bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation Study on the Influence of Yaw-to-Wind Angular Velocity on Wind Turbine Aerodynamic Characteristics
Authors: Jin Baoyu , Gao Zhiying
Published: May 2023

In this paper, the wind turbine of NREL 5MW wind turbine is used as the research object, and the wind turbine is simulated from yaw-to-wind angle 30°-0° at different yaw angular velocities (0.5°/s, 1°/s, 2°/s) under rated operating conditions by using the slip grid model in fluent solver and custom UDF function program. The output characteristics and aerodynamic characteristics of the wind turbine under dynamic wind conditions are studied, and the effects of yaw angular velocity and yaw-to-wind angle on the output power, and near wake speed of the wind turbine are analyzed. The results show that the smaller the yaw angular velocity of the wind turbine is, the better the output power of the wind turbine can be obtained when the yaw angular velocity is 0.5 °/s 1 °/s 2 °/s. By analyzing the wake velocity, it is found that the smaller the yaw angular velocity is, the greater the larger the wake velocity loss area is.
Analysis and Research on Windproof Deviation of Coastal 500kV Transmission Line Jumpers
Authors: Wu Xiaojie , Fan Guiyou , Fu Zhiwei , Chen Xingbao , Lin Chaohui , Huang Guomin , Shen Xiaoyang , Lin Yuanguo , Zhang Luzhou , Xie Yangbin
Published: May 2023

Based on the current situation of frequent wind deflection faults of 500 kV transmission line jumpers caused by typhoons in coastal areas, this paper proposes a new sectional wind deflection proof post insulator transformation measure by analyzing the advantages and disadvantages of conventional jumper wind deflection transformation measures, which effectively improves the anti typhoon and wind resistance of 500 kV transmission line jumpers. It can save the amount of steel for tower transformation and greatly shorten the transformation outage time. It provides a solution for future coastal transmission line construction and wind deflection prevention reconstruction.
Research on Supraharmonics Suppression Strategy of Distribution Network based on Dynamic Cooperative Control of Multiple Harmonic Sources
Authors: Liu Shaojie , Zhao Yingying , Tian Yue , Fan Yubo , Ye Jifang
Published: May 2023

In view of the increasing number of supraharmonic sources in distribution network and the increasing distortion of power grid waveform, a strategy of supraharmonic suppression in distribution network based on dynamic coordinated control of multi-harmonic sources is proposed. The characteristic harmonic current components related to carrier frequency in the output current of each supraharmonic source are shifted by several angles through carrier phase shifting, so that the total current harmonics of all supraharmonic sources merged into point of common coupling (PCC) are obviously reduced to meet the requirements of PCC supraharmonic control. This strategy dynamically adjusts the phase-shift angle according to the running number of supraharmonic sources to avoid the problem that the harmonics of the remaining supraharmonic sources cannot be cancelled after some supraharmonic sources exit the system. The simulation results show that the supraharmonic suppression strategy based on dynamic cooperative control of multi-harmonic sources in distribution network can significantly suppress the supraharmonic current component and voltage distortion rate of a certain number of parallel points.
The online monitoring method of single-phase grounding fault in medium voltage distribution network based on multi-measuring point information
Authors: Zhang Daolu , Wu Dan , Lin Junhong , Huang Fu
Published: May 2023

To reduce the error of single-phase ground fault and improve the security and stability of distribution network operation, an online monitoring method for single-phase ground fault in a medium voltage distribution network based on multi-measuring point information is proposed. Based on the analysis of single-phase grounding transient characteristics, the fault location is determined from the information of multiple measuring points according to the characteristics analysis results to realize the fault subsection location, identify the fault line section, and improve the location accuracy. Based on the fault location results, fault monitoring is realized through the “four-in-one” intelligent distribution terminal. The experimental results show that the accuracy of the monitoring results of this method is kept above 95%, and the monitoring error value of grounding fault is kept at about 1%, so the monitoring results have high reliability.
Distribution Network Line Loss Calculation Method Considering Distributed Photovoltaic Access
Authors: Zhang Lei , Jing Shuzhi , Wang Yang , Tian Yuntao , Cheng Jin , Liu Xiaobin
Published: May 2023

With access to a high proportion of distributed photovoltaics, the power quality and line loss of distribution networks have become the focus of power grid enterprises. Traditional line loss management does not consider the impact of distributed photovoltaic access, which leads to incomplete line loss calculation methods and management means of distribution network. Therefore, this paper establishes a simulation analysis model of high proportion distributed generation connected to the distribution network and puts forward the overall loss method of the distribution network through theoretical analysis. On this basis, the IEEE 34-node system is used to calculate the impact of different capacities and locations of distributed access on the voltage distribution and line loss of the entire distribution network. The example shows that there is a corresponding relationship between the access capacity of DG and the lowest network loss. When the access capacity of distributed generation is too large, the system’s network loss will increase. Therefore, it is necessary to reasonably select the access capacity of distributed generation. The method proposed in this paper is accurate, and can also take the actual limitations of existing photovoltaic access and developable photovoltaic capacity into account, so it has strong engineering practicability.
Investigation of the Design Conformity of Civil Aircraft Battery System to Airworthiness Items
Authors: Wu Shanyong
Published: May 2023

