scholarly journals Impact of the Selected Disturbing Factors on Accuracy of the Distance Measurement with the use of Ultrasonic Transducers in a Hard Coal Mine

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 133
Author(s):  
Sławomir Bartoszek ◽  
Grzegorz Ćwikła ◽  
Gabriel Kost ◽  
Krzysztof Nieśpiałowski
Keyword(s):  
Coal Mine ◽  
Distance Measurement ◽  
Ultrasonic Waves ◽  
Ultrasonic Transducers ◽  
Hard Coal ◽  
Airborne Dust ◽  
Measurement Results ◽  
Legal Restrictions ◽  
Mine Roadways ◽  
The Impact

The article presents tests on the possibility of using ultrasonic transducers for accurate distance measurement in hard coal mines. In order to check the impact of selected disturbing factors on the measurement results, test stands were built, and then a full cycle of measurements with the use of different transducers (AR30 and AR41), which were selected and pre-tested in previous research projects, was realized. The impact of such disturbing factors as airborne dust (coal, stone, lime and mixed dust), changes in temperature and humidity on the propagation of ultrasonic waves, amplitude and measurement accuracy was investigated. The tests were preceded by theoretical analysis. It was found that the transducers selected for the tests had a sufficient accuracy and range, so they can be used in the devices planned to be designed, allowing for the determining of the location of a roadheader in hard coal mine roadways, taking into account technical and legal restrictions. It was also specified which disturbing factors should be compensated and what methods and parameters of this compensation should be used.

scholarly journals Research on Ultrasonic Transducers to Accurately Determine Distances in a Coal Mine Conditions

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2532
Author(s):  
Sławomir Bartoszek ◽  
Krzysztof Stankiewicz ◽  
Gabriel Kost ◽  
Grzegorz Ćwikła ◽  
Artur Dyczko
Keyword(s):  
Coal Mine ◽  
Operating Conditions ◽  
Working Environment ◽  
Ultrasonic Transducers ◽  
Hard Coal ◽  
Distance Measurements ◽  
Initial Stage ◽  
Measurement Results ◽  
Ultrasonic Devices ◽  
Locating System

Determining the location of objects, for example roadheader in a hard coal mine, is a task that should be automated in the conditions of state-of-the-art mining. Current solutions do not meet the user’s expectations due to the lack of the possibility of automation, maladjustment to the environment of a hard coal mine or not meeting the legal requirements. The article describes the initial stage of work on an automatic system for determining the position of machines in difficult underground conditions, including the analysis of requirements and constraints, an overview of available solutions, technologies and algorithms, as a result of which devices were selected for further tests. To determine the location, it is necessary to take distance measurements with high accuracy, despite the disturbances resulting from the working environment. Ultrasonic devices were selected and then tested under various operating conditions, including different distances between the transmitter and receiver as well as different directions and intensities of air movement that could distort the measurement results. During tests, sufficient accuracy, as well as other parameters, of the ultrasonic transducers were confirmed, allowing for distance measurements in the required range, suitable for use in the real-time locating system (RTLS) being developed.

scholarly journals The influence of the fault zone width on land surface vibrations after the high-energy tremor in the “Rydułtowy-Anna” hard coal mine

2018 ◽  
Vol 36 ◽  
pp. 02007 ◽  
Author(s):  
Elżbieta Pilecka ◽  
Dariusz Szwarkowski
Keyword(s):  
Rock Mass ◽  
Fault Zone ◽  
Seismic Wave ◽  
Coal Mine ◽  
Land Surface ◽  
High Energy ◽  
Hard Coal ◽  
Surface Vibrations ◽  
The Impact ◽  
Damage Risk

In the article, a numerical analysis of the impact of the width of the fault zone on land surface tremors on the area of the “Rydułtowy – Anna” hard coal mine was performed. The analysis covered the dynamic impact of the actual seismic wave after the high-energy tremor of 7 June 2013. Vibrations on the land surface are a measure of the mining damage risk. It is particularly the horizontal components of land vibrations that are dangerous to buildings which is reflected in the Mining Scales of Intensity (GSI) of vibrations. The run of a seismic wave in the rock mass from the hypocenter to the area’s surface depends on the lithology of the area and the presence of fault zones. The rock mass network cut by faults of various widths influences the amplitude of tremor reaching the area’s surface. The analysis of the impact of the width of the fault zone was done for three alternatives.

Monitoring of the Setting and early Hardening with Ultrasonic Waves

2018 ◽  
Vol 776 ◽  
pp. 51-54 ◽  
Author(s):  
Iva Rozsypalová ◽  
Ondřej Karel ◽  
Barbara Kucharczyková ◽  
Dalibor Kocáb ◽  
Romana Halamová
Keyword(s):  
Test Specimen ◽  
Ultrasonic Waves ◽  
Ultrasonic Transducers ◽  
Cement Composites ◽  
Measurement Equipment ◽  
Cement Pastes ◽  
Innovative Method ◽  
Measurement Results ◽  
Measurement Principle ◽  
Method Of Measurement

