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Article
Publication date: 1 April 1991

S. RAKHEJA and A.K.W. AHMED

A local equivalent linearization methodology is proposed to simulate non‐linear shock absorbers and dual‐phase dampers in the convenient frequency domain. The methodology…

Abstract

A local equivalent linearization methodology is proposed to simulate non‐linear shock absorbers and dual‐phase dampers in the convenient frequency domain. The methodology based on principle of energy similarity, characterizes the non‐linear dual‐phase dampers via an array of local damping constants as function of local excitation frequency and amplitude, response, and type of non‐linearity. The non‐linear behaviour of the dual‐phase dampers can thus be predicted quite accurately in the entire frequency range. The frequency response characteristics of a vehicle model employing non‐linear dual‐phase dampers, evaluated using local linearization algorithm, are compared to those of the non‐linear system, established via numerical integration, to demonstrate the effectiveness of the algorithm. An error analysis is performed to quantify the maximum error between the damping forces generated by non‐linear and locally linear simulations. The influence of damper parameters on the ride improvement potentials of dual‐phase dampers is further evaluated using the proposed methodology and discussed.

Details

Engineering Computations, vol. 8 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 4 March 2020

B. Mahanthesh

The magnetohydrodynamic (MHD) flow problems are important in the field of biomedical applications such as magnetic resonance imaging, inductive heat treatment of tumours…

Abstract

Purpose

The magnetohydrodynamic (MHD) flow problems are important in the field of biomedical applications such as magnetic resonance imaging, inductive heat treatment of tumours, MHD-derived biomedical sensors, micropumps for drug delivery, MHD micromixers, magnetorelaxometry and actuators. Therefore, there is the impact of the magnetic field on the transport of non-Newtonian Carreau fluid in the presence of binary chemical reaction and activation energy over an extendable surface having a variable thickness. The significance of irregular heat source/sink and cross-diffusion effects is also explored.

Design/methodology/approach

The leading governing equations are constructed by retaining the effects of binary chemical reaction and activation energy. Suitable similarity transformations are used to transform the governing partial differential equations into ordinary differential equations. Subsequent nonlinear two-point boundary value problem is treated numerically by using the shooting method based on Runge–Kutta–Fehlberg. Graphical results are presented to analyze the behaviour of effective parameters involved in the problem. The numerical values of the mass transfer rate (Sherwood number) and heat transfer rate (Nusselt number) are also calculated. Furthermore, the slope of the linear regression line through the data points is determined in order to quantify the outcome.

Findings

It is established that the external magnetic field restricts the flow strongly and serves as a potential control mechanism. It can be concluded that an applied magnetic field will play a major role in applications like micropumps, actuators and biomedical sensors. The heat transfer rate is enhanced due to Arrhenius activation energy mechanism. The boundary layer thickness is suppressed by strengthening the thickness of the sheet, resulting in higher values of Nusselt and Sherwood numbers.

Originality/value

The effects of magnetic field, binary chemical reaction and activation energy on heat and mass transfer of non-Newtonian Carreau liquid over an extendable surface with variable thickness are investigated for the first time.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 5
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 7 March 2016

Yajun Leng, Qing Lu and Changyong Liang

Collaborative recommender systems play a crucial role in providing personalized services to online consumers. Most online shopping sites and many other applications now…

Abstract

Purpose

Collaborative recommender systems play a crucial role in providing personalized services to online consumers. Most online shopping sites and many other applications now use the collaborative recommender systems. The measurement of the similarity plays a fundamental role in collaborative recommender systems. Some of the most well-known similarity measures are: Pearson’s correlation coefficient, cosine similarity and mean squared differences. However, due to data sparsity, accuracy of the above similarity measures decreases, which makes the formation of inaccurate neighborhood, thereby resulting in poor recommendations. The purpose of this paper is to propose a novel similarity measure based on potential field.

Design/methodology/approach

The proposed approach constructs a dense matrix: user-user potential matrix, and uses this matrix to compute potential similarities between users. Then the potential similarities are modified based on users’ preliminary neighborhoods, and k users with the highest modified similarity values are selected as the active user’s nearest neighbors. Compared to the rating matrix, the potential matrix is much denser. Thus, the sparsity problem can be efficiently alleviated. The similarity modification scheme considers the number of common neighbors of two users, which can further improve the accuracy of similarity computation.

Findings

Experimental results show that the proposed approach is superior to the traditional similarity measures.

Originality/value

The research highlights of this paper are as follows: the authors construct a dense matrix: user-user potential matrix, and use this matrix to compute potential similarities between users; the potential similarities are modified based on users’ preliminary neighborhoods, and k users with the highest modified similarity values are selected as the active user’s nearest neighbors; and the proposed approach performs better than the traditional similarity measures. The manuscript will be of particular interests to the scientists interested in recommender systems research as well as to readers interested in solution of related complex practical engineering problems.

