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The Handbook of Road Safety Measures
Type: Book
ISBN: 978-1-84855-250-0

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Article

P.C. Walsh and W.H. Leong

Heat transfer due to natural convection inside a closed cavity must be modeled to include the effects of turbulence if the Rayleigh number is sufficiently large. This…

Abstract

Heat transfer due to natural convection inside a closed cavity must be modeled to include the effects of turbulence if the Rayleigh number is sufficiently large. This study assesses the performance of several commonly used numerical turbulence models such as k‐ε, Renormalized Group k‐ε and Reynolds stress model, in predicting heat transfer due to natural convection inside an air‐filled cubic cavity. The cavity is maintained at 307 K on one side and 300 K on the opposite side with a linear temperature variation between these values on the remaining walls. Two cases are considered, one in which the heated side is vertical, and the other in which it is inclined at 45° from the horizontal. Rayleigh numbers of 107, 108, 109 and 1010 are considered. Results of the three turbulence models are compared to experimentally determined values or values from correlations. It was found that the standard k‐ε model was the most effective model in terms of accuracy and computational economy.

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International Journal of Numerical Methods for Heat & Fluid Flow, vol. 14 no. 5
Type: Research Article
ISSN: 0961-5539

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Article

Travis Lim, Chan-Hoong Leong and Farzaana Suliman

The purpose of this paper is to explore Singaporeans’ view to a multicultural neighbourhood, specifically, their views on the Ethnic Integration Policy (EIP), a housing…

Abstract

Purpose

The purpose of this paper is to explore Singaporeans’ view to a multicultural neighbourhood, specifically, their views on the Ethnic Integration Policy (EIP), a housing policy that promotes residential desegregation, and whether this policy has engendered a positive perspective to residential diversity.

Design/methodology/approach

A grounded theory approach is used to answer the following research questions: how do Singaporeans feel about residential diversity? Does the EIP influence attitudes to residential segregation in Singapore? What do these attitudes mean for governments and policymakers around the world? The research involved focus group discussions with 27 Housing and Development Board real estate agents, in order to tap onto their vast network of clients and better understand the prevailing sentiments on the ground.

Findings

The two major considerations when Singaporeans choose a flat are its price and location. Within the confines of these two factors, however, other considerations like race, nationality and the socio-economic makeup of a neighbourhood will influence their decisions.

Social implications

These considerations can be condensed into the factors of constrained choice and voluntary segregation. By limiting the impact of voluntary segregation, the EIP can be credited with bridging the racial divide. However, with constrained choice being unaddressed by the policy, the emerging formation of a class divide is an unintended consequence.

Originality/value

Because almost all developed economies are culturally plural, understanding Singapore’s approach to residential desegregation offers insights as to how other countries may learn from the Singapore experience in managing and encouraging multiculturalism, especially since ethnic residential concentration can reduce the formation of strong social relationships.

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Equality, Diversity and Inclusion: An International Journal, vol. 39 no. 2
Type: Research Article
ISSN: 2040-7149

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Book part

Mitja Kovac and Ann-Sophie Vandenberghe

This chapter provides comments and suggestions to the lawmaker, and especially to economic policy-makers in the field of the optimal regulatory framework and…

Abstract

This chapter provides comments and suggestions to the lawmaker, and especially to economic policy-makers in the field of the optimal regulatory framework and implementation of sustainable practices. The main findings are as follows: (1) degradation of the rule of law in several European Union (EU) Member States and constant political undermining of the legal institutions represent the main threat for the implementation of sustainable practices and development; (2) the golden regulatory rule of thumb provides that regulatory intervention is suggested merely in cases of market failures under the condition that the costs of such intervention do not exceed the benefits; (3) over-regulation might impede implementation of sustainable practices, distort the operation of the market, undermine productivity, diminish growth and social wealth and consequently also sustainability; (4) efficiency and wealth maximization should be the lawmaker’s leading normative principle in designing the legal framework that will enable effective implementation of sustainable practices; (5) the efficient level of harmonization or subsidiarity of decision-making in the EU urges for a rigorous investigation of costs and benefits of the EU top-down harmonization policies which should lead to a better, efficient vertical allocation of sustainability agenda between EU and the Member States; and (6) The Reflection Paper on Sustainable Development Goals – “Towards a Sustainable Europe in 2030” – represents an effective institutional framework in pursue of the overall sustainability targets.

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Challenges on the Path Toward Sustainability in Europe
Type: Book
ISBN: 978-1-80043-972-6

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Article

Mahmoud Salari, Mohammad Mehdi Rashidi, Emad Hasani Malekshah and Masoud Hasani Malekshah

Because the local Re numbers, ratio of inertia to viscous forces, are not same at different regions of the enclosures, the present study aims to deal with the influences…

Abstract

Purpose

Because the local Re numbers, ratio of inertia to viscous forces, are not same at different regions of the enclosures, the present study aims to deal with the influences of using the turbulent/transition models on numerical results of the natural convection and flow field within a trapezoidal enclosure.

