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Experimental investigation on the movement mechanism of top coal in steeply inclined ultra-thick coal seams

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Acta Mechanica Sinica 2021年第4期37卷 631-648,I0003页

作者： jiachen wang Fei Liu Zhaohui wang School of Energy and Mining Engineering China University of Mining&TechnologyBeijing 100083China Coal Industry Engineering Research Center of Top-Coal Caving Mining Beijing 100083China

The pre-blasting zones have a significant influence on the coal broken and the recovery rate of the top coal caving *** paper explores the coal movement mechanism in the top coal with pre-blasting zones based on the geological parameters of Jiangcang No.1 mine in the western of *** steeply inclined ultra-thick coal seam was mined by using the sublevel top-coal caving mining *** geo-image process system(GIPS)software was used to track the mark points on the coal and *** support was used to record the load on the top of the support during the caving mining *** results show that the horizontal coal is moved to the shield window and the vertical coal is moved downward in the first level,while that in the second level shows consistency for the integrity of the *** vertical displacements of the corresponding points in the first level are lairger than that in the second ***,the load on the top of the support in the first level is smaller than that in the second *** indicated that the pre-blasting zones will give a more loosen top-coal and a small degree of difficulty in the top coal caving.

关键词： Sublevel Top coal caving Pre-blasting Physical modeling Movement mechanism

Application and Demonstration of a Series of Rare Earth Drought Resistant Materials in Western Area of China

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Journal of Rare Earths 2004年第Z1期22卷 317-319页

作者： wang Guoqiang wang jiachen Rare Earth Application Institute in High Technological Zone Yinchuan 750001 China Beijing General Research Institutes for Nonferrous Metals Beijing 100088 China

The application and effects for a series of rare earth (RE) drought resistant materials used in arid, salina,hungriness, wind defending and sand fixing matter, withdraw farming and return to grass and forest in western of China were *** important discussion was technological innovation within two years: such as seed clothing agent,RE liquid field film, RE grass and woods transplant living agent, and RE complex pesticide development and application.

关键词： agriculture innovation rare earths

Different compositions of TC4/TC11 functional gradient materials interface by wire arc additive manufacturing

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Science China Technological Sciences 2024年第12期67卷 3777-3782页

作者： wang jiachen wang He XU TianQiu LIU ChangMeng School of Infrastructure Engineering Nanchang University Beijng Aerospace FeiTeng Equipment Technology Co. Ltd. Department of Mechanical Engineering Politecnico di Milano School of Mechanical Engineering Beijing Institute of Technology

Titanium alloy is widely utilized in diverse industries due to its exceptional specific strength, making it a material with significant potential for advancement. Nevertheless, homogeneous materials are inadequate to meet the demands of various *** gradient materials(FGMs) have garnered increasing interest for their ability to tailor materials and structures. The continuous transition in FGMs often offers a more uniform and well-connected interface. However, there remains a lack of comprehensive research on the transition interface. In this study, TC4/TC11 double-alloy materials were produced using doublewire additive manufacturing. The wire feeding rates were adjusted to create materials with varying compositions. The grain morphologies, microstructures, and mechanical properties were examined. It was observed that as the TC11 content increased,the grain size decreased, the β content rose, the ultimate tensile strength improved, and the elongation decreased. Additionally,analysis of the fracture morphologies revealed that the dimples became smaller, indicating characteristics of ductile *** the solid solution aging heat treatment, it is observed that the α phase increases in size, and the mechanical properties are enhanced. These observations indicate that double-wire additive manufacturing can produce diverse interfaces. Furthermore,the heat treatment process has been shown to enhance the material properties, thus establishing an experimental foundation for FGMs.

关键词： additive manufacturing functional gradient materials titanium alloys transitional layers

Primary Results of New Rare Earth Materials for Hongti Grape

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Journal of Rare Earths 2004年第Z1期22卷 271-273页

作者： He Qiong Gu Jiangyuan wang jiachen Fruit Tree Working Station of Huocheng County Xinjiang 835200 China Agricultural Technological Extend Station of Huocheng County Xinjiang 835200 China Beijing General Research Institates for Nonferous MexalsBeijing 100088 China

New rare earth (RE) materials including RE phosphate as base fertilizer, bioactive RE micro-fertilizer and RE entire plant nutrition agent as topdressing fertilizer are treated on Hongti *** result showes that the plant leaves become thicker, the color is dark green, the plant disease index is lower, and the sugar content significantly increases.

