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1 – 10 of over 22000Oliver Artiga, Ana Bucy, Ruo Qiu, Elaine Cramer and Marcella Raney
The purpose of this study was to determine whether combining a structured stretching program with functional movement/body position training would yield additive effects on…
Abstract
Purpose
The purpose of this study was to determine whether combining a structured stretching program with functional movement/body position training would yield additive effects on flexibility, ergonomic practices, and subjective pain levels for employees at high risk for work-related musculoskeletal disorders.
Design/methodology/approach
Nine control and 13 experimental university cleaning staff participated in a 10-week full-body stretching intervention led by undergraduate students. Experimental participants also engaged in functional movement/body position training once per week. Joint range of motion, task ergonomic form, pain level, and stretching motivation results were compared pre- and post-intervention.
Findings
Overall flexibility (+25.75 ± 3.33%) and task ergonomic form (+26.3 ± 10.5%) significantly improved and were negatively correlated with pain levels (r = −0.541 and r = −0.317, respectively). Experimental participants experienced greater improvements in shoulder (control: +16.8 ± 9.0%; experimental: +64.2 ± 11.5%) and hip (control: +31.4 ± 9.9%; experimental: +91.2 ± 19.9%) flexibility as well as in task-specific ergonomic form for vertical (control: +0.0 ± 5.3%; experimental: +35.2 ± 10.1%) and horizontal wiping (control: −4.7 ± 4.7%; experimental: +29.0 ± 7.8%). Intrinsic motivation was increased for both groups (+26.2 ± 15.4%).
Originality/value
Supplementing a workplace stretching program with functional movement/body position training has the potential to improve flexibility and decrease pain while simultaneously increasing the likelihood that cleaning staff will participate in self-directed stretching in the future. The intervention serves as a model for workplace health management and wellness-focused community building on university campuses who insource cleaning staff.
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Jian Liu, Yubo Hu and Weidong Yu
This paper studies the effects of stretching slenderization on the structure and properties of yak hair using an optical microscope, scanning electron microscope (SEM), Raman…
Abstract
This paper studies the effects of stretching slenderization on the structure and properties of yak hair using an optical microscope, scanning electron microscope (SEM), Raman spectroscopy, tensile curves and dyeability. The SEM results show that stretching slenderization can decrease the diameter of yak hair, and the scale of the fibres is elongated and thinner. As well, the structure of the fibre scale is looser after stretching, and some scale cells are damaged. The stretching process results in the structural transformation of yak hair from an α-keratin to a predominantly β-keratin crystalline structure by the Raman analysis. Through the tensile curves, the slenderizing of the yak hair at different stretching rates is analyzed. The breaking tenacity increases gradually in terms of the stretching rate and breaking elongation decreases. Optical microscope photographs and dyeing rate analysis are used to observe the changes in the dyeability of yak hair before and after the stretching. The results show that after stretching, there is a significant improvement in the dyeing properties of yak hair.
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Sima Samadpoor, Hadi Roohani Ghehsareh and Saeid Abbasbandy
The purpose of this paper is to obtain semi-analytical solutions of similarity solutions for the nano boundary layer flows with Navier boundary condition. The similarity solutions…
Abstract
Purpose
The purpose of this paper is to obtain semi-analytical solutions of similarity solutions for the nano boundary layer flows with Navier boundary condition. The similarity solutions of viscous flows over a two-dimensional stretching surface and an axisymmetric stretching surface are investigated.
Design/methodology/approach
In this work, the governing partial differential equations are transformed to a nonlinear ordinary differential equation by using some proper similarity transformations. Then an efficient semi-analytical method, the Laplace Adomian decomposition method (LADM) is applied to obtain semi-analytical solutions of the similarity solutions in both of viscous flows over a two-dimensional stretching surface and an axisymmetric stretching surface. To improve the accuracy and enlarges the convergence domain of the obtained results by the LADM, the study has combined it with Padé approximation.
Findings
Accuracy and efficiency of the presented method are illustrated and denoted through the tables and figures. Also the effects of the suction parameter λ and slip parameter K on the fluid velocity and on the tangential stress are investigated.
