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Disintegration of Linear Edge Waves 被引量:1
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作者 王岗 Viet Thanh Nguyena +3 位作者 郑金海 董国海 马小舟 马玉祥 《China Ocean Engineering》 SCIE EI CSCD 2013年第4期557-562,共6页
It is demonstrated that offshore wavenumbers of edge waves change from imaginary wavenumbers in deep water to real wavenumbers in shallow water. This finding indicates that edge waves in the offshore direction exist a... It is demonstrated that offshore wavenumbers of edge waves change from imaginary wavenumbers in deep water to real wavenumbers in shallow water. This finding indicates that edge waves in the offshore direction exist as evanescent waves in deep water and as propagating waves in shallow water. Since evanescent waves can stably exist in a limited region while propagating waves cannot, energy should be released from nearshore regions. In the present study, the instability region is predicted based on both the full water wave solution and the shallow-water wave approximation. 展开更多
关键词 edge waves evanescent waves propagating waves water waves
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电压敏感染料成像技术及其在神经科学中的应用 被引量:3
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作者 廖文凯 吴建永 耿新玲 《生物物理学报》 CAS CSCD 北大核心 2011年第7期569-587,共19页
电压敏感染料成像(voltage sensitive dye imaging,VSDI)技术利用结合在神经细胞脂膜上的染料,将膜电位转化为荧光或光吸收信号,并用光学成像方法对神经电活动进行多点测量。VSDI在过去的50年内发展迅速,其良好的时空分辨率使它成为一... 电压敏感染料成像(voltage sensitive dye imaging,VSDI)技术利用结合在神经细胞脂膜上的染料,将膜电位转化为荧光或光吸收信号,并用光学成像方法对神经电活动进行多点测量。VSDI在过去的50年内发展迅速,其良好的时空分辨率使它成为一种在介观(mesoscopic)时空尺度上研究神经元群体电活动的实用技术。这项技术对探索大脑功能和研究神经系统疾病有着重要的贡献。本文首先对该技术的发展历史做一简单介绍,接下来简述当今世界上这一领域的主要研究内容,以及该技术的发展前景。 展开更多
关键词 电压敏感染料 光学成像 时空模式 兴奋波 皮层
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A Study on the Physical Processes of the Formation of the ENSO Cycle 被引量:1
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作者 ZONG Haifeng 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2014年第6期1395-1406,共12页
The physical processes involved in the formation of the ENSO cycle,as well as the possible roles of the Hadley circulation (HC),Walker circulation (WC),and the propagating waves of the Southern Oscillation/Norther... The physical processes involved in the formation of the ENSO cycle,as well as the possible roles of the Hadley circulation (HC),Walker circulation (WC),and the propagating waves of the Southern Oscillation/Northern Oscillation (SO/NO) in its formation,were studied using composite and regression methods.The analysis showed that the convection and heat release triggered by ENSO in the central-eastern equatorial Pacific are the primary drivers for the 3-5 year cycle of the HC,WC and the meridional/zonal circulation.The HC plays a key role in the influence of ENSO on the circulation outside the tropics through angular momentum transportation.Meanwhile,the feedback effects of the anomalous circulation in the mid-high latitudes on ENSO are accomplished by the propagating waves of SO/NO associated with the evolutions of HC and WC.These propagating waves are the main agents of the connections among the meridional/zonal circulation outside the tropics,the Asian/Australian monsoon,the anomalous easterly/westerly winds over the tropical Pacific,and ENSO events.It was found that the 3-5 year cycle of the meridional/zonal circulation forced by ENSO is quite different from the several-week variation of the circulation index triggered by the inner dynamic processes of the atmosphere.The former occurs at the global scale with a definite flow pattern,while the latter occurs only in a wide area without a definite flow pattern.Finally,a physical model for the formation of the ENSO cycle composed of two fundamental processes at the basin and global scale,respectively,is proposed. 展开更多
