bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep Learning based Pavement Crack Detection System
Authors: Yu Lingjun , Li Qi
Published: August 2023

The pavement crack causes the highway service life to shorten, the safety hidden danger to increase. The low efficiency and high cost of manual inspection makes it difficult to detect pavement cracks. This paper proposes a fast and efficient deep learning pavement crack detection system. CRACK2000, an image segmentation dataset with complex interference background and multiple crack types, is constructed based on perspective transformation and image cropping. The scheme corrects the pavement crack images by perspective transformation. The extraction of pavement crack depth features is completed by applying the U-Net network. Finally, the pavement condition index PCI (pavement condition index) is calculated by quantifying the different types of crack information based on the segmentation results. The experimental results show that the Precision, Recall, F1-score and AUC of the U-Net network are 76.67%, 72.32%, 74.43% and 99.46% respectively. The AUC values reflect that the method is more capable of filtering out complex background interference from cracked images. The automatic pavement crack detection system designed in this paper can accurately locate and classify the location and category of pavement cracks, and perform quantitative pavement evaluation to obtain the pavement deterioration of the road section and the corresponding repair recommendations, enhancing the practicality of pavement crack detection.
TOFD Defect Image Recognition Based on YOLOv7
Authors: Fan Xiongfang , Tan Jiawan , Zhang Jianfeng , Gong Yanfeng , Zhang Hairui , Huang Chunsen , Chen Junlong
Published: August 2023

Welding technology is an important link in shipbuilding, and ultrasonic diffraction time difference method is one of its important inspection means, but the identification of its TOFD image still mainly relies on manual evaluation. In this paper, in order to solve the problems of low accuracy and unbalanced categories of defect recognition in the existing automatic identification research, by reclassifying defects into primary defects, secondary defects, and tertiary defects according to the degree of harm to the weld, and constituting a TOFD image dataset containing 934 images, and then using the YOLOv7 model, by adding mixup enhancement combined with mosaic enhancement, the The mAP value of the improved YOLOv7 model was improved by about 42% to 93.41% compared with the original model, and the AP0.5 values of the YOLOv7 improved model for primary defects, secondary defects, and tertiary defects were improved by about 30%, 38%, and 58% compared with the original model, respectively, by introducing the CBAM attention mechanism method to optimize the problems of insufficient data sample size and the imbalance between foreground and background; the AP 0.75 values improved by about 16%, 30%, and 45%, respectively, compared with the original model; its detection speed was 7.8 sheets per second.
A Comparative Study of Contrastive Learning-Based Few-Shot Unsupervised Algorithms for Efficient Deep Learning
Authors: Zhu Yancheng , Wu Qiwei , Liu Jianzi
Published: August 2023

The rapid development in computer vision algorithms, particularly in target detection algorithms based on deep neural networks, has led to significant advancements in various fields. However, recent research on target detection algorithms has shifted towards small sample scenarios with long-tailed distribution of categories, where achieving high accuracy target detection with limited data has become a crucial research topic. Deep neural networks often face several challenges when dealing with limited data, including convergence problems, overfitting, and poor generalization performance. In such scenarios, categories with little data are easily overwhelmed by the negative gradients generated by other categories during network training, which affects the final detection results. To address this issue, an unsupervised contrast learning algorithm has been proposed that can achieve accurate results on a small number of reference datasets without requiring a large number of datasets. One recently proposed contrast learning algorithm is PixelCL, which combines information from image depth in pretraining to improve results. The results of this algorithm show that it can obtain more accurate results through contrast learning with limited sample data. These findings highlight the potential of contrast learning algorithms in addressing negative gradient issues and improving the performance of deep neural networks in target detection tasks with limited data.
Improving Tibetan End-To-End Speech Recognition with Transfer Learning
Authors: Li Yunpeng , Zhang Qinya , Li Guanyu
Published: August 2023

End-to-end architecture has shown outstanding performance in the field of speech recognition, but achieving such performance typically requires a large amount of annotated data. In languages with sufficient corpus and resources, satisfactory recognition results have been achieved. However, for some low-resource data with insufficient training data, the lack of training data remains a bottleneck in building speech recognition systems. This paper presents an approach that utilizes self-supervised feature extraction and transfer learning to enhance the performance of acoustic models in low-resource languages. The proposed strategy involves retraining the fundamental acoustic model, originally trained on resource-rich languages, using a limited amount of low-resource speech data within an end-to-end architecture. By doing so, it aims to construct an improved acoustic model tailored for low-resource languages. The results of the model in the Tibetan language dataset show significant improvement, with a relative decrease of 26% in word error rate from 13.8% to 10.2% on the test set.
On UV Photon Distribution of Discharge in GIS Busbar Based on Ray Tracing
Authors: Shao Mingxin , Du Fei , Yuan Shuai , Bi Jiangang , Xu Yuan
Published: August 2023

