scholarly journals Long High-Performance Sustainable Bolt Technology for the Deep Coal Roadway Roof: A Case Study

2020 ◽  
Vol 12 (4) ◽  
pp. 1375 ◽  
Author(s):  
Houqiang Yang ◽  
Changliang Han ◽  
Nong Zhang ◽  
Yuantian Sun ◽  
Dongjiang Pan ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Mine ◽  
High Performance ◽  
High Efficiency ◽  
Stability Control ◽  
Engineering Practice ◽  
Close Link ◽  
Coal Roadway ◽  
In Situ Investigation ◽  
Roof Stability

High-efficiency maintenance and control of the deep coal roadway roof stability is a reliable guarantee for safe production and sustainable development of a coal mine. With belt haulage roadway 3108 in MenKeqing coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to reveal the law of improving the bearing state of bolts by increasing the thickness of the roof anchoring layer. Also, the mechanism of the high-efficiency and long anchoring of the roof is revealed. Results show that increasing thickness of the roof anchorage layer could mobilize deep rock mass to participate in the bearing and promote the bolt to increase the resistance in a timely manner to limit the deformation of rock mass. Through the close link between shallow soft rock mass and deep stable rock mass, the deformation of the shallow rock mass is well controlled and so are the development and expansion of the roof separated fissures from shallow to deep. Long high-performance sustainable bolt technology for roof are proposed and carried out to control the stability of the deep roadway roof. Engineering practice indicates that deformations of roof could be efficiently controlled. The maximum deformations of the roof and sidewall-to-sidewall are 17 mm and 24 mm, respectively. No obvious separation fissures are found in the anchoring range of roof. This study provides a reference for roof stability control of deep roadway under similar conditions.

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

scholarly journals STUDY ON STABILITY CONTROL OF COAL MINE TUNNEL EXCAVATED IN WEAK ROCK MASS IN INDONESIA

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Phanthoudeth Pongpanya ◽  
Takashi Sasaoka2 ◽  
Hideki Shimada ◽  
Vongsavanh Soysouvanh
Keyword(s):  
Rock Mass ◽  
Numerical Simulations ◽  
Coal Mine ◽  
Support Systems ◽  
Stability Control ◽  
Weak Rock ◽  
Support Design ◽  
Floor Heave ◽  
Weak Rock Mass ◽  
The Stability

This paper focuses on the stability analysis and support design of the coal mine tunnel excavated in weak rock mass in an Indonesian underground coal mine through numerical simulations using the FLAC3D software. The PT Gerbang Daya Mandiri (GDM) coal mine situated in Indonesia was selected as a mine site in this study. According to the results of a series of numerical simulations, the stability of the mine tunnel decreases by increasing the depth and stress ratio. Ground control problems, for example falling roof, sidewall collapse, and floor heave are expected unless an appropriate support system is anticipated. Three support systems, including friction rockbolt, steel arch, and shotcrete are discussed as methods to stabilize the roof and sidewalls of the mine tunnel. From the simulated results, the steel arch is considered to be the most effective support method when compared with other support systems. The steel arch which is installed with closer space and larger crosssection delivers a better stability control to the roof and sidewalls of the mine tunnel. Although the stability of the roof and sidewalls of the mine tunnel can be maintained effectively by the steel arch support, the occurrence of floor heave is expected when the mining depth is increased. To control the floor stability of the mine tunnel, three techniques by applying cablebolt, invert-arch floor, and grooving method are therefore investigated and discussed. Based on simulated results, the heaving of the floor is well controlled after the cablebolt, invert-arch floor, and grooving methods are applied. Nevertheless, it is found that controlling the floor heave by cablebolt support could be the most suitable method comparing with other support systems in terms of the installation process, providing flat and safe working conditions of the floor, and economy. Additionally, the cablebolt with closer row space and longer length works more effectively to control the heaving problem of the floor. Keyword

