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This research investigates the performance of ABS P400 parts under compressive loading. These ABS P400 parts are fabricated by fused deposition modeling (FDM) process using omnidirectional printing. The effects of three critical parameters, raster angle (A), air gap (B), and raster width (C), each at three different levels, were analyzed on three different performance measures, i.e. total deformation up to failure ($TD$) measured in %, maximum energy ($ME$) in MJ/m³ and break energy ($BE$) in MJ/m³. Results of experimentations were analyzed using analysis of variance (ANOVA), perturbation curve and 3D surface plots. The research established the anisotropic nature, durability and less brittleness of the FDM fabricated ABSP400 part, which leads to lower strength and also influence the energy absorbing behavior while deformation under compression. Complex relationships were exhibited between the chosen parameters and studied measures. It was also observed that $TD$ is noticeable due to less brittleness of ABS P400 however, $TD$ and $BE$ vary in a contradictory fashion with changes in process parameters. The models were validated using normality plots. Multi-objective optimization was done using the desirability approach to determine the optimal combination of FDM process parameters for optimum responses. The desirability result showed that the optimized input parameter is $A=60^{\circ },B=0.002$mm, and $C=0.477$mm which yield maximized optimum responses as $TD=47.94$%, $ME=1.6\times 10^6$MJ/m³, and $BE=2.13\times 10^7$MJ/m³. The work not only reflects the effect of three FDM parameters on the total deformation up to failure ($TD$ in %) but, in addition, energy absorption behavior of FDM parts under compression is also investigated. The study on the behavior of energy at ultimate stress or ultimate load and breaking stress or breaking load were rarely investigated in earlier research which reflects the novelty of our research.

A novel electromagnetic energy harvester (EMEH) based on double-ring core for power line energy harvesting is proposed in this paper. Due to large magnetic reluctance caused by the inherent air gap at the opening of core, the magnetic flux leakage in magnetic core severely limits the output power of EMEH. A double-ring core with lower magnetic flux leakage is developed. The internal magnetic reluctance of the double-ring core is reduced by changing the distribution of the air gap with a fixed volume. The simulation results show that the double-ring core can produce the highest average magnetic induction, which is 2.42 times, 1.82 times and 1.7 times that of the single-ring opening, stepped opening and V-shaped opening, respectively. In order to improve the output performance of the EMEH, the resonance matching is used for the power management. The power management unit through the resonant matching can increase the acquisition efficiency by 2.23 times and achieve a maximum output power of 32.78mW at a 10A current across the power line. The EMEH can drive a low-power wireless node operating for 29min. A valuable solution is provided for high-efficiency self-powered systems in smart applications.

In recent years, compact and broad band microstrip antennas have received much attention because of their potential applications in many portable communication systems. Several significant advances in improving the inherent narrow operating bandwidth of microstrip antennas have been reported. Microstrip antennas with air substrate are one of the effective and convenient approaches for improving bandwidth. In this communication an attempt has been made to develop broadband microstrip radiator by creating an airgap between ground plane and dielectric substrate. The analysis has been performed for hexagonal patch microstrip antenna in S and X band of microwave frequency range. Variation in bandwidth and resonant frequency with height of airgap (Δ) has also been estimated and plotted. It has been realized that by employing this technique, it is convenient to design broad band microstrip array configurations.

Spot induction hardening (SIH) is a novel heat treatment for hardening small region area on metal component surface. The air gap (AG) between inductor and workpiece is one of most important factors for SIH hardening effect. On the basis of the characteristics of SIH, a 3D finite element model coupled electromagnetic and temperature filed as well as phase transformation was developed via commercial software ANSYS. The investigation of the effect of AG on SIH process was carried out and the relationship between AG and temperature field, the microstructure transformation and the micro-hardness were obtained respectively via SIH model.