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Sequential analysis concerns statistical evaluation in which the number, pattern, or composition of the data is not determined at the start of the investigation, but instead depends on the information acquired during the investigation. Although sequential analysis originated in ballistics testing for the Department of Defense (DoD)and it is widely used in other disciplines, it is underutilized in the DoD. Expanding the use of sequential analysis may save money and reduce test time. In this paper, we introduce sequential analysis, describe its current and potential uses in operational test and evaluation (OT&E), and present a method for applying it to the test and evaluation of defense systems. We evaluate the proposed method by performing simulation studies and applying the method to a case study. Additionally, we discuss challenges to address for sequential analysis in OT&E. Lastly, while operational testing is the focus in this paper, the methodology presented is applicable to campaigns of experimentation and general testing across numerous disciplines. [ABSTRACT FROM AUTHOR]

Forensic science plays a critical role in the United States criminal legal system. For decades, many featurebased fields of forensic science, such as firearm and toolmark identification, developed outside the scientific community’s purview. The results of these studies are widely relied on by judges nationwide. However, this reliance is misplaced. Black-box studies to date suffer from inappropriate sampling methods and high rates of missingness. Current black-box studies ignore both problems in arriving at the error rate estimates presented to courts. We explore the impact of each type of limitation using available data from blackbox studies and court materials. We show that black-box studies rely on unrepresentative samples of examiners. Using a case study of a popular ballistics study, we find evidence that these nonrepresentative samples may commit fewer errors than the wider population from which they came. We also find evidence that the missingness in black-box studies is non-ignorable. Using data from a recent latent print study, we show that ignoring this missingness likely results in systematic underestimates of error rates. Finally, we offer concrete steps to overcome these limitations. Supplementary materials for this article are available online. [ABSTRACT FROM AUTHOR]

The application of series dual burning rate grain can improve specific impulse of nozzleless solid rocket motor (NSRM). In this paper, burning-rate ratio is the ratio of main propellant burning rate and nozzle propellant burning rate in dual burning rate grain, which has significant influence on NSRM performance. Focusing on relationship between burning-rate ratio and motor performance, internal ballistics simulation of NSRM with different burning-rate ratios has been carried out. Results show that, with the increase of burning-rate ratio, total impulse grows monotonically, while maximum head pressure has two variation stages – the stable stage and the increasing stage. By analyzing the head pressure curves, it is known that maximum head pressure is almost equal to the higher one of initial stage head pressure (p1) and combustion ending stage head pressure (p2). Relationship between p2/p1 and burning-rate ratio has been established by linear fitting, and the critical burning-rate ratio, which is the maximum burning-rate ratio to ensure that maximum head pressure almost is kept invariant, has been obtained. Critical burning-rate ratio has no significant change when geometry size remains invariant. Utilizing critical burning-rate ratio in NSRM with series dual burning rate grain, specific impulse can be enhanced with nearly no sacrifice of maximum head pressure performance. These results can provide references for NSRM designing and optimizing. [ABSTRACT FROM AUTHOR]

Vocational knowledge originates from both research and from practice, each of which is transformed across several epistemic levels to become vocational knowledge. The several transformations of research to vocational knowledge have been described by Young and Bernstein as recontextualisations. Less well described are the successive transformations of practice to become vocational knowledge. This paper observes that practical knowledge has to be transformed across several epistemic levels to become vocational knowledge. It examines different types of literature on European artillery in the early modern period: scholarly books on ballistics which were printed in Latin, gunners' manuals which were manuscripts in the vernacular, and artillery books for non specialist readers which were printed in the vernacular. It finds that practical knowledge didn't have to be transformed just to apply it to a new context. Knowledge is transformed to a different epistemic level when it is expressed for use by a different type of actor for a qualitatively different purpose from the initial use. The paper concludes by arguing that vocational colleges and institutes have a potentially valuable role in developing vocational knowledge from practice. [ABSTRACT FROM AUTHOR]

This article proposes an interior ballistic interval optimization method with the consideration of parameter uncertainty. Interior ballistic parameters such as charge mass, web thickness, powder aperture and chamber volume are considered as design variables and described by interval number. A one-dimensional two-phase interior ballistic model is constructed, and the MacCormack scheme is used to calculate the interior ballistic parameters. A Chebyshev surrogate model is constructed to replace the one-dimensional two-phase interior ballistic model and applied to the optimization process. For each set of design variables, affine arithmetic is introduced to calculate the interval bounds of the performance index of the interior ballistic, avoiding nested double-loop optimization and improving computational efficiency. The Pareto-optimal solution is searched for by an improved non-dominant sorting genetic algorithm. An example is given to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The solid fuel ramjet is one of the simplest air-breathing engines, characterized by increased specific impulse. This study focuses on a parametric investigation of the internal ballistics of a boron-containing solid fuel ramjet. A 2-D axisymmetric model of a ramjet combustor flying at Mach 2.5 was developed and solved numerically utilizing a commercial computational fluid dynamics code modified to address the specific issues of the problem. The simulation results were compared to the theoretical performance calculated by the chemical equilibrium code. The solid fuel regression rate was found to depend on the port diameter and thus decreases with time. Thrust regulation of ramjet engine was demonstrated using bypass air. The specific impulse was found to decrease with boron content, probably because of low combustion efficiency caused by either insufficient oxygen supply or short residence time of the boron particles. [ABSTRACT FROM AUTHOR]

