonlinear deformations of the transmitted regular waves, and to simulate the vortex flow near the obstacle and the shear flows beneath the free surface. 相似文献
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远破波作用下防波堤前海床冲刷及其相似律 总被引：1，自引：0，他引：1
波浪作用下防波堤前海床将发生冲刷 ,进而危及防波堤的安全 .通过试验和理论分析研究了远破波作用下防波堤前沙质海床冲刷 ,包括堤前冲刷深度和范围、基床尺度对堤前冲刷和淤积的影响 .为将研究成果应用于实际工程 ,研究了冲刷相似律 ,提出了模型沙比尺和冲淤比尺 相似文献
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Based on the characteristics of 1D waves,the stress uniformity process in specimens under different loading conditions of rectangular and half-sine input waves was analyzed in split Hopkinson pressure bar (SHPB) test.The results show that the times of an elastic wave propa-gating from one end to the other in a specimen to attain stress equilibrium,is related to input wave-forms and relative mechanical impedance between the specimen and the input/output bars.Here-into,with the increae of the relative impedance,the times decreases under rectangular input waves loading,while it increases under half-sine input wave loading.The dimensionless stress value of specimen corresponding to the status of stress equilibrium increases with the increase of the rela-tive mechanical impedance.However,the dimensionless stress value under half-sine input wave loading is significantly lower than the value under rectangular input wave loading for specimen with low mechanical impedance,and the relative differentia of the dimensionless stress values under two loading conditions decreases with the increase of the relative mechanical impedance.In gen-eral,the forced state of specimen with relatively low mechanical impedance under half-sine input wave loading is evidently superior to the state under rectangular input wave loading in SHPB test,and the advantages of forced state under half-sine input wave loading turns weak with the increase of the relative mechanical impedance. 相似文献
13.
赵国求 《武汉工程职业技术学院学报》2000,(3)
电子、质子、中子半径的实验测量表明 ,康普顿波长 λ。可作为其半径的理论值 ;而由康普顿波长 λ。我们可以构造康普顿物质波。分析表明狄拉克相对论自由电子平面波波函数是康普顿物质波的特例 ,薛定谔自由电子平面波波函数则是康普顿物质波分量的经典极限。对上述三种平面波作箱式归一化处理 ,可以看出自由电子平面波亦是曲率波。 相似文献
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研究了各向异性介质中的谐和粘弹性波的衰减特性，并利用其特征值理论证明了粘弹性介质总是耗散的，在其中传播的波将以指数形式衰减，即耗散介质总具有线性稳定性，而且随着阻尼的增大，介质消耗的能量将越大，波矢量的虚实部比是介质耗散大小的度量。 相似文献
15.
柯惟力 《江苏广播电视大学学报》2002,13(3):49-52
引力波是广义相对论的重要推论之一。科学家们希望能直接探测到引力波,但是由于产生机制的不同,引力波远弱于电磁波,而人工引力波源产生的引力波目前无探测可能。宇宙中虽然存在大量的天体引力波源,但传到地球上的信号都很弱。目前,科学家们已设计出几种实验装置去探测引力波。 相似文献
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The random wave load is applied to dynamic response analysis of circular caisson breakwater. The motion process of circular caisson breakwater is classified as rotation motion mode and rotation-and-sliding motion mode. The dynamic model system composed of damper-antislider to control the lateral sliding is introduced, and corresponding dynamic equations of two motion modes are established. The formulas to calculate added mass and new conversion relation of the unit rotational stiffness coefficient are put forward according to the characteristic of the circular caisson breakwater. An engineering case is calculated by a program compiled in Fortran language using proposed dynamic model and method. The validity of the model is calibrated. 相似文献
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基于Lamb波在各向异性材料的波动方程和频散原理,采用斜入射法激发A0模态兰姆波。针对板材的铺层角度、各接收点方向和频厚积等因素对衰减规律和传播速度规律有较大影响,采用有限元软件建立玻璃钢复合材料层合板模型,对各影响因素进行数值模拟研究。研究表明:Lamb波传播特性与纤维铺层方式有关,声速及衰减特性沿纤维方向和非纤维方向传播声速和衰减差异较大,并且呈对称现象,频厚积在0.6~1.8 MHz·mm,对传播声速和衰减影响为线性下降且趋于平稳。 相似文献
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ＩＮＴＲＯＤＵＣＴＩＯＮＳｈｏｃｋｗａｖｅｒｅｆｌｅｃｔｉｏｎｆｒｏｍａｗａｌｌｓｕｒｆａｃｅ,ｄｉｆｆｒａｃｔｉｏｎａｌｏｎｇａｃｕｒｖｅｄｓｕｒｆａｃｅ ,ｐｒｏｐａｇａｔｉｏｎｔｈｒｏｕｇｈａｃｈａｎｎｅｌｏｒａｔｕｂｅｗｉｔｈｖａｒｙｉｎｇｃｒｏｓｓ 相似文献
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利用广义映射法,研究非线性薛定谔系统,得到了它的周期波解、具有周期性行为的孤波解和雅科比椭圆函数解,并解释了两列互相垂直的具有周期性行为的孤波相互作用后产生新的孤波结构的现象。 相似文献