Solid-gas coupling law during methane seepage from a coal mass in the advanced pressure relief area of a mining seam

2020 ◽  
Vol 23 (1) ◽  
pp. 106
Author(s):  
Wei Qin ◽  
Jialin Xu ◽  
Guozhong Hu
Keyword(s):  
Coal Mass ◽  
Pressure Relief ◽  
Methane Seepage ◽  
Relief Area

Research on Pressure Relief Technology of Main Transformer in 220KV Indoor Substation

2017 ◽  
Vol 873 ◽  
pp. 279-284
Author(s):  
Zheng Wei Guo ◽  
Xiang Li Liu ◽  
Xin Ju Guo ◽  
Cun Kai Liu ◽  
Chuan Jing ◽  
...  
Keyword(s):  
The State ◽  
Transformer Oil ◽  
Pressure Relief ◽  
Relief Area

Most indoor substations adopt oil-immersed transformers as voltage transformation device. In multiple disadvantage conditions, the flammable gases formed form transformer oil may explode in transformer room. Typical 220kV main transformer room of indoor substation was researched in this paper. An correlation of pressure relief area of the 220kV mail transformer room of indoor substation were presented based on the CFD tool FLACS modeling of the general designing schemes of the State Grid Corporation of China. This research may be used as reference of the pressure relief technology for main transformer rooms of indoor substations.

The Effect of Pressure Relief in Prosthetic Sockets on the Wear and Comfort of BK Amputees

2011 ◽  
Author(s):  
Gabi Nehme ◽  
Raymond Semaan ◽  
Ramzi Oueini
Keyword(s):  
Finite Element Analysis ◽  
Pressure Distribution ◽  
Design Of Experiment ◽  
Structural Integrity ◽  
Great Flexibility ◽  
Pressure Relief ◽  
Element Analysis ◽  
Relief Area ◽  
Design Scenario ◽  
Better Than

Great flexibility in prosthetic sockets, with long range of spring like action is needed while designing a socket. A finite element analysis is conducted to investigate the stress and displacement distribution for different socket cases where relief is needed. The relieved socket after optimization of the pressure distribution areas showed less wear and more comfort for amputees than the non-relieved socket. A Design of Experiment using 2 level factorial design is used to optimize the relief areas with respect to pressure distribution. Stresses and displacements were included in the model desirability. Higher deformation of the pressure relief areas is sought while preserving the socket structural integrity. A compromise with the structural integrity of the socket and the optimized values with high desirability of the Design of Experiment Model imply that Duraform socket A with 1.69mm relief area could be the best design scenario between several cases. Wear and skin analysis indicated that the relieved socket is significantly better than the unrelieved one.

scholarly journals RECOGNITION FOR THE BOUNDARY OF PRESSURE-TOLERANT AND PRESSURE-RELIEF AREAS ON THE SCANNED POINTS OF RESIDUAL LIMB

2001 ◽  
Vol 13 (06) ◽  
pp. 276-282 ◽  
Author(s):  
LAI-HSING HSU ◽  
HON-WING AU ◽  
YOU-LI CHOU ◽  
GWO-FENG HUANG
Keyword(s):  
Computer Aided Design ◽  
Geometric Model ◽  
Recognition Algorithm ◽  
Residual Limb ◽  
Pressure Relief ◽  
Characteristic Distance ◽  
Cad System ◽  
Pressure Tolerance ◽  
Aided Design ◽  
Relief Area

An algorithm is proposed to recognize the pressure-relief area and pressure-tolerance area on the CAD (computer aided design)model of a residual limb that needs to be modified for the use of making socket. The recognition algorithm includes the basic techniques of image processing, geometric model transformation, and the characteristic distance between two adjacent scanned points. The results of the boundary points are transferred to a CAD system that is employed to modify the shape of the residual limb within these two types of areas according to the prosthetist requirements. The modified CAD model is then used to produce a better-fit socket.

scholarly journals Research on Optimization of Coal Pressure Relief Borehole Parameters under High-Stress Conditions

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Heng Zhang ◽  
Tie Li ◽  
Zhenhua Ouyang ◽  
Su Liu ◽  
Haiyang Yi
Keyword(s):  
Stress Concentration ◽  
Energy Density ◽  
Elastic Energy ◽  
Large Diameter ◽  
High Stress ◽  
Stress Conditions ◽  
Plastic Behavior ◽  
Coal Seams ◽  
Pressure Relief ◽  
Relief Area

Determining the parameters of boreholes drilled for relieving pressure in coal seams is the key preventing and controlling rock bursts in boreholes of large diameter. In this study, theoretical analysis, numerical simulation, literature research, and other analysis methods are applied to study the angles of elastic energy dissipation and stress transfer, the distribution law of the pressure relief area, and the areas of stress concentration, energy, stress, displacement, and plastic behavior of large-diameter pressure relief boreholes in coal seams under high-stress conditions. The results are then used to evaluate the relationship between large-diameter pressure relief boreholes and the borehole arrangement. The following results are obtained. (1) A large-diameter results in a large amount of elastic energy released by the surrounding coal, low residual elastic energy density, strong interaction between boreholes, large pressure relief range of the borehole, and high pressure relief efficiency. (2) The main evaluation factor of the borehole pressure relief effect is its thickness and stress concentration area; secondary evaluation is based on the areas of energy, displacement, stress, and plastic behavior. (3) Six evaluation index systems are established to evaluate the effects of borehole pressure relief, which are found to be the thicknesses of the borehole pressure relief area and stress concentration area, reduction degree of energy density, percentage of stress reduction, displacement, and penetration degree of the plastic area. (4) It is determined that when the diameters of the pressure relief boreholes are 100, 120, 180, and 200 mm, a single-row borehole arrangement is adopted; a three-pattern borehole arrangement is adopted with diameters of 140 and 160 mm. These research results can provide theoretical support in selecting reasonable borehole arrangements for pressure relief boreholes of different diameters.