Few firearms have attracted as much attention, curiosity, and mythical attributes as the blunderbuss. Indeed, it often seems that fiction has overwhelmed the facts. To add to the mystery, the literature is conflicting with regard to defining exactly what a blunderbuss is, what it was used for, and how it performed. What is the difference between a blunderbuss and a musketoon? Is the blunderbuss really designed as a weapon of defence using whatever ammunition one might find in the garden? What was the real purpose of the flared bell mouth of the blunderbuss? Despite the extraordinary interest, the many extant examples of blunderbusses found in public and private collections, and the numerous related publications over centuries, it appears that virtually no properly controlled scientific studies have been carried out to address blunderbuss ballistics. Unfortunately, it was not possible for the author to carry out the carefully designed comprehensive experiments required for such a study. Thus, this article is a modest attempt to combine what information is available from some published blunderbuss 'tests', together with the results from more scientific forensic studies of the performance of sawn-off shotguns, and the addition some ballistic science and suggested scaling laws, to improve our understanding of blunderbuss ballistics. [ABSTRACT FROM AUTHOR]

Fit-for-purpose operational equipment for women undertaking law enforcement has generated significant discussion and research internationally over several years. This research addresses the need to ensure optimum safety and fit for women who require ballistic vests as part of their policing roles. It examined whether bras can improve the performance of unisex ballistic vests for women of all bust sizes. A survey of 273 female Victoria Police officers was conducted. The results showed that unisex ballistic vests are not suitable for women with larger breasts when combined with commercial sports bras. Conversely, women with smaller breasts experienced limited issues. Although wire-free bras are recommended for use with ballistic vests, officers with larger breasts reported that they preferred to wear underwire bras. Women with larger breasts experienced more problems with unisex ballistic vests than women with small breasts. Sports bras are not designed to be worn under body armour for prolonged periods. [ABSTRACT FROM AUTHOR]

This article presents a new method of metaheuristic optimization, the algorithm of the innovative gunner (AIG), inspired by the choice of artillery parameters that sends a shot precisely to a target. The applied correction of the cannon's setting parameters differs from that defined by classic artillery theory. The innovativeness of the AIG results from the fact that at each step of the iterative process, the previous solution is corrected by means of specially selected multiplication factors. This is a major difference from most methods in which, at each successive step, a corrective element is added to the previous solution. The AIG is characterized by high efficiency and speed in solving various optimization problems having nothing to do with ballistics. It is extremely simple in description and implementation. The algorithm was tested on several known test-optimization tasks. The results are noticeably better than those achieved by other methods and prove the practical usefulness of the AIG. [ABSTRACT FROM AUTHOR]

"High School and Undergraduate Physics Practicals with 3D Simulations" is a monograph written by Robert Lucas and published by CRC Press in 2022. The book provides a comprehensive collection of 34 physics experiments for high school and undergraduate students, along with background information and instructions on how to carry out each experiment. It also includes 3D simulations of the experiments for students who do not have access to a real laboratory. The book is written in a clear and concise manner and is aimed at students, lecturers, and researchers in the field of physics. It is recommended for those looking to enhance their experimental skills and broaden their knowledge in the subject. [Extracted from the article]

A chronological synopsis of the history of the technology used in experimental and testing work relating to artillery pieces is presented. The period covered is from the mid-seventeenth century up to the Cold War era of the mid-twentieth century. Although the focus is on the development of ballistics measurement in Britain, there are important links to related work in continental Europe. The locus for much of what is described is the Royal Artillery proof and experimental range at Shoeburyness and the key individuals and groups of men and women who worked there. There are longitudinal connections between the very earliest technologies of mechanical chronometry, with paper screens and paper-based calculations, and the later technology where timings, screens and calculations had all become electronic. [ABSTRACT FROM AUTHOR]

Despite continued improvements in gunshot residue (GSR) detection and analysis, there are still challenges in the interpretation of GSR evidence. The level and distribution of GSR present on an individual can be influenced by many factors, dependent upon the context of any given case. Due and diligent attention must therefore be placed upon fate and behaviour processes in relation to GSR when assessing and interpreting any case findings. The distribution of GSR upon the body of a recreational shooter was assessed. Samples were taken from 17 positions across a shooter's body immediately after the discharge of one round of ammunition. The shooting hand prevailed as the most GSR-contaminated area, with as many as 351 characteristic GSR particles identified. The face and supporting hand also exhibited high levels of GSR contamination. This level of contamination raises questions concerning the fate and behaviour of GSR particles within the general environment, specifically with regard to transfer processes. [ABSTRACT FROM AUTHOR]

