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Design and Implementation of Self-study Room Platform Based on Springboot and Uni-app Framework LI Jinzhong, HU Zhiming, CHEN Jiangang, CHEN Hanxuan, ZUO Zuo Journal of Hebei University of Water Resources and Electric Engineering    2024, 34 (2): 77-82.   DOI: 10.16046/j.cnki.issn2096-5680.2024.02.014 Abstract （529）      PDF（pc） （551KB）（126）       Knowledge map    Save At present, domestic education has begun to popularize online learning mode on a large scale. However, many existing online learning platforms gradually appear the problem of excessive entertainment and social seriousness, which seriously violatesthe original intention of the birth of online learning platforms. In addition, the platform has relatively limited functions, making it difficult to comprehensively manage the learning status of users, and there is also a considerable shortage of products on the market that meet users'needs. Therefore, this paper designs and develops a mobile self-study room platform based on SpringBoot and Uni-App frameworks, which is specially designed to provide users with learning state management services. The main functions of the platform include five functional modules: self-study state management, learning dynamic management, leaderboard, notepad, and user information management. The platform can provide users with a series of learning state management services to help them develop a good learning self-control, cultivate students' independent learning ability, and improve learning efficiency. Reference | Related Articles | Metrics | Comments（0）

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Design of Intelligent Guide Robot System Based on Machine Vision WANG Zheng-bo, TANG Yong, CHEN Guo-dong, Lu Shu-xuan, Yao Cheng-zhi Journal of Hebei University of Water Resources and Electric Engineering    2021, 31 (4): 17-22+54.   DOI: 10.16046/j.cnki.issn2096-5680.2021.04.003 Abstract （353）      PDF（pc） （3172KB）（85）       Knowledge map    Save With the development of intelligence, image processing technology has become more and more widely used in our lives and production, especially in intelligent robots. Aiming at the current research status of blind guide robots at home and abroad, a kind of blind guide robot based on machine vision is designed. This design can detect and recognize the types of surrounding objects and the distance to the robot through monocular distance measurement combined with You Only Look Once Version3 (YOLO V3) algorithm, and inform the blind by phonetic sound. Guide robot completes autonomous combined with various sensors navigation; the blind person walks under the guidance of robots, which greatly compensates for the blind,s visual defects. From the results of the simulation experiment environment, it can be seen that the guide robot realizes the functions of advance, stop, turn and obstacle avoidance, which can also realize the function of indicating the type and distance of the obstacle in front, thereby providing a safe guarantee for the blind to travel. Reference | Related Articles | Metrics | Comments（0）

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Research on the Influence of High Permeability Distributed Power Supply Access on Voltage Stability of Distribution Network PENG Cheng, LU Wen-mei, LI Wen-cai, SHI Pei-yu, GAO Bo Journal of Hebei University of Water Resources and Electric Engineering    2020, 30 (4): 44-48.   DOI: 10.16046/j.cnki.issn2096-5680.2020.04.007 Abstract （335）      PDF（pc） （1507KB）（59）       Knowledge map    Save With the increasing capacity of DG connected to the distribution network，the problems of node voltage cross-limits，system bidirectional power flow，and short-circuit current increase in the traditional distribution network have become increasingly prominent.In order to improve the capacity of renewable energy consumption in the distribution network，the optimal access scheme and the method of maximum using the residual capacity of grid connected inverter to participate in voltage regulation are proposed.By establishing the calculation model of voltage drop of distribution network with multiple access modes of distributed generation，the influence mechanism of single-point and multi-point distributed generation on voltage distribution of distribution network is analyzed.The IEEE33node system model was built based on Matlab，and the influence of access mode，access location，permeability and power factor on the voltage distribution of the distributed generation was studied.In addition，the voltage distribution is presented in a 3dvisual way to more intuitively compare the advantages and disadvantages of different schemes.Studies have shown that DG more evenly distributed grid and making full use of the residual capacity of grid inverter can effectively improve the distribution network voltage distribution and provide references for improving the consumption of renewable energy. Reference | Related Articles | Metrics | Comments（0）

