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This study investigates the effects of kinetic energy and projectile size on particle emission from a phenylalanine overlayer adsorbed on a graphene bilayer during argon projectile bombardment. Projectiles of various sizes (1–1000 atoms) and kinetic energies (0.5–40 keV) are used to study their impact on the ejection efficiency, mass distribution, and kinetic and angular spectra of the emitted substances. Particle ejection mechanisms are discussed in scenarios with and without sample perforation. Additionally, this study investigated the potential use of graphene in secondary ion mass spectrometry or neutral secondary mass spectrometry analyses. [ABSTRACT FROM AUTHOR]

The three body fragmentation of methane dication has been studied using the technique of cold target recoil ion momentum spectroscopy. The process is initiated by impact of energetic Ar9+ ions on neutral methane and the data is subsequently collected in coincidence with Ar8+ projectile. By analysing the dissociation channels leading to (H + H+ + CH 2 + ) and (H + H 2 + + CH+) fragments, it is concluded that these fragments are formed in a sequential manner via formation of molecular intermediates CH 3 + and CH 2 + respectively. It is shown that these molecular intermediates carry a few eVs as their internal energies, part of which is released when they emit an H-atom with the open possibility that the final detected fragments may still be internally excited. This was accomplished by analysing the two-steps of the sequential process in their own native frames. For a molecular system having three-dimensional structure, our results prove to be an ideal example to highlight the importance of using native frames for correct interpretation of the obtained results. Our results indicate that the dissociation of methane dication can be a major source of production of H-atoms in addition to H+ fragments with the probability of the two being of similar order. [ABSTRACT FROM AUTHOR]

A multivariant statistical approach was used to identify treatment conditions that improve the survivability of structural reactive material (SRM) projectiles upon launch and enhance energy release upon impact. The study included both mechanical testing of projectiles as well as their reactive characterization. The projectiles were launched in a high-velocity impact-ignition testing system and impacted an anvil for vented chamber calorimetry. This study examined a link between ultimate compressive stress and combustion performance. Two treatments were applied to consolidated aluminum projectiles including annealing and addition of silica (SiO2) inclusions. Results showed annealing at moderate temperatures resulted in intact SRM projectiles upon launch. Adding small concentrations (1–2 wt. %) of SiO2 to the SRM promoted fragmentation and combustion performance upon impact. Compared to the untreated projectiles, annealing with SiO2 inclusion processing treatments improved the energy conversion efficiency from 37–84% (for untreated projectiles) up to 54–98%. Increasing interparticle dislocation recovery by annealing while balancing inclusions promoting fragmentation upon impact was the key to optimizing combustion performance for SRM ballistic impact applications. [ABSTRACT FROM AUTHOR]

This article aims to encourage discussion on the dilemma of a non-nuclear US ally's nuclear preparedness through the case of South Korea. Despite the strong demands of its own nuclear armament by the people and North Korea's continuous and aggressive nuclear buildups, South Korea has been focusing on strengthening only its conventional options, such as the Kill Chain (preemptive strikes), KAMD (missile defence), and KMPR (conventional retaliation), in the name of the "Three-Axis System" (TAS). However, these have inherent limitations and are seriously challenged by North Korea's developments of solid-fuel, pull-up manoeuvring, and low-trajectory missiles. As a result, South Korea turned out to be in a dilemma between harmony with its ally, the United States, and a securer nuclear defence against the North Korean nuclear threat. South Korea should do its best to increase the effectiveness of its TAS options in close consultation with the US nuclear extended deterrence. However, it needs to expand its discussion on other options, such as its own nuclear armament, without seriously damaging its alliance with the US. The United States, in turn, should participate in the discussion instead of rejecting South Korea's options other than the TAS. [ABSTRACT FROM AUTHOR]

Ceramic-metal corrugated structures have attracted extensive attention because of their strong penetration resistance. In this study, the effects of geometric features and boundary constraints on corrugated structures consisting of a TC4 frame and five SiC ceramic prisms were explored by performing a series of ballistic tests. Deformation results were obtained using a three-dimensional scanner, and the dynamic response was observed using a high-speed imaging system. Numerical models of these tests were established and validated using experimental results. The results suggest that increasing the support and confining strength of ceramics delay their failure and increase their degree of breakage, thereby increasing the internal energy conversion ratio of the projectile and the energy absorption ratio of ceramics by 14% and 10%, respectively. Notably, a reasonable reduction in the strength of the frame partition expands the plastic deformation range of the frame and increases its energy absorption ratio by 10%. The conclusions of this study provide a reference for designing corrugated composite structures. [ABSTRACT FROM AUTHOR]

The effect of nuclear size on different observables in fragmentation reactions is investigated using the quantum molecular dynamics approach. The present study is carried out using 36 , 37 Mg projectiles on various target nuclei ranging from 27 Al to 80 Br over a wide range of incident energies. Our findings revealed a significant influence (∼ 20 % ) of nuclear size on the energy of peak mass production in reactions involving lighter nuclei and this effect of nuclear size decreases for heavier targets. The role of nuclear size on the onset of multifragmentation is also investigated. Various order parameters, such as slopes of charge distribution and moments are seen to get influenced by this initialisation effect. However, the energy of the onset of multifragmentation in 37 Mg + 27 Al reaction is observed to be independent of nuclear size. [ABSTRACT FROM AUTHOR]

