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Method for detecting microscopic moisture content of wood

A detection method and technology of moisture content, which is applied in the field of wood, can solve the problems of volume shrinkage, difficulty in quantifying moisture, and volume change of absolute dry wood, etc., and achieve the effect of improving accuracy

Active Publication Date: 2019-07-02
CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when the wood is lower than the fiber saturation point, the volume will shrink due to the loss of moisture, and the volume of the absolute dry wood will change during CT scanning, which will affect the accuracy
(3) Magnetic resonance imaging (MRI), the maximum resolution of the microscopic moisture content of this method is at the submillimeter level, and the microscopic moisture content of wood is calculated by using the linear relationship between the nuclear magnetic resonance free induction decay signal (FID) and moisture, but this method is in When the fiber saturation point is below, the properties of water molecules are similar to those of solids, and the adsorbed water is closely combined with wood, and the relaxation time T2 becomes shorter, making it difficult to quantify water and expensive equipment
(4) Neutron imaging technology (NI), the maximum resolution of the microscopic moisture content of this method is 30-50 μm, and the microscopic moisture content of wood is calculated by using the larger scattering and absorption cross-sections of the interaction between thermal neutrons and hydrogen nuclei of water molecules , but this method needs to pay attention to radiation safety issues
In addition, magnetic resonance imaging technology and neutron imaging technology measure the average moisture content of wood, and the microscopic moisture content is derived based on the average moisture content, and the accuracy of the microscopic moisture content is not high
Therefore, so far there is no simple, low-cost, high-precision method for measuring the microscopic moisture content of wood

Method used

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  • Method for detecting microscopic moisture content of wood

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Embodiment 1

[0059] A detection method of wood microscopic moisture content of the present invention, comprises the steps:

[0060] (1) Poplar wood is made into a 10mm (radial) × 5mm (chord) × 5mm (longitudinal) sample;

[0061] (2) After taking the weight of the sample, adopt the drying method (103 ± 2 ° C) to dry and weigh it, measure the dry volume of the sample, and calculate the average moisture content of the poplar sample to be 52.06%. Dry density is 400kg / m 3 ;

[0062] (3) Utilize following formula (1), the volume content of the moisture of calculating sample is 28.40%;

[0063] S=3W m ρ d / (3000-2ρ d ) (1)

[0064] (4) Use a scalpel to process the wide material surface (cross-section) of the dried sample, and the annual ring width is about 10 mm;

[0065] (5) Use a digital slice scanner or a stereo microscope to perform panoramic scanning and shooting of the test rod;

[0066] (6) Use Photoshop to seamlessly splice the photos to generate a full-field digital photomicrogra...

Embodiment 2

[0077] A detection method of wood microscopic moisture content of the present invention, comprises the steps:

[0078] (1) Make a 10mm (radial) × 5mm (chord) × 5mm (longitudinal) sample of fir wood;

[0079] (2) After weighing the sample weight, use the drying method (103 ± 2 ° C) to dry and weigh, measure the dry volume of the sample, and calculate the average moisture content of the fir sample to be 45.12%. The density is 300kg / m 3 ;

[0080] (3) Utilize formula (1), calculate the moisture volume content of Chinese fir sample to be 16.92%;

[0081] S=3W m ρ d / (3000-2ρ d ) (1)

[0082] (4) Utilize a scalpel to process the wide material surface (cross-section) of the dried sample, and measure the annual ring width to be about 9 mm;

[0083] (5) Use a digital slide scanner or a stereo microscope to perform panoramic scanning and shooting of the sample;

[0084] (6) Use Photoshop to seamlessly splice the photos to generate a full-field digital photomicrograph containing...

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Abstract

The invention discloses a method for detecting the microscopic moisture content of wood. The method comprises the steps that S1 a wood sample is prepared, and the average moisture content and the absolute dry density of the wood sample are measured; S2 the volume content of water in the wood sample is calculated; S3 panoramic scanning or photographing is carried out on the wood sample to generatea full-field digital microphotograph with one annual ring; the acquired microphotograph is divided into several parts equally; the cell cavity area in each picture is screened, and the porosity of thecorresponding wood part of each picture is calculated; S4 the acquired porosity data are used to fit a equation to acquire the quantitative characterization equation of the porosity in the wood annual ring; and S5 the microscopic moisture content of wood is calculated by using the volumetric content of water and the quantitative characterization equation of the porosity of the wood annual ring, so as to acquire the result of the microscopic moisture content of wood. The method provided by the invention has the advantages of wide applicability, low cost, simple and fast process steps, and canbe used to accurately measure the microscopic moisture content of wood.

Description

technical field [0001] The invention relates to the technical field of wood, in particular to a method for detecting the microscopic moisture content of wood. Background technique [0002] As a kind of biomass hygroscopic material, wood's size, density, mechanical properties and electrical properties are all affected by its moisture content. Therefore, the relationship between wood and moisture has always been a hot issue in the field of wood science research. With the emergence of new technologies and new analysis methods, the research on the relationship between wood and moisture has gradually transitioned from the macroscopic average moisture content to the microscopic moisture content distribution. Microscopic moisture content refers to the sub-millimeter moisture content from earlywood to latewood in an annual ring. Microscopic moisture content plays a vital role in wood applications. For example, in the field of wood drying, the moisture inside the wood growth ring is ...

Claims

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Application Information

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IPC IPC(8): G01N5/04G01N15/08
CPCG01N5/045G01N15/088
Inventor 郝晓峰李贤军吴义强吕建雄贺霞向瑶
Owner CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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