Explore the vast range of titles available.

The cross-media water entry problem widely exists in fields such as ocean engineering and aerospace. The highly non-stationary characteristics of the cross-media water entry process significantly influence the structural strength and ballistic stability of vehicles. This paper selects air-dropped torpedoes, supercavitating vehicles, and high-speed projectiles as three typical types of cross-media vehicles for study. Based on their unique structural characteristics and typical water entry conditions, this paper focuses on the current status of their respective impact load and load reduction challenges, as well as water entry ballistic stability issues. At the research methodological level, this paper systematically reviews the progress of current research in three directions: theory, experiments, and numerical simulations, and introduces the application of artificial intelligence in solving cross-media problems. Finally, this paper looks forward to future development trends in cross-media water entry research, aiming to provide a reference for structural optimization design, motion stability control, and other related studies of cross-media vehicles.

The study describes the results of static, physicochemical and ballistic examination of double-based gunpowder charges, in order to establish the deviations from the demanded quality of mortar ammunition. The examinations were carried out on gunpowder samples used for laboration of mortar shells 60, 82 and 120 mm caliber and consisted of periodical measurements of the gunpowder mass loss, basic ballistic parameters, and compatibility testing of gunpowder and celluloid containers as well as chemical stability determination. The estimation of the gunpowder quality was performed by comparative analysis and the suggestions for more efficient production of it were given.

Graphene oxide (GO) incorporation in natural fiber composites has recently defined a novel class of materials with enhanced properties for applications, including ballistic armors. In the present work, the performance of a 0.5 vol % GO-incorporated epoxy matrix composite reinforced with 30 vol % fabric made of ramie fibers was investigated by stand-alone ballistic tests against the threat of a 0.22 lead projectile. Composite characterization was also performed by Fourier-transform infrared spectroscopy, thermal analysis and X-ray diffraction. Ballistic tests disclosed an absorbed energy of 130 J, which is higher than those reported for other natural fabrics epoxy composite, 74–97 J, as well as plain Kevlar (synthetic aramid fabric), 100 J, with the same thickness. This is attributed to the improved adhesion between the ramie fabric and the composite matrix due to the GO—incorporated epoxy. The onset of thermal degradation above 300 °C indicates a relatively higher working temperature as compared to common natural fiber polymer composites. DSC peaks show a low amount of heat absorbed or release due to glass transition endothermic (113–121 °C) and volatile release exothermic (~132 °C) events. The 1030 cm−1 prominent FTIR band, associated with GO bands between epoxy chains and graphene oxide groups, suggested an effective distribution of GO throughout the composite matrix. As expected, XRD of the 30 vol % ramie fabric-reinforced GO-incorporated epoxy matrix composite confirmed the displacement of the (0 0 1) peak of GO by 8° due to intercalation of epoxy chains into the spacing between GO layers. By improving the adhesion to the ramie fabric and enhancing the thermal stability of the epoxy matrix, as well as by superior absorption energy from projectile penetration, the GO may contribute to the composite effective ballistic performance.

The air defense multiple launch rocket is an effective terminal air defense weapon. The rotation of its turntable has an effect on the rocket’s ballistic. In the paper, the rotation angular velocity of the turntable is combined into the initial swing angular velocity of the transverse and longitudinal axis of the projectile axis. Based on this, taking the rotation of the turntable in the direction as an example, the six-degree-of-freedom rigid body ballistic model is selected for full ballistic simulation, and the stability of the projectile flight at different rotation angular velocities is studied according to the simulation results of the rocket attitude angle.

Regional Missile Defense from a Global Perspective explains the origins, evolution, and implications of the regional approach to missile defense that has emerged since the presidency of George H. W. Bush, and has culminated with the missile defense decisions of President Barack Obama. The Obama administration's overarching concept for American missile defense focuses on developing both a national system of limited ground-based defenses, located in Alaska and California, intended to counter limited intercontinental threats, and regionally-based missile defenses consisting of mobile ground-based technologies like the Patriot PAC-3 system, and sea-based Aegis-equipped destroyer and cruisers. The volume is intended to stimulate renewed debates in strategic studies and public policy circles over the contribution of regional and national missile defense to global security. Written from a range of perspectives by practitioners and academics, the book provides a rich source for understanding the technologies, history, diplomacy, and strategic implications of the gradual evolution of American missile defense plans. Experts and non-experts alike—whether needing to examine the offense-defense tradeoffs anew, to engage with a policy update, or to better understand the debate as it relates to a country or region—will find this book invaluable. While it opens the door to the debates, however, it does not find or offer easy solutions—because they do not exist.

