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Pump–probe measurements of I2 in solid Ar are reported and analyzed to extract a description of cage response to impulsive excitation, from the gentle kick, up to the breaking point. The most informative data are obtained through wavepacket motion on cage-bound, but otherwise dissociative, potentials where the chromophore acts as a transducer to drive the cage and to report on the local dynamics. This general class of dynamics is identified and analyzed as a function of energy in Ar, Kr, and Xe. The overdriven cage rebounds with a characteristic period of 1.2 ps that shows little dependence on excitation amplitude in all hosts. After rebound, the cage rings as a local resonant mode in Ar, with a period of 1 ps and dephasing time of 3 ps. This mode remains at the Debye edge in Kr and Xe, with periods of 630 and 800 fs, and dephasing times of 8 and 6 ps, respectively. In the bound B-state, the cage fluctuates toward its dilated equilibrium structure on a time scale of 3 ps, which is extracted from the down-chirp in the molecular vibrational frequency. When kicked with excess energy of 4 eV, the Ar cage breaks with 50% probability, and the molecule dissociates. The kinetics of polarization selective, multiphoton dissociation with Gaussian laser intensity profiles is delineated and the ballistics of cage breakout is described: The photodissociation proceeds by destruction of the local lattice, by creating interstitials and vacancies. During large amplitude motion on cage-bound potentials, sudden, nonadiabatic spin–flip transitions can be observed and quantified in space and time. The spin–flip occurs with unit probability in Ar when the I*–I bond is stretched beyond 6 Å. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present an efficient method to calculate the ballistic transmission function and current of an arbitrarily shaped, multiterminal two- or three-dimensional open device. It is shown that the calculation of the energy dependent transmission function can be reduced to a single calculation of some stationary states of the isolated device and the inversion of a small matrix that is energy dependent. The size of this matrix is shown to be governed by the size of the boundary region between the leads and the device. The method that we term contact block reduction method is illustrated by a numerical example. [ABSTRACT FROM AUTHOR]

One of the most interesting problems of modern solid-state physics is the emission mechanism of bright photoluminescence in the red spectral range discovered in silicon nanocrystallite structures, particularly in wires and dots. This article presents an interpretation of strong "red" photoluminescence in silicon wires and dots based on hot carrier ballistic transport in the process of photoluminescence excitation. Photoluminescence (PL), its excitation, electron paramagnetic resonance, infrared absorption and Raman scattering spectra of as-prepared Si wires have been examined. Silicon wire layers (porous silicon) were obtained by electrochemical etching of p-type Si wafers in a HF-ethanol solution. An atomic force microscope is used for porous silicon morphology analysis. It is shown that the very low PL intensity could be attributed to carrier radiative recombination between localized states quantum confined inside Si nanocrystallites. It is revealed that the ballistic effect can enhance the effective hot carrier excitation of interface defect-related photoluminescence in Si nanocrystallite structures. PL excitation spectrum modification depending on the Si crystallite size confirms the role of the ballistic effect in PL excitation of Si low-dimensional structures. [ABSTRACT FROM AUTHOR]

Studies ballistic electronic transport in a proposed mesoscopic structure, quantum cable. Uniqueness of the structure quantum cable for the study of mesoscopic transport; Correlation between Fermi energy of electrons and ballistic conductance of quantum cable; Impact of the accidental degeneracies of the transverse subbands of quantum cable on the quantum conductance units.

Presents information on a study which examined the negative-effective-mass ballistic field-effect transistors. Ballistic carrier transport in diode structures; Ballistic carrier transport in gated structures; Numerical simulation procedure; Simulation results; Conclusions.

In support for the development of a new small-arm ballistic computer based on the NATO Armaments Ballistic Kernel (NABK) for the Canadian snipers, DRDC Valcartier Research Centre was asked to carry out high-fidelity 6 degree-of-freedom (6-DOF) trajectory simulations for a set of relevant vignettes for the snipers, and to compare the direct fire 6-DOF simulation results with those obtained with the 4-DOF NATO Armaments Ballistic Kernel (NABK) adapted to simulate small-arm ammunition trajectories. To conduct this study, DRDC Valcartier Research Centre used BALCO v1.0b. This paper presents (1) the process and the methodology employed to carry out the sniper direct fire solution study, (2) the modeling and the simulation of the sniper projectile, the approach used in calculating the firing solutions, and the results of direct fire simulations for the sniper vignettes, and (3) an analysis of firing solutions obtained with the BALCO engine versus those of NABK. The work presented in this paper serves to validate the use of NABK for the new sniper ballistic computer.

