The stability of slopes and tunnels is controlled by rock discontinuities,and the rock discontinuities roughness and the sliding direction play a signifcant role in shear failure.However,three-dimensional roughness ev...The stability of slopes and tunnels is controlled by rock discontinuities,and the rock discontinuities roughness and the sliding direction play a signifcant role in shear failure.However,three-dimensional roughness evaluation considering shear directions is scare,and the internal shear fracturing processes,micromechanical mechanisms and failure precursor of rock discontinuities are not well understood.Therefore,this study proposes a novel roughness evaluation index to quantitatively analyze the anisotropic characteristics of rock discontinuities.In conjunction with shear tests,a novel 3D-GBM modelling method considering the micromineral constituent and particle size distribution characteristics of granite as well as the geometric shape of discontinuities was realized.The strength,macro and micro-fracture characteristics,visual anisotropic shear evolution process and microfailure mechanism of granite discontinuities at diferent roughness and shear direction were investigated.Finally,the spatial and temporal evolutions of AE parameter b-value and magnitude M were further analyzed to reveal the shear fracture precursor of granite discontinuities.展开更多
Alkaline slag is vital in rare earth steel refining,making it crucial to study the wetting and penetration mechanisms between refractory materials and slag.The effect of Eu_(2)O_(3) doping on the sintering properties ...Alkaline slag is vital in rare earth steel refining,making it crucial to study the wetting and penetration mechanisms between refractory materials and slag.The effect of Eu_(2)O_(3) doping on the sintering properties of MgO-MgAl_(2)O_(4) refractory materials was investigated while simulating the wetting behavior between the refractory and the CaO-Al_(2)O_(3)-SiO_(2)-MgO quaternary alkaline slag during rare earth steel smelting to improve the material’s resistance to alkaline slag corrosion.The doping of Eu_(2)O_(3) can alter the crystal structure parameters of MgAl_(2)O_(4) and MgO,causing lattice distortion.This lattice activation promotes interionic mass and diffusion,helping reduce porosity and promote densification of the material,further improving sintering properties.At the equilibrium wetting temperature(1723 K),Eu_(2)O_(3) doping increases the interfacial free energy between the slag and refractory material,reducing the spreading coefficient of the molten slag.The contact angle increases from 32.1°to 42.2°,and the residual slag volume increases from 17.9%to 23.5%.The results of thermodynamic analysis show that MgAl_(2)O_(4) and EuAlO3 formed at the interface block the penetration of molten slag at high temperatures,improving the resistance of MgO-MgAl_(2)O_(4) refractories to alkaline slag corrosion.Based on the capillary theory model,it was calculated that the capillary tension of the slag gradually increases with the addition of Eu_(2)O_(3),while the theoretical penetration depth of the slag gradually decreases.The experimental results showed that the slag erosion depth of the sample decreased from 102.54 to 68.28μm.展开更多
高熵合金突破传统合金设计思想,依靠近等摩尔比、不低于5种组元混合形成具有远低于平衡相所预测的相数和简单的固溶体结构,从而有可能冲破传统金属材料的性能极限。为了研究多主元合金元素的物相形成机理与显微组织结构对宏观摩擦磨损...高熵合金突破传统合金设计思想,依靠近等摩尔比、不低于5种组元混合形成具有远低于平衡相所预测的相数和简单的固溶体结构,从而有可能冲破传统金属材料的性能极限。为了研究多主元合金元素的物相形成机理与显微组织结构对宏观摩擦磨损性能的影响,采用非自耗电弧熔炼技术制备了等摩尔比的Al Co Cr Cu Fe多主元高熵合金。用X射线衍射仪、扫描电子显微镜、能谱分析仪、显微硬度计和摩擦磨损试验机测试了Al Co Cr Cu Fe合金的物相结构、显微组织与摩擦磨损性能。研究发现:Al Co Cr Cu Fe高熵合金的显微组织为典型的树枝晶,由简单的BCC相和FCC相构成,且BCC相和FCC相的各衍射峰均普遍较宽。在干摩擦条件下,Al Co Cr Cu Fe/GCr15摩擦副的摩擦系数随摩擦时间增大呈先升高后降低再稳定的过程,其磨损机制由剥层磨损向氧化磨损转变,其平均摩擦系数为0.55,质量损失率为1.44%。结果表明:晶间为Cu元素富集区域;枝晶区域为调幅分解的网格层状结构;枝晶边界附近有纳米颗粒析出。Cu元素晶间富集主要是由于Cu与其他元素的混合焓、结合能力、互溶性、熔点等差异较大引起的;枝晶区域的调幅分解层状结构则主要是因为原子尺寸因素产生的共格应力与弹性交互作用抑制了组织长大;枝晶边界附近的纳米颗粒析出则由迟滞扩散效应、金属遗传性与工艺过程所决定。BCC相和FCC相衍射峰变宽是由于各组元原子半径差较大、各元素等摩尔比存在且混合焓不同、合金内部有较大残余应力以及晶粒尺寸小范围广所致。展开更多
Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of subst...Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of substrate and plating films were investigated,The result shows that Ni-P electroless plating could be divided two steps:the induction period and the rapid deposition period.The Ni-P film is amorphous structure:A excellent Ni-P coating can be obtained under the optimal parameter.The Ni-P coating can obviously improve the corrosion resistance of Mg alloy in variety environment.展开更多
The interaction of spinodal decomposition and recrystallization process, and the characteristic of recrystallization in Cu-Ni-Fe alloy aged at different temperatures after solution-treatment and cold rolling have been...The interaction of spinodal decomposition and recrystallization process, and the characteristic of recrystallization in Cu-Ni-Fe alloy aged at different temperatures after solution-treatment and cold rolling have been studied by structural analysis and Vickers hardness test. It has shown that the recrystallization of spinodal Cu -Ni-Fe alloy might be divided into 2 types: spinodal decomposition, recovery and recrystallization of two-phase microstructure take place in the deformed alloy aged below the spinodal temperature; while recrystallization of single-phase microstructure and growth of fully-recrystallized grains take place in the deformed alloy aged above the spinodal temperature. The deformed alloy aged below the spinodal temperature recrystallizes in cellular morphology.展开更多
