XY2型分子伸缩振动与弯曲振动耦合研究

本文研究一种推广的局域模模型，我们用局域坐标描述非线性ＸＹ２分子的伸缩振动，用简正坐标描述弯曲振动；对用曲线内坐标写出的势能函数和Ｇ矩阵元进行Ｔａｙｌｏｒ展开，保留了弯曲振动与伸缩振动耦合的交叉项，获得各阶哈密顿量，略去了五次以上的高阶项；用它对实验数据进行非线性最小二乘法的拟合，得出各个势能参数值，并用它们计算了Ｈ２Ｏ分子的振动光谱，计算结果与实验数据符合得较好。     

复摆的振动分析

研究复摆的非线性振动，从能量和摆角两个方面来分析它们对复摆运动的影响，用第一类完全椭圆积分求出了复摆振动的解和周期，对非线性特征进行了分析。     

高功率超声脉冲激励下金属板的非线性振动现象研究

对高功率超声脉冲作用下金属板中的超谐波、次谐波、准次谐波以及混沌等非线性振动现象进行了实验和理论研究.在实验中,高功率超声换能器产生脉冲调制的高频振动激励金属板产生非线性振动,利用激光测振技术测量不同尺寸和不同固定方式下金属板复杂的非线性振动情况,并对其进行了时序分析、频谱分析以及相空间分析.根据实验条件,提出包含非线性接触阻尼的振动-碰撞动力学模型,用以研究强超声振动-碰撞作用下的板非线性振动机制,并进行了相应的理论计算.计算结果表明,超声换能器的变幅杆与金属板之间的间歇性高频碰撞作用是金属板强非线性振 关键词： 非线性板振动 强超声脉冲激发 振动-碰撞动力学     

组合线性弹簧振子中的非线性振动

从拉格朗日方程出发,分析了几种常见的线性弹簧组合,对作非线性振动弹簧振子进行了数值求解.当作微小振动时,正好是几种典型的非线性振动.通过计算得出解析解并与数值解进行了对比.     

三质点单自由度非线性振动特性分析

设计一个非线性振动实验装置，建立系统的动力学方程，用计算机数值计算并画出相图和运动图，对非线性振动的性质进行了分析。     

基于MATLAB的非线性振动系统临界阻尼的研究

用MATLAB研究了非线性振动系统临界阻尼的性质,提出了非线性振动系统临界阻尼的计算公式和临界阻尼状态下系统的运动方程,并与数值解进行了比较.     

纸张振动中的整数与分数振动

本文使用微扰论方法对纸张振动建立非线性动力学方程模型，通过该模型预测纸张产生的低音与高音现象以及它们之间的联系，并通过实验验证.该模型的非线性动力学方程中存在与低音解相关的分数倍频解，这与实验中存在的分数倍频振动现象相吻合.该模型解释了整数倍频高音产生的非线性本征性以及分数频低音与分数倍频高音产生的衍生性，实验结果中的整数振动与分数振动现象满足理论预测.     

水的非线性振动能谱的自陷理论计算

用非线性自陷方程的动力学理论计算了水分子、液体水和水蒸汽等的ＯＨ和ＨＯＨ键的非线性振动的量子振动能谱，所得结果与实验值符合得较好，也比简正模式和局域模式的结果较好． 关键词：     

一类非线性弹簧振子的振动特性分析

设计了一个非线性振动实验装置 ,建立了质点的动力学方程 ,用计算机数值计算并画出运动图、能量图和相图 ,对非线性振动的特点进行了分析     

规范变换对求解强耦合非线性振动近似解的应用

本文利用规范变换将谐振子的哈密顿量变换成非线性型，然后将其应用于求非线性强耦合振动的近似解。     

某型振动轮噪声数值模拟及优化分析

空中声源的辐射噪声谱包括宽带连续谱和窄带线谱,线谱能量高于连续谱。与水下声源相比,空中声源的运动速度普遍较高,线谱多普勒频移明显,可用于进行水下对空中声源的运动参数估计。首先通过时频分析提取接收信号的瞬时频率,而后利用非线性最小二乘法将瞬时频率提取值与预测值相拟合,进而估计声源的运动参数(声源的运动速度、静止频率、与接收器最小水平距离及经过最近点时刻)。仿真与实验均能较为准确地估计出声源运动参数,同时在实验中实现了水下对空中运动声源的测距和定位,测距误差小于15.8%。在满足一定信噪比和保证足够多普勒信息的情况下,该参数估计方法具有很好的适用性。     

