Sudoku mania

I like playing sudoku, and I suppose a lot of you out there like it as well. Well, here are a few questions that I proposed when I first starting to play sudoku. However, I havn't find answers to any of them. If you have a proof, send it to me.

Before I start, let's have 1 definition in place. A sudoku solution is a sudoku with all the entries filled and valid.

1. Does there exist a 3D sudoku solution?! 3D solution meaning, a 9x9x9 cube, such that the 27 slices of 2D sudoku (9 slices of sudoku on each direction, and 3 direction) are all valid sudoku solution. My quess is no, since the restrictions seems too hard. but that's only a wild guess.

2. Given a sudoku solution, define the number min_entry_needed, to be the minimum number of entries needed to gaurantee that particular sudoku solution. Of course, if one knows all 81 entries, then he has the solution. So 81 can't be the min_entry_needed for any sudoku solution. And of course, knowing only 1 entry is not going to get a unique solution. So the sudoku you see on newspaper, the entries that was given, will gaurantee a unique solution. But it might not be set of the minimum entries for that particular solution. Even more interesting, I might use other entries to greatly reduce the number of entries needed to get that solution.

So if we look at the set of all sudoku solution, on average, what is this min_entry_needed?

3. This one is even harder to describe. Suppose we come up with a set of "contradiction rules". For any un-finished sudoku, can we always apply this set of rule, and get a new entry. (So we will apply this set of rules again, to the sudoku with the newly added entry. Eventually, we'll get the solution). I think an example is needed to make this clear.

Suppose the set of rule only contains the rule "given a 3x3 square, one can only have the number 1-9 exactly once". So if you apply this set of rule to a sudoku, that has 8 numbers in all 9 of the square, then eventually you'll have the solution. But of course, this one single rule is not going to solve any sudoku. So, can anyone come up with this set of rules?

Mug mania II

A couple of my friends are teaching in the universities in Taiwan. So here are mugs for them. The logo mimics the "I love NY" logo, except it says "I flunk students", where "flunk" replaced "love". Originally we were going to print the logo on a t-shirt and gave to my ex-roommate last year, but never got a chance to do so. The form of the mugs are not so interesting, cause I was in a hurry and did not throw the mug carefully. But I did learned something from these mugs. At least I think I learned something. These mugs are made out of porcelain, and I think I know better about the property of porcelain. The stamps I used are cut from 79 cents form visor from Walmart.

Now I am officially tired of mugs. I am happy with the couple of forms that I liked, and can re-produce it most of the time. so unless I come up with other slogans, no more mugs for me..

Mug mania

This mug is made to express the Taiwanese identity inside me. The characters basically says, "I am a Taiwanese", well, with an attitude. The glaze used is from Tracy Thomas, and we call it Tracy's blue. I had made so many copy of this mugs and giving away to my Taiwanese friends. Since this town is flooded with tons of brain dead Chinese, I hope to sell this mug at the Taste of Champaign to see how the Chinese react to this slogan.

My 2 coffee roasters

I modified two popcorn popper for coffee bean roasting a while back. Since someone asked me to share the photo and how I made it, here comes.

先來說第一台好了:

成本價 (美金)
玉米花機: $10.00
兩個電燈開關: ~$6.00
變電器: $10.00
保險失和保險失座: ~$3.00
木頭: 別人家丟出來的床架 免錢
腳和腳座: ~$8.00

壞處: 瓦數不太夠, 1200W, 一次只能烘差不多 75g
好處: 因為量少 降溫快 從接近二爆到室溫 大概只要30-60秒, 沒那麼難看


我把他做成可以分開成兩部分 像這樣:

上半部:

把玉米花機整個拆了
防火災裝置剪掉 才能上高溫
因為要把馬達和熱線圈給分開來 所以麻達用的小線圈也剪了
這一不份網路上有一大堆資料 如果看不董 再問我好了

用木頭做一個口字型 大小要符合玉米花機大小
切 45 度角 再用白膠黏起來
再底下鑽四個洞 放腳 我把其中一隻腳偏了一點 這樣就不會插錯洞了
兩隻腳是風扇 兩隻腳是電熱圈


下半部 我不想拆開了 反正裡面也沒什麼特別的
先做一個箱子
就只裝了變電器 把 120伏的交流電 變成 18伏的直流電 給馬達用
圓的電燈開關 是控制風的大小
另一個就是電熱圈的開和關

這是腳座 鑽洞從裡面鎖上 要能和那四支腳剛好隊到
因為是在木工房做的 我是拿木頭用的白膠 在四支腳下面點一下 放到木頭上 就會出來四個點
再用這四個點去鑽洞


這是保險司座 用修邊機做一個小凹曹 再把保險司座鎖進去 線再拉進去裡面
電源線是用電腦的電源線



這是做來收集銀皮的


把拆下來的玉米花機 上面那個面板 倒翻過來
再把開口 修成可以卡在主機上的大小
再鑽幾個洞 讓篩麵粉的東西 可以倒放 卡住


這樣就大功告成了
基本上 都是在木工房做的 如果你會用那些木工機器的話 大概一個上午就可以完工


第二台:

玉米花機: ebay 標的, ~35
要買第一代的 才是高瓦數 風速大 可以烘相對上比較大量 150g


測溫器: 這個是我逛 ebay 找到的

它可以把溫度 經過 rs232 輸出來 所以我只要寫個程式 就可以每一秒就去讀依次溫度
然後他有一支接腳 可以外接開關 就可以控制那個開關了
因為這個瓦數高 溫度上升快 所以可以用這支接腳 如果溫度太高 就把熱線圈關掉幾秒 再開
這樣就可以控制溫度了
這個看起來是工業用品 應該是裝在大型爐子 像燒陶用的爐子
新的要 $325.00 這個是拆下來的舊的 大概太冷門 沒人和我搶 只花了 $25.00 爽


這一台現在是陽春版 手動控溫
現在只是湊合著用 終極目標是要用電腦控制
只不過我講了一年了 還是懶的動工把電腦的部分加進去
他的風扇馬達 是 120伏交流電 所以也不用變電器
我從壞的電腦電源 拆下兩個開關 因為瓦數夠 我在烘的時候
就把風扇一直開著 然後把電熱圈 開開關關 來控制溫度


我現在都用第二台 量比較多 可以喝快到一個禮拜
剛好烘了一批

收集來的銀皮 不會亂飛


我用手沖 所以一爆過後 還沒到二爆 就把熱線圈關了 只用風扇降溫 大概要2-3分鐘


後面放香料的架子 也是用同一批木頭做的

如果你喜歡 DIY 的話 我覺得這個是蠻不錯的 project
不過像第二台的原料 大概就要靠運氣了