bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotation of the polarization ellipse for broad-band and narrow-band optical pulses. Analytical solutions
Authors: Kasapeteva Z , Dakova A , Slavchev V , Dakova D , Kovachev L 
Published: May 2023

Abstract
In present days the evolution of broad-band laser pulses, propagating in various types of waveguides, has been of a great interest among the scientists. Currently, it is easy for phase-modulated femtosecond pulses the condition Δω≈ω0
to be obtained. It is known that nowadays it is possible also to reach the attosecond region where the spectral bandwidth of the pulse happens to be of order of the carrier frequency also. Light pulses who fulfil this initial condition are called broad-band. On the other hand, the non-fulfilling pulses are the narrow-band ones.
In the present paper it is investigated the parametric interaction of two components of one optical pulse by using the Generalized System of Nonlinear Amplitude Equations (GSNAE). GSNAE was analytically solved. A difference in the period of oscillations of the energy exchange between the two components is found.
Influence of Transition Metal-Nitride Thin Films on the Electrical Contact Resistance of Copper Substrates
Authors: Kotlarski G , Ormanova M , Valkov S , Andreeva A , Bezdushnyi R , Mateev V , Marinova I , Petrov P 
Published: May 2023

Abstract
In the present study, TiN and VN surface coatings are applied on copper substrates, and their influence on the electrical contact resistance (ECR) of the primary material is studied. The coatings are deposited using reactive magnetron sputtering in an Ar/N2 environment. The formed TiN and VN thin films have a thickness of 600 nm and 350 nm, respectively. The preferred crystallographic orientation of both coatings is in the (311) plane. This corresponds to a high crystallite size, high plastic deformations, and high mobility of any structural defects. The I(200)/I(111) ratios of the coatings indicate that the deposited TiN coating is perfectly stoichiometric, and the VN one is hyper stoichiometric, resulting in its’ slightly higher electrical contact resistance. The electrical contact resistance of both coatings is significantly lower compared to that of the pure copper substrate due to their excellent corrosion resistance.
Hardness comparison between Co – Cr metal alloy specimens made by different methods
Authors: Galeva H , Uzunov T , Stoev Y , Sofronov Y , Todorov G 
Published: May 2023

Abstract
The aim of this study is to compare the hardness of Co–Cr metal alloy specimens made by different methods and how it is influenced by multiple temperature changes. Fifty-four samples are made by three different methods and are accordingly divided in three groups – group M (Milling), group LP (Laser Printing) and group LW (Lost Wax), with 18 samples each. All of them contain three subgroups with six samples – metal samples with no thermal cycles (subgroup 1), metal samples with one thermal cycle (subgroup 2) and metal samples with two thermal cycles (subgroup 3). Their Vickers hardness is evaluated by a weight of 1 kg applied for 20 s. The results are presented in tables. The average hardness is the highest for group LP – 509, followed by group M – 440, and for group LW it is 401. For the subgroups, the best results are exhibited by the samples of subgroup 2 – 430, followed by subgroup 3 – 457, and subgroup 1 – 450.
Multi-objective optimization configuration of wind-solar coupling hydrogen production system
Authors: Xu Mingjian , Wang Haocheng , Su Qian , Shi Jiaqi , Li Jiajun 
Published: May 2023

Abstract
The existing research on the wind solar coupling hydrogen generation system lacks the evaluation of factors such as the reliability of power supply to the microgrid system. This paper establishes a multi-objective optimization configuration model of wind-solar coupling hydrogen generation system under grid-connected operation mode for hydrogen generation. From the perspective of system economy and stability analysis, the model optimizes the capacity of the wind power unit, photovoltaic unit, energy storage unit, and hydrogen generation unit to improve the economy and reliability of microgrid operation, to minimize load loss rate, system annual cost, renewable energy power generation loss rate, and energy surplus rate.
Application Research of Power Battery System Fault Identification Method Based on Multi-Classifier Fusion
Authors: Jiang Lu 
Published: May 2023

