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Significance of Darcy-Forchheimer Porous Medium in Nanofluid Through Carbon Nanotubes
This article manages Darcy-Forchheimer 3D flow of water based carbon nanomaterial (CNTs). A bidirectional nonlinear stretchable surface has been utilized to make the flow. Disturbance in permeable space has been represented by Darcy Forchheimer (DF) expression. Heat transfer mechanism is explored through convective heating. Outcomes for SWCNT and MWCNT have been displayed and compared. The reduction of partial differential framework into nonlinear common differential framework is made through reasonable variables. Optimal series scheme is utilized for arrangements advancement of associated flow issue. Optimal homotopic solution expressions for velocities and temperature are studied through graphs by considering various estimations of physical variables. Moreover surface drag coefficients and heat transfer rate are analyzed through plots. 2018 Chinese Physical Society and IOP Publishing Ltd. -
Brinkman-Forchheimer flow of SWCNT and MWCNT magneto-nanoliquids in a microchannel with multiple slips and Joule heating aspects
Purpose: The microfluidics has a wide range of applications, such as micro heat exchanger, micropumps, micromixers, cooling systems for microelectronic devices, fuel cells and microturbines. However, the enhancement of thermal energy is one of the challenges in these applications. Therefore, the purpose of this paper is to enhance heat transfer in a microchannel flow by utilizing carbon nanotubes (CNTs). MHD Brinkman-Forchheimer flow in a planar microchannel with multiple slips is considered. Aspects of viscous and Joule heating are also deployed. The consequences are presented in two different carbon nanofluids. Design/methodology/approach: The governing equations are modeled with the help of conservation equations of flow and energy under the steady-state situation. The governing equations are non-dimensionalized through dimensionless variables. The dimensionless expressions are treated via Runge-Kutta-Fehlberg-based shooting scheme. Pertinent results of velocity, skin friction coefficient, temperature and Nusselt number for assorted values of physical parameters are comprehensively discussed. Also, a closed-form solution is obtained for momentum equation for a particular case. Numerical results agree perfectly with the analytical results. Findings: It is established that multiple slip effect is favorable for velocity and temperature fields. The velocity field of multi-walled carbon nanotubes (MWCNTs) nanofluid is lower than single-walled carbon nanotubes (SWCNTs)-nanofluid, while thermal field, Nusselt number and drag force are higher in the case of MWCNT-nanofluid than SWCNT-nanofluid. The impact of nanotubes (SWCNTs and MWCNTs) is constructive for thermal boundary layer growth. Practical implications: This study may provide useful information to improve the thermal management of microelectromechanical systems. Originality/value: The effects of CNTs in microchannel flow by utilizing viscous dissipation and Joule heating are first time investigated. The results for SWCNTs and MWCNTs have been compared. 2018, Emerald Publishing Limited. -
Enhancements to greedy web proxy caching algorithms using data mining method and weight assignment policy
A Web proxy caching system is an intermediary between the users and servers that tries to alleviate the loads on the servers by caching selective Web objects and behaves as the proxy for the server and service the requests that are made to the servers by the users. In this paper the performance of a proxy system is measured by the number of hits at the proxy. A higher number of hits at the proxy server reflects the effectiveness of the proxy system. The number of hits is determined by the replacement policies chosen by the proxy systems. Traditional replacement policies that are based on time and size are reactive and do not consider the events that will possibly happen in the future. The outcomes of the paper are proactive strategies that augment the traditional replacement policies with data mining techniques. In this paper, the performances of the greedy replacement policies such as GDS, GDSF and GD* are adapted by the data mining method and weight assignment policy. Experiments were conducted on various data sets. Hit ratio and byte hit ratio were chosen as parameters for performance. 2018 ISSN. -
Effect of multiwalled carbon nanotube alignment on the tensile fatigue behavior of nanocomposites