The study concerns a man-weapon interaction during a gunshot. The recoil force measurements obtained for the Kalashnikov automatic rifle are presented and analyzed. The influence of shooter’s mass, height and position is described. The breech pressure and projectile velocity data are presented as well. In addition, a finite element (FE) model of the shooter-rifle system is developed in order to qualitatively assess the quantities which could not be determined experimentally, i.e. the stress, strain and displacement fields which are generated in the human body due to the rifle recoil. Several conclusions are drawn that allow for better understanding of the recoil phenomenon and can be useful from the weapon designer’s point of view.

In this study, a new method based on regularised orthogonal matching pursuit (ROMP) decomposition is proposed to extract the feature of the ballistic target's rotating micro-motion. Based on the establishment of the ballistic target rotation model, the general model of target's narrowband radar echo is obtained. An over-complete dictionary of atoms is established by combining the intrinsic characteristics of the signal model, and the selection of the matched atoms is carried out according to the regularisation principle. The extraction of the target's rotating micro-motion feature and the reconstruction of the original signal are realised. Simulation results show that the method can extract the micro-motion feature efficiently and accurately.

Sabot asymmetric discard after the projectile being launched from the muzzle at various angles of attack and 4Ma is investigated. This is implemented by the coupling computational fluid dynamics (CFD) and six degrees-of-freedom exterior ballistic code through the unstructured dynamic mesh and user defined function. The flow field characteristics during sabot discard process and the trajectory parameters of all three sabots have been obtained. In addition, the aerodynamic coefficients of the projectile are also obtained. The numerical results show that the asymmetric discard of sabot is more obvious along with the increasing angle of attack. Moreover, the aerodynamic forces of projectile have a larger change and the pressure distribution of its surface is more asymmetric and complex. This means the aerodynamic interference at a non-zero angle of attack contributes more significantly to shooting dispersion and flight stability than that at zero angle of attack and the influence increases as the angle of attack increases.

Examines the calculation of the current-voltage (I-V) characteristics within the ballistic limit involving the metal-oxide tunnel transistors (MOTT). What the gate transconductance improves; Discussion on the saturation (knee) point and three modes of current transport across the device; How the low-voltage current saturation for MOTT is obtained.

In order to assess the efficacy of vacuum metal deposition (VMD) as a technique to develop fingermarks on ballistic metallic surfaces, a preliminary study using six donors (three male & three female) was conducted. Using a sequential metal deposition process, two metal combinations were studied—gold/zinc and silver/zinc. Results indicate the potential of this technique, by developing identifiable fingermarks on brass metal disks aged from a few days up to more than a month old. As the development of fingermarks on fired (brass) cartridge cases is an area of interest, a further study was conducted where a total of 20 fingermarks were deposited on cases. After firing, second level fingermark characteristics were successfully observed on cartridge cases highlighting its potential as a fingermark enhancement method for ballistic brass materials. Further work is required to fully evaluate the VMD process and its reliability as a fingermark enhancing method on ballistic surfaces. [ABSTRACT FROM AUTHOR]

The appearance of new projectile propulsion modes is viewed as an important element for understanding human behaviour during the Palaeolithic. Because the organic components of hunting weapons (the bow, spear‐thrower and arrow, and spear shaft) are only rarely preserved archaeologically, some effort has been invested in experiments to explore how the projecting modes could be identified through the analysis of stone points. The kinetic energy developed by each mode of propulsion has been considered a key variable in these experiments. However, the data used in these studies generally come from a few ballistic studies, with varied results. We present the results of a systematic study conducted with a ballistic pendulum and combined with a classic ballistic analysis. We quantified and compared the kinetic energy developed by the four standard modes of propulsion known for the Palaeolithic. The kinetic energy values that we attained, especially those measured for thrusting spears, clearly differ from what has been assumed up to now, and thus challenge current models on the evolution of hunting technology. [ABSTRACT FROM AUTHOR]

In the Renaissance new disciplines had reached scientific dignity thanks to the accuracy of mathematics. Some of these were: architecture, geography, ballistics and optics. In addition to mathematics there is another connection between these scientific fields; that is perspective as the scholar Daniele Barbaro highlighted throughout his career. The aim of this essay is to deal with the link between perspective and other disciplines to make the reader conscious of the importance that this subject assumed at Palladio's time. [ABSTRACT FROM AUTHOR]