关键词 ENSO cycle meridional/zonal circulation Hadley circulation propagating waves Southern Oscillation/Northern Oscillation
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压电超声微马达的研究新进展 被引量:2
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作者 彭海军 王德石 杜贻群 《机械设计与制造》 北大核心 2009年第6期109-111,共3页
介绍了国内外压电超声微马达的最新研究成果。总结出压电超声马达微型化的通用方法,并指出了压电超声微马达的下一步研究重点。
关键词 超声马达 微型马达 行波 驻波
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Universality Class of the Nonequilibrium Phase Transition in Two-Dimensional Ising Ferromagnet Driven by Propagating Magnetic Field Wave
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作者 Ajay Halder Muktish Acharyya 《Applied Mathematics》 2019年第7期568-577,共10页
The purpose of this work is to identify the universality class of the nonequilibrium phase transition in the two-dimensional kinetic Ising ferromagnet driven by propagating magnetic field wave. To address this issue, ... The purpose of this work is to identify the universality class of the nonequilibrium phase transition in the two-dimensional kinetic Ising ferromagnet driven by propagating magnetic field wave. To address this issue, the finite size analysis of the nonequilibrium phase transition, in two-dimensional Ising ferromagnet driven by plane propagating magnetic wave, is studied by Monte Carlo simulation. It is observed that the system undergoes a nonequilibrium dynamic phase transition from a high temperature dynamically symmetric (propagating) phase to a low temperature dynamically symmetry-broken (pinned) phase as the system is cooled below the transition temperature. This transition temperature is determined precisely by studying the fourth-order Binder Cumulant of the dynamic order parameter as a function of temperature for different system sizes (L). From the finite size analysis of dynamic order parameter ?and the dynamic susceptibility , we have estimated the critical exponents and ?(measured from the data read at the critical temperature obtained from Binder cumulant), and (measured from the peak positions of dynamic susceptibility). Our results indicate that such driven Ising ferromagnet belongs to the same universality class of the two-dimensional equilibrium Ising ferromagnet (where and ), within the limits of statistical errors. 展开更多
关键词 ISING Model Dynamic Phase Transition Monte-Carlo Simulation propagating wave FINITE Size Analysis Critical EXPONENTS UNIVERSALITY
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自蔓延高温合成过程中蔓延波的特征
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作者 梅炳初 袁润章 《广西大学学报(自然科学版)》 CAS CSCD 1996年第1期85-88,共4页
本文概述了材料的自蔓延高温合成(SHS)的主要概念,并详细介绍SHS过程中蔓延波的特征。根据温度分布及产物转化过程,蔓延波可分为四类:(1)具有很窄的反应区,在这个区域反应物迅速转变为产物;(2)具有较宽的反应区,反... 本文概述了材料的自蔓延高温合成(SHS)的主要概念,并详细介绍SHS过程中蔓延波的特征。根据温度分布及产物转化过程,蔓延波可分为四类:(1)具有很窄的反应区,在这个区域反应物迅速转变为产物;(2)具有较宽的反应区,反应过程强烈地受动力学控制;(3)在SHS过程中具有相变发生;(4)在生成最终产物之前有中间化合物生成。 展开更多
关键词 自蔓延高温合成 蔓延波 材料合成
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A COUNTER PROPAGATING WAVE STATE WITH A PERIODICALLY HORIZONTAL MOTION OF DEFECTS 被引量:40
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作者 NING Li-zhong QI Xin YUAN Zhe SHI Feng 《Journal of Hydrodynamics》 SCIE EI CSCD 2008年第5期567-573,共7页
