Defence Technology(防务技术)最新文献_第2页

A tensile wearable SHF antenna with efficient communication in defense beacon technology 在国防信标技术中实现高效通信的拉伸可穿戴式 SHF 天线

IF 5

Defence Technology(防务技术) Pub Date : 2024-11-01 DOI: 10.1016/j.dt.2024.05.005

Pooja Naresh Bhatt , Rashmi Pandhare

{"title":"A tensile wearable SHF antenna with efficient communication in defense beacon technology","authors":"Pooja Naresh Bhatt , Rashmi Pandhare","doi":"10.1016/j.dt.2024.05.005","DOIUrl":"10.1016/j.dt.2024.05.005","url":null,"abstract":"<div><div>The study projects a flexible and compact wearable pear-shaped Super High Frequency (SHF) antenna that can provide detailed location recognition and tracking applicable to defense beacon technology. This mini aperture with electrical dimensions of 0.12<em>λ</em><sub>0</sub> × 0.22<em>λ</em><sub>0</sub> × 0.01<em>λ</em><sub>0</sub> attains a vast bandwidth over 3.1–34.5 GHz Super High Frequency (SHF) frequency band at S<sub>11</sub> ≤ −10 dB, peak gain of 7.14 dBi and proportionately homogeneous radiation pattern. The fractional bandwidth (% BW) acquired is 168% that envelopes diversified frequency spectrum inclusive of X band specifically targeted to all kinds of defense and military operations. The proposed antenna can be worn on a soldier's uniform and hence the Specific Absorption Rate simulation is accomplished. The Peak SAR Value over 1 g of tissue is 1.48 W/kg and for 10 g of tissue is 0.27 W/kg well under the safety standards. The flexibility is proven by analyzing the full electromagnetic simulations for various bending conditions. Time response analysis is attained with its Fidelity Factor and Group Delay. Communication excellence is determined using Link Budget Analysis and it is seen that margin at 100 Mbps is 62 m and at 200 Mbps is 59 m. Prototype is fabricated along with experimental validation. All the results show harmony in shaping the antenna to provide critical situational awareness and data sharing capabilities required in defense beacon technology for location identification.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 198-210"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141032947","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}

引用次数: 0

Effect of silica fume and glass powder for enhanced impact resistance in GGBFS-based ultra high-performance geopolymer fibrous concrete: An experimental and statistical analysis 硅灰和玻璃粉对增强基于 GGBFS 的超高性能土工聚合物纤维混凝土抗冲击性的影响：实验和统计分析

IF 5

Defence Technology(防务技术) Pub Date : 2024-11-01 DOI: 10.1016/j.dt.2024.05.015

G. Murali , Anoop Kallamalayil Nassar , Madhumitha Swaminathan , Parthiban Kathirvel , Leong Sing Wong

{"title":"Effect of silica fume and glass powder for enhanced impact resistance in GGBFS-based ultra high-performance geopolymer fibrous concrete: An experimental and statistical analysis","authors":"G. Murali , Anoop Kallamalayil Nassar , Madhumitha Swaminathan , Parthiban Kathirvel , Leong Sing Wong","doi":"10.1016/j.dt.2024.05.015","DOIUrl":"10.1016/j.dt.2024.05.015","url":null,"abstract":"<div><div>Solid waste recycling is an economically sound strategy for preserving the environment, safeguarding natural resources, and diminishing the reliance on raw material consumption. Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials. This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete (UHPGC). In total, 18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder, ranging from 10% to 40%. Similarly, for each of the mixtures above, steel fibre was added at a dosage of 1.5% to address the inherent brittleness of UHPGC. The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders. The specimens were subjected to drop-weight impact testing, wherein an examination was carried out to evaluate various parameters, including flowability, density at fresh and hardened state, compressive strength, impact numbers indicative of cracking and failure occurrences, ductility index, and analysis of failure modes. Additionally, the variations in the impact test outcomes were analyzed using the Weibull distribution, and the findings corresponding to survival probability were offered. Furthermore, the microstructure of UHPGC was scrutinized through scanning electron microscopy. Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume, with reductions ranging from 18.63% to 34.31%. Similarly, failure impact number values decreased from 8.26% to 28.46% across glass powder contents. The maximum compressive and impact strength was recorded in UHPGC, comprising 10% silica fume with fibres.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 59-81"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508136","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}