To solve the problem of the wall panel of high‐performance shelters protecting against the oblique penetration of projectiles, ballistic experiments were carried out with ultra‐high molecular weight polyethylene (UHMWPE) laminates subjected to normal penetration by high‐velocity projectiles, and the deformation and failure characteristics of UHMWPE laminates were analyzed. The numerical model of the resistance of UHMWPE laminates against penetration of projectiles was established by using the finite element program LS‐DYNA. The validity of the numerical model was verified by the experimental results of damage morphology and the depth of depression of the target plate and the deformation of the warhead. On this basis, the ricochet angle and failure mode of the UHMWPE target plate against projectile penetration were studied numerically, and the impact of the angle of incidence on the residual kinetic energy and normal penetration displacement of the bullet, as well as the damage morphology of the UHMWPE target plate, was revealed by using simulation. The results showed that the ricochet angle of the bullet obliquely penetrating into the UHMWPE target plate was in the range of 45° to 50°; at the initial stage of projectile penetration, the shear fracture failure of the fiber layer mainly occurred at the striking face of the UHMWPE target plate. Under the impact of the warhead deformation, with the reduction of the residual velocity of the bullet, the failure mode gradually changed to the tensile and interlaminar cohesion failure of the fiber layer near the back face; When the angle of incidence was greater than the ricochet angle, the residual kinetic energy of the projectile increased slowly with the increase of the angle of incidence of the bullet and then went up approximately linearly; the normal displacement of the bullet obliquely penetrating into the UHMWPE target plate decreased slowly after reaching the peak, and the peak value of the normal penetration displacement decreased gradually with the increase of the angle of incidence, and the time to peak of the displacement shortened gradually. The damage area of the bulge on the back surface of the UHMWPE target plate after penetration decreased gradually with the increase of the angle of incidence. The research results can provide a theoretical reference for the application of UHMWPE laminates in the design of military bulletproof shelters and armor. [ABSTRACT FROM AUTHOR]

This article concentrates on the problem of fixed-time tracking control for a certain class of nonlinear systems with unmodeled dynamics. Unmodeled dynamics are prevalent in practical engineering systems, such as axially symmetric systems like robotic arms, spacecraft, and missiles. In this paper, the fuzzy-logic systems (FLSs) are implemented to address the challenge of accurately approximating the unknown nonlinear terms that arise during the derived control algorithm process. By employing fixed-time command filters (FTCF), the "explosion of complexity" issues encountered in traditional backstepping methods will be effectively resolved. Moreover, error compensation mechanisms are derived to effectively mitigate the filtering errors that may arise from the FTCFs. The computational burden associated with FLSs is reduced through the utilization of the weight vector estimation method based on the maximal norm and an adaptive approach. A fixed-time adaptive fuzzy tracking controller is developed within the backstepping control framework to ensure the boundedness of all signals and achieve fixed-time convergence of the tracking error for the controlled system. Illustrative examples are conducted to illustrate the viability of the derived controller. [ABSTRACT FROM AUTHOR]

Velocity measurements of fast-moving objects are essential to a growing number of geotechnical applications. A photonic Doppler velocimeter (PDV) was configured to acquire the velocity–time history of a decelerating projectile from impact into soil through final burial. The PDV was setup using two independent lasers that were frequency shifted by approximately 0.2 GHz, which permitted recording low velocity data that are typically lost in homodyne configuration employing one laser only. Validation tests were carried out using a rotating target which verified the PDV measurements. The PDV was deployed in a vertical impact laboratory range to obtain deceleration records within carefully prepared soil targets. Two penetration tests into clayey sand targets that were performed by impacting conical projectiles are presented to demonstrate the repeatability of the experimental methodology. In this study, deceleration histories from impact at a velocity of 155 m/s were measured. Time-dependent depth of penetration and penetration resistance were calculated, with high fidelity, from the velocity–time records. The results were nearly identical for both tests for the velocity–time record, and it was possible to track the penetration velocity down to 20 m/s. This demonstrates that PDV measurements are well suited for measuring penetration resistance at ballistic velocities. [ABSTRACT FROM AUTHOR]

The damage stages of the ballistic impact effect on both thin and thick laminated composites were investigated. Thin and thick laminated composite plates were produced with unsymmetrical cross-ply [0/90], [–45/+45], and [30/60] layups consisting of 16 and 50 unidirectional layers, respectively. Ballistic tests of the composite plates were carried out by means of a single-stage gas gun system at different velocities in the range from 447 to 861 m/s. The thin composite plates were more damaged than the thick plates at ballistic tests with the same velocity. Relatively small strains were observed at low-velocity impact while the projectile rebounded in all thick specimens. All thick plate specimens, except the plates with [–45/+45] layup, were perforated at high velocity impacts. Tests showed an increase in the shear stress between layers with increasing projectile velocity. [ABSTRACT FROM AUTHOR]

The finite element model of oblique penetration of short-rod projectile into a thin metal target was established and the effectiveness of the model was verified to study the oblique penetration law of short-rod projectile into a thin metal target. The simulation calculation of short-rod projectile penetrating thin metal targets with different obliquities at different impact velocities was carried out. The simulation results show that the critical ricochet velocity of the projectile increased with the increase of the obliquity of the target plate, as well as the increment of the critical ricochet velocity of the projectile. With the increase in the obliquity of the target plate, the ultimate penetration velocity of the projectile increases exponentially, and when the obliquity is large, the ultimate penetration velocity increases sharply. When the projectile ricocheted without invading the target, the velocity attenuation of the projectile increased with the increase of the impact velocity, whereas the mass of the residual projectile decreased. However, when the impact velocity exceeds the ultimate penetration velocity of the projectile to the target plate, the velocity attenuation of the projectile decreased and the mass of the residual projectile increased with the increase of the impact velocity. With the increase of impact velocity, the included angle decreased gradually, and the decreasing trend also slowed down. When the impact velocity was just greater than the ultimate penetration velocity, the included angle was the largest. At the same impact velocity, the greater the obliquity of the target plate, the greater the included angle. This study is of great significance to reveal the critical ricochet and ultimate penetration of projectile, the velocity, mass, and trajectory change in the process of penetration, as well as the damage of projectile to the target plate. [ABSTRACT FROM AUTHOR]

It has become obvious that one crucial aspect in understanding high energy nuclear reactions is the fragmentation of colliding nuclei. The nuclear emulsion is a 4 π detector that makes it simple to identify and quantify the charges of projectile fragments. In this work, we study the multiplicity distribution and angle distributions of single, double charge projectile fragments, fast target protons (gray particle) as well as their correlation for the events produced in the interactions of 8 4 Kr 3 6 with emulsion nuclei at 1 A GeV. We also study the target-dependent angle distribution of gray particles. The results are compared with other experimental data as per availability. This analysis shows that multiplicity distributions have a remarkable link between the projectile and target fragmentation processes. [ABSTRACT FROM AUTHOR]