Firearm-related exhibits are often found at crime scenes. These exhibits may include the firearm, cartridges, cartridges cases or bullets. As ammunition needs to be handled to load the weapon, regardless of the action or loading type, DNA may be deposited onto the ammunition via touch. As reproducible DNA profiles have been obtained from fired cartridge casings and Improvised Explosive Device (IED) fragments, it is possible that quantifiable amounts of DNA could be recovered from fired bullets. A series of 40 Winchester PowerPoint 22LR 42 grain HP Copper Plated bullets were loaded with serially diluted cell suspensions obtained from a female donor. These were shot into 500 sheet reams of A3 paper for capture and returned to a sterile DNA laboratory for removal, extraction and quantification of DNA. Repeatable partial profiles with five reportable loci pairs consistent with the cell donor were obtained in one replicate of the neat sample. Weak partial profiles were also present in 1:2, 1:5 and 1:10 dilutions. To our knowledge, this is the first reported evidence of DNA surviving the cycle of fire and being recovered from a fired bullet under controlled conditions. [ABSTRACT FROM AUTHOR]

This project looks at the intersection between gunshot damage to road signs and the use of geographic information systems (GIS) for forensic intelligence. The project has surveyed several distinct regions in Victoria Australia (residential, semi-rural and rural) in order to establish the level and distribution of gunshot damage to signs. The study assesses the correlation between population densities, land use and road type and the types of gunshot damage associated with road signs. The study includes a temporal aspect with the aid of backdated GIS image data and assessment is made on the potential benefits for crime scene information gathering. Further, a software tool has been established that enables photographic analysis of the gunshot impact points to be used to help determine the scale of damage associated with the signs in order to help establish the types of weapons used. This information is presented in the context of the typical registered guns in the community to correlate the key types of weapons used in this type of activity. [ABSTRACT FROM AUTHOR]

Triple base propellant (TBP) containing mainly nitrocellulose, nitroglycerine, and nitroguanidine has been manufactured and coated with plasticizer in the present work. The aim was to study ballistics of di-butyl phthalate (DBP)-coated TBP. DBP solution in ethanol containing nitrocellulose dope was used for coating onto the propellant grains. DBP-deterred propellant showed inhibition to burning, resulting in lowering the values of ballistic parameters namely peak pressure (Pmax), dPmax, pressure index (α), and burning rate coefficient (β) during closed vessel firing. Increase in percentage of DBP in coating solution led to further decrease in ballistic parameters. Dynamic evaluation of the surface-moderated propellant showed comparatively lower muzzle velocity and chamber pressure for deterred propellant batches without leaving any unburnt particles in gun chamber at subzero temperatures with the lowest possible charge mass. The DBP-coated propellant can be useful in 155-mm artillery gun to achieve higher loading density as it has lower flame temperature and chamber pressure as compared to uncoated propellant which will result in increasing barrel life due to reduction in the barrel erosion. [ABSTRACT FROM AUTHOR]

Keywords: Olympic archery; shaft; recurve bow; ballistics EN Olympic archery shaft recurve bow ballistics S526 S528 3 01/29/21 20191002 NES 191002 1. When the archer reaches full draw, potential elastic energy (Graph HT ht ) is stored in the bow limbs. [Extracted from the article]

A one-dimensional model is introduced in this paper for problems of internal ballistics involving solid propellant combustion. First, the work presents the physical approach and equations adopted. Closure relationships accounting for the physical phenomena taking place during combustion (interfacial friction, interfacial heat transfer, combustion) are deeply discussed. Secondly, the numerical method proposed is presented. Finally, numerical results provided by this code (UXGun) are compared with results of experimental tests and with the outcome from a well-known zero-dimensional code. The model provides successful results in firing tests of artillery guns, predicting with good accuracy the maximum pressure in the chamber and muzzle velocity what highlights its capabilities as prediction/design tool for internal ballistics. [ABSTRACT FROM AUTHOR]

Effective structural design to resist ballistic effects such as small arms or fragmenting weapons has been a goal since weapons were developed. Approaches currently in use for ballistic design are predominantly deterministic and allow designers to decide what wall thickness should be used to stop a prescribed projectile impacting at a predefined velocity. The research presented in this paper provides a framework for conducting reliability analysis of structures subjected to bullet and fragment demands. Thus, pseudo-fragility curves are developed for the limit states related to spall and perforation of wall panels, residual velocities of bullets and fragments, and injury to personnel. The pseudo-fragility analysis provides engineers and owners with a tool to quickly assess the reliability of a wall system subjected to high velocity, low mass projectiles. In particular, the proposed analysis method allows designers and owners to determine the probability of spall and perforation, residual velocity, and injury as a function of wall thickness or threat standoff distance. Abbreviations:Cumulative distribution function (CDF): Gives the probability that a stochastic variable ‘X’, with a proper probability density function, is equal to or less than a value (x). Coefficient of variation (COV): The quotient of the standard deviation and the mean [ABSTRACT FROM AUTHOR]

