Dynamic actions on bridge slabs due to heavy vehicle impact on roadside barriers

The use of roadside safety barriers in Italy has changed in recent years: the number of installed devices has increased, and so have their stiffness and resistance. These changes were necessary because early barrier design was inadequate to contain and redirect heavy vehicles. The change in barrier design led to an increase in stiffness and resistance; consequently, the action transferred to the structure by the device increased. The need for resistance on the bridge slabs can be too high because the peculiar action of the roadside barriers was not adequately taken into account in the oldest bridge design codes. In addition, characterizing the actions transferred to the bridge slab is difficult because of the dynamic nature of vehicle impacts on roadside barriers. Given the impossibility of performing a full-scale laboratory test for every bridge deck, the use of computational mechanics applied to dynamic impact/interaction problems is one of the best ways to establish these actions in the project phase. Research was conducted into the use of a three-dimensional finite element model of the bridge slab-barrier-vehicle system to perform a numerical simulation of the impact, according to the procedure used for the roadside barrier homologation crash test, described in the European Standard EN 1317

Model and design of a double frequency piezoelectric resonator

A novel design of a multifrequency mechanical resonator with piezoelectric materials for energy harvesting is presented. The electromechanical response is described by a finite element model, which predicts the output voltage and the generated powe

Book Review: War of Supply

Author: David D. Dworak Reviewed by Dr. John A. Bonin, consultant, US Army War College The reviewer notes, “While there are thousands of books about World War II, there are relatively few on the war in the Mediterranean and fewer on its logistics.” Dworak provides just that, with a chronological account of Operation Torch in North Africa; Operations Husky, Avalanche, and Shingle in Sicily and Italy; and Operation Dragoon in southern France.https://press.armywarcollege.edu/parameters_bookshelf/1031/thumbnail.jp

Impurity assisted nanoscale localization of plasmonic excitations in graphene

The plasmon modes of pristine and impurity doped graphene are calculated, using a real-space theory which determines the non-local dielectric response within the random phase approximation. A full diagonalization of the polarization operator is performed, allowing the extraction of all its poles. It is demonstrated how impurities induce the formation of localized modes which are absent in pristine graphene. The dependence of the spatial modulations over few lattice sites and frequencies of the localized plasmons on the electronic filling and impurity strength is discussed. Furthermore, it is shown that the chemical potential and impurity strength can be tuned to control target features of the localized modes. These predictions can be tested by scanning tunneling microscopy experiments.Comment: 5 pages, 4 figure