Measure of Departure from Point-Symmetry for the Analysis of Collapsed Square Contingency Tables

For square contingency tables with ordered categories, there may be some cases that one wants to analyze them by considering collapsed 3 × 3 tables with some adjacent categories combined in the original table. This paper considers the point-symmetry model (Wall and Lienert, 1976) for collapsed tables and proposes a measure to represent the degree of departure from point-symmetry for collapsed tables. Also it gives approximate confidence interval for the proposed measure.

Vision testing method for diameter,roundness and hardness of table tennis ball

Under the premise of fully respecting current national standard of table tennis ball,this paper presents an integrated and effective method for testing diameter,roundness and hardness of table tennis ball based on vision measurement. Firstly,camera calibration is performed by 40 mm gauge block to capture the images of table tennis ball in static and pressed state in an appropriate lighting condition. Then image binarization and extraction of image contour are carried out. The least square method is used to fit its center. Finally,the diameter,roundness and hardness are calculated. The measurement data are analyzed by using the method presented in this paper for table tennis ball with known parameter data and with unknown parameter data. Experimental results show that this method can improve measurement accuracy and provide a technical basis for the online testing and integration measurement of table tennis ball.

Modeling, identification and compensation for geometric errors of laser annealing table

In order to improve the process precision of an XY laser annealing table, a geometric error modeling, and an identification and compensation method were proposed. Based on multi-body system theory, a geometric error model for the laser annealing table was established. It supports the identification of 7 geometric errors affecting the annealing accuracy. An original identification method was presented to recognize these geometric errors. Positioning errors of 5 lines in the workspace were measured by a laser interferometer, and the 7 geometric errors were identified by the proposed algorithm. Finally, a software-based error compensation method was adopted, and a compensation mechanism was developed in a postprocessor based on LabVIEW. The identified geometric errors can be compensated by converting ideal NC codes to actual NC codes. A validation experiment has been conducted on the laser annealing table, and the results indicate that positioning errors of two validation lines decreased from ±37 μm and ±33 μm to ±5 μm and ±4.5 μm, respectively. The geometric error modeling, identification and compensation method presented in this work can be straightforwardly extended to any configurations of 2-dimensional worktable.

Mirror Mapping of Laser Interferometer Measurement System on Ultra-precise Movement Stage

The accuracy and repeatability of the laser interferometer measurement system （LIMS） are often limited by the mirror surface error that comes from the mirror surface shape and distortion. This paper describes a new method to calibrate mirror map on ultraprecise movement stage （UPMS） with nanopositioning and to make a real-time compensation for the mirror surface error by using mirror map data tables with the software algorithm. Based on the mirror map test model, the factors affecting mirror map are analyzed through geometric method on the UPMS with six digrees of freedom. Dam processing methods including spline interpolation and spline offsets are used to process the raw sampling data to build mirror map tables. The linear interpolation as compensation method to make a real-time correction on the stage mirror unflatness is adopted and the correction formulas are illuminated. In this way, the measurement accuracy of the system is obviously improved from 40 nm to 5 nm.

Laser triangulation measurement of the level in a coal silo

Laser triangulation theory was used to develop a novel contact-free method for measuring the coal level in a silo under harsh environmental conditions found in coal mines, such as the presence of dense dust, high humidity, and low illumination. A laser source and a camera were mounted at the top of the silo. The laser spot projected into the silo was imaged by the camera. The pinhole imaging principle allows the level to be found from the lateral shift of the spot image on the sensor. A pre-calibrated look-up table of the coal depth versus spot position was used to obtain the depth. The measurement accuracy depends on the step size used during pre-calibration. The actual application of a device designed according to these principles shows that it is easy to implement. The detection of the coal level in a silo at the low illumination level found in coal mines is demonstrated.

Asymmetry Index on Marginal Homogeneity for Square Contingency Tables with Ordered Categories

For square contingency tables with ordered categories, the present paper considers two kinds of weak marginal homogeneity and gives measures to represent the degree of departure from weak marginal homogeneity. The proposed measures lie between –1 to 1. When the marginal cumulative logistic model or the extended marginal homogeneity model holds, the proposed measures represent the degree of departure from marginal homogeneity. Using these measures, three kinds of unaided distance vision data are analyzed.

