The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

G. J. Brown - One of the best experts on this subject based on the ideXlab platform.

  • Erosion prediction in slurry pipeline tee-junctions
    Applied Mathematical Modelling, 2002
    Co-Authors: G. J. Brown
    Abstract:

    A significant Erosion Problem is found to occur on steel blanks located inside tee-junctions in a slurry pipeline system. A 3-D computational fluid dynamics (CFD) model is developed to predict the motion of caustic liquor and bauxite particles through a tee-junction using an Eulerian–Eulerian continuum approach in conjunction with the k–e turbulence model. Initial simulations assuming a uniform inlet flow are unable to demonstrate the cause of the observed Erosion. However, subsequent modelling with a swirling inlet flow, based on a more thorough assessment of the upstream vessels and piping, results in the prediction of an accumulation of particles on the steel blank at the centre of a slow-moving vortex, the location of which is in excellent agreement with the observed wear on the plant. Furthermore, the predicted wear location is found to be insensitive to the assumed level of inlet swirl and the numerical scheme employed. The multi-phase CFD model is also used to assess several potential solutions to the Erosion Problem, resulting in the replacement of the tee-junctions with a pivoting elbow design which is found to exhibit significantly reduced Erosion rates on the plant. These results demonstrate the effectiveness with which CFD techniques can be used in the solution of industrial Erosion Problems. They also highlight the potential sensitivity of modelling results to inlet boundary condition assumptions and emphasise the need to adequately account for upstream influences when applying CFD techniques to the simulation of industrial flows.

  • Erosion prediction in slurry pipeline tee-junctions
    Applied Mathematical Modelling, 2002
    Co-Authors: G. J. Brown
    Abstract:

    A significant Erosion Problem is found to occur on steel blanks located inside tee-junctions in a slurry pipeline system. A 3-D computational fluid dynamics (CFD) model is developed to predict the motion of caustic liquor and bauxite particles through a tee-junction using an Eulerian-Eulerian continuum approach in conjunction with the k-ε turbulence model. Initial simulations assuming a uniform inlet flow are unable to demonstrate the cause of the observed Erosion. However, subsequent modelling with a swirling inlet flow, based on a more thorough assessment of the upstream vessels and piping, results in the prediction of an accumulation of particles on the steel blank at the centre of a slow-moving vortex, the location of which is in excellent agreement with the observed wear on the plant. Furthermore, the predicted wear location is found to be insensitive to the assumed level of inlet swirl and the numerical scheme employed. The multiphase CFD model is also used to assess several potential solutions to the Erosion Problem, resulting in the replacement of the tee-junctions with a pivoting elbow design which is found to exhibit significantly reduced Erosion rates on the plant. These results demonstrate the effectiveness with which CFD techniques can be used in the solution of industrial Erosion Problems. They also highlight the potential sensitivity of modelling results to inlet boundary condition assumptions and emphasise the need to adequately account for upstream influences when applying CFD techniques to the simulation of industrial flows. © 2002 Elsevier Science Inc. All rights reserved.

Aklilu Amsalu - One of the best experts on this subject based on the ideXlab platform.

  • analysis of farmers perception and response to soil Erosion Problem in ankasha district ethiopia
    Journal of Hill Agriculture, 2016
    Co-Authors: Dessalew Meseret, Aklilu Amsalu
    Abstract:

    Natural resources, such as soil and water are best managed by the people, farmers, who use them rather than by other government bodies. Consideration of farmers ’perception is an essential issue when making decisions on soil and water conservation, and agricultural sustainability. This study analyzed the perception and response of farmers on soil Erosion Problems in Ankasha District, Ethiopia. 79% of farmers perceived Erosion as a Problem on their farm land. However, their understanding of Erosion severity depends on appearance of visible signs of Erosion such as rills and gullies. Educational level of the household heads and slope where the farm land was located had significant influence at 99% (P<0.01) confidence level, contact with extension workers, age of the household heads, participation in agricultural training and plot distance from the homestead had significant influence at 95% (P<0.05) confidence level, whereas, plot size and family size were found to have significant effect at 90% (P<0.1) confidence level. Raising farmers ’awareness and involving them in the planning and designing of conservation measures will increase the chances of success of conservation efforts and reduce Erosion Problem.

