This paper proposes to improve the selectivity and sensitivity of biomedical signals for the detection of biomedical signals EEG, ECG, EMG, based on the piezoresistive principleand MEMS/NEMS (Micro-Electro-Mechanical System) technology. Firstly, according to the characteristics of biomedical signals and detection, the U shaped micro and structure has been proposed, and the fabrication, characterization using SEM,LDV analysis have been carried out. Different designs of MEMS/NEMS cantilevers are fabricated and identified theresonance frequency response of the nano structure, its structure sizes have been determined.Secondly, the processing technology of the micronanostructure with the formation of material over the cantilever hasbeen observed for to increase the sensitivity and sensitivity and the detection of biomedical signals.The advantages of incorporating four cantilevers in the U shaped on the piezoresistive micro cantilever and its optimal position for maximum sensitivity is also studied in this paper. Different designs of cantilevers were modeled and it is found that U shaped cantilevers are found to be suitable structure showing maximum sensitivity for the detection of biomedical signals accurately.

Accurate measurement of oil, water and gas flow without separation has always been a challenge in the oil and gas industry as it involves estimation of five different parameters. One of the critical parameters to estimate is Water-Cut (WC), which is the ratio of water flow rate to the total liquid flow rate. In this paper we employ microwave sensing techniques to measure WC. To establish the accuracy of microwave sensors for WC estimation a static mixer based approach is established with a ground truth accuracy of . Based on this ground truth the Water-Cut estimation accuracy is found to be ±1.5%. This paper is comprehensive summary of the experimental procedure, approach to estimate the uncertainty in reference Water-Cut and the performance of microwave sensors in estimating Water-Cut.

Accurate and reliable measurement of oil, gas and water flow rates as they flow along a pipe as a mixture continues to be a challenging problem in the oil and gas industry. Most of the solutions rely on radioactive sources. This paper explores the use of microwave sensors for flow rate measurement. Microstrip Patch sensors in transmission mode and a near field coaxial probe in reflection mode are used to estimate water fraction even in lossy (saline) medium using physics based models with minimal calibration. Reflection measurements from the Patch sensors are used to estimate gas fraction using empirical models which can enable measurement of gas in high loss cases. Gas velocity is measured from cross correlation. A low cost 5-port measuring instrument was built to do reliable reflection and transmission measurements over a wide temperature range. The microwave system was tested in in-house and external flow loops and in the field under varying temperatures and flow conditions and test results are presented in this paper.

Accurate multiphase flow measurement hinges on the ability to measure flow parameters such as component phase fractions and velocities with high accuracy. Since, the fractions and velocities are not always uniformly distributed in the measurement cross section, any measurement system’s inability to account for spatial variations can result in a high degree of uncertainty in the estimated flow rate. This paper describes a method using an impedance based measurement system using which the profiles of phase fraction and velocity for a vertical pipe downstream of a blind tee can be measured and characterized. Using the same measurement, a modified cross correlation technique provides the vertical and horizontal components of the velocity in a swirling flow. This velocity information along with the phase fraction profile characterizes the flow profile completely. In addition to this analysis, the potential effect of swirl on differential pressure measurements is addressed briefly. Nomenclature τ i j max Time shift corresponding to maximum cross correlation for pixel i j, page 6 P Pressure, page 13 R j,kl xy Cross correlation of series x at pixel i j with y at pixel kl, page 10 R j xy Cross correlation of series x and y at pixel i j, page 6 Vi j Velocity measured at pixel i j, page 6 ρ Density, page 12 1 τ Time shift for cross correlation, page 6 dP Differential pressure, page 12 d j rad Radial distance traveled by pixel i j, page 10 dax Axial distance between cross correlation planes, page 10 r,θ ,z Cylindrical coordinates, page 12 t Time instant, page 6 t Time instant, page 12 ur Radial component of velocity, page 12 uθ Angular component of velocity, page 12 uz Vertical/Axial component of velocity, page 12 xi j,yi j Time series at two planes of measurement at pixel i j, page 6 GVF Gas volume fraction, page 4 WLR Water in liquid ratio, page 4

