应用BP神经网络校正铂电阻温度传感器非线性的方法

本文应用BP神经网络算法对铂电阻温度传感器进行非线性校正,给出了BP神经网络的结构和训练权值的方法,在训练网络时对输入量进行了归一化处理。并应用此训练的网络对一实际的温度采集系统进行校正。此方法实现简单,大大方便了铂电阻温度传感器在温度测量中的应用。     

The Benefits of Fixed Item Parameter Calibration for Parameter Accuracy in Small Sample Situations in Large‐Scale Assessments

Large‐scale assessments such as the Programme for International Student Assessment (PISA) have field trials where new survey features are tested for utility in the main survey. Because of resource constraints, there is a trade‐off between how much of the sample can be used to test new survey features and how much can be used for the initial item response theory (IRT) scaling. Utilizing real assessment data of the PISA 2015 Science assessment, this article demonstrates that using fixed item parameter calibration (FIPC) in the field trial yields stable item parameter estimates in the initial IRT scaling for samples as small as n = 250 per country. Moreover, the results indicate that for the recovery of the county‐specific latent trait distributions, the estimates of the trend items (i.e., the information introduced into the calibration) are crucial. Thus, concerning the country‐level sample size of n = 1,950 currently used in the PISA field trial, FIPC is useful for increasing the number of survey features that can be examined during the field trial without the need to increase the total sample size. This enables international large‐scale assessments such as PISA to keep up with state‐of‐the‐art developments regarding assessment frameworks, psychometric models, and delivery platform capabilities.     

亚像素级激光光条提取及其激光平面标定应用(英文)

为了标定激光平面以实现三维形貌测量,提出一种亚像素级精度激光光条提取算法.该算法包括两侧边检测和中心线提取2个部分.首先,利用基于主成分角的渐进概率霍夫变换检测2条侧边并依赖该两侧边的距离获取光条宽度;然后,应用二维泰勒展式提取具有亚像素级精度的光条中心线并依据重建的三维坐标标定激光平面.实验结果表明,所提算法光条中心提取速度较快,平均约为78 ms/帧,光条平面共面误差较低,限制在0.3 mm以内.因而所提算法能够满足提取光条的两侧边和中心线的需要,且快速可靠、精度高和抗干扰能力强.     

基于HALCON软件的单摄像机标定方法研究

摄像机标定是计算机视觉技术的重要研究内容,本文基于HALCON软件对单摄像机的标定方法进行了研究.文中首先对摄像机模型作了简要的介绍,然后详细阐述了HALCON软件中关于摄像机标定的一些函数,最后给出了示例程序.     

Researchers Propose AFM-based Virtual Nano-hand for Stable Nanomanipulation

<正>The atomic force microscopy(AFM)is a promising tool for manipulating nano-objects to fabricate nano-structures or nano-devices.However,there are still some challenges facing the development of an AFM-based robotic nanomanipulation system,such as the     

不同水分条件下夏玉米生育状况的分析比较

通过对不同水分条件下,夏玉米的干物质积累及产量构成因素、水分校正因子、叶比表面积、同化物在不同器官的分配等不同侧面的分析比较,提出了如何在有限的水资源条件下最大限度提高夏玉米产量。     

基于L-M算法的机械臂三维超声图像标定方法

为了在三维超声成像中获得更多、更详细的位置信息,得到更准确的定位精度,采用机械臂夹持超声探头并利用L-M算法进行超声图像标定。标定过程中,通过将N线模板放在水槽中,从而得到更准确的定位装置接收器与超声图像之间的位置转换关系,利用六自由度机械臂控制超声探头水平移动扫描模板以获取超声图像,并利用区域提取与缺陷分割技术获得图像中的像素坐标,以及扫描点在模板中对应的实际坐标,最后运用L-M算法进行标定计算,获得所需的标定转换矩阵。实验结果证明,该方法简单易行且效率较高,提高了标定精度,可满足实际检测精度需求,避免了手动扫描误差,为后续三维重建奠定了基础。     

新型微波测量线CATS的设计与实现

介绍了自行研制的基于常规测量线测试系统的新型微波测量线CATS(ComputerAidedTestSystem),着重阐述了系统的工作原理、功能、特点和CATS组件的硬件、软件设计方案。在CATS的基础上,配置相应的微波参数测量软件可实现多种参数的自动测量。该系统对微波实验教学和实际应用均具有较高的实用价值。     

Students’ intentions towards studying science at upper-secondary school: the differential effects of under-confidence and over-confidence

Understanding students’ intentions to study science at upper-secondary school, at university, and to follow science careers continues as a central concern for international science education. Prior research has highlighted that students’ science confidence has been associated with their intentions to study science further, although under-confidence and over-confidence (lower or higher confidence than expected, given someone’s attainment) have not been considered in detail. Accordingly, this study explored whether under-confident, accurately evaluating, and over-confident students expressed different attitudes towards their science education, and explored how under-confidence and over-confidence might influence students’ science intentions. The questionnaire responses of 1523 students from 12 secondary schools in England were considered through analysis of variance and predictive modelling. Under-confident students expressed consistently lower science attitudes than accurately evaluating and over-confident students, despite reporting the same science grades as accurately evaluating students. Students’ intentions to study science were predicted by different factors in different ways, depending on whether the students were under-confident, accurate, or over-confident. For accurately evaluating and over-confident students, science intentions were predicted by their self-efficacy beliefs (their confidence in their expected future science attainment). For under-confident students, science intentions were predicted by their self-concept beliefs (their confidence in currently ‘doing well’ or ‘being good’ at science). Many other differences were also apparent. Fundamentally, under-confidence may be detrimental not simply through associating with lower attitudes, but through students considering their choices in different ways. Under-confidence may accordingly require attention to help ensure that students’ future choices are not unnecessarily constrained.     

校正变换矩阵法用于多组分染色剂的同时测定研究

将校正变换矩阵法(CTM)与可见分光光度法相结合,对藏红、荧光桃红、曙红三种染色剂进行不经分离同时测定.使用交叉验证法选择主因子数建立了校正模型,预测结果令人满意.在相同条件下,将校正变换矩阵法与偏最小二乘(PLS)回归的结果进行了比较,结果表明两种方法的预测准确性没有显著性差异.