Automated implementation of rule-based expert systems with neural networks for time-critical applications

In fault diagnosis, control and real-time monitoring, both timing and accuracy are critical for operators or machines to reach proper solutions or appropriate actions. Expert systems are becoming more popular in the manufacturing community for dealing with such problems. In recent years, neural networks have revived and their applications have spread to many areas of science and engineering. A method of using neural networks to implement rule-based expert systems for time-critical applications is discussed here. This method can convert a given rule-based system into a neural network with fixed weights and thresholds. The rules governing the translation are presented along with some examples. We also present the results of automated machine implementation of such networks from the given rule-base. This significantly simplifies the translation process to neural network expert systems from conventional rule-based systems. Results comparing the performance of the proposed approach based on neural networks vs. the classical approach are given. The possibility of very large scale integration (VLSI) realization of such neural network expert systems is also discussed

Fabrication of micro separation column for miniaturized gas chromatography system

The emphasis of this work is on the fabrication of a micro separation column for applicaton in miniaturized gas chromatography system. The micro column was made by microchannels fabricated on the silicon wafer and sealed with a glass lid. The microchannels were fabricated by wet etching process and the channels were of length 2m , width 200 μm and depth 100 μm. The channels were closed by sealing with Pyrex glass. Silicide bonding was done for the bonding of silicon with Pyrex glass. Ti was used as an intermediate layer and bonded at a temperature of 377 ◦C and a force of 1kN. During bonding Ti forms an alloy with silicon and forms Titanium silicide and this helps to bond the glass wafer with silicom wafer with microchannels etched on it

Zero-Voltage and Zero-Current Switching Buck-Boost Converter for PV Applications

A ZVS and ZCS buck boost converter is presented for PV panel applications. The salient points are that all the switching devices are under zero-current switching during turn-on and zero-voltage switching during turn-off. The active switches in the converter undergo zero-capacitive turn-on losses unlike switches in other soft-switched topologies. The switches do not experience any over voltage/over current stress proportional to load as in resonant converters. This soft-switching technique can also be applied to other classical switched mode power converters. A detailed analysis of the converter under steady state is discussed and simulation results obtained are presented

Beam propagation in an active nonlinear graded-index fiber

A theoretical model is developed by exploiting the variational technique to investigate the evolution of an optical beam inside an optically pumped graded-index fiber amplifier. The variational analysis is a semi-analytical method that provides us with a set of coupled ordinary differential equations for the beam's four parameters. Numerical solution of these equations is much faster compared to the underlying multidimensional nonlinear wave equation. We compare the results of the variational and full numerical simulations for the two pumping schemes used commonly for high-power fiber amplifiers. In the clad-pumping scheme, the use of a relatively wide pump beam results in a nearly uniform gain all along the fiber. In the case of edge pumping, a narrower pump beam provides gain that varies both radially and axially along the fiber's length. In both cases, the variational results are found to be in good agreement with time-consuming full numerical simulations. We also derive a single equation for the beam's width that can predict amplification-induced narrowing of the signal beam in most cases of practical interest.Comment: 6 pages, 5 figure