Browse Items (5511 total)
Sort by:
-
Straightforward synthesis of mn3o4/zno/eu2o3-based ternary heterostructure nano-photocatalyst and its application for the photodegradation of methyl orange and methylene blue dyes
Zinc oxide-ternary heterostructure Mn3O4/ZnO/Eu2O3 nanocomposites were successfully prepared via waste curd as fuel by a facile one-pot combustion procedure. The fabricated heterostructures were characterized utilizing XRD, UVVisible, FT-IR, FE-SEM, HRTEM and EDX analysis. The photocatalytic degradation efficacy of the synthesized ternary nanocomposite was evaluated utilizing model organic pollutants of methylene blue (MB) and methyl orange (MO) in water as examples of cationic dyes and anionic dyes, respectively, under natural solar irradiation. The effect of various experimental factors, viz. the effect of a light source, catalyst dosage, irradiation time, pH of dye solution and dye concentration on the photodegradation activity, was systematically studied. The ternary Mn3O4/ZnO/Eu2O3 photocatalyst exhibited excellent MB and MO degradation activity of 98% and 96%, respectively, at 150 min under natural sunlight irradiation. Experiments further conclude that the fabricated nanocomposite exhibits pH-dependent photocatalytic efficacy, and for best results, concentrations of dye and catalysts have to be maintained in a specific range. The prepared photocatalysts are exemplary and could be employed for wastewater handling and several ecological applications. 2021 by the authors. Licensee MDPI, Basel, Switzerland. -
Rapid Eye Movement (REM) Sleep Behavior Disorder and REM Sleep with Atonia in the Young
Background: Rapid eye movement (REM) sleep behavior disorder (RBD) and REM sleep without atonia (RWA) have assumed much clinical importance with long-term data showing progression into neurodegenerative conditions among older adults. However, much less is known about RBD and RWA in younger populations. This study aims at comparing clinical and polysomnographic (PSG) characteristics of young patients presenting with RBD, young patients with other neurological conditions, and normal age-matched subjects.Methods: A retrospective chart review was carried out for consecutive young patients (<25 years) presenting with clinical features of RBD; and data were compared to data from patients with epilepsy, attention deficit hyperactivity disorder (ADHD), and autism, as well as normal subjects who underwent PSG during a 2-year-period.Results: Twelve patients fulfilling RBD diagnostic criteria, 22 autism patients, 10 with ADHD, 30 with epilepsy, and 14 normal subjects were included. Eight patients with autism (30%), three with ADHD (30%), one with epilepsy (3.3%), and six patients who had presented with RBD like symptoms (50%) had abnormal movements and behaviors during REM sleep. Excessive transient muscle activity and/or sustained muscle activity during REM epochs was found in all patients who had presented with RBD, in 16/22 (72%) autistic patients, 6/10 (60%) ADHD patients compared to only 6/30 (20%) patients with epilepsy and in none of the normal subjects.Conclusion: We observed that a large percentage of young patients with autism and ADHD and some with epilepsy demonstrate loss of REM-associated atonia and some RBD-like behaviors on polysomnography similar to young patients presenting with RBD. 2019 The Canadian Journal of Neurological Sciences Inc. -
Self-esteem, eudemonic well-being and flow at work among managers in banking sector
The present research tries to establish a link among well-being, flow at work and self-esteem among managers working in banking sector. The present study aimed to investigate the gender differences in self-esteem eudemonic well-being and flow at work among managers in banking sector, and ascertain the role of self-esteem and eudemonic well-being in predicting flow at work. The present study employs an ex-post facto research design and uses purposive sampling technique to select the respondents (N=100 male and 100 female managers working in the private banks). The data was first checked for normality and then t- test and stepwise multiple regression analysis was used to analyze it. There are significant gender differences on self-esteem, employee well-being and flow at work. Different set of predictors emerged for flow at work for males and females. Studying self-esteem, eudemonic well-being and flow at work has implications not only for the individual but also for the organizations as well, as employees with better well-being and having high self-esteem will eventually help the organization to achieve its goals and objectives. 2021 Ecological Society of India. All rights reserved. -
Establishing the effectiveness of intervention module on positive youth development among adolescent in India