The addition of nanofillers in high-performance reinforcement results in the formation of hybrid composites. The objective of this research is to determine the effect of silica nanofillers loading on the mechanical properties of Kevlar/epoxy composites for ballistic use. Produced hybrid composite laminates were tested for flexural properties, tensile Properties and impact energy absorption. DMA analyses were performed to investigate composite properties at elevated temperatures. It was observed that introduction of silica nanofillers enhanced flexural properties, tensile strength, and storage modulus of composites. Impact energy absorption was increased up to a specific extent of nanofiller addition. The findings of this study indicate that introduction of silica nanofillers on Kevlar fabrics is a promising method for enhancing mechanical properties of hybrid composite laminates. [ABSTRACT FROM AUTHOR]

This paper examines the complex and evolving relationship between science and the military in the development of listening technologies by British, French and German combatants during the First World War to combat increasingly effective ballistics and artillery on the Western Front. Land-based combat changed from the visual to the aural with an increasing selection of audio-based surveillance technologies being made available, notably sound-ranging, in part to combat the physical limitations of the human ear in the battlefield space. The article concludes by analyzing how post-war physics responded to these developments in sound-based battlefield technologies. [ABSTRACT FROM AUTHOR]

Perceptual processes, in particular modular processes, have long been understood as being mandatory. But exactly what mandatoriness amounts to is left to intuition. This paper identifies a crucial ambiguity in the notion of mandatoriness. Discussions of mandatory processes have run together notions of automaticity and ballisticity. Teasing apart these notions creates an important tool for the modularist's toolbox. Different putatively modular processes appear to differ in their kinds of mandatoriness. Separating out the automatic from the ballistic can help the modularist diagnose and explain away some putative counterexamples to multimodal and central modules, thereby helping us to better evaluate the evidentiary status of modularity theory. [ABSTRACT FROM AUTHOR]

Lévy walks are non-Markovian stochastic processes, whose explosion of space with time is faster than regular Brownian motion but slower than ballistic motion. More concretely, they correspond to a random walk process with jump distribution , where is a power law waiting-time distribution. In this paper, we first investigate the probability distribution functions of Lévy walks, then discuss their aging phenomena, forward waiting-time probability distribution and numerical implementations. [ABSTRACT FROM AUTHOR]

While the use of ballistics data and principles to clarify historical experience of firearms is to be encouraged, their application is not always straightforward. This paper emphasizes the need for care. An example is given of too sanguine reliance on period studies, specifically of muzzle velocity, and of inadequate appreciation of the physics, in particular of the Magnus force. [ABSTRACT FROM AUTHOR]

In this study, a Heracron®aramid fiber-based helmet was made, and its ballistic properties were investigated. The effect of fiber density was studied in depth. For the same weight and number of plies, a helmet manufactured from the HT-2820-based composite showed improved ballistic properties compared with one made from the HT-15000-based composite. This result suggested that fiber density may strongly affect the ballistic properties of armor. HT-2820, containing more multifilament fibers, provides more efficient energy absorption and dissipation. The influence of fabrication method on the ballistic behavior of a helmet was studied. The V50of a helmet made by the film laminating method was 10% better than that for a helmet made by the resin dipping approach. Based on these findings, the film laminating method, which forms the composite by directly attaching aramid fabric to the matrix film, may be a good candidate for improving the ballistic behavior. The required composite interfacial strength will be application-dependent. Greater fiber-matrix adhesion may be advantageous in certain cases. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the ballistic performance of angle-interlock woven fabrics. Different fabric structures firstly have been compared to benchmark the ballistic performance of angle-interlock woven fabrics using the energy loss test. It has been shown that compared with other woven structures, angle-interlock woven fabric demonstrates low ballistic resistance as absorbing less impact energy. This is because angle-interlock woven fabric owns less interlacements than its counterparts. The interlacement plays an important role to help to transfer energy to the adjacent yarns: the more interlacements, the larger area the stress wave could propagate, and more projectile impact energy could be absorbed. After this systemic analysis of overall ballistic performance, more detailed parametric study of angle-interlock woven fabric is carried out. A group of 16 different structures have been tested and compared using the in-house firing range. The studies have revealed that the 3D angle-interlock woven fabric not only displays normal features of energy absorption mechanism, like yarn slippage, fibre fracture and cone formation, which 2D fabric usually demonstrates, but also shows the new property: the weaker gripping power on the constituent yarns. Besides, it also shows that the structural parameters of angle-interlock fabrics do not have a clear influence on the ballistic performance, due to the complicated factors which also have been theoretically explained from the four aspects: (a) the clamping state; (b) yarns hit by the projectile; (c) the impact angle of the projectile; (d) the impact velocity. [ABSTRACT FROM AUTHOR]

