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This paper examines, based on certain criteria, the most feasible sustainable energy technology (SET) for rural Bangladesh. The criteria used for the appropriateness of SET for rural Bangladesh are: (a) availability of energy resources, (b) degree of technological complexity of the proposed technology, (c) cost effectiveness, (d) balance between supply of and demand for energy, (e) contribution of the particular energy technology to reducing greenhouse gas emission, and (f) major constraints associated with accepting the recommended technology. The paper describes the theoretical part of the author's Ph.D. thesis where fundamental work has been done. The study applies the criteria to three main energy technologies‐ biomass, solar and wind‐ and finds that none of these technologies are suitable on their own. However, among the three proposed energy technologies, biomass might be the best possible option which can make a positive contribution to alleviate energy poverty in rural Bangladesh. Findings of this study are useful for development policy makers and researchers.

The purpose of this paper is to consider steady two‐dimensional mixed convection flow along a vertical semi‐infinite power‐law stretching sheet. The velocity and temperature of the sheet are assumed to vary in a power‐law form.

The problem is formulated in terms of non‐similar equations. These equations are solved numerically by an efficient implicit, iterative, finite‐difference method in combination with a quasi‐linearization technique.

It was found that the skin‐friction coefficient increased with the ratio of free‐stream velocity to the composite reference velocity and the buoyancy parameter while it decreased with exponent parameter. The heat transfer rate increased with the Prandtl number, buoyancy parameter and the exponent parameter.

A very useful source of information for researchers on the subject of convective flow over stretching sheets.

This paper illustrates mixed convective flow over a power‐law stretched surface with variable wall temperature.

This paper aims to assess the effectiveness of Hall currents and power-law slip condition on the hydromagnetic convective flow of an electrically conducting power-law fluid over an exponentially stretching sheet under the effect of a strong variable magnetic field and thermal radiation. Flow formation is developed using the rheological expression of a power-law fluid.

The nonlinear partial differential equations describing the flow are transformed into the nonlinear ordinary differential equations by employing the local similarity transformations and then solved numerically by an effective numerical approach, namely, fourth-order Runge–Kutta integration scheme, along with the shooting iteration technique. The numerical solution is computed for different parameters by using the computational software MATLAB bvp4c. The bvp4c function uses the finite difference code as the default. This method is a fourth-order collocation method. The impacts of thermophysical parameters on velocity and temperature distributions, skin friction coefficients and Nusselt number in the boundary layer regime are exhibited through graphs and tables and deliberated with proper physical justification.

Our investigation conveys that Hall current has an enhancing behavior on velocity profiles and reduces skin friction coefficients. An increase in the power-law index is observed to deplete velocity and temperature evolution. The temperature for the pseudo-plastic (shear-thinning) fluid is relatively higher than the corresponding temperature of the dilatant (shear-thickening) fluid. The streamlines are more distorted and have low intensity near the surface of the sheet for the dilatant fluid than the pseudo-plastic fluid.

The study is pertinent to the expulsion of polymer sheet and photographic films, hydrometallurgical industry, electrically conducting polymer dynamics, magnetic material processing, solutions and melts of polymer processing, purification of molten metals from nonmetallic. The results obtained in this work can be relevant in fluid mechanics and heat transfer applications.

The present problem has, to the authors' knowledge, not communicated thus far in the scientific literature. A comparative study with the published works is conducted to verify the accuracy of the present study. The results obtained in this analysis are significant in providing the standards for validating the accuracies of some numerical or empirical methods.

The purpose of the present paper is to model a cavity, which is equally divided vertically by a thin, flexible membrane. The membranes are inevitable components of many engineering devices such as distillation systems and fuel cells. In the present study, a cavity which is equally divided vertically by a thin, flexible membrane is model using the fluid–structure interaction (FSI) associated with a moving grid approach.

The cavity is differentially heated by a sinusoidal time-varying temperature on the left vertical wall, while the right vertical wall is cooled isothermally. There is no thermal diffusion from the upper and lower boundaries. The finite-element Galerkin technique with the aid of an arbitrary Lagrangian–Eulerian procedure is followed in the numerical procedure. The governing equations are transformed into non-dimensional forms to generalize the solution.

The effects of four pertinent parameters are investigated, i.e., Rayleigh number (104 = Ra = 107), elasticity modulus (5 × 1012 = E_T = 1016), Prandtl number (0.7 = Pr = 200) and temperature oscillation frequency (2p = f = 240p). The outcomes show that the temperature frequency does not induce a notable effect on the mean values of the Nusselt number and the deformation of the flexible membrane. The convective heat transfer and the stretching of the thin, flexible membrane become higher with a fluid of a higher Prandtl number or with a partition of a lower elasticity modulus.

