Sunday, 27 March 2011

Physics: Introductory Nanotechnology (Atomic physics Ch.5)

Introductory nanotechnology
Nanometer (nm) refers to 10-9m. Nanoscience refers to the science concerning the science on the nanoscale. Nanomaterials have size about 1~100nm, they have quite a different properties from normal objects.
Allotropes of carbon
-          Diamond has a vast network of tetravalent bonding system, with bond angle 109.5º, the strong covalent allows diamond to have high strength and melting point.
-          Graphite forms planar carbon layer with Van Der Waals force holding between layers. As a result they are brittle (layers sliding over each other)
-          Carbon nanotubes / fullerene are formed by closed structure of hexagonal/pentagonal  rings, they have board uses in medical and other fields.
Properties of nanomaterial
-          Mechanical properties like higher tensile strength (maximum stress acting on the solid before it breaks); higher strength without trading off ductility.
-          Optically properties like different colours (aqueous nano-sized gold is in red); different behavior in radiation absorption (e.g. ZnO in blocking UV radiation)
-          Thermal properties like lower m.p. in smaller size and better thermal conductivity.
-          Electrical properties like changing their resistivity (can be increasing / decreasing)
-          Magnetic properties like ferromagnetic (magnetization unchanged when permanent magnet is removed) becomes paramagnetic (magnetization disappears when permanent magnet is removes) when the material is in nanoscale.
Reasons behind the different behaviors
-          Surface area to volume ratio for nanomaterial is larger. Outsider atoms are usually more reactive then interior atoms. When the surface atoms dominate there can be different properties.
-          Quantum effects like the more significant matter wave are given out in nano-sized material and more significant quantization of energy.
Lotus effect
There're many small bumps with wax crystals on the lotus leaf and make it water-repelling. Water on it forms globules and rolls off. This easily catches the dirt, which gives the idea of self-cleaning phenomenon.
Optical Application
The lenses used in optical microscopes are not ideal. The ideal case is that all parallel light (in different wavelengths) passing through the lens converges at the same point. However in real case there're two aberrations:
Optical aberration: parallel light passing through the lens don't converge at the same point.
Chromatic aberration: light with different wavelengths are bent in different extent by the same lens, causing more than one converging point.

Consider the diffraction of light through a circular small hole. The diffraction patterns are several circular rings with successive bright and dark fringes. When two point sources passes through the hole and diffracts, superposition between two diffractions occurs. Then it may not be able to separate the two patterns (into independent wave functions).
The Rayleigh Criterion states that the image is just resolvable when one's central maximum falls on another's first minimum. When the two wave functions go nearer it's not resolvable.
By calculation we obtain θ≥1.22λ/D, where θ is the intersection angle between two point sources or the angular separation of the two sources. At critical case, θ=1.22λ/D.
Consider the two point sources as the extreme points from a lens. Let s be the separation between two point sources, and f be the focal length. For f>>s, s ≈ fsinθ ≈ fθ = 1.22fλ/D. In practical f > D/2, so s > 1.22fλ/D > 0.61λ. Consider for visible light, λ is about 10-7m, the resolving power of optical instruments are also limited to about 10-7m, so it's impossible to observe nanoscale or smaller scale by optical instruments.
Transmission electron microscopes (TEM)
The electron gun emits electron and accelerated under high potential, and passes through a series of magnetic lens (which bends the electron). It passes through the condensing lens and pass through the object, then pass through objective and projection lens and show the image on fluorescent screen. Since electron has smaller (de Broglie) wavelength, it has higher resolving power. Consider voltage applied as V, energy of electron is V (eV) = mev2/2, then we can calculate the wavelength of the electron beam. It's also acceptable that the de Broglie wavelength is approximately equal to the resolving power of the microscope.)
Scanning Tunnelling microscopes (STM)
The tip of the microscopes is about the size of several atoms. They kept a short distance from the object (several nm). A small positive potential is given to the tip so that tunnelling current is produce between the object and the tip. As explained before the tunnelling current is related to the distance between the tip and the object, then the 3D structure of the object is scanned.
Applications
-          Controlling individual atoms, CPU production
-          Nanomaterials with specified properties like medicine, ductile ceramics, clothes…
-          Photocatalysts which enables functions (like dirtiness prevention, anti-fog, anti-bacteria, water treatment and deodorization) under the presence of light like TiO2 and ZnO
-          Nanotechnology like solar panel using nanomaterials and robots.
Potential Hazards
-          Nanomaterials are reactive than its bulk form, and is more volatile, soluble and penetrating, so it can be more easily to be absorbed and can be more toxic.
-          They may have unknown toxicity or even causing DNA mutations
-          Polluting the environment and cause social problems (e.g., upraise of nanoweapons)

