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Linear and non-linear analyses of electrothermo convection in a micropolar fluid
The linear and weakly non-linear stability analyses of electrothermo convention in a micropolar fluid layer heated from below are studied. The linear and non-linear analyses are, respectively, based on normal mode technique and truncated representation of Fourier series. The influence of various parameters on the onset of convection has been analyzed in the linear case. The resulting autonomous Lorenz model obtained in non-linear analysis is solved numerically to quantify the heat transfer through Nusselt number. It is observed that the increase in concentration of suspended particles stabilizes the system and decreases the heat transfer and increase in electric Rayleigh number destabilizes the system and increases the heat transfer. 2017 Pushpa Publishing House, Allahabad, India. -
Linear and non-linear analysis of solute-magneto convection in a couple stress fluid with porous medium under concentration modulation
The effect of concentration modulation and magnetic field in a couple stress fluid with porous medium and salted from above is studied using linear and non-linear analysis. Venezian approach based on perturbation method is used to obtain the expression for solute Rayleigh number and correction solute Rayleigh number. The expression for correction solute Rayleigh number is obtained as a function of couple stress parameter, Chandrashekar number, Darcy number and Schmidt number. The effect of parameters on symmetric and asymmetric concentration modulation are discussed in the paper. A non-autonomous Ginzburg-Landau equation with time periodic co-efficient is obtained to study the effect of parameters on mass transfer. It is found that onset of convection and mass transfer can be delayed or advanced by varying the parameters of the problem. Asymmetric modulation is found to be more stable than the symmetric modulation. 2019 Author(s). -
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Linear and non-linear magneto-convection in couple stress fluid with non-classical heat conduction law
A theoretical examination of the thermal convection for a couple stress fluid which is electrically conductive and possessing significant thermal relaxation time with an externally applied magnetic field is carried out. Fourier's law fails when fluids are subjected to rapid heating or when it is confined and in the case of nano-devices. A frame invariant constitutive equation for heat flux is considered. The linear analysis is carried out implementing a normal mode solution and the non-linear stability of the system is analyzed using a double Fourier series. The analysis of the transfer of heat is determined in terms of the Nusselt number. Published under licence by IOP Publishing Ltd. -
Linear and non-linear stability analyses of Rayleigh-Bard convection in watercopper and wateralloy nanoliquids
In this paper, we perform linear and non-linear stability analyses of Rayleigh-Bard convection in a horizontal layer of watercopper and wateralloy nanoliquids. The corresponding eigen values for the problems involving the two nanoliquids are obtained and compared. The thermophysical properties of nanoliquids have been modelled as a function of the properties of water as base liquid, copper and alloy as nanoparticles. A non-linear analysis is performed using the energy method. The subcritical instability does not exist. As a limiting case the results of water are discussed with results of previous investigations, and a good agreement is found. The effect of nanoparticles is to destabilise the system. The results are depicted graphically. 2022 Informa UK Limited, trading as Taylor & Francis Group. -
Linear and nonlinear convection in dielectric fluids
The thesis is concerned with linear and nonlinear Rayleigh-Benard electroconvection in a horizontal porous layer. Modified Darcy law is employed to describe the fluid motion. The effect of non-0classical heat conduction, chemical reaction, thermal radiation and finite amplitudes on the onset of Darcy electroconvection is considered. The findings of the problems investigated in the thesis may prove useful in heat transfer application situations with dielectric fluids as working medium. -
Linear and Nonlinear Convection In Dielectric Fluids
