Zhang S.Y.Zhang S.Y.Zhang S.Y.

S1226S1226

Hou Z.-Q., PDFand

Lin J. HuResearch Scientist

Hou Z.Hou Z.--Q., PDFQ., PDFandand

Lin J. HuLin J. HuResearch ScientistResearch Scientist

S.Y. (Tony) Zhang, Group Leader

Resource

S.Y. (Tony) Zhang, S.Y. (Tony) Zhang, Group LeaderGroup Leader

ResourceResource

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BackgroundBackgroundBackground

• Affect wood properties and end uses• Little work done• Affect wood properties and end uses• Little work done

Standing Tree DensityStanding Tree Density

• Lumber• Composite wood panels• Lumber• Composite wood panels

X-ray Scanning Technique to Determine DensityX-ray Scanning Technique to Determine Density

• Images of inside of logs• Images of inside of logsComputer Tomography (CT) X-Ray Scanning TechniqueComputer Tomography (CT) X-Ray Scanning Technique

ObjectiveObjectiveObjective

Examine the feasibility of determining standing tree

density using X-ray scanning technique

Examine the feasibility of determining standing tree

density using X-ray scanning technique

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MaterialsMaterialsMaterials

Fresh logs

from beech and

baslsam fir

Fresh logs

from beech and

baslsam fir

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Experimental ProcedureExperimental ProcedureExperimental Procedure

1) Cut butt logs from standing trees and sealed logs in plastic bags

2) CT X-ray scanning using Siemens’s SOMATOM Plus 4 Volume Zoom computer tomography (CT) system for multi-slice spiral scanning

3) Destructive determination of log density using 51 mm (2 in.) discs cut from the log specimens

1) Cut butt logs from standing trees and sealed logs in plastic bags

2) CT X-ray scanning using Siemens’s SOMATOM Plus 4 Volume Zoom computer tomography (CT) system for multi-slice spiral scanning

3) Destructive determination of log density using 51 mm (2 in.) discs cut from the log specimens

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Experimental ProcedureExperimental ProcedureExperimental Procedure

4) Determination of moistrue contents of the discs using oven dry method

5) Analysis of X-ray attenuations (CT numbers)mesured by CT scanner using Matlab program

6) Development of prediction equations for fresh log density from CT number by linear regulation analysis

4) Determination of moistrue contents of the discs using oven dry method

5) Analysis of X-ray attenuations (CT numbers)mesured by CT scanner using Matlab program

6) Development of prediction equations for fresh log density from CT number by linear regulation analysis

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Siemens's SOMATOM Plus 4 Volume Zoom CT X-RaySystem

Siemens's SOMATOM Plus 4 Volume Zoom CT X-RaySystem

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Parameters for CT X-Ray Scanning Log SpecimensParameters for CT XParameters for CT X--Ray Ray Scanning Log SpecimensScanning Log Specimens

• X-ray tube kilovoltage: 140 kVp• X-ray tube current: 178 mA• Volume element of the section that was

scanned (voxel) of 0.78 × 0.78 × 10.00 mm3

• Interval of reconstructed sliced images along the longitudinal direction of the log: 51 mm (two inches)

• X-ray tube kilovoltage: 140 kVp• X-ray tube current: 178 mA• Volume element of the section that was

scanned (voxel) of 0.78 × 0.78 × 10.00 mm3

• Interval of reconstructed sliced images along the longitudinal direction of the log: 51 mm (two inches)

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Image of Cross-Section of Log SpecimenImage of CrossImage of Cross--Section of Section of Log SpecimenLog Specimen

Beech Beech FirFir

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Relationship between fresh log density and X-ray attenuation

Relationship between fresh log Relationship between fresh log density and Xdensity and X--ray attenuation ray attenuation

Fresh beech log

y = 0.86x + 168.34R2 = 0.90

900.0

950.0

1000.0

1050.0

1100.0

900 950 1000 1050 1100

Average CT number of the corresponding cross-section image

Mea

sure

d de

nsity

of 5

.1 c

m

thic

k di

sc (k

g/m

^3)

