關於渦旋
A professor once told me that scientists have already known a lot about vortices, but less about how to tackle with them in here and there cases. As to my mind, this means knowing by halves. As a matter of fact, I gradually found that human may not know more than a dragonfly! A dragonfly flying in a figure of eight pattern does know about Vortices Recycling. The highlight of the experiment is the hovering ability upon a fixed point in the air. Who can stay longer will be the king of Vortices. Sometimes I am not so optimistic about mimicking a fly or a bat, but I am really very interesting in discovering which flying mechanism is more effective,『Fling Mechanism』 or 『In a figure of eight pattern』, if with the same weight and energy? How to implement their mechanism in our flying machine? It is always the best policy to do naturally with vortices. The conservation of vortices is found here and there. Vortex itself is energetic. To gain means to keep. The one who is able to keep vortices will be rewarded. As in life generation and the ability of hovering, the rule follows. Typhoons and tornados still threat us like the beasts. And what’s more, a jumbo-airplane was crashed as beaten by tip vortices of the former airplane. As the dragonflies, the beautiful acrobats of vortices , infuse in tip vortices. Not the strong contradistinction did we realize that it is time for vortices!研究渦旋已經四年。四年之中，涉獵了許多關於渦旋的實驗。當我越了解渦旋，就越佩服那些卓越的昆蟲朋友們，他們可說是調配利用渦旋的大師。從候鳥遷徙的V字型隊伍、海豚的渦旋氣球、到蜻蜓八字型的飛行機制，我很想知道：在一個固定的流場中，到底哪一種運動機制，能最有效率的提供上升的力量？而如何將昆蟲朋友們的高超技術，運用到人類飛行載具上？將是我有興趣的另一項課題。『關於渦旋』是一系列渦旋實驗，目的就是自基礎開始深入了解在地球這樣環境下渦旋的性質。（一）探討基礎的渦旋本質（二）產生相對運動下物體的的渦旋架構（三）物體取得升力和失去升力的要件（四）昆蟲飛行機制探密（五）未來展望與渦旋的運用經過長時間的觀察可以了解到：1、渦旋遵守動量守恆。是以渦旋出現時是成對的2、渦旋是具有能量的。在上升力取得方面，當攻角過大時，渦旋剝離，造成能量的損失；以至於飛行載具失速。而蜻蜓是保有渦旋並加以利用的高手，自然事半功倍。順勢而為，渦旋增強。
液滴在我眼前蒸發
本研究的目的在觀察液滴的蒸發過程，探討影響一滴蒸發方式改變的變因。我們利用數位攝影機外加近攝鏡頭，由側面逆光拍攝液滴蒸發過程，並轉錄成電子檔利用電腦協助分析。液滴影像分隔放大投影在方格紙上，以便測量接觸角及高度的變化。結果發現蒸發情形可分為三種：Ⅰ.當接觸角大於九十度時，液滴和界面的接觸線迅速外擴，直到接觸角遞減至90度後定住不動，蒸發終了時，接觸線迅速內縮，留下縮小的實心殘跡。Ⅱ. 當接觸角小於九十度時，接觸線先些微外擴迅速外擴，之後定住不動，直到蒸發終點，液體內縮，留下環狀殘跡。Ⅲ.當接觸角小等於九十度時，接觸線始終定住不變，液滴蒸發後留下原大小的實心班跡。液滴蒸發時接觸角和高度並不是連續變化，而是交互階梯式遞減。本研究的結果可應用在探討噴漆及噴墨印表機的噴墨印刷上。The objective of this investigation is to observe the evaporation of liquid drop and find out the factors that could affect it. A digital camera with micro lens is used to film the process of the evaporation. And a close-up of the sample drop is taken with backlight. The results are analyzed with a personal computer. The magnified images of the drops are projected on grid papers for measuring the changes on contact angles, and heights of drops. We classify the evaporation of a drop into three types: Ⅰ. The contact angle is greater than 90 degrees. At first, the contact line will spread outwardly till the contact angle decrease to the 90 degrees and then be pinned until the evaporation reach its terminal. At last the contact line quickly contract inwardly, and a solid stain remain. Ⅱ. The contact angle is less than 90 degrees. The contact line will spread slightly and then be pinned. At the terminal the liquid contract inward, and a ring-like stain is formed. Ⅲ. The contact angle is equal to 90 degrees. The contact line will always be pinned, and no ring, but spot stain is left. During the evaporation, we discover that the contact angle and the height of the drop do not change continuously but alternatively decrease by steps. The results of our investigation can be applied to the aspects of paint-spraying and jet printers.
