倫敦奧運

台灣這屆奧運1銀1銅，相較於台灣2000年以前的成績也不算太差了。而南韓這屆亮眼的成績(目前12金7銀6銅)，可能才是最讓大家氣餒的。其實一個國家只要願意投入大量資金，要在奧運衝刺一下獎牌數目，也非難事。不過，我覺得雖然大家抱怨歸抱怨，人們心裡是不情願花這個錢的。再來，台灣社會的基本氛圍(公平原則)也不可能讓政府像南韓一樣集中資源在少數的運動項目。話說回來，我不支持以獲獎數目為導向的政策或政府。因為奧運獎牌的數目與國民平均的體能素質沒有直接的關係。平均地增進國民的健康，比追求看來風光的數字更重要。

最後，來看一下印度這個大國的表現吧。印度目前一銀四銅，以其國力人口，這豈只是差強人意而巳。不過人家不在乎啊。前陣子看了"三個傻瓜 Three Idiots"，發現印度的教育體制和台灣頗為相似的，一樣地對成績分數的追求過於汒目。不過，不同的是，印度對體育競賽的漠視倒是心口一致，我覺得這也是一種忠於自我的聰明與可愛吧。

Trip to Aroggne

It takes two and half hours from UIUC to Argonne by car, but by train I spent eight hours.

Departing 10:14 from terminal Champaign, Amtrak is by far the best choice commuting between Champaign and Chicago. I happened to met Conner with his bike also on his way to Chicago. He is actually leaving States a few days later.

We arrived at Union Station at one O'clock and then we went to MacDonald for lunch. This one on Ohio St. is undoubtedly the most luxurious one on planet. Conner left around two. Hanging out with my magazine until five o'clock, then I walked back to Union Station to take Metra.

When I were standing in front of Union Station staring at the time schedule of trains, a black man approached and said if I need some help. I kind of hesitated and said I just took a look at these schedules. I said that without even turning around to look at him. He said " Just trying to help, I mean you no harm." and left.

I felt bad actually afterward because maybe he really just wanted to help and I acted like I am afraid of him to begging me for money. Although it happened to me several times that they did so, I should not have behaved this way. From now on, I should always presume they are just kind and then we'll see.

Anyway, I took Metra to Argonne. This train is also cozy and kind of old-fashioned.

At six o eight, I arrived at Lemont station 10 min. southern to Argonne.

New York coincidence

I wanna wake up in a city, that doesn’t sleep
And find I’m king of the hill - top of the heap

If I can make it there, I’ll make it anywhere

It’s up to you - new york, new york

Song of Frank Sinatra, the best one to represent this big apple.

It's New York where anything could happened.

Chia-Wei and I were lucky to have his friend, Lin, providing accommodation in Harlem near Columbia University.

Unbelievably it so happened that the roommate of Lin is found to be the roommate of Chia-Wei in senior high. How unlikely this is.

And in the evening of New Year's Eve I were wandering alone along 8 Ave seeking a crack to sneak into Time Square. It's snow raining, not too cold yet not too comfortable. Chia-Wei and Lin had been in Time Square long since 2 o'clock, which is too crazy for me to follow. I took a break in a square in front of a building where I bumped into a classmate of mine in college. Gladly accompanied, we counted down the year together in the Broadway and 57th where Time Square was sparkling far in the end.

After visiting NYC, I think life there would not be too cozy. It's crowed and dirty in general. On the other hand, one could enjoy himself/herself by the best entertainments there, luxurious or not. What's the catch? Money, undoubtedly.

People come to New York City to go after success but leave after they succeed. Maybe that's why it's so dirty. It's home to nobody and nobody care. A temporally residence only it is. Wealthy dirty of a kind.

Three months passed

It's been three months since I had posted my last article on blog.

Three months ago, I passed the Doctor candidate qualifier exam. I believe that would be the last important written exam of my life. I also wondered if that was my most hard-studying summer ever.

This summer vacation is composed of three stages.

The first stage is the first month of it. I went back Taiwan living with my families.

The second stage began from my coming back to USA and continued through the Friday two days before the vacation ended. It's qualifier preparation days.

The third stage only had one weekend. My summer break finally started and came to an end.

And another three months passed. Time flies.

night without computer

Since I wasted too much time with computer, I decided left my laptop in office over night.

After dinner, about 7 thirty, I went back to my room. Instead of sitting down and turning on the screen immediately, I idled for a while. It seemed to me that I am kind of lost.

Nothing came cross my mind, I lied down on bed.

Gosh, what's the meaning of getting rid of computer if I just slept over the night instead. So, should I throw away my bed as well?

Finally, I made up my minding studying the qualifier material. Not until 9 o'clock, I can't stand doing this. My patience is getting short. I grabbed a novel.

Ten thirty, I stopped to exercise.

I did do a lot of things tonight. Without a computer, I felt the leisure and freedom of using time. A little bit bored, though.

