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Artillery designers are always searching for means of improving a gun's external and internal ballistic properties and this resulted in both new theories surrounding gun construction based on the properties of materials and new methods of building guns capable of firing heavier projectiles to greater ranges. The concept of the accelerator gun sought to achieve the same result without the need for larger and heavier guns and reducing recoil through the use of multiple propellant charges fired sequentially, thus accelerating the projectile without the need for a single high-pressure discharge. It was a quest initiated in France, pursued in the United States and then adopted by a desperate Germany during the latter years of World War 2. [ABSTRACT FROM AUTHOR]

The development of ballistic materials has improved very rapidly in the last few years. Body armor plays an important role in protecting individuals during military threats. Body armor can be divided into hard and soft variants depending on the trade-offs between protection levels and wearer agility. Current research aims to optimize strength-to-weight ratios by using different combinations of synthetic or natural fibers or their combinations to achieve increasingly demanding requirements for ballistic materials. Moreover, it examines the various types of fibers utilized in the construction of body armor, ranging from traditional materials like metal and ceramic to synthetic and natural fibers. This paper discusses ongoing research efforts aimed at further enhancing the performance of these materials, such as the incorporation of modified natural fibers into advanced composite systems. The review provides a comprehensive analysis of the current state of the materials utilized in ballistic protection. [ABSTRACT FROM AUTHOR]

We evaluate an adaptive optimisation methodology, Bayesian optimisation (BO), for designing a minimum weight explosive reactive armour (ERA) for protection against a surrogate medium calibre kinetic energy (KE) long rod projectile and surrogate shaped charge (SC) warhead. We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert. A third approach, utilising a novel human-machine teaming framework for BO is also evaluated. Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments. The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations, outperforming both the stand-alone human and stand-alone BO methodologies. From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples. [ABSTRACT FROM AUTHOR]

User expects his weapon to be light and reliable and to perform multiple times firing per unit time at the same time. In today's technology, the maximum number of firings can be made per unit time with steel barreled weapons, but in composite barrels; many problems occur due to overheating, strength and reliability. Meeting these opposite demands is an engineering problem. In this study, the design of a composite‐steel combination light gun barrel is studied. Firstly, pressure distribution through the barrel has been calculated using Vallier‐Heydenreich method. According to the calculations, analysis has been conducted using both steel barrel and composite barrel. After the analysis, a composite barrel has been manufactured and testing has been conducted on an all‐steel barrel and the manufactured composite barrel. Composite is carbon fiber and resin is epoxy resin. In composite material, carbon fiber is preferred at the rates of 50% and 60%, the material of the steel barrel is AISI 416R stainless steel. The manufactured steel barrels have the same outer diameter but different wall thickness ratios, firing tests were conducted in such a way that the number of shots per unit time was the same. Highlights: Stress distribution within a gun barrel was calculated using Vallier‐Heydenreich method.Design and finite element analysis analysis for an all‐steel gun barrel and a composite gun barrel was conducted.A composite gun barrel was manufactured; by using composite materials, the barrel was lightened by 24.8%.The manufactured composite gun barrel and an all‐steel gun barrel were tested by firing over 2500 shots. [ABSTRACT FROM AUTHOR]

Background: Plastic Surgery originated in war and still has an important role in the management of war wounds and their sequelae. Since June 2022 the Plastic Surgery department of Zaragoza's Miguel Servet University Hospital has been involved in the management of patients with injuries secondary to the Russo-Ukrainian War. In this paper we describe the activity of the plastic surgeons involved and the types of injuries and procedures performed. Methods: We included patients injured in the Russo-Ukrainian conflict transferred for multidisciplinary care to the General Defence Hospital in Zaragoza from June 2022 until December 2023. We gathered epidemiological data, mechanism of injury, anatomical location, types of plastic surgery performed, number of interventions and complications. Results: In the period from June 2022 to December 2023 the multidisciplinary team provided care for a total of 59 patients. Plastic surgeons were involved in the care of 16 patients with a total of 34 plastic surgery procedures: 7 microsurgical free flaps, 6 regional flaps, 4 grafts, 8 debridements, 3 flap remodelings, 4 Targeted Muscle Reinervations, 1 amputation and 1 hand surgery. Three patients suffered from major complications in the form of infections of the surgical wound. Conclusions: Our study showed the crucial role of Plastic Surgery in the management of war injuries and the high proportion of high-complexity microsurgical procedures needed to take care of this type of injury. Level of evidence: Level IV, Therapeutic. [ABSTRACT FROM AUTHOR]

Introduction While the 44-mm clay penetration criterion was developed in the 1970s for soft body armor applications, and the researchers acknowledged the need to conduct additional tests, the same behind the armor blunt trauma displacement limit is used for both soft and hard body armor evaluations and design considerations. Because the human thoraco-abdominal contents are heterogeneous, have different skeletal coverage, and have different functional requirements, the same level of penetration limit does not imply the same level of protection. It is important to determine the regional responses of different thoraco-abdominal organs to better describe human tolerance and improve the current behind armor blunt trauma standard. The purpose of this study was to report on the methods, procedures, and data collected from swine. Materials and Methods Live swine tests were conducted after obtaining approvals from the local institution and the Army Care and Use Review Office of the U.S. Department of Defense. Trachea tubes and an intravenous line were introduced before administering anesthesia. Pressure transducers were inserted into the lungs and aorta. An indenter simulating the backface deformation profiles produced by body armor from military-relevant ballistics to human cadavers was used to deliver impact loading to the liver region. A triaxial accelerometer was included in the indenter design. The animals were monitored for 6 hours, necropsies were performed, and injuries were identified. Biomechanical data of the energy, velocity, deflection, viscous criterion, force, and impulse variables were obtained for each test. Results Peak accelerations, velocities, deflections, forces, impulse, and energies ranged from 897 to 5,808 g, 21 to 59 m/s, 1.96 to 8.87 cm, 2.3 to 13.1 kN, 1.1 to 7.1 Ns, and 58 to 387 J, respectively. The peak viscous criterion ranged from 0.8 to 5.8 m/s. All animals survived the 6-hour survival period. Three animals responded with liver lacerations while the remaining 4 did not have any injuries. Conclusion The experimental design based on parallel tests with whole body human cadavers and cadaver swine was found to be successful in delivering controlled impacts to the liver region of live swine and reproducing liver injuries. Previously used biomechanical measures as potential candidates for injury criteria development were obtained. Using this proven model, tests with additional samples are needed to develop injury risk curves for liver impacts and obtain regional (liver) injury criteria. [ABSTRACT FROM AUTHOR]

