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The positioning control of hydraulic support pushing system in fully mechanized mining face is the key technical support to realize intelligent mining. The opening and closing of the existing support switch reversing valve will cause sudden change of system pressure and flow under the condition of high pressure and large flow, which will affect the life of components, the precision and stability of the actuator movement. To solve the problem, the structure of two-speed buffer valve for hydraulic support pushing circuit was designed. Firstly, through theoretical research on the pushing system and the two-speed buffer valve, the pressure characteristics during the start-up and operation of the system after adding the two-speed buffer valve were analyzed. Then, the valve and hydraulic circuit were modeled by SimulationX to analyze the influence of key parameters on valve pressure drop and speed of hydraulic execution system. Finally, an experimental platform was built to study the pressure characteristics of double valve series pushing system under different pressure flow of liquid supply. The research results show that when the two-speed buffer valve is used, the pressure and velocity change thresholds of the system are reduced, which reduces the pressure fluctuation in front of the valve and its effect on the system pressure. At the same time, under different system pressure and flow, the downstream pressure characteristics of the valve are improved, the steady-state pressure anti-interference is enhanced. Therefore, the effectiveness of the scheme is verified, and the basis is provided for the optimization of the downhole valve control cylinder scheme and the subsequent valve. [ABSTRACT FROM AUTHOR]

Both rule-based reasoning (RBR) and case-based reasoning (CBR) methods are applicable to the field of belt conveyor fault diagnosis. Aiming at the problem that both of them focus on cause analysis or maintenance means in fault diagnosis, the reasoning mechanism based on RBR+CBR dual reasoning was studied, and an expert system was established to diagnose the fault of belt conveyor drive system. Firstly, the expert system for fault diagnosis was constructed on the basis of the structure of traditional expert system. Then, the fault tree of the belt conveyor drive system was established according to the fault mechanism, the expert system fault rule base was designed by using the generative representation method, and according to the fault cases and expert experience, the expert system fault case base was designed by using the matrix representation method. The expert system reasoning mechanism was designed based on the rule-based reasoning (RBR) and case-based reasoning (CBR) methods. And the human-computer interaction interface of the expert system was designed by using the LabVIEW program development platform, which realized the series communication process between the sensor, knowledge base and client. Finally, in order to verify the feasibility of the above expert system, experiments were conducted on a belt conveyor operating site in a certain mine, and the results were analyzed. The results of the study show that, the fault cause analysis accuracy of the belt conveyor expert system exceeds 95%, and the effectiveness of the fault repair plan of the expert system exceeds 94%. In comparison with the expert system supported by RBR and CBR algorithms, this expert system has better convergence, effectiveness and accuracy, and it proposes an effective method for the intelligent fault diagnosis of the belt conveyor. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Mechanical & Electrical Engineering is the property of Mechanical & Electrical Engineering Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem that the load fluctuation of permanent magnet outer rotor multi-rope friction mine hoist affects the stability of the hoist system; the control system of the hoist was studied. Firstly, the hoist structure and control theory were analyzed. According to the characteristics of its hidden pole rotor structure, the vector control strategy of id=0 was chosen. The smooth speed curve and sliding mode speed controller were proposed to optimize the stability of the hoist, and the stability of the sliding mode speed controller was judged by Lyapunov stability theorem. Then, the mechatronics simulation model of lifting system was built and studied simulation. Finally, the reliability of the simulation model was verified by field tests. The results show that acceleration mutation has obvious influence on hoist speed overshoot and q axis current of hoist is obviously correlated with acceleration. The speed overshoot of the hoist was reduced by 68% by using only a smooth speed curve, but the speed fluctuation caused by the load fluctuation has no obvious restraining effect. The speed overshoot of the hoist was reduced by 73% by using only the sliding mode speed controller. When using both smooth speed curve and sliding mode speed controller, the hoist speed fluctuation is reduced by 90%, and it has obvious restraining effect on load fluctuation. [ABSTRACT FROM AUTHOR]