Design/methodology/approach

The three-dimensional (3D) trapezoidal enclosure with different inclined side walls of 75, 90 and 105 degrees are considered, where the side walls are heated and cooled at Ra = 1.5 × 109 for all cases. The turbulent models of the k-ε-RNG, k- ω-shear-stress transport (SST) and the newly developed transition/turbulent model of Reθ-γ-transition SST are utilized to analyze the fluid flow and heat transfer characteristics within the enclosure and compared their results with validated results.

Findings

Comprehensive comparisons have been carried out for all cases in terms of flow and temperature fields, as well as turbulent quantities, such as turbulent kinetic energy and turbulent viscosity ratio. Furthermore, the velocity and thermal boundary layers have been investigated, and the approximate transition regions for laminar, transitional and turbulent regimes have been determined. Finally, the heat transfer coefficient and skin friction coefficient values have been presented and compared in terms of different turbulent models and configurations. The results show that the transition/turbulence model has better prediction for the flow and heat fields than fully turbulent models, especially for local parameters for all abovementioned governing parameters.

Originality value

The originality of this work is to analyze the 3D turbulent/transitional natural convection with different turbulence/transition models in a trapezoidal enclosure.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 12
Type: Research Article
ISSN: 0961-5539

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Article

Noureddine Abouricha, Mustapha El Alami and Khalid Souhar

The purpose of this paper is to model the convective flows in a room equipped by a glass door and a heated floor of length l = 0.8 × H and submitted to a sinusoidal…

Abstract

Purpose

The purpose of this paper is to model the convective flows in a room equipped by a glass door and a heated floor of length l = 0.8 × H and submitted to a sinusoidal temperature profile and mono alternative temperature profile.

Design/methodology/approach

The paper opts for a numerical study of convective flows in a large scale cavity using the Lattice Boltzmann Method (LBM) by considering a two dimensions (2D) square cavity of side H and filled by air (Pr = 0.71). All the vertical walls, the ceiling and the rest of the floor are thermally insulated, the hot portion of length l = 0.8×H is heated with two imposed temperature profiles of amplitude values 0.2 ≤  a  ≤ 0.6 and for two different periods ζ = ζ0 and ζ = 0.4×ζ0. One of the vertical walls has a cold portion θc = 0 that represents the glass door.

Findings

A systematic study of the flow structure and heat transfer is carried out considering principal control parameters: amplitude “a” and period ζ for Rayleigh number Ra = 108. Effects of these parameters on results are presented in terms of isotherms, streamlines, profiles of velocities, temperature in the cavity, global and local Nusselt number. It has been found that an increase in amplitude or period increases the amplitude of the temperature in the core of cavity. The Nusselt number increases when the amplitude “a” of the imposed temperature increases, but this later is not affected by variation of the period.

Originality/value

The authors used LBM to simulate the convective flows in a cavity at high Ra, heated from below by tow imposed temperature profiles. Indeed, they simulate a local equipped by a solar water heater (SWH). The floor is subjected to a periodic heating: Sinusoidal heating (Case 1) for which the temperature varies sinusoidally (SWH without a supplement), and mono alternation heating (Case 2), the temperature evolves like a redressed signal (SWH with a supplement). The considered method has been successfully validated and compared with the previous work. The study has been conducted using several control parameters such as the signal amplitude and period in the case of turbulent convection. This allowed us to obtain a considerable set of results that can be used for engineering.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

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Article

Shrimal Perera and Michael Skully

Since there is no agreement on the consistency of their estimates, the purpose of this paper is to investigate whether parametric stochastic frontier analysis (SFA) and…

Abstract

Purpose

Since there is no agreement on the consistency of their estimates, the purpose of this paper is to investigate whether parametric stochastic frontier analysis (SFA) and nonparametric data envelopment analysis (DEA) generate consistent bank efficiency assessments.

Design/methodology/approach

The authors utilize four alternative efficiency computation models: two DEA technical efficiency models based on constant and variable returns to scale, and two SFA cost efficiency models employing Translog and Fourier functional specifications. An unbalanced panel of 59 Indian banks over 1990‐2007 is employed as a model, developing country, banking market.

Findings

The Translog and Fourier specifications in SFA and the constant and variable returns to scale assumptions in DEA are found to rank and identify “best‐practice” and “worst‐practice” approximately in the same order. The association between DEA efficiency estimates and non‐frontier standard performance measures, however, is mixed and inconclusive. Unlike DEA scores, SFA efficiency assessments were found to be consistent with cost and profit ratios and hence are “believable”.

Practical implications

For regulators and bankers alike, the authors' findings highlight the importance of investigating the consistency of efficiency scores across various research methods. They should ensure that frontier‐based efficiency assessments are not simply “artificial constructs” of models' assumptions/specifications.

