利用滾動實驗測量摩擦係數
A cylinder rolling on an inclined plane and a sphere on grooved tracks are discussed in details.Using elementary mechanics, the formulas are derived for the time interval (t) and the final speed (vas a function of release height (h). (1) A cylinder is rolling down an inclined plane. The speed and time of the center of mass ofthe cylinder which changed with position (x) are recorded by a motion sensor. We can get theplots of v vs. √x and t vs. √ x, and find that the acceleration of the center of mass of thecylinder is constant, whether the cylinder is in rolling or a combination of rolling and slipping. (2) A sphere is rolling down an inclined grooved track. The final speed at the bottom of thetrack can be calculated from the physics of projection motion after the sphere leaves the track to thefloor. The time t for the sphere starting from rest to the bottom can be recorded by using photogate detectors. From the v-√h and t-1/√h graphs, μs between the sphere and track can be obtained. (3) When a sphere is released from the vertical height h of a cycloidal slide, the time tof pure rolling is the same independent of release position. But, when the sphere moves at a combination of rolling and slipping, the time t' will be different from t. We measure t and t' with photogate detectors and get the plot of t vs. h. The value ofμs can be calculated from the t - h graph. 圓柱或鋼珠從斜面或有槽曲面形成的軌道上滾下時，利用基本力學，可推導出時間 (t) 、速率 (v) 隨高度改變的函數關係。 (1) 利用運動感應器記錄圓柱由斜面上滾下時，圓柱質量中心的速度及運動時間隨位置 (x) 的變化，可繪出 v 對√ x 及 t 對 √x關係圖，由v－√x 及 t－√ x圖可知不論圓柱純滾動或滾動兼滑動，其質心均等加速度運動。 (2) 鋼珠由有槽斜板滾下時，到達底端的速率可由從底端至地面的拋體運動算出，而其時間t則可利用光電計時器直接記錄，利用 v－√h 圖及 t－1/√ h 圖可求出鋼珠和軌道的靜摩擦係數 μs。 (3) 鋼珠從旋輪線上方純滾動至底端時，所經歷的時間 (t) 和釋放高度無關，但是當鋼珠滾動兼滑動時，所經歷時間 t' 會改變，利用光電計時器量出 t 及 t'並作圖，利用 t－h 圖可出 μs。
滿足
之M點是否為重心之探索
滿足之M 點，我們稱之為Pi(i=1…n)的均值點。當n=3，M 恰為△P1P2P3 的重心 (G); n=4 時，M 亦為三角錐P1P2P3P4 的重心！因此不免引人遐思：滿足之M 點是否皆為其重心？
我們藉由電腦幾何作圖軟體GSP 協助觀察，掌握了圖形變化間之不變性，再配合向量解析及推理，得以發現均值點、多邊形的重心、以至多面體的重心、及平行多邊形的一般性作法。附帶又發現：任意相鄰三頂點即可決定一平行n 邊形。並進而證實：平行四邊形為四邊形M＝G 的充要條件。但當n≧5 時，平行n 邊形只是n 邊形M＝G 的充分非必要條件！一般而言，具有對稱中心O 的n 個點所構成的圖形必可使M 與G 重合於O 點上。
The point M satisfying is called “the mean point of Pi(i=1…n)”. As n=3, M is the center of gravity (G) of the △P1P2P3. If n=4, then M is also the center of gravity of the triangular pyramid P1P2P3P4. Therefore, I began to wonder if the following assumption stands: The point M that satisfies is always a center of gravity.
By using the computer software GSP (The Geometer’s Sketchpad) to observe figures. It is found that when a figure is changing there is still constancy. Furthermore, supported by the analysis based on vectors, general constructions can be established concerning the mean point, the center of gravity of polygon, the center of gravity of polyhedron, and the parallel polygon. Also, I find that any three neighboring vertexes decide a parallel polygon. And thus it is verified that the parallelogram is the sufficient and necessary condition for quadrilateral M=G. As n≧5, the parallel n-sides shape is the sufficient, not necessary condition, for n-sides shape M=G. In general, a central figure of n points having the center of symmetry O can make M and G meet on O.