Abstract
In this paper, a module fault identification method for a power battery system based on multi-classifier fusion is designed. Taking the inverter single tube open circuit fault of the power battery system as an example, the deep learning method of deep neural network and convolutional neural network is used to build the primary diagnosis layer. The fusion method of evidential reasoning rules is used to fuse the primary diagnosis results. The fault data are obtained through simulation of the simulation model, which verifies that the scheme avoids the disadvantage of unstable diagnosis results of a single classifier, and obtains more stable diagnostic results with higher diagnostic accuracy.
Stability Enhancement of Modular Multilevel Converter - High Voltage Direct Current Systems Interacted with Weak Power Grid Based on Current-mode Virtual Inertia Control
Authors: Lin Jinjiao , Kong Xiangping , Gao Lei , Zheng Mingzhong , Li Peng , Wang Chenqing 
Published: May 2023

Abstract
The extensive growth of large-scale flexible high voltage direct current (HVDC) transmission systems compromises the strength of the alternating current (AC) power grid. Sub-synchronous oscillations will likely arise within such flexible HVDC systems, which would significantly threaten the grand electric power system’s stable operation. A current-type enhanced virtual inertia control is proposed to suppress the sub-synchronous oscillations induced by a weak AC power grid in the modular multilevel converter (MMC)-based HVDC systems. Firstly, a small signal model of MMC is established to study the stability of the system under a weak power grid. Focally, a current-mode virtual inertial control is proposed to suppress the AC power grid’s sub-synchronous oscillation by directly taking the grid current as the virtual inertia control variable. Finally, the proposed virtual inertia control approach is verified using both offline and real-time simulation based on the Chongqing-Hubei flexible MMC-HVDC transmission system. The simulation results demonstrate that the proposed current-mode virtual inertia control strategy can efficiently suppress sub-synchronous oscillations in the MMC-HVDC system interacting with a weak AC grid, which enhances the stability and reliability of the power system.
Detection and Location of Series DC Arc Fault in Photovoltaic System Based on VMD
Authors: Guo Feng , Yao Shenghong , Zhang Neng , He Yuchao 
Published: May 2023

Abstract
A large number of connecting wires and electrical contact points exist in large photovoltaic power generation systems, which can easily cause the occurrence of an arc fault. Failure to detect and isolate faults in time will result in serious fire hazards. In the document, a new approach to fault arc monitoring and positioning built on variational mode decomposition is presented for a variety of series DC arc faults in photovoltaic systems. The time and frequency-domain properties of signals collected under different working conditions are obtained by the use of variational mode decomposition (VMD), and the detection of faults by matching changes in features under the same sub-mode. Finally, a 400KW photovoltaic system model is built by Matlab/Simulink for simulation verification. The outcome indicated that the technique is capable of accurately detecting and locating series DC arc faults.
Research on Control Strategy of Hybrid Reactive Power Compensation System for Wind Farms
Authors: Wang Qian , Wu Shouyuan 
Published: May 2023

Abstract
With the increasing scale of wind farms and the increasing proportion of wind power generation in the energy system, the grid has higher and higher requirements for the voltage stability of wind farms. In this paper, we propose a hybrid reactive power compensation system and its control strategy for weakly connected asynchronous wind farms, which can effectively control the compensation cost while improving the continuity of reactive power regulation. It also verifies the correctness and feasibility of the proposed hybrid reactive power compensation system and its control strategy through simulation.
AC and DC voltage control method for off-grid inverter based on matching control
Authors: Kang Pengpeng , Guo Xiaolong , Song Pengfei , Yang Guixing , Zhao Zhiyi 
Published: May 2023

Abstract
Matching control is a new kind of grid-forming control method, compared with droop control and VSM control, it is more stable in a hybrid grid where the synchronous machines and inverters coexist. We introduce the matching control’s concept and developing process briefly, and use the matching control as the inner loop. We propose the VF outer loops to control DC and AC voltage to realize voltage and frequency control in disturbances. Finally, we use Simulink to validate the effectiveness of designed outer loops.
Research on Coordinated Control Strategy Based on DC Bus Voltage of DC Microgrid
Authors: Zhang Meng , Li Jin , Huang Kun 
Published: May 2023

