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Technical parameters of drawing and coal-gangue field movements of a fully mechanized large mining height top coal caving working face 被引量:7
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作者 LIU Chang-you HUANG Bing-xiang WU Feng-feng 《Mining Science and Technology》 EI CAS 2009年第5期549-555,共7页
Under fully mechanized, large mining height top coal caving conditions, the shield beam slope angle of the support increases due to the enlargement of the top coal breaking and caving space. This results in a change o... Under fully mechanized, large mining height top coal caving conditions, the shield beam slope angle of the support increases due to the enlargement of the top coal breaking and caving space. This results in a change of the caving window location and dimensions and, therefore, the granular coal-gangue movement and flows provide new characteristics during top coal caving. The main inferences we draw are as follows. Firstly, after shifting the supports, the caved top coal layer line and the coal gangue boundary line become steeper and are clearly larger than those under common mining heights. Secondly, during the top coal caving procedure, the speed of the coal-gangue flow increases and at the same drawing interval, the distance between the coal-gangue boundary line and the top beam end is reduced. Thirdly, affected by the drawing ratio, the slope angle of the shield beam and the dimensions of the caving window, it is easy to mix the gangue. A rational drawing interval will cause the coal-gangue boundary line to be slightly behind the down tail boom lower boundary. This rational drawing interval under conditions of large mining heights has been analyzed and determined. 展开更多
关键词 large mining height top coal caving coal-gangue movement field coal caving technical parameters coal caving window
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Variable-based Ramberg-Osgood constitutive model of power spinning bushing 被引量:8
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作者 赵俊生 顾元通 樊文欣 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第9期3080-3087,共8页
The influences of power spinning process parameters on the mechanical properties of spinning parts were analyzed with an SXD100/3-CNC numerical control power spinning machine.The unidirectional tensile tests were carr... The influences of power spinning process parameters on the mechanical properties of spinning parts were analyzed with an SXD100/3-CNC numerical control power spinning machine.The unidirectional tensile tests were carried out.Based on the experimental data,a ternary quadratic regression equation was established by orthogonal experiment.The Ramberg-Osgood constitutive model of tin-bronze connecting rod bushing was obtained.Referred to the constitutive relation of macroscopic incremental,the incremental elastoplastic constitutive relation of spinning parts was deduced based on the Mises yield criterion and kinematic hardening model.The results can be applied to the elastoplastic analysis in finite element numerical simulation. 展开更多
关键词 power spinning connecting rod bushing constitutive model technical parameter mechanical properties
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Classification of conditions for short-wall continuous mechanical mining in shallowly buried coal seam with thin bedrock 被引量:7
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作者 LIU Yu-de ZHANG Dong-sheng +2 位作者 MA Li-qiang ZHAO Yong-feng WANG Hong-sheng 《Journal of China University of Mining and Technology》 EI 2008年第3期389-394,共6页
The room and pillar method is usually used to extract coal from shallowly buried seams with thin bedrock. This results in a very low production efficiency and in a low degree of extraction. In recent years short-wall ... The room and pillar method is usually used to extract coal from shallowly buried seams with thin bedrock. This results in a very low production efficiency and in a low degree of extraction. In recent years short-wall continuous mechanical mining has been extensively used in many situations except shallowly buried coal seams with thin bedrock. The principles governing movement of the overlying strata above the 2-2 coal seam were deduced from in-situ experience, laboratory data, calculations and computer simulations. The thicknesses of the bedrock in the Shendong Coal Field where the coal is shallowly buried are classified into 5 types: <10 m, 10–15 m, 15–25 m, 25–35 m and >35 m, which was done using fuzzy clustering results. A series of reasonable, relative parameters in each category have been calculated and analyzed. One proposed way to perform short-wall continuous mechanical mining in shallowly buried coal seams is given. This is significant for coal mines with similar geological conditions. 展开更多
关键词 short-wall continuous mining thin bedrock fuzzy clustering technical parameter
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Effects of Mn on the properties of quenching and partitioning treated sheet steel 被引量:1
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作者 Ji Yunhang Wang Li Feng Weijun 《Baosteel Technical Research》 CAS 2008年第4期12-16,共5页