The one-dimensional structure of carbon nanotubes makes them highly anisotropic, making them to possess unusual mechanical properties, and hence employed as promising nanofiller for the composite structures. However, various carbon nanotube properties are not completely utilized when they are used as reinforcement in composites due to inadequate and immature processing techniques. In the present work, an attempt has been made to utilize the strong anisotropic nature of multi-walled carbon nanotubes (MWCNTs) for improving the fatigue life of nanocomposites only by considering a very low weight percentage (<0.5 wt%). The anisotropy of MWCNTs was imparted into the nanocomposites by aligning them in the epoxy matrix with DC electric field during composite curing. Nanocomposites were made for three MWCNT loadings (0.1, 0.2, and 0.3 wt%). The tensile fatigue behavior was investigated under stress control by applying cyclic sinusoidal load with the frequency range of 13 Hz and stress ratio, R = 0.1. The specimens were tested for the fatigue load until the failure or 1E+05 cycles. The fractured surfaces were examined through scanning electron microscope to analyze the fatigue fracture behavior. A small weight percentage of MWCNT loading (0.2 wt%) into the polymer composite has enhanced on an average 13% to 15% fatigue life, which is encouraging to develop the low cost, improved fatigue life composite structures. Also, the energy dissipation mechanism in MWCNT dispersed nanocomposites has shown a reduced crack propagation rate. The Author(s) 2017. -
Effect of vacancies on thermopower of molybdenum disulfide monolayers
A detailed theoretical investigation of the effect of scattering of electrons and phonons by lattice vacancies in molybdenum disulfide (MoS2) monolayers (MLs) on diffusion, S d, and phonon-drag, S g, components of thermoelectric power (TEP), S, is presented over a wide-temperature range (1 < T < 300 K) using the Boltzmann transport formalism. The diffusion component is assumed to be influenced, not only by vacancies via short-range and Coulomb disorder scattering, but also by charged impurities (CIs) and acoustic and optical phonons. In the case of S g, the phonons are considered to be scattered, besides the vacancies, by sample boundaries, substitutional isotopic impurities, as well as other phonons via both N- and U-processes. Numerical calculations of S d and S g, as functions of temperature and vacancy defect density are presented for MoS2 MLs with n s = 1017 m-2 supported on SiO2/Si substrates. The role of carrier scatterings by mono-sulfur and mono-molybdenum vacancies in influencing the overall electron and phonon relaxation rates and in determining S d and S g are investigated. The behavior of S d and S g is found to be noticeably influenced by vacancy scattering. The influence on S d is seen to be more for mono-sulfur vacancies for densities lesser than 1%. The influence, is to enhance S d slightly for MLs with realizable CI concentrations. On the other hand, S g is found to depend sensitively on the vacancy disorder for T < 50 K; a S-vacancy density of 0.1% is found to suppress the characteristic peak of S g by almost 60%. The extent of reduction in the characteristic peak of S g, observable in low temperature measurements of S, can provide information about defect density. The calculations demonstrate that defect engineering of MoS2 ML systems can be used to tune their thermoelectric performance. A need for detailed experimental studies is suggested. 2018 IOP Publishing Ltd. -
On the Motion of Non-Newtonian EyringPowell Fluid Conveying Tiny Gold Particles Due to Generalized Surface Slip Velocity and Buoyancy
In the painting industry, space science and biomedical science, the nature of relaxation in the flow of non-Newtonian fluid (i.e. blood) containing gold (Ag) suits the characteristics of EyringPowell fluid flow induced by generalized surface slip velocity and buoyancy. However, flow of various non-Newtonian fluids on the horizontal surface of a slanted paraboloid of revolution objects (i.e. rocket, as in space science), over a bonnet of a car and over a pointed surface of an aircraft is of importance to experts in all these fields. In this article, the analysis of the motion within the thin layer formed on a horizontal object which is neither a perfect horizontal nor vertical and neither an inclined surface nor a cone/wedge is presented. The transformed governing equations which model the flow was non-dimenzionalized, parameterized and solved numerically using a well-known RungeKutta integration procedure along with shooting technique. The influence of increasing the magnitude of major parameters on the temperature distribution, local heat transfer rate, concentration of the fluid, local skin friction coefficient and velocity of the flow are illustrated graphically and discussed. Velocity slip parameter is found to be a decreasing function of temperature distribution across the flow. Heat transfer rate (NuxRex-1/2) at the wall (?= 0) is an increasing function of velocity slip parameter. Maximum coefficient of concentration of homogeneous bulk fluid at the wall exists at larger values of the emerged velocity slip and volume fraction parameters. 2018, Springer Nature India Private Limited. -
