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Article
Publication date: 3 July 2017

L. Ebrahimnejad, K.D. Janoyan, D.T. Valentine and P. Marzocca

The application of reduced order models (ROMs) in the aerodynamic/aeroelastic analysis of long-span bridges, unlike the aeronautical structures, has not been extensively…

Abstract

Purpose

The application of reduced order models (ROMs) in the aerodynamic/aeroelastic analysis of long-span bridges, unlike the aeronautical structures, has not been extensively studied. ROMs are computationally efficient techniques, which have been widely used for predicting unsteady aerodynamic response of airfoils and wings. This paper aims to discuss the application of a reduced order computational fluid dynamics (CFD) model based on the eigensystem realization algorithm (ERA) in the aeroelastic analysis of the Great Belt Bridge (GBB).

Design/methodology/approach

The aerodynamic impulse response of the GBB section is used to construct the aerodynamic ROM, and then the aerodynamic ROM is coupled with the reduced DOF model of the system to construct the aeroelastic ROM. Aerodynamic coefficients and flutter derivatives are evaluated and compared to those of the advanced discrete vortex method-based CFD code.

Findings

Results demonstrate reasonable prediction power and high computational efficiency of the technique that can serve for preliminary aeroelastic analysis and design of long-span bridges, optimization and control purposes.

Originality/value

The application of a system identification tool like ERA into the aeroelastic analysis of long-span bridges is performed for the first time in this work. Authors have developed their earlier work on the aerodynamic analysis of long-span bridges, published in the Journal of Bridge Engineering, by coupling the aerodynamic forces with reduced DOF of structural system. The high computational efficiency of the technique enables bridge designers to perform preliminary aeroelastic analysis of long-span bridges in less than a minute.

Details

Engineering Computations, vol. 34 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 19 June 2017

Warwick Funnell, Valerio Antonelli, Raffaele D’Alessio and Roberto Rossi

The purpose of this paper is to understand the role played by accounting in managing an early nineteenth century lunatic asylum in Palermo, Italy.

Abstract

Purpose

The purpose of this paper is to understand the role played by accounting in managing an early nineteenth century lunatic asylum in Palermo, Italy.

Design/methodology/approach

The paper is informed by Foucault’s studies of lunatic asylums and his work on governmentality which gave prominence to the role of statistics, the “science of the State”.

Findings

This paper identifies a number of roles played by accounting in the management of the lunatic asylum studied. Most importantly, information which formed the basis of accounting reports was used to describe, classify and give visibility and measurability to the “deviance” of the insane. It also legitimated the role played by lunatic asylums, as entrusted to them in post-Napoleonic early nineteenth century society, and was a tool to mediate with the public authorities to provide adequate resources for the institution to operate.

Research limitations/implications

This paper encourages accounting scholars to engage more widely with socio-historical research that will encompass organisations such as lunatic asylums.

Originality/value

This paper provides, for the first time, a case of accounting applied to a lunatic asylum from a socio-historical perspective.

Details

Accounting, Auditing & Accountability Journal, vol. 30 no. 5
Type: Research Article
ISSN: 0951-3574

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Article
Publication date: 3 January 2017

Alessandro Ceruti and Pier Marzocca

This paper aims to describe a methodology to optimize the trajectory of unconventional airship performing a high-altitude docking manoeuvre.

Abstract

Purpose

This paper aims to describe a methodology to optimize the trajectory of unconventional airship performing a high-altitude docking manoeuvre.

Design/methodology/approach

The trajectories are based upon Bezier curves whose control points positions are optimized through particle swarm optimization algorithm. A minimum energy strategy is implemented by considering the airship physical properties. The paper describes the mathematical model of the airships, the trajectories modelling through Bezier’s curves and the optimization framework. A series of test cases has been developed to evaluate the proposed methodology.

Findings

Results obtained show that the implemented procedure is able to optimize the airship trajectories and to support their in-flight docking; a strong influence of the wind speed and course on the trajectories planning is highlighted.

Research limitations/implications

The wind speed considered in these simulations depends only on altitude, and gusts effect has been neglected.

Practical implications

The proposed model can support the study of unconventional airship trajectories and can be useful to evaluate best in-air docking strategies.

