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Subsidence control method by inversely-inclined slicing and upward mining for ultra-thick steep seams

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International Journal of Mining science and Technology 2022年第1期32卷 103-112页

作者： Huayang Dai Peng Li Nurpeissova Marzhan Yueguan Yan Chongliang Yuan Tursbekov Serik Junting Guo Yryszhan Zhakypbek Konbay Seituly School of Geosciences and Surveying Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Coal Resource and Safe Mining China University of Mining and Technology-BeijingBeijing 100083China Satbayev University Almaty 050013Kazakhstan Yaojie Coal and Power Group Company Ltd Lanzhou 730080China Al-Farabi Kazakh national University Almaty 050040Kazakhstan China Energy Investment Corporation Beijing 100000China

Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this *** this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining *** application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.

关键词： Ultra-thick steep coal seam Horizontal slicing Subsidence control method Inversely-inclined slicing and upward mining Application study

Effects of Warm Deformation on Mechanical Properties of TRIP Aided Fe-C-Mn-Si Multiphase Steel

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Journal of Iron and Steel Research International 2012年第6期19卷 47-52页

作者： TIAN Yong LI Zhuan~ State Key Laboratory of Roiling and Automation Northeastern University Shenyang 110004 LiaoningChina Department o{ Material Engineering Shenyang Institute of Aeronautical Engineering Shenyang110034 Liaoning China）

Warm deformation tests were performed using a kind of tubby heater. The microstructures and mechanical properties of an Fe-C-Mn-Si multiphase steel resulting from different warm deformation temperatures were investiga- ted by using LOM （light optical microscopy）, SEM and XRD. The results indicated that the microstructure contai- ning polygonal ferrite, granular bainite and a significant amount of the stable retained austenite can be obtained through hot deformation and subsequent austempering. Warm deformation temperature affects the mechanical prop- erties of the hot rolled TRIP steels. Ultimate tensile strength balance reached maximum （881 MPa） when the speci- men was deformed at 250 ~C, and the total elongation and strength-ductility reached maximum （38% and 28 614 MPa ~ ~, respectively） at deforming temperature of 100 ~C. Martensite could nucleate when austenite was deformed above M~, because mechanical driving force compensates the decrease of chemical driving force. The TRIP effect occurs in the Fe-C-Mn-Si multiphase steel at deforming temperature ranging from 15 to 350 ~C. The results of the effects of warm deformation on the mechanical properties of the Fe-C-Mn-Si multiphase steel can provide theoretical basis for the ap- plications and the warm working of the hot rolled TRIP sheet steels in industrial manufacturing.

关键词： warm deformation Fe-C-Mn-Si multiphase steel TRIP effect mechanical property

Direct Numerical Simulation of the Pulsed Arc Discharge in Supersonic Compression Ramp Flow

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Journal of Thermal science 2020年第6期29卷 1581-1593页

作者： SONG Guoxing LI Jun TANG Mengxiao Aeronautics Engineering College Air Force Engineering UniversityXi’an 710038China

Direct numerical simulation(DNS)of shock wave/turbulent boundary layer interaction(SWTBLI)with pulsed arc discharge is carried out in this *** subject in the study is a Ma=2.9 compression flow over a 24-degree *** numerical approaches were validated by the experimental results in the same flow *** heat source model was added to the Navier-Stokes equation to serve as the energy deposition of the pulsed arc *** streamwise locations are selected to apply energy *** effect of the pulsed arc discharge on the ramp-induced flow separation has been studied in *** DNS results demonstrate the incentive locations play a dominant role in suppressing the separated *** show that pulsed heating is characterized by a thermal blockage,which leads to streamwise *** incentive locations upstream the interaction zone of the base flow have a better control *** separation bubble shape shows as"spikes",and the downstream flow of the heated region is accelerated due to the momentum exchange between the upper boundary layer and the bottom boundary *** high-speed upper fluid is transferred to the bottom,and thus enhances its ability to resist the flow *** stripe vortex structures are also generated at the edge of the ***,the turbulent kinetic disturbance energy is increased in the flow *** disturbances that originate from the pulsed heating are capable of increasing the turbulent intensity and then diminishing the trend of flow separation.