In order to clarify the distribution law of the ultraviolet photon field in gas insulated switchgear busbar, meanwhile to correct the detection range of the ultraviolet sensor, the optical model of the gas insulated switchgear busbar based on the uniform theory of diffraction is proposed based on ray tracing. the distributions of the radiation ultraviolet fields are calculated when partial discharge occurs at the key positions such as basin insulator and conductor. Based on the average irradiance, maximum irradiance, and attenuation characteristics, the distribution law in the busbar is further analyzed, which provides a new method to confirm the location of ultraviolet sensors.
Simulation study of DBD discharge characteristics and active particle-assisted methane combustion
Authors: Zhao Zhibo , Song Peng , Su Jing
Published: August 2023

This paper established a model of the coaxial dielectric barrier discharge (DBD). Ar-CH4 is fed into the mixture as a working gas. Using 10.0 kHz as power research in different voltage and dielectric materials and medium thickness has influences on producing active particle mole fraction. The simulation results show that when the voltage increase, the molar concentration of O3 and H energetic particles increase obviously. When the thickness of the medium increases, the molar concentration of O3 and H decreases. When the dielectric constant of the dielectric material increases, the molar concentration of O3 and H also increases. The molar concentration of OH active particles also changed, but the law was unclear. At the same time, when the discharge voltage is 15 kV, the dielectric thickness is 2 mm, the dielectric constant is 3.75, and the DBD discharge is uniform and stable, the molar concentration of O3 and H is 0.069% and 0.056% respectively. The corresponding concentrations of O3 and H active particles were introduced into the established methane combustion reaction model. The study found that the joining of O3 and H energetic particles make the reaction begin to move significantly ahead of time. That has a promoting effect on the rate of the methane combustion reaction. In the methane combustion reaction model with different equivalence ratios, O3 with a molar concentration of 0.069% and H with a molar concentration of 0.056% introduced, it is concluded that these two active particles also have a tremendous promoting effect on the expansion of the thin burning limit of methane.
Transformer Oil Temperature Variation Based on Terahertz Time-domain Spectroscopy
Authors: Luo Guofang , Wei Xiaochuan , Liu Ping’an , Li Wenping , Li Yingze , Zhang Zhixiang , Zhou Kuan , Shao Zuoshan , Wang Dong
Published: August 2023

The transmission terahertz time-domain spectroscopy system is used to measure the transformer oil terahertz spectrum at different temperatures, the time and frequency domain, time delay, and refractive information of transformer oil with different temperatures are tested. The terahertz wave of the time-domain delay of transformer oil at different temperatures is obtained, the variation of time-domain delay and refractive index with different temperatures in the terahertz band were calculated and the linear variation trend was fitted.
The characteristics of positive corona discharge at different altitudes
Authors: Liu Jiqiu , Wei Hongyu , Lv Duo , He Wangling , Wang Yanzhao , Wan Baoquan , Gan Zheyuan , Zhou Yang
Published: August 2023

With the vigorous growth of UHV transmission projects, transmission lines crossing high-altitude areas are inevitable, and the degree of corona discharge in high-altitude areas is more intense. The electromagnetic environmental problems caused by corona discharge have gradually become one of the key technical problems restricting UHV transmission in high-altitude areas. To investigate how height affects the positive polarity corona’s corona characteristics, using the movable small corona cage to carry out experiments at four altitude points in the range of 1120 m–4320 m, and measures the corona current pulse and radio interference level of 0.8 mm diameter fine copper wire under different positive voltages. Several conclusions can be drawn from the data analysis, including the following: The average current pulse amplitude grows with altitude, first before decreasing, and the current pulse repetition frequency rises along with altitude. The major conclusions of this essay can serve as a starting point for the study of the corona effect.
Research On Multi-source Collaborative Distribution Network Fault Recovery Technology
Authors: Liu Huaxia , Xu Yan
Published: August 2023

When a power outage occurs in the power system, multiple distributed power sources and energy storage systems connected to the distribution network can be coordinated to restore power to important lost loads in a priority and fast manner. However, the generation output of intermittent power sources such as wind and photovoltaic is uncertain, which makes it difficult to provide a continuous and stable power supply to the loads in isolated islands. In this paper, we first explore the improvement effect of multi-source cooperative fault recovery on distribution system resilience, consider the distribution system with distributed power sources, energy storage systems, and controllable loads, and propose a distribution system recovery model with the goal of maximizing the power consumption of the restored loads for a relatively short period of time after a power outage incident. Then, the power output characteristics and power supply capacity of various distributed power sources are analyzed, and the intermittent power output fluctuations are compensated using controllable loads. Finally, the proposed model and method are validated using a modified IEEE 33-node distribution network as an example.
Voltage Management of Distributed Photovoltaic Cluster Connected to a Distribution Network
Authors: Yang Shuangshuang , Zhang Ganghong , Gao Jian , Yuan Jianan
Published: August 2023