Gunshots to the human body can cause direct and indirect injuries. Direct injuries are a consequence of the projectile guiding its way through the body, creating a permanent wound channel and thereby damaging the penetrated as well as the adjacent tissue. In addition, the temporary wound cavity is responsible for indirect injuries occurring distant to the actual wound tract. This can potentially affect different types of tissue, like blood vessels, organs, or bones, that are not directly passed through by the projectile. For this case report, we describe a suicidal headshot to the temporal area where the extension of the temporary wound cavity and its subsequent collapse led to massive energy transfer to the surrounding tissue leading to breakage of the upper dental prosthesis and fractures of the lower jaw. Thereby outlining the ballistic mechanisms causing indirect injury pattern that have to be considered when examining gunshot wounds. [ABSTRACT FROM AUTHOR]

As the switch for the start-up of the nozzle at the rear of the recoilless gun, the opening pressure of the blocking sheet directly affects the balance of the recoilless gun during the shooting process. The opening time of the blocking sheet is obtained through high-speed camera by capturing the tail flame. Using piezoelectric pressure sensors, the pressure at different positions along the barrel were measured. Furthermore, the pressure at the moment of opening the blocking sheet was determined based on its opening time. A significant force jump (Δ f = 146.9 kN) in the unbalanced recoil experienced by the recoilless gun during the initial firing stage was identified based on the theory of one-dimensional recoilless gun balanced interior ballistics. This jump arises from the opening pressure of the blocking sheet surpassing the projectile's starting pressure (P 0). This research can provide a reference for the design of recoilless weapons related to unbalanced force. [ABSTRACT FROM AUTHOR]

Using the possibilities of modern science and technology, it can be said that the presented mathematical model has been formulated without significant simplifications, and its (numerical) solution itself will be performed with high accuracy. The main purpose of the work was to create a tool supporting the calculation of the main problem of internal ballistics for barrel propellant systems in order to achieve digital solutions as close as possible to the results obtained using experimental ballistics methods. The scientific hypothesis of the work postulates that the physical model of internal ballistics formulated in Lagrange coordinates will allow to solve the main problem of internal ballistics of barrel systems in a digital way, obtaining such solution results that will satisfactorily reflect the solution results obtained using experimental ballistics methods. The results of digital simulations of physical phenomena of solutions to the main problem of internal ballistics of barrel weapons were compared with the results of experimental tests and the degree of agreement was determined. [ABSTRACT FROM AUTHOR]

Today, most design processes are carried out using specialized tools in the form of advanced computer software, but in the case of designing weapons (especially internal ballistic) it is not generally available or is even classified. On the other hand, there is no analytical system of non-linear differential equations describing the phases of the shot phenomenon in barrel weapons. Therefore, in order to obtain more accurate solutions to the system of equations, it is optimal to use numerical methods. The paper presents a theoretical description of the problem of solving the equations of internal ballistics. Based on this analysis, it was assumed that the solution to the main problem of internal ballistics formulated in Lagrange coordinates gives correct results and enables obtaining more accurate and realistic analytical solutions than using classical solutions. The utilitarian aim was to create a new program to support the design of classic gun tube weapons. [ABSTRACT FROM AUTHOR]

The use of ordnance gelatine has been widespread in the field of ballistics as a simulant for soft tissue when assessing ballistic threats. However, the traditional method of preparing ordnance gelatine is time-consuming and requires precision to ensure that the final mold meets the required specifications. Furthermore, temperature control is necessary post-production, and there are limitations on its usage duration. To address these issues, manufacturers have developed pre-mixed, gelatine-like products that are stable at room temperature and require less preparation time. Nonetheless, it is uncertain whether these new products can perform in the same manner as the gold standard of ordnance gelatine. This study used five types of blocks, including ordnance gelatine (10% and 20%), Clear Ballistics (10% and 20%) and Perma-Gel (10%) and subjected them to 9 mm, 0.380 Auto fired from a universal receiver and a 5.56 × 45 mm ammunition fired by a certified firearms instructor. Delta-V and total energy dissipation were measured after each test using data collected from ballistic chronographs placed in front of and behind each block. High-speed video was recorded, and a cut-down analysis conducted. The findings revealed variations in energy dissipation and fissure formation within the block, with greater energy based on fissure formation observed in the ordnance gelatine. Additionally, the high-speed video showed the occurrence of secondary combustions occurring in the premixed gelatines. [ABSTRACT FROM AUTHOR]

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The discovery of a specific form of Late Neolithic object in northeast Poland, commonly interpreted as reed arrowshaft straighteners, prompted investigation into the possible use of reed for archery in the European past. To examine the archery qualities of this raw material, and thus the likely rationale behind the manufacture and use of reed arrowshafts, a number of mechanical and experimental analyses were conducted. The results presented here indicate that reed was well suited for prehistoric archery. This is demonstrated above all by the arrowshaft stiffness required by this discipline, defined as the spine‐force, but also both the technological ease of production of arrows and their ballistic capabilities. [ABSTRACT FROM AUTHOR]

