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Article
Publication date: 1 February 2000

A.N. Pavlov, S.S. Sazhin, R.P. Fedorenko and M.R. Heikal

Detailed results of numerical calculations of transient, 2D incompressible flow around and in the wake of a square prism at Re = 100, 200 and 500 are presented. An…

Abstract

Detailed results of numerical calculations of transient, 2D incompressible flow around and in the wake of a square prism at Re = 100, 200 and 500 are presented. An implicit finite‐difference operator‐splitting method, a version of the known SIMPLEC‐like method on a staggered grid, is described. Appropriate theoretical results are presented. The method has second‐order accuracy in space, conserving mass, momentum and kinetic energy. A new modification of the multigrid method is employed to solve the elliptic pressure problem. Calculations are performed on a sequence of spatial grids with up to 401 × 321 grid points, at sequentially halved time steps to ensure grid‐independent results. Three types of flow are shown to exist at Re = 500: a steady‐state unstable flow and two which are transient, fully periodic and asymmetric about the centre line but mirror symmetric to each other. Discrete frequency spectra of drag and lift coefficients are presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 10 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 28 October 2014

Alexander Zemliak

The purpose of this paper is to define the process of analog circuit optimization on the basis of the control theory application. This approach produces many different…

Abstract

Purpose

The purpose of this paper is to define the process of analog circuit optimization on the basis of the control theory application. This approach produces many different strategies of optimization and determines the problem of searching of the best strategy in sense of minimal computer time. The determining of the best strategy of optimization and a searching of possible structure of this strategy with a minimal computer time is a principal aim of this work.

Design/methodology/approach

Different kinds of strategies for circuit optimization have been evaluated from the point of view of operations’ number. The generalized methodology for the optimization of analog circuit was formulated by means of the optimum control theory. The main equations for this methodology were elaborated. These equations include the special control functions that are introduced artificially. This approach generalizes the problem and generates an infinite number of different strategies of optimization. A problem of construction of the best algorithm of optimization is defined as a typical problem of the control theory. Numerical results show the possibility of application of this approach for optimization of electronic circuits and demonstrate the efficiency and perspective of the proposed methodology.

Findings

Examples show that the better optimization strategies that are appeared in limits of developed approach have a significant time gain with respect to the traditional strategy. The time gain increases when the size and the complexity of the optimized circuit are increasing. An additional acceleration effect was used to improve the properties of presented optimization process.

Originality/value

The obtained results show the perspectives of new approach for circuit optimization. A large set of various strategies of circuit optimization serves as a basis for searching the better strategies with a minimum computer time. The gain in processor time for the best strategy reaches till several thousands in comparison with traditional approach.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 17 September 2008

Mehdi Dehghan and Akbar Mohebbi

The purpose of this paper is to introduce efficient methods for solving the 2D biharmonic equation with Dirichlet boundary conditions of second kind. This equation…

Abstract

Purpose

The purpose of this paper is to introduce efficient methods for solving the 2D biharmonic equation with Dirichlet boundary conditions of second kind. This equation describes the deflection of loaded plate with boundary conditions of simply supported plate kind. Also it can be derived from the calculus of variations combined with the variational principle of minimum potential energy. Because of existing fourth derivatives in this equation, introducing high‐order accurate methods need to use artificial points. Also solving the resulted linear system of equations suffers from slow convergence when iterative methods are used. This paper aims to introduce efficient methods to overcome these problems.

Design/methodology/approach

The paper considers several compact finite difference approximations that are derived on a nine‐point compact stencil using the values of the solution and its second derivatives as the unknowns. In these approximations there is no need to define special formulas near the boundaries and boundary conditions can be incorporated with these techniques. Several iterative linear systems solvers such as Krylov subspace and multigrid methods and their combination (with suitable preconditioner) have been developed to compare the efficiency of each method and to design powerful solvers.

Findings

The paper finds that the combination of compact finite difference schemes with multigrid method and Krylov iteration methods preconditioned by multigrid have excellent results for the second biharmonic equation, and that Krylov iteration methods preconditioned by multigrid are the most efficient methods.

Originality/value

The paper is of value in presenting, via some tables and figures, some numerical experiments which resulted from applying new methods on several test problems, and making comparison with conventional methods.

Details

Kybernetes, vol. 37 no. 8
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 4 January 2016

Sajjad Miran and Chang Hyun Sohn

– The purpose of this paper is to focus on the variation of wake structures and aerodynamic forces with changes in the cylinder corner radius and orientation.

