最新刊期
卷 55 ， 期 6 ， 2021
- 摘要：The commonly used max pooling only takes the maximum value of neuron activity in the region to bring about loss of a large amount of information, and the average pooling assigns the same weight to the neuron activity values to weaken important features. A novel strategy for down sampling with small-scale convolution kernels is proposed. This strategy replaces the traditional pooling layers with small-scale convolution layers, where the stride of convolution kernels is 2 and the activation function is chosen as Rectified Linear Unit(ReLU), thus the size of the output image only gets half of the input to achieve down sampling and the small-scale kernels can automatically adjust the weight to select effective features during training. Compared with max pooling, the ratio of active neuron and the diversity of neuron activity values are more effectively heightened. The improved deep convolution neural network(DCNN)with the proposed strategy, depth wise separable convolution and global average pooling is tested and compared on a variable-speed and multi-rolling bearings dataset. The results show that the improved DCNN recognition accuracy rate reaches 98.4%, higher than the other competing networks. Meanwhile, the stability of network is greatly enhanced and training time is shortened by 40%. The proposed strategy for down sampling with small-scale convolution kernels may provide a reference to construction of DCNN and fault diagnosis of rolling bearings under variable conditions.关键词：deep convolution neural network;bearing fault diagnosis;variable conditions685|5|13更新时间：2025-07-09
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Method of Model Identification and Precise Control for Tunnel Boring Machine Body Posture Adjustment
摘要：Aiming at the derivation of the tunnel excavation track and the coal production inefficiency and safety problem caused by poor posture control accuracy of tunnel boring machine(TBM), a model identification method based on the particle swarm optimization(PSO)and a fuzzy neural network control method of attitude control are proposed. Firstly, the relation between the posture error and the tunnel section is analyzed, and the structure of the control system transfer function is determined according to the kinematic and hydraulic system model. Through the PSO searching character and the response of the input and output signals, the transfer function parameters could be fitted. Simulation results show that the identification accuracy based on PSO is 96.75% and 95.15% higher, respectively, than that based on least square or genetic algorithm identification method. Making use of the fuzzy logic control' strong nonlinearity adaptability and the neural network' self-learning ability, a posture PID control algorithm is proposed, and a EBZ-55 tunnel boring machine attitude control experiment system is designed and established. Experiment shows that compared with the fuzzy PID, the proposed fuzzy neural network PID control system could mostly reduce 57.1% overshoot error and 53.5% response time in different conditions, and the posture of the tunneling boring machine could be controlled in 1° stably.关键词：tunnel boring machine;posture angle adjustment;particle swarm optimization;model identification;fuzzy neural network PID127|4|4更新时间：2025-07-09 - 摘要：A 2D numerical micro-slip model was developed in order to overcome the limitation on kinematic direction and time-invariant excitation of the one-dimensional micro-slip model, and the incapability of considering the flexibility of the damper when using a traditional macro-slip model. In this model, the dry friction damper was discretized and the lag spring family was used to indicate the local stick-slip effects of the frictional contact surface. The time-process of the external excitation was dispersed and the state vectors were applied to calibrate the local stick-slip-separation state of the contact surface in the beginning of the solution procedure, and then the local kinematic state of the contact friction surface was continuously tracked by the numerical accumulation method. The displacement, friction force and kinematic state vectors were corrected by time point during the solving process according to the stick-slip-separation transformation criterion. After several cycles of tracking, a stable hysteretic curve of contact displacement versus dry friction force was obtained. Resonance frequency response results show that the displacement frequency response calculated by the plane motion micro-slip model is 0.049 m versus 0.038 m calculated by the macro-slip model while greater normal force is applied to the damper, indicating a 22.4% difference between the two dry friction models, and the results obtained by the micro-slip model are closer to the experimental data.关键词：dry friction;2D micro-slip model;contact points;stick-slip-separation;frequency response182|4|2更新时间：2025-07-09
