Pub Date : 2024-07-30DOI: 10.1016/j.dt.2024.07.014
Jiqing Luo, Husheng Fang, Yue Zhong, Jing Zhang, Shengli Song
In this paper, the fixed-time time-varying formation of heterogeneous multi-agent systems (MASs) based on tracking error observer under denial-of-service (DoS) attacks is investigated. Firstly, the dynamic pinning strategy is used to reconstruct the communication channel for the system that suffers from DoS attacks to prevent the discontinuous transmission information of the communication network from affecting MASs formation. Then, considering that the leader state is not available to each follower under DoS attacks, a fixed-time distributed observer without velocity information is constructed to estimate the tracking error between followers and the leader. Finally, adaptive radial basis function neural network (RBFNN) is used to approximate the unknown ensemble disturbances in the system, and the fixed-time time-varying formation scheme is designed with the constructed observer. The effectiveness of the proposed control algorithm is demonstrated by the numerical simulation.
本文研究了在拒绝服务（DoS）攻击下，基于跟踪误差观测器的异构多代理系统（MAS）的定时时变形成。首先，采用动态销钉策略为遭受 DoS 攻击的系统重建通信信道，防止通信网络传输信息不连续影响 MAS 的形成。然后，考虑到在 DoS 攻击下每个跟随者无法获得领导者的状态，构建了一个没有速度信息的固定时间分布式观测器来估计跟随者与领导者之间的跟踪误差。最后，使用自适应径向基函数神经网络（RBFNN）来近似系统中的未知集合干扰，并利用构建的观测器设计定时时变编队方案。数值仿真证明了所提控制算法的有效性。
{"title":"Research on fixed-time time-varying formation of heterogeneous multi-agent systems based on tracking error observer under DoS attacks","authors":"Jiqing Luo, Husheng Fang, Yue Zhong, Jing Zhang, Shengli Song","doi":"10.1016/j.dt.2024.07.014","DOIUrl":"https://doi.org/10.1016/j.dt.2024.07.014","url":null,"abstract":"In this paper, the fixed-time time-varying formation of heterogeneous multi-agent systems (MASs) based on tracking error observer under denial-of-service (DoS) attacks is investigated. Firstly, the dynamic pinning strategy is used to reconstruct the communication channel for the system that suffers from DoS attacks to prevent the discontinuous transmission information of the communication network from affecting MASs formation. Then, considering that the leader state is not available to each follower under DoS attacks, a fixed-time distributed observer without velocity information is constructed to estimate the tracking error between followers and the leader. Finally, adaptive radial basis function neural network (RBFNN) is used to approximate the unknown ensemble disturbances in the system, and the fixed-time time-varying formation scheme is designed with the constructed observer. The effectiveness of the proposed control algorithm is demonstrated by the numerical simulation.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"36 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Explosion-electricity coupling (EEC) is a technical method to induce electric energy into the plasma material produced by explosion to improve the output of explosion. Exploding foil initiator (EFI) which could produce plasma during electric explosion can serve as a good carrier for studying the EEC. To investigate the enhancement ability and mechanism of EEC in EFI ignition performance, a kind of EFI chips which could realize the EEC effect was designed and fabricated to observe the characteristics of current and voltage, flyer and plasma temperature during Boron Potassium Nitrate (BPN) ignition of the EFI. It was found that the EEC could enhance EFI ignition in terms of energy utilization, ignition contact surface, and high-temperature sustainability of plasma: firstly, the EEC prolonged the late time discharge (LTD) phase of the electric explosion, making the energy of capacitor effectively utilized; secondly, the EEC could create a larger area of ignition contact surface; last of all, the EEC effect enhanced its high-temperature sustainability by sustaining continuous energy input to plasma. It also was found that the ignition voltage of BPN could be reduced by nearly 600 V under the condition of 0.4 μF capacitance. The research has successfully combined EEC with EFI, revealing the behavioral characteristics of EEC and demonstrating its effective enhancement of EFI ignition. It introduces a new approach to improving EFI output, which is conducive to low-energy ignition of EFI, and expected to take the ignition technology of EFI to a new level.
