bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear modelling and multi-stability characteristics of asymmetric hydro turbine governing system
Authors: Lai Xinjie , Li Dedi , Zong Yue , Huang Huimin 
Published: May 2023

Abstract
The asymmetric hydro turbine governing system (AHTGS) has been widely applied in engineering practice, yet the stability characteristics and nonlinear behaviours of AHTGS are seldom studied. Therefore, the authors are motivated to study the stability characteristics and nonlinear behaviours of AHTGS by using Hopf bifurcation theory. Firstly, the refined nonlinear mathematical model of AHTGS is constructed, which takes account of the nonlinear head loss in asymmetric penstocks. Subsequently, the multi-stability characteristics of AHTGS is revealed based on the refined nonlinear mathematical model by using stable domain. Then, the multi-timescale oscillation phenomenon is revealed, i.e. system dynamic response consists of two subwaves with different frequencies. Moreover, the relationship of the two subwaves and the system multi-stability is investigated. The result indicates that the two supercritical bifurcation lines are emerged and a two-timescale oscillation is generated. The stability of the two-timescale oscillation is determined by the two emerged stable domains. In addition, the cause of high-frequency and low-frequency subwaves has been verified as the natural hydraulic oscillation and hydraulic interference between the hydro turbine generating units, respectively. The overall stability of AHTGS is determined by the intersection area of the two stable domains, therefore the reasonable tuning of control parameters within the comprehensive stable domain is critical to maintain the stability of AHTGS.
Analysis of Transient Recovery Voltage of 500 kV Line Considering Current Limiting Reactor
Authors: Ren Hongtao , Zhang Ying 
Published: May 2023

Abstract
To limit the short-circuit current level, the method of series current, the limiting reactor is used to limit the short-circuit current, and the common access mode of the current limiting reactor is direct access. The series current limiting reactor can effectively limit the short-circuit current in 500kV power system, but after it is connected to the system, it will increase the transient recovery voltage steepness in case of a circuit breaker breaking fault and affect the normal breaking of the circuit breaker. Based on a 500 kV current limiter project, the influence of a lower limit current reactor on the recovery voltage of circuit breaker under different fault conditions is studied by using electromagnetic transient simulation software EMTP. The results show that the transient recovery voltage of the circuit breaker will exceed the standard value after the reactor is connected. When capacitors above 600nF are connected in parallel to the current limiting reactor, the transient recovery voltage could be limited to the standard range.
Analysis of Low Temperature Anti-Cracking Property of Epoxy Materials for Cable Intermediate Joints
Authors: Qiao Jian , Yin Li , Zhang Chong , Yang Wei , Gao Yanfeng , Li Zhenyu , Lu Yi , He Jianfei , Chen Youwen , Lv Yang , Wang Kun , Chen Yun 
Published: May 2023

Abstract
In this paper, multi-channel strain sensors are used to in-situ monitor the changes of strain with temperature under low temperatures for different stress angles in epoxy cladded metal inserts and the low temperature anti-cracking performances of the epoxy materials used for cable intermediate joint were analyzed. Compared with the foreign epoxy EP-0, the self-prepared toughed epoxy EP-1 has higher tensile strength, larger elongation at break and smaller modulus, showing a stronger toughness. The glass transition temperature of EP-0 and EP-1 epoxy materials are approximately the same. Besides, although the epoxy cladded metal inserts for EP-0 and EP-1 were both uncracked and intact when the temperature decreased from 0 to -70 °C, the strain and the stress at the stress angle R2 of EP-0 increased more rapidly with the decrease of the temperature than that of EP-1, which can be inferred that the cracking temperature of EP-0 is lower than that of EP-1. Thus, the low-temperature anti-cracking performance of self-made toughed epoxy material is better than that of commonly used foreign epoxy material.
A Dimensional Reduction Optimization Strategy for Line Voltage cascade Quasi-Z-Source Inverter Based on GRA-PCA-PSO
Authors: Li Zhiyong , Xi Wanting , Cao Yuan , Pu Shiping 
Published: May 2023