Originality/value

This paper extends the existing literature by checking jointly the statistical consistency of both DEA technical efficiency scores and SFA cost efficiency scores. The prior studies focus either on technical efficiency or cost efficiency, but not both. Moreover, as far as the authors are aware, this is the first cross‐methodological validation study to focus on bank efficiency in the context of a developing country banking market.

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Article

M.B. Vincent and C.P. Wong

This paper presents results on adding silane coupling agents to the underfill encapsulant to enhance the rheology and wetting of the underfill. These results include…

Abstract

This paper presents results on adding silane coupling agents to the underfill encapsulant to enhance the rheology and wetting of the underfill. These results include rheology measurements, contact angle measurements, and in situ flows using a simulated test chip on an FR4 with solder mask substrate. Three properties of the underfill encapsulant that can affect the mechanical reliability of the die and substrate assembly are: CTE; elastic modulus; and adhesion to the die and substrate surfaces. The approach taken in this paper is to add silane coupling agents with different chemistries to the underfill encapsulant to provide interfacial coupling of the underfill material to different die and substrate materials. This paper presents results on the enhancement of the adhesion of underfill encapsulant to silicon (Si), silicon nitride (SiN) die passivation, benzocyclobutene (BCB) die passivation, and solder mask surfaces. The adhesion strength was measured by die shear testing.

Details

Soldering & Surface Mount Technology, vol. 11 no. 3
Type: Research Article
ISSN: 0954-0911

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Article

Esmail M.A. Mokheimer

The aim of this article is to present the results of a parametric analysis of the entropy generation due to mixed convection in the entry‐developing region between two…

Abstract

Purpose

The aim of this article is to present the results of a parametric analysis of the entropy generation due to mixed convection in the entry‐developing region between two differentially heated isothermal vertical plates.

Design/methodology/approach

The entropy generation was estimated via a numerical solution of the mass, momentum and energy conservation equations governing the flow and heat transfer in the vertical channel between the two parallel plates. The resultant temperature and velocity profiles were used to estimate the entropy generation and other heat transfer parameters over a wide range of the operating parameters. The investigated parameters include the buoyancy parameter (Gr/Re), Eckert number (Ec), Reynolds number (Re), Prandtl number (Pr) and the ratio of the dimensionless temperature of the two plates (θT).

Findings

The optimum values of the buoyancy parameter (Gr/Re) optimum at which the entropy generation assumes its minimum for the problem under consideration have been obtained numerically and presented over a wide range of the other operating parameters. The effect of the other operating parameters on the entropy generation is presented and discussed as well.

Research limitations/implications

The results of this investigation are limited to the geometry of vertical channel parallel plates under isothermal boundary conditions. However, the concept of minimization of entropy generation via controlling the buoyancy parameter is applicable for any other geometry under any other thermal boundary conditions.

Practical implications

The results presented in this paper can be used for optimum designs of heat transfer equipment based on the principle of entropy generation minimization with particular focus on the optimum design of plate and frame heat exchanger and the optimization of electronic packages and stacked packaging of laminar‐convection‐cooled printed circuits.

Originality/value

This paper introduces the entropy generation minimization via controlling the operating parameters and clearly identifies the optimum buoyancy parameter (Gr/Re) at which entropy generation assumes its minimum under different operating conditions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 8
Type: Research Article
ISSN: 0961-5539

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Article

Walaa Wahid ElKelish and Mostafa Kamal Hassan

The main purpose of this paper is to investigate the relationship between organizational culture and corporate risk disclosure for listed companies in the United Arab…

Abstract

Purpose

The main purpose of this paper is to investigate the relationship between organizational culture and corporate risk disclosure for listed companies in the United Arab Emirates (UAE).

Design/methodology/approach

The organizational culture is represented by four dimensions: Clan, Adhocracy, Market and Hierarchy (Cameron and Quinn, 1999). Data are computed from the financial reports of all listed companies on the UAE Stock Market as of the year ending 2005. The multiple regression analysis model, ordinary least square, is used to test the study hypotheses.

Findings

Results show that the organizational culture of Hierarchy, which focuses on more formalized work procedures, has a significant positive effect on the companies’ risk disclosure in the UAE business environment. Several other control variables are implemented to ensure reliability of results.

Practical implications

Listed companies in the UAE are more responsive to formal rules and regulations on reporting risk disclosure, which is quite different from the “self-regulation” practices that are more common in some Western countries. Consequently, policymakers and regulators in the UAE, and in other countries with similar conditions, are encouraged to focus on continuous development of formal rules and procedures to enable more harmony with international best practices of risk disclosure.

Originality/value

Unlike the majority of previous empirical studies, this is the first study to incorporate a behavioral endogenous organizational culture model to explain the main determinants of risk disclosure, which opens the door for more understanding of the risk disclosure output function as a management process.

Details

International Journal of Commerce and Management, vol. 24 no. 4
Type: Research Article
ISSN: 1056-9219

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