Highlights This study presents STF/Fabric composite configurations by impregnating single‐phase shear thickening fluids (S‐STF) and multi‐phase shear thickening fluids (M‐STF) into aramid fabrics. S‐STFs were first prepared at different concentrations by weight (25%, 40%, 55%, and 65%). In addition, M‐STFs were produced by adding silicon carbide (SiC) additive to S‐STFs. As a result of the impregnation of the produced STFs on Aramid fabrics, 30‐layer composite samples were prepared. To determine the ballistic performance of the produced samples, tests were carried out with a single‐stage gas gun system. The shots were performed at an average velocity of 670 m/s. Ballistic tests show that STF‐impregnated fabric samples have better ballistic performance compared to fabric without STF. The STF65/Aramid sample is notable for a 238% increase in energy absorption. In addition, the STF40SiC10/Aramid composite sample produced with M‐STF was found to absorb 18.7% more energy compared to the STF40/Aramid sample. It has been confirmed that keeping the weight ratio of the additive at an optimum level will contribute to ballistic performance. These results contributed to determining the optimum concentration amount for STF/Aramid composites at high speed. S‐STF and SiC additive M‐STFs were produced. STFs were impregnated into 30‐layer Aramid fabrics. Ballistics tests were performed on S‐STF/Aramid and M‐STF/Aramid composite samples with a single‐stage gas gun system. The effects of S‐STF and M‐STF on ballistic performance were investigated. The addition of STF enhanced ballistic performance by increasing energy absorption. [ABSTRACT FROM AUTHOR]

The possibility of enhancing the ballistic performance of aramid fabrics such as Kevlar through the impregnation of nanoparticles is well established. In this study, the influence of the nanoparticle's specifications such as size, shape, and material on the underlying mechanisms is investigated. A colloid-based treatment process is used to impregnate dry nanoparticles into Kevlar fabric. Using a customized gas gun rig, neat and treated samples are tested to determine the kinetic energy absorbed. Silica, alumina, and zinc oxide nanoparticles ranging from 10 to 125 nm, with spherical or cylindrical shape are considered. Silica treated samples perform significantly better (83% increase in energy absorbed vs neat fabric) than alumina or zinc oxide treated samples, likely due to greater agglomeration between yarn interfaces leading to enhanced frictional mechanisms. The exit-face damaged zone area acts as a surrogate for energy absorbed as it correlates well across all samples. Compared to samples with three layers treated individually, samples with three layers treated together display a 21% enhancement in the energy absorbed. Specific energy absorbed for three layers treated together with 80-nm silica is nearly 3 times higher than that for the neat fabric. Samples with three layers treated together with 80-nm silica provide the same performance as the neat fabric for a projectile that is nearly 70 m/s faster. Hybrid structural materials such as nanoparticle-fabric composites offer a promising route to enhance ballistic performance without weight penalty, while being amenable to multifunctional applications. [ABSTRACT FROM AUTHOR]

A set of non-linear optimisation algorithms are combined with a finite element simulation code to analyse the energy absorption and elastic stress wave propagation problem in multilayer/multimaterial armour systems under ballistic impacts. An Abaqus Python script is used to simulate the ballistic event and to generate the variables and post-processing outputs necessary for the integration with the optimisation algorithms. A number of modelling strategies are considered and three optimisation algorithms are used: Particle Swarm Optimisation (PSO), Genetic Algorithm (GA) and Simulated Annealing (SA). The performance and efficiency of each algorithm are assessed through four benchmark tests with different levels of complexity. A multi-objective optimisation procedure is proposed that uses the most efficient algorithm based on every single-objective formulation, variables and constraints from the benchmark tests, resulting in a highly non-linear problem. The proposed optimisation methods successfully achieve the study purposes both in the simulation of generic ballistic impacts and in the quality of the optimised solutions, demonstrating the potential for this type of optimisation method on terminal ballistic applications, serving as a standpoint for further studies into higher energy impacts and material non-linearities. [ABSTRACT FROM AUTHOR]

Background: Use of ultrasound (US) for procedural needle guidance can improve success rates, safety, and accuracy. Often, training is performed on task trainers, which can be prohibitively expensive. Determining undesired needle placement is difficult when the needle is poorly visualized with US. Currently available simulation phantoms cannot provide real‐time feedback on the location of needle placement. Objectives: The primary objective was to develop and determine feasibility of a low‐cost simulation phantom with an internal circuit and LED light system to determine when a needle contacts internal structures. We also aimed to determine whether its use was associated with increased comfort level. Methods: Emergency medicine (EM) residents (PGY‐1 to PGY‐3) performed in‐plane and out‐of‐plane US needle guidance using homemade phantoms. Comfort levels were assessed by pre‐ and post intervention survey. Outcomes were measured on Likert scale (minimum = 1, maximum = 5). The primary outcome was change in confidence markers before and after the simulation task. Secondary outcomes were survey results of comparisons of these models to prior training experiences on simulators and humans. Results: All EM residents (30) in our program were invited to participate. Twenty participants enrolled and completed the study. In the primary outcome, median comfort with out‐of‐plane and in‐plane guidance increased after using the model but was more pronounced for out‐of‐plane guidance. On a posttest survey, residents rated the models overall very similar to prior experience on simulators (median 5/5 [IQR 4.0–5.0]) and moderately similar to humans (median 3/5 [IQR 3.0–4.0]). Conclusions: We created a low‐cost ballistic gelatin phantom with an internal electric needle guidance system. Use of the phantom for training was associated with increased learner comfort with the procedure. Learners rated the characteristics of the phantom as similar to higher‐cost commercial equipment and humans. [ABSTRACT FROM AUTHOR]

