胸高直径測定上の誤差について : 第3報 輸尺のあて方による誤差

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概要

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• The first report treated the error owing to the direction of measurement and the second report the error owing to the height of measurement. The third report treats the error owing to the angle between the callipers and the stem axis. If the stem curve near the breast height is linear and the angle between the callipers and the stem axis is not rectangular, the diameter measurement value is expressed by Equation (1) (see Fig. 1). When the stem curves of all trees are expressed by Kunze's stem curve equation and $ \gamma $ is about 2 in the stand, the $$\cos^2${$ \phi $}$ is expressed by Equation (2), and its variance is expressed by Equation (3). As was stated in the second report, $ \gamma $ is not 2 and the stem curves of all trees are not identical (see Fig. 2). In this case, the equation corresponding to (2) is (2'), so that the variance of A is expressed by Equation (3'). When $\cos{ $ \mu $}$ is denoted by B, the variance of B is expressed by, Equation (5), lf the angle between the callipers and the stem axis is taken by equal frequency within the range of G, the v($ \mu $) is expressed by Equation (6). When the Equation (1) is expressed by A and B, Equation (1) turns out to be Equation (7). The variance of Equation (7) is expressed by Equation (8), where V(d) is varied by the measurement method (as shown in the first and the second reports). Inserting the practical data in Equation (8), V, (d') is expressed by Equation (8”). When the diameter is measured exactly (i. e. at the breast height and at the average direction of the maximum and the minimum directions) and the angle between the calliper and the stem axis is not rectangle, the increase of variance is 0.8 per cent. And the increase of variance is 1.3 per cent, when the diameter is measured at random directions, the measurement height being varied 10 cm about the breast height, and the angle between the callipers and the stem axis from 90°to 100°. After all, the variation of the measurement method of the diameter breast high is out of the question.I 緒言　II 試料　III 理論　IIII 数値的結果　V 考察　参考文献　Resume

• 九州大学の論文

著者

• 高田 和彦

  九州大学農学部

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