Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

In broadband coherent anti-Stokes Raman scattering （CARS） spectroscopy with supercontinuum （SC）, the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science.

Investigation into rail corrugation in high-speed railway tracks from the viewpoint of the frictional self-excited vibration of a wheel–rail system

A finite element vibration model of a multiple wheel-rail system which consists of four wheels, one rail, and a series of sleepers is established to address the problem of rail corrugation in high-speed tracks. In the model, the creep forces between the wheels and rail are considered to be saturated and equal to the normal contact forces times the friction coefficient. The oscillation of the rail is coupled with that of wheels in the action of the saturated creep forces. When the coupling is strong, self- excited oscillation of the wheel-rail system occurs. The self-excited vibration propensity of the model is analyzed using the complex eigenvalue method. Results show that there are strong propensities of unstable self-excited vibrations whose frequencies are less than 1,200 Hz under some conditions. Preventing wheels from slipping on rails is an effective method for suppressing rail corrugation in high-speed tracks.

桥梁抗风型TMD对车-桥耦合振动系统减振性能研究

为研究桥梁抗风型调谐质量阻尼器(tuned mass damper, TMD)对车辆荷载引起结构振动的减振效果,并揭示车载作用下的TMD激振机理,提出了基于模态动能演化的多自由度结构TMD控制方法,确定了安装TMD的最优设计参数和布设位置;考虑桥梁有限元模型动力求解的通用性,基于桥梁三维动力分析系统BDANS软件建立了车-桥-TMD动力耦合分析系统;以经典单自由度移动弹簧质量过简支梁模型为研究对象,分析了车-桥-TMD系统振动特性,结合某深水区非通航桥梁抗风型TMD工程实例分析了TMD对车致振动的减振效果和机理。研究结果表明:TMD行程幅值与减振效果呈现正相关特点,即行程幅值越大对车-桥动力效应引起的振动减振效果越好;安装TMD可以显著提高结构的等效阻尼比,满足等效阻尼比>1%的工程需求,提高桥梁结构振动的稳定性;TMD在一定条件下可以减小车辆通过时引发桥梁竖向位移冲击效应,最大可减少3%左右;TMD对车-桥2个子系统的加速度瞬态峰值均起到了一定的抑制效果,尤其对桥梁结构竖向振动加速度作用效果明显,安装TMD后的桥梁跨中竖向振动加速度RMS值减少约20%;对大跨钢箱桥梁而言,相比较小的车辆荷载冲击效应,一阶竖弯呈邻跨反对称特性的桥梁结构在车辆通行过程中更容易激起TMD,使桥梁结构获得更佳的减振效果。

Coupled extension and thickness-twist vibrations of lateral field excited AT-cut quartz plates

In this paper, the coupled extension and thickness- twist vibrations are studied for AT-cut quartz plates under Lateral Field Excitation （LFE） with variations along the x1- direction. Mindlin＇s two-dimensional equations are used for anisotropic crystal plates. Both free and electrically forced vibrations are considered. Important vibration characteristics are obtained, including dispersion relations, frequency spectra, and motional capacitances. It is shown that, to avoid the effects of the couplings between extension and thickness-twist vibrations, a series of discrete values of the length/thickness ratio of the crystal plate need to be excluded. The results are of fundamental significance for the design of LFE resonators and sensors.

Nanoscale mass sensing based on vibration of single-layered graphene sheet in thermal environments

Based on vibration analysis, single-layered graphene sheet （SLGS） with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysupported configuration. Based on the nonlocal plate the- ory which incorporates size effects into the classical theory, closed-form expressions lot the frequencies and relative fre- quency shills of SLGS-based mass sensor are derived using the Galerkin method. The suggested model is justified by a good agreement between the results given by the present model and available data in literature. The effects of tem- perature difference, nonlocal parameter, the location of the nanoparticle and the number of nanoparticles on the relative frequency shift of the mass sensor are also elucidated. The obtained results show that the sensitivity of the SLGS- based mass sensor increases with increasing temperature difference.

NMR Parameters and Vibrational Investigation of 2-Dicyanovinyl-5-(4-ethoxyphenyl) thiophene by ab initio HF and DFT Calculations

Optimized geometry and harmonic vibrational frequency of 2-dicyanovinyl-5-（4- ethoxyphenyl）thiophene （C16Hj2N2OS） are calculated at the HF/6-31＋＋G（d,p） and B3LYP/6- 311 ＋＋G（d,p） levels. Mulliken charges in the ground state are also calculated. The research shows the presence of intermolecular interaction in the title compound. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. A detailed interpretation of the infrared spectra of the title compound is reported. The theoretical spectrograms for IR spectra of the title compound have been constructed, The isotropic chemical shift computed by 13C and 1H NMR analyses also shows good agreement with the experimental observations.

