Due to the massive wireless communications among numerous vehicular and static entities in the internet of vehicle networks, these networks became vulnerable to eavesdropping and interference. Thus, using physical-layer security techniques in vehicular networks can significantly enhance secrecy performance. This paper investigates the secrecy performance of cooperative vehicular relaying networks (CVRNs) over mixed Nakagami-? and double Nakagami-? fading channels in the presence of a single eavesdropper and cochannel interference. The relaying node is assumed to operate with different relaying schemes, namely, decode-and-forward, amplify-and-forward with variable gain, and amplify-and-forward with fixed gain. Hence, mathematical expressions for the average secrecy capacity (ASC) are obtained for the relaying schemes. Furthermore, a power allocation model is proposed to maximize the derived ASCs in terms of the source and relay nodes’ transmission powers, enhancing the relaying schemes’ secrecy performance. The results demonstrate the impact of channel condition and the strength of interference on the system secrecy performance. Moreover, the results show that the proposed power allocation model enhances the secrecy performance significantly compared to the equal power distribution model.

The spread of 3D printing in many different fields has become eminent. This paper aims to improve the mechanical properties of parts printed by fused deposition modeling technique. Acrylonitrile butadiene styrene (ABS) specimens are printed with custom printing parameters. These parameters give a tensile strength that is 86% of the injection- molded ABS strength, and give one of the best recorded results for 100% infill printed ABS tensile specimens. Furthermore, a post filling technique has been studied. Specimens are printed with inner voids and different densities using slicing software. Void shape is precisely selected to conform to the filling process. High-strength, low-cost thermoset resin is injected through specimens to fill those voids. A tensile test has been performed after the full curing of the resin. A morphology analysis is done. Using this technique strength to printed weight ratio is improved by 151 …

The present study experimentally investigated the thermal efficiency, collector area, weight, embodied energy, environmental CO₂ emissions of Al₂O₃/water nanofluid flow in a flat-plate solar collector and with coiled wire turbulators. The experiments were performed at  that is equal to 0.1%, 0.2% and 0.3% and volume flow rate from 120 to 300 L/h. Results indicate that the collector thermal efficiency increased with the increase of particle volume loadings and volume flow rates. The thermal efficiency of the collector with water circulate is 53%, whereas it is enhanced to 65% at  = 0.3% nanofluid, and it is further enhanced to 77% for  = 0.3% nanofluid with 10-mm coiled wire insert in a collector tube at a volume flow rate of 300 L/h. The collector area is declined to 8.66% ( = 0.1%), 14% ( = 0.2%) and 18.66% ( = 0.3%) for nanofluids. The collector area is further reduced to 31.33% for  = 0.3% nanofluid and with a …

Owing to the lack of complementary shear stress on vertical boundaries of a direct simple shear (DSS) specimen, the stress/strain distributions in soil specimens are not uniform. Although the previous studies discussed the effect of diameter-to-height ratio (D/H) on the mechanical and dynamic properties of soil, there is a lack of experimental studies that cover the influence of D/H ratio on the liquefaction potential of sand under stress and strain-controlled conditions. In this study, the influence of the D/H ratio on the cyclic behaviour and liquefaction potential of Ottawa sand C-109 and Ottawa sand F-65 specimens is experimentally investigated. Reconstituted soil specimens of Ottawa sands were prepared at four different D/H ratios using the combined triaxial simple shear (T_xSS) and conventional DSS devices. The influence of the D/H ratio on the cyclic behaviour in terms of pore pressure generation and decay …

The results of cyclic strain-controlled tests performed on reconstituted specimens of Ottawa sand F-65 using the combined triaxial simple shear (T_xSS) apparatus were used to establish a strain/energy-based pore pressure model. The model was utilized in conjunction with the sigmoid function (SIG4) to simulate the cyclic behavior of Ottawa F-65 sand under stress and strain loading conditions using FLAC at the element-level and in 1-D effective stress analysis. A counterpart set of cyclic stress-controlled direct simple shear (DSS) tests was performed to assess the predictive capability of the numerical model to determine the liquefaction potential curves. Two dynamic centrifuge tests were simulated using the proposed model and Finn model, and a satisfactory comparison of the observed and computed responses in terms of pore water pressure generation at different depths was obtained. Furthermore, model …