Despite their wounding potential, air guns are accepted as low-profile weapons or toys, and are not considered as lethal weapons. The aims of this study are to determine the wounding potential of air guns and to increase the consciousness about the dangers of the air guns. The kinetic energy limits are mentioned in 11 different countries’ legislations are evaluated with respect to test results. Twelve Kraton RTM G1 (15%) Transparent Ballistic Candle Blocks were prepared as the artificial soft-tissue test media in three different test models. A 4.5 mm air pistol and a 5.5 mm air rifle were used in the tests, which were performed in 1 and 10 m ranges. The mean penetration depth of the air pistol shots was 25.60 mm and the air rifle penetration was 79.14 mm from the 1 m range for three test models. In the 10 m range, the mean penetration depth of air pistol shots was 25.30 mm, while 79.19 mm was recorded for the air rifle. Considering these penetration depths, shots at especially the neck, eyes and thorax regions, can cause fatal injuries. For that reason, the kinetic energy limits should be the main point of air gun restrictions. [ABSTRACT FROM AUTHOR]

The use of carbon nanotubes in composite hard armor is discussed in this study. The processing techniques to make various armor composite panels consisting of Kevlar®29 woven fabric in an epoxy matrix and the subsequent V50 test results for both 44 caliber soft-point rounds and 30 caliber FSP (fragment simulated projectile) threats are presented. A 6.5% improvement in the V50 test results was found for a combination of 1.65 wt% loading of carbon nanotubes and 1.65 wt% loading of milled fibers. The failure mechanism of carbon nanotubes during the ballistic event is discussed through scanning electron microscope images of the panels after the failure. Raman Spectroscopy was also utilized to evaluate the residual strain in the Kevlar®29 fibers post shoot. The Raman Spectroscopy shows a Raman shift of 25 cm−1for the Kevlar®29 fiber utilized in the composite panel that had an enhancement in the V50 performance by using milled fiber and multi-walled carbon nanotubes. Evaluating both scenarios where an improvement was made and other panels without any improvement allows for understanding of how loading levels and synergistic effects between carbon nanotubes and milled fibers can further enhance ballistic performance. [ABSTRACT FROM AUTHOR]

Influence of chain extender (CE) and bonding agent (BA) on the mechanical, interfacial and ballistic properties of AP/Al/HTPB composite is determined and compared. Results indicate a relationship between the two properties. The composite without the additives exhibited extremely poor mechanical properties whereas maximum tensile strength and ultimate elongation is achieved by introducing CE in the conventional composite. Better mechanical properties in this modified composite also contributed in improving the ballistic behaviour. SEM analysis of the condensed combustion residues obtained from the propellant burnt in open atmosphere reveals a considerable decrease in the agglomerate size in the modified composite. This effect is reflected as higher specific impulse in this composite, determined from thrust time profile obtained in static bed test. Pressure time profile for the modified composite manifests a stable and consistent burning at the tail end in tubular geometry as opposed to the conventional system that exhibits a susceptible and unstable tail-off. [ABSTRACT FROM AUTHOR]

This paper reports a detailed numerical investigation of the geometrical and structural properties of three-dimensional heaps of particles. Our goal is the characterization of very large heaps produced by ballistic deposition from extended circular dropping areas. First, we provide an in-depth study of the formation of monodisperse heaps of particles. We find very large heaps to contain three new geometrical characteristics: they may display two external angles of repose, one internal angle of repose, and four distinct packing fraction (density) regions. Such features are found to be directly connected with the size of the dropping zone. We derive a differential equation describing the boundary of an unexpected triangular packing fraction zone formed under the dropping area. We investigate the impact that noise during the deposition has on the final heap structure. In addition, we perform two complementary experiments designed to test the robustness of the novel features found. The first experiment considers changes due to polydispersity. The second checks what happens when letting the extended dropping zone to become a point-like source of particles, the more common type of source. [ABSTRACT FROM AUTHOR]

Energy transport in dielectric thin films is mainly governed by the phonon transport across the edges of the film. Depending on the phonon frequencies and the film thickness, some of the phonons do not undergo scattering in the film, which results in ballistic effect on the energy transport in the film. In the present study, the influence of ballistic phonons on the energy transport in silicon thin film is investigated for a spatially varying temperature source at the film edge. The Gaussian temperature distribution at one edge of the film is considered to account for the spatial variation of temperature. The influence of film thickness on energy transport is also incorporated in the analysis. It is found that the Gaussian parameter, defining the spatial distribution of temperature at the film edge, significantly influences equivalent equilibrium temperature variation in the film. Equivalent equilibrium temperature reduces sharply across the film as the film thickness reduces. [ABSTRACT FROM AUTHOR]