The proportion of distributed photovoltaic grid connection in the distribution network is gradually increasing, and its characteristics of high volatility and poor stability have brought new challenges to the overvoltage problem faced by the distribution network structure and safe and stable optimization operation. This paper mainly studies clustering and reactive power optimization control of distributed Photovoltaic. The system architecture of the cloud edge is constructed, and the voltage autonomy strategy within the region after partition is proposed. The model is established with the total voltage offset and the minimum line loss as targets. Adopting adaptive PSO-BP algorithm model for optimization solution. Finally, conduct simulation analysis on the MATLAB platform. We can see that the proposed method can not only reduce the uneven voltage distribution, network loss, but also reduce the calculation burden of the controller has a positive effect.
Phase-angle adaptive current differential protection for active distribution network
Authors: Ni Pinghao , Cao Hao , He Jinghan , Li Meng , Gao Fengxi , Wang Ziqi
Published: August 2023

With the distributed generator to be attached to the distribution network, the current differential protection scheme may have some problems, resulting in maloperation or rejection of protection. This paper investigates the current distribution properties of an active distribution network with branches of undetected load and draws the conclusion that undetected load may cause differential protection maloperation. The differences in fault properties of differential protection in transmission network scenarios and distribution networks containing distributed generator are evaluated, leading to the conclusion that differential protection applied to active distribution networks may have reduced resistance to transition resistance and that poor signal synchronization conditions in distribution networks may lead to larger synchronization errors. A phase-angle adaptive current differential protection is proposed. It adaptively adjusts the phase angle constraint using the magnitude of the power frequency full current component proportion at both sides of the line. It can accommodate the protection needs of various operation modes of distribution networks containing distributed generator, and has the characteristics of strong resistance to transition resistance and strong phase shift braking ability. The correctness of the suggested protection scheme was verified using the PSCAD platform.
Simulation-based Multi-unit Collaborative Optimization in Data Centers
Authors: Liu Zhiqiu , Song Jiaqi , Li Rui
Published: August 2023

With the rapid development of information technology in China, the problem of energy conservation in data centers has become increasingly prominent, and the green data center model is inevitable. The refrigeration equipment which is the main power consumption in the data center is affected by the environment, room temperature, unit output, and other factors. This paper provides a scheme of multi-unit collaborative optimization cooling. It is mainly divided into four stages: first, a model of the data center is built through Modelica, and it is exported as a fmu file. Second, the PSO optimization strategy is used to generate the data sets which contain unit output and cooling effect at different times. Third, LSTM and TCN load forecasting models are trained. Finally, through a comparison of various optimization algorithms, the PSO-LSTM-TCN model is used to simulate the unit output and optimize the output parameters of multiple units.
Large-signal Stability Analysis of Grid-connected DC Microgrid with VSC
Authors: Wu Ying , Xu Yonghai , Wang Yingxin , Chen Lin
Published: August 2023

The grid-connected DC microgrid under the background of high penetrations of renewable energy sources and high penetrations of inverter-interfaced devices has the characteristics of strong nonlinearity and poor immunity, which leads to the problems of large-scale voltage fluctuation and instability when the grid-connected DC microgrid suffers large disturbances, and it seriously influences the security and stable operation of the system. Therefore, a large disturbance stability criterion which is based on the mixed potential theory (MPT) for the DC microgrid model with a grid-connected voltage-source converter (VSC) is proposed. This paper also analyzes the mechanism of the conservatism of the stability criterion, verifies the accuracy of the large disturbance stability standard, and analyses the influencing elements and basic mechanism of the large-signal stability (LSS) of the nonlinear systems, which provides a benchmark to design the parameters of the control of VSC and main circuit. Finally, the effectiveness and accuracy of the analysis are verified by electromagnetic transient simulation.
Suppression Strategy of Differential Mode Circulating Current in Parallel Three-Phase PWM Converter
Authors: Wang Lianzhong , Cao Yifan , Liang Xiaobin , Jiang Xinjian , Li Tao , Zou Qifeng
Published: August 2023

Parallel three-phase pulse width modulation (PWM) converter is a useful technique for increasing the capacity of a power system, but it also introduces the issue of circulating current, which can cause an increase in the loss of power electronics (PE) switches and even lead to over-current, which can affect the overall performance of the system. In this paper, a strategy is proposed for suppressing the differential mode circulating current (DMCC) in each phase of the parallel converter, which is less dependent on system parameters. Based on the mathematical model of the parallel converter, the relationship between the PWM duty cycle and circulating current is derived, which provides a basis for adjusting the switching operation of PE switches. This method requires no additional hardware and is simple to implement with a fast dynamic response. The simulation results verify the correctness of the theoretical analysis, and it can effectively achieve the balanced suppression of DMCC in each phase, which indicates that the method is suitable for the application scenario of parallel current sharing of multiple converters.
A Time-sequential OPF Simulation Method for Renewable Utilization Studies Considering Energy Storage
Authors: Zhang Zhenmin , Cai Wenbin , Wang Yuan , Lu Haixia , Li Ye , Li Qinmiao
Published: August 2023

