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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]

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]

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]

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]

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]

The sodium rhodizonate test is a simple colorimetric technique used to identify traces of lead and barium. A positive test provides rapid and photographically documentable results for shots fired at distances not exceeding 50 cm. Usually, this method is not used for identification of the firing hand, which is detected by electron microscopy with energy dispersive analysis (SEM-EDX), requiring the removal of any particles on the surface to be analyzed by STUB. The use of Sodium Rhodizonate, which is undoubtedly less selective, has the disadvantage of target element solubilization (lead and barium) and thus the loss of the preliminary morphological investigation of the particles. The purpose of this paper is to demonstrate that the two indicated methods can be considered complementary in the following order: 1. buffer sampling for electron microscopy investigation (STUB); 2. and subsequent performance of the Sodium Rhodizonate Test. In some special cases, when it is necessary to obtain the result more quickly, with regards to respecting the chronology of the aforementioned tests, it may be useful to carry out the Sodium Rhodizonate Test first, especially when particular and perhaps antiquated weapons were used for suicidal purposes causing considerable gas dispersion and shot residues from the mechanisms. This research illustrates how significant results were obtained substantiating the suicide hypothesis, following the use of an old revolver (year of manufacture around 1915-1920).

Low velocity ballistic deformation behavior of closed-cell aluminum metal foam targets fabricated by powder metallurgy technique has been investigated. The metal matrix of aluminum (60 micron) was mixed with carbamide (CH4N2O) particles of size one mm. Green samples were obtained by compacting the mixture followed by sintering process using a muffle furnace and the metallic foam thus obtained had an average pore size of 1.5 mm. Compared to metallic material, significant reduction in hardness and density was observed when the porosity was increased from 5 to 30%. Using a gas gun setup, low velocity (100 m/s and conical projectile) ballistic experiments were conducted on metal foam targets to understand the deformation behavior. Not any penetration of the projectile was observed when the percentage of porosity was less than 5%. When the percentage of porosity was increased, the projectile was able to perforate the target as the fracture toughness decreases. The size of fragmented areas of the perforated targets and depth of penetration (DoP) of the projectile were measured. Decrease in DoP (improved ballistic resistance) was observed with the increase in relative density of the closed foam target. Even though the projectile could perforate the foam target, no cracks were observed which enhances the suitability of the metal foams to be used as structural applications of defense vehicles. [ABSTRACT FROM AUTHOR]

As one of the most widely used personal protective equipment (PPE), body armors play an important role in protecting the human body from the high-velocity impact of bullets or projectiles. The body torso and critical organs of the wear may suffer severe behind-armor blunt trauma (BABT) even though the impactor is stopped by the body armor. A type of novel composite material through incorporating shear stiffening gel (STG) into ethylene-vinyl acetate (EVA) foam is developed and used as buffer layers to reduce BABT. In this paper, the protective performance of body armors composed of fabric bulletproof layers and a buffer layer made of foam material is investigated both experimentally and numerically. The effectiveness of STG-modified EVA in damage relief is verified by ballistic tests. In parallel with the experimental study, numerical simulations are conducted by LS-DYNA® to investigate the dynamic response of each component and capture the key mechanical parameters, which are hardly obtained from field tests. To fully describe the material behavior under the transient impact, the selected constitutive models take the failure and strain rate effect into consideration. A good agreement between the experimental observations and numerical results is achieved to prove the validity of the modelling method. The tests and simulations show that the impact-induced deformation on the human body is significantly reduced by using STG-modified EVA as the buffering material. The improvement of protective performance is attributed to better dynamic properties and more outstanding energy absorption capability of the composite foam. [ABSTRACT FROM AUTHOR]

This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured (LAV) and medium armoured military vehicles (MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles; however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 ＋ STANAG 4569 military standard (projectile 14.5 mm ( 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite (MMC) reinforced with carbon nanotubes (CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP - STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates (AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate. [ABSTRACT FROM AUTHOR]

To accelerate the practicality of electromagnetic railguns, it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage. In this paper, a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun, and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network (PFN) is carried out. Various test methods such as spectrometer, fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity, transient magnetic field strength and stress-strain of rail. Combining the simulation results and experimental data, the damage condition of the contact surface is analyzed. [ABSTRACT FROM AUTHOR]

In this paper, the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of fragments. Attention is paid to elucidating the influences of rod cross-section dimensions, structure height, structure layer, and rod inclination angle on the deformation mode, ballistic performances, and ability to change the ballistic direction of fragments. The results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural parameters. In this respect, structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and, consequently, ballistic performances. [ABSTRACT FROM AUTHOR]