  • Analysis of farmers ’perception and response to soil Erosion Problem in Ankasha district, Ethiopia
    Journal of Hill Agriculture, 2016
    Co-Authors: Dessalew Meseret, Aklilu Amsalu
    Abstract:

    Natural resources, such as soil and water are best managed by the people, farmers, who use them rather than by other government bodies. Consideration of farmers ’perception is an essential issue when making decisions on soil and water conservation, and agricultural sustainability. This study analyzed the perception and response of farmers on soil Erosion Problems in Ankasha District, Ethiopia. 79% of farmers perceived Erosion as a Problem on their farm land. However, their understanding of Erosion severity depends on appearance of visible signs of Erosion such as rills and gullies. Educational level of the household heads and slope where the farm land was located had significant influence at 99% (P

  • determinants of adoption and continued use of stone terraces for soil and water conservation in an ethiopian highland watershed
    Ecological Economics, 2007
    Co-Authors: Aklilu Amsalu, Jan De Graaff
    Abstract:

    In the Ethiopian highlands, land degradation resulting from soil Erosion and nutrient depletion is a serious environmental and socio-economic Problem. Although soil and water conservation techniques have extensively been introduced over the past decades, sustained use of the measures was not as expected. Based on data obtained from 147 farming households, this paper examines the determinants of farmers' adoption and continued use of introduced stone terraces in an Ethiopian highland watershed. A sequential decision-making model using the bivariate probit approach was employed to analyze the data. The results show that the factors influencing adoption and continued use of the stone terraces are different. Adoption is influenced by farmers' age, farm size, perceptions on technology profitability, slope, livestock size and soil fertility, while the decision to continue using the practice is influenced by actual technology profitability, slope, soil fertility, family size, farm size and participation in off-farm work. Perceptions of Erosion Problem, land tenure security and extension contacts show no significant influence. Further, the results indicate the importance of household/farm and plot level factors in farmers' conservation decision. It is therefore concluded that 1) analysis of the determinants of adoption per se may not provide a full understanding of the range of factors influencing farmers' decision of sustained investments and 2) conservation interventions should focus not only on the biophysical performance of the measures but also on economic benefits that can be obtained at reasonable discount rates to the farmers in order to enhance sustained use of the measures.

Jan De Graaff - One of the best experts on this subject based on the ideXlab platform.

  • determinants of adoption and continued use of stone terraces for soil and water conservation in an ethiopian highland watershed
    Ecological Economics, 2007
    Co-Authors: Aklilu Amsalu, Jan De Graaff
    Abstract:

    In the Ethiopian highlands, land degradation resulting from soil Erosion and nutrient depletion is a serious environmental and socio-economic Problem. Although soil and water conservation techniques have extensively been introduced over the past decades, sustained use of the measures was not as expected. Based on data obtained from 147 farming households, this paper examines the determinants of farmers' adoption and continued use of introduced stone terraces in an Ethiopian highland watershed. A sequential decision-making model using the bivariate probit approach was employed to analyze the data. The results show that the factors influencing adoption and continued use of the stone terraces are different. Adoption is influenced by farmers' age, farm size, perceptions on technology profitability, slope, livestock size and soil fertility, while the decision to continue using the practice is influenced by actual technology profitability, slope, soil fertility, family size, farm size and participation in off-farm work. Perceptions of Erosion Problem, land tenure security and extension contacts show no significant influence. Further, the results indicate the importance of household/farm and plot level factors in farmers' conservation decision. It is therefore concluded that 1) analysis of the determinants of adoption per se may not provide a full understanding of the range of factors influencing farmers' decision of sustained investments and 2) conservation interventions should focus not only on the biophysical performance of the measures but also on economic benefits that can be obtained at reasonable discount rates to the farmers in order to enhance sustained use of the measures.

Massimo Alessio - One of the best experts on this subject based on the ideXlab platform.

  • Median‐modified Wiener filter provides efficient denoising, preserving spot edge and morphology in 2‐DE image processing
    Proteomics, 2009
    Co-Authors: Carlo Vittorio Cannistraci, Franco Maria Montevecchi, Massimo Alessio
    Abstract:

    Denoising is a fundamental early stage in 2-DE image analysis strongly influencing spot detection or pixel-based methods. A novel nonlinear adaptive spatial filter (median-modified Wiener filter, MMWF), is here compared with five well-established denoising techniques (Median, Wiener, Gaussian, and Polynomial-Savitzky-Golay filters; wavelet denoising) to suggest, by means of fuzzy sets evaluation, the best denoising approach to use in practice. Although median filter and wavelet achieved the best performance in spike and Gaussian denoising respectively, they are unsuitable for contemporary removal of different types of noise, because their best setting is noise-dependent. Vice versa, MMWF that arrived second in each single denoising category, was evaluated as the best filter for global denoising, being its best setting invariant of the type of noise. In addition, median filter eroded the edge of isolated spots and filled the space between close-set spots, whereas MMWF because of a novel filter effect (drop-off-effect) does not suffer from Erosion Problem, preserves the morphology of close-set spots, and avoids spot and spike fuzzyfication, an aberration encountered for Wiener filter. In our tests, MMWF was assessed as the best choice when the goal is to minimize spot edge aberrations while removing spike and Gaussian noise.