Originality/value
The similarity solutions of the governing partial differential equation are obtained analytically by using an efficient developed method, namely the Laplace Adomian decomposition-Padé method. The analytic solutions of nonlinear ordinary differential equation are constructed for both of viscous flows over a two-dimensional stretching surface and an axisymmetric stretching surface.
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The purpose of this paper is to study the effects of surface mass transfer on the steady mixed convection flow from a vertical stretching sheet in a parallel free stream with…
Abstract
Purpose
The purpose of this paper is to study the effects of surface mass transfer on the steady mixed convection flow from a vertical stretching sheet in a parallel free stream with variable wall temperature and concentration.
Design/methodology/approach
An implicit finite difference scheme in combination with the quasilinearisation technique is employed to obtain non‐similar solutions of the governing boundary layer equations for momentum, temperature and concentration fields.
Findings
The numerical results are reported here to display the effects of mixed convection parameter, ratio of buoyancy forces, surface mass transfer (suction and injection), the ratio of free stream velocity to the composite reference velocity, Prandtl number and Schmidt number on velocity, temperature and concentration profiles as well as on skin friction, Nusselt number and Sherwood number.
Research limitations/implications
Thermophysical properties of the fluid in the flow model are assumed to be constant except the density variations causing a body force term in the momentum equation. The Boussinesq approximation is invoked for the fluid properties to relate density changes, and to couple in this way the temperature and concentration fields to the flow field. The concentration of diffusing species is assumed to be very small in comparison with other chemical species far away from the surface. Hence the Soret and Dufour effects are neglected. The stretching sheet is assumed to be subject to a power‐law wall temperature as well as to a power‐law wall concentration, in a parallel free stream.
Practical implications
Convective heat and mass transfer over a vertical stretching sheet in a parallel stream is very important for various design of technological process are hot rolling, wire drawing, glass‐fiber paper production, both metal and polymer sheets, for instance, in cooling of an infinite metallic plate in a cooling bath, the boundary layer along material handling conveyors, etc.
Originality/value
The paper studies the combined effects of thermal and mass diffusion over a vertical stretching sheet with surface mass transfer.
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Prabhugouda Mallanagouda Patil, Geeta Hadimani, Shashikant A., P.S. Kulkarni and Mukesh Kumar
This paper aims to provide a detailed study on the influence of slip flow and thermal jump over mixed convection flow along an exponentially stretching surface. Also, impacts of…
Abstract
Purpose
This paper aims to provide a detailed study on the influence of slip flow and thermal jump over mixed convection flow along an exponentially stretching surface. Also, impacts of suction/blowing, volumetric heat source/sink and velocity ratio parameter will be studied in this analysis.
Design/methodology/approach
The modeled governing equations for the assumed problem are dimensional nonlinear partial differential equations in nature. To reduce these equations, non-similar transformations are used to get the dimensionless nonlinear partial differential equations. Then, quasi-linearization technique is used to linearize these non-dimensional nonlinear partial differential equations. Finally, an implicit finite difference scheme is used to discretize the resulting equations.
Findings
The physical explanations are provided for the variations of various non-dimensional governing parameters over the velocity and temperature profiles. Also, the effects of these dimensionless parameters on skin friction coefficient and heat transfer rate are scrutinized in a manner which highlights their physical interpretation. The detailed discussion exhibits the fact that the streamwise co-ordinate velocity ratio parameter, partial slip parameter and the thermal jump parameter have significant influence over the flow and thermal fields.
Originality/value
This work has not been reported in the literature to the authors’ best of knowledge.
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S. Das, R.R. Patra and R.N. Jana
The purpose of this study is to present the significance of Joule heating, viscous dissipation, magnetic field and slip condition on the boundary layer flow of an electrically…
Abstract
Purpose
The purpose of this study is to present the significance of Joule heating, viscous dissipation, magnetic field and slip condition on the boundary layer flow of an electrically conducting Boussinesq couple-stress fluid induced by an exponentially stretching sheet embedded in a porous medium under the effect of the magnetic field of the variable kind. The heat transfer phenomenon is accounted for under thermal radiation, Joule and viscous dissipation effects.
