ANALYSIS OF SHEARER VIBRATION CHARACTERISTICS UNDER DIFFERENT LIFT ANGLE

According to shearer vibration problems in the practical work,using multi-body dynamics theory,considering shearer support characteristics of guide boots and flat boots,and the stiffness of rocker arm and adjustment height oil vat,6 degrees of freedom dynamic model in the vertical direction of shearer was established.The vertical direction of shearer drum load was used as an external excitation,and the effect of different lift angle on vertical direction vibration characteristics of shearer were solved by using numerical analysis method.The results show that the lift angle has great influence on vibration displacement of drum and ranging arm when the range is 17° 37°,and the displacement range is 21.5521 15.424 mm,9.4005 ~3.306 4 mm.Because of the low frequency vibration of shearer under actual operating conditions,the vibration acceleration under different lift angle is insensitive

ANALYSIS OF SHEARER VERTICAL DIRECTION VIBRATION CHARACTERISTICS UNDER DIFFERENT HAULAGE SPEED

According to shearer vibration problems in the practical work,using multi-body dynamics theory,considering the connection characteristics between walking unit of shearer and scraper conveyor,the support characteristics of adjustment height oil vat,the stiffness of rocker arm of shearer,the connection characteristics between the parts of shearer,vibration angle of shearer,6 degrees of freedom dynamic model in the vertical direction of shearer was established.The vertical direction of shearer drum load was used as an external excitation,and the effect of different haulage speed on vertical direction vibration characteristics of shearer were solved by using numerical analysis method.The results show that the haulage speed has great influence on vibration displacement of front and rear cutting unit when the range is 2 m/min～5 m/min,the displacement range of front and rear drum is 12.3325 mm～38.9104 mm、7.5240 mm～23.7396 mm,and the displacement range of front and rear rocker arm is 4.8826 mm～15.4052 mm、3.0548 mm～9.6384 mm.Finally,the results of model is verified by experiment

7-DOF NONLINEAR VIBRATION ANALYSIS OF SHEARER UNDER CONDITION EXCITATION

In order to study the influence of shearer traction speed on its dynamic characteristics,using the three-axis force of pick as the description of cutting incentive of shearer pick,Hertz contact theory was used to describe shearer’s smooth boot brace stiffness and damping. Nonlinear model of meshing gear with the clearance was used to describe brace stiffness and damping of shearer guide boot and the pin rows. 7-DOF dynamic model of shearer was established according to Lagrange ’s equations. Vibration characteristics of shearer under different traction speed was solved by numerical methods. The results show that the increasing of speed have great influence on the vibration displacement of back-end drum,have little effect on the fuselage,and have significant influence on Y axis vibration angle of the fuselage

The Incoherence of Deep Isotropic Neural Networks Increases Their Performance in Image Classification

Although neural-network architectures are critical for their performance, how the structural characteristics of a neural network affect its performance has still not been fully explored. Here, we map architectures of neural networks to directed acyclic graphs (DAGs), and find that incoherence, a structural characteristic to measure the order of DAGs, is a good indicator for the performance of corresponding neural networks. Therefore, we propose a deep isotropic neural-network architecture by folding a chain of the same blocks and then connecting the blocks with skip connections at different distances. Our model, named FoldNet, has two distinguishing features compared with traditional residual neural networks. First, the distances between block pairs connected by skip connections increase from always equal to one to specially selected different values, which lead to more incoherent graphs and let the neural network explore larger receptive fields and, thus, enhance its multi-scale representation ability. Second, the number of direct paths increases from one to multiple, which leads to a larger proportion of shorter paths and, thus, improves the direct propagation of information throughout the entire network. Image-classification results on CIFAR-10 and Tiny ImageNet benchmarks suggested that our new network architecture performs better than traditional residual neural networks. FoldNet with 25.4M parameters can achieve 72.67% top-1 accuracy on the Tiny ImageNet after 100 epochs, which is competitive compared with the-state-of-art results on the Tiny ImageNet

The Incoherence of Deep Isotropic Neural Networks Increases Their Performance in Image Classification

Although neural-network architectures are critical for their performance, how the structural characteristics of a neural network affect its performance has still not been fully explored. Here, we map architectures of neural networks to directed acyclic graphs (DAGs), and find that incoherence, a structural characteristic to measure the order of DAGs, is a good indicator for the performance of corresponding neural networks. Therefore, we propose a deep isotropic neural-network architecture by folding a chain of the same blocks and then connecting the blocks with skip connections at different distances. Our model, named FoldNet, has two distinguishing features compared with traditional residual neural networks. First, the distances between block pairs connected by skip connections increase from always equal to one to specially selected different values, which lead to more incoherent graphs and let the neural network explore larger receptive fields and, thus, enhance its multi-scale representation ability. Second, the number of direct paths increases from one to multiple, which leads to a larger proportion of shorter paths and, thus, improves the direct propagation of information throughout the entire network. Image-classification results on CIFAR-10 and Tiny ImageNet benchmarks suggested that our new network architecture performs better than traditional residual neural networks. FoldNet with 25.4M parameters can achieve 72.67% top-1 accuracy on the Tiny ImageNet after 100 epochs, which is competitive compared with the-state-of-art results on the Tiny ImageNet