Due to its material, function, safety, and other characteristics, there are also special requirements in terms of the design and verification of civil aircraft batteries. This paper studies the airworthiness compliance design method of the civil aircraft battery system. First, it introduces the battery technology used in mainstream civil aircraft, obtains specific design requirements by analyzing the airworthiness clauses applicable to battery systems, and then proposes the key issues that need to be considered in the design process of civil aircraft battery systems based on these design requirements. That is to say, the design of a civil aircraft battery system must fully consider the requirements of function, performance, and installation, which are defined in airworthiness regulations, and then it can be used safely on a civil airplane.
Study on the combustion process of the ramjet combustion chamber
Authors: Zhang Tingliang , Zhao Hui , He Lantao , Wang Tianyu
Published: May 2023

To explore the ignition performance of the ramjet combustion chamber, this paper combined the specific structure and working principle of the ramjet to model the ramjet combustion chamber, and carried out numerical simulation research on the flow field characteristics and combustion process of the stable operation of the combustion chamber. The results show that for the blunt-body of the flame stabilizer, the overall flame stability zone is relatively large at low inlet velocity, but the strength of the return zone at low inlet velocity is smaller than that at high speed. The flame stability zone formed at high inlet velocity is more stable and has stronger resistance to external disturbance. When the ratio of oil and gas mixtures is in the flammability limit range, the selection of ignition position has an important influence on the success of ignition. When the high-temperature zone formed by the initial ignition core can be diffused into the reflux zone and maintain sufficient temperature, the ignition can be successful.
Buckling and Post-buckling Analysis of Composite Hat Stiffened Panels under Axial Compression Loads
Authors: Wang Zhe , Wang Binwen , Bao Rui , Chen Xiangming , Liang Qingxianglong , Yu Fei
Published: May 2023

Owing to their unique material design-ability and excellent weight reduction properties of carbon fibre reinforced polymers(CFRP), commercial aircraft OEMs have been innovating design and manufacturing approaches to wider the application of advanced composites. In this paper, the bearing capacity of composite hat-stiffened panels is determined by an improved engineering calculation method and numerical analysis method. The effectiveness of both methods is verified by the test. The advantage of the engineering estimation method is simple and fast, which is suitable for the parametric analysis of the structure in the preliminary design phase. The finite element method can better simulate the test process and is suitable for the comprehensive evaluation of structural strength. The combination of the two methods has a high reference value for rapid design and selection.
Numerical Analysis of Pressure Load on Hypersonic Wing
Authors: Chao Zheng , Jiang Shubo , Zhang Guangming
Published: May 2023

The flight vibration environment of hypersonic vehicles has always been a hot topic in the field of aerospace at home and abroad. In this paper, the simple wing model and the outer flow field grid of the wing are established by using fluent software. A series of environmental parameter conditions are set in the hypersonic flow field, and the steady and unsteady flow fields are analyzed. The distribution characteristics of the pressure load on the wing surface in the hypersonic flow field are obtained. The results show that the pressure load measured at the head position of the wing model is larger, and the pressure load at the fuselage position is smaller and changes more gently. With the increase of Mach number, the pressure load on the wing model will also increase. Then MatLab software is used to convert the time domain curve of wing surface pressure load into a power spectral density curve, which provides load input for subsequent random vibration response simulation on finite element software.
Health Assessment of Mission-oriented TT&C Antenna
Authors: Guo Lei , Xu Jihui , He Weihui
Published: May 2023

To solve the problem that it is difficult to quantitatively evaluate the health status of TT&C antennas and that the health status cannot be effectively associated with the ability to perform tasks, this paper proposes a systematic evaluation method for the health management of aerospace TT&C antennas based on the functional mission of TT&C antennas, which closely associates the equipment health status with the ability to perform tasks. According to the functional mission of equipment, the overall health level is evaluated through the health status of the underlying indicators of the ability to perform tasks and equipment performance. Firstly, the assessment index system of the mission-oriented TT&C antenna is analyzed, and then the assessment of the target is decomposed into the assessment of multiple underlying indicators using the analytic hierarchy process (AHP), which is widely used in health assessment. The quantitative assessment is made according to the specific indicators of the lowest level, and their importance to the target assessment is determined layer by layer, so as to achieve the purpose of assessing the target health status. On this basis, the health level of the TT&C antenna is determined according to the maximum membership principle. The evaluation index system and method have important reference significance for the follow-up test and identification work.
Research on WBS-RBS Oriented Security Risk Assessment Index System for Space Domain Private Network
Authors: Wang Rui
Published: May 2023

