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15 February 2024 Volume 37 Issue 2
  
    Power Load Forecasting Model Based on Expansion Period
    ZHANG Haifang,HE Qinglong,ZHANG Lin
    Electronic Science and Technology. 2024, 37(2):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2024.02.001
    Abstract ( 70 )   HTML ( 9 )   PDF (756KB) ( 51 )  
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    In view of the problem that the existing power load forecasting models rely on recent data, which leads to the prediction results deviating from the real situation of the time series, a power load forecasting model based on extended period information is proposed. The pre-processed power load time series is processed according to the same time and different days. On this basis, the ARIMA(Autoregressive Integrated Maving Average Model) model and LSTM(Long Short-Term Memory Network) model are used for modeling and analysis, and three evaluation indicators are used to evaluate the predictive performance of the model. The prediction results show that the three evaluation indexes of the ARIMA model constructed by expanding the period information are lower than those of the traditional ARIMA model, and the corresponding RMSE(Root Mean Square Error), MAE(Mean Absolute Error) and MAPE(Mean Absolute Percentage Error) are 32 434.114 8, 5 828.390 9 and 0.025 2, respectively. The LSTM model of expanding the period information is also lower than the original LSTM model, and the corresponding RMSE, MAE, and MAPE are 13 520.497 4, 9 298.352 6, and 0.091 4,respectively.

    A Review and Prospect of Research on Situational Awareness Technology in Active Distribution Network
    MAN Yanlu,LIU Min,WANG Kai
    Electronic Science and Technology. 2024, 37(2):  6-13.  doi:10.16180/j.cnki.issn1007-7820.2024.02.002
    Abstract ( 47 )   HTML ( 5 )   PDF (1036KB) ( 25 )  
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    With the large-scale access of distributed generation and diversified loads, the traditional distribution network is gradually transformed into an active distribution network,which means that the types of faults in distribution networks are becoming more diverse, and the operating environment, operating conditions and topologies are becoming more and more complex. Therefore, in order to accurately predict the potential risks of the system in the active distribution network, it is necessary to improve the timeliness and accuracy of system operation decisions through sophisticated and efficient situational awareness technology.This study expounds the significance and concept of situational awareness technology in active distribution network, constructs its basic framework, latsly summarizes the research process, research difficulties and future research directions of situational awareness, situation understanding and situation prediction in detail.

    Small Object Detection Based on Convolution and Self-Attention of Aggregation
    WANG Xiaozhu,YU Lianzhi
    Electronic Science and Technology. 2024, 37(2):  14-22.  doi:10.16180/j.cnki.issn1007-7820.2024.02.003
    Abstract ( 44 )   HTML ( 9 )   PDF (2213KB) ( 28 )  
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    Small object detection is a research hotspot in most object detection open datasets. In view of the problem of insufficient detection accuracy of small targets in multi-size detection scenarios, an improved small target detection model based on YOLOv5s(You Only Look Once version 5s) is proposed in this study.A convolution self-attention aggregation residual block is added to the feature extraction network of the detector to improve the feature extraction ability, and a new feature graph is introduced from the shallow network to enhance the feature information of small object. The feature fusion network structure is improved to make full use of the newly introduced shallow features. SIOU Loss is introduced to replace the original GIOU Loss rectangular frame loss function to improve the detection accuracy and training speed.The experimental results show that the detection accuracy of the improved model is 0.012 higher than YOLOv5s on the 2007 and 2012 data sets of PASCAL VOC, and the small object detection accuracy is 0.023 higher than YOLOv5s. The detection accuracy of the imporved model in MS COCO data set is 0.001 higher than YOLOv5s, and the detection accuracy of small objects is 0.009 higher than YOLOv5s.