The thesis is concerned with linear and nonlinear Rayleigh-Bard electroconvection in a horizontal porous layer. Modified Darcy law is employed to describe the fluid motion. The effect of non-classical heat conduction, chemical reaction, thermal radiation and finite amplitudes on the onset of Darcy electroconvection is considered. The findings of the problems investigated in the thesis may prove useful in heat transfer application situations with dielectric fluids as working medium. The summary of the problems addressed in the thesis is given below.Effect of non-classical heat conduction on Rayleigh-Bard newlineconvection in a horizontal layer of porous medium saturated with a dielectric fluid The method of small perturbations is used to examine the effect of non-classical heat conduction on the onset of Darcy electroconvection. Exact solutions for both stationary and oscillatory instability are obtained and known results have been deduced as limiting cases of the present study. It is shown that electroconvective instability in a Darcy porous layer is hastened by increasing the strengths of second sound and electric newlineforces and that the presence of second sound and dielectrophoretic force leads to shorter wavelength electroconvection. Further, it is found that the effect of Vadasz number is to advance the onset of oscillatory Darcy newlineelectroconvection and oscillatory instability sets in before stationary convection provided that the Vadasz number and the Cattaneo number are sufficiently large. Rayleigh-Bard convection in a horizontal layer of porous medium saturated with a chemically reacting dielectric fluid The problem of the effect of chemical reaction on the onset of Darcy electroconvection in a horizontal porous layer heated from below is newlineinvestigated. It is assumed that the fluid experiences a zero-order exothermic chemical reaction and that there exists a local thermal equilibrium between the fluid and the solid phases. -
Linear and Nonlinear Convection in Magnetic Fluids
The thesis deals with linear and nonlinear Rayleigh-Bard ferroconvection in a horizontal porous layer. Modified Darcy law is used to describe the fluid motion. The effect of chemical reaction, temperature newlinemodulation, gravity modulation and finite amplitudes on the onset of Darcy ferrroconvection is considered. The findings of the problems addressed in the thesis may come in handy for heat transfer application newlinesituations with ferromagnetic fluids as working medium. The summary of the problems investigated in the thesis is given below.Effect of chemical reaction on the onset of ferroconvection in a porous medium The problem of the effect of chemical reaction on the onset of Darcy newlineferrroconvection in a horizontal porous layer heated from below is investigated by means of the classical linear stability analysis. It is assumed that the fluid undergoes a zero-order exothermic chemical reaction and that there exists a local thermal equilibrium between the fluid and the solid phases. It is proved that stationary convection is preferred to the oscillatory mode. The Galerkin method is employed to determine the eigenvalues.The effect of Frank-Kamenetskii number and magnetic parameters on the stability of the system is discussed. It is newlinefound that the basic temperature profile turns out to be more and more nonlinear and asymmetric as the Frank-Kamenetskii number increases and that the effect of both chemical reaction and magnetic forces is to newlinehasten the onset of Darcy ferrroconvection. Further, it is shown that when there is very strong nonlinearity of magnetization, the fluid layer is destabilized slightly. Effect of temperature modulation on the onset of ferroconvection in a porous medium The effect of temperature modulation on the onset of Darcy ferroconvection in a horizontal porous layer heated from below is considered. The analysis is based on the assumption that the amplitude of the temperature modulation is small enough compared with the imposed newlinesteady temperature difference. -
Linear and nonlinear convection in magnetic fluids /
The thesis deals with linear and nonlinear Rayleigh-Benard ferroconvection in a horizontal porous layer. Modified Darcy law is used to describe the fluid motion. The effect of chemical reaction, temperature modulation, gravity modulation and finite amplitudes on the onset of Darcy ferroconvection is considerd. The findings of the problems addressed in the thesis may come in handy for heat transfer application situations with ferromagnetic fluids as working medium. -
Linear and nonlinear triple diffusive convection in the presence of sinusoidal/non-sinusoidal gravity modulation: A comparative study
The non-uniform vertical vibrations (gravity modulation) or g-jitter or time-periodic body force, can be realized by oscillating the system vertically. The time periodic variations are considered to vary sinusoidally (trigonometric cosine) or non-sinusoidally (square, sawthooth and triangular) to study three-component convection in a Newtonian fluid using linear and non-linear analyses. In the linear theory, the expressions for the Rayleigh number and the correction Rayleigh number are obtained by using a regular perturbation method. The eigen value is obtained by adopting the classical Venezian approach. The generalized Lorenz model is derived using a Fourier series with additional modes and under the assumption of the Boussinesq approximation and small-scale convection motion. The resulting non-autonomous Lorenz model is solved numerically to quantify the heat and mass transports. The results are considered against the background of the results of no modulation. Study reveals that all the four types of gravity modulation delay the onset of convection and thereby lead to the diminished heat transfer situation. It is also found that in the case of trigonometric type of gravity modulation heat and mass transports are between those of the cases of triangular and square types. The results in respect of saw-tooth and triangular wave modulations are identical. 2021 Elsevier Ltd -