Study of the engraving process is significant for interior ballistics. Due to the high transient and strong nonlinear characteristics of the engraving, research on the engraving mechanism is challenging. In this paper, based on the one-dimensional two-phase flow model of interior ballistics coupled with explicit dynamics software, finite element simulation of the engraving is carried out to obtain the changes of parameters during the engraving process, and the dynamic characteristics of the projectile engraving are discussed. By comparing the simulation results with the experimental data, the accuracy of the coupling method in this paper is verified. The relationship between the structural parameters of the sealing band and the extrusion resistance is revealed, and the influence of the extrusion resistance on the dynamic characteristics of the projectile is demonstrated. The simulation results can provide an essential reference for selecting a reasonable sealing band structure. [ABSTRACT FROM AUTHOR]

Sprinkler irrigation is widely used in agriculture because it allows for rational use of water. However, it can induce negative effects of soil erosion and of surface waterproofing. The scholars of these phenomena use the numerical integration of the equation of motion, but if there was an analytical solution, the study would be facilitated, and this solution could be used as software for regulating sprinklers. Therefore, in this study, the solution of the differential equation of the flight of droplets produced by sprinklers in the absence of wind was developed. The impossibility of an exact analytical solution to the ballistic problem due to the variability of the drag coefficient of the droplets is known; therefore, to find the integrals in closed form, the following were adopted: a new formula for the drag coefficient; a projection of the dynamic's equation onto two local axes, one tangent and one normal to the trajectory and some linearization. To reduce the errors caused by the latter, the linearization coefficients and their calculation formulas were introduced through multiple non-linear regressions with respect to the jet angle and the initial droplet speed. The analytical modeling obtained, valid for jet angles from 10° to 40°, was compared to the exact numerical solution, showing, for the total travel distance, a high accuracy with a mean relative error MRE of 1.8% ± 1.4%. Even the comparison with the experimental data showed high accuracy with an MRE of 2.5% ±1.1%. These results make the analytical modeling capable of reliably calculating the travel distance, the flight time, the maximum trajectory height, the final fall angle and the ground impact speed. Since the proposed analytical modeling uses only elementary functions, it can be implemented in PLC programmable logic controllers, which could be useful for controlling water waste and erosive effects on the soil during sprinkler irrigation. [ABSTRACT FROM AUTHOR]

The large compositional space of high entropy alloys (HEA) often presents significant challenges in comprehensively deducing the critical influence of atomic composition on their mechanical responses. We propose an efficient nonparametric kernel-based probabilistic computational mapping to obtain the optimal composition of HEAs under ballistic conditions by exploiting the emerging capabilities of machine learning (ML) coupled with molecular-level simulations. Compared to conventional ML models, the present Gaussian approach is a Bayesian paradigm that can have several advantages, including small training datasets concerning computationally intensive simulations and the ability to provide uncertainty measurements of molecular dynamics simulations therein. The data-driven analysis reveals that a lower concentration of Ni with a higher concentration of Al leads to higher dissipation of kinetic energy and lower residual velocity, but with higher penetration depth of the projectile. To deal with such conflicting computationally intensive functional objectives, the ML-based simulation framework is further extended in conjunction with multi-objective genetic algorithm for identifying the critical elemental compositions to enhance kinetic energy dissipation with minimal penetration depth and residual velocity of the projectile simultaneously. The computational framework proposed here is generic in nature, and it can be extended to other HEAs with a range of non-aligned multi-physical property demands. [ABSTRACT FROM AUTHOR]

Gunshot wound analysis is an important part of medicolegal practice, in both autopsies and examinations of living persons. Well-established and studied simulants exist that exhibit both physical and biomechanical properties of soft-tissues and bones. Current research literature on ballistic wounds focuses on the biomechanical properties of skin simulants. In our extensive experimental study, we tested numerous synthetic and natural materials, regarding their macromorphological bullet impact characteristics, and compared these data with those from real bullet injuries gathered from medicolegal practice. Over thirty varieties of potential skin simulants were shot perpendicularly, and at 45°, at a distance of 10 m and 0.3 m, using full metal jacket (FMJ) projectiles (9 × 19 mm Luger). Simulants included ballistic gelatine at various concentrations, dental silicones with several degrees of hardness, alginates, latex, chamois leather, suture trainers for medical training purposes and various material compound models. In addition to complying to the general requirements for a synthetic simulant, results obtained from dental silicones shore hardness 70 (backed with 20 % by mass gelatine), were especially highly comparable to gunshot entry wounds in skin from real cases. Based on these results, particularly focusing on the macroscopically detectable criteria, we can strongly recommend dental silicone shore hardness 70 as a skin simulant for wound ballistics examinations. [ABSTRACT FROM AUTHOR]

Contact shots to the head often leave behind biological traces inside firearm barrels, a phenomenon of great forensic interest. Until now, the visualization and preservation of these traces presented a significant challenge, lacking a reliable method. This study addresses this gap by searching for a suitable method to extract the traces within a casting. Using alginate or gelatine as suitable materials, the results were hampered by serious adhesion issues and their extraction out of the firearm barrel was impeded. Finally, the combination of 11% gelatine with 1% alginate, introduced into the barrel around a 'central spine', succeeded to consistently produce replicable castings. Experimental contact shots displayed a distinct staining gradient from the muzzle to the rear of the barrel, as revealed through endoscopy and proved in the macroscopic casting. The technique proved effective for various common handgun barrels and successfully preserved blood and gunshot residue (GSR) patterns within the barrel. This method offers the dual benefits of visually mapping staining patterns and securing localized samples for targeted molecular genetic analysis in forensic investigations. [ABSTRACT FROM AUTHOR]