Details

Kybernetes, vol. 45 no. 3
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 13 May 2021

Saeed Dinarvand, Seyed Mehdi Mousavi, Mohammad Yousefi and Mohammadreza Nademi Rostami

The purpose of this paper is to study the steady laminar magnetohydrodynamics (MHD) flow of a magnesium oxide-silver/water hybrid nanofluid along a horizontal slim needle…

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Abstract

Purpose

The purpose of this paper is to study the steady laminar magnetohydrodynamics (MHD) flow of a magnesium oxide-silver/water hybrid nanofluid along a horizontal slim needle with thermal radiation by considering dual solutions.

Design/methodology/approach

It is assumed that the needle can move in the same or opposite direction of the free stream. Also the solid phase and fluid phase are in thermal equilibrium. The basic partial differential equations become dimensionless using a similarity transformation method. Moreover, problem coding is accomplished using the finite difference method. The emerging parameters are nanoparticles mass (0–40 gr), base fluid mass (100 gr), needle’s size (0.001–0.2), magnetic field parameter, velocity ratio parameter, radiation parameter and Prandtl number (6.2).

Findings

With help of the stability analysis, it is shown that always the first solutions are physically stable. Results indicate that the magnetic parameter and the second nanoparticle’s mass limit the range of the velocity ratio parameter for which the solution exists. Besides, the magnetic parameter leads to decrease of quantities of engineering interest, i.e. skin friction coefficient and local Nusselt number.

Originality/value

To the best of the authors’ knowledge, no one has ever attempted to study the present problem through a mass-based model for hybrid nanofluid. Moreover, the dual solutions for the problem are new. Indeed, the results of this paper are purely original and the numerical achievements were never published up to now. Finally, the authors expect that the present investigation would be useful in hot-wire anemometer or shielded thermocouple for measuring the velocity of the wind, etc.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 3 April 2009

Daniel Castro‐Lacouture and Kathy O. Roper

This research seeks to investigate sources of renewable energy into the everyday operation of federally owned facilities. The goal is to present comparisons of existing US…

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1787

Abstract

Purpose

This research seeks to investigate sources of renewable energy into the everyday operation of federally owned facilities. The goal is to present comparisons of existing US federal buildings and analyze the savings and methodologies for acceptance of each project for the use of building and project managers within the US federal government or other researchers interested in similar analysis.

Design/methodology/approach

Data were analyzed on several case studies where solar, wind, and geothermal sources of renewable energy have already been integrated in federally owned facilities. The analysis focused on cost due to available data and resources, and its scope was to estimate the potential for success or failure and possible outcomes.

Findings

Current case studies of solar, wind, and geothermal projects within the US federal government suggest that cost savings are not the sole reason for adopting such technologies. Projects move forward based on additional motivations such as reduced environmental impact, government policy, and in an effort to increase leadership, awareness, and image.

Research limitations/implications

A larger number of case studies are needed to infer trends in federal renewable energy projects. The methodology is aimed at an objective comparison of electricity costs between buildings; however, as the findings demonstrate, the quantitative normalized ratio implemented needs other soft considerations to fully represent renewable energy scenarios in US federal buildings.

Practical implications

Key decisions that must be made in order to get a renewable energy‐building project completed may be facilitated by using the paper and its implications of the need for soft factors to become part of the analysis.

Originality/value

The analysis presented here includes five stages or key decisions that must be made to get a renewable energy project in US federal facilities to award, including criteria beyond economics. Findings support the need for inclusion of soft factors, along with economic considerations for project success.

Details

Facilities, vol. 27 no. 5/6
Type: Research Article
ISSN: 0263-2772

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Article
Publication date: 27 September 2021

Ioan Pop, Mohammadreza Nademi Rostami and Saeed Dinarvand

The purpose of this article is to study the steady laminar magnetohydrodynamics mixed convection stagnation-point flow of an alumina-graphene/water hybrid nanofluid with…

Abstract

Purpose

The purpose of this article is to study the steady laminar magnetohydrodynamics mixed convection stagnation-point flow of an alumina-graphene/water hybrid nanofluid with spherical nanoparticles over a vertical permeable plate with focus on dual similarity solutions.

Design/methodology/approach

The single-phase hybrid nanofluid modeling is based on nanoparticles and base fluid masses instead of volume fraction of first and second nanoparticles as inputs. After substituting pertinent similarity variables into the basic partial differential equations governing on the problem, the authors obtain a complicated system of nondimensional ordinary differential equations, which has non-unique solution in a certain range of the buoyancy parameter. It is worth mentioning that, the stability analysis of the solutions is also presented and it is shown that always the first solutions are stable and physically realizable.

Findings

It is proved that the magnetic parameter and the wall permeability parameter widen the range of the buoyancy parameter for which the solution exists; however, the opposite trend is valid for second nanoparticle mass. Besides, mass suction at the surface of the plate as well as magnetic parameter leads to reduce both hydrodynamic and thermal boundary layer thicknesses. Moreover, the assisting flow regime always has higher values of similarity skin friction and Nusselt number relative to opposing flow regime.

Originality/value

A novel mass-based model of the hybridity in nanofluids has been used to study the foregoing problem with focus on dual similarity solutions. The results of this paper are completely original and, to the best of the authors’ knowledge, the numerical results of the present paper were never published by any researcher.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 11
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 July 2005

Josip Stepanić, Gabrijela Sabol and Mislav Stjepan Žebec

Constant question in determination of a social system state is how to obtain a sufficient quantity of information with a small enough, manageable indicator set.

