Deep learning-based method for detecting anomalies in electromagnetic environment situation

The anomaly detection of electromagnetic environment situation(EMES) has essential reference value for electromagnetic equipment behavior cognition and battlefield threat assessment.In this paper,we proposed a deep learning-based method for detecting anomalies in EMES to address the problem of relatively low efficiency of electromagnetic environment situation anomaly detection(EMES-AD).Firstly,the convolutional kernel extracts the static features of different regions of the EMES.Secondly,the dynamic features of the region are obtained by using a recurrent neural network(LSTM).Thirdly,the Spatio-temporal features of the region are recovered by using a de-convolutional network and then fused to predict the EMES.The structural similarity algorithm(SSIM) is used to determine whether it is anomalous.We developed the detection framework,de-signed the network parameters,simulated the data sets containing different anomalous types of EMES,and carried out the detection experiments.The experimental results show that the proposed method is effective.

Biomass-Derived Carbon Heterostructures Enable Environmentally Adaptive Wideband Electromagnetic Wave Absorbers

Although advances in wireless technologies such as miniature and wearable electronics have improved the quality of our lives,the ubiquitous use of electronics comes at the expense of increased exposure to electromagnetic(EM)radiation.Up to date,extensive efforts have been made to develop high-performance EM absorbers based on synthetic materials.However,the design of an EM absorber with both exceptional EM dissipation ability and good environmental adaptability remains a substantial challenge.Here,we report the design of a class of carbon heterostructures via hierarchical assembly of graphitized lignocellulose derived from bamboo.Specifically,the assemblies of nanofibers and nanosheets behave as a nanometer-sized antenna,which results in an enhancement of the conductive loss.In addition,we show that the composition of cellulose and lignin in the precursor significantly influences the shape of the assembly and the formation of covalent bonds,which affect the dielectric response-ability and the surface hydrophobicity(the apparent contact angle of water can reach 135°).Finally,we demonstrate that the obtained carbon heterostructure maintains its wideband EM absorption with an effective absorption frequency ranging from 12.5 to 16.7 GHz under conditions that simulate the real-world environment,including exposure to rainwater with slightly acidic/alkaline pH values.Overall,the advances reported in this work provide new design principles for the synthesis of high-performance EM absorbers that can find practical applications in real-world environments.

Electromagnetic environments in roadways of underground coal mines and a novel testing method

The electromagnetic environment of laneways in underground coal mines is an important area for the design of new electronic products,as well as a fundamental space for mine monitoring,surveillance,communications and control systems.An investigation of electromagnetic interference in coal mines is essential for the enhancement of performances of these systems.In this study,a new field method is provided in which radiated emission tests in coal mine laneways have been carried out.We conclude that:1) the wiring motor vehicles can radiate interference with a bandwidth up to 1 GHz and with an amplitude 10 dBμV/m higher than the background noise;2) the PHS(Personal Handy phone System) mobile communication system can cause interference 40 dBμV/m higher than the background noise;3) an interference 25 dBμV/m higher than the background noise can be generated during the communication at a working bandwidth of 48.8 MHz;and 4) power cables,battery vehicles as well as mechanical and electrical dong rooms have little effect on the electromagnetic radiation environment in coal mine tunnels.

Research on Distribution of Electromagnetic Environment around Substations and Optimization Layout of On-line Monitoring

The characteristics and distribution law of electromagnetic environment around substations with different levels of voltage were studied,and the main influencing factors were discussed. Meanwhile,a scheme for locating monitoring points suitable for an on-line monitoring system of electromagnetic environment was proposed.

A Spectrum Prediction-Based Frequency Band Pre-Selection over Deteriorating HF Electromagnetic Environment

As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in efficient manner becomes one of the key challenges in HF communication. Spectrum prediction infers the future spectrum status from history spectrum data by exploring the inherent correlations and regularities. The investigation of HF electromagnetic environment data reveals the correlations and predictability of HF frequency band in both time and frequency domain. To solve this problem, we develop a Spectrum Prediction-based Frequency Band Pre-selection(SP-FBP) for HF communications. The pre-selection of HF frequency band mainly incorporated in prediction of HF spectrum occupancy and prediction of HF usable frequency, which provide the frequency band ranking of spectrum occupancy and alternative frequency for spectrum sensing, respectively. Performance evaluation via real-world HF spectrum data shows that SP-FBP significantly improves the efficiency of finding quality frequency in HF communications.

