Somnath Santra, Shubhadeep Mandal and Suman Chakraborty
The purpose of this study is to perform a detailed review on the numerical modeling of multiphase and multicomponent flows in microfluidic system using phase-field method. The…
Abstract
Purpose
The purpose of this study is to perform a detailed review on the numerical modeling of multiphase and multicomponent flows in microfluidic system using phase-field method. The phase-field method is of emerging importance in numerical computation of transport phenomena involving multiple phases and/or components. This method is not only used to model interfacial phenomena typical to multiphase flows encountered in engineering and nature but also turns out to be a promising tool in modeling the dynamics of complex fluid-fluid interfaces encountered in physiological systems such as dynamics of vesicles and red blood cells). Intrinsically, a priori unknown topological evolution of interfaces offers to be the most concerning challenge toward accurate modeling of moving boundary problems. However, the numerical difficulties can be tackled simultaneously with numerical convenience and thermodynamic rigor in the paradigm of the phase field method.
Design/methodology/approach
The phase-field method replaces the macroscopically sharp interfaces separating the fluids by a diffuse transition layer where the interfacial forces are smoothly distributed. As against the moving mesh methods (Lagrangian) for the explicit tracking of interfaces, the phase-field method implicitly captures the same through the evolution of a phase-field function (Eulerian). In contrast to the deployment of an artificially smoothing function for the interface as used in the volume of a fluid or level set method, however, the phase-field method uses mixing free energy for describing the interface. This needs the consideration of an additional equation for an order parameter. The dynamic evolution of the system (equation for order parameter) can be described by Allen–Cahn or Cahn–Hilliard formulation, which couples with the Navier–Stokes equation with the aid of a forcing function that depends on the chemical potential and the gradient of the order parameter.
Findings
In this review, first, the authors discuss the broad motivation and the fundamental theoretical foundation associated with phase-field modeling from the perspective of computational microfluidics. They subsequently pinpoint the outstanding numerical challenges, including estimations of the model-free parameters. They outline some numerical examples, including electrohydrodynamic flows, to demonstrate the efficacy of the method. Finally, they pinpoint various emerging issues and futuristic perspectives connecting the phase-field method and computational microfluidics.
Originality/value
This paper gives unique perspectives to future directions of research on this topic.
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Subhendu Bikash Santra, Subodh Kumar Mohanty and Tanmoy Roy Choudhury
This study aims to propose a new connection technique of bypass diode (BD) in photovoltaic (PV) array, which reduces the circulating current (CC) within PV modules as well as…
Abstract
Purpose
This study aims to propose a new connection technique of bypass diode (BD) in photovoltaic (PV) array, which reduces the circulating current (CC) within PV modules as well as conduction loss in partial shaded condition (PSC).
Design/methodology/approach
Linearized circuit model of PV panel is proposed for calculating the CC and power loss of novel BD arrangements in PV array. From the analysis the best BD arrangement is applied in series parallel, TCT and honeycomb (HC) PV array structure for simulation and hardware verification. The hardware verification is performed in a 3 × 3 PV array, where individual panel capacity is 200 W.
Findings
The proposed BD arrangement reduces the power loss due to CC under PSC by almost 3% compared to conventional BD structure in a PV array.
Originality/value
The proposed BD arrangement is simple and useful in large PV power plants to reduce the CC-based extra power loss under PSC.
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J. Jayaprakash, Vediyappan Govindan, S.S. Santra, S.S. Askar, Abdelaziz Foul, Susmay Nandi and Syed Modassir Hussain
Scientists have been conducting trials to find ways to reduce fuel consumption and enhance heat transfer rates to make heating systems more efficient and cheaper. Adding solid…
Abstract
Purpose
Scientists have been conducting trials to find ways to reduce fuel consumption and enhance heat transfer rates to make heating systems more efficient and cheaper. Adding solid nanoparticles to conventional liquids may greatly improve their thermal conductivity, according to the available evidence. This study aims to examine the influence of external magnetic flux on the flow of a mixed convective Maxwell hybrid non-Newtonian nanofluid over a linearly extending porous flat plate. The investigation considers the effects of thermal radiation, Dufour and Soret.
Design/methodology/approach
The mathematical model is formulated based on the fundamental assumptions of mass, energy and momentum conservation. The implicit models are epitomized by a set of interconnected nonlinear partial differential equations, which include a suitable and comparable adjustment. The numerical solution to these equations is assessed for approximate convergence by the Runge−Kutta−Fehlberg method based on the shooting technique embedded with the MATLAB software.