There are two important factors that make multiphase flow particularly hard to characterize. One is the complex interaction between the different phases and components. The other is the dependence of this interaction on several aspects of the flow itself such as component flow rates, component densities and viscosities, temperature and pressure. Based on the characteristics of this interaction, the flow is categorized into what are referred to as flow regimes. In gas-liquid vertical flows, the flow regimes most commonly encountered are bubbly, slug, churn and annular. Early attempts at modelling the flow physics tended to lump all flow regimes into one, which while greatly simplifying the analysis, were inadequate in describing the intricacies of each regime [2]. Thus, generic models typically fall short in terms of accuracy and reliability. Yet another challenging aspect of modelling multiphase flow is its non-uniform and time varying nature. Research efforts tend to address this issue in one of two ways make the model less complicated by assuming temporal or spatial uniformity or account for non-uniformities through correction terms determined empirically or analytically.

Performance of MEMS devices relies largely on the interaction between structural actuation membranes and fluids surrounding them. When optimizing these MEMS design it is important to consider the general characteristics of this fluid-structure interaction. Finite Element approach is used to study the effect of mass damping and stiffness damping arising due to micro fluid layers in Micro-machined Air-coupled Capacitance transducer. Transient dynamics of these systems are completely driven by this fluid-structure interaction. The aim of this paper is to understand the variations in mass and stiffness damping with frequency of operation. Furthermore, the effect of the mass and stiffness damping with geometrical parameters and transient behavior of the system are discussed.

Ultrasonic forms an important tool in industrial health and process monitoring. In general, ultrasonic wave propagation studies are carried out in a stationary medium. But in certain scenarios, medical application included, it is essential to understand ultrasound path in a non-stationary medium. In this paper, we quantify the influence of a moving medium on the propagation of ultrasound through a finite element implementation of a modified wave equation. Analytical profile for the velocity of the moving medium is mapped over the spatial domain. Results for the beam drift due to the moving medium for both normal and angular incidence of the wave are presented.

This paper presents a comparison of three Finite Element approaches for modeling the behavior of a Capacitive Micromachined Ultrasonic Transducer (CMUT). CMUTs have become very popular over the last decade because of the comparable bandwidth, sensitivity and dynamic range with its piezoelectric counterparts. The ease of fabrication is an added advantage. Modeling of CMUTs is a coupled physics problem, which involves solving Electrostatics and Structural interactions simultaneous. Finite Element models of the CMUT are constructed using the commercial code ANSYS (9.0). Three different approaches of solving the coupled field problem are discussed and the results are compared for resonance frequency, collapse voltage, capacitance and electromechanical coupling coefficient. The approaches discussed involve sequentially coupled-field analysis, direct coupled-field analysis and reduced order modeling. Detailed results have been presented for the effect of variation in geometrical factors as predicted by the three models.

This paper aims at developing a numerical model for guided wave propagation in plates and the interaction of modes with defects using Finite Element Modeling (FEM). Guided waves propagate as extensional, flexural and torsional waves. Theoretically, these modes are infinite in number, but only some of these propagate and the others are attenuated. The dispersion curves for a structure reveal the plausibility of these modes. In this paper, FEM is used to examine interaction of first few symmetric and anti‐symmetric modes independently with the cracks of various sizes in a plate. A time‐frequency representation of the acquired guided wave mode signals will be discussed to show the mode sensitivity with crack size.

Time frequency representation (TFR) of ultrasonic signals plays an important role in describing the propagation and dispersive effects in thin walled structures. In this paper, Generalized time-frequency representations viz. the Wigner-Ville distribution, Choi-William distribution and Short-Time Fourier Transform are discussed in the context of mode analysis. A comparison on the estimation of various modes and the obscuring interference terms, due to bilinear structure of TFRs, is presented for lamb waves in aluminum plates. Studies on the performance of TFRs in the presence of strong colored noise are presented.