bluuebunny/crossref_metadata_2025_split huggingface dataset:
Second-order kinetic energy-conservative analysis of incompressible turbulence under a collocated grid system
Authors: Suzuki Hiroki , Hasegawa Yutaka , Watanabe Masaya , Tatsuo Ushijima , Mochizuki Shinsuke 
Published: September 2020

Abstract
The study presented in this paper investigates the second-order conservation error of kinetic energy of an incompressible flow under a collocated grid. A collocated grid is often used to numerically analyse the flow around an aerofoil. The kinetic energy conservation error under a collocated grid is often greater than that under a staggered grid. The results of analysis based on coarse computational grids, such as LES analysis, are considerably affected by the kinetic energy conservation error. This study shows the results of numerical analysis in which the kinetic energy has a second-order conservation error under the collocated grid. This higher-order kinetic energy is strictly validated using inviscid flow. Furthermore, the results of conservation errors of higher-order statistics of kinetic energy are discussed in this study. The numerical analysis is then validated using a turbulent channel flow. The statistics obtained by this analysis agree well with those of previous studies in turbulent channel flows.
Design and performance analysis of pneumatic disc brake of a new energy commercial vehicle
Authors: Fu Shichao , Sun Haiming 
Published: September 2020

Abstract
The brake is the key mechanism of automobile braking system, which makes the vehicle reach the expected driving state by outputting braking force to the wheel. SolidWorks was used to model the pneumatic disc brake of EQ1180GEVJ new energy commercial vehicle. The finite element software ANSYS workbench was used to conduct the finite element analysis of the brake disc, brake clamp and bracket, and the stress cloud diagram under the braking condition, as well as the first 10 natural frequencies and the main vibration pattern diagram were obtained. The results show that the maximum deformation of the brake disc is in the lower position on both sides of the brake disc, and the maximum stress is in the position connected with the wheel hub. The maximum stress of the brake clamp is at the connection between the connecting arm and the brake chamber. The maximum stress of the support is at the connection between the support and the suspension. The first ten natural frequencies of the three parts are between 240Hz and 3000Hz. By analysing the mode, we can obtain the position where the mode which is prone to sudden vibration frequency change and the system may generate the maximum vibration amplitude when resonance occurs. The results provide some references for further optimization of disc brake.
Research on the simulation technology of the combined effects of transient thermal shock and a triaxial 6-DOF
Authors: Yao Zemin , Huang Xiaokai , Huang Shouqing , Liu Shouwen 
Published: September 2020

Abstract
During the reentry of a spacecraft, it will encounter extreme environment of transient thermal shock and a triaxial 6-DOF. Currently, there is a lack of experimental verification means. Taking a second power supply as an example, the finite element simulation model is established, and the model is verified by the heat balance test and random vibration modal test. The thermal response distribution of rapid temperature change, low-temperature holding and high-temperature holding phrases is obtained through the transient thermal shock simulation; Based on the multi-stress simulation of the workbench, the stress-strain response distribution under the triaxial 6-DOF random vibration is obtained. According to the principle of stress coupling, the thermal response distribution matrix and stress-strain response distribution matrix are applied to the finite element model of electronic products at the same time, and then the transient thermal shock and the triaxial 6-DOF coupling simulation is realized, which provides a theoretical guidance for test verification of the extreme environment during the reentry of a spacecraft.
Analysis of vibration resistance reliability of directional probe framework for MWD logging system
Authors: Liu Qing , Wu Junjie 
Published: September 2020

Abstract
This paper discusses the failure mode of structure under complex working conditions of oil drilling. The method of selecting the main failure mode of directional probe framework under the condition of vibration is deduced. The calculation of the vibration resistance reliability for the framework of directional probe is simplified. The anti-vibration reliability index of directional probe framework is calculated by an example in this paper. The influence of machining error and additional quality on the vibration resistance reliability of directional probe framework are also analyzed. The results show that the main failure modes of the directional probe framework are different with different additional mass. Therefore, the research results have certain design guidance significance.
The study on lashing ware location of vibration reduction model of detuned blade disc structure
Authors: Wang Lijuan , Yang Guohui 
Published: September 2020

Abstract
The studies on vibration localization of periodic structure are mainly based on displacement modes at present, while the strain modes have not been applied to the research of vibration localization. Consequently, it was imagined to apply the strain modes to vibration localization based on a finite element model of bladed disk with shrouds, and the vibration localization factors based on strain modes and displacement modes were compared with the condition that the bladed disk is mistuning. The result shows that the vibration localization based on strain modes is much more sensitive to stiffness mistuning than the vibration localization based on displacement modes; what’s more, the strain mode shapes are different with the displacement modes at the same mode order. The result is important to the design of periodic structure with snubbing mechanism.
Numerical simulation, verification and experiment validation on hydrodynamic performance and radiated noise properties of skewed propeller
Authors: Ma Fuqiang , Liu Yansen , Mu Lin , Jia Bing 
Published: September 2020

