On bio-convection thermal radiation in Darcy – Forchheimer flow of nanofluid with gyrotactic motile microorganism under Wu’s slip over stretching cylinder/plate

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
H. Waqas ◽  
M. Imran ◽  
Taseer Muhammad ◽  
Sadiq M. Sait ◽  
R. Ellahi
Keyword(s):  
Mixed Convection ◽  
Volume Fraction ◽  
Research Work ◽  
Concentration Field ◽  
Second Order ◽  
Original Research ◽  
Stretching Cylinder ◽  
Content Type ◽  
Mixed Convection Parameter ◽  
Convection Parameter

Purpose The purpose of this study is to discuss the Darcy–Forchheimer nanoliquid bio-convection flow by stretching cylinder/plate with modified heat and mass fluxes, activation energy and gyrotactic motile microorganism features. Design/methodology/approach The proposed flow model is based on flow rate, temperature of nanomaterials, volume fraction of nanoparticles and gyrotactic motile microorganisms. Heat and mass transport of nanoliquid is captured by the usage of popular Buongiorno relation, which allows us to evaluate novel characteristics of thermophoresis diffusion and Brownian movement. Additionally, Wu’s slip (second-order slip) mechanisms with double stratification are incorporated. For numerical and graphical results, the built-in bvp4c technique in computational software MATLAB along with shooting technique is used. Findings The influence of key elements is illustrated pictorially. Velocity decays for higher magnitude of first- and second-order velocity slips and bioconvection Rayleigh number. The velocity of fluid has an inverse relation with mixed convection parameter and local inertia coefficient. Temperature field enhances with the increase in estimation of thermal stratification Biot number and radiation parameter. A similar situation for concentration field is observed for mixed convection parameter and concentration relaxation parameter. Microorganism concentration profile decreases for higher values of bioconvection Lewis number and Peclet number. A detail discussion is given to see how the graphical aspects justify the physical ones. Originality/value To the best of the authors’ knowledge, original research work is not yet available in existing literature.

Mixed convection boundary layer flow from a vertical truncated cone in a nanofluid

2014 ◽  
Vol 24 (5) ◽  
pp. 1175-1190 ◽  
Author(s):  
F.O. Pătrulescu ◽  
T. Groşan ◽  
I. Pop
Keyword(s):  
Boundary Layer ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Convection Boundary Layer ◽  
Particle Volume ◽  
Content Type ◽  
Mixed Convection Parameter ◽  
Layer Flow ◽  
Convection Parameter

Purpose – The purpose of this paper is to investigate the steady mixed convection boundary layer flow from a vertical frustum of a cone in water-based nanofluids. The problem is formulated to incorporate three kinds of nanoparticles: copper, alumina and titanium oxide. The working fluid is chosen as water with the Prandtl number of 6.2. The mathematical model used for the nanofluid incorporates the particle volume fraction parameter, the effective viscosity and the effective thermal diffusivity. The entire regime of the mixed convection includes the mixed convection parameter, which is positive for the assisting flow (heated surface of the frustum cone) and negative for the opposing flow (cooled surface of the frustum cone), respectively. Design/methodology/approach – The transformed non-linear partial differential equations are solved numerically for some values of the governing parameters. The derivatives with respect to? were discretized using the first order upwind finite differences and the resulting ordinary differential equations with respect to? were solved using bvp4c routine from Matlab. The absolute error tolerance in bvp4c was 1e-9. Findings – The features of the flow and heat transfer characteristics for different values of the governing parameters are analysed and discussed. The effects of the particle volume fraction parameter \phi, the mixed convection parameter \lambda and the dimensionless coordinate? on the flow and heat transfer characteristics are determined only for the Cu nanoparticles. It is found that dual solutions exist for the case of opposing flows. The range of the mixed convection parameter for which the solution exists increases in the presence of the nanofluids. Originality/value – The paper models the mixed convection from a vertical truncated cone using the boundary layer approximation. Multiple (dual) solutions for the flow reversals are obtained and the range of existence of the solutions was found. Particular cases for ?=0 (full cone), ? >>1 and (free convection limit) \lambda>>1were studied. To the authors best knowledge this problem has not been studied before and the results are new and original.