A series of ballistic experiments were performed to investigate the damage behavior of high velocity reactive material projectiles (RMPs) impacting liquid-filled tanks, and the corresponding hydrodynamic ram (HRAM) was studied in detail. PTFE/Al/W RMPs with steel-like and aluminum-like densities were prepared by a pressing/sintering process. The projectiles impacted a liquid-filled steel tank with front aluminum panel at approximately 1250 m/s. The corresponding cavity evolution characteristics and HRAM pressure were recorded by high-speed camera and pressure acquisition system, and further compared to those of steel and aluminum projectiles. Significantly different from the conical cavity formed by the inert metal projectile, the cavity formed by the RMP appeared as an ellipsoid with a conical front. The RMPs were demonstrated to enhance the radial growth velocity of cavity, the global HRAM pressure amplitude and the front panel damage, indicating the enhanced HRAM and structural damage behavior. Furthermore, combining the impact-induced fragmentation and deflagration characteristics, the cavity evolution of RMPs under the combined effect of kinetic energy impact and chemical energy release was analyzed. The mechanism of enhanced HRAM pressure induced by the RMPs was further revealed based on the theoretical model of the initial impact wave and the impulse analysis. Finally, the linear correlation between the deformation-thickness ratio and the non-dimensional impulse for the front panel was obtained and analyzed. It was determined that the enhanced near-field impulse induced by the RMPs was the dominant reason for the enhanced structural damage behavior. [ABSTRACT FROM AUTHOR]

A terminal ballistic analysis of the effects of 7.62 mm X 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study. The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea® software yielded the conclusions. The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile's core. The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results. An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study. The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile's performance. [ABSTRACT FROM AUTHOR]

Machine learning (ML) is well suited for the prediction of high-complexity, high-dimensional problems such as those encountered in terminal ballistics. We evaluate the performance of four popular ML-based regression models, extreme gradient boosting (XGBoost), artificial neural network (ANN), support vector regression (SVR), and Gaussian process regression (GP), on two common terminal ballistics' problems: (a) predicting the V50 ballistic limit of monolithic metallic armour impacted by small and medium calibre projectiles and fragments, and (b) predicting the depth to which a projectile will penetrate a target of semi-infinite thickness. To achieve this we utilise two datasets, each consisting of approximately 1000 samples, collated from public release sources. We demonstrate that all four model types provide similarly excellent agreement when interpolating within the training data and diverge when extrapolating outside this range. Although extrapolation is not advisable for ML-based regression models, for applications such as lethality/survivability analysis, such capability is required. To circumvent this, we implement expert knowledge and physics-based models via enforced monotonicity, as a Gaussian prior mean, and through a modified loss function. The physics-informed models demonstrate improved performance over both classical physics-based models and the basic ML regression models, providing an ability to accurately fit experimental data when it is available and then revert to the physics-based model when not. The resulting models demonstrate high levels of predictive accuracy over a very wide range of projectile types, target materials and thicknesses, and impact conditions significantly more diverse than that achievable from any existing analytical approach. Compared with numerical analysis tools such as finite element solvers the ML models run orders of magnitude faster. We provide some general guidelines throughout for the development, application, and reporting of ML models in terminal ballistics problems. [ABSTRACT FROM AUTHOR]

In a tidal disruption event (TDE), a star is destroyed by the gravitational field of a supermassive black hole (SMBH) to produce a stream of debris, some of which accretes onto the SMBH and creates a luminous flare. The distribution of mass along the stream has a direct impact on the accretion rate, and thus modelling the time-dependent evolution of this distribution provides insight into the relevant physical processes that drive the observable properties of TDEs. Analytic models that only account for the ballistic evolution of the debris do not capture salient and time-dependent features of the mass distribution, suggesting that fluid dynamical effects significantly modify the debris dynamics. Previous investigations have claimed that shocks are primarily responsible for these modifications, but here we show – with high-resolution hydrodynamical simulations – that self-gravity is the dominant physical mechanism responsible for the anomalous (i.e. not predicted by ballistic models) debris stream features and its time dependence. These high-resolution simulations also show that there is a specific length-scale on which self-gravity modifies the debris mass distribution, and as such there is enhanced power in specific Fourier modes. Our results have implications for the stability of the debris stream under the influence of self-gravity, particularly at late times and the corresponding observational signatures of TDEs. [ABSTRACT FROM AUTHOR]

The last five decades have seen strong developments in irrigation modeling. In solid-set sprinkler irrigation, models have generally been applied to a few sprinklers in a regular arrangement, making them representative of a sector or a field. In this research, the Ador-Solid-Set model for whole-field solid-set sprinkler irrigation is presented, validated and applied to simulate an irrigation event in two fields: CA (10.2 ha) and ZA (24.5 ha), equipped with 12 and 26 sectors, respectively. The model couples pipeline hydraulics (EPANET), sprinkler ballistics and irrigation scheduling at execution time. Field experiments were used to validate the ballistic model in a solid-set combining full- and partial-circle sprinklers. Observed and simulated irrigation depths and coefficients of uniformity showed determination coefficients of 0.73*** and 0.89***, respectively. Optimization was used to estimate pipeline roughness based on pairs of pressure measurements (at the inlet and specific sprinklers): 26 pairs in CA and 58 pairs in ZA. Roughness parameters were estimated for the main pipeline, each sector and the sprinkler risers: 14 parameters in CA and 28 in ZA. More than a million hydraulic simulations were required to estimate roughness in each field. Maps were produced for applied water in CA and ZA following a sequential irrigation of their sectors lasting for 24 hours. The model produced whole-field coefficients of uniformity of 80.2 in CA and 80.9 in ZA. Finally, Ador-Solid-Set quantified the volume of drift outside the field (2.4 and 1.5% of the applied water in CA and ZA, respectively). This additional drift can be added to the wind drift and evaporation losses obtained from empirical equations, in a process that requires further analysis. Research efforts are also needed to enhance the current model capabilities and address the challenges related to water quantity and quality in sprinkler solid-sets.

