(SoE) School of Engineering

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

This communication reports the effects of multiphase flow on the corrosion product formed on the surface of 1018 C-steel coupons in oil and gas lines in presence of inhibitor oleic imidazoline. Both bulk and surface analytical techniques reveal the presence of FeCO3, a classic example of CO2 corrosion. While significant changes in the surface morphology with flow condition are monitored by SEM and OM, detailed AES and XPS analysis show the deterioration of inhibitor chemistry as the flow is increased from full pipe (Fr = 0) to slug flow (Fr = 6). XPS shakeup satellite lines in the N (1s) spectra have been useful in the analysis. (C) 2000 Elsevier Science Ltd. All rights reserved. This communication reports the effects of multiphase flow on the corrosion product formed on the surface of 1018 C-steel coupons in oil and gas lines in presence of inhibitor oleic imidazoline. Both bulk and surface analytical techniques reveal the presence of FeCO3, a classic example of CO2 corrosion. While significant changes in the surface morphology with flow condition are monitored by SEM and OM, detailed AES and XPS analysis show the deterioration of inhibitor chemistry as the flow is increased from full pipe (Fr = 0) to slug flow (Fr = 6). XPS shakeup satellite lines in the N (1s) spectra have been useful in the analysis.

World University root node

Electrical Engineering

Corrosion Science

Effect of multiphase flow on corrosion of C-steel in presence of inhibitor: A surface morphological and chemical study

A 0.1-m ID acrylic pipe, with four 36-inch radius 90° sweep, clear PVC bends test facility has been constructed to allow for visualization of flow characteristics in hilly terrain and topographies with short elevation changes. The height of the riser and crossing length is 5 meters. A detailed visualization of multiphase flow regimes and flow characteristics using water-carbon dioxide mixtures has been carried out. Visual observations of enhanced turbulence regions were noted and characteristics were noted at different velocities for nine locations along the system. ER probes are used to monitor corrosion rates in the first two bends where elevated turbulence was noted. Corrosion rates observed in the bends are compared to previous rates recorded in horizontal pipelines under similar operating conditions. © 2000 by NACE International.

NACE - International Corrosion Conference Series

Multiphase flow and its effects on localized corrosion in regions with abrupt inclination changes

In multiphase flow, bubbles are produced and collapse on the solid/liquid interface. Bubble collapse can enhance the CO2 corrosion of carbon steel pipe, as shown by coupon surface analysis, corrosion rate measurements and visualization of bubble movement in multiphase flow. Using the electrochemical limiting current density technique, experiments have been carried out to study the effect of bubbles on mass transfer in an electrochemical cell and in slug flow. The limiting current density signal as a function of time and frequency shows the direct influence of bubble movement on mass transfer. It also indicates the difference of mass transfer in fully developed turbulent flow, an electrochemical cell and slug flow. The enhancement of mass transfer coefficient by bubble collapse is considered an important factor that contributes to the increased corrosion rate in multiphase flow. © 2000 by NACE International.

Effect of bubbles on mass transfer in multiphase flow

Tracking of multiple targets by using only the bearing information is an important problem in passive sensing scenarios such as passive sonar or infrared seeker applications. In this paper, a new algorithm is presented to adaptively estimate the DOA's of multiple moving targets when Linear Equispace Array (LES) is used for making the measurements. These algorithms are based on Differential MUSIC method. The results obtained by these algorithms are then applied as input to a Non-Linear state linear Measurement unscented filter. The unscented filter based tracker is compared with the EKF based tracker. Simulation results show that the former is superior to the latter.

Proceedings of the IEEE International Conference on Industrial Technology

Passive target tracking by unscented filters

Corrosion rates at the top and bottom of the pipe have been measured in wet gas multiphase flow at carbon dioxide partial pressures of 0.46 MPa and 0.79 MPa and temperatures of 40 C and 60 C in a high pressure 10-cm diameter system. Gas velocities up to 30 m/s and liquid velocities up to 0.5 m/s were used. The liquid consisted of a mixture of de-ionized water and low viscosity oil at two water cuts of 80% and 40%, and carbon dioxide was used in the gas phase. Corrosion inhibition studies were carried out at 50 ppm and 100 ppm dosage levels. The inhibitor used was an oleic imidazoline active compound dissolved in isopropyl alcohol and water. The corrosion rate was found to increase with increase in gas velocity, liquid velocity, temperature and CO2 partial pressure. The corrosion rate at the top of the pipe is negligible up to a gas velocity of 20 m/s. However, at a gas velocity of 30 m/s, there is substantial and measurable corrosion at the top of the pipe. This was attributed to wave spreading. Addition of inhibitors reduced the corrosion rate at the top and bottom of the pipe significantly. However, the corrosion rates are not negligible. © 2000 by NACE International.