Structural and Vibrational Study of 2-（Quinolin-8-yloxy）-Acetic Acid based on FT-IR-Raman Spectroscopy and DFT Calculations

We have prepared the 2-（quinolin-8-yloxy）-acetic acid and characterized it by infrared and Raman spectroscopies in the solid phase. The Density Functional Theory （DFT） method, together with the 6-31G^＊ and 6-311＋＋ G^＊＊ basis sets, show that three stable molecules, for the anhydrous and monohydrated compounds were theoretically determined in the gas phase, and that probably the two more stable conformations are present in the solid phase of the monohydrated compound. The harmonic vibrational wavenumbers for the optimized geometries were calculated at B3LYP/6-31G^＊and B3LYP/6-311＋＋G^＊＊ levels. For a complete assignment of all the observed bands in the vibrational spectra the DFT calculations were combined with Pulay＇s scaled quantum mechanical force field （SQMFF） methodology in order to fit the theoretical Wavenumber values to the experimental ones. The characteristics of the electronic delocalization of all structures of both forms were performed by using natural bond orbital （NBO）, while the corresponding topological properties of electronic charge density are analysed by employing Bader＇s atoms in molecules theory （AIM）.

基于3,5-二溴水杨醛席夫碱镍配合物-氧化石墨烯电化学免疫传感器检测Anti-IgG含量的研究

应用物理吸附法将羊抗人IgG抗原直接固定于3,5-二溴水杨醛席夫碱镍配合物-氧化石墨烯修饰的金电极表面,制备电化学免疫传感器。采用循环伏安法和交流阻抗法对传感器进行表征,结果表明该传感器适合检测Anti-IgG浓度。同时探讨了缓冲液pH值、扫描速度、免疫反应温度、抗原与抗体配比对循环伏安峰电流的影响,结果表明在5-100mV/s扫速范围内,峰电流与扫速呈线性。孵育最优条件为25℃,h-IgG与Anti-IgG配比为1∶1。循环伏安法研究还表明Anti-IgG浓度在0.01-260μg/L范围内,线性关系良好,相关系数r^2=0.993,检出限（S/N=3）为0.006μg/L,据此建立了检测Anti-IgG浓度的新方法。

信号分子IRAK1/4在antiβ-2GPI/β2GPI复合物诱导THP-1细胞表达TF中的作用探讨

目的:探讨IRAK1和IRAK4在antiβ-2GPI/β2GPI复合物诱导单核细胞株THP-1表达组织因子(TF)中的作用。方法:利用荧光定量PCR(Real-time PCR)、TF活性试剂盒分别检测THP-1细胞表达TF mRNA及TF活性;Western blot检测anti-β2GPI/β2GPI复合物诱导THP-1细胞表达IRAK1、磷酸化-IRAK1(p-IRAK1)、IRAK4情况;观察IRAK1/4抑制物是否干预anti-β2GPI/β2GPI复合物诱导THP-1表达TF。结果:Antiβ-2GPI/β2GPI复合物(100μg/ml)诱导THP-1细胞表达TF显著增加(P<0.05 vs control);Antiβ-2GPI/β2GPI复合物(100μg/ml)刺激THP-1细胞表达IRAK1、p-IRAK1、IRAK4(蛋白)显著升高(P<0.05 vscontrol);IRAK1/4抑制物(50μmol/L)能够阻断antiβ-2GPI/β2GPI复合物(100μg/ml)诱导THP-1表达TF及IRAK1磷酸化的效应。结论:antiβ-2GPI/β2GPI复合物诱导THP-1细胞表达TF过程中,信号分子IRAK1/4被激活进而发挥重要作用。

Seismic Sequence in Carbonate Rocks By Vibrational Liquefaction

On the basis of the records of strong seismic events taking place in soft carbonate sediments, a new seismic sequence system of vibrational liquefaction is established, which consists of a series of units, such as escaped structure of micrite veins and liquefied deformation formed in the period of seismic liquefaction, land subsidence structure after liquefaction, tsunamic hummocky and turbidite produced by seismic events, This sequence is a generalization and summation of field observation in vast areas, which shows the whole process of a strong seismic event and provides an unified theoretical explanation. The pattern of the seismic sequence by vibrational liquefaction provides one of correlation standards for geologists in the field to discriminate events in carbonate sequences. Based on the pattern of seismic sequence, the authors first advance a new conception of the Palaeo-Tanlu (Tancheng-Lujiang) Zone and discuss primarily its geological significations.

