Bobbie's Blog

Boys be ambitious.

色情和艺术是近义词吗?

色情和艺术是不是一线之隔的近义词?热情和沮丧是不是两种相反的情绪?我最近对这一类问题有一些思考,想把它们整理出来。

Dancing With Julia

I have been having fun with the Julia language lately. It is a new programming language for scientific computing. You may wonder, why do we need a new language at all? Don’t we already have MATLAB, Mathematica, Python with NumPy and SciPy, etc., are’t those enough?

Well, it is true that those are awesome softwares for scientific computing, they have all the necessary functionalities and powerful libraries, and they are easy to learn. But there is a common (fatal) issue that prevents them from creating industrial quality codes – speed. We want faster speed! The Julia language is developed specifically for this.

The Holy Trinity

This isn’t about theology, but I will talk about the number three.

We love the number three. Many of our rules/doctrines consist of three parts. For example, in Christianity, there is the theory of the Holy Trinity, stating that God manifests Himself in three forms: the Father, the Son, and the Holy Spirit. I’d love to cast them into a shamrock diagram:

The key idea here is that, although there are three forms, there is really only one God.

Beamer Video Tutorial

As a researcher, I often need to make presentation slides, and want to embed movies in my slides for better illustrations. After doing a little research, I converged to the solution described in this article.

博客更新

我对最开始的两编博客内容进行了更新。因为经过这段时间的学习,我的电脑水平有所增长,回头看当时写的东西不禁发现了各种不严谨和各种 bug,忍不修补了一下。

好了,本篇的主要内容完毕,以下完全是跑题的内容,是我对这个学期所学的一门课的吐嘈,可以随意忽略。。

Fluid or Solid?

This is something I learned today from the Fluid Mechanics class in the Chemical Engineering department, class number CHE 527.

We have had the intuitive ideas about what a fluid is versus what a solid is. A solid is something that can resist shear stress, and will maintain its shape, while a fluid is something that will deform continuously when a shear is applied to it, without changing back to the original shape.

But there are many substances in the world that cannot be classified into solid or fluid with the above simple and intuitive definitions. Here are some examples:

Silly putty:

Human Brain Works Logarithmically

Do you know that our brain works logarithmically?

  1. Do this exercise:
    • Draw a number line
    • Mark $0$ and $1,000,000,000$ on the line.
    • Ask yourself a question: where is $1,000$?
  2. Many people put $1,000$ at the $1/3$ position. Note that $1,000=10^3$, $1,000,000,000=10^9$, where $9$ is triple of $3$. This implies that we perceive number logarithmically!
  3. Not only size of a number, but also weight of an object, loudness of a sound, brightness of a star, spiciness of a chili, all of these are perceived logarithmically by the human brain.
  4. Such logarithmic law is known more than 100 years ago, under the name “Weber-Fechner law” in psychophysics.

谁说英文歌词都没有深度?

上周和朋友吃饭,听着餐厅用流行歌做BGM,聊起歌词的意思。朋友表示英文歌词都没什么深度,都是很肤浅直白的句子,比如艾薇儿、霉霉、Maroon 5 的歌大多都这样。我表示不同意,只是我们不知道哪些有深度的歌词而已,就像周杰伦的青花瓷老外大多没听过,歌词写得好的英文歌咱也很多都没听过。当时我一时没想出实例支持我的论点,后来想想,不少耳熟能详的英文老歌歌词都不错,比如 Scarborough Fair, The Sound of Silence, 歌词都很棒值得细细品味。

昨天看一本并行运算的书,书的每章开头都会有一段引用文字作为引子,用来科普小历史或者纯粹增加趣味。其中关于数据依赖关系(Dependences)那一章的开头就引用了一句歌词 “I wish I didn’t know now what I didn’t know then”,来自 Bob Seger 的 “Against the Wind”。原歌词讲述了故事主角经历了很多世事之后怀念当初年轻时懵懂但拥有的那种兴奋感,现在放在“数据依赖”的语境下又多了一层玩味,看得出写这本书的几位科学家也是有感情有趣的有血有肉的人呢。

管理引用文献

管理文献对于做研究或者各种技术工程师都是很重要的事情。需要资料时要快速查得到,运用资料时要给出出处,这就要平时把文献资料整理得井井有条;尤其当文献数量达到上百甚至上千条,没有有效的管理方法简直寸步难行。

于是专业人员都会用到软件来管理文献。比如文章 How to read a book 就提到一些常用的文献管理软件(Reference Management Software)。

市面上的文献管理软件

个人测试过以下这几个最流行的软件

  • EndNote:据说挺好用,但是(1)需要花稍多一点的时间学习使用,(2)收费,差不多 80 大洋。网络 basic 版免费,但是试用了一下并不方便,也有导入数量限制。
  • Papers:据说很好用,但是收费,学生版差不多 50 大洋。iPad 版免费,但是只用 iPad 版而没有桌面版也是很不方便。
  • Bookends:优势是可以找 Amazon 上的书,不用费神想到底要连哪个出版商的数据库。
  • Mendeley:暂时觉得最好用的一个。免费。可以把 PDF 文献原文拖入软件窗口,就会帮你自动识别 citation 信息,虽然并不总是准确,但如果知道 DOI 的话可以自动更正。在 mendeley 中可以连接到本地 PDF,并且直接打开做笔记挺方便。
  • BibDesk:神器,免费,原生支持 BibTeX (BibTeX 是基于 LaTeX 的文献管理软件)。适合习惯用 LaTeX 写论文的人 (理工科写论文基本标配用 LaTeX )。就用它了!

Remark: 如果不怎么用 LaTeX 写论文的话,Mendeley 就很好用。以前大部分人都用 Mendeley,现在很多科研人员不用的原因是因为“洁癖”: Mendeley 被 Elsevier (爱思唯尔出版社) 收购了,Elsevier 在学术界变得“臭名昭著”可以参考 Wikipedia: The Cost of Knowledge,中文参考 科学网:逾万科学家联名抵制爱思唯尔