In situ investigations into mining-induced overburden failures in close multiple-seam longwall mining: A case study

Ning, Jianguo,Wang, Jun,Tan, Yunliang,Zhang, Lisheng,Bu, Tengteng Techno-Press 2017 Geomechanics & engineering Vol.12 No.4

Preventing water seepage and inrush into mines where close multiple-seam longwall mining is practiced is a challenging issue in the coal-rich Ordos region, China. To better protect surface (or ground) water and safely extract coal from seams beneath an aquifer, it is necessary to determine the height of the mining-induced fractured zone in the overburden strata. In situ investigations were carried out in panels 20107 (seam No. $2-2^{upper}$) and 20307 (seam No. $2-2^{middle}$) in the Gaojialiang colliery, Shendong Coalfield, China. Longwall mining-induced strata movement and overburden failure were monitored in boreholes using digital panoramic imaging and a deep hole multi-position extensometer. Our results indicate that after mining of the 20107 working face, the overburden of the failure zone can be divided into seven rock groups. The first group lies above the immediate roof (12.9 m above the top of the coal seam), and falls into the gob after the mining. The strata of the second group to the fifth group form the fractured zone (12.9-102.04 m above the coal seam) and the continuous deformation zone extends from the fifth group to the ground surface. After mining Panel 20307, a gap forms between the fifth rock group and the continuous deformation zone, widening rapidly. Then, the lower portion of the continuous deformation zone cracks and collapses into the fractured zone, extending the height of the failure zone to 87.1 m. Based on field data, a statistical formula for predicting the maximum height of overburden failure induced by close multiple seam mining is presented.

Managing Quality-of-Control and Requirement-of-Bandwidth in Networked Control Systems via Fuzzy Bandwidth Scheduling

Zuxin Li,Yunliang Jiang,Wanliang Wang 제어·로봇·시스템학회 2009 International Journal of Control, Automation, and Vol.7 No.2

There is an unavoidable tradeoff between the control performance and the quality of service in networked control systems with resource constraints. To address the impact of network resources availability on requirement of bandwidth (RoB) and quality of control (QoC), an intelligent control ap-proach to dynamic bandwidth management, namely fuzzy bandwidth management, is proposed based on fuzzy logic control technique. In order to guarantee the system’s stability, the lower and upper bound of the assignable bandwidth are evaluated in terms of linear matrix inequalities and the resource constraints, respectively. In addition, the normalizable criterions of QoC and RoB are also defined, which can estimate the performance of the whole networked control systems. Preliminary simulations are carried out to highlight the merits of the proposed approach. It is argued that the proposed approach can save significant bandwidth and simultaneously improve overall control performance in comparison with the fixed bandwidth allocation and optimal bandwidth allocation.

Experimental Study of Factors Affecting the 7075 Aluminum Alloy Thin-walled Parts Milling Force

Fengyun Yu,Lin Wu,Yunliang Fu,Yanyan Guo,Can Zhao,Xufeng Wang 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.8

Taking 7075 aluminum alloy thin-walled part as the research object, with higher cutting parameters than the normal value selected, a four factors and four levels orthogonal experiment was carried out, in which we chose YG carbide cutting tools for the milling, intercepted the milling force stable section, selected ten peak values and took an average, conducted multiple linear regression analysis using Matlab numerical calculation software and established the milling force empirical formula of 7075 aluminum alloy thin-walled part to study the factors which have influence on its milling force. By range analysis of the experimental results, the cutting force change rule in the manufacturing process of aluminum alloy with the change of cutting parameter was revealed. It is found that the axial cutting depth had the greatest influence on the force perpendicular to the direction of cutting surface, and the radial cutting depth had the minimal impact. By comparative analysis on theoretical value and experimental value of milling forces, we found that the predicted value of the milling force Fx and Fy in theory were in good agreement with the experimental results with a relative error less than 8.7%. Under the experimental conditions, the optimal milling parameters are axial cutting depth of 2mm, radial cutting depth of 0.5mm, feed speed 95mm/min and cutting speed of 23.86m/min. It will provide data and experiment support for milling of thin-walled parts of similar materials, which will have important practical value and theoretical significance for engineering.

