最新刊期
卷 56 ， 期 3 ， 2022
- 摘要：In the multi-actuator compound operation equipment such as engineering machinery, the throttling loss of the valve-controlled system is serious and the installed power of the pump-controlled system is too large. Therefore, a pump and valve dual-source collaborative driving multi-actuator system(PVDS)is proposed. Firstly, the energy efficiency mechanism of different systems is analyzed theoretically, and it is identified that the essential cause of the large throttling loss of the valve-controlled system due to load difference is the different pressures of actuator driving chambers. Based on this, a extremely low-pressure loss control strategy based on the proposed system is designed. Then, simulation model of a 37 t excavator is established by SimulationX, and its accuracy is verified by experiments. Furthermore, co-simulation models of the hydraulic excavator with the PVDS and electro-hydraulic flow matching system are established. Finally, under the no-load condition of combined action of boom and bucket, the operation performance and energy characteristics of the proposed system and the electro-hydraulic flow matching system are analyzed and compared. The results show that compared with the electro-hydraulic flow matching system, the proposed system significantly improves the response lag of the heavy-load actuator and the stability of the system. Meanwhile, the pressure loss of the light-load actuator caused by load difference is greatly reduced, the throttling loss and energy consumption of the whole system are reduced by 67.2% and 39.8%, respectively. This research can provide a new solution to the reduction of the throttling loss of multi-actuator compound operation equipment.关键词：valve-controlled system;pump-controlled system;engineering machinery;multi-actuator load difference;energy saving187|6|0更新时间：2025-07-09
- 摘要：In view of the uneven distribution of temporal and spatial information and the difficulty in obtaining long-term information representation, we propose a dual-path action recognition method MRTP based on time and motion perception, which takes RGB video as input and applies two parallel perception paths to extract spatial and motion features from the video at different time resolutions. In the spatial path, the action-perception based on feature difference is applied to find and strengthen the action feature representation; in the action path, the channel is filtered based on the weight of action perception, and channel attention and time attention are added to enhance the key features; the characteristics of the two paths are merged to calculate the action category score of the video. The experimental results show that MRTP achieves accuracy of 95.6% on the UCF101 data set to outperform the model without time attention; on the AVA2.2 data set, the accuracy of mAP reaches 28% to outperform the model without action perception and time attention. Compared with the current mainstream two-stream network, 3D convolution, Transformer, and other methods on a number of accuracy indicators, this method is endowed with better recognition effect and robustness.关键词：action recognition;dual-path network;feature difference;action perception;temporal attention217|7|0更新时间：2025-07-09
- 摘要：A relativistic average generative adversarial network for pan-sharpening(Pan-RaGAN)based on a deep learning algorithm is proposed to solve the problems that details of fusion result are easy to be lost due to insufficient feature extraction from original image in the pan-sharpening process and information redundancy is caused by ignoring spatial feature difference of different regions in image fusion process. Firstly, the improved dense block structure is utilized to extract the features of the original image in the generator, so as to make full use of the features from different layers of the original image and obtain better fusion results with more details. Secondly, a feature refinement module based on spatial attention mechanism is proposed for feature selection, which can make a better trade-off between retaining effective high-frequency information and eliminating redundant information. Furthermore, the image reconstruction module is utilized to fuse the refined features with the up-sampled low resolution multispectral images to preserve the spectral information. Finally, the relativistic average discriminator is utilized to improve the loss function of the network, and further optimize the fusion effect. Experimental results on Gao Fen-2 dataset and Quick Bird dataset and a comparison with the existing generative adversarial network for remote sensing image pan-sharpening show that the spectral angle mapper index of the proposed Pan-RaGAN network is reduced by 0.075 on average, which verifies the effectiveness of the proposed Pan-RaGAN network.关键词：pan-sharpening;image fusion;relativistic average generative adversarial network;spatial attention mechanism;deep learning96|4|0更新时间：2025-07-09