With respect to the multiple attribute decision making problems with linguistic preference relations on alternatives in the form of incomplete linguistic judgment matrix, a method is proposed to analyze the decision p...With respect to the multiple attribute decision making problems with linguistic preference relations on alternatives in the form of incomplete linguistic judgment matrix, a method is proposed to analyze the decision problem. The incomplete linguistic judgment matrix is transformed into incomplete fuzzy judgment matrix and an optimization model is developed on the basis of incomplete fuzzy judgment matrix provided by the decision maker and the decision matrix to determine attribute weights by Lagrange multiplier method. Then the overall values of all alternatives are calculated to rank them. A numerical example is given to illustrate the feasibility and practicality of the proposed method.展开更多
Based on bounded network-induced time-delay, the networked control system is modeled as a linear time-variant singular system. Using the Lyapunov theory and the linear matrix inequality approach, the criteria for dela...Based on bounded network-induced time-delay, the networked control system is modeled as a linear time-variant singular system. Using the Lyapunov theory and the linear matrix inequality approach, the criteria for delay-independent stability and delay-dependent stability of singular networked control systems are derived and transformed to a feasibility problem of linear matrix inequality formulation, which can be solved by the Matlab LMI toolbox, and the feasible solutions provide the maximum allowable delay bound that makes the system stable. A numerical example is provided, which shows that the analysis method is valid and the stability criteria are feasible.展开更多
基金Financial support to complete this study was provided in part by National Natural Science Foundation of China(52109119)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(China Institute of Water Resources and Hydropower Research)(IWHR-SKL-202202)+1 种基金the China Postdoctoral Science Foundation Project(2022M723408)the Systematic Project of Guangxi Key Laboratory of Disaster Prevention and Engineering Safety(2020ZDK007)。
文摘The stability of slopes and tunnels is controlled by rock discontinuities,and the rock discontinuities roughness and the sliding direction play a signifcant role in shear failure.However,three-dimensional roughness evaluation considering shear directions is scare,and the internal shear fracturing processes,micromechanical mechanisms and failure precursor of rock discontinuities are not well understood.Therefore,this study proposes a novel roughness evaluation index to quantitatively analyze the anisotropic characteristics of rock discontinuities.In conjunction with shear tests,a novel 3D-GBM modelling method considering the micromineral constituent and particle size distribution characteristics of granite as well as the geometric shape of discontinuities was realized.The strength,macro and micro-fracture characteristics,visual anisotropic shear evolution process and microfailure mechanism of granite discontinuities at diferent roughness and shear direction were investigated.Finally,the spatial and temporal evolutions of AE parameter b-value and magnitude M were further analyzed to reveal the shear fracture precursor of granite discontinuities.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U21A2057 and U1908223)the open research fund for the State Key Laboratory of Advanced Refractories(Grant No.SKLAR202405).
文摘Alkaline slag is vital in rare earth steel refining,making it crucial to study the wetting and penetration mechanisms between refractory materials and slag.The effect of Eu_(2)O_(3) doping on the sintering properties of MgO-MgAl_(2)O_(4) refractory materials was investigated while simulating the wetting behavior between the refractory and the CaO-Al_(2)O_(3)-SiO_(2)-MgO quaternary alkaline slag during rare earth steel smelting to improve the material’s resistance to alkaline slag corrosion.The doping of Eu_(2)O_(3) can alter the crystal structure parameters of MgAl_(2)O_(4) and MgO,causing lattice distortion.This lattice activation promotes interionic mass and diffusion,helping reduce porosity and promote densification of the material,further improving sintering properties.At the equilibrium wetting temperature(1723 K),Eu_(2)O_(3) doping increases the interfacial free energy between the slag and refractory material,reducing the spreading coefficient of the molten slag.The contact angle increases from 32.1°to 42.2°,and the residual slag volume increases from 17.9%to 23.5%.The results of thermodynamic analysis show that MgAl_(2)O_(4) and EuAlO3 formed at the interface block the penetration of molten slag at high temperatures,improving the resistance of MgO-MgAl_(2)O_(4) refractories to alkaline slag corrosion.Based on the capillary theory model,it was calculated that the capillary tension of the slag gradually increases with the addition of Eu_(2)O_(3),while the theoretical penetration depth of the slag gradually decreases.The experimental results showed that the slag erosion depth of the sample decreased from 102.54 to 68.28μm.