Findings
The findings are presented through graphical representations, offering a visual exploration of the effects of various dynamic parameters on the flow field. These parameters encompass a wide range of factors, including radiation, thermal and Brownian diffusion parameters, Eckert, Lewis and Soret numbers, magnetic parameters, Maxwell fluid parameters, Darcy numbers, thermal and solutal buoyancy factors, Dufour and Prandtl numbers. Notably, the authors observed that nanoparticles with a spherical shape exerted a significant influence on the stream function, highlighting the importance of nanoparticle geometry in fluid dynamics. Furthermore, the analysis revealed that temperature profiles of nanomaterials were notably affected by their shape factor, while concentration profiles exhibited an opposite trend, providing valuable insights into the behavior of nanofluids in porous media.
Originality/value
A distinctive aspect of the research lies in its novel exploration of the impact of external magnetic flux on the flow of a mixed convective Maxwell hybrid non-Newtonian nanofluid over a linearly extending porous flat plate. By considering variables such as solar radiation, external magnetic flux, thermal and Brownian diffusion parameters and nanoparticle shape factor, the authors ventured into uncharted territory within the realm of fluid dynamics. These variables, despite their significant relevance, have not been extensively studied in previous research, thus underscoring the originality and value of the authors’ contribution to the field.
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Amita Majumder, Ranjan Ray and Sattwik Santra
The purpose of this study is to examine the sensitivity of regional and world poverty rates to the purchasing power parities (PPP) used in the calculations. The PPPs are required…
Abstract
Purpose
The purpose of this study is to examine the sensitivity of regional and world poverty rates to the purchasing power parities (PPP) used in the calculations. The PPPs are required to convert the “international poverty line” typically denominated in US dollar to its local currency equivalent in the various countries. While recent studies on world poverty differ with respect to the specification of the international poverty line (IPL), they universally use the PPP available from the international comparison program (ICP). This study provides a departure and calculates PPPs using the Gini–Elteto–Koves–Szulc (GEKS) price index and country product dummy (CPD) model as alternatives to the ICP PPPs. The GEKS and CPD PPPs are compared with the ICP PPPs. The paper then compares the global and regional poverty rates based on the three sets of PPPs and presents evidence of significant revision to the poverty rates if we depart from the use of the ICP PPPs. The study tests for the presence of serial correlation between price movements in different countries and investigates its impact on the PPPs. The methodological contribution of this paper is to establish the close nexus between price indices and poverty rates via the PPPs used in obtaining the local currency unit (LCU) denominated IPL.
Design/methodology/approach
The PPP calculations in this paper relate to the ICP round, 2011. Along with the ICP PPPs from published reports (with India as the numeraire country), we report the following indices, namely, the GEKS, weighted CPD and its two spatially correlated generalisations. The ICP PPPs are used as benchmark. The ICP group in the World Bank made the price and expenditure information for 2011 available. Corresponding poverty rates are calculated at the country, regional and global levels.
Findings
The empirical evidence points to the fact that while at the country level the alternative calculations have high impact on the implied poverty rates, at the regional and global level the rates are reasonably quite robust.
Research limitations/implications
Three points are worth noting, namely, as opposed to the PPP for “Individual consumption expenditure by households” (ICEH), which is the PPP used for international poverty monitoring by the World Bank and others, we have used the ICP PPPs for “Actual individual consumption” (AIC); although ICP uses the GEKS procedure above the BH level, we independently calculated these PPPs using the price information provided, and the base country has been moved from the USA to India.
Practical implications
One can come up with independently estimated PPPs that do not require the elaborate and expensive procedure set up by the ICP and can arrive at robust poverty rates at the regional and global level.
Social implications
The change in base has been made as India shares many of the features of a developing country including high poverty rates, but at the same time provides a market and an economy size that places it in the top tier of nations. In addition, poverty comparisons amongst developing countries can be made using these PPPs directly, without reference to the USA. The poverty calculations are based on the PovcalNet program.
Originality/value
There is no clear answer to the question “how robust are the global poverty numbers to departures from the ICP PPPs?” in the literature nor is there any evidence on the robustness of the ICP PPPs themselves to changes in the ICP methodology. Given that the ICP uses the Gini–Elteto–Koves–Szulc (GEKS) multilateral price index in aggregation of ICP PPP basic heading data, in an attempt to partially answer this question this study examines the sensitivity of measures of relative prices (and poverty) to using CPD (and various spatial versions) and GEKS methods, using price data provided by the World Bank. It also verifies how these PPPs track the published 2011 ICP PPPs, which are used as benchmark.
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V. V. Singh, Abubakkar Idris Mohhammad, Kabiru Hamisu Ibrahim and Ibrahim Yusuf
This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The…
Abstract
Purpose
This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The computed results are more supportable for repairable system performability analysis.