Abstract

Purpose

The purpose of this paper is to focus on the variation of wake structures and aerodynamic forces with changes in the cylinder corner radius and orientation.

Design/methodology/approach

Numerical simulations were performed for flow past a square cylinder with different corner radii placed at an angle to the incoming flow. In the present study, the rounded corner ratio R/D=0 (square cylinder), 0.1, 0.2, 0.3, and 0.4 (where R is the corner radius and D is the characteristic dimension of the body) and the angle of incidence α in the range of 0°-45° were considered.

Findings

The numerical model was validated by comparing the present results with results in the available literature, and they were found to be in good agreement. The critical incidence angle for the rounded corner cylinder – corresponding to the minimum mean drag coefficient (C D ), the minimum root mean square value of the lift coefficient C L,RMS), and the maximum Strouhal number – shifted to a lower incidence angle compared with the sharp corner square cylinder. The minimum drag and lift coefficient at R/D=0 were observed for the critical incidence angle αcri=12°, whereas for R/D=0.1-0.4, the minimum drag and lift coefficient were found to be within the range of 5°-10° for α.

Originality/value

The presented results shows the importance of the incidence angle and rounded corners of the square cylinder for reduction of aerodynamic forces. The two parameters support the shear layer flow reattachment on the lateral surface of the cylinder, have a strong correlation with the reduction of the wake width, and hence reduced the values of C D and C L .

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 5 May 2015

Sajjad Miran and Chang Hyun Sohn

– The purpose of this paper is to numerically investigate the influence of corner radius on flow past a square cylinder at a Reynolds number 500.

Abstract

Purpose

The purpose of this paper is to numerically investigate the influence of corner radius on flow past a square cylinder at a Reynolds number 500.

Design/methodology/approach

Six models were studied, for R/D=0 (square cylinder), 0.1, 0.2, 0.3, 0.4, and 0.5 (circular cylinder), where R is the corner radius and D is the characteristic dimension of the body. The transient two-dimensional (2D) laminar and large eddy simulations (LES) models were employed using finite volume code. The Strouhal number, mean drag coefficient (CD), and root mean square (RMS) value of lift coefficient (CL,RMS), for different R/D values, were computed and compared with experimental and other numerical results.

Findings

The computational results showed good agreement with previously published results for a Reynolds number, Re=500. It was found that the corner effect on a square cylinder greatly influences the flow characteristics around the cylinder. Results indicate that, as the corner radius ratio, R/D, increases, the Strouhal number increases rapidly for R/D=0-0.2, and then gradually rises between R/D=0.2 and 0.5. The minimum values of the mean drag coefficient and the RMS value of lift coefficient were found around R/D=0.2, which is verified by the time averaged streamwise velocity deficit profile.

Originality/value

On the basis of the numerical results, it is concluded that rounded corners on a square cylinder are useful in reducing the drag and lift forces generated behind a cylinder. Finally, it is suggested that with a rounded corner ratio of around R/D=0.2, the drag and oscillation of the cylinder can be greatly reduced, as compared to circular and square cylinders.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 25 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 28 August 2019

Anouk de Regt, Matteo Montecchi and Sarah Lord Ferguson

Diffusion of fake news and pseudo-facts is becoming increasingly fast-paced and widespread, making it more difficult for the general public to separate reliable…

Abstract

Purpose

Diffusion of fake news and pseudo-facts is becoming increasingly fast-paced and widespread, making it more difficult for the general public to separate reliable information from misleading content. The purpose of this article is to provide a more advanced understanding of the underlying processes that contribute to the spread of health- and beauty-related rumors and of the mechanisms that can mitigate the risks associated with the diffusion of fake news.

Design/methodology/approach

By adopting denialism as a conceptual lens, this article introduces a framework that aims to explain the mechanisms through which fake news and pseudo-facts propagate within the health and beauty industry. Three exemplary case studies situated within the context of the health and beauty industry reveal the persuasiveness of these principles and shed light on the diffusion of false and misleading information.

Findings

The following seven denialistic marketing tactics that contribute to diffusion of fake news can be identified: (1) promoting a socially accepted image; (2) associating brands with a healthy lifestyle; (3) use of experts; (4) working with celebrity influencers; (5) selectively using and omitting facts; (6) sponsoring research and pseudo-science; and (7)exploiting regulatory loopholes. Through a better understanding of how fake news spreads, brand managers can simultaneously improve the optics that surround their firms, promote sales organically and reinforce consumers’ trust toward the brand.