The authors believe that the modeling of natural convection and heat transfer in a cavity with the deformable membrane and oscillating wall heating is a new subject and the results have not been published elsewhere.

This study aims to investigate the structural, mechanical, thermal and electrical properties of tin–silver–nickel (Sn-Ag-Ni) melt-spun solder alloys. So, it aims to improve the mechanical properties of the eutectic tin–silver (Sn-Ag) such as tensile strength, plasticity and creep resistance by adding different concentrations of Ni content.

Ternary melt-spun Sn-Ag-Ni alloys were investigated using x-ray diffractions, scanning electron microscope, dynamic resonance technique (DRT), Instron machine, Vickers hardness tester and differential scanning calorimetry.

The results revealed that the Ni additions 0.1, 0.3, 0.5, 0.7, 1, 3 and 5 Wt.% to the eutectic Sn-Ag melt-spun solder were added. The “0.3wt.%” of Ni was significantly improved its mechanical properties to efficiently serve under high strain rate applications. Moreover, the uniform distribution of Ag₃Sn intermetallic compound with “0.3wt.%” of Ni offered the potential benefits, such as high strength, good plasticity consequently and good mechanical performance through a lack of dislocations and microvoids. The tensile results showed improvement in 17.63 per cent tensile strength (26 MPa), 21 per cent toughness (1001 J/m³), 22.83 per cent critical shear stress (25.074 MPa) and 11 per cent thermal diffusivity (2.065 × 10⁻⁷ m²/s) when compared with the tensile strength (21.416 MPa), toughness (790 J/m³), critical shear stress (19.348 MPa) and thermal diffusivity (1.487 × 10⁻⁷ m²/s) of the eutectic Sn-Ag. Slight increments have been shown for the melting temperature of Sn_96.2-Ag_3.5-Ni_0.3 (222.62°C) and electrical resistivity to (1.612 × 10⁻⁷ Ω.m). It can be said that the eutectic Sn-Ag solder alloy has been mechanically improved with “0.3wt.%” of Ni to become a suitable alloy for high strain rate applications. The dislocation movement deformation mechanism (n = 4.5) without Ni additions changed to grain boundary sliding deformation mechanism (n = 3.5) with Ni additions. On the other hand, the elastic modulus, creep rate and strain rate sensitivity with “0.3wt.%” of Ni have been decreased. The optimum Ni-doped concentration is “0.7wt.%” of Ni in terms of refined microstructure, electrical resistivity, Young’s Modulus, bulk modulus, shear modulus, thermal diffusivity, maximum shear stress, tensile strength and average creep rate.

This study provides nickel effects on the structural of the eutectic Sn-Ag rapidly solidified by melt-spinning technique. In this paper, the authors have compared the elastic modulus of the melt-spun compositions which has been resulted from the tensile strength tester with these results from the DRT for the first time to best of the authors’ knowledge. This paper presents new improvements in mechanical and electrical performance.

The purpose of this paper is to examine e-service quality (E-SQ) of online shopping in Pakistan using “E-S-QUAL scale.” Moreover, in this study, the relationship of E-SQ with e-customer satisfaction (E-CS) and e-customer loyalty (E-CL) has been studied.

Following a quantitative research methodology, data were collected from 298 respondents using convenience sampling and survey research design was followed. In order to develop the model and test the hypotheses, structure equation modeling (SEM) was done through AMOS.

Findings indicate that all of the first latent constructs are significant where E-CS and E-CL (dependent variables) are influenced by E-SQ (independent variable). Using SEM, statistically fit structural model was developed on the basis of confirmatory factor analysis. The analysis shows that there is a strong positive relation between E-SQ and E-CS and E-SQ and E-CL.

Asian markets have been identified as the fastest growing e-commerce markets in present era. Similarly, retail sector in Pakistan is booming, at the same time an exponential increase is being observed in the number of internet users and online shopping. It is important for marketers and retailers to explore new horizons and enter the age of e-commerce for expansion of their businesses.

The increasingly wide use of the internet is influencing everything around the globe and these emerging e-commerce trends have tremendously changed the mode of shopping from brick and mortars to e-stores. The study explores the e-commerce and focuses on E-SQ and its impact on E-CS and E-CL in the context of a developing economy, i.e. Pakistan, uncovering the key dimensions and attributes.

This paper aims to explore netizen’s opinions on cryptocurrency under the lens of emotion theory and lexicon sentiments analysis via machine learning.