引用次数: 0

Properties of high cis-1,4 content hydroxyl-terminated polybutadiene and its application in composite solid propellants 高顺式-1,4 含量羟基封端聚丁二烯的性能及其在复合固体推进剂中的应用

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.04.014

{"title":"Properties of high cis-1,4 content hydroxyl-terminated polybutadiene and its application in composite solid propellants","authors":"","doi":"10.1016/j.dt.2024.04.014","DOIUrl":"10.1016/j.dt.2024.04.014","url":null,"abstract":"<div><div>In this paper, high <em>cis</em>-1,4 content hydroxyl-terminated polybutadiene (<em>cis</em>-HTPB) with different molecular weights was prepared through the oxidative cracking process using <em>cis</em>-butadiene rubber as raw material. Firstly, this article comprehensively compared the differences between <em>cis</em>-HTPB and conventional I-HTPB in terms of molecular weight distribution, functionality, viscosity, molecular polarity, and other physicochemical properties, which provided effective data support for its subsequent application. In addition, the reaction kinetics study showed that <em>cis</em>-HTPB with isocyanate curing agent has high reactivity, allowing it to be rapidly cured at low temperatures, and the cured elastomers had excellent mechanical properties, with tensile strength and elongation up to 1.89 MPa and 1100%, respectively. It was also found that <em>cis</em>-HTPB has extremely excellent low-temperature resistance, and the glass transition temperature (<em>T</em><sub>g</sub>) of its cured elastomer is as low as −101 °C. Based on the above studies, <em>cis</em>-HTPB is applied as a binder in composite solid propellants for the first time to investigate its practical performance, and the results indicated that <em>cis</em>-HTPB-based propellants have excellent process and mechanical properties.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 199-209"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140765286","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}

引用次数: 0

A novel framework to intercept GPS-denied, bomb-carrying, non-military, kamikaze drones: Towards protecting critical infrastructures 拦截不使用 GPS、携带炸弹的非军事神风特攻队无人机的新型框架：保护关键基础设施

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.05.001

{"title":"A novel framework to intercept GPS-denied, bomb-carrying, non-military, kamikaze drones: Towards protecting critical infrastructures","authors":"","doi":"10.1016/j.dt.2024.05.001","DOIUrl":"10.1016/j.dt.2024.05.001","url":null,"abstract":"<div><div>Protection of urban critical infrastructures (CIs) from GPS-denied, bomb-carrying kamikaze drones (G-B-KDs) is very challenging. Previous approaches based on drone jamming, spoofing, communication interruption and hijacking cannot be applied in the case under examination, since G-B-KDs are uncontrolled. On the other hand, drone capturing schemes and electromagnetic pulse (EMP) weapons seem to be effective. However, again, existing approaches present various limitations, while most of them do not examine the case of G-B-KDs. This paper, focuses on the aforementioned under-researched field, where the G-B-KD is confronted by two defensive drones. The first neutralizes and captures the kamikaze drone, while the second captures the bomb. Both defensive drones are equipped with a net-gun and an innovative algorithm, which, among others, estimates the locations of interception, using a real-world trajectory model. Additionally, one of the defensive drones is also equipped with an EMP weapon to damage the electronics equipment of the kamikaze drone and reduce the capturing time and the overall risk. Extensive simulated experiments and comparisons to state-of-art methods, reveal the advantages and limitations of the proposed approach. More specifically, compared to state-of-art, the proposed approach improves: (a) time to neutralize the target by at least 6.89%, (b) maximum number of missions by at least 1.27% and (c) total cost by at least 5.15%.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 225-241"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141038220","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}

引用次数: 0

Research status and challenges in the manufacturing of IR conformal optics 红外保偏光学器件制造的研究现状与挑战