We present here the fabrication at the wafer level and the electrical performance of two types of graphene diodes: ballistic trapezoidal-shaped graphene diodes and lateral tunneling graphene diodes. In the case of the ballistic trapezoidal-shaped graphene diode, we observe a large DC current of 200 µA at a DC bias voltage of ±2 V and a large voltage responsivity of 2000 v/w, while in the case of the lateral tunneling graphene diodes, we obtain a DC current of 1.5 mA at a DC bias voltage of ±2 V, with a voltage responsivity of 3000 v/w. An extended analysis of the defects produced during the fabrication process and their influences on the graphene diode performance is also presented. [ABSTRACT FROM AUTHOR]

This research manuscript describes the process of degradation of an Armox 600 armour plate during the impact of a 5.56x45 mm SS109 projectile. The creation process of the numerical FEM model of the projectile is presented. The projectile impact angle is set between 15° and 90°, and this phenomenon is investigated via numerical and experimental approaches. The experiment is conducted under the same conditions as the numerical approach to validate the FEM model. The experiments are conducted using a high-speed camera. This research manuscript presents the influence of the projectile impact angle on the degradation of the armour plate and its protection capability for different angles. The results demonstrate the dependence of the transferred energy on the armour plate, speed of the particles after impact, and trace dimensions on the armour plate for different impact angles. [ABSTRACT FROM AUTHOR]

This article attempts to trace the development of artillery since the appearance of black powder in Europe. Gradually, the process of gunpowder production was improved by purification of its ingredients and selecting the right proportions. Cannons became the next stage in the evolution of the former throwing machines. In order to produce them, suitable metal alloys were discovered, and the art of gun-founding was perfected. The use of iron and lead projectiles instead of stone projectiles made it possible to reduce their size and enhance their striking power. Initially not very effective, the new weapons became increasingly significant in battle outcomes, playing a key role in events such as the capture of Constantinople or the end of the Hundred Years' War. [ABSTRACT FROM AUTHOR]

Purpose. Solution of the three-dimensional nonlinear problem of external ballistics and development of an approximate mathematical model of the dynamic process for cargo falling from low-speed aircraft, which makes it possible to obtain an analytical solution, which is possible in combination with a geometric representation of the dynamic process using computer algebra. Methodology. Utilizing a blend of analytical and numerical research algorithms, an innovative model was devised, grounded in a nonlinear system of differential equations characterized by time-varying coefficients. The applied three-dimensional approach to the dynamic problem with an initial velocity from a UAV, in the presence of frontal and side wind loading, made it possible to use the nonlinear theory of external ballistics. This streamlining of the problem involved solving a related system of differential equations with variable coefficients along corresponding coordinates, leveraging an asymptotic approach. Furthermore, the formulation of the problem incorporated applied mathematical analysis and modeling, accommodating various pertinent environmental parameters. Findings. The creation of mathematical models and algorithms for calculating the parameters of the dynamic process of falling loads from low-speed aircraft within the framework of the theory of nonlinear external ballistics is an urgent problem both from the point of view of the development of the dynamic theory of the specified class of systems, and the creation of effective calculation algorithms with the possibility of practical application. As a result of the research, characteristic valuations of the influence of variable coefficients on the results of estimated accuracy of landing as a derivative of time were obtained. The obtained analytical and graphical dependences with the provision of appropriate assessments of the applied approach make it possible to establish the correlation of methods and results. Originality. The relevance of scientific research in the field of nonlinear external ballistics is based both on the internal trends of the development of this science and on the urgent needs of modern industry. In this paper, an approximate analytical solution of the nonlinear problem of external ballistics is proposed, which is subject to the applied conditions of motion. The resulting dependencies made it possible to establish the relationship between the parameters and find the degree of their influence on the landing time function. Practical value. The derived analytical findings and solution methodology can be integrated into practical applications within the realms of mathematical physics and engineering computations. This is particularly pertinent in the advancement of control algorithms for ballistic systems. [ABSTRACT FROM AUTHOR]

To enhance the comprehensive performance of artillery internal ballistics--encompassing power, accuracy, and service life--this study proposed a multi-stage multidisciplinary design optimization (MS-MDO) method. First, the comprehensive artillery internal ballistic dynamics (AIBD) model, based on propellant combustion, rotation band engraving, projectile axial motion, and rifling wear models, was established and validated. This model was systematically decomposed into subsystems from a system engineering perspective. The study then detailed the MS-MDO methodology, which included Stage I (MDO stage) employing an improved collaborative optimization method for consistent design variables, and Stage II (Performance Optimization) focusing on the independent optimization of local design variables and performance metrics. The methodology was applied to the AIBD problem. Results demonstrated that the MS-MDO method in Stage I effectively reduced iteration and evaluation counts, thereby accelerating system-level convergence. Meanwhile, Stage II optimization markedly enhanced overall performance. These comprehensive evaluation results affirmed the effectiveness of the MS-MDO method. [ABSTRACT FROM AUTHOR]

Functionally graded materials (FGMs) with a gradual transition from ceramic to metal are believed to have superior ballistic performance compared to ceramic/metal composite armors. Therefore, multilayered SiC/AA7075 FGM samples of size 50 × 50 mm are synthesized using a relatively simple and inexpensive technique, i.e., powder metallurgy. The armor requirements depend upon the type of threat and hence, the region and circumstances. Therefore, unlike most of the available investigations, the present study deals with FGM armors with low areal density (< 30 kg/m2) against 7.62 × 39 mm Hardened Steel Core bullets. Two different FGM designs comprising 3 and 5 layers of SiC/AA7075 composite, with 10-30-50 wt.% SiC and 10-20-30-40-50 wt.% SiC, respectively, are developed herein along with a homogeneous composite with 30 wt.% SiC for comparison. The fabrication process involves the stacking of powder blends pertaining to different layers in the die cavity followed by hot pressing at a temperature of 400 °C and 325 MPa pressure. The green compacts are then subjected to pressureless sintering at 540 °C for 3 h. Solution heat treatment and aging are found to enhance the hardness of each layer significantly. The results of the depth of penetration-based ballistic evaluation profoundly establish the superiority of FGM armors over homogeneous composites. Besides, a one-dimensional stress wave propagation-based analysis is also presented herein to explain the reason for the better ballistic performance of FGMs. [ABSTRACT FROM AUTHOR]

