Sharif Digital Repository

In this paper, a three-invariant cap plasticity is developed for description of powder behavior under cold compaction process. The constitutive elasto-plastic matrix and its components are derived as the nonlinear functions of powder relative density. Different aspects of 2D and 3D cap plasticity models are illustrated and the procedure for determination of powder parameters is described. It is shown how the proposed model could generate the elliptical yield surface, double-surface cap plasticity and the irregular hexagonal pyramid of the Mohr-Coulomb and cone-cap yield surface, as special cases. The single-cap plasticity is performed within the framework of large finite element deformation,... 

This article presents an applicable intuitive current-voltage model for long-channel transistors based on 2-D materials. This model carefully predicts the transistor behavior in the saturation and triode regions, which are important for analog and digital applications. Moreover, the effect of mobility degradation on the characteristics of the transistor is probed. As a case study, the developed model has been applied to a transistor with mono-layer MoS2 as the channel material. The excellent agreement with experimental data verifies the accuracy of the model. Finally, the introduced model has been utilized to design an amplifier, a differential pair, and a low-frequency common source mixer... 

It is shown that a compact MOSFET-aging model for circuit simulation is possible by considering the dynamic trap-density increase, which is induced during circuit operation. The dynamic trap/detrap phenomenon, which influences the switching performance, is also considered on the basis of well-known previous results. Stress-dependent hot-carrier effect and NBTI effect, origins of the device aging, are modeled during the circuit simulation for each device by integrating the substrate current as well as by determining the oxide-field change due to the trapped carriers over the individual stress-duration periods. A self-consistent solution can be obtained only by iteratively solving the Poisson... 

A modified plastic yield function is proposed to predict the consolidation behavior of nanostructured metal powders and metal-matrix nanocomposite powders under uniaxial compaction. The validity of the model is verified for nanocrystalline Al6063 (~100nm) alloy reinforced without and with 0.8vol.% Al2O3 nanoparticles (~25nm). The plastic deformation propensity of these powders is analyzed by linear compaction equations. The yield stress of the powder compacts is shown to be influenced by the nano-scale grains and the reinforcement nanoparticles