- 摘要：To improve the transmission efficiency of line gear, a designing method for pure-rolling internal line gear mechanism is proposed for parallel shaft transmission. Following the line gear meshing theory, the equations of spatial conjugate curves are solved and the constraint conditions for pure-rolling meshing are analyzed. The profile cross-section located on the contact point and perpendicular to the direction of angular velocity is established. The mathematical models of tooth surface of convex-convex, convex-concave and convex-flat contacts are constructed according to the profile cross-section equations and contact curve equations. Taking cylindrical helix as an example, the selection criterion of designing parameters for pure-rolling meshing state is analyzed and the pure-rolling internal meshing tooth surface is constructed. The contact stress of tooth surface with different contact forms is analyzed. Meanwhile, the modeling of convex-concave surface and the kinematics analysis are carried out with 3D software. The results show that when the theoretical transmission ratio, the contact ratio, and the teeth number of pinion are respectively set as 2, 1.5 and 6, the convex-concave contact with the relative smallest curvature radius has the lowest contact stress under the same restrictive conditions, and the contact stress is reduced by 28.95% and 19.17% respectively, compared to convex-convex and convex-flat contacts. The average transmission ratio of the internal line gear pair constructed by this method reaches 2.00, and the maximum variation of the instantaneous transmission ratio reaches only 0.07, smooth and continuous speed transmission is thus realized.关键词：internal line gear;conjugated curves;pure-rolling;convex-concave surface;kinematics analysis68|5|0更新时间：2025-07-09
- 摘要：A fast adaptive disturbance rejection control method(FADRC)based on finite-time parameter estimation is proposed to realize high precision motion control of motor servo systems under the combined effect of parameter uncertainties and unmodeled disturbances. For parameter uncertainties, a novel parameter adaptation law driven by a combination of tracking error, parameter estimation error and system state estimation error is constructed by introducing first-order low-pass filtering operations and auxiliary intermediate variables to realize the fast online updating of unknown parameters. For unmodeled disturbances, an extended state observer(ESO)is designed to estimate them and compensate them with a feedforward term. In addition, the overall robustness of the system is ensured by the feedback robust term. Analysis based on Lyapunov stability theory shows that the proposed control method can guarantee fast parameter estimation performance and excellent tracking control effect. An electric servo experimental platform is built to test its effectiveness and superiority. Test results and a comparison with the traditional adaptation law-based control method show that the proposed novel control method improves the convergence speed of parameter estimation by about 80% and reduces the maximum tracking error by about 13.8%. This method can provide reference for high precision servo control and fast parameter identification of practical electromechanical systems.关键词：motor servo system;parameter uncertainty;unmodeled disturbance;fast adaptive;extended state observer215|4|6更新时间：2025-07-09
- 摘要：An image dehazing method combining adaptive brightness transformation inequality to estimate transmittance is proposed to solve the problems of inaccurate transmittance estimation and incomplete dehazing in single image dehazing algorithms. Firstly, the brightness transformation inequality is applied to construct the scene depth by using brightness and inverse saturation, and a logarithmic transformation is used to expand gray scale. Secondly, regularization is used to optimize scene depth to solve the excessive difference between adjacent pixels and to approximate the exact depth of the scene. Then, according to the local constant assumption, the dynamic atmospheric scattering coefficient is estimated using local average depth and joint bilateral filtering, and the transmittance is obtained by combining the scene depth and dynamic atmospheric scattering coefficient. Finally, the median filtering and interval estimation are used to optimize the local atmospheric light, and clear image is recovered by the atmospheric scattering model. Experimental results show that the proposed method can adaptively adjust the model parameters in different scenes, thoroughly remove haze, and get better dehazing effect. At the same time, the average visual contrast in objective indexes reaches 60.572, with good image fidelity.关键词：image dehazing;transformation inequality;regularization;local average depth;local atmospheric light114|4|4更新时间：2025-07-09
- 摘要：Aiming at the problem of electrostatic discharge in the process of production, storage, transportation and use of explosives, the electrostatic breakdown characteristics of air, carbon dioxide and helium under three temperature conditions of 0, 20, 40 ℃ and the pressure range between 0.05 and 0.15 MPa are studied to find a feasible way to suppress the excessively high electrostatic discharge voltage, and the electrostatic breakdown energy is calculated and compared. The results show that the electrostatic breakdown voltage of the three gases increases with the increase of the pressure. The electrostatic discharge voltage and energy of carbon dioxide are the highest under the same condition, while the discharge voltage of helium is the lowest among the three gases; with the increase of temperature, the electrostatic breakdown voltage of the three gases decreases, and the electrostatic breakdown voltage of the three gases reaches the minimum at 40 ℃ and 0.05 MPa. Therefore, an environment with low pressure, higher temperature, and low breakdown field strength should be selected as the electrostatic protection atmosphere environment. These research results may serve as data basis and theoretical support for selection of protective atmosphere environment in the production process of explosives.关键词：electrostatic discharge;typical gases;production of explosives;electrostatic protection79|4|1更新时间：2025-07-09