Purpose: Positive Youth Development (PYD) originated in the west as a pragmatic approach to teaching youth skills and attributes to develop into healthy, productive, and engaged adults. This approach proposes that youth with more developmental resources experience increased academic success, better economic prospects, are more civically engaged, and experience optimal well-being and functioning in the long term. Over time, the need for administering evidence-based interventions was felt by practitioners, researchers, and policymakers. With this background and the absence of research in PYD in India, the present research was carried out to develop and test an intervention module for its effectiveness in bringing about a positive change among youth. Approach: The present research is quantitative in nature with pre-test post-test control group design. The PYD intervention program included activities, non-profit visits, community building exercises, and mentoring programs, creating self-actualizing youth. The paper deliberates on the findings of a six-month interventional program based on the Six Cs model of Learner (2005). Findings: The independent sample t-test was significant, for overall PYD, t (98) = 3.45, p <. 001. and on all the dimensions of PYD, indicating that intervention was effective as there are statistically significant differences among experimental and control groups. Value: The intervention was experientially positive for the students, valued, and commended by the school authorities. The paper recommends enhancing psychological intervention research in school settings, including multiple approaches to address holistic student development, facilitating peer relationships and mentoring, developing resources, and enhancing growth opportunities. 2021 RESTORATIVE JUSTICE FOR ALL. -
Decoding HERO: Predicting psychological capital with subjective well-being
The positive psychology movement has gained momentum in recent years and organizations have ascribed great importance to employee well-being in light of the favorable outcomes associated with it. The widely researched Psychological Capital (PsyCap) has been consistently linked to well-being across a variety of contexts but a gap still exists in literature about what lies to the 'left' of psychological capital. The present study attempts to fill this gap by examining subjective well being components- positive and negative affect and life satisfaction, as potential antecedents of PsyCap. The Academic PsyCap questionnaire, the Positive and Negative Affect Schedule (PANAS) and the Satisfaction with Life Scale (SWLS) were administered to participants. Results confirmed the expected associations between affect and PsyCap-positive affect positively predicted PsyCap and its four constituents whereas negative affect emerged as a negative predictor of PsyCap and its dimensions. Life satisfaction positively predicted only individuals' total hope scores. Thus, highlighting the role of subjective well-being components as antecedents of PsyCap, these findings suggest that promoting higher positive affect and lower negative affect can do more than just make individuals feel good, rather, it can bolster their reservoirs of crucial psychological resources as well. 2021 Ecological Society of India. All rights reserved. -
A study on police personnels perception about causes for stress and frequency of stress occurrence
This paper states that Police Personnels Perception about causes for Occupational stress like organizational context (goals and objectives), organizational structure (size, degree of centralization), organizational processes (leadership style, decision making etc.), nature of work (shifts etc.) and physical environment (employee safety, rewards etc.) constitute the dimensions of the climate.This study is a descriptive one and it reveals the facts which are already exist. This report is about the policeconstables where it is in Tuticorin district, South part of Tamilnadu. This study focused on52 police stationswhichare divided into eight sub divisions and 600samples collected from three differentgrades of police constables. Police stress inventory (PSI) used to measure the level ofoccupational stress. Appropriate statistical tool was used for data analysis. According to theresults most of the police constables experienced more stress. Female constables facehigh stress compare with male police constables. This study concludes most of the constables areunder medium level stress group and results shows a significant difference between occupationalstressorganizational context (goals and objectives), organizational structure (size, degree of centralization), organizational processes (leadership style, decision making etc.), nature of work (shifts etc.) and physical environment (employee safety, rewards etc.). 2020 SERSC. -
Design of Lowpower 4-bit Flash ADC Using Multiplexer Based Encoder in 90nm CMOS Process