In recent years, renewable generation, especially wind, and solar have become one of the major generation resources in electrical power systems. Due to the non-dispatchable feature of renewable generation, curtailment occurs when the rest of the system is not able to accommodate the maximum renewable output. To analyze the curtailment in the system planning stage, however, traditional studies such as the production simulation method are limited to identifying accurate curtailment rates since the time resolution is sparse and grid topology is omitted. Therefore, in this paper, we propose a time-sequential optimal power flow (TSOPF) simulation method for studying renewable utilization. This method supports second-level temporal simulation which is fine enough to capture the fluctuations of renewables. In addition, the energy storage is incorporated in the simulation to reflect its impact on facilitating renewable utilization. The proposed simulation method is tested based on a real provincial power grid with historical time-sequential data of system load and renewable.
Unit commitment with AC optimal power flow constraint
Authors: Liu Shiqi , Wang Haoyi , Lu Zheqin , Dong Jizhe
Published: August 2023

Because of the enormous economic gain it may offer, unit commitment (UC) has been a primary optimization job in the daily operation planning of contemporary power systems. The AC optimal power flow (ACOPF) constraint is a method for determining the ideal load arrangement in alternating current (AC) power systems. Using unit commitment and ACOPF limitations to determine optimal load distribution is an important approach to ensure the steady functioning of power systems. The unit commitment approach with ACOPF constraint is examined in this study. The aims and contents of the study are set by analyzing the current approaches, and a piecewise linearized unit commitment method is developed that takes into consideration the ACOPF limitations and has good accuracy and practicality. Finally, to validate the method’s effectiveness, it was tested using a six-bus test system.
Two-stage Short Circuit Current Method Based on New Energy Source Fault Characteristic Fitting
Authors: Du Bowen , Guo Haiyi , Jiang Tong
Published: August 2023

A large number of full-power inverter type new energy sources are connected to the power grid, resulting in a large error in the traditional power grid short-circuit calculation method. By analyzing the relationship between the output current of full-power inverter type new energy sources and the voltage at the parallel point, a two-stage short circuit current method based on the fitting of new energy source fault characteristics is proposed. In the first stage, the polynomial fitting method is used. The piecewise function expression of the new energy source output current is fitted into a continuous derivative curve. In the second stage, the original output characteristic function is correspondingly replaced with the fitting function in the first stage. In each iteration process, the output short-circuit current of the new energy source is corrected according to the current new energy grid-connected node voltage until the convergence conditions are met. The feasibility of the proposed method is verified by the analysis and simulation of an IEEE 15 node example system. This method can be applied to solve the short-circuit current of the power grid with a full-power inverter type new energy source.
The coordinated control strategy of DC microgrid based on multiple energy storage units
Authors: Wang Chenxia , Xie Jiayu , Wu Zhiquan , Zhang Xin , Li Yingying , Song Huihui
Published: August 2023

Recently, the DC microgrid (MG) has caught people’s attention because of its simpler control system than the AC microgrid. In this paper, the bus voltage layering control method based on droop control is used for DC microgrid coordination control. According to the working characteristics of the DC bus, the voltage of the DC bus is divided into five sections, corresponding to 5 operating modes respectively. Inside the DC microgrid, each unit converts the operation mode by local control according to voltage amplitude. The photovoltaic power generation unit adopts MPPT control and constant voltage control to adjust the running point tracking, so as to realize changing-over smoothly between voltage regulator mode and MPPT. The battery system adopts a hierarchical operation control method of several batteries on the basis of the state of charge (SOC). To realize the target, which means getting rational active power allocation and SOC equilibrium of each battery unit, as well as different batteries changing-over the charge and discharge modes on the basis of SOC size, so as to adjust the droop curve according to the power size. Finally, the balance between the three objectives of the highest photovoltaic energy utilization rate, energy storage SOC balance, and stable bus voltage is achieved.
Operating State Evaluation Method of UHV Oil Immersed Shunt Reactors
Authors: Gu Zhaoliang , Gu Chao , Li Zhen , Zhu Wenbing , Zhu Qingdong , Li Longlong , Wang Jian , Wang Haozhe
Published: August 2023