Originality/value

The paper addresses the problem of trajectory optimization for a class of new air vehicles with an heuristic approach.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 1
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 1 September 2021

Said Chaabani and Naoufel Azouz

This paper presents preliminary results of the modeling of a large autonomous quad-rotor airship, with flying wing shape. This airship is supposed to be a flexible body…

Abstract

Purpose

This paper presents preliminary results of the modeling of a large autonomous quad-rotor airship, with flying wing shape. This airship is supposed to be a flexible body. This study promotes an entirely analytical methodology with some assumptions. In this study and as first assumption, the shape of the careen is supposed to be an elliptic cone. To retrieve the velocity potential shapes, this paper solved the Laplace’s equation by using the sphero-conal coordinates. This leads to the Lamé’s equations. The whole system equations governing the interaction of air–structure, including the boundary conditions, is solved in an analytical setting.

Design/methodology/approach

This paper opted for a modeling and determination of the added masses of a flexible airship by an analytical method illustrated by a comparison with a geometric method. This analytical method includes the study of complex functions which are the Lamé functions.

Findings

This paper provides an analytical way to estimate an aerodynamic phenomenon which acts on the airship and in particular on its envelope and known as the phenomenon of added masses or virtual masses, as well as the means of defining it and the calculation analytically for the case of the flexible airship.

Research limitations/implications

Considering that the calculation of the added masses is very difficult and the numerical methods increase the number of degrees of freedom, the analytical method established in this paper has become a solution of calculations of these virtual masses.

Practical implications

This paper includes an application for determining the added masses of a new generation MC500 airship.

Originality/value

This paper allows defining an analytical method which determines the added masses of an airship, which helps the automation engineer to develop a control strategy to stabilize this airship.

Details

Aircraft Engineering and Aerospace Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 1 August 2016

Fatemeh Esfarjani, Ramin Khaksar, Fatemeh Mohammadi Nasrabadi, Roshanak Roustaee, Haleh Alikhanian, Niloofar Khalaji, Amin Mousavi Khaneghah and Hedayat Hosseini

Domestic refrigerators could be considered as one of the major potential sources of food-borne diseases, in addition limited data are available regarding the level of…

Abstract

Purpose

Domestic refrigerators could be considered as one of the major potential sources of food-borne diseases, in addition limited data are available regarding the level of contamination of domestic refrigerators in Iran. The purpose of this paper is to detect some of bacterial contamination in domestic refrigerators.

Design/methodology/approach

In total, 104 households were randomly selected from ten health centers in five areas of Tehran, Iran. Visual inspection and temperature evaluation of the households’ refrigerators were done. In addition, the refrigerators were swabbed and analyzed for contaminants using polymerase chain reaction (PCR) method. DNA was isolated and purified by the proposed standard protocol.

Findings

Screening of the domestic refrigerators by PCR method showed that 51.7 percent of the samples were positive for pathogens as follows: L. monocytogenes 41.6 percent, S. aureus 5.5 percent, Salmonella spp 4.6 percent, and E. coli O157:H7 0 percent; consequently, none of mentioned pathogens were detected in 48.3 percent of the refrigerators. Results of the visual inspection indicated that 57 percent of the refrigerators were on desirable, 36.5 percent were acceptable, and 7 percent were weak conditions. Most of the refrigerators about 44 percent had desirable temperatures. There were no significant correlations between the visual inspection scores, temperature and frequency of isolation of specific pathogens in the domestic refrigerators. A significant correlation was observed between contamination and education of parents (p < 0.05).

Originality/value

Determination of the bacterial contamination and evaluating the temperature of domestic refrigerators in Iran can be considered as a novel approach of current study. These findings could be employed in designing and implementing appropriate educational interventions to promote food safety and diminish the risk of food-borne illnesses. Also, obtained results might be applied as introduction for further investigations.