三维Anti de Sitter空间中Lorentzian曲面的S_t^1×S_s^1-值光锥Gauss映射的奇点分类

利用Arnol'd的Legendrian理论,对三维Anti de Sitter空间中Lorentzian曲面进行了研究.引入光维高度函数概念研究了三维Anti de Sitter空间Lorentzian曲面的S1t×S1s-值、光锥Gauss映射的奇点,进行了奇点分类,揭示了类光Causs-kronecker曲率之间的关系;并研究了Lorentzian曲面的一些基本几何性质.

Synchronization of three homodromy coupled exciters in a non-resonant vibrating system of plane motion

In this paper, the synchronization problem of three homodromy coupled exciters in a non-resonant vibrating system of plane motion is studied. By introducing the average method of modified small parameters, we deduced dimensionless coupling equation of three exciters, which converted the problem of synchronization into that of the existence and stability of zero solutions for the average differential equations of the small parameters. Based on the dimensionless coupling torques and characteristics of the cor- responding limited functions, the synchronization criterion for three exciters was derived as the absolute value of dimensionless residual torque difference between arbitrary two motors being less than the maximum of their dimensionless coupling torques. The stability criterion of its synchronous state lies in the double-condition that the inertia coupling matrix is positive definite and all its elements are positive as well. The synchronization determinants are the coefficients of synchronization ability, also called as the general dynamical symmetry coefficients. The double-equilibrium state of the vibrating system is manifested by numeric method, and the numeric and simulation results derived thereof indicate the indispensable and crucial role the structural parameters of the vibrating system play in the stability criterion of synchronous operation. Besides, by adjusting its structural parameters, the elliptical motion of the vibrating system successfully met the requirements in engineering applications.

Reducing force transmissibility in multiple degrees of freedom structures through anti-symmetric nonlinear viscous damping

In the present study, the Volterra series theory is adopted to theoretically investigate the force transmissibility of multiple degrees of freedom （MDOF） structures, in which an isolator with nonlinear anti-symmetric viscous damping is assembled. The results reveal that the anti-symmetric nonlinear viscous damping can significantly reduce the force trans- missibility over all resonance regions for MDOF structures with little effect on the transmissibility over non-resonant and isolation regions. The results indicate that the vibration isolators with an anti-symmetric damping characteristic have great potential to solve the dilemma occurring in the design of linear viscously damped vibration isolators where an increase of the damping level reduces the force transmissibility over resonant frequencies but increases the transmissibility over non-resonant frequency regions. This work is an extension of a previous study in which MDOF structures installed on the mount through an isolator with cubic nonlinear damping are considered. The theoretical analysis results are also verified by simulation studies.

Vibration analysis of axisymmetric functionally graded viscothermoelastic spheres

The present study focuses on the analysis of free vibrations of axisymmetric functionally graded hollow spheres. The material is assumed to be graded in radial di- rection with a simple power law. Matrix Frrbenious method of extended power series is employed to derive the analytical solutions for displacement, temperature, and stresses. The dispersion relations for the existence of various types of pos- sible modes of vibrations in the considered hollow sphere are derived in a compact form. In order to explore the character- istics of vibrations, the secular equations are further solved by using fixed point iteration numerical technique with the help of MATLAB software. The numerical results have been presented graphically for polymethyl methecrylate materials in respect of natural frequencies, frequency shift, inverse quality factor, displacement, temperature change, and radial stress.

DYNAMIC ANTI-PLANE PROBLEMS OF PIEZOCERAMICS AND APPLICATIONS IN ULTRASONICS—A REVIEW

We review theoretical results on anti-plane motions of polarized ceramics based on the linear theory of piezoelectricity. Solutions to dynamic problems of the propagation of bulk acoustic waves （BAW） and surface acoustic waves （SAW）, vibrations of finite bodies, and applications to various piezoelectric devices including piezoelectric waveguides, resonators, mass sensors, fluid sensors, actuators, nondestructive evaluation, power harvesters （generators）, transformers, and power transmission through an elastic wall by acoustic waves are discussed. Complications due to material inhomogeneity, initial stress, electromagnetic coupling, electric field gradient and semiconduction are also discussed. The paper cites 82 references.

Active Damping of Milling Vibration Using Operational Amplifier Circuit

The problem of chatter vibration is associated with adverse consequences that often lead to tool impairment and poor surface finished in a workpiece, and thus, controlling or suppressing chatter vibrations is of great significance to improve machining quality. In this paper, a workpiece and an actuator dynamics are considered in modeling and controller design. A proportional-integral controller(PI) is presented to control and actively damp the chatter vibration of a workpiece in the milling process. The controller is chosen on the basis of its highly stable output and a smaller amount of steady-state error. The controller is realized using analog operational amplifier circuit. The work has contributed to planning a novel approach that addresses the problem of chatter vibration in spite of technical hitches in modeling and controller design. The method can also lead to considerable reduction in vibrations and can be beneficial in industries in term of cost reduction and energy saving. The application of this method is verified using active damping device actuator(ADD) in the milling of steel.

