AE data (Hsu-Nielsen tests) from overwrapped composite pressure vessel type-IV

Vallen files:

- Contains the raw acoustic emission data for each of the 40 marked areas on the pressure vessel
- This data was directly recorded using the Vallen measurement system

Matlab files and h5 files:

- These folders contain processed and filtered data, with data for each measurement area provided separately within each folder type
- For each area, the data is structured into two main arrays:
-- TRAI_TIME_MAP (variable mapping): This is a numerical array with dimensions (2, N, 4)
--- The first dimension (size 2) serves to differentiate between two types of information for each measurement event and sensor:
---- Index 1 (Matlab m files)/ Index 0 (Python HDF files): Contains the Transaction Record Identifiers (TRAIs). Each TRAI is a unique identifier associated with a specific acoustic emission event detected by a sensor
---- Index 2 (Matlab m files)/ Index 1 (Python HDF files): Contains the Time of Arrival (ToA) of the acoustic emission signal at each sensor, measured in microseconds or other consistent time units from the start of the recording epoch for that event
--- N represents the total number of distinct acoustic emission measurements (events, e.g., pencil lead breaks) recorded for that specific area
--- The third dimension (size 4) corresponds to the four acoustic emission sensors used in the setup
--- For example, TRAI_TIME_MAP[1, i, j] would provide the TRAI for the i-th measurement event as captured by the j-th sensor, while TRAI_TIME_MAP[2, i, j] would provide the corresponding Time of Arrival (using Matlab)

-- TRAI_WAVEFORMS: This array with dimensions (L, M) stores the complete acoustic emission waveform data for all recorded signals.
--- L is the sample length of each individual signal (e.g., 4096 samples)
--- M is the total number of unique recorded waveforms (identified by TRAIs) for that specific measurement area (e.g., M = 610).
--- This array serves as a "pool" of all waveforms, where each column m is a complete, unique signal

- Explicit Mapping Logic:
-- The two arrays are linked via an index-based lookup. To find the waveform for a specific event i and sensor j, you must perform the following two steps:
--- Get the Waveform Index: First, retrieve the mapping index, let's call it m, from TRAI_TIME_MAP. This index m corresponds to the specific TRAI for that measurement
--- m = TRAI_TIME_MAP[1,i,j] (Matlab usage)/ m = TRAI_TIME_MAP[0,i,j] (Python HDF usage)
--- Retrieve the Waveform: Use this index m to select the correct column from the TRAI_WAVEFORMS array. The complete signal is the entirety of that column
--- Waveform Signal = TRAI_WAVEFORMS[:,m]
-- Matlab uses numbering from 1, HDF files are created in Python therefore index numbers start from 0