Assessment of d.c. traction stray currents effects on nearby pipelines

2016 ◽  
Vol 35 (4) ◽  
pp. 1468-1477 ◽  
Author(s):  
Wojciech Machczynski ◽  
Krzysztof Budnik ◽  
Jan Szymenderski
Keyword(s):  
Simulation Model ◽  
Electric Circuit ◽  
Voltage Source ◽  
Electrode Kinetics ◽  
Polarization Phenomenon ◽  
Electrical Equivalent Circuit ◽  
Content Type ◽  
Method Of Calculation ◽  
Non Linear ◽  
Lumped Parameters

Purpose – dc electrified traction systems are a potential source of stray currents. The purpose of this paper is to evaluate the harmful effects (electrolytic corrosion) that an electrified railway has on nearby earth return circuits (e.g. pipelines). Design/methodology/approach – The electric circuit approach, based on the earth return circuit theory, to model stray currents interference on extended structures is presented. An exact method of calculation is applicable to any dc railway system in which tracks can be represented by a single earth-return circuit (equivalent rail) with current energization. In the approximate method, the equivalent rail with current energization is modeled as a large multinode electrical equivalent circuit with lumped parameters. The circuit is a chain of basic circuits, which are equivalents of homogenous sections of the rail. The electrode kinetics (polarization phenomenon) is taken into account in the model developed. Findings – Formulas in partially closed forms are derived applicable to the analysis of currents and potentials along a pipeline laid in the proximity with railway tracks. The attempt is undertaken, to incorporate the electrode kinetics into the simulation model in which the polarization phenomenon (Tafel equation) is modeled by a non-linear voltage source with source voltage being iteratively calculated. The polarization potential along the affected pipeline can be determined. Originality/value – The pipeline electrochemical response (polarization behavior – non-linear phenomenon on the interface metal-soil electrolyte) to the dc stray currents interference is innovative incorporated into the simulation model with lumped parameters using the iterative process.

scholarly journals Distribution system power quality compensation using a HSeAPF based on SRF and SMC features

2021 ◽  
Author(s):  
Akram Qashou ◽  
Sufian Yousef ◽  
Abdallah A. Smadi ◽  
Amani A. AlOmari
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Reactive Power ◽  
Sliding Mode ◽  
Distribution Network ◽  
Harmonic Distortion ◽  
Phase Locked Loop ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Non Linear

AbstractThe purpose of this paper is to describe the design of a Hybrid Series Active Power Filter (HSeAPF) system to improve the quality of power on three-phase power distribution grids. The system controls are comprise of Pulse Width Modulation (PWM) based on the Synchronous Reference Frame (SRF) theory, and supported by Phase Locked Loop (PLL) for generating the switching pulses to control a Voltage Source Converter (VSC). The DC link voltage is controlled by Non-Linear Sliding Mode Control (SMC) for faster response and to ensure that it is maintained at a constant value. When this voltage is compared with Proportional Integral (PI), then the improvements made can be shown. The function of HSeAPF control is to eliminate voltage fluctuations, voltage swell/sag, and prevent voltage/current harmonics are produced by both non-linear loads and small inverters connected to the distribution network. A digital Phase Locked Loop that generates frequencies and an oscillating phase-locked output signal controls the voltage. The results from the simulation indicate that the HSeAPF can effectively suppress the dynamic and harmonic reactive power compensation system. Also, the distribution network has a low Total Harmonic Distortion (< 5%), demonstrating that the designed system is efficient, which is an essential requirement when it comes to the IEEE-519 and IEC 61,000–3-6 standards.

Heat and mass transfer effects on MHD non-Newtonian fluids flow through an inclined thermally-stratified porous medium

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gladys Tharapatla ◽  
Pamula Rajakumari ◽  
Ramana G.V. Reddy
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Velocity Profile ◽  
Heat And Mass Transfer ◽  
Newtonian Fluids ◽  
Transfer Effects ◽  
Content Type ◽  
Non Linear ◽  
Homotopy Analysis ◽  
Flow Through