周轉不靈（汽車過彎翻覆原理與對策）
「翻車」事件令人怵目驚心，輕則車毀，重則人亡。減少翻車事件，可減少悲劇的發生。而翻車絕大多數均發生在轉彎的路段，且伴隨著超速發生。因此，本研究乃針對汽車過彎行駛，探討其翻覆的原因以及改進之道 · 本研究乃利用實驗分析法以及理論驗證法進行研究，實驗中變化不同的汽車質量，車軸寬、車身高以及車軸寬/車身高，質量重心寬、高以及寬/高、傾斜度以及迴轉半徑等九種參數 · 於自製的紅外線偵測變頻式可調迴轉模擬機上以八部模型試驗車測試其翻覆轉速，並換算為翻覆速度後逐一分析討論之。經由實驗結果，本研究得到以下結論：一、汽車轉彎翻覆與離心力有關，當離心力大於臨界側向推力時，汽車即翻覆。臨界側向推力公式為 F = mg ( tanθ + K?) / ( l -K? tanθ ) 二、最大容許車速平方與轉彎半徑及質量中心寬高比相乘積成正比；而在定車速下，飲小客許轉彎半徑與質量中心寬高比成反比．前述各項皆與質量大小無關．三、提高轉彎路面傾斜度對防止汽車翻覆有確實的效果。而最佳的過彎防止翻覆方法是降低車行速度，提高轉彎半徑，增加路面外側傾斜度，以及提高汽車質量中心寬高比”四、汽車過彎不致翻覆的最大極限速度 Vc 以及最小轉彎半徑rc分別為 vc=〔 rg ( tan θ + K ?）/ ( l 一 K ? tanθ ) ]; rc =（ V2 / g ) ( l 一 K?tanθ ) / ( tanθ + K? ) 五、本實驗所設計紅外線偵測變頻式可調迴轉模擬機，可有效的模擬汽車過彎翻覆，適用於中等學校物理、力學等學科的實驗課程。The accident of overturning a car always results in both destroying the car body and the death of the people. This project is to investigate what factors would have an effect on overturning a car and how to prevent a car from overturning.This project explores the factors by varying the mass of the cars, the distance between axes, the height of the car body, the ratio between the axis distance and the car height, the central gravity, and the declination. We test and record different overturning rotating speeds of eight model cars by a self-made adjustable simulator with a varying frequency infra-red detector. According to the experiment, the following results are obtained. I. The overturning occurrence is as a result of the eccentric force over the critical lateral force. The critical lateral force is F=mg(tanθ +K?)/(l—K?tan θ) 2. The square of allowable maximum speed is in proportion to the product of turning radius and ration of width to height for the center of mass; however, the allowable minimum turning radius is inversely proportional to the ration of width to height for the center of mass under constant vehicle speed. The above inference is independent of the mass of vehicle. 3. Increasing the declination can prevent a car from overturning. 4. The maximum speed for a car turning without overturning is Vc. The minimum turning radius is r. Both are expressed as follows:Vc=[rg(tanθ +K2)/(1—K?tanθ );rc=(’V2/g)( I —K?tanθ )/(tanθ +K?)5. The self-made adjustable simulator with a varying frequency infra-red detector can be used in the experiments of the middle school science curriculum.