Research Progress of On-line Monitoring Technology for Electromagnetic Environment of Power Transmission and Transformation Projects

Based on the collection of relevant literature and cases,the research and application status of on-line monitoring technology for electromagnetic environment of power transmission and transformation projects at home and abroad were introduced.Moreover,the problems existing in the on-line monitoring of electromagnetic environment were expounded,and the development prospect was forecasted.

Study on the Simulation Technique for Urban Electromagnetic Environment Supported by GIS

Electromagnetic radiation environment is one of the important environmental factors. In resent 20 years, the applications of electromagnetic technology became more and more popular. However, electromagnetic environment makes some negative impacts on the surrounding environments and human health, and Environmental Management and Research Department pay a lot attention to it. It will make a great significance if we study of the simulation technique for urban electromagnetic environment which supported by GIS. This paper presents some key technologies of the electromagnetic environment simulation, including terrain rendering, city building modeling and volume data superposition, basically realize the visualization of volume data (electromagnetic fields) based on city building model and real time mapping of virtual scene data.

The Measurement and Evaluation of the Electromagnetic Environment from 5G Base Station

In order to evaluate the electromagnetic environment of 5G base station, measurement and evaluation of the electromagnetic environment are studied. The 12 measuring points are chosen on the roof, inside and outside of the building, which has a 5G base station on the top. The electric field intensity, magnetic field intensity, and power density have been measured. The measurement methods include background measurement and work measurement. Background measurement is the measurement of environmental electromagnetic field (EMF) before the installation of 5G base station while the working measurement is the measurement after the installation of 5G base station. The evaluation methods include t-test for qualitative evaluation and electromagnetic gain for quantitative evaluation. The results show that the electromagnetic environment after the installation of 5G base station in most places is different from that in the background. And the environmental electromagnetic fields in certain parts are lower than those in the background. The conclusions are as follows: 1) The electromagnetic environment of 5G base station is far lower than the control limit of the national standard and conforms to the national standard;2) The electromagnetic environment of 5G base station has little impact on the electromagnetic environment;3) It is not sufficient to assume that 5G is harmful to health without the results of the epidemiological investigation;4) Before the construction of 5G base station, do background EMF detection, which can provide support for future evaluation.

Analysis of Electromagnetic Environment Effect Using TDIE-FDTD-MNA Hybrid Algorithm

It is important but difficult to analyze the electromagnetic environment effect(E3) in the designing of modern airborne,sea,space,and ground systems.Thus a hybrid algorithm of time domain integral equation,finite difference time domain and modified nodal analysis(TDIE-FDTD-MNA) is developed to analyze the E3 of complex systems with cables and nonlinear circuit structures.The plane wave time domain(PWTD) enhanced TDIE method is adopted to solve field problems.The higher order FDTD(2,4) is adopted to solve cable problems.The MNA is adopted to obtain the response of complex circuits(with nonlinear structures).Numerical examples demonstrate the effectiveness of the proposed algorithm.

A Predictive 6G Network with Environment Sensing Enhancement:From Radio Wave Propagation Perspective

In order to support the future digital society,sixth generation(6G)network faces the challenge to work efficiently and flexibly in a wider range of scenarios.The traditional way of system design is to sequentially get the electromagnetic wave propagation model of typical scenarios firstly and then do the network design by simulation offline,which obviously leads to a 6G network lacking of adaptation to dynamic environments.Recently,with the aid of sensing enhancement,more environment information can be obtained.Based on this,from radio wave propagation perspective,we propose a predictive 6G network with environment sensing enhancement,the electromagnetic wave propagation characteristics prediction enabled network(EWave Net),to further release the potential of 6G.To this end,a prediction plane is created to sense,predict and utilize the physical environment information in EWave Net to realize the electromagnetic wave propagation characteristics prediction timely.A two-level closed feedback workflow is also designed to enhance the sensing and prediction ability for EWave Net.Several promising application cases of EWave Net are analyzed and the open issues to achieve this goal are addressed finally.