Mixed convection stagnation point flow of a hybrid nanofluid past a vertical flat plate with a second order velocity model

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alin V. Roşca ◽  
Natalia C. Roşca ◽  
Ioan Pop
Keyword(s):  
Differential Equations ◽  
Mixed Convection ◽  
Stagnation Point ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Second Order ◽  
Hybrid Nanofluid ◽  
Content Type ◽  
Practical Applications ◽  
Hybrid Nanofluids

Purpose The purpose of this study is to describe the steady mixed convection stagnation point of a hybrid nanofluid with a second-order velocity slip. Design/methodology/approach Using appropriate similarity variables, the partial differential equations are transformed into ordinary (similar) differential equations, which are numerically solved using the bvp4c function in MATLAB. The numerical results are used to present graphical illustrations for the reduced skin friction, reduced Nusselt number, velocity and temperature profiles. Findings Dual solutions are discovered in this study. Thus, stability analysis is implemented and the first (upper branch) and second (lower branch) solutions are determined and analyzed. Research limitations/implications Hybrid nanofluids have many practical applications in the modern industry such as in micro-manufacturing, periodic heat exchanges process, nano drug delivery system and nuclear reactors. Originality/value Despite numerous studies on the mixed convection stagnation point of classical viscous fluids past a vertical plate flow, none of the researchers have focused on the effect of second-order slip velocity on hybrid nanofluids. The behavior of the flow and heat transfer has been thoroughly analyzed with the variations in governing parameters such as heat source/sink and nanoparticle volume fraction. Moreover, the use of the wall slip velocity in this hybrid nanofluid model strengthened the novelty of this study.

Active thermography as a tool for internal composite structure observation and evaluation

2018 ◽  
Vol 9 (6) ◽  
pp. 779-792 ◽  
Author(s):  
Katarzyna Majewska ◽  
Magdalena Mieloszyk ◽  
Wieslaw Ostachowicz
Keyword(s):  
Research Work ◽  
Structural Condition ◽  
Original Research ◽  
Pulsed Thermography ◽  
Content Type ◽  
Three Samples ◽  
Structure Observation ◽  
Material Discontinuities ◽  
Excellent Tool ◽  
Composite Samples

Purpose The purpose of this paper is to study if it is possible applying infrared thermography (both vibro and pulsed) to detect and localise material discontinuities as well as to find the place where the inclusion was introduced. Design/methodology/approach The experimental investigation is performed on samples manufactured during infusion process. The measurements were performed on three four-layered rectangular composite samples with discontinuities. The discontinuities introduced in the samples were as follow: all three samples between first and second layer counting form the bottom two optical fibres (OFs) were embedded and additionally: sample no. 1 – one of the OF was broken, sample no. 2 – the drop of water was introduced, and sample no. 3 – the little amount of dust was introduced. Findings For some discontinuities, the vibrothermography is excellent tool (placement of broken OF, drop of water), for same is not sufficient (healthy OFs or dust). For dust, the pulsed thermography seems to be the required tool. Different approaches (vibrothermography and pulsed thermography) for the same sample will confirm that for same defects vibrothermograpy is better and for some pulsed thermography – complex combination of different thermography approaches is needed to have complex response about sample structural condition. Originality/value The presented paper is an original research work. There are very limited literature papers applying both vibro and pulsed thermography for one problem. The assessment of different discontinuities (inclusions) and detailed analysis is presented.