Convection in a horizontal fluid layer heated from below is one of models for studying patterns of convection in binary fluid mixtures and has been extensively studied. In this article, the convection structures in a ... Convection in a horizontal fluid layer heated from below is one of models for studying patterns of convection in binary fluid mixtures and has been extensively studied. In this article, the convection structures in a rectangular cell were investigated for the aspect-ratio Г= 12 and the separation ratio ψ = -0.47. Simulations were preformed by solving the hydrodynamic equations using the SIMPLE method. A Counter Propagating Wave (CPW) state was found in binary fluid convection with a periodically horizontal motion of defects, and the pattern dynamics was further discuss. 展开更多
关键词 Counter propagating wave (CPW) defect convection pattern dynamics
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顶部水泥脉冲振动的数学模型 被引量:12
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作者 练章华 李文魁 陈小榆 《石油学报》 EI CAS CSCD 北大核心 2001年第1期83-88,共6页
介绍了顶部水泥脉冲振动技术的基本原理和方法。文中根据牛顿定律、质量守恒定律及水泥浆的宾汉塑性流变性 ,在顶部水泥脉冲振动作用下 ,建立了水泥浆中 ,一维压力传播的波动方程的数学模型。同时根据弹性理论和液体可压缩性 ,推导出了... 介绍了顶部水泥脉冲振动技术的基本原理和方法。文中根据牛顿定律、质量守恒定律及水泥浆的宾汉塑性流变性 ,在顶部水泥脉冲振动作用下 ,建立了水泥浆中 ,一维压力传播的波动方程的数学模型。同时根据弹性理论和液体可压缩性 ,推导出了井眼岩石、水泥浆及套管共同作用下的当量体积弹性模量 ,并讨论了顶部水泥脉冲振动波动方程数学模型的物理意义及其具体应用时所要考虑的问题 ,为固井时 ,顶部水泥脉冲振动的优化设计、压缩机的优化及优选提供了理论依据。 展开更多
关键词 水泥浆 脉冲振动 波动方程 压力波 数学模型 石油钻井 固井
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长矩形截面腔体内具有缺陷的对传行波斑图 被引量:8
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作者 郝建武 宁利中 +1 位作者 王卓运 王娜 《力学季刊》 CSCD 北大核心 2013年第1期139-146,共8页
在长高比Γ=40、分离比ψ=-0.6情况下,通过流体力学基本方程组的数值模拟,得到了一种新的有趣斑图,即单侧缺陷摆动对传行波。通过分析单侧缺陷摆动对传行波各物理场随时间变化的等值线图、波形图,讨论了其形成过程及时空动力学特性。进... 在长高比Γ=40、分离比ψ=-0.6情况下,通过流体力学基本方程组的数值模拟,得到了一种新的有趣斑图,即单侧缺陷摆动对传行波。通过分析单侧缺陷摆动对传行波各物理场随时间变化的等值线图、波形图,讨论了其形成过程及时空动力学特性。进一步对比不同相对瑞利数下的单侧缺陷摆动对传行波,探讨了缺陷数、缺陷周期以及缺陷方向等缺陷特征对相对瑞利数的依赖性。 展开更多
关键词 单侧缺陷 对传行波 分离比 瑞利数
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TRANSIENT-STATE RESPONSE OF WAVE PROPAGATION IN MAGNETO-ELECTRO-ELASTIC SQUARE COLUMN 被引量:2
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作者 Jianping Wei Xianyue Su 《Acta Mechanica Solida Sinica》 SCIE EI 2008年第6期491-499,共9页
This is a continued work in studying the wave propagation in a magneto-electroelastic square column (MEESC). Based on the analytic dispersive equation, group velocity equation and steady-state response obtained in o... This is a continued work in studying the wave propagation in a magneto-electroelastic square column (MEESC). Based on the analytic dispersive equation, group velocity equation and steady-state response obtained in our previous paper 'Steady-state response of the wave propagation in a magneto-electro-elastic square column' published in CME, the dynamical behavior of MEESC was studied in this paper. The unlimited column is an open system. The transientstate response in the open system subjected by arbitrary external fields was derived when the propagating wave pursuing method was introduced. 展开更多
关键词 magneto-electro-elastic square column open system transient-state response propagating wave pursuing method
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On Two-Dimensional Above-Barrier Penetration and Sub-Barrier Tunneling for Non-Relativistic Particles and Photons
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作者 Vladislav S. Olkhovsky Mariya V. Romaniuk 《Journal of Modern Physics》 2011年第10期1166-1171,共6页
