A new structural wave number method to measure the dynamic characteristic parameters of viscoelastic damping material

For the viscoelastic damping material to possess excellent dissipating performance, it is crucial to obtain the dynamic characteristic parameters (DCP) of viscoelastic damping material exactly and effectively, and then to make it as input data for numerical analysis and design in the control of structural vibration. For this sake a new measurement method is presented to acquire the DCP of the viscoelastic damping material effectively in the manuscript. The properties of damping material can be achieved by substituting tested wave numbers or loss factor of composite viscoelastic damping beam (CVDB) into its inversion process of complex bending stiffness. In the present study, the loss factor of beam with unconstrained viscoelastic damping layer is measured by McDaniel and attenuation methods, respectively. And those results are compared with each other to certify the accuracy of test results firstly. Then influences of test conditions on loss factors derived from McDaniel method are studied to give some advices in the measurement. Finally the DCP of the viscoelastic damping material are obtained by the new method with complex wave number and compared with those obtained by using the resonance beam method. From the comparison it is concluded that the present proposed new approach can use limited samples to measure the DCP of the viscoelastic damping material in a wide range of frequencies effectively and conveniently

Design of a multicast router for network-on-chip architectures with irregular topologies

As chip complexity keeps increasing in system-on-chip (SoC), the on-chip interconnect has become a critical issue for large-scale chip design.It has been proposed that the packet-switched network exchanging messages between intellectual property (IP) cores is a viable solution for the SoC interconnect problem.The design of the router in such network-on-chip (NoC) architectures is the key to high-performance communication for the IP cores in SoC. In this paper, we present the design and implementation of a multicast router for NoC with irregular topologies.The router employs our previously proposed tree-based routing algorithm for irregular networks.Our experiment results show that the multicast router has a slightly lower clock rate and moderately larger chip area than the unicast router in NoC.Since multicasting is a technique providing superior network performance, especially for large networks, such multicast router design is an effective routing solution for large-scale network-on-chip architectures

An analytical approach to study the dynamic characteristic of beams carrying any type of attachments with arbitrary distributions under elastic constraint boundary supports

An analytical method to study the dynamic characteristic of free vibration of beams carrying any type of attachments with arbitrary distributions on elastic constraint boundary supports is developed in the paper. To obtain an exact solution of the governing function, the displacement function is expressed as a modified Fourier series based on the Euler-Bernoulli beam differential equation, which consists of a standard Fourier cosine series plus several supplementary series used to improve uniform convergence of the series representation. Compared with other techniques, the current method offers a unified solution to entire situations of beams carrying various types of attachments, regarding different distributions and arbitrary boundary conditions. The results of different numerical examples are compared with the results of the references to illustrate the excellent accuracy of the current solution and validate the methodology. Furthermore, the proposed analytical method can be directly extended to caculate the natural frequencies of beam on Pasternak soil and with distribution attachment varying with its length which is never studied before