GRANITOIDS,VOLCANIC ROCKS AND CHERTS FROM NORTH ALTYN TAGH,NW CHINA: IMPLICATION FOR THE TECTONIC ENVIRONMENT DISCRIMINATION

Granitoids,volcanic rocks and cherts,mainly of early Paleozoic,in northern Altyn Tagh(Fig.1) are analyzed here for the purpose of the determination of the tectonic environments and their development since Early Paleozoic.(1) Granitoids\ The collection of 128 main\|element petrochemical data from North Altyn Tagh area shows that most of the granitoids here are granites and granodiorites of calc\|alkaline series.They consist mainly of metaluminous and peraluminous in Shand’s index,and only one of them,which belongs to Mesozoic,is peralkaline.Most of the granitoids plot in the IAG+CAG+CCG fields in the Maniar and Piccoli’s diagrams (1989) for tectonic discrimination of granitoids.IAG (Island arc granitoids)and CAG (Continental arc granitoids) can be distinguished for Early and Late Paleozoic granitoids,and maybe some CCG (Continental collision granitoids) for Early Paleozoic.Granitoids of Mesozoic and Cenozoic inherited the characteristics of those of Paleozoic.Destructive active plate margin (pre\|plate collision)and Anatectic magmatism(syn\|orogenic,S\|type granites)are distinguished (Fig.2)for Paleozoic granitoids using de la Roche R 1\| R 2 multicationic diagram (Batchelor and Bowden,1985).Mesozoic and Cenozoic granitoids inherited the characteristics of Anatectic magmatism (syn\|orogenic)of these early ones,and post\|orogenic(A\|type)granites occurred in Mesozoic.The mechanism for magma formation is mainly partial melting.

Environmental Radiation Measurement and Assessment of Natural Radioactivity in Soil, Water and Vegetation

Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (40K), are only present due to natural processes, a few isotopes, e.g. tritium (3H), result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238 (238U), can be affected by human activity because of the constant exposure of Human beings to radiation caused by terrestrial, extra-terrestrial and anthropogenic radio nuclides, it is necessary to determine and estimate the activity of various radio nuclides in environmental media such as vegetation, soil, and water. In the present research, the activities of 226Ra, 232Th and 40K are measured in soil, vegetation and water samples, collected from Yangdong District, Yangxi County, and Yangjiang County of Guangdong Province, China using an HPGe based gamma spectrometry system. The measured mean activity of 226Ra, 232Th and 40K in soil samples was found to be 31.19 ± 1.2, 47.00 ± 2.30 and 589.31 ± 17.52 Bqkg-1, respectively. The measured mean activity of these radionuclides in all water samples was found to be below minimum detectable activity. The measured mean activity of 226Ra, 232Th and 40K in vegetation samples was 19.92 ± 3.09, 25.36 ± 8.11 and 4982.94 ± 85.68 Bqkg-1, respectively. No anthropogenic 137Cs was detected in these environmental samples. Mean radium equivalent activity (Raeq), external radiation hazard index (Hex), internal radiation hazard index (Hin) and absorbed dose rate (D) for the area under study were determined as 142.92 Bqkg-1, 0.38, 0.47 and 66.47 nGyh-1, respectively. The annual effective dose equivalent (AEDE) varied in the range from 0.03 to 0.12 mSvy-1. It is concluded that the surveyed area do not pose any significant radiological risk to the population and environment.

