最新刊期
卷 54 ， 期 6 ， 2020
- 摘要：Aiming at the problem of removing accretion layers on the structure surface, two layering models are proposed. Combining theory with experiment, the shear layering of the solid-solid interface under ultrasonic excitation is investigated, and the ultrasonic coupling resonance mechanism of solid-solid interface shear delamination is revealed. The displacement and stress fields in the accretion layer structure under ultrasonic excitation are obtained with Fourier integral transform method, and the solid-solid interface shear stress field is further evaluated. Via numerical integration, the shear stress amplitude at the interface between aluminum and gypsum is calculated, and the influence of excitation frequency and accretion layer thickness on the shear stress amplitude at the interface is achieved. Under the shear layering conditions at the solid-solid interface, a method for selecting ultrasonic layering frequencies is presented. According to the two layering models, the ultrasonic lay关键词：ultrasonic;solid-solid interface shear layering;coupling resonance mechanism276|4|1更新时间：2025-07-09
- 摘要：To deal with the operational risks of integrated electricity and natural gas system brought about by uncertainty of new energy sources, this approach selects a reasonable unit commitment strategy to balance the operational risks and operating costs of the integrated energy system, and constructs a risk-averse integrated energy system unit commitment model. Conditional value-at-risk(CVaR)is introduced into the unit commitment of the integrated energy system to describe the load loss risk of the power system and the natural gas system. The operational risk of the power system and the natural gas system, and mutual influence between them are analy-ed. The piecewise lineari-ation technique is used to lineari-e the natural gas flow equation, and the model is decomposed into the main unit commitment problem, sub-problems for sub-scenario and natural gas load loss risk verification problems by the Benders decomposition algorithm. Compared with the traditional model, the proposed one can effec关键词：risk-averse;integrated electricity and natural gas system;stochastic unit commitment;conditional value-at-risk(CVaR);Benders decomposition229|4|4更新时间：2025-07-09
- 摘要：An improved sliding mode control strategy for permanent magnet synchronous motor(PMSM)using novel reaching law and improved extended state observer is proposed to solve problems of sliding mode chattering, load disturbances and poor control accuracy in traditional sliding mode control system for PMSM. Firstly, a novel reaching law is proposed to solve the problem of sliding mode chattering, and an integral sliding mode controller based on the novel reaching law is designed in speed loop. The chattering suppression effect of the novel reaching law is analy-ed by a difference equation. Secondly, a sliding mode control law is added to the extended state observer to solve the problem of disturbance compensation and to improve the adaptive ability of observer, and an improved extended state observer is designed to estimate disturbance torque. Then, the estimated disturbance torque value is served as a feedforward signal to compensate sliding mode controller in speed loop. The stability of t关键词：permanent magnet synchronous motor(PMSM);novel reaching law;sliding mode control;improved extended state observer252|4|16更新时间：2025-07-09
- 摘要：Aiming at the problems of long distance and high failure rate of hybrid bipolar high voltage direct current(HVDC)transmission lines, a relay protection method suitable for -500 kV hybrid DC transmission lines is proposed. According to the different high and low frequency energy of the signals on the two sides of the boundary element of the hybrid bipolar HVDC transmission line, and considering the type of fault and the influence of the transition resistance on the result, a protection scheme for the transient energy ratio of the active power fault component is constructed. This method adopts wavelet packet transform to decompose the active power fault component to obtain the transient energy of each node. The positive and negative energy ratios are used to distinguish between internal and external faults, the differences between positive and negative energy ratios are taken to distinguish single faults from bipolar ones, and the positive and negative part of the frequency band energy140|4|2更新时间：2025-07-09
- 摘要：A method using a support vector machine algorithm with hybrid kernel function is proposed to solve the problem that it is difficult to evaluate the insulation status of stator bars of large-capacity generators. The method bases on a multi-factor aging test platform to obtain non-destructive characteristic parameters such as absorption ratio, dielectric loss, and dielectric loss increment at different periods that can characteri-e the insulation aging state of a stator bar. Pearson correlation coefficient is calculated to further verify the significant correlation between the above non-destructive parameters and the residual breakdown field strength. Then the support vector machine algorithm with hybrid kernel function is used to establish the mapping relationship between the non-destructive characteristic parameters of the stator bar and the residual breakdown field strength and to predict the residual breakdown field strength of the stator bar. Finally, the main insulation state of th关键词：generator;stator bar;non-destructive parameters;support vector machine138|4|3更新时间：2025-07-09
- 摘要：To study the waveform parameters of the trigger pulse of fast linear transformer driver(FLTD)in the internal triggering brick mode and its influence factors for its practical application and structural optimi-ation, a simulation software of the finite integration technique is used to establish a single-stage FLTD field simulation model and to obtain parameters and influence factors of the trigger pulse. And the parameters are validated on the 1 MA FLTD experimental platform. The simulation results show that the leading edge of the trigger pulse increases from 49.3 ns to 60.1 ns when the inductance of the trigger brick increases from 100 nH to 350 nH. When the grounding resistance of the trigger brick is less than 200 , the trigger voltage increases with the value of the resistance. When the value of the grounding resistance is greater than 200 , increasing the value of the resistance has little effect on the trigger voltage. Changing the impedance of the a-imuthal transmission line in关键词：single-stage FLTD;internal trigger brick mode;electromagnetic model;trigger pulse;influencing factor148|4|2更新时间：2025-07-09