Performance Analysis of Novel Compact Octagonal Shaped Fractal Antenna for Broadband Wireless Applications
Antenna plays an important role in any part of the communication system. It has to be designed very cautiously to provide improved system performance to meet the developments in wireless technologies with various design constraints such as small size, low cost, high data, low power consumption and wideband capabilities. Several efforts have been made by various investigators around the globe to amalgamate benefits of fractal structures with electromagnetic concepts and applications to reduce the size of the antenna without obstructing the performance of the antennas. This paper proposes a novel compact octagonal shaped broadband fractal antenna. The proposed antenna was designed on an inexpensive FR4-epoxy substrate and simulated using the High Frequency Structure Simulator. The antenna resonates in dual bands in 3.8 and 1GHz with lowest return loss of ?32.80dB and gain of 10.22dB while maintaining the VSWR in the 2:1 level. Attempts have been made to reduce the size and improve the bandwidth using fractal concept and truncation of ground plane. The fabricated antenna was verified experimentally and the results are agreeing with the simulations. The point of attraction of this antenna is the use of single patch for broadband coverage with easy fabrication. 2018, Springer Science+Business Media, LLC, part of Springer Nature. -
Template-based classification of SDSS-GALEX point sources
We have classified a sample of 37,492 objects from SDSS into QSOs, galaxies and stars using photometric data over five wave bands (u, g, r, i and z) and UV GALEX data over two wave bands (near-UV and far-UV) based on a template fitting method. The advantage of this method of classification is that it does not require any spectroscopic data and hence the objects for which spectroscopic data is not available can also be studied using this technique. In this study, we have found that our method is consistent by spectroscopic methods given that their UV information is available. Our study shows that the UV colours are especially important for separating quasars and stars, as well as spiral and starburst galaxies. Thus it is evident that the UV bands play a crucial role in the classification and characterization of astronomical objects that emit over a wide range of wavelengths, but especially for those that are bright at UV. We have achieved the efficiency of 89% for the QSOs, 63% for the galaxies and 84% for the stars. This classification is also found to be in agreement with the emission line diagnostic diagrams. 2018, Indian Academy of Sciences. -
A study on optimal portfolio construction with special reference to NSE CNX Nifty pharma index
Portfolio is a process of blending together the broad asset classes so as to obtain optimum return with minimum risk is called portfolio construction. In order to reduce the risk, investors need to diversify, spread their portfolio across a broad mix of assets. Diversifying the portfolio can help smooth out market ups and downs and returns from better performing assets help to offset those that arent performing so well. The present study has empirically examined the portfolio construction with special reference to NSE CNX Nifty Pharma Index. The study applied the Sharpe Single Index model to generate an efficient combination of securities from sample Pharma companies and has come up with a subsequent pattern. The study found that out the sample Pharma companies, Aurobindo Pharma Ltd attracted high risk while Glenmark Pharmaceuticals Ltd experienced the least risk, on the basis of return earned by the companies in the Pharma Index; Aurobindo Pharma Ltd has high return while Lupin Ltd has lowest return. Experimental results have demonstrated the feasible of the investment strategy, portfolio idea and electiveness of the combination assets on the investment strategy. IAEME Publication. -
Transformation of hydrocarbon soot to graphenic carbon nanostructures
Graphenic carbon nanostructures were synthesized from different precursors of petroleum and agricultural origin by oxidative scissoring. In the present study soot, an environmental pollutant is converted to a value-added product by facile synthesis techniques. The physicochemical changes of the nanostructures are investigated by means of XRD, AFM, FTIR, Raman spectroscopy, XPS analyses SEM-EDS and TEM analysis. XRD analysis confirms the formation of few layer oxidized carbon nanostructures with smaller lateral dimensions. Raman spectra reveal the existence of graphenic layer with a fewer defect. AFM and SEM analyses reveal the formation of stacked tiny fragments of graphenic carbon lamellae. XPS and IR analyses confirm the incorporation of oxygen functionalities into the carbon backbone. 2018 by the authors. -
