“国家关键基础设施电磁安全”专辑出版前言

<正>国家关键基础设施电磁安全一般是指能源系统、通信系统、金融系统和交通系统等国家关键基础设施在强电磁环境下的兼容性、可靠性和安全性,侧重关注电磁易损性引起的安全问题。随着基础设施自动化、网络化、智能化水平的不断提高,以高空电磁脉冲、高功率微波、极端地磁     

《强激光与粒子束》“国家关键基础设施电磁安全”专辑征稿通知

正近年来,电力系统、油气管道、高速铁路、电信设施、互联网、金融系统等国家关键基础设施广泛使用电力电子器件和自动化、网络化、智能化等现代技术,技术水平突飞猛进。与此同时,电磁兼容和电磁安全问题也日益得到重视,特别是强电磁脉冲环境下(高空电磁脉冲、高功率微波、雷电、极端地磁暴等)关键基础设施的电磁安全问题已经成为国内外的关注热点。为了促进强电磁脉冲技术和国家关键基础设施电磁安全领域的学术交流,集中展示国内外的最新研究进展,《强激光与粒子束》编     

时域全波电磁计算程序JEMS-FDTD在复杂电磁环境研究中的应用

将自主研发的大规模并行三维全波电磁场时域求解程序JEMS-FDTD应用于复杂电磁环境问题,计算并分析了楼宇内电波传播特性和飞行器瞬态电磁特性。对楼宇内电波传播特性的计算获得了建筑物内任意位置的电磁场分布和电磁脉冲在建筑物内的时域传播过程,其结果可用于无线通信和电磁环境安全研究;对飞行器瞬态电磁特性的计算获得了飞行器舱内外瞬态电磁近场分布,其结果可用于飞行器强辐射场防护等研究。     

超短波跳频电台复杂电磁环境适应能力评估方法

以某型超短波通信电台为例,分析了该电台工作于跳频组网状态时所面临的复杂电磁信号环境,在电台使用区域内,根据构成威胁电磁环境、目标电磁环境和背景电磁环境的各电子设备的频谱占用度、时间占有度、空间覆盖率的不同,提出了复杂电磁环境量化分级标准。采取实装构设与模拟仿真技术相结合的手段,分别构建了针对该电台的简单、轻度、中度和重度等不同级别的复杂电磁环境,并给出了电台对不同等级复杂电磁环境适应能力的初步评估结论。项目成果可为今后电子信息装备复杂电磁环境适应性的理论研究工作提供有益借鉴。     

电磁作战环境概念分析

从近年来热议的电磁频谱战入手,分析了此概念群的来龙去脉,并深入解读和分析了联合电磁频谱作战、电磁作战环境、电磁战斗序列与传统电磁环境等概念及其相互关系;从《军语》定义出发,透视了电磁作战环境的电磁环境结构,刻画了其对军事力量的电磁影响,揭示出电磁作战环境与复杂电磁环境具有情理之中的同构;通过案例也提醒人们电磁作战环境仍有意料之外的复杂性;最后,指出新老概念的辩证统一。     

典型光电系统强电磁脉冲耦合分析与加固方法

随着电磁环境的日益复杂,电子设备面临的电磁威胁愈加严峻。光电系统作为高灵敏集成化电子设备,强电磁脉冲能量耦合进入系统内部,影响防护能力本就薄弱的光电系统的正常运行。为明晰典型光电系统强电磁耦合过程,通过仿真分析不同强电磁辐照条件下筒型、侧窗型和多窗口型三种典型光电系统的强电磁耦合情况,提取了光电系统强电磁耦合特征及其制约因素,验证了光电系统进行强电磁防护加固的必要性和紧迫性。为解决光电系统强电磁防护能力薄弱的问题,通过仿真分析,验证了透明电磁防护窗口的强电磁加固效能;开展了基于支撑台阶与导电侧壁的电磁缝隙防护加固方法研究,分析了透明防护窗口缝隙耦合泄露的关键安装结构参数,提出了一种非电接触式装配缝隙强电磁防护加固方法。经测试,当缝隙防护结构长度为6 mm时,在0.2～4 GHz频率范围光电系统平均强电磁防护效能提升4.51 dB。研究结果为光电系统强电磁防护能力提升提供了理论指导和具体解决方案。     

武器装备全寿命复杂电磁环境试验与评估方法

介绍了业内普遍接受的电磁环境和武器装备电磁环境效应概念,以及美军电磁环境效应试验的相关内容和理念,说明了电磁环境效应问题与复杂电磁环境问题的关系与本质。通过对复杂电磁环境的分解,从数学上给出武器装备复杂电磁环境适应性试验与评估的理论方法,这种方法在实施效益上具有全面性、完整性、通用性和可操作性,试验与评估结果具有客观稳定性。结合武器装备全寿命周期过程,给出了武器装备论证阶段、技术开发阶段、研制试验阶段、量产和装备部署阶段、形成完全作战能力阶段武器装备复杂电磁环境试验与评估的实施方法。     