  • median modified wiener filter provides efficient denoising preserving spot edge and morphology in 2 de image processing
    Proteomics, 2009
    Co-Authors: Carlo Vittorio Cannistraci, Franco Maria Montevecchi, Massimo Alessio
    Abstract:

    Denoising is a fundamental early stage in 2-DE image analysis strongly influencing spot detection or pixel-based methods. A novel nonlinear adaptive spatial filter (median-modified Wiener filter, MMWF), is here compared with five well-established denoising techniques (Median, Wiener, Gaussian, and Polynomial-Savitzky-Golay filters; wavelet denoising) to suggest, by means of fuzzy sets evaluation, the best denoising approach to use in practice. Although median filter and wavelet achieved the best performance in spike and Gaussian denoising respectively, they are unsuitable for contemporary removal of different types of noise, because their best setting is noise-dependent. Vice versa, MMWF that arrived second in each single denoising category, was evaluated as the best filter for global denoising, being its best setting invariant of the type of noise. In addition, median filter eroded the edge of isolated spots and filled the space between close-set spots, whereas MMWF because of a novel filter effect (drop-off-effect) does not suffer from Erosion Problem, preserves the morphology of close-set spots, and avoids spot and spike fuzzyfication, an aberration encountered for Wiener filter. In our tests, MMWF was assessed as the best choice when the goal is to minimize spot edge aberrations while removing spike and Gaussian noise.

Carlo Vittorio Cannistraci - One of the best experts on this subject based on the ideXlab platform.

  • Median‐modified Wiener filter provides efficient denoising, preserving spot edge and morphology in 2‐DE image processing
    Proteomics, 2009
    Co-Authors: Carlo Vittorio Cannistraci, Franco Maria Montevecchi, Massimo Alessio
    Abstract:

    Denoising is a fundamental early stage in 2-DE image analysis strongly influencing spot detection or pixel-based methods. A novel nonlinear adaptive spatial filter (median-modified Wiener filter, MMWF), is here compared with five well-established denoising techniques (Median, Wiener, Gaussian, and Polynomial-Savitzky-Golay filters; wavelet denoising) to suggest, by means of fuzzy sets evaluation, the best denoising approach to use in practice. Although median filter and wavelet achieved the best performance in spike and Gaussian denoising respectively, they are unsuitable for contemporary removal of different types of noise, because their best setting is noise-dependent. Vice versa, MMWF that arrived second in each single denoising category, was evaluated as the best filter for global denoising, being its best setting invariant of the type of noise. In addition, median filter eroded the edge of isolated spots and filled the space between close-set spots, whereas MMWF because of a novel filter effect (drop-off-effect) does not suffer from Erosion Problem, preserves the morphology of close-set spots, and avoids spot and spike fuzzyfication, an aberration encountered for Wiener filter. In our tests, MMWF was assessed as the best choice when the goal is to minimize spot edge aberrations while removing spike and Gaussian noise.

  • median modified wiener filter provides efficient denoising preserving spot edge and morphology in 2 de image processing
    Proteomics, 2009
    Co-Authors: Carlo Vittorio Cannistraci, Franco Maria Montevecchi, Massimo Alessio
    Abstract:

    Denoising is a fundamental early stage in 2-DE image analysis strongly influencing spot detection or pixel-based methods. A novel nonlinear adaptive spatial filter (median-modified Wiener filter, MMWF), is here compared with five well-established denoising techniques (Median, Wiener, Gaussian, and Polynomial-Savitzky-Golay filters; wavelet denoising) to suggest, by means of fuzzy sets evaluation, the best denoising approach to use in practice. Although median filter and wavelet achieved the best performance in spike and Gaussian denoising respectively, they are unsuitable for contemporary removal of different types of noise, because their best setting is noise-dependent. Vice versa, MMWF that arrived second in each single denoising category, was evaluated as the best filter for global denoising, being its best setting invariant of the type of noise. In addition, median filter eroded the edge of isolated spots and filled the space between close-set spots, whereas MMWF because of a novel filter effect (drop-off-effect) does not suffer from Erosion Problem, preserves the morphology of close-set spots, and avoids spot and spike fuzzyfication, an aberration encountered for Wiener filter. In our tests, MMWF was assessed as the best choice when the goal is to minimize spot edge aberrations while removing spike and Gaussian noise.