This work describes a 4-bit Flash ADC with low power consumption. The performance metrics of a Flash ADC depend on the kind of comparator and encoder used. Hence open-loop comparator and mux-based encoder are used to obtain improved performance. Simulation results show that the simulated design consumes 0.265mW of power in 90nm CMOS technology using cadence-virtuoso software. The circuit operates with an operating frequency of 100MHz and a supply voltage of 1V. The Author(s). -
Human cognition and emotional response towards visual environmental features in an urban built context: a systematic review on perception-based studies
Urban built environments can influence human cognitive and emotional comforts. Human comfort in the built environment has challenged architects and urban designers while developing comfortable spaces. Emerging cognitive-architectural studies in architecture engineering inform new directions for improvising human spatial design practices. This paper intends to present a systematic meta-analysis of selected empirical studies to identify the gaps and future scope of research in human cognition and built environments. However, the scope of the literature review is to concentrate on experiments that consider physiological reading in different environments, such as nature and architectural spaces in cognitive study areas. The peer-reviewed literature published from 2010 to 2021 illustrates that only limited design parameters are considered in these experiments. The study analyses the extensive consideration of experimental medium, simulation categories, and participant factors like gender and age in this research domain. The survey recommends considering more visual features, contextual conditions, and ethnic groups. 2023 Informa UK Limited, trading as Taylor & Francis Group. -
Effects of 12 Weeks Core Strength Training on Bio-motor Fitness Abilities among College Level Soccer Players
This study aimed to evaluate the effects of a 12-week core strength training (CST) program on bio-motor fitness components among college-level male soccer players aged 18 to 23 years. Methods: Sixteen male soccer players participated in this study. They were divided into an experimental group that underwent a CST program and a control group that maintained their regular training routine. The CST program, integrated into the regular soccer training schedule, included exercises such as planks, bridges, and various forms of crunches, progressively increasing in intensity. Upper body explosive strength was assessed using a backward medicine ball throw, lower body explosive power using a standing long jump and countermovement jump, and change of direction speed using an agility test. Sprint performance was measured with 15m and 30m linear sprint tests. Results: The CST group showed significant improvements across all measured variables. Notable percentage changes were observed in the 15m sprint (4.08%), 30m sprint (1.56%), upper body strength (6.87%), standing long jump (4.66%), countermovement jump (15.69%), and change of direction speed (12.35%). Effect sizes indicated substantial enhancements in standing long jump (g = 1.634, p = 0.001), countermovement jump (g = 7.110, p < 0.001), and change of direction speed (g = 3.142, p = 0.001). The control group did not exhibit significant changes in any variables. Conclusion: A 12-week core strength training program, consisting of three sessions per week, significantly improved bio-motor fitness components in college-level soccer players aged 18 to 23 years. These findings support the inclusion of CST in soccer training regimens to enhance athletic performance. 2024 by authors, all rights reserved. -
Brinkman-Bard convection in a rotating-binary liquid saturated porous medium
The primary intent of the work is to investigate the linear and weakly non-linear stability analyses of natural convection in a rotating binary liquidsaturated porous medium. In the mathematical model, Newtonian binary liquid-saturated porous medium with uniform rotation subjected to stress-free isothermal boundaries and the validity of OseenBoussinesq approximation is considered in the study. Normal mode analysis is operated to acquire the DarcyRayleigh number expression in terms of the other parameters. The amount of heat and mass transfer rates are approximated at the lower boundary by performing weakly non-linear stability analysis using truncated Fourier series solution. The analysis of critical Rayleigh number, critical wave number, heat, and mass transfer is done for different values of parameters and discussed in detail with the help of plots and tables. Lewis number stabilizes the convective system, whereas increasing in the separation ratio coefficient destabilizes the convective system. Weakly nonlinear stability analysis reveals that the binary liquids with a smaller separation ratio coefficient transport the maximum heat and minimum mass compared to binary liquids with large separation ratio coefficient values. The amount of heat transport is enhanced by 14% with increase in the values of Ta whereas the same is diminished by 3.5 % and 5% respectively for the ? and Le. Thus, the effect of rotations pronounced on the onset of convection, heat and mass transports predominantly compared to the effect of binary mixtures parameters. The results of the classical RayleighBard convection and natural convection in a liquid-saturated porous medium with local thermal-equilibrium assumption can be obtained as a particular case of the study by setting the appropriate limits. 2025 Elsevier Ltd -