An automated Web-scrapping via RStudio is performed to collect the data of 15,000 tweets on cryptocurrency. Sentiment lexicon analysis is done via machine learning to evaluate the emotion score of the sample. The types of emotion tested are anger, anticipation, disgust, fear, joy, sadness, surprise, trust and the two primary sentiments, i.e. negative and positive.

The supervised machine learning discovers a total score of 53,077 sentiments from the sampled 15,000 tweets. This score is from the artificial intelligence evaluation of eight emotions, i.e. anger (2%), anticipation (18%), disgust (1%), fear (3%), joy (15%), sadness (3%), surprise (7%), trust (15%) and the two sentiments, i.e. negative (4%) and positive (33%). The result indicates that the sample primarily contains positive sentiments. This finding is theoretically significant to measure the emotion theory on the sampled tweets that can best explain the social implications of the cryptocurrency phenomenon.

This work is limited to evaluate the sampled tweets’ sentiment scores to explain the social implication of cryptocurrency.

The finding is necessary to explain the recent phenomenon of cryptocurrency. The positive sentiment may describe the increase in investment in the decentralised finance market. Meanwhile, the anticipation emotion may illustrate the public’s reaction to the bubble prices of cryptocurrencies.

Previous studies find that the social signals, e.g. word-of-mouth, netizens’ opinions, among others, affect the cryptocurrencies’ movement prices. This paper helps explain the social implications of such dynamic of pricing via sentiment analysis.

This study contributes to theoretically explain the implications of the cryptocurrency phenomenon under the emotion theory. Specifically, this study shows how supervised machine learning can measure the emotion theory from data tweets to explain the implications of cryptocurrencies.

The purpose of this study is to analyze the impact of chemical reaction and thermal radiation on mixed convection flow, heat and mass transfer characteristics of nanofluid through a wedge occupied with water–TiO₂ and water–Al₂O₃ made nanofluid by considering velocity, temperature and concentration slip conditions in present investigation.

Using acceptable similarity transformations, the prevailing partial differential equations have been altered into non-linear ordinary differential equations and are demonstrated by the diverse thermophysical parameters. The mathematical model is solved numerically by implementing Galarkin finite element method and the outcomes are shown in tables and graphs.

The temperature and concentration fields impede as magnetic field parameter improves in both water–Al₂O₃ and water–TiO₂ nanofluid. While there is contradiction in the velocity field as the values of magnetic field parameter rises in both nanofluids. The non-dimensional velocity rate, rate of temperature and rate of concentration rise with improved values of Weissenberg number.

Nanofluid flows past wedge-shaped geometries have gained much consideration because of their extensive range of applications in engineering and science, such as, magnetohydrodynamics, crude oil extraction, heat exchangers, aerodynamics and geothermal systems. Virtually, these types of nanofluid flows happen in ground water pollution, aerodynamics, retrieval of oil, packed bed reactors and geothermal industries.

This paper aims to peruse the influence of second law analysis for electrically conducting fluid of a Casson nanofluid over a wedge. For activation energy, a modified Arrhenius function is used.

The highly non-linear governing equations are developed using similarity transformations and then computed numerically via Keller–Box method.

The influences of emerging parameters on velocity, temperature distribution and concentration of nanoparticle are explained and presented via graphs and tables. Also, the behavior of fluid flow is investigated through the coefficient of skin friction, Nusselt and Sherwood numbers. Results reveal that the velocity profile enhances due to increasing Casson parameter and magnetic parameter, whereas the temperature distribution and concentration of nanoparticle decrease with larger vales of Casson parameter. It is inspected that the concentration boundary layer increases due to activation energy and decreases due to reaction rate and temperature differences.

The authors believe that all the numerical results are original and significant which are used in biomedicine, industrial, electronics and transportation. The results have not been considered elsewhere.

The purpose of this paper is to predict the effects of magnetic field, heat and mass transfer and rotation on the peristaltic flow of an incompressible Newtonian fluid in a channel with compliant walls. The whole system is in a rotating frame of reference.

The governing equations of two-dimensional fluid have been simplified under long wavelength and low Reynolds number approximation. The solutions are carried out for the stream function, temperature, concentration field, velocity and heat transfer coefficient.

The results indicate that the effects of permeability, magnetic field and rotation are very pronounced in the phenomena. Impacts of various involved parameters appearing in the solutions are carefully analyzed.

The effect of the concentration distribution, heat and mass transfer and rotation on the wave frame is analyzed theoretically and computed numerically. Numerical results are given and illustrated graphically in each case considered. A comparison was made with the results obtained in the presence and absence of rotation, magnetic field and heat and mass transfer.