To solve the problems such as unclear overall situations, incomplete risk analysis, and lack of targeted evaluation indicators of the security of the special network in the aerospace field, this paper takes the special network in the aerospace field as the research object, uses the WBS-RBS method to analyze the risk of network security, and uses the OSM model to establish an evaluation indicator system for the identified risks, to provide an indicator model for the subsequent security detection and evaluation of the special network in the aerospace field.
Fatigue Life Analysis of Bearing in Oscillatory Applications based on Ncode DesignLife
Authors: Ren Hailun , Zhou Aiguo , Jia Jianjun , Li Zhaohui
Published: May 2023

Aiming at the fatigue life of bearing in oscillatory applications, through the analysis of the equivalent load of each part of bearing in oscillatory applications, the equivalent load of each part is calculated. Taking the 7005 angular contact ball bearing as the research object, the stress changes of each component are obtained through the transient dynamic analysis of the model, the fatigue of the bearing is analyzed based on the stress damage theory, and the damage and fatigue life of the bearing is obtained. The results show that the rolling element of the 7005 bearings is the weak part of failure under the given working condition, and it is more reasonable to design the service life of the shafting structure with an equivalent load of the rolling element, which provides reference measures for improving the service life of the oscillated bearing.
Research on flight path planning method based on genetic ant colony algorithm and Maklink diagram
Authors: Bian Xijian , Zhang Kezhi
Published: May 2023

To reduce the cost of a flight, a calculation method is proposed in this paper, which takes the shortest distance as the goal and avoids the obstacle zone, and controls the turning angle as a constraint. Firstly, the Maklink diagram is used to build the obstacle zone model and establish the relationship between the obstacle zones. Then Dijkstra algorithm is used to construct the initial flight path to form a suboptimal path. Then the genetic ant colony algorithm is used to optimize the obtained suboptimal path. When there is a conflict risk between the two planned paths, the flight altitude of the aircraft on one path is adjusted, and the constraints are checked to form the optimal path. The simulation results show that the method can realize flight path optimization and verify the feasibility of the method.
A Space-ground Joint Target Detection System Based on Artificial Intelligence
Authors: Wang Jinghua , Shi Junqing , Lei Yong , Yao Xinyu , Chen Chen , Dong Xiyan
Published: May 2023

Due to the low efficiency and poor adaptability of template matching in target detection, this paper represents a space-ground joint detection system based on artificial intelligence, which takes advantage of the high computation power of the ground system to train neural networks and utilize the measurement and control channel to update and synchronize the on-orbit system. Based on YOLOv5, an oriented bounding box is used for labeling and training, the angle is considered as a class and the loss for the angle is added to the code. After training the network with the ground system, the weight will be sent to the satellite. This process would repeat once there are new training data that worse the update. Based on the new routine for target detection, the accuracy and robustness are significantly higher than before.
Anomaly detection of satellite telemetry data based on extended dominant sets clustering
Authors: Jin Xin , Wang Hui Quan , Jin Zhong He
Published: May 2023

To mine out anomalies in satellite telemetry data under unsupervised conditions, a cluster-based method is proposed in this paper. Firstly, an extended dominant sets clustering algorithm is proposed to cluster the telemetry data with arbitrary shapes. Secondly, objects that do not belong to any cluster or belong to small clusters are traditionally identified as anomalies. Thirdly, the anomalies in large clusters are detected according to the relative similarity. Finally, the information on anomaly windows in the telemetry sequence is obtained according to the local anomaly rate, which provides more characteristics of the anomalies. Experimental results show that: 1) The proposed extended dominant sets clustering algorithm can deal with the dataset containing multiple and arbitrarily shaped clusters; 2) The introduction of relative similarity increases the AUC values of anomaly detection by 3%~10%; 3) The proposed anomaly detection method can effectively detect the anomalies in magnetometer telemetry data of Tianping-2B satellite. Therefore, the proposed method can achieve anomaly detection of satellite telemetry data under unsupervised conditions, and provide support for improving satellite safety and reliability.
Research on Travelling Gust Field Interpolation for Dynamic Response of the Aircraft
Authors: Jing Zhiwei , Wang Libo , Tang Chu
Published: May 2023

The traveling gust by the explosion has a strong influence on the aircraft’s dynamic response. Previous research often takes the hypothesis that the aircraft is ‘frozen’ at the initial location and focuses on the time interpolation of the traveling gust field. This paper investigates the influence of two traveling gust filed interpolation methods on the aircraft dynamic response. The first one is the ‘frozen field’ interpolation method, and the other one is the ‘spatial field’ interpolation method which considers the time and aircraft location. Simulation results demonstrate that the ‘frozen field’ interpolation method increases the dynamic response of the aircraft.
Analysis and application of deep space exploration satellite telemetry data combined with empirical mode decomposition and ARIMA model
Authors: Liu Di , Cui YunFei , Feng Zhuonan , Wang Yanjuan
Published: May 2023