Accurately predicting the drift of spinning projectiles in the highland region has always been a challenging task. The study combines genetic algorithm, modified mass ballistic model, and data from ballistic tests to establish a computational model of projectile plateau drift, which is able to compute the value of projectile drift accurately. The reliability of the model was verified by the tests. The study also explains the reasons for the formation of projectile drift and the characteristics of plateau drift through theory. The results of the study proved that under the same range, the projectile's yaw of repose angle is larger in the plateau region, but its projectile plateau drift is smaller mainly because the flight time of the projectile on the highland is smaller than that on the plains. The results of the study are of great significance for the precision strike of projectiles in the highland area. [ABSTRACT FROM AUTHOR]

The water entry of a projectile constrained by polar floating ice presents a unique cross-media challenge. This paper investigates the dynamics of oblique water entry for a projectile influenced by floating ice using the fluid–structure interaction (FSI) method. The validity of the numerical method has been confirmed through experimental validation. The water entry process of a projectile from the side of the floating ice is examined. The evolution of the cavity and the movement patterns of objects as the distance between the projectile and the floating ice decreases toward collision are investigated. The influence of water on the critical collision distance between the projectile and the floating ice during oblique water entry is analyzed. Additionally, the physical mechanism of floating ice deflection through collision is investigated based on the theory of cavity dynamics. Subsequently, the study focuses on the oblique water entry process of a projectile colliding with the upper surface of the floating ice. Different entry angles determine the collision mode between the projectile and the floating ice surface. This study also examines how varying entry angles influence cavity evolution and object movement patterns during oblique collisions. Different collision modes between the projectile and the floating ice lead to asymmetric cavity evolution and various modes of object deflection motion. Finally, changes in the flow field and vortex structure during oblique collisions are studied to examine the influence of the FSI process between the projectile and the floating ice on the flow field. [ABSTRACT FROM AUTHOR]

This paper discusses using ground-based imagery to determine the attitude of a flying projectile assuming prior knowledge of its external geometry. It presents a segmentation-based approach to follow the object and evaluates it quantitatively with simulated data and qualitatively with both simulated and real data. Two experimental cases are considered: One assumes reliable target distance measurement from an auxiliary range sensor, while the other assumes no range information. The results show that in the case of an unknown projectile–camera distance, with projectile dimensions of 1.378 m and 0.08 m in length and diameter, the estimated distance, in-plane location, and pitch angle accuracies are about 50 m, 0.15 m, and 6 degrees, respectively. Yaw angle estimation is ambiguous. In the second case, assuming that the projectile–camera distance is known resolves the ambiguity of yaw estimation, resulting in accuracies of about 0.15 m, 3 degrees, and 20 degrees for in-plane location, pitch, and yaw angles, respectively. These accuracies were normalized to a 1-km projectile–camera distance. [ABSTRACT FROM AUTHOR]

This paper simulates the launching dynamics of the Terminal-guidance projectile considering the barrel thermo-chemical erosion wear and mechanical wear. A thermochemical erosive material degradation model that considers the rise in friction temperature is first introduced. Moreover, the wear state of barrel rifling at different periods is calculated using the erosion wear model. A three-dimensional model of the worn barrel is established, and the coupled barrel– terminal-guidance projectile launch dynamics are simulated for different wear periods. Finally, the projectile's bore overload and attitude are analyzed to explore the effect of barrel wear on launch. [ABSTRACT FROM AUTHOR]

The survivability of artillery projectile 155-mm Extended Range Full Bore Boat Tail (ERFB BT) inside gun barrel during gun launch mainly depends upon the mechanical properties of the shell body, boat tail and driving band materials. Any abrupt change in geometry of any one of these components can impair the structural integrity of the projectile, thereby resulting in malfunctioning of the projectile. Investigating the effect of abrupt change in geometry of the components is of much significance for assessing structural integrity. To investigate the effect of abrupt change in geometry of the components on structural failure, the notch tensile tests are performed to quantify the data on notch strength ratio (NSR), stress triaxiality and true fracture strain of the materials. To identify the mode of failure, the fractographic examination of the fracture surfaces is made. NSR is found more than unity; stress triaxiality determined by applying Bridgman's analysis reveals notch strengthening behavior of the materials. The fractographic examination shows that the shell body and boat tail materials fail in the combined ductile and brittle mode, whereas the driving band material fails by ductile mode. The outcome of the investigation confirms the load-carrying capacity and structural integrity of the projectile. [ABSTRACT FROM AUTHOR]

A unique 2 mm‐wide clast of fine‐grained garnet–omphacite peridotite with chondritic chemistry was reported from the CR2 chondrite Northwest Africa 801 by Hiyagon et al. (2016, Geochimica et Cosmochimica Acta, 186, 32–48). Those authors described the clast as eclogitic and inferred from its mineral compositions that the rock formed quickly, during perhaps 100–1000 years of burial, deep within a Moon‐sized body at about 3 GPa (30 kbar) pressure and 1000°C. Such conditions are unprecedented among meteorites and invite scrutiny. Here, we discuss the clast and its origin. The inferred conditions appear justified, but the published idea of burial during a protoplanetary merger and, soon after, exhumation in a violent collision seems improbable and contrary to the clast's low shock levels. We find that exhumation is better explained by pull‐apart of a projectile in a low velocity hit‐and‐run collision. We try inconclusively to explain near‐simultaneous burial and exhumation in a hit‐and‐run return scenario. Taking a different approach, and to conclude, we speculate that an approximately lunar‐mass body was molten beneath a thin dense chondritic crust, of which fragments foundered and sank deep into the magma ocean as an ongoing process. Fragments that were changing to garnet–omphacite peridotite were exhumed when the molten body was pulled apart in a hit‐and‐run collision with a larger body. [ABSTRACT FROM AUTHOR]

Background and importance: Nonpowder firearm injuries to the head pose major health risks, with retained fragments potentially causing harmful sequelae that require neurosurgical intervention. Clinical presentation: We report the case of 2-year-old girl who sustained an accidental gunshot wound to the head. She sustained a penetrating ballistic intracranial injury caused by a BB shot from a rifle. At presentation, she was neurologically intact with a punctate laceration on her left forehead. Head CT demonstrated a small depressed left frontal skull fracture, a small intracerebral hematoma, and a 5-mm metallic bullet fragment in the deep left frontal lobe near the frontal horn of the left lateral ventricle. She was admitted to the hospital and managed nonoperatively with levetiracetam and intravenous antibiotics, and discharged home in good condition. Follow-up CT in 1 week showed slight migration of the metallic bullet fragment to the left, placing it at the anterior horn of the lateral ventricle. Six weeks later, follow-up CT showed migration of the bullet to the temporal horn of the left lateral ventricle. Intraventricular migration of the bullet raised concern that it could move further to obstruct the foramen of Monro or cerebral aqueduct. Therefore, we removed the bullet through a small left temporal craniotomy with image guidance using a microsurgical approach through a translucent tube. Conclusion: The authors discuss the rationale and technique for removing a nonpowder firearm bullet that has migrated within the cerebral ventricles. [ABSTRACT FROM AUTHOR]

