The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Jirina Machackova - One of the best experts on this subject based on the ideXlab platform.
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pollutant plume delineation from tree Core Sampling using standardized ranks
Environmental Pollution, 2012Co-Authors: Agung Wahyudi, Patrick Bogaert, Stefan Trapp, Jirina MachackovaAbstract:There are currently contradicting results in the literature about the way chloroethene (CE) concentrations from tree Core Sampling correlate with those from groundwater measurements. This paper addresses this issue by focusing on groundwater and tree Core datasets in CE contaminated site, Czech Republic. Preliminary analyses revealed strongly and positively skewed distributions for the tree Core dataset, with an intra-tree variability accounting for more than 80% of the total variability, while the spatial analyses based on variograms indicated no obvious spatial pattern for CE concentration. Using rank transformation, it is shown how the results were improved by revealing the initially hidden spatial structure for both variables when they are handled separately. However, bivariate analyses based on cross-covariance functions still failed to indicate a clear spatial correlation between groundwater and tree Core measurements. Nonetheless, tree Core Sampling and analysis proved to be a quick and inexpensive semi-quantitative method and a useful tool.
Stefan Trapp - One of the best experts on this subject based on the ideXlab platform.
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test of tree Core Sampling for screening of toxic elements in soils from a norwegian site
International Journal of Phytoremediation, 2012Co-Authors: Mette Algreen, Arno Rein, Charlotte Nielsen Legind, Carl Einar Amundsen, Ulrich Karlson, Stefan TrappAbstract:Tree Core samples have been used to delineate organic subsurface plumes. In 2009 and 2010, samples were taken at trees growing on a former dump site in Norway and analyzed for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn). Concentrations in wood were in averages (dw) 30 mg/kg for Zn, 2 mg/kg for Cu, and <1 mg/kg for Cd, Cr, As and Ni. The concentrations in wood samples from the polluted test site were compared to those derived from a reference site. For all except one case, mean concentrations from the test site were higher than those from the reference site, but the difference was small and not always significant. Differences between tree species were usually higher than differences between reference and test site. Furthermore, all these elements occur naturally, and Cu, Ni, and Zn are essential minerals. Thus, all trees will have a natural background of these elements, and the occurrence alone does not indicate soil pollution. For the interpretation of the results, a...
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pollutant plume delineation from tree Core Sampling using standardized ranks
Environmental Pollution, 2012Co-Authors: Agung Wahyudi, Patrick Bogaert, Stefan Trapp, Jirina MachackovaAbstract:There are currently contradicting results in the literature about the way chloroethene (CE) concentrations from tree Core Sampling correlate with those from groundwater measurements. This paper addresses this issue by focusing on groundwater and tree Core datasets in CE contaminated site, Czech Republic. Preliminary analyses revealed strongly and positively skewed distributions for the tree Core dataset, with an intra-tree variability accounting for more than 80% of the total variability, while the spatial analyses based on variograms indicated no obvious spatial pattern for CE concentration. Using rank transformation, it is shown how the results were improved by revealing the initially hidden spatial structure for both variables when they are handled separately. However, bivariate analyses based on cross-covariance functions still failed to indicate a clear spatial correlation between groundwater and tree Core measurements. Nonetheless, tree Core Sampling and analysis proved to be a quick and inexpensive semi-quantitative method and a useful tool.
Abdul Mounem Mouazen - One of the best experts on this subject based on the ideXlab platform.
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Development of a methodology for in situ assessment of topsoil dry bulk density
Soil and Tillage Research, 2013Co-Authors: Mohammed Z. Quraishi, Abdul Mounem MouazenAbstract:A reliable, speedy and objective technique for in situ assessment of soil compaction in topsoil is needed. Penetrometer measurements to determine soil compaction are affected by several factors namely soil texture, moisture content (MC), organic matter content (OMC) and dry bulk density (BD), whereas Core Sampling method is laborious and time consuming. The aim of this study is to develop a methodology to predict BD as a function of MC, OMC, soil clay content (CLC) and penetration resistance (PR), aiming at the development of a reliable, cost, and time effective measurement system of field topsoil compaction indicated as BD. Laboratory and field tests were carried out using 570 soil samples collected from 20 fields in Czech Republic, Denmark, the Netherlands, and the UK to establish algorithms to predict BD as a function of PR, MC, OMC and CLC. These algorithms were created by means of multiple linear regression (MLR) and artificial neural network (ANN) methods.The results showed non-linear exponential relationships between PR, and all affecting independent parameters, e.g. BD, MC, OMC and CLC. Due to this non-linear relationship, MLR resulted in low prediction accuracy of BD with a determination coefficient (R 2) value between predicted and measured BD of 0.51 and a root mean square error of prediction (RMSEP) of 0.13Mgm -3. The ANN enabled the prediction of BD with high accuracy with a high R 2 value of 0.81 and a low RMSEP of 0.11Mgm -3. This ANN model can now be used to assess topsoil BD in agricultural fields with similar texture, pedology and geological conditions to those considered in this work, provided that data on PR, MC, OMC and CLC are available. Based on these results, a portable measurement device with multiple sensors is currently under development to enable the measurement of MC, OMC, CLC and PR, and thus derive BD values with the ANN algorithm developed. It is hoped that the proposed methodology will replace existing methods such as the Core Sampling method and provide a quick and easy solution for in situ assessment of topsoil BD. ?? 2012 Elsevier B.V.