Stability Analyses of BrinkmanBard Convection in Hybrid-Nanoliquid Saturated-Porous Medium Using Local Thermal Non-equilibrium Model
This paper carries out linear and weakly non-linear stability analyses of natural convection in a Newtonian hybrid-nanoliquid saturated porous medium. The Boussinesq approximation is assumed to be valid in the study, and a two-phase energy model is used. The weighted residual Galerkin technique is employed to obtain the expression for the Rayleigh number and Lorenz model by using a truncated double Fourier series solution. The quadratic non-linear Lorenz model is solved numerically by using the RungeKuttaFehlberg method. Water is considered as a carrier liquid, and copper and alumina nanoparticles are considered with dilute concentration. Linear stability analysis reveals the onset of convection prepones in a hybrid nanoliquid-saturated porous medium. The amount of heat transport is maximum in a hybrid nanoliquid saturated porous medium and minimum in a liquid-saturated porous medium. Local thermal non-equilibrium situation ceases at higher rates of interphase heat transfer coefficient. The assumption of local thermal non-equilibrium is prominent in hybrid nanoliquid saturated porous medium. The results of the hybrid-nanoliquid channel, a hybrid nanoliquid saturated porous medium with the local thermal assumption, are presented as a limiting case of the study. 2024, The Author(s), under exclusive licence to Springer Nature India Private Limited. -
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. -
A study on entropy generation and heat transfer in a magnetohydrodynamic flow of a couple-stress fluid through a thermal nonequilibrium vertical porous channel
The effect of local thermal nonequilibrium (LTNE) on the entropy generation and heat transfer characteristics in the magnetohydrodynamic flow of a couple-stress fluid through a high-porosity vertical channel is studied numerically using the higher-order Galerkin technique. The Boussinesq approximation is assumed to be valid and the porous medium is considered to be isotropic and homogeneous. Two energy equations are considered one each for solid and fluid phases. The term involving the heat transfer coefficient in both equations renders them mutually coupled. Thermal radiation and an internal heat source are considered only in the fluid phase. The influence of inverse Darcy number, Hartmann number, couple-stress fluid parameter, Grashof number, thermal radiation parameter, and interphase heat transfer coefficient on velocity and temperature profiles is depicted graphically and discussed. The entropy generation, friction factor, and Nusselt number are determined, and outcomes are presented via plots. The effect of LTNE on the temperature profile is found to cease when the value of the interphase heat transfer coefficient is high, and in this case, we get the temperature profiles of fluid and solid phases are uniform. The physical significance of LTNE is discussed in detail for different parameters' values. It is found that heat transport and friction drag are maximum in the case of LTNE and minimum in the case of local thermal equilibrium. We observe that LTNE opposes the irreversibility of the system. The corresponding results of a fluid-saturated densely packed porous medium can be obtained as a limiting case of the current study. 2021 Wiley Periodicals LLC -
Analytical study of BrinkmanBard convection in a bidisperse porous medium: Linear and weakly nonlinear study