文摘高熵合金突破传统合金设计思想,依靠近等摩尔比、不低于5种组元混合形成具有远低于平衡相所预测的相数和简单的固溶体结构,从而有可能冲破传统金属材料的性能极限。为了研究多主元合金元素的物相形成机理与显微组织结构对宏观摩擦磨损性能的影响,采用非自耗电弧熔炼技术制备了等摩尔比的Al Co Cr Cu Fe多主元高熵合金。用X射线衍射仪、扫描电子显微镜、能谱分析仪、显微硬度计和摩擦磨损试验机测试了Al Co Cr Cu Fe合金的物相结构、显微组织与摩擦磨损性能。研究发现:Al Co Cr Cu Fe高熵合金的显微组织为典型的树枝晶,由简单的BCC相和FCC相构成,且BCC相和FCC相的各衍射峰均普遍较宽。在干摩擦条件下,Al Co Cr Cu Fe/GCr15摩擦副的摩擦系数随摩擦时间增大呈先升高后降低再稳定的过程,其磨损机制由剥层磨损向氧化磨损转变,其平均摩擦系数为0.55,质量损失率为1.44%。结果表明:晶间为Cu元素富集区域;枝晶区域为调幅分解的网格层状结构;枝晶边界附近有纳米颗粒析出。Cu元素晶间富集主要是由于Cu与其他元素的混合焓、结合能力、互溶性、熔点等差异较大引起的;枝晶区域的调幅分解层状结构则主要是因为原子尺寸因素产生的共格应力与弹性交互作用抑制了组织长大;枝晶边界附近的纳米颗粒析出则由迟滞扩散效应、金属遗传性与工艺过程所决定。BCC相和FCC相衍射峰变宽是由于各组元原子半径差较大、各元素等摩尔比存在且混合焓不同、合金内部有较大残余应力以及晶粒尺寸小范围广所致。
基金National Hi-Tech Research and Development Program"863"
文摘Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of substrate and plating films were investigated,The result shows that Ni-P electroless plating could be divided two steps:the induction period and the rapid deposition period.The Ni-P film is amorphous structure:A excellent Ni-P coating can be obtained under the optimal parameter.The Ni-P coating can obviously improve the corrosion resistance of Mg alloy in variety environment.
文摘The interaction of spinodal decomposition and recrystallization process, and the characteristic of recrystallization in Cu-Ni-Fe alloy aged at different temperatures after solution-treatment and cold rolling have been studied by structural analysis and Vickers hardness test. It has shown that the recrystallization of spinodal Cu -Ni-Fe alloy might be divided into 2 types: spinodal decomposition, recovery and recrystallization of two-phase microstructure take place in the deformed alloy aged below the spinodal temperature; while recrystallization of single-phase microstructure and growth of fully-recrystallized grains take place in the deformed alloy aged above the spinodal temperature. The deformed alloy aged below the spinodal temperature recrystallizes in cellular morphology.
基金the National Natural Science Foundation of China (70701008)National Science Foundationfor Distinguished Young Scholars of China (70525002)
文摘With respect to the multiple attribute decision making problems with linguistic preference relations on alternatives in the form of incomplete linguistic judgment matrix, a method is proposed to analyze the decision problem. The incomplete linguistic judgment matrix is transformed into incomplete fuzzy judgment matrix and an optimization model is developed on the basis of incomplete fuzzy judgment matrix provided by the decision maker and the decision matrix to determine attribute weights by Lagrange multiplier method. Then the overall values of all alternatives are calculated to rank them. A numerical example is given to illustrate the feasibility and practicality of the proposed method.
基金the National Natural Science Foundation of China (60574011)the National Natural Science Foundation of Liaoning Province (2050770).
文摘Based on bounded network-induced time-delay, the networked control system is modeled as a linear time-variant singular system. Using the Lyapunov theory and the linear matrix inequality approach, the criteria for delay-independent stability and delay-dependent stability of singular networked control systems are derived and transformed to a feasibility problem of linear matrix inequality formulation, which can be solved by the Matlab LMI toolbox, and the feasible solutions provide the maximum allowable delay bound that makes the system stable. A numerical example is provided, which shows that the analysis method is valid and the stability criteria are feasible.
