{'fraction_non_alphanumeric': 0.015283842794759825, 'fraction_numerical': 0.0, 'mean_word_length': 5.457746478873239, '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}}
Design and implementation of a hierarchical control strategy for proton exchange membrane fuel cells

The modeling and control strategies for proton exchange membrane (PEM) fuel cells are presented. Two different pulsing methodologies were designed and implemented in Fuel Cell Laboratory at Florida Atlantic University in order to increase the efficiency and performance of PEM fuel cells. The schedule experiments for each method comprised of varying the pulse amplitude, the frequency and the duty cycles. The amplitude variations were controlled by a pressure regulator on the pulsed air source; frequency and duty cycle changes were implemented using computer software in conjunction with A/D, D/A, timer and electronic circuits. The experimental results are promising. Further experimental work to improve the efficiency of PEM fuel cells based on an intelligent hybrid control strategy is under investigation.