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Article
Publication date: 13 September 2021

Gholamreza Imani and Mohsen Mozafari-Shamsi

The lattice Boltzmann simulation of fluid flow in partial porous geometries with curved porous-fluid interfaces has not been investigated yet. It is mainly because of the…

Abstract

Purpose

The lattice Boltzmann simulation of fluid flow in partial porous geometries with curved porous-fluid interfaces has not been investigated yet. It is mainly because of the lack of a method in the lattice Boltzmann framework to model the hydrodynamic compatibility conditions at curved porous-fluid interfaces, which is required for the two-domain approach. Therefore, the purpose of this study is to develop such a method.

Design/methodology/approach

This research extends the non-equilibrium extrapolation lattice Boltzmann method for satisfying no-slip conditions at curved solid boundaries, to model hydrodynamic compatibility conditions at curved porous-fluid interfaces.

Findings

The proposed method is tested against the results available from conventional numerical methods via the problem of fluid flow through and around a porous circular cylinder in crossflow. As such, streamlines, geometrical characteristics of recirculating wakes and drag coefficient are validated for different Reynolds (5 ≤ Re ≤ 40) and Darcy (10−5Da ≤ 5 × 10−1) numbers. It is also shown that without applying any compatibility conditions at the interface, the predicted flow structure is not satisfactory, even for a very fine mesh. This result highlights the importance of the two-domain approach for lattice Boltzmann simulation of the fluid flow in partial porous geometries with curved porous-fluid interfaces.

Originality/value

No research is found in the literature for applying the hydrodynamic compatibility conditions at curved porous-fluid interfaces in the lattice Boltzmann framework.

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: 27 July 2021

Cong Liu, Yanguo Yin, Baohong Tong and Guotao Zhang

This study aims to investigate the effect of MoS2 powder on tribological properties of sliding interfaces.

Abstract

Purpose

This study aims to investigate the effect of MoS2 powder on tribological properties of sliding interfaces.

Design/methodology/approach

Loose MoS2 powder was introduced in the gap of point-contact friction pairs, and sliding friction test was conducted using a testing machine. Friction noise, wear mark appearance, microstructure and wear debris were characterized with a noise tester, white-light interferometer, scanning electron microscope and ferrograph, respectively. Numerical simulation was also performed to analyze the influence of MoS2 powder on tribological properties of the sliding interface.

Findings

MoS2 powder remarkably improved the lubrication performance of the sliding interface, whose friction coefficient and wear rate were reduced by one-fifth of the interface values without powder. The addition of MoS2 powder also reduced stress, plastic deformation and friction temperature in the wear mark. The sliding interface with MoS2 powder demonstrated lower friction noise and roughness compared with the interface without powder lubrication. The adherence of MoS2 powder onto the friction interface formed a friction film, which induced the wear mechanism of the sliding interface to change from serious cutting and adhesive wear to delamination and slight cutting wear under the action of normal and shear forces.

Originality/value

Tribological characteristics of the interface with MoS2 powder lubrication were clarified. This work provides a theoretical basis for solid-powder lubrication and reference for its application in engineering.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0150/

Details

Industrial Lubrication and Tribology, vol. 73 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 16 November 2012

M.A.K. Chowdhuri and Z. Xia

It is well known that stress singularity may exist at the edges of a bonded bi‐material interface due to the discontinuity of material properties. This stress singularity…

Abstract

Purpose

It is well known that stress singularity may exist at the edges of a bonded bi‐material interface due to the discontinuity of material properties. This stress singularity causes difficulty in accurately determining the bi‐material interface bonding strength. This paper aims to present a new design of specimen geometry to eliminate the stress singularity and present an experimental procedure to more accurately determine the bonding strength of the bi‐material interface.

Design/methodology/approach

The design is based on an asymptotic analysis of the stress field near the free edge of bi‐material interface. The critical bonding angle, which delineates the singular and non‐singular stress field near the free edge, is determined.

Findings

With the new designed specimen and a special iterative calculation algorithm, the interface bonding strength envelope of an epoxy‐aluminum interface was experimentally determined.