    Estimation and Performance Analysis of Unscented Kalman Filter with Randomly Missing Measurements
    BAI Rui,REN Zhu
    Electronic Science and Technology. 2024, 37(2):  23-29.  doi:10.16180/j.cnki.issn1007-7820.2024.02.004
    Abstract ( 30 )   HTML ( 2 )   PDF (865KB) ( 18 )  
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    In engineering applications, wireless network control systems are mostly nonlinear systems. Due to long-distance transmission and unreliable communication networks, the measured values of system sensors may be lost in the transmission process, which influences accuracy estimation and system performance. In this study, the problem of unscented Kalman filtering for a class of nonlinear discrete stochastic systems affected by correlated noise and sensor measurement loss is studied. By introducing a random variable that obeys Bernoulli distribution and has known conditional probability to describe the random sensor measurement loss, an algorithm is proposed to compensate the data. The results are verified by standard numerical software. The results show that the filter compensated by the algorithm can estimate the system well, greatly reduce the impact of sensor measurement loss on the filter performance, and increase the accuracy of estimation.

    Ozone Generation by Dielectric Barrier Discharge under Different Square Wave Pulse Modes
    JIANG Song,HE Yuanyuan
    Electronic Science and Technology. 2024, 37(2):  30-35.  doi:10.16180/j.cnki.issn1007-7820.2024.02.005
    Abstract ( 21 )   HTML ( 2 )   PDF (1897KB) ( 12 )  
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    In order to improve the concentration and output of ozone produced by dielectric barrier discharge, the characteristics of ozone produced by dielectric barrier discharge under different square wave pulse modes are studied in this study. The discharge characteristics of the system are analyzed, the discharge power of the system is calculated, and the concentration and output of ozone produced under different polarity, frequency and pulse width are studied. The results are analyzed and discussed. The results show that the ozone concentration is the highest (8.8 g·Nm-3) when positive and negative square wave pulses are applied, while the ozone yield is the highest (55 g·kWh-1) when positive square wave pulses are applied. With the increase of the frequency, the ozone concentration and production show a trend of first increasing and then decreasing. When the discharge frequency is 1 kHz, the ozone concentration is the highest, and when the discharge frequency is 1.5 kHz, the ozone production is the highest. Under the condition that other parameters are fixed, the ozone concentration increases slowly with the increase of pulse width, and the output of ozone basically remains unchanged.

    Research Status of Mid-Infrared Silicon-Based Optical Waveguides
    FENG Lulu,FENG Song,HU Xiangjian,CHEN Menglin,LIU Yong,WANG Di
    Electronic Science and Technology. 2024, 37(2):  36-45.  doi:10.16180/j.cnki.issn1007-7820.2024.02.006
    Abstract ( 37 )   HTML ( 2 )   PDF (2256KB) ( 24 )  
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    As the basic passive device in silicon photonic integrated chip, silicon-based optical waveguide is the channel for optical signal transmission. Because of its good performance and compatibility with CMOS(Complementary Metal Oxide Semiconductor) process, silicon-based optical waveguide has been widely used. Silicon photonic integrated circuits used in telecommunications and data centers have been gradually commercialized.The potential applications of mid-infrared band in free-space communication, sensing, environmental monitoring and other fields have attracted much attention from researchers in recent years.In this study, the research status of mid-infrared silicon-based optical waveguides in recent years is analyzed.The research results of waveguide material platform of SOI(Silicon on Insulator)、GOSI(Ge-on-SOI)、SOS(Si on Sapphire)、GOS(Ge-on-Si)、SGOS(SiGe-on-Si)、SON(Si-on Si3N4)、GON(Ge-on Si3N4) and manufacturing process platform of SOPS(Si on Porous Si), Pedestal, Freestanding, Suspended, LOCOS(Local Oxidation of Silicon), plasma structure are summarized. So far, the propagation loss of most monocrystalline silicon in MIR(Mid-Infrared) platform is about 0.7~3.0 dB·cm-1. The application prospects of different types of waveguides are discussed and compared, which provides a reference for the research and development, application and commercialization of mid-infrared silicon-based optical waveguides.

