scholarly journals Searching for the Optimal Parameters of the Thick Steep Seams‘ Under-Level Development

2018 ◽  
Vol 41 ◽  
pp. 01002
Author(s):  
Svetlana Kostyuk ◽  
Nikolay Bedarev ◽  
Oleg Lyubimov ◽  
Nikolay Kovalyov
Keyword(s):  
Tensile Strength ◽  
Bulk Density ◽  
Optimal Parameters ◽  
Coal Seams ◽  
Technical Result ◽  
Immediate Roof ◽  
Working Out ◽  
Excavation Site ◽  
Coal Region

At the present time the problem to search for variants for the development of steep thick coal seams is highly interest. Here there are, for example, variants for managing the workings’ roof by caving or laying the worked out space. The authors proposed a number of methods for it, which are protected by patents. The permissible span of the roof exposure is estimated as a function of the type of the immediate roof of the mine, its thickness, bulk density and tensile strength, and the height of the underlevel is also determined. The technical result is provided by the presence of the protective inter-horizon strips and inter-sectional pillars, by the order of working out the excavation site and by the value of the step of the binding of the worked out space. The above solutions are acceptable for the Prokopyevsk-Kiselevsk coal region in Kuzbass.

scholarly journals Criteria for the difficulty of working out coal-bearing zones of quarry fields

2019 ◽  
Vol 134 ◽  
pp. 01018
Author(s):  
Alexei Selyukov ◽  
Nuray Demirel
Keyword(s):  
Complex Structure ◽  
Uneven Distribution ◽  
Open Pit ◽  
Coal Seams ◽  
Mining Methods ◽  
Coal Reserves ◽  
Working Out

Coal-bearing zones of open pit fields are represented by formations of coal seams from inclined to steep bedding with unstable thickness, both in dip and strike with different dip angles even within the same strata, with varying rock inter-layers and strength. In addition, most coal seams have a complex structure, including rock layers inside. In most cases, there is an uneven distribution of coal seams, and, consequently, coal reserves over the area of quarry fields. In this regard, for the analysis of quarry fields, there is a need to select criteria for assessing the complexity of coal-bearing zones for the purpose of systematizing them and choosing directions for constructing technological schemes for excavation and loading operations and mining methods.

Tests of Selected Properties of Aggregates on Ceramic Wastes

2016 ◽  
Vol 677 ◽  
pp. 246-253
Author(s):  
Artur Koper
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Physical Properties ◽  
Bulk Density ◽  
Water Cycle ◽  
Free Water ◽  
Coarse Aggregates ◽  
Sanitary Ceramic ◽  
Mechanical And Physical Properties ◽  
Ceramic Sintering

The article analysed the results of comparative sampling of selected properties of concretes with addition of aggregates from sanitary ceramic wastes. For the need of the analyses there were created concretes of various w/c coefficients (0,35, 0,50, 0,75) and with diverse percentage participation of ceramic wastes aggregates (exchange of 50% and 100% coarse aggregates into ceramic). The range of performed samples and analyses included sampling of mechanical and physical properties of concretes and the aggregates used. What was under analysis: for aggregates – sampling of bulk density, absorbency, resistance to crushing; for concretes from ceramic wastes – sampling of density, absorbency, compressive strength, tensile strength and compressive strength after roasting. Roasting was performed according to defined temperature cycles: cycle I - from 0 to 150OC (vaporisation of free water), cycle II - from 150 to 550OC (separation of chemically combined water), cycle III - beyond 550OC (change of hydraulic combination into ceramic, sintering).

scholarly journals Combined Response Surface Method and Modified Differential Evolution for Parameter Optimization of Friction Stir Welding

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1080
Author(s):  
Thanatkij Srichok ◽  
Rapeepan Pitakaso ◽  
Kanchana Sethanan ◽  
Worapot Sirirak ◽  
Parama Kwangmuang
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Ultimate Tensile Strength ◽  
Differential Evolution ◽  
Welding Speed ◽  
Tool Material ◽  
Optimal Parameters ◽  
Friction Stir ◽  
Surface Method ◽  
Tool Pin

In this study, we constructed a new algorithm to determine the optimal parameters for friction stir welding including rotational speed, welding speed, axial force, tool pin profile, and tool material. The objective of welding is to maximize the ultimate tensile strength of the welded aluminum. The proposed method combines the response surface method and the modified differential evolution algorithm (RSM-MDE). RSM-MDE is a method that involves both experimental and simulation procedures. It is composed of four steps: (1) finding the number of parameters and their levels that affect the efficiency of the friction stir welding, (2) using RSM to formulate the regression model, (3) using the MDE algorithm to find the optimal parameter of the regression model obtained from (2), and (4) verifying the results obtained from step (3). The optimal parameters generated by the RSM-MDE method were a rotation speed of 1417.68 rpm, a welding speed of 60.21 mm/min, an axial force of 8.44 kN, a hexagon-tapered tool pin profile, and the SKD 11 tool material. The ultimate tensile strength obtained from this set of parameters was 294.84 MPa, which was better than that of the RSM by 1.48%.

scholarly journals Sintering and mechanical properties of porcelains prepared from algerian raw materials

Cerâmica ◽  
2011 ◽  
Vol 57 (344) ◽  
pp. 453-460 ◽  
Author(s):  
S. Kitouni ◽  
A. Harabi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Bulk Density ◽  
Phase Diagrams ◽  
Heating Rate ◽  
Ternary Phase ◽  
Raw Materials ◽  
Micro Hardness ◽  
Ternary Phase Diagrams

