Performance of paddy dryer with screw conveyor assisted parabolic cylinder collector as thermal generator

During shield machine tunneling, the earth pressure in the sealed cabin must be kept balanced to ensure construction safety. As there is a strong nonlinear coupling relationship among the tunneling parameters, it is difficult to control the balance between the amount of soil entered and the amount discharged in the sealed cabin. So, the control effect of excavation face stability is poor. For this purpose, a coordinated optimization control method of shield machine based on dynamic fuzzy neural network (D-FNN) direct inverse control is proposed. The cutter head torque, advance speed, thrust, screw conveyor speed and earth pressure difference in the sealed cabin are selected as inputs, and the D-FNN control model of the control parameters is established, whose output are screw conveyor speed and advance speed at the next moment. The error reduction rate method is introduced to trim and identify the network structure to optimize the control model. On this basis, an optimal control system for earth pressure balance (EPB) of shield machine is established based on the direct inverse control method. The simulation results show that the method can optimize the control parameters coordinately according to the changes of the construction environment, effectively reduce the earth pressure fluctuations during shield tunneling, and can better control the stability of the excavation surface.

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The Mechanical Research of Vertical Screw Conveyor Particle Group Based on the Radial Change of Material Speed

Journal of Physics Conference Series ◽

10.1088/1742-6596/1952/3/032026 ◽

2021 ◽

Vol 1952 (3) ◽

pp. 032026

Author(s):

Lei Mei ◽

Chuang Cheng ◽

Ziqiang Fan

Keyword(s):

Screw Conveyor ◽

Particle Group

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Controlling Film Thickness Distribution by Magnetron Sputtering with Rotation and Revolution

Coatings ◽

10.3390/coatings11050599 ◽

2021 ◽

Vol 11 (5) ◽

pp. 599

Author(s):

Handan Huang ◽

Li Jiang ◽

Yiyun Yao ◽

Zhong Zhang ◽

Zhanshan Wang ◽

...

Keyword(s):

Magnetron Sputtering ◽

Film Thickness ◽

Multilayer Film ◽

Thickness Distribution ◽

Parabolic Cylinder ◽

Particle Model ◽

Planetary Motion ◽

X Rays ◽

X Ray ◽

Sputtering System

The laterally graded multilayer collimator is a vital part of a high-precision diffractometer. It is applied as condensing reflectors to convert divergent X-rays from laboratory X-ray sources into a parallel beam. The thickness of the multilayer film varies with the angle of incidence to guarantee every position on the mirror satisfies the Bragg reflection. In principle, the accuracy of the parameters of the sputtering conditions is essential for achieving a reliable result. In this paper, we proposed a precise method for the fabrication of the laterally graded multilayer based on a planetary motion magnetron sputtering system for film thickness control. This method uses the fast and slow particle model to obtain the particle transport process, and then combines it with the planetary motion magnetron sputtering system to establish the film thickness distribution model. Moreover, the parameters of the sputtering conditions in the model are derived from experimental inversion to improve accuracy. The revolution and rotation of the substrate holder during the final deposition process are achieved by the speed curve calculated according to the model. Measurement results from the X-ray reflection test (XRR) show that the thickness error of the laterally graded multilayer film, coated on a parabolic cylinder Si substrate, is less than 1%, demonstrating the effectiveness of the optimized method for obtaining accurate film thickness distribution.

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Numerical Simulation of EPB Shield Tunnelling with TBM Operational Condition Control Using Coupled DEM–FDM

Applied Sciences ◽

10.3390/app11062551 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2551

Author(s):

Hyobum Lee ◽

Hangseok Choi ◽

Soon-Wook Choi ◽

Soo-Ho Chang ◽

Tae-Ho Kang ◽

...

Keyword(s):

Numerical Simulation ◽

Large Scale ◽

Tunnel Boring Machine ◽

Chamber Pressure ◽

Screw Conveyor ◽

Shield Tunnel ◽

Pressure Balance ◽

Operational Conditions ◽

Shield Tunnelling ◽

Epb Shield

This study demonstrates a three-dimensional numerical simulation of earth pressure balance (EPB) shield tunnelling using a coupled discrete element method (DEM) and a finite difference method (FDM). The analysis adopted the actual size of a spoke-type EPB shield tunnel boring machine (TBM) consisting of a cutter head with cutting tools, working chamber, screw conveyor, and shield. For the coupled model to reproduce the in situ ground condition, the ground formation was generated partially using the DEM (for the limited domain influenced by excavation), with the rest of the domain being composed of FDM grids. In the DEM domain, contact parameters of particles were calibrated via a series of large-scale triaxial test analyses. The model simulated tunnelling as the TBM operational conditions were controlled. The penetration rate and the rotational speed of the screw conveyor were automatically adjusted as the TBM advanced to prevent the generation of excessive or insufficient torque, thrust force, or chamber pressure. Accordingly, these parameters were maintained consistently around their set operational ranges during excavation. The simulation results show that the proposed numerical model based on DEM–FDM coupling could reasonably simulate EPB driving while considering the TBM operational conditions.

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Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.261-263.1831 ◽

2011 ◽

Vol 261-263 ◽

pp. 1831-1835

Author(s):

Guo Gang Qiao ◽

Da Jun Yuan ◽

Bo Liu

Keyword(s):

Experimental Research ◽

Clay Soil ◽

Soil Improvement ◽

Engineering Properties ◽

Screw Conveyor ◽

Test Results ◽

X Ray Diffraction ◽

Shield Tunneling ◽

Red Clay ◽

Improvement Measures

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.

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