The oil-immersed shunt reactor is one of the most important reactive power compensation equipment in the ultra-high voltage (UHV) long-distance transmission and transformation system, which can solve the problem of large power and long-distance transmission that makes the capacitance effect of transmission lines obvious. At present, the commonly used state evaluation methods for UHV oil-immersed shunt reactors are mostly based on a certain factor or several factors to make judgments, without a comprehensive consideration of the overall operating condition information of the shunt reactors. There are various uncertainties in the process of fault diagnosis and state evaluation of the shunt reactors, and the accuracy and timeliness of the diagnosis results are poor. To solve the above problems, this paper combines the key characteristic parameters of oil immersed shunt reactor, such as vibration, chromatography, partial discharge, and oil temperature, and establishes a comprehensive evaluation method for the operating state of oil immersed shunt reactor based on Gaussian Cloud Model (GCM), and verifies its effectiveness through test data, whose R2 over 0.98. The test data show that this method can effectively judge the operation state of the UHV oil-immersed shunt reactor, which accuracy rate of state diagnosis is over 91%. The results of this paper can provide technical support for the application of UHV oil-immersed shunt reactor state assessment and diagnosis, and further improve the level of equipment operation and maintenance.
Localized Equipment Calibration Technology for Substation Relay Protection Considering Electromagnetic Interference
Authors: Chen Jianpeng , Yang Mingze , Shi Yongjun , Yao Bin , Yun Zhenxing , Li Qinghong
Published: August 2023

At present, the conventional localized equipment calibration technology mainly adopts the manual way to check the equipment parameters, which leads to low calibration accuracy due to the lack of analysis of the calibration error sources. In this regard, the localized equipment calibration technology for substation relay protection considering electromagnetic interference is proposed. The calibration error value is calculated by simulating a high-precision localized equipment unit, designing the pre-circuit for fast voltage and current sampling, and analyzing the calibration error source. The experimental results show that the proposed calibration technique can effectively reduce the delay characteristic error value of the equipment and has a high calibration accuracy. The delay characteristic error of the average calibration is lower than 23%.
An LSTM-PSO-Based Predictive Strategy and Its Application in the Main Steam Temperature Control in Power Plants
Authors: Jin Fei , Hao Xiaoguang , Yin Zhe , Yang Chunlai , Liu Xuelai , Shi Yijun
Published: August 2023

We proposed an LSTM-PSO predictive controller strategy to overcome the large delay and strong disturbance during main steam temperature control. First, the long short-term memory (LSTM) network model was developed to forecast the future trend of mainstream temperature, and the deviation between the model output and the expected value after feedback correction was minimized by the particle swarm optimization (PSO) algorithm. Then, the LSTM-PSO predictive controller was taken as the primary controller to maintain the steam temperature of the coal-fired boiler. A comparative simulation with conventional PID cascade control and dynamic matrix controller strategies was given, and the test calculations indicate that the adjustment time was shortened and the overshoot was reduced. Finally, the LSTM – PSO predictive control strategy was deployed into the actual boiler operation process of a 300 MW coal-fired power plant, within 0.5 °C steady-state error and 2 °C dynamic error.
First-principles Study of the Structural Properties of RbSnI2Br Perovskites Under Pressure
Authors: Liu Xin , Zhang Suyun , Deng Pengcheng , Li Haoning , Zhao Yifen
Published: August 2023

As a member of lead-free perovskite, tetragonal phase perovskite RbSnI2Br has a long-term development prospect. Due to the effect of structural changes on physical properties, we have explored the pressure-induced phase transition of RbSnI2Br perovskite. For this project, the structural properties of the tetragonal phase perovskite RbSnI2Br are studied by using the Perdew-Burke-Ernzerhof (PBE) functional for the generalized gradient approximation (GGA) under pressure conditions of 0 GPa–1 GPa. The calculation results of structural factors were in excellent agreement with those obtained from previous studies at the ground state, which ensures the accuracy of the study. The results show phase transitions occur with increasing pressure. The structural space group of β-RbSnI2Br changes from P4/MMM (tetragonal system) to P1 (triclinic system) under pressure in the range of 0 GPa–1 GPa. All these provide a relative theoretical basis for our further understanding of α-RbSnI2Br perovskite.
Adaptive control of DFIG-based wind turbines for fault ride-through and reactive power support based on stator current transient component
Authors: Wang Jianing , Fu Yuan , Zhang Xiangyu
Published: August 2023

The fault ride-through performance is improved through the control of the transient components of the stator current. The reactive power provided by the DFIG within the margin of the converter can significantly enhance the grid-connected safety of the DFIG. Firstly, the reasons for the fault overcurrent of the DFIG’s rotor are analyzed. Secondly, according to the operating conditions of the wind turbine, the reactive power support limit of the DFIG-based wind turbines based on the stator current transient component control is analyzed, and an adaptive reactive power support control suitable for fault ride-through is proposed to maximize its support potential for grid-connected voltage. Finally, the DFIG can not only suppress the rotor overcurrent through the transient component of the stator current but also have a reactive power support capability that is superior to the grid-connected standard.
Suppression of voltage gain fluctuation in LLC Resonant Converter Based on chaotic spread spectrum
Authors: Liu Hong , Kong Fan-nie , Chen Yan-Ming
Published: August 2023

