Defence Technology(防务技术)最新文献

{"title":"A data and physical model dual-driven based trajectory estimator for long-term navigation","authors":"","doi":"10.1016/j.dt.2024.05.006","DOIUrl":"10.1016/j.dt.2024.05.006","url":null,"abstract":"<div><div>Long-term navigation ability based on consumer-level wearable inertial sensors plays an essential role towards various emerging fields, for instance, smart healthcare, emergency rescue, soldier positioning et al. The performance of existing long-term navigation algorithm is limited by the cumulative error of inertial sensors, disturbed local magnetic field, and complex motion modes of the pedestrian. This paper develops a robust data and physical model dual-driven based trajectory estimation (DPDD-TE) framework, which can be applied for long-term navigation tasks. A Bi-directional Long Short-Term Memory (Bi-LSTM) based quasi-static magnetic field (QSMF) detection algorithm is developed for extracting useful magnetic observation for heading calibration, and another Bi-LSTM is adopted for walking speed estimation by considering hybrid human motion information under a specific time period. In addition, a data and physical model dual-driven based multi-source fusion model is proposed to integrate basic INS mechanization and multi-level constraint and observations for maintaining accuracy under long-term navigation tasks, and enhanced by the magnetic and trajectory features assisted loop detection algorithm. Real-world experiments indicate that the proposed DPDD-TE outperforms than existing algorithms, and final estimated heading and positioning accuracy indexes reaches 5° and less than 2 m under the time period of 30 min, respectively.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 78-90"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141028479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A cloud model target damage effectiveness assessment algorithm based on spatio-temporal sequence finite multilayer fragments dispersion","authors":"","doi":"10.1016/j.dt.2024.05.008","DOIUrl":"10.1016/j.dt.2024.05.008","url":null,"abstract":"<div><div>To solve the problem of target damage assessment when fragments attack target under uncertain projectile and target intersection in an air defense intercept, this paper proposes a method for calculating target damage probability leveraging spatio-temporal finite multilayer fragments distribution and the target damage assessment algorithm based on cloud model theory. Drawing on the spatial dispersion characteristics of fragments of projectile proximity explosion, we divide into a finite number of fragments distribution planes based on the time series in space, set up a fragment layer dispersion model grounded in the time series and intersection criterion for determining the effective penetration of each layer of fragments into the target. Building on the precondition that the multilayer fragments of the time series effectively assail the target, we also establish the damage criterion of the perforation and penetration damage and deduce the damage probability calculation model. Taking the damage probability of the fragment layer in the spatio-temporal sequence to the target as the input state variable, we introduce cloud model theory to research the target damage assessment method. Combining the equivalent simulation experiment, the scientific and rational nature of the proposed method were validated through quantitative calculations and comparative analysis.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 48-64"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141051229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influences of oscillation on the physical stability and explosion characteristics of solid‒liquid mixed fuel","authors":"Chi Zhang ,&nbsp;Ge Song ,&nbsp;Hui Guo ,&nbsp;Jiafan Ren ,&nbsp;Chunhua Bai","doi":"10.1016/j.dt.2024.05.014","DOIUrl":"10.1016/j.dt.2024.05.014","url":null,"abstract":"<div><div>The stratification phenomenon resulting from differences in the physical properties of solid‒liquid components seriously affect the final combustion and explosion characteristics of mixed fuel under the action of oscillation. The effects of oscillation on the physical stability of mixed fuel with two solid‒liquid ratios and three liquid component distribution ratios have been investigated using a self-designed experimental system at oscillation frequencies of 60–300 r/min. The explosion characteristics of mixed fuel before and after oscillation are gained from a 20 L spherical explosion container system. When the mass ratio of liquid components is controlled at 66.9%, 64.7%, 62.6% the final explosion characteristics are stable, with a maximum difference of only 0.71%. The volume of liquid fuel precipitation increases with increasing oscillation frequency when the mass ratio of liquid components reaches 71.7%, 69.6%, 67.7%. The fuel explosion overpressure after oscillation decreases with increasing liquid precipitation volume, and the repeatability is poor, with a maximum standard deviation of 82.736, which is much higher than the ratio without stratification. Properly controlling the mass ratio of liquid components of the mixed fuel can effectively combat the impact of oscillation on the physical state and maintain the stability of the final explosion characteristics.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 191-198"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141784823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetics and mechanism of the low-energy β-α phase transition of the second kind in 2,4-dinitroanisole","authors":"","doi":"10.1016/j.dt.2024.04.004","DOIUrl":"10.1016/j.dt.2024.04.004","url":null,"abstract":"<div><div>In this work, comprehensive studies of 2,4-dinitroanisole (2,4DNAN) were carried out using powder thermorentgenography of the internal standard. The time of the complete polymorphic transition in the solid phase β→α in 2,4DNAN under various combinations of conditions has been determined. It has been established that, regardless of the season of manufacture of the substance, when it is stored for 8–9 months, with a change in ambient temperature from minus 30 °C to plus 30 °C, a complete polymorphic transition β→α occurs. When stored in conditions below minus 5 °C, polymorphic transition does not occur. When stored in conditions above plus 30 °C in a closed container, polymorphic transition occurs within 3 weeks. The polymorphic transition is accompanied by a decrease in density by 1.3%–1.5% and an increase in melting temperature by 10–12 °C, depending on the degree of purity of the starting substance. The activation energy of the molecular rearrangement was 68–70 kJ/mol (16.5 ± 3 kcal/mol). The mechanism of polymorphic transition has been evaluated, which is presumably based on internal homodiffusion and energy transfer to the surface of the mass of powder particles and the product. The average activation energy of the polymorphic transition process was 110 ± 6.2 kJ/mol (26.2 kcal/mol). In an open container, reactions proceed by a homogeneous mechanism, and in a closed container by a heterogeneous mechanism involving the gas phase.