Search

This paper investigates the effects of abrasion on the penetration of an ogival-nosed projectile into concrete targets. A numerical procedure is constructed based on an abrasion model which is proposed based upon the experimental observations and a forcing function. The forcing function is a polynomial of the normal velocity which approximates the response of target and can be determined either empirically or theoretically or numerically. The proposed numerical procedure is easy to implement and can be used to calculate the time-histories of projectile velocity, penetration depth, deceleration, mass loss and its nose shape. It is found that the model predictions are in good agreement with available test data in terms of mass loss, penetration depth and nose shape change of the projectile.

From dynamic rupture simulations, we reveal under which conditions a rupture in the Groningen gas field stops along fault dip or along fault strike after it starts on a fault in the reservoir. The simulations focus on the capabilities of fault plane irregularities to arrest ruptures. Such irregularities can be recognised in sandstone outcrops. Fault planes in the Groningen field, extracted from the 3D seismic data by seismic attribute extraction methods, show similar irregularities. A detailed surface of a major fault plane in the field indicates that steps and jogs of tenths of metres are possible. Although these irregularities are close to seismic resolution and could be partially artificial, we investigated their effect on rupture arrest.

Weyl semimetals exhibit exotic properties owing to the presence of Weyl fermions. Here, Xu et al. show that tantalum phosphide is an ideal platform for studying the transport properties of these particles because its low-energy properties are dominated by a single type of Weyl fermion.

Weyl semimetals are a class of materials that can be regarded as three-dimensional analogs of graphene upon breaking time-reversal or inversion symmetry. Electrons in a Weyl semimetal behave as Weyl fermions, which have many exotic properties, such as chiral anomaly and magnetic monopoles in the crystal momentum space. The surface state of a Weyl semimetal displays pairs of entangled Fermi arcs at two opposite surfaces. However, the existence of Weyl semimetals has not yet been proved experimentally. Here, we report the experimental realization of a Weyl semimetal in TaAs by observing Fermi arcs formed by its surface states using angle-resolved photoemission spectroscopy. Our first-principles calculations, which match remarkably well with the experimental results, further confirm that TaAs is a Weyl semimetal.