Abstract
Numerical simulation of hydrodynamic performance and radiated noise properties of the standard propeller is carried out by computational fluid dynamics (CFD) approach and acoustic analogy equation, and verifying and validating the numerical result by experiments in cavitation tunnel. Taking Potsdam Propeller Test Case (PPTC) propeller as an example, the geometric model, grid model and numerical simulation boundary conditions are established. The comparison between numerical calculation and experimental results of open water characteristics of propeller, including thrust coefficient, torque coefficient and efficiency shows that the numerical model is reliable. Under the condition of good agreement between numerical simulation and experimental results of unsteady hydrodynamic characteristics, which contains the pressure distribution of blades, cavitation properties, the wake vortex distribution of the propeller, the numerical calculation and characteristic analysis of propeller radiated noise are carried out. The results show that the relation between the radiated noise of the propeller and the inherent structure and the motion state is correlated. The research can provide a theoretical basis for the target detection and recognition based on such characteristics.
Research on the influence of pulse parameters on surface charge of epoxy resin
Authors: Lin Haofan , Tao Ruixiang , Zhou Luyao , Yang Yong , Yu Bing , Liu Shuang 
Published: September 2020

Abstract
The dynamic characteristic of the surface charge on insulating material is an important electrical characteristic, which can effectively reflect the insulation performance of materials. The phenomenon of surface charge accumulation leads to surface discharge and surface flashover. In this paper, the surface charge accumulation and dissipation of epoxy resin under different pulse parameters were studied. The experimental results showed that the increase of pulse frequency intensified the phenomenon of surface charge accumulation and inhibited the process of charge dissipation. Meanwhile, the increase of the number of pulses led to the increase of surface charge accumulation first and then saturation. At the same time, it inhibited the process of surface charge dissipation.
Investigation on the transient stability of hydro generator working with power grid
Authors: Sun Fuchun , Wang Andong , Wang Jihao , Xu Dai , Zhuang Xu 
Published: September 2020

Abstract
Huge hydro-generator is the inevitable development trend of hydro-generator for utilization of water resources. It is very necessary to research the technical issues for 1000MW hydro-generator. Whether the short-circuit faults locate at the generator terminal or the end of transmission line, the transient stability of hydro-generator is calculated and analyzed based on the field-circuit coupling model. Short-circuit fault must be cleared immediately in order that the power system and generator can maintain stable operation, in this paper, fault clearing time limit under different conditions is obtained by mass of simulation. The results obtained in this paper can provide valuable reference for the actual operation of 1000MW hydro-generator, and it is also useful and valuable for the design of protection devices, the dispatching of power grid and the debugging of generator when be connected to power grid.
Partial discharge identification of DC cross-linked polyethylene cables based on GA-BP algorithm
Authors: Wang Luliang , Yang Xu , Jiang Yi , Zhang Jing , Yao Yuhang , Wu Qian 
Published: September 2020

Abstract
In this paper, XLPE DC cables were used to construct three kinds of defects of inner semiconducting layer breakage, internal air gap defect, and insulating surface scratching defect. And their DC PD characteristics were tested under different voltage amplitudes and polarities. The study found that these three defects exhibit different DC partial discharge characteristics and change with voltage amplitude and polarity. Subsequently, two methods were used to identify the type of defect. The recognition rate of the traditional defect type identification method reached 97.1%, and the recognition rate of the optimized defect type identification method based on GA-BP was increased to 98.9%, which solved the problem that the traditional method was affected by the voltage level and polarity, and improved the recognition rate.
Defect simulation and state characteristic analysis of cable joints with tip defects
Authors: Jiang Hang , Cao Junping , Wang Shuyang , Tong Li , Zhou Weijie , Yang Yong 
Published: September 2020

Abstract
In recent years, the breakdown of the body and accessories of high voltage cables has increased gradually. Taking the tip defect of 110 kV high voltage cable joint as an example to carry out electric field simulation analysis, the distribution and change law of electric field under this defect are put forward. Based on full working condition detection platform of high voltage cable, the simulation test of the defect is carried out. The effectiveness of various charged detection methods and on-line monitoring methods has been studied, and the variation rules of cable state under different working conditions have been obtained. The results show that, when tip defect is between stress cone silicon rubber and main insulation of cable body, electric field distortion around the tip shows discharge, and the breakdown potential is 83 kV. The high frequency partial discharge detection method and ultrasonic partial discharge detection method can detect the defects effectively, among which anti-interference ability of high frequency partial discharge detection at the capacitive arm is the best, and detection sensitivity of the grounding current is higher in the on-line monitoring. The thermal efficiency of load current has little effect on development of tip defects. But with the increase of test voltage, the high frequency emission volume increases obviously and breakdown occurs easily at higher voltage.
Research on motion characteristics and stability of 500kV fast mechanical switch
Authors: Huang Leichao , Fang Chun’en , Li Wei , Tang Xiaoyu , Zhang Ning , Chen Junping 
Published: September 2020