This study investigates the effects of baffles and various other design changes on a partially filled fuel tank subjected to high-velocity projectile impact. Modelling of the tank filled with water is done using ANSYS software. The Eulerian domain is used to analyse water, whereas the Lagrangian domain is used to assess the tank and bullet. The developed finite element model is verified with available results in the literature. The effect of design parameters like edge fillet, number of baffles, thickness of baffles, orientation of baffles, height of baffles, position of the projectile and projectile speed on the impact responses of the fuel tank is studied. From the analysis results, it could be observed that the edge fillet provided the minimum stress due to the lower stress concentration on the fuel tank, but it was not effective in decreasing the velocity of the projectile. Therefore, the baffles are introduced inside the fuel tanks, which are highly effective in reducing the velocity and generating huge stress on the tanks. The velocity and position of the projectiles are also varied to understand their effect on the fuel tank. [ABSTRACT FROM AUTHOR]

This article discusses the challenges faced by NATO during the Cold War. It highlights two main challenges: the Soviet Union's aggressive behavior and nuclear disarmament proposals. The article focuses on the period of the late 1970s when the Soviet Union expanded its nuclear arsenal and developed a new intermediate-range nuclear missile. NATO responded with a dual-track proposal, offering disarmament negotiations with the Soviets while also deploying nuclear missiles if the talks failed. The Soviet Union launched a propaganda campaign to oppose the deployment of new weapons, which led to public opposition in Western European countries. Despite the pressure, Western European parliaments voted in favor of stationing U.S. missiles. The article also discusses the subsequent disarmament talks between the U.S. and the Soviet Union, which resulted in the INF Treaty in 1987. The author argues that Gorbachev's repeated offers to negotiate and disarm could have undermined NATO if the Cold War had not ended. The article concludes by stating that NATO was not destroyed by the debates over the Euromissiles and that the end of the Cold War presented a greater challenge to the alliance. The author also mentions the recent threat posed by Russian aggression and the potential withdrawal of the United States from NATO under President Donald Trump. [Extracted from the article]

Several black and white Italian cabassets, and associated armours, are described. All share an unusual, recessed construction and typically bear an etched family crest on the front. The cabassets also have (1) a predominantly Spanish distribution, (2) a high frequency of damage, including tears (that may reflect exposure to ballistic projectiles), (3) a high frequency of paired holes in the brim (for conversion into make-shift buckets?), and (4) distinctive copper-alloy plume-holders. We critically evaluate the stylistic, historical, geographic, ballistic and archaeological evidence that may link these recessed cabassets with the 1588 Spanish Armada. Furthermore, the distinctive family crest on the cabassets, and one breastplate, may provide specific links with a Spanish infantry company commanded by Captain Fernando de Ayala on the Armada's flag galleass, the San Lorenzo. In combination, these independent lines of evidence suggest that the recessed cabassets were used by troops on the Spanish Armada. [ABSTRACT FROM AUTHOR]

A novel integrated guidance and control scheme is derived for STT missile with strict constraints as desired impact angle, input saturation and partial system state in three-dimensional space. The backstepping technique and command filter are adopted for achieving input constraints, and the improved compensation signals are constructed to correct tracking errors. The integral barrier Lyapunov function is introduced to prevent the partial system states from exceeding a predefined interval. A modified extended state observer is employed to strengthen the robustness of the system further. Theoretically, the required properties of a closed-form system are proved by Lyapunov theory in detail. Numerical simulations are conducted to exhibit the performance and robustness of the IGC scheme fully. [ABSTRACT FROM AUTHOR]

Canted fins can significantly improve the flight stability and the on-target accuracy of Explosively Formed Projectiles (EFP). The current work uses the effective charge theory to derive the formation of periodic tails from shaped charge with stepped casing by considering the detonation impulse. According to the established model, the distribution of velocity along the circumference of the liner increases linearly with the square root of the casing thickness. There are two stages in the formation of canted fins influenced by the stepped casing: (1) the distribution of velocity along the circumference of the liner upon initiation, and (2) the torsion and folding of the liner edge during deformation. Numerical simulation was carried out with LS-DYNA for shaped charge (56 mm in diameter) with regular and stepped casing. The expansion of the casing and the deformation of the liner with velocity distribution at initial times were compared between the regular and the stepped casing. The distribution regularities and the final velocity of the canted fin EFP from the simulation agree well the established velocity distribution model. Soft recovery experiments were also carried out to prove the feasibility of using shaped charge with stepped casing. [ABSTRACT FROM AUTHOR]

It is of great significance to explore the ocean environment and strategic deployment under the polar ice layer. In this paper, the evolution laws of the water entry cavity of projectiles passing through ice holes with different shapes and sizes are studied, and the motion states of projectiles passing through holes are described. The case of zero-gap contact motion between a projectile and a hole is considered. The results show that the initial resistance drag of the projectile passing through the circular ice hole is the largest in the case of zero-gap contact, and the cavity collapse is serious, while almost no cavity appears at the shoulder of the projectile when passing through the square hole. The intersection of splash crowns is formed at the square and triangular ice holes as the hole size increases, a diffused cavity is formed at the bottom of the hole edge, and the formation of the jet appears multiple times at each stage. Some unique vortices appear near the hole when the projectile passes through the hole. The variations of force and velocity of the projectile passing through the triangular hole are stable, but the velocity drop is the largest. [ABSTRACT FROM AUTHOR]