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798

Abstract

Purpose

Constant question in determination of a social system state is how to obtain a sufficient quantity of information with a small enough, manageable indicator set.

Design/methodology/approach

The concept is developed in a thorough analysis of strengths and weaknesses of existing approaches, and in thorough contrasting the proposed solutions with these.

Findings

The social free energy and social entropy overcome the gap between the meta‐theoretically founded quantities and indicators related to social system state description. The social free energy measures the totality of resources used for social system preservation during changes in environment. The social entropy measures the number of different realisations of a particular state.

Practical implications

Combination of social free energy and social entropy is on the one hand a set of quantities easily determinable from available data, and on the other hand a set of indicators intuitively connected with social system states. We relate the system social free energy and levels of organisation and adaptation. From these measures we derive the measure of social system adaptation.

Originality/value

The use of social free energy in describing the social system states adds a significant value in forming the small set of representative indicators. It is of importance for all researchers; theoreticians and practitioners.

Details

Kybernetes, vol. 34 no. 6
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 23 June 2020

M. Gnaneswara Reddy, P. Vijaya Kumari, G. Upender Reddy, K. Ganesh Kumar and B. C. Prasannakumara

The main theme of this paper is the effect of viscous dissipation Darcy–Forchheimer flow and heat transfer augmentation of a viscoelastic fluid over an incessant moving needle.

Abstract

Purpose

The main theme of this paper is the effect of viscous dissipation Darcy–Forchheimer flow and heat transfer augmentation of a viscoelastic fluid over an incessant moving needle.

Design/methodology/approach

The governing partial differential equations of the current problem are diminished into a set of ordinary differential equations using requisite similarity transformations. Energy equation is extended by using Cattaneo–Christov heat flux model with variable thermal conductivity. By applying boundary layer approximation system of equations is framed.

Findings

Convective condition is also introduced in this analysis. Obtained set of similarity equations are then solved with the help of efficient numerical method four–fifth-order RKF-45.

Originality/value

The outcomes of various pertinent parameters on the velocity, temperature distributions are analysed by using portraits.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 29 March 2011

Xianqiang Zhu and Zhenfeng Shao

The purpose of this paper is to analyze the spectrum influence between radon transform and log‐polar transform when rotation and scale effect is eliminated. The average…

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1388

Abstract

Purpose

The purpose of this paper is to analyze the spectrum influence between radon transform and log‐polar transform when rotation and scale effect is eliminated. The average retrieval performance of wavelet and NSCT with different retrieval parameters is also studied.

Design/methodology/approach

The authors designed a multi‐scale and multi‐orientation texture transform spectrum, as well as rotation‐invariant feature vector and its measurement criteria. Then a new two‐level coarse‐to‐fine rotation and scale‐invariant texture retrieval algorithm based on no‐parameter statistic features was proposed. Experiments on VisTex texture database show that the algorithm proposed in this paper is appropriate for main orientation capturing and detail information description.

Findings

According to the experiments results, it was found that the combination of this two‐level progressive retrieval strategy and multi‐scale analysis method can effectively improve retrieval efficiency compared with traditional algorithms and ensure a high precision as well.

Originality/value

The paper presents a novel algorithm for rotation and scale‐invariant texture retrieval.

Details

Sensor Review, vol. 31 no. 2
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 29 October 2019

Petra Eriksson, Vlatko Milić and Tor Brostrom

Energy use in buildings needs to be reduced to meet political goals; however, reducing energy use can conflict with heritage preservation objectives. The purpose of this…

Abstract

Purpose

Energy use in buildings needs to be reduced to meet political goals; however, reducing energy use can conflict with heritage preservation objectives. The purpose of this paper is to demonstrate a method that combines quantitative and qualitative analyses of the potential of energy savings in an historic building stock. Specifically, this study examines how requirements of historic building preservation affect the energy saving potential on a building stock level.

Design/methodology/approach

Using the World Heritage Town of Visby, Sweden as a case study, this paper illustrates a step-by-step method as a basis for implementing energy savings techniques in an historic building stock. The method contains the following steps: categorisation of a building stock, definition of restriction levels for energy renovation scenarios and life cycle costs optimisation of energy measures in archetype buildings representing the building stock. Finally, this study analyses how different energy renovation strategies will impact heritage values and energy saving potentials for different categories of buildings.

Findings

The outcome of the study is twofold: first, the method has been tested and proven useful and second, the results from the application of the method have been used to formulate differentiated energy renovation strategies for the case study.

Originality/value

The study shows that it is possible to integrate techno-economic analysis with assessment of heritage values in a given building stock in order to facilitate a strategic discussion balancing policies and targets for energy savings with policies for the preservation of heritage values. The findings will contribute to sounder policy development and planning for historic building stocks.

Details

International Journal of Building Pathology and Adaptation, vol. 38 no. 2
Type: Research Article
ISSN: 2398-4708

Keywords

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