Evaluation of soil erosion and sediment sources in two contrasting sub-basins, using fingerprinting and 137Cs techniques in Uruguay. Preliminary results.

2021 ◽  
Author(s):  
Marcos Tassano ◽  
Romina Sanabria ◽  
Joan Gonzalez ◽  
Pablo Cabral ◽  
Samuel Tejeda ◽  
...  
Keyword(s):  
Reference Value ◽  
Distribution Model ◽  
Balance Model ◽  
Sediment Sources ◽  
Surface Samples ◽  
Natural Pasture ◽  
Clayey Silt ◽  
Profile Distribution ◽  
Geochemical Elements ◽  
The 19Th Century

<p>The study site consists of two sub-basins (“Arbolito”, 20.94 km2; and “Horno”, 10.44 km2) divided by the Rolon stream, which in turn flows into the Baygorria hydroelectric dam reservoir (-32.77152 S; -56.84093 W). The "Arbolito" sub-basin consists of natural pasture with extensive cattle from the 19th century to the present day.  Soils are predominantly eutric brunosols and clayey haplic vertisols with slopes > 6% (MGAP, Uruguay). The “Horno” sub-basin consists of intensive agriculture since the mid-1980s, with a history of rice, wheat, oat, soybean and pastureland rotations. At the beginning of the 2000s, direct sowing began in this region of the country. Soils in Horno are predominantly clayey, deep Haplic Vertisols and Typical Eurethric Brunosols, clayey silt, vertically and moderately deep, with slopes ≤ 6 % (MGAP, Uruguay). Both soil types and their formation are associated with basaltic lithologies. A total of 50 surface samples from natural pastures, cropland and channel banks were used as sources to describe the mixture of sediments (fine-bed material) using geochemical elements and the FingerPro mixing model. For the 137Cs technique, a total of 120 surface samples were taken, multi-transect sampling was conducted in both sub-basins, and reference sites were established. Profile Distribution Model (PDM) and Diffusion Model (DM) were used as conversion model for the Arbolito sub-basin, while Mass Balance Model II (MBM II) was used for Horno sub-basin. MODERN model was used in both areas. Sediment fingerprinting results showed that the proportion of sediment sources is divided as follows: cropland (up to 70%), pastures (up to 25%) and channel banks (the remaining 5%). The reference value of 137Cs found was 369.0 bq.m-2 (SD 7.4 bq.m-2) on 01/01/2020 calibration date. The results of the net soil redistribution rates using different conversion models of 137Cs were consistent with each other, and showed erosion in both sub-basins, Arbolito: PDM (-0.72 Mg ha-1 yr-1), DM (-0.29 Mg ha-1 yr-1), MODERN (-0.69 Mg ha-1 yr-1); Horno: MBM II (-0.5 Mg ha-1 yr-1), MODERN (-0.56 Mg ha-1 yr-1). Although the net erosion rate in both sub-basins is similar, the redistribution of soil within each sub-basin is different. While the Arbolito shows on average preserved areas at the top of the slopes (MODERN 1.7 Mg ha-1 yr-1), with high erosion in the middle (MODERN -5.7 Mg ha-1 yr-1) and low erosion in lower areas (MODERN -0.47 Mg ha-1 yr-1); Horno sub-basin shows in average eroded areas at the top of the slopes (MODERN -4.3 Mg ha-1 yr-1) with low sedimentation in the middle (MODERN 0.4 Mg ha-1 yr-1) and high sedimentation in the lower areas (MODERN 2.21 Mg ha-1 yr-1). This would explain a greater redistribution of the soil from the high to the low areas in the Horno sub-basin compared to Arbolito, probably due to the mechanical movement of the soil by agriculture practice. These results may explain a greater export of soils in Horno compared to Arbolito, which agrees with cropland as the most important source of sediments (up to 70%) by fingerprinting techniques.</p>

scholarly journals Antarctic Surface and Subsurface Snow and Ice Melt Fluxes

2005 ◽  
Vol 18 (10) ◽  
pp. 1469-1481 ◽  
Author(s):  
Glen E. Liston ◽  
Jan-Gunnar Winther
Keyword(s):  
Energy Balance ◽  
Dominant Role ◽  
Field Measurements ◽  
Distribution Model ◽  
Balance Model ◽  
Near Surface ◽  
Production Values ◽  
Surface Melt ◽  
The Antarctic ◽  
Snow And Ice