Analysis of Displacement and Deformation Caused by Underground Mining in one Coal Mine of China

2013 ◽  
Vol 275-277 ◽  
pp. 375-378
Author(s):  
Xu Li Liang ◽  
Fang Hong Li
Keyword(s):  
Rock Mass ◽  
Coal Mine ◽  
Underground Mining ◽  
Engineering Practice ◽  
Hyperbolic Tangent ◽  
Function Model ◽  
Hyperbolic Tangent Function ◽  
Safe Production ◽  
Tangent Function ◽  
Mass Displacement

A hyperbolic tangent function model was used to make analysis for the rock mass displacement and deformation caused by underground mining, the model is verified correctness through real engineering practice. The cracking damage of the above buildings was analyzed using the model; the result could provide guidance for the underground mining and safe production.

High-Performance Hardware Interpolation Architecture for High Efficiency Video Coding Decoder

2016 ◽  
Vol 11 (9) ◽  
pp. 764
Author(s):  
Lella Aicha Ayadi ◽  
Nihel Neji ◽  
Hassen Loukil ◽  
Mouhamed Ali Ben Ayed ◽  
Nouri Masmoudi
Keyword(s):  
Video Coding ◽  
High Performance ◽  
High Efficiency ◽  
High Efficiency Video Coding

scholarly journals Investigation on the La Replacement and Little Additive Modification of High-Performance Permanent Magnetic Strontium-Ferrite

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1034
Author(s):  
Ching-Chien Huang ◽  
Chin-Chieh Mo ◽  
Guan-Ming Chen ◽  
Hsiao-Hsuan Hsu ◽  
Guo-Jiun Shu
Keyword(s):  
High Performance ◽  
Single Phase ◽  
Permanent Magnets ◽  
High Efficiency ◽  
Cobalt Content ◽  
Preparation Condition ◽  
Milling Process ◽  
Experimental Parameters ◽  
La Substitution ◽  
Hard Magnets

In this work, an experiment was carried out to investigate the preparation condition of anisotropic, Fe-deficient, M-type Sr ferrite with optimum magnetic and physical properties by changing experimental parameters, such as the La substitution amount and little additive modification during fine milling process. The compositions of the calcined ferrites were chosen according to the stoichiometry LaxSr1-xFe12-2xO19, where M-type single-phase calcined powder was synthesized with a composition of x = 0.30. The effect of CaCO3, SiO2, and Co3O4 inter-additives on the Sr ferrite was also discussed in order to obtain low-temperature sintered magnets. The magnetic properties of Br = 4608 Gauss, bHc = 3650 Oe, iHc = 3765 Oe, and (BH)max = 5.23 MGOe were obtained for Sr ferrite hard magnets with low cobalt content at 1.7 wt%, which will eventually be used as high-end permanent magnets for the high-efficiency motor application in automobiles with Br > 4600 ± 50 G and iHc > 3600 ± 50 Oe.

New hole transport styrene polymers bearing highly π-extended conjugated side-chain moieties for high-performance solution-processable thermally activated delayed fluorescence OLEDs

2021 ◽  
Vol 12 (11) ◽  
pp. 1692-1699
Author(s):  
Ji Hye Lee ◽  
Jinhyo Hwang ◽  
Chai Won Kim ◽  
Amit Kumar Harit ◽  
Han Young Woo ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Delayed Fluorescence ◽  
Hole Transport ◽  
Side Chain ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Turn On ◽  
Solution Processable

New polystyrene-based polymers with high π-extended hole transport pendants were synthesized to obtain a low turn-on voltage and high efficiency in solution-processed green TADF-OLEDs.

scholarly journals Directional Hydraulic Fracturing (DHF) of the Roof, as an Element of Rock Burst Prevention in the Light of Underground Observations and Numerical Modelling