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Expansion and Quantitative Attribution of China’s Built-up Areas Based on Parameter Optimal Geodetector LIU Dan-dan, LI Yong-liang Journal of Hebei University of Water Resources and Electric Engineering    2023, 33 (3): 33-39.   DOI: 10.16046/j.cnki.issn2096-5680.2023.03.006 Abstract （321）      PDF（pc） （464KB）（95）       Knowledge map    Save To study the spatiotemporal changes in urban built-up areas in China over the past 20 years from 2002 to 2021, promoting the urbanization process, and socially sustainable development in China, urban units in China were selected as the research objects. DMSP-OLOS data from 2002 and NPP-VIIRS night light data from 2021 were used, combined with indicators such as expansion speed, standard deviation ellipse, and spatial autocorrelation. Quantitative analysis of the spatial distribution characteristics in built-up areas is elaborated in two aspects: quantity structure and spatial distribution. Some factors are used as independent variables such as GDP difference, population difference, elevation, road network density, temperature difference, and rainfall difference. Expansion speed is used as the dependent variable. The driving force is quantitatively analyzed by parameter optimal geographic detector. 1) In the past 20 years, the expansion speed of urban built-up areas in our country has been mainly in medium and low speed, The annual expansion rate of the built-up areas in the eastern and northern coastal areas is higher than the national average. The middle reaches of the Yellow River and the southern coast are comparable to the national average, while the middle reaches of the Yangtze River, Southwest China, Northeast China and Northwest China are significantly lower than the national average. The eastern coastal areas have the fastest expansion speed and the smallest difference in urban development, while the center of gravity of China′s built-up areas moves 100.22 kilometers from the eastern coastal areas to the northwest. 2) The expansion speed of the built-up area has spatial heterogeneity, reflecting the accumulation of cold and hot spots. Cold spot areas are distributed in the northern and central regions of China and exhibit low-low clustering and high-low clustering, while hot spot areas are distributed in the southeastern coastal areas of China and exhibit high-high clustering and low-high clustering; 3) GDP,population are the main factors affecting the development of built-up areas, with the explanatory power of 0.6395, 0.4965, respectively. The interaction between various factors is either double factor enhancement or non-linear enhancement, with strong interaction between socioeconomic factors, and the strongest interaction between GDP and population factors. The explanatory power of 1.1361 shows a double-factor enhancement. Reference | Related Articles | Metrics | Comments（0）

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Measurement of Phase Difference Based on FFT and Its Implementation in STM32 CHEN Zhe, FENG Min Journal of Hebei University of Water Resources and Electric Engineering    2019, 29 (2): 40-44.   DOI: 10.16046/j.cnki.issn2096-5680.2019.02.008 Abstract （308）      PDF（pc） （1457KB）（161）       Knowledge map    Save According to the problem of large error in the traditional measuring method for phase difference,this paper presents a digital measuring method for phase difference based on FFT spectral analysis,and builds a measuring system for phase difference by using the ARM＇s processor Cortex-M3core STM32F103.Through the FFT transformation of 64sampling points in a period and withdrawal of the fundamental wave parameter,the phase difference of measured signal is obtained and shown on the LCD.The structure of this system is simple,the cost of hardware is low,and the processing speed is fast.Through the test,this digital measuring system has an effective resolution accuracy of 1degree. Reference | Related Articles | Metrics | Comments（0）

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Research on Comprehensive Prevention Technology of Bird Damage on Transmission Line HU Jian, GUO Hao, ZHANG Zhi-hong Journal of Hebei University of Water Resources and Electric Engineering    2020, 30 (3): 42-47.   DOI: 10.16046/j.cnki.issn2096-5680.2020.03.008 Abstract （272）      PDF（pc） （2077KB）（133）       Knowledge map    Save In recent years,with the continuous extension of the power grid and the improvement of the ecological environment,the activities of birds in the vicinity of overhead power lines have increased,which has had a certain impact on the safe operation of the power grid.This paper analyzes the types and mechanisms of bird damage,as well as the regional distribution and laws.Then typical examples for bird damage identification are provided.The common bird damage prevention measures are studied,and new bird prevention measures are proposed to address the shortcomings,improve the transmission line bird prevention level,and reduce the transmission line trip rate,which is of great significance to ensure stable and reliable power supply for the power system. Reference | Related Articles | Metrics | Comments（0）