Purpose This paper aims to analyze heat and mass transfer of magnetohydrodynamic (MHD) non-Newtonian fluids flow past an inclined thermally stratified porous plate using a numerical approach. Design/methodology/approach The flow equations are set up with the non-linear free convective term, thermal radiation, nanofluids and Soret–Dufour effects. Thus, the non-linear partial differential equations of the flow analysis were simplified by using similarity transformation to obtain non-linear coupled equations. The set of simplified equations are solved by using the spectral homotopy analysis method (SHAM) and the spectral relaxation method (SRM). SHAM uses the approach of Chebyshev pseudospectral alongside the homotopy analysis. The SRM uses the concept of Gauss-Seidel techniques to the linear system of equations. Findings Findings revealed that a large value of the non-linear convective parameters for both temperature and concentration increases the velocity profile. A large value of the Williamson term is detected to elevate the velocity plot, whereas the Casson parameter degenerates the velocity profile. The thermal radiation was found to elevate both velocity and temperature as its value increases. The imposed magnetic field was found to slow down the fluid velocity by originating the Lorentz force. Originality/value The novelty of this paper is to explore the heat and mass transfer effects on MHD non-Newtonian fluids flow through an inclined thermally-stratified porous medium. The model is formulated in an inclined plate and embedded in a thermally-stratified porous medium which to the best of the knowledge has not been explored before in literature. Two elegance spectral numerical techniques have been used in solving the modeled equations. Both SRM and SHAM were found to be accurate.

Adaptive efficiency of the Mexican Stock Exchange

2018 ◽  
Vol 31 (2) ◽  
pp. 326-335
Author(s):  
Esmeralda Brito-Cervantes ◽  
Semei Coronado ◽  
Manuel Morales-García ◽  
Omar Rojas
Keyword(s):  
Market Efficiency ◽  
Granger Causality ◽  
Latin American ◽  
Stock Exchange ◽  
Information Process ◽  
Causality Test ◽  
Content Type ◽  
Regulatory Policies ◽  
Adaptive Efficiency ◽  
Non Linear

Purpose The purpose of this paper is to analyse the adaptive market efficiency in the price–volume (P–V) relationship of the stocks listed in the Mexican Stock Exchange. The period under study goes from 1982 to 2015. In order to detect causality and, thus, determine adaptive efficiency in the market, one linear and two non-linear tests are applied. There are few papers in the literature that study the P–V relationship in Latin American markets; as such, this paper may be of interest and importance to financial academics and practitioners alike. Design/methodology/approach The Diks and Panchenko (DP) non-parametric Granger causality and the Brooks and Hinich (BH) cross-bicorrelation tests are applied. Findings Derived from the DP test, the findings show that there exists bi-directional non-linear Granger causality in 25.71 per cent of the firms studied, compared to 8 per cent when applying the linear Granger causality test. Therefore, there is evidence of weak-form efficiency in the market. From the BH test, evidence is shown of the adaptive market efficiency, since 71.42 per cent of firms exhibited some form of non-linear dependence in certain periods of time. With these results, the information process should be better studied for a greater comprehension of regulatory policies in the market and better decision-making tools for the investors. Originality/value This paper complements studies on the P–V relationship and efficiency in a Latin American market.

Non-linear stability analysis of micropolar fluid lubricated journal bearings with turbulent effect

2019 ◽  
Vol 71 (1) ◽  
pp. 31-39
Author(s):  
Subrata Das ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Micropolar Fluid ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Content Type ◽  
Non Linear ◽  
The Stability ◽  
Bearing System

Purpose The purpose of this paper is to investigate the effect of turbulence on the stability characteristics of finite hydrodynamic journal bearing lubricated with micropolar fluid. Design/methodology/approach The non-dimensional transient Reynolds equation has been solved to obtain the non-dimensional pressure field which in turn used to obtain the load carrying capacity of the bearing. The second-order equations of motion applicable for journal bearing system have been solved using fourth-order Runge–Kutta method to obtain the stability characteristics. Findings It has been observed that turbulence has adverse effect on stability and the whirl ratio at laminar flow condition has the lowest value. Practical implications The paper provides the stability characteristics of the finite journal bearing lubricated with micropolar fluid operating in turbulent regime which is very common in practical applications. Originality/value Non-linear stability analysis of micropolar fluid lubricated journal bearing operating in turbulent regime has not been reported in literatures so far. This paper is an effort to address the problem of non-linear stability of journal bearings under micropolar lubrication with turbulent effect. The results obtained provide useful information for designing the journal bearing system for high speed applications.