Originality/value

Within the wider context of the health and beauty industry, this article sets to explore the mechanisms through which fake news and pseudo-facts propagate and influence brands and consumers. The article offers several contributions not only to the emergent literature on fake news but also to the wider marketing and consumer behavior literature.

Details

Journal of Product & Brand Management, vol. 29 no. 2
Type: Research Article
ISSN: 1061-0421

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Article
Publication date: 22 July 2019

Amanda Blair, Thomas Martin Key and Matthew Wilson

The purpose of this paper is to illustrate and conceptualize how crowdsourcing can be implemented as a potential means to address gaps in service quality within service…

Abstract

Purpose

The purpose of this paper is to illustrate and conceptualize how crowdsourcing can be implemented as a potential means to address gaps in service quality within service networks and to provide guidance to marketing practitioners on the use of crowdsourcing within service networks.

Design/methodology/approach

This paper conceptualizes how crowdsourcing can be used to address service quality gaps in service networks and provides propositions regarding the effects of crowdsourcing on service quality gaps.

Findings

Conceptual paper with a literature review, suggested a model for service quality gaps in service networks and propositions regarding the effects of crowdsourcing to manage service quality gaps.

Research limitations/implications

This research contributes to the literature on crowdsourcing by theorizing how crowdsourcing impacts service quality in service networks.

Practical implications

Considerations for managers implementing crowdsourcing strategies and activities within service networks are provided. In particular, implications with regard to forming the crowd, developing the most appropriate approach and integrating value into the firm are discussed.

Originality/value

This paper offers an original contribution linking crowdsourcing to service quality.

Details

Journal of Business & Industrial Marketing, vol. 34 no. 7
Type: Research Article
ISSN: 0885-8624

Keywords

Abstract

Details

Multi-Channel Marketing, Branding and Retail Design
Type: Book
ISBN: 978-1-78635-455-6

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Article
Publication date: 1 March 2008

Wanpeng Wang, Zhufeng Yue, Yongle Hu and Junde Lin

This paper presents numerical simulation results of cylindrical steel lining‐concrete structure’s dynamic plastic response under internal intense blast loading by…

Abstract

This paper presents numerical simulation results of cylindrical steel lining‐concrete structure’s dynamic plastic response under internal intense blast loading by ANSYS/lS‐DYNA finite element software. The emphasis is put on the dynamic plastic deformation and three‐dimensional stress conditions of steel lining‐concrete structure. It is shown that maximal plastic deformation of steel lining‐concrete structure results from the first action of shock wave on internal surface of the structure. For the steel lining of the structure, radial stress is compressive stress, while hoop and axial stress is tension stress. For concrete of the structure, three‐dimension stress is compressive stress near the out surface of steel lining. Radial stress of concrete at intense shock wave seems to decay as an exponential function with increasing of scaled‐distance.

Details

Multidiscipline Modeling in Materials and Structures, vol. 4 no. 3
Type: Research Article
ISSN: 1573-6105

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Book part
Publication date: 6 April 2021

Alexey Mikhaylov, Mir Sayed Shah Danish and Tomonobu Senjyu

In this study, it is examined how to improve the effectiveness of bitcoin market. In this framework, firstly, a wide literature review is made, and different factors that…

Abstract

In this study, it is examined how to improve the effectiveness of bitcoin market. In this framework, firstly, a wide literature review is made, and different factors that may be effective in this regard are identified. Afterward, an analysis is performed with Hurst method to determine which of these factors are more important. The study of cryptocurrency volatility is important in terms of financial instruments for hedging traditional assets, as well as in terms of pricing. The above results would be particularly useful in terms of portfolio management and risk management. This study discusses various financial issues related to cryptocurrencies, as well as some problems associated with the problems of their forecasting. To solve the problems of forecasting, the authors have not only studied, but also improved the forecasting method based on the machine learning algorithm in the MATLAB system using the tree model. Most of the analysis in the document relies heavily on studies by authors studying this issue. They can help make more informed decisions regarding financial investments and avoid the risks of using cryptocurrencies. The results may also assist regulators in creating a favorable legal environment for the functioning of the cryptocurrency market.

Details

Strategic Outlook in Business and Finance Innovation: Multidimensional Policies for Emerging Economies
Type: Book
ISBN: 978-1-80043-445-5

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