What is beautiful is good: An evalutation of effectiveness of attractiveness in celebrity endorsements
The studies in the field of marketing have shown that characteristics of the source will influence persuasiveness of an advertisement. Attractiveness is one such celebrity characteristic that is widely studied by researchers in the field of marketing. However, still, literature failed to explain how attractiveness of celebrity endorsers influenced purchase intentions. This study tried to fill this gap by modelling the influence of celebrity attractiveness on purchase intention. It also evaluated the effect of respondents' gender on the model. The data collection for the study were carried out during March - June 2017. The study found that the effect of celebrity attractiveness on purchase intention was mediated by celebrity brand fit, attitude towards the advertisement, and attitude towards the brand. The study also evaluated the moderating effect of respondents' gender using chi- square analysis, which found no significant model difference among male and female respondents. These findings indicated that celebrity attractiveness created purchase intention in a mediated manner among the respondents, irrespective of their gender. 2018, Associated Management Consultants Private Limited. -
Mining the web data for classifying and predicting users' requests
Consumers are the most important asset of any organization. The commercial activity of an organization booms with the presence of a loyal customer who is visibly content with the product and services being offered. In a dynamic market, understanding variations in client?s behavior can help executives establish operative promotional campaigns. A good number of new consumers are frequently picked up by traders during promotions. Though, several of these engrossed consumers are one-time deal seekers, the promotions undeniably leave a positive impact on sales. It is crucial for traders to identify who can be converted to loyal consumer and then have them patronize products and services to reduce the promotion cost and increase the return on investments. This study integrates a classifier that allows prediction of the type of purchase that a customer would make, as well as the number of visits that he/she would make during a year. The proposed model also creates outlines of users and brands or items used by them. These outlines may not be useful only for this particular prediction task, but could also be used for other important tasks in e-commerce, such as client segmentation, product recommendation and client base growth for brands. Copyright 2018 Institute of Advanced Engineering and Science. All rights reserved. -
Parental Involvement in School Counseling Services: Challenges and Experience of Counselor
School counselors include parents as informants in school counseling for various reasons like for consultation and clients intervention which could lead to a different experience. The objective of the present study was to explore the challenges faced by school counselors when involving parents in the school counseling process and the ways they handle the challenges. The participants consisted of seven school counselors, with whom in-depth interviews were conducted. The subjective experiences of the school counselors were objectively interpreted by the researcher using interpretative phenomenological analysis. The research results were categorized into master and subordinate themes using double hermeneutics. The results revealed that although school counselors have their own individual perceptions of challenges and methods of handling parental inclusion in the school counseling context, there still exist similarities in their methods of handling. The study highlights school counselors beliefs about parents perceptions and expectations of counseling as well as parents reaction toward their childs problem as a challenge. The findings throw light on the need for stronger evidence-based practices and policies for school counseling programs. Training and competence-building programs for school counselors would improve the service delivery. 2018, National Academy of Psychology (NAOP) India. -
Synthesis and Characterization of Cyclopentadithiophene and Thienothiophene-Based Polymers for Organic Thin-Film Transistors and Solar Cells