The frequency of ballistic spinal injuries is rising in developing nations around the globe. These injuries lead to a functional prognosis linked to disabling sequelae and vitals in patients, which often results in serious complications and death.This study describes the epidemiological, diagnostic, therapeutic, evolutionary characteristics of Ballistic Medullar-Vertebral trauma (BMVT). It presents the particularities of management in the sub-Saharan African country of Chad.This is a prospective descriptive study of 27 ballistic spinal injury patients conducted over an 18-month period.Ballistic Medullar-Vertebral injuries (BMVI) represented 12.9 % of spinal trauma. The average age of the patients was 31.8, and 40.7 % were between 31 and 40 years of age. Military personnel represented 78 % of the patients. 44.4 % of cases came from the Lake Chad region. 59.3 % of injuries were caused by Kalashnikov’s (AK 47) firearms. 74.1 % of cases were admitted to the emergency department within 12 to 24 h. The diameter of the wounds that corresponded to the entry orifice of the bullet was between 1 and 2 cm in 59.25 % of the cases. A Dural breach was found in 14.8 %. 48.1 % had ASIA C score and none of them met the criteria for spinal cord injury collection and immobilization. The lumbosacral location was reported in 55.6 %, and the type I Roy Camille fracture was found in 70.37 %. Surgical management was performed in 88.9 % cases. Multidisciplinary management of the associated lesions was performed in 25.9 %. 7.4 % of patients with cervical trauma died due to septic shock.Delayed emergency department admissions and limited access to medicalized transportation are main factors to BMVI in Chad. Lesion is predominantly located in the lumbosacral region. Lesions and spinal cord involvement were factors of poor vital and functional prognosis. Surgery plays an important role in management. Socio-professional reintegration remains problematic.

Abstract Background Ballistics deals with the study of projectile propulsion, flight, and impact in any medium. Different garment materials can have varying effects when it comes to the penetration of pellets into the body. Body armor has been around for a long time. Dhal, a curving strip of rhino hide, was possibly the first armor in India, used for sword fighting or defense against arrows and spears. It gave way to steel armor, which protected the body’s essential organs from spear and arrow strikes. The current study is primarily concerned with how jeans material, when employed as body armor, contributes to the inquiry. The present study also examines how airgun pellets fired at various ranges affect jeans clothing wrapped around gel blocks. Results The study concluded that when fired at varied ranges, there was no significant variation in the diameters of the entry holes on clothing material. The gel block covered with jeans clothing was not found to be more damaged. Conclusions The findings also indicate that pellets had larger track lengths regardless of the range from which they were fired.

A detailed mapping of volcanic ballistic projectiles emplaced in a defined area, represents the starting point to derive preparatory data in hazard and risk studies of ballistics phenomena. Considering as case study the 3rd July 2019 paroxysmal eruption occurred at Stromboli volcano, we map and analyse at very high spatial resolution (8 cm) the distribution of the ballistic spatter clasts emplaced on the E flank of the volcano. The resulting map identifies and reproduces as geospatial polygon elements 152,228 spatter clasts with areal dimensions from 0.03 to 4.23 m2. Dispersed on 0.407 km2, the spatters cover an area of 29,000 m2 corresponding to an erupted products volume from 2.3 to 7.0 × 103 m3, calculated here for the first time. Spatial analyses indicate that the area mostly affected by the clasts emplacement is between N67.5 and N135 directions, identifying a preferential deposition between N112.50 and N123.75 directions. The clasts size distribution rapidly decreases with the size increase, highlighting a nearly constant ratio small/large clasts regardless the distance from the vent. Finally, additional investigations reveal that clasts dispersion parameters decrease progressively with the distance from the vent only along one direction (N67.5), highlighting how the morphology influences the deposition and remobilisation of mapped ballistics. [ABSTRACT FROM AUTHOR]

A mathematical simulation of the internal ballistics of a shot from a gun, depending on the design of the charge of the gun, has been performed. A general system of equations defining the unsteady movement of a two-phase gas–powder mixture in the channel of the barrel of a gun in the one-dimensional approximation is presented. Results of simulation of a shot from a gun charged with tubular powder or chopped powder are presented. The influence of the gradual ignition of a powder in a gun and of its nonstationary and erosion burning in it on the parameters of the ballistic process in the gun and the influence of the mass and disposition of an igniter in the gun on the dynamics of a shot from it were investigated. [ABSTRACT FROM AUTHOR]

The change of ambient temperature will cause the change of gunpowder burning rate, which will directly affect the ballistic performance of the projectile and cause the change of the overload of the projectile fuze system. In this study, the numerical simulation program of the interior trajectory of a large-caliber gun was established by MATLAB, and the variation rules of the corresponding trajectory parameters at different temperatures were obtained. ANSYS finite element software is used to analyze the force of the projectile fuze system under different ambient temperatures. The results show that under the same loading conditions, with the increase of ambient temperature, the maximum pressure in the gun bore and the muzzle velocity of the projectile increase significantly, and the stress and strain of the projectile fuze system in the bore increase gradually. The numerical simulation results are in good agreement with the theory, which reveals the influence of ambient temperature on the overload in the bore of the projectile fuze system to a certain extent, and provides theoretical support for the study of internal ballistics, charge design and gun use. [ABSTRACT FROM AUTHOR]

