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Article
Publication date: 5 April 2021

Zhixin Wang, Peng Xu, Bohan Liu, Yankun Cao, Zhi Liu and Zhaojun Liu

This paper aims to demonstrate the principle and practical applications of hyperspectral object detection, carry out the problem we now face and the possible solution…

Abstract

Purpose

This paper aims to demonstrate the principle and practical applications of hyperspectral object detection, carry out the problem we now face and the possible solution. Also some challenges in this field are discussed.

Design/methodology/approach

First, the paper summarized the current research status of the hyperspectral techniques. Then, the paper demonstrated the development of underwater hyperspectral techniques from three major aspects, which are UHI preprocess, unmixing and applications. Finally, the paper presents a conclusion of applications of hyperspectral imaging and future research directions.

Findings

Various methods and scenarios for underwater object detection with hyperspectral imaging are compared, which include preprocessing, unmixing and classification. A summary is made to demonstrate the application scope and results of different methods, which may play an important role in the application of underwater hyperspectral object detection in the future.

Originality/value

This paper introduced several methods of hyperspectral image process, give out the conclusion of the advantages and disadvantages of each method, then demonstrated the challenges we face and the possible way to deal with them.

Details

Sensor Review, vol. 41 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 October 2004

Shihe Xin, Marie‐Christine Duluc, François Lusseyran and Patrick Le Quéré

External natural convection is rarely studied by numerical simulation in the literature due to the fact that flow of interest takes place in an unbounded domain and that…

Abstract

External natural convection is rarely studied by numerical simulation in the literature due to the fact that flow of interest takes place in an unbounded domain and that if a limited computational domain is used the corresponding outer boundary conditions are unknown. In this study, we propose outer boundary conditions for a limited computational domain and make the corresponding numerical implementation in the scope of a projection method combining spectral methods and domain decomposition techniques. Numerical simulations are performed for both steady natural convection about an isothermal cylinder and transient natural convection around a line‐source. An experiment is also realized in water using particle image velocimetry and thermocouples to make a comparison during transients of external natural convection around a platinum wire heated by Joule effect. Good agreement, observed between numerical simulations and experiments, validated the outer boundary conditions proposed and their numerical implementation. It is also shown that, if one tolerates prediction error, numerical results obtained remain at least reasonable in a region near the line‐source during the entire transients. We thus paved the way for numerical simulation of external natural convection although further studies remain to be done for higher heating power (higher Rayleigh number).

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 14 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 3 October 2016

Michael James McCord, Peadar T. Davis, Martin Haran and John McCord

The purpose of this research is to examine the nature of housing market affordability. Although the problem of housing affordability has been widely discussed, the…

Abstract

Purpose

The purpose of this research is to examine the nature of housing market affordability. Although the problem of housing affordability has been widely discussed, the theoretical underpinnings of the concept have received less attention. It has become increasingly evident that more holistic insights and integrated approaches are needed to provide a platform to define affordability to influence research and policy discourse.

Design/methodology/approach

Given the increasing importance of affordability within housing policy reform, this paper seeks to “unearth” the most important prognosticators of affordability. The paper uses principal component analysis to determine how affordability, as a key policy tool, should be analysed. In addition, co integration techniques, Granger causality and impulse response analysis are applied to test the movement and shocks of the key affordability indicators and the two common affordability metrics.

Findings

The principal conclusions stemming from this paper demonstrate that affordability is a multifaceted policy concept influenced by financial access (purchase) costs and the repayment costs of housing services which are correlated and interchangeable but significantly were found not to be co integrated.

Originality/value

Understanding the nature of housing market affordability remains problem for policy-makers. This paper adds to the debate and empirical understanding of the cyclic nature of affordability and how it is defined. It shows that there are intricate causal short-term relationships between the key affordability indicators. This is problematic for contemporary housing policy and the key directions in which policy must turn.

