Rico's Nerd Cluster

「离开世界之前 一切都是过程」

Linux - Udev Rules, Systemd Services, inotify

Udev Rules Systemd Services, Inotify

Udev Unix Kernel is a monolithic kernel and provides API to access these hardware. Udev is a device manager of Linux Kernel, and serves as a successor of the Unix Kernel. It handles device nodes i...

Posted by Rico's Nerd Cluster on January 7, 2018

Linux - SSH and X Window System

X Window System, SSH, Static IP

SSH Generate an SSH Key: ssh-keygen -t rsa -b 4096. This will create ~/.ssh/id_rsa and optionally sets a passphrase Copy ssh onto a remote machine: ssh-copy-id username@rem...

Posted by Rico's Nerd Cluster on January 5, 2018

Electronics - General Science Facts

Adiabatic Cooling, Centripedal & Centrifugal Forces

Adiabatic Cooling In an adiabatic process, the system does not gain or lose heat (Q=0Q=0), meaning that all changes in internal energy come from work done by or on the gas. For an ideal gas, the i...

Posted by Rico's Nerd Cluster on July 1, 2017

Literature - The Wealthy Barber Notes

Financial Literacy

Roy’s Story “We all felt bad about Roy having to put off his dream of becoming a lawyer, but deep down we knew that he was doing the right thing. You got to be there when your family needs you,...

Posted by Rico's Nerd Cluster on June 5, 2017

Electronics - General Electronics Notes

Encoders, Motors, Capacitors, IMU, Testing, Telecommunication

Electronics EEPROM EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory used in microcontrollers to store small amounts of data that must be preserved whe...

Posted by Rico's Nerd Cluster on June 3, 2017

Electronics - Embedded Systems Notes

HAL

HAL vs SAL Hardware Abstraction Layer (HAL) is software that abstracts hardware-specific details from the application or higher-level software. It provides a unified API for accessing hardware fun...

Posted by Rico's Nerd Cluster on June 1, 2017

Electronics - Communication Protocols

Encoding / Decoding, Error Checking (CRC), Base64, EtherCAT

Error Checking CRC GF(2) Math GF(2) is pronounced as “Galois Field 2”. Often used in cryptography, it’s a binary field that contains only 0 and 1 for error correction. Some properties of GF(2):...

Posted by Rico's Nerd Cluster on June 1, 2017

Electronics - EMF and Eddy Current

Electromotive Force (EMF，电动势) In short, EMF is: 1 changing magnetic field -> induced voltage It’s characterized by the Faraday’s law: \[\begin{gather*} \begin{aligned} & \epsilon = -N \...

Posted by Rico's Nerd Cluster on June 1, 2017

Math - Trace, Determinant, Frobenius Norm

Von-Neumann's Trace Inequality

Determinant $\det(AB) = \det(A)\,\det(B)$ For an orthogonal matrix $Q$ (i.e., $Q^\top Q = I$), we have $\det(Q) = \pm 1$: \[\begin{align*} & Q^\top Q &= I \\ & \Rightarrow\; \de...

Posted by Rico's Nerd Cluster on February 28, 2017

Math - Linear Fitting

Plane Fitting, Line Fitting, Isotropic Matrix, Condition Number of Covariance Matrix

Given a group of points x_i = [x, y, z], how do we find a plane and a line that best fit them? Plane Fitting Points on a plane satisfy: \[\begin{gather*} \begin{aligned} & n^Tx + d = 0 \end{...

Posted by Rico's Nerd Cluster on February 25, 2017

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