Abstract
DC microgrid is the trend of the future distribution grid. Coordinated control of different types of distributed generation units, energy storage systems, converters, and loads in the DC microgrid to ensure efficient system operation is the focus of current research on the DC microgrid. In this paper, by taking the renovation project of Liangzi Island Electric Hotel in Hubei Province as a case, a coordinated control strategy based on DC bus voltage is proposed for internal power balance and stable system operation of the DC microgrid. Firstly, the operation mode is divided according to the different working conditions of the DC microgrid. The hierarchical droop control is used to associate each operating mode with different DC bus voltage intervals. Then a multi-source coordinated strategy is proposed, and each unit switches its operation mode according to DC bus voltage to maintain bus voltage and ensure power balance. Finally, the simulation is built and run in MATLAB/Simulink to verify the feasibility of the proposed coordinated control strategy.
New High-strength Aluminum Alloy Used for Distribution Circuit Fittings
Authors: Liu Weike , Cao Xianhui , Xie Yi , Hu Yujing , Jiang Peng , Feng Chao , Huang Rong , Wang Jun , Chen Junjun , Li Wenbo 
Published: May 2023

Abstract
Traditional Q235A distribution circuit fittings have high operation energy consumption and galvanized pollution problems, which is not in line with our carbon peaking and carbon neutrality goals. A new type of high-strength aluminum alloy with tensile strength up to 407.3 MPa and elongation at break up to 11% is created. It can be used to replace the traditional Q235A in the preparation of distribution circuit fittings.
Volatility analysis of the flight block time based on the stochastic volatility model
Authors: Sun Ya , Wang Meiyi , Xie Hua 
Published: May 2023

Abstract
To effectively predict the volatility of flight block time, this paper constructs a stochastic volatility model based on actual flight block time data, solves the model parameters by the Markov chain Monte Carlo method, and uses the standard stochastic volatility (SV-N) model and thick-tailed stochastic volatility (SV-T) model to characterize the volatility of flight block time. The results show that the thick-tailed stochastic volatility model is better than the standard stochastic volatility model in describing the volatility of the segment runtime, and the thick-tailed stochastic volatility model is chosen to predict the volatility of the flight block time. Predicting the flight block time volatility in real time can provide a theoretical basis for traffic traveler planning.
Dynamic CFD/CSD Coupling Research for Flexible Micro Aircraft
Authors: Chen Lili , Yang Wenqing , Wang Wei 
Published: May 2023

Abstract
Bio-inspired flapping wing aircraft have made progress in recent years. Flying birds can fly in various low Reynolds numbers (103-105) with high flight stability and maneuvering ability by use of the flexible deformation of skeletal muscle structures or thin-film structure wings. Early studies mainly focused on the aerodynamics and kinematics of the flapping wings, with relatively little research on the flexible structure, and the aerodynamic structure coupling characteristics of micro flappings are still unclear. At present, the focus of research is to evaluate the impact of structural deformation on the aerodynamic characteristics of flexible micro-flapping wing. A CFD/CSD coupling solver are developed and several technical challenges related to the CFD/CSD interface are resolved in this study (CFD/CSD data exchange method and moving mesh generation). The aerodynamic characteristics of five flexible wings with different structural parameters are calculated and compared. The results show that structural parameters play an important role in aerodynamic performance, which also indicates that the potential aerodynamic performance can be improved by the optimal structural design.
Noise Attenuation by Half Flat tip Serrated Trailing Edge in Rotating Blades
Authors: Chen Jieyan , Xie Jinlong , Mun Lee Hsiao 
Published: May 2023

Abstract
Two rotating blade models with different half-flat tip trailing edge serrations were proposed. The flow characteristics and aerodynamic noise were simulated using the large-eddy simulation model and Ffowcs Williams and Hawking’s acoustic analogy, respectively. The effect of half-flat tip trailing edge serrations in reducing noise was investigated. Results showed that the proposed half-flat tip trailing edge serration designs can effectively reduce broadband noise, and the effectiveness of noise reduction was related to the wavelength-to-amplitude ratio of the half-flat tip trailing edge serrations. The Wide-serrated blade had better noise reduction performance, and the local noise reduction according to the simulations can be as high as 3.3 dBA. Besides, it was found that the aerodynamic performance of the rotating blades was not detrimentally affected by the introduction of half-flat tip serration.
The High-speed Aircraft Trajectory Prediction Method Based on Deep Learning Network
Authors: Hu Yu Chuan , Dai Jing , Yi Juan , Fan Zhong Hang 
Published: May 2023