西天山乌孙山花岗岩和闪长岩年代学、地球化学及岩石成因

笔者选取位于伊犁盆地内乌孙山北缘察布查尔林场花岗岩为研究对象,其地球化学、地质年代学和岩石成因研究对于探讨西天山南缘壳幔岩浆作用具有较重要的指示意义。岩石地球化学特征显示二长花岗岩属高钾钙碱性准铝质-弱过铝质岩石系列;轻稀土富集,弱的Eu负异常(δEu=0.74~0.84),富集大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素特征,Zr/Hf=42~44,部分样品中含有少量的刚玉标准矿物,显示出壳源花岗岩的特征。闪长岩Al_(2)O_(3)、FeOT、CaO含量明显高于二长花岗岩,Na_(2)O和K_(2)O含量低于二长花岗岩,属于高钾准铝质岩石系列;轻稀土富集,显示出Eu的轻微正异常(δEu=0.90~1.24),富集大离子亲石元素,亏损Nb、Ta等高场强元素,此外,闪长岩还显示出具有高Sr(Sr>400×10^(-6))低Y(12.83×10^(-6))及Yb(1.34×10^(-6))和高Mg^(#)特征,其源岩应为俯冲板片上覆地幔部分熔融产物。二者均显示出岛弧岩浆的特征。二长花岗岩锆石U-Pb年龄为(361.7±1.8)Ma;形成于晚泥盆世末期,结合前人的研究资料认为在~360 Ma由于南天山洋板片的回撤或俯冲流体参与,上覆地幔发生部分熔融产生了基性岩浆,岩浆上涌过程中提供大量的热导致地壳发生部分熔融形成了酸性岩浆,两种岩浆发生不均匀混合作用。上涌的岩浆引起地幔对流,导致伊犁地块内部出现一定的伸展作用(弧后伸展作用)。

电磁脉冲电场测量技术研究综述

宽频带大动态范围的脉冲电场测量是电磁脉冲效应、防护以及电磁兼容等相关领域的一项共性基础技术,在过去50年以来受到研究人员的广泛关注,并发展出不同手段的测量技术。无源微分(D-dot)测量传感器带宽相对较高,但尺寸较大、集成度低;有源光纤测量系统最大测量带宽约为1 GHz,尺寸相对较小、集成度高、实用性强。集成光学传感器作为一种带宽宽、体积小的无源传感器,各国均有研究。本文主要回顾上述几种脉冲电场测量技术近期研究进展,并结合发展现状分析脉冲电场测量技术存在的挑战和未来可能的研究方向,为相关领域研究人员提供参考。

装备复杂电磁环境适应性试验标准体系框架研究

复杂电磁环境适应性试验是进行装备试验鉴定的重要环节,也是近年来探索研究的热点问题。开展装备复杂环境适应性试验标准化研究,推动形成一系列试验标准,是规范装备复杂电磁环境适应性试验、进一步提升装备能力水平的重要环节。通过梳理国内外复杂电磁环境方面的标准现状,在分析装备复杂电磁环境适应性内涵及试验关键环节的基础上,提出了复杂电磁环境适应性试验标准体系的初步框架,可为后续进一步开展装备试验鉴定标准体系规划论证提供参考和借鉴。

多因素影响下无人机编队任务可靠性模型构建研究

针对多因素影响下无人机(unmanned aerial vehicle,UAV)编队任务可靠性问题,提出了无人机编队任务可靠性双层模型。首先,基于故障树分析方法,构建了无人机编队任务可靠性下层模型,描述无人机编队的故障状态;其次,基于Markov模型构建无人机编队任务可靠性上层模型,描述无人机编队任务过程中,阶段及状态的转换;最后,建立任务可靠度求解的双层模型对无人机编队任务可靠度进行仿真模拟。设定应用场景仿真验证,仿真结果表明:在起飞/爬升阶段和巡航阶段,本文方法与传统故障树法所计算的任务可靠度结果一致;在侦察阶段,本文方法比传统故障树法的任务可靠度计算结果高0.012 5,给定显著性水平,本文算法的可靠度结果均落在置信区间内,验证了计算结果的可信性。

750kV单回并行输电线路电磁辐射环境研究

采用《环境影响评价技术导则输变电》(HJ 24—2020)附录C、D推荐的计算模式对750 kV单回并行输电线路电磁辐射环境进行计算与预测。结果表明,经过耕地、园地、牧草地、畜禽饲养地、道路等场所,当导线对地最小高度为15.5 m时,单回并行线路下的工频电场强度最大值超过10 kV/m;需将导线对地最小高度提至16.5 m,才能满足4 kV/m控制限值要求。750 kV单回并行输电线路产生的工频磁场强度小于公众曝露控制限值(100μT),一般情况下不会成为线路建设的环境制约因素;但其产生的工频电场是电磁环境影响的主要因素,电场强度控制限值(4 kV/m)是线路建设的环境制约因素,同时也是输变电电磁环境重点控制因素。现场实测结果与理论预测结果符合性较好,表明采用的预测模式具有较好的应用性,研究结果可为750 kV单回并行输电线路的建设和环境监管提供支持。