Effects of a One-Day Krav Maga Training: Early Stages of Skill Acquisition of a Krav Maga Kick and Punch

Krav Maga (KM), inspired by various forms of martial arts, is a form of self-defence training intended to teach civilians the necessary techniques required to fight against street violence. KM offers self-defence training in over 70 countries to a variety of populations. Moreover, in countries such as U.S.A and France, KM is an integral part of the military and police training. Although many forms of martial arts have been studied for decades, theres few mentions of KM in the current literature. The current study investigated the effectiveness of a 30-minute instructional session among seventeen female volunteers. The participants displayed a 42% increase in kick peak force when compared to their baseline. This change in performance is most likely associated with KM instruction and is perhaps demonstrating characteristics of learning among novice

Determination of atomic-scale structure and compressive behavior of solidified AlxCrCoFeCuNi high entropy alloys

The atomic configurations play a key role in predicting the solidification process of high-entropy alloys (HEAs). The atomic scale structures of AlxCrCoFeCuNi (x = 0.5, 1.5, 3.0) HEAs that emerge during solidification with a cooling rate of 12 × 109 (K/s) are evaluated using molecular dynamics (MD) simulation. While BCC (body-centered cubic) structure is obtained for Al0.5CrCoFeCuNi and Al1.5CrCoFeCuNi where lattice distortion increases with increasing aluminum fraction from x = 0.5 to x = 1.5, for Al3.0CrCoFeCuNi, an amorphous structure is formed under the same cooling rate. The diffusion coefficient of all the elements at 2200 K and the super-heating temperature of each alloy are evaluated to explain the disordering mechanism due to aluminum addition, which affects both the aluminum mobility and diffusion of the constituent atoms in the HEA. Finally, the compression behavior of all the three HEAs was studied to show the effect of crystalline structure on the stress fluctuation. It was found that phase transformation induced plasticity occurred which led to a secondary hardening of crystalline alloys after ultimate compressive strength (UCS)

Nano-scale simulation of directional solidification in TWIP stainless steels: a focus on plastic deformation mechanisms

In this study, in order to understand the nanostructure of FeCrNi steels in the laser powder bed fusion (LPBF) process, directional solidification was simulated using largescale molecular dynamics simulation (LSMDS). For this purpose, an atomic box with a dimension of including random dispersion of Fe, Cr and Ni was created. Then, two different fixed temperatures were considered for the left and right side of the box during cooling from the liquid molten state. For evaluation of the uniformity in mechanical properties, uniaxial tensile tests were performed in the parallel and perpendicular directions. Extensive twinning induced plasticity (TWIP) occurred alongside Shockley partial dislocations (DLs) evolution in both directions, while different ultimate tensile strengths (UTS) were obtained as a sign of nonuniform tensile behavior. Different plastic deformation mechanisms at the nano-scale including stacking faults (SFs) interaction with each other/grain boundaries (GBs)/twin boundaries (TBs), formation of defective coherent twins (DCTs), dynamic Hall-Petch, shear stress gradient (back stress), and a new mechanism for dynamic recrystallization at room temperature are discussed in detail