- 摘要：Considering the difficulty of measuring friction coefficient under actual working conditions, a numerical method for calculating the friction coefficient with finite element analysis is proposed to solve the complex friction and wear phenomenon between the slipper and the track at high sliding speeds. By means of W-M function method, MATLAB is used to complete the numerical simulation analysis for surface contour under different roughness, then the function of quickly establishing rough surface model in the finite element is reali-ed via secondary development of ABAQUS. The mathematical model of friction coefficient, pressure and velocity is obtained by analy-ing dynamic variation law of friction coefficient during running of slipper. The simulation results are verified by the pin plate wear experiment and it is found that all errors are below 10%.关键词：coefficient of friction;fractal theory;double rough surface;pin disk wear test175|4|6更新时间：2025-07-09
- 摘要：In view of lack of analysis and optimi-ation of existing hydrostatic spindle motion errors, a dynamic model of the spindle motion error is constructed based on structural parameters, and the laws of dynamic parameters of the spindle rotor at different rotational speeds with an unbalanced mass are quantitatively analy-ed. The mathematical model of the spindle motion error is taken as the objective function, and the spindle system parameters are used as design variables. Genetic algorithm is adopted to optimi-e the motion error of the hydrostatic spindle system. In the single-factor optimi-ation analysis, the optimi-ation efficiency for the radial error motions x and y of the spindle system and the spindle inclination angle - reaches 41.22%, 25.21% and 66.16%, respectively, and the efficiency gets 4.7% during multi-objective optimi-ation. The optimi-ed spindle motion accuracy is significantly improved, and a combination of structural parameters is obtained to heighten the hydraulic stat关键词：ultra-precision machining;hydrostatic spindle;motion error;dynamic parameter;genetic algorithm159|4|1更新时间：2025-07-09
- 摘要：To effectively extract the dynamic stress of the flexible ring gear root of the planetary gear transmission system and comprehensively consider the dynamic characteristics of the system, a calculation for dynamic stress of the ring gear is carried out. In this calculation, taking the coupling relationship of the components of the planetary gear transmission system into account, the translation and torsion coupling dynamic model of the planetary gear transmission system is established, and the dynamic load time history of the system is extracted. The dynamic analysis model of ring gear structure is constructed with finite element method. The meshing area of each tooth in the ring gear is divided into n contact lines, and the dynamic equations of ring gear are decoupled by mode superposition, the dynamic stress of the ring gear root under different loads is calculated with Newmark-- method. The effectiveness of the calculation method is verified by comparing with Kahraman and the other140|4|4更新时间：2025-07-09
- 摘要：To solve the problems of numerical oscillations and divergence in the simulation of compressor process, 4th-order backward difference formula(BDF-4)and classical 4th-order Runge-Kutta(RK-4)method are adopted to analysis the stability of control equations of element volume, and the results of two methods are compared. The analysis results show that a small fluctuation of pressure in the process of suction and exhaust would induce a large fluctuation in the calculation of the mass flow, which would result in a large stiffness of the governing equation and is the key factor to cause numerical oscillations. The results indicate that there is no stability constraint in the calculation using the BDF-4 method, so that the oscillations and divergence due to the numerical stiffness can be avoided. However, the calculation time of the BDF-4 method is 1.7-1.8 times of the RK-4 method at one step, and the simulation accuracy of the BDF-4 method is nearly the same as that of the RK-4 me关键词：compressor;stiffness;backward difference formula152|4|0更新时间：2025-07-09
- 摘要：To explore the mechanism of the interaction between ethanolamine and catalyst in the catalytic dehydrogenation of ethanolamine, the adsorption of ethanolamine on Ni(111)and Cu(111)surfaces with high symmetry sites is investigated by using density functional theory(DFT). The adsorption structure of ethanolamine is optimi-ed at the Top, Bridge, Hcp and Fcc sites, and the adsorption energy, charge transfer and state density of the most stable adsorption configuration are analy-ed comparatively. The results show that the adsorption energy of ethanolamine gets the smallest as the nitrogen atom of the amino group approaching the surface Top site of Ni(111)and Cu(111), and is determined as -1.31 eV and -1.04 eV respectively. At this point, the charge transfer amount of ethanolamine to the metal surface is determined as 0.08e and 0.06e respectively. The internal bond length of ethanolamine is basically unchanged after adsorption, which indicates that the adsorption of ethanolamine on the surfa关键词：first principles;ethanolamine;Ni(111);Cu(111);surface adsorption179|4|1更新时间：2025-07-09
- 摘要：A novel trajectory planning and tracking control method for fully-automatic parking system based on hp-adaptive pseudo spectral method is proposed for application scenarios of parallel parking and vertical parking. Firstly, a mathematical description of the trajectory planning problem is established by comprehensively taking the kinematic constraint of the vehicle, the requirements of obstacle avoidance constraint and the boundary constraint in parking process into account, and then the problem is transformed into a non-linear programming problem using hp-adaptive pseudo spectral method. Then, the trajectory tracking control problem is decoupled into a path tracking control problem and a longitudinal velocity tracking control problem. A non-time reference path tracking fast terminal sliding mode control law is designed based on finite-time stability theory and the longitudinal velocity tracking control law is presented based on the -proportional+integral- smooth switching criterion.214|4|16更新时间：2025-07-09
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