Reflection on methodology of the correlation between electromagnetic interference and safety in high-speed railway

Purpose – In the continuous development of high-speed railways, ensuring the safety of the operation controlsystem is crucial. Electromagnetic interference (EMI) faults in signaling equipment may cause transportationinterruptions, delays and even threaten the safety of train operations. Exploring the impact of disturbances onsignaling equipment and establishing evaluation methods for the correlation between EMI and safety isurgently needed.Design/methodology/approach – This paper elaborates on the necessity and significance of studying theimpact of EMI as an unavoidable and widespread risk factor in the external environment of high-speed railwayoperations and continuous development. The current status of research methods and achievements from theperspectives of standard systems, reliability analysis and safety assessment are examined layer by layer.Additionally, it provides prospects for innovative ideas for exploring the quantitative correlation between EMIand signaling safety.Findings – Despite certain innovative achievements in both domestic and international standard systems andrelated research for ensuring and evaluating railway signaling safety, there’s a lack of quantitative and strategic research on the degradation of safety performance in signaling equipment due to EMI. A quantitativecorrelation between EMI and safety has yet to be established. On this basis, this paper proposes considerationsfor research methods pertaining to the correlation between EMI and safety.Originality/value – This paper overviews a series of methods and outcomes derived from domestic andinternational studies regarding railway signaling safety, encompassing standard systems, reliability analysisand safety assessment. Recognizing the necessity for quantitatively describing and predicting the impact ofEMI on high-speed railway signaling safety, an innovative approach using risk assessment techniques as abridge to establish the correlation between EMI and signaling safety is proposed.

Design of high-speed signal acquisition system and analysis of signal integrity

The device is used for the test on the fuze detonating time according to the initial velocity of the projectile and the altitude and speed of enemy aircraft flight. For the special requirements of the high-speed signal acquisition in the process, the characteristics of the measured signal are analyzed. The system is investigated in chip selection, signal transmission, signal processing, signal storage, post-production PCB design, etc. The appropriate measures and solutions which affect the integrity and accuracy of the signal in each process are proposed. The rules for the layout of the device and wiring are made. The result show that the measurement values are accurate without loss of data.

Wing buzzing as a mechanism for generating vibrational signals in psyllids (Hemiptera: Psylloidea)

Psyllids,or jumping plant lice(Hemiptera:Sternorrhyncha:Psylloidea),are a group of small phytophagous insects that include some important pests of crops world-wide.Sexual communication of psyllids occurs via vibrations transmitted through host plants,which play an important role in mate recognition and localization.The signals are species-specific and can be used to aid in psyllid taxonomy and pest control.Sev-eral hypotheses have been proposed for the mechanism that generates these vibrations,of which stridulation,that is,friction between parts of the forewing and thorax,has re-ceived the most attention.We have investigated vibrational communication in the Euro-pean pear psyllid species Cacopsylla pyrisuga(Foerster,1848)using laser vibrometry and high-speed video recording,to directly observe the movements associated with signal pro-duction.We describe for the first time the basic characteristics of the signals and signal emission of this species.Based on observations and analysis of the video recordings us-ing a point-tracking algorithm,and their comparison with laser vibrometer recordings,we argue that males of C.pyrisuga produce the vibrations primarily by wing buzzing,that is,tremulation that does not involve friction between the wings and thorax.Comparing observed signal properties with previously published data,we predict that wing buzzing is the main mechanism of signal production in all vibrating psyllids.

Forecasting wind speed using a reinforcement learning hybrid ensemble model:a high-speed railways strong wind signal prediction study in Xinjiang,China

Considering the application of wind-forecasting technology along the railway,it becomes an effective means to reduce the risk of tain more reliable wind-speed prediction results,this study proposes an intelligent ensemble forecasting method for strong winds train derailment and overturning.Accurate prediction of crosswinds can provide scientific guidance for safe train operation.To obalong the high-speed railway.The method consists of three parts:the data preprocessing module,the hybrid prediction module and original wind speed data.Then,Broyden-Fletcher-Goldfarb-Shanno(BFGS)method,non-linear autoregressive network with exoge-the reinforcement learing ensemble module.First,fast ensemble empirical model decomposition(FEEMD)is used to process the prediction models for all the sublayers of decomposition.Finally,Q-learning is utilized to iteratively calculate the combined weights nous inputs(NARX)and deep belief network(DBN),three benchmark predictors with different characteristics are employed to build of the three models,and the prediction results of each sublayer are superimposed to obtain the model output.The real wind speed data of two railway stations in Xinjiang are used for experimental comparison.Experiments show that compared with the single benchmark model,the hybrid ensemble model has better accumacy and robustness for wind speed prediction along the railway.The 1-step forecasting results mean absolute error(MAE),mean absolute percentage error(MAPE)and root mean square error(RMSE)of Q-leaming-FEEMD-BFGS-NARX-DBN in site #1 and site #2 are 0.0894 m/s,0.6509%,0.1146 m/s,and 0.0458 m/s.0.2709%,0.0616 m/s.respectively.The proposed ensemble model is a promising method for railway wind speed prediction.