戒咖啡第二天

感覺今天對咖啡的慾望消弱了不少

肚子也比較正常了

但雖然是這樣說

下午還是有偷喝一罐可樂來解饞

計劃上禁咖啡的天數是兩天

所以從明天開始我要回復咖啡咽的日子

戒咖啡一天

由於肚子不舒服一陣子了

昨天決定不管如何都不能再喝咖啡了

也不能喝茶

果然，「戒」是不容易的

一整天一直冒出各種念頭、藉口：

「戒咖啡應該循序漸進。先從早上不喝咖啡好了……下午喝可以吧」

「不然Latte好了，Latte比較沒那麼刺激」

……

最後還是都忍住了

恭禧

陽光

陽光超爽朗的

一整個想去海灘

光是為了這陽光

就讓人不想離開美國了吧

練拳

決定昭告天下

這樣比較會有壓力

每天晚上九點

放鬆功、站椿二十分鐘、水肢二百六十下

真是一個很懶的工課表，但總比沒有好

新室友兩個半

第一次看見嘉偉時就有點面善，原來他也是清大工科系畢業的(04級)，很巧。

他在台大唸電子所，不過來UIUC唸的是Finance.

June是韓國人，唸生物方面的大學部。很和氣的一個人，和Michael一起上教會。口頭禪是mess up。

Michael是Matt的combo friends，華裔美國人。異常活潑。雖然晚上常常在客廳大笑害我沒辦法睡覺，但的確是一位相當好的人。因為常常過來我們家，所以是半個室友。口頭禪是fail。

再介紹一下老室友吧

Matt是台大電機所來的交換學生。萬人迷。今年七月就會回去了，但再過一兩年就會回來美國唸博士了。

Adrian，電機博士生三年級。每天早上六點半起床，晚上十二點睡覺。

旅行

大學畢業那年和好友們去新竹湖口玩

途中去朋友姑姑家坐了一下

聊天中不經意聽到的「愛玩」兩字

卻像一把鑰匙開啟了我未來四年出外旅行的日子

當下我默默地下了決定……

///

北京、長春、大阪、京都、神戶

印象很深的是第一次從大阪回來的時候

老師說我有改變

自信和講話的氣勢都不一樣了

原來旅行有這種效果?

///

北京、長春、大阪、京都、神戶、上海、芝加哥、西雅圖、舊金山、波士頓

去旅行像是在吃藥

憂鬱藥

需要它在下沉中的心情中拉一把

///

北京、長春、大阪、京都、神戶、上海、芝加哥、西雅圖、舊金山、波士頓、東京、山形、日光

在台北東區

忠孝東路可能有走過九百九十九遍了

就像呼吸一樣沒有特別的想法

但是轉念一想

如果開始想象我正在旅行

在台北旅行

那車外的街景就變得有趣起來

好像我在國外似的

如果可以的話

把心眼打開

讓每一刻都在旅行

///

北京、長春、大阪、京都、神戶、上海、芝加哥、西雅圖、舊金山、波士頓、東京、山形、日光、台北

桃園機場

去過那麼多國外的機場後
才發現我們的桃園機場真的是有待改善
網路上巳經有了相當多的討論

不過我覺得我們機場有兩點倒是相當可愛
一、免費的無線網路
二、免費的行李推車
在國外的機場，這幾乎都是要收費的

但我覺得最可愛的還是入關處一整排的「持中華民國護照」通道
像是家門
在展開雙臂歡迎國人回家

山形第一天

Last time I visited Osaka, I made a conclusion that Japanese girls are not that pretty. They are merely cute, but not pretty. This fact really disappointed me since I had always expected that there should be many beautiful girls in Japan because they are usually pretty in Japanese drama.

But this time in Tokyo, I found these Japanese dramas did not lie. 

In Tokyo station, beautiful office ladies are so many. Maybe the most pretty ones are always gathered in the largest city. Just like the situation in Taipei of Taiwan. The pretty comes and goes. I really want to enjoy appreciating them but I can't do that too apparently. Because my parents are with me. I better be a good boy XD.

And I think this is the most important thing of the day.

Way back home

As I had expected, it's a terribly long trip home.

Getting up at eight, I went to Illini terminals at nine to take Amtrak train. To my disappointment, the train delayed for one hour. Not until today, I have seen the amtrak as the most reliable transportation to Chicago( I wondered if there is an grammar error of this sentence). This reminded me the rail trains in Taiwan which delay all the time. I wondered if I could ask for a ticket fee return.

And then, I took CTA subway to O'Hare airport. I don't know it's because of my unluckiness or what, the train stopped after one or two stops and all passengers were requested to take off. And after several minuets, all passengers were asked to take on the very same train again. Thank god I had pretty adequate buffer for transferring.

With two McDonald's meals for lunch and dinner, I found I always choose McDonald's in airport.