The paper deals with the experimental investigation aimed at the continual monitoring of the process of setting and early hardening in cement pastes and mortars using the measurement equipment Vikasonic. The measurement principle consists in measuring the time of ultrasonic pulses transit through a test specimen placed between two ultrasonic transducers. This innovative method of measurement could in the future suitably complement or, in some cases, completely substitute the measurement of setting in cement composites using the Vicat apparatus. The pilot measurement results performed on the cement pastes and mortars are presented in the paper.

scholarly journals The Impact of the Low Throw Fault on the Stability of Roadways in a Hard Coal Mine

2017 ◽  
Vol 39 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Piotr Małkowski ◽  
Łukasz Ostrowski ◽  
Piotr Bachanek
Keyword(s):  
Fault Zone ◽  
Coal Mine ◽  
Geological Structure ◽  
Hard Coal ◽  
Convergence Results ◽  
Roadway Stability ◽  
Special Measuring ◽  
The Stability ◽  
Degree Of Convergence ◽  
The Impact

Abstract Ensuring roadways stability in hard coal mines is one of the main challenges faced by engineers. A changeable geological structure have caused the roadway’s conditions to vary, thus influencing its stability. One of the causes of those changes is the presence of a previously undiscovered fault zone (small faults crossed the roadway) within which a significant convergence or support deformation may occur. The paper presents the impact of low throw faults on the degree of convergence of roadways. Convergence is determined for two roadways in the hard coal mine. A special measuring stations have been installed in one of the roadways, and they have carried out constant measurements for 15 months. In the other roadway, the degree of convergence has been determined on the basis of an on-site verification and comparison of the measurements obtained and the initial values, based on the roadway’s records. On the basis of the obtained convergence results, the impact of a single fault and the entire fault zone on the roadway stability has been determined. The impact of a single, low throw fault results in a 30% higher vertical convergence than in the case of roadways free of geological disturbance. In the roadway section located in the fault zone, vertical convergence is 4 times higher than in the case of sections free of disturbance impact. The floor heaving constitutes ca. 90% of vertical convergence both for roadway sections situated within the faulted zones and for sections free of the influence of any additional factors.

The Influence of Disintegration of Hard Coal Varieties of Different Metamorphism Grade on the Amount of Sorbed Ethane / Wpływ rozdrobnienia odmian węgla kamiennego o różnym stopniu metamorfizmu na ilości sorbowanego etanu

2013 ◽  
Vol 58 (2) ◽  
pp. 449-463 ◽  
Author(s):  
Mieczysław Żyła ◽  
Agnieszka Dudzińska ◽  
Janusz Cygankiewicz
Keyword(s):  
Sorption Isotherms ◽  
Electron Donors ◽  
Hard Coal ◽  
Coal Surface ◽  
Compact Layer ◽  
Compact Structure ◽  
Small Surface ◽  
Mining Works ◽  
The Impact ◽  
Content Of Oxygen

Ethane constitutes an explosive gas. It most often accompanies methane realizing during exploitation and mining works. In this paper the results of ethane sorption have been discussed on three grain classes of six selected hard coal samples collected from active Polish coalmines. On the basis of obtained results, it has been stated that the tested hard coals prove differentiated sorption power with reference to ethane. Te extreme amount of ethane is sorbed by low carbonized hard coal from “Jaworzno” coalmine. This sort of coal shows great porosity, and great content of oxygen and moisture. The least amount of ethane is sorbed by hard coal from “Sośnica” coalmine. This sort of coal possesses relatively a great deal of ash contents. Together with the process of coal disintegration, the amount of sorbed ethane increases for all tested coal samples. Between tested coals there are three medium carbonized samples collected from “Pniówek”, “Chwałowice” “Zofiówka” coalmines which are characterized by small surface values counted according to model BET from nitrogen sorption isotherms determined at the temperature of 77.5 K. The samples of these three coals prove the highest, from between tested coals, increase of ethane sorption occurring together with their disintegration. These samples disintegrated to 0,063-0,075 mm grain class sorb ethane in the amount corresponding with the sorption quantity of low carbonized coal from “Jaworzno” coalmine in 0.5-0.7 mm grain class. It should be marked that the low carbonized samples collected from “Jaworzno” and Wesoła” coalmines possess large specific surface and great porosity and belong to coal group of “loose” spatial structure. Regarding profusion of sorbed ethane on disintegrated medium carbonized samples from “Pniówek”, “Zofiówka”, “Chwałowice” coalmines it can be supposed that in the process of coal disintegration, breaking their “compact’ structure occurs. Loosened structure of medium carbonized coals results in increasing accessibility of ethane particles to sorption centres both electron donors and electron acceptors which are present on hard coal surface. The surface sorption centre increase may result in formation a compact layer of ethane particles on coal surface. In the formed layer, not only the strengths of vertical binding of ethane particles with the coal surface appear but also the impact of horizontal strengths appears which forms a compact layer of sorbed ethane particles. The surface layer of ethane particles may lead to explosion.

