Fast measurement and prediction method for electromagnetic susceptibility of receiver

Aiming at evaluating and predicting rapidly and accurately a high sensitivity receiver’s adaptability in complex electromagnetic environments,a novel testing and prediction method based on dual-channel multi-frequency is proposed to improve the traditional two-tone test.Firstly,two signal generators are used to generate signals at the radio frequency(RF)by frequency scanning,and then a rapid measurement at the intermediate frequency(IF)output port is carried out to obtain a huge amount of sample data for the subsequent analysis.Secondly,the IF output response data are modeled and analyzed to construct the linear and nonlinear response constraint equations in the frequency domain and prediction models in the power domain,which provide the theoretical criteria for interpreting and predicting electromagnetic susceptibility(EMS)of the receiver.An experiment performed on a radar receiver confirms the reliability of the method proposed in this paper.It shows that the interference of each harmonic frequency and each order to the receiver can be identified and predicted with the sensitivity model.Based on this,fast and comprehensive evaluation and prediction of the receiver’s EMS in complex environment can be efficiently realized.

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.

Advances in the research and application of high-intensity focused electromagnetic technology for fat apoptosis and body shaping

With improvements in living standards and advancements in medical technology,the demand for fat reduction and body shaping is increasing.Non-invasive fat reduction and body shaping therapy has gradually become a research hotspot in plastic surgery.High-intensity electromagnetic technology,a non-invasive treatment that can reduce subcutaneous fat and strengthen muscle,has been increasingly applied in clinics in recent years.This article reviews the fat reduction and body shaping mechanism and clinical effects of this equipment and provides a reference for its clinical application.

Research on Electromagnetic Acoustic Emission Signal Recognition Based on Local Mean Decomposition and Least Squares Support Vector Machine

Electromagnetic acoustic emission technology is one of nondestructive testing, which can be used for defect detection of metal specimens. In this study, round and cracked metal specimens, round metal specimens, and intact metal specimens were prepared. And the electromagnetic acoustic emission signals of the three specimens were collected. In addition, the local mean decomposition(LMD), Autoregressive model(AR model) and least squares support vector machine (LSSVM) algorithms were combined to identify the eletromagnetic acoustic emission signals of round and cracked, round, and intact specimens. According to the algorithm recognition results, the recognition accuracy of can reach above 97.5%, which has a higher recognition rate compared with SVM and BP neural network. The results of the study show that the algorithm is able to identify quickly and accurately crack defect in metal specimens.

Full electromagnetic transient simulation for large power systems

For building Global Energy Interconnection(GEI), it is necessary to implement new breakthroughs on largepower system simulation. Key routes for implementing full electromagnetic transient simulation of large-power systems are described in this paper, and a top framework is designed. A combination of the new large time step algorithm and the traditional small-time step algorithm is proposed where both parts A and B are calculated independently. The method for integrating the Norton equivalence of the power electronic system to the entire power grid is proposed. A two-level gird division structure is proposed, which executes a multi-rate parallel calculation among subsystems and element parallel calculation in each subsystem. The initialization method of combining load flow derivation and automatic trial-and-error launching is introduced. The feasibility of the method is demonstrated through a practical power grid example, which lays a foundation for further research.

Design and fabrication of a bistable electromagnetic microactuator

An electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The cantilever beam has two stable positions due to the use of permanent magnets. With electromagnetic actuation arising from the planar coils, the cantilever beam will switch from one stable position to the other. Mechanical and magnetic analysis are carried out on the actuator, and the device with a size of 2.2 mm × 2.5 mm is fabricated with the UV-LIGA technology. The test results show that a current pulse with an amplitude of 70 mA is needed for actuator＇ s switching between the two stable states, and the switching time is no more than 6 ms. Displacement of the end of cantilever is about 15 μm.

