Search results

1 – 10 of over 30000
To view the access options for this content please click here
Article
Publication date: 13 September 2011

Kirill Blinov, Alexander Nikanorov, Bernard Nacke and Markus Klöpzig

Because of their widespread use in industry, induction through‐heaters of various metal products must be of high effectiveness not only in “quasi” steady‐state operation…

Abstract

Purpose

Because of their widespread use in industry, induction through‐heaters of various metal products must be of high effectiveness not only in “quasi” steady‐state operation but in different transient modes as well. Nowadays, they are usually designed to provide the required characteristics in “quasi” steady‐state operation mode mainly. The purpose of this paper is to examine numerical simulation of transient processes in induction through‐heating lines generally and investigate dynamic temperature fields during the first start of the heaters particularly.

Design/methodology/approach

The research methodology is based on coupled numerical electromagnetic and thermal analyses using FEM approach. ANSYS simulations are supported with the developed tools for imitation of mass transfer effects in continuous induction heating lines.

Findings

The results show that transient temperature fields in the heated strip or slab significantly differ from their “quasi” steady‐state descriptions. Local temperature variations acquired in longitudinal as well as transverse flux induction heaters during the first start have been predicted.

Practical implications

The received results can be used for design of induction through‐heaters and improvement of their characteristics in dynamic operation modes.

Originality/value

Investigation of dynamic characteristics of the heaters in dynamic modes can be only done by numerical modelling based on special algorithms providing a time loop additional to coupling between electromagnetic and thermal analyses. Such algorithms have been developed and used for investigation of two types of induction installations: through‐heaters of cylindrical billets for forging and heating lines of strip or thin slab for rolling mills.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 27 May 2021

Runqiang Zhang, Guoyong Sun, Yuchuan Wang and Sebastián Leguizamón

The study aims to display the bubbles' evolution in the shear layer and their relationship with the pressure fluctuations. Furthermore, the coherent structures of the…

Abstract

Purpose

The study aims to display the bubbles' evolution in the shear layer and their relationship with the pressure fluctuations. Furthermore, the coherent structures of the first six modes are extracted, in order to provide insight into their temporal and spatial evolution and determine the relationship between cavitating bubbles and coherent structures.

Design/methodology/approach

In the present study, numerical simulations of submerged jet cavitating flow were carried out at a cavitation inception condition inside an axisymmetric cavity using the large eddy simulation (LES) turbulence model and the Schnerr–Sauer (S–S) cavitation model. Based on snapshots produced by the numerical simulation, dynamic mode decomposition (DMD) was performed to extract the three-dimensional coherent structures of the first six modes in the shear layer.

Findings

The cavitating bubbles in the shear layer are deformed to elongated ellipsoid shapes by shear forces. The significant pressure fluctuations are induced by the collapse of the biggest bubble in the group. The first mode illustrates the mean characteristics of the flow field. The flow in the peripheral region of the shear layer is mainly dominated by large-scale coherent structures revealed by the second and third modes, while different small-scale coherent structures are contained in the central region. The cavitating bubbles are associated with small size coherent structures as the sixth or higher modes.

Practical implications

This work demonstrates the feasibility of LES for high Reynolds number shear layer flow. The dynamic mode decomposition method is a novel method to extract coherent structures and obtain their dynamic information that will help us to optimize and control the flow.

Originality/value

(1) This paper first displays the three-dimensional coherent structures and their characteristics in the shear layer of confined jet flow. (2) The relationship of bubbles shape and pressure fluctuations is illustrated. (3) The visualization of coherent structures benefits the understanding of the mixing process and cavitation inception in jet shear layers.

Details

Engineering Computations, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 8 May 2018

Stephie Edwige, Yoann Eulalie, Philippe Gilotte and Iraj Mortazavi

The purpose of this paper is to present numerical investigations of the flow dynamic characteristics of a 47° Ahmed Body to identify wake flow control strategy leading to…

Abstract

Purpose

The purpose of this paper is to present numerical investigations of the flow dynamic characteristics of a 47° Ahmed Body to identify wake flow control strategy leading to drag coefficient reduction, which could be tested later on sport utility vehicles.