And now I am in LA airport. This is the most uncomfortable airport I have ever been in USA. It's crowded. Many places are under refurnishing or something( or supposed to be?). It's dark in the check-in hall and , especially, in the food court.

Finally, I were home. To my curiosity, I did not feel very excited. Further more, the humid and warm air made me uncomfortable. Maybe I am really not a homesick type of person I think.

class review NPRE 441 5/4

Regulations
ICRP 26/30 Philosophy( dose equivalent (rem or Sv) and effective dose equivalent,Stochastic and Nonstochastic effect.)

Because different radiations cause different biological effect, so we define:
dose equivalent is equal to dose by quality factor.

Because different tissues respond differently to radiations, so we define:
effective dose equivalent is equal to dose equivalent by tissue weighting factor W(tissue). It only applies to stochastic case.

For nonstochastic case, we consider a 50 year organ dose.
For stochastic case, we consider doses upon whole body.

we also have limitation on intake dose( also stochastic and non-stochastic).

NPRE 441 5/1

Photon shielding:

Secondary protection barrier( for scattered photons and leakage radiation), depending on ratio of scattering to incident radiation scattering field size, exposure rate on scatterer....

Distance between "source and scatterer" and "scatterer and objective place" are related to allowable value as well as occupancy factor and others.

Eventually, I want to find the required barrier thickness. Usually we would find K or B, attenuation factor) first, then we can use some table or figure to find the corresponding required wall thickness.

Beta ray shielding:

Gotta consider both electrons  and bremsstrahlung radiation. To calculate the bremsstrahlung part, we first find the fraction of energy emitted as bremsstrahlung. And then to find the required thickness of wall. 

Neutron shielding:

For fast neutron.

Use table 9.5, we could find the relation of neutron energy and neutron flux that cause a 0.01 Sv/h.

Once we know the attenuation cross section, we can know the flux distribution of neutron in the wall. At the end point of wall, the flux of neutron should equal the required value. This is, we could find the required wall thickness.

For thermal neutron.

Gotta consider gamma capture reaction. Usually, we assume a uniformly distributed gamma source. Then we have equation to fine the dose rate on the surface of the sphere. 

So, we have dose rate from fast and thermal neutrons and gamma rays. One way to reduce gamma ray radiation, we could add some lower energy emitter like boron(0,48Mev).

Spring is coming

When flower blooms, the spring is coming.
I came to USA in summer and now it's spring.
So, I have experienced all of four seasons in America.

This is photo I took this afternoon.

This is in summer, the first day I came to UIUC.

This is in fall.

This is in winter

NPRE 441 4/29

When it comes to photons radiation protection, we should not only consider the originally incident photos but also should take care of the scattered photons and characteristic x-rays that follow because these following photons contribute to the dose as well. A build up factor is called for counting this fact.

Build up factor depends on (1)source (photons) energy (2)the distance traveled and (3)the nature of the medium. With build up factor, we could calculate the dose more precisely.

In order to satisfy the Requirements for structural shielding for X-ray facilities, we consider the following factors. (1)the maximum voltage that X-ray tube is used. This is related to the incident photos energy. (2)maximum current(mA) of beam current, which relate to flux of radiation. (3)work load of the X-ray tube. (4)the use factor. The fraction of workload that the beam is pointed directly to. (5)the occupancy factor.

class review NPRE 455 4/28

By operating integration of energy over E_g to E_g-1 on energy dependent neutron diffusion equation, we can get definitions of some group constant like group absorption cross section, group scattering cross section weighed by flux.

For diffusion coefficient, it's weighed by gradient of flux, not flux itself. It is reasonable because the diffusion depends on gradient of flux, not flux.

It's interesting that we have flux dependence( or gradient of flux) , which we have not known yet, in the definition of group constants. This is called a recursive problem. To tackle this, we assume the spatial part and energy part of flux is separable. And then, we further assume that we know the energy dependence. For example, we assume a Maxwellian-Boltzmann distribution for thermal neutrons.

Since the difficulty of group parameter constants are already solved, we can easily write down the two group diffusion equation. What following is similar in one group. We will have two kind of problems, source problems and criticality problems.

class review NPRE 455 4/23

Topics: Neutron transport equation

Starting from expanding flux dependence to even include direction and energy. ø( position, energy, direction, time), we write down the neutron balance equation. And then, omit direction dependence first and focus on energy dependence from now on.

ø( vector r, E, t)

Notice that not only flux has a energy dependence, some parameters like cross section, velocity or diffusion coefficients are also energy dependent now.
Some changes in neutron balance equation:
1. Fission neutrons come from fission reactions of neutrons of all energy.
2. Losing neutrons by scattering from objective energy to any other energy.
3. Gaining neutrons by scattering from any other energy to objective energy.

Then we define g group of flux ø_g by integrate the flux from E_g to E_g-1. By this, we have the neutron balance equation of group g.

For example, we had taken a look of two group, G=2. Some simplifications are used like up-scattering, fission neutrons being all fast