- 摘要：In order to improve the aerodynamic performance and noise characteristics of multi-blade centrifugal fan, combining with the characteristics of high degree of freedom in the design of inter-blade flow channel of double-arc blade and based on a single-arc blade multi-blade centrifugal fan with better performance, a full parameter matching optimization design of double-arc blade is carried out through the combination of CFD and experiments. Taking the air volume of the fan under 0 Pa static pressure condition as the optimization goal, the Box-Behnken response surface experimental design method is used to determine the inlet angle, outlet angle, inner to outer diameter ratio, arch point diameter and central angle for parameter design, and 46 sets of sample spaces are obtained. Through the quadratic regression fitting of the design parameters and the sample results, the functional relationship between the parameters of the double-arc blade and the air volume, as well as the optimal parameter combination, is obtained. The results show that the inlet angle and outlet angle have the highest sensitivity to the air volume in all main effects, while the inlet angle, the outlet angle, the inner diameter to outer diameter ratio and the central angle have the highest sensitivity to air volume in all interaction effects. The CFD and FW-H methods are used to calculate the aerodynamic performance and sound field characteristics of the optimized double-arc blade fan and the prototype fan. The results show that the air volume of the optimized fan increases by 118 m3·h-1 compared to the prototype fan, with a relative increases of 9.7%. The optimized blade can effectively suppress the generation and development of vortex flow in the inter-blade flow channel. The inlet angle and outlet angle of the blade are more consistent with the inlet and outlet flow angles of the airflow, which effectively reduces the pressure pulsation caused by the impact of the blade leading edge and the unsteady interaction of wake flow and volute. The test results show that the power of the fan under the same air volume is reduced by 4.7% compared with the prototype, and the noise is reduced by 1.8 dB.关键词：multi-blade centrifugal fan;double-arc blade;Box-Behnken RSM;parametric design;aerodynamic performance102|5|0更新时间：2025-07-09
- 摘要：The airflow excited rotordynamic characteristics of labyrinth seal with swirl brakes at two different inlet preswirl ratios were numerically investigated by solving the unsteady Reynolds-average Navier-Stokes equation based on the multi-frequency elliptical orbit rotor whirling mode and dynamic mesh technique. The average circumferential velocity, leakage flow rate and rotordynamic coefficients of labyrinth seal with inlet swirl brake(Design 2)or double swirl brakes(Design 3), or without swirl brake(Design 1), were analyzed at two different inlet preswirl ratios of 0.13 or 1.32. The numerically predicted leakage flow rate and rotordynamic coefficient of experimental labyrinth seal without swirl brake(Design 1)agreed very well with the experimental data, so the accuracy of the used numerical method was validated. The obtained results show that the direct stiffness and the effective damping ofDesign 1 decrease' and the direct damping and cross-coupling stiffness increase' at higher inlet preswirls. The cross-coupling stiffness ofDesign 2 decreases by 63.3%-86.3% compared withDesign 1 at the inlet preswirl ratio of 1.32. The cross-coupling stiffness ofDesign 3 decreases by 12.9%-39.4% compared withDesign 2 at the inlet preswirl ratio of 1.32. The cross-coupling stiffness ofDesign 2 is less than zero at the inlet preswirl ratio of 0.13. The magnitude of negative cross-coupling stiffness ofDesign 3 increases by 24.4%-153.0% compared toDesign 2 at the inlet preswirl ratio of 0.13.Design 2 reduces the crossover frequency of effective damping from 175.1 Hz to 28.3 Hz compared withDesign 1 when the inlet preswirl ratio is 1.32.Design 2 adds 31.5%-60.0% to the effective damping after 20 Hz compared withDesign 1 when the inlet preswirl ratio is 0.13.Design 3 eliminates the crossover frequency of effective damping compared withDesign 2 when the inlet preswirl ratio is 1.32.Design 3 adds 26.9%-38.0% to the effective damping after 20 Hz compared withDesign 1 when the inlet preswirl ratio is 0.13. Adding double swirl brakes inDesign 3 would slightly reduce the direct stiffness and cross-coupling stiffness and increase the direct damping compared withDesign 2 at different inlet preswirl ratio. This research can provide a reference for the swirl brake design to improve rotordynamic characteristics of labyrinth seals.关键词：labyrinth seal;swirl brake;inlet preswirl;rotordynamic characteristics52|4|0更新时间：2025-07-09
- 摘要：In order to study the interference of different electrode materials on arc fault detection in DC system, and to solve the malfunction problems of arc fault detection with avarious electrode materials, a DC arc fault detection algorithm based on Catboost algorithm is proposed. A DC arc fault experiment platform is built and the DC arc fault data from 6 electrode materials are obtained by the pulling-apart method. Through constructing the evaluation index of the arc fault detection characteristic, the wavelet transform method is used to extract time-frequency characteristics of arc faults more effectively for different electrode materials. The influences of different electrode materials on DC arc fault detection characteristics and efficiency of the algorithms are analyzed, and it is pointed out that the detection characteristic index has a positive correlation with the melting point and resistivity of electrode material. Compared with the existing threshold comparison method and the Adaboost algorithm, the proposed algorithm improves the range of arc fault detection and effectively solves the problem that it is difficult to accurately detect arc faults using pure aluminum electrode material. This algorithm can realize rapid detection of arc faults within 1.5 s for the 6 different electrode materials, and the detection accuracy reaches 100%, which meets the requirements of UL1699B standard.关键词：DC system;arc fault;electrode material;time-frequency feature;Catboost algorithm57|5|0更新时间：2025-07-09
