Distributed fiber-optic vibration sensor using a ring Mach-Zehnder interferometer

A novel distributed fiber-optic vibration sensing system is proposed and demonstrated. By employing a ring Mach-Zehnder interferometer (MZI) structure as the sensing section, both position and frequency can be determined by combining two phase signals from the ring configuration. A spatial resolution better than 38 m is successfully verified in a 1.01 km prototype system of single vibration. Moreover, the feasibility of separately locating multiple vibrations is also theoretically simulated and experimentally investigated.     

关于图的团符号控制数

引入了图的团符号控制的概念,给出了n阶图G的团符号控制数γks(G)的若干下限,确定了几类特殊图的团符号控制数,并提出了若干未解决的问题和猜想.     

Research on performance indices of vibration isolation system

Power flow transmissibility is proposed as a performance index to evaluate the performance of isolation system. It is defined as the ratio of the power flow input into the equipment and the power flow transmitted into the receiver. Based on a simple vibration isolation system, its relationship with other performance indices is given by theoretical and numerical analysis. The results show that power flow transmissibility can reflect the response characteristics of the whole isolation system effectively. In addition, power flow transmissibility can be estimated easily according to vibration acceleration level difference and does not involve the measurement of power flow. Furthermore, the influences of several parameters such as the damping, loss factor and stiffness of isolator on power flow transmissibility are analyzed.     

Updated Standards of the International Society for Terrain-Vehicle Systems

The last version of the ISTVS standards was published in the Journal of Terramechanics in 1977. Since then, the document has not been updated, although new concepts, techniques, testing procedures, and technology have been developed in the last 40 years, which renders some content of the 1977 ISTVS standards outdated and in-complete. The ISTVS identified as a priority the need to develop a set of standards for terminology and testing for modern day research on off-road mobility. This paper, for which the work has been funded in part by ISTVS, is an updated version of the 1977 ISTVS standards and covers a range of aspects in off-road mobility for: vehicles, tires, tracks, soil, wheels, modelling approaches, test methods, and equipment.     

Tactile Response Characterization of a Dynamic System Using Craig-Bampton Method

Vibrational characteristics in small horizontal axis wind turbine system are presented in this study with a system concept called tactile response and substructuring. The main focus is on managing the dynamic properties like vibration, noise, and harshness that occur during the operational mode. Tactile response is defined as the response of subsystem which is induced when a human body touches a vibrating system. Sub structuring is a computational method used to reduce the dynamic behavior of a large complex system with a smaller number of degrees of freedom without disturbing the mesh size of the model. Sub structuring has the ability to combine numerical results along with the experimental results. Combination of substructuring and tactile response is applied in this study. Mode shapes of the system are analyzed and results obtained are correlated within this study to provide better optimization of the results. Wind turbine excited with wind energy depends on wind speed. Torsional vibration has a significant role in determining dynamic properties. Torsional vibration is caused as a result of the rotation of the turbine blade and depends on wind speed. The study gives importance to investigating the ability to simulate the numerical method and tactile response to predict and improve dynamic properties.     

函数值差的正和

本文给出了用有限的步骤做出有下界的振动函数的一个函数值差的正和的方法.     

Component-Mode Synthesis Method Variants in the Dynamics of Coupled Structures

The component-mode synthesis method is usually adopted in order to reduce the number of degrees-of-freedom of structures composed of two or more substructures without loosing the main physical characteristics of the whole structure. Many approaches of this method have been proposed in the literature. These approaches differ from each other for the boundary conditions which are imposed at the interface of the two substructures. In this paper four variants of interface boundary conditions are examined. For each set of conditions a suitable coordinate transformation, compatible with the conditions at the boundary degrees-of-freedom between the two substructures, is presented. Moreover, in the numerical applications a comparison between the four component-mode synthesis variants here proposed with respect to the same variants proposed in the literature is presented. The better accuracy of the proposed approach is shown.     

Blind separation of vibration signals and source change detection – Application to machine monitoring

The paper presents a new approach for machine vibration analysis and health monitoring combining blind source separation (BSS) and change detection in source signals. So, the problem is transferred from the original space of the measurements to the space of independent sources, where the reduced number of components is going to simplify the monitoring problem while the change detection methods are going to be applied for scalar signals. The assessment of the approach on a real machine is presented in this paper.     

Identification of winter tires using vibration signals generated on the road surface

During the winter, traffic regulations state that automobile drivers must use winter tires on unsafe roads such as snowy expressways. The present report is concerned with the development of an automatic tire identification system that can discriminate winter tires from summer tires with high accuracy. The system detects the impact vibration signal that is specifically generated by winter tires when tread blocks with wide grooves strike the road surface during rolling. The signal is picked up by a commercially available vibration sensor. If the signal contains specified impact frequency components, the tire is judged to be a winter tire. Compared with the previous identification system, which used airborne tire/road noise, the proposed system has two advantages. First, it is unaffected by meteorological factors such as wind noise. Second, the proposed system performs well even when the target vehicle is traveling at low speed. We evaluate the performance of the system outdoors using a number of vehicles with various tires and demonstrate an overall improvement in identification accuracy for vehicles traveling at low or moderate speeds.     

一种新型磨床振动频率测量系统设计

设计了一种新型的磨床振动频率测量系统,采用MMA8451Q微加速度计作为测量元件,使用高性能低功耗单片机MSP430F5529作为控制核心。系统用滑动平均滤波算法对信号进行了降噪平滑处理,计算出振动数据的“虚拟过零点”,以此为基础计算出振动的频率。通过在标准振动源上的标定实验验证了滤波算法的有效性和频率测量的准确性,误差在0.2Hz以内,引用误差为0.25%。最后在曲轴磨床上进行了实际测量实验,得出测量结果和理论计算结果是吻合的,证明了系统的可行性。