关键词： direct numerical simulation pulsed arc discharge shock waves turbulent boundary layer flow separation

Hazard Control of NO_x in Hot Stove

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Journal of Iron and Steel Research International 2014年第3期21卷 306-311页

作者： Chuan CHEN Shu-sen CHENG Xi-bin GUO School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Xuanhua Iron and Steel Group Co. Ltd.

Hazard control of NOx is very important for the long life of hot stove shell and environmental protection. NOx concentrations during different operation periods of hot stove were calculated according to thermodynamical and dynamical analyses. The results were verified by the previously measured data. Then, the influence of hot stove oper- ation parameters on NOx concentration and the mechanism of liquid water formation in hot stove were studied. The results indicated that in gas period, the dome temperature should be controlled below 1420 ℃ in order to decrease NO~ emission. In the case of banking operation, NOx concentration was about 40--60 times higher than that in gas period. Hence, reasonable measures should be taken to reduce banking operation, especially in the situation of large excess air ratio. Since NOx formed during the whole operation process, the most effective way of preventing liquid water and HNO3 generation is to control the pipe and shell temperature, which should be higher than the condensa- tion temperature of water vapour. The condensation temperature should be considered as the design temperature of pipe and shell for hot stove.

关键词： hot stove hazard control NO~ emission liquid water formation

Effect of Electromagnetic Stirring on Molten Steel Flow and Solidification in Bloom Mold

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Journal of Iron and Steel Research International 2014年第12期21卷 1095-1103页

作者： Zhen-guo YANG Bao WANG Xiao-feng ZHANG Ya-tao WANG Hong-biao DONG Qing LIU State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Special Steel Plant Laiwu Iron and Steel Co.Ltd. Department of Engineering University of Leicester

The effect of electromagnetic stirring on molten steel flow and heat transfer in a 260 mm× 300 mm bloom mold was investigated by using a method combining both finite element method and finite volume method. The simu lation results related to magnetic fields were consistent with the onsite measured data. The magnetic flux density in creased with increasing the current intensity but decreased with increasing the current frequency. Electromagnetic stirring caused molten steel to flow with rotation on a horizontal section and two sets of recirculation regions with opposite fellow directions in a longitudinal section formed. The maximum tangential velocity increased with increasing the current intensity and frequency. Furthermore, the superheat degree of the molten steel on the outlet cross section of the mold decreased with increasing the current intensity. growth zone of solidified shell in the effective stirring zone. bearing steel, the appropriate values of current intensity and to be 300 A and 3 Hz, respectively. Electromagnetic stirring caused the emergence of a zero For the 260 mm N 300 mm bloom continuous caster of current frequency of electromagnetic stirring were found

关键词： bloom mold electromagnetic stirring flow heat transfer numerical simulation bearing steel

Hull form optimization of a cargo ship for reduced drag

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Journal of Hydrodynamics 2016年第2期28卷 173-183页

作者： Fuxin HUANG Chi YANG Department of Physics and Astronomy George Mason University

Hydrodynamic optimization of the hull forms can be realized through the implementation and integration of computational tools that consist of a hydrodynamic module, a hull surface representation and modification module, and an optimization module. In the present paper, a new bulbous bow generation and modification technique has been developed and integrated into the hull surface representation and modification module. A radial basis function based surrogate model is developed to approximate the objective functions and reduce the computing cost. A multi-objective artificial bee colony optimization algorithm is implemented and integra- ted into the optimization module. To illustrate the integrated hydrodynamic optimization tools, a cargo ship is optimized for reduced drag. The optimal hull forms obtained are then validated computationally and experimentally. Validation results show that the prese- nt tools can be used efficiently and effectively in the simulation based design of the hull forms for reduced drag.

