最新刊期
卷 58 ， 期 6 ， 2024
- 摘要：In order to solve the problem that the basic tracker is prone to tracking failure in long-term tracking scenarios such as occlusion and out of view, a long-term tracking algorithm for unmanned aerial vehicle(UAV)based on local-global region redetection is proposed. The basic filter is designed, and the high-confidence samples are combined with it, and the adaptive spatio-temporal regularization is integrated to solve the filter degradation problem and improve the robustness of the model and its performance in complex scenarios. The filter update strategy is optimized, and the adaptive update is performed by evaluating the tracking results. A fast scale filter is designed to solve the problem of scale change in the tracking process. A local-global region redetection mechanism is designed. When the tracking fails, the re-detector is started to recover the tracking target and the local region re-detection is completed first. If the tracking recovery fails, the global region re-detector is used to continue to recover the target tracking state. The experimental results show that the precision and accuracy of the proposed algorithm on the UAV20L data set can reach 0.724 and 0.621 respectively, representing improvement of 25.9% and 20.6% respectively compared with the STRCF algorithm. Compared with the similar mainstream algorithms, the tracking effect of the algorithm is improved, which proves its effectiveness.关键词：unmanned aerial vehicle;long-term tracking;correlation filter;heavy detector;fast scale filtering;high confidence541|19|0更新时间：2025-07-28
- 摘要：Aiming at the limited storage and computing resources of the embedded computing platform of self-driving vehicles, the uncertainty of future trajectory of the vehicle, and the complex and changeable surrounding environment information, a lightweight multimodal vehicle trajectory prediction algorithm(CAM-MobileNeXt)based on MobileNeXt is proposed. Firstly, a vehicle trajectory prediction model with fewer parameters and computations is constructed based on the MobileNeXt lightweight framework. Secondly, the trajectory prediction is adjusted from unimodal to multimodal to predict multiple potential future trajectories that may exist for the target vehicle. Finally, attention mechanism is introduced to enable the system to screen out important information and efficiently allocate limited storage and computing resources. In experiments conducted on the Lyft dataset for Level 5 autonomous vehicle trajectories, the results show that the proposed algorithm exhibits lower parameter and computational requirements, while outperforming the Lyft baseline method, ResNet50, in predictive performance. Compared with MobileNeXt, the proposed algorithm has an 11.9% reduction in loss values on the Lyft dataset. It also exhibits a decrease of 7.4% in final displacement error and an 11.4% reduction in average displacement error. The proposed algorithm is suitable to be deployed on the embedded computing platform of self-driving vehicles, and performs accurate multi-modal trajectory prediction for the surrounding vehicles to ensure the safe driving of self-driving vehicles, indicating good application prospects.关键词：vehicle trajectory prediction;lightweight network;multi-modal;attention mechanism213|10|0更新时间：2025-07-28
- 摘要：Traditional BP neural network PID(BP-PID)control has a slow convergence speed due to its random initial weights, resulting in significant errors in the early stages of control. This paper focuses on the initial weight optimization problem of BP neural network, establishes a servo three loop model of the ball screw feed system, designs a BP-PID controller, and proposes a second-order oscillation chaotic mapping particle swarm optimization algorithm(SCMPSO)to optimize the BP-PID controller of the ball screw feed system. Firstly, the chaotic mapping initializes the particle position, making the particles evenly distributed in space and increasing the diversity of particle solutions. Then, a nonlinear cosine adaptive inertia weight is proposed to balance the global search ability and local search ability of the algorithm. Finally, a second-order oscillation link is introduced in the algorithm, which can timely jump out of the local optimal solution in the face of sudden multi peak interference. The results show that when external interference is added, the average displacement error of SCMPSO-BP-PID during the forward feed period is 0.013 mm, which is about 45.8%, 55.2%, and 61.7% higher than the three control strategies of SAWPSO-BP-PID, LDWPSO-BP-PID, and PSO-BP-PID, respectively. When step response is added, the maximum overshoot of SCMPSO-BP-PID is only 0.029, and the system adjustment time and peak time are significantly improved compared with the three control strategies, representing high control accuracy and stability.关键词：ball screw;control;chaos mapping;second-order oscillatory particle swarm136|15|0更新时间：2025-07-28
