Current Issue : October-December Volume : 2026 Issue Number : 4 Articles : 5 Articles
The rapid adoption of alternative marine fuels has introduced safety challenges not fully addressed by regulatory frameworks developed for conventional fuels. This study examines how International Maritime Organization (IMO) safety regulations respond to the dominant risk characteristics of alternative fuels, focusing on LNG, LPG, methanol, and ammonia. A comparative analysis is conducted based on physicochemical properties, hazard pathways, and corresponding provisions under the IGF Code and Interim Guidelines. The results show that while the IGF Code provides a goal-based, flammability-centered framework, its extension to fuels with different risk profiles—such as toxicity and liquid-phase hazards—creates structural mismatches between dominant hazards and regulatory trigger mechanisms. In particular, reliance on flammability-based indicators (e.g., LEL) for safety system activation in toxicity-dominant fuels reveals a misalignment between regulatory assumptions and actual risk pathways. In addition, intensified conservatism in ammonia regulations enhances safety but raises challenges related to operability and regulatory predictability. The study concludes that future regulatory development should adopt an integrated framework aligning hazard-specific indicators with regulatory mechanisms and incorporating empirical evidence through the Experience Building Phase (EBP)....
Additive manufacturing’s design freedom enables new approaches to component modularity that were previously constrained by traditional manufacturing methods. This research presents such an application in aeroacoustic research, where the acoustic emission of fans operating under disturbed inflow conditions remains a critical factor in the acceptance of Heating, Ventilation and Air Conditioning (HVAC) systems. While leading-edge modifications such as serrations, slits, or porous structures have shown noise reduction potential, research into different variants has been costly due to the need to manufacture complete blade sets for each design iteration. This study presents a modular research fan blade design featuring an interchangeable leading edge manufactured using powder bed fusion laser beam (PBF-LB) technology. The modular design utilizes a stepped-cut interface at one-third of the chord length at the fan tip, with manufacturing tolerances systematically optimized to achieve minimal gap dimensions at the blade interface while maintaining mechanical reliability through lateral screw fixation. Experimental validation using a fan test rig compliant with DIN 5801 confirmed that the modular configuration maintains equivalent performance to a monolithic reference fan of identical geometry. Both aerodynamic and acoustic measurements showed close agreement across all operating points, with static pressure rise deviations below 2 Pa within the design operating range (maximum 4 Pa in the partial load region) and acoustic deviations within ±0.5 dB(A). Spectral analysis confirmed no introduction of tonal components. This platform provides a foundation for systematic investigation of noise reduction technologies in axial-fan applications....
Composite hat-stiffened panels are widely used in civil aircraft structural design as typical closed-section stiffened components with high load-carrying efficiency. To accurately predict the post-buckling bearing capacity and optimize the tapered termination design of such panels, this paper investigates the failure process of composite hat-stiffened panels with tapered ends through physical modeling and numerical analysis. A nonlinear failure analysis model is established by introducing the failure mechanisms of adhesive interfaces and composite laminates. The modeling method is verified against experimental results, showing discrepancies of 2.7% for buckling load and 3.5% for post-buckling failure load, respectively. Based on the validated numerical approach, parametric studies are carried out to analyze the effects of termination taper parameters on buckling and post-buckling mechanical behaviors. The results indicate that the termination taper design effectively adjusts the stiffness matching between stiffeners and skin and relieves local stress concentration. The optimal taper angle of 120◦ is recommended, where the failure load increases by 22% to 141.8 kN compared to the baseline configuration, significantly improving its post-buckling load-carrying capacity. The findings of this study can provide technical references for the design of stiffened composite panels with tapered stringer terminations in aerospace engineering....
This study demonstrates formal connections between Abelian group theory and factorial experimental designs. I begin by showing that full-factorial designs are isomorphic to elementary p-groups. I continue with an analysis of the general group and subgroup structure of 3 × 3 full-factorial designs commonly utilized in detection studies, followed by extensions to more general but related designs in the subsequent section, namely, 3 × 3 × 3 designs. I show that the subgroup lattice of 3 × 3 designs decompose the experiment into single and double-target subgroups and a target-absent subgroup. An application of this endeavor is the identification of experimental strata, interactions, interaction contrasts, and fractional designs. By using examples from the reaction-time (RT) and non-parametric modeling literature, it is shown how comparisons across and within these subgroup structures can readily be used to derive predictions about human information processing. Relatedly, I provide predictions derived from subgroup analyses to increase statistical power and simplify data analyses. Finally, some suggestions are provided for analyzing more general designs....
To ensure safety in structural design, a method to quantify the damage in thermoplastic ultrasonic single-spot-welded Single-Lap Shear (SLS) joints is needed. This paper investigates whether detailed knowledge regarding the shape of the weld is required when using the global compliance to quantify damage. A finite element model using cohesive zone elements is developed in Abaqus to simulate single-spot SLS specimens with varying weld areas, aspect ratios, and damage growth directions, covering damage levels from 0 to 90% of the initial weld area. For each configuration, the relationship between intact weld area and global compliance is evaluated, and the numerical trends are compared to previously published experimental data from similar joints. The results show that weld size and damage growth direction have negligible influence on the relationship between global compliance and weld area, and that weld shape is also insignificant as long as the aspect ratio remains within a practical range; only very elongated welds with an aspect ratio over 4.4, which are unlikely in production, deviate significantly. Global compliance can be used as a reliable indicator of damage in single-spot ultrasonic welds that is insensitive to weld shape. This enables simplified in situ damage monitoring and reduces the need for detailed geometric characterisation during mechanical testing....
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