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Fresh fir-log

y = 0.55x + 310.55R2 = 0.40

600.0

620.0

640.0

660.0

680.0

700.0

720.0

740.0

760.0

780.0

800.0

600 620 640 660 680 700 720 740 760 780 800

Average CT number of the coresponding cross-section image

Mea

sure

d de

nsity

of 5

.1cm

th

ick

disc

(kg/

m^3

)

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Relationship between fresh log density and X-ray attenuation

Relationship between fresh log Relationship between fresh log density and Xdensity and X--ray attenuation ray attenuation

Discrepancy of predicted density from measured density (%)Discrepancy of predicted density Discrepancy of predicted density from measured density (%)from measured density (%)

-12.28.02.5Fresh fir

-1.52.20.7Fresh beech

Minimum Maximum Absolute Mean

Log species

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Factors Affecting the AccuracyFactors Affecting the Factors Affecting the AccuracyAccuracy

Uniformity of Density DistributionUniformity of Density Distribution

Moisture Content (%)Moisture Content (%)

6.77.2107.5Fresh fir2.01.468.5Fresh beech

Coefficient Variation (%)

Standard Deviation

AverageLog species

16.94.3Fresh fir log

9.62.6Fresh beech log

RadialLongitudinal

Coefficient Variance (%)Log species

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Longitudinal Density Distribution Longitudinal Density Distribution Longitudinal Density Distribution

Fresh beech log

950

1000

1050

1100

1 6 11 16 21 26 31 36 41 46

Longitudinal position from big end

Mea

sure

d de

nsity

(kg/

m3 )

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Fresh fir log

600

650

700

750

800

850

1 6 11 16 21 26 31 36 41 46

Longitudinal position from big end

Mea

sure

d de

nsity

(kg/

m3 )

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Longitudinal Density Distribution Longitudinal Density Distribution Longitudinal Density Distribution

Prediction of Radial Density Distribution Along Profile-1 of a Cross-Section of

Fresh Beech Log Specimen

Prediction of Radial Density Distribution Prediction of Radial Density Distribution Along ProfileAlong Profile--1 of a Cross1 of a Cross--Section ofSection of

Fresh Beech Log SpecimenFresh Beech Log Specimen

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Across-Pith Radial Density Distribution Along Profile-1 of a Fresh-Beech

Log Cross-Section

AcrossAcross--Pith Radial Density Distribution Pith Radial Density Distribution Along ProfileAlong Profile--1 of a Fresh1 of a Fresh--BeechBeech

Log CrossLog Cross--SectionSection

800

850

900

950

1000

1050

1100

1150

1200

1250

1300

1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201

Across-pith radial position from the outest shell

Pred

icte

d de

nsity

(kg/

m̂3)

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Prediction of Radial Density Distribution Along Profile-1 of a Cross-Section of

Fresh Fir Log Specimen

Prediction of Radial Density Distribution Prediction of Radial Density Distribution Along ProfileAlong Profile--1 of a Cross1 of a Cross--Section ofSection of

Fresh Fir Log SpecimenFresh Fir Log Specimen

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Across-Pith Radial Density Distribution Along Profile-1 of a Fresh-Fir

Log Cross-Section

AcrossAcross--Pith Radial Density Distribution Pith Radial Density Distribution Along ProfileAlong Profile--1 of a Fresh1 of a Fresh--FirFir

Log CrossLog Cross--SectionSection

300

400

500

600

700

800

900

1000

1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221

Across-pith radial position from the outest shell

Pred

icte

d de

nsity

(kg/

m^3

)

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Conclusion & RecommendationConclusion & Conclusion & RecommendationRecommendation

1) X-ray scanning is a promising technique to non-destructively determine fresh log density

2) Portable X-ray device is needed for standing tree density determination

3) Further research is needed to improve the accuracy and effectiveness of its application to various species of standing trees

1) X-ray scanning is a promising technique to non-destructively determine fresh log density

2) Portable X-ray device is needed for standing tree density determination

3) Further research is needed to improve the accuracy and effectiveness of its application to various species of standing trees

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