Design/methodology/approach

This study begins with a mean flow topology description owing to dynamic and spectral analysis of the aerodynamic tensor. Then, the sparse promoting dynamic modal decomposition method is discussed and compared to other modal approaches. This method is then applied on the wall and wake pressure to determine frequencies of the highest energy pressure modes and their transfers to other frequency modes. This analysis is then used to design appropriated feedback flow control strategies.

Findings

This dynamic modal decomposition highlights a reduced number of modes at low frequency which drive the flow dynamics. The authors especially notice that the pressure mode at a Strouhal number of 0.22, based on the width between feet, induces aerodynamic losses close to the rear end. Strategy of the proposed control loop enables to dampen the energy of this mode, but it has been transferred to lower frequency mode outside of the selected region of interest.

Originality/value

This analysis and methodology of feedback control shows potential drag reduction with appropriated modal energy transfer management.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 8 May 2007

Yi Zhang, Zigang Zhang and Zhixue Liu

This paper seeks to challenge the traditional wisdom that sheds light upon sequential entry modes in developed countries by exploring the dynamic entry mode choice in…

Downloads
10915

Abstract

Purpose

This paper seeks to challenge the traditional wisdom that sheds light upon sequential entry modes in developed countries by exploring the dynamic entry mode choice in sequential foreign direct investment (FDI) in emerging economies.

Design/methodology/approach

A review of the literature on the entry mode choice is undertaken. Based on analysing two related theories consisting of the knowledge‐based theory of the firm and organizational learning theory, entry mode choices in sequential FDI in emerging economies are investigated using both an internationalisation process model and the capability‐developing perspective, and exclusive propositions are put forward accordingly. Then, these propositions are tested on the context of China with the methodology of paired‐samples t‐tests.

Findings

Based on macro‐level longitudinal data in China from 1979 to 2005, the choice of entry mode in sequential FDI in emerging economies is inconsistent with the capability‐developing theory of the firm, but is consistent with the international process model.

Practical implications

This study provides four practical implications. First, managers intending to invest abroad need to consider the cost and return of a specific entry mode. Second, knowledge about host markets has a more important effect on entry mode choice in emerging markets than MNCs' internal organizational capabilities. Third, MNCs adopt sequential investment in emerging economies, in which they adopt joint ventures in earlier entries and then shift to green‐field investment in later entries. Fourth, experiential learning, which consists of learning about host markets and local partners' skills, is emphasized in sequentially entering emerging markets.

Originality/value

This paper expands the research scope of previous studies that either explore a static choice of entry mode in foreign markets or only examine the entry mode choice in sequential FDI in developed countries. Taking into consideration the dynamic choice of entry modes, the paper studies sequential FDI in emerging economies, which throws light upon theoretical analysis of sequential FDI in China, and which has practical implications for foreign firms that are interested in China and planning to enter China's markets.

Details

Management Decision, vol. 45 no. 4
Type: Research Article
ISSN: 0025-1747

Keywords

To view the access options for this content please click here
Article
Publication date: 3 October 2016

Yanhong Yao and Huiping Zhou

The purpose of this paper is to build a symbiotic evolution model to analyze the symbiotic modes and dynamic equilibrium of mobile internet platform innovation ecosystem…

Abstract

Purpose

The purpose of this paper is to build a symbiotic evolution model to analyze the symbiotic modes and dynamic equilibrium of mobile internet platform innovation ecosystem (MIPIE) in order to explore its evolutionary path.

Design/methodology/approach

From a symbiosis theory perspective, the authors studied the dynamic evolution stages and symbiotic mode of MIPIE. By adopting logistic model, the symbiotic evolution model of MIPIE is established. After calculating the steady conditions and equilibrium point of this model, numerical simulation was done with MATLAB software to illustrate the impact of symbiotic parameters on evolution path in this ecosystem.

Findings

The symbiotic evolution mode of MIPIE experienced parasitism, commensalism to asymmetric mutualism, and symmetry mutualism or independence. In given conditions, the dynamic evolution of MIPIE eventually tends to a steady equilibrium point. The evolutionary consequence of innovative subjects is not only determined by the natural growth rate, but symbiotic modes can also affect the evolutionary path. Different symbiotic modes result in different evolutionary paths.