Linear and weakly non-linear analysis of gravity modulation and electric field on the onset of Rayleigh- Benard convection in a micropolar fluid /
Journal of Advances in Mathematics, Vol.9, Issue 3, pp.363-388, ISSN No: 2347-1921. -
Linear and weakly non-linear stability analyses of Rayleigh-Bard convection in a water-saturated porous medium with different shapes of copper nanoparticles
The Rayleigh-Bard convection of a nanoliquid-saturated porous medium confined in a very shallow enclosure is investigated theoretically using the modified Buongiorno - Brinkman model. In the study, the chosen nanoliquid-saturated porous medium is assumed to be made up of water well dispersed with copper(Cu) nanoparticles of five different shapes saturating in a 30% reinforced polycarbonate glass fiber(GF) porous material of high porosity and its effective thermophysical properties are calculated using the phenomenological laws or mixture theory. Two kinds of boundary conditions, viz., stress-free and rigid, are employed and the analytical solution is obtained in both cases. On the other hand, Rayleigh-Bard convection in a very shallow domain of height 5mm and width 5cm filled with water-liquid and bounded by the rigid boundaries is simulated. The simulation results are then compared with the analytical results in the case of rigid boundaries. We found that the analytical results are in good agreement with those of the simulation results and this validates results of the present study. Linear and weakly non-linear stability analyses are performed to find the onset and the heat transport of the system. The effects of various parameters on the onset and heat transport of the system are depicted graphically and the physical explanation is provided for all observed results in the study. We found that the addition of dilute concentration of nanoparticles advances the onset and thereby enhances the heat transport in the system. Among five different shapes of copper nanoparticles, maximum and minimum heat transports are observed in the cases of blade and spherical shaped nanoparticles, respectively. The porous medium parameters: Brinkman number and porous parameter, show a stabilizing effect in the system. The existence of subcritical motions is also predicted for the system. The results of the Khanafer-Vafai-Lightstone(KVL) single-phase model, nanoliquid, base liquid and base liquid-saturated porous medium are obtained as limiting cases of the present study. Since nanoparticles and porous medium, respectively, show a destabilizing and stabilizing nature of influence in the system, the present work has possible applications in both heat removal and heat retainment systems. 2022, The Author(s), under exclusive licence to SocietItaliana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature. -
Linear Regression Tree and Homogenized Attention Recurrent Neural Network for Online Training Classification
Internet has become a vital part in people's life with the swift development of Information Technology (IT). Predominantly the customers share their opinions concerning numerous entities like, products, services on numerous platforms. These platforms comprises of valuable information concerning different types of domains ranging from commercial to political and social applications. Analysis of this immeasurable amount of data is both laborious and cumbersome to manipulate manually. In this work, a method called, Linear Regression Tree-based Homogenized Attention Recurrent Neural Network (LRT-HRNN) for online training is proposed. In the first step, a dataset consisting of student's reactions on E-learning is provided as input. A Linear Regression Decision Tree (LRT) - based feature (i.e., student's reactions and posts) selection model is applied in the second step. The feature selection model initially selects the commonly dispensed features. In the last step, HRNN sentiment analysis is employed for aggregating characterizations from prior and succeeding posts based on student's reactions for online training. During the experimentation process, LRT-HRNN method when compared with existing methods such as Attention Emotion-enhanced Convolutional Long Short Term Memory (AEC-LSTM) and Adaptive Particle Swarm Optimization based Long Short Term Memory (APSO-LSTM, performed better in terms of accuracy(increased by 6%), false positive rate (decreased by 22%), true positive rate (increased by 7%) and computational time (reduced by 21%). 2022 IEEE. -
Link stability - based optimal routing path for efficient data communication in MANET