Spin separation technology is a key technology for realizing the detection function at the end of the rotational trajectory. It is also a necessary condition for the fuse control system to adjust its control strategy according to actual combat needs. To explore a new type of proximity fuse detection method, this article first designs a detection separation mechanism for the end of the trajectory. An interior ballistic model of the separation mechanism was then established through closed bomb tests and equivalent interior ballistic equations, and the aerodynamic parameters of the front-stage separation body at the moment of separation were obtained based on computational fluid dynamics numerical simulation. Finally, a separation dynamics model of the separation mechanism was established to analyze the motion state after the separation action of the front-stage separation body. The results demonstrate the feasibility of the proposed separation mechanism. The discrepancy between the simulation and experiment of the velocity increment for the front-stage separation body is about 1.07%. The attack angle for the front-stage separation body is below 2°, and the period with a displacement between two stage bodies greater than 3 m is around 0.365 s. This research can provide new ideas and theoretical references for the design of a similar fuse detection separation mechanism. [ABSTRACT FROM AUTHOR]

Reducing recoil as well as reducing muzzle hazards are important issues in artillery design. This paper presents a barrel gas reflection method for the artillery aiming for efficient recoil reduction while reducing muzzle hazards. The launching process is modeled by coupling the interior ballistic equations and the flow equations of the barrel gas reflection device. The fourth-order Runge–Kutta method was used to solve the model, and the LHS method as well as the Kriging model was used to establish a mapping relationship between the parameters and the effect. To validate the proposed model, shooting experiments are carried out on a 30 mm caliber artillery. The maximum error between the experiment and simulation results was 5.32%. The experiment has demonstrated that the barrel gas reflection method increases the recoil reduction efficiency of artillery by 44.54% and reduces the muzzle hazard by 52.18%. Finally, the barrel gas reflection method can produce effects with the muzzle device at the same time, and it has little effect on the velocity of the projectile muzzle velocity, and it provides a new way of thinking for the development of future artillery recoil reduction technology. [ABSTRACT FROM AUTHOR]

A structured dynamic overlapping grid and a user-defined function are used to study the projectile launching process, and the hybrid Roe scheme is used to solve the flow field with strong shock wave. The launching process of a projectile with a muzzle decompression device is numerically simulated by using a three-dimensional transient model, and the flow field inside the muzzle decompression device and the development process of the muzzle flow field in the projectile launching process are discussed in detail. Compared with no device, the muzzle decompression device can effectively reduce the peak pressure around the muzzle; the numerical results are in agreement with the corresponding experimental values. The numerical investigation in this paper is helpful to understand the mechanism of pressure reduction of the device. It also provides a new way to reduce the muzzle pressure of aircraft gun. [ABSTRACT FROM AUTHOR]

Graphene nanoribbon woven fabrics (GNWFs) with excellent mechanical properties are promising for ballistic armor materials. The dynamic response of single-layer and bilayer GNWFs under nano-projectile impact at high-speed (4–5 km s−1) is investigated by molecular dynamics simulations. Results show that the woven structure is determined by the bandwidth and gap spacing, which influences the deformation/fracture and motion coupling effects of the crossed nanoribbons and the ballistic performance of GNWF. Owing to the perturbation of the van der Waals (vdW) interface between nanoribbons, the specific penetration energy of GNWFs reaches 16.02 MJ kg−1, which is much higher than that of single-layer graphene (10.80 MJ kg−1) and bilayer graphene (10.07 MJ kg−1). The peculiarities of woven structure minimize the damage of GNWFs, on the one hand, the reversibility of vdW interactions and the entanglement of nanoribbons provide GNWFs a certain self-healing ability. On the other hand, the porous nanostructure of twist-stacked bilayer GNWFs tends to be uniform and dense with the twist angle, which improves the impact resistance. This study provides more understanding of the ballistic properties of GNWFs and the design of nano-fabrics based on two-dimensional materials. [ABSTRACT FROM AUTHOR]

Linear induction launchers (LILs) are a specific subtype of linear motors. However, LILs are air-core machines that consistently operate in a transient rather than a steady state. Moreover, their operating currents and voltages exceed those of traditional machines. The execution time of LILs often remains within a few milliseconds, and it is essential to manage extremely high-power levels quickly. The control methods for LILs differ from those used for regular machines due to the differences from conventional linear motors. In this respect, there are still challenges to be overcome in power systems designed for LILs in the literature. This study has developed a novel power energization system to address these challenges, particularly in terms of inadequate V/f control and the unnecessary energization of regions along the barrel where no projectile is present. It focuses on the system's design using multi-stage H-bridge inverters to produce a sinusoidal current for section-by-section polyphase excitation. An FPGA-based electronics control system generates bipolar PWM fiber-optical signals for IGBT switches for scalar V/f control of the inverters. Distributed multi-inverters power each stage of the launcher's barrel and are controlled by the FPGA to create the travelling electromagnetic wave package. Three-dimensional FEM analysis is used for observation of the trigger timing to ensure positive force along the barrel. By driving each inverter independently, the coils on the barrel are excited sequentially based on the position of the projectile. This study also explains the implementation of a laboratory-scale barrel prototype, a 40 mm aluminum projectile, its power electronics, and the control part of the multi-stage inverters. In this study, 3300 V–1200 A IGBTs and 8.8 mF–2000 V DC-Link capacitors were used in the H-bridge inverter modules. Experimental studies have been conducted on the launcher, and the results obtained, including achieving a velocity of 30 m/s, are consistent with the electromagnetic simulations. It has been observed that the launcher, powered by the proposed system, is approximately 57.14% more efficient compared to the version energized by a single inverter. [ABSTRACT FROM AUTHOR]

The measurement of fusion cross sections from the 9 Be induced reaction on 93 Nb within the energy range of 20–46 MeV has been conducted using off-beam γ -ray spectroscopy. The measured excitation functions have been analyzed using equilibrium and pre-equilibrium reaction-based model codes to understand the underlying mechanisms. Additionally, the measured fusion excitation function was examined within the framework of the coupled-channel approach using the CCFULL code. Notably, the coupled-channel calculations, including couplings to inelastic states of the target and the projectile, yielded a satisfactory description of the sub-barrier fusion data. However, at energies above the barrier, the fusion cross section was observed to be suppressed by approximately 17% compared to the predictions made by the coupled-channel calculations. [ABSTRACT FROM AUTHOR]