Details

International Journal of Housing Markets and Analysis, vol. 9 no. 4
Type: Research Article
ISSN: 1753-8270

Keywords

Article
Publication date: 2 November 2015

J. McCord, M. McCord, P.T. Davis, M. Haran and W.J. Rodgers

The purpose of this paper is to investigate delay factors within private housing construction in Northern Ireland. Delays are inherent throughout the construction industry…

1408

Abstract

Purpose

The purpose of this paper is to investigate delay factors within private housing construction in Northern Ireland. Delays are inherent throughout the construction industry and create major difficulties in terms of project performance and client satisfaction. Whilst a voluminous body of international literature has investigated pertinent delay factors within construction projects, there is a relative paucity of research which offers a more delineated exploration of delay factors affecting private housing development schemes, particularly in the UK context.

Design/methodology/approach

This study applies questionnaire survey research to examine the relative importance of 75 delay attribute factors for housing construction projects in Northern Ireland. The approach applies both a relative rank and principal component analysis to distil the key factors impinging upon the delay process in housing construction.

Findings

The key finding from this research is that delays within the housing construction sector in Northern Ireland can be attributed to deficiencies in site management, ineffective communication strategies and a lack of coordination between key stakeholders involved in the construction process.

Originality/value

The study adds to the existing knowledge base and provides stakeholders with information on factors, which, if properly risk assessed and understood, can improve housing construction performance. The findings are of relevance to construction industry practitioners, policy makers and researchers with lessons learned serving as a basis for future policy development as well as affording an information platform for improving the efficiency and expediency of housing provision internationally.

Details

Journal of Financial Management of Property and Construction, vol. 20 no. 3
Type: Research Article
ISSN: 1366-4387

Keywords

Article
Publication date: 13 August 2019

Mohamed El-Beltagy

The paper aims to compare and clarify the differences and between the two well-known decomposition spectral techniques; the Winer–Chaos expansion (WCE) and the…

Abstract

Purpose

The paper aims to compare and clarify the differences and between the two well-known decomposition spectral techniques; the Winer–Chaos expansion (WCE) and the Winer–Hermite expansion (WHE). The details of the two decompositions are outlined. The difficulties arise when using the two techniques are also mentioned along with the convergence orders. The reader can also find a collection of references to understand the two decompositions with their origins. The geometrical Brownian motion is considered as an example for an important process with exact solution for the sake of comparison. The two decompositions are found practical in analysing the SDEs. The WCE is, in general, simpler, while WHE is more efficient as it is the limit of WCE when using infinite number of random variables. The Burgers turbulence is considered as a nonlinear example and WHE is shown to be more efficient in detecting the turbulence. In general, WHE is more efficient especially in case of nonlinear and/or non-Gaussian processes.

Design/methodology/approach

The paper outlined the technical and literature review of the WCE and WHE techniques. Linear and nonlinear processes are compared to outline the comparison along with the convergence of both techniques.

Findings

The paper shows that both decompositions are practical in solving the stochastic differential equations. The WCE is found simpler and WHE is the limit when using infinite number of random variables in WCE. The WHE is more efficient especially in case of nonlinear problems.

Research limitations/implications

Applicable for SDEs with square integrable processes and coefficients satisfying Lipschitz conditions.

Originality/value

This paper fulfils a comparison required by the researchers in the stochastic analysis area. It also introduces a simple efficient technique to model the flow turbulence in the physical domain.

Details

Engineering Computations, vol. 36 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 2 January 2018

Anan Zhang, Cong He, Maoyi Sun, Qian Li, Hong Wei Li and Lin Yang

Noise abatement is one of the key techniques for Partial Discharge (PD) on-line measurement and monitoring. However, how to enhance the efficiency of PD signal noise…

Abstract

Purpose

Noise abatement is one of the key techniques for Partial Discharge (PD) on-line measurement and monitoring. However, how to enhance the efficiency of PD signal noise suppression is a challenging work. Hence, this study aims to improve the efficiency of PD signal noise abatement.

