Build a Raspberry Pi-based air quality monitoring system with gas and dust sensors, plus a DIY air purifier using a box fan and MERV 13 filter.
从鸡翅膀谈起——无人机的空气动力学（下）
续篇：固定翼与直升机/四轴的稳定性差异、上反角原理、机械效率对比，以及为什么不太看好载人四轴的发展前景。
从鸡翅膀谈起——无人机的空气动力学（上）
无人机空气动力学入门：机翼升力原理、失速现象、螺旋桨工作方式、周期变距器的作用，以及为什么四轴有速度上限。
Easy EC2 Sharing (While You Pay the Bill)
Simple web system for sharing EC2 access while the bill payer maintains control—team members can start instances via web interface with authentication.
Easy and cheap cluster building on AWS
Build cheap compute clusters on AWS using spot instances: automated system configuration, sshfs file transfer, and GNU parallel for job distribution.