A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing e...A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing equations of circular plates.The relation between dimensionless final plastic deformation of circular plates and the new dimensionless number is established based on massive underwater explosion test data.Meanwhile,comparative analysis was discussed with two other published dimensionless parameters which indicated the new dimensionless number proposed in this paper is more effective and extensive to predict the dynamic plastic response of circular plates under underwater explosion condition.展开更多
This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod ...This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimensionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.展开更多
According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal ...According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal rise due to oxidation.Studying the distribution of the "Three Zones" in gob is important for predicting and preventing spontaneous combustion in coalmine.In normal mining operations,temperature of coal is roughly constant.The process of mass transfer in the gob is considered to be steady.Based on mass conservation,gas species conservation,darcy's law,Ficks law of diffusion and coal oxidation 1-grade reaction rule,governing equation for air leakage intensity and species concentration are deduced.With critical value of coal spontaneous combustion and the size of longwall workface as basic dimension,a dimensionless steady coupled model of air flow diffusion and chemical reaction in loose coal of Fully Mechanized Top-Coal Caving Mining Workface(FMTCCMW) is setup.By solving the model numerically,regulation of three zones' distribution and spontaneous combustion in the gob can be obtained.The results can be easily popularized to prediction of spontaneous combustion in other coalmines' longwall gob.展开更多
耐震时程分析(endurance time analysis,ETA)法作为结构响应分析领域的有效简化方法,基于频域地震动反应谱合成的耐震时程曲线无法准确反映时域的脉冲特性,限制了其在近断层脉冲型地震中的应用。为将ETA法应用到近断层脉冲型地震动作用...耐震时程分析(endurance time analysis,ETA)法作为结构响应分析领域的有效简化方法,基于频域地震动反应谱合成的耐震时程曲线无法准确反映时域的脉冲特性,限制了其在近断层脉冲型地震中的应用。为将ETA法应用到近断层脉冲型地震动作用下斜拉桥动力响应分析中,基于增量动力分析(incremental dynamic analysis,IDA)法研究了不同峰值下脉冲、高频分量对斜拉桥动力响应的贡献程度,构建了考虑脉冲和强度特性的斜拉桥动力响应预测模型,利用ETA法模拟高频分量下的斜拉桥动力响应并结合预测模型,预测了近断层脉冲型地震动下斜拉桥的动力响应。结果表明:建立的预测模型可以精确表达不同强度下高频分量与原始地震动响应之间的定量关系;基于ETA模型和IDA法计算出0.6 g下的平均动力响应最大相对误差不超过10%,具有良好的预测精度。研究成果为高效合理地计算近断层脉冲型地震动下斜拉桥的动力响应提供了技术支撑。展开更多
当前基于车桥耦合系统的桥梁频率间接识别方法普遍对行驶车辆参数和速度有较大约束,难以应用于正常行驶的普通车辆。为了解决这一问题,该文提出了一种考虑车辆无量纲响应的桥梁频率间接识别方法。首先,以无量纲化的车-桥耦合运动学方程...当前基于车桥耦合系统的桥梁频率间接识别方法普遍对行驶车辆参数和速度有较大约束,难以应用于正常行驶的普通车辆。为了解决这一问题,该文提出了一种考虑车辆无量纲响应的桥梁频率间接识别方法。首先,以无量纲化的车-桥耦合运动学方程为基础,构建基于改进子空间识别法的系统状态方程与输出信号方程,建立了考虑时间差的车辆双轴无量纲响应差值信号方程,从理论上有效地消除了状态方程与输出信号中的路面平整度信息,突破了传统子空间识别法对车辆参数的限制,使该方法适用于任何普通车辆,同时验证了基于单次行驶双轴车辆响应的桥梁频率间接识别方法对简支梁桥频率识别的可行性。然后,通过数值计算探讨了车辆行驶速度、路面平整度等级和随机车辆荷载对桥梁频率间接识别的影响。计算结果表明,充分的荷载激励对桥梁频率的稳定识别非常重要,并且能够激发桥梁高阶模态的振动,更有利于桥梁高阶频率的识别。最后,针对一座实际服役的高墩简支梁桥开展现场行车试验,基于车桥动态接触力作为信号输入,验证子空间识别法获得桥梁频率的可行性和准确性。试验结果表明,短时随机子空间识别方法可以提取测试桥梁前2阶频率,在高阶频率的识别中有着更优于MOESP(multivariable output error state space,MOESP)子空间识别法的效果。展开更多
基金supported by the National Natural Science Foundation of China(12402444)。
文摘A new dimensionless number is proposed for dynamic plastic deformation analysis of clamped circular plates under underwater explosion loads by introducing dimensional analysis method to the basic dynamical governing equations of circular plates.The relation between dimensionless final plastic deformation of circular plates and the new dimensionless number is established based on massive underwater explosion test data.Meanwhile,comparative analysis was discussed with two other published dimensionless parameters which indicated the new dimensionless number proposed in this paper is more effective and extensive to predict the dynamic plastic response of circular plates under underwater explosion condition.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272257,12102292,12032006)the special fund for Science and Technology Innovation Teams of Shanxi Province(Nos.202204051002006).
文摘This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimensionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.
基金Supported by the National Natural Science Foundatin of China(10972178)
文摘According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal rise due to oxidation.Studying the distribution of the "Three Zones" in gob is important for predicting and preventing spontaneous combustion in coalmine.In normal mining operations,temperature of coal is roughly constant.The process of mass transfer in the gob is considered to be steady.Based on mass conservation,gas species conservation,darcy's law,Ficks law of diffusion and coal oxidation 1-grade reaction rule,governing equation for air leakage intensity and species concentration are deduced.With critical value of coal spontaneous combustion and the size of longwall workface as basic dimension,a dimensionless steady coupled model of air flow diffusion and chemical reaction in loose coal of Fully Mechanized Top-Coal Caving Mining Workface(FMTCCMW) is setup.By solving the model numerically,regulation of three zones' distribution and spontaneous combustion in the gob can be obtained.The results can be easily popularized to prediction of spontaneous combustion in other coalmines' longwall gob.
文摘当前基于车桥耦合系统的桥梁频率间接识别方法普遍对行驶车辆参数和速度有较大约束,难以应用于正常行驶的普通车辆。为了解决这一问题,该文提出了一种考虑车辆无量纲响应的桥梁频率间接识别方法。首先,以无量纲化的车-桥耦合运动学方程为基础,构建基于改进子空间识别法的系统状态方程与输出信号方程,建立了考虑时间差的车辆双轴无量纲响应差值信号方程,从理论上有效地消除了状态方程与输出信号中的路面平整度信息,突破了传统子空间识别法对车辆参数的限制,使该方法适用于任何普通车辆,同时验证了基于单次行驶双轴车辆响应的桥梁频率间接识别方法对简支梁桥频率识别的可行性。然后,通过数值计算探讨了车辆行驶速度、路面平整度等级和随机车辆荷载对桥梁频率间接识别的影响。计算结果表明,充分的荷载激励对桥梁频率的稳定识别非常重要,并且能够激发桥梁高阶模态的振动,更有利于桥梁高阶频率的识别。最后,针对一座实际服役的高墩简支梁桥开展现场行车试验,基于车桥动态接触力作为信号输入,验证子空间识别法获得桥梁频率的可行性和准确性。试验结果表明,短时随机子空间识别方法可以提取测试桥梁前2阶频率,在高阶频率的识别中有着更优于MOESP(multivariable output error state space,MOESP)子空间识别法的效果。