Molecularly Imprinted Polymers Modified by Deep Eutectic Solvents and Ionic Liquids with Two Templates for the Simultaneous Solid-Phase Extraction of Fucoidan and Laminarin from Marine Kelp

Li, Guizhen,Dai, Yunliang,Wang, Xiaoqin,Row, KyungHo Informa UK (TaylorFrancis) 2019 Analytical letters Vol.52 No.3

Experimental Research on the Influence of Tool Material and Geometric Parameters on Cutting Surface Quality of Super Alloy

Fengyun Yu,He Wang,Yunliang Fu 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.5

For nickel base superalloy GH4169 is investigated in the process of machining tool is easy to wear,cold-setting severe deformation, surface quality is difficult to guarantee and so on, using different carbide cutting tools and different tool geometry parameters, nickel-based superalloy GH4169 be turning experiments. The cutting tool material, cutting tool rake angle and corner radius of the influence law of super alloy surface roughness, different tool wear condition analysis. Results show that using K313, KC5510, SM1105 three kinds of cutting tool materials processing, the difference of obtained surface roughness is not big, but for the tool wear condition, the rake face and rear face wear of KC5510 is small. Integrated tool wear and workpiece machined surface quality, in the selection of the four tool materials, KC5510 is more suitable for processing GH4169; Single factor experiments found that with the gradual increase in rake angle and the corner radius, the surface roughness gradually decreases. Therefore, when GH4169 be turning, in order to reduce the surface roughness, grain refinement should be used, together with the PVD TiAlN coating carbide cutting tools, while a larger rake angle and corner radius are selected.

Research on Simulation and Experiment of Chip Shape for Machining High Temperature Alloy

Fengyun Yu,YuanTu,He Wang,Yunliang Fu 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.8

For superalloy GH4169poor processing, tool wear serious, affecting the surface quality of the workpiece and other issues, using the finite element software AdvantEdge to simulate the formation process of superalloy GH4169 chip in two-dimensional, and researching the characterization of serrated chip. Take the single factor experiment and conduct finite element simulation for superalloy GH4169 in changing the rake angle and tip arc radius of the situation. The simulation and the chip shape taking from experiments will be compared to prove the feasibility of the simulation. And find out changes of rake angle and tiparc radius; make clear the influence of degree of serrated chip. The results show: with the rake angle increases, serrated degree increases, and with tiparc radius increases, serrated degree increases. The study provides a reference for reasonable choice of optimized cutting tool geometric parameters.

Distributed Filtering for Markovian Jump Systems With Packet Loss Compensation

Zhidong Zhou,Yuyan Wu,Jun Cheng,Yunliang Wang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.7

In this article, the distributed-based filtering problem is studied for a type of Markov jump system subject to mode-dependent random packet losses. Packet dropout happens during the communication channel, which can be described via a random variable. In order to describe the nonhomogeneous Markov process, transition probabilities (TPs) on polytopic-structure-based are introduced. In view of packet loss, added by the single exponential smoothing (SES) technique, the packet loss compensation is provided to deal with the prediction value of the missing output. Besides, as for the physical limitations, it is quite difficult to ensure that all mode signals of the plant are available to filter. In the sequel, we establish a partially mode-dependent filter (PMDF). By using the Lyapunov theory, some sufficient conditions are obtained to guarantee the stochastically stable (SS) of the filtering error system (FES), and the filter parameters can be derived. Lastly, the validity of the presented results is tested through a numerical example.

Relationship of box counting of fractured rock mass with Hoek-Brown parameters using particle flow simulation

Ning, Jianguo,Liu, Xuesheng,Tan, Yunliang,Wang, Jun,Tian, Chenglin Techno-Press 2015 Geomechanics & engineering Vol.9 No.5

Influenced by various mining activities, fractures in rock masses have different densities, set numbers and lengths, which induce different mechanical properties and failure modes of rock masses. Therefore, precisely expressing the failure criterion of the fractured rock influenced by coal mining is significant for the support design, safety assessment and disaster prevention of underground mining engineering subjected to multiple mining activities. By adopting PFC2D particle flow simulation software, this study investigated the propagation and fractal evolution laws of the micro cracks occurring in two typical kinds of rocks under uniaxial compressive condition. Furthermore, it calculated compressive strengths of the rocks with different confining pressures and box-counting dimensions. Moreover, the quantitative relation between the box-counting dimension of the rocks and the empirical parameters m and s in Hoek-Brown strength criterion was established. Results showed that with the increase of the strain, the box-counting dimension of the rocks first increased slowly at the beginning and then exhibited an exponential increase approximately. In the case of small strains of same value, the box-counting dimensions of hard rocks were smaller than those of weak rocks, while the former increased rapidly and were larger than the latter under large strain. The results also presented that there was a negative correlation between the parameters m and s in Hoek-Brown strength criterion and the box-counting dimension of the rocks suffering from variable mining activities. In other words, as the box-counting dimensions increased, the parameters m and s decreased linearly, and their relationship could be described using first order polynomial function.