In order to realize the voltage stable output of the LLC resonant converter under different loads, a voltage gain fluctuation suppression technology of the LLC resonant converter based on a chaotic spread spectrum is proposed. The gain fluctuation electromagnetic interference signal is eliminated by the Chua’s circuit; The rated voltage value is discretized, and the target network and the evaluation network are used to form a deep Q network, with the multi-threshold judgment method and the variable step method respectively completed the gain fluctuation suppression target under different working conditions. The experimental results show that the proposed technology can achieve stable voltage output in both dynamic and steady-state conditions, with good gain fluctuation suppression effect and strong timeliness. It provides data reference for the rational application of the LLC resonant converter.
Research on Intelligent Terminal Based on Distribution Multi-service Integration under The Dual-carbon Target
Authors: Chen Zhijun , Zhou Chunli , He Chengyu , Lin Xiqiao , Qin Huiling , Cheng Min
Published: August 2023

The distribution network is used to distribute electric energy in the power system, which can reasonably allocate resources according to the power demand of different users. Intelligent terminals for distribution multi-service integration mainly include a distribution switch monitoring module, distribution transformer monitoring module, concentrator, gateway, and main controller. Firstly, the current, voltage, and power of electricity are collected by setting monitoring points in the distribution network and installing current transformers, voltage transformers, and energy meters. The collected data are processed by the distribution transformer monitoring module to improve the effectiveness of the data. Finally, the processed data are sent remotely through the main controller and gateway. By designing a four-in-one intelligent terminal device for distribution multi-service integration, it can monitor power equipment and collect power consumption information of different users, further excavating the potential value of power data, which has practical significance for the improvement of energy utilization efficiency.
Electric tractor dual motor coupling drive system structure design and simulation experimental research
Authors: Zhang Xin , Qi Huijun , Wang Wei , Ge Hongen
Published: August 2023

Electric tractors as a kind of green agricultural machinery, in reducing carbon emissions, saving resources, and other aspects have outstanding advantages. Therefore, the development and research of electric tractors are of great significance. In this paper, a new dual-motor coupled drive system applicable to electric tractors is proposed, and the structure and transmission characteristics of the system are analyzed in conjunction with the tractor operation requirements. At the same time, the drive system model is built in MATLAB/Simulink environment for simulation and verification. Finally, hardware-in-the-loop experiments were conducted using the Speedgoat platform. The simulation and experimental results prove that the electric tractor with this dual-motor coupled drive system has better power performance. The economic performance is better compared with the single-motor drive system, and the whole vehicle range can be extended by 1.23 h.
Hardware design of electrostatic levitation accelerometer control system
Authors: Liu Jianhe , Huang Wenhao , Chen Yuqi
Published: August 2023

The electrostatic levitation accelerometer is a high-precision inertial instrument for measuring small displacement and acceleration, and it plays a very important role in global gravity field measurement, space gravitational wave detection, and other space missions as a key payload for satellites. It can realize the measurement of three-axis linear acceleration and three-axis angular acceleration. The open loop is unstable, and the control system needs to control six degrees of freedom at the same time so that the test mass can be stably suspended in the center position of the capacitive pole plate. For the demand of multi-channel simultaneous control of electrostatic levitation accelerometer, this paper designs an eight-channel digital control system hardware circuit with DSP as the core and FPGA as the co-processor, which can realize the data acquisition and feedback control of six degrees of freedom, writes the driver using hardware description language (Verilog), and simulates and analyzes the driver timing by the timing simulation software Modelsim. Finally, the hardware circuit was tested for the onboard drive. The results show that the system can work normally, the average sampling error of ADC is 0.00198 V, and the output error of DAC is 0.004 V, which is small enough to meet the system requirements.
LEO Small-Scale Experimental Regional Navigation Constellation Design and Optimization
Authors: Liu Jialu , Wang Shuquan
Published: August 2023

In order to demonstrate the key functionalities of large-scale LEO navigation constellations, this paper investigates the small-scale LEO experimental constellation design problem. The major requirements include achieving quadruple coverage of specific ground target areas. The regional navigation constellation consists of four satellites distributed on two orbit planes. Considering the sustainable regional navigation, it is expected that the orbits of the satellites are regressional such that it takes little effort for the constellation to cover the designated region. In this way, the structure of the optimization problem is set up, which is constrained by the quadruple coverage and accuracy requirements. It takes the maximum task time as the objective function. The differential evolution algorithm (DE) is utilized to solve the optimization problem. The optimal regional navigation constellation design scheme satisfying the constraints is obtained. The simulation results show that the regional navigation constellation designed by this method can meet the predetermined requirements.
Integrated System of Spacecraft Impact Monitoring and Shape Reconstruction
Authors: Luo Yuxiang , Zhang Qingzhi , Wang Dingding , Sun Geng , Wu Yanxi , Cao Jian , Du Xuan , Sun Zhaoxiong , Zhang Tao
Published: August 2023