Details

British Food Journal, vol. 118 no. 8
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 3 January 2017

Anwar ul-Haque, Waqar Asrar, Ashraf Ali Omar, Erwin Sulaeman and JS Mohamed Ali

Realistic data bank of aerodynamic and stability derivatives is still missing for hybrid buoyant aerial vehicles. Such vehicles take-off and land similar to an aircraft…

Abstract

Purpose

Realistic data bank of aerodynamic and stability derivatives is still missing for hybrid buoyant aerial vehicles. Such vehicles take-off and land similar to an aircraft with their partial weight balanced by the aerostatic lift. The purpose of this paper is to use wind tunnel testing for a better understanding of the aerodynamic and static stability behavior of such vehicles.

Design/methodology/approach

The effect of wing on the aerodynamic and static stability characteristics of a clean configuration hybrid buoyant is analyzed. The free stream velocity is 20 m/s, and ranges of angle of attack and side slip angle are from −8° to 12° and ±16°, respectively. Data are corrected to account for the effect of strut interference and zero load condition. The maximum blockage of the model with respect to the cross-section area of the test section is about 2.7 per cent.

Findings

A hybrid model manufactured by using wood and metal is an optimum solution with less number of parts. The vehicle is statically, longitudinally and directionally stable. Wings designed to fulfill the partial requirement of lift contribute significantly to counter the huge moment generated by the voluminous hull for centre of gravity location ahead of the leading edge of the wing.

Research limitations/implications

There are number of manufacturing constraints for scaling down a model of a hybrid buoyant aerial vehicle configuration. Specially, the thickness of the wing limits the testing envelop of angle of attack and free stream velocity.

Practical implications

The data presented here are a preliminary guide for further work on larger size models. The data may also be used to build and perform flight tests on small full-scale instrumented models and to obtain flight dynamics data.

Originality/value

The estimated aerodynamic and stability derivatives and slopes can be utilized in future for multidisciplinary design.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 1
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 31 May 2011

S. Askari, M.H. Shojaeefard and K. Goudarzi

The purpose of this paper is to carry out a comprehensive study of compressible flow over double wedge and biconvex airfoils using computational fluid dynamics (CFD) and…

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Abstract

Purpose

The purpose of this paper is to carry out a comprehensive study of compressible flow over double wedge and biconvex airfoils using computational fluid dynamics (CFD) and three analytical models including shock and expansion wave theory, Busemann's second‐order linearized approximation and characteristic method (CHM).

Design/methodology/approach

Flow over double‐wedge and biconvex airfoils was investigated by the CFD technique using the Spalart‐Allmaras turbulence model for computation of the Reynolds stresses. Flow was considered compressible, two dimensional and steady. The no slip condition was applied at walls and the Sutherland law was used to calculate molecular viscosity as a function of static temperature. First‐order upwind discretization scheme was used for the convection terms. Finite‐volume method was used for the entire solution domain meshed by quadratic computational cells. Busemann's theory, shock and expansion wave technique and CHM were the analytical methods used in this work.

Findings

Static pressure, static temperature and aerodynamic coefficients of the airfoils were calculated at various angles of attack. In addition, aerodynamic coefficients of the double‐wedge airfoil were obtained at various free stream Mach numbers and thickness ratios of the airfoil. Static pressure and aerodynamic coefficients obtained from the analytical and numerical methods were in excellent agreement with average error of 1.62 percent. Variation of the static pressure normal to the walls was negligible in the numerical simulation as well as the analytical solutions. Analytical static temperature far from the walls was consistent with the numerical values with average error of 3.40 percent. However, it was not comparable to the numerical temperature at the solid walls. Therefore, analytical solutions give accurate prediction of the static pressure and the aerodynamic coefficients, however, for the static temperature; they are only reliable far from the solid surfaces. Accuracy of the analytical aerodynamic coefficients is because of accurate prediction of the static pressure which is not considerably influenced by the boundary layer. Discrepancies between analytical and numerical temperatures near the walls are because of dependency of temperature on the boundary layer and viscous heating. Low‐speed flow near walls causes transformation of the kinetic energy of the free stream into enthalpy that leads to high temperature on the solid walls; which is neglected in the analytical solutions.

Originality/value

This paper is useful for researchers in the area of external compressible flows. This work is original.

Details

Engineering Computations, vol. 28 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 24 September 2021

Qiang Wang, Chen Meng and Cheng Wang

This study aims to reveal the essential characteristics of nonstationary signals and explore the high-concentration representation in the joint time–frequency (TF) plane.