The study deals with the problem of layered plate multiobjective optimization against penetration of strikers having supersonic entry velocities. The plate is monolithic piece-wise homogeneous and composed from several plate-like layers produced from various given materials. The number of considered materials is supposed to be finite and consequently the admissible design set consists of separate discrete values. The impactor is modeled as an axisymmetric rigid body with blunted nose. The ballistic limit velocity and the mass of the plate are taken as components of the vector-functional that is optimized in Pareto sense. Best distribution of given materials is found with the help of genetic algorithm. [ABSTRACT FROM AUTHOR]

We describe an optical system in which a vibration induced to a laser probe beam combined with a half-blocked photodiode allows determination of the position and width of objects buried in turbid media. Our system is based on the detection of an AC signal which drastically decreases under the presence of an obstructing buried object. We describe the technique and include experimental results showing that the system is capable of detecting 2 mm wide objects buried at depths up to 3 cm from the front surface of a sample simulating scattering properties of soft tissue. [ABSTRACT FROM AUTHOR]

In previous work, a time-stepped numerical algorithm to compute particle trajectories consisting of lunar soil blown by the engine exhaust of a lunar lander was developed. The time-stepped integration method relies on the gas density, velocity, and temperature fields, calculated by computational fluid dynamics simulations, to compute the forces and accelerations acting on single noninteracting particles. In this paper, a computationally efficient particle ballistics model is presented where the trajectory is estimated by computing the vertical position (axial coordinate x) as a function of the horizontal position (radial coordinate y) using a constant horizontal velocity and a vertical acceleration approximated as a power-law. The unknown parameters of the model are determined by fitting the ballistics trajectory path to a matrix of trajectories generated by the time-step integration method using the rocket exhaust gas properties predicted by computational fluid dynamics software. Also in previous work, a strictly empirical trajectory model was developed to satisfy the need for a computationally efficient method of computing particle trajectories. This new model (like the previous model) is expressed as a time-independent trajectory path function. However, the method of this current work is based on physical laws of motion, unlike the previous empirical model. [ABSTRACT FROM AUTHOR]

In this study, aramid, Heracron®, which was purchased from Kolon Inc., Korea, and phenol composites were prepared by plasma treatment and the influence of this plasma treatment on their mechanical properties and ballistic behavior were ascertained. By measurement of water contact angle and XPS analysis, we find that the plasma treatment may help the incorporation of functional oxygen groups on the surface of the Heracron® fabrics. Additionally, the surface roughness of Heracron® fiber may be proportional to the plasma treatment times. By SEM and mechanical tests, it was shown that plasma-treated Heracron®/phenol composites exhibited higher mechanical properties compared with plasma-untreated Heracron®/phenol composites. Based on this finding, we can conclude that plasma-treatment can promote the interfacial adhesion between Heracron® and phenol, resulting in the superior mechanical properties of their composites. However, the ballistic behavior conflicted with the mechanical properties. That is to say, a helmet, manufactured from the plasma-treated Heracron®/phenol composites, exhibited lower ballistic properties than that of the plasma-untreated Heracron®/phenol composites. As a result, we demonstrated that for ballistic application, somewhat weak fiber-matrix adhesion leads to the improved ballistic behavior. However, it becomes apparent that the optimum strength condition for the composite interphase depends on the particular application, thus increased fiber-matrix adhesion may be more appropriate. [ABSTRACT FROM AUTHOR]

Sir Ralph Payne-Gallwey is best known nowadays as the author of The Crossbow (1903) which remains a reliable introduction to the study of this weapon. Based on experiments with mediaeval weapons he had restored and the work of two research assistants it covers the development of the weapon from the early middle ages to the nineteenth century. He also made scale models and one third replicas of ancient ballistas, which he tested on his estate at Thirkleby, Yorkshire and at Fort Belan, adjacent to the Menai straits. Using a crossbow he shot an arrow and hurled a stone ball from a ballista, over the narrows, a distance of about a quarter of a mile. Arrow-throwing, shooting with the Turkish composite bow as well as the Indian quoit and the boomerang all demonstrate an interest not only in exotic and unusual weapons but also in the science of ballistics. This he showed to friends at Thirkleby, to enthusiastic audiences at the Royal Toxophilite Society meetings and more formally at the Royal Institution in 1908. The text of his lecture was subsequently printed and is reproduced here. These ballistic experiments led to the design of a golf ball with a reticulated surface and his unique 'roller' golf club. [ABSTRACT FROM AUTHOR]

Abstract Based on an energy conservation model, the strength offered by a number of brittle materials has been calculated from depth-of-penetration (DOP) test results. Each material was completely penetrated by a tungsten carbide cored projectile of known kinetic energy and the residual penetration into a ductile aluminium alloy backing material was measured. The energy transferred to the tile by the projectile has been calculated and has been shown to vary linearly with the tile thickness. From the energy transferred to the armour tile, the mean resisting stress that was offered to the penetrator was calculated and for the materials tested, scaled with the material hardness. This work shows that for DOP testing, where the projectile remains intact, the measured DOP is merely a facet of the ceramic's hardness and not its true ballistic performance. The possibility of using this method to measure the strength of damaged ceramic is also discussed. [ABSTRACT FROM AUTHOR]