Electromagnetic Response Studies of the Antenna for Deep Water Deep Target CSEM Environments

The Controlled Source Electromagnetic Method (CSEM) is used for offshore hydrocarbon exploration. Hydrocarbon detection in seabed logging (SBL) is a very challenging task for deep hydrocarbon reservoirs. The electromagnetic field response of an antenna is unable to detect deep hydrocarbon reservoirs due to a weak electromagnetic signal response in the seabed logging environment. This work premise deals with the comparison of the electromagnetic signal strength of a new antenna with a straight antenna and the orientation of an antenna for deep target hydrocarbon exploration. Antenna position and orientation (Tx and Ty) was studied using Computer Simulation Technology software (CST) for deep targets in marine CSEM environments. The model area was assigned as (40 ′ 40 km) to replicate the real seabed environment. From the results, the new dipole antenna shows an 804% and 278% increase in electric and magnetic field strength than the straight antenna. An electric (E) and magnetic (H) field component study was done with and without the presence of a hydrocarbon reservoir. Ex and Hz field component responses with the new antenna at the1 kmtarget were measured in a deep water environment. It was analyzed that the antenna shows 53.10% (Ex) and 83.13% (Hz) field difference in deep water with and without a hydrocarbon reservoir at the30 mantenna position from the sea floor. From the antenna orientation results, it was observed that, the electric field Ex and magnetic field Hz responses decreased from 18% to 12% and 21% to 16%, respectively but was still able to detect the deep target hydrocarbon reservoir at the4 kmtarget depth. This EM antenna may open new frontiers for the oil and gas industry for deep target hydrocarbon detection (HC).

Vacuum Switching Technology for Future of Power Systems

Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum is an eco-friendly technology compared to switching in SF 6 gas,which is the strongest greenhouse gas according to the Kyoto Protocol.Vacuum,an eco-friendly natural medium,is promising for reducing the usage of SF 6 gas in current switching in transmission voltage.Second,switching in vacuum achieves faster current interruption than existing alternating current(AC)switching technolo-gies.A vacuum circuit breaker(VCB)that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption,which can interrupt a short-circuit current in the first half-cycle of a fault current,compared to the more common three cycles for existing current switching technologies.This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults,especially for ultra-and extra-high-voltage power transmission lines.Third,based on fast vacuum switching technology,various brilliant applications emerge,which are benefiting the power systems.They include the applications in the fields of direct current(DC)circuit breakers(CBs),fault current lim-iting,power quality improvement,generator CBs,and so forth.Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times.With this controlled switching,vacuum switching technology may change the“gene”of power systems,by which power switching transients will become smoother.

Electromagnetic Transmission Characteristics of Y-Shaped and Y-Ring-Shaped Frequency Selective Fabrics

Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space method. The test results of representative samples show that the resonance frequencies and the resonance peak or valley values in two polarization modes are not completely identical but the differentials are small, indicating that the influences of polarization modes are not significant. The transmission coefficient curves of Y-shaped and Y-ring-shaped FSFs with various size parameters are obviously different. For instance, as the unit size D increases by 4.0 mm, the resonance frequencies of patch FSFs decrease by 1.92 GHz and the resonance valleys increase by 12.32 dB. Different size parameters have dissimilar effects on the transmission characteristics and the corresponding influence laws should be analyzed concretely. The work could provide reference for the structural design and characteristics analysis of other FSFs.

An electromagnetic wave attenuation superposition structure for thin-layer plasma

This work proposes a new plasma super-phase gradient metasurfaces(PS-PGMs)structure,owing to the limitations of the thin-layer plasma for electromagnetic wave attenuation.Based on the cross-shaped surface unit configuration,we have designed the X-band absorbing structure through the dispersion control method.By setting up the Drude dispersion model in the computer simulation technology,the designed phase gradient metasurfaces structure is superposed over the plasma,and the PS-PGMs structure is constructed.The electromagnetic scattering characteristics of the new structure have been simulated,and the reflectance measurement has been carried out to verify the absorbing effect.The results demonstrate that the attenuation effect of the new structure is superior to that of the pure plasma structure,which invokes an improved attenuation effect from the thin layer plasma,thus enhancing the feasibility of applying the plasma stealth technology to the local stealth of the strong scattering part of a combat aircraft.

