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Lignite-derived nanocarbon as surface passivator and cosensitizer in dye-sensitized solar cell
Interfacial exciton recombination and narrow absorption region are two bottlenecks that limit the performance of a dye-sensitized solar cell (DSSC). The present study focuses on improving the solar cell's efficiency by utilizing a lignite-derived nanocarbon that behaves as a surface passivator and cosensitizer. Incorporating nanocarbon enhanced the spectral absorption region of the N719 dye with a bathochromic shift and played the role of a cosensitizer. In addition, the quenched photoluminescence spectra revealed that nanocarbon also aids in the swift transfer of electrons to the conduction band of TiO2 by reducing the exciton recombination and acting as a surface passivator. On measuring the fabricated DSSC under AM 1.5G irradiation with the intensity of 100 mW/cm2, the nanocarbon-based device exhibited an efficiency (?) of 9.02% with a photocurrent density of 20.45 mA/cm2, outperforming the pristine device (? = 6.21%). An enhancement of 45% in the power conversion efficiency was achieved. Thus, the results unveiled that nanocarbons derived from pollution-causing fuel synergistically aided in enhancing the performance of DSSC. 2024 Elsevier Ltd -
Lignocellulosic biomass for biochar production: A green initiative on biowaste conversion for pharmaceutical and other emerging pollutant removal
Lignocellulosic waste generation and their improper disposal has accelerated the problems associated with increased greenhouse gas emissions and associated environmental pollution. Constructive ways to manage and mitigate the pollution associated with lignocellulosic waste has propelled the research on biochar production using lignocellulose-based substrates. The sustainability of various biochar production technologies in employing lignocellulosic biomass as feedstock for biochar production not only aids in the lignocellulosic biomass valorization but also helps in carbon neutralization and carbon utilization. Functionalization of biochar through various physicochemical methods helps in improving their functional properties majorly by reducing the size of the biochar particles to nanoscale and modifying their surface properties. The usage of engineered biochar as nano adsorbents for environmental applications like dye absorption, removal of organic pollutants and endocrine disrupting compounds from wastewater has been the thrust areas of research in the past few decades. This review presents a comprehensive outlook on the up-to-date research findings related to the production and engineering of biochar from lignocellulosic biomass and their applications in environmental remediation especially with respect to wastewater treatment. Further a detailed discussion on various biochar activation methods and the future scope of biochar research is presented in this review work. 2024 Elsevier Ltd -
Lilliputians' dilemma: Survival strategies of small states in South Asia
One of the most striking features of contemporary international politics is asymmetrical power relations among states. With the birth of the United Nations, the sovereign equality of the states began to be fully respected, at least in principle. During the Cold War, small states gained much importance when superpowers tried to co-opt them. Small states situated in specific geo-strategic areas were seen as 'assets' or 'trouble spots' depending on their ideological leaning. 1 Given the fact that small states constitute majority in terms of numbers in global politics, but at the same time facing numerous politico-security and economic issues, several interesting questions arise. Do small states feel secured in regional and international politics dominated by big and middle powers? What survival strategies do they adopt to secure themselves? How does this translate to South Asian region that is commonly viewed as 'India-dominant'? Do small states of South Asia follow similar or differing strategies to safeguard their security? South Asia offers a right case to look at the issue of survival strategies of small states in regional politics from both theoretical and empirical contexts. 2024 selection and editorial matter, Adluri Subramanyam Raju and R. Srinivasan. All rights reserved. -
Limaco?n Inspired Particle Swarm Optimization forLarge-Scale Optimization Problem
Large-scale optimization problems are a complex problem in the class of NP-Hard. These problems are not solvable by traditional methods in a reasonable time. Single machine total weighted tardiness scheduling problem (SMTWTSP) is a complex problem in this category. It has a set of different events with varying criteria that need to be scheduled on one machine. The main aim of this problem is to find the minimum possible total weighted tardiness. Particle swarm optimization (PSO) algorithm has performed admirably in the field of optimization. To solve complex optimization problems, several new variants of this algorithm are being developed since its inception. This work proposed an influential local search (LS) technique inspired by limaco?n curve. The new local search is hybridized with PSO and named Limaco?n inspired PSO (LimPSO) algorithm. The efficiency and accuracy of the designed LimPSO strategy are tested over the large-scale SMTWTS problem, which shows that LimPSO can be considered an effective method for solving the combinatorial optimization problems. 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. -
Limelight in Dark Times: Jyoti Kumari's 'Cyclothon'
[No abstract available] -
Line completion number of grid graph Pn Pm