- 摘要：Aiming at the problems of low recognition accuracy of multi-target SSVEP signals and suppression of the characteristics of signal while the linear recognition method suppresses noise, this paper proposes a nonlinear multi-objective SSVEP signal recognition algorithm based on the noise reduction characteristics of empirical mode decomposition, Duffing chaotic system's sensitivity to weak periodic signals and the immune characteristics of noise. First, multi-channel SSVEP signals are integrated into single-channel signals by using the co-average reference algorithm. Then, the phase spectrum of SSVEP signal is obtained by Fourier transform, and the phase is added to the periodic dynamics of Duffing chaotic system. After empirical mode decomposition noise reduction, the first eigenmode function obtained is input into Duffing chaotic system, and the amplitude of each target stimulus frequency is solved by using the chaotic system state discrimination method based on spectral difference. Finally, the stimulus target was determined according to the amplitude of the maximum stimulus frequency and multi-target SSVEP signals are recognized. The results show that the average recognition accuracy of the proposed nonlinear signal processing method is 7.3% higher than that of typical correlation analysis. The information transmission rate increases by 3.84 bit/min. The method provides a new direction for exploring nonlinear SSVEP signal decoding algorithms.关键词：steady-state visual evoked potential signals;Duffing chaos system;nonlinear signal processing;empirical mode decomposition65|31|0更新时间：2025-07-28
- 摘要：Aiming at the problem that the high pressure common-rail diesel engine control unit(ECU)is highly dependent on imported chips and lack of independence, an ECU scheme based on fully domestic chips is proposed. The domestic micro-controller named GD32F450 produced by Gigadevice is adopted as the core of engine data sampling, processing, storage and control tasks. The Boost circuit is employed to provide the peak current of diesel injector. A double-side drive circuit with current feed-back functional module is designed using domestic discrete electrical devices and the drive current of the diesel injectors is controlled in the way of closed-loop without imported application specific integrated chip. Moreover, the bottom driving software of high pressure common-rail diesel engine is developed based on FreeRTOS and the execution period of different tasks has been precisely controlled. Finally, the ECU scheme is verified by experiments. The results show that the developed domestic ECU of a high pressure common-rail diesel engine proposed in this paper is full-featured and works stable. Additionally, the typical peak current and hold current of the double-side drive circuit is 22 A and 10 A, respectively. The minimum interval time of multi-injection is 200 μs and it is comparable to the Bosch system in terms of the multi-injection characteristics. The tasks execution period is controlled precisely and the bottom driving software has good real-time performance at varying engine speeds. This research confirms that the feasibility of the high pressure common-rail diesel engine ECU scheme based on fully domestic chips and provides a reference for promoting the self-developed engine ECU technology.关键词：high-pressure common rail diesel engine;engine control unit;domestic chips;underlying software;FreeRTOS operating system88|9|0更新时间：2025-07-28
- 摘要：To improve the dynamic performance of multi-stage labyrinth seal on turbine shaft, the structure design and performance evaluation of anti-swirl and vibration suppression are proposed for a new type of anti-swirl brake with upstream rotor-step in two-stage labyrinth seal with staggered teeth. Firstly, four types of anti-swirl brakes for two-stage staggered-tooth labyrinth seal are designed in this paper. In addition, a dynamic calculation model of labyrinth seal with “virtual bypass boundary” is established to achieve accurate simulation in the pressure field and high swirl velocity field. Then, a transient computational fluid dynamic CFD-based perturbation method based on the multiple-frequency elliptical-orbit rotor whirling model is adopted to analyze the leakage characteristics and dynamic characteristic coefficients of labyrinth seal with various anti-swirl brakes. Finally, the performance of anti-swirl and vibration suppression is elucidated by analyzing swirl velocity development, velocity field and dynamic pressure distribution of labyrinth seal. The results show that the labyrinth seal without anti-swirl brake has the lowest leakage, and the addition of the one-stage traditional anti-swirl brake or the one-stage anti-swirl brake with upstream rotor-step will reduce the number of seal teeth, resulting in the increase of seal leakage(by about 4.5%). Compared with the one-stage anti-swirl brake, the two-stage anti-swirl brake can further increase the leakage by 5.5%. Compared with the traditional anti-swirl brake, the swirl brake with upstream rotor-step can decrease cross-coupled stiffness and increase the effective damping. Compared with the one-stage anti-swirl brake, the cross-coupled stiffness of two-stage anti-swirl brake can be further reduced and the direct damping can be increased, so the effective damping can be significantly increased. Installing the upstream rotor-step on the basis of the traditional anti-swirl brake can improve the anti-swirl performance and two-stage anti-swirl brake can effectively suppress the development of swirl in the downstream of the seal. The research results show that compared with the one-stage anti-swirl brake, the multi-stage anti-swirl brake has better performance of improving the dynamic characteristics and suppressing the vibration.关键词：labyrinth seal;leakage characteristic;rotordynamic characteristic;swirl brake61|11|0更新时间：2025-07-28
