In situ measurement of water accumulation in overlying goaf of coal mine-a transient electromagnetic-based study

2021 ◽  
Vol 14 (5) ◽  
Author(s):  
Zhiyong Fu ◽  
Jian Kang ◽  
Dong-wei Qiu
Keyword(s):  
Coal Mine ◽  
In Situ Measurement ◽  
Transient Electromagnetic ◽  
Water Accumulation

scholarly journals Application of Transient Electromagnetic in Detection of Water Accumulation in Broad Coal Mine

2021 ◽  
Vol 06 (08) ◽  
Author(s):  
Gao Chong ◽  
Keyword(s):  
Coal Mine ◽  
Power Supply ◽  
Electromagnetic Emission ◽  
Mining Area ◽  
Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Wire Frame ◽  
Water Accumulation ◽  
Supply Current ◽  
Mining Coal

In view of the problem of serious water accumulation and frequent accidents in the coal mine mining area, the distribution range of Yuzhou Shenhuo Kuanfa Mining Coal (hereinafter referred to as Kuanfa Coal Mine) is detected by transient electromagnetic method. The transient electromagnetic emission wire frame is 480m × 480m, frequency is 8Hz, power supply current is 16A. The research conclusion preliminarily determines that the transient electromagnetic and controllable source audio earth electromagnetic method is applicable for the exploration of the mined space area in Yuzhou mining area, and the construction parameters provide a reliable reference for the accurate exploration of the mined space area in Kuanmining area.

scholarly journals Simulation Research and Application on Response Characteristics of Detecting Water-filled Goaf by Transient Electromagnetic Method

2021 ◽  
Author(s):  
Tingye Qi ◽  
Xiaoming Pei ◽  
Guorui Feng ◽  
Huiru Wei
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Water Inrush ◽  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Induced Voltage ◽  
Measuring Point ◽  
Response Characteristics ◽  
Transient Electromagnetic ◽  
Water Accumulation

Abstract Water inrush disasters poses a great threat to the safe exploitation of coal resources. To solve this problem, the transient electromagnetic method(TEM) was proposed to accurately detect the water accumulation in the goaf. The electromagnetic response characteristics of different water-filled goaves were studied by electromagnetic field theory, numerical simulation and field verification. Through the models of 100% water accumulation, 50% water accumulation, 0% water accumulation, 100% water accumulation with collapsed rock, 50% water accumulation with collapsed rock and 0% water accumulation with collapsed rock goaf, the characteristics of induced voltage attenuation curves were studied. Meanwhile, the relationship between the attenuation voltage value and area of the transmitting coil and the depth of the goaf were also simulated. The results illustrate that the attenuation curve of induced voltage presented a regular exponential decay form in the 0% water accumulation model but existed abnormal exaltation for voltage in water-filled model. Through the linear fitting curve, it can be seen that the abnormal intensity of the induced voltage becomes stronger as the distance between the measuring point and the center of the target decrement. Moreover, the abnormal amplitude of the induced voltage increases with the rise of the water accumulation and collapsed rock will weakly reduce the low-resistance anomalous effect on the water-accumulated goaf. In addition, the response value of the attenuation voltage increased in second-order as the area of the transmitting coil increases, but decreased in third-order as the depth of the target body increases. The field detection results of the Majiliang coal mine also confirmed the theoretical analysis and the numerical simulation. The conclusions had important guiding significance for accurate detection of coal mine goaf.

In Situ Measurement of Soil Heat Flux with the Gradient Method

2003 ◽  
Vol 2 (4) ◽  
pp. 589
Author(s):  
Douglas R. Cobos ◽  
John M. Baker
Keyword(s):  
Heat Flux ◽  
Gradient Method ◽  
Soil Heat Flux ◽  
In Situ Measurement

In-Situ Measurement Technique of Stress and Structure Change

2015 ◽  
Vol 84 (8) ◽  
pp. 567-572
Author(s):  
Tadafumi HASHIMOTO ◽  
Masahito MOCHIZUKI
Keyword(s):  
Measurement Technique ◽  
Structure Change ◽  
In Situ Measurement

In-situ measurement of α formation kinetics in a metastable β Ti-5553 alloy using laser ultrasonics

2021 ◽  
Vol 866 ◽  
pp. 158954
Author(s):  
Mariana C.M. Rodrigues ◽  
Thomas Garcin ◽  
Matthias Militzer
Keyword(s):  
In Situ Measurement ◽  
Laser Ultrasonics ◽  
Formation Kinetics

scholarly journals In situ measurement and closed-loop control for powder supply processes

2021 ◽  
Author(s):  
Philipp Peter Breese ◽  
Tobias Hauser ◽  
Daniel Regulin ◽  
Stefan Seebauer ◽  
Christian Rupprecht
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Closed Loop ◽  
In Situ Measurement ◽  
Closed Loop Control ◽  
Loop Control ◽  
Powder Feeder ◽  
Powder Mass

AbstractThe powder mass flow rate is one of the main parameters regarding the geometrical precision of built components in the additive manufacturing process of laser metal deposition. However, its accuracy, constancy, and repeatability over the course of the running process is not given. Reasons among others are the performance of the powder conveyors, the complex nature of the powder behavior, and the resulting issues with existing closed-loop control approaches. Additionally, a direct in situ measurement of the powder mass flow rate is only possible with intrusive methods. This publication introduces a novel approach to measure the current powder mass flow rate at a frequency of 125 Hz. The volumetric powder flow evaluation given by a simple optical sensor concept was transferred to a mass flow rate through mathematical dependencies. They were found experimentally for a nickel-based powder (Inconel 625) and are valid for a wide range of mass flow rates. With this, the dynamic behavior of a vibration powder feeder was investigated and a memory effect dependent on previous powder feeder speeds was discovered. Next, a closed-loop control with the received sensor signal was implemented. The concept as a whole gives a repeatable and accurate powder mass flow rate while being universally retrofittable and applicable. In a final step, the improved dynamic and steady performance of the powder mass flow rate with closed-loop control was validated. It showed a reduction of mean relative errors for step responses of up to 81% compared to the uncontrolled cases.

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