T continued functionality of a nation’s infrastructure systems, e.g. bridges, is a necessary pre-requisite to her continued social and economic development. However, in about 15 years, 50 percent of our bridges will be over 50 years old, inducing an unprecedented commitment of both financial and human resources. Hence, a successful Structural Health Monitoring (SHM) strategy, providing reliable...

The course on Mechanical Vibration is an important part of the Mechanical Engineering undergraduate curriculum. It is necessary for the development and the performance of many modern engineering products: automobiles, jet engines, rockets, bridges, electric motors, electric generators, and so on. Whenever a mechanical system contains storage elements for kinetic and potential energies, there wi...

A spatially dense wireless sensor network was designed, developed and installed on a long-span suspension bridge for a 3-month deployment to record ambient acceleration. A total 174 sets of data 1.3 GB were collected from 64 sensor nodes on the main span and south tower of the Golden Gate Bridge. Analysis of the vibration data using power spectral densities and peak picking provide approximate ...

A stochastic model of traffic excitation on bridges is developed assuming that the arrival of vehicles traversing a bridge modeled as an elastic beam follows a Poisson process, and that the contact force of a vehicle on the bridge deck can be converted to equivalent dynamic loads at the nodes of the beam elements. The parameters in this model, such as the Poisson arrival rate and the stochastic...

Semi-active control systems have been widely studied over the last 20 years. The range of applications includes automotive suspensions, seismic vibration mitigation, large bridges vibration control, knee prosthesis, among others. Semi-active actuators have a complex dynamics, and interaction between actuator and plant cannot be ignored in control design. This is specially true for magneto-rheol...

The development of low-cost wireless sensor networks has resulted in resurgence in the development of ambient vibration monitoring methods to assess the in-service condition of highway bridges. However, a reliable approach towards assessing the health of an in-service bridge and identifying and localizing damage without a priori knowledge of the vibration response history has yet to be formulat...

In this paper w e discuss three little known letters on the Konigsberg bridges problem. These letters indicate more clearly Euler’s attitude to the problem and to his solution of it.

Transient process spectroscopy has previously been thought to be applicable only to the analysis of intra-molecular processes. Two metal ion bridges used in the present work have allowed us to visualize real-time variations of the molecular vibration frequencies during photo-disproportionation inside bimolecule aggregates, which directly shows transient inter-molecular reactions.