Hip Joint Pain Caused by Electromagnetic Waves Following an Operation for a Complex Humerus Fracture

This case report illustrates hip joint pain caused by electromagnetic waves following an operation for a complex humerus fracture. The subject was a 22-year-old woman. The patient complained of pain in her left hip joint and discomfort, particularly while walking. The subject suffered a fracture in her left upper arm in a traffic accident approximately 3 months previously. She underwent an operation wherein seven titanium bolts were used to fix the humerus. The operation was deemed successful and the prognosis of the operation was also good;however, approximately 3 months after the operation, she developed pain and discomfort in her left hip joint, particularly while walking. Symptoms were improved by covering the surgical field with aluminum foil, blocking electromagnetic waves. Electromagnetic waves attracted by the titanium bolts may have induced pain.

Electromagnetic System Design and Visual Simulation

An electromagnet design system is developed using Visual C++ language and OpenGL technology to visualize parametric 3D model. The system consists of primary design, optimization design, dynamic and static characteristics, and visual simulation. All empirical parameters and curves used in design process are stored in database. Through human-computer interactions, an electromagnetic system can be designed conveniently with the results and characteristics curves displayed in graphic model. Using this system can greatly shorten the process of product design, and the results satisfy technical requirements.

准噶尔盆地盆1井西凹陷石炭系火山岩凝析气藏的发现与勘探启示

准噶尔盆地石炭系火山岩油气藏是油气勘探的重点领域之一。根据录测井资料、地球化学分析数据及岩石薄片鉴定资料,结合地球物理方法,厘清了准噶尔盆地盆1井西凹陷石炭系火山岩油气成藏的主控因素,总结出深层火山岩气藏富集规律,明确了有利勘探方向。研究结果表明:(1)准噶尔盆地盆1井西凹陷风城组烃源岩厚度为100~300 m,面积约为5 400 km2,整体进入生凝析油—干气阶段,生气强度大于20×108m3/km2,为凹陷提供了丰富的天然气源。(2)研究区石炭系火山岩岩性复杂,爆发作用形成的安山质火山角砾岩受到风化淋滤作用,可形成物性较好的风化壳型储层。石炭系—二叠系大型不整合面和广泛发育的深大断裂是重要的输导体系,二叠系上乌尔禾组泥岩作为区域盖层,为凝析气成藏提供了保存条件,油藏主要分布在高部位,气藏分布于低部位。(3)通过“两宽一高”(宽方位、宽频带、高密度)技术,提高地震成像精度,联合时-频电磁技术(TFEM),实现了石炭系火山岩的精细刻画,为深层油气藏的勘探提供了有力支撑。石西16井的重大突破,证实了盆1井西凹陷石炭系火山岩具有巨大的勘探潜力。

电磁超表面全息成像技术研究进展

超表面全息术的出现极大地促进了全息成像技术的发展,同时也拓展了电磁超表面的应用范围。为进一步梳理超表面全息成像的发展脉络,以技术发展的时间轴为主线,系统地回顾了超表面技术的发展历程,以及受益于超表面技术的全息成像模式的进步。随着技术的进步,超表面全息术逐渐从可见光频段向微波频段发展,从静态重现向动态全息演变,因此,着重介绍了超表面全息术的未来方向——可重构超表面及其动态全息技术,并且从超表面单元高性能创新技术、超表面阵列全息模式以及超表面全息系统研究3个方面对可重构超表面全息术的发展做了展望。

航天返回舱雷达探测技术研究

雷达在探测航天返回舱黑障区时,因受到等离子体鞘套干扰,长期存在跟踪不稳定甚至丢失等问题。本文从等离子体鞘套与电磁波相互作用机理出发,提出了航天返回舱黑障区电磁特性仿真方法和再入场景回波仿真方法;结合仿真与实测数据研究获取黑障区目标回波特征,提出了基于鞘套快时变特性的目标检测方法;设计了返回舱黑障区认知探测流程,将其应用于多频段雷达装备成功完成了多次返回舱探测任务,保障了黑障区稳定跟踪,基本解决了航天返回舱黑障区雷达探测问题。

