Shields

About: Shields is a research topic. Over the lifetime, 1456 publications have been published within this topic receiving 10896 citations.

Armor, shields and helmets with highly property-mismatched interface materials to reduce dynamic force and damage

Abstract: Armor/shields/helmets including highly property-mismatched interfaces (mismatch level of bulk materials and interfaces more than 60%) are disclosed, which provide protections against external dynamic loading such as blast loading, impact of projectiles and sharp-edged foreign objects. The mechanism to reduce dynamic force and damage is a specific material design using soft and ductile interfaces/adhesive layers to 1) bond or hold other layers/bulk materials with blast/impact/stab resistance, 2) reduce stress wave transmission and the maximum dynamic force, 3) decrease shear deformation of the inner layers behind interfaces, and 4) dissipate more energy due to blast and impact along the armor/shield/helmet surface. Therefore, less energy would be available to contribute to penetrate the armor/shields/helmets, or cause damage.

Force and torque model sensitivity and coarse graining for bedload-dominated sediment transport

Abstract: We present results from Euler–Lagrange simulations of turbulent flow over an erodible monodisperse bed of particles at a shear Reynolds number of R e τ = 180 . The Galileo number G a and the ratio of Shields to the critical Shields number Θ / θ c r were varied in the range 11.4 to 29.8 and 1.32 to 5.98, respectively. Two drag force models were investigated along with the influence of lift, particle rotation, and tangential collision forces for each model. Both models give similar results as far as mean particle flux and Shields stress are concerned, however we find that excluding particle rotation, without ignoring the associated tangential collisional force, significantly reduces the particle flux with little influence on Shields stress. On the other hand, when both particle rotation and tangential collision forces are not taken into account, the particle flux is practically unchanged, but the excess Shields stress slightly increases compared to the case where both effects are considered. We also find the lift force to substantially influence particle flux. Additionally, we show the importance of spatial coarse graining and time averaging for Euler–Euler simulations and quantify the reduction in scatter for space and time dependent variables such as sediment flux, Shields stress, and bed surface fluid velocities.

Device for fast neutrons radiation cancer therapy

Abstract: FIELD: medical equipment. ^ SUBSTANCE: invention relates to medical equipment, in particular to the devices for cancer fast neutrons radiation therapy; the device comprises the neutrons generator surrounded from above by the shield protecting from the broad beams of boronized polyethylene; the generator located against the biological shield on the same axle with the built in it neutron channel; the device is also equipped with the functional shield; the biological and functional shields are performed in the shape of adjacently placed stunned cones with a big footing from the side of the outlet aperture of the neutron channel and a smaller one - from the side of the neutrons generator; the shields are executed fungible from the same material or composite consisting of the parts in the shape of blunted cones put one inside the other, at that the parts of the biological shield and/or functional shield are made fungible or have interstratified layers; the biological and functional shields or their parts are made of metal or metal hydrides or metal alike substances or porous materials containing light nucleuses or hydric compositions; herewith the radius of the inlet aperture of the neutron channel and of the thickness of the biological and functional shields is selected on the basis of the conditions of provision of the therapeutic efficiency determined by the formula F=D/L, wherein D is the distance from the back edge of the outlet channel of the neutron channel on the surface of the shield to the point whereat the kerma counts to 20% of the kerma in the beam center, and L is the distance passed by the fast neutron without interacting with the shields materials up to the point whereat the kerma amounts to 20% of the kerma in the beam center. ^ EFFECT: application of the invention allows to enhance the operation characteristics of the device due to the creation of the optimal shaper of the radioactive fields and the requisite radiation protection of the patient. ^ 9 cl, 4 dwg.