关键词： Hongti grape sugar content rare earths

Characteristics and applications of gas desorption with excavation disturbances in coal mining

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International Journal of Coal Science & Technology 2015年第1期2卷 30-37页

作者： jiachen wang College of Resources and Safety Engineering China University of Mining & Technology (Beijing) Beijing 100083 China State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology (Beijing) Beijing 100083 China

According to the deficiency of experiment system for gas adsorption and desorption in coal mass, a large scale experiment system is developed independently by researchers. This experiment system is composed of primary and auxiliary boxes, power transmission system, mining system, loading system, gas charging system, data monitoring and intelligent acquisition system. The maximum experiment coal consumption is 1200 kg, the mining system is developed to conduct experiment for gas desorption under excavating disturbance, and the plane-charging cribriform ventilation device is developed to realize uniform ventilation for experiment coal sample, which is accord with the actual gas source situation of coal bed. The desorption characteristics of gas in coal are experimentally studied under the conditions of nature and mining using the experiment system. The results show that, compare with nature condition, the permeability of coal and the velocity of gas desorption could significantly increase under the influence of coal pressure relief and destruction caused by mining, and the degree of gas desorption could somewhat increase too. Finally, pressure relief gas extraction of current seam and adjacent seams after mining in a certain coal mine of Yangquan mining area are introduced, and the gas desorption experiment results is verified by analyzing the effect of gas extraction.

关键词： Gas adsorption and desorption experimental system Mining Gas desorption ~ Simultaneous extraction of coal and gas

Mixing and segregation of binary mixtures of biomass and silica sand in a fluidized bed

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Particuology 2021年第5期19卷 58-73页

作者： Tolu Emiola-Sadiq jiachen wang Lifeng Zhang Ajay Dalai Department of Chemical and Biological Engineering University of Saskatchewan.SaskatoonSK S7N 5A9Canada

In this work,mixing and segregation of binary mixtures involving biomass materials in a fluidized bed was experimentally investigated.A frozen bed method was employed to investigate both axial and radial distribution of biomass particles in silica *** different biomass materials were studied:willow sawdust,pelletized soy and oat hull *** loading investigated ranged from 5% to 30% by *** extent of mixing for each of the biomass composition was investigated using Lacey’s mixing index which is based on the standard deviations of the sample at different axial positions in the *** radial composition was also investigated by means of digital imaging analysis using a high-resolution digital *** experiments revealed the differences in the extent of particle distribution for pelletized biomass materials vs non-densified materials as a result of differences in particle size,density and importantly,the particle shape of the materials *** results showed an increase in the extent of mixing as the fluidizing velocity increased for both pellet materials while the mixing index for sawdust decreased beyond a loading of 20%.With an increase in biomass loading,an increase in mixing index was found for the two pellet materials.A similar trend was observed for sawdust at the lower loading ***,the mixing index started to decrease at higher loading level beyond 20%.The results greatly contributed to the understanding of the hydrodynamics of binary and multicomponent mixtures involving biomass materials,especially pelletized materials in fluidized beds.

关键词： Mixing Segregation Biomass Binary Fluidization Pellets

Status of Rare Earths for Agriculture in China

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Journal of Rare Earths 2004年第Z1期22卷 313-316页

作者： wang jiachen Yang Jun Liu Xiangsheng Beijing General Research Instiutes for Nonferrous Metals Beijing 100088 China National Rare Earth Center for Agriculture of China Beijing 100088 China Grirem Advanced Materials Co.Ltd. Beijing100088 China

Rare Earths (RE) for agriculture is a very typical application and has already brought good economic benefit to Chinese agriculture and *** this paper, the origin, development, status and the future of RE for agriculture in China were ***, through the researches of RE in the fields of physiological activity, physiological and biochemical mechanism, sanitation toxicology and environment security in 1980's, RE has been extended more widely in agriculture, such as crops, vegetables, forest, wood grass and stock breeding, such as cattle, fish and ***, with using of new techniques that were developed in the "State Ninth Five-Year Plan", the utilization area of RE was expanded to broad agricultural space, such as sunlight converting plastic film, RE fertilizer, RE drought resistant and RE water saving materials and new RE top dressing ***, with the development of the nanometer materials, the techniques and process of nanometer RE materials were *** these kinds of materials, the new seed cover matters, new seed mixed matter and new nanometer fertilizer will appear in the near future, and will produce many updated techniques and improve a new round RE application in agriculture.