无人机在复杂电磁环境下的效能评估

通过分析无人机的结构层次和研究复杂电磁环境对无人机的影响,建立了复杂电磁环境下无人机的效能评估指标体系,通过主观赋权法和客观赋权法得到各项指标的权重,针对评估指标的模糊性和不确定性,基于云理论的原理,实现一定条件下评估指标的定性与定量的描述,综合考虑了评估过程中的模糊性和不确定性因素,并利用评价云模型拟合出无人机在复杂电磁环境下的综合效能。结合实例模拟分析表明,复杂电磁环境下的无人机云效能评估模型,为复杂电磁环境下无人机的定量化效能评估提供参考。     

X86军用平板电脑电磁兼容性设计

X86平板电脑是军用移动信息系统的重要组成部分,具有性能高、兼容性强等优点,电磁兼容性是设备的关键指标。为满足X86平板电脑在环境恶劣的野战条件下的使用需求,需要对其进行针对性的电磁兼容性设计。通过分析X86平板电脑电磁干扰源,提出电磁兼容设计方法,包括屏蔽、滤波和PCB板设计等,重点是显示屏蔽和通信滤波设计。经试验分析,采取以上措施的X86平板电脑的电磁兼容性设计,能够满足国军标相关电磁兼容性要求。     

电控单元强电磁安全威胁分析及电源防护研究

强电磁脉冲通过场线耦合的方式,对车辆电子控制系统造成了严重的电磁安全威胁,影响车辆机动性能的发挥。基于典型车辆平台,分析了电控单元在强电磁脉冲环境下的效应机理,开展了整车平台的宽带强电磁脉冲辐照试验,分析了车辆平台发动机系统运行状态与电控单元电源线上耦合脉冲电压之间的关系。试验结果表明宽带电磁脉冲通过电源线缆对车辆电控单元造成干扰效应,导致发动机熄火。根据分析结果,对电控单元直流电源进行了多级防护电路设计,通过切断电磁脉冲能量传输路径的方式实现电磁安全防护,并验证了防护电路的有效性。     

Vulnerability analysis of interdependent infrastructure systems: A methodological framework

Infrastructure systems such as power and water supplies make up the cornerstone of modern society which is essential for the functioning of a society and its economy. They become more and more interconnected and interdependent with the development of scientific technology and social economy. Risk and vulnerability analysis of interdependent infrastructures for security considerations has become an important subject, and some achievements have been made in this area. Since different infrastructure systems have different structural and functional properties, there is no universal all-encompassing ‘silver bullet solution’ to the problem of analyzing the vulnerability associated with interdependent infrastructure systems. So a framework of analysis is required. This paper takes the power and water systems of a major city in China as an example and develops a framework for the analysis of the vulnerability of interdependent infrastructure systems. Four interface design strategies based on distance, betweenness, degree, and clustering coefficient are constructed. Then two types of vulnerability (long-term vulnerability and focused vulnerability) are illustrated and analyzed. Finally, a method for ranking critical components in interdependent infrastructures is given for protection purposes. It is concluded that the framework proposed here is useful for vulnerability analysis of interdependent systems and it will be helpful for the system owners to make better decisions on infrastructure design and protection.     

The impact of model detail on power grid resilience measures

Extreme events are a challenge to natural as well as man-made systems. For critical infrastructure like power grids, we need to understand their resilience against large disturbances. Recently, new measures of the resilience of dynamical systems have been developed in the complex system literature. Basin stability and survivability respectively assess the asymptotic and transient behavior of a system when subjected to arbitrary, localized but large perturbations in frequency and phase. To employ these methods that assess power grid resilience, we need to choose a certain model detail of the power grid. For the grid topology we considered the Scandinavian grid and an ensemble of power grids generated with a random growth model. So far the most popular model that has been studied is the classical swing equation model for the frequency response of generators and motors. In this paper we study a more sophisticated model of synchronous machines that also takes voltage dynamics into account, and compare it to the previously studied model. This model has been found to give an accurate picture of the long term evolution of synchronous machines in the engineering literature for post fault studies. We find evidence that some stable fix points of the swing equation become unstable when we add voltage dynamics. If this occurs the asymptotic behavior of the system can be dramatically altered, and basin stability estimates obtained with the swing equation can be dramatically wrong. We also find that the survivability does not change significantly when taking the voltage dynamics into account. Further, the limit cycle type asymptotic behaviour is strongly correlated with transient voltages that violate typical operational voltage bounds. Thus, transient voltage bounds are dominated by transient frequency bounds and play no large role for realistic parameters.     

Local vs. global redundancy – trade-offs between resilience against cascading failures and frequency stability

When designing or extending electricity grids, both frequency stability and resilience against cascading failures have to be considered amongst other aspects of energy security and economics such as construction costs due to total line length. Here, we compare an improved simulation model for cascading failures with state-of-the-art simulation models for short-term grid dynamics. Random ensembles of realistic power grid topologies are generated using a recent model that allows for a tuning of global vs local redundancy. The former can be measured by the algebraic connectivity of the network, whereas the latter can be measured by the networks transitivity. We show that, while frequency stability of an electricity grid benefits from a global form of redundancy, resilience against cascading failures rather requires a more local form of redundancy and further analyse the corresponding trade-off.     