{"title":"Investigation on the exploding foil initiators ignition enhanced by explosion-electricity coupling","authors":"Songmao Zhao, Haotian Jian, Ke Wang, Zheng Ning, Peng Zhu, Ruiqi Shen","doi":"10.1016/j.dt.2024.06.013","DOIUrl":"https://doi.org/10.1016/j.dt.2024.06.013","url":null,"abstract":"Explosion-electricity coupling (EEC) is a technical method to induce electric energy into the plasma material produced by explosion to improve the output of explosion. Exploding foil initiator (EFI) which could produce plasma during electric explosion can serve as a good carrier for studying the EEC. To investigate the enhancement ability and mechanism of EEC in EFI ignition performance, a kind of EFI chips which could realize the EEC effect was designed and fabricated to observe the characteristics of current and voltage, flyer and plasma temperature during Boron Potassium Nitrate (BPN) ignition of the EFI. It was found that the EEC could enhance EFI ignition in terms of energy utilization, ignition contact surface, and high-temperature sustainability of plasma: firstly, the EEC prolonged the late time discharge (LTD) phase of the electric explosion, making the energy of capacitor effectively utilized; secondly, the EEC could create a larger area of ignition contact surface; last of all, the EEC effect enhanced its high-temperature sustainability by sustaining continuous energy input to plasma. It also was found that the ignition voltage of BPN could be reduced by nearly 600 V under the condition of 0.4 μF capacitance. The research has successfully combined EEC with EFI, revealing the behavioral characteristics of EEC and demonstrating its effective enhancement of EFI ignition. It introduces a new approach to improving EFI output, which is conducive to low-energy ignition of EFI, and expected to take the ignition technology of EFI to a new level.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"68 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-22DOI: 10.1016/j.dt.2024.06.012
Zehao Wang, Pengfei Xue, Qingxuan Zeng, Mingyu Li
The integration method of exploding foil initiator system (EFIs) used to be researched to broaden its application range in military and aerospace in the last few decades. In order to lower the firing voltage below 1 kV, an integrated EFIs with enhanced energy efficiency was designed. Corresponding exploding foil initiator chips were fabricated in batch via micro electromechanical systems technology by integrating a unified foil, a flyer layer and a barrel on a glass substrate successively, meanwhile its package of the whole system was proposed at a volume of 2.194 cm. The structural parameters were determined by predicted performance including flyer velocity, impact behavior and conduction property via the proposed theoretical models and the static electric field simulation. As expect, this integrated EFIs exhibited excellent functions, which could accelerate the flyer to a terminal velocity over 4 km/s and preeminently initiate HNS-IV pellet at a circuit of 0.24 μF/0.9 kV. Furthermore, the theoretical design, fabrication and performance test have been all included to validate the feasibility of this integrated EFIs that was beneficial for its commercial development in the future.