魚洗水跳現象的探討
In the previous year study, we assumed that the fish basin as a column-shape model in order to exam and explain how the water spouting. This year, we established a reality-like situation of the fish basin to construct our theory base. At this point, round-waves and up-down waves are found as the beginning point of the water spouting. The sound from the basin is the frequency of the vibrations. Meanwhile, this process enables us to understand the causes of four, six, and eight waves. In addition, we tried to change the basin's positions, the capacities of water, the densities of liquids, and the sizes of the containers to demonstrate the theory. Furthermore, we used similar containers, such as high-heel cup and big magnetic bowl to experiment. The results are also corresponded with the theory. These results can also be used to explain the Chinese aeolian bell, clock, shaking bell, etc. That is a major innovation for us. Finally, we obtain better understanding of the abstractive theory though the simulation of the computerized photographs. 魚洗，也稱龍洗，傳說是中國唐宋時代皇帝洗臉的臉盆，內底四條魚紋，麟尾畢具。洗內盛水後，用手摩擦其兩個雙耳，立即發出響亮的嗡鳴聲，並出現美麗了漣漪，水珠四濺，摩擦越快，聲音越響，波浪翻騰，水珠越烈。對此在上一年度的研究中，是將洗盆視為圓柱狀，然後由圓柱狀所建立的模型去解釋水跳的原因，初步瞭解了水跳的原因。今年我們以洗盆真實的情況建立理論模型，在殼體產生共振的圓形駐波及上下駐波，此為水跳產生點，此時殼體發出的聲音就是共振的頻率。也瞭解了有四個、六個、八個、十個波腹的原因。並以改變殼體不同位置、水量、液體密度及洗盆大小等變因應證模型，結果與理論相符合。繼而以高腳杯、大磁碗等類似魚洗盆構造的容器，加以實驗應證，也能符合此理論。甚可推到中國古時候的編鐘、搖鈴、風鈴等器材。對於我們總認為碰撞就產生聲音的觀念實是一大突破。最後經由電腦動畫的模擬，讓此抽象的理論更容易瞭解。
吸管笛的諧音之研究與發展
吹長笛時，按同一按鍵，以大小不同的力量去吹，會引發不同頻率的泛音，而通常越用力吹，引發泛音的頻率越高，所以我們想了解為什麼越用力，泛音的頻率會高，其間的關係究竟是什麼？風經過管口會產生各種頻率的噪音，其中某些特定頻率的聲音會因為會在管內形成駐波而放大，所以我們只能聽到某些特定頻率的聲音。當風速增加時，會在管口形成渦漩逸放的紊流現象。其渦漩頻率與流速成正比（註一）。我們以塑膠管實驗。發現以特定的風速引發該基音後，繼續增加風速，當風速達某一定強度時，才會躍遷為下一個泛音的頻率。這個現象告訴我們：在一封閉管下，風速與泛音的關係並非「線性遞增」，而是越「躍遷遞增」的關係。另一個實驗測量不同管長、其諧音之頻率的關係，我們可以得知，越短的管子，因為相鄰兩泛音間頻率差較大，越不易激發更高階泛音。經由這些實驗結果，我們能夠推論：當管子越長、基音頻率越低時，諧音間頻率的差距相對越小，繪出的風速－頻率關係圖應更加顯示了風速與頻率呈正比關係。未來我們可以以閃頻器觀測紊流渦漩的產生，再變化至不同吹入角度，及各式管口造形，這些實驗能協助我們更進一步了解樂器的發聲原理，甚至開發一個以聲音頻率測量風速的儀器。註一：林婉如、張?文2006 國際科工程組佳作作品。When we press the same key and blow a flute using different strengths, we can get different overtones. Usually, the harder we blow the flute, the high the frequency we get. We want to understand why we get a higher frequency when we blow harder into the flute and to understand the relationship between them. When wind passes through the mouthpiece, many kinds of noises will be produced. Some of the frequencies will expand because they will form standing waves in the tube. Therefore, we can only hear certain frequencies. As wind speed increases, a turbulence of the vortex shedding will be formed. The frequency of the vortex shedding and wind speed will be in a direct ratio. We experiment with plastic tubes. When we increase the wind speed and get certain magnitudes, the frequency will jump to the next overtone. The phenomenon shows that the relation, in a closed tube, between wind speed and harmonics is not a linear increase but a transition increase. In another experiment, we measured the relationship between wind speed and different lengths of tubes. We can infer that the shorter the tube, the higher high-frequency harmonics can be produced. Through these experiments, we come to the conclusion that the longer the tube, the lower frequency of the fundamental tone we get and the discrepancy in frequency between harmonics is smaller. Then we make a diagram between wind speed and frequency that indicates that there is a direct ratio between wind speed and frequency. In the future, we can use “” to observe the production of turbulence. Then we can switch to different angles when we blow into flutes. Otherwise, we can experiment with different shapes of mouthpieces. These experiments can assist us to understand more how the instrument sounds. We can develop a device measuring wind speed with frequency.