With China’s deep space exploration program constantly expanding, the number of satellites on-orbit is increasing year by year. The stable operation of satellites in orbit hinges on long-term monitoring and analysis of the telemetry data downloaded from the satellite on the ground, which enables quick detection of any irregularities. If we can grasp the changing trend and operation law of satellite telemetry data, we can monitor and control satellites and reduce losses better. Aiming at a large amount of telemetry data of deep space exploration satellites, the data presents non-stationary and nonlinear characteristics, The time series to be processed is constructed sequentially using the acquired telemetry data, and it is decomposed using the empirical mode decomposition approach. The non-stationary signal is divided into a stationary sequence and the sum of a series of stationary intrinsic mode functions. Then the decomposed sets of results are used as the input of the ARIMA model, and the ARIMA model is constructed to predict the predicted value of each decomposed sequence, and the weighted summation of the predicted values is performed to reconstruct the predicted results. Lastly, actual satellite telemetry data is used to confirm the method’s viability. The experimental findings demonstrate that the model can more successfully anticipate the short-term trend of satellite telemetry data.
Spatial-temporal adaptive network partitioning for urban traffic signal control
Authors: Liu Chang , Yuan Hong , Liu Rui , Lin Li , Zhang Yourong , Huang Kaisheng
Published: May 2023

In response to rapidly growing and diversifying traffic demand, it is necessary to develop a network partitioning method that could achieve real-time global optimal performance and adapt to traffic network evolution. In this paper, an adaptive partitioning method is presented, which achieves optimal partitions at runtime and determines appropriate Time-of-Day breakpoints to update partition results simultaneously. For each time interval, partitioning schemes are firstly assessed in terms of modularity by taking roadway geometry, real-time traffic flow information, and signal timing into account. Two values are attained from the assessment: the maximum modularity of the optimal partition and the modularity obtained from the existing partition. Then the existing partition is updated, provided that the relative deviation of these two values exceeds a given threshold for a certain number of successive time intervals. Experimental results show that the above-mentioned partitioning scheme outperforms some notable traffic control techniques in modularity in the spatial aspect. In the temporal aspect, the updating scheme can well respond to varying traffic conditions and yield significantly higher average modularity.
Estimation Distributed Algorithm to Aid Aircraft Runway Scheduling Problem
Authors: Liu Yingli , Hu Minghua , Su Jiaming
Published: May 2023

In this paper, we proposed a runway sequencing and optimal scheduling method. This includes constructing a flight sequencing model to minimize design delay time for arrival and departure flights and designing flight sequencing rules to obtain large-scale feasible runway usage sequences efficiently. Furthermore, a Kendall-τ distance-based Mallows model is constructed based on the obtained flight sequences. An Estimation Distributed Algorithm (EDA) is used to assign each flight a runway usage time that meets the constraint so that the total delay time is minimized. Finally, it is verified that the method can not only reduce the total delay time of the flight as a whole but also has significant performance and is highly implementable through the analysis of calculation cases.
A short-term highway traffic flow forecasting model based on CNN-LSTM with an attention mechanism
Authors: Ma Feihu , Deng Shiqi , Mei Sang
Published: May 2023

Domestic and foreign scholars have researched traffic flow forecasting and established mature systems; however, these systems are mainly based on normal weather. The influence of weather on traffic flow forecasting is rarely considered in existing studies. Therefore, the correlation between meteorology and traffic flow is analyzed, and an attention mechanism is introduced to improve the ability of the model to extract characteristics of time series data. The results show that the model proposed in this paper is better than other models and the traffic flow forecast using meteorological data is more accurate when an attention mechanism is added.
Optimization of holes routing in hydraulic manifold blocks based on simulated annealing algorithm
Authors: Jia Chunqiang , Li Han , Yu Ling
Published: May 2023

The design of the hydraulic manifold block is time-consuming, laborious, and prone to make mistakes due to the vertical intersection and dense complexity of its internal oil passage network. The mathematical optimization model of this problem is given based on the comprehensive analysis of the structural characteristics and design rules of the internal orifices of the hydraulic manifold block. Using the integrated circuit layout algorithm for reference, an optimization design method of a multi-wire mesh channel network based on routing sequence optimization is proposed and verified by an example. The research results show that the optimization of the connection order between multiple wire networks at both ends and the routing order between multiple wire networks in a single-wire network can not only achieve the optimal design of the connectivity of the single-wire network but also ensure the optimal connectivity result of the entire hole network. At the same time, as the bottom core algorithm of the integrated block layout optimization design, it can provide a powerful technical guarantee for improving the integrated block design level, quality, and automation.
Optimal calculation of the operation strategy of a distributed heating system combining wind, solar and electrical energy
Authors: Zhou Ce , Ma Lirong , Liu Peng
Published: May 2023

