{'fraction_non_alphanumeric': 0.036917098445595854, 'fraction_numerical': 0.014248704663212436, 'mean_word_length': 4.80827067669173, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Effects of seat-back angle and accelerometer height at the seat-back on seat-back x axis r.m.s. acceleration in filed experiments according to the ISO2631-1 standard.

The effects of seat-back angle and accelerometer height at the seat-back on seat-back x-axis frequency-weighted root-mean-square (r.m.s.) acceleration have been investigated in field experiments. Experiment 1 investigated the range and variability, of frequency-weighted r.m.s. acceleration at the same measurement position, where the seat-back angle was 24 degrees from vertical on the floor and the accelerometer height was 38 cm up from the seat cushion surface. Experiment 2 investigated ranges of frequency-weighted r.m.s. acceleration between the reference position, which was the position used in experiment 1, and test positions at different seat-back angles, 4 degrees ahead of and 4 degrees behind the reference position. Experiment 3 investigated the range of frequency-weighted r.m.s. acceleration between the reference position which was the same as in experiments 1 and experiment 2, and test positions at different accelerometer heights at the seat-back from a seat cushion surface, 2.5 cm higher, 2.5 cm lower and 5 cm lower than the reference position. This investigation clarifies that different seat-back angles and accelerometer heights at the seat-back affect the frequency-weighted r.m.s. acceleration at these measurement positions, which is beyond the exposure values at which people are able to distinguish different vibration acceleration magnitudes.