The paper delves into the complexities of Mobile Ad hoc Networks (MANETs), which consist of a diverse array of wireless nodes. In such networks, routing packets poses a significant challenge due to their dynamic nature. Despite the variety of techniques available for optimizing routing in MANETs, persistent issues like packet loss, routing overhead, and End-to-End Delay (EED) remain prevalent. In response to these challenges, the paper proposes a novel approach for efficient Data Communication (DC) by introducing a Link Stability (LS)-based optimal routing path. This approach leverages several advanced techniques, including Pearson Correlation Coefficient SWIFFT (PCC-SWIFFT), Galois-based Digital Signature Algorithm (G-DSA), and Entropy-based Gannet Optimization Algorithm (E-GOA). The proposed methodology involves a systematic process. Initially, the nodes in the MANET are initialized to establish the network infrastructure. Subsequently, the Canberra-based K Means (C-K Means) algorithm is employed to identify Neighboring Nodes (NNs), which are pivotal for creating communication links within the network. To ensure secure communication, secret keys (SK) are generated for both the Sender Node (SN) and the Receiver Node (RN) using Galois Theory. Following this, PCC-SWIFFT methodologies are utilized to generate hash codes, serving as unique identifiers for data packets or routing information. Signatures are created and verified at the SN and RN using the G-DSA. Verified nodes are subsequently added to the routing entry table, facilitating the establishment of multiple paths within the network. The Optimal Path (OP) is selected using the E-GOA, considering factors such as link stability and network congestion. Finally, Data Communication (DC) is initiated, continuously monitoring LS to ensure optimal routing performance. Comparative analysis with existing methodologies demonstrates the superior performance of the proposed model. In summary, the proposed approach offers a comprehensive solution to enhance routing efficiency in MANETs by addressing critical issues and leveraging advanced algorithms for key generation, signature verification, and path optimization. 2024, Universitas Ahmad Dahlan. All rights reserved. -
Linkage Between Brand Value and Firm Performance: An Empirical Examination Using Fuzzy Set Qualitative Comparative Analysis
This study is designed with the data of Interbrand for ranking top 100 global brands. In this study, the linkage between brand values and financial performance was estimated using different performance measures that include both stock market and operating performance using Fuzzy Set Qualitative Comparative Analysis (fsQCA) technique. The study investigates the effect of brand value on profitability and shareholder. It is observed that the firms that have superior operating performance result in greater brand valuation. Performance of firms measured through profitability is found to be a significant factor in brand valuation. Brand valuation is also found to be significant determinant of profitability. Thus, higher brand quality improves the likelihood of repurchases and in turn improved cash flows. Firms with high agency conflicts tend to have lower brand value. Higher market valuation positively impacts brand valuation in the context of lower leverage and agency costs. The linkage of brand value to firm performance is the justification for marketers investments toward branding initiatives as a mechanism that creates value. This study is the first of its kind to examine the impact of agency costs on brand value using fsQCA technique to understand valuation impact of brands. To measure the effect of branding and marketing initiatives of the firms on financial performance, this study integrated both econometric and financial modeling. The Author(s) 2023. -
Linkage between enterpreneurial orientation and export performance of South Asian countries
Purpose: South Asian economies has witnessed export dependence over the past several years and the dependence has increased manifold. Export performance is the most preferred modes of internationalisation in developing economies as it is directly linked to getting access to international markets with limited resources and capabilities thereby contributing to the economic productivity of the country. This paper examines co-integration between the export performance and entrepreneurial orientation in South Asian nations explaining it as the main enabler of export. Entrepreneurial Orientation has been considered an important criterion for promoting export as EO requires innovation, proactiveness and risk taking which provides competitive advantage to enterprises. Design/Methodology/Approach: The research employed an econometric panel cointegration investigation to analyse the long run relationship of economic orientation and export performance among these nations. Findings: The research confirmed positive long run causality between the innovativeness, proactiveness and risk taking as three dimensions of entrepreneurial orientation and export concentration ratio as an indicator for export performance among South Asian nations. So, if these developing nations continue to diversify their product & market mix in exporting products and services the concentration ratio would improve that would result in growing further economic productivity. Practical implications: This research will serve as an aid to policy makers and entrepreneurs of South Asian nations to focus on the diverse mix of variety of products, services and markets to help South Asian nations prosper. Originality/Value: The policy makers and entrepreneurs of South Asian nations have accorded high priority to export performance. This research is one of the few studies that highlights access to EO as the basis for better export performance of South Asian nations. 2021, Allied Business Academies. All rights reserved. -