关键词： simulation based design ship hull form optimization drag reduction radial basis function surrogate model,Neumann-Michell theory

Layered virtual machine migration algorithm for network resource balancing in cloud computing

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Frontiers of Computer science 2018年第1期12卷 75-85页

作者： Xiong FU Juzhou CHEN Song DENG Junchang WANG Lin ZHANG School of Computer and Technology Nanjing University of Posts and Telecommunications Nanjing 210023 China Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Nanjing 210023 China Institute of Advanced Technology Nanjing University of Posts and Telecommunications Nanjing 210023 China

Due to the increasing sizes of cloud data centers, the number of virtual machines （VMs） and applications rises quickly. The rapid growth of large scale Internet services re- suits in unbalanced load of network resource. The bandwidth utilization rate of some physical hosts is too high, and this causes network congestion. This paper presents a layered VM migration algorithm （LVMM）. At first, the algorithm will divide the cloud data center into several regions according to the bandwidth utilization rate of the hosts. Then we bal- ance the load of network resource of each region by VM migrations, and ultimately achieve the load balance of net- work resource in the cloud data center. Through simulation experiments in different environments, it is proved that the LVMM algorithm can effectively balance the load of network resource in cloud computing.

关键词： virtual machine migration cloud computing,layered theory load balancing

Technology Development for Controlling Slab Transverse Corner Crack of Typical Micro-alloyed Steels

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Journal of Iron and Steel Research International 2015年第2期22卷 99-105页

作者： Hui ZHANG Chun-zheng YANG Ming-lin WANG Hong-biao TAO He-ping LIU Xue-bing WANG Central Iron and Steel Research Institute Shougang Jingtang United Iron and Steel Co. Ltd.

A mathematical model for simulating the fluid flow, heat transfer and solidification in the conventional mold and the chamfer mold, together with a finite element stress-strain model in the straightening process of both molds, were established for the typical niobium, vanadium, and titanium micro-alloyed steels. On the basis of both numerical analysis, the mold copper plate with an optimum chamfered shape was designed and applied in industrial tests. The predicted results from numerical simulation of fluid flow, heat transfer and solidification in the conven tional mold and the chamfer mold show that the increased chamfered angle leads to an approximately linear increase o[ the slab surface temperature, but it also causes strong flow near the slab corner. Very small chamfered length can lead to a significant increase of the temperature near the slab corner. However, with further increasing the chamfered length, the temperature of the slab corner increased slightly. The calculated results from the finite element analysis of stress-strain during the straightening process show that at the same slope width, the tangential strain on the slat） edges and corners is minimum when the chamfered angle is 30° and 45°, which is only 40° to 46° of rectangular slabs with the same cross-section area. At the same chamfered angle of 30°, when the chamfered length is controlled between 65-85 mm, the tangential strain on the part of the slab edges and corners is relatively smaller. Industrial test results show that the slab corner temperature at straightening segment increases about 100 ℃ by using chamfer mold compared to the conventional molds. The slab transverse corner cracks have been reduced more than 95° in comparison with those in the conventional mold.

关键词： micro-alloyed steel transverse corner crack chamfer mold slab

Microstructure modification of Y2O3 stabilized ZrO2 thermal barrier coatings by laser glazing and the effects on the hot corrosion resistance

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Journal of Advanced Ceramics 2020年第2期9卷 232-242页

作者： Lei GUO Hui XIN Zhao ZHANG Xinmu ZHANG Fuxing YE School of Materials science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced Joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China School of Materials science and Engineering Liaocheng UniversityLiaocheng 252059China

Y2O3 stabilized ZrO2(YSZ)thermal barrier coatings(TBCs)are prone to hot corrosion by molten *** this study,the microstructure of atmospheric plasma spraying YSZ TBCs is modified by laser glazing in order to improve the corrosion *** optimizing the laser parameters,a^18μm smooth glazed layer with some vertical cracks was produced on the coating *** as-sprayed and modified coatings were both exposed to hot corrosion tests at 700 and 1000℃for 4 h in V2O5 molten salt,and the results revealed that the modified one had improved corrosion *** hot corrosion,the glazed layer kept structural integrity,with little evidence of ***,the vertical cracks in the glazed layer acted as the paths for molten salt penetration,accelerating the corrosion of the non-modified *** optimization of the glazed layer is needed in the future work.

关键词： thermal barrier coatings(TBCs) air plasma spraying(APS) Y2O3 stabilized ZrO2 microstructure modification laser glazing V2O5 corrosion