Optimum calibration of a parallel kinematic manipulator using digital indicators

This paper presents a calibration method for parallel manipulators using a measurement system specially installed on an external fixed frame. The external fixed frame is important as an error reference for calibration in certain operations, such as in the configuration of a parallel manip- ulator functioning as a machine tool where the workpiece is fixed to a worktable. The pose of the end-effector is mea- sured using three digital indicators installed on the external fixed frame. To enable measurement, the end-effector is assumed to be a plane large enough that all digital indicators could touch. The error is defined as the difference between the theoretical and actual readings of the digital indicators. The geometric parameters of the parallel manipulator are optimized to minimize this error. This calibration method is low cost and feasible for compensating geometric parameter errors for a parallel manipulator. Optimal pose selection for the calibration is achieved using a swarm intelligence search algorithm. The method is implemented on a prototype of a six degrees-of-freedom （DOFs） Gough-Stewart platform constructed to function as a machine tool.     

几个反应参数对SiO2纳米粒子最终粒径影响的探讨

研究了在低TEOS浓度和高TEOS浓度下, TEOS浓度、NH3浓度、H2O浓度对SiO2纳米粒子最终粒径的影响.发现,在低TEOS浓度下制备的粒子,单分散性较好,粒径偏大;在高TEOS浓度下制备的粒子,粒径较小,属于纳米级粒子.另外,在低TEOS浓度和高TEOS浓度下,NH3浓度、H2O浓度对最终粒径的影响有较大差异.     

Temporal variation in modal properties of a base-isolated building during an earthquake

Temporal variation of dynamical modal properties of a base-isolated building is investigated using earthquake records in the building. A batch processing least-squares estimation method is applied to segment-wise time-series data. To construct an input-output system, an auto-regressive model with exogenous input （ARX） of second-order including a forgetting coefficient as a weighting coefficient is used for the estimation of modal parameters. The fundamental and second natural frequencies and the damping ratios of the fundamental and second natural modes of the base-isolated building are identified in the time domain. The identified results are consistent with the results obtained from the micro-tremor vibration data, forced-vibration test data and earthquake records in the present base-isolated building in the case of taking into account the amplitude-dependency of the iso- lators and viscous dampers. It is finally pointed out that several factors, e.g., amplitude dependency of the isolator and damper system and special characteristics of the series-type viscous damper system, may be related complicatedly with the temporal variation in modal properties of the above-mentioned system.     

Fanuc系统参数在伺服系统调试中的应用

Fanuc数控系统在我国机床行业的市场占有率相当高,数控系统参数对数控系统的正常运行以及故障的排除具有至关重要的作用,因此了解重要系统参数的含义及设置方法对于搞好数控系统调试和维修非常必要。     

简析不锈钢的切削加工

阐述了不锈钢的加工特点,并从化学和物理的角度对其难切削加工的特性进行了分析,对切削不锈钢所使用的刀具材料、刀具几何参数的确定进行了说明,对切削用量的选择进行了具体的描述,并对切削液的使用提出了建设性的看法。     

光面爆破技术在复杂地质隧洞开挖中的应用

根据勐野江水电站隧洞围岩岩体类别差异性大的特殊地质条件,采用工程类比和现场试验法,研究复杂地质条件下隧洞光面爆破的爆破参数、炮孔布置、装药结构、起爆网路、施工方案及处理措施.研究结果表明,在复杂地质条件下进行洞室开挖,只要选择正确的爆破参数和合理的施工方法也可以取得良好的爆破效果.     

离散混沌系统的参量驱动同步

介绍利用驱动参量法实现混沌同步的过程，用该法成功实现了离散混沌系统Logistic映象与Henon映象的同步。     

带右删失数据的非线性随机效应模型参数估计

本文讨论了带右删失数据的非线性随机效应模型的参数估计,给出Gauss-Newton迭代法和改进后的Gauss-Newton迭代法,根据参数估计和算法给出数值模拟,验证了参数估计和算法的可行性.     

AgxZn1-x和AgxAl1-x双相合金超导体的超导态参数

A well-known pseudopotential is used to investigate the superconducting state parameters (SSP), viz., electron-phonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength for AgxZn1-x and AgxAl1-x binary alloys theoretically for the first time. We have incorporated here five different types of the local field correction functions to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of various exchange and correlation functions is concluded from the present study. Comparison with others such experimental values is encouraging, which confirms applicability of the model potential in explaining the superconducting state parameters of binary mixture.     

细胞饼瞬时表达体系的优化

细胞饼瞬时转化技术具有重要的应用前景,然而其转化效率的优化研究尚未见报道。通过农杆菌介导法,系统地比较不同农杆菌浓度,抗氧化剂以及表面活性剂的添加对细胞饼瞬时转化效率的影响。研究结果表明:1)侵染用农杆菌的浓度在较高水平(OD=1.0)时更有利于转化效率的提升;2)两种抗氧化剂中,辛硫酸效果较半胱氨酸为好。但两者均表现为低浓度对转化效率具有促进作用,而高浓度则表现为抑制作用;3)测试的两种表面活性剂,Triton X-100以及Silwet L-77对转化效率均具有显著提升作用,而Silwet L-77的作用则更为突出;4)在优化条件下,人白介素10的含量较对照高出3.66倍。本研究的结果可进一步提升细胞饼瞬时转化技术的应用前景,为后续这一技术的应用奠定了一定的理论基础。