关键词： agriculture typical application origin development status

Theoretical description of drawing body shape in an inclined seam with longwall top coal caving mining

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International Journal of Coal Science & Technology 2020年第1期7卷 182-195页

作者： jiachen wang Weijie Wei Jinwang Zhang School of Energy and Mining Engineering China University of Mining and Technology(Beijing)Beijing 100083China Coal Industry Engineering Research Center of Top-coal Caving Mining Beijing 100083China

Understanding the characteristics of drawing body shape is essential for optimization of drawing parameters in longwall top coal caving *** this study,both physical experiments and theoretical analysis are employed to investigate these characteristics and derive a theoretical equation for the drawing body shape along the working face in an inclined *** analyzing the initial positions of drawn marked particles,the characteristics of the drawing body shape for different seam dip angles are *** is shown that the drawing body of the top coal exhibits a shape-difference and volume-symmetry characteristic,on taking a vertical line through the center of support opening as the axis of symmetry,the shapes of the drawing body on the two sides of this axis are clearly different,but their volumes are *** establishing theoretical models of the drawing body in the initial drawing stage and the normal drawing stage,a theoretical equation for the drawing body in an inclined seam is proposed,which can accurately describe the characteristics of the drawing body *** shape characteristics and volume symmetry of the drawing body are further analyzed by comparing the results of theoretical calculations and numerical *** is shown that one side of the drawing body is divided into two parts by an inflection point,with the lower part being a variation development *** variation development area increases gradually with increasing seam dip angle,resulting in an asymmetry of the drawing body ***,the volume symmetry coefficient fluctuates around 1 for all values of the seam dip angle variation,and the volumes of the drawing body on the two sides are more or less equal as the variation development volume is more or less equal to the cut *** theoretical calculations and numerical simulations confirm that the drawing body of the top coal exhibits the shape-difference and volume-symmetry characteristic.

关键词： Longwall top coal caving mining Inclined seam Top coal Drawing body shape Equation for drawing body

Numerical investigation on the caving mechanism with different standard deviations of top coal block size in LTCC

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International Journal of Mining Science and Technology 2020年第5期30卷 583-591页

作者： jiachen wang Weijie Wei Jinwang Zhang Brijes Mishra Ang Li State Key Laboratory Coal Resources and Safe Mining China University of Mining and Technology-BeijingBeijing 100083China School of Energy and Mining Engineering China University of Mining and Technology-BeijingBeijing 100083China Coal Industry Engineering Research Center of Top-coal Caving Mining Beijing 100083China Department of Mining Engineering West Virginia UniversityMorgantownWV 26505USA

The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining *** standard deviation of top coal block size(dt)is one of the main parameters to reflect the size distribution of top *** find the effect of dt on the caving mechanism,this study simulates experiments with 9 different dt by using discrete element software *** dt is divided into two stages:uniform distribution stage(UDS)whose dt is less than 0.1(Schemes 1–5),and nonuniform distribution stage(NDS)whose dt is more than 0.1(Schemes 6–9).This research mainly investigates the variation of recovery ratio,drawing body shape,boundary of top coal,and contact force between particles in the two stages,*** results showed that with the increasing dt,the recovery ratio of the panel increases first and then decreases in *** is the largest in Scheme 3,which mainly increases the drawing volume at the side of starting drawing ***,the recovery ratio decreases first and then increases quickly in NDS,and it is the largest in Scheme 9,where the drawing volume at the side of finishing drawing end are relatively *** UDS,the major size of top coal is basically medium,while in NDS,the size varies from medium to small,and then to large,with a distinct difference in shape and volume of the drawing *** the major size of top coal is medium and small,the cross-section width of the initial boundary of top coal at each height is relatively ***,when the top coal size is large,the initial boundary of top coal has a larger opening range,the rotating angle of lower boundary is relatively small in the normal drawing stage,which is conducive to the development of drawing body and reduces the residual top coal,and the maximum particle velocity and the particles movement angle are both *** study lays a foundation for the prediction of recovery ratio,and sug

关键词： Longwall top coal caving mining Standard deviation of top coal size Recovery ratio Drawing body Boundary of top coal Contact force