We study the two-dimensional above-barrier penetration and the sub-barrier tunneling of non-relativistic particles and photons, described in the quasi-monochromatic approximation by simple plane waves. Our scheme repr... We study the two-dimensional above-barrier penetration and the sub-barrier tunneling of non-relativistic particles and photons, described in the quasi-monochromatic approximation by simple plane waves. Our scheme represents the motion from the left free-motion zero-potential region to the right zero-potential region through the intermediate region with a one-dimensional rectangular potential barrier along the axis, normal to the both parallel interfaces between all three regions, and with the zero potential along the axis, parallel to the those interfaces. We have firstly obtained the analytical expressions for the infinite series of multiple internal and external reflections and also of multiple transmitted waves of particles and photons, with equal shifts between them along the interfaces for the above-barrier penetration and with various shifts between them in the case of the sub-barrier tunneling. Finally the Hartman and Fletcher effect for any transmitted wave is established. 展开更多
关键词 TWO-DIMENSIONAL (2D) Penetration and TUNNELING Quasi-Monochromatic Approximation propagating Plane waves Evanescent and Anti-Evanescent waves
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Nonequilibrium Phase Transition in Spin-S Ising Ferromagnet Driven by Propagating and Standing Magnetic Field Wave
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作者 Ajay Halder Muktish Acharyya 《Communications in Theoretical Physics》 SCIE CAS CSCD 2017年第11期600-610,共11页
The dynamical response of spin-S(S=1, 3/2, 2, 3) Ising ferromagnet to the plane propagating wave, standing magnetic field wave and uniformly oscillating field with constant frequency are studied separately in two dime... The dynamical response of spin-S(S=1, 3/2, 2, 3) Ising ferromagnet to the plane propagating wave, standing magnetic field wave and uniformly oscillating field with constant frequency are studied separately in two dimensions by extensive Monte Carlo simulation. Depending upon the strength of the magnetic field and the value of the spin state of the Ising spin lattice two different dynamical phases are observed. For a fixed value of S and the amplitude of the propagating magnetic field wave the system undergoes a dynamical phase transition from propagating phase to pinned phase as the temperature of the system is cooled down. Similarly in case with standing magnetic wave the system undergoes dynamical phase transition from high temperature phase where spins oscillate coherently in alternate bands of half wavelength of the standing magnetic wave to the low temperature pinned or spin frozen phase. For a fixed value of the amplitude of magnetic field oscillation the transition temperature is observed to decrease to a limiting value as the value of spin S is increased. The time averaged magnetisation over a full cycle of the magnetic field oscillation plays the role of the dynamic order parameter. A comprehensive phase boundary is drawn in the plane of magnetic field amplitude and dynamic transition temperature. It is found that the phase boundary shrinks inwards for high value of spin state S.Also in the low temperature(and high field) region the phase boundaries are closely spaced. 展开更多
关键词 Ising model dynamic phase transition Monte-Carlo algorithm propagating wave standing wave
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为什么近场? 被引量:2
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作者 肖暮霏 《南昌航空工业学院学报》 CAS 1997年第1期89-92,共4页
本文提出对近场光学的一些新的看法,介绍了隐视波(evanescent)和传递波(propagating)的分解,以及它们在近、中和远场中的不同分布和行为,从而提出对扫描近场光学显微镜(SNOM)分辨率的全新观点。本文... 本文提出对近场光学的一些新的看法,介绍了隐视波(evanescent)和传递波(propagating)的分解,以及它们在近、中和远场中的不同分布和行为,从而提出对扫描近场光学显微镜(SNOM)分辨率的全新观点。本文还探讨了在中场或远场区域获得小于经典衍射极限的分辨率的可能性。文中为简洁起见。 展开更多
