速度合成定理几何证明中一直存在的概念错误

指出理论力学教材用几何法证明速度合成定理时存在的错误,从概念和几何两方面给予分析.提出了合理的位移分解图.

组合转子结构整体应力分析通用计算方法的轴向位移连续方程

为建立通用的轴向位移连续方程的力学、数学模型，本文提出了“封闭环”、“轴向位移真值”、“位移合成”等概念。

高职物理教学中的合成与分解

高职物理教学中涉及到合成与分解的地方主要有两处:一是力的合成与分解,另一是运动的合成与分解.由于学生在初中物理和数学教学中从未学过矢量概念,而高职数学中矢量的教学又要到很迟才进行,学生学习"合成与分解"的困难很多,笔者从以下几方面进行尝试,以解决学生在学习中的难点,消除模糊认识.

5R串联机器人的静态误差分析及优化方法

以5自由度串联机器人为研究对象,采用D-H法建立该机器人运动学模型,并利用微小位移合成法建立该机器人的位置误差模型,通过理论计算得到末端位置静态误差表达式。以末端位置最大误差值为评价指标,运用控制变量法,研究各连杆参数误差对该串联机器人末端位置精度的影响程度。提出一种利用Jacobi矩阵将末端运动轨迹在Descartes坐标下的误差转换为关节角修正量的算法,并对其运动过程中的关节转角进行优化。仿真结果表明,该优化方法正确、有效,可有效降低运动路径误差至3mm以下。

考察多层圆筒界面层对周向导波传播的影响

首次对界面层存在时周向导波在多层圆筒中传播问题进行理论推导,并对理论结果进行相应的数值计算。结果表明:频散现象和模态干涉现象在多层圆筒中传播时也同样出现;通过与理想的固结连接和理想的光滑连接类比发现,界面层存在时,对频散曲线和合成位移都有明显的影响,这与界面材料的Lamé常数和界面层的厚度有关。因此,工程上要根据实际需要的理想边界状况,选用合适的材料作为界面层。

滑坡测斜数据处理的应用研究

当前,我国山区滑坡现象日趋严重,对国民经济、人身安全造成重大损害。治理滑坡过程中滑坡监测尤为重要,而测斜作为一种精确、快捷的监测技术在滑坡监测中应用越来越广泛。通过对门头沟区双大路滑坡区五个钻孔进行的长时间测斜监测,在阐述测斜原理的基础上,全面系统地分析原始数据,计算出每个测点深度处的方向位移、合成位移、合成角度、位移速率,总结出了它们之间的相互对应关系和变化规律,确定了滑坡面的准确深度和滑动方向,为滑坡后期治理提供了科学依据。

Performance of fixed geosynthetic technique of GRPS embankment

Geosynthetic-reinforced and pile-supported （GRPS） embankment has been increasingly constructed in a large number of regions and for a wide range of projects in the past decades. However, many disadvantages are exposed through a lot of applications on conventional technique of GRPS embankment （called CT embankment）, i.e., intolerable settlement and lateral displacement, low geosynthetic efficiency, etc. In view of these disadvantages, the fixed geosynthetic technique of GRPS embankment （called FGT embankment） is developed in this work. In this system, the geosynthetic is fixed on the pile head by the steel bar fulcrum and concrete fixed top. The principles and construction techniques involved in the FGT embankment are described firstly. Then, the numerical analysis method and two-stage analysis method are used to study the performance of FGT embankment, respectively. It is shown that the FGT embankment can provide a better improvement technique to construct a high embankment over soft ground.

Lateral displacement of silty clay under cement-fly ash-gravel pile-supported embankments: Analytical consideration and field evidence

Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.

Redox-sensitive colorimetric polyaniline nanoprobes synthesized by a solvent=shift process

We have synthesized water-stable polyaniline nanoparticles coated with tri- armed polyethylene glycol chains using a solvent-shift method and confirmed their colloidal size and aqueous solubility. Furthermore, we have demonstrated that the polyaniline nanoparticles can be doped with biological dopants to produce distinct color changes allowing the detection of live cancer cells.

A euryarchaeal histone modulates strand displacement synthesis by replicative DNA polymerases

Euryarchaeota and Crenarchaeota, the two main lineages of the domain Archaea, encode different chromatin proteins and differ in the use of replicative DNA polymerases. Crenarchaea possess a single family B DNA polymerase(Pol B), which is capable of strand displacement modulated by the chromatin proteins Cren7 and Sul7 d. Euryarchaea have two distinct replicative DNA polymerases, PolB and PolD, a family D DNA polymerase. Here we characterized the strand displacement activities of Pol B and Pol D from the hyperthermophilic euryarchaeon Pyrococcus furiosus and investigated the influence of HPf A1, a homolog of eukaryotic histones from P. furiosus, on these activities. We showed that both Pol B and Pol D were efficient in strand displacement. HPf A1 inhibited DNA strand displacement by both DNA polymerases but exhibited little effect on the displacement of a RNA strand annealed to single-stranded template DNA. This is consistent with the finding that HPf A1 bound more tightly to double-stranded DNA than to a RNA:DNA hybrid. Our results suggest that, although crenarchaea and euryarchaea differ in chromosomal packaging, they share similar mechanisms in modulating strand displacement by DNA polymerases during lagging strand DNA synthesis.