The analysis was performed on six commonly used 5.56 x 45 mm projectile types (M193, M855, M855A1, L31A1, M995, and AP45). The projectile's impact velocity (chosen as 900 m/s) was the same in the examination process. This made it possible to assess how the projectile's design has affected its performance against a hard steel target. These evaluations included numerical simulations (Ansys Autodyn) of projectile impacts. Using the available experimental data, the materials in the computational model were first validated. A short description and CAD model of projectiles is also given. Relevant conclusions were reported. [ABSTRACT FROM AUTHOR]

Although underwater submerged launching has been rigorously investigated for decades, there remains a dearth of comprehensive understanding regarding the underwater interior ballistic characteristics for varying barrel lengths. To address this knowledge gap, the present study aims to explore, via numerical simulations, the initial velocity of interior ballistics, projectile drag, and the mechanism of initial flow field formation at the muzzle under various barrel lengths, thereby considering the influence of differing barrel lengths. The five distinct lengths of barrels are expressed as dimensionless ratios of the weight of water column in front of the projectile to the weight of the projectile in order to be more general. Five different ratios of water-to-projectile weight are investigated: 1.0, 1.2, 1.5, 1.8, and 2.0, all possessing identical diameters and evaluated under equivalent launch conditions. Different ratios significantly impact muzzle velocity, with shorter barrels yielding higher muzzle velocities, while ensuring complete propellant combustion. Further investigations indicate that variations in drag constitute the fundamental cause of initial velocity changes. Furthermore, it is observed that barrels of different lengths exhibit identical characteristics at the point of maximum drag. The initial flow field at the muzzle exhibits considerable variations in terms of length, profile dimensions, and intensity. The findings of this study offer valuable insights into exploring the mechanism of submerged launching and will be utilized to investigate the optimal barrel length. [ABSTRACT FROM AUTHOR]

In this study, the ballistic resistance of SiC (silicon carbide) and a SiC mixture S80B20 (80% SiC/20% B4C) backed with UHMWPE (ultra-high-molecular-weight-polyethylene) fiber board was investigated by striking it with a.30-06 armor piercing projectile. The front plate of the high hardness ceramics is intended to passivate the bullet and limit the bullet's impact kinetic energy, and the high strength backing plate undergoes plastic deformation, absorbing the bullet's residual energy. Ballistic tests revealed that an 8 mm thick S80B20 ceramics produced at a sintering temperature of 2120° or 2140°C, combined with a composite plate, can successfully resist.30-06 armorpiercing rounds with energy greater than 3900 J. The optimal SiC plate meeting the NIJ 0101.06 Level IV was an 8 mm thick SiC sheet backed with 9 mm of fiber board (total thickness, 17 mm; areal density, 33.217 g/m2). The 8 mm thick 80% SiC/20% B4C plate sintered at 2120°C, backed with 7 mm fiber board, had an areal density of only 29.615 kg/m2. If the depth of penetration is less than 44 mm, the fiber board thickness must be increased from 7 to 8 mm, increasing the areal density to 30.552 kg/m2. Compared with the SiC ballistic plate, the density of the composite is 2.665 kg/m2 lower. [ABSTRACT FROM AUTHOR]

The use of non-lethal weapons has spread worldwide, being introduced as an alternative to firearms in many countries such as the United States or the United Kingdom. Among non-lethal weapons, conducted electrical weapons have been adopted worldwide, to control unruly suspected criminals or to neutralise violent situations. The stun gun belongs to this category and is the most widely available, with more than 140,000 units in use by police officers in the field in the US, and an additional 100,000 electrical stun guns owned by civilians worldwide. In Italy, the use of conducted electrical weapons by law enforcement has only recently been introduced, with private use and commercialisation still prohibited, mainly due to controversies related to the potential dangers of such devices. Before the official adoption, several experiments had to be carried out, with mechanisms that reproduced the ballistics of the stun gun. Here we present the case of a man who suffered a self-injury trauma to his hand during a ballistics exercise with a crossbow loaded with stun gun probes. [ABSTRACT FROM AUTHOR]

During engineering blasting operations, various man-made elements (particles) can be formed from the structure due to the impact of an explosion, which, as experimental data show, can have a completely arbitrary shape and a fairly large mass and speed. This article is devoted to consideration of the ballistics of elongated elements and the derivation of the calculated dependencies that allow one to estimate the trajectory of their movement. [ABSTRACT FROM AUTHOR]

We present theoretical analysis and design considerations of a THz superradiant FEL. We derive analytical expressions for the spectral parameter of THz radiation, emitted superradiantly in a rectangular waveguide using a Longitudinal Section Magnetic mode expansion. The results compare well with numerical simulations using UCLA GPTFEL code. GPT simulations of the accelerator e-beam transport show that the chirp provided by a hybrid photocathode RF gun, can produce tight bunching at the undulator site below σ = 100fs. This enables intense superradiant emission up to 3THz, limited by the beam bunching factor. Phase-space analysis of the beam transport indicates that keeping the beam bunching parameter small enough for higher THz frequency operation is limited by the energy spread of the beam in the gun. [ABSTRACT FROM AUTHOR]