- 摘要：To deal with the issues of high memory consumption and low computation efficiency of the existing convolutional modules in practical application, following the Kronecker CANDECOMP/PARAFAC(KCP)tensor decomposition, a lightweight, efficient, bottleneck-structured convolutional module(KCPNet)is proposed. The normal convolution is firstly decomposed as the 2nd-order KCP, the generated factor tensors are mapped into two 1×1 convolutions to carry out the transformation of input and output channels, and into two depthwise convolutions with changeable channels to perform the feature extraction, respectively. Then, these 4 convolutions are assembled into the KCPNet module with a bottleneck structure. The KCPNet is deployed in the embedded GPU based on the OpenCL parallel programming framework, and the dynamic gesture recognition application is developed around a pico-flexx depth camera. The experimental results show that compared with the existing convolutional modules of tensor decomposition such as ResNet, ResNeXt, etc., the KCPNet can consider the efficiency of both space and computation complexity with a similar accuracy on the large-scale benchmark dataset ImageNet; the KCPNet can also compress the traditional VGG model to its original 16.1% and save 75.5% of computation without obvious accuracy loss on the medium-scale benchmark dataset CIFAR-10; the parallelly deployed KCPNet can achieve the recognition rate of 100 frames/s for CIFAR-10 when orienting to the embedded GPU. The developed gesture recognition application with the KCPNet as its core can achieve 99.5% accuracy and the running rate beyond 100 frames/s, and the memory cost is 22 MB.关键词：tensor decomposition;Kronecker CANDECOMP/PARAFAC tensor decomposition;lightweight convolutional module;parallel deployment;gesture recognition50|5|0更新时间：2025-07-09
- 摘要：Numerical simulation methods were adopted to investigate the heat transfer and film cooling effect at the pressure-side winglet-squealer tip in the first stage of a gas turbine. The effects of seven different tip geometries(e.g.uniform cross-section winglet and distortion winglet)on the aerodynamic performance of turbine stage and the heat transfer coefficient distributions at the tip were analyzed. The film cooling and heat transfer performances at the conventional squealer tip, non-pressure-side rim tip and pressure-side winglet tip with two different hole arrangements(single row of hole-array and double rows of hole-array)were compared. The result shows that a high heat transfer area appears on the cavity floor of the conventional squealer tip. A proper design of pressure-side winglet is able to effectively eliminate the high heat transfer area on the cavity floor and also reduce the averaged heat transfer coefficient at the squealer tip. Compared with the conventional squealer tip, the averaged heat transfer coefficient at the distorted winglet tip with round corners is reduced by about 16.45%. The single row of tip cooling holes has a significant effect on reducing the averaged heat transfer coefficient of squealer tips, while the film cooling effectiveness at different squealer tips is significantly improved with the double rows of hole-arrays. For the single row of hole-array cases, the advantage of film cooling effect on the winglet-squealer tip is not obvious. The heat transfer and film cooling effect can be improved significantly by adding film cooling holes at the blade pressure side. With both tip and pressure-side cooling hole-arrays, the averaged heat transfer coefficient at the winglet-squealer tip is about 0.76% lower than that of the conventional squealer tip, and 7.84% lower than that of non-pressure side rim tip. The film cooling effectiveness at the winglet-squealer tip is about 9.13% higher than that of the conventional squealer tip, and 9.6% higher than that of the non-pressure side rim tip.关键词：gas turbine;tip;winglet;squealer;heat transfer;film cooling45|5|0更新时间：2025-07-09
- 摘要：To reduce the overall thermal load at squealer tip and improve the film cooling effectiveness in high heat transfer areas, the influence of pressure-side coolant jet flow on heat transfer and film cooling performance of squealer tip in a turbine stage was investigated. The heat transfer coefficient and film cooling effectiveness at squealer tip with two kinds of cooling hole shapes(i.e.cylindrical and fan-shaped holes)and five different jet ejection angles(20°-40°)for pressure-side cooling holes were obtained through numerical simulations. The results show that the pressure-side cooling flow enters the cavity near the leading edge, improving the cooling effect on the cavity floor. The pressure-side coolant from the middle chord and near the trailing edge holes forms the cooling film on the tip surface and at the tip trailing edge, which enhances the cooling performance in the tip's high thermal load area. In the present study, the cooling effect on squealer tip is increased with the decrease of ejection angle. For the fan-shaped holes at squealer tip, the area-averaged heat transfer coefficient is increased by 6% and the area-averaged film cooling effectiveness is decreased by 14.3% on the squealer rim, whereas the area-averaged heat transfer coefficient is increased by 36% and the area-averaged film cooling effectiveness is decreased by 37.2% in the tip pressure-side region, as the jet ejection angle increases from 20° to 40°. With small jet ejection angle, the film cooling effect on the squealer tip and pressure-side surface for the fan-shaped holes is better than that of cylindrical holes. If the jet ejection angle is fixed at 20°, the fan-shaped holes are able to decrease the heat transfer coefficient by 2% while increase the film cooling effectiveness by 5.9% on the tip surface, and decrease the heat transfer coefficient by 22.6% while increase the film cooling effectiveness by 43.3% on the pressure-side surface, as compared with the cylindrical holes.关键词：gas turbine;squealer tip;heat transfer;film cooling;fan-shaped hole;jet angle54|5|0更新时间：2025-07-09