Abstract
Compared with traditional inverters, line voltage cascade quasi-Z source inverter (LVC-QZSI) has many advantages, but its power quality problems limit its wide application to some extent. In this paper, voltage ripple and power loss of LVC-QZSI are selected as the optimization objectives to build a multi-objective optimization model of LVC-QZSI. In the optimization process, it is found that the dimension of decision variables is too high, which belongs to a kind of large-scale multi-objective optimization problem. To solve this problem, this paper proposes the dimension reduction and optimization strategy of particle swarm optimization based on gray relation analysis and principal component analysis (GRA-PCA-PSO). GRA-PCA is used to realize the dimension reduction of decision variables, and then PSO based on information entropy is used to optimize the multi-objective optimization model after dimension reduction. Finally, the original optimization parameter values are derived from the eigenvalue matrix obtained from PCA. Compared with the traditional method of decision variable grouping and co-evolution, it reduces the calculation cost and improves the optimization accuracy. Finally, we verify the reliability of the algorithm.
The Impact on Absolute Along-Track Station-Keeping of Coordinate Additional Perturbation
Authors: Liu Qi , Zhao Shuge , Li Xiaoyu , Deng Xuelei , Zhang Zhen 
Published: May 2023

Abstract
The purpose of the current paper is to investigate how the coordinated additional perturbation influences the along-track station-keeping. The absolute along-track station-keeping method has been developed and can achieve high-precision maintenance when the orbits are near-pole in previous studies. The accuracy of station-keeping deteriorates when the orbits are not near-pole. The reason is that the additional perturbation of the Mean Equator Mean Equinox of the J2000.0 (J2000) coordinate system makes a great difference in the absolute station-keeping between different inclinations, which has not been studied before. First, the impact factor model is constructed to measure the influence of the coordinate additional perturbation. Second, the impact factors of different orbits are analyzed and it is found the impact factor increases gradually with the decrease of inclination. Third, how impact factor indicating the accuracy of station-keeping is investigated and coordinate systems are recommended based on the impact factors. Finally, the numerical simulations of station-keeping in the J2000 coordinate system and True Equator Mean Equinox (TEME) coordinate system are carried out. Results show that the TEME coordinate system is more advantageous in the station-keeping mission than J2000 when the orbits are not near-pole.
PID control and simulation of moving mass quadcopter UAV
Authors: Xu Tianfang 
Published: May 2023

Abstract
Based on the quadrotor drones we see today, in this paper, a mass center control mechanism installed on the body is proposed to control the flying attitude of the UAV. The moving mass control technology changes the position of the center of mass by moving the position of the mass block of the system. The technology is used in a wide range of aircraft, from drones to gravity satellites. The moving mass center mechanism mentioned in this paper is composed of three sliding blocks that can slide along the spatial axes and are controlled by a linear motor. The linear motor controls the slider movement to generate the torque along different channel directions, to realize the attitude change of the UAV. In this paper, through the kinematics analysis of the quadrotor UAV, combined with PID control and simulation, finally realized the modification of the UAV’s flight attitude with moving mass technology. The simulation results show that the quadrotor UAV can complete the attitude conversion stably with the help of the mass center control mechanism.
Fatigue life assessment of fuselage panel modification based on flight measurement
Authors: Liu Fu wen , Huang Bo , Xiao Ying Chun , Yang Yu 
Published: May 2023

Abstract
During the modification of the aircraft fuselage panel, the fatigue performance of the structure changes. To ensure the safety and reliability of commercial aircraft, the fatigue life assessment of the modified structure is required. In this paper, the detailed fatigue rating method was used for fatigue assessment. The strain information of the modified structure during the flight was obtained by installing fiber Bragg grating sensors. Through the finite element analysis, the fatigue critical parts were determined and the measured data before modification were converted into the data after modification. The detailed fatigue ratings of the fatigue critical parts were calculated. The fatigue life of the critical parts was evaluated based on the linear fatigue damage cumulative rule. According to the results, the most critical part was determined, which provides a basis for the determination of the modification plan of the fuselage panel.
Helicopter Load Factor Limit Protection Method Based on A Predictive Control Algorithm for Vertical Maneuvering
Authors: Liu Xiaoxiao , Li Pan , Zhu Zhenhua 
Published: May 2023