Tuesday, 22 March 2011

22-3-11

很久沒有打過日記了……
最近的時間都花了在物理上,一眨眼那已是四五月、數學比賽的季節又到了。升上中五發覺自己同時睇幾科ALevel有點力不從心,更沒空操數了。現時惟有操下日本那邊的數學入學試,總覺得那邊一些題目很深入,但一些偏目的課題都不見了。
我打算用McGrawHill為參考書編寫Organic Chem的筆記,希望不會選材太深,還望大家多加意見……
小說方面,我繼續寫Osu!-related的文章,但接龍方面則被荒廢了,我希望有空填坑 orz
最近看了一本不能開名的小說,某魔王艾爾以金錢稱王,而「以金錢之力在RPG系統稱霸」是否可行這課題我倒很希望抽空研究一下……

狂人者,有吐嘈,亦有生動的一面……

機會成本 千玥


這是一則發生在經濟堂的事情。
「各位同學,今天我要教的是……」正在上經濟堂的我倒在桌上,默默地聽着老師講課。但可能是因為剛剛吃完午飯的關係,一股倦意正逐漸襲上我的心頭,使我愈來愈沒有精神上課。
好累呢……昨天為了完成所有的數學功課所以弄得很晚才睡覺。所以啊,讓我好好的睡一覺吧……反正現在老師教的都是一些基本的概念,而這些我早就預習了,睡一會兒也不至於聽不懂……嗯,就這樣決定吧,睡十分鐘就好了。
正當我下定決心而且快要睡著的時候,坐在我旁邊的同學突然推了我一下,「耶,別睡了,老師正走過來呢!」
……不是吧!他不會剛好走過來然後問我問題吧!
我慌忙地拍拍自己的臉頰,好讓自己清醒點。可是我整個人還是很累,完全提不起精神。
……怎麼辦?!
啊!有辦法了!
我看着眼前的一瓶冰冷的礦泉水,心裏有了一個主意。
我打開瓶蓋,「咕嚕」一聲喝了好幾口。
好冰!我差點想毫不優雅地把冰水噴出來。
但我最終都沒有這樣做。
而這個舉動,令我整個人都清醒了起來,專注度直達一百!
而我也決定,以後絕對不會在堂上喝冰水。實在是冷死了!
然後又無驚無險地過了半小時,老師說休息五分鐘。
我們整班吵鬧起來。有些人說要去洗手間,而有些人,就例如我,則選擇和朋友談天。(當然是關於經濟學的問題啦!)
正當我們談得興起的時候,突然有同學發覺有些中一的學弟在走廊徘徊着,不知道在幹甚麼。
於是,我們整班一致地望向我們親愛的老師。沒辦法,誰叫我們的經濟老師是訓導老師其中之一呢。
在這個時候當然是他出馬的時候啦!
老師咳了一聲,然後走出課室,望向那群中一的同學。
「你們還不回去上課?」
……這一刻,我突然覺得老師很有訓導老師的威嚴。
說完後,他便走了進來。
我們全班同時拍手、笑瘋了……
然後,他又咳了一聲,裝作嚴肅,說,「嗯哼,是時候上課了。」
「前天,我看到了一則新聞,可以用我今天所教的機會成本來解釋這則新聞。」
我們全班專注地聽着他的說話。
「內容是說有一個外表漂亮的中年女人,任職銀行家,年薪有百萬之多,可是,為甚麼她仍然找不到一個條件相約的伴侶呢?」老師這番問題,使全班興奮了起來。
為甚麼會這樣?對於這個問題,我完全找不到答案。
突然,坐在我身後的同學給了一個很棒的解釋給我。「我知道!因為和她條件差不多的男人都希望找到一個穩定的對象。可是,假如有她這樣漂亮的伴侶的話,每天都要提心吊膽的過日子,害怕女朋友被別人搶去。所以,為了自身的幸福着想,他們都寧願選一個沒那麼漂亮的作為伴侶,而不是那個外表美麗而且擁有百萬年薪的中年女人!」
哈哈!光是聽到這個答案,我就已經覺得今天的經濟堂值回票價了!
看我們沒有人肯舉手回答,老師便自揭答案。
「先不要理會有沒有競爭對手這個問題。假設現在沒有人追求她,可是,光是要留住她,就需要大量金錢和時間。試想想,這樣的話,追求她的機會成本不是大了很多嗎?」
全班哄堂大笑。
「再者,假如有人正同時追求她的話,為了要獲得她的青睞,你便要付出最大的代價來討得她的歡心。而且,你還要有心理準備,她會另結新歡,和你分手。這樣不是很不划算嗎?」
老師詳細地解釋着,到最後連自己也忍不住笑了起來。
這時,放學的鈴聲剛好響起來,代表今天的經濟堂已經上完了。可是,我們全班還是議論紛紛,不捨得散去。
嘿,假如以後的經濟堂也這麼的好玩就好了!

