Construction of a novel densitometer that utilizes a near-infrared laser system with Douglas fir (Pseudotsuga menziesii)

Abstract

A novel densitometer consisting of a continuous wave near-infrared (NIR) laser source and an avalanche photodiode module as the detector has been designed, which can rapidly and non-destructively measure the density of wood. The wood density of a small area (3.14 mm²) at the radial-transverse face was continuously estimated using the intensity of the transmitted light with the aid of the modified Lambert-Beer law. By conducting a validity evaluation with statistical coefficients, it was shown that the constructed system could obtain the sharp density profile compatible with X-ray densitometer [Root mean squared error of calibration (RMSEC) = 0.045 g cm^?3, Root mean squared error of validation (RMSEV) = 0.046 g cm^?3). It was concluded that the constructed NIR device has high performance from the viewpoint of operability, measuring time and safety.     

振动管式液体密度传感器机理的研究

以单U型振动管式液体密度传感器为例，对振动管式液体密度传感器的工作机理进行了进一步的探讨，推导了液体密度和振动管固有频率之间的函数关系方程，建立了手持僵携式密度仪表的多自由度振动模型，对传感器进行了误差分析，试验结果表明，所设计的U型振动管式液体密度传感器可以达到0．001g/cm^3的测量精度。     

MWMY型木材微密度测定仪的研制

为开拓木材密度变异性的研究，中国林科院木工所与北京科信机电技术研究所合作研制成功了ＭＷＭＹ型木材微密度测定仪。本文报道了研制中解决的主要技术问题。包括仪器选型、总体布局、光栏、测量系统标定、微密度测定方法、软件系统系统和精度考核等项。测量精度与国外类似试验装置水平接近，在光栏结构，软件设计，质量衰减系数标定和试样制作工具方面有所创新。