In this paper, a distributed combined heating system is proposed, composed of an electrically driven air source heat pump (two-stage compression type), solar collector, wind turbine heater, and thermal storage device. A multi-objective optimization mathematical model is established, aiming to minimize the operating cost and carbon dioxide emission during a certain time. The multi-objective planning problem is used to guide solutions to building heating problems in Northern China. Subsequently, for a specific example, the NSGA2 algorithm is used to solve the calculation. Based on the compromise solution of the two optimization objectives, the optimal operation strategy is determined: the amount of heat generated or stored by each device on a typical day. The optimal operating strategy is as follows. In the low heat load period (9:00-16:00), which coincides with the sunny period, the heat production of the solar collectors and the wind turbine heaters exceeds the heat load, and the storage device stores surplus heat. During peak hours (0:00-9:00, 16:00-24:00), the solar collectors are not activated because the solar irradiance is nearly zero. And at this point, the heat production by the wind turbine heaters fluctuates greatly, and the air source heat pump turns out to be the main heating equipment and the heat storage device to release heat when necessary.
Optimal Dispatch of Multi-energy Microgrid Considering Flexible Resources Aggregation
Authors: Xiang Xinyu , Gong Chengyao , Zong Xingchen , Luo Qing , Xia Tian , Lu Tao
Published: May 2023

Distributing energy has facilitated the interaction between electricity, heating, and gas systems. Aggregating flexible resources in the optimal scheduling process of multi-energy microgrids can promote the complementary coordination of multi-energy systems and reduce useless energy waste. In this paper, flexible resource aggregation analysis is added to the optimal scheduling problem of multi-energy microgrids. Firstly, a resource aggregation model based on Mincowski addition is proposed to fully characterize the schedulable potential of flexible resources. Then, a multi-energy microgrid collaborative optimal scheduling model is established to fully exploit the operational potential of flexible resources. Finally, a numerical example is simulated to verify the validity of the aggregation model and control algorithm above-mentioned, which improves the efficiency and accuracy of optimal control of multi-energy microgrids.
The Investigation of the Mixture Formation and Combustion Characteristic of the Spray-wall Impingement
Authors: Li Jingyuan , Wang Xiaoyang , Yu Hanzhengnan , Liu Yu , An Xiaopan , Ma Kunqi , Liang Yongkai , Xu Hang , Zhang Hao
Published: May 2023

In recent years, investigations into the formation of mixture or combustion characteristics of diesel spray-wall impingement have been summarized. On one hand, the air entrainment strength and fuel concentration distribution in the near-wall area during the spray-wall collision process have been studied. On the other hand, the combustion characteristics of the impinged spray, including ignition and combustion characteristics, have also been discussed. Additionally, the effect of impingement between spray and wall on real diesel engines’ operating condition has been analyzed and summarized. Results showed that increasing the pressure of the injection and shortening the collision distance could enhance the air entrainment strength of spray-wall impingement. Moreover, increasing the injection pressure, shortening the impingement distance, decreasing the environmental pressure, increasing the wall temperature, and reducing the nozzle diameter all improved the mixture formation. Conversely, reducing the environmental temperature, decreasing the nozzle diameter, and increasing the impingement distance all reduced the concentration of soot, and even achieved no soot formation. Under real diesel engine operation conditions, some of the soot formed in the spray-wall collision and deposited on the wall. The structure of these deposits was mainly a simple cluster structure composed of several basic particles, and the porous structure of the deposits was conducive to the oxidation of soot and reduced the deposition rate.
Simultaneous analysis of supercritical carbon dioxide power cycle coupling zeotropic organic Rankine cycle with composition-adjustment and dual-pressure evaporation
Authors: Huang Renlong , Chen Chaoda , Wang Yage , Zhong Tianming
Published: May 2023

A novel cycle is established about the supercritical carbon dioxide power cycle (S-CO2) and the zeotropic organic Rankine cycle (ORC). The thermal efficiency of S-CO2 is superior to the steam Rankine cycle. However, the waste heat released from the expander is not well utilized. The zeotropic ORC with dual-pressure evaporation is considered to be one of the most promising cycles for recovering waste heat. Dual-pressure evaporation of ORC can improve the phase change heat transfer matching in the evaporation section, thus improving the energy conversion efficiency. If the composition of the zeotropic mixture can be adjusted during the dual-pressure evaporation process, the system power performance can be further improved. The supercritical carbon dioxide power cycle coupling the zeotropic organic Rankine cycle with composition adjustment and dual-pressure evaporation (S-CO2/ORC) is proposed for energy utilization efficiency. The influence of different working fluids and exergy destruction analysis is carried out for S-CO2/ORC. The results show that the net power output of the system is the largest, which is 359.79 kW, when R245fa-R236ea is used as the working fluid for the ORC. The analysis of the exergy destruction of S-CO2/ORC using R245fa-R236ea shows that the S-CO2 system accounted for the largest exergy destructions.
Max-Pressure Controller for Networks of Signalized Intersection and simulation study
Authors: Xiong Shuai , Zhu Xiaodong , Meng Weiwei , Guo Liping
Published: May 2023