- 摘要：Aiming at the problem of secondary flow development and cooling effect deviation from the design value caused by the actual mix condition between combustor and turbine coolant jets, comprehensively considering the combustor louver coolant and the turbine double-row hole jets, the coolant mix mechanism at combustor-turbine interface is numerically studied in this paper, and its influence on the cooling and flow characteristics of turbine vane endwall is analyzed too. The results show that the majority of the louver coolant is entrained by the cavity vortex to develop downstream across the double-row hole jets, and the double-row hole jets are largely entrained by the horseshoe vortex to develop on the outer side of cavity vortex. At low double-row hole blowing ratios(Mh=0.5 and 1.0), the horseshoe vortices lead to a wedge-shaped high cooling effectiveness region, and the attachment and separation side of cavity vortices lead to high and low cooling effectiveness regions, respectively. With the increase of louver blowing ratio, the cavity vortex is weakened, and the cooling effectiveness at wedge-shaped region core increases. At high double-row hole blowing ratio(Mh=1.5), the hole jets can partly flow across the horseshoe vortex, and the vane endwall can be fully covered. With the increase of louver coolant blowing ratio from 0.5 to 1.5, the averaged cooling effectiveness of the vane endwall increases from 0.4 to 0.63. This study can provide a theoretical foundation for the design of turbine vane endwall cooling layout considering the actual flow mixing conditions at the combustor-turbine interface.关键词：turbine vane;endwall;combustor louver coolant;double-row hole jet;film cooling157|23|0更新时间：2025-07-28
- 摘要：To analyze the effects of surface roughness of flow passage component on cryogenic turbopump performance and explain the influence mechanism of surface roughness on rotor-stator centripetal flow, a cryogenic turbopump made of shrouded impeller produced by additive manufacturing is selected as the research object, and the experimental tests and numerical calculations on the performance of cryogenic turbopump are carried out taking into consideration the influence of thermodynamic effects and using liquid nitrogen as the pressurizing and conveying medium. The results show that when the test working condition is in the range of 13 500 to 26 000 r/min, the values of outlet pressure and temperature rise obtained by numerical calculation are fitted with the test data after considering the effects of the surface roughness, compared with the numerical results obtained from smooth wall setting. As the values of the impeller and volute surface roughness increase to 36 μm, the head coefficient and efficiency decrease by 9.1% and 10.6%, respectively. The axial thrust acting on the impeller decreases significantly by 25.8%, after increasing the values of the rotor-stator surface roughness from 0 to 20 μm. The study provides a theoretical foundation for revealing the influence of surface roughness on cryogenic turbopump flow characteristics and zoned controlling the surface quality of the turbopump flow passage components.关键词：turbopump;surface roughness;rotor-stator cavity;thermodynamic effects;axial thrust64|19|0更新时间：2025-07-28
- 摘要：To address the issues of low energy efficiency of multi-flow evaporator caused by non-uniform distribution of vapor-liquid two-phase flow in refrigeration system, and unreasonable design of distributor structure, the vapor-liquid two-phase flow model of refrigerant in distributor is established based on hexahedral grid and Euler-Euler model. The flow characteristics of refrigerant in distributor is analyzed in detail, and the effects of parameters such as cavity height, cavity diameter and insertion depth of branch on the non-uniformity of distribution under different conditions are explored. Furthermore, sensitivity analysis and parametric optimization are conducted using Taguchi method, and the contribution ratios and optimal parameter combination are obtained. The simulation results indicate that as the height and diameter of the cavity increase, the mixing effect of vapor and liquid is improved, and the non-uniformity gradually decreases. As the insertion depth increases, the non-uniformity first decreases and then increases, with an optimal insertion depth of 5 mm. With the mass flow rate increases, the contribution ratios of cavity height and insertion depth gradually increase, while the contribution ratio of cavity diameter gradually decreases, indicating that the dependence of distribution uniformity on cavity diameter decreases. Compared with the base case, the non-uniformity of the optimal parameter combination decreases by 6.6% to 19.3%. This research provides a theoretical foundation and data support for inhibiting the phase separation of vapor-liquid two-phase flow and design of distributor structure.关键词：distributor;vapor-liquid two-phase flow;non-uniformity;sensitivity analysis;parametric optimization83|12|0更新时间：2025-07-28
