Search results

The purpose of this paper is to present a complex pyrolysis computational fluid dynamics (CFD) model of timber protection exposed to fire in a medium size enclosure. An emphasis is placed on rarely used temperature-dependent thermal material properties effecting the overall simulation outputs. Using the input dataset, a fire test model with oriented strand boards (OSB) in the room corner test facility is created in Fire Dynamics Simulator (FDS).

Seven FDS models comprising different complexity approaches to modelling the burning of wood-based materials, from a simplified model of burning based on a prescribed heat release rate to complex pyrolysis models which can describe the fire spread, are presented. The models are validated by the experimental data measured during a fire test of OSB in the room corner test facility.

The use of complex pyrolysis approach is recommended in real-scale enclosure fire scenarios with timber as a supplementary heat source. However, extra attention should be paid to burning material thermal properties implementation. A commonly used constant specific heat capacity and thermal conductivity provided poor agreement with experimental data. When the fire spread is expected, simplified model results should be processed with great care and the user should be aware of possible significant errors.

This paper brings an innovative and rarely used complex pyrolysis CFD model approach to predict the behaviour of timber protection exposed to fire. A study on different temperature-dependent thermal material properties combined with multi-step pyrolysis in the room corner test scenario has not been sufficiently published and validated yet.

Recently, the original Wavenumber approach was introduced for dynamic analysis of dam-reservoir systems in frequency domain in the context of pure finite element programming. But its main disadvantages are that it cannot be implemented in time domain. The purpose of this paper is to propose an approximation to the original approach which enables one to carry out this effective method in time domain as well as in frequency domain. Based on the present investigation, it is proven that the Approximate Wavenumber approach has inherent characteristics, which allows it to be envisaged as an effective technique for calculating the response of concrete gravity dam-reservoir systems in time domain.

The method is described initially. Subsequently, the response of an idealized triangular dam-reservoir system is obtained by the proposed approach as well as by applying two other well-known absorbing conditions which are widely utilized in practice. The results are also controlled against the corresponding exact responses. It should be emphasized that all results presented herein are obtained by the FE-FE method under different absorbing conditions applied on the truncation boundary. These include two well-known absorbing conditions referred to as Sommerfeld and Sharan as well as the proposed approach of the present study (i.e. Approximate Wavenumber condition).

It is concluded that the maximum error for the Approximate Wavenumber approach is in the range of 10 percent at the major peaks of the response. This occurs mainly for the very low reservoir lengths under full reflective reservoir base condition and vertical excitation. This is a remarkable result for any kind of robust truncation boundary simulation that one may expect. The fundamental frequency of the system is captured correctly for the Approximate Wavenumber approach, even in cases of low reservoir length.

Based on this investigation, it is proven that the Approximate Wavenumber approach has inherent characteristics, which allows it to be envisaged as an effective technique for calculating the response of concrete gravity dam-reservoir systems in time domain. It is concluded that the maximum error for the Approximate Wavenumber approach is in the range of 10 percent at the major peaks of the response. This occurs mainly for the very low reservoir lengths under full reflective reservoir base condition and vertical excitation. This is a remarkable result for any kind of robust truncation boundary simulation that one may expect.

Suggests that a number of difficulties are experienced by organizations using conventional risk analysis and management. “Conventional” refers to those methodologies which are based on the traditional asset/threat/vulnerability model. Identifies a need for an approach that is more suitable for smaller organizations, as well as organizations requiring a quicker, more simplified and less resource‐intensive approach. In light of this requirement, proposes an alternative approach to effective information technology (IT) risk analysis and management. This approach has a business‐oriented focus from an IT perspective.

Preface The functions of business divide into several areas and the general focus of this book is on one of the most important although least understood of these—DISTRIBUTION. The particular focus is on reviewing current practice in distribution costing and on attempting to push the frontiers back a little by suggesting some new approaches to overcome previously defined shortcomings.

The purpose of this paper is to originate a proactive approach for the quantification and analysis of liquidity risk for trading portfolios that consist of multiple equity assets.

The paper presents a coherent modeling method whereby the holding periods are adjusted according to the specific needs of each trading portfolio. This adjustment can be attained for the entire portfolio or for any specific asset within the equity trading portfolio. This paper extends previous approaches by explicitly modeling the liquidation of trading portfolios, over the holding period, with the aid of an appropriate scaling of the multiple‐assets' liquidity‐adjusted value‐at‐risk matrix. The key methodological contribution is a different and less conservative liquidity scaling factor than the conventional root‐t multiplier.

The proposed coherent liquidity multiplier is a function of a predetermined liquidity threshold, defined as the maximum position which can be unwound without disturbing market prices during one trading day, and is quite straightforward to put into practice even by very large financial institutions and institutional portfolio managers. Furthermore, it is designed to accommodate all types of trading assets held and its simplicity stems from the fact that it focuses on the time‐volatility dimension of liquidity risk instead of the cost spread (bid‐ask margin) as most researchers have done heretofore.

Using more than six years of daily return data, for the period 2004‐2009, of emerging Gulf Cooperation Council (GCC) stock markets, the paper analyzes different structured and optimum trading portfolios and determine coherent risk exposure and liquidity risk premium under different illiquid and adverse market conditions and under the notion of different correlation factors.

