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Article

M. Poursina, C.A.C. António, C.F. Castro, J. Parvizian and L.C. Sousa

A numerical method for shape optimisation in forging is presented. The goal of the optimisation is to eliminate work‐piece defects that may arise during the forging…

Abstract

A numerical method for shape optimisation in forging is presented. The goal of the optimisation is to eliminate work‐piece defects that may arise during the forging process. A two‐dimensional finite element code has been developed for the simulation of the mechanical process. The material is incompressible and it follows the Norton‐Hoff law. To deal with contact constraint the velocity projection algorithm is used. The optimisation process is conducted using a genetic algorithm supported by an elitist strategy. A new genetic operator called adaptive mutation has been developed to increase the efficiency of the search. The developed scheme is used to design optimal preform shapes for several axisymmetric examples. Continuous and discrete design variables are considered. The objective function of the optimisation problem is associated with the quality of the final product. Comparing the obtained optimal results with the literature validates the proposed optimisation method.

Details

Engineering Computations, vol. 21 no. 6
Type: Research Article
ISSN: 0264-4401

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Article

Catarina F. Castro, Luísa Costa Sousa, C.A.C. António and J.M.A. César de Sá

An optimisation method for design of intermediate die shapes needed in some forging operations is presented. The basic problem consists of finding an optimal two‐step…

Abstract

An optimisation method for design of intermediate die shapes needed in some forging operations is presented. The basic problem consists of finding an optimal two‐step forging sequence by automatically designing the shape of the preforming tools. The optimisation problem is defined based on an inverse formulation. The objective function of the optimisation problem is a function describing the quality of the obtained part by measuring the die underfill. The finite element method is used to simulate the forging problem. The optimisation method is based on a modified sequential unconstrained minimisation technique and a gradient method. The sensitivity‐dependent algorithm requires computing the derivatives of the objective function with respect to the design variables defining the preform shapes. A direct differentiation method has been developed for this purpose. The optimisation scheme is demonstrated with two axisymmetric forging examples in which optimal preform dies are obtained.

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Engineering Computations, vol. 18 no. 8
Type: Research Article
ISSN: 0264-4401

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Article

Conceição Castro, Fernanda A. Ferreira and Flávio Ferreira

The aim of this paper is to analyze and compare the effect of different hotel characteristics and room attributes on room rates of hotels in the cities of Lisbon and…

Abstract

Purpose

The aim of this paper is to analyze and compare the effect of different hotel characteristics and room attributes on room rates of hotels in the cities of Lisbon and Porto, the capital and second most important city in Portugal.

Design/methodology/approach

Using the hedonic pricing method, hotel characteristics are decomposed and analyzed, giving us the perception of the impact of each hotel attributes on the room rates and the people’s willingness to pay for this. Ordinary least square regression analysis was applied to the hedonic price model to find which variables could explain differences in the hotel room rates in Lisbon and Porto.

Findings

The results suggest that in Lisbon and in Porto, a number of common characteristics have significant effects on consumer willingness to pay for a stay in a hotel as star rating, consumer rating and the room size. In Porto, the existence of a fitness centre and in Lisbon, the distance to the city centre are also attributes that create a premium in room rates.

Practical implications

The knowledge of the most valued characteristics by consumers is an important tool for hotel managers to define a price strategy. Also important is the knowledge of the attributes that provide more added value for consumers as these should be taken into account in new investment decisions.

Originality/value

This study highlights the implications of the way one defines and measures qualitative hotel characteristics in hedonic pricing. Although the hedonic method has been applied in several studies, to our knowledge, in Portugal, there are few studies applied only to hotel room rates, and there are no studies comparing hotel room rates in different Portuguese cities. Moreover, the research highlights the critical role of a proper definition and measurement of the variables in hedonic pricing in general and the hotel star in particular.

