Target classification is one of the most important issues in battlefield situational awareness. As seismic signals are an effective means of obtaining such information, any knowledge of the subsurface environment in which the target signal propagates is very important in either developing or fine-tuning classification algorithms. Seismic signal attenuation is an essential subsurface environment...

In the classic microseismic band of 5-20 s seismic noise consists mainly of fundamental mode Rayleigh and Love waves; however, at shorter periods seismic noise also contains a significant amount of body wave energy and higher-mode surface waves. In this study we perform a global survey of Earth’s short period seismic noise field with the goal of quantifying the relative contributions of these p...

An empirical, energy-based methodology for liquefaction hazard assessment and microzonation mapping is presented. The approach is probabilistic, considers the uncertainty in the liquefaction criterion, and is applicable to most earthquake-induced liquefaction analyses. The examples illustrated are for water-saturated sands at level ground. The energy of ground shaking is estimated from the Four...

It is shown that in perfectly quasi-isodynamic stellarators, trapped particles with a bounce frequency much higher than the frequency of the instability are stabilizing in the electrostatic and collisionless limit. The collisionless trapped-particle instability is therefore stable as well as the ordinary electron-density-gradient-driven trapped-electron mode. This result follows from the energy...

Abstract. Previously suggested definitions of averagely trapped surfaces are not welldefined properties of 2-surfaces, and can include surfaces in flat space-time. A natural definition of averagely trapped surfaces is that the product of the null expansions be positive on average. A surface is averagely trapped in the latter sense if and only if its area A and Hawking mass M satisfy the isoperi...

This paper describes a magnetic nozzle with a magnetic mirror configuration that transforms a collisionless subsonic plasma flow into a supersonic jet expanding into the vacuum. The nozzle converts electron thermal energy into the ion kinetic energy via an ambipolar electric field. The ambipolar potential in the expanding plume involves a time-dependent rarefaction wave. Travelling through the ...

The large processing requirements of seismic wave propagation simulations make High Performance Computing (HPC) architectures a natural choice for their execution. However, to keep both the current pace of performance improvements and the power consumption under a strict power budget, HPC systems must be more energy e cient than ever. As a response to this need, energye cient and low-power proc...

in many seismological applications, the earth is considered as a perfectly elastic, homogeneous, and isotropic body. although this assumption is approximately valid, it is known that seismic waves pass through the real earth that is anelastic, inhomogeneous and anisotropic.  we consider four processes that can reduce wave amplitude, i.e.: geometrical spreading, scattering, multi-pathing, and an...

According to modern seismic codes, in concentrically braced frames the seismic input energy should be dissipated by means of the hysteretic behaviour of braces while all the other members (i.e. beams and columns) have to remain elastic. Accordingly, the design internal forces of braces are determined in these codes by elastic analysis of the structure subjected to seismic forces obtained by the...