Saturday, 12 March 2011

Castles in the Sky: 論同人創作

Find your castles in the sky---
還記得很久以前的施政報告/預算案嗎?六大產業中其中一個叫做文化創意產業。從兩年後的今天回望過去,文化界有沒有明顯起色?沒有。
<<香港.文化.金錢>>一文中曾講過有關出版界的惡性循環,香港書甚至是港漫,均因為市場問題抬不起頭來(港漫的問也許更為複雜),結果大家有目共睹:香港人的主流書籍均為內地或台灣,或是日本歐美的翻譯書本,本土非愛情小說作家(也是口味問題,此類小說可謂重量不重質,加上需求彈性不高,自然維持了一定市場。有關此類小說的問題我參透不了,但有本網上小說倒值得參考:小說村的<<典型言情小說>>)更是小之又小。不久之前,本土作家天航移居台灣發展,雖不能說是找「新財路」(當然,像巴金那樣不為錢而寫、不為權而寫的人少之又少),但留在香港的話根本入不敷出,再崇高的工作,沒了錢也不能在這世界生存(錢,泛指能換錢的價值,比如歌星的知名度,或者當權者的權力等。正如五六十年代的毛老頭一樣,不必有錢在手,但當然能吃喝飽足)
考慮到市場的問題,今天討論的主題是關於香港的金錢物質主義與文化產業在意識上的不同,那香港人的口味與那種小說不符也就不奇怪了。
將一切寫實的成分撇開,憑空創作的精髓──天馬行空,另一種比較難聽說法叫空中樓閣。用一點認真的成分去閱讀這些小說,科幻一點的的小說,只要分析一下其違反我們這世界定律的設定,不難發現必定有矛盾之處。(有關這方面的內容可參考RPG系統一文。)
空中樓閣同樣可指那沒有公理支持的設定,反正實行完全的天馬行空本來就沒有依循已有法則的必要。英文同樣有一句話來形容空中樓閣,那就是Castles in the sky,碰巧這是DJ Satomi的一首名曲,其內容剛好演釋了科幻創作的精神:
It’s a place in my mind; no one knows where it hides
And my fantasy is flying, it a castle in the sky.
科幻的原創性:基本上每一個獨立的故事的設定集都不相同,從心出發、原創的內容才真正屬於自己的。
It’s a world of out past, where the legend still last;
Where the king wears the crown, but the magic is the law.
典型的RPG模式。其背景生活設定類似於中世紀的模式(因此我們有時會將這些故事定為過去),例如階級制度,以及絕對的由上而下的管治方式,與現時不同的是,中世紀也許只有有錢人才能讀書,對其仕途有著正面的影響,但在RPG模式中,只有有錢人才有資格學習魔法,由於魔法與武力等價,於是有了「魔法(力量)就是法律」的講法。
Now take your sword and your shield, there’s a battle in the field;
You are knight, you are right, so with dragon now you’ll fight.
龍作為傳奇性的生物在RPG中被抬出來並不奇怪,最經典的大概是勇者鬥惡龍吧。遊戲與現實的最大是出於道德的考慮上:遊戲中你也許可以殺人放火,偷別人的東西(例如GTA),但那在現實上是絕對不可以的。遊戲中只要完成任務可以不擇手段,但現實上的限制將會更多。
And my fantasy is flying, it’s the castles in the sky;
Or there’s nothing out there, it’s a castles in the air.
Fairytales live in me, fables coming from my memory;
Fantasy is not a crime; find your castles in the sky.
RPG的創作背景總是跟寓言及神話的哲學思想有關:而寓言與遊戲的共通點在於觀看單一的故事時我們只會看到世界的其中一方面,局部或不完整的世界觀將幻想最大化才能吸引玩家。這段同時回應了現實(整體的世界觀)與幻想(部分的世界觀)存在予盾,但作者始終認為幻想能與現實並存。
You’ve the key to the kingdom of the clouds,
Open the door and leaving back your doubts.
You’ve the power to leave another childhood,
So ride the wind that leads you to the moon.
既然現實與幻想存在予盾,我們可將幻想比為一道鎖上的門,有幻想的人才會進入;另一方面,接受幻想的人亦會在進入幻想之門時拋下對現實與幻想之間的予盾。最擅長幻想的人?當然是小孩……
既然幻想的世界觀與現實有所相違,現實對幻想產生排斥也是很正常的事,比如「把書讀好,少玩一會遊戲機」、「玩得遊戲多,日後還不是沒工作」之類的說話隨處可見。本人並不排斥這種說法,因為加深對幻想世界觀的認識對現實並無幫助(我們可將兩種世界觀視為兩個平行世界,兩者實無關連,幻想的世界觀頂多也就以電子或磁場的形式在記憶體存在而已。不過考慮到幻想世界觀的不完整性甚至相逆的公理的存在可能性,其平行世界的存在性令人生疑,不過這已經不在此文的探討範圍中。此外,這些責罵的句子雖然概念正確,但免不了有所誇飾……)
在香港,這種排斥更為嚴重,一切都是金錢作怪。