Abstract This paper presents modeled surface and subsurface melt fluxes across near-coastal Antarctica. Simulations were performed using a physical-based energy balance model developed in conjunction with detailed field measurements in a mixed snow and blue-ice area of Dronning Maud Land, Antarctica. The model was combined with a satellite-derived map of Antarctic snow and blue-ice areas, 10 yr (1991–2000) of Antarctic meteorological station data, and a high-resolution meteorological distribution model, to provide daily simulated melt values on a 1-km grid covering Antarctica. Model simulations showed that 11.8% and 21.6% of the Antarctic continent experienced surface and subsurface melt, respectively. In addition, the simulations produced 10-yr averaged subsurface meltwater production fluxes of 316.5 and 57.4 km3 yr−1 for snow-covered and blue-ice areas, respectively. The corresponding figures for surface melt were 46.0 and 2.0 km3 yr−1, respectively, thus demonstrating the dominant role of subsurface over surface meltwater production. In total, computed surface and subsurface meltwater production values equal 31 mm yr−1 if evenly distributed over all of Antarctica. While, at any given location, meltwater production rates were highest in blue-ice areas, total annual Antarctic meltwater production was highest for snow-covered areas due to its larger spatial extent. The simulations also showed higher interannual meltwater variations for surface melt than subsurface melt. Since most of the produced meltwater refreezes near where it was produced, the simulated melt has little effect on the Antarctic mass balance. However, the melt contribution is important for the surface energy balance and in modifying surface and near-surface snow and ice properties such as density and grain size.

Projections of future habitat use by Atlantic bluefin tuna: mechanistic vs. correlative distribution models

2016 ◽  
Vol 74 (3) ◽  
pp. 698-716 ◽  
Author(s):  
Barbara A. Muhling ◽  
Richard Brill ◽  
John T. Lamkin ◽  
Mitchell A. Roffer ◽  
Sang-Ki Lee ◽  
...  
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Species Distribution Model ◽  
Bluefin Tuna ◽  
Distribution Model ◽  
Balance Model ◽  
Oxygen Balance ◽  
Spatiotemporal Resolution ◽  
Atlantic Bluefin Tuna ◽  
Fishing Fleets

Climate change is likely to drive complex shifts in the distribution and ecology of marine species. Projections of future changes may vary, however, depending on the biological impact model used. In this study, we compared a correlative species distribution model and a simple mechanistic oxygen balance model for Atlantic bluefin tuna (Thunnus thynnus: ABFT) in the North Atlantic Ocean. Both models gave similar results for the recent historical time period, and suggested that ABFT generally occupy favourable metabolic habitats. Projections from an earth system model showed largely temperature-induced reductions in ABFT habitat in the tropical and sub-tropical Atlantic by 2100. However, the oxygen balance model showed more optimistic results in parts of the subpolar North Atlantic. This was partially due to an inherent ability to extrapolate beyond conditions currently encountered by pelagic longline fishing fleets. Projections included considerable uncertainty due to the simplicity of the biological models, and the coarse spatiotemporal resolution of the analyses. Despite these limitations, our results suggest that climate change is likely to increase metabolic stress on ABFT in sub-tropical habitats, but may improve habitat suitability in subpolar habitats, with implications for spawning and migratory behaviours, and availability to fishing fleets.

Neural model of relative mass flows of water and sugar in an installation for crystallizing and centrifuging A massecuite

2010 ◽  
pp. 506-514 ◽  
Author(s):  
Jan Iciek ◽  
Arkadiusz Jezierski
Keyword(s):  
Water Mass ◽  
Calculated Data ◽  
Reference Value ◽  
Neural Model ◽  
Balance Model ◽  
Relative Mass ◽  
Practical Application ◽  
Relative Water ◽  
Mass Flows

Three models of relative mass flows of water and sugar concerning crystallizing and centrifuging of A massecuite are presented. The input data for the calculation of particular flow volumes were the dry substance content wDS and sucrose content wS values measured in them during the sugarbeet campaign in one Polish beet sugar factory. These values, along with authors’ own knowledge and technological charts, provided the authors with the basis for the development of a mathematical model making possible the determination of appropriate, relative mass flows (sugar mass flow was accepted as the reference value) in a station for crystallizing and centrifuging of A massecuite. Then, an external balance model was developed to check the accuracy of the measured and of the calculated data. This model was provided with reliable data to develop a neural model. The developed and trained artificial neural network allowed for the simulation of relative water and sugar mass flows in an installation for crystallizing and centrifuging A massecuite. The results were satisfactory and the neural model developed was found to have a practical application in the simulation of the influence of particular sugar and water mass flows on the work of this installation.