Urban intersections are faced with complex congestion problems and centralized control system has many drawbacks. To solve this problem, a relatively simple local control method - the maximum pressure (MP) control strategy is studied. Meanwhile, the simulation of the proposed MP control method is conducted. After analyzing the simulation results, it is found that MP control can realize the adaptive change of phase duration. The MP control makes the number of throughput vehicles at a high level and can stabilize the queue length within a certain range, ensuring the stability of the operation of the intersection. The control effect of MP is better than that of the fixed-time control.
Active RCD adaptive voltage balancing control strategy for high-voltage uncontrolled rectifier valve
Authors: Chen Wenhao , Yang Ping , Peng Guoping , Liu Zejian , Zeng Jun , Shi Ben , Wang Hongzhan
Published: May 2023

The voltage balance of the series diodes is the premise to ensure the stable and reliable operation of the high voltage uncontrolled rectifier valve. When traditional RC and RCD voltage balancing methods are applied to high voltage uncontrolled rectifier valves in far-reaching offshore wind farms, the complex and changeable operating environment poses a challenge to the anti-interference of the balance effect of the snubber circuit. In this paper, an active RCD adaptive voltage balancing control strategy with strong anti-interference ability is proposed based on the establishment of the active RCD voltage balancing model of the high voltage uncontrolled rectifier valve. The parameter tuning method of the active RCD snubber circuit is given, and the auto-PID control strategy of the active RCD snubber circuit is proposed according to its nonlinear time-varying characteristics. The simulation example verifies that the active RCD adaptive voltage balancing strategy of the high voltage uncontrolled rectifier valve has strong anti-interference performance, which provides a reference for the design of the high voltage uncontrolled rectifier valve voltage sharing system in the far-reaching offshore wind farm.
A Link Real-time Travel Time Estimation on Speed-time Field Traversing Incorporating LSTM Neural Network
Authors: Chen Shiyi , Pan Yiyong
Published: May 2023

A travel time estimation method based on Speed-time field traversal including LSTM neural network was proposed to increase the real-time and accuracy of travel time estimation. The node departure speed of the traditional piecewise truncated quadratic speed trajectory model was optimized by the road node arrival speed, considering the impact of road conditions on travel time. The node arrival speed was modeled as time series and predicted in the short-term future by combining the LSTM neural network model to construct a spatiotemporally continuous speed trajectory, to estimate the link’s travel time. The method was tested on an actual road and gave considerably improved estimates and results compared to the original method, using LSTM neural network to predict node departure speed and the technique using node arrival speed. According to experimental results, the proposed method performs well in both smooth and crowded traffic circumstances, serving as a benchmark for precise real-time travel time estimation on urban roads.
Integrated Design of Control System for Spaceborne Infrared Imaging Mechanism
Authors: Zhai Yunxuan , Jiu Yuanwei , Chang Xia , Wang Yu , Geng Zhenhua
Published: May 2023

The design method of “centralized acquisition, time-sharing operation and array drive” has been proposed for the integrated and coordinated control of the black-body calibration mechanism, black-body radiation calibration source, focusing mechanism, filter wheel mechanism and thermo-threshold mechanism in an aerospace infrared remote sensor. Compared with the decentralized control of traditional components, this method uses FPGA as the main control chip to effectively realize the integrated function of multi-component control of movable and radiating mechanisms through pulse-width modulation drive control of heater band and semiconductor and servo control of the stepping motor. The independence of the drive array and the stability of the temperature control are verified through experiments, and the feasibility of the design is confirmed. The design reduces the volume, weight and complexity of the product, improves the integration, reliability and versatility of the product, and provides a technical reserve for platform load integration.
MEMS-IMU automatic calibration system design and implementation
Authors: Wang Jingxiao , Liu Ning
Published: May 2023

Aiming at the problems of traditional calibration, long calibration cycles, and low efficiency of traditional error calibration methods for MEMS inertial devices, a MEMS IMU automatic calibration system is proposed. Firstly, the error mechanism of MEMS-IMU is analyzed, the error model is established, and the calibration scheme is designed. Then, the automatic control of the turntable and the automatic data acquisition of MEMS inertial devices are realized by designing the data interaction mechanism between the system equipment. Finally, the least square method is used to identify the model parameters. The experimental results show that this method can meet the requirements of multi-position and multi-rate calibration. After compensation, the relative errors of the MEMS gyroscope and accelerometer are 0.04% and 0.15%, respectively, and the cross-coupling error of the MEMS gyroscope is reduced to about 0.1 °/s. At the same time, the whole calibration process is easy to operate, which greatly shortens the calibration time and improves the calibration efficiency.
Structural design and mechanical analysis for space-borne electronic equipment
Authors: Yin Qifeng , Xue Fei , Shen Li
Published: May 2023