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 210-224"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141197906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of B4C and ZrB2 reinforcements on microstructural, mechanical and wear behaviour of AA 2014 aluminium matrix hybrid composites","authors":"","doi":"10.1016/j.dt.2024.05.009","DOIUrl":"10.1016/j.dt.2024.05.009","url":null,"abstract":"<div><div>Considering their affordability and high strength-to-weight ratio, lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry. This research effort aims to develop novel hybrid composites based on AA 2014 alloy through the use of liquid metallurgy stir casting to reinforce dual ceramic particles of Zirconium Diboride (ZrB₂) and Boron Carbide (B₄C). The weight percentage (wt%) of ZrB₂ was varied (0, 5, 10, and 15), while a constant 5 wt% of B₄C was maintained during this fabrication. The as-cast samples have been assessed using an Optical Microscope (OM) and a Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS). The properties such as hardness, tensile strength, and wear characteristics of stir cast specimens were assessed to examine the impact of varying weight percentages of reinforcements in AA 2014 alloy. In particular, dry sliding wear behaviour was evaluated considering varied loads using a pin-on-disc tribotester. As the weight % of ZrB₂ grew and B₄C was incorporated, hybrid composites showed higher hardness, tensile strength, and wear resistance. Notably, the incorporation of a cumulative reinforcement consisting of 15 wt% ZrB₂ and 5 wt% B₄C resulted in a significant 31.86% increase in hardness and a 44.1% increase in tensile strength compared to AA 2014 alloy. In addition, it has been detected that wear resistance of hybrid composite pin (containing 20 wt% cumulative reinforcement) is higher than that of other stir cast wear test pins during the whole range of applied loads. Fractured surfaces of tensile specimens showed ductile fracture in the AA 2014 matrix and mixed mode for hybrid composites. Worn surfaces obtained employing higher applied load indicated abrasive wear with little plastic deformation for hybrid composites and dominant adhesive wear for matrix alloy. Hence, the superior mechanical and tribological performance of hybrid composites can be attributed to dual reinforcement particles being dispersed well and the effective transmission of load at this specific composition.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 242-254"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive optimisation of explosive reactive armour for protection against kinetic energy and shaped charge threats","authors":"","doi":"10.1016/j.dt.2024.05.007","DOIUrl":"10.1016/j.dt.2024.05.007","url":null,"abstract":"<div><div>We evaluate an adaptive optimisation methodology, Bayesian optimisation (BO), for designing a minimum weight explosive reactive armour (ERA) for protection against a surrogate medium calibre kinetic energy (KE) long rod projectile and surrogate shaped charge (SC) warhead. We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert. A third approach, utilising a novel human-machine teaming framework for BO is also evaluated. Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments. The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations, outperforming both the stand-alone human and stand-alone BO methodologies. From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 1-12"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141143012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological optimization of ballistic protective structures through genetic algorithms in a vulnerability-driven environment","authors":"","doi":"10.1016/j.dt.2024.05.011","DOIUrl":"10.1016/j.dt.2024.05.011","url":null,"abstract":"<div><div>Reducing the vulnerability of a platform, i.e., the risk of being affected by hostile objects, is of paramount importance in the design process of vehicles, especially aircraft. A simple and effective way to decrease vulnerability is to introduce protective structures to intercept and possibly stop threats. However, this type of solution can lead to a significant increase in weight, affecting the performance of the aircraft. For this reason, it is crucial to study possible solutions that allow reducing the vulnerability of the aircraft while containing the increase in structural weight. One possible strategy is to optimize the topology of protective solutions to find the optimal balance between vulnerability and the weight of the added structures. Among the many optimization techniques available in the literature for this purpose, multi-objective genetic algorithms stand out as promising tools. In this context, this work proposes the use of a in-house software for vulnerability calculation to guide the process of topology optimization through multi-objective genetic algorithms, aiming to simultaneously minimize the weight of protective structures and vulnerability. In addition to the use of the in-house software, which itself represents a novelty in the field of topology optimization of structures, the method incorporates a custom mutation function within the genetic algorithm, specifically developed using a graph-based approach to ensure the continuity of the generated structures. The tool developed for this work is capable of generating protections with optimized layouts considering two different types of impacting objects, namely bullets and fragments from detonating objects. The software outputs a set of non-dominated solutions describing different topologies that the user can choose from.