Impact cratering in sand: comparing solid and liquid intruders

Crater characteristics are compared for droplet and solid ball impact on a granular target at the same effective impact energies.

Calculation of Dynamic Hardness by Molecular Dynamics

Based on the molecular-dynamic simulation of the impact of a solid ball on the surface of polycrystalline copper, a method for calculating the dynamic hardness of nanocrystalline materials is proposed. It is proposed to carry out the calculation of hardness by dividing the impact work by the squeezed volume. It is shown that this expression of dynamic hardness is consistent with Meyer hardness in the case of quasistatic indentation. As a result of this simulation, it is shown that under conditions when the diameter of the impactor decreases and approaches the crystal lattice constant of the target, the dynamic hardness increases. Also, in the calculations, the impactor density varied approximately twice, which was equal to the density of steel and the density of tungsten carbide. For a striker diameter of 5 nm, dynamic hardness increases with the speed of the striker and does not depend on its density.

Recovering a Rotation Matrix From Three Direction Cosines

In this paper, we propose a new parameterization method to represent rotation matrices using the angles ϕ→ recovered from the three direction cosines that lie on the diagonal. The map from the possible configuration space of the new variable ϕ→ to the solid ball model in axis-angle coordinates is constructed. We also introduce a bi-invariant metric and two left-invariant metrics for measuring the distance in configuration space which could be the foundation for path planning in ϕ→ space. We further analyze the Jacobian matrix and singularities to better understand the manipulability.

The Effect of AlCl3 and Ti on Hydrogen Storage Performance of 4MgH2-Li3AlH6 System

The AlCl3/Ti co-doped 4MgH2-Li3AlH6 has been successfully synthesized using solid ball-milled method. The effect of AlCl3/Ti and different preparation conditions on reversible hydrogen storage of 4MgH2-Li3AlH6 were investigated. It was found that the formed Al3Ti and Al can improve the de/rehydriding performance. The onset temperature of the system dehydrogenation decreased to 58 °C, and it can release hydrogen of 7.2 wt.% at 400 °C. The hydriding of the system was found that the adsorption rate greatly increased from 0.02 to 0.35 wt.% min-1. The activation energy (Ea) of MgH2 dehydrogenation decreased from 147 to 113.7 kJ mol-1 by adding additive AlCl3 and Ti. The AlCl3/Ti improved the thermodynamic and kinetic performance of the 4MgH2-Li3AlH6 composite, which was attributed to the high catalytic activity of Al3Ti and Al.

The principle of natural law show Complete Scientific Modeling" with its internet could inclusive of all human faith, knowledge and experience. The world peace come from all the personality together blooming and complement each other

This paper, based on Humankinds interdisciplinary and complete theory of mutual cognition publishing by china Xian Zhuang Publisher and The principle of cosmic life being multi-dimensional and simultaneously evolving Published by Frontier Science 2014 Vol. Issue 2 Chinaï¼ Abbreviation The principle of natural law. For example: The complete universe is a solid ball. All humans cognitions and certifications are this solid ball itself and each of its levels, angles, positions, interfaces... Presence Ways and Presence Relationships. When all humans cognitions and certifications, departure from their respective standpoint and attributes, reaches to each other's standpoint and attributes. That will become same one song played in different tones (as each other or each own). Otherwise people will each stick to their own limited area, disagree and no-inclusive other side. Basis on the above, The principle of natural law don't against any of human experience and knowledge. It clarifies all human cognitions and certifications where are they located at the system of universe, what people has been find out or not grasp yet. How could from people knowing arrival to their unknowing, and final build all human consensus. For help different disciplines reach consensus, The principle of natural law will combine with each disciplines examples, and follow three big basic theorem steps to show that same one song how could play with different tones.