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Article
Publication date: 10 July 2007

Ranjan Ganguli, Beatrix Jehnert, Jens Wolfram and Peter Voersmann

To investigate the use of centre of gravity location on reducing cyclic pitch control for helicopter UAV's (unmanned air vehicles) and MAV's (micro air vehicles). Low…

Abstract

Purpose

To investigate the use of centre of gravity location on reducing cyclic pitch control for helicopter UAV's (unmanned air vehicles) and MAV's (micro air vehicles). Low cyclic pitch is a necessity to implement the swashplateless rotor concept using trailing edge flaps or active twist using current generation low authority piezoceramic actuators.

Design/methodology/approach

An aeroelastic analysis of the helicopter rotor with elastic blades is used to perform parametric and sensitivity studies of the effects of longitudinal and lateral center of gravity (cg) movements on the main rotor cyclic pitch. An optimization approach is then used to find cg locations which reduce the cyclic pitch at a given forward speed.

Findings

It is found that the longitudinal cyclic pitch and lateral cyclic pitch can be driven to zero at a given forward speed by shifting the cg forward and to the port side, respectively. There also exist pairs of numbers for the longitudinal and lateral cg locations which drive both the cyclic pitch components to zero at a given forward speed. Based on these results, a compromise optimal cg location is obtained such that the cyclic pitch is bounded within ±5° for a BO105 helicopter rotor.

Originality/value

The reduction in the cyclic pitch due to helicopter cg location is found to significantly reduce the maximum magnitudes of the control angles in flight, facilitating the swashplateless rotor concept. In addition, the existence of cg locations which drive the cyclic pitches to zero allows for the use of active cg movement as a way to replace the cyclic pitch control for helicopter MAV's.

Details

Aircraft Engineering and Aerospace Technology, vol. 79 no. 4
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 25 September 2009

Anette Rohmann and Jens Rowold

The purpose of this paper is to analyze whether German male and female leaders differ in their leadership behavior, focusing on transactional vs transformational leadership styles.

Abstract

Purpose

The purpose of this paper is to analyze whether German male and female leaders differ in their leadership behavior, focusing on transactional vs transformational leadership styles.

Design/methodology/approach

A field study in which followers were asked to evaluate their respective leaders was conducted in three different organizational contexts in Germany using questionnaires: a recreational sports club (n = 183), a government agency (n = 267), and a public transport services company (n = 203). Additionally, students (n = 518) were asked to evaluate historical world‐class leaders in terms of their leadership styles after a standardized presentation of their life and leadership style using biographies, essays, and movies.

Findings

Results in all four samples show that female leaders were perceived as exhibiting more transformational leadership behavior than male leaders. Moreover, female leaders were evaluated as more effective and as producing more satisfaction than their male counterparts.

Research limitations/implications

Self‐report data were used and leadership was assessed from the perspective of the followers. Future research should also include leaders' and peers' perspectives.

Originality/value

The finding that women have a more transformational leadership style than men is extended to another cultural context. The importance of analyzing different organizational contexts is highlighted.

Details

Equal Opportunities International, vol. 28 no. 7
Type: Research Article
ISSN: 0261-0159

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Abstract

Details

Punk, Gender and Ageing: Just Typical Girls?
Type: Book
ISBN: 978-1-83982-568-2

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Article
Publication date: 11 September 2009

P. Enciu, F. Wurtz, L. Gerbaud and B. Delinchant

The purpose of this paper is to illustrate automatic differentiation (AD) as a new technology for the device sizing in electromagnetism by using gradient constrained…

Abstract

Purpose

The purpose of this paper is to illustrate automatic differentiation (AD) as a new technology for the device sizing in electromagnetism by using gradient constrained optimization. Component architecture for the design of engineering systems (CADES) framework, previously described, is presented here with extended features.

Design/methodology/approach

The paper is subject to further usage for optimization of AD (also named algorithmic differentiation) which is a powerful technique that computes derivatives of functions described as computer programs in a programming language like C/C++, FORTRAN.

Findings

Indeed, analytical modeling is well suited regarding optimization procedure, but the modeling of complex devices needs sometimes numerical formulations. This paper then reviews the concepts implemented in CADES which aim to manage the interactions of analytical and numerical modeling inside of gradient‐based optimization procedure. Finally, the paper shows that AD has no limit for the input program complexity, or gradients accuracy, in the context of constrained optimization of an electromagnetic actuator.

