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991.
通过煤泥窄粒级浮选速率实验,以煤泥浮选一级动力学为基础,对煤泥浮选动力学的关键参数进行研究,包括最大可燃体回收率ε∞的计算、浮选级数n的确定、浮选速率常数K的变化.结果表明:浮选动力学模型中ε∞的经验解比模型解更符合实际;窄粒级煤泥的浮选动力学级数最符合一级动力学;窄粒级煤泥的浮选速率常数K是时间的函数,可用幂函数或经验公式表达,先求出ε∞的经验解,再求解K(t)函数,所得模型非常符合煤泥浮选特征的浮选动力学模型. 相似文献
992.
993.
A beam-column joint of precast and partial steel reinforced concrete( PPSRC) is proposed for precast reinforced concrete frames. The PPSRC consists of partial steel and reinforced concrete. The partial steel is located in the core joint region and the connections between concrete members. This paper presents an experimental study of a series of PPSRC specimens. These specimens are tested under low cyclic loading.Experimental results demonstrate that the bearing capacity of the PPSRC specimens is 3 times that of the ordinary reinforced concrete( RC) beam-column joints. The strength and stiffness degradation rates are slower compared with that of the RC beam-column joints. In addition,the strength of the core joint region and the connections is higher than other parts of the PPSRC specimens. Beam failure occurs firstly for the PPSRC specimens,followed by column failure and connections failure. The failure of the core joint region occurs finally.Test results show that the seismic performance of the PPSRC is better than that of the ordinary RC beam-column joints. 相似文献
994.
钢板移动式感应加热的多场耦合数值分析 总被引:1,自引:0,他引:1
针对钢板的感应加热弯板成形问题,利用ANSYS软件的物理环境法建立了钢板移动式感应加热的电磁-热-结构耦合分析的数值模型。为了实现移动加热的模拟,采用节点约束方程解决了钢板、感应器和空气间隙组成的求解域的多场耦合问题,数值计算结果与实验数据吻合,验证了数值模型的正确性。然后,对钢板感应加热过程进行了数值分析,得出结论:感应加热过程中,涡流集中分布于感应器前端的钢板金属,有利于钢板快速升温,并迅速进入准稳态加热状态;在加热结束时,磁通密度外扩形成感应加热过程所特有的端部效应,从而影响钢板端部的温度分布及最终的板边变形。 相似文献
995.
为求解一类非线性矩阵方程的对称解,提出一种双迭代算法。运用牛顿迭代解法求解一类非线性矩阵方程的对称解,应用修正共轭梯度法求解由牛顿法每一步迭代所得到的线性矩阵方程的对称解或最小二乘对称解。数值实例表明,该双迭代算法是有效的。 相似文献
996.
Safety threshold of high-speed railway pier settlement based on train-track-bridge dynamic interaction 总被引:1,自引:0,他引:1
This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed railways.An analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge system.By adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs,the variations of vehicle dynamics indices with pier settlement are comparatively analyzed.Then,the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed trains.Results show that the dynamics indices of different trains have different sensitivities to the pier settlement,and the train CRH2C is the most sensitive one among all the types of Chinese high-speed trains.When passing through the bridges in common span with pier settlement at the speed of 250–350 km/h,the trains suffer the low-frequency excitations,and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics indices.When the car body vertical acceleration just exceeds the allowable limit,the critical settlement value is 23.4 mm,which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways. 相似文献
997.
基于密度泛函理论的第一性原理方法,对六方纤锌矿结构的Zn O晶体,N、Ag分别掺杂Zn O,以及Ag-2N共掺杂Zn O晶体的几何结构分别进行了比较研究,在此基础上计算得到了未掺杂Zn O晶体和不同掺杂情况下Zn O晶体的能带结构、总体态密度、分波态密度和电荷布居数.结果显示:Ag-2N共掺杂Zn O具有较稳定的结构,能有效提高载流子粒子数分数,更容易得到稳定的p型Zn O. 相似文献
998.
999.
To alleviate the main limitations of lithium ion diffusion rate and poor electronic conductivity for LiFePO4 cathode material, it is desirable to synthesize nano-size LiFePO4 material due to its enhanced electronic and lithium ion transport rates and thus an improved high-rate performance. However, our previous synthesized LiFePO4 nanorods only exhibited low high-rate and slightly unstable cycle performance. Possible reasons are the poor crystallization and Fe2+ oxidation of LiFePO4 nanorods prepared by hydrothermal method. In this paper, LiFePO4 nanorods were simply dealt with at 700 ℃ for 4 h under the protection of Ar and H2 mixture gas. The electrochemical properties of LiFePO4/Li cells were investigated by galvanostatic test and cyclic voltammetry(CV). The experimental results indicated that the annealed LiFePO4 nanorods delivered an excellent cycling stability and obviously improved capacity of 150 mA·h·g-1 at 1C, and even 122 mA·h·g-1 at 5C. 相似文献
1000.
The degradation mechanisms of cementitious materials exposed to sulfate solutions have been controversial, despite considerable research. In this paper, two methodologies of image analysis based on scanning electron microscope and chemical mapping are used to analyse Portland cement mortars exposed to sodium sulfate solution. The effects of sulfate concentration in solution and water to cement ratio of mortar, which are considered as the most sensitive factors to sulfate attack, are investigated respectively by comparing the macro expansion with microstructure analysis. It is found that the sulfate concentration in pore solution, expressed as sulfate content in C-S-H, plays a critical role on the supersaturation with respect to ettringite and so on the expansion force generated. 相似文献