Observation of volcanic gases with a simple alkaline filter paper method at Sakurajima Volcano in Kagoshima, Japan.
There are many active volcanoes in Kagoshima Prefecture, including Sakurajima Volcano. So, the volcanic disaster prevention is an urgent issue. Also, Hirabayashi of Tokyo Institute of Technology reported that the molar ratio of HCl/SO2 is large during periods of high HCl/SO2 and conversely small during periods of low HCl/SO2 , and that explosions increase one month after the molar ratio of HCl/SO2 increases during periods of no explosions. We decided to determine the composition ratio of volcanic gases (sulfur dioxide, hydrogen chloride, and hydrogen fluoride) emitted from Sakurajima crater in order to understand and predict volcanic activities. Th us, we established a simple collection method for volcanic gases using alkaline filter paper and a quantitative method using a self m ade absorbance photometer so that even high school students could perform the measurement at many points, and we discussed the data from various perspectives. Furthermore, since last year, we have found a correlation between the variation of Cl-/SO2 ratio and the number of eruptions at Sakurajima volcano. Also, a model for the behavior of volcanic gases was developed based on a comparison of the amount of volcanic ash and the number of eruptions.
探討「互相牽制」中整除問題的整數解
在這篇作品中,探討科學研習月刊中森棚教官的數學題-「互相牽制」的整除問題,此問題是指「你可以找到多少組正整數對(x, y),讓x的平方減5為y的倍數且y的平方減5為x的倍數?」。我們除了探討原問題之外,也探討將5改為任意整數 l 的情況,我們要刻畫滿足 y | x2- l 且 x | y2- l 的所有整數解(x, y)。 首先建構生成另一組整數解的方法且推導出在 (x2+y2-l) / xy 為整數的條件下生成另一組整數解的方法。在 (x2+y2-l) /xy 為整數的條件下,可利用二階齊次線性遞迴數列及二次曲線刻畫滿足 y | x2 - l 且 x | y2- l 的所有整數解(x, y)。當上述條件不成立時,利用二次曲線試圖刻畫滿足 y | x2 且 x | y2 的所有整數解(x, y),進一步推導出在特定條件下,可利用二次曲線刻畫滿足 y | x2且 x | y2的所有整數解(x, y)。
從心開始-三角形的四心到各邊距離和
此研究討論三角形𝐴𝐵𝐶的外心、重心、垂心、內心到三邊之距離,並依銳角、直角及鈍角三角形,去比較各距離總和之大小關係及相互之間的關聯性。其主要結果為: 1.用外接圓半徑𝑅及∠𝐴,∠𝐵,∠𝐶表示各心到三邊之距離。 2.設外心、重心、垂心、內心到三邊之距離總和依序為𝑑1, 𝑑2, 𝑑3, 𝑑4 ,其大小關係為: (1)在銳角∆中,𝑑1 ≥ 𝑑2 ≥ 𝑑4 ≥ 𝑑3,僅當正∆ 時,等號成立。 (2)在直角∆中,𝑑1 > 𝑑2 > 𝑑4 > 𝑑3。 (3)在鈍角∆中,𝑑1 > 𝑑2 > 𝑑4 恆成立。𝑑3與𝑑1、𝑑2、𝑑4比較,並無絕對關係,但在等腰鈍角∆,我們給出其大小順序的臨界值。 (4)在鈍角∆中,若最大內角≥ 120° ,則𝑑3 > 𝑑1 > 𝑑2 > 𝑑4。 3.在銳角∆ 及直角∆ 中,等式𝑑2=2/3 𝑑1+1/3 𝑑3和 𝑑2+1/3 𝑑1-1/3 𝑑3-1/3 𝑑4 = 𝑅 恆成立。