Design, Development and Geometric Error Analysis of an Aerostatic Rotary Table

Rotary tables are equipments in precision machinery applied in five-axis Machine Tools and CMM （Coordinate Measuring Machines）, offering rotational （C-axis） and tilting motion （A-axis）, allowing the obtaining of several configurations for manufacturing or inspection of parts with complex geometries. The demand for high accuracy, high efficiency and fewer errors in the positioning of the part in precision machines increases every day, thus ensuring their high confidence and the use of aerostatic bearings enable constructive innovations to the equipment. In this context, this work presents the mechanical design, the development and error analysis of a prototype of an aerostatic rotary table. This study emphasizes the analysis of a prototype that uses the air as a working principle for reducing friction between moving parts, increasing the mechanical efficiency, and its influence of motion error is also discussed based on the experimental results. For the geometrical errors analysis, experimental tests were realized in laboratory using a DBB （Double Ballbar）. The tests are performed with only one axis moving, observing the behavior of the system for different feedrate at the C-axis.

支架固定馆藏人物俑文物振动台试验研究

为研究博物馆最常用的支架固定措施固定馆藏人物俑文物的抗震有效性,开展了两类典型体型易损、材质易损人物俑文物复制品‐支架固定措施抗震系统足尺振动台试验研究。获得了人物俑在不同工况下的地震响应及人物俑与支架间的相互作用,探讨人物俑关键体型参数、金属支架卡固位置、支架尺寸、固定措施与人物俑间安装缝隙对该类文物运动状态的影响,评估了支架固定措施的抗震有效性并提出了合理建议,为兼顾安全性及最小干预原则的支架固定人物俑文物的优化设计提供必要依据。研究结果表明:浮放人物俑均发生倾覆,具有极大震损风险;采用支架固定后可有效降低人物俑的摇摆响应,随着人物俑复制品的质心高度与底座宽度比值增加以及其质量增大,较小尺寸支架发生明显塑性变形甚至根部断裂,导致人物俑倾覆并损坏;随着支架尺寸的增加,其对文物固定效果的提高作用有限,基于文物保护最小干预原则,综合考虑文物的抗震安全及艺术展示效果,优化支架尺寸;支架固定人物俑肩部时,人物俑摇摆响应得到一定控制,但随着支架固定位置的提高,人物俑滑移响应愈加明显;当支架与人物俑相互作用时,人物俑表面出现明显损伤,在两者缝隙填充硅胶垫,人物俑的摇摆响应和滑移响应分别降低近40%和50%,支架根部应变下降近40%,人物俑与支架接触处应变下降近60%,有效提高了支架固定措施的抗震有效性。

支架固定馆藏人物俑文物的抗震优化设计研究

为优化支架固定馆藏人物俑文物的抗震效果,选取不同尺寸和体态的典型地震易损人物俑文物复制品(武士俑和唐三彩人物俑),开展文物复制品-优化组合措施(支架和卡固件)抗震系统振动台试验,获得影响文物复制品运动状态的关键优化参数、文物复制品与支架相互作用规律,并检验组合措施对较大体积人物俑文物的抗震固定效果。建立文物复制品-组合措施相互作用系统数值分析模型,通过参数分析,获得支架与文物间安装缝隙、在安装缝隙内填充不同种类隔震垫对文物动力响应的影响、文物复制品与固定措施相互作用规律及采用独立支架/组合措施有效固定人物俑的最小支架尺寸,为兼顾安全性及最小干预原则的固定措施优化设计提供必要依据。结果表明:相比独立支架,组合措施能够有效降低人物俑文物动力响应,有效提高固定效果;为保证人物俑文物安全,建议支架与文物间安装缝隙不大于5 mm;在缝隙中填充橡胶垫及硅胶垫可使文物与支架间相互作用力降低50%~75%,有效防止文物局部损伤;当人物俑文物体型超过一定限值,独立支架不再适用,建议选择支架和随形卡固件组合措施。

转台负载工况下角位置误差补偿方法研究

负载会影响转台回转轴的运动状态,进一步影响转台角位置误差的大小。通过分析负载工况下转台角位置误差傅里叶阶次的变化情况,提出一种基于谐波补偿的误差补偿方法。首先,分析负载对转台回转轴的影响,建立回转轴误差运动与角位置误差之间的数学模型,并进行数值仿真;其次,通过负载变化影响回转轴误差运动的大小,获取转台不同负载下的自校准曲线,采用傅里叶法分析对负载变化敏感的傅里叶阶次;最后,选取对负载变化敏感的傅里叶阶次拟合谐波补偿函数对转台角位置误差进行补偿。误差补偿后转台在不同负载工况下的角位置误差最大为±0.25″,与补偿后空载工况下角位置误差相差±0.03″,有效减小了负载对转台角位置误差的影响。