Abstract

Purpose

This study aims to reveal the essential characteristics of nonstationary signals and explore the high-concentration representation in the joint time–frequency (TF) plane.

Design/methodology/approach

In this paper, the authors consider the effective TF analysis for nonstationary signals consisting of multiple components.

Findings

To make it, the authors propose the combined multi-window Gabor transform (CMGT) under the scheme of multi-window Gabor transform by introducing the combination operator. The authors establish the completeness utilizing the discrete piecewise Zak transform and provide the perfect-reconstruction conditions with respect to combined TF coefficients. The high-concentration is achieved by optimization. The authors establish the optimization function with considerations of TF concentration and computational complexity. Based on Bergman formulation, the iteration process is further analyzed to obtain the optimal solution.

Originality/value

With numerical experiments, it is verified that the proposed CMGT performs better in TF analysis for multi-component nonstationary signals.

Details

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

Keywords

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Article
Publication date: 21 September 2020

Jacobus D. Brandsen, Axelle Viré, Sergio R. Turteltaub and Gerard J.W. Van Bussel

When simulating fluid-structure interaction (FSI), it is often essential that the no-slip condition is accurately enforced at the wetted boundary of the structure. This…

Abstract

Purpose

When simulating fluid-structure interaction (FSI), it is often essential that the no-slip condition is accurately enforced at the wetted boundary of the structure. This paper aims to evaluate the relative strengths and limitations of the penalty and Lagrange multiplier methods, within the context of modelling FSI, through a comparative analysis.

Design/methodology/approach

In the immersed boundary method, the no-slip condition is typically imposed by augmenting the governing equations of the fluid with an artificial body force. The relative accuracy and computational time of the penalty and Lagrange multiplier formulations of this body force are evaluated by using each to solve three test problems, namely, flow through a channel, the harmonic motion of a cylinder through a stationary fluid and the vortex-induced vibration (VIV) of a cylinder.

Findings

The Lagrange multiplier formulation provided an accurate solution, especially when enforcing the no-slip condition, and was robust as it did not require “tuning” of problem specific parameters. However, these benefits came at a higher computational cost relative to the penalty formulation. The penalty formulation achieved similar levels of accuracy to the Lagrange multiplier formulation, but only if the appropriate penalty factor was selected, which was difficult to determine a priori.

Originality/value

Both the Lagrange multiplier and penalty formulations of the immersed boundary method are prominent in the literature. A systematic quantitative comparison of these two methods is presented within the same computational environment. A novel application of the Lagrange multiplier method to the modelling of VIV is also provided.

Details

Engineering Computations, vol. 38 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 2 May 2017

S. Ahmad Fazelzadeh and Emad Azadi

The purpose of this paper is to analyze and control the thermally induced vibration of orbiting smart satellite panels, which have been modeled as functionally graded…

Abstract

Purpose

The purpose of this paper is to analyze and control the thermally induced vibration of orbiting smart satellite panels, which have been modeled as functionally graded material (FGM) beams.

Design/methodology/approach

It is assumed that the satellite moves in a circular orbit and has pitch angle rotation maneuver. Rapid temperature changes at day–night transitions in orbit generate time dependent bending moments that induce vibrations in the appendages. So, the heat radiation effects on the appendages should be considered. The thermally induced vibrations of the appendages and the nonlinear heat transfer equation are coupled and should be solved simultaneously. So, the governing equations of the motion are nonlinear and very complicated ones. A robust passivity-based controller is proposed to control the satellite maneuver and appendages vibrations, using piezoelectric sensors/actuators.

Findings

After the simulation, the effects of the heat radiation, piezoelectric actuators and piezoelectric locations on the response of the system are studied. The results of dynamic response and thermal analysis show that the radiation thermal effects are coupled with structure dynamic. These effects induce the vibration. Also, the effectiveness and the capability of the controller are analyzed. The results of the simulation show that the robust passivity-based control can ensure that the satellite rotates in the desired trajectory and vibrations of the appendages are damped. It demonstrates that the proposed control scheme is feasible and effective.

Originality/value

The paper is the basis of deriving the governing equations, thermal analysis and a robust control system design of a smart satellite with FGM panels.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

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