System and neural network analysis of intent to buy and willingness to pay insurance premium

2019 ◽  
Vol 45 (1) ◽  
pp. 147-168 ◽  
Author(s):  
Sanjay Tolani ◽  
Ananth Rao ◽  
Genanew B. Worku ◽  
Mohamed Osman
Keyword(s):  
Neural Network ◽  
Social Security ◽  
Willingness To Pay ◽  
United Arab Emirates ◽  
Middle Eastern ◽  
Country Of Origin ◽  
Research Work ◽  
Original Research ◽  
Content Type ◽  
Social Security Benefits

Purpose The purpose of this paper is to analyze significant determinants to assess the probability of insureds’ intent to buy (ITB) insurance and willingness to pay (WTP) quantum of dollars for security benefits. Design/methodology/approach The authors use the Double Hurdle Model (DHM) and Neural Network (NN) architecture to analyze the insureds’ behavior for ITB and WTP. The authors apply these frameworks to all the 503 insureds of a branch of a leading insurer in the United Arab Emirates. Findings The DHM identified age, loans & liabilities, body mass index, travel outside the UAE, salary and country of origin (Middle Eastern and African) as significant determinants to predict WTP for social security benefits. In addition to these determinants, NN architecture identified insurance replacement, holding multiple citizenship, age of parents, mortgages, country of origin: Americas, length of travel, income of previous year and medical conditions of insured as additional important determinants to predict WTP for social security benefits; thus, NN is found to be superior to DHM due to its lowest RMSE and AIC in the holdout sample and also its flexibility and no assumptions unlike econometric models. Research limitations/implications Insureds’ data used from one UAE Branch limit the generalizability of empirical findings. Practical implications The study findings will enable the insurers to appropriately design the insurance products that match the insurers’ behavior of ITB and WTP for social security benefits. Social implications The study findings have the potential for insurance institutions to be more flexible in their insurance practices through public–private partnerships. Originality/value This is the authors’ original research work.

Characterization of the mechanical behaviour of wooden construction materials from “quinta lobeira de cima”

2018 ◽  
Vol 9 (3) ◽  
pp. 396-410 ◽  
Author(s):  
Patricia Raposo ◽  
João Martins ◽  
José Correia ◽  
Maria E. Salavessa ◽  
Cristina Reis ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Mechanical Behaviour ◽  
Research Work ◽  
Construction Materials ◽  
Image Correlation ◽  
Original Research ◽  
Content Type ◽  
Cultural Patrimony ◽  
Master Thesis ◽  
Longitudinal Modulus

Purpose The antique structures are part of the inheritance that our elders left, being important to preserve their memories. It is important to preserve, rehabilitate and restore the historic buildings protecting the cultural patrimony, attending to the actual comfort and habitability requirements. It is necessary to study the behaviour of the various elements that compose antique structures (masonry and wood) in order to develop assessment measures according to the characteristics of the original materials. The paper aims to discuss these issues. Design/methodology/approach An experimental campaign to characterize the mechanical behaviour of the wood of the roof of the “sequeiro” of “Quinta Lobeira de Cima”, a building from the twentieth century located in Minho, was carried out. The tested wood specimens are from two different species: chestnut and oak. Compression, tension and static flexion tests according to parallel to the grain direction were performed. Other parameters, such as density, moisture content and longitudinal modulus of elasticity in compression and in tension, were also obtained. The measurement of displacements was made with Digital Image Correlation (DIC). Findings The results of this study show the similarity between experimental and empirical values for the studied woods species. Originality/value This original study aimed at characterizing the mechanical properties using DIC of wood of the roof of the “sequeiro” of “Quinta Lobeira de Cima”, a building from the twentieth century located in Minho (Portugal). This study is part of master thesis of João Martins, an original research work.