磁流體的浪潮－磁場梯度下磁流波紋之研究
在本次實驗中，我們發現在不同厚度的磁流體薄膜中，會因本身磁性粒子結合，而呈現不同的影像圖形。隨著薄膜厚度增加，其磁性粒子會由鏈狀排列成塊狀叢集，可是一旦外加磁場後，又要全部轉向磁力線方向集結。另一個發現是將磁流體薄膜放在一個不均勻的磁場梯度中，則樣品內的磁流體粒子，不僅會隨著磁力線的方向排列移動，更會出現磁流波紋，其行進路徑是沿著垂直於磁力線的方向，向磁力線密集處移動。我們亦發現在不同的薄膜厚度及不同外加磁場下，其”磁流波紋”的波速亦會隨之改變。一般而言，樣品的厚度愈厚，或外加磁場愈大，其”磁流波紋”的波速愈快，反之則愈慢。最後，我們列出了一些磁流波紋的應用，相信是精采可期！In this experiment, we find that in different thickness of magnetic fluid different images will appear, because of the connection of magnetic particles. With the increasing of thickness the magnetic particles will change its shape from chains to blocks. But when we add external magnetic field, they will get in line one by one to the direction of magnetic line of force. We also find that we put the magnetic fluid film in the uneven magnetic gradient, the magnetic particle in the sample not only follow the direction of magnetic line of force but also show the “magnetic wave”. Its move path is perpendicular to the direction of magnetic line of force. In the different film thickness of magnetic field, the wave velocity of the “magnetic wave” will change. In generally, the thicker the sample is, or the larger the magnetic field is, the faster the wave velocity of magnetic wave is and adverse is true. At last, we list the applications of “magnetic wave”, we believe they are marvelous!
國王的海市蜃樓
在夏日的午後，在炎熱的柏油路面上很容易可觀察到遠方的 路面上，出現如鏡子般的倒影，看起來彷彿前方有一灘水，但當 我們向前進一些時，倒影卻突然消失了，這個現象，一般稱為海 市蜃樓。 一般解釋海市蜃樓的成因，都是由於在上層的低溫空氣，和 在下層靠近路面的高溫空氣，因密度的不同，以致於折射率的漸 層差異，繼而產生全反射。 但我們觀察發現，地面與上層空氣的溫差，並非柏油路面上 假積水現象及倒影出現的必要條件；反而和入射光的角度、路面 的平坦程度及路面的性質有關。我們提出了粗糙面在入射光的入 射角接近90度時，可發生單向反射的模型。並由實驗來驗證假積 水現象及倒影主要的成因是「柏油路面的單向反射」而非「空氣 的折射與全反射」。 Under the scorching sunshine, we can see the reflection on the tarmac in the distance just like a water puddle on the road. And the water also reflects the people and object nearby. But, in fact, the tarmac road over there is very hot and dry. Therefore we call the phenomenon as the “false water puddle on the tarmac.” According to the textbook , the main reason for “false water puddle on the tarmac” is that the temperature difference leads to the refraction of the light and causes the phenomenon. However, from our observation, the theory still can’t explain some phenomenon, For example, the “false water puddle on the tarmac” remains to appear when the wind blows fiercely. Even with little temperature different at night the phenomenon is still obvious. Therefore, in our opinion, the temperature different of the air is not a necessary condition of “ the false water puddle on the tarmac.” We bring up the model to explain the phenomenon that when the incident angle of the light approach 90 degrees, the light will result in one-way reflection. According to the model, furthermore, we make experiments at midnight and at dawn. The result of the experiment assures us the hypothesis of the model, Consequently, we hold the ideal that the main condition of the “false water puddle on the tarmac.” Is not because of the refraction and the total reflection but because the light reflects off the road and result in the one-way reflection on the tarmac road.