Just Facts

AA and AAA batteries differ in size, yet both have a voltage of 1.5 V. Nickel–metal hydride (NiMH) batteries are rechargeable and come in the same sizes as AA and AAA, but their voltage is 1.2 V. Mobile phone lithium batteries, on the other hand, are often rated at 3.7 V. You may have noticed these seemingly odd numbers before. Have you ever wondered why these different types of batteries all have such fixed voltage values? Today, let’s get to the root of the question.

No English version provided.

前幾天，我在攜程網上預訂了一張蘭州到青島的機票。因爲行程有變，需要改期。當我打開訂單頁面，發現「退改說明」是這樣寫的：

套餐更改：起飛前2小時之前的改期手續費按旅行套餐價收取50%，起飛前2小時（含）以內及起飛後的收取70%；

套餐退訂：起飛前2小時之前的套餐退訂手續費按旅行套餐價收取80%，起飛前2小時（含）以內和起飛後不支持套餐退訂。

In the course Network Measurement and Analysis, we were assigned a project to visualize the Internet. This project is based on the data from Macroscopic Internet Technology Data Kit (ITDK) to complete some analysis on Autonomous Systems (ASes) over the Internet.