Network Sorting Algorithm of Multi-Frequency Signal with Adaptive SNR

An signal noise ratio（ SNR） adaptive sorting algorithm using the time-frequency（ TF）sparsity of frequency-hopping（ FH） signal is proposed in this paper. Firstly,the Gabor transformation is used as TF transformation in the system and a sorting model is established under undetermined condition; then the SNR adaptive pivot threshold setting method is used to find the TF single source. The mixed matrix is estimated according to the TF matrix of single source. Lastly,signal sorting is realized through improved subspace projection combined with relative power deviation of source. Theoretical analysis and simulation results showthat this algorithm has good effectiveness and performance.

Research on Multi-System Ultra-High Speed Optical Signal Access System

In view of the small transmission capacity and single signal modulation format of the existing optical transmission system, this paper proposes an ultra-high-speed optical signal access scheme based on NEL0670, which can realize the transmission of 100 G DP-QPSK, 200 G DP-16QAM and 400 G DP-16QAM signals, and realize flexible and intelligent reception of multi-system optical signals.

Wideband signal detection based on high-speed photonic analog-to-digital converter

This Letter demonstrates the effectiveness of a high-speed high-resolution photonic analog-to-digital converter （PADC） for wideband signal detection. The PADC system is seeded by a high-speed actively mode locked laser, and the sampling rate is multiplied via a time-wavelength interleaving scheme. According to the laboratory test, an X-band linear frequency modulation signal is detected and digitized by the PADC system. The channel mismatch effect in wideband signal detection is compensated via an algorithm based on a short-time Fourier transform. Consequently, the signal-to-distortion ratio （SDR） of the wideband signal detection is enhanced to the comparable SDR of the single-tone signal detection.

Signal waveform design to detect an underwater high-speed small target

The problem of sonar signal waveform design to detect a high-speed small target in an underwater environment is discussed. From theoretical analysis, time-frequency hop signal is regarded as the most suitable signal waveform in this application. To get precise target parameter estimation ability, the signal should have high range-Doppler resolution performance. The results of signal analysis show that hop signal with frequency serial coding as Costas array has sharp ambiguity characteristic, so it can be used in an active sonar system to detect a high speed small target. A scheme of frequency coding is also presented.

Development of readout electronics for bunch arrival-time monitor system at SXFEL

A bunch arrival-time monitor(BAM) system,based on electro-optical intensity modulation scheme, is under study at Shanghai Soft X-ray Free Electron Laser.The aim of the study is to achieve high-precision time measurement for minimizing bunch fluctuations. A readout electronics is developed to fulfill the requirements of the BAM system. The readout electronics is mainly composed of a signal conditioning circuit, field-programmable gate array(FPGA), mezzanine card(FMC150), and powerful FPGA carrier board. The signal conditioning circuit converts the laser pulses into electrical pulse signals using a photodiode. Thereafter, it performs splitting and low-noise amplification to achieve the best voltage sampling performance of the dual-channel analog-to-digital converter(ADC) in FMC150. The FMC150 ADC daughter card includes a 14-bit 250 Msps dual-channel high-speed ADC,a clock configuration, and a management module. The powerful FPGA carrier board is a commercial high-performance Xilinx Kintex-7 FPGA evaluation board. To achieve clock and data alignment for ADC data capture at a high sampling rate, we used ISERDES, IDELAY, and dedicated carry-in resources in the Kintex-7 FPGA. This paper presents a detailed development of the readout electronics in the BAM system and its performance.

Molten pool and temperature field in CO_2 laser welding

Two measuring methods, high-speed camera and optical monitoring system, were used to study processes of laser welding. Molten pool, cooling time and temperature field were analyzed based on real measured images and optical signal data. The results show that the width of molten pool is almost equal to the width of weld, and length is about 7. 8 mm. The solidification time is about 0. 5 s and the temperature gradient is great, so HAZ is very small. The method and results will be of benefit to build the relationship between welding parameters and microstructure.