Originality/value

This new design of specimen, experimental procedure and iterative algorithm may be applied to obtain more reasonable and accurate bonding strength data for a wide range of bi‐material interfaces.

Details

International Journal of Structural Integrity, vol. 3 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 25 January 2008

Liang Lu and Wenhu Huang

As the installation of the vibration isolation device to the spacecraft for the whole spacecraft vibration isolation, the interface structure is typically modeled as a…

Abstract

Purpose

As the installation of the vibration isolation device to the spacecraft for the whole spacecraft vibration isolation, the interface structure is typically modeled as a rigid structure during the design phase. However, the flexibility of the interface structure does exist for a large‐sized adaptor. This is a source of uncertainty and could reduce the reliability of the system. It is necessary to investigate the influence of this type of flexibility on the vibration isolation performance in an engineering practice. This paper aims to address this situation.

Design/methodology/approach

The vibratory transmissibility from the bottom of the isolator is generally used to evaluate the performance of the vibration isolation. By introducing the interface flexibility from both the adaptor and the vibration isolation device, a planar model which includes a flexible beam representing the interface structure is established to study the influence of this type of flexibility on the vibratory transmissibility.

Findings

It is found that, when this type of flexibility is included, an extra low‐frequency mode dominated locally by the interface structure is induced, and then a significant resonance appears in the vibratory transmissibility of the vibration isolation device at a low frequency.

Originality/value

The vibration isolation performance may be over‐estimated in the design by taking the interface as rigid. The inherent flexibility of the interface structure, on the other hand, may degrade the performance of the vibration isolation device and degrade the function of the rotation constraint device added into the vibration isolation device.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 12 January 2010

Ningbo Liao and Ping Yang

The small dimensions of future device designs also imply a stronger effect of material boundary resistance. For nanoscale devices and structures, especially, interface

Abstract

Purpose

The small dimensions of future device designs also imply a stronger effect of material boundary resistance. For nanoscale devices and structures, especially, interface phenomena often dominate their overall thermal behavior. The purpose of this paper is to propose molecular dynamics (MD) simulations to investigate the mechanical and thermal properties at Cu‐Al interface.

Design/methodology/approach

The two‐temperature model (TTM)‐MD model is used to describe the electron‐phonon scattering at interface of different metals. Before the simulation of heat transfer process, a non‐ideal Cu‐Al interface is constructed by simulating diffusion bonding.

Findings

According to the simulation results, in unsteady state, the temperature distribution and the displacements of atoms near the interface tend to generate stress and voids. It reveals the damage mechanics at the interface in heat transfer.

Originality/value

The atomic model proposed in this paper is computationally efficient for interfacial heat transfer problems, and could be used for investigation of other interfacial behaviors of dissimilar materials.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 September 1994

Alan Dix

Looks at the design elements of an effective human interface. Outlineswhat makes a good interface and why so many are bad. Explains the importanceof having a clear idea of…

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645

Abstract

Looks at the design elements of an effective human interface. Outlines what makes a good interface and why so many are bad. Explains the importance of having a clear idea of what jobs are to be done and an understanding of the ways errors happen. Also explains the need to understand and involve the user and the importance of trying out the interface at an early stage. Concludes that bad interfaces cost money and can be dangerous and that the human interface should attract at least the same level of resources as any other major part of system design.

Details

Assembly Automation, vol. 14 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 1 September 2005

Hartmut Brauer, Marek Ziolkowski and Milko Kuilekov

The interface between two conducting fluids in a magnetic fluid dynamics (MFD) problem was identified by means of external magnetic field measurements. Genetic algorithms…

Abstract

Purpose

The interface between two conducting fluids in a magnetic fluid dynamics (MFD) problem was identified by means of external magnetic field measurements. Genetic algorithms (GA) were applied to solve the inverse problem.The principal component analysis (PCA) was used to speed up the process of interface reconstruction.

Design/methodology/approach

With respect to the experimental results we have designed a general technique for mode identification and/or interface reconstruction. Two main procedures are available to solve the inverse problem, the full interface reconstruction and the principle component analysis (PCA) mode. In the case of full reconstruction, it can be decided whether an algorithm for fast identification of the dominant modes applying a FFT module should be performed or not. The full interface reconstruction applies stochastic optimization methods ((GA) or evolution strategies (ES)) for the estimation of the interface shape characteristics. The main goal of the PCA mode is to find the dominant mode of the interface shape and its amplitude. The PCA mode is realized by means of stochastic optimization methods (GA, ES) and a simple direct searching (DS) using the golden section technique.