{"title":"Design, fabrication and performance test of an integrated exploding foil initiator system","authors":"Zehao Wang, Pengfei Xue, Qingxuan Zeng, Mingyu Li","doi":"10.1016/j.dt.2024.06.012","DOIUrl":"https://doi.org/10.1016/j.dt.2024.06.012","url":null,"abstract":"The integration method of exploding foil initiator system (EFIs) used to be researched to broaden its application range in military and aerospace in the last few decades. In order to lower the firing voltage below 1 kV, an integrated EFIs with enhanced energy efficiency was designed. Corresponding exploding foil initiator chips were fabricated in batch via micro electromechanical systems technology by integrating a unified foil, a flyer layer and a barrel on a glass substrate successively, meanwhile its package of the whole system was proposed at a volume of 2.194 cm. The structural parameters were determined by predicted performance including flyer velocity, impact behavior and conduction property via the proposed theoretical models and the static electric field simulation. As expect, this integrated EFIs exhibited excellent functions, which could accelerate the flyer to a terminal velocity over 4 km/s and preeminently initiate HNS-IV pellet at a circuit of 0.24 μF/0.9 kV. Furthermore, the theoretical design, fabrication and performance test have been all included to validate the feasibility of this integrated EFIs that was beneficial for its commercial development in the future.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"771 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141784749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-22DOI: 10.1016/j.dt.2024.06.014
Chengjun Yue, Li Chen, Zhan Li, Bin Feng, Ruizhi Xu
The gas explosion in residential building has always been a highly concerned problem. Explosions in homogeneous mixtures have been extensively studied. However, mixtures are often inhomogeneous in the practical scenarios due to the differences in the densities of methane and air. In order to investigate the effects of gas explosions in inhomogeneous mixtures, experimental studies involving gas leakage and explosion are conducted in a full-scale residential building to reproduce the process of gas explosion. By fitting the dimensionless buoyancy as a function of dimensionless height and dimensionless time, a distribution model of gas in large-scale spaces is established, and the mechanism of inhomogeneous distribution of methane is also be revealed. Furthermore, the stratified reconstruction method (SRM) is introduced for efficiently setting up inhomogeneous concentration fields in FLACS. The simulation results highlight that for the internal overpressure, the distribution of methane has no effect on the first overpressure peak (ΔP1), while it significantly influences the subsequent overpressure peak (ΔP2), and the maximum difference between the overpressure of homogeneous and inhomogeneous distribution is 174.3%. Moreover, the initial concentration distribution also has a certain impact on the external overpressure.
{"title":"Research on the hazards of gas leakage and explosion in a full-scale residential building","authors":"Chengjun Yue, Li Chen, Zhan Li, Bin Feng, Ruizhi Xu","doi":"10.1016/j.dt.2024.06.014","DOIUrl":"https://doi.org/10.1016/j.dt.2024.06.014","url":null,"abstract":"The gas explosion in residential building has always been a highly concerned problem. Explosions in homogeneous mixtures have been extensively studied. However, mixtures are often inhomogeneous in the practical scenarios due to the differences in the densities of methane and air. In order to investigate the effects of gas explosions in inhomogeneous mixtures, experimental studies involving gas leakage and explosion are conducted in a full-scale residential building to reproduce the process of gas explosion. By fitting the dimensionless buoyancy as a function of dimensionless height and dimensionless time, a distribution model of gas in large-scale spaces is established, and the mechanism of inhomogeneous distribution of methane is also be revealed. Furthermore, the stratified reconstruction method (SRM) is introduced for efficiently setting up inhomogeneous concentration fields in FLACS. The simulation results highlight that for the internal overpressure, the distribution of methane has no effect on the first overpressure peak (ΔP1), while it significantly influences the subsequent overpressure peak (ΔP2), and the maximum difference between the overpressure of homogeneous and inhomogeneous distribution is 174.3%. Moreover, the initial concentration distribution also has a certain impact on the external overpressure.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"87 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141572580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-18DOI: 10.1016/j.dt.2024.06.009
Tawfiq Aljohani, Abdulaziz Almutairi
With the continuous development of transportation electrification, the cybersecurity of energy infrastructure has become increasingly prominent. Explicitly, EVs resemble a significant tool to carryout cyberattacks since EVs are not only seen as dynamic loads but also as mobile energy sources that establish two-way communications with several players in the grid. This taxonomy aims to provide a comprehensive overview of cyberattacks against EVs from four distinct perspectives. The first is the research domains of EVs application, which investigates the different fields of research related to the development and application of EVs and how they are susceptible to cyber threats. The second is the CIA-based attacks, which examines the threats to the confidentiality, integrity, and availability of EVs' sensitive information and critical systems. The third taxonomy discusses the countermeasures and defensive mechanisms to secure the EVs against cyberattacks, including preventive measures, detection algorithms, response strategy, and recovery techniques. The fourth taxonomy is the verification and validation methodologies, which explores the software tools and hardware testbeds used to test and evaluate the security of EVs against cyber threats. Finally, this taxonomy presents an understanding of the current state of cyberattacks against EVs and serves as a valuable resource for researchers and practitioners in the fields of cybersecurity and electric mobility.
