基于多 CNN 的分块镜 piston 和 tip-tilt 误差同步检测方法研究

绝大多数大型望远镜采用分块镜的设计方案,为了获得优质的成像效果,需要控制分块望远镜系统的 piston 和 tip-tilt 误差。 神经网络误差检测方法相较于传统的检测方法具有一定优势,但存在仅检测单一类型误差的局限性。 本文提出一种基 于卷积神经网络的 piston 和 tip-tilt 误差同步检测方法,通过在出瞳面设置具有离散孔的光阑,引发分段镜反射的子波发生干涉 -衍射现象,构建包含丰富 piston 和 tip-tilt 误差信息的数据集。 通过粗测网络和精测网络级联,满足大范围和高精度同步检测 的需求。 结果表明,该方法实现了对输入光源相干长度内纳米级的 piston 误差检测,并对 10 μrad 范围内的 tip-tilt 误差实现了 亚微弧度检测;对 40 dB 的 CCD 噪声表现出良好的抗干扰性,对面形误差的允差为 0. 05λ0RMS(λ0 = 600 nm),同时对六子镜系 统具有可扩展性。 本文方法光路简单,操作便利,具有实际意义。     

手持式激光测距仪"测距标准偏差综合评定"的扩展不确定度

在确定的函数关系(数学模型)中,因变量(输出量)随自变量(输入量)的变化规律完全由数学逻辑所确定,自变量到因变量的传递系数(灵敏系数)也可由因变量的标准差和自变量的标准差之比所决定,而与自变量的来历(测量的或者给定的)没有关系[1].本文根据这一基本原理,采用模拟自变量随机变化的方法,成功计算了手持式激光测距仪的测距固定偏差和比例偏差系数的测量不确定度,从而计算出测距标准差综合评定的扩展不确定度,同时解决了复杂的数学模型中多个输入量到输出量的灵敏系数和输出量的不确定度的计算问题.     

Application of ATR-FTIR for a rapid and simultaneous determination of sugars and organic acids in apricot fruit

A simple, fast and accurate Fourier transform mid-infrared spectroscopy method was developed for simultaneously determining sugar and organic acid contents in apricot fruit slurries using the attenuated total reflectance. The potential of this method coupled with chemometric techniques based on partial least squares was assessed by comparison with currently used enzymatic determination of sucrose, glucose, fructose, malic acid and citric acid. Fruits of eight contrasted cultivars harvested at different ripening stages were used in this study and randomly divided in a calibration set (505 apricots) and in a validation set (252 apricots). The most suitable region was found in the range between 1500 and 900 cm⁻¹. Good prediction performances were obtained (R² ? 0.74 and RMSEP ? 18%). Results concerning the prediction of other quality traits such as firmness, skin colour, ethylene production, soluble solids content and titratable acidity were discussed.     

对《称重传感器》国标5.2.1条款

通过对《称重传感器》国标仔细研读和分析,在标准规定的三段最大允许误差限基础上,提出了五段式最大允许误差限和分段点必检的观点,从而满足了5.2.1提出的全量程、全分度的检定要求。     

多工位跳步模送料机械手手指参数的确定

介绍了多工位跳步模送料机械手手指参数的计算方法及分析结果，并编制了计算机分析计算程序软件，为机械手的设计提供了方便有利的工具。     

流体阻力摩擦系数关联式演变的探讨

在通用的流体阻力摩擦系数计算公式的基础上进行推演变形,得到两个不同形式的计算表达式。并运用Excel的图表向导功能对这两个表达式进行误差校验。分析数据表明,这两个新的公式被用于计算莫迪图中十条不同相对粗糙度曲线的摩擦系数时,所产生误差的平均水平均能满足工程计算的精度要求。文章立意中的对通用公式进行推演变形的必要性在理论上是成立的。     

Effects of aluminium content on the molecular structure and properties of polyaluminocarbosilane for SiC fibre fabrication

Polyaluminocarbosilane (PACS) is an important precursor for silicon carbide (SiC) fibres and ceramics. Much work has focused on the sintering effect of elemental Al, and it was found to increase density and inhibit grain growth during the pyrolysis of the SiC_xO_y phase at high temperatures. In addition to the sintering effect, Al may also affect the detailed molecular structure and the related properties of the precursor. In this work, PACS with different Al contents are prepared by a high-pressure method. The structural forms of the component elements are quantitatively determined by ¹H NMR, ²⁹Si NMR, DEPT, ²⁷Al MAS NMR and elemental analysis, and a method of determining the relative branching degree of PACS is proposed. It is found that increasing the Al content in the precursor leads to an increase in the weight percentage of the SiC₃O, CH₂ and CH groups, while the content of the SiC₄ groups remains almost unchanged, which consequently causes a rise in the relative branching degree of the molecular structure. The rheological properties of the precursors are investigated on a monofilament spinning device. It is found that the apparent viscosity rises, and the spinnability of the precursor weakens, with increasing Al content, while the non-Newtonian index becomes larger, indicating a decrease in the pseudo-plasticity of the precursor. In addition, the ceramic yield becomes higher, which is definitely correlated to the more branched and ring molecular structures.     

相变材料相变点温度热物性的测试及误差分析

固-液相变过程中移动的相界面曲线与两相热物性如比热、密度、导热系数以及相变潜热是密切相关的。本文提出通过测定相界面的移动速率来确定相变材料固-液相变温度点导热系数等多个热物性参数的方法,并设计了相应的测试装置。对测试系统的测量误差进行了定量分析,发现采用数值计算与实验相结合的方法测试的系统误差不超过3％。利用研制的测试系统对几种材料的导热系数和热扩散系数进行了测定,得到了满意的结果,表明本文所提出的测试方法是可信的。     

不同熔盐制造离子扩散型抗菌陶瓷中银离子的扩散

本文对以AgNO3:KNO3和AgNO3:NaNO3熔盐制造抗菌陶瓷中的银在釉中的扩散进行了研究。用电子探针对银的分布进行了分析,给出了用误差函数拟合描述扩散过程的方法,实验发现对同一种釉使用AgNO3:KNO3时银的扩散要比 AgNO3:NaNO3快得多,两种情况下银的表现扩散系数分别为1．6×10-11L-1．3×10-10cm2S-1。     

低温空气源热泵实验台

实验台由热泵机组和室内外环境模拟系统组成。基于系统误差分析的基本原理,合理选择测量仪表。分析得知,温差对测量精度的影响大于流量的影响。重复测试的结果表明,制热量和制热COP的总误差分别为3.65%和3.79%,能满足试验精度要求。