不同边界条件下一维双原子链的晶格振动

在自由边界条件和驻波边界条件下，讨论分析了一维双原子链晶格振动的振动模和色散关系，并与周期性边界条件下的结果进行了比较；明确了在不同边界条件下讨论实际原子链晶格振动的振动模和色散关系，其结果是相同的。     

Vibration in dwellings from road and rail traffic — Part II: exposure-effect relationships based on ordinal logit and logistic regression models

The 1998 Norwegian Socio-vibrational Survey with 1503 respondents from 14 study areas was undertaken in the autumns of 1997 and 1998. Telephone interviews were used for obtaining people's reactions to vibrations in dwellings while in-dwelling vibration values were calculated for 1427 of these respondents. The response rate was 50%. The calculations of the vibration values were based on measurements and calculations by using a semi-empirical vibration prediction model. The logarithmic transformation of the calculated statistical maximum vibration value v_w,95 as defined in the new Norwegian Standard NS 8176, was selected as exposure measure. There were no significant differences in reactions to vibrations from different sources. An estimated exposure-effect ordinal logit model for degrees of annoyance as a function of the vibration exposure measure shows good fit and narrow statistical error bands. Further studies are needed to determine whether the exposure measure should also include the number and duration of vibration events.     

Effect of Different Local Vibration Frequencies on the Multiscale Regularity of Plantar Skin Blood Flow

Local vibration has shown promise in improving skin blood flow (SBF). However, there is no consensus on the selection of the best vibration frequency. An important reason may be that previous studies utilized time- and frequency-domain parameters to characterize vibration-induced SBF responses. These parameters are unable to characterize the structural features of the SBF response to local vibrations, thus contributing to the inconsistent findings seen in vibration research. The objective of this study was to provide evidence that nonlinear dynamics of SBF responses would be an important aspect for assessing the effect of local vibration on SBF. Local vibrations at 100 Hz, 35 Hz, and 0 Hz (sham vibration) with an amplitude of 1 mm were randomly applied to the right first metatarsal head of 12 healthy participants for 10 min. SBF at the same site was measured for 10 min before and after local vibration. The degree of regularity of SBF was quantified using a multiscale sample entropy algorithm. The results showed that 100 Hz vibration significantly increased multiscale regularity of SBF but 35 Hz and 0 Hz (sham vibration) did not. The significant increase of regularity of SBF after 100 Hz vibration was mainly attributed to increased regularity of SBF oscillations within the frequency interval at 0.0095–0.15 Hz. These findings support the use of multiscale regularity to assess effectiveness of local vibration on improving skin blood flow.     

空化流动诱导离心泵低频振动的实验研究

空化流动严重影响泵安全稳定运行,为充分认识泵内空化发展程度及其诱导的低频振动特性,设计了一台离心式模型泵作为研究对象,同时采用高速摄影及振动加速度测试手段,实现了叶轮内部空化流动的可视化及对应的泵体低频振动信号提取,分析了空化泡形态随空化发展的演化规律,对比了空化发生前后泵体低频振动频谱特性,探讨了泵体总振级水平、离散频率下振动加速度幅值随空化发展程度的变化,提出振动临界汽蚀余量可作为空化程度的另一判据,叶频时的振动加速度幅值变化亦可作为泵内空化程度的表征。     

高频振动模糊图像仿真与分析

研究了运动模糊图像在空间域和频域上的数学模型,根据运动图像的模糊原理,提出了时间等分运动模糊图像的仿真方法,仿真了高频振动模糊图像.理论分析指出,物体做高频谐波振动时运动模糊成像的频谱会由于Bessel函数的零点的存在而形成系列条纹,对振动模糊图像的频谱做两次Radon变换能检测出振动的方向和振幅,从而得到高频振动模糊...     