To clarify the combustion process of a modular charge system with a primer gap, the rules governing the cartridge movement and pressure change in the chamber are analyzed. Based on the characteristics of the modular charge system, an axisymmetric two-phase flow model of the interior ballistics is established, with the monotonic upward-centered scheme for conservation laws adopted to calculate the combustion process. Compared with the experimental results, the difference in the peak pressure is less than 5%, which indicates that the mathematical model and scheme are reliable and accurate. The results show that, during the initial stage of ignition, the combustible container remains unbroken, and the gas and solid particles are prevented from spreading to the chamber by the end cap of the cartridge. Thus, only the gas inside the igniter tube influences the flow field in the chamber. After the combustible container has broken, the gas and solid particles move rapidly toward the cavity from the combustible container. The axial movement of solid particles is more intense than that of the gas particles, but the radial movement of solid particles is relatively weak. Furthermore, the existence of the primer gap leads to a delay in the ignition time of the solid particles, which delays the rupture time of the igniter tube and the module cartridge. [ABSTRACT FROM AUTHOR]

Fluctuations in outer space's temperature would affect the spacecraft's regular operation. This paper aims to study the temperature influences of the aluminum honeycomb buffer in the tether-net launcher. Firstly, a buffer structure was designed to attenuate the pyroshock generated by the pyrotechnic device. Secondly, the mechanical properties of aluminum honeycomb at different temperatures were obtained through quasi-static compression experiments. Then, the internal ballistic responses of the launcher were gained by the closed bomb tests and the equivalent classical interior ballistic model. Finally, the recoil performance of the launcher with aluminum honeycomb buffer at different temperatures was studied. It is revealed that the aluminum honeycomb crushing force gradually decreases with the temperature increases. The peak pressure, burning rate coefficient and velocity increase while the peak time decreases with the temperature increase for the interior ballistics. For the launcher recoil responses, the average launch recoil decreases if the aluminum honeycomb doesn't enter the dense stage. The impact acceleration, projectile velocity and displacement increase as the temperature increase. The paper spotlights the temperature's influence on the recoil characteristics of the aluminum honeycomb buffer, which provides a new idea for buffering technology of pyrotechnic devices in a complex space environment. [ABSTRACT FROM AUTHOR]

In this research, the ballistic behavior of the ceramic-reinforced aluminum matrix composite plates is investigated to provide an optimal design for protecting against 7.62 mm bullet at the speed of 800 m/s experimentally and numerically. The target materials are Al5083 alloy as the metal matrix and alumina ceramic balls as the reinforcement. To simulate a 3D numerical model, ABAQUS FE code has been utilized. After validation the numerical model by experiments, the effect of ceramic ball weight percentage include 15%, 30% and 45% and the target thickness 20, 25 and 30 mm is considered on the ballistic results like the kinetic energy, residual velocity and depth of penetration. Finally, it was found that the specimen with 25 mm thickness and 30% alumina is optimum based on existing ballistic protection criteria. [ABSTRACT FROM AUTHOR]

A methodology is developed based on the coupling of a finite element code with an optimisation module for the design of land vehicle armouring composed of lightweight aluminium alloy and high strength steel plate. Following an experiment/simulation correlation, a numerical model has been built and calibrated considering monolithic plates and then verified considering a bi-metal protection against tungsten carbide projectile mimicking the core of a 7.62x51 AP8 ammunition. In addition, a method is proposed to obtain the vres - vi curve for the full 7.62x51 AP8 bullet from the vres - vi curve obtained from the core only. [ABSTRACT FROM AUTHOR]

The trade e off between protection and weight is a constant consideration when designing a portable protective solution. Greater mobility is a desirable attribute and protection must therefore adapt, prompting a demand for lightweight, simple to construct, low-cost and effective ballistic protection systems. High strength and ductility, wave spreading capability and good energy absorption are key properties for ballistic protection. Four materials, polycarbonate, Kevlar®-epoxy, polyurethane foam, and aluminium alloy, possess these properties and were selected for analysis by numerical simulation. Multilayered configurations were proven to be an optimal solution, by exploiting the advantages of each material without having large penalties of mass and cost. Numerical modelling using ANSYS AUTODYN® is used to simulate monolithic and multi-layered target configurations, to obtain the penetration mitigation performance. The results are analysed to select configurations based on different requirements, such as lowest cost, lowest mass, best performance, and optimal configuration which balanced the three key parameters mentioned. The optimal configuration of Aluminium, Kevlar-Epoxy, Polyurethane, and Polycarbonate has layers with thickness of 7, 3, 38, 2 mm respectively with a total mass of 7.97 kg, total cost of $39.86 and penetration of 29.34% (14.67 mm). Polynomial relationships between performance and mass/cost are also determined. [ABSTRACT FROM AUTHOR]