- 摘要：In view of off-design working condition characteristics of the original pumped hydro compressed air(PHCA)system, and based on previous research of PHCA, a novel steam constant-pressure pumped hydro combined with compressed air energy storage system is proposed. The system realizes constant pressure discharge process by using the latent heat and sensible heat released from steam, and steam also serves as working fluid after condensation, which improves energy capacity and energy density of whole system. Following the second-law of thermodynamics, the system performances are analyzed with focus on the dependence of energy efficiency and energy density on each parameter, and the exergy loss of the equipment in each part of the system is evaluated. The results show that with the increasing initial pressure, energy density of the system increases gradually, but the total efficiency decreases; with the increasing volume of a single cylinder, the total efficiency and energy density of the system reach the minimum and maximum successively; the exergy loss of steam generator and cylinder gets the highest.关键词：compressed air energy storage system;thermodynamic analysis;renewable energy100|7|7更新时间：2025-07-09
- 摘要：The rectification characteristics of a tab-type elbow flow conditioner under three incoming flow conditions are investigated by numerical methods, and the flow mechanism, rectification performance, application range and pressure loss characteristics are analyzed. The results show that the elbow tabs form a counter-rotating induced vortex through the influence of pressure difference, and guide the outside fluid to the inside in elbows, thus greatly enhancing the momentum exchange between the fluids, and achieving the effect of disturbing the original velocity distribution and forming a uniform flow. Compared with the smooth tube elbow, the tab-type flow conditioner has little effect on the pressure uniformity, but increases the velocity uniformity by 21%-36%, and the influence on the flow angle uniformity varies with the inlet conditions. The flow resistance of the tab-type flow conditioner is higher than that of the blade-type flow conditioner, lower than that of the orifice-plate flow conditioner, and equivalent to the tube bundle flow conditioner.关键词：elbow pipe;flow conditioner;uniformity;swirl angle;pressure loss77|4|0更新时间：2025-07-09
- 摘要：For the poor flow stability and uniformity problem of double elbow pipes with circular cross section in industrial water pipeline, based on the energy gradient theory, a numerical simulation method is used to study the influencing rules of three different arrangement modes of the double elbow pipe at angles 0°, 90° and 180° on the flow stability and uniformity when Reynolds number ranges from 6×105 to 1.2×106. The results show that under the same Reynolds number condition, the velocity uniformity of 180° double elbow pipe is the best among the three arrangement schemes within 12D downstream length, followed by 0° double elbow pipe, and 90° double elbow pipe is the worst, while the results of the pressure uniformity are just the opposite. The resultant force at the downstream bend of 90° double elbow pipe has larger components in circumferential and radial directions, resulting in strong secondary flow, while its swirling angle is the largest among the three arrangements. At the downstream 45D location of double elbow pipe with 90°, the swirling angle is about 10°, so a longer straight distance is needed to meet the requirements of flowmeter installation. When the Reynolds number is in the range of 6×105 to 1.2×106, the stability of flow and the pressure uniformity decrease with the increase of Reynolds number, but the corresponding velocity uniformity increases.关键词：double elbow pipe;stability;uniformity;swirling angle74|4|1更新时间：2025-07-09
- 摘要：Dynamic thermal characteristics of cryogenic targets are studied under conditions of temperature disturbance of the thermal shield. Based on user-defined functions and the discrete coordinate radiation model, a model is numerically developed and the propagation characteristics of the temperature disturbance in the hohlraum system are studied. The influences of the thermal mechanical package(TMP)shell absorptivity and the sealing film transmissivity on the stability and uniformity of the capsule surface temperature field are obtained. The results show that the temperature fluctuation of the shield has two paths. The first path is the shield-sealing film-capsule and the second one is the shield-TMP-gold hohlraum wall-helium chamber-capsule. Under typical operating conditions, the temperature fluctuation of shield with amplitude 10 K is attenuated to 0.85 mK at the outer wall of the target. The temperature amplitude of each surface of the hohlraum system varies from large to small: the outer wall of the target, the outer wall of TMP, the inner wall of TMP, and the inner wall of gold hohlraum. The stability and uniformity of the capsule temperature is significantly improved by decreasing the TMP shell absorptivity when the sealing film transmissivity is small, or increasing the TMP shell absorptivity when the sealing film transmissivity is large, or decreasing the sealing film transmissivity.关键词：cryogenic target;thermal shield;temperature disturbance;dynamic characteristics;numerical simulation50|4|1更新时间：2025-07-09