scholarly journals Characterizing the Permeability and Methane Release with the Treatment of Pressure-relief Mining: Intensive Field Measurements

2020 ◽  
Author(s):  
Cun Zhang ◽  
Qingsheng Bai ◽  
Ziyu Song ◽  
Yang Luo ◽  
Jianhang Chen
Keyword(s):  
Theoretical Analysis ◽  
Coal Seam ◽  
Permeability Coefficient ◽  
Field Measurements ◽  
Gas Pressure ◽  
Pressure Relief ◽  
Methane Release ◽  
Longwall Panel ◽  
Relief Area ◽  
Pressure Evolution

Abstract Characterizing the permeability evolution and methane release is of great significance for the safe mining of the high gas outburst seams, as well as coal and gas simultaneous extraction. Theoretical analysis, laboratory testing, and numerical simulation are widely used methods to characterize the permeability and methane release with the treatment of pressure-relief mining. However, these methods cannot fully reflect the complexity of filed practice. In this study, we report the effectiveness of protective coal seam (PCS) mining and the pressure-relief area in the protected coal seam (PDCS) based on detailed and integrated field measurements in a Chinese coal mine. To the best of our knowledge, it is the first time to measure the permeability coefficient and gas pressure evolution in the PDCS during the PCS longwall mining. The evolution of the permeability coefficient in the pressure-relief area during PCS mining can be divided into four stages: slowly decreasing, sharply increasing, gradually decreasing, and basically stable. The maximum permeability coefficient is 322 times of the initial value and finally stabilized at 100 times after the goaf compacted. The gas pressure evolution in the PDCS indicates that the strike pressure relief angle is 52.2° at the active longwall face zone, and 59.3° at the installation roadway side. The tendency pressure relief angles at the lower and upper sides of the longwall panel are 75° and 78.9°, respectively. The residual gas content and gas pressure of the PDCS in the pressure-relief area are reduced to less than 6 m3/t and within 0.4 MPa, respectively. The field measurements show that pressure-relief mining can prevent coal and gas outbursts in PDCSs. The field observations in this paper can serve as benchmark evidence for theoretical analysis and numerical simulations, and also provide insights into realizing safety mining in similar conditions.

On the assessment of ventricular reconfiguration after intracranial pressure relief. What information is encoded in size and form?

2004 ◽  
Vol 31 (S 1) ◽  
Author(s):  
C Preul ◽  
M Tittgemeyer ◽  
D Lindner ◽  
C Trantakis ◽  
J Meixensberger ◽  
...  
Keyword(s):  
Intracranial Pressure ◽  
Pressure Relief

Revisão sistemática sobre os posicionamentos de tilt e recline para usuários de cadeira de rodas

2018 ◽  
Vol 19 (3) ◽  
pp. 417
Author(s):  
Luma Carolina Gradim ◽  
Paulo Vinícius Braga Mendes ◽  
Debora Caires Paulisso ◽  
Daniel Marinho Cezar Da Cruz
Keyword(s):  
Web Of Science ◽  
Pressure Relief

Introdução: O uso prolongado de cadeira de rodas pode acarretar em lesões por pressão, dores e perda de independência funcional. O método de inclinação e/ou de reclinar (tilt/recline) é prescrito para neutralizar e minimizar esses efeitos nocivos. Porém, não há um consenso de qual ângulo destes recursos é o ideal, bem como a eficiência destes para os usuários. Objetivos: a) conhecer e verificar quais angulações dos sistemas de posicionamento de tilt e recline são mais utilizadas e favoráveis para os usuários de cadeira de rodas e; b) classificar pesquisas encontradas pelo seu nível de evidência. Métodos: Trata-se de uma revisão sistemática sem meta-análise. Foram recuperados artigos publicados até setembro de 2017, na Biblioteca Virtual em Saúde-BVS, Pubmed, Scopus, Web of Science e OTseeker, utilizando as palavras-chave: “wheelchair”, “tilt-in-space”, “tilt-recline”, “recline”, “pressure relief” e “repositioning systems”. Resultados: A maioria dos artigos selecionados correspondeu ao nível IV de evidência, que se caracteriza como estudos não experimentais. Os principais resultados apontam que a combinação de tilt e recline favorece o alívio de pressão na região das nádegas dos usuários de cadeira de rodas e promove conforto postural, mas para existir eficácia, há a necessidade de maiores angulações. Identificou-se que os menores ângulos são os mais realizados pelos usuários de cadeira de rodas, com a finalidade de gerar conforto e alívio de pressão. Conclusão: A prescrição e utilização dos sistemas de posicionamentos variáveis favorecem o usuário de cadeira de rodas, sendo os efeitos proporcionalmente relacionados ao grau de angulação adotado.Palavras-chave: úlcera por pressão, reabilitação, traumatismos da medula espinal, cadeiras de rodas.

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