Proton exchange membrane fuel cells (PEMFCs) have attracted significant attention due to their high efficiency and low emission characteristics. However, the cell performance is strongly influenced by operating conditions and membrane properties, which are difficult to investigate comprehensively by experimental approaches alone. This study develops a complete electrochemical model of a single PEM fuel cell in the MATLAB – Simulink environment based on the voltage loss mechanisms including the Nernst potential, activation overpotential, ohmic losses, and concentration losses. The model is employed to quantitatively investigate the effects of operating temperature, hydrogen partial pressure, oxygen partial pressure, and membrane thickness on the polarization characteristics (I – V curves) of the PEMFC. Simulation results indicate that increasing temperature significantly enhances activation kinetics and improves cell voltage, while elevated oxygen partial pressure yields the most pronounced performance improvement among gas parameters. Conversely, increasing membrane thickness leads to higher ohmic losses and voltage degradation, especially in the high –current – density regime. The proposed model provides an effective numerical tool for teaching, system analysis, and preliminary optimization of PEMFC operating conditions.

ABSTRACT This paper analyzes the security performance of underlay cognitive energy-harvesting relay radio networks (UCEHRRN) through the Monter-Carlo simulation results. The results clarify the influence of critical operating parameters on the security performance of the system. Furthermore, the security capabilities of UCEHRRN have been compared with those of the live transmission system. Moreover, many results show that the security performance of the system is significantly improved. Analysis of the results also shows that UCEHRRN is especially effective when the direct transmission system cannot achieve security due to objective reasons such as path loss, severe fading, and shadowing.