幻想觀既然只以非實體的形式存在,那麼其初始的存在形式其本上以數碼為主(動畫、漫畫的圖檔、文字檔案)。如果說實體經濟是考慮到稀少性(Scarcity,不能滿足所有人的需求),那麼數位市場就傾向追求豐富甚至浪費(「滿足所有人的需求」是理想條件,也就是數位市場所追求的目標。)。其豐富性質在於複製的成本趨近於零(只是改變了幾個電子或磁場的極性,沒有改變物體的本質;有別於現實中複製一件實體改變了物體的特性,其成本是不能比擬的),以及貨架(存放空間)的成本趨近於零(數位形式的貨架也就是硬碟,邊際成本幾本為零,因為你填滿一個硬碟時會讓某些記憶消失而非買一個新的硬碟;相反實體的貨架無疑於複製另一種物件(貨架))在科技進步的前提下,由於數位空間獨立於實體材料的需求,早有數據顯示數位空間、頻寬及處理器的單位成本每年下降約五成。如此下去,成本會變成一文不值而成為真正的零。
趨向免費的數位市場會產生另一種效應,稱之為去金錢化(Demonetization)。以百科全書為例,現時維基百科的資產總值比起以前的大英百科全書要少。很詭異的一點是,在替代效應上,只有更具競爭性的物品才會替代舊有者。維基是如何以一個更小的產業應付一個更大的市場?這件事有幾個條件:一、維基完全免費,這是數位競爭的首要條件(在便士效應Penny effect下,免費和一元的需求差距遠比一元和任何其他定價的需求差距來得大。在免費下我們的成本僅為擺放的成本,在數位系統下成本趨近於零)。二就是去金錢化。
「天下沒白吃的午餐」這句名言相信大家耳熟能詳,在封閉市場下每個交易最終都有人為一件物品而付費;在數位市場下這名言依然正確,但成本的單位再不是金錢而更多傾向於名譽等難以量化的單位。(當然,名譽是否值錢就看你自己的功夫了。此是後話。)維基自身雖然不夠值錢,但其名聲卻大於大英百科全書──一些人就是靠著編寫維基而出名繼而賺到錢。當然,去金錢化與講求將價值量化的資本主義同樣有相逆之處,因此目前一些成功去金錢化的市場仍屬少數。
香港的同人市場亦有同樣的問題,由於市場不夠大,實體商品的市場並不吃香,數位市場成為了同人畫師爭取注意力之地。將值錢的同人誌捨棄,改為免費放在Pixiv的畫作,倒能為他們在周邊商品(文件夾、匙扣)帶來利益。
儘管香港同人市場並非全屬禮物經濟,但我相信對於創作,特別是市場先天不足的同人創作來說,要令更多人認識二次創作,要對抗過份資本的拜金主義,奉行禮物經濟不失為一個好辦法。當然,這同樣也能應用於其他文化產業,那就要看香港的造化了。
P.S. 有一本書頗切合本文內容,值得一讀: Free: The Future of Radical Price

Sunday, 6 March 2011

6-3-2011

The core idea of atomic world electives has been finished. I tried to put a bit extra material about uncertainty and tunneling to make the concept on quantum physics clearer.
Since I'm avoiding the statistical mechanics approach and those advanced maths (partial deviation and multiple integration), I don't think I can put anymore extra stuff in the notes.
The last topic on atomic world is about nano technology. The content includes
- Effect different from classical view due to nano-sized material, such as Lotus effect
- Reasons that contributes to those nano-sized effect
- Magifying technology like STM and their principle
- Other application
- Hazards behind like high pentrating power
Among them, the principle is STM is very hard as tunneling is the principle of quantum theory. When the probe releases electrons to detect the tunneling current, inversely exponentially related to the distance between object and the probe. However considering the distance between the electrons (wave) and the object is about the level of 10^-10~10^-15m, there hardly exist a barrier, or an atom as a barrier. Without the existance of barrier, simply no tunneling exist...

Anyway the principle of STM is not required in the syb. so I'm considering to skip it.