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"Projectiles."
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Research on the responsive characteristics of isolation mechanisms in MEMS safety systems
In response to issues such as the unclear characteristics of isolation mechanisms, explosion-proof ability, high dynamic environmental response characteristics in MEMS safety systems, and insufficient design verification basis, the basic theory of the motion process of the explosion-proof mechanism was analyzed starting from the working principle of the explosion-proof mechanism. The explosion-proof performance and response characteristics of the explosion-proof mechanism under different preset conditions were studied through simulation calculation and experimental verification. The results show that when the thickness of the nickel material partition is less than 0.3 mm, it can block the high-speed impact of titanium flying plates with a design size of Φ 0.75 mm ×0.025 mm and the speed not exceeding 2,800 m/s; when the projectile speed is not less than 20,000 r/min, the isolation mechanism can move in place normally and lock successfully, while also having the ability to resist high overload impact. Under the action of not more than 50,000 g rear seat overload, the structure of the explosion-proof mechanism is intact without any failure.
Journal Article
Developments of 7.62 x39mm armor piercing projectiles
Calibers 7.62 x39mm are one of the most common calibers used all over the world. As a result of developments of modern armors that become lighter, and with-stand more impact kinetic energies. Consequently, the development of ammunition becomes important to increase the combat ability of used weapons to face modern armors. In this paper, some modifications are already done in construction and design of existing bullets, in which the inner cores or parts of them are replaced by harder material, tungsten carbide, instead of lead or hard steel core. Some internal and external ballistic predictions are calculated to make sure the expected developments do not affect the weapons barrels compared with the original bullets and the check of the stability during the flight are also studied by using PRODAS package Resultant depths of penetrations are compared experimentally with that of original types, the experimental results show a noticeable increase in depth of penetration compared with that of original bullets.
Journal Article
Analysis of the influence of structural parameters of irregular charges on the forming performance of EFP with tail Fins
In this study, a special charge structure is designed to form an explosively formed projectile (EFP) with fins for stable flight. By using LS-DYNA for numerical simulation, the influence of charge structure parameters on the EFP characteristics of the tail fins was analyzed. The results show that the irregular charge structure can reliably form an EFP with fins, and the number of EFP tail fins can be controlled by changing the number of sides n of the regular polygon at the top section of the charge. Changing the shape parameters n and Dn of the top section of the charge will greatly affect the shape of the tail fins, while the charge height H has a significant impact on the length to diameter ratio of EFP, the appropriate range of H values should be between 0.5 Dc and 0.8 Dc . The research results can provide reference for the design ideas of tail wing EFP.
Journal Article
Fusion of Stable Odd-A isotope targets with Doubly Magic 16O Projectile
Fusion excitation functions of stable odd-A targets 147,149Sm with 16O projectile are theoretically analyzed within view of the symmetric-asymmetric Gaussian barrier distribution (SAGBD) formalism. For the purposes of this study, we assumed that bombardment energies of the 16O + 147,149Sm reactions would be around nominal barrier. For these reactions, Wong based computations fails to retrace the fusion data whereas SAGBD predictions fairly retrace the fusion data in entire bombarding energy range. The evaluated values of channel coupling parameter (λ) and VCBRED from SAGBD outcomes are found larger for heavier (16O + 149Sm) over lighter (16O + 149Sm) system, which suggests that heavier system possess extra fusion enhancement in sub-barrier domain. Present theoretical investigation highlights the significant contributions of intrinsic channels that emerges due to structure of reacting nuclei and such effects are empirically included in SAGBD method.
Journal Article
Confident Learning: Estimating Uncertainty in Dataset Labels
Learning exists in the context of data, yet notions of confidence typically focus on model predictions, not label quality. Confident learning (CL) is an alternative approach which focuses instead on label quality by characterizing and identifying label errors in datasets, based on the principles of pruning noisy data, counting with probabilistic thresholds to estimate noise, and ranking examples to train with confidence. Whereas numerous studies have developed these principles independently, here, we combine them, building on the assumption of a class-conditional noise process to directly estimate the joint distribution between noisy (given) labels and uncorrupted (unknown) labels. This results in a generalized CL which is provably consistent and experimentally performant. We present sufficient conditions where CL exactly finds label errors, and show CL performance exceeding seven recent competitive approaches for learning with noisy labels on the CIFAR dataset. Uniquely, the CL framework is not coupled to a specific data modality or model (e.g., we use CL to find several label errors in the presumed error-free MNIST dataset and improve sentiment classification on text data in Amazon Reviews). We also employ CL on ImageNet to quantify ontological class overlap (e.g., estimating 645 missile images are mislabeled as their parent class projectile), and moderately increase model accuracy (e.g., for ResNet) by cleaning data prior to training. These results are replicable using the open-source cleanlab release.
Journal Article
Research on Artillery Firing Trajectory under the Condition of Extra-large Elevation Difference between Artillery and Target in Plateau Area
Get the influence of shooting on the ballistic elements and correction elements of grenade under the condition of extra-large elevation difference between artillery and target in plateau area through simulation, and drawn the comparison chart of different altitude and elevation difference between artillery and target by using the simulation data. Calculate the variation characteristics of the hit range of laser terminal guided projectile under the condition of the elevation difference of extra-large elevation difference between artillery and target at different altitudes, and the influence of altitude and extra-large elevation difference between artillery and target on the hit range of laser terminal guided projectile is analyzed and summarized. It has a certain reference value for improving the shooting accuracy under the condition of high altitude and extra-large elevation difference between artillery and target.
Journal Article