超精密平面研磨加工速度对精度的影响

为了提高加工精度和减少研磨轮磨损,对研磨加工过程中的加工参数进行分析.针对目前常用的两种不同结构砂轮(放射线研磨轮以及螺旋线研磨轮),采用加工精度系数和砂轮磨损系数的概念描述加工精度与砂轮磨损,并提出相应的数学模型,以分析加工参数与工件精度及研磨轮磨损的关系.着重探讨了研磨轮与工件相对速度变化对加工精度的影响.通过理论分析与实践表明:优化设计砂轮的结构、合理选择加工参数,可以实现提高研磨加工精度及降低砂轮磨损的目的.     

压铸机双曲肘合模机构参数关系的研究

合模机构是压铸机最重要的部件之一,其结构直接影响到整个压铸机的性能.使用MathCAD软件对双曲肘合模机构的参数关系进行研究,总结出参数关系表.     

相对小裂纹da／dN公式参数的试验测定法

本文研究了耐久性分析的确定性裂纹增长方法（DCGA）中相对小裂纹的da／dN公式参数的试验测定方法,为耐久性分析的“发展的确定性裂纹增长方法（EDCGA）[1]”提供了计算依据,从而使应用这一改进后的EDCGA进行损伤度评估和经济寿命预测能够得以实现。     

超混沌吕系统的滞后投影同步与参数识别

研究了超混沌吕系统的滞后投影同步与系统参数识别.在响应系统中加入适当的非线性控制器,利用Lyapunov稳定性方法和Barbalat引理进行理论分析证明,实现了驱动响应系统之间所有变量的全局滞后投影同步,并能够对超吕系统的未知参数进行识别.最后通过数值仿真对本文中提出的理论方法的正确性及可行性进行验证.     

Calibration and validation of DEM-FEM model parameters using upscaled particles based on physical experiments and simulations

The real sand is usually idealized by using upscaled particles, due to the large number of particles of tire-sand interaction. This study aims to determine a unique and complete set of DEM-FEM model parameters to improve numerical accuracy of tire-sand interaction after particles idealization. To achieve this aim, a novel method based on experimental design is proposed to calibrate the DEM-FEM model parameters by a series of single-factor numerical calibration tests. Initially, the interaction properties such as equivalent friction coefficients of particle-particle, particle-soil bin and particle-tire are determined successively by comparing experimental test with numerical simulation using the angle of repose as a bulk response. The material parameters of particles are then obtained by modified iteratively to match the stress-strain behavior of the granular assembly in triaxial test. After that, the calibrated parameter set is used to investigate the interaction mechanisms between the off-road tire and the granular terrain. Finally, the simulation results are qualitatively in agreement with the soil bin experiments, which verifies the effectiveness of the calibrated parameter set for the tractive performance analysis of tire-sand interaction.     

数字高精度脉冲信号参数测量仪的设计

本文针对高速脉冲信号的测量要求,采用FPGA为主处理器,MSP430单片机为人机交互控制器。FPGA用于对被测脉冲信号进行实时采样,并转换为相应的有效值,经由MSP430单片机的片内AD转换成数字脉冲信号。此脉冲信号进一步输入双路高速比较器电路,与作为比较器参考电压的AD转换器输出进行比较,之后两路信号送FPGA处理得到脉冲信号的上升时间。     

PARAMETERS ESTIMATION FOR A FIRST ORDER IRREVERSIBLE REACTION. A STOCHASTIC APPROACH

A first order irreversible reaction is investigated using a stochastic model in order to account for the perturbations inherent to any chemical process. The main conclusion is that the concentration is distributed according to a lognormal law rather than to a normal one. This approach leads to a maximum likelihood estimate of the kinetic constant which is different with respect to the usual least squares estimate. Moreover, the stochastic model allows us to predict not only the expected value of the concentration, but to get a confidence interval, too. Statistical tests are provided in order to detect outliers, high-leverage and influential points.     

浅谈欧陆590＋在电缆生产设备上的创新性应用

电缆挤出生产线的收线置作用是将产品均匀收卷于线盘中,生产要求收线速度和收线张力收卷平稳可靠。本文主要阐述如何创新性应用590＋系列直流控制器,通过合理设计,使电缆收卷的速度和张力控制稳定可靠。     

位相测量技术中系统参数的选择与测定

位相测量轮廓术（PMP）是将被测物体表面投影光栅条纹的灰度分布变换为位相分布，从而求得被测物体高度分布的轮廓测量技术。本文讨论PMP测量系统参数：抽样间隔X、Y；光栅周期p、q；最大系统噪声nmax以及光瞳位置参数d、L的选择和测定。这些参数的合理选择与精确测定，将提高位相测量以及位相-高度转换的精度。     

汽车模具材料表面强化中的激光相变硬化技术的研究与应用

使用不同的激光工艺参数对汽车模具CrMo铸铁、Cr12两种材料表面进行激光相变硬化试验,研究了激光硬化层沿横向和深度方向显微硬度的分布情况以及硬化层的组织结构的变化。结果表明,材料经激光强化处理,表面硬度可大幅提高,同时可以消除表面裂纹,从而有效地提高汽车模具的使用寿命。