Dissent and Education

2018 ◽  
Author(s):  
Mark Burden
Keyword(s):  
Eighteenth Century ◽  
Seventeenth Century ◽  
Educational Activity ◽  
Educational Institutions ◽  
Higher Educational Institutions ◽  
Legal Restrictions ◽  
Higher Educational ◽  
Set Up ◽  
The Impact ◽  
Dissenting Academies

Much eighteenth-century Dissenting educational activity was built on an older tradition of Puritan endeavour. In the middle of the seventeenth century, the godly had seen education as an important tool in spreading their ideas but, in the aftermath of the Restoration, had found themselves increasingly excluded from universities and schools. Consequently, Dissenters began to develop their own higher educational institutions (in the shape of Dissenting academies) and also began to set up their own schools. While the enforcement of some of the legal restrictions that made it difficult for Dissenting institutions diminished across the eighteenth century, the restrictions did not disappear entirely. While there has been considerable focus on Dissenting academies and their contribution to debates about doctrinal orthodoxy, the impact of Dissenting schools was also considerable.

Numerical study and field performance of rockbolt support schemes in TBM-excavated coal mine roadways: A case study

2021 ◽  
Vol 115 ◽  
pp. 104053
Author(s):  
Bin Tang ◽  
Mathias Yeboah ◽  
Hua Cheng ◽  
Yongzhi Tang ◽  
Zhishu Yao ◽  
...  
Keyword(s):  
Coal Mine ◽  
Numerical Study ◽  
Field Performance ◽  
Mine Roadways ◽  
Rockbolt Support

scholarly journals The Impact of the Coexistence of Methane Hazard and Rock-Bursts on the Safety of Works in Underground Hard Coal Mines

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 128
Author(s):  
Justyna Swolkień ◽  
Nikodem Szlązak
Keyword(s):  
Rock Burst ◽  
Methane Concentration ◽  
High Energy ◽  
Hard Coal ◽  
Coal Seams ◽  
Safety Level ◽  
Methane Drainage ◽  
Innovative Methods ◽  
Hard Coal Mining ◽  
The Impact

Several natural threats characterize hard coal mining in Poland. The coexistence of methane and rock-burst hazards lowers the safety level during exploration. The most dangerous are high-energy bumps, which might cause rock-burst. Additionally, created during exploitation, safety pillars, which protect openings, might be the reason for the formation of so-called gas traps. In this part, rock mass is usually not disturbed and methane in seams that form the safety pillars is not dangerous as long as they remain intact. Nevertheless, during a rock-burst, a sudden methane outflow can occur. Preventing the existing hazards increases mining costs, and employing inadequate measures threatens the employees’ lives and limbs. Using two longwalls as examples, the authors discuss the consequences of the two natural hazards’ coexistence. In the area of longwall H-4 in seam 409/4, a rock-burst caused a release of approximately 545,000 cubic meters of methane into the excavations, which tripled methane concentration compared to the values from the period preceding the burst. In the second longwall (IV in seam 703/1), a bump was followed by a rock-burst, which reduced the amount of air flowing through the excavation by 30 percent compared to the airflow before, and methane release rose by 60 percent. The analyses presented in this article justify that research is needed to create and implement innovative methods of methane drainage from coal seams to capture methane more effectively at the stage of mining.

scholarly journals Use of the AE Effect to Determine the Stresses State in AAC Masonry Walls under Compression

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3459
Author(s):  
Radosław Jasiński ◽  
Krzysztof Stebel ◽  
Paweł Kielan
Keyword(s):  
Ultrasonic Waves ◽  
Image Correlation ◽  
Masonry Walls ◽  
Acceptable Error ◽  
Compressive Stresses ◽  
Deformation State ◽  
Hydrostatic Stresses ◽  
Stress States ◽  
The Impact ◽  
Masonry Units

Safety and reliability of constructions operated are predicted using the known mechanical properties of materials and geometry of cross-sections, and also the known internal forces. The extensometry technique (electro-resistant tensometers, wire gauges, sensor systems) is a common method applied under laboratory conditions to determine the deformation state of a material. The construction sector rarely uses ultrasonic extensometry with the acoustoelastic (AE) method which is based on the relation between the direction of ultrasonic waves and the direction of normal stresses. It is generally used to identify stress states of machine or vehicles parts, mainly made of steel, characterized by high homogeneity and a lack of inherent internal defects. The AE effect was detected in autoclaved aerated concrete (AAC), which is usually used in masonry units. The acoustoelastic effect was used in the tests described to identify the complex stress state in masonry walls (masonry units) made of AAC. At first, the relationships were determined for mean hydrostatic stresses P and mean compressive stresses σ3 with relation to velocities of the longitudinal ultrasonic wave cp. These stresses were used to determine stresses σ3. The discrete approach was used which consists in analyzing single masonry units. Changes in velocity of longitudinal waves were identified at a test stand to control the stress states of an element tested by the digital image correlation (DIC) technique. The analyses involved density and the impact of moisture content of AAC. Then, the method was verified on nine walls subjected to axial compression and the model was validated with the FEM micromodel. It was demonstrated that mean compressive stresses σ3 and hydrostatic stresses, which were determined for the masonry using the method considered, could be determined even up to ca. 75% of failure stresses at the acceptable error level of 15%. Stresses σ1 parallel to bed joints were calculated using the known mean hydrostatic stresses and mean compressive stresses σ3.

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