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电磁场中的葫芦模型
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作者 吕敏 田川 《数理化学习(高中版)》 2019年第7期55-56,共2页
带电粒子在电磁场中的运动问题是学生学习物理时的一个难点.原子核物理中衰变粒子和反冲核在磁场中的运动的问题因为综合了洛伦兹力、动量守恒、电荷守恒、核物理等诸多问题,因而学生学起来感觉吃力,教师没有讲过的话,大多数学生都反映... 带电粒子在电磁场中的运动问题是学生学习物理时的一个难点.原子核物理中衰变粒子和反冲核在磁场中的运动的问题因为综合了洛伦兹力、动量守恒、电荷守恒、核物理等诸多问题,因而学生学起来感觉吃力,教师没有讲过的话,大多数学生都反映看不懂题.此文的目的就是突破这一教与学的难点. 展开更多
关键词 电磁场 反冲核 葫芦模型
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立体透视企业价值体系
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作者 杨云飞 白庆华 《科技与管理》 2003年第4期87-90,共4页
从时间、空间和维度三个视角,考察了企业的价值创造活动,并认为波特价值链理论是基于空间视角上的企业价值体系,并以房地产、啤酒行业为案例,补充发展了波特的价值链模型,提出了新颖的价值链葫芦模型;最后指出,价值理论体系在宏观层面... 从时间、空间和维度三个视角,考察了企业的价值创造活动,并认为波特价值链理论是基于空间视角上的企业价值体系,并以房地产、啤酒行业为案例,补充发展了波特的价值链模型,提出了新颖的价值链葫芦模型;最后指出,价值理论体系在宏观层面上归敛于马克思的劳动价值理论。 展开更多
关键词 企业管理 企业价值体系 价值链 葫芦模型 马克思 劳动价值理论
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基于机器学习的高应力软岩巷道支护抗毁能力预测 被引量:3
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作者 邓广哲 付英凯 《煤矿安全》 CAS 北大核心 2021年第8期201-207,共7页
为了避免传统预测方法在高应力软岩巷道支护抗毁能力预测时出现的问题,提出了基于机器学习的高应力软岩巷道支护抗毁能力预测方法;首先根据岩石物理力学性质,分析软岩强度特性,同时在支护构建模型支持下,分析软岩巷道围岩流变特性,由此... 为了避免传统预测方法在高应力软岩巷道支护抗毁能力预测时出现的问题,提出了基于机器学习的高应力软岩巷道支护抗毁能力预测方法;首先根据岩石物理力学性质,分析软岩强度特性,同时在支护构建模型支持下,分析软岩巷道围岩流变特性,由此研究高应力软岩巷道特性;然后依据软岩塑性变形机理,确定弹性区、塑性硬化区、塑性软化区和塑性流动区对应关系,并计算软岩周围岩层向临空区域运动的合力,由此确定最佳支护时间;最后使用机器学习方法将高应力软岩巷道支护结构简化为葫芦结构模型,并计算外界作用力大小,确定高应力软岩巷道支护结构质量参数矩阵。通过对比3种常规方法可知,该方法在3种不同破坏强度下预测精准度均较高。 展开更多
关键词 支护抗毁 能力预测 机器学习 软岩塑性 变形机理 葫芦结构模型 巷道支护
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Sorption of Manganese (II) and Chromium (III) Ions from Aqueous Solution Using Water Hyacinth Biomass (Eichhornia crassipes) 被引量:3
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作者 T. Tarawou D. Wankasi M. Horsfall Jnr 《Journal of Environmental Science and Engineering》 2010年第11期38-43,共6页
The use of water hyacinth biomass as adsorbent for Cr3+ and Mn2+ ions from aqueous solution by means of batch-adsorption technique was investigated to determine the potential ability of the biomaterial for metal ion... The use of water hyacinth biomass as adsorbent for Cr3+ and Mn2+ ions from aqueous solution by means of batch-adsorption technique was investigated to determine the potential ability of the biomaterial for metal ion removal. The equilibrium isotherm study showed that the maximum monolayer coverage on the biomass surface was 0.933 mg·g-1 and 0.874 mg·g-1 for Mn2+ and Cr3+ ions respectively. The highest percentage of Cr3+ and Mn2+ ions adsorbed by the biomass was 86.4% and 82.6% at the optimum pH of 4.0 and 6.0 respectively. The results also showed that the highest percentage removal 82.5% and 78.3% was obtained at 30 and 20 minutes respectively for Cr3+ and Mn2+ ions. The sorption process was examined by means of the Langmuir model. The adsorption equilibrium data were found to follow the Langmuir isotherm model with high coefficients of determination (R2 = 0.990 and 0.999) for Cr+ and Mn2+ ions respectively. The adsorption capacity of water hyacinth showed that water hyacinth will be useful in recovering chromium (III) and manganese (II) ions from solution and their subsequent removal from industrial effluents. 展开更多
关键词 SORPTION metal ions water hyacinth biomass aqueous solution.
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Research & design on the drive system of nuclear fuel manipulate crane
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作者 穆兆辉 Li Weidong Liu Rao 《High Technology Letters》 EI CAS 2014年第4期446-450,共5页
The control of nuclear fuel manipulator crane (MC) drive system is essential for its running and other systems are designed surrounding the drive system.This paper gives a brief introduction to the composition and f... The control of nuclear fuel manipulator crane (MC) drive system is essential for its running and other systems are designed surrounding the drive system.This paper gives a brief introduction to the composition and function of MC,analyses its drive mode and control method and applies PLC to control its frequency transducer directly to help the motor work more stable.Based on the control requirements of bridge,trolley,Hoist,the control system of bridge applies a drive mode with 2-drag2 drive model on both sides and a multi-control method to realize simultaneous runningof two sides,1-drag-1 model on through-going axes and closed loop control method finish the precise location of trolley,and the using of 1-drag-1 model drive mode and closed loop control method solves the protect control difficulty of hoist which stops/starts repeatedly and changes speed. 展开更多
关键词 PMC manipulate crane (MC) drive system drive mode control method
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