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.04.015

引用次数: 0

Comparative impact behaviours of ultra high performance concrete columns reinforced with polypropylene vs steel fibres 用聚丙烯纤维和钢纤维加固的超高性能混凝土柱的冲击行为比较

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.04.016

{"title":"Comparative impact behaviours of ultra high performance concrete columns reinforced with polypropylene vs steel fibres","authors":"","doi":"10.1016/j.dt.2024.04.016","DOIUrl":"10.1016/j.dt.2024.04.016","url":null,"abstract":"<div><div>Polypropylene (PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacity improvement. This study unveils the possibility of using PP micro-fibres to improve the impact behaviour of fibre-reinforced ultra-high-performance concrete (FRUHPC) columns. Results show that the addition of fibres significantly improves the impact behaviour of FRUHPC columns by shifting the failure mechanism from brittle shear to favourable flexural failure. The addition of steel or PP fibres affected the impact responses differently. Steel fibres considerably increased the peak impact force (up to 18%) while PP micro-fibres slightly increased the peak (3%–4%). FRUHPC significantly reduced the maximum mid-height displacement by up to 30% (under 20° impact) and substantially improved the displacement recovery by up to 100% (under 20° impact). FRUHPC with steel fibres significantly improved the energy absorption while those with PP micro-fibres reduced the energy absorption, which is different from the effect of PP-macro fibre reported in the literature. The optimal fibre content for micro-PP fibres is 1% due to its minimal fibre usage and low peak and residual displacement. This study highlights the potential of FRUHPC as a promising material for impact-resistant structures by creating a more favourable flexural failure mechanism, enhancing ductility and toughness under impact loading, and advancing the understanding of the role of fibres in structural performance.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 138-153"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141023485","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}

引用次数: 0

Spontaneous ignition of corrugated cardboard under dynamic high radiant flux 动态高辐射通量下瓦楞纸板的自燃

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.05.010

{"title":"Spontaneous ignition of corrugated cardboard under dynamic high radiant flux","authors":"","doi":"10.1016/j.dt.2024.05.010","DOIUrl":"10.1016/j.dt.2024.05.010","url":null,"abstract":"<div><div>Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme scenarios. Unlike the more moderate radiant fluxes in conventional hydrocarbon fires, extreme events such as strong explosion, concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m<sup>2</sup> level, creating a unique threat to materials. This study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods, under 10-cm dynamic high radiant fluxes ranging from 0.2 to 1.25 MW/m<sup>2</sup> for 10 s. The spontaneous ignition process at dynamic high radiant fluxes was recorded and quantified. Two ignition modes were found at the critical radiant flux of 0.4 MW/m<sup>2</sup>, namely hot-gas spontaneous ignition and hot-residue piloted ignition. The latter is not the focus of this paper due to its extremely small probability of occurrence. The research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition, lower ignition energy density, along with a corresponding rise in the critical mass flux and surface temperature at ignition moment. The simulation results are generally aligned with the experimental findings, despite some divergences may be attributed to model simplifications and parameter assumptions. The work contributes to a deeper insight into material behavior under extreme radiation, with valuable implications for fire safety and hazard assessment.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 65-77"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141050054","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}

