Recently, a large amount of studies have been related to nonlinear systems with multi-degrees of freedom as well as continuous systems. The purpose of this paper is to optimize passive vibration absorbers in linear and nonlinear states for an Euler-Bernoulli beam with a nonlinear vibratory behavior under concentrated moving load. The goal parameter in the optimization is maximum deflection of t...

Tomographic imaging is a technique for exploration of a cross-section of an inspected object without destruction. Normally, the input data, known as the projections, are gathered by repeatedly radiating coherent waveform through the object in a number of viewpoints, and receiving by an array of corresponding detector in the opposite position. In this research, as a replacement of radiographs, t...

Microaccelerometers using piezoelectric lead zirconate titanate (PZT) thin films have attracted much interest due to their simple structure and potentially high sensitivity. In this paper, we present a theoretical model for a microaccelerometer with four suspended flexural PZT-on-silicon beams and a central proof mass configuration. The model takes into account the effect of device geometry and...

The terahertz range of the electromagnetic spectrum reveals important insights when studying material properties. An ultra-broadband time-domain spectroscopy system based on state-of-the-art, high-stability organic nonlinear optical crystals used as both THz wave generator and detector is presented. In transmission geometry, a broad exceeding 20 high dynamic more than 80 dB achieved using compa...

Broadband enhancement of Raman signals is vital for molecular spectroscopy and sensing applications. However, typically, there a compromise between the resonance width local field factors. Here, we merge broadband open plasmonic cavity concepts with geometry exploiting narrow gaps reflecting layer. This results in metasurface design that maintains substantial electric confinement gap volume acc...

in this paper, eringen’s nonlocal elasticity and timoshenko beam theories are implemented to analyze the bending vibration for non-uniform nano-beams.  the governing equations and the boundary conditions are derived using hamilton’s principle. a generalized differential quadrature method (gdqm) is utilized for solving the governing equations of non-uniform timoshenko nano-beam for pinned-pinned...

Tomography in a focused ion beam (FIB) scanning electron microscope (SEM) is a powerful method for the characterization of three-dimensional micro- and nanostructures. Although this technique can be routinely applied to conducting materials, FIB-SEM tomography of many insulators, including biological, geological and ceramic samples, is often more difficult because of charging effects that distu...

A new single-pulse behaviour has been identified in two pulsars, B0919+06 and B1859+07. Normally both stars emit bright subpulses in a region near the trailing edge of their profile. However, occasionally these stars exhibit “events” wherein the emission longitude gradually decreases, by about their profile width, remains in this position for typically several tens of pulses, and then gradually...

Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, ...