Design/methodology/approach

In this approach, the time–frequency characteristics of PD signal had been obtained based on fast kurtogram and S-transform time–frequency spectrum, and these characteristics were used to optimize the parameters for the signal matching over-complete dictionary. Subsequently, a self-adaptive selection of matching atoms was realized when using Matching Pursuit (MP) to analyze PD signals, which leading to seldom noise signal element was represented in sparse decomposition.

Findings

The de-noising of PD signals was achieved efficiently. Simulation and experimental results show that the proposed method has good adaptability and significant noise abatement effect compared with Empirical Mode Decomposition, Wavelet Threshold and global signal sparse decomposition of MP.

Originality/value

A self-adaptive noise abatement method was proposed to improve the efficiency of PD signal noise suppression based on the signal sparse representation and its MP algorithm, which is significant to on-line PD measurement.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 1996

I. Raspo, J. Ouazzani and R. Peyret

This paper presents a spectral multidomain method for solving theNavier‐Stokes equations in the vorticity‐stream function formulation. Thealgorithm is based on an…

Abstract

This paper presents a spectral multidomain method for solving the Navier‐Stokes equations in the vorticity‐stream function formulation. The algorithm is based on an extensive use of the influence matrix technique and so leads to a direct method without any iterative process. Numerical results concerning the Czochralski melt configuration are reported and compared with spectral monodomain solutions to show the advantage of the domain decomposition for such a problem which solution presents a singular behaviour.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 6 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 June 2000

R.V.N. Melnik

The dynamics of coupling between spectrum and resolvent under ε‐perturbations of operator and matrix spectra are studied both theoretically and numerically. The phenomenon…

4152

Abstract

The dynamics of coupling between spectrum and resolvent under ε‐perturbations of operator and matrix spectra are studied both theoretically and numerically. The phenomenon of non‐trivial pseudospectra encountered in these dynamics is treated by relating information in the complex plane to the behaviour of operators and matrices. On a number of numerical results we show how an intrinsic blend of theory with symbolic and numerical computations can be used effectively for the analysis of spectral problems arising from engineering applications.

Details

Engineering Computations, vol. 17 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 November 2002

Herbert Martins Gomes and Armando Miguel Awruch

In this paper, special emphasis is given to uncertainties in the evaluation of the structural behavior, looking for a better representation of the system characteristics…

Abstract

In this paper, special emphasis is given to uncertainties in the evaluation of the structural behavior, looking for a better representation of the system characteristics and quantification of the significance of these uncertainties in structural design. The reliability analysis of reinforced concrete structures is performed taking into account the spatial variability of material properties. The finite element method is used to analyze reinforced concrete structures. A multidimensional non‐Gaussian stochastic field generation model (independent of the finite element mesh) is developed and used. The reliability analysis is carried out employing the first order reliability method. Numerical examples are presented to study how to generate correlated non‐Gaussian stochastic fields and determine the reliability of a reinforced concrete structure with respect to a limit state function.

Details

Engineering Computations, vol. 19 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 16 November 2010

R. Rothe, M. van der Giet and K. Hameyer

The purpose of this paper is to present a method for analyzing higher magnetic force harmonics in electrical machines based on electromagnetic finite element simulation.

Abstract

Purpose

The purpose of this paper is to present a method for analyzing higher magnetic force harmonics in electrical machines based on electromagnetic finite element simulation.

Design/methodology/approach

Sampling of air gap field solution data allows for a Fourier decomposition of magnetic forces and flux densities. A two‐dimensional convolution gives insight into the spectral decomposition of forces responsible for acoustic noise, vibration and higher torque harmonics.

Findings

The proposed approach seems especially suitable for synchronous machine models. The influence of magnetic circuit design parameters that are difficult to calculate analytically on the harmonic air gap content can be analyzed and the spectral force decomposition illustrated by means of space vectors.

Originality/value

The approach is generalized to the convolution and analysis of arbitrarily sampled two‐dimensional data in this paper.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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