- 摘要：To effectively improve energy efficiency of multiple HE-IESs, aiming at the cost sharing problem of multiple HE-IESs coordinated operation taking wind power consumption into account, a multi-HE-IESs multi-objective optimization operation model with Nash bargaining theory is proposed. The framework of multi-HE-IESs is constructed to model gas turbine, heat pump, electric energy storage, thermal energy storage and the other equipments in HE-IES, and multiple power interaction models among HE-IESs and between HE-IES and distribution network are established. Taking operating costs and wind power consumption of multi-HE-IESs as the indicators, the multi-objective weighted programming method is used to establish a multi-HE-IESs multi-objective optimization model. Furthermore, following Nash bargaining theory, a cooperative game model of multi-HE-IESs is constructed, and the non-convex problem is transformed into two convex sub-problems via mathematical transformation to realize the Pareto optimum for each HE-IES, which ensures the enthusiasm of all HE-IESs to participate in cooperation. A simulation example verifies that the proposed method enables to reduce total operating costs and total wind curtailment costs by 660.14 and 222.03 yuan, respectively, and also to reduce operating costs and wind curtailment costs of each HE-IES by 220.05 and 74.07 yuan, thus the Pareto optimum of overall HE-IESs is achieved.关键词：heat-electricity integrated energy system;cooperative game;Nash bargaining;wind power consumption;multi-objective optimization58|5|0更新时间：2025-07-09
- 摘要：A prediction method of rolling bearing life based on improved regression support vector machine(SVR)is proposed to accurately evaluate the running state of rolling bearings and predict their performance degradation trend and remaining life. The time domain and time-frequency domain features of bearing signals are extracted, and the feature indexes are fused into a normalized comprehensive index by principal component analysis(PCA)method to characterize the running state of the bearing. Data sets of training and prediction vectors are constructed by using the feature indexes and the comprehensive indexe, the optimal penalty parameters and RBF kernel parameters are determined by the differential evolution grey wolf optimizer(DEGWO), and the SVR model is constructed. The prediction data set is input into the SVR model optimized by DEGWO algorithm to obtain the predicted value of the bearing condition evaluation index, and the remaining life of the bearing is predicted. The validity of the proposed method is verified using the IEEE PHM 2012 Dataset. The advantage of the proposed method is examined by comparing the prediction result with those obtained by the SVR model optimized by grey wolf optimizer(GWO), the SVR model optimized by grid search algorithm(GSA), and the long short-term memory networks(LSTM)model. Simulation results show that compared with other methods, the MSE values of bearing life prediction obtained by the proposed method is reduced by 44.74%, 66.67% and 77.27% respectively, and the determination coefficient is increased by 7.25%, 20.72% and 11.94% respectively. These results demonstrate the superiority of the proposed method in the application of bearing remaining life prediction.关键词：rolling bearing;state evaluation;principal component analysis;differential evolution grey wolf optimizer;remaining life prediction66|5|0更新时间：2025-07-09
- 摘要：In order to reduce the loss of internal calculation and communication resources in the attitude tracking control of quadrotors, an attitude tracking control based on the backstepping method and multi-event triggered mechanism is proposed. First, the dynamic model of the quadrotor aircraft is established, and the roll angle system is taken as an example. Also, a continuous controller is designed using the backstepping method to achieve the tracking control of the aircraft roll angle to the reference signal. Second, an event-triggered controller is constructed by introducing an event-triggered mechanism. Based on the Lyapunov stability theory, it is proved that the designed event-triggered controller can keep the roll angle system stable and avoid the Zeno phenomenon. At the same time, the same method is adopted for the other three systems of the quadrotor. Under different parameters, the corresponding event-triggered mechanism and event-triggered controller are designed, respectively. The four event-triggered mechanisms constitute the multi-event triggered mechanism of the quadrotor. Finally, the simulation results show that under the multi-event triggered mechanism, the proposed event-triggered controller can be triggered 150 times in 3 seconds to achieve the same tracking effect as the periodic sampling controller for 3 000 consecutive samples.关键词：quadrotors;attitude tracking control;backstepping;multi-event triggered mechanism;event triggered controller88|6|0更新时间：2025-07-09
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