in this paper, the operation of helix traveling wave tube in interaction region is investigated by using a three dimensional large signal lagrangian model in frequency domain. the complete simulation of these tubes is essential for optimum design and minimum manufacturing cost. this 3d code can compute interception current (or current losses ), beam radius changes in interaction region and the ...

Abstract The grain boundary network of WC in WC-Co is important, as cracks often travel intergranularly. This motivates the present work, where we experimentally measure fracture energy Σ2 twist boundaries between crystals using a double cantilever beam opened with wedge under displacement control WC-10wt%Co sample. this type was compared cleaving { $$10\overline{1}0$$ <mml:math xmlns:mml="http...

In our previous publication, we identified novel gene candidates involved in shell formation by EST analyses of the nacreous and prismatic layer-forming tissues in the pearl oyster Pinctada fucata. In the present study, 14 of those genes, including two known genes, were selected and further examined for their involvement in shell formation using the RNA interference. Molecular characterization ...

A simple prismatic Timoshenko beam model with soil-structure interaction (SSI) is developed to approximate the dynamic linear elastic behavior of buildings. A closed-form solution with complete vibration modes is derived. It is demonstrated that building properties, including mode shapes, can be derived from knowledge of the natural frequencies of the first two translational modes in a particul...

Although the favored glide planes in hexagonal close-packed Zr are prismatic, screw dislocations can escape their habit plane to glide in either pyramidal or basal planes. Using ab initio calculations within the nudged elastic band method, we show that, surprisingly, both events share the same thermally activated process with an unusual conservative motion of the prismatic stacking fault perpen...

Evaluating the integrity of structures is an important issue in engineering applications. The use vibration-based techniques has become a common approach to assessing cracks, which are most frequently occurring damage structures. When involving inverse method, it necessary know influence position and geometry crack on modal parameter changes. crack, both size shape, defines severity (DS). In th...

there are several techniques in use for non-linear refractive index measurement, namely, interferometric techniques, in which conventional inter-ferometers are used, degenerate for wave mixing (dfwm), and z-scan, each of these techniques suffers from some shortcmings. for example conventional interferometers like fabry-perot and twyman-green need high quality optical components, unwanted reflec...

In this study, the effect of channel-bed slope and non-prismatic converging channel on discharge coefficient labyrinth weirs is numerically investigated utilizing FLOW-3D model. Numerical simulation results show that modifying weir through both methods improves coefficient. Among selected bed slopes wall, β=4% angle θ=10° yielded highest For a ratio HT/P=0.1, (HT: flow height, P: height) rate f...

We describe the synthetic preparation of well-defined symmetric multifaceted prismatic silver nanoparticles with chemically controlled faceting advantageous for strong and tunable surface-enhanced Raman scattering, SERS. These silver nanoparticles, that have been termed nanoflowers, AgNFls for their characteristic morphologies, have been prepared by a one-pot aqueous reaction under ambient cond...