Study on rectangular ultrasonic radiator of flexural resonant vibration in high modes

Based on the theory of coupling vibration and flexural vibration of thin rod of rectangular cross section, the fiexural vibration of rectangular thin plate was studied. The frequency equation was derived under the condition of freeboundaries. The normal modes and the relation between the normal modes and the resonant frequency were obtained. Experiments showed that the calculated resonant frequencies agree well with the measured results, and the rectangular thin plate in flexural vibration has abundant resonant frequencies. The radiator of flexural vibration used in ultrasonic cleaning and other techniques has the advantages of large acoustic radiating area, uniform acoustic field and easy adjustment of resonant frequencies, proving that it is a promising ultrasonic source.     

怠速工况下燃油系统的噪声评价和改善*

在实车怠速工况下的噪声振动性能评价过程中,燃油系统是发动机诸多子系统当中一个重要的声源。针对这一子系统产生的车内脉动噪声偏大的问题,总结出了对燃油类液体的脉动噪声振动控制机理、原因及诊断方法。首先,采用在燃油轨内追加阻尼器的方案很好地抑制了谐频噪声;然后,从燃油泵这一主要激振源出发,提出了设定燃油泵单品噪声振动、声品质等目标值的策略,即从源头上控制关键产品的噪声性能。在此基础之上,与之相应的解决方案实施之后,怠速工况下的车内噪声提升到了较好的水平,而且,燃油系统噪声的主观评价结论也认为得到了明显改善。     

Improving Melt Flow Behavior via Melt Vibration

A self‐made melt vibration extrusion device was used to study the melt flow behavior in a vibration field. A pulse pressure was superimposed on the flowing melt during extrusion, called vibration assisted extrusion (VAE); conventional extrusion (CE) was studied for comparison. A die (L/D=17.5) was attached to the device to study melt flow behavior of an amorphous polymer (polystyrene) and semi‐crystalline polymers (high density and linear low polyethylene). Results show that the melt vibration technique is an effective processing tool to improve polymer melt flow behavior for both crystalline and amorphous polymers. Increasing with vibration frequency for extrusion at constant vibration pressure amplitude, the viscosity decreases sharply, and also with increasing vibration pressure amplitude at a constant vibration frequency. The effect of vibration field on melt flow behavior depends greatly on the melt temperature, with the largest change in viscosity obtained at low temperature. Increasing with vibration frequency at constant pressure vibration amplitude, the maximum decrease percentages of viscosities are 82.9, 66.7, and 48.9%, for HDPE, LLDPE, and PS, respectively; increasing with pressure vibration amplitude at a constant vibration frequency, the maximum decrease percentage of viscosities are 99.0, 94.3, and 99.0%, for HDPE, LLDPE, and PS, respectively.     

类声子晶体结构对超声塑料焊接工具横向振动的抑制

利用声子晶体的带隙理论以及耦合振动理论对大尺寸矩形超声塑料焊接工具的耦合振动进行了研究.在实际工程应用中,大尺寸工具的横向振动将严重导致工具头辐射面位移不均匀,影响系统的焊接质量及工作效率.为提高其工作效率,改善工具头辐射面位移的均匀程度,利用类声子晶体结构对大尺寸超声塑料焊接工具的横向振动进行抑制,分析并得出了类声子晶体结构的横向振动带隙,同时分析了工具头横向振动未抑制与抑制后其辐射面位移的大小与均匀程度.研究表明,通过合理设计类声子晶体的结构及尺寸,可以有效抑制超声塑料焊接工具的横向振动.不但改善了焊接工具辐射面纵向振动位移的均匀程度,而且提高了焊接工具的纵向振动位移幅度.