Prakash R. Apte

Designing Asymmetric 2.4 GHz RF Oscillator for improving Signal Integrity by Design of Experiments

Designing of an Asymmetric RF Oscillator for improved Signal Integrity, using Design of Experiments is presented and Taguchi Orthogonal Array is used for the same. Dependence of various physical parameters on output quality parameters that are Eye Height and Jitter, are shown by curves. Jitter is reduced and Eye Height is increased and as outcome of both, Eye SNR is increased. All in all, Designing of an Asymmetric Oscillator for better Signal Integrity is shown using Design of Experiments.

Experimental evaluation of current transformer performance under saturation

Current transformers form an integral part of protective systems. Ideal current transformers (CTs) are expected to reproduce the primary current faithfully on the secondary side. Often, during fault conditions an important component of current is exponentially decaying DC offset current. Under such conditions the CT saturates, and hence it cannot reproduce the primary current faithfully. This paper deals with experimental methods for determining CT performance under saturation. A laboratory setup has been developed to observe CT response under steady state and fault conditions. Thus, it is now possible to experimentally evaluate the CT performance under fault conditions

Optimizing Phase Noise of 2 GHz RF oscillator with minimum frequency deviation

Phase Noise optimization for RF oscillator using Design of Experiments (DOE) is presented. The constraint of keeping frequency deviation minimum is taken in to account by ANOVA and nominal-the-best approach of Taguchi methods. Phase Noise of the oscillator is improved by −3.6 dB with frequency deviation of 0.04 %. Power consumption is also reduced by 3.2 mW. 1

Minimization of Ovality of Circular Holes in Drilling Process

In drilling and boring process, the relief in clamping stress causes deformations that cause variations in the geometry of the drilled hole. In automobile industry, when such holes are used to hold gear systems or rods in place, this variation in geometry leads to poor fitting and subsequent failure. To avoid this, high level accuracy is required which is both expensive and time-consuming. Therefore, a high percentage of such drilled parts are rejected in industry. The present paper addresses this problem by characterizing the variations in hole geometry as a function of clamping force, hole diameter, hole eccentricity (distance of hole-center from center of drilled face) and angular position of hole with respect to clamp location. The analysis result quantifies the comparative effect of each aforementioned factor on hole geometry variation. Taguchi Method based Design of Experiments using L25 orthogonal array has been used for performing the parametric design to arrive at the best settings of the 4 parameters. The optimal settings minimize ovality and displacement of the hole-center, and thus increase hole-fitting and its reliability against manufacturing variability.

Novel Design of Valve Stem to Eliminate Buckling

Acceptable variations in the length of the valve stem, in a conventionally manufactured valve, give room to the possibility of the stem to buckle and get jammed in the guide. Salvaging such a situation is expensive and time consuming. The present paper addresses this problem by increasing the compliance of the valve stem by introducing holes in it. The desired elastic deformation along the length, however, causes transverse deformation, which needs to be minimized. The use of multiple holes helps achieve this. Taguchi Method based Design of Experiments using L25 orthogonal array has been used for performing the parametric design to arrive at the best settings of the 5 parameters. The optimal settings eliminate the buckling and thus make the operation of the valve stem robust against manufacturing variabilities.

Optimization of Tensile Properties of Epoxy/Nanoclay/MWNT Nanocomposites by Taguchi Method

In this study, nanoclay and multi-wall carbon nanotubes have been used as a dual filler in an epoxy matrix. In the design of the experiment (DOE) the Taguchi Method was selected to study the effect of the factors involved in this study. The effect of the clay/MWNT ratio, types of solvent, clay cation, composition of LENR, cure time and cure temperature on tensile properties of the epoxy nanocomposites were investigated. The confirmation experiment obtained from Taguchi analysis, achieved 57% improvement in tensile strength. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the presence of intercalated and aggregated structures. Due to the lower crosslink density of the system, a decrease in decomposition temperature and glass transition temperature was observed in the optimum sample.

Design and testing of heuristic for market splitting in electric power exchange

This paper proposes Taguchis method for design of experiments to test market splitting algorithm of an electric power exchange. Such a mechanism is required because price-volume pairs of a trader are usually bound by confidentiality requirement and hence not available as test data. We also propose a novel and simple market splitting heuristic considering congestion management problem in a meshed network with incomplete information of the network. Simulation results are reported in the paper.

2D simulation of multilayered MEMS structures

MEMS device structures, particularly those made using Surface-Micromachining, consist of thin layers of insulator, silicon, silicon dioxide, silicon nitride, metal or poly-silicon held at few points onto a thick silicon substrate. These heterogeneous layers resemble closely to laminas of composites used in building structures. For these heterogeneous material systems, involving Metal-Insulator-Semiconductor layers, there is usually an inherent two dimensional thermal contraction of the various layers upon cooling from a growth temperature of 1000 to 1200 C down to room temperature. The thermal stress, so developed, could result in static deformation as well change the dynamic characteristics of the micro-parts. Thin heteroepitaxial layers, with lattice mismatch with the single crystal substrate, can also result in a built in stress. External effects like electrostatic potentials and magnetic fields applied to a layered structure can also result in contractions or extensions of specific layers that respond to applied fields. A generic formulation of governing equations of equilibrium and compatibility has been developed for laminated structures with various in-built stress effects like difference in temperature of formation and use; difference in lattice constants of heteroepitaxial layers; effects that involve dimensional changes like piezoelectric effect and magnetostriction. This paper aims at demonstrating, through simulations of a test structure of a doubly suspended resonator, how these multi-layer structures could exploit the static deformations to result in a robust (temperature-insensitive) dynamic response. The static deformation for temperature changes in a bi-layer of aluminum and silicon dioxide is simulated on ANSYS. The results of ANSYS match very well with a fabricated test device.