- 摘要：In order to study the influence of rib height to channel height ratio(e/H), rib spacing to rib height ratio(P/e)and rib angle(α)on the flow and heat transfer characteristics of ribbed U-type channels, the channel wall surface temperature distribution is measured using copper plate method combining thermocouple. Experimental study of the heat transfer characteristics on the surface of ribbed U-type channel with 6 different rib parameters is carried out. The ribbed channel has a square cross section, and the Reynolds number in this experiment is from 5.0×103 to 1.0×105. The experimental results show that with the increase of the e/H and Reynolds number, the convective heat transfer coefficient of the ribbed channel gradually increases, but the corresponding pressure loss increases significantly. As the e/H increases from 0.08 to 0.12, the friction factor of the channel almost doubles. For channel with e/H=0.08, among the three cases with the P/e being 6, 8, and 10, the convective heat transfer coefficient and pressure loss are highest when the ratio is 8. The angled rib can further enhance the convective heat transfer in ribbed channels compared to the 90° orthogonal rib. Additionally, the 75° rib is slightly more effective than the 60° rib. Within the experimental parameter range, the convective heat transfer coefficient is 1.9—3.0 times that of the smooth channel, and the drag coefficient is about 4—6 times that of the smooth channel. Considering heat transfer and flow resistance comprehensively, under the conditions of e/H=0.08, P/e=8, and α=45°, the thermal performance is the best.关键词：turbine vane;internal cooling;ribbed channel;convective heat transfer75|27|0更新时间：2025-07-28
- 摘要：In order to facilitate the design and research of gas turbine blade leading edge compound impingement/film cooling, a flow network coupling method is proposed. The flow network calculation program for blade cooling design is programmed with Python and verified by the experimental data of impingement cooling. Combined with ANSYS CFX, the flow network coupling design and computing platform for blade leading edge compound impingement and film cooling is built, and the flow network model for the internal cooling calculation is designed. Meanwhile, the film cooling correction method for flow network coupling program is developed. Numerical simulations are conducted after turbulence model verification and grid independence test, then results are compared with that of the home-made code, and reliability of the home-made code is verified by conjugate numerical study. The results show that the flow network model has good simulation accuracy, and can be used for the internal flow calculation during the flow network coupling. The relative difference of the averaged film cooling effectiveness calculated by the film cooling corrected flow network method and the CFD is between 2.18% and 12.2%, which verifies the reliability of the film cooling correction. The flow network coupling result is consistent with the CFD conjugated study. The blade temperature distribution calculated by the two methods is consistent with each other, but time needs for the flow network coupling calculation is only 1/18 of the CFD conjugated study, that is a massive time saver. Consequently, flow network coupling method can be applied to the design and research of blade leading edge compound impingement/film cooling.关键词：compound impingement and film cooling;flow network calculation;flow network coupling;film cooling correction82|23|0更新时间：2025-07-28
- 摘要：To explore the effect of plasma actuation on tip leakage flow, ring-type dielectric barrier discharge plasma model is proposed based on unsymmetrical electrodes dielectric barrier discharge plasma model in this paper. Blade tip leakage flow characteristics on a gas turbine is numerically studied with three plasma actuation voltage(9, 13, 17 kV)and three actuation frequency(8, 10, 12 kHz)by implementing plasma actuation forces into the momentum equations of Reynolds-averaged Navier-Stokes equations. The results show that the pressure distribution has been changed in the tip clearance by ring-type plasma actuation. The mainstream of pressure side is obstructed by strong vortex structure which is generated by plasma actuation in tip clearance and both sides of the tip. The tip leakage flow is suppressed effectively. When the actuation frequency is constant, the total pressure loss caused by the tip leakage flow decreases with the increase of the actuation voltage, but excessively high actuation voltage will cause additional induced vortex loss. When the actuation voltage remains unchanged, the increase of the actuation frequency has little effect on the high pressure region of the tip clearance and the induced vortices on both sides of the tip are enhanced and the adjacent passage vortices are squeezed. The area-average total pressure loss on 120% axial chord passage section is further reduced. The actuation voltage of 13 kV and actuation frequency of 12 kHz has the lowest total pressure loss coefficient on 120% axial chord passage section, which is 16.12% lower than no plasma actuation. The influence law of plasma actuation voltage and actuation frequency on the tip flow characteristics and aerodynamic performance is clarified in this paper.