Notes & essays

Ghi chú & bài viết

Science, implementation, war stories — and counting.

Khoa học, implementation, war story — và còn viết tiếp.

2026-08-25 · 21 min

Allan variance, or how long a gyroscope can be trusted

We left five phones logging their gyroscopes overnight and used Allan deviation to work out how many minutes of heading Wheria can borrow between compass corrections.

physicswheriamath
2026-08-18 · 20 min

An inaudible sonar that watches you breathe

Sonarish's experimental breathing monitor drives the speaker at 19 kHz, listens on the mic, and reads 118 µm of chest motion out of the phase of the echo.

sonarishdspphysics
2026-08-11 · 19 min

Semantic search with no server in the loop

Sentence embeddings, int8 vectors and a brute-force cosine scan let Stashio search your saved links by meaning entirely on the phone.

stashiomathengineering
2026-08-04 · 18 min

The lab behind the Lab page

A tech-stack tour of the browser demos on the lab page, from AnalyserNode fine print to hand-shifted spectrogram pixels, built with no framework and no trackers.

engineeringdsp
2026-07-27 · 19 min

The battery budget of an always-on sensor app

Four phones on a shelf, airplane mode, screen off, and five weeks of overnight battery logs to find out what each sensor really costs an always-on app.

engineeringwheriaphysics
2026-07-18 · 18 min

Shipping the same day on two app stores

atuan explains the release train that moves five apps to two stores on the same day, with review-time numbers from the studio's own log.

engineeringstudio
2026-07-04 · 20 min

Welcome to uranashel

Who we are, why five apps exist, and how this blog explains the physics behind them — in plain language.

studio
2026-06-15 · 19 min

Why everything runs on your phone

Why parking, sleep audio, and noise meters must compute on your phone — latency, privacy, and offline garages explained step by step.

privacy
2026-05-28 · 21 min

Indoor navigation when GPS dies

When GPS fails underground, Wheria walks you back with steps, heading, and pressure — how sensor fusion works and what we honestly tell users.

wheriaphysics
2026-04-10 · 20 min

Sound that never repeats

Your brain detects loops; Estua generates fresh ambient sound every night. How real-time synthesis at 48 kHz replaces repeating rain clips.

estuadsp
2026-03-22 · 18 min

Designing in strict monochrome

Why instrument apps stay black and white, and how we fight SwiftUI blue and Material purple without sacrificing readability.

design
2026-03-08 · 19 min

Barometers and parking floor math

Pressure changes as you descend — the hydrostatic idea behind guessing B2 vs B3, and why weather and elevators complicate it.

wheriaphysics
2026-02-18 · 22 min

Magnetometers and compass nightmares

Magnetometers in steel garages see a distorted Earth field. How Wheria calibrates, when it trusts the gyro instead, and why we warn instead of guessing.

wheriaphysics
2026-02-04 · 20 min

Step detection and IMU odometry

Double integration drifts fast; counting steps does not. A clear explanation of pedestrian dead reckoning in Wheria.

wheriaphysics
2026-01-21 · 21 min

Kalman filters for parking

Combining noisy steps, heading, and pressure without panic — an intuitive tour of the filter Wheria uses underground.

wheriamath
2026-01-07 · 19 min

FFT for mortals

What a spectrum actually shows, how Sonarish builds it from microphone data, and how to read peaks from fans and motors.

sonarishdsp
2025-12-14 · 18 min

A-weighting and decibels explained

Decibels, A-weighting, and LAeq explained so your phone measurements mean something next to real-world noise limits.

sonarishphysics
2025-11-28 · 20 min

Machine fault diagnosis via acoustic baseline

Machines hum in patterns; Sonarish lets you save a healthy baseline and compare later — acoustic diagnosis without cloud AI.

sonarish
2025-11-10 · 18 min

Sleep, waves, and why your brain likes surf

Why surf-like 1/f noise soothes sleep, and how Estua mimics it with slow modulation instead of a beach recording on repeat.

estuaphysics
2025-10-22 · 22 min

Phyzix — 100+ physics instruments in your pocket

Turn the phone into a physics lab: live sensors, graphs in SI units, simulations, and bilingual classroom use.

phyzixeducation
2025-10-08 · 20 min

Sensor hacking 101

Accelerometers measure specific force, not “zero when still.” A gentle primer on what each phone sensor really reports.

phyzixphysics
2025-09-20 · 19 min

Shipping iOS and Android at the same time

SwiftUI and Compose, two codebases, one physics core — why we ship iOS and Android together and how we keep them aligned.

engineering
2025-09-05 · 20 min

Why GPS lies to you

Line of sight, multipath, and concrete — a physics-first explanation of why your map dot lies in parking garages.

wheriaphysics
2025-08-18 · 18 min

Nunito on every pixel

Typography is part of measurement UI. How Nunito stays consistent across SwiftUI and Compose, and what the OS still controls.

design
2025-08-02 · 21 min

Life on the audio thread

Real-time audio has hard deadlines. The rules Estua follows so sleep sounds never click at 3 AM.

estuadsp
2025-07-15 · 19 min

Stashio — saving the internet without losing your mind

Save links and PDFs from the share sheet, find them later — Stashio’s capture and search flow, including when cloud helps.

stashio
2025-06-28 · 22 min

CS + Physics → app studio

Computer science plus physics shaped uranashel — not as credentials, but as a way to ask what sensors mean before writing code.

studiophysics