Abstract It is known that ceramic materials in armour are often shattered by a penetrating projectile and the resistance to penetration is therefore dependent upon the properties of this failed material. A small explosive charge was used to shatter a confined 95% alumina tile by passing the stress wave from an explosive detonation through a steel cover plate and into the ceramic. This fractured material was shown to have an elastic modulus of 130 GPa compared to 330 GPa for the monolithic alumina. Impact indentation tests and ballistic depth of penetration tests were performed on the intact ceramic, shattered ceramic and a pressed ceramic powder compact. It was found that the fractured material had a ballistic efficiency approximately 70% of that of the monolithic alumina and was also able to cause significant erosion to the projectile. [ABSTRACT FROM AUTHOR]

Abstract The performance of armour materials depends upon the deformation mechanisms operating during the penetration process. The critical mechanisms determining the behaviour of armour ceramics have not been isolated using traditional ballistics. It has recently become possible to measure strength histories in materials under shock. The data gained for the failed strength of the armour are shown to relate directly to the penetration measured. Furthermore, it has been demonstrated in one-dimensional strain that the material can be loaded and recovered for post-mortem examination. Failure is by microfracture, which is a function of the defects and then cracking activated by plasticity mechanisms within the grains and failure at grain boundaries in the amorphous intergranular phase. Thus, it appears that the shock induced plastic yielding of grains at the impact face that determines the later time penetration through the tile. [ABSTRACT FROM AUTHOR]

This article deals with the perforation of ductile metal plates subjected to impact by flat-nosed projectiles at normal incidence. Generally speaking, ductile metal plates under impact by flat-ended missiles can fail either by global deformation combined with local shear rupture or by localized adiabatic shear plugging depending upon the geometrical and thermo-mechanical properties of both the targets and the projectiles. Modification is first made to the Bai-Johnson model for adiabatic shear plugging by taking account of strain rate effects using a thermo-viscoplastic constitutive equation instead of thermo-plastic material model and equations for the energy dissipated in the perforation process (perforation energy), the ballistic limit and the residual velocity are then obtained. Furthermore, a critical condition is obtained for differentiating localized adiabatic shear plugging from simple shear plugging failure with global deformations by comparing the modified Bai-Johnson model and the Wen-Jones model. It transpires that the present theoretical predictions are in good agreement with available experimental data in terms of the ballistic limits and the critical transition condition for the modes of plugging failure of ductile metal plates subjected to impact by flat-nosed missiles. It also transpires that the present model predicts well the residual velocities and the energies dissipated in the perforation process. [ABSTRACT FROM AUTHOR]

Efforts to understand the trajectory of cannonballs are an interesting example of the tensions between practical and theoretical knowledge. Although Galileo's 1638 parabolic trajectory was an important theoretical step forward, field gunnery practice was guided by Tartaglia's 1537 'mixed motion' model until the eighteenth century. In 1742, Benjamin Robins published New principles of gunnery, and revolutionized the study of ballistics by suggesting the projectile's initial velocity—not its range—was the appropriate parameter to consider in accounting for air resistance. In 1745, Leonard Euler produced a German translation of New principles, adding his own extensive commentary. Euler's annotated translation quickly became a standard text—Napoleon Bonaparte studied ballistics from the French version—thereby influencing the education of artillery officers and, eventually, of all engineers. This paper surveys the contributions of Robins and Euler to mathematical ballistics theory, examines the influence of these developments on the education of eighteenth-century military engineers, and considers the extent to which the history of ballistics theory supports the thesis that the drive to reconcile practical knowledge with theoretical knowledge can be a critical element in shaping mathematical theory. We close with comments concerning the use of this history in today's classroom. [ABSTRACT FROM AUTHOR]

We present an analytical model for the subthreshold characteristic of ultra-thin independent double-gate (IDG) MOSFETs working in the ballistic regime. This model takes into account short-channel effects, quantisation effects and source-to-drain tunnelling (Wentzel-Kramers-Brillouin (WKB) approximation) in the expression of the subthreshold drain current. Important device parameters, such as off-state current or subthreshold swing, can be easily evaluated through this full analytical approach. The model can be successfully implemented in a Technologies Computer-Aided Design (TCAD) circuit simulator for the simulation of IDG MOSFET-based circuits. [ABSTRACT FROM AUTHOR]