关键词：turbine blade;plasma actuation;tip leakage flow;aerodynamic performance118|24|0更新时间：2025-07-28
- 摘要：Film cooling and heat transfer performance on the squealer tip with different degrees of cooling-hole blockage are investigated using numerical methods. The film cooling effectiveness and heat transfer coefficient distribution on the squealer tip are obtained under three blowing ratios(M=0.5, 1.0, and 1.5)and five different blockage ratios(B=0, 0.2, 0.4, 0.6, and 0.8). The results show that the cooling-hole blockage causes decrease of film cooling effect and increase of thermal load on the squealer tip. The film cooling effect and heat transfer performance on the squealer tip are deteriorated with increasing the blockage ratio. The blockage in film cooling holes significantly alters the flow structures in the squealer tip gap. With cooling-hole blockage, the lift-off effect of coolant in the squealer cavity will be aggravated, resulting in earlier leave of cooling flow from the squealer cavity. Generally, the blowing ratio is an important factor that affects the heat transfer and film cooling effect on the squealer tip under blockage conditions. Compared with the unblocked cases, the area-averaged film cooling effectiveness on the squealer tip decreases by 64.88%, and the heat transfer coefficient increases by 13.01%, at blowing ratio M=1.0 and blockage ratio B=0.8. Reducing the blowing ratio is conducive to the improvement of film cooling effectiveness on the squealer tip with small blockage ratio. The area-averaged film cooling effectiveness on the squealer tip only decreases by 6.82% at blowing ratio M=0.5 and blocking ratio B=0.4. However, in the case of small blow ratio, for example M=0.5, the film cooling effect on the squealer tip is deteriorated significantly under the condition of large blockage ratio. At blowing ratio M=0.5 and blocking ratio B=0.8, the area-averaged film cooling effectiveness on the squealer tip decreases by 82.09% compared with the unblocked case. The increase in blowing ratio can improve the film cooling effect on the squealer tip with large blockage ratio. Compared with the unblocked case, the area-averaged film cooling effectiveness on the squealer tip only decreases by 51.34% and the heat transfer coefficient increases by 11.52% at blowing ratio M=1.5 and blockage ratio B=0.8.关键词：gas turbine;squealer tip;hole blockage;film cooling;heat transfer;blowing ratio39|25|0更新时间：2025-07-28
- 摘要：In order to clarify the spray morphology and flame development characteristics of dimethyl ether(DME)and methanol dual direct injection under high injection pressure conditions, the spray and combustion characteristics of methanol and DME are compared and studied based on the schlieren method by using high-speed camera and high-temperature and high-pressure constant volume bomb. In the experiment, the injection pressure is set to 60 MPa, 80 MPa and 100 MPa, the ambient pressure is set to 0.2 MPa and 4 MPa, and the ambient temperature is 500 K and 800 K, respectively. The results show that under 0.2 MPa ambient pressure, the gas phase and liquid phase penetration distance and the spray projection area of DME are smaller than those of methanol, while the result is on the contrary under 4 MPa ambient pressure, but the proportion of DME liquid phase spray penetration distance and spray area are less than those of methanol under the same working conditions, that is, the atomization effect of DME is better than that of methanol under the two ambient pressure conditions. With the increase of injection pressure, the flame floating length of dual direct injection spray increases, and the flame floating length under 100 MPa injection pressure increases by about 26.42% compared with 60 MPa, the ignition delay period becomes longer, and the sum of KL decreases by 44.05%. With the increase of the DME injection delay time, the development of dual direct injection spray formed by the collision of the two sprays becomes faster, the spray area becomes smaller first and then larger, and the ignition delay period becomes longer, the flame floating length increases by about 8.34%. Compared with synchronous injection condition, DME injection with a delay of 1 ms has the lower soot formation and 26.12% higher KL formation. It is indicated that increasing the injection pressure and delaying the injection time of DME are beneficial to optimize the injection and combustion of DME and methanol dual fuel engine.103|23|0更新时间：2025-07-28