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 125-137"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141528398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and evaluation of a kind of polymer-bonded explosives with improved mechanical sensitivity and thermal properties","authors":"","doi":"10.1016/j.dt.2024.04.005","DOIUrl":"10.1016/j.dt.2024.04.005","url":null,"abstract":"<div><div>The emergence of TKX-50, an energetic ionic salt with a high enthalpy of formation and low sensitivity, has opened a new path for the development of high-energetic, insensitive composite explosives. However, due to the poor interfacial binding properties of TKX-50 with conventional binders, there is a lack of effective guidance for the design of TKX-50 based composite explosives. To address the above issues, the interactions between carboxymethyl cellulose acetate butyrate (CMCAB) and other binders with explosives TKX-50/HMX were compared using the molecular dynamics method. Based on the simulations, TKX-50/HMX/CMCAB-based polymer-bonded explosives (PBXs) were prepared with CMCAB as binder, which displays a high binding energy (<em>E</em>_bind) with TKX-50 and high cohesive energy density (CED), and the effect of TKX-50 content on the performance of PBXs was investigated. The physical properties of PBXs, specifically the morphology, mechanical sensitivity, and thermal conductivity, were analyzed by SEM, sensitivity apparatus, and thermal conductivity meter, respectively. The specific heat capacity (<em>C</em>_<em>p</em>) and non-isothermal decomposition temperature of PBXs were tested by DSC, and then the corresponding thermal kinetic parameters were analyzed to evaluate their thermal safety. The adiabatic thermal decomposition processes of PBXs were tested using an ARC instrument. The decomposition mechanism and kinetics were also explored to further analyze their thermal stability and thermal safety under adiabatic conditions. The computer code EXPLO5 was used to predict the detonation parameters of PBXs. The results showed that CMCAB and TKX-50 displayed favorable interfacial bonding properties, and TKX-50 can be bonded with HMX to form a molding powder with a desirable morphology and safety profile. The TKX-50 in PBXs effectively improves the mechanical sensitivity and thermal safety of PBX and has a significant effect on the detonation performance of PBX. This research demonstrates a novel method suitable for screening and investigating high-energetic insensitive explosive systems compatible with TKX-50.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 13-24"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140772991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resistance of full-scale beams against close-in explosions. Numerical modeling and field tests","authors":"","doi":"10.1016/j.dt.2024.05.002","DOIUrl":"10.1016/j.dt.2024.05.002","url":null,"abstract":"<div><div>This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading. Field test data has been used to compare model results for each case. The numerical modelling has been, carried out using the suitable code LS-DYNA. This code integrates blast load routine (CONWEP) for the explosive description and four different material models for the concrete including: Karagozian &amp; Case Concrete, Winfrith, Continuous Surface Cap Model and Riedel–Hiermaier–Thoma models, with concrete meshing based on 10, 15, and 20 mm. Six full-scale beams were tested: four of them used for the initial calibration of the numerical model and two more tests at lower scaled distances. For calibration, field data obtained employing pressure and accelerometers transducers were compared with the results derived from the numerical simulation. Damage surfaces and the shape of rupture in the beams have been used as references for comparison. Influence of the meshing on accelerations has been put in evidence and for some models the shape and size of the damage in the beams produced maximum differences around 15%. In all cases, the variations between material and mesh models are shown and discussed.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 35-47"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141027329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Failure pattern in ceramic metallic target under ballistic impact","authors":"","doi":"10.1016/j.dt.2024.05.012","DOIUrl":"10.1016/j.dt.2024.05.012","url":null,"abstract":"<div><div>The ballistic resistance and failure pattern of a bi-layer alumina 99.5% - aluminium alloy 1100-H12 target against steel 4340 ogival nosed projectile has been explored in the present experimental cum numerical study. In the experimental investigation, damage induced in the ceramic layer has been quantified in terms of number of cracks developed and failure zone dimensions. The resultant damage in the backing layer has been studied with variation in the bulge and perforation hole in the backing layer with the varying incidence velocity. The discussion of the experimental results has been further followed by three dimensional finite element computations using ABAQUS/Explicit finite code to investigate the behaviour of different types of bi-layer targets under multi-hit projectile impact. The JH-2 constitutive model has been used to reproduce the behaviour of alumina 99.5% and JC constitutive model has been used for steel 4340 and aluminium alloy 1100-H12. The total energy dissipation has been noted to be of lesser magnitude in case of sub-sequential impact in comparison to simultaneous impact of two projectiles. The distance between the impact points of two projectiles also effected the ballistic resistance of bi-layer target. The ballistic resistance of single tile ceramic front layer and four tile ceramic of equivalent area found to be dependent upon the boundary conditions provided to the target.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 173-190"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141528399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}