Implementation of Audio Effect Generator in FPGA

This paper describes the theory and implementation of audio effects such as echo, distortion and pitch-shift in Field Programmable Gate Array (FPGA). At first the mathematical formulation for generation of such effects is explained and then the algorithm is described for its implementation in FPGA using Very high speed integrated circuit hardware descriptive language (VHDL). The digital system being designed, which is synthesizable and reconfigurable, offers a great flexibility and scalability in designing and prototyping in FPGAs. The system is divided into three HDL blocks, each for echo, distortion, and pitch-shift effect generation, which are multiplexed in order to share the common ADC and DAC. The audio effect generator designed in this paper was successfully implemented in Spartan-3E FPGA utilizing the resources available effectively. There has been tremendous research being carried out in the field of IP core. Efficient IP cores designed to carry out digital signal processing are implemented in every modern device using configurable logics. This trend hasn’t yet been realized in Nepal. Through the design and implementation of audio effect generator, this paper also aims at bringing the field of IP core development to limelight among scholars of Nepal.DOI: http://dx.doi.org/10.3126/njst.v15i1.12022 Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 89-98

Simulation and Analysis of Biogas operated Double Effect GAX Absorption Refrigeration System

A thermodynamic simulation of a double effect generator heat exchanger absorption refrigeration cycle using biogas as source of energy has been carried out. The binary mixture considered in the present investigation was NH3 – H2O (Ammonia - Water). This simulation was performed in order to investigate the effect of the temperature and pressure of the high temperature generator and the pressure of evaporator have over the Coefficient of Performance (COP) for a constant condenser and absorber temperatures. The basic parameters at various state points of the cycle was computed using standard correlations. The solution circulation rates and volume of biogas required for operation of the cycle are analysed for the variations in operating parameters at the high temperature generator and evaporator.

On the Boundedness of the Dimensionless Index of Performance of a Nernst Effect Generator

The author, in an earlier paper, analyzed a Nernst effect generator by the usual thermodynamic methods and found that a bound of unity arises on the dimensionless quantity θT where θ is given as the square of the product of the Nernst coefficient and magnetic field divided by the thermal conductivity and electrical resistivity. By application of the appropriate equations of semiconductor theory this bound is shown to be justified for four limiting cases: Weak magnetic fields considering both extrinsic and intrinsic materials, and strong magnetic fields considering both extrinsic and intrinsic materials.

A Nernst Effect Power Generator

The direct conversion of heat to electricity by means of the Nernst effect is analyzed. The Nernst effect is the creation of an electrical potential perpendicular to both an applied temperature difference and an applied magnetic field. The effect is pronounced in semiconductors which have large mobility, large mobility ratio, and relatively small energy gap. Indium antimonide exhibits theoretically the best performance to date. A Nernst effect generator using indium antimonide experiencing an applied temperature difference of 300 deg K and a magnetic flux density of 10 kilogauss would have a thermal efficiency of about 1.6 percent and a power density of 10 watts per cubic centimeter.