Linkages between Stock Market Development, Banks and Economic Growth in India: An ARDL Approach
The banking and stock market development was perceived to be an essential channel for economic growth through mobilisation and allocating productive investments. On the other hand, it was emphasised that economic growth would create demand for financial services and would lead to financial sector development. Existing literature attempts to investigate whether financial development is the primary driver of economic growth or vice versa. However, the issue remains unsolved and ambiguous. The present study investigated the causal relationship between stock markets, banks and economic growth in India using Autoregressive Distributed Lag (ARDL) bounds testing approach. The empirical result confirmed the long-run bidirectional relationship between financial development and economic growth in India. In the short-run, the empirical evidence showed that the market capitalisation of the Bombay Stock Exchange and IIP were unrelated and that a bidirectional relationship existed between the value of shares traded on the Bombay Stock Exchange and output. Furthermore, the findings supported unidirectional causality from the National Stock Exchange market capitalisation to output in the short-run. The value of shares traded on the National Stock Exchange and output had a feedback connection. 2022 The Society of Economics and Development, except certain content provided by third parties. -
Linking Metacognition, Workplace Cognitive Competencies and Performance: An Integrative Review-Based Conceptual Framework
A key driver of workplace cognitive competencies is metacognition which has been shown to impact performance among nurses, teachers and firefighters, however, it is scarcely studied among managerial employees. The research investigating this relationship is also scattered across multiple domains limiting its utility for researchers and practitioners. This paper, therefore, presents an integrative review of the existing empirical literature from the Web of Science and Scopus database to trace the linkages of metacognition, workplace cognitive competencies and performance at work. The identified linkages are then formulated into a conceptual framework clarifying how various workplace cognitive competencies and performance may be linked to metacognition. The findings indicate linkages between metacognition and various workplace cognitive competencies such as problem-solving, decision-making, innovation, creativity and knowledge acquisition. The present research also establishes the link of metacognition and cognitive competencies with learning, individual and firm performance. The review paves way for metacognition to be considered as a distinct construct in the workplace, identifies gaps and provides direction for future research. Copyright 2022 The Author(s). -
Linking non-financial motivators of women entrepreneurs with entrepreneurial satisfaction: A cluster analysis
Women entrepreneurs confronted with several obstacles while managing their business houses and dealt firmly developing successful ventures over time. The long term sustainability of their business reflects their entrepreneurial skills. The existence of certain forces empowered entrepreneurial drive of women entrepreneurs leading to their satisfaction and engagement in their ventures. The present investigation evaluated the antecedents of women's entrepreneurial satisfaction by examining 405 women entrepreneur participants using confirmatory factor analysis and cluster analysis techniques. This study comprises only micro and small businesses of women. The non-monetary determinants emerged out as the significant determinants of satisfaction of women entrepreneurs. The results revealed four clusters of women entrepreneurs based on motivational theory such as micro-achievers, entrepreneurial team, liberal and socialist feminism and optimism. The results also indicated that the clusters of women entrepreneurs' respond distinctively towards various dimensions of entrepreneurial satisfaction, i.e., quality of married life, overall venture satisfaction, achieved innovation, achieved freedom, team orientation, achieved recognition and identity and achieved employee trust. 2022 Inderscience Enterprises Ltd.