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Causes,Treatment and Improvement Measures of Several Faults of Leakage Protector YU Zhong-he, RU Jiang-yan Journal of Hebei University of Water Resources and Electric Engineering    2019, 29 (4): 46-49.   DOI: 10.16046/j.cnki.issn2096-5680.2019.04.007 Abstract （251）      PDF（pc） （453KB）（13）       Knowledge map    Save Due to the mismatch of power supply system，improper selection of electrical equipment matching with leakage protector and the reasons of the protected electrical equipment itself，the leakage protector will cause misoperation or refusal of action.In this paper，the common faults of leakage protection devices in engineering practice are described in detail，the causes of the faults are analyzed and the safe and effective solutions are given. Reference | Related Articles | Metrics | Comments（0）

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Research on Isolated Three-phase Bridgeless Sepic PFC Converter Based on One-cycle Control ZHANG Chun-jiang, TANG Jia-lin, XU De-xun, GAO Jia-ning, SHI Bing-qian Journal of Hebei University of Water Resources and Electric Engineering    2022, 32 (2): 20-28.   DOI: 10.16046/j.cnki.issn2096-5680.2022.02.004 Abstract （246）      PDF（pc） （2020KB）（130）       Knowledge map    Save Power factor correction technology is widely used in rectifier circuits to reduce harmonic pollution. Firstly, this paper studies a new type of isolated three-phase bridgeless Sepic PFC converter, which can realize power factor correction and isolated DC/DC conversion through one-stage conversion. In this paper, each working mode of the three-phase bridgeless Sepic PFC converter is analyzed in detail, and the continuous working conditions of the circuit are analyzed. Secondly, the one-cycle control technology is used to realize the closed-loop control, the core control equation of the one-cycle control is established, the small signal modeling is carried out, and the voltage loop controller is designed to stabilize the system under different parameters in the frequency domain and time domain respectively. The simulation analysis is carried out, and the realization method of digital one-cycle control based on DSP is designed. Simulation and experimental results show that the one-cycle control three-phase bridgeless Sepic PFC converter can achieve unity power factor and small current distortion rate. Reference | Related Articles | Metrics | Comments（0）

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Design and Research of External Prestressed Reinforcement of Highway Simply Supported T Beam Based on MIDAS Civil JI Gang-sheng, MA Shi-bin, CHEN Xiao-guang, LIANG Dong Journal of Hebei University of Water Resources and Electric Engineering    2021, 31 (4): 1-7+36.   DOI: 10.16046/j.cnki.issn2096-5680.2021.04.001 Abstract （225）      PDF（pc） （3526KB）（49）       Knowledge map    Save In view of the serious shortage the baring capacity caused by the long-term disrepair of some important trunk highway bridges , low standard of design load and rapid increase of traffic flow, the construction scheme of external prestressed reinforcement can effectively improve the bearing capacity of the main girder structure, reduce the impact of construction on traffic to the greatest extent, and has good economic effect. In this paper, based on the introduction of the external prestressed structural design of Wusugou Bridge, MIDAS Civil finite element numerical simulation analysis, the load-bearing capacity and normal service limit state of the main beam structure before and after reinforcement are checked. Finally, combined with the actual engineering construction monitoring, the maximum deflection measured after the completion of tension is 15.63mm. It appears at the position of 2# beam in the middle section of the test T beam, and the variation of deflection is basically consistent with the theoretical calculation value and the measured value of the bottom stress of the main beam. The results show that it is feasible and effective to use external prestress to reinforce highway simply supported T beam. Therefore, from the technical feasibility, effect reliability and construction simplicity, this study can provide reference for similar construction projects. Reference | Related Articles | Metrics | Comments（0）