Since it has excellent tensile strength, the quenching and partitioning (Q & P) treated steel has been widely acclaimed. Some researched is currently being conducted on Q & P steel, but Q & P techniques and relat... Since it has excellent tensile strength, the quenching and partitioning (Q & P) treated steel has been widely acclaimed. Some researched is currently being conducted on Q & P steel, but Q & P techniques and related mechanisms have been mostly research based on conventional transformation-induced plasticity (TRIP) steel. This study researches the effect of Mn on the properties of Q &P sheet steel. Two kinds of steel sheet with different levels of Mn content (1.46% Mn and 2.75% Mn) are investigated. After being fully annealed, the steel sheets were quenched to a temperature between Ms and Mr. Allocation treatment then caused the carbon to be partitioned into the remaining austenite.The microstructure and tensile properties were analyzed. The results show that the increment of Mn content can increase the stability of the steel and decrease the sensitivity of the quenching temperature (QT). The results also indicate that increasing the level of Mn can effectively suppress the formation of bainite. 展开更多
关键词 Q P steel high strength retained austenite technical parameters
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Application of orthogonal design in the experiment of plasma arc powder surfacing technology
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作者 张德勤 杜则裕 云绍辉 《China Welding》 EI CAS 2001年第2期57-61,共5页
In this paper, the influence of plasma arc powder surfacing technical parameters on the property of layer is defined using the orthogonal design. By the orthogonal polynomial regression, when plasma arc powder surfaci... In this paper, the influence of plasma arc powder surfacing technical parameters on the property of layer is defined using the orthogonal design. By the orthogonal polynomial regression, when plasma arc powder surfacing is used on the surface of the X65 steel plate with the Fe-07 alloy powder, the optimum technical parameters are the following: I=180~190 A , G=41.5 g/min , v=102 mm/min , T_0=350 ℃ , Q_l=280 L/h , Q_s=400 L/h . Further, analysis of the cracking test data showed that the cracking preheat temperature is 350 ℃ . 展开更多
关键词 orthogonal design plasma arc powder surfacing orthogonal polynomial regression optimum technical parameters cracking test
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Innovative Design and Development of Simplysupported Tied Arch of Beijing-Shanghai HSR
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作者 WU Mengchang WEN Wangqing XU Sanping 《Chinese Railways》 2022年第2期60-68,共9页
Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply... Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure. 展开更多
关键词 Beijing-Shanghai HSR simply-supported tied arch tie beam arch rib SUSPENDER arch foot cross bracing key technical parameters
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Soil Wetting Patterns and Water Distribution as Affected by Irrigation for Uncropped Ridges and Furrows 被引量:1
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作者 ZHANG Yong-Yong ZHAO Xi-Ning WU Pu-Te 《Pedosphere》 SCIE CAS CSCD 2015年第3期468-477,共10页
The ridge-furrow tillage combined with furrow irrigation is being more widely applied and has been shown to be effective in the Loess Plateau of China. Accurate characterization of water infiltration behavior under ri... The ridge-furrow tillage combined with furrow irrigation is being more widely applied and has been shown to be effective in the Loess Plateau of China. Accurate characterization of water infiltration behavior under ridge-furrow irrigation could provide guidelines and criteria for future irrigation system design and operation. Our objective was to investigate soil water behavior during ponding infiltration in a cross-sectional ridge-furrow configuration. Soil water movement within three different soil textures was tested by tracking the spatial and temporal soil water content(SWC) variations in a soil chamber. The two-dimensional transient flow initially transferred rapidly, but gradually decreased with elapsed infiltration time, approaching a stable flow after 90 min. A technical parameter equation incorporating the Philip equation was developed using the water balance method to accurately predict total applied water volume(TAWV). The wetting patterns moved outward in an elliptical shape. The wetted lateral and downward distances fitted using equations accounted for capillary and gravitational driving forces in variably wetted soil media. Increasing initial SWC resulted in an increase in wetted soil volume, which can also be caused by decreasing bulk density in a homogeneous soil. Higher water level produced greater wetted lateral distance and more irrigation uniformity. The wetted lateral distance was almost identical to the wetted depth in silty clay loam soil; hence ridge-furrow irrigation should be implemented in such finer-textured soils. The wetted soil volume differed markedly among different soil textures(hydraulic properties), demonstrating that these properties can largely determine soil water spreading patterns and distribution. 展开更多
关键词 INFILTRATION ridge-furrow tillage soil texture soil water content technical parameter equation wetted soil volume
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