新型光纤加加速度传感器在振动台试验中的应用

目前在结构振动和地震动测量中,主要关注位移、速度和加速度响应,而忽略了加速度的微分(即加加速度)。结构的加加速度响应与舒适度和结构损伤演化密切相关,已经开始受到工程技术人员的重视。在土木工程领域,加加速度传感器尚未被成熟地应用于工程项目或结构试验中。介绍了一种基于微分Mach-Zehnder干涉仪的新型光纤加加速度传感器,可直接测量结构的加加速度响应。将该传感器直接布置于振动台台面进行了0.1~100.0 Hz的正弦扫频校准振动测试,试验结果证明该传感器具有良好的工作性能,由采集的加加速度积分获取的加速度时程与振动输入的相关系数达到了0.976。同时,将该加加速度传感器应用于某超高层模型结构的振动台试验,采集超高层结构加加速度时程响应。试验结果表明该超高层结构顶部的加加速度放大效果超过了6倍,鞭梢效应显著。试验中采集的加加速度响应也为进一步开展该抗震新参量的研究提供了数据支撑。该新型光纤加加速度测量仪器在地震工程领域具有广阔的应用前景。

Integral precession calibration method of PIGA on linear vibration table

Linear vibration table can provide harmonic accelerations to excite the nonlinear error terms of Pendulous Integrating Gyro Accelerometer(PIGA).Integral precession calibration method is proposed to calibrate PIGA on a linear vibration table in this paper.Based on the precise expressions of PIGA’s inputs,the error calibration model of PIGA is established.Precession angular velocity errors of PIGA are suppressed by integer periodic precession and the errors caused by non-integer periods vibrating are compensated.The complete calibration process,including planning,preparation,PIGA testing,and coefficient identification,is designed to optimize the test operations and evaluate the calibration results.The effect of the main errors on calibration uncertainty is analyzed and the relative sensitivity function is proposed to further optimize the test positions.Experimental and simulation results verify that the proposed 10-position calibration method can improve calibration uncertainties after compensating for the related errors.The order of calibration uncertainties of the second-and third-order coefficients are decreased to 10^(-8)(rad.s^(-1))/g^(2)and 10^(-8)(rad.s^(-1))/g3,respectively.Compared with the other two classical calibration methods,the calibration uncertainties of PIGA’s nonlinear error coefficients can be effectively reduced and the proportional residual errors are decreased less than 3×10-6(rad.s^(-1))/g by using the proposed calibration method.

中国新能源产业关联测度及其效应分析

新发展阶段背景下能源消费转型的迫切性日益增强,以新能源为契机的能源结构转型是中国式现代化的重要内容。为了深入了解中国新能源产业现状及其对国民经济影响,设计并编制2015年、2017年、2018年和2020年新能源产业投入产出表。为了进一步分析新能源产业的关联效应,探究产业间的内部关联机制,运用结构分解法测算了新能源产业部门的内生乘数效应、回馈效应和外向溢出效应。研究发现:1)新能源产业规模发展整体呈上升趋势。新能源产业的增加值率处于较高水平,但整体上新能源产业部门对国民经济的影响未达到社会平均影响力,对国民经济发展的后项推动作用尚不明显。2)新能源产业的自身关联性不强,所有产业部门与新能源产业有后向直接关联关系,且在考虑间接消耗下,制造业、建筑业仍然是新能源产业的密切后向完全关联产业。3)通过静态分解效应发现,新能源产业部门的内生乘数效应、回馈效应和外向溢出效应均低于全社会平均水平,就产业部门自身来看,外向溢出效应是其部门产出增长的主要来源,但2020年有所下降并与内生乘数效应贡献持平;进一步动态分解效应发现,在观察期内的新能源产业部门产出增长的主要来源,经历了由其他部门最终需求刺激过渡到自身部门最终需求刺激,再到新一轮其他部门最终需求刺激的动态发展过程。总体上看,新能源产业与其他产业的关联程度动态增强趋势。新能源产业发展状态较为良好,处于上升蓬勃发展阶段。基于研究结果,提出以下建议:1)加大技术研发投入和推广普及新能源应用,增强新能源产业在国民经济部门中的以影响力为表征的前向牵引作用;2)合理规划和布局新能源产业集群发展,并连通其与制造业、建筑业等密切关联产业部门的生产交流通道,实现产业协同发展;3)加强新能源产业建设和政策引导扶持,以增强新能源产业感应能力优势,为实现中国式现代化助力。