With the development of a new generation of radar performance requirements, the chip integration and module assembly density of onboard electronic equipment have been greatly improved. The integration of the system is becoming more complex. This paper designs a kind of electronic equipment with a superposition structure. Separate functional modules are strung together by a screw. Each module unit has the same sectional size. The conventional cabinet form structure is abandoned. The main contradiction of volume, weight, and reliability is solved well. The mechanical properties of electronic equipment are analyzed by the finite element method, and the structure of the fixed lug is optimized. The result shows that the electronic equipment meets the requirements of structural safety margin. The structural design is safe and reliable.
Kinematic modeling and motion characterization of an articulated mobile robot
Authors: Zhang Tan , Ding Chengjun , Li Xinbao , Zhang Jianing , Xu Yingjie
Published: May 2023

In response to the outstanding problems of poor motion flexibility and poor terrain adaptability of conventional mobile robots in unstructured environments, a multi-vehicle modular articulated mobile robot capable of adapting to complex and variable obstacle terrain was developed by designing and introducing a flexible articulation device. By constructing a kinematic model of the single body module of the robot, integrating the motion constraint relations among the modules, and establishing the overall robot attitude equations, we propose a robot soft motion control method. Based on the analysis of robot motion characteristics under special obstacle terrain, the relationship model between obstacle parameters and robot pose is constructed, and the correction strategy under unilateral unstable motion state is proposed through the analysis of robot motion state under unilateral unstable condition. Theoretical analysis and experimental results show that the robot has good motion flexibility and complex terrain adaptability.
A data-driven approach to fault modeling and diagnosis of brake-by-wire system
Authors: Mei Mingming
Published: May 2023

E-Booster plays an important role in braking safety as the pressure source for vehicle hydraulic systems. According to the design feature of its series controller, the signals on key nodes, which can be directly measured, can be used as the data source for fault diagnosis. In this paper, a deep learning technique of residual 1-D CNN equipped with parallel structure is proposed for fault recognition and classification in a dynamic process. With the help of wavelet transform and probabilistic heat map, it is found that the phase current fault feature is distinct in the frequency domain. In contrast, the uniform demagnetization fault and pressure recession fault are more obvious in the time domain. Therefore, the parallel network structure with a wide and narrow convolutional kernel is used, which can handle multiple complex fault features simultaneously. Simulation models based on both data-driven and mathematical formulations are also established to better fit the actual nonlinear conditions. Finally, the proposed network structure can reach 92.1% classification accuracy compared with the commonly used lightweight 2-D CNN model. It can be concluded that 1-D CNN achieves similar classification results as 2-D CNN with less computational resource consumption.
A search and rescue robot device realization based on ROS operating system combined with visual algorithm
Authors: Cui Jiaqi
Published: May 2023

Aiming at the problem of low accuracy of intelligent devices to find missing people, a search and rescue robot device based on ROS intelligent navigation system was proposed. SolidWorks was used to improve the new mechanical structure that can switch autonomously to different terrain and combined with Yolov5 deep learning algorithm to complete face recognition. Using the stm32 single-chip microcomputer, we adjusted the cascade PID parameters of the motor and simulation to realize the omnidirectional movement control of the robot. Through the analysis and verification of the experimental data, the adaptive ability of the improved robot platform to the terrain was significantly improved. The method can accurately complete the task of face recognition and autonomous navigation, which is practical and improves the accuracy of finding the missing people.
An attitude estimation algorithm for the telescopic arm of the boarding bridge based on YOLOv5 and EPnP
Authors: Chen Weizhuo , Zhang Lijie , Luo Fangrui
Published: May 2023

Aiming at the attitude estimation of the telescopic arm of the boarding bridge in the process of docking with the offshore wind turbine, an attitude estimation algorithm for the telescopic arm of the boarding bridge based on YOLOv5 and EPnP is proposed in this paper. YOLOv5 algorithm is used to detect four marks in the offshore wind turbine logo image, and then the EPnP algorithm is used to solve attitude angles of the telescopic arm relative to the landing port of the offshore wind turbine according to the 2D pixel coordinates of the center point of each mark. The experimental results show that the attitude estimation error of the proposed algorithm is less than 0.4° and the data update frequency of the algorithm implemented in NVIDIA Jetson AGX Xavier is 25Hz, which meets the real-time and accuracy requirements for the attitude detection of the boarding bridge telescopic arm.
Research on High-order Sliding Mode Control Strategy for High Voltage Transmission Line Strip Operation Robot
Authors: Guo Xiyi , Xu Boyu , Zhang Jianfeng , Li Muxuan , Long Jiulong
Published: May 2023

When performing robotic electrical work, the mechanical arm will come into contact with wires, bolts, and gold tools. In order to prevent the robot from being shocked or vibrating excessively during this process, as well as to accurately control the screwing bolt angle issue, the robot force control issue should be taken into account. Based on the theory of higher order sliding mode control for such non-linear systems, a differential observer-based higher order sliding mode control method is proposed in this study. In order to build a type of controller based on the differential observer, the differential observer is used to observe the information of the derivative of the angular velocity and the information of the derivative order sliding variables of the higher-order sliding mode. The outcomes demonstrate the control method’s applicability to powered robots, as well as its ability to successfully suppress the jitter issue associated with conventional sliding mode control and achieve good control performance.
Ripple Voltage Suppression of Dual Active Bridge Converter in Electric Locomotive Using H∞ Loop Shaping Control Method
Authors: He Weiyi , Ma Lei , Cheng Shaokun
Published: May 2023