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TMulti-target Detection of Smart City Based on Improved YOLOv5 Algorithm WANG Jichao, TANG Yong, HUI Zhenqiao, LIU Haozhuo, LIU Bing Journal of Hebei University of Water Resources and Electric Engineering    2024, 34 (3): 24-29.   DOI: 10.16046/j.cnki.issn2096-5680.2024.03.005 Abstract （222）      PDF（pc） （342KB）（41）       Knowledge map    Save As the core technology of smart city construction, multi-object detection plays an irreplaceable role in establishing city map, mining city operation law and improving city operation efficiency. Based on the excellent target detection model YOLOv5, this paper selects typical scenes in cities, takes pedestrians and vehicles as detection targets, and improves the SPP module of the neck part of the original lightweight version algorithm to ensure detection speed and increase detection accuracy. Then, the improved algorithm and YOLOv5-s algorithm were deployed on the edge devices of smart cities at the same time, and a comparative test was conducted. Experimental results show that compared with YOLOv5-s algorithm, the improved algorithm in this paper can improve the multi-target detection accuracy by 15.7% when the speed remains basically unchanged, which solves the problem that the detection rate and accuracy of edge devices in smart cities cannot meet the requirements at the same time to a certain extent, and provides a theoretical reference and method basis for multi-target real-time detection in smart cities. Reference | Related Articles | Metrics | Comments（0）

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Review on the High Temperature Performance Evaluation Indexes of Asphalt Binder HOU Licheng, MA Shibin, ZHANG Yu, YUAN Qijie, ZOU Baogang Journal of Hebei University of Water Resources and Electric Engineering    2024, 34 (1): 9-15.   DOI: 10.16046/j.cnki.issn2096-5680.2024.01.002 Abstract （222）      PDF（pc） （1006KB）（13）       Knowledge map    Save Using different indicators to evaluate the high temperature performance of the same asphalt binder may get different results. In order to quickly and accurately analyze the high temperature performance of asphalt binders, it’s very important to select a suitable evaluation index. Firstly, this article summarizes the limitations of conventional indicators such as penetration, softening point, 60℃ dynamic viscosity, and rutting factor in evaluating the high temperature performance of asphalt binders. Secondly, new indicators are introduced, including modification rutting factor G*/(sinδ)9, viscous part of complex shear modulus Gv and non-recoverable creep compliance Jnr, then the characteristics of these new indicators are analyzed and research results obtained by using each indicator are reviewed. Finally, this paper puts forward suggestions for the revision of relevant norms in my country and the future development is prospected. Reference | Related Articles | Metrics | Comments（0）

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Study on Dynamic Mechanical Properties of Concrete under Impact Load CHENG Siwu, DAI Xingxian, FENG Kai, QI Ziyi, ZHANG Ze Journal of Hebei University of Water Resources and Electric Engineering    2024, 34 (1): 22-28.   DOI: 10.16046/j.cnki.issn2096-5680.2024.01.004 Abstract （207）      PDF（pc） （1120KB）（25）       Knowledge map    Save In order to investigate the dynamic mechanical properties of concrete under impact load, finite element analysis software was used to simulate the SHPB tests of C30, C40 and C60 concrete under different impact velocities. The stress-strain curves and energy time-history curves at different velocities were obtained by numerical simulation, and the crushing process of the specimen was analyzed. The results show that the peak stress of C40 concrete and C60 concrete is 20.8% and 31.6% higher than that of C30 concrete, respectively. Improving the strength grade of concrete can improve the impact resistance of concrete structure. When the impact velocity is 10m/s and 15m/s, the strain rate of concrete is 3.2 and 4.7 times that of 5m/s, respectively, indicating that concrete is a strain rate-sensitive material. The energy time history curve is generally divided into three stages: the initial stable stage, the mid-term growth stage, and the final stable stage. Under impact load, concrete breaks from the edge from outside to inside first, and splits inside. Reference | Related Articles | Metrics | Comments（0）