Abstract
This paper applies deep learning technology to the trajectory prediction research of high-speed aircraft in order to predict the medium- and long-term trajectory. Hence, a hybrid model combining the time series convolution neural network (TSCNN) and the long short-term memory (LSTM) is put forward to predict position and velocity of high-speed aircraft. In the TSCNN, convolution operations are used to extract trajectory features of time and space to predict the future trajectory. However, the error will be generated during prediction the process, so the LSTM network can be tapped to correct it by analyzing why it is produced in a bid to address error accumulation. According to simulations conducted, the model can lead to high-precision prediction.
Nozzle Thrust Eccentricity Calculation Based on FLUENT Software
Authors: Hu Yongzheng , Chen Jun , Shen Xiaodong , Dang Jiantao 
Published: May 2023

Abstract
Thrust eccentricity refers to the phenomenon that the thrust vector deviates from the axis of symmetry. This phenomenon will produce lateral force and torque around the aircraft, which affects the normal flight of the aircraft, increases the required control torque, and reduces the density of uncontrolled rockets. There are three sources of thrust eccentricity: mass eccentricity, geometric eccentricity, and aerodynamic eccentricity. The aerodynamic eccentricity is caused by the asymmetrical flow of combustion gas in the nozzle. This paper uses FLUENT software to carry out a numerical simulation of a cone-shaped nozzle. By changing different factors such as the structure of the inner surface of the nozzle and the convergence radius, the influence law of the inner surface structure of different nozzles on the lateral force of the pneumatic eccentricity of the nozzle is explored. The following conclusions were drawn: With the expansion of the expansion half-angle, the second zero point moves toward the nozzle outlet. The relative radius of curvature has little effect on the main thrust of the nozzle but has a certain influence on the eccentricity of its thrust, and as the relative radius of curvature increases, the first and second zeros move toward the throat.
Simulink-Based Simulation of Gas Pilot Servo Actuator for Aviation Ejection Seat
Authors: Zhou Congcong , Chen Jun , Duan Jianing , Wu Ruiqiang 
Published: May 2023

Abstract
The ejection seat needs the ability of rapid attitude adjustment to save lives, and the gas servo steering engine is a feasible scheme for correcting the seat position. The three closed-loop control system of the permanent magnet synchronous motor is built to realize the rotor position loop control of the motor; the working principle of the gas steering gear is analyzed, and the mathematical model of the gas servo system is constructed; Simulink is used to simulate the position of the motor and gas valve; the simulation results show that the steering gear can respond quickly to the control command, and the torque to the rudder surface generated by gas is large enough to meet the needs of the rudder blade to overcome the torque generated by the erosion of the rudder surface and the timeliness of the ejection seat.
Dual-antenna GPS-based UAV Attitude Determination Method and Accuracy Analysis
Authors: Wu Yilun , Sun Chunsheng 
Published: May 2023

Abstract
Accurate attitude information of small-sized unmanned aerial vehicles (UAVs) is required to obtain absolute azimuth information of a target via an airborne electro-optical imaging system. The direct attitude solution method of dual-antenna Global Position System (GPS) is investigated in this paper to address this need. We analyzed the attitude measurement principle of the direct method, gave the error estimation model, and estimated the inner and outer precision through simulation. The simulation results demonstrated that to achieve the requirement of UAV yaw angle error within 1°, the baseline length should be no less than 1 m. The applicability of the model and algorithm was confirmed.
Research on Flight Schedule Optimization Based on Different Runway Operation Modes
Authors: Wang Shuce , Hu Minghua , Zhao Zheng , Shu Jie , Zhu Xuhao 
Published: May 2023