Novel donor-donor type alternating copolymers (8CDT-TT and 16CDT-TT) derived from cyclopentadithiophene (CDT) and thienothiophene (TT) moieties that differ from solubilizing side chains were successfully synthesized and characterized. After the synthesis of CDT-TT-based conjugated polymers with dioctyl and dihexadecyl side chains, their optical, thermal, structural and semiconducting properties were investigated. Organic thin-film transistors fabricated from 8CDT-TT and 16CDT-TT exhibit carrier mobilities as high as 3.920-4 and 1.050-3 cm2V-1s-1, respectively. Bulk heterojunction solar cells fabricated using a polymer:PCBM blend ratio of 1:3 exhibit power conversion efficiencies of 2.12 and 1.84% for 8CDT-TT and 16CDT-TT, respectively. 2018, The Polymer Society of Korea and Springer Nature B.V. -
Numerical study of thermal performance in a circular pipe using angle plate inserts directed in horizontal and vertical directions
A novel type of angle plate inserts (APIs) was designed to improve the convection heat transfer in a circular pipe. In the present work characteristics of heat transfer, flow resistance, and overall thermo-hydraulic performance of turbulent airflow in a circular tube fitted with APIs were investigated at the Reynolds numbers range of 6000-18000 through numerical simulation. Our main attention was paid to the effects of the APIs with forward or backward arrangements, and the angle plates with various inclined angles (? = 30, 45 and 60) inserted in the circular tube for a constant pitch of 0.03 m. The results show that the Nusselt number is augmented by 2.39-4.63 times (Nu = 124.25-239.76) as that of the smooth tube. The value of performance index (PI) lies in the range of 1.34-1.63, which demonstrates that the angle plate insert has a very good overall thermo-hydraulic performance. The numerical results obtained were compared with those from plain tubes of published data and empirical relations. The maximum increases in Nusselt number for the inclined forward angle plate insert were 1.34 to 1.5 times and, while those for the backward angle plate insert were 1.46 to 1.63 over the plain tube, respectively. The friction factor ( f ) resulted in an increase of 4.28-23.12 times in case of forward arrangement and 8.09-31.76 times in case of backward arrangement. In addition, the use of the angle plate insert strip with backward arrangement leads to better overall enhancement ratio than that with forwarding arrangement around 8% to 9%. 2018 Pushpa Publishing House, Allahabad, India. -
Evaluation of cytotoxicity and antioxidant properties of some Zingiberaceae plants
Aim: Zingiberaceae family is widely distributed in the tropical realm of Asia. Considering its diverse applications as spices and therapeutics, the present study was undertaken to evaluate the cytotoxic and antioxidant effect of the ethanolic rhizome extracts of five plants, namely Alpinia galanga (L.) Willd., Alpinia zerumbet (Pers.) B.L. Burtt and R. M. Smith, Curcuma caesia Roxb., Zingiber officinale Rosc., and Zingiber zerumbet (L.) Smith on Allium cepa Linn. system. Materials and Methods: Cytotoxicity was evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) and 2',7'-dichlorofluorescein diacetate (DCFDAH 2 ) assays. Further, in vitro DNA protection assay was performed to confirm the antioxidant potentials of the extracts. Characterization of phytochemicals was done by performing qualitative tests. Results and Discussion: TTC reduction assay revealed that the extracts (2.5, 5, and 10 g/ml) had no cytotoxic effect on A. cepa root cells. Roots treated with extracts (2.5 g/ml) were stained with reactive oxygen species-sensitive dye DCFDAH 2 and visualized under the fluorescence microscope. The result confirmed that the extracts did not exert any prooxidant effect. Further, the extracts established their substantial antioxidant potential by inhibiting oxidative DNA damage in an in vitro system. In addition, qualitative analysis showed that the rhizomes are rich in phytochemicals. Conclusion: From the current observations, it can be concluded that the selected herbs can be utilized safely for human consumption. 2019 BRNSS Publication Hub. All Rights Reserved. -
The hope and the dilemma of the urban poor
A common view about economically weaker sections and lower-income groups in India is that they live in slums because they cannot afford to buy or rent decent accommodation in the formal market. However, some can pay a monthly rent and/or for the services such as garbage disposal and water, but they, and others who can afford to buy, are deterred by institutional constraints. Many slum households face a dilemma: opting for better and more secure living conditions would mean losing some of the advantages of living in a slum and the possibility of a free home. 2018 Economic and Political Weekly. All rights reserved. -
