| 1. |
- Antoniou, Nestoras, et al.
(author)
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CFD and wind-tunnel analysis of outdoor ventilation in a real compact heterogeneous urban area : evaluation using “air delay”
- 2017
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In: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 126, s. 355-372
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Journal article (peer-reviewed)abstract
- Outdoor urban ventilation in a real complex urban area is investigated by introducing a new ventilation indicator – the "air delay". Computational Fluid Dynamics (CFD) simulations are performed using the 3D steady Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The up-to-date literature shows the lack of detailed evaluations of the two approaches for real compact urban areas. This study further presents a systematic evaluation of steady RANS and LES for the assessment of the ventilation conditions in a dense district in Nicosia, Cyprus. The ventilation conditions within the urban area are investigated by calculating the distribution of the age of air. To better assess the outdoor ventilation, a new indicator, the "air delay" is introduced as the difference between the local mean age of air at an urban area and that in an empty domain with the same computational settings, allowing the comparison of the results in different parts of the domain, without impact of the boundary conditions. CFD results are validated using wind-tunnel measurements of mean wind speed and turbulence intensity performed for the same urban area. The results show that LES can accurately predict the mean wind speed and turbulence intensity with the average deviations of about 6% and 14%, respectively, from the wind-tunnel measurements while for the steady RANS, these are 8% and 31%, respectively. The steady RANS simulations overestimate the local mean air delay. The deviation between the two approaches is 52% at pedestrian level (2 m).
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| 2. |
- Hamid Mohammed, Hamed, et al.
(author)
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Using Spectral Descriptive Signatures for Industrial Plume Detection
- 2012
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In: WSEAS Transactions on Environment and Development. - 2224-3496. ; 8:4, s. 120-132
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Journal article (peer-reviewed)abstract
- This paper presents a novel approach for anomaly detection base on computing and utilizing descriptive spectral signatures. The goal of the work is to distinguish between contaminated and normal water areas within a region of investigation. A site-independent approach was developed by considering descriptive spectral signatures characterising normal sweat lake water as reference spectral features. Thereafter, it was possible to detect and determine the distribution of industrial outlet plumes which usually have spectral characteristics that deviate from the surrounding unaffected normal waters. The method was evaluated on airborne hyperspectral remotely-sensed image-data acquired over the region of Norrsundet, Sweden. In this region, areas of different water types were found, such as riverine sweet water, coastal salt seawater, as well as waste water discharged from paper-pulp industries. The work aimed at identifying these types of waters and their distributions. The needed reference descriptive spectral signatures of uncontaminated normal water were generated by using a dataset consisting of laboratory measurements of chlorophyll-a and phaeophytine-a concentrations and the corresponding field reflectance spectra collected at 22 sampling stations in Lake Erken, Sweden. The final results, showing the locations and distributions of contaminated and normal water areas, are in full agreement with field observations in the investigated region.
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| 3. |
- Karbalaie, Abdolamir, et al.
(author)
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Exact Solution of Partial Differential Equation Using Homo-Separation of Variables
- 2014
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In: International Journal of Nonlinear Science. - 1749-3889. ; 17:1, s. 84-90
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Journal article (peer-reviewed)abstract
- In this study, we find the exact solution of certain partial differential equations (PDE) by proposing and using the Homo-Separation of Variables method. This novel analytical method is a combination of the homotopy perturbation method (HPM) with the separation of variables method. The exact solutions are con-structed by choosing an appropriate initial approximation in addition to only one term of the series obtained by HPM. The proposed method is introduced an efficient tool for solving a wide class of partial differential equations. It is straight-forward, easy to understand and fast requiring low computational load.
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| 4. |
- Karbalaie, Abdolamir, et al.
(author)
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Exact Solution of Time-Fractional Partial Differential Equations Using Sumudu Transform
- 2014
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In: WSEAS Transactions on Mathematics. - : World Scientific and Engineering Academy and Society. - 1109-2769 .- 2224-2880. ; 13, s. 142-151
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Journal article (peer-reviewed)abstract
- Abstract: In this study, we propose a new algorithm to find exact solution of nonlinear time- fractional partialdifferential equations. The new algorithm basically illustrates how two powerful algorithms, the homotopy pertur-bation method and the Sumudu transform method can be combined and used to get exact solutions of fractionalpartial differential equations. We also present four different examples to illustrate the preciseness and effectivenessof this algorithm.
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| 5. |
- Karbalaie, Abdolamir, et al.
(author)
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New approach to find the exact solution of fractional partial differential equation
- 2012
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In: WSEAS Transactions on Mathematics. - 1109-2769 .- 2224-2880. ; 11:10, s. 908-917
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Journal article (peer-reviewed)abstract
- In this study, we present the exact solution of certain fractional partial differential equations (FPDE) by using a modified homotopy perturbation method (MHPM).The exact solutions are constructed by choosing an appropriate initial approximation and only one term of the series obtained by MHPM. The exact solutions for initial value problems of FPDE are analytically derived. The methods introduced an efficient tool for solving a wide class of time-fractional partial differential equations.
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