    Research Progress of SiGe Electro-Optical Modulator
    WANG Di,FENG Song,CHEN Menglin,LIU Yong,HU Xiangjian,FENG Lulu
    Electronic Science and Technology. 2024, 37(2):  46-54.  doi:10.16180/j.cnki.issn1007-7820.2024.02.007
    Abstract ( 28 )   HTML ( 2 )   PDF (1975KB) ( 18 )  
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    Photon modulator is the core device in the optical fiber communication system, which mainly modulates the optical signal to realize the conversion of the signal from the electrical domain to the optical domain. With the development of silicon based semiconductor technology, silicon based photonic modulator has gradually become a mainstream silicon photonic device. The realization of GHz bandwidth modulator based on silicon technology also lays a foundation for the development of silicon photonics. As a high performance optical modulator for short distance off optical interconnection, SiGe optical absorption modulator has gotten much attention. This study discusses the development status of high-performance SiGe electro-optic modulator, mainly analyzes the research progress of silicon based photonic modulator at home and abroad,and discusses the electrical modulation structures such as PIN, PN junction, which provides a way to continue to develop high-speed, low loss photonic modulator in the future.

    Sorting Method of Multi Leads ECG Based on Mutual Information
    NAN Jiao,SUN Zhanquan
    Electronic Science and Technology. 2024, 37(2):  55-60.  doi:10.16180/j.cnki.issn1007-7820.2024.02.008
    Abstract ( 28 )   HTML ( 2 )   PDF (731KB) ( 17 )  
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    The studies of automatic Electrocardiograph(ECG) classification based on convolutional neural networks all extract features from the ECG with the default 12-lead sequence, ignore the influence of lead sequence on feature extraction of convolutional network. To solve the problem, this study proposes a 2-end increasing sorting method based on mutual information, which uses mutual information to measure the correlation between leads. According to the correlation between leads and the characteristics of two-dimensional convolution, the adjacent connections of closely related leads are sorted.The experimental results show that the multi-lead ECG sorting method has achieved remarkable results on three databases and three convolutional network classification models.F1, accuracy, recall, accuracy, and Jacquard's coefficient of the proposed method increases by 0.011,0.009,0.007,0.014, and 0.013, while Hamming's loss decreases by 0.002.

    Research on Hardware in Loop Experiment Method of Direct Drive Wind Turbines Based on RTDS
    HE Puxiang,HAO Zhenghang,CHEN Zhuo,YANG Guangrao,NIE Chunfang
    Electronic Science and Technology. 2024, 37(2):  61-68.  doi:10.16180/j.cnki.issn1007-7820.2024.02.009
    Abstract ( 22 )   HTML ( 2 )   PDF (1028KB) ( 13 )  
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    In order to realize the generality of wind turbines hardware in the loop platform, a universal wind turbines hardware in the loop experiment platform is built to realize the optimal control of wind turbines. In view of the problem that direct drive wind turbines can affect the normal operation of direct drive wind turbines when the power grid voltage is unbalanced or asymmetrical, this study adopts the algorithm based on the decoupling of positive sequence current and negative sequence current to eliminate the negative sequence current and keep the constant output power. By inhibiting the double frequency fluctuation of the reactive power of the wind turbines when the fault occurs, the reference value of the active power and reactive power is 0, the amplitude of the double frequency fluctuation component of the grid reactive power is 0, and the purpose of eliminating the negative sequence current and making the output of the wind turbines stable is achieved. The simulation verification is carried out on the experimental platform. The experimental results show that the active power output of wind turbines remains unchanged and the grid-connection adaptability of wind turbines is significantly improved, which verifies the rationality and effectiveness of the method.