ANALYSIS OF SHEARER SIDE DIRECTION VIBRATION CHARACTERISTICS UNDER DIFFERENT HAULAGE SPEED

According to shearer vibration problems in the practical work,using multi-body dynamics theory,considering shearer support characteristics of guide boots and pin-rail,the friction between flat boots and middle trough,the connection characteristics between the parts of shearer,vibration angle of shearer,6 degrees of freedom dynamic model in the lateral direction of shearer was established. The axial direction of shearer drum load was used as an external excitation,and the effect of different haulage speed on lateral direction vibration characteristics of shearer were solved by using numerical analysis method. The results show that the haulage speed has great influence on vibration displacement of front and rear cutting unit when the range is 2 m/min 5 m/min,the displacement range of front and rear drum is 4. 994 1 mm 11. 262 3 mm、4. 842 0 mm 10. 791 7 mm,and the displacement range of front and rear rocker arm is 3. 199 1 mm 5. 709 7 mm、3. 046 3 mm 5. 236 9 mm. Research results provide the basis for shearer in the actual production process. Finally,the results of model is verified by experiment

RESEARCH ON DYNAMIC CHARACTER OF PLOUGH UNDER OBLIQUE CONDITION AND OPTIMIZATION DESIGN OF OPERATION PARAMETERS

To research the dynamic character of plough under oblique cut conditions,the cutting coal wall depth of planing tool and the condition of participate in cutting were derived. The dynamic model of plough was established by finite elem ent method. The numerical simulation analysis of dynamic character of plough was executed. velocity and tension fluctuation curve of plow head and chains were obtained. Take feeding velocity and middle trough swing angle as design variables,and take minimal unit energy consumption and minimal load fluctuation rate as objective function. The Optimal design was executed by the method of multi-population genetic algorithm. The results are obtained that the optimal feeding velocity is 1. 2m/s,and middle trough optimal swing angle are 1°,1°,0. 7°. The results provide theoretical basis for coal plough in engineering

RIGID-FLEXIBLE COUPLING DYNAMICS OF COAL WINNING MACHINE CUTTING PART DRIVE SYSTEM SIMULATION

On the basis of the theory of rigid-flexible coupling multibody dynamics as well as the transmission system of coal winning machine cutting part the transmission principle and structure parameters,the dynamic characteristics of coal winning machine cutting part drive system was researched for the problem about dynamic characteristics of coal winning machine cutting part the transmission system. The rigid-flexible coupling dynamics model of coal winning machine cutting part for gear transmission system was built in Recurdyn software environment. To the cutting force in drum three loads,Transmission Model was under full consideration of the flexible drive shaft in all directions feature and calculated the gear meshing force,strain and bearing junctioncontact. Results showed that 11 th gear mesh together is the biggest,11272634. 4N. The maximum contact force,912317. 98 N,is measured at the place of the shaft 5 bearings 1. Results provide a basis for optimum design of the transmission system and prediction of fatigue life

Effects of Directional Wave Spectra on the Modeling of Ocean Radar Backscatter at Various Azimuth Angles by a Modified Two-Scale Method

Knowledge of the ocean backscatter at various azimuth angles is critical to the radar detection of the ocean environment. In this study, the modified two-scale model (TSM), which introduces a correction term in the conventional TSM, is improved based on the empirical model, CMOD5.n. Then, the influences of different directional wave spectra on the prediction of azimuthal behavior of ocean radar backscatter are investigated by comparing the simulated results with CMOD5.n and the Advanced Scatterometer (ASCAT) measurements. The results show that the overall performance of the single spectra of D, A, E, and H18 and the composite spectra of AH18 and AEH18 in predicting ocean backscatter are different at different wind speeds and incidence angles. Generally, the AH18 spectrum has better performance at low and moderate wind speeds, while the A spectrum works better at high wind speed. Nevertheless, the wave spectra have little effect on the prediction of the azimuthal fluctuation of scattering, which is highly dependent on the directional spreading function. The relative patterns of azimuthal undulation produced by different spreading functions are rather different at different wind speeds, but similar under different incidence angles. The Gaussian spreading function generally has better performance in predicting the azimuthal fluctuation of scattering