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Calibration of an on-line sensor for measurement of topsoil bulk density in all soil textures
Soil and Tillage Research, 2013Co-Authors: Mohammed Z. Quraishi, Abdul Mounem MouazenAbstract:An on-line sensor for the prediction of bulk density (BD) has been previously developed, and calibrated for light textured soils. This study aims to expand the implementation of this sensor for all soil types, including clay soils. The on-line sensor consists of a single ended shear beam load cell to measure draught (D), a visible and near infrared (vis–NIR) sensor to measure moisture content (MC), and a wheel gauge equipped with a draw wire linear sensor to measure depth (d). This sensor was used to collect data from 14 fields across four European countries (Denmark, Czech Republic, the Netherlands and the UK) with different soil textures. The three measured parameters were substituted into a previously developed model to calculate BD. The calculated BD for 333 samples was compared with BD measured with a Core Sampling kit to validate the system and to calculate correction factors (CF) valid for each additional soil texture. A multiple linear regression (MLR), nonlinear multiple regression (NMR) and artificial neural network (ANN) analyses were carried out to establish models to predict CF, as a function of average field MC and soil texture fractions. For clay soils, the correlation between the measured and on-line predicted BD was satisfactory (R2= 0.54–0.69), and suggested a large negative CF > −0.248 Mg m−3. For other soil types with lighter soil textures, accuracy of measurements varied (R2= 0.51–0.96), with lower CF values than those calculated for clay soils and ranged between negative and positive values (−0.007 Mg m−3< CF < 0.079 Mg m−3). The ANN analysis resulted in the best model to predict CF as function of MC and soil texture fractions (R2= 0.96), which allowed the utilisation of the on-line measurement system for any field having any texture and average MC. The on-line BD sensor was shown to be capable of predicting field dry BD rapidly for a large number of samples, as compared with traditional methods.
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development of on line measurement system of bulk density based on on line measured draught depth and soil moisture content
Soil & Tillage Research, 2006Co-Authors: Abdul Mounem Mouazen, Herman RamonAbstract:On-line measurement of soil compaction is needed for site specific tillage management. The soil bulk density (ρ) indicating soil compaction was measured on-line by means of a developed compaction sensor system that comprised several sensors for on-line measurement of the draught (D) of a soil cutting tool (subsoiler), the soil cutting depth (d ) and the soil moisture content (ww). The subsoiler D was measured with a single shear beam load cell, whereas d was measured with a wheel gauge that consisted of a swinging arm metal wheel and a linear variable differential transducer (LVDT). The soil ww was measured with a near infrared fibre-type spectrophotometer sensor. These on-line three measured parameters were used to calculate ρ, by utilising a hybrid numerical–statistical mathematical model developed in a previous study. Punctual kriging was performed using the variogram estimation and spatial prediction with error (VESPER) 1.6 software to develop the field maps of ρ , soil ww, subsoiler d and D, based on 10 m × 10 m grid. To verify the on-line measured ρ map, this map was compared with the map measured by the conventional Core Sampling method. The spherical semivariogram models, providing the best fit for all properties was used for kriging of different maps. Maps developed showed that no clear correlation could be detected between different parameters measured and subsoiler D. However, the D value was smaller at shallow penetration d, whereas large D coincided with large ρ values at few positions in the field. Maps of ρ measured with the Core Sampling and on-line methods were similar, with correlation coefficient (r) and the standard error values of 0.75 and 0.054 Mg m−3, respectively. On-line measured ρ exhibited larger errors at very dry zones. The normal distribution of the ρ error between the two different measurement methods showed that about 72% of the errors were less than 0.05 Mg m−3 in absolute values. However, the overall mean error of on-line measured ρ was of a small value of 2.3%, which ensures the method accuracy for on-line measurement of ρ. Measurement under very dry conditions should be minimised, because it can lead to a relatively large error, and hence, compacted zones at dry zones cannot be detected correctly.
