Search results for "Ballistic"
showing 9 items of 49 documents
Ceramique/metal component elaborated by flash sintering for ballistic protection
2012
This dissertation describes the synthesis of new components for ballistic protection with the assistance of flash sintering. Indeed, the objective is to associate two compounds showing very different sintering temperatures – such as alumina and aluminum, two reference materials for ballistic protection applications.The first synthesis method tested was the elaboration of a bi-material via the sintering of aluminump owder on alumina bulks. This study permitted to observe the formation of the alumina/aluminum bonding by scanning and transmission electron microscopy and to optimize the assembly parameters in order to obtain a bimaterials howing a strong interfacial cohesion. Adapted characteri…
Neural contribution to postactivation potentiation
2015
The current study was designed to investigate the contribution of neural factors to postactivation potentiation (PAP). Neuromuscular function (i.e. twitches, H-reflexes, motor evoked potentials, and voluntary isometric ballistic contractions) of 8 power-trained (POW) and 8 endurance-trained (END) athletes was recorded before and after a 8-second maximal isometric conditioning contraction (CC) to induce PAP, to elucidate discriminating neural factors in exploiting PAP that might arise from the former training background compared to the latter. After CC, twitch peak force and rate of force development were significantly increased, with higher potentiation in POW (29 ± 11% and 64 ± 24%) than E…
Generalized heat equation and transitions between different heat-transport regimes in narrow stripes
2019
Abstract In the framework of weakly nonlocal thermodynamic theory, in this paper we derive a nonlocal and nonlinear heat-transport equation beyond the Fourier law by means of thermodynamic considerations in agreement with the second law. The obtained equation describes the transitions among different heat-transport regimes. The stability of the solution of that equation is also analyzed in a special case.
Progress in THz Rectifier Technology: Research and Perspectives
2022
Schottky diode (SD) has seen great improvements in the past few decades and, for many THz applications, it is the most useful device. However, the use and recycling of forms of energy such as solar energy and the infrared thermal radiation that the Earth continuously emits represent one of the most relevant and critical issues for this diode, which is unable to rectify signals above 5 THz. The goal is to develop highly efficient diodes capable of converting radiation from IR spectra to visible ones in direct current (DC). A set of performance criteria is investigated to select some of the most prominent materials required for developing innovative types of electrodes, but also a wide variet…
On the limit velocity and buckling phenomena of axially moving orthotropic membranes and plates
2011
In this paper, we consider the static stability problems of axially moving orthotropic membranes and plates. The study is motivated by paper production processes, as paper has a fiber structure which can be described as orthotropic on the macroscopic level. The moving web is modeled as an axially moving orthotropic plate. The original dynamic plate problem is reduced to a two-dimensional spectral problem for static stability analysis, and solved using analytical techniques. As a result, the minimal eigenvalue and the corresponding buckling mode are found. It is observed that the buckling mode has a shape localized in the regions close to the free boundaries. The localization effect is demon…
Imaging for Ballistic Trauma: Other Applications of Forensic Imaging in the Living
2019
Firearms are mechanical instruments that allow launching remote specific bodies with mass (bullets) exploiting burst gas energy. The role of imaging for ballistic trauma is crucial in order to define the main characteristics for both judiciary and nonjudiciary purpose, which are the intracorporeal trajectory, the entrance and exit wounds, and the general characteristics of gunshot injuries.
The acute effects of different high-intensity conditioning activities on sprint performance differ between sprinters of different strength and power …
2021
The purpose of the present study was to examine the effect of different conditioning activities (CAs) on short-term increase in sprint performance. In twelve male sprinters (21.1+2.6 years, 100 m performance: 11.5+0.6 s) their body composition, half squat maximum strength, 100 m sprinting and countermovement jump performances were evaluated. The performance of a 50 m sprint (splits at 10 m, 30 m and 50 m) was evaluated before and 5, 10 and 15 min after four postactivation performance enhancement CAs on different occasions: [1] 3 sets x 4 s maximum isometric half squat (IHF), [2] 3 sets x 3 consecutive countermovement jumps (cCMJs), [3] 3 repetitions x 30 m overspeed sprinting (OVSP) and [4]…
Improved Maximum Strength, Vertical Jump and Sprint Performance after 8 Weeks of Jump Squat Training with Individualized Loads
2016
The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax) and rate of force development over 100ms (RFD100), countermovement jump (CMJ) and squat jump (SJ) height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg) were divided into experimental (EXP; n = 36) and control (CON, n = 32) groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets o…
Fractal dynamics in chaotic quantum transport
2013
Despite several experiments on chaotic quantum transport in two-dimensional systems such as semiconductor quantum dots, corresponding quantum simulations within a real-space model have been out of reach so far. Here we carry out quantum transport calculations in real space and real time for a two-dimensional stadium cavity that shows chaotic dynamics. By applying a large set of magnetic fields we obtain a complete picture of magnetoconductance that indicates fractal scaling. In the calculations of the fractality we use detrended fluctuation analysis -- a widely used method in time series analysis -- and show its usefulness in the interpretation of the conductance curves. Comparison with a s…