Abstract
The purpose of this paper is to solve the problem of the helicopter load factor limit exceeding caused by inappropriate pilot control in vertical maneuvering flight. Through the collective stick control power restriction, an load factor limit protection method based on a load factor predictive algorithm is proposed. First, the load factor prediction is realized by the change rate of the collective stick position given by the actuator and the control derivative of the collective stick position to vertical acceleration, and then the vertical control power is restricted according to the predicted load factor, so as to achieve the purpose of helicopter load factor protection.
Application and research of linear ADRC in Buck converter
Authors: Shen Wang , Zhang Xieyan , Xie Yixue 
Published: May 2023

Abstract
This paper takes PWM modulated DC-DC Buck converter as the object to improve the traditional LADRC method. Firstly, the LESO module directly feeds back an error differential signal, which can improve its disturbance observation performance. Secondly, the disturbance differential term is imported to the LESO module to enhance the observation speed of disturbance. Finally, a first-order inertial link is joined to the disturbance estimation channel to suppress the high-frequency noise disturbance caused by the increase in observation bandwidth. By analyzing the frequency response characteristic curves of the improved LADRC method and the conventional LADRC method, it can found that improved LADRC method has preferable disturbance resistance performance. Using Simulink model, experimental consequence confirm the availability and correctness of the optimization method.
Distributed rotorcraft coupling modal parameters influence analysis
Authors: Zhang Guibao , Zhu Yan , Wang Siwen , Sun Fengnan , Cheng Qiyou , Feng Zhizhuang 
Published: May 2023

Abstract
In order to explore the influence mechanism of different parameters on Multi-rotor aircraft dynamic characteristics, Hamilton principle and the theory of medium deformation beam were used to derive the rotors/nacelle/wing coupling structure dynamic equation, and a solution method suitable for the analysis of coupled modal was established. By using literature as an example calculate rotor and wing modal, the error is less than 5% compared with the experimental results in the literature, indicating that the coupling model in this paper is accurate and effective. On this basis, the influences of, nacelle offset, rotor collective pitch, blade center of mass on the coupling modal are studied.
Research on Asynchronous Information Fusion Technology of the Distributed Active/Passive Imaging Detection System
Authors: Gu Yifan , Kang Youwei , Fang Zeyuan , Liao Xin , Tang Shanjun 
Published: May 2023

Abstract
In the process of target cooperative tracking of the distributed multi-imaging detection system, aiming at the problem of asynchronous measurement information from different detectors, a distributed Asynchronous and Heterogeneous Information Matrix Fusion algorithm based on the Cubature Kalman Filter (CKF-AHIMF) is proposed. According to the Local Detector Driven Communication (LDDC) method and CKF nonlinear mapping, IMF distributed fusion algorithm is generalized into nonlinear, asynchronous, and heterogeneous cases to integrate the information from a multi-imaging detection system and to obtain global high-precision target trajectory. Through the digital simulation, it is verified that the CKF-AHIMF algorithm under the LDDC method proposed in this paper is more effective and has higher tracking accuracy than other distributed fusion algorithms in dealing with the problem of target cooperative tracking under asynchronous information from local imaging detectors, which is also valid to implement in precision detection and guidance system.
An Improved Mickens Iterative Method for Nonlinear Aeroelastic analysis of Airfoils with an External Store
Authors: Chen Feixin , Deng Jianxin , Ding Zhenghao , Li Weihua , Xiao Suhua 
Published: May 2023

Abstract
This paper aims to propose a modified Mickens iteration method for analyzing the flutter stability of the nonlinear airfoil with an external storage system. Unlike the regular Mickens approach, the modified form is established by substituting previous frequencies of the limit cycle oscillation (LCO) into unknown ones. Then the algebraic equations governing the LCO amplitude and frequency could keep linear, which might improve the calculation efficiency. The numerical example shows the LCOs obtained easily and accurately. Furthermore, the phase planes of the LCOs are investigated with the wind speed varying. The approach could be applicable to investigate mechanical systems with complicated nonlinearities.
Experimental Research on Vibration Dynamics Performance of Type B Metro Vehicles
Authors: Chen Guanghu , Gong Yanqing , Xie Lei , Liu A’kui , Chen Shaoqiang 
Published: May 2023