Polycarbonate is commonly used as the material of riot shields. Firings of 83 g steel ball bearings at velocities of 23–98 ms–1 produced damage in the form of dents. Subsequent tensile testing showed a small drop in yield strength and ductility for impact velocities greater than 58 ms–1. This drop in yield strength and ductility was more marked for specimens that had been soaked in acetone for 10 min after ballistic impact. Soaking in n-heptane produced no similar effect to that seen with acetone. Measurements were taken of the velocities of projectiles likely to be thrown by rioters. These showed that the measured velocities were lower than those that caused macroscopic damage to polycarbonate when hit by a ball bearing. Thus susceptibility to brittle failure is likely to be associated with shields that have been hit by sharp objects and exposed to solvents after impact. Mechanical stressing of polycarbonate at the point of impact by the ball bearing had no effect on the subsequent mechanical properties. This is in contrast to the embrittlement seen in polycarbonate when internal strains are present produced on fast cooling from the melt. [ABSTRACT FROM AUTHOR]

The article describes a property of ellipses which was observed by the physicist Jean-Marc Richard in connection with a problem from ballistics. The maximal perimeter of a parallelogram inscribed in a given ellipse can be realized by a parallelogram with one vertex at any prescribed point of the ellipse. The well-known geometric object to which the foregoing discussion relates is the orthoptic circle of Monge, who proved that the locus of points from which one sees an ellipse at right angles is a circle.

Forensic science can be a powerful tool in counter-terrorism, not only in post-incident prosecution, but also in pre-incident deterrence. Examples are given from experience in Israel, and the question is raised how professionals can be taught to maximize upon the capabilities of forensic science. [ABSTRACT FROM AUTHOR]

The development of lightweight armour systems for ballistic protection is under continuing attention of the manufacturers and users. A new design of the composite armour systems has been developed and ballistically tested. A new armour system consists of a ceramic plate, an intermediate ceramic–polymer layer and a polymer fibre lining as a backing material. The proposed composite armour systems prepared with a use of specially selected compositions of the intermediate layer promoting the absorption of the kinetic energy of projectiles provide adequate ballistic protection to National Institute of Justice (NIJ) level III and level IV, and they successfully withstand multiple hits. [ABSTRACT FROM AUTHOR]

We investigate the influence of molecular motion on DNA conductance and charge transfer in the ballistic transport regime. We evaluate the conductance/charge transfer properties for ensembles of conformations representative of the molecular fluctuations in an explicit all-atom representation. We generate such ensembles by classical molecular dynamics (MD) and investigate the influence of conformational change on the charge transfer properties of the system. Using this approach, we can qualitatively explain the influence of base-pair mismatches on DNA electrical properties. [ABSTRACT FROM AUTHOR]

We use a case study approach to explore the facilitators and impediments to effectively using forensics ballistics imaging technology to improve police investigations in a developing country. The study site, Trinidad and Tobago, a nation located in the Caribbean basin, was experiencing a homicide epidemic during the time of this study. The homicide epidemic involved the repeated use of a limited number of firearms, conditions that are ideal for ballistics imaging technology. This nation also possessed a professionalized forensic crime lab and advanced ballistic imaging technology. The analysis reveals that the effective use of ballistics imaging was impeded by inefficient processes and backlogs at the national crime lab, time delays in identifying ballistics hits, and an inefficient system of transmitting hit reports to police investigators. In sum, organizational arrangements in the forensic crime lab and police in the focal country blunted the effectiveness of a proven forensic technology. [ABSTRACT FROM PUBLISHER]

A computational approach for the engineering analysis of ablative-type thermal protection systems (TPS) in atmospheric reentry ballistic flights is communicated. We first propose an improved lumped differential approach for ablative thermal protection analysis, which involves the use of materials with low thermal diffusivity. The results obtained for a one-dimensional thermal ablation problem in a finite slab are compared against those obtained by previously reported lumped differential solutions. Benchmark results for the local nonlinear model, obtained through the generalized integral transform technique, are utilized to verify the proposed solution in a realistic ablation problem, consisting of a low thermal diffusivity material subjected to a prescribed net aerodynamic heating. In addition, an integrated symbolic–numerical system is constructed based on the Mathematica platform for the derivation and computation of all the related quantities along the flight, yielding the transient behavior of the TPS recession and thermal performance for both the constant and variable initial thickness along the vehicle nose region. An illustrative example of the computational tool and the typical results for an orbital platform in ballistic reentry flight are presented. [ABSTRACT FROM AUTHOR]

We present ab initio calculations for spin injection in Fe-ZnSe and Fe-GaAs(001) systems, with and without detection by a second Fe lead. We consider the case of hot injection, as well as the presence of a tunneling barrier at the interface. Our calculations are valid in the ballistic regime. We find that these systems can be very efficient spin filters, leading to current spin polarizations and magnetoresistance ratios very close to the ideal 100%. [ABSTRACT FROM AUTHOR]

Discusses the controversy over the nuclear weapons program of Iran, as of 2002. Details on its policy of nuclear and missile technology procurement from China, Russia and North Korea; Significance of the nuclear infrastructure in Iran; Background on the ballistic missile program of Iran.