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Design and Implementation of Body Motion Recognition Method Based on Kinect V2 WANG Zheng-bo, TANG Yong, LIU Chen-miao, SUN Dong-lai Journal of Hebei University of Water Resources and Electric Engineering    2023, 33 (1): 12-18.   DOI: 10.16046/j.cnki.issn2096-5680.2023.01.003 Abstract （203）      PDF（pc） （434KB）（32）       Knowledge map    Save In the fields of computer vision and pattern recognition, body motion recognition has always been a hot topic. Body motion recognition technology has been widely used in various industries. In this paper, Kinect equipment is used to collect the three-dimensional coordinates of 20 key parts of the human body and apply them to the analysis and identification of body movements; on this basis, the three-dimensional depth information based on human bones is analyzed, and the human motion is further analyzed. Identification and expression of features. Through the system simulation and analysis of the recognition results, the recognition accuracy rates are all above 92%. At the same time, the recognition and analysis of different forms of characters can be recognized normally, which verifies the feasibility of the system. Reference | Related Articles | Metrics | Comments（0）

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Design of a Quadcopter Based on Ultrasonic Obstacle Avoidance SUN Xiao-hui, YANG Jin-guang Journal of Hebei University of Water Resources and Electric Engineering    2023, 33 (3): 9-13.   DOI: 10.16046/j.cnki.issn2096-5680.2023.03.002 Abstract （201）      PDF（pc） （401KB）（88）       Knowledge map    Save This paper expounds the design of a quadcopter and proposes an overall solution that applies ultrasonic ranging technology to realize the automatic obstacle avoidance function of UAV. Firstly, algorithms such as Euler angle and extended Kalman filtering are applied to process the information collected by the MPU9250 sensor, calculate the position and attitude information, and adjust the PID parameters to realize the steady-state flight control of the quadrotor UAV. Secondly, the information collected by the SUI04 ultrasonic obstacle avoidance sensor is transmitted to the STM32H743 controller, and the corresponding instructions are output through algorithm processing to realize the obstacle avoidance function. Finally, after testing, in the outdoor low-speed flight state, the quadcopter UAV basically realizes the functions of fixed height flight and automatic obstacle avoidance. Therefore, it can be concluded that the automatic obstacle avoidance function of quadrotor UAV can be realized by ultrasonic ranging technology, and the obstacle avoidance effect is relatively stable and has certain practicality. Reference | Related Articles | Metrics | Comments（0）

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Application of Flipped Classroom in College English Teaching Journal of Hebei University of Water Resources and Electric Engineering    2019, 29 (4): 77-80.   DOI: 10.16046/j.cnki.issn2096-5680.2019.04.014 Abstract （201）      PDF（pc） （149KB）（21）       Knowledge map    Save Reference | Related Articles | Metrics | Comments（0）

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Discussion on the Technology and Safety Protection Measures of Hanging Basket Construction Across Freeways JIN Da-zhi, LU Cheng-ming, LU Nan Journal of Hebei University of Water Resources and Electric Engineering    2023, 33 (4): 53-57.   DOI: 10.16046/j.cnki.issn2096-5680.2023.04.010 Abstract （201）      PDF（pc） （411KB）（197）       Knowledge map    Save In the construction of highway bridges, the hanging basket construction technology has been widely used, but in some special geographical environments, this method still needs to overcome various difficulties and challenges. This article provides a detailed introduction to the design scheme, installation steps, and construction process of the hanging basket for an overpass highway bridge construction case, and explores the safety protection measures during the construction of the overpass highway. The results indicate that during the construction of the cross highway range, protective brackets and protective nets are used to seal the mid span hanging basket. At the same time, a bottom protection platform is set under the main body of the hanging basket, which can effectively prevent scattered materials such as steel reinforcement heads, bolts and nuts, mortar, welding electrodes, welding sparks, small tools, etc. from falling into the traffic lane and prevent high-speed traffic safety accidents. By exploring the construction process and safety protection measures of hanging baskets in this article, solutions and ideas are provided for similar engineering project construction difficulties. Reference | Related Articles | Metrics | Comments（0）