Abstract
The update and iteration of the airport facilities completed in the runway operation system raise a request for more scientific control operation restrictions. In the old, optimized method of flight slot, no consideration was given to the runway operation strategy. As a result, the flight slot failed to meet the operation restriction and would incur unavoidable delays. This paper sets the research objective as the system composed of an apron, runway entrance and exit, and parallel runway. It focuses on matching the corresponding relationship between time and space of flights in the studied system. It establishes three flight slot optimization models to meet the requirements of isolated operation, semi-mixed operation, and mixed operation, respectively. On a practical level, the computer simulation software AirTOp is employed for simulation verification in the example of Wuhan Tianhe Airport. The results show that the delay in the isolation operation mode is reduced by about 59%, the semi-mixed operating mode reduces delays by about 48%, and mixed operating mode delays are reduced by approximately 52%. Therefore, it proves its feasibility of effective reduction in overall delay and its ability to provide decision support for the allocation of the flight time resource in parallel dual runway airports.
The Design of Dynamic Channelization and Signal Control System
Authors: Wang Yanjun , Wang Bing 
Published: May 2023

Abstract
For a long time, the development of urban transportation promotes economic development, however, which brings many urban traffic problems. The significant fluctuation of daily traffic volume has caused serious congestion and queuing at some small or medium-sized intersections. In order to enhance the performance of the, this paper proposes a scheme of dynamic channelization and signal control system which can be adapted to flat and peak. The scheme realizes the conversion of different channelization schemes via LED light strips laid on the road. In order to avoid potential conflicts in the process of scheme transformation, this paper focuses on the transition process from flat peak scheme to peak scheme. This scheme can also realize the systematic adjustment of traffic capacity at intersection, and also has the function of dynamic lane adjustment.
Research on Energy-saving Calculation of Navigational Lighting System Powered by Low Current in Green Airport
Authors: Ma Xiaodan , Li Tuo , Chen Fei , Zhang Lihua 
Published: May 2023

Abstract
The airport navigation lighting system is an important energy-consuming system in the flight area. The annual energy consumption of large and medium-sized airports can reach millions of kilowatt hours. At present, the airport is replacing traditional halogen lamps with LED navigation lighting for energy conservation. For LED lighting under the traditional 6.6 A power supply system, the circuit loss is high, and the overall energy-saving effect of the system is not good. A low-current power supply energy-saving navigation lighting system is proposed. The primary cable, secondary cable, isolation transformer, and auxiliary lighting system in the navigation lighting circuit are studied by performing the energy-saving calculation of navigation lights under low currents. By building a set of navigation lighting systems to conduct energy consumption experiments and comparing them with theoretical calculations, a calculation model is proposed to provide a basis for energy-saving calculations for the application of a low-current power supply navigation lighting system.
Analysis of single-phase grounding fault and its protection in the medium and low voltage distribution system
Authors: Jiang Chongran , Huang Yixiang , Xue Jiangyu 
Published: May 2023

Abstract
The single-phase ground fault of the medium and low voltage distribution system occurs most frequently in the distribution network. The fault should be eliminated in a short time. The single-phase ground short circuit fault that occurs when the neutral point of the power supply is not directly grounded in the medium and low voltage distribution network should be simulated and analyzed. The study seeks to understand the trend of voltage and current as well as the changes of its amplitude and phase when the fault occurs, which are consistent with the theoretical calculation and analysis. According to the analysis of single-phase grounding fault based on the simulated data, the acquisition of zero sequence current, the protection configuration, and the method of setting the point are discussed.
Research on bridge high-resolution optical fiber temperature sensing technology suitable for the low-temperature environment
Authors: Li Chen , Zho Liguo , Fu Zhipeng 
Published: May 2023

Abstract
An improved bridge Fiber Bragg Grating (FBG) temperature sensor technology is presented in this paper. The sensitivity and stability of the material and structure on the wavelength of the FBG are studied theoretically and experimentally. Compared with the traditional bridge temperature monitoring technology, the new sensor technology can adapt to a low-temperature environment and has high resolution. In order to verify the technology, experimental verification is carried out on the basis of theoretical analysis. The results show that the sensitivity of the new optical fiber temperature sensor is about 22 pm/°C, twice that of the bare raster, and shows good stability.