The Marymoor Site (45KI9) has long frustrated students of Northwest Coast precontact history because it contains a unique artifact assemblage that has been considered unsuitable for analysis for over 50 years. The problems that researchers encountered were that the collection was chronologically mixed and that they attempted to use the collection in its entirety. This consistently led to non-significant results. By reducing the collection to only the excavation units that contained discernable geologic stratification, we were able to isolate two chronologically discrete analytic units. Radiocarbon analysis of calcined bone from these units enabled us to date them to between 8000 and 5950 cal. B.P. This allows the site to be accurately placed in the cultural sequence of the southern Puget Sound. Marymoor is unique in Salish Sea archaeology as a node in the limited geographic distribution of side-notched projectile points and associated microblades within and west of the Cascade Range. Pondering this, we offer several alternatives, including the possibility that the ethnic geography of the region might at times have differed from the pattern observed at European contact. [ABSTRACT FROM AUTHOR]

Purpose: One of the challenges encountered in the design of guided projectiles is their prohibitive cost. To diminish it, an appropriate avenue many researchers have explored is the use of the non-actuator method for guiding the projectile to the target. In this method, biologically inspired by the flying concept of the single-winged seed, for instance, that of maple and ash trees, the projectile undergoes a helical motion to scan the region and meet the target in the descent phase. Indeed, the projectile is a decelerator device based on the autorotation flight while it attempts to resemble the seed's motion using two wings of different spans. There exists a wealth of studies on the stability of the decelerators (e.g. the mono-wing, samara and pararotor), but all of them have assumed the body (exclusive of the wing) to be symmetric and paid no particular attention to the scanning quality of the region. In practice, however, the non-actuator-guided projectiles are asymmetric owing to the presence of detection sensors. This paper aims to present an analytical solution for stability analysis of asymmetric decelerators and apprise the effects of design parameters to improve the scanning quality. Design/methodology/approach: The approach of this study is to develop a theoretical model consisting of Euler equations and apply a set of non-dimensionalized equations to reduce the number of involved parameters. The obtained governing equations are readily applicable to other decelerator devices, such as the mono-wing, samara and pararotor. Findings: The results show that the stability of the body can be preserved under certain conditions. Moreover, pertinent conclusions are outlined on the sensitivity of flight behavior to the variation of design parameters. Originality/value: The analytical solution and sensitivity analysis presented here can efficiently reduce the design cost of the asymmetric decelerator. [ABSTRACT FROM AUTHOR]

Despite the fact that a large amount of small arms ammunition has been used up over the past two years, their stocks in warehouses and arsenals in various countries are quite large. And their shelf life is 20 years or more. In addition, over time, the number of such ammunition will increase. Among the large number of requirements for modern small arms, one can highlight the provision of the necessary survivability of its parts and mechanisms. The problem of barrel survivability is especially important. One of the factors affecting barrel survivability is changes in internal ballistics parameters. In turn, these parameters change when using ammunition whose service life exceeds the warranty. In this regard, the task of studying the survivability indicators of small arms barrels when using post-warranty ammunition seems relevant. The requirements for barrel systems and factors affecting the wear of the barrel bore of powder charges during long-term storage have been determined. An analysis of changes in the ballistic characteristics of powder charges was carried out, which allows to state increased wear of barrels when using ammunition with long storage periods. The dependencies for determining the limit number of shots from a weapon sample are analyzed. A method for predicting barrel survivability when using long-term storage ammunition is proposed. Data are presented on an experimental study to determine changes in barrel survivability as a result of the use of long-term storage ammunition by estimating changes in the initial velocity of the projectile. Based on the results obtained, ways for further research are proposed in the direction of expanding the range of ammunition and weapons. [ABSTRACT FROM AUTHOR]

The article presents a numerical study of the high-speed impact of a steel projectile on a concrete target. Calculations have been carried out within the framework of a porous elastoplastic medium. The dynamic fracture is considered as the growth and coalescence of microdefects under the action of stresses formed during loading. The projectile interacts with the target at a speed of 600 m/s. As a result of impact loading, through penetration occurs in the concrete target with the formation of a crater on the front side and a back spall. [ABSTRACT FROM AUTHOR]

The ability of the projectile to strike accurately in the air depends on the accurate measurement of its flight distance. Due to the influence of the external environment, it is very difficult to measure the distance of high-speed projectiles in real time with ranging equipment such as radar and laser. Based on this, a real-time measurement model of the horizontal flight distance of the projectile was designed, which combines trajectory equation and discrete acceleration. First, the angle of inclination of the projectile at each position was calculated according to the six-degree-of-freedom rigid outer trajectory model. Then, two kinds of distance measurement models based on discrete acceleration integration were introduced, and the accuracy simulation was carried out. Simulation results show that the Simpson integral method is more accurate. The flight arc length of the projectile was calculated by the Simpson integral method. Finally, the horizontal flight distance of the projectile was obtained by combining the flight arc length and inclination angle of the projectile. Finally, the flight distance measurement model was simulated, and the simulation results show that the model has high accuracy. The simulation results show that the horizontal flight distance of the projectile can be measured by the trajectory equation and discrete acceleration according to the set conditions. This method can be used to measure the distance of the projectile by carrying the sensor and is less affected by the external environment. It can provide a theoretical basis and reference for the measurement of the horizontal distance of the projectile. [ABSTRACT FROM AUTHOR]

Flow control techniques play an important role during water entry. In this paper, the idea of water entry of the projectile with single canard-wing is proposed and applied to the water entry problem. The cavity evolution and motion characteristics of projectile with canard-wing were investigated through experiments, and the cavity length, trajectory, and attitude changes of projectile with canard-wing during water entry were quantified. The results show that, different from the water entry process of projectile without wing, the projectile with canard-wing has the typical characteristics of forming the attached cavity on the wing. Due to the influence of canard-wing, the trajectory deflection is always toward the side without the wing, and the initial moment of trajectory deflection is advanced with the increase in the impact velocity. The length of the fore-end cavity and the attached cavity on the wing increases as the impact velocity increases and the pinch-off depth of the fore-end cavity also increases. Moreover, the deviation of the trajectory and the attitude angle of the projectile with canard-wing increases as the impact velocity increases during water entry. The results can provide important support for the passive flow control during the water entry of the projectile and the development of the trans-media aircraft. [ABSTRACT FROM AUTHOR]