Control techniques for enhancing performance of PV system under dynamic conditions

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Md Ehtesham ◽  
Majid Jamil
Keyword(s):  
Power Quality ◽  
Research Work ◽  
Environmental Parameters ◽  
Original Research ◽  
State Variables ◽  
Estimation Of Parameters ◽  
Pv System ◽  
Partial Shading ◽  
Content Type ◽  
Dynamic Conditions

Purpose The purpose of this paper is to focus on two major areas of concern for the Photovoltaic (PV) system, i.e. power quality and maximum power point tracking (MPPT). Novel control strategies have been proposed for both these issues, and their respective superiorities over the existing techniques have been established. On the other hand, as far as MPPT is concerned, two limitations are found in the available techniques. One is the inability of effective MPPT in dynamic conditions where the environmental parameters changes very rapidly. Second one is the ineffective tracking of global maxima under partial shading conditions. Design/methodology/approach Here, modified Kalman filtering approach has been applied for estimating the reference current of active power filter, incorporated for power quality improvement. The proposed Kalman algorithm introduces a weighted matrix, which advances the estimated values of state variables. This paper presents a simple and enhanced model-based (MB) MPPT algorithm that has the capability of tracking MPPT effectively in both these working conditions. The proposed MB algorithm uses the mathematical modelling, and based on precised estimation of parameters, it pre-determines the MPP analytically. Findings It has been tested successfully for dynamic variations of insolation, temperature and partial shading, where all these three parameters are rigorously varied over the full scale of practical values. The results have been also investigated experimentally and compared with the simulated one. A close matching of both the results has been shown through the plots, which validates the effectiveness of proposed algorithms. Originality/value This research paper is part of the original research work carried out in Lab. Simulated results are obtained in MATLAB/Simulink platform, whereas these are further validated experimentally on 2-KW panel constituted with all types of commercial products, namely, mono, poly and thin-film.

scholarly journals Entire functions of restricted hyper-order sharing a set of two small functions IM with their linear c-shift operators

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abhijit Banerjee ◽  
Arpita Roy
Keyword(s):  
Entire Function ◽  
Entire Functions ◽  
Shift Operator ◽  
Research Work ◽  
Original Research ◽  
Exponent Of Convergence ◽  
Content Type ◽  
Shift Operators ◽  
Small Functions ◽  
Hyper Order

PurposeThe paper aims to build the relationship between an entire function of restricted hyper-order with its linear c-shift operator.Design/methodology/approachStandard methodology for papers in difference and shift operators and value distribution theory have been used.FindingsThe relation between an entire function of restricted hyper-order with its linear c-shift operator was found under the periphery of sharing a set of two small functions IM (ignoring multiplicities) when exponent of convergence of zeros is strictly less than its order. This research work is an improvement and extension of two previous papers.Originality/valueThis is an original research work.

Viscous Dissipation Effect on a Steady Generalised Couette Flow of Heat-Generating/Absorbing Fluid in a Vertical Channel

2019 ◽  
Vol 74 (7) ◽  
pp. 605-616
Author(s):  
Abiodun O. Ajibade ◽  
Tafida M. Kabir
Keyword(s):  
Mixed Convection ◽  
Couette Flow ◽  
Viscous Dissipation ◽  
Reverse Flow ◽  
Vertical Channel ◽  
Heated Wall ◽  
Fluid Temperature ◽  
Dissipation Effect ◽  
Mixed Convection Parameter ◽  
Convection Parameter

AbstractThis article investigates the viscous dissipation effect on steady generalised Couette flow of heat-generating/absorbing fluid in a vertical channel. Equations of energy and momentum are obtained and solved using the homotopy perturbation method. The influences of the dimensionless flow parameter have been plotted graphically and discussed for varying values of the controlling parameters. During the course of computation, it is found that fluid temperature and velocity increase with an increase in viscous dissipation and also seen that growing mixed convection parameter Gre leads to a corresponding rise in temperature and velocity. It is further discovered that heat absorption leads to increase in the heat transfer on the heated wall. Finally, it is concluded that heat generation contributes to increase the mixed convection, hence, it requires decrease in mixed convection parameter to bring about a reverse flow near the stationary plate.