Tailoring of low grade coal to fluorescent nanocarbon structures and their potential as a glucose sensor
Lignite is an abundantly utilized feedstock for the facile synthesis of fluorescent carbon dots and carbon nanomaterials. Its value is appreciated as an energy source for combustion for long time. Herein we report a novel top-down strategy to synthesis lignite based fluorescent nano carbon structures by combined acidic oxidation and chemical reflux. The nanocarbon crystallites in lignite are converted to oxygenated nano carbon dots and graphene sheets. They exhibited stable fluorescence property in the visible region depending on their size, functionalities and defects which were highly stable in all the pH conditions. These nanocarbon structures are an effective probe for fluorescent sensing of label-free and selective detection of glucose ions with detection limit as low as 0.125 mM, promising real-world sensor applications. These findings establish a scalable method for the production of fluorescent carbon based glucose sensor from lignite. 2018, The Author(s). -
Variable viscosity effects on third-grade liquid flow in post-treatment analysis of wire coating in the presence of nanoparticles
Purpose: The features of coated wire product are measured by the flow and heat transport occurring in the interior of dies. Therefore, an understanding of characteristics of polymers momentum, heat mass transfer and wall shear stress is of great interest. Enhancement of heat transfer rate is fundamental need of wire coating process. Therefore, this study aims to investigate the effect of suspended nanoparticles in heat and mass transport phenomena of third-grade liquid in post-treatment of wire coating process. Buongiorno model for nanofluid is adopted. Two cases of temperature dependent viscosity are considered. Design/methodology/approach: The governing equations are modelled with the help of steady-state conservation equations of mass, momentum, energy and nanoparticle concentration. Some appropriate dimensionless variables are introduced. Numerical solutions for the nonlinear problem are developed through RungeKuttaFehlberg technique. The outcome of sundry variables for dimensionless flow, thermal and nanoparticle volume fraction fields are scrutinised through graphical illustrations. Findings: The studys numerical results disclose that the force on the total wire surface and shear stress at the surface in case of Reynolds Model dominate Vogels Model case. Impact of nanoparticles is constructive for force on the total wire surface and shear stress at the surface. The velocity of the coating material can be enhanced by the non-Newtonian property. Practical implications: This study may provide useful information to improve the wire coating technology. Originality/value: Effect of nanoparticles in wire coating analysis by using Brownian motion and thermophoresis slip mechanisms is investigated for the first time. Two different models for variable viscosity are used. 2018, Emerald Publishing Limited. -
Electrochemical synthesis, photodegradation and antibacterial properties of PEG capped zinc oxide nanoparticles
The effect of surfactant and dopant on the properties of zinc oxide nanoparticles were studied by preparing polyethylene glycol (PEG) capped ZnO and tungsten doped PEG capped ZnO nanoparticles via the electrochemical method. These nanoparticles were characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet Diffuse Reflection Spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM) and Electron Dispersive Analysis of X Rays (EDAX). The photocatalytic degradation of malachite green dye using these nanoparticles was studied under visible light. The effects of various reaction parameters like dye concentration, catalyst concentration, pH and time were studied to optimize the photodegradation reaction. Reusability of these nanoparticles was studied and no significant change was observed in the degradation efficiency of PEG capped ZnO till the fourth cycle, while there was a gradual decrease in the degradation efficiency of tungsten doped PEG capped ZnO. Langmuir- Hinshelwood kinetic model well describes the photodegradation capacity and the degradation of malachite green follows pseudo-first order kinetics.Photocatalytic studies reveal that PEG capping increases the degradation properties of ZnO while tungsten doping decreases the extent of PEG capping and has a detrimental effect on the degradation properties of ZnO. The prepared nanoparticles exhibit significant antibacterial properties against gram-positive Bacillus cereus and gram-negative Escherichia coli bacterial strains by agar well diffusion method. 2018 Elsevier B.V.