- 摘要：Aiming at the low computational efficiency of existing binocular-vision-based methods for measuring the three-dimensional strain field on cylindrical surfaces from the obtained three-dimensional displacement field, a method of calculating the three-dimensional strain field on a cylindrical surface by integrating cylinder fitting and subdomain projection is proposed. The method integrates the geometric prior information of cylindrical structures into the theory of subdomain projection, replaces a large number of redundant local tangent plane least squares solutions by cylindrical standard coordinate transformation. Then, numerical simulation was used to compare and analyze the proposed method with the general surface subdomain projection method under different strain regions and displacement field noise conditions. Finally, cylindrical tensile experiments were conducted, and the strain calculation results of the proposed method were compared with the strain gauge measurement results from both single point and full field perspectives. The results show that while ensuring calculation accuracy and robustness to displacement field noise, the proposed method improves calculation efficiency by about 20% and is in good agreement with the experimental measurement results of strain gauges. The proposed method can achieve efficient measurement of the three-dimensional strain field on the surface of cylindrical structures, and also provides a new approach for calculating the three-dimensional strain field on regular structural surfaces.关键词：binocular vision;subdomain projection;three-dimensional strain field;cylinder fitting;least square fitting184|16|0更新时间：2025-07-28
- 摘要：To solve the problem of inconsistency in the characteristics(or parameters)of cells in a series-connected lithium-ion battery pack, a lithium-ion battery pack equalization strategy using an improved matrix-type reconfigurable topology is proposed in this paper. The strategy takes the state of charge(SOC)of each cell in the battery pack as the equalization target parameter, and uses the switching matrix to control the switching of battery groups between series and parallel topologies and realize the equalization between battery cells and battery groups, and accelerates the equalization speed by isolating the cell or battery group with the lowest SOC. Simulation results using MATLAB/Simulink and comparison with the original matrix reconfigurable equalization strategy show that, compared with the original matrix reconfigurable equalization strategy, the improved strategy can improve the equalization speed by 13.1%, 27.1% and 30.1% under the loads of 10, 20 and 40 W, respectively. Taking the switch on-resistance into consideration, the improved strategy proposed accelerates the equalization process through the voltage difference caused by the SOC difference at the later stage of the equalization process, and can still effectively equalize the battery pack when the on-resistance is high, which effectively avoids the defects that the equalization effect of the original matrix-type reconfigurable equalization strategy deteriorates or even fails with the increase of on-resistance, and achieves the equalization target successfully. This proves that the improved matrix-type equalization strategy proposed has a better equalization effect compared with the original matrix-type equalization strategy.关键词：lithium-ion battery;active equalization;inconsistency;state of charge56|17|0更新时间：2025-07-28
- 摘要：In order to fully tap the potential of primary frequency modulation in the energy storage unit of the thermal-storage combined system and reduce the frequency regulation of thermal power units, a twin delayed deep deterministic policy gradient algorithm based energy storage assisted primary frequency regulation control strategy for thermal power unit is proposed. A typical regional power grid primary frequency regulation model containing thermal-storage combined frequency regulation system is established. Optimization problems with multiple objectives such as improving the frequency control effect of the power grid, maintaining a stable state of charge(SOC), and reducing the frequency regulation actions of thermal power unit are set. Taking into account the constraints of power grid operation status and frequency regulation actions, the primary frequency regulation problem of thermal power unit assisted by energy storage is modeled as a Markov decision process. Twin delayed deep deterministic policy gradient algorithm is used for optimization problem solving. The simulation results of typical frequency regulation task scenarios show that compared with traditional frequency regulation system control algorithms, the proposed energy storage assisted intelligent frequency regulation control strategy for thermal power units can reduce the average frequency difference of the power grid by about 10.4%, and reduce the frequency regulation actions of thermal power unit by about 56.2%. This verifies that the strategy can effectively release the frequency regulation potential of the thermal-storage combined system while significantly reducing frequency regulation of thermal power units.关键词：primary frequency control;deep reinforcement learning;droop control;frequency dead band;state of charge43|37|0更新时间：2025-07-28
