全國中小學科展

數學

遞迥數列及渾沌現象

給定一個P∈(0,1),令k0=0, p0=p,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n 與kn ,,則稱p∈ I∞。如此區間(0,1)可分解成集合I1,I2,…,I∞。

一些Moire patterns 的數學性質研究

Moire 為法文,其英譯為watered, 是古代織布技術的一種應用;將印有規律條?的透明薄片重疊時,稍微移動或轉動其中的一片,會形成極大的圖形變化,稱為moire pattern本作品針對三個moire pattern 的數學式加以推導:(一)、兩張透明片各印有等間隔平行線,轉動其中一片使兩線的夾角θ,亮紋垂直距離和暗?垂直距離的比值為tanθ/2tanθ 。(二)、兩張透明片各印有輻射線,重疊後行成圓系,可由代數或幾何加以證明,利用三角函數可推導出此圓系方程式為:x2+{y-rtan[π/2-(θ-?)]}2)]}={rsec[π/2-(θ-?)]}2)]}\r \r (三)、透明片A 印有等間隔平行線,B 印有符合高斯曲線的平行線,AB 重疊時,形成一系列的高斯曲線,AB 的夾角減少時,會增大曲線的曲率,我們進一步討論曲線的曲率和平行線斜率的關係。Moire is the French word “watered” and refers to an ancient technique employed in cloth making. The moire occurs whenever two or more transparent sheets with periodic strips on them are superposed. The characteristic of moire patterns is the fact that a slight shift of sheets will create dramatic alternations in the observed patterns. In the present report, We derive the equations of three different moire patterns. First of all, take a sheet with equal spaced straight lines and placed it on top of another identical sheet. They are made to intersect and form an angle of θ. As the angle changes slightly, it produces huge changes in the spacing of moire fringes. We can derive a formula related to the interfringe distance. The ratio of bright fringes and dark fringes is tanθ/2tanθ.Secondly, two transparent sheets with radial lines on them are overlapped, forming a pattern similar to the lines of force between point charges. We can find that the pattern is a series of circle by means of algebraic and geometric proofs. And proven by trigonometric functions, we canconclude that they satisfy the equation :x2+{y-rtan[π/2-(θ-?)]}2)]}={rsec[π/2-(θ-?)]}2)]}\r Thirdly, a set of lines of equal spacing is overlapped with a second set of lines whose spacing are derived from a Gaussian curve. A series of Gaussian curves is reproduced in a moire pattern. Reducing the angle of intersection between the two figures steepen the curvature. We discussed the relation between the curvature and the slope of inclined lines.

Amazing Fairy Chess -討論多元方形鏈的數量

在這篇研究報告中,我們討論的是一種方形集合圖形的數量。”多元方形鏈”約略在 60 年代被提出,衍生出一系列的問題和遊戲,例如熟知的電玩軟體 『 俄羅斯方塊 』 ,或是 『 益智積木 』 的遊戲,都是多元方形鏈的應用。在這些問題當中,最令人頭痛的難題就是 n 元方形鏈的圖形總數。為了解決這道難題,我們採用一種轉換方法將圖形轉換成序組,並且給出序組的性質,再據此寫成 C 語言的程式;反覆地修改程式以增進執行效率及速度,最後利用該程式成功地統計出圖形總數。 In this report, we discussed the amount of polyominoes, the graphs of a set of squares. “Polyominoes” has been brought up in 1960s, and later developed into a series of questions and games, such as a well-known video game — Tetrix, and the game of puzzle blocks. Both are the applications of polyominoes. Among those questions, the toughest one is the amount of n-polyominoes. To solve this problem, we used a method which transforms the graphs into sequences. By looking into the properties of those sequences, we obtain a set of rules that can be used to determine the quantity of n-polyomines. The rules are implemented into computer codes in C language with proper modifications made to speed up the efficiency of our algorithm. The computational results show that the amount has been successfully calculated.