随着交通电气化的不断发展，能源基础设施的网络安全问题日益突出。明确地说，电动汽车是实施网络攻击的重要工具，因为电动汽车不仅被视为动态负载，还是与电网中多个参与者建立双向通信的移动能源。本分类法旨在从四个不同角度全面概述针对电动汽车的网络攻击。首先是电动汽车应用的研究领域，调查与电动汽车开发和应用相关的不同研究领域，以及它们如何容易受到网络威胁。第二类是基于 CIA 的攻击，研究对电动汽车敏感信息和关键系统的保密性、完整性和可用性的威胁。第三个分类法讨论确保电动汽车免受网络攻击的对策和防御机制，包括预防措施、检测算法、响应策略和恢复技术。第四个分类法是验证和确认方法，探讨用于测试和评估电动汽车应对网络威胁的安全性的软件工具和硬件测试平台。最后，本分类法介绍了针对电动汽车的网络攻击的现状，为网络安全和电动汽车领域的研究人员和从业人员提供了宝贵的资源。
{"title":"A comprehensive survey of cyberattacks on EVs: Research domains, attacks, defensive mechanisms, and verification methods","authors":"Tawfiq Aljohani, Abdulaziz Almutairi","doi":"10.1016/j.dt.2024.06.009","DOIUrl":"https://doi.org/10.1016/j.dt.2024.06.009","url":null,"abstract":"With the continuous development of transportation electrification, the cybersecurity of energy infrastructure has become increasingly prominent. Explicitly, EVs resemble a significant tool to carryout cyberattacks since EVs are not only seen as dynamic loads but also as mobile energy sources that establish two-way communications with several players in the grid. This taxonomy aims to provide a comprehensive overview of cyberattacks against EVs from four distinct perspectives. The first is the research domains of EVs application, which investigates the different fields of research related to the development and application of EVs and how they are susceptible to cyber threats. The second is the CIA-based attacks, which examines the threats to the confidentiality, integrity, and availability of EVs' sensitive information and critical systems. The third taxonomy discusses the countermeasures and defensive mechanisms to secure the EVs against cyberattacks, including preventive measures, detection algorithms, response strategy, and recovery techniques. The fourth taxonomy is the verification and validation methodologies, which explores the software tools and hardware testbeds used to test and evaluate the security of EVs against cyber threats. Finally, this taxonomy presents an understanding of the current state of cyberattacks against EVs and serves as a valuable resource for researchers and practitioners in the fields of cybersecurity and electric mobility.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"32 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141948365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-30DOI: 10.1016/j.dt.2024.04.017
Amir Abdelaziz, Djalal Trache, Ahmed Fouzi Tarchoun, Hani Boukeciat, Yash Pal, Sourbh Thakur, Weiqiang Pang, Thomas M. Klapötke
The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate (AN) particles utilizing a microencapsulation technique, which involves solvent/non-solvent in which nitrocellulose (NC) has been employed as a coating agent. The SEM micrographs revealed distinct features of both pure AN and NC, contrasting with the irregular granular surface topography of the coated AN particles, demonstrating the adherence of NC on the AN surface. Structural analysis infrared spectroscopy (IR) demonstrated a successful association of AN and NC, with slight shifts observed in IR bands indicating interfacial interactions. Powder X-ray Diffraction (PXRD) analysis further elucidated the structural changes induced by the coating process, revealing that the NC coating altered the crystallization pattern of its pure form. Thermal analysis demonstrates distinct profiles for pure and coated AN, for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6 °C, and 36%, respectively. Furthermore, the presence of NC coating alters the intermolecular forces within the composite system, leading to a reduction in melting enthalpy of coated AN by ∼39% compared to pure AN. The thermal decomposition analysis shows a two-step thermolysis process for coated AN, with a significant increase in the released heat by about 78% accompanied by an increase in the activation barrier of NC and AN thermolysis, demonstrating a stabilized reactivity of the AN-NC particles. These findings highlight the synergistic effect of NC coating on AN particles, which contributed to a structural and reactive stabilization of both AN and NC, proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.