Details

Worldwide Hospitality and Tourism Themes, vol. 8 no. 6
Type: Research Article
ISSN: 1755-4217

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Book part

Abstract

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Advances in Positive Organizational Psychology
Type: Book
ISBN: 978-1-78052-000-1

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Article

A.R. Khoei, Sh. Keshavarz and A.R. Khaloo

The purpose of this paper is to present a shape optimization technique for powder forming processes based on the genetic algorithm approach. The genetic algorithm is…

Abstract

Purpose

The purpose of this paper is to present a shape optimization technique for powder forming processes based on the genetic algorithm approach. The genetic algorithm is employed to optimize the geometry of component based on a fixed‐length vector of design variables representing the changes in nodal coordinates. The technique is used to obtain the desired optimal compacted component by changing the boundaries of component and verifying the prescribed constraints.

Design/methodology/approach

The numerical modeling of powder compaction simulation is applied based on a large deformation formulation, powder plasticity behavior, and frictional contact algorithm. A Lagrangian finite element formulation is employed for large powder deformations. A cap plasticity model is used in numerical simulation of nonlinear powder behavior. The influence of powder‐tool friction is simulated by the use of penalty approach in which a plasticity theory of friction is incorporated to model sliding resistance at the powder‐tool interface.

Findings

Finally, numerical examples are analyzed to demonstrate the feasibility of the proposed optimization algorithm for designing powder components in the forming process of powder compaction.

Originality/value

A shape optimization technique is presented for powder forming processes based on the genetic algorithm approach.

Details

Engineering Computations, vol. 27 no. 3
Type: Research Article
ISSN: 0264-4401

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Book part

Tim Urdan, Neha Sharma and Marli Dunn

A strong anti-immigrant and anti-refugee sentiment permeates the political discourse in the United States and many Western European countries. This political discourse…

Abstract

A strong anti-immigrant and anti-refugee sentiment permeates the political discourse in the United States and many Western European countries. This political discourse, along with policies designed to limit immigration, is likely to influence the academic motivation of students from immigrant groups. In this chapter, we consider how anti-immigrant sentiment in the host countries may affect the motivation and achievement of immigrant and refugee students. Specifically, we apply findings from research examining stress and anxiety, belonging, identity, teacher expectancies, and stereotype threat to speculate about how these motivational factors may be affected by anti-immigrant rhetoric. Next, we use Maehr’s (1984) theory of personal investment (PI) as a framework for integrating the various components of motivation that can be applied to the current plight of immigrant and refugee students. The chapter concludes with a brief discussion about the steps we can take, both at the personal and the policy levels, to counteract the hostile political discourse and promote higher levels of PI in education among immigrant and refugee students.

Details

Motivation in Education at a Time of Global Change
Type: Book
ISBN: 978-1-78754-613-4

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Book part

Abstract

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Transitions in Latin America and in Poland and Syria
Type: Book
ISBN: 978-1-84950-469-0

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Article

J.T. Hong, S.R. Lee, C.H. Park and D.Y. Yang

In the finite element analysis of a hot forging process, it is difficult to design an optimal preform because of highly nonlinear characteristics of design variables. In…

Abstract

Purpose

In the finite element analysis of a hot forging process, it is difficult to design an optimal preform because of highly nonlinear characteristics of design variables. In this paper, a new preform design method which can reduce the forming load and the die wear by removing the flash is developed and applied to the pre form design of a piston.

Design/methodology/approach

After finite element analyses of hot forging processes, if the final product is found to have excessive flash and cause high die wear, a new preform design technique, so‐called iterative preform design technique is applied to obtain an optimal preform design. From the results of FE simulations, a boundary region at the outlet of the flash is first selected. Then, by tracing the section along the deformation path to the initial billet, it is possible to obtain a mapped section boundary in the initial billet. After updating the initial shape by removing the exterior region of the mapped section boundary, a finite element simulation is carried out with the updated initial shape. Iterations should be continued until a desired result is obtained.