When the spacecraft is in orbit, there is a risk of high-speed impact by space debris. After the spacecraft is impacted, it is of great significance to determine the exact location of the spacecraft and the structural changes caused by the impact. However, the conventional impact monitoring methods are mainly realized by sticking sensors on the surface of spacecraft structures. Such contact measurement methods generally have one or more of the problems of large size, heavy mass, complex system, easy to fall off, and do not have the function of reconstructing the shape of the impacted part of the spacecraft. This study proposes an integrated system of spacecraft impact monitoring and shape reconstruction, which realizes the organic integration of positioning and shape reconstruction and can help astronauts and ground technicians to timely know the impact location and shape changes after spacecraft damage.
The Demand for Satellite Attitude Error for High-Resolution Spaceborne SAR Image Quality
Authors: Guo Xin , Yao Yuying , Fu Weida , Shi Sihan , Wang Zhonghui
Published: August 2023

Because of the prominent problem of insufficient index decomposition of satellite-earth integration indicators and attitude control demand analysis for spaceborne SAR, this paper made studies on the effect of attitude measurement error and attitude pointing error for spaceborne SAR images. The attitude error model of azimuth and range antennae was constructed. The quantitative transfer relationships, which contain the attitude measurement error model determined by azimuth Doppler parameters and the attitude pointing error model determined by ambiguity and system sensitivity, were analyzed. Theoretical analysis and simulation results are shown as follows: for the X-band SAR satellite, the attitude measurement error should be better than 0.01° for 0.5 m azimuth resolution, and the attitude pointing error should be better than 0.03°. The research results can provide theoretical support for the error allocation phase of the satellite scheme and the analysis of attitude control requirements.
Design and Analysis of Buffer Device for Interstage Pyrotechnic Separation
Authors: Yang Yifan , Lin Sanchun , Luo Yanshou , Yu Yubing , Yang Heng
Published: August 2023

Buffer device for interstage pyrotechnic separation is the key part to achieving electrical connector plug separation. This paper carries out research on the buffer structure in different working conditions and finally designs two kinds of buffer devices, which are respectively applied to the stage separation structure of large mass SLMB (Shingle-Like Mass Blocks) and the stage separation structure of the small mass SLMB. Both can control the energy absorption size of the device through structural parameters to adapt to different working conditions. Compared with the original structure, the buffer effect after optimization is very obvious. The time domain peak value and frequency domain peak value of the buffering device suitable for small mass SLMB are reduced by 79.90% and 85.67%, respectively. The buffering device suitable for large mass SLMB changes the energy absorption mode of the buffering structure, and the steel cable structure will not break. Compared with the original structure loaded with small mass SLMB, the response in the time domain and frequency domain also decreased. The application range of buffer devices for interstage pyrotechnic separation is greatly expanded.
Pipe Routing Design for Aero-Engine Using Monte Carlo Tree Search Method
Authors: Xu Hongbin , Fan Jiang , Meng Qingze , Su Yuming
Published: August 2023

Pipe routing design (PRD) is a complex process that involves a large search space and requires experienced professionals. Despite advancements in aero-engine design, PRD remains a stage that is not completely automated. In this article, we present a new approach to PRD by formulating it as a Markov decision process and proposing a pipe routing design method based on Monte Carlo Tree Search (PRD-MCTS). Firstly, this paper uses an intelligent algorithm to look for enough paths for each pair of joints. Secondly, PRD-MCTS regards each path as a candidate choice, and then PRD-MCTS randomly chooses a path and calculates the probability of collision-free routing until the set time. The method selects the path with the highest probability and updates the environment for the next selection. A simplified environment from the aero engine verifies the correctness of the methods.
Aerodynamic Stability Study of Turbojet Engine During Unmanned Aerial Vehicle Assisted Taking Off Stage
Authors: Du Yufei , Wu Jiang , Wang Gerui , Du Farong
Published: August 2023

Rocket Assisted Take Off (RATO) technology is utilized for the takeoff phase of various types of UAVs. RATO creates heavy axial overload for a UAV system, which consequently increases the inlet pressure of the fuel pump of the UAV’s turbojet engine. This situation leads to an abrupt change in fuel supply for its combustor, eventually causing drastic changes in the operating state of the compressor system. In addition, it may potentially induce compressor surge. To resolve this problem, through an experimental investigation, this study delves into the dynamic response of the fuel system during the RATO phase. A two-zone dual-wave coupled compressor model has been established for the intake-turbojet engine system to scrutinize the aerodynamic stability of the turbojet engine during the RATO phase. The findings reveal that when the increase of fuel pump inlet pressure causes changes in the fuel flow rate, it is essential for the engine to re-establish aerodynamic equilibrium in order to mitigate the impacts of abrupt fuel flow step increases. Moreover, it has been observed that the more the ratio of the length of the intake and the cross-section area, the greater the contribution of the inertial force of airflow in the pipe it brings within the passage. This results in a stronger suppression of combustion chamber pressure and flow rate fluctuations induced by fuel step supply, thereby rendering the compressor less susceptible to surge. In summary, this research contributes valuable insights for appropriate matching of intakes, enhancing the ability of the turbojet engine against fuel step supply in the combustion chamber during the takeoff stage and augmenting the aerodynamic and thermodynamic overload resistance capability of the engine.
A high-precision synchronization system based on custom benchmarks
Authors: Shi Xiaoxia , Wang Yu , Li Xindong
Published: August 2023