本研究旨在利用微胶囊技术稳定硝酸铵（AN）颗粒的室温各向同性转变，该技术涉及溶剂/非溶剂，其中采用硝化纤维素（NC）作为涂层剂。扫描电镜显微照片显示了纯 AN 和 NC 的明显特征，与涂覆 AN 颗粒的不规则颗粒表面形貌形成鲜明对比，表明 NC 附着在 AN 表面。红外光谱（IR）结构分析表明 AN 和 NC 成功地结合在一起，观察到的红外波段有轻微偏移，表明存在界面相互作用。粉末 X 射线衍射 (PXRD) 分析进一步阐明了涂层过程引起的结构变化，显示出 NC 涂层改变了其纯形式的结晶模式。热分析显示了纯 AN 和涂层 AN 的不同曲线，其中涂层样品的室温各向同性转变温度和焓值分别提高了 6 ℃ 和降低了 36%。此外，NC 涂层的存在改变了复合体系内的分子间作用力，导致涂层 AN 的熔化焓比纯 AN 降低了 39%。热分解分析表明，包覆 AN 的热分解过程分为两步，释放的热量显著增加了约 78%，同时 NC 和 AN 的热分解活化势垒也有所提高，这表明 AN-NC 颗粒的反应活性趋于稳定。这些发现凸显了数控涂层对 AN 粒子的协同效应，有助于 AN 和数控的结构和反应稳定化，证明了数控涂层 AN 作为一种具有战略优势的氧化剂在复合固体推进剂配方中的潜在应用。
{"title":"Synergistic effect of nitrocellulose coating on structural and reactivity stabilization of ammonium nitrate oxidizer","authors":"Amir Abdelaziz, Djalal Trache, Ahmed Fouzi Tarchoun, Hani Boukeciat, Yash Pal, Sourbh Thakur, Weiqiang Pang, Thomas M. Klapötke","doi":"10.1016/j.dt.2024.04.017","DOIUrl":"https://doi.org/10.1016/j.dt.2024.04.017","url":null,"abstract":"The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate (AN) particles utilizing a microencapsulation technique, which involves solvent/non-solvent in which nitrocellulose (NC) has been employed as a coating agent. The SEM micrographs revealed distinct features of both pure AN and NC, contrasting with the irregular granular surface topography of the coated AN particles, demonstrating the adherence of NC on the AN surface. Structural analysis infrared spectroscopy (IR) demonstrated a successful association of AN and NC, with slight shifts observed in IR bands indicating interfacial interactions. Powder X-ray Diffraction (PXRD) analysis further elucidated the structural changes induced by the coating process, revealing that the NC coating altered the crystallization pattern of its pure form. Thermal analysis demonstrates distinct profiles for pure and coated AN, for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6 °C, and 36%, respectively. Furthermore, the presence of NC coating alters the intermolecular forces within the composite system, leading to a reduction in melting enthalpy of coated AN by ∼39% compared to pure AN. The thermal decomposition analysis shows a two-step thermolysis process for coated AN, with a significant increase in the released heat by about 78% accompanied by an increase in the activation barrier of NC and AN thermolysis, demonstrating a stabilized reactivity of the AN-NC particles. These findings highlight the synergistic effect of NC coating on AN particles, which contributed to a structural and reactive stabilization of both AN and NC, proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"19 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141197773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-27DOI: 10.1016/j.dt.2024.04.007
M.Z. Naser
Causality, the science of cause and effect, has made it possible to create a new family of models. Such models are often referred to as causal models. Unlike those of mathematical, numerical, empirical, or machine learning (ML) nature, causal models hope to tie the cause(s) to the effect(s) pertaining to a phenomenon (i.e., data generating process) through causal principles. This paper presents one of the first works at creating causal models in the area of structural and construction engineering. To this end, this paper starts with a brief review of the principles of causality and then adopts four causal discovery algorithms, namely, PC (Peter-Clark), FCI (fast causal inference), GES (greedy equivalence search), and GRaSP (greedy relaxation of the sparsest permutation), have been used to examine four phenomena, including predicting the load-bearing capacity of axially loaded members, fire resistance of structural members, shear strength of beams, and resistance of walls against impulsive (blast) loading. Findings from this study reveal the possibility and merit of discovering complete and partial causal models. Finally, this study also proposes two simple metrics that can help assess the performance of causal discovery algorithms.
