Celia H. Watson, Laurence Bates, and Ian Horsfall
The performance of 7.62×54r BS32 armour-piercing incendiary (API) projectiles against ceramic-faced armour is investigated in trials for yawed impacts. Controlled yaw of the projectile was induced by chamfering the rear of the projectile, producing strong asymmetric lift forces on the tail of the round during the intermediate ballistics phase. High-speed video recorded yaw in two orthogonal planes immediately before impact. Projectile yaw varied in a sinusoidal manner at approximately 3.5m wavelength with a maximum of 8–14° at approximately 10m from the muzzle. Logistic regression was used to determine the penetration probability curve and V50 ballistic limit velocity which was found to be 735 ms–1 for the un-yawed projectiles but only 685 ms–1 for the yawed projectiles.
Manfred Held
155 mm projectiles are detonated in a test arena with steel momentum plates of 30×50×2cm3 with 23.55 kg weight, positioned 1.25m above the ground where their achieved velocities are measured by the displacement distance on the ground. Although the impulse density results show a large scatter, they can be roughly described as exponential equations of the scaled displacements.
S. Veerabuthiran and A.K. Razdan
Remote detection of chemical warfare agents and toxic gases in the atmosphere is of current interest to both military and civilian agencies. Differential Absorption Lidar (DIAL) is a powerful technique for remote detection of such toxic agents in the atmosphere. This system uses two wavelengths—one corresponding to strong absorption characteristics of a toxic agent, and the other to weak absorption of that agent/gas molecule for detection at stand-off distances. In this paper, we present a theoretical estimation of design parameters of a DIAL system for detection of potential nerve and blister agents. A TEA CO2 laser-based system is considered as a transmitter and 500 mm cassegrain telescope as a receiver along with an MCT detection module. Our results reveal that a 100 mJ laser source is capable of detecting a few ppm concentrations of chemical warfare agents present anywhere between the ranges from a few metres to 1.5 km (range resolved measurements) to 5 km (co-operative target). The influence of interfering molecules of trace gases present in the atmosphere and the effect of the extinction coefficient on the maximum detectable range is also studied. The results show a significant reduction in the maximum detectable range.
Peter Dobias and Kevin Sprague
This paper outlines the use of two quantities, the fractal dimension and symmetropy, the latter a marriage of symmetry and entropy, that have been shown to be effective in describing key aspects of the spatial distribution of systems that display nontrivial spatial patterns and that are regulated by fractal statistics. Motivation for applying these two measures to the geographical distribution of violent incidents in Afghanistan from 2006 to 2009 was provided by previous studies suggesting that this conflict exhibits properties of a near critical system when violent incidents are viewed as a point process. In this paper, the (spatial) fractal dimension and symmetropy are computed for violent incidents in Afghanistan from 2006 to 2009 and noticeable changes are qualitatively linked to known events over the same time period. Overall, it was found that variations in the (spatial) fractal dimension were highly correlated with the data density and that variations in the symmetropy were largely anti-correlated with both. Both measures detected the presence of localized patterns, and symmetropy distinguished a strong pattern formation not related to density, suggesting a possible shift in the conflict dynamics.
James Wanliss, Peter Dobias, and Kevin Sprague
We have tested the hypothesis that combat related data in Afghanistan for the epoch 2002–2009 demonstrates features of a complex dynamical system. To detect long-term correlations in the presence of trends, we apply detrended fluctuation analysis (DFA), a modern technique for examination of complex systems, to systematically detect and overcome nonstationarities in the data at all time scales. In every instance strong power law correlations were found, and accurate scaling exponents were obtained. It was determined that a measure of predictability was inherent in the dynamics of the system. In other words, there is a history or memory in the signal so that the future dynamics are not random but statistically correlated with past events. We also found an interesting difference in the dynamics of different types of combat events, suggesting the likelihood of different command structure.
Trevor Manning, Microwave Radio Transmission Design Guide , Artech House, Norwood, MA, 2009.