The concept of super line graph was introduced in the year 1995 by Bagga, Beineke and Varma. Given a graph with at least r edges, the super line graph of index r, Lr(G), has as its vertices the sets of r-edges of G, with two adjacent if there is an edge in one set adjacent to an edge in the other set. The line completion number lc(G) of a graph G is the least positive integer r for which Lr(G) is a complete graph. In this paper, we find the line completion number of grid graph Pn Pm for various cases of n and m. 2021 Azarbaijan Shahid Madani University. -
Linear and Global Stability Analyses on the Influences of Thermal Non-Equilibrium and Non-uniform Gravity Field on DarcyBrinkmanBard Convection
Global and linear stability analyses of DarcyBrinkmanBard convection in a liquid-saturated porous medium with a non-uniform gravity field using the local thermal non-equilibrium (LTNE) model are investigated. Linear and quadratic (parabolic) gravity field profiles are considered in the analysis. The OberbeckBoussinesq approximation is assumed to be a valid and the stationary mode of onset of convection is shown to be the preferred mode due to the validity of the principle of exchange of stabilities. Critical values of wavenumber and thermal Rayleigh number are obtained numerically using the higher-order Galerkin technique. The effect of an increase in the gravity fields strength is to delay the onset of convection, and to a growth in convective cell size. Further, linear convective profile is found to postpone convection compared to the quadratic one. Global stability ensures the existence of subcritical motions in the case of a non-uniform gravity field. In contrast, subcritical motions do not exist in constant gravity in LTE and LTNE situations. A non-uniform gravity field has a significant influence on the convective instability in a liquid-saturated high-porosity medium, lesser influence in the case of a low porosity medium and least in the case of a clear fluid layer. 2021, The Author(s), under exclusive licence to Springer Nature India Private Limited. -
Linear and non-linear analyses of double diffusive chandrasekhar convection with heat and concentration source in micropolar fluid with saturated porous media under gravity modulation
In this paper, linear and non-linear analysis of Double-Diffusive convection in the presence of magnetic field and gravity modulation with heat and concentration source in a micropolar fluid is studied by assuming the strength of heat and concentration source same. The expression for Rayleigh number and correction Rayleigh number are obtained using regular perturbation method. The effects of parameters on heat and mass transport is investigated using non-linear analysis by deriving eighth order Lorenz equation. It is found that coupling parameter and Chandrasekhar number stabilizes the system. Whereas internal Rayleigh number and Darcy number destabilizes the system. 2020 International Association of Engineers. -
Linear and non-linear analyses of double-diffusive-Chandrasekhar convection coupled with cross-diffusion in micropolar fluid over saturated porous medium
Purpose: The problem aims to find the effects of coupled cross-diffusion in micropolar fluid oversaturated porous medium, subjected to Double-Diffusive Chandrasekhar convection. Design/methodology/approach: Normal mode and perturbation technique have been employed to determine the critical Rayleigh number. Non-linear analysis is carried out by deriving the Lorenz equations using truncated Fourier series representation. Heat and Mass transport are quantified by Nusselt and Sherwood numbers, respectively. Findings: Analysis related to the effects of various parameters is plotted, and the results for the same are interpreted. It is observed from the results that the Dufour parameter and Soret parameter have an opposite influence on the system of cross-diffusion. Originality/value: The effect of the magnetic field on the onset of double-diffusive convection in a porous medium coupled with cross-diffusion in a micropolar fluid is studied for the first time. 2020, Emerald Publishing Limited. -
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). -
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 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 and weakly nonlinear stability analyses of Darcy Bard convection with feedback control
In this paper, the effect of feedback control on the criterion for the onset of DarcyBard convection in a horizontal Boussinesq Newtonian fluid is studied theoretically. The bounding isothermal lower and upper surfaces are considered to be rigid. The single term Galerkin method and the Maclaurin series expansion are combined with the Newton-Raphson method of three variables to perform a linear stability analysis in order to determine eigen value. To make a weakly nonlinear stability analysis of the system, a Vadasz Lorenz model is constructed. The models various properties are discovered to be identical to those of the standard Lorenz model. The exhibits both dissipative and conservative characteristics and the bounded nature of its solution is demonstrated by the trapping region, which takes the form of an ellipsoid. The Hopf-Rayleigh number determined from the autonomous dynamical system predicts the onset of chaos. The influence of the controller gain parameter and the Biot number on the onset of convection has been analyzed. Results from the study reveal that the controller gain parameter stabilizes the system and further delays the onset of chaos. Overall, the study establishes that an increase in the Biot number promotes long-term periodic motion over chaotic behavior, while an increase in the controller gain parameter enlarges the trapping region, thereby contributing to improved system stability. The Author(s) 2025. -
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.