Abstract
The key component of fast mechanical switch (FMS) is electromagnetic repulsion mechanism (ERM), and the stability of ERM has an important influence on fault breaking time and breaking performance of hybrid DC circuit breaker (DCCB). In this paper, a FMS based on ERM is designed. In order to improve the stability of the FMS, the key factors affecting the stability of the excitation coil resistance, the inductance of the excitation coil, the capacitance of the energy storage capacitor, the charging voltage and the ambient temperature are analyzed. Then, 2D ERM simulation model is set up and study the above parameters deviation and the change of environmental temperature on the repulsive force driving characteristics. In order to ensure that the ERM moves to 10mm in 2ms, and the time dispersion is less than ±0.2ms. The reasonable variation ranges of each parameter required for the stable action of the ERM and the appropriate working environment temperature are determined. Finally, the developed FMS prototype was tested for opening, temperature rise and consistency, and the test results were consistent with the simulation results.
Simulation study on parameters of steam turbine governing system based on power grid stability analysis
Authors: Wen Libin 
Published: September 2020

Abstract
Limited to the general software model of power grid stability analysis can not be changed and added, the parameter setting of steam turbine regulating system is improper, and it will be difficult to model and simulate if it does not conform to the relevant software model; moreover, improper parameter setting of steam turbine regulating system will also cause large fluctuation of generator output power in the process of unit primary frequency regulation, which will affect the stable operation of power grid. In this paper, through the simulation analysis and experimental research of the turbine governing system, the relevant control parameters are changed and optimized, so that the actual unit governing system model is consistent with the general calculation software model of power grid stability, so as to meet the technical requirements of power grid stability analysis and generator unit access to the grid; at the same time, the stability and rapidity of the unit participation in power grid primary frequency regulation are improved.
Open-circuit fault diagnosis of traction inverter based on improved convolutional neural network
Authors: Liu Jun , Wang Junnian , Yu Wenxin , Wang Zhenheng , Zhong Guang’an 
Published: September 2020

Abstract
In the traction system of high-speed EMUs, the inverter’s Insulated Gate Bipolar Transistor (IGBT) often occurs open-circuit (OC) faults. However, traditional fault diagnosis relies mainly on signal processing to extract fault features, which is susceptible to environmental interference, resulting in poor generalization ability of the model. Aiming at this problem, a fault diagnosis method based on an improved convolutional neural network is proposed. Firstly, the three-phase stator current signal is preprocessed by wavelet domain denoising. Secondly, fault features are independently learned through a convolutional network. Finally, a fully-connected layer is used for fault diagnosis. The experimental results show that this method could resolve the OC fault diagnosis problem of the inverter’s IGBT effectively, and also achieve higher accuracy under the interference of noise, and the diagnosis can be made at 0.01s after the fault occurs.
Research on mppt control method of doubly-fed wind power system based on sliding mode control
Authors: Huang Yong , Jiang Dongmei , Pan Lin 
Published: September 2020

Abstract
In order to solve the problem of maximum wind energy tracking wind speed measurement of wind turbine at present, a new wind energy control algorithm, sliding mode control algorithm, is proposed, which adjusts the speed of fan by sliding mode control, avoids the problem of real-time wind speed measurement in wind speed tracking control, and can respond quickly to the sudden change of wind speed and solve the problem of uncertain inherent parameters of wind speed. The proposed algorithm is compared with the PI control algorithm and the analog 660KW generator, and the effectiveness of the algorithm is verified. Results: the sliding mode control algorithm has good track tracking performance, can shorten the delay time between the actual value and the reference value, and has good performance.
Study on electro-hydraulic control system of advanced support in large section roadway
Authors: Wang Qi , Shi Tao 
Published: September 2020

Abstract
Taking the large cross-section return air roadway of 4201 working face in No.2 panel of Liuzhuang Coal Mine as engineering background, the engineering geological conditions and supporting conditions of roadway were analyzed, and the 3×ZQL2×5200/23/45WD split advanced support was used to support the roadway in the advance support area. On this basis, the design schemes of support pressure monitoring system, automatic deviation adjustment system, environmental monitoring system, remote control system and software control system were analyzed, the subsystems with different functions constitute the electro-hydraulic control system of advanced support. The advanced support has good application effect and can meet the requirements of advanced support and automation control of large cross-section roadway.
Power system reserve scheduling with wind farm integration considering robust security constraints
Authors: Dou Fei , Cheng Jinmin , Wang Weiyuan , Yu Xuan , Xia Kai , Xu Yiqing , Wan Zhendong 
Published: September 2020