Practical implications

Improved understanding of symbiosis in MIPIE could help policy makers to promote value co-creation and dynamic interests balance while facilitating the cooperation of others for successful platform ecosystem management.

Originality/value

The logistic model introduced here bridge theory and practice while establishing a stronger link between symbiosis theory and platform ecosystem management.

Details

Kybernetes, vol. 45 no. 9
Type: Research Article
ISSN: 0368-492X

Keywords

To view the access options for this content please click here
Article
Publication date: 1 December 2001

Nasr Eddine Debbache

Increases in air traffic and air traffic controller workload lead to a need to provide assistance to the air traffic controller. Proposes and validates a new organization…

Abstract

Increases in air traffic and air traffic controller workload lead to a need to provide assistance to the air traffic controller. Proposes and validates a new organization of air traffic control, which allows air traffic controllers to remain active in the control and supervisory loop of the process, in order to maintain the present traffic safety level and to improve the global system performances. Consists of decomposing the problem according to the two levels of the air traffic control organization. Directs the first step towards a horizontal cooperation that consists of a dynamic allocation of the tactical level control tasks between human air traffic controllers and an assistance tool. Presents the dynamic task allocation principles, and describes the experimental platform for task allocation in air traffic control. Describes the experimental protocol used for the experiments with qualified controllers and presents the first results. They show the real help a dynamic task allocation provides to the air traffic controllers.

Details

Aircraft Engineering and Aerospace Technology, vol. 73 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

To view the access options for this content please click here
Article
Publication date: 13 February 2020

Liping Ying, Yijiang Peng and Mahmoud M.A. Kamel

Based on the random aggregate model of recycled aggregate concrete (RAC), this paper aims to focus on the effect of loading rate on the failure pattern and the macroscopic…

Abstract

Purpose

Based on the random aggregate model of recycled aggregate concrete (RAC), this paper aims to focus on the effect of loading rate on the failure pattern and the macroscopic mechanical properties.

Design/methodology/approach

RAC is regarded as a five-phase inhomogeneous composite material at the mesoscopic level. The number and position of the aggregates are modeled by the Walraven formula and Monte–Carlo stochastic method, respectively. The RAC specimen is divided by the finite-element mesh to establish the dynamic base force element model. In this model, the element mechanical parameters of each material phase satisfy Weibull distribution. To simulate and analyze the dynamic mechanical behavior of RAC under axial tension, flexural tension and shear tension, the dynamic tensile modes of the double-notched specimens, the simply supported beam and the L specimens are modeled, respectively. In addition, the different concrete samples are numerically investigated under different loading rates.

Findings

The failure strength and failure pattern of RAC have strong rate-dependent characteristics because of the inhomogeneity and the inertial effect of the material.

Originality/value

The dynamic base force element method has been successfully applied to the study of recycled concrete.

Details

Engineering Computations, vol. 37 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 12 February 2019

S. Abolfazl Mokhtari and Mehdi Sabzehparvar

The paper aims to present an innovative method for identification of flight modes in the spin maneuver, which is highly nonlinear and coupled dynamic.

Abstract

Purpose

The paper aims to present an innovative method for identification of flight modes in the spin maneuver, which is highly nonlinear and coupled dynamic.

Design/methodology/approach

To fix the mode mixing problem which is mostly happen in the EMD algorithm, the authors focused on the proposal of an optimized ensemble empirical mode decomposition (OEEMD) algorithm for processing of the flight complex signals that originate from FDR. There are two improvements with the OEEMD respect to the EEMD. First, this algorithm is able to make a precise reconstruction of the original signal. The second improvement is that the OEEMD performs the task of signal decomposition with fewer iterations and so with less complexity order rather than the competitor approaches.

Findings

By applying the OEEMD algorithm to the spin flight parameter signals, flight modes extracted, then with using systematic technique, flight modes characteristics are obtained. The results indicate that there are some non-standard modes in the nonlinear region due to couplings between the longitudinal and lateral motions.

Practical implications

Application of the proposed method to the spin flight test data may result accurate identification of nonlinear dynamics with high coupling in this regime.