关键词 隐视波 传递波 光学 近场光学
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基于P波残差理论的微震信号传播波速标定试验研究 被引量:2
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作者 刘超 李树刚 +1 位作者 林海飞 刘纪坤 《煤矿开采》 北大核心 2013年第3期8-10,7,共4页
为了获取监测区域微震信号传播波速,基于P波残差理论,通过爆破试验标定波速的方法,研究了微震信号传播波速的标定原理及方法,并优化了监测区域P波波速,提高了震源定位精度。结果表明:该方法与传统的以实验室所测试样波速进行定位计算相... 为了获取监测区域微震信号传播波速,基于P波残差理论,通过爆破试验标定波速的方法,研究了微震信号传播波速的标定原理及方法,并优化了监测区域P波波速,提高了震源定位精度。结果表明:该方法与传统的以实验室所测试样波速进行定位计算相比,能够较为真实地反映出监测区域的煤岩体波速。上述结果能很好地提高微震技术在煤岩体稳定性评估方面的监测效果。 展开更多
关键词 P波残差理论 微震信号 传播波速 标定 爆破试验
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表面张力、黏性和驱动对非传播表面孤立波的影响 被引量:2
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作者 颜家壬 周川汇 +1 位作者 钟建新 游建强 《力学学报》 EI CSCD 北大核心 1994年第2期158-164,共7页
从理论上研究了表面张力、黏性和驱动对非传播表面孤立波的影响。指出表面张力使孤波高度增大、宽度减小.作出了孤波的等波响应曲线(equal-wave-response-curves)并与实验结果进行了比较。
关键词 非传播孤立波 表面张力 粘性
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薄壁板结构随机声激励振动响应计算与分析 被引量:2
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作者 张国治 沙云东 +1 位作者 朱林 冯飞飞 《沈阳航空航天大学学报》 2014年第4期23-28,共6页
针对航空发动机压气机转子叶片结构声振动问题,建立了薄壁板有限元简化模型,基于耦合有限元/边界元法对薄壁板在行波加载下随机声激励振动响应进行了仿真计算,得到了在不同声压级下的应力响应结果。改变声载荷激励方向,分别对薄壁板施... 针对航空发动机压气机转子叶片结构声振动问题,建立了薄壁板有限元简化模型,基于耦合有限元/边界元法对薄壁板在行波加载下随机声激励振动响应进行了仿真计算,得到了在不同声压级下的应力响应结果。改变声载荷激励方向,分别对薄壁板施加单音噪声激励和宽频随机噪声激励,通过仿真计算得到了不同角度随机声激励下薄壁板振动响应频响曲线。对比分析发现,薄壁板模态振型与噪声加载方向是引起薄壁板共振的重要因素。 展开更多
关键词 薄壁板 耦合有限元/边界元法 行波加载 随机声激励 振动响应
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混合流体对流中具有间歇性缺陷的缺陷源摆动的对传波 被引量:1
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作者 宁利中 宁景昊 +3 位作者 宁碧波 田伟利 郝建武 吴昊 《应用力学学报》 CSCD 北大核心 2017年第2期342-347,共6页
通过数值模拟,研究了长高比Γ_x=40和分离比ψ-=2.0时有间歇性缺陷的缺陷源摆动的对传波。研究表明:对于给定的相对瑞利数r,在缺陷源摆动的对传波中,缺陷源做"S"型曲线摆动,缺陷源两侧行波分支上存在间歇性缺陷,行波分支上的... 通过数值模拟,研究了长高比Γ_x=40和分离比ψ-=2.0时有间歇性缺陷的缺陷源摆动的对传波。研究表明:对于给定的相对瑞利数r,在缺陷源摆动的对传波中,缺陷源做"S"型曲线摆动,缺陷源两侧行波分支上存在间歇性缺陷,行波分支上的缺陷数量不固定;随相对瑞利数r增加,缺陷源沿腔体水平方向的摆动振幅不断减小,缺陷源两侧行波分支上的缺陷数量呈减少局势,缺陷源初始摆动方向由向左变为向右;垂直流速最大值δw_(max)和下壁面努塞尔数Nu-1是相对瑞利数r的函数,并给出了它们随着相对瑞利数r的变化关系式。 展开更多
关键词 对传波 缺陷源 摆动 斑图 混合流体
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浅水中水内部非传播孤波的研究
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作者 徐柳苏 黄健强 《广西工学院学报》 CAS 2002年第1期10-11,31,共3页
在外部驱动下 ,不仅在浅水表面 ,而且在水内部都会产生非传播孤波。本文用多重尺度的摄动法给出了水内部的非传播孤波表达式 。
关键词 非传播孤波 多重尺度法 摄动法 孤波解 水动力学 浅水
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大气波导特征分析及其对电磁波传播的影响 被引量:127
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作者 姚展予 赵柏林 +3 位作者 李万彪 朱元竞 杜金林 戴福山 《气象学报》 CSCD 北大核心 2000年第5期605-616,共12页
文中在介绍大气折射的基本类型及其存在条件的基础上 ,阐述了三种类型的大气波导的形成机制 ,总结并分析了大气波导的几个主要特征 ,并用西北太平洋云辐射实验的实测资料和西沙海域的气象资料进行了验证 ,同时试验了蒸发波导高度对大气... 文中在介绍大气折射的基本类型及其存在条件的基础上 ,阐述了三种类型的大气波导的形成机制 ,总结并分析了大气波导的几个主要特征 ,并用西北太平洋云辐射实验的实测资料和西沙海域的气象资料进行了验证 ,同时试验了蒸发波导高度对大气湿度、气海温差、水平风速变化的敏感性 .在分析大气波导对电磁波传播的影响时 ,推导了可形成波导传播的电磁波最大陷获波长和临界发射仰角 ,提出了电磁波形成波导传播的 4个必要条件 ,并讨论了大气波导对超短波传播、雷达探测、短波通信等方面的影响 . 展开更多
关键词 大气波导 特征分析 电磁波传播 表面波导
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桥梁振动辐射低频噪声评估方法研究 被引量:31
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作者 谢旭 张鹤 +1 位作者 山下幹夫 张治成 《土木工程学报》 EI CSCD 北大核心 2008年第10期53-59,共7页
为了研究桥梁交通振动辐射低频噪声的机理和建立相应的数值模拟方法,用车桥耦合振动和空气波传播原理提出桥梁振动辐射低频噪声的计算方法。以一座简支钢桥为例,用格子梁结构计算模型分析车辆通过时的结构振动和由此引起的声压,通过与... 为了研究桥梁交通振动辐射低频噪声的机理和建立相应的数值模拟方法,用车桥耦合振动和空气波传播原理提出桥梁振动辐射低频噪声的计算方法。以一座简支钢桥为例,用格子梁结构计算模型分析车辆通过时的结构振动和由此引起的声压,通过与现场实测结果的对比,验证理论方法分析桥梁振动辐射低频噪声机理的可能性。在此基础上进一步对路面平整性、车辆计算模型等参数的影响进行对比分析,探索路面以及车辆模型对计算结果的影响。结果表明,平整路面可以降低桥梁辐射低频噪声的强度;采用不同的车辆模型对计算得到的声压有一定的影响;为了提高精度需要对高频范围内的桥梁振动计算方法、非平稳信号分析以及声波在边界上吸收、反射等方面进行进一步改进。 展开更多
关键词 桥梁振动 空气波传播 低频噪声 交通振动
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