My DokuWiki private:writeups

private:writeups:capoeira

Anonymous (anonymous@undisclosed.example.com) — 2022-09-25T17:09:23+00:00

I find capoeira to be a beautiful, challenging, and fulfilling activity. However, it is somewhat factious, not well documented, and difficult for a beginner to pickup. In particular, I struggle with the non-unified naming of the various moves between capoeira groups. (Give example). The goal of page is to document most every capoeira move (defense, attack, movement, etc) and present them in a way that makes it easier for a beginner to better learn the moves and the names associated with them…

private:writeups:cncjs

Anonymous (anonymous@undisclosed.example.com) — 2020-10-04T14:51:59+00:00

Install CNCJS Raspberry pi Setup a fresh install of raspian on a raspberry pi. Enable ssh, vnc, etc. as usual. Download cncjs. Note this site appears to have the latest code and NOT the intuitively named . Install cncjs Follow the directions on .

private:writeups:dmd

Anonymous (anonymous@undisclosed.example.com) — 2020-11-27T19:11:19+00:00

Assume we start with 2D data matrix, $Z$, with dimensions R and T. (R is space, T is time). Define $X=Z(t)$ and $X'=Z(t+dt)$ Perform SVD on X to get spatial basis functions. $U,S,V^T = \text{SVD}(X)$ Define $A=(U^T \cdot X') \cdot \left (\frac{V}{S} \right)$ Find eivenvalues and eigenvectors. $\lambda, v = \text{eig} (A)$ spatial structure. $Bt = \left(X' \cdot \frac{V}{S} \right) \cdot v$ $\omega = \frac{ \text{log} \left| \lambda \right| }{dt}$ time evolution. Vandermonde, $M = …

private:writeups:hallthrusters

Anonymous (anonymous@undisclosed.example.com) — 2020-08-06T15:59:34+00:00

Tiered understanding of Hall thrusters Tier 1 - Simplest All rockets (chemical, electrical) generate thrust by throwing out particles at high velocity out their rear. Electric propulsion systems, such as Hall thrusters, use electricity (instead of chemical combustion) to create thrust. $ \frac{E_z \times B_r}{B_r^2}$$E_z=-\nabla_z V$$E_z=-\nabla_z V$$I_b$$I_e$$B_r$$\nabla_r B_r$$E \times B$$B_r$$-\nabla_r B_r$$E_z \times B_r$$\nu_e n_e v_{ez} m_e + e n_e E_z + j_{e\theta}B_r + \nabla_z p_e =…

private:writeups:hamradio

Anonymous (anonymous@undisclosed.example.com) — 2020-07-22T13:02:07+00:00

Digital modes JS8 software : JS8Call 20 m band : 14.078 bandwidth : 50 Hz duration : 15 seconds cycle details : WSPR software : WSJT-X 20 m band : 14.0956 + bandwidth : 6 Hz duration : 120 seconds cycle (115 second duration) details :

private:writeups:photobox

Anonymous (anonymous@undisclosed.example.com) — 2021-01-01T15:32:25+00:00

The directions here are what I followed to turn my raspberry pi and 7“ pi screen into a photobox. Step 1 - Setup Install Raspiberry pi OS (full) onto an SD card and install in your Pi. Bootup, run raspi-config, and get everything setup the way you like it.

private:writeups:plasmaimpedanceprobes

Anonymous (anonymous@undisclosed.example.com) — 2020-07-02T14:17:39+00:00

Plasma Impedance Probes (PIPs) What it does Measures * Plasma frequency [Blackwell2005] * Electron density (by measuring plasma frequency) [Blackwell2005] * Plasma potential * Collision frequency Methods PIPs can be operated in a number of methods

private:writeups:plasmaphysics

Anonymous (anonymous@undisclosed.example.com) — 2020-07-16T15:00:24+00:00

This page is intended as a “cheat sheet” or brief overview of basic plasma physics concepts. Plasma viscous flow (electrical conductivity and diffusion) When forces are applied to a plasma (or any fluid) in the presence of a damping force (viscosity, friction, collisions, etc), the plasma achieves a steady-state velocity (i.e. terminal velocity) with the form$\left< v \right> = \text{constants} * F_{orces}$$J= n \mu F_{orces} = \sigma \frac{F_{orces}}{e} $$\mu$$\sigma$$ J = \sigma E $$ J =…

private:writeups:svd

Anonymous (anonymous@undisclosed.example.com) — 2020-10-18T21:25:47+00:00

Math $$X_{(m,n)}=\begin{bmatrix} | & | & & | \\ x_1 & x_2 & \dots & x_m \\ | & | & & | \end{bmatrix} =U\Sigma V^T =\begin{bmatrix} | & | & & | \\ u_1 & u_2 & \dots & u_n \\ | & | & & | \end{bmatrix} \begin{bmatrix} \sigma_1 & & \\ & \ddots & \\ & & \sigma_m \\ & & \end{bmatrix} \begin{bmatrix} | & | & & | \\ v_1 & v_2 & \dots & v_m \\ | & | & & | \end{bmatrix}^T $$ where $n$ is the number of points in each $x$, and $m$ is the number of $x$ values. This can b…