隨機遞迴數列及渾沌現象
給定一個p∈(0,1)，令k0=0,p0在(0,1)間隨機分布,定義 k1為能使的最小正整數k，而;相同的，對於給定的kn-1,kn為能使的最小正整數k，。若存在kn使得，則稱p∈In;若對於所有的n與kn，，則稱p∈I∞。如此區間(0,1)可分解成集合I1,I2,…I∞。
小小細菌立大功-油類生物復育模式的探討
20 世紀初，石油的量產造就了人類文明前所未有的繁榮，然而由於運送、廢棄處理等因素，使得油類污染成為環境保護的重大議題。本實驗中，我們的研究主題為在受油污染的土壤中純化並鑑定出可分解油類之土壤菌和綠膿桿菌對可分解油類之土壤菌與這群土壤菌彼此之間的交互關係，藉此了解它們間的互動對環境生物復育的影響。我們由受油類污染的行道樹土壤中分離了約12 種的土壤菌，其中我們得到3 種對油類分解效果效果極佳的非綠膿桿菌(暫時命名為P7A、P7C、P7D)。經過菌種鑑定發現P7A、P7C、P7D 均為格蘭氏陽性菌。為了解這群可分解油類之土壤菌間的互動關係，我們針對分解效果最佳的P7A、P7C、P7D 作為研究對象，將菌落接種至含有鹽類與機油的液體培養基中震盪培養，並每隔一定時間測量其O.D 值。結果發現P7A、P7C、P7D 間的互動會導致其在以機油為單一碳源的培養液中之生長速度的改變，因此在行環境生物復育時須注意土壤菌間交互關係對其分解污染物速率的影響。此外我們由受油類污染的行道樹土壤中亦分離出了一些綠膿桿菌，因文獻指出，綠膿桿菌所分泌的綠膿素降低受油污染土壤中土壤微生物相的多樣性；因此，我們將由行道樹土壤中純化出的綠膿桿菌T3 與可分解油類P7A、P7C、P7D 進行交互作用觀察，發現T3 會侵占P7A、P7C、P7D 的既有菌落區，而平板培養基亦可清楚看出和T3 交接的P7A、P7C、P7D 菌落區寬度有明顯降低，因此我們認為T3 可抑制或殺死P7A、P7C、P7D，可得知綠膿桿菌會對可分解油類之土壤菌產生抑制或競爭關係。In early 20th century, the exploitation of petroleum transformed human civilization into a tremendously prosper stage. Because of the transportation and disposition of petroleum, the oil pollution has become a important issue in environmental protection. Besides, Chloropseudomonas spp. which can survive in many different environments and decompose lots of organic compounds. In this study, we want to find the bacteria which can utilize oil from machine oil-contaminated soil, investigating the interaction relations between Chloropseudomonas spp. and these oil-degrading soil bacteria. First, we classified these oil-degrading bacteria by the book called“Bergey’s Manual of Systematic Bacteriology.”We find three species of oil-degrading bacteria (P7A、 P7C、P7D) which are all grams-positive bacillus, possibly belonged to Aureobactreium、Curtobacterium、Cellulomonas、Oerskovia、Brochothrix、 Caryophanon. Second, in the study of the relationship between Chloropseudomonas spp. and the oil degrading soil bacteria, we found that Chloropseudomonas spp can considerably inhabit the growth of oil-degrading bacteria. Besides, there are also a great variety of interaction between three species of the oil-degrading bacteria. According to the result , the interaction might considerably affect the efficiency of oil bioremediation. Due to our analysis, we suggest that it is necessary to pay more attention to the interaction between bacteria when undertaking oil bioremediation.
台灣沿岸地形與海嘯的實驗室模擬
本實驗利用喇叭、薄膜電極、波型產生器、鎖相放大器、及750 介面卡組合一套系統,此系統可使偵測精密度大幅提升(±4*10-5cm),使得水槽及地表模型尺度變小(40*22*35cm),因此可節省實驗的成本與時間我們在坡度實驗中,發現坡度在3 度左右,淺化係數都超過3. 對照台灣沿岸發生海嘯的歷史記載,確實在台灣東北角及西南沿岸等坡度為三度之地區都發生較明顯的海嘯危害. 反之,坡度在四度以上的東岸其海嘯波高都非常低.最後再藉著硬體系統及電腦2D 動畫模擬的整合,使我們可方便掌握波浪在不同坡度及位置,其波長及波高變化比,如此有助於預估及說明海嘯隨地形變化的狀況.By using the horn, membranous electrodes, function generator, phase-locked amplifier, and Science Workshop 750, we plan to assemble a tsunami simulation system in which the precision can be getting increased (±4*10-5cm) .Because of the improvement of its precision, the size of the tank and of the surface models will become smaller .As a result, the money and time spent on the experiment will be spare. When experimenting on the influence of inclination of the landforms, we observed that when the inclination reaches about 3 degrees, the shoaling coefficient exceeded 3 .The result of our experiment can provide an explanation to the tsunami on the northeast and southwest coast of Taiwan .According to the historical records, the disastrous tsunami happens frequently on the northeast and southwest coast of Taiwan where its inclination is also about 3 degrees as well .On the other hand, on the eastern coast, the wave height is lower and its inclination exceeds 4 degrees .Apparently, our experimenting result is correspond to the natural phenomena in Taiwan’s coast . Besides, with the help of hardware system and computer 2D animation simulation, we can easily measure the wavelength and wave height scale of the wave in different inclinations and positions. Therefore, this tsunami simulation system can provide a great help to estimate and explain the phenomena of tsunami which may change its condition in different landforms.