Porcelain is a type of ceramics highly valued for its beauty and strength. The overall goal of this work is to utilize local raw materials within the following fractions: 37 wt.% kaolin, 35 wt.% feldspar and 28 wt.% quartz. This composition has been selected on the basis of the ternary phase diagrams (kaolin-feldspar-quartz). The densification behaviour indicated that specimens sintered at 1200 °C for 2 h with a heating rate of 5 °C/min, have a bulk density of about 2.50 g/cm³. This value is slightly higher than that reported for the conventional porcelain products (2.45 g/cm³). Porcelain specimens with and without calcination sintered at 1200 °C for 2 h have tensile strength values of about 45 and 73 MPa, respectively (equivalent flexural strength values of about 122 and 197 MPa, respectively). The flexural strength values of both specimens are much higher than those reported for conventional porcelains (ranged between 60 and 80 MPa). Furthermore, the value of micro-hardness of the fired samples without calcination at 1200 °C is 9.3 ± 0.2 GPa which is higher than the commercial porcelain products (5.5 GPa).

scholarly journals Optimization of Copper Electroforming Process Parameters Based on Double Hidden Layer BP Neural Network

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1157
Author(s):  
Feng Ji ◽  
Chao Chen ◽  
Yongfei Zhao ◽  
Byungwon Min
Keyword(s):  
Neural Network ◽  
Tensile Strength ◽  
Back Propagation ◽  
Pulse Frequency ◽  
Back Propagation Neural Network ◽  
Copper Layer ◽  
Process Conditions ◽  
Optimal Parameters ◽  
Hidden Layer ◽  
Experimental Values

In order to optimize the pulse electroforming copper process, a double hidden layer BP (back propagation) neural network was constructed. Through sample training, the mapping relationship between electroforming copper process conditions and target properties was accurately established, and the prediction of microhardness and tensile strength of the electroforming layer in the pulse electroforming copper process was realized. The predicted results were verified by electrodeposition copper test in copper pyrophosphate solution system with pulse power supply. The results show that the microhardness and tensile strength of copper layer predicted by “3-4-3-2” structure double hidden layer neural network are very close to the experimental values, and the relative error is less than 2.82%. In the parameter range, the microhardness of copper layer is between 100.3~205.6 MPa and the tensile strength is between 165~485 MPa. When the microhardness and tensile strength are optimal, the corresponding range of optimal parameters are as follows: current density is 2–3 A·dm−2, pulse frequency is 1.5–2 kHz and pulse duty cycle is 10–20%.

scholarly journals DETERMINATION OF THE RATIONAL LENGTH OF THE BLOCK ALONG THE STRIKE FOR EXPANSION TO PROVIDE SAFETY AND EFFICIENCY IN THE WORKING OF THE MEDIUM THICK IN-CLINED COAL SEAMS WITH THE ROOM AND PILLAR SYSTEM IN THE QUANG NINH COAL BASIN

2018 ◽  
pp. 3-8
Author(s):  
Duc Thang Pham ◽  
Victor G. Vitcalov
Keyword(s):  
Coal Seams ◽  
Coal Basin ◽  
Foreign Experience ◽  
Geological Conditions ◽  
Rational Length ◽  
Working Out ◽  
Quang Ninh ◽  
Excavation Area

An analysis of the constraints that apply the technology and the complexities of the mining and geological conditions of the Quang Ninh coal basin. The possi-bility and expediency of using the foreign experience of working out of the me-dium thick inclined coal seams in the mines of Vietnam. The scheme of prepara-tion and working out of the excavation area is given in view of the technological features in difficult mining and geological conditions, using the room and pillar system and determination of the rational length of the block along the strike.

scholarly journals Characterization of Recycled Polyethylene Terephthalate Powder for 3D Printing Feedstock

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Chukwunonso N Nwogu ◽  
Remy Uche ◽  
John O Igbokwe ◽  
Chukwunenye A Okoronkwo
Keyword(s):  
Tensile Strength ◽  
3D Printing ◽  
Flexural Strength ◽  
Bulk Density ◽  
Intrinsic Viscosity ◽  
Coefficient Of Friction ◽  
Flow Property ◽  
Grade One ◽  
Density Coefficient

This paper assessed the suitability of PET powder produced by crushing used plastic bottles as 3D printing feedstock. Characterization of the powder was done through determining its flow property, coefficient of friction, bulk density, flexural and tensile strengths and compared with those of ABS, PLA, PVA, Nylon and HDPE which are used conventionally 3D printing of plastic parts. Two grades of PET bottles were used in this study: grade one which is designated PET1 with intrinsic viscosity values ranging from 0.78-0.80 (used for water bottles) and grade two which is designated PET2 with intrinsic viscosity values ranging from 0.80-0.85 (used for carbonated drinks bottles). The results of the tests performed showed that PET1 has bulk density, coefficient of friction, flexural strength and tensile strength values of 0.16 g/m3, 0.43, 82.1 MPa and 63.4 MPa respectively while PET2 has bulk density, coefficient of friction, flexural strength and tensile strength values of 0.15 g/m3, 0.22, 82.7 MPa and 57.8 MPa respectively. The Experimental results show that both PET1 and PET2 have very good flow property, and are suitable for 3D printing. This study solves two major problems: plastic waste management and availability of locally produced 3D printing feedstock, which is currently the greatest challenge of 3D printing in Nigeria. Keywords— 3D printing feedstock, Characterization, Intrinsic viscosity, PET powder.

Sign in / Sign up

Export Citation Format

Share Document