A mini recipe to fit arbitrary models to data using lmfit in Python
6 mins
In this blog post, we navigate through an unorthodox yet effective method of building models using the lmfit library, a wrapper around scipy's fitting routines. The article dives into a hands-on approach for fitting noisy data with a custom-defined Gaussian model, while suggesting that the conventional wisdom of lmfit isn't the only path to success. The tutorial initializes by installing lmfit and swiftly moves to crafting a function for the Gaussian model, which involves defining an objective function to decipher the best parameters for data fit. It guides the reader through generating synthetic noisy data, plotting it for visual aid, and conducting the fitting process. Through this procedure, a parameters are constructed and optimized to fit our model to the noisy data, followed by a presentation of the fitting report. Finally, the results are visualized, and the article concludes by discussing the advantages of this method, especially when dealing with complex or iterative models. The full code for the exercise is accessible in a GitHub GIST, allowing readers to directly engage with the material covered.
Using ancient PHP versions from FreeBSD ports with suphp
3 mins
This concise article provides a detailed guide on installing and running multiple outdated PHP versions on a FreeBSD system using suphp. It covers essential steps such as retrieving specific ports tree revisions, configuring distinct installation paths to prevent version conflicts, and setting up suphp for handling different PHP versions. Emphasizing strict security precautions, the article strongly advises against using this setup in public-facing systems and suggests its use solely for isolated, non-public applications.
Using the RaspberryPi GPIOs on FreeBSD
5 mins
Mini summary and recipes to use the RaspberryPi GPIOs from FreeBSD
The most simple Difference of Gaussian image pyramid with OpenCL
22 mins
The following blog article summarizes a quick implementation of a Difference of Gaussian (DoG) pyramid as approximation of a Laplacian of a Gaussian pyramid. It does not utilize optimizations so performance (around 10ms for a simple 6 octave pyramid) is rather low.
Assigning unique device names for CP2102N serial port devices on FreeBSD
5 mins
Just a short recipe on how to get unique device names for CP2102N serial or RS485 to USB adapters even when they're renumbered by the operating system.
Triggering Jenkins build from locally hosted git repository using the post-receive commit hook
6 mins
A short summary on how to trigger Jenkins jobs by executing a post-receive commit hook in a git repository
Using the CP2102N USB to UART bridge
22 mins
A mini summary (mostly for my own reference) on how to use the CP2102N USB to UART bridge in minimal configurations. This article explains the different powering schemes, lists some of the uncommon functionality and shows the design of a simple USB to TTL serial and USB to RS485 half duplex interface board. In addition it contains a short introduction on how to configure the USB chipsets later on.
Some simple image filters by convolution in Python and OpenCL
71 mins
This short article contains a summary about image filters and how one can realize them. It will contain a short reminder of how convolution works, what separable filters are and some example of image filters and their (most inefficient but direct) implementation in Python. In the end it will also show how one might naively implement convolution in OpenCL to increase performance in comparison to the naive Python implementations shown. This article provides one with a small playground to quickly try out separable image filter kernels and execute them on the GPU using pyopencl from a Python testing environment.
Towards Driving Quantum Systems in Cryogenic Environments with the Near-Field of Modulated Electron Beams
1 min
Presented at the 13th ASEM (Austrian Society for Electron Microscopy) workshop: Coherent electro-magnetic control of quantum systems is usually done by electro-magnetic radiation - which limits addressing single selected quantum systems, especially in the microwave range. In our proof of concept experiment we want to couple for the first time the non-radiative electro-magnetic near-field of a spatially modulated electron beam to a quantum system in a coherent way. As the quantum system we use the unpaired electron spins of a free radical organic sample (Koelsch radical - α, γ-Bisdiphenylene-β-phenylallyl) that is excited via the near-field of the modulated electron beam. The readout of the spin excitation resembles a standard continuous wave electron spin resonance experiment and is done inductively via a microcoil using a lock-in amplifier. In the long term this experiment should demonstrate the feasability of coherent driving and probing of quantum systems far below the diffraction limit of electro-magnetic radiation by exploiting the high spatial resolution of an electron beam.
Using pycryptodomex for encryption and signing (PKCS1 OAEP and PSS) in Python
18 mins
This is a short summary or rather recipe collection on how to use ```pycryptodomex``` for some simple encryption and decryption procedures using RSA with the OAEP schemes from ```PKCS#1``` as well as signing and verification routines using the PSS scheme.
