定位误差的本质及其计算方法讨论

定位误差的分析和计算是进行工艺装备设计必不可少的重要环节。文中根据工程实践及教学体会，分析了计算定位误差的原因和定位误差的本质，并结合具体的实例．对计算定位误差的三种方法——定义法、合成法、微分法进行了阐述，为正确选择计算方法提供了依据。     

基于激光准直的直线度误差自动测量系统

介绍了基于激光准直原理的直线度误差自动检测方法，详细分析了激光器、传感器信号处理电路和数据采集处理系统的设计。软件开发时结合了直线度误差的两类测量方法和两种误差评定方法，不仅能与激光准直仪、电子水平仪、光学自准直仪等多种仪器配合使用，而且采用了符合最小条件原理的两条理想包客参考直线精确计算直线度误差，具有运算精度高、运算速度快的特点，应用袁明系统性能稳定可靠，具有推广应用价值。     

机器人关节摩擦的自适应模糊补偿建模与控制

采用自适应模糊系统在线逼近摩擦模型并将模型辨识结果作为控制算法的补偿项，在控制方法上，采用了基于自适应模糊补偿的PD算法。在系统证明上，从李雅普诺夫函数中导出了自适应参数并且分析了闭环系统跟踪误差的有界性。在算法实现上，利用Matlab对文中的方法及证明的有效性进行了验证。     

三自由度并联姿态测量机构及其运动学参数最优化设计

提出了基于并联结构的三自由度姿态测量机构，将其连接到三自由度串联结构位置测量装置末端可以实现对被测物体六自由度位姿的综合测量。该测量机构克服了并联机构运动学正解的困难，得到运动平台姿态坐标参数的显式解。建立了基于全微分理论的姿态测量机构坐标参数误差模型，实现机构运动学参数的优化设计。误差因子分析使得机构运动学参数设计更为合理。     

工件装夹方式与工艺参数选择

通过对小轴车削加工多种装夹方式的比较，选择采用三爪卡盘夹一端的方式装夹。为了计算阶梯轴零件的切削变形，推导出变截面悬臂梁的弯曲变形通用表达式，应用C语言编程计算出控制切削变形误差的工件直径与长度的关系。并用工艺参数控制法减少切削变形误差，从而保证加工精度。     

用KHβ新算法研究齿轮轮齿载荷分布

提出齿轮轮齿齿向载荷分布系数KHβ新的计算方法,并用此方法对影响KHβ的各种因素进行电算分析.新算法舍弃了齿轮强度国家标准中,轮齿载荷分布沿齿向成线性的假设条件,依据轮齿的载荷-变形协调关系,把影响载荷分布系数KHβ的各类误差归结为影响轮齿齿向的初始载荷分布,最终确定在动态条件下轮齿啮合线上的稳定载荷分布,再由KHβ的定义算得轮齿的载荷分布系数KHβ.利用新算法得到的轮齿齿宽、齿轮轴长、齿轮在轴上几何位置和齿轮精度等因素对KHβ影响的关系曲线,可供齿轮强度设计人员参考.     

Precision of stereological planar area predictors

Total planar area can be estimated based on sampling by a lattice of figures (e.g. point patterns, line segments, quadrats). General formulae are provided for the approximation of mean squared errors. The approximation formulae are products of the boundary length and of a parameter that depends only on the sampling scheme. An R package is provided by the authors for the numerical computation of the mean squared error formulae. The speed of convergence of the mean squared error approximation is assessed on the basis of several simulations. Several sampling schemes are compared in view of the approximated mean squared errors.     

基于8PSK 和16PSK 调制的全双工RoF 系统研究

误码率(bit error rate, BER)是信号传输质量的重要衡量指标,为了对比分析8进制相移键控(eight hexadecimal phase shift keying, 8PSK)与16进制相移键控(sixteen hexadecimal phase shift keying, 16PSK)信号的传输性能,建立了一个全双工光载无线通信(radio over fiber, RoF)链路模型。系统的下行链路是对基于马赫增德尔调制器(Maher-Zehnder modulator, MZM)的抑制奇次边带两路信号,分别进行8PSK和16PSK调制。上行链路是取下行链路中一路未被调制的抑制奇次边带信号,作为上行基带信号的载波信号,节约系统的成本。该系统分别在不同的光信噪比(optical signal to noise ratio, OSNR)和不同传输距离条件下,仿真分析了下行链路两种调制信号的光谱图及误码率曲线,通过分析接收信号的星座图和误码特性证明:与16PSK信号相比,当OSNR 25时, 8PSK信号误码率量级可以达到10-4(lg BER-3),当传输距离为40 km时, 8PSK的误码率为4.8×10-3(lg BER=-2.32),仍然可以有效传输数据信息。且在不同OSNR和不同传输距离条件下, 8PSK的误码率均低于16PSK,因此8PSK具有更可靠的传输性能,且更适用于远距离传输。     

A Bayesian network incorporating observation error to predict phosphorus and chlorophyll a in Saginaw Bay

Empirical relationships between lake chlorophyll a and total phosphorus concentrations are widely used to develop predictive models. These models are often estimated using sample averages as implicit surrogates for unknown lake-wide means, a practice than can result in biased parameter estimation and inaccurate predictive uncertainty. We develop a Bayesian network model based on empirical chlorophyll-phosphorus relationships for Saginaw Bay, an embayment on Lake Huron. The model treats the means as unknown parameters, and includes structure to accommodate the observation error associated with estimating those means. Compared with results from an analogous simple model using sample averages, the observation error model has a lower predictive uncertainty and predicts lower chlorophyll and phosphorus concentrations under contemporary lake conditions. These models will be useful to guide pending decision-making pursuant to the 2012 Great Lakes Water Quality Agreement.     

Self-information-based weighted CUSUM charts for monitoring Poisson count data with varying sample sizes

In many applications, the Poisson count data with varying sample sizes are monitored using statistical process control charts. Among these applications, the weighted CUSUM charts are developed to deal with the effect of the varying sample sizes. However, some of them use limited information of the sample size or the count data while assigning the weights. To gain more information of the process, the self-information weight functions are developed based on both the sample size and the observed count data. Then, the weighted CUSUM charts are proposed with the self-information-based weight. Simulation studies show the self-information-based weighted CUSUM charts perform better than the benchmark methods in detecting small shifts. Moreover, the performance of proposed method with estimated parameters is investigated via simulation. Finally, an example is given to illustrate the application of the proposed weighted CUSUM charts.