Originality/value

First, to fix the mode mixing problem in EMD, an optimized ensemble empirical mode decomposition algorithm is introduced, which disturbed the original signal with a sort of white Gaussian noise, and by using white noise statistical characteristics the OEEMD fix the mode mixing problem with high precision and fewer calculations. Second, by applying the OEEMD to the flight output signals and with using the systematic method, flight mode characteristics which is very important in the simulation and controller designing are obtained.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

To view the access options for this content please click here
Article
Publication date: 1 September 2006

Paul Knott

The purpose of this research is to improve the success rate and quality of outcome when strategy tools are used in practical situations.

Downloads
4895

Abstract

Purpose

The purpose of this research is to improve the success rate and quality of outcome when strategy tools are used in practical situations.

Design/methodology/approach

Draws on post‐experience teaching and uses conceptual reasoning to propose a typology of tool applications.

Findings

The paper finds that strategy tools need to be used differently according to the problem needs, and hence proposes five generic modes of tool application. These draw on seven dimensions to codify the functions and cognitive characteristics in a given tool application.

Research limitations/implications

The modes of application are conceptually rather than empirically derived. The paper provides conceptual background that could be used in much‐needed empirical work on tool use in the strategy activity.

Practical implications

The typology could be used in teaching or facilitation to encourage and help with the design of tool adaptations that are coherent and well adapted to the situation. It provides a means for prior reflection on tool choice and application that could help reduce detrimental framing effects.

Originality/value

The paper highlights the centrality of user adaptation of tools and begins to codify the effects of tool enactment. It moves debate from the tools themselves to the application of tools, which has seldom been addressed in a systematic fashion. For practitioners it provides explicit guidance on the tool adaptation process.

Details

Management Decision, vol. 44 no. 8
Type: Research Article
ISSN: 0025-1747

Keywords

To view the access options for this content please click here
Article
Publication date: 16 July 2021

Vieri Cardinali, Marta Castellini, Maria Teresa Cristofaro, Giorgio Lacanna, Massimo Coli, Mario De Stefano and Marco Tanganelli

This paper aims to contribute to the discussion of the experimental campaigns on Cultural Heritage buildings. By adopting integrated procedures it is possible to limit the…

Abstract

Purpose

This paper aims to contribute to the discussion of the experimental campaigns on Cultural Heritage buildings. By adopting integrated procedures it is possible to limit the invasiveness of the destructive techniques leading to reliable results. The purpose is the proper definition of the structural system, which represents the starting point of the following analysis's phases, not treated in this work. A methodology based on normative references and acknowledged non-destructive and partial destructive strategies has been conceived. The latter aims to an accurate comprehension of the structural information.

Design/methodology/approach

An integrated approach for the structural assessment of cultural heritage buildings is presented. The methodology defines an interdisciplinary procedure based on normative references, non-destructive and minor-destructive techniques. A funnel-shaped workflow is developed to characterize the structural system of the buildings. The non-destructive campaigns are widely extended. Then, in-depth analysis concerning partial demolitions and minor-destructive tests are performed. The dynamic identification of the building is executed to detect its global response. The final validation of the assumed mechanical values is obtained by comparing the experimental modes coming from the ambient vibrations and the analytical modes of the structural modelling.

Findings

This research belongs to the Protocol signed between the Municipality of Florence and Department of Earth's Science and Department of Architecture of the University of Florence for the seismic vulnerability assessment of relevant and strategic buildings.

Research limitations/implications

The descripted methodology is targeted for monuments and special buildings where the use of destructive techniques is not possible or unrecommended.

Social implications

Social implications are related to the conservation of Heritage buildings. The latter deals with: (1) risk assessment of the targeted buildings towards different hazard sources (e.g. earthquakes, floods); (2) knowledge path developed through non-invasive diagnostic campaigns oriented to the conservation of the manufact. Furthermore, the paper encourages towards the recognition of non-destructive techniques and ambient vibration tests for the achievement of higher knowledge levels.

Originality/value

This paper defines a funnel-shaped procedure defining hierarchical roles between the different available strategies. The originality of this contribution is firstly related to the methodological flowchart. It is targeted to limit the invasive tests and consequently achieving accurate levels of knowledge. Secondly, some novelty can be found in the adoption of improvement parameters from a regional database adopting a Bayesian approach.

Details

Journal of Cultural Heritage Management and Sustainable Development, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2044-1266

Keywords

1 – 10 of over 30000