Articles containing the keyword 'cross-section'
Category : Article
Electrical impedance characteristics of plant cells are dependent on such physiological factors as physiological condition, developmental stage, cell structure, nutrient status, water balance and temperature acclimation. In the measurements also such technical and physical factors as type of electrodes, frequency, geometry of the object, inter-electrode distance and temperature have an effect. These factors are discussed especially with respect to the impedance method in frost resistance studies of plants.
The PDF includes an abstract in Finnish.
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Repo,
E-mail:
tr@mm.unknown
The structure of 20 Scots pine (Pinus sylvestris L.) trees was analysed as a water transport system. There is a tight linear regression between the cross-sectional area of the stem at the height of its lowest living branch and the cross-sectional area of its coarse roots, between the cross-sectional area of the stem at the height of its lowest living branch and the total cross-sectional area of its branches, and between the cross-sectional area of the base of a branch and the total cross-sectional area of subsidiary branches of that branch. The capacity of successive organs, measured as cross-sectional areas, to transport water was thus found to be regular within a tree.
The PDF includes an abstract in Finnish.
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Hari,
E-mail:
ph@mm.unknown
- Heikinheimo, E-mail: ph@mm.unknown
- Kaipiainen, E-mail: lk@mm.unknown
- Korpilahti, E-mail: eeva.korpilahti@luke.fi
- Mäkelä, E-mail: am@mm.unknown
- Samela, E-mail: js@mm.unknown
In this study the area, 8 diameters, and 16 radii were measured of 174 discs representing aspen logs in a mill. The average difference between the largest and smallest diameter was 18 mm, or 7% of the longest diameter. The difference between the largest and smallest radius was 29 mm, or 22% of the longest radius. The diameter was on the average 2.4 mm longer than the two corresponding radii.
The exact area of each disc was measured using a planimeter. In comparison, the area based on the circle formula the diameter being the arithmetic mean of largest and smallest diameters overestimated the area by 1.7%. The results also indicated that the use of random direction in the measurement of diameter overestimated the cross-sectional area on the average by 1.8%.
The study is continuation of the earlier study where the bibliography is presented. As far as the results are comparable, they support each other.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The aim of the study was to determine the extent to which the cross section of birch (Betula sp.) and aspen (Populus tremula L.) logs differ from a circle and to test some simple methods for measuring the cross-sectional area which can be used, for instance, for determining the volume of the logs. The material consisted of 420 debarked birch disks and 240 aspen disks which were representative of the logs arriving at two factories.
The convex deficit values for the material were very small, the cross-sectional area error being in general less than 1%. On the other hand, the other parameters deviated from the circular form to quite a large degree. It was also evident that the radii measured from the piths to the surface of the wood varied considerably more in the same disk, as regards length, than the diameters measured in different directions.
It was evident that the shape of the average cross-sectional area was not in general elliptical. It thus appears that any method for measuring the cross-sectional area which is based on elliptical formula is not suitable. The method which gave the best result was that in which the cross-sectional area was taken as the average of the area of the circle calculated from the smallest diameter and that calculated from the diameter passing at right angles to it. This method also appeared to be the best for disks which deviated to quite a large degree from the circular form. The suitability of this method is increased by the fact that the relative error is only slightly dependent on the size of the disk.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
Category : Article
Because the cross-sectional area of a tree stem is ellipsis, it cannot be determined exactly with only the diameter measurement. The article presents a formula and the calculation of the exact cross-sectional area. If the cross-sectional area is calculated as arithmetic mean of two diameter measurement, varies the error between two limit values. The error becomes smallest by calculating the area based on the biggest and the smallest diameter measurements.
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Heikkilä,
E-mail:
th@mm.unknown
Category : Research article
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Pulkkinen,
E-mail:
minna.pulkkinen@iki.fi
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Pérez Cordero,
Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), Turrialba, Costa Rica
E-mail:
diegoperez@costarricense.cr
- Kanninen, Center for International Forestry Research (CIFOR), Bogor, Indonesia E-mail: mk@nn.id