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 562
Author(s):  
Marek Jendryś ◽  
Andrzej Hadam ◽  
Mateusz Ćwiękała
Keyword(s):  
Rock Mass ◽  
Hydraulic Fracturing ◽  
Coal Mining ◽  
Rock Burst ◽  
Coal Mine ◽  
Seismic Activity ◽  
Black Coal ◽  
Directional Hydraulic Fracturing ◽  
Before And After ◽  
The Face

The following article analyzes the effectiveness of directional hydraulic fracturing (DHF) as a method of rock burst prevention, used in black coal mining with a longwall system. In order to define changes in seismic activity due to DHF at the “Rydułtowy” Black Coal Mine (Upper Silesia, Poland), observations were made regarding the seismic activity of the rock mass during coal mining with a longwall system using roof layers collapse. The seismic activity was recorded in the area of the longwall itself, where, on a part of the runway, the rock mass was expanded before the face of the wall by interrupting the continuity of the rock layers using DHF. The following article presents measurements in the form of the number and the shock energy in the area of the observed longwall, which took place before and after the use of DHF. The second part of the article unveils the results of numerical modeling using the discrete element method, allowing to track the formation of goafs for the variant that does not take DHF into consideration, as well as with modeled fractures tracing DHF carried out in accordance with the technology used at “Rydułtowy” coal mine.

scholarly journals Neighborhood Energy Modeling and Monitoring: A Case Study

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3716
Author(s):  
Francesco Causone ◽  
Rossano Scoccia ◽  
Martina Pelle ◽  
Paola Colombo ◽  
Mario Motta ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Early Stage ◽  
Energy Performance ◽  
Monitoring Plan ◽  
Performance Targets ◽  
Carrier Energy ◽  
Zero Carbon ◽  
Energy Grid

Cities and nations worldwide are pledging to energy and carbon neutral objectives that imply a huge contribution from buildings. High-performance targets, either zero energy or zero carbon, are typically difficult to be reached by single buildings, but groups of properly-managed buildings might reach these ambitious goals. For this purpose we need tools and experiences to model, monitor, manage and optimize buildings and their neighborhood-level systems. The paper describes the activities pursued for the deployment of an advanced energy management system for a multi-carrier energy grid of an existing neighborhood in the area of Milan. The activities included: (i) development of a detailed monitoring plan, (ii) deployment of the monitoring plan, (iii) development of a virtual model of the neighborhood and simulation of the energy performance. Comparisons against early-stage energy monitoring data proved promising and the generation system showed high efficiency (EER equal to 5.84), to be further exploited.

scholarly journals Iodine reduction for reproducible and high-performance perovskite solar cells and modules

2021 ◽  
Vol 7 (10) ◽  
pp. eabe8130
Author(s):  
Shangshang Chen ◽  
Xun Xiao ◽  
Hangyu Gu ◽  
Jinsong Huang
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
High Efficiency ◽  
Electronic Materials ◽  
Substantial Reduction ◽  
Perovskite Solar Cells ◽  
High Yield ◽  
Operation Conditions ◽  
Record Value ◽  
Precursor Powders

Perovskite-based electronic materials and devices such as perovskite solar cells (PSCs) have notoriously bad reproducibility, which greatly impedes both fundamental understanding of their intrinsic properties and real-world applications. Here, we report that organic iodide perovskite precursors can be oxidized to I2 even for carefully sealed precursor powders or solutions, which markedly deteriorates the performance and reproducibility of PSCs. Adding benzylhydrazine hydrochloride (BHC) as a reductant into degraded precursor solutions can effectively reduce the detrimental I2 back to I−, accompanied by a substantial reduction of I3−-induced charge traps in the films. BHC residuals in perovskite films further stabilize the PSCs under operation conditions. BHC improves the stabilized efficiency of the blade-coated p-i-n structure PSCs to a record value of 23.2% (22.62 ± 0.40% certified by National Renewable Energy Laboratory), and the high-efficiency devices have a very high yield. A stabilized aperture efficiency of 18.2% is also achieved on a 35.8-cm2 mini-module.

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