When the penetrating warhead penetrates the target, the internal charge is subjected to extremely high overload and impact loads. If the load intensity and duration meet the detonation conditions, the warhead may experience early detonation, compromising both the penetration effect and safety. To study the influence of charge structure on penetration stability, a specific warhead was used as a model reference, and finite element simulation software was employed to numerically simulate the penetration of concrete targets by the warhead. The results showed that stress concentration occurred at the warhead head during the penetration process, with the maximum stress exceeding the critical detonation stress of the charge, indicating a possibility of early detonation. To improve penetration stability while maintaining the original damage performance, different models of penetration warheads with various charge structures were constructed to analyze the influence of baffle position and number on charge stress. The results show that the loading structure with added partitions can effectively reduce the stress on the charge during penetration. The optimal effect is achieved when the partition is located at 1/2 of the interior of the projectile, with a maximum pressure of 3.75 GPa, which is 44.36% lower than that of the structure without partitions, thereby improving the penetration stability of the projectile.

To investigate the penetration-deflagration coupled characteristics of encased reactive fragments, a numerical simulation model of the encased reactive fragments penetration plate was developed based on Ansys/Lsdyna. Firstly, the mechanical response of the encased reactive fragments penetration plate was obtained using the Johnson-Cook material model, which yielded the internal pressure distribution of the reactive material. Subsequently, the JWL model was used to simulate the penetration-deflagration process, where the JWL parameters of the reactive material were determined based on the condensed reaction material detonation theory. The results indicate that a larger plate thickness value leads to a decrease in the overall internal pressure of the reactive material, thereby reducing the reaction rate of the reactive material. The plate thickness has a marginal impact on the reaction of the encased reactive fragments, but it significantly influenced the deformation and break of the shell, this paper gives the optimal shell and plate thickness under the impact conditions. coefficient and stability.

This paper studies the ballistic behavior of developed 12.7x99mm armor-piercing (AP) projectiles with Tungsten Carbide Core. The development of AP projectiles aims to improve their penetration abilities against high-strength alloy steel targets. Different designs have been modeled in order to determine their penetration capabilities to choose the best design compared with that of traditional 12.7x99mm AP projectile. The study includes, the ballistic performance and stability of the newly developed bullets have been evaluated using PRODAS. Then, Numerical simulations in the environment of ANSYS have been carried out for the developed configurations as well as the traditional AP one to predict their penetration abilities. Finally and according to the PRODAS and simulation results, the designs with best results are chosen to be manufactured and tested by firing against ARMOX-500 steel alloy targets. The results show that the stability has been achieved and the penetration ability for one of the developed projectiles is more than traditional AP projectiles by 150%.

The world is in a second nuclear age in which regional powers play an increasingly prominent role. These states have small nuclear arsenals, often face multiple active conflicts, and sometimes have weak institutions. How do these nuclear states-and potential future ones-manage their nuclear forces and influence international conflict? Examining the reasoning and deterrence consequences of regional power nuclear strategies, this book demonstrates that these strategies matter greatly to international stability and it provides new insights into conflict dynamics across important areas of the world such as the Middle East, East Asia, and South Asia. Vipin Narang identifies the diversity of regional power nuclear strategies and describes in detail the posture each regional power has adopted over time. Developing a theory for the sources of regional power nuclear strategies, he offers the first systematic explanation of why states choose the postures they do and under what conditions they might shift strategies. Narang then analyzes the effects of these choices on a state's ability to deter conflict. Using both quantitative and qualitative analysis, he shows that, contrary to a bedrock article of faith in the canon of nuclear deterrence, the acquisition of nuclear weapons does not produce a uniform deterrent effect against opponents. Rather, some postures deter conflict more successfully than others. Nuclear Strategy in the Modern Eraconsiders the range of nuclear choices made by regional powers and the critical challenges they pose to modern international security.

The nonlinear bang‐bang impact control (NBBIC) had been proposed for robots performing tasks having frequent contact with different environments because it takes advantage of the frictions in robot joints that are not helpful for constrained space control usually, does not need to change gains throughout tasks, and requires little information on robot dynamics. Despite these advantages, due to the lack of stability proof, it was not widely adopted. Recently, the stability of the NBBIC for one degree‐of‐freedom (DOF) robot has been proved almost two decades after its first proposal. The stability condition provided a theoretical stable region of the inertia estimate and was not dependent on environment dynamics, indicating the robustness of NBBIC to environment dynamics (e.g. stiffness). Thus, there is a strong need to verify the stability condition and the robustness of NBBIC to environment dynamics. Experiments of single DOF robots colliding with various environments showed that the stability condition predicted the stable range of the inertia estimate well, though there was a reduction in upper‐bound because of sensor noise. The impact force response did not vary significantly for environments with different stiffness (silicon, aluminium, and steel wall), thereby confirming the robustness of the NBBIC to environment dynamics.