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Book part
Publication date: 5 August 2015

Bob Caves

Abstract

Details

Airport Design and Operation
Type: Book
ISBN: 978-1-78441-869-4

Abstract

Details

Airport Design and Operation
Type: Book
ISBN: 978-1-78441-869-4

Article
Publication date: 2 May 2017

Ali Dinc

This paper aims to present a genuine code developed for multi-objective optimization of selected parameters of a turboprop unmanned air vehicle (UAV) for minimum landing-takeoff…

Abstract

Purpose

This paper aims to present a genuine code developed for multi-objective optimization of selected parameters of a turboprop unmanned air vehicle (UAV) for minimum landing-takeoff (LTO) nitrogen oxide (NOx) emissions and minimum equivalent power specific fuel consumption (ESFC) at loiter (aerial reconnaissance phase of flight) by using a genetic algorithm.

Design/methodology/approach

The genuine code developed in this study first makes computations on preliminary sizing of a UAV and its turboprop engine by analytical method for a given mission profile. Then, to minimize NOx emissions or ESFC or both of them, single and multi-objective optimization was done for the selected engine design parameters.

Findings

In single objective optimization, NOx emissions were reduced by 49 per cent from baseline in given boundaries or constraints of compressor pressure ratio and compressor polytropic efficiency in the first case. In second case, ESFC was improved by 25 per cent from baseline. In multi-objective optimization case, where previous two objectives were considered together, NOx emissions and ESFC decreased by 26.6 and 9.5 per cent from baseline, respectively.

Practical implications

Variation and trend in the NOx emission index and ESFC were investigated with respect to two engine design parameters, namely, compressor pressure ratio and compressor polytropic efficiency. Engine designers may take into account the findings of this study to reach a viable solution for the bargain between NOx emission and ESFC.

Originality/value

UAVs have different flight mission profiles or characteristics compared to manned aircraft. Therefore, they are designed in a different philosophy. As a number of UAV flights increase in time, fuel burn and LTO NOx emissions worth investigating due to operating costs and environmental reasons. The study includes both sizing and multi-objective optimization of an UAV and its turboprop engine in coupled form; compared to manned aircraft.

Details

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

Keywords

Article
Publication date: 1 February 2016

S. Ali Faghidian

The linear regression technique is widely used to determine empirical parameters of fatigue life profile while the results may not continuously depend on experimental data. Thus…

Abstract

Purpose

The linear regression technique is widely used to determine empirical parameters of fatigue life profile while the results may not continuously depend on experimental data. Thus Tikhonov-Morozov method is utilized here to regularize the linear regression results and consequently reduces the influence of measurement noise without notably distorting the fatigue life distribution. The paper aims to discuss these issues.

Design/methodology/approach

Tikhonov-Morozov regularization method would be shown to effectively reduce the influences of measurement noise without distorting the fatigue life distribution. Moreover since iterative regularization methods are known to be an attractive alternative to Tikhonov regularization, four gradient iterative methods called as simple iteration, minimum error, steepest descent and conjugate gradient methods are examined with an appropriate initial guess of regularized coefficients.

Findings

It has been shown that in case of sparse fatigue life measurements, linear regression results may not have continuous dependence on experimental data and measurement error could lead to misinterpretations of the solution. Therefore from engineering safety point of view, utilizing regularization method could successfully reduce the influence of measurement noise without significantly distorting the fatigue life distribution.

Originality/value

An excellent initial guess for mixed iterative-direct algorithm is introduced and it has been shown that the combination of Newton iterative approach and Morozov discrepancy principle is one of the interesting strategies for determination of regularization parameter having an excellent rate of convergence. Moreover since iterative methods are known to be an attractive alternative to Tikhonov regularization, four gradient descend methods are examined here for regularization of the linear regression problem. It has been found that all of gradient decent methods with an appropriate initial guess of regularized coefficients have an excellent convergence to Tikhonov-Morozov regularization results.

Details

International Journal of Structural Integrity, vol. 7 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Open Access
Article
Publication date: 3 June 2022

Peter Gangl, Stefan Köthe, Christiane Mellak, Alessio Cesarano and Annette Mütze

This paper aims to deal with the design optimization of a synchronous reluctance machine to be used in an X-ray tube, where the goal is to maximize the torque while keeping low…

Abstract

Purpose

This paper aims to deal with the design optimization of a synchronous reluctance machine to be used in an X-ray tube, where the goal is to maximize the torque while keeping low the amount of material used, by means of gradient-based free-form shape optimization.