圓來如此─西姆松「圓」的研究

若從一個三角形的外接圓上取一點,作其對三角形三邊的垂足,我們知道這三點共線,是為西姆松線。\r 那麼當此點不在圓周上的情形呢?自平面上一點對一三角形的三邊分別做垂線,得到三垂足,並作此三垂足的外接圓,我定義其為:此點對此三角形的西姆松圓。這篇作品主要成果便是對西姆松圓的研究。透過不斷的研究,發現了許多關於西姆松圓的神奇性質,並得到了一些結果,主要的研究方向:討論共點、共圓、相似。\r 這篇報告是循序漸進的,後面的結果常用到前面的知識為基礎。此篇另一特點是:全篇的證明皆是自已給出的,採用方法皆為一般幾何證明,而沒有用到解析證明。\r 在研究過程中也得到關於著名的費爾巴哈定理及大上茂喬定理的另一種證明。

NICE數-正方形與正立方體的切割

源自於Thinking Mathematically這本書的一道題目, 關於正方形的切割問題:將一個正方形切成不重疊的正方形, 所得的個數就可被稱作NICE(好的), 問有哪些數是NICE數? 在平面的正方形切割的問題, 透過分割技巧, 我們得出了重要的結果:除了2、3、5以外的自然數都是NICE數, 並推導出:若k為NICE數, m為自然數, 則k+3m為NICE數。我們將問題推廣至立方體:將一個正方體切成不重疊的正方體, 所得的個數就可被稱作very NICE(非常好的), 問有哪些數是very NICE數?我們也得出重要的結果:大於47的自然數皆為very NICE數, 並推導出:若 是very NICE數, 且m是自然數, 則k+7m為very NICE數。

Computation of the Alexander-Conway Polynomial on the Chord Diagrams of

平面切立方體內單位立方格數極值之計算

我們先假設有一正方體及一截過正方體之平面,並設正立方體為一k*k*k 之立體。為計算平面截過之單位正立方體個數,我們必須先分別計算各層被切過之個數再將之相加,因此將各層面投影至同一平面,簡化為平面上之問題,並討論其性質/規律,計算平面截此正立方體之個數。如此,便可以一般化數學式計算平面截正立方體個數之問題。接著,用以上方法為基礎,討論各種平面切正立方體之類型,將被平面所截之單位立方體個數以電腦程式算出,觀察數字變化及其性質規則,並找出最大值發生之條件。 We initially supposed that there are a regular hexahedron consists of unitary n × n cubes and a plane which incises the regular hexahedron. To calculate the total number of the unitary cubes incised by the plane, we can first calculate them layer by layer and then sum them up. And further, we project each layer on the same plane, so the three-dimensional problem is simplified into two-dimension. By making use of the character which results from projection, we can easily calculate the number of the unitary cubes incised. Consequently, we are able to calculate them with a general equation. Afterward, we research each circumstance that the plane incises the regular hexahedron on the base of the mentioned methods. Calculate them with self-designed computer programs, and observe the regulation and change of the result. Furthermore, we can find out when it will achieve the maximum.

架構「類球狀多面體」的理論與實務

本報告的目的在:電腦Cabri 3D 軟體上模擬出「類球狀多面體」(圖1-8),\r 並實作其模型(圖9)與它們的星體(圖10)。「類球狀多面體」的定義如下:\r 可由「正多面體」切出之多面體,且需滿足以下性質:(1) 除「正多邊形」外,\r 其餘皆是「六邊形」。(2)鳥瞰每個「正多邊形」時,形狀皆保持不變。(3)\r 等長的稜數最多。\r 以「正十二面體」切出之「類球狀多面體」為例,(圖1)中兩個「正五邊形」\r 相距一個「六邊形」簡稱A1。(圖2-4)依序為A2、A3 與A5。正二十面體可切\r 得(圖5-6),正六面體可切得(圖7-8),......等。(圖9)為A2 的實體模型,\r (圖10)為A2 的星體模型。

棋盤的費伯那契

在學校科研營的教材中,有一個題目,其內容相當於:「在一列格子中 放入黑棋與白棋。白棋不可連續放置,而黑棋不受此限,請問共有幾種可能的排列方式?,在此規則下,若將格子推廣為m列n行的棋盤,那又如何呢?我們對此好奇不已。

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∞。