Investigation of corrosion inhibition of C38 steel in 5.5 M H3PO4 solution using Ziziphus lotus oil extract: an application model

2019 ◽  
Vol 66 (1) ◽  
pp. 121-126 ◽  
Author(s):  
Walid Belmaghraoui ◽  
Aimad Mazkour ◽  
Hicham Harhar ◽  
Mourad Harir ◽  
Souad El Hajjaji
Keyword(s):  
Carbon Steel ◽  
Corrosion Inhibition ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Electric Circuit ◽  
Oil Composition ◽  
Content Type ◽  
Tafel Polarization ◽  
Chemical Content ◽  
Oil Extract

Purpose This study aims to investigate the corrosion inhibition effect of extracted oil from Ziziphus lotus fruit on corrosion of C38 carbon steel in 5.5 M H3PO4 solution using potentiodynamic polarization and impedance techniques. Design/methodology/approach Oil composition was determined using gas chromatography, and the results showed that oleic and palmitic acids present approximately 84.0 per cent of its total chemical content. Electrochemical impedance spectroscopy (EIS) data were analyzed by adapting it to a well-developed electric circuit model. The inhibition efficiency of Z. lotus oil was calculated and compared using Tafel polarization and EIS. Findings Accordingly, the oil extract was found to act as an anodic type inhibitor. Furthermore, inhibition efficiency of Z. lotus oil extract increase with oil concentrations and achieve approximately 70.5 per cent at 3 g/L solution of Z. lotus oil. Originality/value The results obtained from different tested methods were in line, and the oil was able to reduce significantly the kinetics of the corrosion process of C38 carbon steel.

Computational analysis of turbulent flow through an eccentric annulus under different temperature conditions

2018 ◽  
Vol 28 (9) ◽  
pp. 2189-2207 ◽  
Author(s):  
Erman Ulker ◽  
Sıla Ovgu Korkut ◽  
Mehmet Sorgun
Keyword(s):  
Turbulent Flow ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Content Type ◽  
Non Linear ◽  
Fully Developed Turbulent Flow ◽  
Effects Of Temperature ◽  
Eccentric Annuli ◽  
Pipe Rotation

Purpose The purpose of this paper is to solve Navier–Stokes equations including the effects of temperature and inner pipe rotation for fully developed turbulent flow in eccentric annuli by using finite difference scheme with fixing non-linear terms. Design/methodology/approach A mathematical model is proposed for fully developed turbulent flow including the effects of temperature and inner pipe rotation in eccentric annuli. Obtained equation is solved numerically via central difference approximation. In this process, the non-linear term is frozen. In so doing, the non-linear equation can be considered as a linear one. Findings The convergence analysis is studied before using the method to the proposed momentum equation. It reflects that the method approaches to the exact solution of the equation. The numerical solution of the mathematical model shows that pressure gradient can be predicted with a good accuracy when it is compared with experimental data collected from experiments conducted at Izmir Katip Celebi University Flow Loop. Originality/value The originality of this work is that Navier–Stokes equations including temperature and inner pipe rotation effects for fully developed turbulent flow in eccentric annuli are solved numerically by a finite difference method with frozen non-linear terms.

Exploration of activation energy and binary chemical reaction effects on nano Casson fluid flow with thermal and exponential space-based heat source

2019 ◽  
Vol 15 (1) ◽  
pp. 227-245 ◽  
Author(s):  
Gireesha B.J. ◽  
M. Archana ◽  
B. Mahanthesh ◽  
Prasannakumara B.C.
Keyword(s):  
Activation Energy ◽  
Heat Source ◽  
Chemical Reaction ◽  
Radiative Heat ◽  
Physical Parameters ◽  
Content Type ◽  
Heat Process ◽  
Flow Past ◽  
Non Linear ◽  
Exponential Space

