Physical Simulation of Strata Failure and Its Impact on Overlying Unconsolidated Aquifer at Various Mining Depths

This paper studies the measurement of motion parameters of a parachute scanning platform. The movement of a parachute scanning platform has fast rotational velocity and a complex attitude. Therefore, traditional measurement methods cannot measure the motion parameters accurately, and thus fail to satisfy the requirements for the measurement of parachute scanning platform motion parameters. In order to solve these problems, a method for measuring the motion parameters of a parachute scanning platform based on a combination of magnetic and inertial sensors is proposed in this paper. First, scanning motion characteristics of a parachute-terminal-sensitive projectile are analyzed. Next, a high-precision parachute scanning platform attitude measurement device is designed to obtain the data of magnetic and inertial sensors. Then the extended Kalman filter is used to filter and observe errors. The scanning angle, the scanning angle velocity, the falling velocity, and the 2D scanning attitude are obtained. Finally, the accuracy and feasibility of the algorithm are analyzed and validated by MATLAB simulation, semi-physical simulation, and airdrop experiments. The presented research results can provide helpful references for the design and analysis of parachute scanning platforms, which can reduce development time and cost.

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Physical simulation of nuclear reactor power plant systems

10.1145/1457720.1457735 ◽

1958 ◽

Author(s):

J. J. Stone ◽

B. B. Gordon ◽

R. S. Boyd

Keyword(s):

Power Plant ◽

Nuclear Reactor ◽

Physical Simulation ◽

Reactor Power ◽

Reactor Power Plant

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The influence of advance speed on overburden movement characteristics in longwall coal mining: insight from theoretical analysis and physical simulation

Journal of Geophysics and Engineering ◽

10.1093/jge/gxab005 ◽

2021 ◽

Vol 18 (1) ◽

pp. 163-176

Author(s):

Penghua Han ◽

Cun Zhang ◽

Zhaopeng Ren ◽

Xiang He ◽

Sheng Jia

Keyword(s):

Physical Simulation ◽

Impact Load ◽

Main Roof ◽

Longwall Face ◽

Mine Safety ◽

Efficient Production ◽

Time Space ◽

Mining Pressure ◽

The Impact ◽

Advance Speed

Abstract The advance speed of a longwall face is an essential factor affecting the mining pressure and overburden movement, and an effective approach for choosing a reasonable advance speed to realise coal mine safety and efficient production is needed. To clarify the influence of advance speed on the overburden movement law of a fully mechanised longwall face, a time-space subsidence model of overburden movement is established by the continuous medium analysis method. The movement law of overburden in terms of the advance speed is obtained, and mining stress characteristics at different advance speeds are reasonably explained. The theoretical results of this model are further verified by a physical simulation experiment. The results support the following conclusions. (i) With increasing advance speed of the longwall face, the first (periodic) rupture interval of the main roof and the key stratum increase, while the subsidence of the roof, the fracture angle and the rotation angle of the roof decrease. (ii) With increasing advance speed, the roof displacement range decreases gradually, and the influence range of the advance speed on the roof subsidence is 75 m behind the longwall face. (iii) An increase in the advance speed of the longwall face from 4.89 to 15.23 m/d (daily advancing of the longwall face) results in a 3.28% increase in the impact load caused by the sliding instability of the fractured rock of the main roof and a 5.79% decrease in the additional load caused by the rotation of the main roof, ultimately resulting in a 9.63% increase in the average dynamic load coefficient of the support. The roof subsidence model based on advance speed is proposed to provide theoretical support for rational mining design and mining-pressure-control early warning for a fully mechanised longwall face.

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Experimental and Numerical Study of the Effects of the Reversal Hot Rolling Conditions on the Recrystallization Behavior of Austenite Model Alloys

Metals ◽

10.3390/met11010026 ◽

2020 ◽

Vol 11 (1) ◽

pp. 26

Author(s):

Krzysztof Muszka ◽

Mateusz Sitko ◽

Paulina Lisiecka-Graca ◽

Thomas Simm ◽

Eric Palmiere ◽

...

Keyword(s):

Microstructure Evolution ◽

Hot Rolling ◽

Strain Path ◽

Physical Simulation ◽

Numerical Study ◽

Kinematic Hardening ◽

Process Window ◽

Recrystallization Behavior ◽

Full Field ◽

Strain Reversal

The experimental and numerical study of the effects of the recrystallization behavior of austenite model alloys during hot plate rolling on reverse rolling is the main goal of the paper. The computer models that are currently applied for simulation of reverse rolling are not strain-path-sensitive, thus leading to overestimation of the processing parameters outside the accepted process window (e.g., deformation in the partial austenite recrystallization region). Therefore, in this work, a particular focus is put on the investigation of strain path effects that occur during hot rolling and their influence on the microstructure evolution and mechanical properties of microalloyed austenite. Both experimental and numerical techniques are employed in this study, taking advantage of the integrated computational material engineering concept. The combined isotropic–kinematic hardening model is used for the macroscale predictions to take into account softening effects due to strain reversal. The macroscale model is additionally enriched with the full-field microstructure evolution model within the cellular automata framework. Examples of obtained results, highlighting the role of the strain reversal on the microstructural response, are presented within the paper. The combination of the physical simulation of austenitic model alloys and computer modeling provided new insights into optimization of the processing routes of advanced high-strength steels (AHSS).

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Physical simulation on the 1550 nm Infrared Photon Absortion in Ge and Graphene filled Silicon Micro-hole Array

2020 Opto-Electronics and Communications Conference (OECC) ◽

10.1109/oecc48412.2020.9273652 ◽

2020 ◽

Author(s):

Ching-Yu Hsu ◽

Zingway Pei

Keyword(s):

Physical Simulation ◽

Hole Array ◽

Micro Hole ◽

Infrared Photon

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Controlling mine pressure by subjecting high-level hard rock strata to ground fracturing

International Journal of Coal Science & Technology ◽

10.1007/s40789-020-00405-1 ◽

2021 ◽

Author(s):

Rui Gao ◽

Tiejun Kuang ◽

Yanqun Zhang ◽

Wenyang Zhang ◽

Chunyang Quan

Keyword(s):

Energy Release ◽

Physical Simulation ◽

Hard Rock ◽

Structural Characteristics ◽

Effective Control ◽

Mine Pressure ◽

Control Effect ◽

Propagation Length ◽

Ground Pressure ◽

High Level

AbstractWhen mining extra-thick coal seams, the main cause of strong ground pressure are the high-level thick and hard strata, but as yet there is no active and effective control technology. This paper proposes the method of subjecting hard roofs to ground fracturing, and physical simulation is used to study the control effect of ground fracturing on the strata structure and energy release. The results show that ground fracturing changes the structural characteristics of the strata and reduces the energy release intensity and the spatial extent of overburden movement, thereby exerting significant control on the ground pressure. The Datong mining area in China is selected as the engineering background. An engineering test was conducted on site by ground horizontal well fracturing, and a 20-m-thick hard rock layer located 110 m vertically above the coal seam was targeted as the fracturing layer. On-site microseismic monitoring shows that the crack propagation length is up to 216 m and the height is up to 50 m. On-site mine pressure monitoring shows that (1) the roadway deformation is reduced to 100 mm, (2) the periodic weighting characteristics of the hydraulic supports are not obvious, and (3) the ground pressure in the working face is controlled significantly, thereby showing that the ground fracturing is successful. Ground fracturing changed the breaking characteristics of the high-level hard strata, thereby helping to ameliorate the stress concentration in the stope and providing an effective control approach for hard rock.

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