scholarly journals Optimization of Caving Technology in an Extrathick Seam with Longwall Top Coal Caving Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Liu Yang ◽  
Lianghui Li ◽  
Weijie Wei
Keyword(s):  
Body Shape ◽  
Dispersion Coefficient ◽  
Recovery Ratio ◽  
Coal Seams ◽  
Volume Changes ◽  
Positive Order ◽  
New Approach ◽  
Cluster Group ◽  
Single Opening ◽  
Longwall Top Coal Caving

The optimization of top coal caving technology is an efficient method to improve the recovery ratio in longwall top coal caving (LTCC). In extrathick coal seams, the conventional single-opening sequential caving technology (SOSCT) shows the following problems: low recovery ratio, high rock mixed ratio, and poor drawing balance. For these problems, this research verifies the applicability of multiopening caving technology (MOCT) in extrathick coal seams theoretically. However, different drawing sequences have a great effect on the drawing mechanism. Based on the progressive drawing sequence of cluster-group-support, this paper firstly proposes a systematic naming method for the top coal caving technology. Furthermore, an independent cluster-group caving technology (ICGCT) is given, meaning that all supports are divided into several clusters, a cluster is divided into several groups, and clusters extract top coal in positive order while groups are in reverse order in the drawing process. By establishing an experimental model by the discrete element method PFC2D, the drawing mechanism is investigated under different caving technologies. The results show that ICGCT significantly improves the recovery ratio of the panel and mainly increases the drawing volume of top coal in the middle and upper end of the panel. The shape of the top coal boundary reflects the drawing efficiency. Due to the effect of drawing sequence in ICGCT, the generation and disappearance processes of coal ridge greatly decrease the residual top coal in the middle of the panel. The drawing body shape has a direct influence on the recovery ratio. Multiple complete drawing bodies exist in ICGCT, and the dispersion coefficient of drawing volume changes periodically in the range of 0.5–1.7, which is conducive to the management of drawing processes. In addition, discussing ICGCT and the dependent cluster-group caving technology (DCGCT), it is found that the recovery ratio of DCGCT has a slight increase, which enlarges the maximum drawing range of top coal at both panel ends, shortening the total drawing time of the panel. In summary, ICGCT provides a new approach for improving the recovery ratio and drawing balance in LTCC with an extrathick coal seam.

Monitoring and modelling of gas dynamics in multi-level longwall top coal caving of ultra-thick coal seams, Part II: Numerical modelling

2015 ◽  
Vol 144-145 ◽  
pp. 58-70 ◽  
Author(s):  
Guangyao Si ◽  
Ji-Quan Shi ◽  
Sevket Durucan ◽  
Anna Korre ◽  
Jerneja Lazar ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Gas Dynamics ◽  
Coal Seams ◽  
Multi Level ◽  
Longwall Top Coal Caving

scholarly journals Metallic Glasses: A New Approach to the Understanding of the Defect Structure and Physical Properties

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 605 ◽  
Author(s):  
Vitaly Khonik ◽  
Nikolai Kobelev
Keyword(s):  
Shear Modulus ◽  
Physical Properties ◽  
Experimental Verification ◽  
Metallic Glasses ◽  
Structural Relaxation ◽  
Defect Structure ◽  
Relaxation Phenomena ◽  
Volume Changes ◽  
New Approach ◽  
Heat Effects

The work is devoted to a brief overview of the Interstitialcy Theory (IT) as applied to different relaxation phenomena occurring in metallic glasses upon structural relaxation and crystallization. The basic hypotheses of the IT and their experimental verification are shortly considered. The main focus is given on the interpretation of recent experiments on the heat effects, volume changes and their link with the shear modulus relaxation. The issues related to the development of the IT and its relationship with other models on defects in metallic glasses are discussed.

Experimental Drying of Ceramics Bricks Including Shrinkage

2015 ◽  
Vol 365 ◽  
pp. 106-111 ◽  
Author(s):  
J.J.S. Nascimento ◽  
F.A. Belo ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Body Shape ◽  
Initial Moisture Content ◽  
Experimental Tests ◽  
Clay Material ◽  
Drying Process ◽  
Volume Changes ◽  
Air Drying ◽  
Different Dimensions ◽  
Ball Clay ◽  
Red Ceramics

This work presents an experimental study on the behavior of clays during the drying process. Experimental tests were carried out with clay material for the production of red ceramics and white ceramic (ball clay). Different dimensions and the material initial moisture content plus temperature and relative air-drying humidity were taken into account. Drying kinetics and volume changes of parallelepiped-shaped samples were shown and analyzed. It has been verified that air-drying temperatures and body shape have an enormous influence on the drying rate process. The drying process occurs during the falling drying period and the volume changes display two linear periods.

FE Approach: Electro-Mechanical-Fluid Interaction of Jet Pipe Electrohydraulic Flow Control Servovalve

2003 ◽  
Author(s):  
Somashekhar S. Hiremath ◽  
M. Singaperumal ◽  
R. Krishna Kumar
Keyword(s):  
Steady State ◽  
Force Balance ◽  
Fe Model ◽  
Volume Changes ◽  
New Approach ◽  
Turbine Engine ◽  
Steady State Operation ◽  
Actual Flow ◽  
The Relationship ◽  
Fluid Interaction

Jet pipe electrohydraulic servovalve finds main application in feedback control system working on jet engine and fighter aircrafts. The analyzed jet pipe electrohydraulic servovalve is used in precise fuel control applications in gas turbine engine. This paper gives a new approach for servovalve modeling with the hydrostatic fluid elements in achieve steady state operation. The actual flow required to achieve the force balance is presented analytically. FE model gives the relationship between the spool and jet pipe position in achieving the steady state operation. The spool end cavity volume changes are presented.

