Hysteresis and bifurcations in the classical model of generator

The single machine operating onto an infinite bus is analyzed for its nonlinear dynamics using the classical model. Many aspects of limit cycle oscillations, bifurcation, and hysteresis in the system are brought to attention that were not known in the context of a power generator. A parameter graph that determines the nature of the dynamics for a given mechanical power at a given damping coefficient of the rotor is provided which helps determine the precise parameter values where hysteresis effects are to be expected.     

Inhibiting effects of 5-substituted isatin-based Mannich bases on the corrosion of mild steel in hydrochloric acid solution

The inhibition effect of all the three Mannich bases against the corrosion of mild steel in 1 M HCl solution was studied by weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and atomic force microscopy techniques. Data obtained from EIS studies were analyzed to model the corrosion inhibition process through appropriate equivalent circuit models. The adsorption of Mannich bases obeyed Langmuir adsorption isotherm. Both thermodynamic and activation parameters were calculated and discussed. Polarization curves indicate that they are mixed type of inhibitors. All the Mannich bases were adsorbed physically at lower concentration, whereas chemisorption was favored at higher concentration. The results obtained from weight loss, EIS, and Potentiodynamic polarization are in good agreement.     

Finite element modeling of orthogonal micromachining of anisotropic pyrolytic carbon via damaged plasticity

Engineered features on pyrolytic carbon (PyC) have been demonstrated as an approach to improve the flow hemodynamics of the cardiovascular implants such as bileaflet mechanical heart valve. PyC also finds application in thermonuclear and missile components due to its unique directional thermal properties. However, very little work has been reported on modeling of machining/micromachining of PyC. Note that PyC is a brittle anisotropic material and its machining characteristics differ from plastically deformable isotropic materials. Consequently, this study is aimed at developing a finite element model to understand the mechanics of material removal in the plane of transverse isotropy (horizontally stacked laminae) of PyC. A damaged plasticity model has been used to capture the effect of material degradation under machining. Uniaxial tension/compression tests have been carried out to calibrate the damaged plasticity model. A cohesive element layer has been used between the chip layer and the bulk material to simulate the delamination/peeling effect. The model predicts cutting force and thrust forces at different set of process parameters. The orthogonal cutting model has been validated against the experimental data for different cutting conditions for cutting and thrust forces. In addition, the chip geometry has also been compared. The prediction error in the model lies between 9% and 27%. Parametric studies have also been performed to understand the effect of the machining parameters on the process response. It is found that use of the positive rake angle decreases the cutting forces up to 75%.     

Effect of Ultrasonic Shot Peening on Microstructure and Mechanical Properties of High-Nitrogen Austenitic Stainless Steel

The effect of ultrasonic shot peening (USSP) was studied on microstructural modification and mechanical properties such as microhardness, yield strength, tensile strength, and low cycle fatigue (LCF) life of a nitrogen stabilized austenitic stainless steel, at room temperature. There was grain refinement up to nano scale in surface region of the shot peened specimens and the microhardness was increased markedly up to the depth of approximately 100 µm. There was insignificant increase in yield and tensile strength, but drastic reduction in LCF life, particularly at low strain amplitude, from USSP. The nominal increase in yield and tensile strength was due to grain refinement in the surface region and drastic fall in LCF life was due to surface cracking resulting from USSP.     

A mathematical model for transporting the biomass to biomass based power plant

In Punjab, million of tons of agricultural biomass are being generated every year, but it is spatially scattered. The spatial distribution of this resource and the associated costs on collection and transportation are the major bottleneck in the success of biomass energy-conversion facilities. This paper deals with the mathematical model for collection and transporting the biomass from fields to biomass based power plant. The unit transport cost was calculated by using this model. Four systems of transport were conceptualized for two transport modes (tractor with wagon and truck). Three types of agricultural biomass (loose, baled and briquetted) were considered for transport analysis. For all modes of transport, it was observed that unit cost of transport decreases with increase in distance. The transport cost was least for briquetted biomass as compared to loose and baled biomass.     

Design and Self-Consistent Schrodinger-Poisson Model Simulation of Ultra-Thin Si-Channel Nanowire FET

Silicon - Since at the regime of nanometer, the quantum confinement effects are observed and the wave nature of electrons is more dominant. Therefore, the classical approach of current formulation...     

Investigation of N + SiGe Gate Stacked V-TFET Based on Dopingless Charge Plasma for Gas Sensing Application

Silicon - In this paper, a novel n + SiGe pocket layer gate stacked VTFET doping less charge plasma is proposed and analyzed using Silvaco TCAD simulation software. The proposed device...     

Slurry Erosion Resistance of Microwave Derived Ni-SiC Composite Claddings

Silicon - Hydro machinery components such as turbines, pipes, guide vanes, and pumps suffer from severe slurry erosion caused by the abrasive particles entrained in working fluid. In the current...     

Ultra Steep Ge-Source Dopingless Tunnelling Field Effect Transistor with Enhanced Drive Current: DC to Linearity Characteristics Analysis

Silicon - Ge-source dopingless tunnelling field effect transistor (Ge-source DLTFET) with the optimization of dielectric oxide thickness under the source and the gate contacts is proposed and...     

Design and Investigation of SiGe Heterojunction Based Charge Plasma Vertical TFET for Biosensing Application

Silicon - This paper explores the Vertical tunnel FET with the introduced layer of SiGe within the channel/source junction using TCAD. As Tunnel FETs smothered the 60 mV/decade confinement...