Abstract
In recent years, due to the acceleration of urban rail transit construction, the cumulative length of urban rail transit lines in China has also continued to grow. As one of the typical representatives of urban rail transit, the subway is an excellent choice for the general public due to its energy saving, environmental friendliness, large transportation capacity, and high punctuality rate. However, this also imposes stricter requirements on the operational safety and smoothness of subway vehicles. The vibration generated by subway vehicles in operation will affect the riding experience of passengers and subway vehicles to varying degrees. Vibration research is an important part of the research on rail transit vehicles. In this paper, a dynamic performance test of a B-type subway vehicle is carried out. According to GB/T5599-2019 and other standards, the operation safety and stability of the vehicle under no-load and overloaded loads and the vehicle vibration characteristics are studied, which provides reliable experimental data for the subsequent research of the vehicle.
Research on optimization of photovoltaic capacity in the multi-energy complementary power generation system
Authors: Zhang Bozhi , Wei Zirui , Li Kun , Zhou Lixia 
Published: May 2023

Abstract
Multi-energy complementary power generation (MEPG) technology is one of the effective utilization means of renewable energy generation. In this paper, a MEPG system is proposed, which includes a photovoltaic (PV) subsystem and ISCC (solar integrated combined cycle) subsystem. To optimize the capacity of the PV subsystem, the dynamic simulation of the MEPG system is carried out under the condition of operating for 2 hours continuously. By stabilizing the output power of the MEPG system at the target value during the operation, the relatively suitable capacity of the PV subsystem is obtained. The results show that for the MEPG system, the PV subsystem should be less than the capacity of the solar field in the ISCC subsystem.
Analysis Service Process of Aircraft Turnaround Operations by Petri Net
Authors: Zhang Shu-qin , Jiang Wei , Yang Ning , Liu Ying 
Published: May 2023

Abstract
Airport collaborative decision-making has put forward higher requirements for aircraft turnaround operations. In order to improve the efficiency of aircraft turnaround operations, this paper improves the Petri net model based on the characteristics of MATLAB language. It gives the specific steps to analyze the influence of aircraft turnaround operations period on the apron flight viable service route. The experimental analysis shows that the change in passenger cabin cleaning, catering, and air bridge disconnecting within the routine service time does not affect the number of viable service routes and critical operations of aircraft turnaround service. Suppose the time of four operations, the bridge connecting, water clearing, passenger deboarding, and water filling, are respectively set in the interval [1.43, 1.98], [8, 8.7], [10.5, 11] and [8.1, 9.9], the number of viable service routes will only achieve two values. In that case, the bigger one is 4.7543 * 1076 with the 72% generating probability. The other is 3.5715 * 1076, which is 3.11 * 104 times as many as the minimum value obtained by the regular value interval of four operations, improving the quality of the minimum number of viable service routes. The results indicate that setting the time of some aircraft turnaround operations within a reasonable range will improve the number of viable service routes.
Analysis method and application of rotor dynamic balance test for large hydropower units
Authors: Yang Xingfu , Zhang Haiku , Li Guiji , Fu Zhiqi , Tan Xiaoxia , Chen Lei 
Published: May 2023

Abstract
The spindle runout of unit 2 in a hydropower plant seriously exceeded the standard during the startup test, and its main frequency was consistent with the conversion frequency, which did not meet the startup test acceptance specification. Through the analysis of the variable speed test data of the unit, it is judged that the reason for the excessive runout is the mass imbalance of the generator rotor, which affects the vibration of the shafting and the frame. A dynamic balance test analysis method is proposed to determine the counterweight weight and orientation, which is the same centrifugal force with the equivalent in the state. In this method, the weight of the trial counterweight and the total unbalanced mass is calculated by using the trial counterweight empirical formula and dynamic balance equation respectively, and the second counterweight test is carried out after calculation. Through the application in unit 2 of the power plant, the serious problem of excessive runout of the unit can be completely solved. The analysis method of the rotor dynamic unbalance test for large hydropower units proposed in this paper can provide a technical reference for similar problems.
Design and verification of VCU system based on ISO26262
Authors: Wang Xiyang , Li Hongpeng , Xi Wenxia , Zhang Dianming , Guo Wei 
Published: May 2023

