In recent years, wearable antennas gain significant attention for use in healthcare applications, particularly in Implantable Medical Devices (IMDs) and Medical Body Area Networks. These antennas must be small, lightweight, and body-conforming to meet the needs of these applications. As the wearable antennas play a crucial role in Medical Body Area Networks (MBAN), facilitating continuous health monitoring. Their integration in IMDs requires minimizing electromagnetic interference and optimizing radiation characteristics. As healthcare systems demand more efficient and precise devices, the development of wearable antennas becomes essential for enhanced performance. The development of such antenna has gathered substantial awareness in recent years in the telemedicine industry. This study proposes a two-dimensional square loop-based antenna design, operating at 2.4 GHz with improved radiation properties and reduced backward radiation. The antenna dimensions are 60 × 40 × 0.7 mm3, making it compact and effective for body-worn applications. The antenna design process incorporates Machine Learning (ML) techniques to minimize simulation time, increase efficiency, and enhance design accuracy. ML algorithms optimize the antenna’s performance, particularly in terms of reflection coefficient, bandwidth, and gain. The proposed antenna design has tackled the issues faced by the conventional antenna and holds promise for real-time applications in healthcare, military, sports, and identification systems. It addresses critical challenges such as Specific Absorption Rate (SAR) and efficiency, ensuring optimal performance when interacting with human body tissues. Moreover, the experimental results demonstrate that the simulated and fabricated results exhibit similar deviations, confirming that the antenna is suitable for real-world applications.
Excess energy (PExc) in isolated microgrids based on hybrid renewable energy systems (HRES) causes reliability and protection issues. This paper presents the optimal design of HRES by minimizing the levelized cost of energy (LCOE) and PExc management in isolated microgrids (IMGs) with different types of energy storage systems (ESS), including battery energy storage (BES) technologies, pumped hydro storage (PHS), hydrogen energy storage (HES), and thermal energy storage (TES). The IMGs design with the various BES technologies minimizes the LCOE in the range of 0.1050 $/kWh-0.3307 $/kWh, ensuring supply reliability above 96% and limiting PExc generation below 10%. Similarly, the IMGs with PHS, HES, and TES offer the electricity at LCOEs of 0.4094 $/kWh, 0.2824 $/kWh, and 0.1429 $/kWh, respectively. The optimally designed IMG with the HES reduces the highest 92.39% greenhouse gas emissions. The African Vultures Optimization Algorithm (AVOA) minimizes the LCOE with a faster convergence rate and higher accuracy.
The rapid rise in atmospheric CO2 concentrations, now exceeding 420 ppm, necessitates the urgent deployment of scalable carbon capture, utilization, and storage (CCUS) technologies to mitigate global warming. This review offers a comprehensive analysis of carbon nanomaterials (CNMs) as a transformative class of adsorbents, providing a sustainable alternative to energy-intensive amine scrubbing. CNMs span all dimensional regimes, ranging from zero-dimensional (0D) fullerenes and carbon dots, through one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene, to three-dimensional (3D) hierarchical foams, which exhibit exceptional physicochemical properties, notably high specific surface areas and highly tunable pore architectures. Various surface engineering approaches, including tuning surface chemistry and pore architecture and heteroatom functionalization, have been explored to enhance adsorption capacity and selectivity, as well as enable multiple regeneration cycles. Through structure–property–performance analysis, it has been concluded that ultra-micropores (<0.7 nm) are favorable, which further enhance adsorption capacity at low pressures, the isosteric heat of adsorption (35–50 kJ mol−1), and cycling stability. Furthermore, the surface modification of CNMs through nitrogen doping, amine functionalization, and hybrid composite engineering achieved CO2 adsorption capacities of up to ∼9 mmol g−1 at modest pressures, along with low-temperature regeneration (<100 °C), resulting in energy-efficient performance. This article also outlines ongoing challenges and research frontiers, emphasizing the need to enhance the CO2/N2 selectivity ratio, develop sustainable and scalable synthesis methods, incorporate techno-economic evaluations, and bridge laboratory-scale performance with industrial implementation. Later, a comparative analysis of the modified CNMs with standardized MOFs in terms of capacity is also discussed in detail. This analysis synthesizes current advancements and identifies knowledge gaps, offering a prospective outlook on the development and future trajectories of CNM-based adsorbents in greenhouse gas mitigation and achieving net-zero emission targets.
Inspired by tetracyclic nitropyrazole-based stable and potential energetic materials, we designed two new C-C and C-N-linked tetrazole-pyrazole-based energetic molecules, with acceptable detonation performance and moderate sensitivity. The heat of formation and performance parameters were analyzed by density functional theory, and the calculations demonstrate that both compounds have a high positive heat of formation (> 930 kJ/mol). The designed compounds, A1 (density: 1.79 g/cm3, detonation velocity: 7.95 km/s, pressure: 25.30 GPa, impact sensitivity: 35 J) and A2 (density: 1.87 g/cm3, detonation velocity: 8.83 km/s, pressure: 33.31 GPa, impact sensitivity: 21 J), exhibit moderate to high detonation performance and low sensitivity to impact stimuli. Further, the analysis of bond strength and Mayer bond order of the C-NO2 bond and charge on -NO2 groups suggests the stability of the C-NO2 bond in designed compounds in comparison with reported tetracyclic energetic compounds. These findings demonstrate that the combination of bistetrazole with nitropyrazole and dinitropyrazole rings holds high potential for developing new high-performing and less sensitive energetic materials. The optimization and energy calculations of designed tetracyclic compounds were carried out at the B3LYP/6-311G(d,p) level of theory, utilizing the Gaussian 09 software package. The molecular surface properties were analysed using Multiwfn. The EXPLO5 (V7.01.01) thermochemical code was used to predict the detonation properties.
Wire arc additive manufacturing (WAAM), leveraging traditional gas metal arc welding (GMAW) technology, offers a promising approach for fabricating large-scale metallic components with high deposition rates. Among GMAW-based processes, cold metal transfer (CMT) and pulsed metal inert gas (MIG) techniques differ significantly in their metal transfer mechanisms and thermal inputs, which directly influence the resulting material properties. This study systematically compares the microstructural, mechanical, tribological, and corrosion characteristics of 316L stainless steel walls produced using CMT and pulsed MIG WAAM processes under similar heat input conditions (CMT: 323.48 J/mm, pulsed MIG: 329.14 J/mm). The CMT process produced finer grains (11.16 mu m) compared to pulsed MIG (14.14 mu m), contributing to slightly higher microhardness (171.90 HV versus 171.14 HV) and improved mechanical properties. Charpy impact toughness, yield strength, and ultimate tensile strength were all higher for the CMT process by 16.4%, 3.4%, and 1.3%, respectively, while pulsed MIG showed slightly higher elongation (56% versus 52.25%). Fractographic analysis revealed finer, more uniform dimples in the CMT samples, indicating ductile fracture behavior. In terms of tribological performance, the CMT process exhibited a lower coefficient of friction (0.216 versus 0.249) and a significantly reduced wear-rate (3.4 x 10(-3) mm(3)/m versus 5.5 x 10(-3) mm(3)/m). Corrosion resistance was also marginally better in the CMT samples, with a corrosion rate of 0.05235 mm/year compared to 0.05524 mm/year for pulsed MIG. Overall, the CMT process consistently outperformed pulsed MIG across multiple performance metrics, making it a more favorable choice for high-integrity additive manufacturing of stainless steel components.