Findings

It has been confirmed that the proposed preform design technique has a negligible effect on the initial forgeability of the workpiece. It is expected that the tool life will be increased, because the forming load and die wear are reduced as the number of iterations are increased. Moreover, because the preform design reduces the flash, it thereby reduces the waste of material.

Originality/value

In the 3D finite element analysis of a hot forging process, several optimal preform design techniques have been developed. However, it is difficult to use the techniques in general problems because it is difficult to formulate cost functions, which mainly depend on the experience and physical insight of the designer. In addition, tremendous time is consumed in optimizing a problem as a large number of iterations are required in minimizing the objective function. The proposed preform design technique is simple enough to apply to general hot forging problems involving excessive flash. The proposed preform design technique is an offline method and easy to apply to any other analysis program, including commercial programs.

Details

Engineering Computations, vol. 23 no. 1
Type: Research Article
ISSN: 0264-4401

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Book part

Elricke Botha

The aim of this chapter is to provide the readers with a brief background to the characteristics of tourism and a synoptic presentation of the main trends in tourism…

Abstract

Purpose

The aim of this chapter is to provide the readers with a brief background to the characteristics of tourism and a synoptic presentation of the main trends in tourism markets and challenges that tourism businesses should deal with.

Methodology/approach

A literature review was conducted on the relevant trends that can affect the management and marketing of tourism businesses. Micro case studies were also presented as practical examples of how tourism businesses have adapted to trends.

Findings

This chapter highlights the specific characteristics of the tourism industry, as well as the trends in the market/business environment. Tourism businesses need to remain aware of trends and find solutions to adapt their services and activities to take advantage of them.

Research limitations/implications

This chapter is explorative in nature because it has made used of extant literature.

Practical implications

Tourism entrepreneurs are encouraged to stay abreast of changes in the business environment. Some of the examples provided may only be applicable in the short run but other examples have long-term impact. Valuable solutions are provided for consideration.

Originality/value

This chapter analyses several trends affecting the tourism industry from management and marketing perspectives. This analysis gives a better understanding of how these trends specifically affect tourism. This chapter highlights the importance of monitoring the trends and their evolution in the various markets.

Details

The Emerald Handbook of Entrepreneurship in Tourism, Travel and Hospitality
Type: Book
ISBN: 978-1-78743-529-2

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Article

Alina Morawska and Matthew Sanders

Despite the importance of increasing engagement and minimising attrition and drop‐out in parenting interventions, there is a paucity of empirical evidence examining…

Abstract

Despite the importance of increasing engagement and minimising attrition and drop‐out in parenting interventions, there is a paucity of empirical evidence examining factors related to engagement and participation. The range of factors examined in relation to engagement is generally limited in scope and variety, focusing on variables of convenience rather than utilising a theoretically‐driven approach.The aim of this article is to review the factors related to parental engagement with interventions and to describe strategies and implications for improving engagement with parenting interventions. Several policy and practice implications are identified: (1) Poor parental engagement may threaten or compromise the capacity of parenting programmes to deliver valued outcomes. Viable engagement strategies need to be a core part of prevention and early intervention parenting programmes; (2) Agencies delivering parenting services need a proactive engagement strategy, which includes strategies to prevent drop‐out, as well as strategies to actively respond to parental disengagement; (3) Research is needed to test the efficacy and robustness of different engagement enhancement strategies. Empirical tests are needed to test the effectiveness of different engagement strategies in order to ensure that the most efficient, cost‐effective and efficacious approach is used in order to engage parents. Investment of research effort to improve parental engagement is likely to have a high yield in terms of programme efficiency, utility and cost effectiveness. We conclude that research examining how to improve engagement and decrease non‐completion is needed to strengthen the population level value of parenting programmes as preventive interventions.

Details

Journal of Children's Services, vol. 1 no. 1
Type: Research Article
ISSN: 1746-6660

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