Abstract
According to ISO26262 standard, the functional safety analysis of the pure electric vehicle’s concept stage of Vehicle Control Unit (VCU) was carried out. From this, the safety goals and ASIL levels of the VCU are determined. According to the safety analysis method, the functional safety requirements of the VCU at the vehicle level are obtained. At the hardware architecture level, the functional safety design of the VCU’s microcontroller module, storage module, and power supply module is carried out to meet the functional safety development requirements. Carefully consideration of software failures that may occur during VCU software development. These include software architecture design, safety-critical code/program flow monitoring, change management, and safety-critical variables. The fault injection test of the VCU demonstrates the feasibility of this technology.
Visual/inertial odometry with tight coupling of multi-bit pose information
Authors: Jie Xiaohan , Liu Ning 
Published: May 2023

Abstract
To address the problem that the loosely coupled frame pose scale needs to be initialized manually, making the subsequent algorithm less accurate and less real-time, while the tightly coupled OKVIS does not include closed-loop detection and map building, an adaptive vision/inertial odometry method with tightly coupled multi-bit pose information is proposed, incorporating optimized map points to provide more accurate data for the subsequent algorithm, with repositioning, closed-loop detection and global a complete visual/inertial odometry system with repositioning, closed-loop detection, and global posture map optimization functions. The adaptive vision/inertial odometry with tightly coupled multi-location posture information is experimentally validated to have better real-time performance, accuracy, and robustness than the loosely coupled algorithm.
Optimization of Diversion Device and Experiment on Air-assisted Sprayers in Orchards
Authors: Fan Shaohuan , Gao Gaili , Shen Hui 
Published: May 2023

Abstract
In order to improve the velocity distribution of the airflow field generated by the air-assisted sprayer in the orchard, a flow field distribution model of the sprayer air delivery system based on CFD simulation is designed. The airflow field distribution of the air-assisted operation is obtained through FLUENT simulation. The calculation domain includes the internal flow field and external flow field of the fan. The simulation result guides the optimal installation angle of the flow guide device. The installation angle of the upper deflector is 50°, and the installation angle of the lower deflector is 25°, so that the airflow generated by the air-assisted sprayer is mainly concentrated at a height of 0.7–3 m when it reaches the pear tree canopy. The installation angle of the inner deflector 1 and inner deflector 2 is 35°, the installation angles of the inner deflector 3, inner deflector 4, and inner deflector 5 are all 45°, and the average speed is increased by 18.81% in the range of height 1.6–2.4 m. A velocity distribution experiment is designed to measure the airflow velocity to verify the accuracy of the CFD simulation model. The simulation value is basically consistent with the measured value, which provides guidance for optimizing the parameters of the flow guide device.
Robot path planning by integrating improved A* algorithm and DWA algorithm
Authors: Jin Mengqi , Wang Hanxi 
Published: May 2023

Abstract
Traversing many nodes, low search efficiency, path slanting through obstacles, many path redundancy points, and the inability of dynamic real-time obstacle avoidance are all typical problems of A* algorithm. In this paper, A robot path planning method combining improved A* algorithm and DWA algorithm is proposed.The ratio of the distance between the current point and the starting point and the target point is introduced into the heuristic function, and the search efficiency is improved through the optimized heuristic function; the neighborhood search principle is simplified to 5-neighborhood search, and the nodes adjacent to obstacles are deleted to reduce the traversal nodes while avoiding diagonal penetration of obstacles; redundant node improvement method is used to reduce the degree of path transition; finally the path key points of the improved A* algorithm are extracted and DWA algorithm is fused to realize the robot to avoid unknown obstacles. Finally, experiments are carried out on Matlab to prove the feasibility of the new algorithm.