Impact of China’s high speed train window glass on GNSS signals and positioning performance

High speed train(HST)is an excellent platform to perform ultra-high spatial and temporal resolution observations of atmosphere using global navigation satellite systems(GNSS).However,we find that signal attenuation caused by HST window glass is a major barrier for HST-based GNSS applications inside HST chambers.A field experiment is conducted to analyze the effect of HST glass on GNSS signal propagation.In the experiment,GNSS observations are collected and analyzed from a receiver covered with an HST window glass and one with an open-sky view.The size of the HST window glass is 670 mm×720 mm,with a thickness of 34 mm.The window glass is a double-glazing glass in which each layer has an actual thickness of 6 mm,and the two layers are separated by an air gap of 22 mm.The experiment results indicate that HST window glass can cause significant degradation to GNSS signals and even loss of tracking of the signal.Based on statistical results,HST window glass causes 39%,56%,49%,and 59%loss in GPS,GLONASS,Galileo,and BDS signals,respectively.Additionally,up to 20 dB-Hz of carrier-to-noise ratio(C/N0)degradation is also observed in the remaining observations.The significant signal attenuation and loss further lead to the decrease in the number of tracked satellites and occurrence of more cycle slips.The results of the study indicate that 44-230 cycle slips are detected for the HST glass-covered receiver whereas the receiver without glass does not exhibit more than 16 cycle slips.Additionally,the number of GNSS satellites tracked by the HST glass-covered receiver is reduced by 65%owing to the loss of signal.Furthermore,GNSS positioning performances from two receivers are also tested.With respect to GPS+GLONASS static precise point positioning(PPP),HST glass causes a degradation of 1.516 m and 1.159 m in the single-frequency and dual-frequency three-dimensional positioning accuracy,respectively.With respect to the GPS+GLONASS kinematic PPP,the accuracy degradations for single-frequency and dual-frequency kinematic PPP are 2.670 m and 4.821 m,respectively.

L_x频段高速跳频频率合成器

Ｌ_ｘ频段高速跳频频率合成器主研人员：李少谦冯晓东程国辉洪福明杨毅生葛运坤舒力林精波达到的战术指标！ｏｉ＄：１３３８～１５７５Ｍｉｌｋ；③脚濒点间隔：３－－；频率切换时间：＜ｓｗ；相位噪声：＜一９０ｄＢｃ／ｌ（ｌｌ处；ｎｇ：＜一６０ｄＢ，－－－－－ｘ...

Single-photon microwave photonics

With the rapid development of microwave photonics technology, high-speed processing and ultra-weak signal detection capability have become the main bottlenecks in many applications. Thanks to the ultraweak signal detection capability and the extremely low timing jitter properties of single-photon detectors, the combination of single-photon detection and classical microwave photonics technology may provide a solution to break the above bottlenecks. In this paper, we first report a novel concept of singlephoton microwave photonics(SP-MWP), a SP-MWP signal processing system with phase shifting and frequency filtering functionalities is demonstrated based on a superconducting nanowire single photon detector(SNSPD) and a successive time-correlated single photon counting(TCSPC) module.Experimental results show that an ultrahigh optical sensitivity down to-100 d Bm has been achieved,and the signal processing bandwidth is only limited by the timing jitter of single-photon detectors. In the meantime, the proposed system demonstrates an ultrahigh anti-interference capability, only the signal which is phase locked by the trigger signal in TCSPC can be extracted from the detected signals combining with noise and strong interference. The proposed SP-MWP concept paves a way to a novel interdisciplinary field of microwave photonics and quantum mechanism, named by quantum microwave photonics.

Principle and applications of semiconductor optical amplifiers-based turbo-switches

All-optical effectively increase the semiconductor optical recovery time or the high-speed turbo-switches can switching speed using cascaded amplifiers （SOAs）. The overall bandwidth of turbo-switch was numerically analyzed with time-domain and frequency-domain SOA models. The turbo-switch was explored from the fundamental carrier dynamics in SOAs for the purpose of further increasing its operation speed. An integrated turbo-switch was also been proposed and demonstrated, where a phase adjustable Mach-Zehnder interferometer （MZI） was applied as an optical band-pass filter between SOAs. Wavelength conversion was first demonstrated at 84.8 Gbit/s using the integrated turbo-switch.