利用蒙特卡洛方法计算陶瓷刀具磨损可靠性

在连续切削条件下,陶瓷刀具的失效形式是以磨粒磨损为主的摩损失效,其磨损寿命由材料的断裂韧性、硬度和切削过程的参数决定,利用蒙特卡洛方法分别随机生成断裂韧性与硬度的样本值,利用连续车削试验确定切削过程参数,将得到的样本值与切削参数相结合可计算刀具在相应切削条件下的磨损寿命及其可靠性,计算结果表明：陶瓷刀具的断裂韧对磨损寿命的可靠性影响较为明显,因而可以利用断裂韧性来估算磨损可靠性。     

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通过对套铣筒这种特殊结构钻柱的分析,在现有钻柱力学模型研究的基础上,针对 套铣筒结构特点(大筒径、薄壁筒型钻柱),建立套铣筒与井壁接触力学模型,通过分析套铣 管柱在井下屈曲状态以及与井壁接触压力的计算,对套铣筒进行力学分析以及摩阻力计算.     

NORMAL GRID RULE FOR HYPERSONIC HEAT FLUX NUMERICAL SIMULATION

采用数值求解雷诺平均Navier-Stokes 方程方法对高超声速钝双锥模型进行了计算,比较了不同法向网格尺度对热流计算的影响,并在此基础上提出了一种适于热流计算的网格准则. 研究表明:在实际外形的热流计算中,使用过密或过粗的法向网格均不利于得到准确的热流数据;采用该文提出的基于当地温度梯度的法向网格尺度准则可以在保证热流计算精度的同时实现较高的收敛速度.     

A General Random Walk Model of Molecular Motor

A general random walk model framework is presented which can be used to statistically describe the internaldynamics and external mechanical movement of molecular motors along filament track. The motion of molecular motorin a periodic potential and a constant force is considered. We show that the molecular motor‘s movement becomesslower with the potential barrier increasing, but if the forceis increased, the molecular motor‘s movement becomesfaster. The relation between the effective rate constant and the potential barrier‘s height, and that between the effectiverate constant and the value of the force are discussed. Our results are consistent with the experiments and relevanttheoretical consideration, and can be used to explain some physiological phenomena.     

Obstacle Effects on One-Dimensional Translocation of ATPase

We apply a general random walk model to the study of the ATPase‘s one-dimensional translocation along obstacle biological environment, and show the effects of random obstacles on the ATPase translocation along single stranded DNA. We find that the obstacle environment can reduce the lifetime of ATPase lattice-bound state which results in the inhibition of ATPase activity. We also carry out the ranges of rate constant of ATPase unidirectonal translocation and bidirectional translocation. Our results are consistent with the experiments and relevant theoretical consideration, and can be used to explain some physiological phenomena.     

并联机器人刚度与静力学研究现状与进展

并联机器人的刚度与静力学分析, 对于机构力学性能研究具有重要的理论价值和意义. 本文围绕杆支撑、绳牵引和钢带传动 3 种结构形式, 详细阐述了国内外并联机构刚度和静力学分析的研究现状. 着重从有限元、解析模型和性能分析 3 方面分析了杆支撑并联机构的刚度研究进展. 讨论了有关绳牵引并联机构中绳拉力、动载荷频率、绳牵引预紧力与刚度、静力学之间关系的研究成果. 根据钢带并联机器人结构的特殊性, 对钢带并联机构的刚度与静力学分析中可能遇到的失稳与振动问题进行了探讨. 最后, 对并联机器人技术发展情况进行总结与展望, 指出随着刚度分析与静力学分析的不断深入, 并联机器人的力学理论将会日趋成熟和完善, 为并联机器人机构优化设计提供更深入、系统的理论依据.      

深圳某电厂H型钢桩沉桩与效果测试

在上部为花岗岩块石填土、下部为相对软弱的粘性土 ,地下水与海水相通的地区进行大型工程建设 ,主要建 (构 )筑物采用桩基础是安全可靠的措施 ,但采用何种桩型、沉桩时怎样才能顺利穿过花岗岩块石填土是一个值得研究的课题。采用潜孔锤引孔穿过花岗岩块石填土 ,往孔内回填碎石 ,然后打H型钢桩 ,在深圳某电厂地基处理中获得了较好的效果     

A General Random Walk Model of Molecular Motor

A general random walk model framework is presented which can be used to statistically describe the internal dynamics and external mechanical movement of molecular motors along filament track. The motion of molecular motor in a periodic potential and a constant force is considered. We show that the molecular motor‘s movement becomes slower with the potential barrier increasing, but if the force is increased, the molecular motor‘‘s movement becomes faster. The relation between the effective rate constant and the potential battler‘s height, and that between the effective rate constant and the value of the force are discussed. Our results are consistent with the experiments and relevant theoretical consideration, and can be used to explain some physiological phenomena.     

迷迭香中微量元素与黄酮类化合物的含量分析

以甲醇为溶剂用索氏提取法提取迷迭香中总黄酮,用比色法测定了其含量;并采用电感耦合等离子体-原子发射光谱仪(ICP-AES)测定了该植物中9种微量元素的含量。结果表明:迷迭香中黄酮类化合物的含量为1.61mg/g,加样回收率为98.98%—100.06%,RSD为0.419%(n=6),该法操作简便,重现性好,适合于黄酮类化合物含量的测定;迷迭香中Fe、K、Mg、Mn、Zn含量丰富。     

湖南扬子地台砂矿金刚石的红外、拉曼特征及指示意义

产于湖南沅水地区的十颗砂矿金刚石的红外光谱和拉曼光谱的研究结果表明：湖南砂矿金刚石多为I_aAB型,且往往表现为A型氮相对富集;金刚石中的氮含量介于38.30～840.67 μg·g-1之间,且不同金刚石晶体中氮含量差别极大;金刚石在地幔中的存储时间介于0.043～3.315 Ga之间,不同的样品在地幔中的存储时间相差较大,且最长存储时间(3.315 Ga)要大于湘鄂黔桂毗邻区最老岩体的年龄(3.285 Ga);湖南砂矿金刚石在其形成过程中经历过较为显著的环境变化,且菱形十二面体金刚石晶体的形成深度大于八面体金刚石晶体。