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Article
Publication date: 3 May 2021

Lakehal Belarbi and Hichem Elhendi

Let (M, g) be a n-dimensional smooth Riemannian manifold. In the present paper, the authors introduce a new class of natural metrics denoted by gf and called gradient

Abstract

Purpose

Let (M, g) be a n-dimensional smooth Riemannian manifold. In the present paper, the authors introduce a new class of natural metrics denoted by gf and called gradient Sasaki metric on the tangent bundle TM. The authors calculate its Levi-Civita connection and Riemannian curvature tensor. The authors study the geometry of (TM, gf) and several important results are obtained on curvature, scalar and sectional curvatures.

Design/methodology/approach

In this paper the authors introduce a new class of natural metrics called gradient Sasaki metric on tangent bundle.

Findings

The authors calculate its Levi-Civita connection and Riemannian curvature tensor. The authors study the geometry of (TM,gf) and several important results are obtained on curvature scalar and sectional curvatures.

Originality/value

The authors calculate its Levi-Civita connection and Riemannian curvature tensor. The authors study the geometry of (TM,gf) and several important results are obtained on curvature scalar and sectional curvatures.

Details

Arab Journal of Mathematical Sciences, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1319-5166

Keywords

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Book part
Publication date: 18 July 2007

John M. Polimeni and Jon D. Erickson

This chapter presents projections of residential development in Wappinger Creek watershed of Dutchess County, New York in the Hudson River Valley. A spatial econometric…

Abstract

This chapter presents projections of residential development in Wappinger Creek watershed of Dutchess County, New York in the Hudson River Valley. A spatial econometric model is developed based on data from a geographical information system (GIS) of county-level socio-economic trends, tax parcel attributes, town-level zoning restrictions, location variables, and bio-geophysical constraints including slope, soil type, riparian and agricultural zones. Monte Carlo simulation is employed to distribute spatially explicit projections of land-use change under various residential development scenarios. Scenario analysis indicates the likelihood of continued residential, decentralized development patterns in formerly agricultural and forested parcels. Policy scenarios demonstrate possible courses of action to direct development and protect watershed health.

Details

Ecological Economics of Sustainable Watershed Management
Type: Book
ISBN: 978-1-84950-507-9

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Book part
Publication date: 19 January 2005

Stephen Sheppard

Abstract

Details

Urban Dynamics and Growth: Advances in Urban Economics
Type: Book
ISBN: 978-0-44451-481-3

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Article
Publication date: 1 August 1939

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National…

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics and publications of other similar research bodies as issued

Details

Aircraft Engineering and Aerospace Technology, vol. 11 no. 8
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 10 June 2021

Witold Artur Klimczyk

This paper aims to present a methodology of designing a custom propeller for specified needs. The example of propeller design for large unmanned air vehicle (UAV) is considered.

Abstract

Purpose

This paper aims to present a methodology of designing a custom propeller for specified needs. The example of propeller design for large unmanned air vehicle (UAV) is considered.

Design/methodology/approach

Starting from low fidelity Blade Element (BE) methods, the design is obtained using evolutionary algorithm-driven process. Realistic constraints are used, including minimum thickness required for stiffness, as well as manufacturing ones – including leading and trailing edge limits. Hence, the interactions between propellers in hex-rotor configuration, and their influence on structural integrity of the UAV are investigated. Unsteady Reynolds-Averaged Navier–Stokes (URANS) are used to obtain loading on the propeller blades in hover. Optimization of the propeller by designing a problem-specific airfoil using surrogate modeling-driven optimization process is performed.

Findings

The methodology described in the current paper proved to deliver an efficient blade. The optimization approach allowed to further improve the blade efficiency, with power consumption at hover reduced by around 7%.

Practical implications

The methodology can be generalized to any blade design problem. Depending on the requirements and constraints the result will be different.

Originality/value

Current work deals with the relatively new class of design problems, where very specific requirements are put on the propellers. Depending on these requirements, the optimum blade geometry may vary significantly.

Details

Aircraft Engineering and Aerospace Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 26 September 2019

Leiyu Zhang, Jianfeng Li, Shuting Ji, Peng Su, Chunjing Tao and Run Ji

Upper-limb joint kinematics are highly complex and the kinematics of rehabilitation exoskeletons fail to reproduce them, resulting in hyperstaticity and human–machine…

Abstract

Purpose

Upper-limb joint kinematics are highly complex and the kinematics of rehabilitation exoskeletons fail to reproduce them, resulting in hyperstaticity and human–machine incompatibility. The purpose of this paper is to design and develop a compatible exoskeleton robot (Co-Exos II) to address these problems.

Design/methodology/approach

The configuration synthesis of Co-Exos II is completed using advanced mechanism theory. A compatible configuration is selected and four passive joints are introduced into the connecting interfaces based on optimal configuration principles. A Co-Exos II prototype with nine degrees of freedom (DOFs) is developed and still owns a compact structure and volume. A new approach is presented to compensate the vertical glenohumeral (GH) movements. Co-Exos II and the upper arm are simplified as a guide-bar mechanism at the elevating plane. The theoretical displacements of passive joints are calculated by the kinematic model of the shoulder loop. The compatible experiments are completed to measure the kinematics of passive joints.

Findings

The compatible configuration of the passive joints can effectively reduce the gravity influences of the exoskeleton device and the upper extremities. The passive joints exhibit excellent compensation effect for the GH joint movements by comparing the theoretical and measured results. Passive joints can compensate for most GH movements, especially vertical movements.

Originality/value

Co-Exos II possesses good human–machine compatibility and wearable comfort for the affected upper limbs. The proposed compensation method is convenient to therapists and stroke patients during the rehabilitation trainings.

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