This paper fills a main gap in market and liquidity risk management literatures by putting forward a thorough modeling of liquidity risk under the supposition of illiquid and adverse market settings. The empirical results are interesting in terms of theory as well as practical applications to trading units, asset management service entities and other financial institutions. This coherent modeling technique and empirical tests can aid the GCC financial markets and other emerging economies in devising contemporary internal risk models, particularly in light of the aftermaths of the recent sub‐prime financial crisis.

Explores the practical and theoretical issues involved in the evaluation, quality assurance and engagement of operating an e‐learning programme as a distance learning service on an international basis for people in employment. Focuses on the experiences of delivery of e‐learning of a case at the University of Wales, Lampeter that has been adapted from a project into mainstream provision. Suggests that the current emphasis of the prefix “e” in learning application needs to shift from electronic to the more supportive descriptions of engagement, enhancement and execution of the student learning programme. Reviews the current quality assurance recommendations in the context of e‐learning. Concludes with the evidence emerging from the particular case of e‐learning provision at Lampeter and the key findings of the programme.

This paper deals with experimental and numerical investigations of the composite behaviour within concrete-filled tubular columns with embedded massive steel core (CFTES columns). As the inner profile provides the main load-bearing capacity, the load introduction and transfer is of particular interest for the structural detailing of CFTES columns. Currently, no specific design regulations are available – neither for room temperature nor fire design. The presented investigations provide a basis for design recommendations and numerical approaches on reliable shear stresses.

Three series of push-out tests at room temperature and high temperatures are analysed in terms of ultimate shear strength, bond strength and shear strength-displacement-curve shape. The test parameters involve the steel core diameter and concrete cover, applying normal strength steel and concrete. Furthermore, a three-dimensional finite element model of the push-out tests is set up in Abaqus. The model implies temperature-dependent contact properties derived from the experimental tests using the cohesive behaviour method.

The test data reveal a distinctive reduction in both ultimate shear and bond strength for high temperatures. For high temperatures, the thermal expansion coefficients dominate the composite behaviour. Using the 3D numerical model and applying a temperature-dependent joint stiffness, maximum shear stress criterion and damage evolution, the observed composite behaviour can be described in a realistic manner.

The presented experimental investigations are unique, both concerning the investigated column type and performing push-out tests at high temperatures. For the first time, a temperature-dependent reduction of capable shear stresses is identified, which is crucial for the design of structural components.

This study aims to carry out an investigation of design approaches that should be used for the design of unconventional, innovative transmission system for construction yards to privilege a smooth behaviour efficiency, and the use of innovative production techniques. Results are quite surprising, as with a proper method it is possible to demonstrate that a cycloidal drive with Wolfrom topology should be an interesting solution for the proposed application.

With a functional approach, also considering materials and specifications related to the investigated application, it is possible to demonstrate that possible optimal solutions should be quite different respect to the ones that can be suggested with a conventional approach. In particular for proposed applications constraints related to encumbrances, the choice of new material has led to the innovative unconventional choice of a Wolfrom cycloidal speed reducer.

Provided solution is innovative respect current state of the art for machine currently used in construction yards: in terms of adopted transmission layout; in terms of chosen materials, resulting in an innovative solution.

Current research has strong implications on the adoption of polimeric materials for the construction of reliable transmission for harsh industrial environment as the proposed case study (concrete mixer for construction yard).

Proposed transmission system is absolutely original and innovative respect current state of art also considering proposed materials and consequently production methods. This is an example of transmission designed to be built with polymeric materials by optimizing chosen topology respect to chosen material.

This paper advances the specification and estimation of econometric models of retirement and saving in two earner families. The complications introduced by the interaction of retirement decisions by husbands and wives have led researchers to adopt a number of simplifications. Our analysis relaxes these restrictions. The model includes three labor market states, full-time work, partial retirement, and full retirement; reverse flows from states of lesser to greater work; an extended choice set created when spouses make independent retirement decisions; heterogeneity in time preference; varying taste parameters for full-time and part-time work; and the possibility of changes in preferences after retirement.

The purpose of this empirical case study is to apply several existing frameworks to consider the notion of integrating corporate social responsibility (CSR) with a brand leadership strategy. The investigation focuses on two main questions: What are the core components for the development of a CSR brand? What capabilities are necessary to implement a CSR‐related brand strategy?

Five firms provide input for a multiple case‐based approach.

Intuitive and intended approaches for CSR brand leadership emerge from the multiple case study results. Different capabilities are required at each stage of the development and implementation process for CSR brand leadership.

This research extends three prior studies – Aaker and Joachimsthaler's brand leadership framework, Maon et al.'s proposed integrative framework for designing and implementing CSR, and Beverland et al.'s capabilities view on the development of global brand leadership – and fills a theoretical gap.

Managers can use the proposed integrated and implementable framework to determine the impact of dynamic factors, such as ownership, culture, executive leadership, and the specific context of product and corporate branding, on the development and implementation of their CSR brand.

No studies examine how to leverage CSR in brand‐building activities. Specifically, no empirically grounded research examines the required path to create and manage CSR brands and associated benefits, nor is the number of capabilities required to develop a credible CSR brand clear. Comprehensive models of the processes for developing and implementing CSR brands and the capabilities that underlie them are needed. The proposed model emphasizes the contextualized need to rely on different capabilities at different stages of this development process to generate constructive and sustainable outcomes.