Design/methodology/approach

The presented approach is based on the mathematical concept of shape derivatives and allows to obtain new motor designs without the need to introduce a geometric parametrization. This paper presents an extension of a standard gradient-based free-form shape optimization algorithm to the case of multiple objective functions by determining updates, which represent a descent of all involved criteria. Moreover, this paper illustrates a way to obtain an approximate Pareto front.

Findings

The presented method allows to obtain optimal designs of arbitrary, non-parametric shape with very low computational cost. This paper validates the results by comparing them to a parametric geometry optimization in JMAG by means of a stochastic optimization algorithm. While the obtained designs are of similar shape, the computational time used by the gradient-based algorithm is in the order of minutes, compared to several hours taken by the stochastic optimization algorithm.

Originality/value

This paper applies the presented gradient-based multi-objective optimization algorithm in the context of free-form shape optimization using the mathematical concept of shape derivatives. The authors obtain a set of Pareto-optimal designs, each of which is a shape that is not represented by a fixed set of parameters. To the best of the authors’ knowledge, this approach to multi-objective free-form shape optimization is novel in the context of electric machines.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 10 November 2014

Joshua Floyd

This paper aims to make the case for continued opportunity for high levels of human well-being under descent conditions characterised by declining economic throughput and…

Abstract

Purpose

This paper aims to make the case for continued opportunity for high levels of human well-being under descent conditions characterised by declining economic throughput and socio-political complexity.

Design/methodology/approach

Relationships between assumptions about human well-being formed within a modern industrial context, the guiding narratives attending these, and the broader cultural influence of ideas from the evolutionary sciences are examined. Alternative ways of making sense of these relationships are explored. The experiences of societies guided by cultural narratives based on different premises to those most influential in industrial societies are reviewed for their implications for human well-being under descent conditions.

Findings

Human experiences of well-being are principally a function of the sources of meaning and associated narratives by which members of a culture make sense of their situation, as these determine the nature of the material and energetic conditions required to live well. Under descent conditions, the narrative of progress that has supported viable societies during the 300-year period of industrial expansion is unlikely to continue serving humanity well. Collective participation in the renewal of guiding cultural narratives is a primary target for efforts to provide continued opportunities for high quality of life to all members of humanity.

Practical implications

The findings point towards specific characteristics of cultural sense-making narratives that may support viable human societies under descent conditions.

Social implications

By moving beyond the default assumption that descent automatically implies decline in human well-being, a barrier may be lowered to more open and mature society-wide engagement in conversations about the present human predicament and effective ways of responding to it.

Originality/value

New connections are identified between perspectives based on biological evolutionary theory and the continued influence of the idea of progress in establishing default assumptions about prospects for human well-being under descent conditions. Experiences of non-industrial societies are taken as the basis for identifying opportunities for human well-being under far more modest material and energetic conditions than those available to the portion of humanity that presently enjoys benefits of industrial development that outweigh the attendant costs.

Details

foresight, vol. 16 no. 6
Type: Research Article
ISSN: 1463-6689

Keywords

Article
Publication date: 7 March 2016

Petros Vourvachis, Thérèse Woodward, David G. Woodward and Dennis M Patten

The purpose of this paper is to contribute to the literature investigating disclosure reactions to legitimacy threats by analyzing the corporate social responsibility (CSR…

1964

Abstract

Purpose

The purpose of this paper is to contribute to the literature investigating disclosure reactions to legitimacy threats by analyzing the corporate social responsibility (CSR) disclosure reactions to catastrophic accidents suffered by major airlines.

Design/methodology/approach

The authors use content analysis to examine changes in annual report disclosure in response to four separate airline disasters. The authors adopt two classification schemes and two measurement approaches to explore these changes.

Findings

The authors find that for three events the organizations appear to have responded with considerable increases in CSR disclosure that are consistent with attempts of legitimation. For one of the events examined, the authors find no disclosure response and suggest that this could be due to the company’s unwillingness to accept responsibility.

Research limitations/implications

The study’s focus on major airlines that have suffered an accident with available annual reports in English meant that other companies had to be excluded from the analysis.

Practical implications

The findings demonstrate the use of the annual report as a legitimation tool and further highlight the need for greater transparency and comparability across publications.

Originality/value

The paper adds to the scarce literature examining corporate disclosure reactions following threats to their social legitimacy.

Details

Sustainability Accounting, Management and Policy Journal, vol. 7 no. 1
Type: Research Article
ISSN: 2040-8021

Keywords

Article
Publication date: 11 August 2021

Irappa Basappa Hunagund, V. Madhusudanan Pillai and Kempaiah U.N.

