| 1. |
- Hedin, Jonas, et al.
(författare)
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Using radio telemetry to study dispersal of the beetle Osmoderma eremita, an inhabitant of tree hollows
- 2002
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Ingår i: Computers and Electronics in Agriculture. - 0168-1699. ; 35:2-3, s. 171-180
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Konferensbidrag (refereegranskat)abstract
- This paper describes a radio-tracking study of Osmoderma eremita, a large Scarabaeid beetle, living in hollow trees. The study seems to be the first in which radio telemetry has been used with a flying insect in the field. Some 74 adult beetles were tagged with radio transmitters weighing 0.48-0.52 1, and having a nominal battery life of 12-20 days. Transmissions were detected at ranges of up to 330 m, with 50-100 in obtained routinely. Contact was lost with 71% of the females and 20% of the males before the end of the nominal lifetime of the transmitter's battery, probably because the transmitter ceased to function. Radio telemetry proved effective in this study and gave dispersal ranges and rates that were consistent with those from a concurrent mark-recapture study in the same area. However, further development of the technique is desirable. The antennas need to be more flexible and the transmitters smaller and lighter. Nevertheless, even the current form of the technique may be suitable for studying short-range dispersal in other large-bodied flight-capable insects.
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| 2. |
- Johansson, J., et al.
(författare)
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Predicting moisture content and density of Scots pine by microwave scanning of sawn timber
- 2003
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Ingår i: Computers and Electronics in Agriculture. - 0168-1699 .- 1872-7107. ; 41:1-3, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- Non-destructive testing of wood for prediction of strength is significantly influenced by wood density and moisture content. A sensor capable of measuring both density and moisture content would be a good tool to aid in predicting the strength of sawn timber. This study was carried out to investigate the possibility of calibrating a prediction model for the moisture content and density of Scots pine (Pinus sylvestris) using microwave sensors. The material was initially at green moisture content, and thereafter dried in several steps to zero moisture content. At each step all the samples were weighted, scanned with a microwave camera (Satimo 9.4 GHz) and CT scanned with a medical CT scanner (Siemens Somatom AR.T.). The output variables from the microwave camera were used as predictors, and CT images correlated with known moisture content were used as response variables. Multivariate models to predict moisture content and density were calibrated using partial least squares (PLS) regression. The result shows that it is possible to predict both moisture content and density with very high accuracy using microwave sensors
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| 3. |
- Nyström, Jan
(författare)
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Automatic measurement of fiber orientation in softwoods by using the tracheid effect
- 2003
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Ingår i: Computers and Electronics in Agriculture. - 0168-1699 .- 1872-7107. ; 41:1-3, s. 91-99
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Tidskriftsartikel (refereegranskat)abstract
- Spiraled grain commonly occurs in softwood trees. Instead of running parallel to the pith, the grain runs spirally around the trunk like a helix. Since wood is an orthotropic material with higher shrinkage perpendicular to than parallel to the fibers, the log will twist when dried, and so will a plank or board cut from it. Several investigations have shown that the magnitude of twist in sawn wood is highly correlated to the fiber orientation, so by measuring the fiber orientation on green lumber, the risk of warp after drying can be indicated. Fiber orientation is also interesting for other purposes, for example stress grading and research applications. We concern the tracheid effect, which utilizes the light conducting properties of the softwood tracheids to measure fiber orientation. A small circular laser beam was projected onto the wood surface. The light was transmitted in the wood and scattered back to form an elliptical shape extended in the direction of the fibers. The ellipse of light was registered with a CMOS camera, and the orientation of the ellipse's major axis was calculated. This method has a correlation coefficient of 0.99996 to manually aligned fiber orientation, and repeated measurements show a standard deviation of 0.2°. Calculation time for one 64×64 pixel image was 67 μs, which must be regarded as useful for industrial applications.
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| 4. |
- Oja, Johan, et al.
(författare)
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Automatic grading of Scots pine (Pinus sylvestris L.) sawlogs using an industrial X-ray log scanner
- 2003
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Ingår i: Computers and Electronics in Agriculture. - 0168-1699 .- 1872-7107. ; 41:1-3, s. 63-75
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Tidskriftsartikel (refereegranskat)abstract
- The successful running of a sawmill is dependent on its ability to achieve the highest possible value recovery from the sawlogs, i.e. to optimize the use of the raw material. Such optimization requires information about the properties of every log. One method of measuring these properties is to use an X-ray log scanner. The objective was to determine the accuracy when grading Scots pine (Pinus sylvestris L.) sawlogs using an industrial scanner known as the X-ray LogScanner. The study was based on 150 Scots pine sawlogs from a sawmill in northern Sweden. All logs were scanned in the LogScanner at a speed of 125 m/min. The X-ray images were analyzed on-line with measures of different properties as a result (e.g. density and density variations). The logs were then sawn with a normal sawing pattern (50 × 125 mm) and the logs were graded depending on the result from the manual grading of the center boards. Finally, partial least squares (PLS) regression was used to calibrate statistical models that predict the log grade based on the properties measured by the X-ray LogScanner. The study showed that 77-83% of the logs were correctly sorted when using the scanner to sort logs into three groups according to the predicted grade of the center boards. After sawing the sorted logs, 67% of the boards had the correct grade. When scanning the same logs repeatedly, the relative standard deviation of the predicted grade was 12-20%. The study also showed that it is possible to sort out 10 and 16%, respectively, of the material into two groups with high quality logs, without changing the grade distribution of the rest of the material to any great extent
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| 5. |
- Seger, M.M., et al.
(författare)
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Scanning of logs with linear cone-beam tomography
- 2003
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Ingår i: Computers and Electronics in Agriculture. - 0168-1699 .- 1872-7107. ; 41:1-3, s. 45-62
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports an ongoing feasibility study in industrial X-ray tomography. Full volume scanning of logs may have a large potential in terms of increased sales value. On the other hand, there is no technology commercially available today which can meet the requirements for speed. In conventional medical 3D-tomography, the source-detector system rotates around a slowly translating patient. We do not believe such an arrangement is able to reach our speed requirements. Instead, we have been simulating an arrangement with two fixed source-detector systems rotated 90° relative to each other. Each system consists of an X-ray source and a 2D detector. The logs are to be translated through this arrangement at relatively high speed (2-3 m/s) lengthwise on a conveyor belt, while cone-beam projections are acquired by each of the source-detector systems. The 2D-detectors are composed of a number of 1D-detectors side by side. For cost reasons we will try to limit the number of rows to nine, forming a 2D-array of 256 x 9 detector elements. Due to the unconventional scanning geometry, we have developed a new reconstruction algorithm, which also takes special care to avoid many artifacts due to sparse and/or missing data. Experiments (still simulated), performed on voxelized CT data, indicate that the knots are reconstructed with sufficient accuracy to allow for quantitative optimization. Due to the missing data, however, heartwood can barely be distinguished from sapwood, but his fact does not seem to compromise the subsequent knot detection. Note that this paper only describes the reconstruction part of the simulated experiments. To be complete, the feasibility study should also include segmentation, which is outside the scope of this paper. © 2003 Elsevier Science B.V. All rights reserved.
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