Design/methodology/approach
In this paper, the authors have analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The supplementary variable technique has employed for analyzing the performance of the system.
Findings
Reliability measures have been computed for different types of configuration. It generalized the results for purely series and purely parallel configurations.
Research limitations/implications
This research may be beneficial for industrial system performances whereas a k-out-of-n-type configuration exists.
Practical implications
Not sure as it is a theoretical assessment.
Social implications
This research may not have social implications.
Originality/value
This work is the sole work of authors that have not been communicated to any other journal before.
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Sustainable energy like renewable energy plays a critical role in achieving sustainable development goals including energy security in emerging economics. BRICS (Brazil, Russia…
Abstract
Sustainable energy like renewable energy plays a critical role in achieving sustainable development goals including energy security in emerging economics. BRICS (Brazil, Russia, India, China and South Africa) constitutes about 23% of the world’s GDP, 40% of the world’s population and 36% share of the supply of primary energy in the world. Obviously the Bloc has tremendous potential in influencing the global sustainable clean energy transition with the advantages like lowering the costs of renewable, boosting employment in the sector of green energy, enhancement of energy security and improvement of local air quality. Despite the existence of varieties of renewable energy resources in the BRICS economies, renewable energy resources are found underdeveloped. The major objectives of this chapter are to assess progress of different forms of energy especially renewable energy, impact of development of renewable energy on carbon emission and policy issues in renewable energy development in the context of sustainable energy development of BRICS countries.
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Amita Majumder, Ranjan Ray and Sattwik Santra
This paper aims to illustrate the usefulness of the proposed procedure to evaluate the Goods and Services Tax (GST) in India by applying it to provide evidence on optimal…
Abstract
Purpose
This paper aims to illustrate the usefulness of the proposed procedure to evaluate the Goods and Services Tax (GST) in India by applying it to provide evidence on optimal commodity tax rates.
Design/methodology/approach
In the optimal commodity tax literature, the commonly used Ramsey–Samuelson–Diamond–Mirrlees framework assumes invariance of budget allocation between pre- and posttax regimes and uses only the first-order conditions in the two-stage optimization procedure. This paper proposes an iterative method that overcomes the above limitations in obtaining the optimal tax rates.
Findings
It is found that the optimal commodity taxes are highly sensitive to the procedure used to estimate them. The resulting tax rates turn out to be close to the GST tax slabs. The results also show that on both absolute and relative measures, for all the selected states considered here and for All-India, the optimal tax systems are progressive for two chosen values of the inequality aversion parameter.
Originality/value
There is a very limited literature on the computational methodology to calculate optimal commodity taxes, and consequently, the evidence is quite scarce as well. In combining contributions to the computation of optimal taxes with empirical evidence, this paper fills a significant gap in the literature. The context of India gives it added value since the GST has recently been introduced in India, and to the best of the authors’ knowledge, this is one of the first attempts at evaluating the Indian GST through the spectacles of optimal taxes.
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Félix Orlando Martínez-Ríos, José Antonio Marmolejo-Saucedo and Gonzalo Abascal-Olascoaga
This chapter proposes a protocol based on blockchain technology applied to corporate social responsibility (CSR). The first part discusses the characteristics associated with CSR…
Abstract
This chapter proposes a protocol based on blockchain technology applied to corporate social responsibility (CSR). The first part discusses the characteristics associated with CSR actions and the main difficulties its development faces, such as transparency, security, fault tolerance, among others. Subsequently, the authors describe the characteristics and concepts related to blockchain-based developments to later describe our framework for the control and development of CSR actions based on blockchain. Herein, the authors also describe how to publicly and privately identify the participating elements of CSR and the operations and resources necessary for the implementation and operation of the proposed protocol.
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Aatef Hobiny and Ibrahim Abbas
The purpose of this paper is to study the wave propagation in a non-homogenous semiconducting medium through the photothermal process using the fractional order…
Abstract
Purpose
The purpose of this paper is to study the wave propagation in a non-homogenous semiconducting medium through the photothermal process using the fractional order photo-thermoelastic without neglecting the coupling between the plasma and thermoelastic waves that photogenerated through traction free and loaded thermally by exponentially decaying pulse boundary heat flux.
Design/methodology/approach
The analytical solutions in the transformed domain by the eigenvalue approach were observed through the transform techniques of Laplace.
Findings
Silicon-like semiconductor was used to achieve the numerical computations.
Originality/value
Some comparisons are shown in the figures to estimate the effects of the fractional order and non-homogeneous parameters.