Experimental results show that there are uninterpreted physical phenomena in the resistivity behavior of carbon nanotubes (CNT) in terms of their diameter changes. In this paper, a model based on previously published empirical data is created. This model is used later to analysis the effect of repulsion on electron transport throughout CNT. The relationship between the resistivity and the diameter of CNT, with an introduced parameter named 'electron gas hardness' has theoretically investigated. The results show an acceptable theoretical model for the behavior of electrical resistivity to reduce the diameter of nanotubes and is predicted by physico-mathematical calculations. Furthermore, a detailed analysis of the temperature effects on the transport properties in CNT and how compare to electron-phonon interactions that have been shown to affect resistivity and a theoretical model of electrical resistivity to changes of two important parameters of diameter and temperature of carbon nanotubes, physical formulation and modeling is presented.These results are consistent with the experimental results and are generalized.

Wire EDM is a modern machining process that uses electrical discharge to cut workpieces. High temperatures generated by wire EDM can cause surface cracking due to metallurgical changes. A new approach is to use the ultrasonic peening treatment to cause surface severe plastic deformation to improve the mechanical properties, especially the hardness. In this study, the focus was on exploring the impact of cutting types in wire EDM, feeding rate, and the number of peening passes as input parameters on Mo40 (1.7225) alloy steel. The experiments were designed using the multilevel factorial design method. The average hardness values were then analyzed based on the input parameters. The maximum hardness value was determined through optimization using the multilevel factorial design method. Analysis of variance was used to evaluate the impact of parameters on hardness. The highest hardness value of 952.7 (HV) was obtained with a feeding rate of 0.12 (mm/rev) and 3 peening passes in roughing mode, leading to a 48% increase in hardness. A mathematical model with 99.87% desirability was developed to study the correlation between input parameters and response variables. The hardness distribution in the peened workpieces continued up to 200 µm below the surface layers. The highest hardness was found at a feeding rate of 0.12 (mm/rev), which influences the time needed to alter dislocation density and form a new sublayer structure. Overall, increasing the feeding rate decreases hardness, while increasing peening passes increases it. According to a single-objective optimization, the cutting types, feeding rate, and number of peening passes respectively affect hardness value.

Effects were studied of 200 ppm silver and copper nano-suspensions, with size range from 20 to 80 nm, on the hardness of particleboards produced at an industrial scale at the Iran-Choob Factory, Iran. Metal nano-suspensions were added to the mat at two levels of 100 and 150 milli-liters/kg dry weight wood particles, and the results were compared with those of the control panels. Results showed that the high thermal conductivity coefficient of silver nanoparticles broke down part of the resin bonds, it also heat-treated the surface wood particles, resulting in significant decrease in the hardness of treatment with 150 mL/kg. However, in the nanocopper-treated panels, no significant change was observed due to the lower thermal conductivity coefficient of copper, furthermore, as to the formation of higher hydroxyl bonds, it even slightly increased. High significant correlations were determined between most of the physical and mechanical properties of the panels.