{"title":"Discovering causal models for structural, construction and defense-related engineering phenomena","authors":"M.Z. Naser","doi":"10.1016/j.dt.2024.04.007","DOIUrl":"https://doi.org/10.1016/j.dt.2024.04.007","url":null,"abstract":"Causality, the science of cause and effect, has made it possible to create a new family of models. Such models are often referred to as causal models. Unlike those of mathematical, numerical, empirical, or machine learning (ML) nature, causal models hope to tie the cause(s) to the effect(s) pertaining to a phenomenon (i.e., data generating process) through causal principles. This paper presents one of the first works at creating causal models in the area of structural and construction engineering. To this end, this paper starts with a brief review of the principles of causality and then adopts four causal discovery algorithms, namely, PC (Peter-Clark), FCI (fast causal inference), GES (greedy equivalence search), and GRaSP (greedy relaxation of the sparsest permutation), have been used to examine four phenomena, including predicting the load-bearing capacity of axially loaded members, fire resistance of structural members, shear strength of beams, and resistance of walls against impulsive (blast) loading. Findings from this study reveal the possibility and merit of discovering complete and partial causal models. Finally, this study also proposes two simple metrics that can help assess the performance of causal discovery algorithms.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"31 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141197772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-22DOI: 10.1016/j.dt.2023.12.005
Ya Yang, Xiangzhen Kong, Qin Fang
Foam concrete is a prospective material in defense engineering to protect structures due to its high energy absorption capability resulted from the long plateau stage. However, stress enhancement rather than stress mitigation may happen when foam concrete is used as sacrificial claddings placed in the path of an incoming blast load. To investigate this interesting phenomenon, a one-dimensional difference model for blast wave propagation in foam concrete is firstly proposed and numerically solved by improving the second-order Godunov method. The difference model and numerical algorithm are validated against experimental results including both the stress mitigation and the stress enhancement. The difference model is then used to numerically analyze the blast wave propagation and deformation of material in which the effects of blast loads, stress–strain relation and length of foam concrete are considered. In particular, the concept of minimum thickness of foam concrete to avoid stress enhancement is proposed. Finally, non-dimensional analysis on the minimum thickness is conducted and an empirical formula is proposed by curve-fitting the numerical data, which can provide a reference for the application of foam concrete in defense engineering.
{"title":"Non-dimensional analysis on blast wave propagation in foam concrete: Minimum thickness to avoid stress enhancement","authors":"Ya Yang, Xiangzhen Kong, Qin Fang","doi":"10.1016/j.dt.2023.12.005","DOIUrl":"https://doi.org/10.1016/j.dt.2023.12.005","url":null,"abstract":"<p>Foam concrete is a prospective material in defense engineering to protect structures due to its high energy absorption capability resulted from the long plateau stage. However, stress enhancement rather than stress mitigation may happen when foam concrete is used as sacrificial claddings placed in the path of an incoming blast load. To investigate this interesting phenomenon, a one-dimensional difference model for blast wave propagation in foam concrete is firstly proposed and numerically solved by improving the second-order Godunov method. The difference model and numerical algorithm are validated against experimental results including both the stress mitigation and the stress enhancement. The difference model is then used to numerically analyze the blast wave propagation and deformation of material in which the effects of blast loads, stress–strain relation and length of foam concrete are considered. In particular, the concept of minimum thickness of foam concrete to avoid stress enhancement is proposed. Finally, non-dimensional analysis on the minimum thickness is conducted and an empirical formula is proposed by curve-fitting the numerical data, which can provide a reference for the application of foam concrete in defense engineering.</p>","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"34 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139029879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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