app

VT Resistance

VT Resistance estimates cathodic and anodic steady resistance from a biphasic voltage transient and reports the mean of their absolute values.

Requirements And Launch

The app requires a chrono DTA curve with valid time, voltage, and current columns.

labkit_VTResistance_app

Inputs And Batch Behavior

Add one or more chrono .DTA files. The transient session decodes and analyzes the registered batch so shared setting changes update every result together. No electrode-area normalization is performed because the reported quantity is electrical resistance in ohms. Saved projects preserve source order and portable identity through removal, later additions, and reopen.

Basic Workflow

1. Add files and select a representative transient.
2. Choose pulse detection, steady-window policy, and voltage definition.
3. Inspect detected phase windows and current/voltage traces.
4. Review cathodic, anodic, and average resistance.
5. Export the batch result CSV.

Analysis Parameters

The center-60% policy uses the interval from 20% to 80% of each detected phase to reduce onset and offset transients. Plot marker and shading choices affect display only.

Calculation Semantics

After finite-sample filtering and pulse detection, the app calculates median current and voltage in the chosen cathodic and anodic steady windows. The cathodic baseline is the median pre-pulse voltage and the anodic baseline is the median post-pulse voltage, with explicit finite fallbacks.

Baseline-corrected mode uses:

R_cath = (V_cath,steady - V_cath,baseline) / I_cath,steady
R_anod = (V_anod,steady - V_anod,baseline) / I_anod,steady
R_average = mean(abs(R_cath), abs(R_anod))

Raw mode replaces each voltage difference with its steady absolute voltage. Division by a missing, non-finite, or effectively zero current returns NaN; the app does not invent a finite resistance.

Output Schema

The CSV contains source identity, steady currents and voltages, baseline voltages and windows, raw and baseline-corrected resistance fields, selected resistance values, absolute cathodic/anodic resistance, average resistance, pulse-detection method, and status. A result manifest records the common batch parameters and output role.

Use Without The GUI

[item, status] = labkit.dta.loadFile("pulse.DTA", "chrono");
assert(status.ok, status.message);

options = struct( ...
    "pulseMode", "Metadata first, then auto", ...
    "windowMode", "Full pulse median", ...
    "voltageMode", "Baseline-corrected dV/I");
result = vt_resistance.analysisRun.computeResistance(item, options);
assert(result.ok, result.message);

Errors And Limitations

• At least five finite T, Vf, and Im samples are required.
• Each selected steady window must contain at least two samples.
• Resistance is invalid when steady current is zero or non-finite.
• The result is a transient-derived estimate and does not replace an impedance model or compensate wiring/contact resistance automatically.

Related Topics

• Electrochemistry family
• CIC
• DTA Library
• API Reference