- 摘要：Aiming at the issue of low efficiency and poor robustness in large-scale real-world data clustering, a fast correntropy-based clustering algorithm(FCC)is proposed. FCC is mainly divided into the following two steps:1)Performing k-means on the original data to obtain rough labels to serve as the label matrix of the second step; 2)Adopting the original data and those anchors to construct the anchor graph and taking Laplacian matrix of the anchor graph as a graph constraint to explore the internal structure of original data so as to obtain the final categories of these samples. Meanwhile, the whole clustering process is carried out under the correntropy instead of the traditional Euclidean distance framework, which can effectively suppress the influence of the large amount of non-linear and non-Gaussian noise in the real-world data on the clustering robustness. To verify the performance of FCC, five state-of-the-art algorithms are developed as baselines to run with FCC on four large-scale real-world data sets. The results show that FCC can improve the clustering accuracy in most cases(by 8.58%, 6.86% and 1.86% respectively on WebKB, TDT2 and Cora)while greatly improving the clustering efficiency(by several or even dozens of times). Furthermore, to verify the robustness of FCC, varying degrees of random noise and Poisson noise are added to WebKB and Cora to obtain 8 noisy data sets, and all algorithms are run on these noisy data sets under the same conditions. Compared with the other baseline algorithms, FCC can maintain the optimal clustering robustness.关键词：fast clustering;correntropy;anchor graph98|4|0更新时间：2025-07-09
- 摘要：A GIS(gas insulated switchgear)acoustic vibration joint detection system based on LabVIEW software is developed for the purpose to collect the acoustic emission and vibration signals under the action of foreign body defects in GIS online, and to meet the requirements of system functions, such as data acquisition, recording, analysis and evaluation, of foreign body defects. Firstly, based on analyzing the functional requirements of the system, acoustic emission, vibration sensors and high-speed data acquisition cards are used to build a portable multi-channel GIS acoustic and vibration signal acquisition device. Secondly, using the design idea of modularization and functionalization, the software design focuses on the development of the collection and recording, analysis and processing, storage and viewing of the two-way signal of acoustic and vibration, and the development of testing and evaluation interface. Finally, environmental sensors are used to build a detection module of environmental variables in GIS detection scene, and Matlab software is called to perform spectrum analysis and result evaluation of the extracted acoustic and vibration signals. Experimental results show that the system can effectively obtain the acoustic and vibration signals generated by foreign body defects in the GIS by connecting the measuring sensors and realize the 3D dynamic simulation and flight map function of the free metal particles of foreign body defects in the GIS. The developed system has strong functional extensibility, simple and intuitive software interface, and is easy to operate. The detection accuracy of GIS foreign body defects is greater than 90%, which brings convenience to GIS inspection work.关键词：gas insulated switchgear;LabVIEW;acoustic vibration union;foreign body defect detection102|6|2更新时间：2025-07-09
- 摘要：A 3D topography model of surfaces with better calculation convergence is proposed to solve the problems that the existing three-dimensional surface model of machined surface cannot effectively reflect macro and micro comprehensive characteristics of surface, and the calculation convergence is poor in contact and lubrication analysis. Based on the theory of differential geometry, vector functions are used to characterize the macroscopic features such as contour size and curvature of the surface. Based on the fractal theory, the W-M function is used to characterize the microfeatures such as the height and distribution of asperity and the texture direction. Then the vector function and the W-M function are superimposed to construct a three-dimensional surface topography model. In order to solve the problem of calculation convergence, the rough surface is smoothed by filtering, and the continuous and differentiable rough surface is obtained on the premise of retaining the original surface topography. Through comparison of the elastohydrodynamic lubrication analysis, it is found that the calculation convergence of the filtered model is significantly improved. Matlab is used to simulate the constructed three-dimensional rough surface, and the result verifies the effective characterization ability of the model for rough surface morphology. In order to test the applicability of the model, the cycloidal gear, a key part of the RV reducer, is taken as an example to construct the tooth surface model of the cycloidal gear. The model can completely reflect the macroscopic profile and microscopic appearance of the cycloidal gear teeth. The obtained cycloid gear tooth profile model is applied to the mixed lubrication analysis, and the obtained analysis results are consistent with those obtained by using the rough surfaces collected by experiment. The errors of the key parameters are less than 3%, but the calculation time is greatly shortened. The calculation efficiency in the example is improved by 55.7%. By adjusting the parameters of the rough surface model, different rough surfaces can be quickly obtained to participate in the relevant analysis and comparison, which can provide a basis for the optimization design of the macroscopic profile and surface topography of the mechanical joint surfaces.关键词：fractal theory;differential geometry;W-M function;vector function;3D surface topography model48|4|1更新时间：2025-07-09