The next-generation electric locomotive drive system has the problem of double grid frequency ripple voltage in the DC side of a single-phase PWM rectifier. In this paper, the intermediate stage dual-active-bridge DC-DC converter is studied, and an H∞ loop shaping ripple voltage suppression control strategy is proposed to restrain the harmonic voltage and optimize the dynamic and robust performance of the closed-loop system. Firstly, the mathematical model of the DAB closed-loop control system with fluctuating input voltage is established. Then, based on the H∞ loop shaping control theory, the dynamic performance, the ability of ripple voltage suppression, and the robust performance of the system are analyzed in the frequency domain. According to the results, a reasonable compensator is selected to reconstruct the magnitude frequency characteristic curve of the nominal system. After reconstruction, the solution of the robust stability margin of the corrected object is transformed into the H∞ robust control problem under the coprime factor uncertainty. The suboptimal H∞ robust controller is solved to obtain the best robustness boundary of the constructed system. Finally, the H∞ loop shaping ripple voltage suppression controller is obtained by combining the H∞ controller with the compensator. The experimental environment is set up in MATLAB-Simulink software. Compared with the traditional voltage loop control method and the input voltage feedforward control method, the dynamic performance of the proposed control strategy is slightly improved, and while within the allowable robust boundaries of the system, it has better ripple voltage suppression performance. When the system magnitude frequency curve is outside the tolerant robust stability margin, the ripple voltage suppression performance fails, but the harmonic content of output voltage is still far less than the other two control methods. The experiment results also prove the correctness of the theoretical analysis and that the proposed control method is effective and proper.
Impact of leaf phenology on estimates of aboveground biomass density in a deciduous broadleaf forest from simulated GEDI lidar
Authors: Cushman K C , Armston John , Dubayah Ralph , Duncanson Laura , Hancock Steven , Janík David , Král Kamil , Krůček Martin , Minor David M , Tang Hao , Kellner James R
Published: May 2023

The Global Ecosystem Dynamics Investigation (GEDI) is a waveform lidar instrument on the International Space Station used to estimate aboveground biomass density (AGBD) in temperate and tropical forests. Algorithms to predict footprint AGBD from GEDI relative height (RH) metrics were developed from simulated waveforms with leaf-on (growing season) conditions. Leaf-off GEDI data with lower canopy cover are expected to have shorter RH metrics, and are therefore excluded from GEDI’s gridded AGBD products. However, the effects of leaf phenology on RH metric heights, and implications for GEDI footprint AGBD models that can include multiple nonlinear RH predictors, have not been quantified. Here, we test the sensitivity of GEDI data and AGBD predictions to leaf phenology. We simulated GEDI data using high-density drone lidar collected in a temperate mountain forest in the Czech Republic under leaf-off and leaf-on conditions, 51 d apart. We compared simulated GEDI RH metrics and footprint-level AGBD predictions from GEDI Level 4 A models from leaf-off and leaf-on datasets. Mean canopy cover increased by 31% from leaf-off to leaf-on conditions, from 57% to 88%. RH metrics < RH50 were more sensitive to changes in leaf phenology than RH metrics ⩾ RH50. Candidate AGBD models for the deciduous-broadleaf-trees prediction stratum in Europe that were trained using leaf-on measurements exhibited a systematic prediction difference of 0.6%–19% when applied to leaf-off data, as compared to leaf-on predictions. Models with the least systematic prediction difference contained only the highest RH metrics, or contained multiple predictor terms that contained both positive and negative coefficients, such that the difference from systematically shorter leaf-off RH metrics was partially offset among the multiple terms. These results suggest that, with consideration of model choice, leaf-off GEDI data can be suitable for AGBD prediction, which could increase data availability and reduce sampling error in some forests.
The relative role of soil moisture and vapor pressure deficit in affecting the Indian vegetation productivity
Authors: Dubey Nivedita , Ghosh Subimal
Published: May 2023

Atmospheric aridity (vapor pressure deficit, VPD) and soil moisture (SM) deficit limit plant photosynthesis and, thus, affect vegetation carbon uptake. The strong correlation between SM and VPD makes it challenging to delineate their relative contributions to regional vegetation productivity. Addressing this gap is vital to understand the future trajectory of plant productivity in India—the second-highest contributor to global greening. Here, we separate the controls of SM and VPD on the Indian vegetation using statistical and causal analysis. We found that vegetation productivity in India is primarily controlled by SM limitation (87.66% of grids) than VPD limitation (12.34% of grids). Vegetation has a varying association with SM and VPD across different agroecological regions in India. The negative impact of VPD on vegetation carbon uptake is not visible in high-rainfall areas of India. These findings advance our understanding of vegetation dynamics under regional dryness stress and can enhance dynamic vegetation model estimates for India under changing climate scenarios.