Design/methodology/approach
The governing nonlinear partial differential equations are transformed to the nonlinear ordinary differential equations (ODEs) by using some appropriate dimensionless variables and then the consequential nonlinear ODEs are solved numerically by making the use of the well-known shooting iteration technique along with the standard fourth-order Runge–Kutta integration scheme. The impact of emerging flow parameters on velocity and temperature profiles, streamlines, local skin friction coefficient and Nusselt number are described comprehensively through graphs and tables.
Findings
Results reveal that the velocity profile is observed to diminish considerably within the boundary layer in the presence of a magnetic field and slip condition. The enhanced radiation parameter is to decline the temperature field. The slip effect is favorable for fluid flow.
Originality/value
Till now, slip effect on Boussinesq couple-stress fluid over an exponentially stretching sheet embedded in a porous medium has not been explored. The present results are validated with the previously published study and found to be highly satisfactory.
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Andrew G. Parsons and Christoph Schumacher
The purpose of this paper is to examine the regulation of advertising by considering market‐driven firms (those seeking to keep within the boundaries set by social and industry…
Abstract
Purpose
The purpose of this paper is to examine the regulation of advertising by considering market‐driven firms (those seeking to keep within the boundaries set by social and industry norms) and market drivers (those seeking to stretch boundaries to gain a competitive advantage). Thought is also given to the costs of regulation and tolerance to the social purse, and the benefits gained by compliance and violation.
Design/methodology/approach
The authors develop a conceptual argument for boundary stretching where market drivers are present in a marketplace dominated by market‐driven firms. The authors then apply a game theory model to examine the conditions, the firm responses, and Government responses. In doing so the authors investigate incentives for non‐compliant behavior in a self‐regulated market and show that a firm can achieve a market advantage by stretching advertising boundaries.
Findings
Results suggest that when government takes a “wait‐and‐see” approach of partial tolerance, then the market driver can become the focal point for the market‐driven, and a shift will take place in the regulatory boundary. If the government is the boundary shifter then social engineers are taking advantage of artificial boundaries they know will not be enforced, with implications for campaigns such as drink‐driving, smoking, and domestic violence. Also, the market driver will gain a competitive advantage by entering a market‐driven marketplace through boundary shifts, even after incurring an initial penalty.
Research limitations/implications
The research demonstrates a need for research into marketing regulation to consider firm types, violation types, and tolerance levels. The study contributes to our understanding of marketer activity with two implications; first the firm is shifting the boundaries and redefining the market focal point as themselves, rather than violating the boundaries and setting themselves outside the rules. Second, depending on the level of tolerance that government has with the regulation of advertising, there is a cost to both the social purse and to market‐driven firms associated with boundary shifters.
Practical implications
A market driver, looking for growth opportunities, should try to enter markets dominated by market‐driven firms, and which have self‐regulation, while market driven firms should either look for regulatory protection or act collectively to wield power over third parties – for example forcing media outlets not to carry market driver advertising.
Originality/value
By introducing the concept of boundary stretching and allowing for market drivers and market driven firms, the authors show the effects of regulation (or tolerance) in a realistic setting and allow for the real‐world dynamics of a marketplace where new ideas create new focal points for social acceptance. This study also provides a clear illustration of the usefulness of game theory in marketing studies.
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M. Muthtamilselvan and A. Renuka
The purpose of this paper is to investigate the nanofluid flow and heat transfer induced by two co- axially rotating disks using Buongiorno’s model. This model took into account…
Abstract
Purpose
The purpose of this paper is to investigate the nanofluid flow and heat transfer induced by two co- axially rotating disks using Buongiorno’s model. This model took into account the Brownian diffusion and thermophoresis effects due to the presence of nanoparticles.
Design/methodology/approach
The governing partial differential equation was transformed into a set of nonlinear ordinary differential equations by using similarity transformation and solved numerically using shooting techniques.
Findings
The present work is a comparison study of Maxwell-Garnett model and modified Maxwell model for the effective thermal conductivity of nanofluids. The effects of different involved parameters on velocity and temperature profile are examined graphically. Numerical values of skin friction coefficient and Nusselt number are computed and studied.
