随着中国铁路运营里程的不断增加，铁路外部环境日益复杂，以彩钢瓦房、防尘网、塑料大棚、地膜、塑料垃圾为主的铁路外部环境隐患层出不穷，频繁引发铁路交通重大事故，已经成为铁路安全运营的重要制约因素。铁路外部环境隐患的高效监测是实现治理的重要前提，而遥感技术是目前实现大范围、低成本铁路外部环境隐患监测的最佳手段。为此，文章对光学遥感、合成孔径雷达、激光雷达、地基视频监控等4类遥感监测技术的优势、局限及应用现状进行了梳理；分析了基于人工特征和基于深度学习这两类监测识别方法的特点及不足；最后，从铁路外部环境多源遥感数据多层次融合、铁路外部环境隐患精准识别模型构建、知识引导的铁路外部环境隐患智能动态监测等方面，对基于多源遥感数据融合的铁路外部环境隐患智能监测进行了展望。

全膜脉冲电容器是脉冲功率系统的重要储能单元，其寿命影响着整个系统的可靠性。在脉冲工况下，全膜脉冲电容器的失效多为突发失效，且寿命的分散性较大。为探究全膜脉冲电容器老化失效机理，开展了其寿命试验及电场与温度场的仿真。利用LTD基本放电单元（Brick）实验腔体对电容器进行寿命测试并获得失效电容器，分析了失效电容在不同故障形式下的失效原因，并利用有限元分析软件对电容器局部“电场易畸变”区域进行了电场仿真，说明上述区域存在的畸变电场是发生绝缘介质击穿的主要原因；对电容器进行温度场分析，发现电容器温度与充放电频率成正相关，温度最高点位于电容器几何中心处附近，在充放电频率较低时，电容器温升不明显，说明在较低充放电频率下，电容器绝缘介质老化以电老化为主，而非热老化。

The terahertz (THz) wave is at the intersection between photonics and electronics in the electromagnetic spectrum. Since the vibration mode of many biomedical molecules and the weak interaction mode inside the molecules fall in the THz regime, utilizing THz radiation as a signal source to operate substance information sensing has its unique advantages. Recently, the metamaterial sensor (metasensor) has greatly enhanced the interaction between signal and substances and spectral selectivity on the subwavelength scale. However, most past review articles have demonstrated the THz metasensor in terms of their structures, applications, or materials. Until recently, with the rapid development of metasensing technologies, the molecular information has paid much more attention to the platform of THz metasensors. In this review, we comprehensively introduce the THz metasensor for detecting not only the featureless refractive index but also the vibrational/chiral molecular information of analytes. The objectives of this review are to improve metasensing specificity either by chemical material-assisted analyte capture or by physical molecular information. Later, to boost THz absorption features in a certain frequency, the resonant responses of metasensors can be tuned to the molecular vibrational modes of target molecules, while frequency multiplexing techniques are reviewed to enhance broadband THz spectroscopic fingerprints. The chiral metasensors are also summarized to specific identification chiral molecules. Finally, the potential prospects of next generation THz metasensors are discussed. Compared to featureless refractive index metasensing, the specific metasensor platforms accelerated by material modification and molecular information will lead to greater impact in the advancement of trace detection of conformational dynamics of biomolecules in practical applications.

The discharged capillary plasma channel has been extensively studied as a high-gradient particle acceleration and transmission medium. A novel measurement method of plasma channel density profiles has been employed, where the role of plasma channels guiding the advantages of lasers has shown strong appeal. Here, we have studied the high-order transverse plasma density profile distribution using a channel-guided laser, and made detailed measurements of its evolution under various parameters. The paraxial wave equation in a plasma channel with high-order density profile components is analyzed, and the approximate propagation process based on the Gaussian profile laser is obtained on this basis, which agrees well with the simulation under phase conditions. In the experiments, by measuring the integrated transverse laser intensities at the outlet of the channels, the radial quartic density profiles of the plasma channels have been obtained. By precisely synchronizing the detection laser pulses and the plasma channels at various moments, the reconstructed density profile shows an evolution from the radial quartic profile to the quasi-parabolic profile, and the high-order component is indicated as an exponential decline tendency over time. Factors affecting the evolution rate were investigated by varying the incentive source and capillary parameters. It can be found that the discharge voltages and currents are positive factors quickening the evolution, while the electron-ion heating, capillary radii and pressures are negative ones. One plausible explanation is that quartic profile contributions may be linked to plasma heating. This work helps one to understand the mechanisms of the formation, the evolutions of the guiding channel electron-density profiles and their dependences on the external controllable parameters. It provides support and reflection for physical research on discharged capillary plasma and optimizing plasma channels in various applications.