Shivan Ismael Abdullah

This study investigates the nonlinear vibrational behavior of single-walled boron nitride nanotubes (SWBNNTs) using a nonlinear Euler–Bernoulli beam model. The governing partial differential equations are reduced to a set of ordinary differential equations through Galerkin’s method employing trigonometric shape functions. The multiple time scales method is then applied to analyze the nonlinear frequency response under primary, subharmonic, and superharmonic resonances, and implicit analytical expressions for the frequency response are derived. A comprehensive parametric study is conducted to examine the influences of stiffness, excitation amplitude, damping coefficient, and detuning parameter on the nonlinear dynamic behavior. The results reveal that increased stiffness significantly suppresses nonlinear effects by enhancing resistance to deformation, while higher excitation amplitudes amplify nonlinear response intensity across all resonance cases. Subharmonic resonance exhibits response trends distinct from those of primary and superharmonic resonances, although their overall effectiveness remains comparable. Backbone curve curvature effectively captures the growth or decay of nonlinear intensity due to parameter variations. Furthermore, damping is shown to attenuate nonlinear effects owing to energy dissipation, whereas increased detuning leads to stronger nonlinear responses characterized by pronounced multi-valued behavior. These findings provide valuable insights into controlling and tuning the nonlinear vibration characteristics of SWBNNT-based nanostructures.

This research examines the nonlinear dynamics of carbon nanotube-based nanobeams subjected to harmonic forcing, aiming to advance the design of high-performance athletic gear. The analysis accounts for geometric nonlinearities, damping from a viscoelastic substrate, and surface effects essential to creating lightweight yet robust components for items such as tennis rackets, golf clubs, and protective equipment. Given the elevated surface-to-volume ratio in nanomaterials, the study evaluates surface elasticity and residual stresses to improve shock absorption and energy dissipation. Equations of motion are formulated based on Euler-Bernoulli beam theory, discretized through the Galerkin approach employing trigonometric modes, and resolved via the method of multiple scales. Critical factors, including viscoelastic damping factors, crystal directions ([100] and [111]), and nonlinear geometry, are assessed for their impact on the primary resonance curve. Findings reveal that strategic adjustment of these variables can profoundly modify the frequency-amplitude behavior, allowing customized rigidity and attenuation suited to sporting needs. This work establishes a basis for engineering advanced nanomaterials in sports, harnessing nonlinear vibrations to enhance functionality, longevity, and user protection.

This study aims to investigate the influence of building height and layout on energy consumption. It also analyzes methods for reducing energy consumption in these buildings. The EnergyPlus software performs simulations under local climatic conditions for all seasons. The city is divided into several sections based on cardinal directions, and energy consumption is calculated for each section, considering the city's distinct seasonal variations. Buildings in suburban areas with more sunlight exhibited higher overall energy consumption due to the reliance on heating and cooling systems, compared to the city center where denser urban areas moderated temperature extremes. Additionally, building design and insulation played significant roles. The analysis also revealed a west-to-east trend; higher consumption at the edges compared to the center. This is attributed to factors such as building density and shade from taller structures. The study further examined the impact of varying building heights. While most buildings were 20 meters tall, specific rows ranged from 21 to 25 meters. Changing these heights resulted in decreased cooling and increased heating demands in the north-south analysis, and reduced demands for both heating and cooling in the west-east analysis. This highlights the complex interplay between building layout, height, and energy consumption.

In this study, the effects of graphene oxide (GO) on composites based on epoxy resin were analyzed. Different contents of GO (1.5–6vol.%) were added to epoxy resin. The GO/epoxy composite was prepared using the casting method and was prepared under room temperature. Mechanical tests’ results such as tensile test, impact test and hardness test show enhancements of the mechanical properties of the GO/epoxy composite. The experimental results clearly show an improvement in the Young’s modulus, tensile strength and hardness. The impact strength was seen to decrease, pointing to brittleness increase of the GO/epoxy composite. A microstructure analysis using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis was also performed, which showed how GO impeded the propagation of cracks in the composite. From the SEM images we observed the interface between the GO and the epoxy composite. As can be seen from this research, the GO/epoxy composites can be used for a large number of applications. The results of this research are a strong evidence for GO/epoxy composites being a potential candidate for use in a variety of industrial applications, especially for automobile parts, aircraft components, and electronic parts such as supercapacitors, transistors, etc