Findings

PCA with GA procedure enables the identification of the dominant mode of the interface shape between two conducting fluids with sufficient accuracy for simulated magnetic fields. Time of identification is strongly reduced due to a redefinition of the genotype representations in the PCA mode. Accuracy of reconstruction depends on the noise level, i.e. signal to noise ratio and a geometrical model used in the reconstruction phase. The correlation between the noise level and values of cost function for identified modes has been found if a proper geometry modelling is applied.

Originality/value

The paper describes a new, fast technique for solving an inverse field problem of a MFD problem where the interface between two conducting fluids has to be identified using a magnetic field tomography measuring system.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 27 November 2007

Mansor Yushiana and Widyawati Abdul Rani

The purpose of this paper is to investigate the usability of a web‐based OPAC (WebPAC) user interface at the International Islamic University Malaysia (IIUM). It also…

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3255

Abstract

Purpose

The purpose of this paper is to investigate the usability of a web‐based OPAC (WebPAC) user interface at the International Islamic University Malaysia (IIUM). It also looks at the applicability of heuristic evaluation in designing a user‐centered WebPAC interface.

Design/methodology/approach

Based on Nielsen's ten usability heuristic principles, the study focuses on three heuristics only, i.e. aesthetic and minimalist design, match between interface and the real world, and visibility of interface status.

Findings

Results of the study found that the WebPAC interface conforms to at least 70 percent usability properties prescribed. Usability problems violated in the interface were identified.

Practical implications

The study suggests that heuristic evaluation is applicable in libraries to asses the usability of user interface for online catalogs.

Originality/value

Heuristic evaluation could assist libraries in designing user‐centered interface for online catalogs.

Details

Library Hi Tech, vol. 25 no. 4
Type: Research Article
ISSN: 0737-8831

Keywords

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Book part
Publication date: 17 August 2017

Lars-Erik Gadde and Finn Wynstra

In a relationship both sides are important for the development. This is one reason why purchasing has always been as central as marketing in the empirical studies in IMP…

Abstract

In a relationship both sides are important for the development. This is one reason why purchasing has always been as central as marketing in the empirical studies in IMP. The manner in which the features of business networks affect the role of purchasing and the roles of the suppliers and supply management is here in focus. The existence and importance of business relationships have normative consequences for purchasing that are very distinct and break clearly with some of the traditional normative recommendations for purchasing. The authors believe that ‘buying organisations increasingly need to develop interactive interfaces with their suppliers. One reason is that collaborative innovation and therefore the development role of PSM (purchasing and supply management) is becoming more important’. The conclusion is clear: If the buying organisations want to get more out of the suppliers than the supply of a standard product at a certain price, they have to engage in a more extensive interaction and develop a broader and closer business relationship that must be properly managed. That implies giving up some autonomy and accepting dependence on suppliers as developmental partners.

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Book part
Publication date: 23 July 2014

Gertjan Schuiling

This chapter describes the change efforts and action research projects at a Dutch multinational which, over a period of 25 years, produced in one of its businesses a…

Abstract

This chapter describes the change efforts and action research projects at a Dutch multinational which, over a period of 25 years, produced in one of its businesses a zigzag path toward collaborative leadership dynamics at the horizontal and vertical interfaces. The chapter also identifies the learning mechanisms that helped achieve this transformation. Changing the patterns at the vertical interfaces proved to be a most tricky, complex, and confusing operation. The data show that organizations need hierarchical interfaces between levels, but are hindered by the hierarchical leadership dynamics at these interfaces. The data furthermore show that competitive performance requires more than redesigning horizontal interfaces. A business can only respond with speed and flexibility to threats and opportunities in the external environment when the leadership dynamics at agility-critical vertical interfaces are also changed.

Details

Research in Organizational Change and Development
Type: Book
ISBN: 978-1-78350-312-4

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