Aiming at the non-uniformity of the air film between the conveyor belt and the trough during the operation of the air-cushion belt conveyor, a comprehensive study was executed by means of simulation analysis. Firstly, the air cushion pressure was theoretically deduced according to the principle of force balance, and the theoretical distribution expression and curve of air cushion pressure were given. Then, by constructing a gas flow model around the stomata, the pressure and velocity distribution of the flow field near the stomata were deduced, by constructing a cross-sectional gas outflow model, the outflow velocity and pressure distribution of the air cushion along the cross-section were deduced. Finally, the air cushion field was simulated and analyzed based on the fluid dynamics analysis software Fluent, the effects of different pore velocity, pore arrangement and air cushion thickness on the characteristics of the air cushion flow field were studied. The results indicate that air cushion pressure decreases with increasing air cushion thickness. The bearing capacity of the air cushion has a linear relationship with the stomatal flow rate, and the linear ratio is K=41.57. The optimal design parameters for the arrangement of air holes is the aperture of 7 mm and the hole spacing of 75 mm. When the air cushion thickness is 3 mm ～5 mm, air cushion stiffness decreases with increasing air cushion thickness. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problems of unstable flow field and large pressure loss in FBD No. 8. 0 mine counter rotating axial flow fan, the geometric parameters of collector and fairing in the fan were optimized. First, the inlet diameter, length of the collector and the two horizontal lengths of the fairing were selected as the orthogonal test factors, and the total pressure efficiency was the evaluation index of the test to explore the influence on the aerodynamic performance of the fan under the joint action of the collector and the fairing. Then, according to the orthogonal test table of L9(34), nine test schemes were designed and numerically calculated. Finally, through the range analysis method, the primary and secondary influence order of geometric parameters on fan efficiency was obtained, and the optimal combination of size parameters was determined. The results show that comparing with the prototype fan, the total pressure and efficiency of the optimized fan are respectively increased by 2. 64% and 1. 74% at the flow point of 750 m³/min. Under the full flow condition, the total pressure and efficiency are increased by 2. 12% and 2. 31% on average. The optimized fan can effectively alleviate the vortex phenomenon at the inlet, reduce the pressure difference inside the front end of the air duct and improve the air inlet;the vorticity on the blade surface is reduced and the fan performance is improved. [ABSTRACT FROM AUTHOR]

Aiming at the problems of unwinding or overloading of the winding motor caused by the unstable winding tens ion of the belt conveyor during the belt change process, the constant tension control of the belt winding machine was studied, a mathematical model of winding tension control was proposed, and a center winding type winding machine and a control strategy to achieve constant tension winding through PI frequency conversion speed control were designed through this model. The tape coiler model was simplified, Recurdyn-R2R2D was used to build a simplified dynamic simulation model of the tape coiler, and a constant tension control strategy was built in Colink aceording to the tension control model. Finally. the effect of constant tension winding was analyzed through Co-simulation of Recurdyn and Colink. The results indicate that the PI variable frequency speed regulation designed by the tension control model to realize the control strategy of constant tension winding can stabilize the unit tension at 5 N/mm² during the winding process, and the maximum overshoot does not exceed 8%. It also can sense the sudden increase signal of winding tension to quickly control the stop of the winding machine to prevent the motor from overloading, which provides a reference for the design and field application of the conveyor belt winder. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical & Electrical Engineering is the property of Mechanical & Electrical Engineering Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to the relationship between the characteristics and winding state of the bending right regular lay rope，the space curve of single helical wire for the bending wire rope was established.Based on the theory of differential geometry，the Frenet-Serret frame was built and the space curve of double helical wire for the right regular lay rope was deduced.Two finite element models for the 12-6×7IWRC right lang lay and right ordinary lay rope were established. The boundary conditions were set through restricting the degree of freedom in three directions at one end of wire rope and loading the mass force at the other end. The distribution of equivalent stress and deformation of two models were compared. The study results show that the amplitude of equivalent stress for the right regular lay rope is greater than that of the right lang lay rope and the deformation of the right lang lay rope is greater than that of the right regular lay rope.The tensile tests for the right regular lay rope were conducted. Compared the deformations of the ropes obtained by the present finite element analysis with those obtained experimentally and theoretical value by Costello theory，the valve of maximum errors is 10%，which suggests that the models are valid. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)