Search Results (5)

Reducing greenhouse gas (GHG) emissions is essential across all sectors, including the maritime transport industry. Speed reduction is a key short-term operational measure for lowering GHG emissions from ships, and its implementation has already begun. While speed reduction offers significant benefits, particularly in terms of GHG emissions reduction potential, there are concerns about its application, including increased voyage times, an increase in the number of ships required, and the fact that ships may operate in conditions quite different from those for which they were designed and optimized. This study investigates the impact of speed reduction on ship performance in calm water, using a post-Panamax container ship as an example. Numerical simulations of resistance, open-water, and self-propulsion tests were conducted for a full-scale ship and propeller, and the results were validated against extrapolated towing tank data. Hydrodynamic characteristics, fuel consumption, and carbon dioxide emissions at various speeds were then estimated. The results indicated that when constant transport work was maintained, yearly CO₂ emissions decreased by −16.89% with a 10% speed reduction, −21.97% with a 20% speed reduction, and −25.74% with a 30% speed reduction. This study demonstrates that the classical cubic law for fuel oil consumption and speed dependence is not valid, as the speed exponent is lower than 3. The potential benefits and drawbacks of implementing slow steaming are discussed. Finally, this research contributes to the existing literature by evaluating the CO₂ emissions reduction potential of slow steaming. Full article

The “excess salt replication process” is a new simple method of fabrication of open-cell metal foam based on the commonly known salt replication method. Porous materials with porosity between 46% and 66% result when the employed alloy is 25% antimonial lead alloy and when it is 58% to 65% zamak 5. These foams are proposed as structured catalysts instead of packed beds in the treatment of wastewater. The local regimes influencing macroscopic air flow behaviour through these foams are delimited and boundaries are analysed in terms of sample length. Most of the experimental tests in this work exhibited a general trend of air flow in ESR foams dominated by the “strong inertia regime”. It was established that the law governing the unidirectional air flow through these foams was the full cubic law. The permeability and inertia coefficient of five samples with a cell diameter between 2.5 and 4.5 mm were calculated, and an empirical correlation was fitted. The irregular cuboid shape of salt grains used in the ESR foam was the origin of the special cell form of ESR foams leading to an anisotropic ordered porous media. This can explain the macroscopic turbulence of air flow because there were many dead zones present in the corner of each cubic cell, thus causing kinetic energy loss starting at earlier regimes. Full article

This work recovers cubic-quartic optical solitons with dispersive reflectivity in fiber Bragg gratings and parabolic law of nonlinearity. The Lie symmetry analysis first reduces the governing partial differential equations to the corresponding ordinary differential equations which are subsequently integrated. This integration is conducted using two approaches which are the modified Kudryashov’s approach as well as the generalized Arnous’ scheme. These collectively yielded a full spectrum of cubic-quartic optical solitons that have been proposed to control the depletion of the much-needed chromatic dispersion. They range from bright, dark, singular to combo solitons. These solitons are considered with dispersive reflectivity, which maintains the necessary balance between chromatic dispersion and nonlinear refractive index structure for an uninterrupted transmission of solitons along intercontinental distances. Their respective surface and contour plots are also exhibited. A few closing words are included with some prospective future avenues of research to extend this topic further. Full article

This work analytically recovers the highly dispersive bright 1–soliton solution using for the perturbed complex Ginzburg–Landau equation, which is studied with three forms of nonlinear refractive index structures. They are Kerr law, parabolic law, and polynomial law. The perturbation terms appear with maximum allowable intensity, also known as full nonlinearity. The semi-inverse variational principle makes this retrieval possible. The amplitude–width relation is obtained by solving a cubic polynomial equation using Cardano’s approach. The parameter constraints for the existence of such solitons are also enumerated. Full article

The thermal scattering law (TSL), i.e., S(α,β), represents the momentum and energy exchange phase space for a material. The incoherent and coherent components of the TSL correlate an atom’s trajectory with itself and/or with other atoms in the lattice structure. This structural information is especially important for low energies where the wavelength of neutrons is on the order of the lattice interatomic spacing. Both thermal neutron scattering as well as low energy resonance broadening involve processes where incoming neutron responses are lattice dependent. Traditionally, Doppler broadening for absorption resonances approximates these interactions by assuming a Maxwell–Boltzmann distribution for the neutron velocity. For high energies and high temperatures, this approximation is reasonable. However, for low temperatures or low energies, the lattice structure binding effects will influence the velocity distribution. Using the TSL to determine the Doppler broadening directly introduces the material structure into the calculation to most accurately capture the momentum and energy space. Typically, the TSL is derived assuming cubic lattice symmetry. This approximation collapses the directional lattice information, including the polarization vectors and associated energies, into an energy-dependent function called the density of states. The cubic approximation, while valid for highly symmetric and uniformly bonded materials, is insufficient to capture the true structure. In this work, generalized formulation for the exact, lattice-dependent TSL is implemented within the Full Law Analysis Scattering System Hub (FLASSH) using polarization vectors and associated energies as fundamental input. These capabilities are utilized to perform the generalized structure Doppler broadening analysis for UO₂. Full article