产教融合背景下电磁法水力压裂裂缝监测实验平台建设

水力压裂是油田提高勘探开发效率的核心技术之一,电磁监测是评估水力压裂效果的有效测量手段。该文升级改造了传统裂缝监测装置,搭建了基于电磁法的水力压裂裂缝在线监测实验教学平台,平台包含多种裂缝模型,且能合理设计各裂缝模型参数,以油田现场压裂裂缝监测问题为导向,灵活优化组合裂缝模型,使用COMSOL数值模拟及可视化方法,在实验室探索压裂裂缝参数与电磁监测信号间的规律,为反演有效裂缝参数提供理论依据。该实验项目具有前沿性、学术研究性和应用性选题特点,可以提升学生自主创新能力和实践探究能力。

雷达波形对抗技术发展预见

随着雷达、电子侦察等传感器技术的进步,对电磁空间的操控从能量、频率向更高维度的波形发展,雷达波形对抗应运而生。阐述雷达波形对抗技术产生的背景、概念内涵和发展现状,同时提出可利用博弈思维建立雷达波形“OODA”回路,通过对雷达波形进行伪装、扰乱和利用以达成制造战场迷雾、创造新质杀伤链的效果。此外,介绍实现雷达波形对抗的波形隐匿、波形重建与利用、波形捷变反侦察等关键技术及原理。从波形管控等3个方面提出雷达波形对抗制胜电磁空间的发展建议。

电磁层析成像技术中的谱参数混合共轭梯度法

电磁层析成像技术是基于电磁感应原理的过程检测技术,图像重建是解决其反问题的关键.基于共轭梯度算法,修正搜索方向和迭代参数,推导出基于谱参数的混合共轭梯度算法,以提高图像重建质量和收敛性.介绍了电磁层析成像系统的实验室模型和灵敏度分布矩阵,作为反问题基础;对搜索方向进行修正,提出一个新的谱参数,用来控制新旧搜索方向之间的角度,根据每一步迭代的残差结果,寻找最优解;改善共轭参数,分析非线性共轭梯度算法中FR算法(fletcher-reeves method)和PRP算法(polak-ribiere-polyak method)的各自优势,将它们按照一定比例进行混合,得到一种新的混合共轭梯度算法;将谱参数混合共轭梯算法应用到电磁层析成像实验室系统中,构建了3种典型实验室模型,对比谱参数混合共轭梯度算法与传统算法并作出评价.实验结果表明:谱参数混合共轭梯度算法的重建图像的质量更高,具有较好的数值表现;混合共轭梯度算法结合了FR算法和PRP算法的优点,收敛速度比PRP算法快,成像质量比其他算法高.

基于里德堡原子的无线电技术研究进展

近年来,量子信息技术飞速发展,其中基于里德堡原子的电磁传感器吸引了人们的极大兴趣。里德堡原子是一种处于高能态的原子,因其拥有对外场响应灵敏、具备自校准并直接追溯到国际单位制的测量能力、不受传统天线尺寸效应的影响等特点,十分适合于无线电传感与探测。自2012年Shaffer等突破性地利用里德堡原子的电磁诱导透明效应测量微波电场强度的灵敏度及不确定度均远高于传统微波测量结果之后,近十年来,以里德堡原子超外差测量等新理论和新技术为代表的研究已经实现了对电磁波的频率、极化、相位、强度等多参数的测量,相关工程化的技术也蓬勃发展,有望对传统的无线电技术产生颠覆性的影响。对基于里德堡原子的无线电技术近十年来的研究进展进行综述,从探测原理出发,梳理本领域的发展脉络,并对其未来发展趋势进行展望。