Selective excitation of molecular mode in a mixture by femtosecond resonance-enhanced coherent anti-Stokes Raman scattering spectroscopy

Femtosecond time-resolved coherent anti-Stokes Raman scattering （CARS） spectroscopy is used to investigate gaseous molecular dynamics. Due to the spectrally broad laser pulses, usually poorly resolved spectra result from this broad spectroscopy. However, it can be demonstrated that by the electronic resonance enhancement optimization control a selective excitation of specific vibrational mode is possible. Using an electronically resonance-enhanced effect, iodine molecule specific CARS spectroscopy can be obtained from a mixture of iodine-air at room temperature and a pressure of 1 atm （corresponding to a saturation iodine vapour as low as about 35 Pa）. The dynamics on either the electronically excited state or the ground state of iodine molecules obtained is consistent with previous studies （vacuum, heated and pure iodine） in the femtoseeond time resolved CARS spectroscopy, showing that an effective method of suppressing the non-resonant CARS background and other interferences is demonstrated.

INVESTIGATION OF VORTEX SHEDDING INDUCED HYDRODYNAMIC VIBRATION IN VORTEX STREET FLOWMETER

Vortex street flowmeter has been used in steady flow measurement for about three decades The benefits of this type of flowmeter include high accuracy,good linearty,wide measuring range,and excellent reliability However,in unsteady flow measurement,the pressure disturbance as well as the noise from the system or surrounding can reduce the signal to noise ratio of the flowmeter seriously Aimed to use vortex street flowmeters in unsteady flow measurement,the characteristics of the vortex shedding induced hydrodynamic vibration around the prism bluff body in a vortex street flowmeter are investigated numerically and by expriments The results show that the hydrodynamic vibrations with 180° phase shift occur at the axisymmetric points of the channel around the bluff body The most intense vibration occurs at the points on the lateral faces close to the base of the prism The results provide therefore a useful reference for developing an anti interference vortex flowmeter using the different ial sensing technique.

负刚度-惯容阻尼器对隔震结构减震性能提升研究

为进一步控制地震作用下基础隔震结构的地震响应,融合负刚度与惯容的减震优势,开展了负刚度-惯容阻尼器(Negative Stiffness Inerter Damper,NSID)对隔震结构减震性能提升研究。基于NSID-隔震结构耦合系统的状态空间方程,推导了Clough-Penzien谱输入下耦合系统随机地震响应;综合NSID设计成本和隔震结构减震性能提升需求,提出了基于成本控制的NSID参数优化方法;通过对比NSID、黏滞阻尼器(Viscous Damper,VD)、负刚度阻尼器(Negative Stiffness Damper,NSD)、惯容阻尼器(Viscous Inerter Damper,VID)对隔震结构在近场脉冲型地震作用下的控制效果,阐明了NSID对隔震结构减震控制的优势。研究结果表明:基础隔震复合NSID的减震措施可以有效降低隔震结构的隔震层位移,以及上部结构层间位移和绝对加速度响应;由于负刚度元件的存在,NSID对隔震结构位移的控制效果稍劣于VID,但优于NSD和VD;优化设计的NSID综合了惯容和负刚度对隔震结构层间位移和绝对加速度的控制优势,对隔震结构层间位移和绝对加速度的控制效果优于VD、VID和NSD。

On the Construction of Deepening Anti - corruption Mechanism

It needs the foundation of system and the guarantee of organizational system for anti-corruption,but it is more necessary to build and form an effective anti-corruption mechanism,so that the anti-corruption can be really put into practice. Anti-corruption mechanism refers to a organic operation system of the interaction,interconnection and constraint between the constituent elements( parts) and elements of national anti-corruption,and as a system,anti-corruption mechanism should have the characteristics of system aticness,comprehensiveness,transparency,legalization,public participation,scientific dynam ic,and internationalism. The construction of deepening anti-corruption mechanism is the need for reconstructing the ruling legitimacy of the party and the governm ent. Adhering to the principle of treating both root causes and symptoms is necessary in the construction of anti-corruption m echanism,com bating and punishing corruption is an important part of anti-corruption,and the prevention and control of corruption is the basic project of anti-corruption. Therefore,the construction of prevention and control mechanism in the anti-corruption mechanism has a more far-reaching significance.