Abstract
The fluctuation of real-time wind power output and the capacity limits of transmission network have been identified as bottlenecks to integrate wind power in power system operation. This paper proposes a novel model of robust linear optimization for the reserve scheduling considering the secondary frequency the power network security constraints. In this model, the linearization decision rule is introduced to describe the allocation of the secondary frequency control reserves; the mean value and unsymmetrical interval bound instead of the probability distribution are used to describe the wind power uncertainty. The stochastic robust linear optimization model is converted into a deterministic linear programming, thus achieving the tractability. Case studies are carried out to verify the effectiveness of the proposed method.
Speed optimal method of intelligent network vehicles passing through signalized intersection
Authors: Chen Zhenglong , Chen Jing , Xiao Chun , Li Zhihua 
Published: September 2020

Abstract
Aiming at the problem that the frequent stops and changes of intelligent network vehicles passing through the signalized intersections, speed Optimal method of intelligent network vehicles passing through signalized intersection is proposed in the paper. The position and speed of the intelligent network vehicles are detected by the RSU (Road Side Unit) in real time, the distance of ahead vehicles is controlled by the method. The frequent deceleration of the vehicles passing through the signal intersection is solved effectively, at the same time reducing the vehicles fuel consumption in the running.
Performance comparison of switching losses of SiC DMOS vs Si IGBT
Authors: Bukhari Syed Arslan , Zhang Hongjuan , Bukhari Syed Humza , Iqbal Muhammad Yousaf 
Published: September 2020

Abstract
Silicon Carbide Double Diffused Metal Oxide Semiconductor (SiC-DMOS), having a more comprehensive bandgap, fast switching and low power losses, has been rapidly developed and applied. This paper elaborates a detailed analysis of switching losses by comparing Si IGBT and SiC DMOS under the same voltage parameters and identical conditions. The switch’s characteristics are evaluated and contrasted in various gate resistances. In addition, a gate driver is designed to calculate the switching losses of IGBT and SiC DMOS at different frequencies. Then they are respectively used in the buck converter. The experimental platform is built to test and validate that the SiC DMOS buck converter achieves faster dynamic performance and higher efficiency than Si IGBT.
Fuzzy comprehensive evaluation method of variable weight for power distribution equipment group
Authors: Liu Chenlong 
Published: September 2020

Abstract
The evaluation of equipment group status has some reference value for maintenance strategy optimization and distribution network reliability evaluation. In this paper, the fuzzy evaluation method of variable weight is applied to evaluate the equipment group of power distribution network hierarchically. The importance degree of individual equipment in the evaluation of equipment group is determined by the load size and the importance degree of load borne by the equipment, the network equivalent method is applied to calculate the weight of individual equipment, and the conjoint analysis optimization algorithm is applied to realize dynamic weight variation. A set of transformer winding and casing and a partial 10kV line are taken as examples to verify the effectiveness of the proposed method.
A new discrimination of stator single-phase grounding fault based on multi-dimensional fusion for Powerformer
Authors: Fang Tao , Zhou Yue , Liao Weiping , Su Jue , Xie Wuchao , Xu Jianxiong , Li Huahui , Li Yun , Chen Xinquan , Su Hailin 
Published: September 2020

Abstract
Some existing fusion discriminations are used to identify whether a stator single-phase grounding fault occurs in parallel Powerformers. However, such methods are complicated to operate and require a large amount of training data as support. Therefore, a new discrimination of stator single-phase grounding fault based on multi-dimensional fusion for Powerformer is proposed. Firstly, the faulty Manhattan distance and the sound Manhattan distance about each Powerformer are calculated by the fusion formula of Manhattan distance base on the four features extracted in Powerformer. Then, the sizes of the faulty and sound Manhattan distances about each Powerformer are compared. If the faulty Manhattan distance of the Powerformer is less than the sound Manhattan distance, the Powerformer can be judged as the fault, otherwise, it can be judged as the sound Powerformer. The simulation experiment show that this method does not need a large number of data as support, nor does need to set the threshold value artificially, so it improves the practicability and applicability of the method.
Application of improved wavelet denoising method in low-frequency oscillation analysis of power system
Authors: Liu Mosi , Sun Zhiyuan , Li Mingpo 
Published: September 2020

Abstract
The Prony algorithm has been widely used in low-frequency oscillation analysis of power system due to its good mathematical characteristics. However, the Prony algorithm is very sensitive to noise and requires a high level of input signal. This paper overcomes the shortcomings of traditional soft and hard threshold denoising methods by improving the threshold and threshold function of wavelet denoising. Using the improved wavelet threshold denoising method to preprocess the sampled signal can effectively improve the anti-interference ability of the Prony algorithm. The simulation experiment is performed with MATLAB and the experimental results show the effectiveness of the improved method.