引用次数: 0

Blast injury risks to humans within a military trench 军事战壕内的爆炸对人体造成伤害的风险

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.03.006

{"title":"Blast injury risks to humans within a military trench","authors":"","doi":"10.1016/j.dt.2024.03.006","DOIUrl":"10.1016/j.dt.2024.03.006","url":null,"abstract":"<div><div>In land warfare, trenches serve as vital defensive fortifications, offering protection to soldiers while engaging in combat. However, despite their protective function, soldiers often sustain injuries within these trenches. The lack of corresponding blast data alongside empirical injury reports presents a significant knowledge gap, particularly concerning the blast pressures propagating within trench spaces following nearby explosions. This absence hinders the correlation between blast parameters, trench geometry, and reported injury cases, limiting our understanding of blast-related risks within trenches.</div><div>This paper addresses the critical aspect of blast propagation within trench systems, essential for evaluating potential blast injury risks to individuals within these structures. Through advanced computational fluid dynamics (CFD) simulations, the study comprehensively investigates blast injury risks resulting from explosions near military trenches. Employing a sophisticated computational model, the research analyzes the dynamic blast effects within trenches, considering both geometrical parameters and blast characteristics influenced by explosive weight and scaled distance.</div><div>The numerical simulations yield valuable insights into the impact of these parameters on blast injury risks, particularly focusing on eardrum rupture, lung injury, and traumatic brain injury levels within the trench. The findings elucidate distinct patterns of high-risk zones, highlighting unique characteristics of internal explosions due to confinement and venting dynamics along the trench. This study underscores the significance of detailed numerical modeling in assessing blast injury risks and provides a novel knowledge base for understanding risks associated with explosives detonating near military trenches. The insights gained contribute to enhancing safety measures in both military and civilian contexts exposed to blast events near trench structures.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 91-104"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140399346","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}

引用次数: 0

Exploring the hygroscopic behavior of highly energetic oxidizer ammonium dinitramide (ADN) at different temperatures and humidities using an innovative hygroscopic modeling 利用创新吸湿模型探索高能氧化剂二硝胺铵（ADN）在不同温度和湿度下的吸湿行为

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.06.003

{"title":"Exploring the hygroscopic behavior of highly energetic oxidizer ammonium dinitramide (ADN) at different temperatures and humidities using an innovative hygroscopic modeling","authors":"","doi":"10.1016/j.dt.2024.06.003","DOIUrl":"10.1016/j.dt.2024.06.003","url":null,"abstract":"<div><div>Ammonium dinitramide (ADN) is a new type of green energetic oxidizer with excellent energy density and low pollution combustion characteristics. However, the strong hygroscopicity has a significant impact on its practical application. To assist in the research on moisture-proof modification of ADN materials, an innovative hygroscopic modeling approach was proposed to evaluate the hygroscopicity of ADN at various temperatures and humidities. By investigating the diffusion coefficient of water molecules in molecular dynamics processes, a visual insight into the hygroscopic process of ADN was gained. Furthermore, analyzing the non-covalent interactions between ADN and water molecules, the hygroscopicity of ADN could be evaluated qualitatively and quantitatively. The energy analysis revealed that electrostatic forces play a dominant role in the process of water adsorption by ADN, whereas van der Waals forces impede it. As a whole, the simulation results show that ADN presents the following hygroscopic law: At temperatures ranging from 273 K to 373 K and relative humidity (RH) from 10% to 100%, the hygroscopicity of ADN generally shows an increasing trend with the rise in temperature and humidity based on the results of three simulations. According to the non-hygroscopic point (298 K, 52% RH) of ADN obtained by experiment in the literature, a non-hygroscopic range of temperature and humidity for ADN can be depicted when the simulation results in relative hygroscopicity is less than or equal to 17%. This study can provide effective strategies for screening anti-hygroscopic modified materials of ADN.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 25-34"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416031","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}

引用次数: 0

Data-driven prediction of dimensionless quantities for semi-infinite target penetration by integrating machine-learning and feature selection methods 通过整合机器学习和特征选择方法，以数据驱动预测半无限目标穿透的无量纲数量

IF 5

Defence Technology(防务技术) Pub Date : 2024-10-01 DOI: 10.1016/j.dt.2024.04.012

{"title":"Data-driven prediction of dimensionless quantities for semi-infinite target penetration by integrating machine-learning and feature selection methods","authors":"","doi":"10.1016/j.dt.2024.04.012","DOIUrl":"10.1016/j.dt.2024.04.012","url":null,"abstract":"<div><div>This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements. The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables. As a physics-based dimension reduction methodology, this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases. Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering. The results indicate that the selected critical dimensionless feature variables by this synergistic method, without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics, are in accordance with those reported in the reference. Lastly, the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case, and the reliability of regression functions is validated.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 105-124"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141528353","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}

引用次数: 0