Background: Ballistics deals with the study of projectile propulsion, flight, and impact in any medium. Different garment materials can have varying effects when it comes to the penetration of pellets into the body. Body armor has been around for a long time. Dhal, a curving strip of rhino hide, was possibly the first armor in India, used for sword fighting or defense against arrows and spears. It gave way to steel armor, which protected the body's essential organs from spear and arrow strikes. The current study is primarily concerned with how jeans material, when employed as body armor, contributes to the inquiry. The present study also examines how airgun pellets fired at various ranges affect jeans clothing wrapped around gel blocks. Results: The study concluded that when fired at varied ranges, there was no significant variation in the diameters of the entry holes on clothing material. The gel block covered with jeans clothing was not found to be more damaged. Conclusions: The findings also indicate that pellets had larger track lengths regardless of the range from which they were fired. [ABSTRACT FROM AUTHOR]

It is shown that the ratio of the proton convective gyroradius r Ep, to the width of the shock ramp D , controls the thermalization process of ions in quasi-perpendicular shocks. When r Ep/ D > 1, the solar wind beam energy is rapidly converted to gyration (thermal) energy by a universal, transit time thermalization (TTT) mechanism that does not require any collisions, waves, or instabilities. The TTT of ions on magnetic field gradients is followed by stochastic wave energization (SWE) on electric field gradients. Ions heated by TTT and SWE processes are subject to additional ballistic surfing acceleration caused by the convection field in the shock front. These three fundamental ion energization mechanisms are studied with test-particle simulations in a realistic shock model, and are shown to be consistent with magnetospheric multiscale measurements in the Earth's bow shock. It is also shown that shock reflected ions are produced by the SWE process and not by the cross-shock potential. An explanation for downstream oscillations in quasi-perpendicular shocks is also provided. [ABSTRACT FROM AUTHOR]

Two-phase flow numerical methods are applied in internal ballistics widely, which has made higher fidelity analysis with minimal cost become an urgent demand. Current methods are based on independent dimension, and there is no definite conversion criterion and data transmission method, which have limited the application of efficient hybrid models applied to calculation. In this paper, we propose a hybrid method by linking a two dimensional (2D) model to a one dimensional (1D) model for two-phase flow. First, 1D and 2D two-phase flow models are established according to the flow field states in different phases. Next, the criterion of conversion between the two models is established, which is a quantitative index to judge the degree of radial effect and axial effect. Finally, dimension transformation in the radial direction and grid mergence in the axial direction are conducted to complete the whole computing model. The simulation results show that the hybrid method is more efficient in the interior ballistic process and maintains the level of trust in classical codes. Compared with the 2D method, the hybrid method significantly improves the computational efficiency by 86.5%. By analyzing the state in the chamber, the accuracy of the conversion criterion is confirmed. This criterion can be used as the transformation criterion of the hybrid model to form the standard multi-dimensional calculation transformation criterion of interior ballistics and may be promising for the rapid simulation of two-phase flow in interior ballistics. [ABSTRACT FROM AUTHOR]

Multi-layer fabrics are commonly used in ballistics shields with a lower bulletproof class to protect against pistol and revolver bullets. In order to additionally limit the dynamic deflection of the samples, layers reinforced with additional materials, including non-Newtonian fluids compacted by shear, are additionally used. Performing a wide range of tests in each case can be very problematic; therefore, there are many calculation methods that allow, with better or worse results, mapping of the behavior of the material in the case of impact loads. The search for simplified methods is very important in order to simplify the complexity of numerical fabric models while maintaining the accuracy of the results obtained. In this article, multi-layer composites were tested. Two samples were included in the elements subjected to shelling. In the first sample, the outer layers consisted of aramid fabrics in a laminate with a thermoplastic polymer matrix. The middle layer contained a non-Newtonian shear-thickening fluid enclosed in hexagonal (honeycomb) cells. The fluid was produced using polypropylene glycol and colloidal silica powder with a diameter of 14 µm in the proportions of 60/40. The backing plate was made using a 12-layer composite made of Twaron® para-aramid fabrics with a DCPD matrix—not yet used in a wide range of ballistics. Then, numerical simulations were carried out in the Abaqus/Explicit dynamic analysis. The Johnson–Cook constitutive strength model was used to describe the behavior of elastic–plastic materials constituting the elements of the projectiles. For the non-Newtonian fluid, a Up-Us EOS was used. The inner layers of the fabric were treated as an orthotropic material. Complete homogenization of the sample layers was carried out, thanks to which each layer was treated as a homogeneous continuum. As a parameter of fracture mechanics for shield components, the strain criterion was used with the smooth particles hydrodynamics method (SPH). Then, the results of simulations were compared with the results of the ballistic test for both samples placed next to each other, which resulted in the formation of a multi-layer composite in one ballistic test subjected to impact loads during firing with a 9 × 19 mm Parabellum FMJ projectile with an initial velocity of 370 ± 10 m/s. The results of numerical tests are very similar to the ballistic tests, which indicates the correct mapping of the process and the correct conduct of layer homogenization. The applied proportions of the components in the non-Newtonian fluid allowed a reduction in the deflection compared to previous studies. Additionally, the proposal to use a DCPD matrix allowed to obtain a much lower deflection value compared to other materials, which is a novelty in the field of production of ballistic shields. [ABSTRACT FROM AUTHOR]

