64 lines
2.4 KiB
Markdown
64 lines
2.4 KiB
Markdown
# Drag Auto — Drag Force Analysis
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Loads particle centroid tracking data, lets you interactively define movement regions, and computes drag force vs. displacement with a linear fit per particle and direction.
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---
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## Workflow Overview
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1. **Load CSVs** — Reads all `*.csv` files from a folder (output from `Drag Force Particle Tracking Automatic.ipynb`). Automatically detects the number of particles from the column count (3 columns per particle: `cx`, `cy`, `r`).
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2. **Set regions (slider cell)** — For each speed, an interactive plot shows the x-position traces for all particles over time. Use the three sliders to define:
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- **Stationary** — frames where the stage is not moving (baseline)
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- **Movement 1** — first direction of stage movement
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- **Movement 2** — second direction of stage movement (return)
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Click **Confirm All & Continue** when all speeds are set.
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3. **Analyze** — Computes the mean displacement of each particle relative to its stationary baseline, and the expected Stokes drag force at each speed. Fits a linear spring constant `k` (pN/µm) per particle per direction through the origin.
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---
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## Key Parameters (Analysis Cell)
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| Parameter | Description |
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|---|---|
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| `folder` | Path to folder containing `{speed} mms.csv` files |
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| `PIXELS_PER_MICRON` | Pixel-to-micron conversion factor |
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| `ETA` | Fluid viscosity (Pa·s); default: `0.001` (water) |
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| `R` | Particle radius (m); default: `1e-6` (1 µm) |
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| `TRIM` | Frames trimmed from each edge of a region to remove transients |
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---
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## Output Plot
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- **Color = particle** (each particle gets a unique color)
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- **Filled circles** = Direction 1 (Movement 1), **open circles** = Direction 2 (Movement 2)
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- **Solid fit line** = Direction 1, **dotted fit line** = Direction 2
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- Separate origin-constrained fit per particle per direction with 95% confidence interval shading
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- Printed spring constant `k ± σ` (pN/µm) for each particle and direction
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---
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## Input File Format
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CSV files must match the output of `Drag Force Particle Tracking Automatic.ipynb`:
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- No header row
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- Filename: `{speed} mms.csv` (e.g. `0.25 mms.csv`)
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- Columns: `cx0, cy0, r0, cx1, cy1, r1, cx2, cy2, r2` (3 per particle, up to 3 particles)
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---
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## Dependencies
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`numpy`, `pandas`, `scipy`, `matplotlib`, `ipywidgets`, `ipympl`
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Install missing packages with `pip install <package>`.
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---
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## Tracking Data Source
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Generate input CSVs using `Drag Force Particle Tracking Automatic.ipynb`.
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