PurposeThe purpose of this paper is to explore the effects of binary chemical reaction and activation energy on nano Casson liquid flow past a stretched plate with non-linear radiative heat, and also, the effect of a novel exponential space-dependent heat source (ESHS) aspect along with thermal-dependent heat source (THS) effect in the analysis of heat transfer in nanofluid. Comparative analysis is carried out between the flows with linear radiative heat process and non-linear radiative heat process.Design/methodology/approachA similarity transformation technique is utilised to access the ODEs from the governed PDEs. The manipulation of subsequent non-linear equations is carried out by a well-known numerical approach called Runge–Kutta–Fehlberg scheme. Obtained solutions are briefly discussed with the help of graphical and tabular illustrations.FindingsThe effects of various physical parameters on temperature, nanoparticles volume fraction and velocity fields within the boundary layer are discussed for two different flow situations, namely, flow with linear radiative heat and flow with non-linear radiative heat. It is found that an irregular heat source/sink (ESHS and THS) and non-linear solar radiation play a vital role in the enhancement of the temperature distributions.Originality/valueThe problem is relatively original to study the effects of activation energy and binary chemical reaction along with a novel exponential space-based heat source on laminar boundary flow past a stretched plate in the presence of non-linear Rosseland radiative heat.

Discrete differential operators for periodic and two-periodic time functions

2019 ◽  
Vol 38 (1) ◽  
pp. 325-347 ◽  
Author(s):  
Tadeusz Sobczyk ◽  
Michał Radzik ◽  
Natalia Radwan-Pragłowska
Keyword(s):  
Differential Operators ◽  
High Accuracy ◽  
Large Set ◽  
Periodic Functions ◽  
Content Type ◽  
Second Derivatives ◽  
Non Linear ◽  
Discrete Operators ◽  
Linear Differential ◽  
Very High

Purpose To identify the properties of novel discrete differential operators of the first- and the second-order for periodic and two-periodic time functions. Design/methodology/approach The development of relations between the values of first and second derivatives of periodic and two-periodic functions, as well as the values of the functions themselves for a set of time instants. Numerical tests of discrete operators for selected periodic and two-periodic functions. Findings Novel discrete differential operators for periodic and two-periodic time functions determining their first and the second derivatives at very high accuracy basing on relatively low number of points per highest harmonic. Research limitations/implications Reduce the complexity of creation difference equations for ordinary non-linear differential equations used to find periodic or two-periodic solutions, when they exist. Practical implications Application to steady-state analysis of non-linear dynamic systems for solutions predicted as periodic or two-periodic in time. Originality/value Identify novel discrete differential operators for periodic and two-periodic time functions engaging a large set of time instants that determine the first and second derivatives with very high accuracy.

Relational asymmetry, trust, and innovation in supply chain management: a non-linear approach

2019 ◽  
Vol 30 (1) ◽  
pp. 303-328 ◽  
Author(s):  
Marek Michalski ◽  
Jose Luis Montes ◽  
Ram Narasimhan
Keyword(s):  
Supply Chain ◽  
Supply Chain Management ◽  
Institutional Environment ◽  
Least Squares Method ◽  
Cross Sectional ◽  
Chain Management ◽  
Content Type ◽  
Relationship Analysis ◽  
Novel Approach ◽  
Non Linear

PurposeThe purpose of this paper is to examine the non-linear aspects of the asymmetry-performance relationship under varying conditions of trust and innovation. Its novel approach is useful for addressing the strategic elements of supply chain management (SCM) relationships based on trust and innovation decisions.Design/methodology/approachResults are based on a study of 90 managers from small- and medium-sized firms in Spain. Instead of a classical linear relationship analysis, the authors performed a non-linear analysis, using polynomial modeling and Warp 3 partial least squares method, which provides a more nuanced view of the data and constitutes an original approach to empirical research in SCM.FindingsThis study adds a new viewpoint on SC relationships by suggesting that not all trust and innovation development leads directly to performance improvement. The principal finding is, in varying trust and innovation contexts, that the influences of asymmetry on performance have uneven characteristics and follow non-linear paths.Research limitations/implicationsThis study focuses on only one particular institutional environment in one country. The data are also cross-sectional, which makes it difficult to empirically test causality.Practical implicationsThe findings provide rational insights to managers on when it is appropriate to reduce (or not) asymmetric relationships with partners.Originality/valueTrust and innovation are important and ones of the key requirements of supply chain relationships in any environment, this study argues that the interactions of key SCM elements that drive members to better performance are more complex and non-linear.

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