- 摘要：Aiming at the problem of severe friction and wear between the stator and rotor surfaces of traditional ultrasonic motor causing system performance degradation, a new non-contact levitation acoustic streaming ultrasonic motor is proposed. The proposed motor has a compact structure and uses the acoustic levitation principle to realize non-contact driving of stator and rotor, thus eliminating the friction and serious wear existing in the traditional ultrasonic motor. Based on the continuity equation, the fluid analysis model of levitated interstitial medium is established and solved by finite element method. The rotation characteristic test experiment was carried out on the established test bench. The working mechanism of the new motor was analyzed, and the acoustic streaming distribution under different grooves and operating conditions was studied. The results show that the grooves on the surface of the rotor cause a pressure gradient in the circumferential direction of the gap, which in turn form the torque that drivers the rotor. With the increase of the driving voltage, the amplitude of stator disk vibration and rotor speed both increase. When the driving voltage is 1 430 V, the vibration amplitude of the stator is 9.8 μm, and the rotor speed reaches 74 r·min-1. Compared to smooth rotors, grooved rotors exhibit significant changes in the acoustic streaming field near the groove region. This research can provide reference for the research of non-contact ultrasonic motor, and also can further expand the application field of ultrasonic motor.关键词：ultrasonic motor;acoustic streaming;non-contact levitation;acoustic levitation29|36|0更新时间：2025-07-28
- 摘要：The structure and measurement principles of a high-frequency dynamic piezoelectric shock wave pressure sensor based on piezoelectric effect are proposed in response to the increasing demand for fast measurement of shock wave pressure signals. The performance requirements of the high-frequency dynamic piezoelectric pressure sensor are determined by analyzing the time-frequency characteristics of shock wave signal. The measurement principle of the high-frequency dynamic piezoelectric pressure sensor is used to analyze the proposed shock wave pressure measurement. Based on the principle of deformation coordination and consistency, static and dynamic models are established to analyze the influence of sensor structural parameters on sensitivity and natural frequency. The optimized three-dimensional model of the sensor is imported into ANSYS for static, dynamic, and piezoelectric coupling analyses, and the feasibility of the sensor structure and its measurement principle is verified. Through quasi-static and dynamic calibration experiments, the measurement performance indicators of the sensor, such as voltage sensitivity, nonlinearity, and natural frequency, are obtained. The experimental results show that the developed prototype of the high-frequency dynamic piezoelectric shock wave pressure sensor has high sensitivity: 3.19 mV/kPa, high natural frequency characteristic: 95.625 Hz, and short rise time: 10.45 μs, which can meet the requirements in actual tests.关键词：mechanical model;pressure sensor;shock wave;calibration experiment;piezoelectric ceramics38|21|0更新时间：2025-07-28
- 摘要：Aiming at the complicated time-variant flow coefficients and strong coupling notch structure parameters of K-K shape notches, the research of K-K shape notch flow pressure drop characteristics of the hydraulic cylinder spool valve is carried out using the flow area parameter model(FAPM). First, the mathematical model of K-K shape notch's flow area is derived, which is equivalent to the combination of three single-stage notches. Then, based on computational fluid dynamics(CFD)and response surface model(RSM), the FAPM model of the K-K shape notch under limit saturation flow is established. Finally, the mapping relationship between the combined notch spool structure and flow-pressure drop is obtained on the basis of the FAPM model. The results show that the limit saturation flow requirement is met when the inlet volume flow is 7.31 L/min, and the flow coefficient is independent of inlet volume flow at this moment. When the inlet volume flow is 20, 30 and 50 L/min, the average deviations of the K-K shape notch valve port pressure drop between the value predicted by the FAPM model and the CFD simulation value are all below 7%. The proposed model effectively realizes the approximate expression of K-K shape notch structure and can be applied to other types of notches.关键词：hydraulic cylinder spool valve;K-K shape notch;flow area parameter model;flow pressure characteristics;computational fluid dynamics;response surface model58|23|0更新时间：2025-07-28
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