In this study, ventilated cavitating flow characteristics around an axisymmetric projectile are investigated by combining experiments and numerical simulations. Experiments were carried out with a Split–Hopkinson pressure bar launch system and the pressure-equaling exhaust technology. Modular projectiles are designed to experimentally investigate the influence of head shape and ventilatory volume on flow characteristics. Large eddy simulation model is applied to obtain more flow field information. Compared with the conical head projectile, the hemispherical head projectile has a thinner attached cavity and more local detachment of the cavity. The statistical structure of the velocity and pressure fluctuations are analyzed by combining histograms and Q–Q diagrams. The results show that the pressure drag is dominant in the total drag and the periodic pulsation of the tail cavity and the stable vortex structure at the tail cause the variation of drag. The larger cavity volume changes the actual shape of the projectile, making the drag of the conical head projectile higher. The evolution characteristics of the cavitating flow field around the projectile with different ventilatory volumes are obtained, and the relationship between pressure fluctuation and chamber volume is derived. It is found that the reentrant jet causes a reverse flow at the nozzle, which leads to local pressure rise at the same interval. The above research work could contribute to the design and flow control of the ventilated cavity body. [ABSTRACT FROM AUTHOR]

Photodiode‐type solar‐blind photodetectors (SBPDs) with the self‐powered feature hold great promise for applications in unattended secure communication, flame detection, and missile warning. However, the responsivity of SBPDs is usually limited due to the severe solar‐blind (SB) light extinction in substrates and charge transport layers. Herein, a spectrally selective hole extraction structure (SHE) is proposed for high‐efficiency perovskite SBPDs. The SHE consisting of a tandem Fabry–Perot cavity and energy‐level‐matched hole transport layer endows the device with narrowband absorption in the SB region and optimized charge extraction capability from the CsPbI2Br perovskite. The optimized SHE exhibits a peak transmittance of 27% at 255 nm and a half maximum at full width of 28 nm. Under SB light illumination, the champion device achieves a responsivity of 56.20 mA W−1 and a detectivity (D*) of 2.86 × 1013 Jones, which are the record values among the reported results. The approach demonstrated here paves the way for the optical and electrical design of perovskite photodetectors with spectrally selective detection. [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]

This article delves into Captain Samuel Alfred Warner's dogged campaign to sell two inventions – his submersible mine and "long range" missile – to the British government in the 1840s and 1850s. Departing from a historiography that dismisses Warner as a fraudster, it clarifies how he managed to generate widespread interest in his weapons technologies for nearly twenty years. I therefore analyze three key elements of his self-promotion: his personal branding, his pitch, and his simultaneous embrace and rejection of publicity. Neither elite nor highly educated, Warner ran up against a culture of "polite science" that distinguished disinterested practitioners from profit-minded schemers. To establish his credentials, he emphasized his practical maritime experience and represented himself as a martyr willing to bear the scorn of a disbelieving establishment. In pitching his devices, Warner capitalized on alarmism over border security and the integrity of the empire; he declared that they could hobble France's modernizing navy and quickly end colonial conflicts. When skeptics began to fret over the proliferation of his destructive weapons, Warner flipped the script and lauded the threat of mutual annihilation as a deterrent to needless warfare. The issue of publicity, however, would ultimately be Warner's professional undoing. Despite successful demonstrations, his clashes with official investigators and his refusal to disclose his chemical secrets led critics to dispute the originality of his discoveries. An examination of Warner's self-promotional strategies, his fraught interactions with the British state, and the ambivalent public reaction to his contraptions provides insight into how scientific authority was acquired and lost in this period. [ABSTRACT FROM AUTHOR]

The article explores the topic of projectile motion through an experiment conducted by Alice and Bob. They used a high-speed camera to capture the movement of a projectile and discovered that its trajectory formed a parabola. The article provides equations and tests to determine the aspect ratio of the trajectories and offers hands-on projects of increasing difficulty related to projectile motion. It emphasizes the importance of accurate measurements and uncertainties in conducting such experiments. The article also discusses the use of scaling and geometric approaches, data fitting, and suggests using simulations and video recordings for analysis. Overall, it provides practical methods for understanding and studying projectile motion. [Extracted from the article]

The cell array type significantly affects the global stresses in curved honeycomb sandwich panels. In this study, the curved sandwich panels with the out-plane honeycomb core (COP) and the in-plane honeycomb core (CIP) are proposed. Their local impact resistance is numerically investigated using finite element simulation calibrated with air cannon test results. Various impact scenarios including different projectile diameters, different impacting velocities, angles, as well as locations are considered. The performances of the COP and CIP panels with similar overall mass and relative density are compared by evaluating their impact histories and energy absorption properties. It is demonstrated that the CIP panel shows improved impact mitigation and energy absorption property under local impact. However, its overall displacement is significantly larger than that of the COP panel. Based on the impact behavior of COP and CIP panels, the hybrid two-layer structures (HOI and HIO) are designed. It is found that the HIO panel shows an increase in energy absorption of approximately 3% over the COP and CIP panels and a reduction in the overall displacement of at least 28% over the CIP panel. Moreover, HIO configuration with the thinner cell wall thickness of the upper core demonstrates improved impact mitigation. [ABSTRACT FROM AUTHOR]

A mathematical method is developed for solving the problem of detonation initiation in a hydrogen–air mixture by a small-diameter sphere flying with a velocity greater than the Chapman–Jouguet detonation velocity. The mathematical model verification is performed against experimental data on the detonation cell size in hydrogen–oxygen and hydrogen–air mixtures. Depending on the pressure in the mixture, which is varied from 100 to 250 kPa, three types of oblique detonation waves are obtained: (1) stabilized oblique detonation wave at 250 kPa; (2) stabilized oblique detonation wave of the "straw hat" type at 200 kPa; (3) periodic regime with an attenuated oblique detonation wave, which was not observed in previous experiments, at 125 kPa. At 100 kPa, a regime of shock-initiated combustion is observed. Based on an analytical dependence, the energy of detonation initiation by a high-velocity projectile is estimated, and the analytical and numerical data are found to be in good agreement. [ABSTRACT FROM AUTHOR]