Research of New Filling and Mining Technology Using Waste Rocks in Steep Coal Seams

2012 ◽  
Vol 204-208 ◽  
pp. 1395-1400
Author(s):  
Chuan Wei Zang ◽  
Chuan Le Ma ◽  
Xue An Zhuang
Keyword(s):  
Coal Mining ◽  
Coal Pillar ◽  
Recovery Ratio ◽  
Mining Method ◽  
Coal Seams ◽  
Coal Recovery ◽  
Waste Rocks ◽  
Filling Method ◽  
Gob Area ◽  
Coal Pillars

During the extraction of steeply inclined coal seams, the coal recovery ratio is low be-cause of the coal pillar loss and the production of waste rock is high due to lots of rock roadways which causes serious environmental pollution. This status is conflicted with the strategy of Clean Coal Mining and Green Coal Mining in China, so it is necessary to develop new coal mining method. In this paper, Downward Stratified Gangue Self-filling Method on the Flexible Shield (DSGSMFS) is put forward first. It means that the coal face is lain horizontally and advances along the dip; the flexible shield is used to separate the gob area; the waste rocks are self-filled downward to the top the shield; the coal is broken by drilling and blasting method under the shield, and the broken coal is transported by the electrical winch and the scraping mucker; the flexible shield moves downward automatically by the weight of itself and waste rocks. Field test shows that the strata displacement is effectively controlled by using DSGSMFS, so some coal pillars are recovered; as a result the problem of large quantity gangue and low coal recovery ratio in steep coal seam is solved. DSGSMFS is proved to be a new hopeful and effective coal green mining method.

Parametric modeling of historical mannequins

2019 ◽  
Vol 32 (3) ◽  
pp. 366-389
Author(s):  
Aleksei Moskvin ◽  
Mariia Moskvina ◽  
Victor Kuzmichev
Keyword(s):  
Nineteenth Century ◽  
Body Shape ◽  
Digital Technologies ◽  
High Accuracy ◽  
Parametric Modeling ◽  
Body Measurements ◽  
Sources Of Information ◽  
New Approach ◽  
Content Type ◽  
Digital Multimedia

Purpose Digital technologies are widely used for digitization of museum and archival heritage and creation of digital, multimedia and online exhibitions, especially in terms of costume history. Digital exhibitions require historical dress forms which were used in the past for costume presentation. The purpose of this paper is to develop a new method for parametric modeling of the nineteenth century dress forms in accordance with fashionable body shape. Design/methodology/approach Due to limited number of body measurements in historical sizing tables, it is impossible to redesign the morphology of old fashionable body with high accuracy by means of contemporary CAD. The developed method is based on two sources of information: first, historical sizing tables with body measurements; second, historical corsets. By combining both resources and applying virtual try-on technology, the full anthropometric database about the nineteenth century fashionable body shape has been organized and the parametric model of historical dress form has been generated. Findings The digital replica of deformable parametric dress form was created automatically in accordance with the historical sizing systems and the corsets construction. The process of reproduction of a historical dress form has been done with high accuracy due to substantial advantages of contemporary software. Originality/value This study shows new way of anthropometric data generating from the construction of close-fitting and compression undergarments. The developed method and the new database can be applied for each type of dress forms which were used in the second part of the nineteenth century to generate its digital replica in virtual reality. The new approach is joining the digital technologies and the professional knowledge as an important part of cultural heritage for studying, recreating and presenting historical costume.

scholarly journals Application of BigML in the Classification Evaluation of Top Coal Caving

2021 ◽  
Vol 2021 ◽  
pp. 1-28
Author(s):  
Meng Wang ◽  
Caiwang Tai ◽  
Qiaofeng Zhang ◽  
Zongwei Yang ◽  
Jiazheng Li ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Evaluation Model ◽  
Engineering Practice ◽  
Coal Seams ◽  
Mining Technology ◽  
Evaluation Result ◽  
Sample Data ◽  
Classification Evaluation ◽  
Longwall Top Coal Caving

Longwall top coal caving mining is one of the main methods of mining thick coal seams in China. Therefore, carrying out the classification evaluation of top coal caving is of great significance to ensure mining success and reduce the risk of mining technology. In order to realize the classification evaluation of top coal caving, this article introduces the method of using BigML to establish the classification evaluation model of top coal caving. Furthermore, using the data from the CNKI database as sample data, a classification evaluation model of top coal caving is established on BigML. After training, testing, and optimization, the model is used to evaluate the top coal caving in No. 3 coal seam of Gucheng Coal Mine, and the evaluation result is grade 1, which is consistent with the engineering practice. The final research results show that the application of BigML in the classification evaluation of top coal caving is successful; the evaluation of top coal caving through BigML is reliable; BigML provides another scientific reliability way for the classification evaluation of top coal caving.

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