Originality/value
It is found that the results of azimuthal velocity profile are an increasing function of upper disk stretching parameter. The radial and axial velocity profile is enlarged for a large value of lower stretching parameter. Fluid temperature decays for large values Reynolds number and lower disk stretching parameter.
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Ioan Pop, Kohi Naganthran and Roslinda Nazar
The purpose of this paper is to analyse numerically the steady stagnation-point flow of a viscous and incompressible fluid over continuously non-aligned stretching or shrinking…
Abstract
Purpose
The purpose of this paper is to analyse numerically the steady stagnation-point flow of a viscous and incompressible fluid over continuously non-aligned stretching or shrinking surface in its own plane in a water-based nanofluid which contains three different types of nanoparticles, namely, Cu, Al2O3 and TiO2.
Design/methodology/approach
Similarity transformation is used to convert the system of boundary layer equations which are in the form of partial differential equations into a system of ordinary differential equations. The system of similarity governing equations is then reduced to a system of first-order differential equations and solved numerically using the bvp4c function in Matlab software.
Findings
Unique solution exists when the surface is stretched and dual solutions exist as the surface shrunk. For the dual solutions, stability analysis has revealed that the first solution (upper branch) is stable and physically realizable, while the second solution (lower branch) is unstable. The effect of non-alignment is huge for the shrinking surface which is in contrast with the stretching surface.
Practical implications
The results obtained can be used to explain the characteristics and applications of nanofluids, which are widely used as coolants, lubricants, heat exchangers and micro-channel heat sinks. This problem also applies to some situations such as materials which are manufactured by extrusion, production of glass-fibre and shrinking balloon. In this kind of circumstance, the rate of cooling and the stretching/shrinking process play an important role in moulding the final product according to preferable features.
Originality/value
The present results are original and new for the study of fluid flow and heat transfer over a stretching/shrinking surface for the problem considered by Wang (2008) in a viscous fluid and extends to nanofluid by using the Tiwari and Das (2007) model.
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Golam Mortuja Sarkar, Suman Sarkar and Bikash Sahoo
This paper aims to theoretically and numerically investigate the steady two-dimensional (2D) Hiemenz flow with heat transfer of Reiner-Rivlin fluid over a linearly stretching…
Abstract
Purpose
This paper aims to theoretically and numerically investigate the steady two-dimensional (2D) Hiemenz flow with heat transfer of Reiner-Rivlin fluid over a linearly stretching/shrinking sheet.
Design/methodology/approach
The Navier–Stokes equations are transformed into self-similar equations using appropriate similarity transformations and then solved numerically by using shooting technique. A simple but effective mathematical analysis has been used to prove the existence of a solution for stretching case (λ> 0). Moreover, an attempt has been laid to carry the asymptotic solution behavior for large stretching. The obtained asymptotic solutions are compared with direct numerical solutions, and the comparison is quite remarkable.
Findings
It is observed that the self-similar equations exhibit dual solutions within the range [λc, −1] of shrinking parameter λ, where λc is the turning point from where the dual solutions bifurcate. Unique solution is found for all stretching case (λ > 0). It is noticed that the effects of cross-viscous parameter L and shrinking parameter λ on velocity and thermal fields show opposite character in the dual solution branches. Thus, a linear temporal stability analysis is performed to determine the basic feasible solution. The stability analysis is based on the sign of the smallest eigenvalue, where positive or negative sign leading to a stable or unstable solution. The stability analysis reveals that the first solution is stable that describes the main flow. Increase in cross-viscous parameter L resulting in a significant increment in skin friction coefficient, local Nusselt number and dual solutions domain.
Originality/value
This work’s originality is to examine the combined effects of cross-viscous parameter and stretching/shrinking parameter on skin friction coefficient, local Nusselt number, velocity and temperature profiles of Hiemenz flow over a stretching/shrinking sheet. Although many studies on viscous fluid and nanofluid have been investigated in this field, there are still limited discoveries on non-Newtonian fluids. The obtained results can be used as a benchmark for future studies of higher-grade non-Newtonian flows with several physical aspects. All the generated results are claimed to be novel and have not been published elsewhere.
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