Mixed convection flow due to a moving vertical plate parallel to free stream under the influence of Newtonian heating and thermal radiation

2014 ◽  
Vol 5 (3) ◽  
pp. 859-870
Author(s):  
Prabhugouda Patil ◽  
S. Roy
Keyword(s):  
Prandtl Number ◽  
Mixed Convection ◽  
Thermal Radiation ◽  
Vertical Plate ◽  
Free Stream ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Newtonian Heating ◽  
Mixed Convection Parameter ◽  
Convection Parameter

The steady mixed convection flow from a moving vertical plate in a parallel free stream is considered to investigate the combined effects of buoyancy force and thermal diffusion in presence of thermal radiation as well as Newtonian heating effects. The governing boundary layer equations are transformed into a non-dimensional form by a group of non-similar transformations. The resulting system of coupled non-linear partial differential equations is solved by an implicit finite difference scheme in conjunction with the quasi-linearization technique. Computations are performed and representative set is displayed graphically to illustrate the influence of the mixed convection parameter ( ), Prandtl number (Pr), the ratio of free stream velocity to the composite reference velocity ( ) and the radiation parameter (R) on the velocity and temperature profiles. The numerical results for the local skinfriction coefficient ( ) and surface temperature ( ) are also presented. The results show that the streamwise co-ordinate  significantly influences the flow and thermal fields which indicate the importance of non-similar solutions. Also, it is observed that the increase of mixed convection parameter causes the increase in the magnitude of velocity profile about 65% for lower Prandtl number fluids (Pr=0.7), while it decreases in the temperature profile about 30%. Present results are compared with previously published work and are found to be in excellent agreement.

Investigation and modeling of lean six sigma barriers in small and medium-sized industries using hybrid ISM-SEM approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mahipal Singh ◽  
Rajeev Rathi
Keyword(s):  
Six Sigma ◽  
Structural Equation ◽  
Research Work ◽  
Lean Six Sigma ◽  
Equation Modeling ◽  
Original Research ◽  
Extensive Literature ◽  
Implementation Barriers ◽  
Interpretive Structural Modeling ◽  
Content Type

Purpose Lean six sigma (LSS) has attained a prominent position in mature organizations but small- and medium-sized enterprises (SMEs) are struggling in the proper implementation of LSS in their core business. This study aims to make a comprehensive analysis of LSS implementation barriers in SMEs so that LSS execution can be much fluent in SMEs. Design/methodology/approach This research work is carried out based on investigation of LSS barriers through extensive literature review. For validating the identified barriers, a questionnaire survey was conducted, and out of 400 samples, 260 responses received back. The collected responses are analyzed statistically and found 16 significant barriers. The finalized barriers are modeled using interpretive structural modeling (ISM) and clustered them through matrice d’impacts croisés-multiplication appliquée a un classement (MICMAC) analysis. Furthermore, to check the consistency of results, ISM-MICMAC outcomes are validated through structural equation modeling (SEM). Findings The result reveals that 16 LSS implementation barriers are finalized through expert’s opinion and validated through statistical reliability test with Cronbach’s alpha value of 0.820. The ISM model reveals that the management relevant barriers are exhibiting the leading role to influence the implementation of LSS in SMEs. Moreover, the obtained results validated through SEM are found in good agreement. Research limitations/implications During pairwise comparisons, there may be some prejudice and subjectivity as human judgments are engaged. Practical implications This study provides impetus to practitioners and consultant for the initiation of LSS in the business organization through tackling the LSS barriers as per their driving and dependence power. Originality/value In the past, limited studies had explored the LSS barriers, but a few studies analyzed the mutual relationship between barriers. No such study is reported in literature that validates the mutual interaction model of LSS barriers. Hence, this paper presents the original research work of identification and modeling of barriers associated with LSS implementation in SMEs through hybrid ISM-SEM approach.

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