Featured Application: These research results can be applied in forest fire suppression. This paper focuses on improving fire suppression performance through the use of compressed-air launching technology. A launch dynamics calculation model of a compressed-air launcher is presented, developed using VC++ programming, to simulate the acceleration process of a fire-extinguishing bomb in a barrel. By analyzing the influences of various structural and initial parameters on interior ballistics variations, the effectiveness of the calculation model and program in accurately simulating the launching process is demonstrated. The calculation results indicate that the bore pressure follows a similar trend to that of traditional gunpowder launching. Additionally, it is found that specific structural parameters, such as nozzle diameter and gas cylinder volume, have a direct impact on interior ballistics variations. Notably, the nozzle diameter positively affects the peak pressure, muzzle velocity, gas transfer efficiency, and launch efficiency. To ensure an optimal launch effect and efficiency, the nozzle diameter should be selected to be more than half of the launcher caliber. Similarly, the gas cylinder volume positively influences the peak pressure and muzzle velocity while negatively affecting the gas transfer efficiency and launch efficiency. Furthermore, the initial pressure in the gas cylinder exhibits a positive linear relationship with both the peak pressure and muzzle velocity but a negative linear relationship with the gas transfer efficiency and launch efficiency. The loading position minimally impacts the peak pressure and muzzle velocity but slightly enhances the gas transfer efficiency and launch efficiency. Finally, it is observed that launch angles do not affect the interior ballistic process. The research findings provide valuable theoretical guidance for determining the working parameters of compressed-air accelerated fire-extinguishing bombs. [ABSTRACT FROM AUTHOR]

. During shooting operations in garrison shooting ranges, a phenomenon of random deflection of the bullet flight path was noticed which may cause secondary reflections from accidentally hit technical and ballistic shooting range elements and the ground of the actual plane of the shooting range (ricochets posing a threat to people and property within the shooting range and safety zones). Minimisation of this phenomenon must be considered during the design and operation of the shooting ranges. In 20202022 the Military Institute of Armament Technology (Zielonka, Poland) carried out tests with the aim of determining the impact of the shooting target or military target material or design (hereinafter referred to as the targets) on the risk of occurrence of modifications of bullet trajectory that cause the bullets to leave the shooting zone. The paper presents example results of these tests that show, but are not limited to, that the reasons to modify the direction of the bullet path after target penetration and any ricochets include: target material (flat or corrugated sheet metal, cardboard, plywood, etc.), target wooden legs, and even metal elements fixing the legs to the target. On the basis of the test it was shown that the metal targets prohibited on intermediate lines may cause significant deflections of the bullet flight path after penetration and dangerous ricochets. Due to the reason presented above, the metal targets are placed on the last line of targets before the main bullet trap only where the technical and ballistic parameters of the bullet trap ensure that any ricochets are captured. It was stated that the contact targets used on intermediate target lines and provided with wooden legs may cause bullet trajectory changes comparable to or even greater than in the case of the prohibited metal targets. To this end it is advisable to establish legal framework covering the ballistic inspection of the target materials to be used in garrison shooting ranges.

A recently published modeling approach for the penetration into adobe and previous approaches implicitly criticized are reviewed and discussed. This article contains a note on the paper titled "Ballistic model for the prediction of penetration depth and residual velocity in adobe: A new interpretation of the ballistic resistance of earthen masonry" (DOI: https://doi.org/10.1016/j.dt.2018.07.017). Reply to the Note from Li Piani et al is linked to this article. [ABSTRACT FROM AUTHOR]

Ongoing military conflicts, along with a constant evolution of individual protection devices, have shown an urgent need of development in terms of the armour piercing capability of standard infantry small arms ammunition. The following paper includes a brief overview of the existing armour-piercing intermediate rounds, in an effort to define the most reasonable design of a perspective armour-piercing projectile. Therefore, various projectiles were designed and evaluated in terms of their external ballistic performance for chosen initial conditions, followed by preliminary internal and terminal ballistic calculations that were performed in order to assess the most reasonable outcome.

A promising direction in barrel ballistics aimed at increasing the muzzle velocity of a projectile is the use of new propellants as an attached charge. This paper presents an experimental and theoretical method for determining the law of propellant combustion in a manometric experiment (in a closed volume). Within the framework of this method, a small number of experiments could be sufficient to determine a change in the law of combustion during the propellant burnout and depending on pressure. This method is demonstrated on the example of processing three experiments with model high-density propellant. The laws of combustion of high-density propellants, obtained in this study, can later be used to calculate the gas-dynamic parameters of a shot from a barrel system or a nozzle bomb (in a semi-closed volume) using these propellants. [ABSTRACT FROM AUTHOR]

Superior ballistic performance and the lightweight character of Ti alloys are considered as main reasons for their use in armour applications against a broad spectrum of ballistic threats, e.g. bullet, fragment or blast impact. Because dynamic loading caused by typical penetrators is characterized by high strain rates, only specific test methods allow a closer investigation of the respective material behaviour. In the present study, quasi-static and dynamic compression tests as well as ballistic tests were conducted on a twophase α+β alloy Ti-6Al-4V (in m%) manufactured by hot-rolling. Post-deformation heat treatments, influencing microstructure and mechanical properties were applied in order to compare three different microstructural configurations: as-rolled, mill-annealed and bimodal. While, on the one hand, ballistic tests were employed for the determination of the ballistic limit velocity v50, compression tests, on the other hand, delivered essential input parameters for the application of the Johnson-Cook constitutive model in a finite element simulation of the impact event. The comparison of experimental results to simulation results was supplemented by means of microstructural characterization of tested samples with the focus set on the prevalently observed deformation and damage mechanisms, as for example adiabatic shearing. [ABSTRACT FROM AUTHOR]