Linear and weakly nonlinear stability analyses of BrinkmanBard convection of a Newtonian fluid saturating a bidisperse porous medium (BDPM) are made. Local-thermal-non-equilibrium (LTNE) is assumed between the fluid and the porous spheres (micro-pores) that make up the macro porous medium. Two coupled linear momentum equations are considered one each for the macro- and micro-pores. Results of mono-disperse porous medium (MDPM) with solid spheres are recovered as a limiting case of the present study. Further, in the case of both types of porous media considered the results of DarcyBard and BrinkmanBard convection are extracted under suitable limiting procedures. To keep the work analytical, we reduce the intractable hexa-modal Lorenz model with four quadratic nonlinearities into the tractable mono-modal StuartLandau equation (SLE) with cubic and quintic nonlinearities. Subcritical instability is discounted in the study thereby suggesting that cubic SLE and cubicquintic SLE both expound similar results qualitatively. The concept of a BDPM is shown to be meaningful only when the pores are not large, and when they are very small, then the MDPM assumption applies. Similar observation can be made when the ratio of permeabilities is large. The presence of micro-pores does not alter the size of the convective cell significantly at the onset. The present study reiterates the findings of several earlier works. 2023 Elsevier Ltd -
Rayleigh-Bard Convection of Water-Copper and Water-Alumina Nanofluids Based on Minimal- and Higher-Mode Lorenz Models
Linear and nonlinear stability analyses of Rayleigh-Bard convection in water-copper and water-alumina nanofluids are studied in the paper by considering a minimal as well as an extended truncated Fourier representation. These representations respectively result in a third-order classical Lorenz model and a five-dimensional extended Lorenz model. The marginal stability plots reveal that the influence of added dilute concentration of nanoparticles in water is to destabilize the system. The rate of destabilization depends on the nanoparticles' thermophysical properties and their volume fraction. Influence of adding an additional mode in the horizontal direction is to modify the cell size. This can be observed through the marginal curves as well as the stream line plots. Further, from the Nusselt number plots it is evident that the presence of dilute concentration of nanoparticles in water is to enhance heat transport in the system significantly. The dynamical behavior of the minimal and the extended Lorenz models is investigated using the bifurcation diagram. From the study an important finding that emerges is that the Fourier truncated solution is predicted to have different effects in lower-order and higher-order models. The extended penta-modal Lorenz system predicts advanced onset of chaos compared to that predicted by the classical third-order Lorenz model. The individual influence of both nanoparticles in water is to advance the onset of convection as well as to advance the onset of chaos. 2023 World Scientific Publishing Company. -
A study of Darcy-Bard regular and chaotic convection using a new local thermal non-equilibrium formulation
The onset of Darcy-Bard regular and chaotic convection in a porous medium is studied by considering phase-lag effects that naturally arise in the thermal non-equilibrium heat transfer problem between the fluid and solid phases. A new type of heat equation is derived for both the phases. Using a double Fourier series and a novel decomposition, an extended Vadasz-Lorenz model with three phase-lag effects is derived. New parameters arise due to the phase-lag effects between local acceleration, convective acceleration, and thermal diffusion. The principle of exchange of stabilities is found to be valid and the subcritical instability is discounted. The new perspective supports the finding of an analytical expression for the critical Darcy-Rayleigh numbers representing, respectively, the onset of regular and chaotic convection. The understanding of the transition from the local thermal non-equilibrium situation to the local thermal equilibrium one is also best explained through the new perspective. In its present elegant form, the extended Vadasz-Lorenz system with three phase-lag effects is analyzed using the largest Lyapunov exponent and the bifurcation diagram. It is found that the lag effects not only give rise to a quantitative difference in the above two metrics concerning chaos, but also present a qualitative difference as well in the form of the very nature of chaos. 2021 Author(s). -
Influence of symmetric/asymmetric boundaries on axisymmetric convection in a cylindrical enclosure in the presence of a weak vertical throughflow
The linear and nonlinear stability of axisymmetric convection of a viscous fluid in a cylindrical enclosure heated from below is investigated for various radius to height ratios. A weak vertical throughflow is imposed in a gravity-aligned or a gravity-opposing manner. Symmetric and asymmetric boundaries of free-free, rigid-rigid and rigid-free types are considered for lower and upper boundaries with isothermal temperature boundary condition. The side-walls are assumed to be rigid and adiabatic. A convergent Maclaurin series representation is considered for the finding of axial trial eigenfunctions. In order to corroborate the results of the present study with those of a previous investigation, the critical Rayleigh number and the number of radial rolls manifesting for any given aspect ratio are determined in the case of no throughflow and an exact match is found. Further, the influence of boundaries and the effect of throughflow on chaotic and periodic regimes of motion are studied with the help of a time series solution and the largest Lyapunov exponent as indicators of chaos. The novelty of the present study is the use of a Maclaurin series representation for the eigenfunctions of the linear problem and using the same in determining the solution with the convective mode. 2023 Elsevier B.V. -
