Marine water jet propulsion systems require optimized nozzle and duct geometries to maximize thrust and efficiency, yet design improvements are often limited by the lack of integrated hydrodynamic analysis. This study aimed to design an efficient marine water jet and evaluate its hydrodynamic performance through combined CAD modeling and CFD simulation. A three-dimensional model of the propulsion system was developed in SolidWorks, incorporating optimized nozzle and internal duct geometry. Computational Fluid Dynamics (CFD) simulations were performed to analyze velocity fields, pressure distributions, and thrust output under defined fluid properties and boundary conditions. Both the complete jet system (including a free-surface water interface) and a simplified nozzle-only configuration was examined. Simulations revealed clear correlations between geometric parameters and performance, identifying configurations that improved energy conversion and reduced wall friction. The optimized design achieved higher thrust efficiency compared to baseline geometries. Integrated CAD–CFD analysis provides a robust framework for marine water jet design, enabling targeted geometry refinements that enhance hydrodynamic performance. The findings support future development of high-efficiency propulsion systems for marine applications. 

We investigate the structural properties of a graph defined on the ring. The Adjacency between two different vertices and is determined by the bilinear congruence. We analyze three fundamental cases, and for distinct odd primes. We describe the graph's breakdown into unit and non-unit vertex subsets. The unit subgraph forms disjoint cliques, with sizes depending on Euler's totient function. In contrast, the zero-divisor subgraph shows more complex behaviour governed by annihilation ideals. We establish general properties, including degree formulas, determination of maximum clique sizes in each component, determining the diameter, computing the girth, locating the graph centers, and finding the measures of vertex and edge connectivity. Additionally, we characterize independent sets and prove the existence of Hamiltonian cycles and supereulerian properties under certain connectivity conditions. Our results show how the prime factorization of influences these properties.

The aim of this paper is to prove that the Diophantine exponent 𝐷𝑖𝑜( 𝑑−𝜷(𝑙𝛽)) is bounded by 𝑙𝑜𝑔𝑀(𝛽)𝑙𝑜𝑔𝛽+(𝑑−1)𝑙𝑜𝑔|𝑎𝑑|+1𝑙𝑜𝑔𝛽, where 𝛽 is an algebraic number, and 𝑀(𝛽) is the Mahler measure of 𝛽. In addition, a new result will be founded about transcendental number 𝑎 when 𝐷𝑖𝑜(𝑎) is infinite.

The study investigates the mechanical performance of isolated steel–concrete composite joints subjected to both positive and negative bending moments through an advanced finite element modeling approach. The research addresses a critical gap in existing design codes, which often overlook the nonlinear interaction between steel and concrete components in semi-rigid connections. The primary aim is to evaluate the joint behavior under realistic service and extreme loading conditions, offering a validated numerical framework that can support future enhancements in structural design standards. A three-dimensional nonlinear finite element model was developed using ABAQUS, integrating the Concrete Damaged Plasticity (CDP) model to capture concrete cracking, steel yielding, and interfacial slip. Experimental data from composite specimens tested in Warsaw University of Technology and replicated at the Libyan Concrete Materials Laboratory were used for calibration and validation. Parametric analyses considered variations in end-plate geometry, bolt arrangements, and column dimensions to assess their influence on joint stiffness, ductility, and load transfer mechanisms. The results demonstrated excellent agreement between experimental and numerical findings, with a correlation coefficient exceeding 0.95 for moment–rotation relationships. Among the tested configurations, the CSB7 joint (eight-bolt symmetric extended end plate) exhibited the highest performance, achieving sagging and hogging moments of 144 kNm and 269 kNm, respectively. These results highlight the joint's superior ductility and robustness under nonlinear loading, indicating its suitability for structures exposed to exceptional conditions such as seismic or fire events. The research contributes to the ongoing development of Eurocode-based composite joint design, emphasizing the need for nonlinear performance criteria and predictive modeling tools. While the study was limited by the absence of cyclic and high-temperature testing, its implications extend to safer, more resilient, and sustainable structural systems, promoting optimized connection design and improved global design standards.

KEYWORDS

Numerical Modeling, Steel, Concrete, Composite, ABAQUS, Finite Element Method

ZnO thin films were deposited on stainless steel substrates using the immersion method by immersing the substrates in a sol-gel coating solution at temperatures of 70 °C and 80 °C for varying durations of (1, 2, 3, and 4minutes). The results indicated that increasing the immersion time significantly influenced the film thickness. Optical measurements showed that transmittance at a wavelength of 350nm increased with higher deposition temperatures. Additionally, the Urbach tail energy increased with temperature, whereas the band gap (Eg) decreased markedly. Furthermore, the electrical conductivity of the ZnO films improved with increased temperature and immersion time.

This paper presents a comprehensive study of modelling human body blockage (the most critical challenges in fifth-generation (5G)) effects on indoor millimetre wave (mmWave) communication links at 32.5 GHz, a key frequency for 5G networks. Through controlled experiments in a laboratory environment, we analyse signal attenuation as a human subject obstructs the line-of-sight (LOS) path between transmitter and receiver, recording received power at incremental positions. To model the observed phenomena, we propose a hybrid framework integrating deterministic and statistical components: (1) a modified Double Knife-Edge Diffraction (DKED) model with Gaussian-shaped blockage attenuation (20.8 dB peak at full blockage) and reflection-induced signal enhancement (−15.0 dB peak from nearby objects), and (2) a log-normal shadowing component (σ = 11.8 dB) capturing environmental randomness. Our results reveal strong agreement between simulations and measurements, achieving a mean absolute error of 3.2 dB and a correlation coefficient R² = 0.89. The analysis demonstrates that human-induced diffraction dominates near the LOS centre, while multipath reflections significantly alter signal strength at peripheral positions. We further derive practical guidelines for 5G network design, recommending a 44.4 dB link budget safety margin to account for combined blockage and shadowing effects. This work advances indoor mmWaves channel modelling by unifying physics-based diffraction analysis with empirical reflection characterization, the framework achieves strong experimental validation and offers actionable insights for 5G network design