    Research on MHz High Voltage Pulse Power Supply
    DING Kai,RAO Junfeng
    Electronic Science and Technology. 2024, 37(2):  69-75.  doi:10.16180/j.cnki.issn1007-7820.2024.02.010
    Abstract ( 29 )   HTML ( 3 )   PDF (1597KB) ( 13 )  
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    In view of the application requirements of high frequency nanosecond pulse such as uniform discharge and biomedical, a high frequency and high voltage pulse power supply based on radio frequency Metal Oxide-Semiconductor Field Effect Transistor(MOSFET) is designed. The control signal of the pulse power supply is provided by Field Programmable Gate Array(FPGA) and transmitted through optical fiber. After amplification by the driver chip, each stage of the discharge tube is triggered synchronously. The drive chip adopts power module to provide different ground potential. The discharge tube adopts Residual Current Device(RCD) absorbing circuit to improve the instantaneous working condition at the opening and closing time. The main analysis and research is the effect of the last stage isolation inductance on the voltage waveform of discharge tube and load voltage waveform, and the Marx circuit is improved. The experimental results show that the power supply can output nanosecond pulses with rising edge of 40 ns, half-height width of 100 ns and voltage amplitude of 1.1 kV at 1 MHz repetition rate on 1 kΩ resistance load. It is verified that the power supply can work reliably in high frequency and high voltage state and meet the design requirements.

    Network Security Device Design Based on Red-Black Isolation Architecture
    GONG Zhi,LIU Chao,FU Qiang
    Electronic Science and Technology. 2024, 37(2):  76-86.  doi:10.16180/j.cnki.issn1007-7820.2024.02.011
    Abstract ( 33 )   HTML ( 3 )   PDF (3711KB) ( 15 )  
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    The data transmission of the heaven and the earth integrated network based on IP(Internet Protocol) technology is vulnerable to illegal attacks. The traditional network security device based on IPSec(Internet Protocol Security) is designed by connecting a single host to both internal and external network processing units, which has the risk of unauthorized users directly accessing the protected intranet through the extranet. A new scheme for a network security device based on a red-black isolation architecture is proposed. The scheme adopts the design concept of red-black partition and VPN technology based on IPSec framework under Linux. It implements the validity verification of the transmitted data based on the "quintuple" security and security rules and the encapsulation and decapsulation transformation of the IPSec ESP protocol in the red zone, and implements the public network sending and receiving of the ESP encapsulated and encrypted data in the black zone. In this scheme, the security service module implements dynamic switching of encryption algorithms and encryption and decryption of ESP encapsulated data according to external instructions, and uses the security service module as a data exchange channel between the red and black zones to achieve isolation between the internal and external networks and effectively ensure Intranet security.The experimental results show that the network security device based on red-black isolation architecture has the advantages of strong anti-attack capability, replaceable encryption algorithm, and encryption rate of 1 024 bytes packet length greater than 50 Mbit·s-1 under 100 megabit bandwidth.

    Classification Method of Steel Surface Defects Based on Multi-Scale Feature Fusion
    TIAN Zhixin,XU Zhen,MAO Jian,LIN Binbin,LIAO Wei
    Electronic Science and Technology. 2024, 37(2):  87-95.  doi:10.16180/j.cnki.issn1007-7820.2024.02.012
    Abstract ( 43 )   HTML ( 4 )   PDF (2470KB) ( 22 )  
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    In view of the low detection rate of steel surface defect classification, a surface defect classification method based on texture multi-scale feature fusion is adopted. Gabor filter and gray level co-occurrence matrix are used to establish multi-scale feature vectors of texture images. At the same time, convolution operation is used to extract features of texture images, and hybrid dilated convolution module is introduced to increase receptive field. The two feature vectors are fused to obtain the enhanced fused texture feature vector. The fused features are input into Long Short-Term Memory(LSTM) network in sequence to build a classification model, and the classification results are evaluated using the confusion matrix. The results show that the classification accuracy of this method on the NEU(Northeastern University) data set is 97.5%. The LSTM network, BP(Back Propagation) neural network, SVM(Support Vector Machine), KNN(K-Nearest Neighbor), CART(Classification And Regression Tree) and other classification methods are set up for comparative experiments. The results show that LSTM classification method performs best in multi-scale, and F1 index is the highest. Ablation experiments are conducted with BP network, LSTM network, SVM, KNN, CART, CNN, AlexNet and other methods to verify the universality of this method. This method fully exploits the multi-scale feature information of the texture image, and has important significance for the research of the classification method of steel surface defects.

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