Modeling extreme values resulting from compromising electromagnetic emanations generated by an information system

Electromagnetic intelligence and attacks pose unacceptable risks for the security and safety of critical networks and more specifically the power network. In this paper, it is pointed out how the use of the excess model allows one to extrapolate the very high level of spurious compromising emanations induced by an information system in realistic power network models. It is shown that the design of appropriate protections and risk management methodologies can be enhanced thanks to the extreme value statistics.     

Development of low loss Mn–Zn ferrite working at frequency higher than 3 MHz

With the advance of modern electronic technology, there has been a critical need for Mn–Zn ferrites with even higher permeability and even lower power loss at higher frequencies. In this study, ferrite with extremely low losses than conventional ferrite materials at high frequency was developed employing a conventional ceramic powder processing technique. As a result, the core loss at 3 MHz, 10 mT and 100 °C is around 300 kW/m³, and its cutoff frequency is 4 MHz. Furthermore, the electromagnetic characteristics and the microstructure of this new DMR50 material are also discussed.     

Near-field thermal emission from metamaterials

A closed form expression for the local density of electromagnetic states (LDOS) due to a thermally emitting metamaterial bulk is derived from Maxwell's equations combined with fluctuational electrodynamics. The final form is the same as that for nonmagnetic materials, where the influence of the magnetic permeability is embedded in the Fresnel reflection coefficients. Spectral distributions of LDOS near metallic- and dielectric-based metamaterials are investigated. Results reveal that LDOS profiles are dominated by surface polaritons (SPs) in both TE and TM polarization states. A detailed discussion is provided on the necessary conditions for exciting TM- and TE-polarized SPs via a dispersion relation analysis that accounts for losses. Beyond the conventional conditions for excitation of SPs, the lossy dispersion relation analysis demonstrates mathematically that SPs exist when the imaginary parts of the permittivity or permeability, as well as n′n″, are close to zero, where n′ and n″ are the real and imaginary parts of the refractive index, respectively. An asymptotic expression for the extreme near field LDOS is derived, showing a Δ^?3 power law relationship, as for nonmagnetic media, between LDOS and distance from the emitting bulk Δ. Results obtained from this study will assist in assessing material properties of arbitrarily electromagnetic materials in applications related to energy harvesting.     

Robustness of spatial networks and networks of networks

Many complex networks have recently been recognized to involve significant interdependence between different systems. Motivation comes primarily from infrastructures like power grids and communications networks, but also includes areas such as the human brain and finance. Interdependence implies that when components in one system fail, they lead to failures in the same system or other systems. This can then lead to additional failures finally resulting in a long cascade that can cripple the entire system. Furthermore, many of these networks, in particular infrastructure networks, are embedded in space and thus have unique spatial properties that significantly decrease their resilience to failures. Here we present a review of novel results on interdependent spatial networks and how cascading processes are affected by spatial embedding. We include various aspects of spatial embedding such as cases where dependencies are spatially restricted and localized attacks on nodes contained in some spatial region of the network. In general, we find that spatial networks are more vulnerable when they are interdependent and that they are more likely to undergo abrupt failure transitions than interdependent non-embedded networks. We also present results on recovery in spatial networks, the nature of cascades due to overload failures in these networks, and some examples of percolation features found in real-world traffic networks. Finally, we conclude with an outlook on future possible research directions in this area.     

Leadership Hijacking in Docker Swarm and Its Consequences

With the advent of microservice-based software architectures, an increasing number of modern cloud environments and enterprises use operating system level virtualization, which is often referred to as container infrastructures. Docker Swarm is one of the most popular container orchestration infrastructures, providing high availability and fault tolerance. Occasionally, discovered container escape vulnerabilities allow adversaries to execute code on the host operating system and operate within the cloud infrastructure. We show that Docker Swarm is currently not secured against misbehaving manager nodes. This allows a high impact, high probability privilege escalation attack, which we refer to as leadership hijacking, the possibility of which is neglected by the current cloud security literature. Cloud lateral movement and defense evasion payloads allow an adversary to leverage the Docker Swarm functionality to control each and every host in the underlying cluster. We demonstrate an end-to-end attack, in which an adversary with access to an application running on the cluster achieves full control of the cluster. To reduce the probability of a successful high impact attack, container orchestration infrastructures must reduce the trust level of participating nodes and, in particular, incorporate adversary immune leader election algorithms.     

Extreme events in epileptic EEG of rodents after ischemic stroke

Extreme events are observed on electroencephalographic (EEG) recordings of rodents with induced ischemic stroke. These events represent themselves as post-stroke epileptic seizures in the form of spontaneous high-amplitude oscillations, which appear during the first 2–3 h after induced focal cerebral ischemia. The analysis of the EEG time-frequency structure reveals these extreme events as a sharp sudden growth of the wavelet energy in a particular frequency band, while the energy in the resting part of the power spectrum remains normal. The distinguished features of the extreme events are used for detection and quantification of the pathological brain activity.