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Application of Comprehensive Geophysical Exploration Method in Leakage Detection of Levee Liu Jin-peng, Wang Zhi-hao, Tang Ke-xuan, Zhang Mei-duo, Liu Kang-he Journal of Hebei University of Water Resources and Electric Engineering    2023, 33 (4): 1-7.   DOI: 10.16046/j.cnki.issn2096-5680.2023.04.001 Abstract （195）      PDF（pc） （596KB）（422）       Knowledge map    Save Geophysical detection method is an effective method for non-destructive testing of levees, but each geophysical detection method measures a single physical parameter, such as resistivity value, potential value, seismic wave velocity and so on. There are limitations and multiple solutions in geological interpretation when using a single parameter. This paper introduces the basic principles, advantages and disadvantages of common used geophysical detection methods for hidden dangers of levees, and discusses the application of comprehensive geophysical methods in identifying hidden dangers of levees leakage through engineering examples, which can be used as a reference for similar projects. Reference | Related Articles | Metrics | Comments（0）

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Research on Coordinated Control Strategy and Grid Connection of Wind-solar Complementary Power Generation System MENG De-yue, LIU Wei, CUI Mao-qi Journal of Hebei University of Water Resources and Electric Engineering    2021, 31 (2): 51-55+66.   DOI: 10.16046/j.cnki.issn2096-5680.2021.02.009 Abstract （195）      PDF（pc） （1832KB）（105）       Knowledge map    Save Photovoltaic power generation and wind power generation are characterized by intermittenency and volatility.Combining the two can effectively alleviate power supply imbalance and improve the reliability of power generation system.In this paper，the photovoltaic electronic module，wind electronic module and battery sub-module in wind-solar complementary power generation system are analyzed and modeled，and the maximum power tracking simulink simulation of photovoltaic power generation system and wind power generation system is completed.On this basis，a wind-solar complementary coordinated control and grid connection strategy is proposed，and the simulation results verify the feasibility of the control strategy. Reference | Related Articles | Metrics | Comments（0）

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A DEM Generation Method Based on Progressive Morphological Filter WU Jingchuan, LIU Niantao Journal of Hebei University of Water Resources and Electric Engineering    2024, 34 (1): 81-86.   DOI: 10.16046/j.cnki.issn2096-5680.2024.01.014 Abstract （190）      PDF（pc） （1042KB）（23）       Knowledge map    Save In order to find a new production method for DEM and improve the updating efficiency of city DEM, this paper proposes a new method to filter non-ground elevation points from ground elevation points in DSM by progressive morphological filter. The ground elevation points are then triangulated to Delaunay triangulation and the DEM is generated by intersecting rays with the Delaunay triangulation. The experiment shows that the proposed method not only generates DEM effectively, but also generates DEM with great precision, proving that it has important practical value. In conclusion, the proposed algorithm is technically feasible and it can improve the utilization rate of drone DSM to promote the renewal of city DSM. Reference | Related Articles | Metrics | Comments（0）

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Construction Technology for TBM Card Machine Trapping under Unfavorable Geological Conditions of Rock Burst and Altered Rock HAN Jianlu Journal of Hebei University of Water Resources and Electric Engineering    2024, 34 (1): 16-21.   DOI: 10.16046/j.cnki.issn2096-5680.2024.01.003 Abstract （188）      PDF（pc） （1230KB）（34）       Knowledge map    Save With the rapid development of the economy and society, tunnel engineering is flourishing in China. Tunnel Boring Machine (TBM) combined with drilling and blasting method is currently a commonly used construction method for ultra long mountain tunnels. In adverse geological conditions, hard rock tunneling machines are prone to jamming, and in severe cases, engineering accidents may even occur. In order to cope with the possible jamming situation mentioned above, a technology for dealing with TBM jamming under adverse geological conditions such as rockburst and weathered rock is proposed based on the construction of water conveyance tunnels using the TBM method under construction. The key points of treatment, specific construction methods, and control processes are emphasized. The implementation of this construction technology and the application of TBM to overcome difficulties provide valuable cases and references for dealing with similar engineering equipment in the future. Reference | Related Articles | Metrics | Comments（0）