Stromboli is a volcanic island in a persistent state of activity, located off the northern coast of Sicily. The paroxysms have been the most powerful explosive phenomena at Stromboli in the last 150 years. These explosions can produce ballistic projectiles that can heavily affect trails and observation sites as well as hit inhabited areas at lower elevations, down to the coast. On July 3, 2019, a paroxysm significantly affected a great portion of the island with ballistic projectiles. In particular, many decimeter and meter-sized spatter bombs hit the W flank of Stromboli, and ignited multiple fires. In May 2022, we conducted an Unmanned Aerial System photogrammetric campaign over a sector of the W flank of Stromboli that was heavily affected by the paroxysm. The largest clasts were still preserved after 3 years, not disturbed by significant mass wasting phenomena or human interference, and they were not yet hidden by the post-fire regrowth of the brush vegetation. In this study, we constrained the main sources of uncertainty affecting the bombs distribution on the ground, by characterizing a percentage of uncertain clasts, testing various density estimators, and by modeling an areal buffer around the mapped clasts. We produced a 0.18 km2 wide 1.6-cm resolution orthomosaic, a 10-cm resolution Digital Surface Model, and 2813 outlines of the mapped ballistics. Spatial distribution of the ground cover and associated uncertainty were analyzed as a function of the distance and of the angular direction from the source. [ABSTRACT FROM AUTHOR]

A coupled framework of ballistic simulations and an optimized machine learning (ML) model was developed to accurately predict the kinetic energy reduction of a projectile impacting a target. ML models can require a significant number of data points for proper training, testing, and validation. High-performance computing (HPC) resources can be used to simulate the ballistic impacts of various projectiles against several different target materials using appropriate physics-based hydrocodes. Computational modeling can explore areas where experiments would naturally be cost-prohibitive. These hydrocodes can evaluate large parametric spaces varying the projectile and target variables that are required to train an ML model. In this study a large, generated set of data points was used to develop an optimized artificial neural network (ANN) algorithm to create a fast-running model without prior knowledge of the mathematical relationships between all the input and output variables. The optimized ANN model was developed using Optuna in an HPC environment to tune the hyperparameters needed for the ANN model. This fast-running ML model could then be leveraged to investigate designing optimized targets that could protect against different types of projectiles. The results of this work showed that the optimized ANN model predicted the kinetic energy reduction with a mean absolute percentage error of 2.7% across the validation data. Overall, the optimized ANN model showed excellent agreement across the range of data considered by the computational models. [ABSTRACT FROM AUTHOR]

Ballistics is an area of flight, and fewer subjects were of greater importance to nation states in the eighteenth century. William Mountaine who published on the topic in 1747 and 1781, wrote: 'It is not possible in the nature of things for any one kingdom to continue long in a state of peace and tranquility', and 'the art of gunnery has from time to time engaged the attention of the most eminent mathematicians'. This paper describes the slow up-take of ideas, first put forward explicitly by Benjamin Robins in 1742, which challenged the belief that air resistance could be neglected in the flight of cannon balls, and asks why it could be, that for a topic so pressing, a clearly wrong mathematical theory was upheld for so long. While considering a number of factors, it argues the attraction of beautiful and simple geometry can be beguiling. [ABSTRACT FROM AUTHOR]

A new area of underwater equipment research focus is the use of underwater unmanned vehicles (UUVs) with launch mechanisms to deploy lightweight and small-sized robots for functions including communication, exploration, and detection. The internal ballistic mathematical model of the underwater launch system for small robots is established in this paper. The internal ballistic parameters and the robot displacement and velocity change rule over time are obtained. The optimization calculation of the crucial parameters to be determined by the particle swarm algorithm is completed. Following optimization, the gas cylinder's initial pressure is 2 MPa, its capacity is 30 L, its opening area is 9.683 × 10−5 m2, and its opening time is 0.02 s. A numerical simulation is performed for the small robot's underwater launch process, based on the mathematical and physical model supplied by Fluent 2020 software. The results yield the robot's motion law and the properties of the flow field during the launch process. The purpose of the underwater launcher experiment is to determine the robot's motion characteristics. The accuracy of the theoretical model is confirmed by comparing and analyzing the numerical simulation results with the actual data. [ABSTRACT FROM AUTHOR]