A general geometric model of the elliptical cross-section double-ogive-nose projectile (ECDP) was established, and the expression of penetration resistance was obtained. Based on the special shape and penetration process characteristics of the ECDP, a three-stage penetration model was constructed, and closed-form penetration equations were derived. Three ECDPs with the major-minor axis ratio of 1.5 were launched by a 130 mm gas-gun to impact the plain concrete targets with the oblique angle of 10° at a nominal striking velocity of 650 m/s, the experimental data such as the penetration depth of the ECDPs and the failure characteristic parameter of the targets was obtained. The initial posture of the ECDP had little effect on the penetration depth and trajectory deflection under the condition of the target with 10° oblique angle, but it had obvious influence on the structural response. The theoretical model was verified by experimental data, the calculated result of the penetration depth was in good agreement with the experimental data, the deviation was within the range of -13.5% ~ -8.5%. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate a novel impact time control guidance (ITCG) law based on the sliding mode control (SMC) for a nonmaneuvering target using the predicted interception point (PIP). Design/methodology/approach: To intercept the target with the minimal miss distance and desired impact time, an estimation of time-to-go is introduced. This estimation results in a precise impact time for multimissiles salvo attack the target at the same time. Even for a large lead angle, the desired impact time is achieved by using the sliding mode and Lyapunov stability theory. The singularity issue of the proposed impact time guidance laws is also analyzed to achieve an arbitrary lead angle with the desired impact time. Findings: Numerical scenarios with desired impact time are presented to illustrate the performance of the proposed ITCG law. Comparison with the state-of-art impact time guidance laws proves that the guidance law in this paper can enable the missile to intercept the target with minimal miss distance and final impact time error. This method enables multiple missiles to attack the target simultaneously with different distances and arbitrary lead angles. Originality/value: An ITCG law based on sliding mode and Lyapunov stability theory is proposed, and the switching surface is designed based on a novel estimation time-to-go for the missile to intercept the target with minimal miss distance. To intercept the target with initial arbitrary lead angles and desired impact time, the authors analysis the singular issue in SMC to ensure that the missile can intercept the target with arbitrary lead angle. The proposed approach for a nonmaneuvering target using the PIP has simple forms, and therefore, they have the superiority of being implemented easily. [ABSTRACT FROM AUTHOR]

Purpose: In recent years, increased use of all-aspect infrared (IR)-guided missiles based on the long-wave infrared (LWIR; 8–12 µm) band has lowered the probability of aircraft survival in warfare. The lock-on of these highly sensitive missiles is difficult to break, especially from the front. Aerodynamically heated swept-back leading edges (SBLE), because of their high temperature and large area, serve as a prominent LWIR source for aircraft detection from the front. This study aims to report the influence of sweep-back angle (Λ, based on the Mach number [M∞]) on aerodynamic heating and the LWIR signature of SBLE. Design/methodology/approach: The temperature along SBLE is obtained numerically as radiation equilibrium temperature (Tw) by discretizing the SBLE length into "n" number of segments, and for each segment, emission based on Tw is evaluated. IR radiance due to reflected external sources (sky-shine and Earthshine) and radiance due to Tw are collectively used to determine the IR contrast between SBLE and its replaced background in the LWIR band (icont-SBLE,LWIR). Findings: The results are obtained for low subsonic turboprop aircraft (Λ = 3°, M∞ = 0.44); high subsonic strategic bombers (Λ = 35°, M∞ = 0.8); fifth-generation stealth aircraft (Λ = 40°, M∞ = 1.6); and aircraft with supercruise/supersonic capability (Λ = 50°, M∞ = 2.5). The aircraft with supersonic capability (Λ = 50°, M∞ = 2.5) reports the maximum LWIR signatures and hence the highest visibility from the front. The results obtained are compared with values at Λ = 0° for all cases, which shows that increasing Λ significantly reduces aerodynamic heating and LWIR signatures. Originality/value: The novelty of this study comes from its report on the influence of Λ on the LWIR signatures of aircraft SBLE in the frontal aspect for the first time. [ABSTRACT FROM AUTHOR]

Tail slapping is considered to be a prominent mode for facilitating the movement of supercavitating projectiles underwater. Stability mechanism of the tail slapping and stability criterion of projectiles was numerically investigated in this paper. A numerical method was conducted to calculate the free flight of projectiles by combining the finite volume method, the mixture multiphase model, and a dynamic meshing scheme. The accuracy and applicability of the numerical calculation method are verified by experiments. Three typical stability modes of tail slapping motion, namely, stable, conditionally stable, and unstable, were identified through the free flight numerical simulations of projectiles with varying length-to-diameter ratios under different initial angular velocities. The stability criterion of projectiles was proposed, indicating that the tail slapping stability can be determined by analyzing the curve of the moment variation with the angle of attack at any velocity above 200 m/s. Furthermore, it was found that the stable projectiles possess inherent motion states that are exclusively determined by their structural features and are unaffected by the initial motion conditions. [ABSTRACT FROM AUTHOR]

The role of initial state (ISI) and final state (FSI) ion–ion interactions in heavy-ion double-charge-exchange (DCE) reactions A (Z , N) → A (Z ± 2 , N ∓ 2) are studied for double single-charge-exchange (DSCE) reactions given by sequential actions of the isovector nucleon–nucleon (NN) T-matrix. In momentum representation, the second-order DSCE reaction amplitude is shown to be given in factorized form by projectile and target nuclear matrix elements and a reaction kernel containing ISI and FSI. Expanding the intermediate propagator in a Taylor series with respect to auxiliary energy allows us to perform the summation in the leading-order term over intermediate nuclear states in closure approximation. The nuclear matrix element attains a form given by the products of two-body interactions directly exciting the n 2 p − 2 and p 2 n − 2 DCE transitions in the projectile and the target nucleus, respectively. A surprising result is that the intermediate propagation induces correlations between the transition vertices, showing that DSCE reactions are a two-nucleon process that resembles a system of interacting spin–isospin dipoles. Transformation of the DSCE NN T-matrix interactions from the reaction theoretical t-channel form to the s-channel operator structure required for spectroscopic purposes is elaborated in detail, showing that, in general, a rich spectrum of spin scalar, spin vector and higher-rank spin tensor multipole transitions will contribute to a DSCE reaction. Similarities (and differences) to two-neutrino double-beta decay (DBD) are discussed. ISI/FSI distortion and absorption effects are illustrated in black sphere approximation and in an illustrative application to data. [ABSTRACT FROM AUTHOR]