A Unified Approach to Two-Dimensional Brinkman-Bard Convection of Newtonian Liquids in Cylindrical and Rectangular Enclosures
A unified model for the analysis of two-dimensional BrinkmanBard/RayleighBard/ DarcyBard convection in cylindrical and rectangular enclosures ((Formula presented.)) saturated by a Newtonian liquid is presented by adopting the local thermal non-equilibrium ((Formula presented.)) model for the heat transfer between fluid and solid phases. The actual thermophysical properties of water and porous media are used. The range of permissible values for all the parameters is calculated and used in the analysis. The result of the local thermal equilibrium ((Formula presented.)) model is obtained as a particular case of the (Formula presented.) model through the use of asymptotic analyses. The critical value of the Rayleigh number at which the entropy generates in the system is reported in the study. The analytical expression for the number of Bard cells formed in the system at the onset of convection as a function of the aspect ratio, (Formula presented.), and parameters appearing in the problem is obtained. For a given value of (Formula presented.) it was found that in comparison with the case of (Formula presented.), more number of cells manifest in the case of (Formula presented.). Likewise, smaller cells form in the (Formula presented.) problem when compared with the corresponding problem of (Formula presented.). In the case of (Formula presented.), fewer cells form when compared to that in the case of (Formula presented.) and (Formula presented.). The above findings are true in both (Formula presented.) and (Formula presented.). In other words, the presence of a porous medium results in the production of less entropy in the system, or a more significant number of cells represents the case of less entropy production in the system. For small and finite (Formula presented.), the appearance of the first cell differs in the (Formula presented.) and (Formula presented.) problems. 2023 by the authors. -
Effect of homogeneous chemical reaction on the dispersion of a solute in a threedimensional flow of a Newtonian liquid through a porous medium
All-Time dispersion of a reactive solute in a Newtonian fluid flow through a Darcy-Brinkman-Forchheimer Porous medium is carried out using the approach of Gill - Sankarasubramanian (1970) and Doshi etal. (1978). The velocity profile of the non - linear porous medium flow equation is solved using the Maclaurin series of two variables. The three - dimensional model brings into the focus the convective and dispersion coefficients. The chemical reaction is assumed to be homogeneous. The chemical reaction is shown to increase the value of the convective coefficient while it decreases with increase in the value of the reaction rate parameter. The effect of the presence of the porous medium is to decrease the flow and hence the convective coefficient. Similar effect of the porous parameter is seen on the dispersion coefficient. The reaction rate parameter and the porous parameter have opposite effect on the mean concentration distribution. 2023 Taylor & Francis Group, LLC. -
A New Series Solution Applicable to a Class of Boundary Layer Equations with Exponential Decay in Solution
A new series solution for the coupled nonlinear boundary value problem (BVP) of the FalknerSkan-type, resulting from the use of the boundary layer approximation to a mixed convective flow is obtained. The solution domain is transformed from the semi-infinite interval of physical interest to the unit interval by using the transformation z= 1 - e-?. The coupled nonlinear BVP is converted into an equivalent initial value problem (IVP) by supplying appropriate initial conditions. Series solution of the equivalent IVP is obtained in powers of 1 - e-? with assistance from the NewtonRaphson method. Convergence of the series is assured by the very design of the series as confirmed by the DombSykes plots and the plots of partial sums. The results of the series solution compare well with the numerical results obtained by the shooting method based on the RungeKuttaFehlberg45 and NewtonRaphson methods. The novelty of the methodology lies in the construction of a new series solution for a class of problems with exponential decay in their solution. Such a work has not been reported before. 2020, Springer Nature India Private Limited.