Experimental laws of cratering for hypervelocity impacts of spherical projectiles into thick target

It is shown in this paper that the laws of cratering in a thick target under hypervelocity impact by a spherical projectile can be approximately expressed by the so-called iso-deviation law and a 2/3 power law. Moreover, hypervelocity impact should be characterized by the isotropic expansion of a crater. In the special case, when the projectile and target are of the same material, the laws mentioned above reduce to the result of a semi-spherical crater and the energy criterion. Generally speaking, a semi-spherical crater and the energy criterion are both approximations, which only take projectile density and target strength into account, and can be used for a rough estimation on the order of magnitude. The inconsistency in various fitted power laws in the literature was also clarified and explained in the paper.

Ad valorem housing subsidies may reduce house building

In this paper it is shown that an ad valorem housing subsidy set by a central regulator (or a raise in the ad valorem housing subsidy rate) may reduce the number of houses built in the market and increase the price paid by the buyers of houses. The analysis considers a situation where there is imperfect competition in the housing market and a local regulator that decides on density, or on the number of sites for housing development, and that cares about a combination of the profits of housing developers and the surplus of buyers of houses.

Consensus-building process

(4pp.)