This article presents a probabilistic approach for the immunity/susceptibility assessment of a twisted-wire transmission line in the presence of a perfect ground plane. A random electromagnetic field is assumed to excite the transmission line, which is essentially modeled as a plane wave with certain parameters (magnitude, polarization angle, direction-of-arrival angles) treated as independent random variables. Closed-form expressions are provided for the probability density function of the induced common-mode and differential-mode terminal voltages in certain cases. New formulas for the pertinent first and second moments (mean values and mean square values) are also obtained. A general Monte Carlo technique is employed to verify the aforementioned closed-form expressions, but also for treating excitation scenarios that are not analytically tractable.

The present study examines the physicochemical degradation and elemental contamination of marine distillate diesel fuels, which were stored in land-based tanks in operational conditions. Forty-one (41) samples, in compliance with ELOT ISO 8217:2024 were analyzed for crucial physicochemical properties. Stepwise regression identified magnesium (Mg) (positive) and chromium (Cr) (negative) as significant viscosity predictors (R² = 0.269, p = 0.003, VIF < 2), while calcium (Ca), Phosphorus (P), zinc (Zn), copper (Cu), lead (Pb) and Ferrous (Fe) were excluded due to multicollinearity. Strong correlations (r > 0.85) between element pairs (Cu-Pb) (r = 0.996), Ca-Zn (r = 0.897), and P-Ca (r = 0.888) indicate common sources from lubricant additives (ZDDP) and brass corrosion, with individual correlations recorded for Ca (showing r = 0.679, p < 0.001), P (r = 0.722, p < 0.001), and Zn (r = 0.595, p < 0.001). The results revealed that fuels stored in carbon steel tanks under high-humidity conditions for over six (6) months recorded higher metal loads than those in stainless steel tanks with regular periodic supply. The FAME content in the studied samples ranged from 6.7 to 7.1% v/v and showed no significant correlation with degradation indicators (p > 0.05). The narrow FAME range examined precludes definitive conclusions regarding specific biodiesel effects. The threshold of 0.2 mg/kg, as set by manufacturers’ guidelines to protect injectors, was exceeded in the coastal carbon steel tank samples with eight (8) months of storage under high-humidity conditions and in the coastal carbon steel tank samples with nine (9) months of storage under high-humidity conditions examined. The current study offers a systematic correlation between viscosity and elemental contamination for marine distillate fuels under operational storage conditions regarding real-world samples.

Frequency domain methods used in electromagnetic analyses, such as the Method of Auxiliary Sources (MAS) and the various Moment Methods (MoM), share many similarities but have notable differences in terms of numerical stability, accuracy, and computational cost. Computational cost differs from algorithmic complexity, which is easier to define. Consequently, it is rarely analyzed systematically in numerical studies. To this end, this work deals with the canonical problem of electromagnetic scattering from an externally excited circular cylinder of infinite conductivity and applies both MAS and MoM in order to assess their solutions and behaviors from the aforementioned perspectives. This problem is solved by meticulously applying MAS and two popular variants of MoM to achieve comparable stability and accuracy. Then, the methods are compared in terms of the associated computational cost, not only in solving the ensuing matrix equations, but also in computing the near and far fields at a large number of points.

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This study investigated the degradation and contamination behavior of 41 real-world operational Marine Diesel Fuel samples, conforming to ELOT ISO 8217:2024 (DFA category). Samples were sourced directly from land-based supply tanks. To assess fuel degradation, a comprehensive suite of parameters was evaluated, including fuel characteristics such as viscosity and density. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was employed for elemental analysis to determine the content of wear and other metallic contaminants. Elevated concentrations of various metals were detected, suggesting potential leaching from system components within the storage infrastructure. Notable elemental concentrations included Iron (Fe up to 1.38 mg/kg), Copper (Cu up to 0.401 mg/kg), Lead (Pb up to 0.358 mg/kg), Aluminum (Al up to 0.218 mg/kg), Zinc (Zn up to 1.331 mg/kg), Nickel (Ni up to 0.172 mg/kg), Calcium (Ca up to 8.054 mg/kg), Sodium (Na up to 0.332 mg/kg), Phosphorous (P up to 0.602 mg/kg), and Silicon (Si up to 8.249 mg/kg). The presence of these contaminants in marine fuels, if bunkered, poses a significant risk of impaired engine performance, including injector fouling and ash formation. Critically, this study suggests that FAME content is not the primary driver of the observed oxidation and subsequent metallic degradation.