Hybrid composite materials combine different fibers in preform and take advantages of different mechanical behaviors for improving ballistic impact damage tolerances. Here we report ballistic impact damages of plain-woven laminates with different hybrids and stacking sequences. Three kinds of hybrid laminates, i.e., carbon/Kevlar, carbon/ultra-high molecular weight polyethylene (UHMWPE), and UHMWPE/Kevlar, had been prepared and tested in ballistic penetration with fragment simulating projectiles (FSP). The residual velocities of the projectiles and impact damage morphologies of the laminates have been obtained to show impact energy absorptions for the different hybrid schemes. A microstructural model of the hybrid laminates had also been established to show impact damage mechanisms with finite element analysis (FEA). We found that the UHMWPE/Kevlar hybrid laminates with Kevlar layers as the front face have the highest energy absorption capacity, followed by the carbon/Kevlar hybrid laminates with carbon layers as the front face. The main damage modes are fiber breakages, matrix crack and interlayer delamination. The ballistic damage evolutions from the FEA results show that the major damage is shear failure for front layers, while tension failure for the back layers. We expect that the ballistic impact performance could be improved from the different hybrid schemes. [ABSTRACT FROM AUTHOR]

The identification of firearms is of paramount importance for investigating crimes involving firearms, as it establishes the link between a particular firearm and firearm-related elements found at a crime scene, such as projectiles and cartridge cases. This identification relies on the visual comparison of such elements against reference samples from suspect firearms or those existing in databases. Whenever this approach is not possible, the chemical analysis of the gunpowder and gunshot residue can provide additional information that may assist in establishing a link between samples retrieved at a crime scene and those from a suspect or in the identification of the corresponding model and manufacturer of the ammunition used. The most commonly used method for the chemical analysis of gunshot residue is scanning electron microscopy with energy dispersive X-ray, which focuses on the inorganic elements present in ammunition formulation, particularly heavy metals. However, a change in the legal paradigm is pushing changes in these formulations to remove heavy metals due to their potential for environmental contamination and the health hazards they represent. For this reason, the importance of the analysis of organic compounds is leading to the adoption of a different set of analytical methodologies, mostly based on spectroscopy and chromatography. This manuscript reviews the constitution of primer and gunpowder formulations and the analytical methods currently used for detecting, characterising, and identifying their compounds. In addition, this contribution also explores how the information provided by these methodologies can be used in ammunition identification and how it is driving the development of novel applications within forensic ballistics. [ABSTRACT FROM AUTHOR]

This article deals with Ballistic interpretation of gunshot traces by presenting the main theoretical and practical aspects, which are related to forensic ballistics, firearms, traces left by them and some elements of forensic tactics and technique. [ABSTRACT FROM AUTHOR]

To improve the tactical and technical performance of pulse correction projectiles while maintaining stability in uncertain conditions and considering practical engineering constraints, this study performs a multi-objective robust optimization design of the aerodynamic shape and external ballistics of a projectile. The study utilizes an aerodynamic force engineering algorithm and numerical trajectory calculations to obtain the projectile's performance responses within the Latin hypercube design space. To enhance optimization efficiency, a stochastic Kriging surrogate model is established to capture the inherent uncertainty of limited input data. Ultimately, a Pareto optimal solution for the projectile is obtained using a non-dominated sorting multi-objective sparrow search algorithm. The results of this study demonstrate that the consideration of design uncertainty in the robust optimization of pulse correction projectiles leads to significant enhancements in both lateral correction ability and range while satisfying flight stability requirements. Moreover, when compared to deterministic optimization, the performance variability of the design is markedly improved. This research methodology provides valuable insights for optimizing the performance of pulse correction projectiles. [ABSTRACT FROM AUTHOR]

Some quadrupeds have evolved the ability of pronking, which consists in leaping by extending the four limbs simultaneously. Pronking is typically observed in some ungulate species inhabiting grassland populated by obstacles such as shrubs, rocks and fallen branches scattered across the environment. Several possible explanations have been proposed for this peculiar behaviour, including the honest signalling of the fitness of the individual to predators or the transmission of a warning alert to conspecifics, but so far none of them has been advocated as conclusive. In this work, we investigate the kinematics of pronking on a two-dimensional landscape populated by randomly scattered obstacles. We show that when the density of obstacles is larger than a critical threshold, pronking becomes the gait that maximizes the probability of trespassing in the shortest possible time all the obstacles distributed across the distance fled, and thus represents an effective escape strategy based on a simple open-loop control. The transition between pronking and more conventional gaits such as trotting and galloping occurs at a threshold obstacle density and is continuous for a non-increasing monotone distribution of the height of obstacles, and discrete when the distribution is peaked at a non-zero height. We discuss the implications of our results for the autonomous robotic exploration on unstructured terrain.