Inhibition of multiphase wet gas corrosion

This paper presents the experimental results for CO2 corrosion of C-1018 carbon steel in a multiphase flow system using electrochemical noise measurement. A unique biased ZRA mode electrochemical noise technique is utilized to study the corrosion processes and detect localized corrosion preferentially on a single electrode due to external polarization of the bias voltage under extended exposure times. For full pipe flow at 0.55 m/s liquid velocity, the experimental results show that both noise resistance Rn and noise impedance Rosn can be related to the corrosion activity. The trends of Rn and Rosn at different experimental times are also consistent with the results obtained from EIS experiments. The experimental results at slug flow of Froude Numbers of 6 and 9 show that the magnitude of current noise increases with the increase of flow turbulence, Compared to slug flow, the current noise fluctuation for full pipe flow is much lower. © 2000 by NACE International.

Corrosion monitoring using electrochemical noise measurement with bias voltage

We reconsider the mode of operation of a Marx bank circuit and analyze the secondary breakdown of transistors with shorted emitter-base. The mechanism of breakdown of the transistor when a fast rising voltage pulse is applied across is investigated. The device exhibits chaotic behavior at the breakdown point where it can go into two possible modes of breakdown. A new explanation for the working of the circuit consistent with the experimental observations is proposed.

Solid-State Electronics

Breakdown of transistors in Marx bank circuit

We describe a deterministic parallel algorithm for linear programming in fixed dimension d that takes poly(log log n) time in the common concurrent read concurrent write (CRCW) PRAM model and does optimal O(n) work. In the exclusive read exclusive write (EREW) model, the algorithm runs in O(logn·log logd-1 n) time. Our algorithm is based on multidimensional search and effective use of approximation algorithms to speed up the basic search in the CRCW model. Our method also yields very fast poly(log log n) algorithms for smallest enclosing sphere and approximate ham-sandwich cuts and an O(log n) time work-optimal algorithm for exact ham-sandwich cuts of separable point sets. For these problems, in particular for fixed-dimensional linear programming, o(log n) time efficient deterministic PRAM algorithms were not known until very recently. © 2000 Society for Industrial and Applied Mathematics.

SIAM Journal on Computing

Fast and optimal parallel multidimensional search in prams with applications to linear programming and related problems

We describe a model that enables us to analyze the run-nine time of an algorithm in a computer with a memory hierarchy with limited associativity, in terms of various cache parameters. Our model, an extension of Aggarwal and Vitter's I/O model, enables us to establish useful relationships between the cache complexity and the I/O complexity of computations. As a corollary, we obtain cache-optimal algorithms for fundamental problems like sorting, FFT, and an important subclass of permutations in the single-level cache model. We also show that ignoring associativity concerns could lead to inferior performance, by analyzing the average-case cache behavior of mergesort. Our techniques may be used for systematic exploitation of the memory hierarchy at the algorithm design stage, and dealing with the hitherto unresolved problem of limited associativity.

Fulltext

Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms

Towards a theory of cache-efficient algorithms

This communication reports the effects of multiphase flow on the corrosion products formed on the surface of 1018 C-steel coupons in oil and gas lines. The main objective of this paper is to understand the effects of multiphase flow (full pipe and slug flow Fr. No. 6 and 9 at various flow and oil-water mixtures) on the morphology and the porosity of the C-steel coupon subjected to a horizontal test loop. The corrosion product layer formed on the surface of the steel coupons were analyzed using Scanning Electron Microscopy (SEM), Electron Dispersive Spectroscopy (EDS), X-ray mapping, Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). Detailed porosity calculation has been carried out using metallographic software. The porosity increases as the flow velocity is increased. The corrosion product layer is primarily made of iron carbonate crystals along with Na and CI as indicated by EDS measurements. Detailed XPS analysis show the deterioration of inhibitor film as the flow is increased from full pipe (Fr = 0) to slug flow (Fr = 6). XPS shakeup satellite lines in the N (1s) spectra have been useful in the analysis. © 2000 by NACE International.