This paper presents a method for obtaining time dependent back face deformation (BFD) data for body armor during ballistic impact using a clear ballistics gelatin backing and high-speed cameras to capture the deformation profile. Using this method, baseline fabric characterization data was obtained for samples comprised of varying layers of 467 g/m2 Kevlar K29 fabric impacted with 8.24 g steel ball projectile and backed with NATO standard 20% clear ballistics gelatin. For these tests, deformation depths were seen to increase with increasing impact energy and decreasing total areal density. A limited study of the various test parameters was performed by testing one additional fabric, projectile, and ballistics gelatin. From these comparisons, it was observed that 122 g/m2 Kevlar KM2+ fabric performs better per weight than 467 g/m2 Kevlar K29 fabric in terms of BFD, 9 mm FMJ projectiles produce deeper BFDs than 12.7 mm steel ball projectiles, and backing a sample with FBI standard 10% ballistics gel increases the BFD considerably over NATO standard 20% ballistics gel. [ABSTRACT FROM AUTHOR]

With no two gunshot wounds (GSW) being the same, novel research into wound ballistics is challenging. It is evident that the majority of previous wound ballistic research has been conducted without the presence of clothing. Whilst the effect of clothing on wound contamination has been explored, there is a paucity of literature examining the effect of clothing on GSW patterns. The aim of this study was to test the effect of Multi-Terrain Pattern (MTP) UK military clothing on GSW patterns within calibrated blocks of 10% by mass gelatine, using two types of ammunition commonly used in recent conflicts—7.62 × 39 mm and 5.45 × 39 mm. In total, 36 blocks were shot, 18 by each projectile type, further divided into 6 with no clothing layers (Cnil), 6 with a single clothing layer (Cmin) and 6 with maximum clothing layers (Cmax) worn on active duty. Blocks were analysed with high-speed video and dissection to capture measurements of damage, and results compared using analysis of variance (ANOVA). Results showed significantly different damage measurements within blocks with Cmax for both ammunition types compared to the other clothing states. This may result in GSWs that require more extensive surgical management, inviting further study. [ABSTRACT FROM AUTHOR]

Studies on ballistic trauma to the ribs and thorax, cranium, and long bones demonstrate the potential of obtaining a bullet caliber from an entrance wound. In order to validate prior research on caliber estimation in bone tissue and assess the viability of bullet type determination based on the macroscopic evidence at the entrance wound, thirty fleshed pork (Sus scrofa) shoulders (humeri) were shot with either lead or copper jacketed bullets in one of three calibers; 0.22, 9 mm, or 0.38. Overall, our findings are consistent with previous research indicating that calibers can be grouped into "small" and "large" categories. Bullet type, lead or copper jacket, can be ascertained based on cortical flaking and the analysis of materials deposited around the entry wound. The addition of this evidence holds value in cases where no firearm or ballistic evidence is recovered from a crime scene. [ABSTRACT FROM AUTHOR]

Firing accuracy is a critical quantity of interest in the performance analysis of electromagnetic railgun (EMRG) exterior ballistics. Since the simulation technique is always used to simulate the complex physical system at a low cost, it is employed to evaluate the firing accuracy of railgun projectile with uncertainty in this paper. An exterior ballistics simulation model of the railgun, including 3-DOF flight mechanical model, relative kinematic model, and guidance law model, is developed to simulate the ballistics behavior in the missile target intercept mission. The firing accuracy is studied in this paper to compare the capability of EMRG with different ranges and muzzle velocities. In order to explore the firing accuracy of the guided projectile, the guidance precision analysis and ballistics uncertainty quantification are studied. In the guidance precision analysis, the shot range and efficiency are used to make a comparison. In addition, the sensitivity analysis and firing accuracy analysis are also performed in terms of uncertainty quantification. The simulation results illustrate that the simulation of the guided projectile can give some practical guide to the projectile design of EMRG. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics is becoming a key tool for reducing the hybrid rocket operation uncertainties and development cost, but numerous challenges, due to the complexity of modeling the solid fuel consumption mechanism and the interaction with the reacting flowfield, have still to be addressed. These latter features are further complicated with paraffins for the melted-fuel entrainment phenomenon. This paper presents a computational thermo-fluid-dynamic model of the internal ballistics of hybrid rockets burning gaseous oxygen and paraffin-based fuel. With the purpose of predicting the local fuel regression rate, the model is coupled with an improved gas/fuel-surface interface treatment based on local mass, energy and mean mixture fraction balances, combined to an additional analytical equation for the calculation of the entrainment fraction of the fuel consumption rate. Parametric analyses are carried out to assess the effect of fuel properties on the regression rate. Several experimental test cases, obtained from static firing of a laboratory-scale rocket, are simulated. Calculated regression rates show an error with respect to the measured data around 10% in the worst case. Chamber pressure is predicted with lower accuracy, with errors less than 20%; the main factor of deviation is shown to be the estimation of the combustion efficiency. [ABSTRACT FROM AUTHOR]