转台运动误差分离与角度优化技术研究

为了解决测量转台运动误差时存在的多种误差耦合问题,提出了一种基于多点法的运动误差分离方法。首先,通过分析转台在回转过程中多自由度误差的运动特性,提出了一种端面四点误差分离方法,在分离出测量盘下表面的平面度误差的同时,可完成倾斜误差和轴向误差的解耦。然后,建立了该方法的误差传递函数,采用麻雀算法(SSA)进行优化,寻找不同阶次下受谐波抑制影响最小的最优布置角,提高了误差解耦精度。最后,通过仿真与实验的方式对该方法进行验证。仿真结果表明,端面四点误差分离方法对轴向、倾斜误差的分离精度(相对误差)分别为1.934%和9.177%。实验结果表明,分离的运动误差与转台标定误差相符合,验证了该方法能够精确获得转台运动误差。

基于激光测长的影像法线纹检测装置

基于激光测长的影像法技术是提高线纹测量精度,实现线纹快速直接测量的有效途径。针对线纹尺刻线的磨损、缺损以及传统提取刻线影像边缘的影像测量技术不适用等问题,本文提出了一种步进电机驱动加载影像测量机构的浮动工作台定位,并采用射流技术,利用减速器和丝杠传动的方法,实现机构的微调功能。同时,为提高检测装置的精度,对激光测长的定位误差进行了线性补偿,使检测装置精度整体提高了50%以上。

提升儿童青少年照明产品近视防控合格评定影响的对策分析

普通教室照明产品和读写作业台灯是儿童青少年学习用品,在学校教室学习和家庭学习中均起到了重要的作用,因此改善学校和家庭的视觉照明环境是儿童青少年近视防控的有效措施。通过对在儿童青少年近视防控照明产品当前主要的质量安全风险和市场准入政策的现状进行阐述,对目前进行儿童青少年近视防控照明产品的质量监管情况和质量保障措施进行分析,为提升儿童青少年近视防控照明产品性能合格评定影响力的对策提供了切实可行的对策和建议。

地震时饱和砂土地基中管线上浮机理及抗震措施试验研究

采用模型试验技术 ,证实了地震中由于地基的液化使管线上方的填土抗剪强度降低 ,浅埋在饱和砂土下的管线“上浮”到地表 ,最终导致管线破坏 ;通过类比试验的方法 ,着重研究了地震时砂土地基的加速度反应、振动孔隙水压力的产生消散过程、管线的上浮机理、多种排水 (或加固 )措施的抗震效果 ,为进一步的深入研究。

基于一体化结构的全力测试平台的研制及其动态性能研究

介绍了一种全力信息测试平台的系统结构 ,标定与解耦的原理。进而提出了一种基于模糊推理的分区解耦的方法 ,显著降低了大面积测试台对材料刚度的要求 ,减小了耦合误差。最后集中探讨了全力测试平台的动态特性和补偿问题。

时栅数控转台空间回转位置预测方法研究

时栅传感器利用时空变换技术将空域信息变换到时域,以时间测量空间位移。为了研制高精度时栅数控转台,减少动态位置反馈误差,提出了一种回转位置预测测量新方法,利用时空变换技术将时域信息返回到空域。利用时间序列理论对时栅测量值进行建模,从而预测出数控转台未来一段时间内的位置值,并利用当前测量值对前一次的预测误差进行实时修正。介绍了测量数据建模方法和预测系数估计算法。为了验证位置预测方法的有效性,设计了一套动态实验系统。实践证明,数控转台的角位移预测误差为±2″,实现了精密位置预测。

铀矿找矿中氡的迁移机制探讨

本文主要介绍铀矿勘查中氡的迁移机制。通过对自行设计的氡迁移模型长达３个月的试验研究（与理论计算值进行比较）和选择一条经深部揭露的地段（多个矿体埋深为已知）进行地表多种氡法测量，证明只用扩散理论是不可能完满解释为什么氡法能够探测到深达二三百米的铀矿体。从广义角度提出了氡的迁移机制主要是“接力传递”作用。