- 摘要：Aiming at the characteristics of large inertia, pure hysteresis and large overshoot of blast furnace hot blast stove vault temperature control, a fuzzy adaptive sliding mode control strategy is proposed. Combining the strong robustness of sliding mode control with the good approximation ability of fuzzy adaptive control, and considering that system uncertainties and external disturbances will cause the system state to deviate from the sliding mode surface, additional control items are introduced to enable the system trajectory to tend to the sliding mode surface within a finite time; fuzzy adaptive control is used to approximate the unknown parameters and uncertain terms of the system, so as to offset the influence of modeling errors and external disturbances on the system, and realize the correction and compensation of the approximation error; the Lyapunov method to derive the fuzzy adaptive law to ensure the convergence and stability of the entire closed-loop system by adjusting the adaptive weights. Simulation results show that compared with PID control and conventional sliding mode control, the fuzzy adaptive sliding mode control strategy can reduce the adjustment time by up to 35 s after interference is added, the overshoot can be reduced by up to 12.1%, and the system chattering can be reduced by up to 16% compared with the conventional sliding mode control. Engineering application shows that after using the proposed strategy, the vault temperature has a smaller fluctuation range, the deviation is less than ±5 ℃, and the system stability and anti-interference ability are significantly improved, which indicates that the fuzzy adaptive sliding mode controller has smaller chattering, faster response, and higher precision.关键词：blast furnace hot blast stove;vault temperature;sliding mode control;fuzzy adaptive control73|4|4更新时间：2025-07-09
- 摘要：A multidomain anti-interference scheme with joint power domain and time domain in the wireless relay system based on Stackelberg game is proposed to solve the problem that under imperfect circumstances the relay system in the wireless communication is easy to be attacked by jammer. First, in the non-ideal case of incomplete channel information and estimation errors of power and time parameters, a legitimate system including the source node and relay node is set as the leader according to the theory of Stackelberg game, and the jammer is set as a follower. The legitimate system works in a half-duplex mode, and its parameters include the transmit power of source node, the transmit power of relay node, and the frequency hopping period, while the parameters of the jammer include the signal detection time and the power allocation of the interference signal. Then, utility functions of the leader and the follower are respectively constructed based on the equivalent signal-to-interference-noise ratio of receiver. Therefore, the legitimate system sets its parameters to maximize its own utility function so as to improve the effect of anti-jamming while the jammer also adjusts its parameters to maximize its own utility function so as to improve the effect of jamming. Finally, the backward induction method is used to solve the problem of maximizing the utility functions of the two parts in the game. Closed form expressions of the multi-domain jamming parameters are derived, and a genetic algorithm based on exponential distribution is proposed to obtain the optimal multi-domain parameters of the source and relay. Simulation results show that, when the transmitting power cost factor is 0.7, the legitimate utility function value of the proposed scheme is at least twice of those achieved by the power-domain game scheme, time-domain game scheme and multi-domain random scheme, and the jammer utility function value reduces at least 50% compared to those of the power-domain game scheme, time-domain game scheme and multi-domain random scheme.关键词：wireless relay system;incomplete channel information;Stackelberg game;anti-jamming65|4|1更新时间：2025-07-09
- 摘要：Aiming at the problems of slow transient response speed and difficult parameter design of DC-DC converters with right half plane(RHP)zero when they work in a wide range of load, a mathematical model of negative regulated voltage transient state is established by taking Buck-Boost converter as an example, and based on the model, the relationship between the peak time of negative regulated voltage and load resistance is analyzed. It is pointed out that when the minimum load resistance is smaller than the critical load resistance, the peak time of negative voltage regulation increases with the increase of load resistance. When the minimum load resistance is greater than the critical load resistance, the peak time of negative voltage decreases with the increase of load resistance. When the load resistance and the critical load resistance are equal, the negative voltage peak time reaches the maximum value. According to the relationship between the peak time of negative voltage regulation and the load resistance, a parameter design method for Buck-Boost converter with wide load range and RHP zero point is proposed. Experimental results show that the proposed parameter design method effectively improves the transient response speed of the Buck-Boost converter with wide load range. These results may serve as reference for the parameter design of DC-DC converter with wide load range and RHP zero point.关键词：right half plane zero;wide load range;negative voltage;transient performance;parameter design56|4|2更新时间：2025-07-09
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