In order to meet the requirements of high synchronization of information flow for the cooperation among subsystems of spacecraft and of autonomous operation and management of spacecraft, this article proposes a synchronization system design based on a custom synchronization benchmark. This plan provides a custom synchronization benchmark design method and design constraints and proposes synchronization strategies for different system requirements. On this basis, a high-precision synchronization system design scheme is proposed. By conducting tests, the synchronization error compliance of the synchronization system is verified based on custom benchmarks. This design does not rely on the availability of GPS signals, and the synchronization system design is triggered by the requirement for synchronization accuracy. This method can be applied to spacecraft onboard systems and ground testing systems with extensive application value.
Analysis of Pressure Fluctuation of Pumped Storage Units
Authors: Li Yao , Ma Zhijie , Sun Bozhi
Published: August 2023

In pump turbines, the observation in the engineering field shows that pressure fluctuation has become one of the most serious hydraulic instability phenomena. The pressure pulsation will cause vibration and fatigue failure of the unit, even vibration of the plant, which greatly affects the safe operation of the power station. In this paper, the research on pressure fluctuation by domestic and foreign researchers is introduced and discussed. It includes the characteristics of pressure pulsation in various regions of pump turbines under various operating conditions, existing research methods, and the possibility of improving pressure pulsation problems with variable-speed pumped storage units, which will serve as the basis for further research and improvement of pressure pulsation.
A New Type of Oxidation Air Bubble Breaking and Detention Device with Wing Span Baffle Structure Numerical simulation research
Authors: Zhang Qilong , Wu Dehua , Guo Junhai , Wu Bin , Qi Zhenyu , Wang Peng
Published: August 2023

Taking the limestone gypsum wet desulfurization oxidation air duct of a 660 MW coal-fired unit in a power generation enterprise as the research object, a new type of oxidation air bubble crushing and retention device with a wing span baffle structure was simulated and optimized using CFD numerical simulation technology. The results showed that the retention time of bubbles in the slurry in the final design scheme was about 10.4 seconds, significantly better than the initial scheme’s 8.5 seconds and the comparison scheme 1’s 6.5 seconds. The new oxidation air bubble crushing and retention device significantly increases the retention time of oxidation air bubbles in the slurry, reduces the size of oxidation air bubbles, and improves the distribution uniformity of oxidation air in the slurry pool.
UCAV situation assessment based on SAE-ELM
Authors: Xie Lei , Huang Changqiang , Tang Shangqin , Li Yintong , Han Bo
Published: August 2023

A Stacked Autoencoder Extreme learning machine (SAE-ELM) assessment model is proposed to study the weight of an Unmanned Combat Air Vehicle (UCAV) situation assessment. On the basis of the existing air combat situation description parameters and their optimized situation advantage function weights, the mapping relationship between the air combat situation description parameters and the situation advantage function weights is established by using the SAE-ELM to achieve a more accurate evaluation. From the four error indicators of MAE, RMSE, MAPE, and R-Squared, the simulation experiment shows that the SAE-ELM evaluation error is the smallest and can effectively achieve accurate situation assessment.
Evaluation Indicators of Space Frontier Technology Based on D-ANP
Authors: Zheng LeiXin , Wang WeiJun
Published: August 2023

With the rapid development of aerospace frontier technology and the gradual improvement of its application impact, it is particularly necessary to track and analyze the development and evaluation of frontier technology. In the process of a comprehensive evaluation, the rationality and weight of evaluation indicators determine whether the evaluation is effective. In this paper, the relevant evaluation index system is constructed through a comprehensive analysis of various factors of aerospace frontier technology. The weight of the index is calculated by the combination of DEMATEL and ANP to judge the interaction and importance of the indexes and make the evaluation results more accurate and reliable.
Study on the aerodynamic performance of nacelle inlet under crosswind
Authors: Lin Weibin , Wu Xing , Shao Yanan , Meng Tianyu , Zhang Han
Published: August 2023

Flow separation will occur in the nacelle inlet under crosswind operation, which will result in engine intake distortion and even engine surge. To study the reference characteristics of the flow field of the short tank inlet separation under the influence of crosswind, this paper observed the cloud map of the total price loss coefficient by changing the flow deflection Angle and flow velocity, made a qualitative analysis of the total pressure distortion degree, then calculated the average total pressure loss coefficient and distortion index, and conducted a quantitative analysis to explore the improvement of the total pressure distortion under different flow field factors. The results show that the degree of total pressure distortion is improved with the increase of incoming flow velocity at a small inlet deflection Angle, but with the increase of incoming flow deflection Angle, the ability of incoming flow velocity to improve the total pressure distortion gradually weakens until it disappears. The inlet deflection Angle plays a decisive role in the improvement effect of incoming flow velocity on the total pressure distortion.