N. Stanic - One of the best experts on this subject based on the ideXlab platform.
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Relating the structural strength of concrete sewer pipes and material properties retrieved from Core samples
Structure and Infrastructure Engineering, 2016Co-Authors: N. Stanic, Jeroen Langeveld, T.a.m. Salet, François ClemensAbstract:Drill Core samples are taken in practice for an analysis of the material characteristics of concrete pipes in order to improve the quality of the decision-making on rehabilitation actions. Earlier research has demonstrated that Core Sampling is associated with a significant uncertainty. In this paper, the results of Core samples are compared with the results of full-scale pipe cracking lab experiments. It is shown that the concrete of deteriorated sewer pipes shows a significant variability in material characteristics. Further it is shown that the formation of ettringite due to biochemical sulphuric corrosion is not necessarily limited to the crown of the pipe and also degradation of pipe material, measured by the carbonation depth, is occurring at the inside and outside of the pipe. It is concluded that tensile splitting strength and the carbonation depth are the two material property parameters of Core Sampling with a sufficiently high correlation (R2 >.90) with the structural strength of the pipe. The thickness of the remaining ‘healthy’ concrete material is the optimal parameter, as this requires the smallest Sampling size.
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comparison of Core Sampling and visual inspection for assessment of concrete sewer pipe condition
Water Science and Technology, 2013Co-Authors: N. Stanic, Cornelis De Haan, M. Tirion, Jeroen Langeveld, F H L R ClemensAbstract:Sewer systems are costly to construct and even more costly to replace, requiring proper asset management Sewer asset management relies to a large extent on available information. In sewer systems where pipe corrosion is the dominant failure mechanism, visual inspection (CCTV) and Core Sampling are amongst the methods applied mostly to assess sewer pipe condition. This paper compares visual inspection and drill Core analysis in order to enhance further understanding of the limitations and potentials of both methods. Both methods have been applied on a selected sewer reach in the city of the Hague, which was reportedly subject to pipe corrosion. Results show that both methods, visual inspection and Core Sampling, are associated with large uncertainties and that there is no obvious correlation between results of visual inspection and results of drill Core analysis.
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Comparison of Core Sampling and visual inspection for assessment of sewer pipe condition
2012Co-Authors: N. Stanic, Cornelis De Haan, M. Tirion, Jeroen Langeveld, François ClemensAbstract:Sewer systems are costly to construct and even more costly to replace, requiring proper asset management Sewer asset management relies to a large extent on available information. In sewer systems where pipe corrosion is the dominant failure mechanism, visual inspection (CCTV) and Core Sampling are amongst the methods applied mostly to assess sewer pipe condition. This paper compares visual inspection and drill Core analysis in order to enhance further understanding of the limitations and potentials of both methods. Both methods have been applied on a selected sewer reach in the city of the Hague, which was reportedly subject to pipe corrosion. Results show that both methods, visual inspection and Core Sampling, are associated with large uncertainties and that there is no obvious correlation between results of visual inspection and results of drill Core analysis.
Agung Wahyudi - One of the best experts on this subject based on the ideXlab platform.
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pollutant plume delineation from tree Core Sampling using standardized ranks
Environmental Pollution, 2012Co-Authors: Agung Wahyudi, Patrick Bogaert, Stefan Trapp, Jirina MachackovaAbstract:There are currently contradicting results in the literature about the way chloroethene (CE) concentrations from tree Core Sampling correlate with those from groundwater measurements. This paper addresses this issue by focusing on groundwater and tree Core datasets in CE contaminated site, Czech Republic. Preliminary analyses revealed strongly and positively skewed distributions for the tree Core dataset, with an intra-tree variability accounting for more than 80% of the total variability, while the spatial analyses based on variograms indicated no obvious spatial pattern for CE concentration. Using rank transformation, it is shown how the results were improved by revealing the initially hidden spatial structure for both variables when they are handled separately. However, bivariate analyses based on cross-covariance functions still failed to indicate a clear spatial correlation between groundwater and tree Core measurements. Nonetheless, tree Core Sampling and analysis proved to be a quick and inexpensive semi-quantitative method and a useful tool.