Originality/value

AD is employed for a large and complex numerical code computing multidimensional integrals of functions. Thus, the paper intends to prove the AD capabilities in the context of electromagnetic device sizing by means of gradient optimization. The code complexity as also as the implications of AD usage may stand as a good reference for the researchers in this field area.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 5
Type: Research Article
ISSN: 0332-1649

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Book part
Publication date: 6 September 2019

Annika Christensen

In 2001, Faroese Viking Metal band Týr entered a Faroese music competition with their song ‘Ormurin Langi’, which was a reinterpretation of a famous Faroese kvæÐi (a form…

Abstract

In 2001, Faroese Viking Metal band Týr entered a Faroese music competition with their song ‘Ormurin Langi’, which was a reinterpretation of a famous Faroese kvæÐi (a form of European ballad believed to derive from the Middle Ages) by the same name. Hearing this piece of medieval Faroese heritage represented through metal music was not something anyone had ever experienced before. This chapter will therefore explore how Faroese Viking metal – through its musical and visual style – interprets Faroese kvæÐi, which are themselves interpretations of a Faroese medieval past. The combination of Faroese traditions and contemporary metal music does have a societal and cultural effect. What, therefore, happens when the local and the global intersect and create something that cannot be considered global, but is however not purely local either, as it is in Faroese Viking Metal? The interpretation of several kvæÐi in Faroese Viking metal does not exactly perpetuate the authentic, but rather it presents them in a new form and ensures their circulation and repetition through a more globalised and popular media and Viking romanticism is therefore caught up with contemporary sociocultural imaginings of Faroese identity.

Details

Medievalism and Metal Music Studies: Throwing Down the Gauntlet
Type: Book
ISBN: 978-1-78756-395-7

Keywords

Content available
Article
Publication date: 30 May 2008

Joachim Schopfel and Cherifa Boukacem-Zeghmouri

Abstract

Details

Interlending & Document Supply, vol. 36 no. 2
Type: Research Article
ISSN: 0264-1615

Content available
Book part
Publication date: 1 October 2020

Tim Gorichanaz

Abstract

Details

Information Experience in Theory and Design
Type: Book
ISBN: 978-1-83909-368-5

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Article
Publication date: 10 May 2011

Dejan V. Tošić and Marija F. Hribšek

The purpose of this paper is to model multilayer structure surface acoustic wave (SAW) sensors, incorporated in CMOS or micro‐electro‐mechanical system integrated…

Abstract

Purpose

The purpose of this paper is to model multilayer structure surface acoustic wave (SAW) sensors, incorporated in CMOS or micro‐electro‐mechanical system integrated circuits, and to derive the corresponding wave velocity as an analytic expression in terms of the layers‘ thickness and density, which is suitable for analysis and design.

Design/methodology/approach

The method is based on an electro‐mechanical equivalent model of multilayer structure SAW sensors. A multilayered SAW device is represented by a two‐port electrical equivalent circuit consisting of three parts: input transducer, output transducer, and between them the delay line, which is the sensing part. The sensing part is modelled as a mechanical two‐port network. The wave velocity is calculated using analogy between the mechanical and electrical quantities and the fact that the wave motion of the SAW extends below the surface to a depth of about one wavelength.

Findings

The presented model predicts very efficiently and accurately the velocity of SAW sensors with multilayer substrates in the case where the thicknesses of upper layers are much smaller than the signal wavelength. The velocity can be calculated from the formula, so that elaborate numerical computations involving partial differential equations are avoided.

Research limitations/implications

The model and the velocity calculation can be applied only to acoustically thin upper and middle layers where acoustically thin means that a layer is sufficiently thin and rigid (large shear modulus). The presented results provide a starting‐point for further research in the analysis and design of sensors fabricated using AlGaN, GaN, AlN/diamond.

Practical implications

Since the majority of SAW sensors is designed with acoustically thin layers, the proposed model and calculation can be of interest for many practical material combinations. The presented model and calculation can be used in most cases of the optimal sensor design with respect to the sensor sensitivity or required area on the sensor chip.

Originality/value

The paper presents a new original model of multilayer structure SAW sensors and a new method of SAW velocity calculation. The method gives good results, with much simpler calculations than in the wave equation method, in cases where certain layers are acoustically thin.

Details

Microelectronics International, vol. 28 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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