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The object of research is the complex realm of energy localization and coherent ballistic electronic transport within low-dimensional silicon quantum wires, specifically those doped with germanium atoms. Unlike their three-dimensional counterparts, low-dimensional systems exhibit unique electronic transport behaviors, necessitating novel analytical approaches for a comprehensive understanding. The core of this investigation leverages the Phase Field Matching Theory (PMFT) and the tight-binding (TB) approximation, sophisticated methodologies that enable a deep dive into the quantum mechanical nuances of these systems. Through this lens, we examine the intricate dynamics of dispersion relationships, phase factors, group velocities, and notably, the impact of defects introduced by the germanium doping. This research meticulously analyzes how these defects affect electronic and thermal conductivities, along with densities of states, offering new insights into the role of Fano resonances in the fluctuation of transmission and reflection spectra. These resonances, we find, are crucially dependent on the nature of the defects, their configuration, and the electronic parameters in their vicinity, underscoring the nuanced interplay between material composition and electronic properties in low-dimensional systems. The implications of our findings extend far beyond the theoretical. They pave the way for significant advancements in nanotechnology and the design of electronic devices, highlighting the potential for creating more efficient, high-performance components. Furthermore, this work proposes a framework for developing non-destructive testing methodologies that could revolutionize material science by enabling the precise analysis of defects in low-dimensional systems without causing damage. This is particularly critical for the ongoing development of materials with optimized properties for various applications, from electronics to energy storage. In essence, this research not only enriches our understanding of the physics governing low-dimensional systems but also offers practical insights into leveraging these properties for technological innovation. By bridging the gap between theoretical physics and material science, our study sets the stage for the next generation of electronic components and non-destructive evaluation techniques, marking a significant step forward in the application of quantum mechanics to real-world challenges. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) may have a crucial role in the forensic documentation and analysis of firearm injuries. The aim of this forensic ballistics case study was to explore whether two types of expanding bullets and a full metal-jacketed bullet could be differentiated by inspecting bullet fragments and fragmentation pattern in CT. Three types of.30 caliber bullets (full metal-jacketed Norma Jaktmatch, expanding full-copper Norma Ecostrike, and expanding soft-point Norma Oryx) were test fired from a distance of 5 m to blocks of 10% ballistic gelatine. CT scans of the blocks were obtained with clinical equipment and metal artifact reduction. Radiopaque fragments were identified and fragmentation parameters were obtained from the scans (total number of fragments, maximum diameter of the largest fragment, distance between entrance and the closest fragment, length of the fragment cloud, and maximum diameters of the fragment cloud). The fragmentation patterns were additionally visualized by means of 3D reconstruction. In CT, the bullet types differed in several fragmentation parameters. While the expanding full-copper bullet Ecostrike left behind only a single fragment near the end of the bullet channel, the soft-point Oryx had hundreds of fragments deposited throughout the channel. For both expanding bullets Ecostrike and Oryx, the fragments were clearly smaller than those left behind by the full metal-jacketed Jaktmatch. This was surprising as the full metal-jacketed bullet was expected to remain intact. The fragment cloud of Jaktmatch had similar mediolateral and superoinferior diameters to that of Oryx; however, fragments were deposited in the second half of the gelatine block, and not throughout the block. This case study provides a basis and potential methodology for further experiments. The findings are expected to benefit forensic practitioners with limited background information on gunshot injury cases, for example, those that involve several potential firearms or atypical gunshot wounds. The findings may prove beneficial for both human and wildlife forensics. [ABSTRACT FROM AUTHOR]

In examining deaths resulting from gunshot wounds, it is important to describe the wound pathway created by the projectile. Forensic pathologists must identify all entrance and exit wounds and account for all projectiles. Occasionally, confusion arises as to whether a skin defect represents an entrance wound or not, an exit wound, or some other type of wound. Herein, we propose the descriptor "bullet track skin defect" as a formal description for a superficial skin defect created along the pathway of a projectile within the body. Specifically, we define the "bullet track skin defect" as a partial‐ or full‐thickness skin defect produced by a projectile traveling beneath the skin in a relatively tangential fashion as part of a wound pathway within the body. It is somewhat analogous to a traditional graze or superficial tangential wound, wherein the projectile traveling outside the body strikes the skin tangentially from above, without entering the body. However, the projectile is already traveling within the body with the bullet track skin defect, disrupting the skin tangentially from below rather than from above, without exiting the body. Although these defects are not a common presentation of gunshot wounds, they are certainly not rare. With this case series, we suggest that such defects may be referred to as "bullet track skin defects." Alternative language that can substitute for "bullet track skin defects" includes "bullet track skin wounds" or "bullet track cutaneous defects." [ABSTRACT FROM AUTHOR]

Purpose. Development of an approximate nonlinear model for the solution of the external ballistics problem with determination of the nonlinear system parameters and development of a methodology for calculating the aerodynamic characteristics of the cargo, located on the external suspension of unmanned aerial vehicle (UAV) in order to increase the efficiency of their delivery to the specified landing target by means of asymptotic approach with given parameters of the studied system and external load. Methodology. The development of an effective model was carried out using analytical and numerical research algorithms based on a nonlinear system of differential equations in a general form with time-varying coefficients. In order to obtain a solution to the nonlinear problem of external ballistics in a two-dimensional formulation, the assumption of a significant influence of the projection of the velocity function on the ordinate axis in relation to the component on the abscissa axis is introduced. The problem is reduced to the solution of a related system of differential equations with variable coefficients along the corresponding coordinates using the asymptotic approach for a small parameter of the coefficient of frontal aerodynamic resistance. Applied mathematical analysis and modeling have been used for the problem formulation considering studied environmental parameters. Findings. Analytical dependences of the nonlinear problem of ballistics and application of finite-element analysis (FEA) with respect to the cargo motion from the UAV in the presence of the initial speed and wind load in the plane of motion are proposed. It is shown that the obtained analytical solution is correlated with the direct numerical calculation of the basic differential equation with respect to the ordinate axis. Originality. A mathematical nonlinear model of the dynamic process is proposed, assuming the prevailing influence of the speed function along the ordinate axis compared to the function along the abscissa axis. To obtain an approximate analytical solution of the basic nonlinear system of differential equations with variable coefficients the asymptotic perturbation method is applied. The dependence for the axial displacement function is presented considering actual time-flight parameter. Practical value. The obtained analytical dependencies for estimating the time and distance reaching the target with the initial speed of movement and the presence of wind load can be used in applied problems of mathematical physics and engineering calculations of functional dependencies and control of the cargo delivery process and target reaching from an UAV. The obtained analytical results and the solution algorithm can be integrated into applied problems of mathematical physics and engineering calculations, particularly the development of ballistic system control algorithms. [ABSTRACT FROM AUTHOR]

This review covers the effect of ageing on solid gun and rocket propellants in terms of their ballistic properties. A brief overview of the types of methods, which can be used to determine such parameters, is provided and the literature is described in terms of broad motivation areas for the research. It has been demonstrated that understanding the effects and outputs of propellants, and how these might be affected by ageing, remains an important area of research in the field of energetic materials. [ABSTRACT FROM AUTHOR]