The purpose of this paper is to review, evaluate and classify the academic research that has been published in facility layout problems (FLPs) and to analyse how researches and…

Abstract

Purpose

The purpose of this paper is to review, evaluate and classify the academic research that has been published in facility layout problems (FLPs) and to analyse how researches and practices on FLPs are.

Design/methodology/approach

The review is based on 166 papers published from 1953 to 2021 in international peer-reviewed journals. The literature review on FLPs is presented under broader headings of discrete space and continuous space FLPs. The important formulations of FLPs under static and dynamic environments represented in the discrete and continuous space are presented. The articles reported in the literature on various representations of facilities for the continuous space Unequal Area Facility Layout Problems (UA-FLPs) are summarized. Discussed and commented on adaptive and robust approaches for dynamic environment FLPs. Highlighted the application of meta-heuristic solution methods for FLPs of a larger size.

Findings

It is found that most of the earlier research adopted the discrete space for the formulation of FLPs. This type of space representation for FLPs mostly assumes an equal area for all facilities. UA-FLPs represented in discrete space yield irregular shape facilities. It is also observed that the recent works consider the UA-FLPs in continuous space. The solution of continuous space UA-FLPs is more accurate and realistic. Some of the recent works on UA-FLPs consider the flexible bay structure (FBS) due to its advantages over the other representations. FBS helps the proper design of aisle structure in the detailed layout plan. Further, the recent articles reported in the literature consider the dynamic environment for both equal and unequal area FLPs to cope with the changing market environment. It is also found that FLPs are Non-deterministic Polynomial-complete problems, and hence, they set the challenges to researchers to develop efficient meta-heuristic methods to solve the bigger size FLPs in a reasonable time.

Research limitations/implications

Due to the extremely large number of papers on FLPs, a few papers may have inadvertently been missed. The facility layout design research domain is extremely vast which covers other areas such as cellular layouts, pick and drop points and aisle structure design. This research review on FLPs did not consider the papers published on cellular layouts, pick and drop points and aisle structure design. Despite the possibility of not being all-inclusive, the authors firmly believe that most of the papers published on FLPs are covered and the general picture presented on various approaches and parameters of FLPs in this paper are precise and trustworthy.

Originality/value

To the best of the authors’ knowledge, this paper reviews and classifies the literature on FLPs for the first time under the broader headings of discrete space and continuous space representations. Many important formulations of FLPs under static and dynamic environments represented in the discrete and continuous space are presented. This paper also provides the observations from the literature review and identifies the prospective future directions.

Article
Publication date: 13 May 2020

Álvaro Rodríguez-Sanz, Cecilia Claramunt Puchol, Javier A. Pérez-Castán, Fernando Gómez Comendador and Rosa M. Arnaldo Valdés

The current air traffic management (ATM) operational approach is changing; “time” is now integrated as an additional fourth dimension on trajectories. This notion will impose on…

Abstract

Purpose

The current air traffic management (ATM) operational approach is changing; “time” is now integrated as an additional fourth dimension on trajectories. This notion will impose on aircraft the compliance of accurate arrival times over designated checkpoints (CPs), called time windows (TWs). This paper aims to clarify the basic requirements and foundations for the practical implementation of this functional framework.

Design/methodology/approach

This paper reviews the operational deployment of 4D trajectories, by defining its relationship with other concepts and systems of the future ATM and communications, navigation and surveillance (CNS) context. This allows to establish the main tools that should be considered to ease the application of the 4D-trajectories approach. This paper appraises how 4D trajectories must be managed and planned (negotiation, synchronization, modification and verification processes). Then, based on the evolution of a simulated 4D trajectory, the necessary corrective measures by evaluating the degradation tolerances and conditions are described and introduced.

Findings

The proposed TWs model can control the time tolerance within less than 100 s along the passing CPs of a generic trajectory, which is in line with the expected future ATM time-performance requirements.

Originality/value

The main contribution of this work is the provision of a holistic vision of the systems and concepts that will be necessary to implement the new 4D-trajectory concept efficiently, thus enhancing performance. It also proposes tolerance windows for trajectory degradation, to understand both when an update is necessary and what are the conditions required for pilots and air traffic controllers to provide this update.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 9
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 November 1955

J.S. Shapiro

THE reason for using the helicopter in transport is neither its performance nor its own cost, but the nature and design of its operating site. To separate the two, as is sometimes…

Abstract

THE reason for using the helicopter in transport is neither its performance nor its own cost, but the nature and design of its operating site. To separate the two, as is sometimes done in discussions of comparative merits of helicopters and aeroplanes, is clearly a futile exercise.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 11
Type: Research Article
ISSN: 0002-2667

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