In criminal investigations, the Directorate for Investigation and Detective Management – Police investigators are required by Philippine National Police orders to conduct forensic science-based crime scene investigations. In order to ensure that every government employee adheres to the accepted belief that public office is a public trust, it is challenging to assess the work of police detectives performing crime scene investigations using forensic technology. This essential value of forensic science in police investigations is undeniable. This study discusses the scope of police forensic methods in ballistics, photography, and dactyloscopy, specifically in the Province of Antique. These issues regarding the scope of practices in conducting investigations and forensic examinations are expressed via a survey questionnaire and a series of statistical tests. In addition, the report outlines the difficulties experienced by these Philippine National Police investigators. The results of the study found that police investigators had a high level of forensic experience with ballistics and photography. Further, results revealed low level of forensic experience with dactyloscopy.. Therefore, Police investigators, among many solutions, may consider the following to be of great help: 1-attending relevant seminars and trainings involving dactyloscopy, and 2- specifying budget allocation for lacking equipment.

Evolution of contemporary military conflicts has revealed some shortcomings of existing individual small arms ammunition. The first attempts to undertake research and development works on new weapons and ammunition were made in the USA, however, some projects are also being launched in other countries. This paper presents a short review of the newly developed rounds for perspective small arms systems as well as an attempt to determine a caliber of perspective individual weapon. For this purpose, some preliminary external and terminal ballistic analyses were conducted for various diameter projectiles of the same design.

A letter published in the Journal of Translational Medicine discusses the immune response triggered by radiation therapy (RT). The letter explains that RT can have both immunomodulatory and immunosuppressive effects on the immune system. The authors conducted a study comparing two types of RT, shield RT (SRT) and conformal RT (CRT), and found that CRT was more effective at delaying tumor growth and improving survival due to a stronger CD8+ TIL-mediated immune response. The study also revealed that monocytes played a critical role in activating CD8+ TILs after CRT. The authors emphasize the importance of accurately describing the irradiation technique used in preclinical studies and highlight the need for further research on the immune mechanisms underlying RT efficacy. [Extracted from the article]

A recent study published in the journal Nature has provided new insights into the charge-transfer processes that occur in photocatalytic reactions. The researchers used unique methods involving time-resolved and spatiotemporally resolved measurements to monitor these processes in Cu2O semiconductors. They found that quasi-ballistic inter-facet electron transfer and spatially selective trapping are the predominant processes that facilitate efficient charge separation in photocatalysts. This knowledge could lead to the development of high-performance semiconductors for various applications. The study utilized surface photovoltage microscopy and time-resolved photoemission electron microscopy to observe the charge-transfer processes spatially and temporally. [Extracted from the article]

Shear thickening fluid (STF) is a dense colloidal suspension of nanoparticles in a carrier fluid in which the viscosity increases dramatically with a rise in shear rate. Due to the excellent energy absorption and energy dissipation of STF, there is a desire to employ STFs in a variety of impact applications. In this study, a comprehensive review on STFs' applications is presented. First, several common shear thickening mechanisms are discussed in this paper. The applications of different STF impregnated fabric composites and the STF's contributions on improving the impact, ballistic and stab resistance performance have also been presented. Moreover, recent developments of STF's applications, including dampers and shock absorbers, are included in this review. In addition, some novel applications (acoustic structure, STF-TENG and electrospun nonwoven mats) based on STF are summarized, to suggest the challenges of future research and propose some more deterministic research directions, e.g., potential trends for applications of STF. [ABSTRACT FROM AUTHOR]

This paper describes the method and results of an experimental study of unsteady burning rate of high-energy materials containing metal powder additives under depressurization at a rate of 140–160 MPa/s. The method based on stating and solving the inverse problem of internal ballistics is used to determine the unsteady burning rate. The studies are carried out for high-energy materials, including energy additives in the form of metal powders (ASD-4, ASD-6, and Alex aluminum powders), aluminum diboride, and dodecaboride. It is shown by analyzing the this study that the unsteady burning rate of high-energy materials under sharp depressurization is oscillatory and depends on the energy additive type. [ABSTRACT FROM AUTHOR]

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Rare earth-doped zinc oxide (ZnO:RE) systems are attractive for future optoelectronic devices such as phosphors, displays, and LEDs with emission in the visible spectral range, working even in a radiation-intense environment. The technology of these systems is currently under development, opening up new fields of application due to the low-cost production. Ion implantation is a very promising technique to incorporate rare-earth dopants into ZnO. However, the ballistic nature of this process makes the use of annealing essential. The selection of implantation parameters, as well as post-implantation annealing, turns out to be non-trivial because they determine the luminous efficiency of the ZnO:RE system. This paper presents a comprehensive study of the optimal implantation and annealing conditions, ensuring the most efficient luminescence of RE3+ ions in the ZnO matrix. Deep and shallow implantations, implantations performed at high and room temperature with various fluencies, as well as a range of post-RT implantation annealing processes are tested: rapid thermal annealing (minute duration) under different temperatures, times, and atmospheres (O2, N2, and Ar), flash lamp annealing (millisecond duration) and pulse plasma annealing (microsecond duration). It is shown that the highest luminescence efficiency of RE3+ is obtained for the shallow implantation at RT with the optimal fluence of 1.0 × 1015 RE ions/cm2 followed by a 10 min annealing in oxygen at 800 °C, and the light emission from such a ZnO:RE system is so bright that can be observed with the naked eye. [ABSTRACT FROM AUTHOR]