A statistical analysis of rotary friction welding of steel with varying carbon in workpieces

Laser drilling is increasingly becoming the method of choice for precision drilling for variety of components. However, a number of defects such as spatter, recast, heat-affected zone (HAZ), and taper limit the application. Elimination of these defects is the subject of intense research. This paper presents a grey relational optimization approach for the determination of the optimum process parameters which minimize the HAZ and hole circularity and maximize material removal rate in a Pulsed Nd:YAG laser micro-drilling in high carbon steel within existing resources. The input process parameters considered are pulse width, number of pulses, assist gas (oxygen) flow rate, and its supply pressure. A higher resolution-based L₂₅ orthogonal array has been used for conducting the experiments. The designed experimental results are used in grey relational analysis and the weights of the quality characteristics are determined optimizing the parameters. On the basis of optimization results, it has been found that the optimal parameter level gives a small HAZ, fine hole, and maximum material removal rate. Subsequently, the results are also verified and found appropriate by running confirmation tests.     

Short-term hydrothermal scheduling using clonal selection algorithm

An efficient optimization procedure based on the clonal selection algorithm (CSA) is proposed for the solution of short-term hydrothermal scheduling problem. CSA, a new algorithm from the family of evolutionary computation, is simple, fast and a robust optimization tool for real complex hydrothermal scheduling problems. Hydrothermal scheduling involves the optimization of non-linear objective function with set of operational and physical constraints. The cascading nature of hydro-plants, water transport delay and scheduling time linkage, power balance constraints, variable hourly water discharge limits, reservoir storage limits, operation limits of thermal and hydro units, hydraulic continuity constraint and initial and final reservoir storage limits are fully taken into account. The results of the proposed approach are compared with those of gradient search (GS), simulated annealing (SA), evolutionary programming (EP), dynamic programming (DP), non-linear programming (NLP), genetic algorithm (GA), improved fast EP (IFEP), differential evolution (DE) and improved particle swarm optimization (IPSO) approaches. From the numerical results, it is found that the CSA-based approach is able to provide better solution at lesser computational effort.     

Multiplier less high-speed squaring circuit for binary numbers

The squaring operation is important in many applications in signal processing, cryptography etc. In general, squaring circuits reported in the literature use fast multipliers. A novel idea of a squaring circuit without using multipliers is proposed in this paper. Ancient Indian method used for squaring decimal numbers is extended here for binary numbers. The key to our success is that no multiplier is used. Instead, one squaring circuit is used. The hardware architecture of the proposed squaring circuit is presented. The design is coded in VHDL and synthesised and simulated in Xilinx ISE Design Suite 10.1 (Xilinx Inc., San Jose, CA, USA). It is implemented in Xilinx Vertex 4vls15sf363-12 device (Xilinx Inc.). The results in terms of time delay and area is compared with both modified Booth’s algorithm and squaring circuit using Vedic multipliers. Our proposed squaring circuit seems to have better performance in terms of both speed and area.     

Preparation of Starch/PVA/CaCO3 Nanobiocomposite Films: Study of Fire Retardant,Thermal Resistant,Gas Barrier and Biodegradable Properties

Starch/PVA/CaCO₃ nanobiocomposite films were prepared by the solution casting method. The prepared nanobiocomposite films were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) methods. The fire retardant, tensile strength and thermal properties of nanobiocomposite films were enhanced with increasing percentage of CaCO₃. When the concentration of nano-CaCO3 was increased, the oxygen permeability of starch/PVA/CaCO₃ was reduced. The increase in fire retardant and oxygen barrier properties along with improvement in thermal and tensile properties of nanobiocomposite may enable the material suitable for packaging application.     

SPLIT-WINDING STARTING OF A SINGLE-PHASE INDUCTION MOTOR

Abstract

Results of investigation of starting a single-phase induction motor having a single stator winding and using normal stator and rotor punchings are presented in this paper. Theoretical and experimental studies show that the motor requires less copper for its stator winding compared to a split-phase motor and the overall starting performance is very satisfactory.     

Multiuser Massive MIMO Channel Estimation and BER Analysis Using Convex Combination Based Algorithms

Wireless Personal Communications - Massive multiple-input multiple-output (MIMO) employs a large antenna array and is used as a key technology in 5G communication standards. In this work,...     

A novel approach for reactive power compensation in hybrid wind-battery system using distribution static compensator

This paper proposes a novel algorithmic approach to compensate the reactive power using distribution static compensator (DSTATCOM) for wind energy conversion system (WECS). Three phase bidirectional converter is utilized to exchange real and reactive power in both directions. The plug-in hybrid electric vehicle (PHEV) is enabled to consume during excess power availability. The battery is connected through a separate bidirectional DC-DC converter to adjust the power at the desired range. The compensated reference current is being generated based on the load requirement, wind power generations and state of charge (SOC) status. The proposed algorithmic approach helps to stabilize the grid by injecting accurate compensating current at the point of common coupling (PCC). Thereby, the proposed approach ensures the grid at balanced states under all operating cases. In order to validate the proposed approach, different case studies have been considered and validated through simulation results using PSCAD/EMDTC software.     

A Comparison of Machinability in Hard Turning of EN-24 Alloy Steel Under Mist Cooled and Dry Cutting Environments with a Coated Cermet Tool

Journal of Failure Analysis and Prevention - In this current research, mist cooling and dry cutting effects on cutting force, flank wear, chip morphology, crater wear, surface roughness and...     

Dielectric and impedance spectroscopy of Bi(Ca0.5Ti0.5)O3 ceramic

Bismuth calcium titanate (BiCa_0.5Ti_0.5O₃) ceramic, fabricated by a ceramic processing technique, has been characterized using a variety of experimental techniques. Analysis of basic crystal structure using X-ray diffraction data exhibits the orthorhombic system. Measurements and detailed analysis of some electrical parameters (i.e.,dielectric constant, loss tangent (energy loss), electrical impedance and modulus, conductivity, etc.) of Bi(Ca_0.5Ti_0.5)O₃ in a wide range of frequency (10³–10⁶ Hz) and temperature (30–500 °C) have provided some interesting and useful data and results on structure–properties relationship, conduction mechanism, etc.The role of interface, space charge polarization and Maxwell–Wagner dielectric relaxation in getting high dielectric constant of the material at low frequencies and high temperatures has been discussed. Study of temperature dependence of Nyquist plots clearly shows the contributions of grains in resistive and capacitive properties of the material. The frequency of the applied electric field and temperature strongly affect the dielectric (permittivity and dissipation of energy) and electrical (impedance, electrical modulus and conductivity) characteristics of the material.