An Engineering Model for the Impact Breakup of the Space Target

2013 ◽  
Vol 290 ◽  
pp. 63-68
Author(s):  
Wei Jie Wang ◽  
Huai Rong Shen ◽  
Yi Yong Li
Keyword(s):  
Thin Plate ◽  
Reference Value ◽  
Equivalent Model ◽  
Distribution Model ◽  
Engineering Model ◽  
Target Characteristic ◽  
Set Up ◽  
Average Size ◽  
The Impact ◽  
Space Target

To the question of the breakup of the space target impacted by projectile, an engineering model is developed. The space target characteristic is analyzed, and the target equivalent model is established based on the thin plate. The average size model for the impact fragment of thin plate is established depending on strain rate, fragments are discrete according to Poisson statistic and fragment distribution model is figured out. The length and velocity degraded model is set up against projectile with the shape of cylindrical rod. The simulation case is analyzed and the result indicates that the related models are effective, flexible and have important reference value.

Refractivity profile distribution model for infrared waves

2012 ◽  
Vol 24 (12) ◽  
pp. 2778-2782 ◽  
Author(s):  
孙正 Sun Zheng ◽  
宁辉 Ning Hui ◽  
谢永杰 Xie YongJie ◽  
曹鑫 Cao Xin
Keyword(s):  
Distribution Model ◽  
Profile Distribution

scholarly journals Mathematical Modeling and Mechanism of VUV Photodegradation of H2S in the Absence of O2

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Jian-hui Xu ◽  
Bin-bin Ding ◽  
Xiao-mei Lv ◽  
Shan-hong Lan ◽  
Chao-lin Li ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Retention Time ◽  
Gas Flow ◽  
Flow Distribution ◽  
Calculation Model ◽  
Point Of View ◽  
Distribution Model ◽  
Balance Model ◽  
Photodegradation Rate ◽  
The Mathematical Model

The existence of H2S has limited the biogas energy promotion. The traditional photodegradation of H2S is usually conducted in the presence of O2, yet this is unsuitable for biogas desulfurization which should be avoided. Therefore, the ultraviolet degradation of H2S in the absence of O2 was investigated for the first time in the present study from a mathematical point of view. Light wavelength and intensity applied were 185 nm and 2.16 × 10−12 Einstein/cm2·s, respectively. Firstly, the mathematical model of H2S photodegradation was established with MATLAB software, including the gas flow distribution model and radiation model of photoreactor, kinetics model, mass balance model, and calculation model of the degradation rate. Then, the influence of the initial H2S concentration and gas retention time on the photodegradation rate were studied, for verification of the mathematical model. Results indicated that the photodegradation rate decreased with the increase in initial H2S concentration, and the maximum photodegradation rate reached 62.8% under initial concentration of 3 mg/m3. In addition, the photodegradation rate of H2S increased with the increase in retention time. The experimental results were in good accordance with the modeling results, indicating the feasibility of the mathematical model to simulate the photodegradation of H2S. Finally, the intermediate products were simulated and results showed that the main photodegradation products were found to be H2 and elemental S, and concentrations of the two main products were close and agreed well with the reaction stoichiometric coefficients. Moreover, the concentration of free radicals of H• and SH• was rather low.

scholarly journals Update and Evaluation of a High-Throughput In Vitro Mass Balance Distribution Model: IV-MBM EQP v2.0

Toxics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 315
Author(s):  
James M. Armitage ◽  
Alessandro Sangion ◽  
Rohan Parmar ◽  
Alexandra B. Looky ◽  
Jon A. Arnot
Keyword(s):  
Mass Balance ◽  
Model Performance ◽  
Distribution Model ◽  
Balance Model ◽  
In Vitro Assays ◽  
Organic Chemicals ◽  
In Vitro Test ◽  
Data Set ◽  
Blood Concentrations

This study demonstrates the utility of an updated mass balance model for predicting the distribution of organic chemicals in in vitro test systems (IV-MBM EQP v2.0) and evaluates its performance with empirical data. The IV-MBM EQP v2.0 tool was parameterized and applied to four independent data sets with measured ratios of bulk medium or freely-dissolved to initial nominal concentrations (e.g., C24/C0 where C24 is the measured concentration after 24 h of exposure and C0 is the initial nominal concentration). Model performance varied depending on the data set, chemical properties (e.g., “volatiles” vs. “non-volatiles”, neutral vs. ionizable organics), and model assumptions but overall is deemed acceptable. For example, the r2 was greater than 0.8 and the mean absolute error (MAE) in the predictions was less than a factor of two for most neutral organics included. Model performance was not as good for the ionizable organic chemicals included but the r2 was still greater than 0.7 and the MAE less than a factor of three. The IV-MBM EQP v2.0 model was subsequently applied to several hundred chemicals on Canada’s Domestic Substances List (DSL) with nominal effects data (AC50s) reported for two in vitro assays. We report the frequency of chemicals with AC50s corresponding to predicted cell membrane concentrations in the baseline toxicity range (i.e., >20–60 mM) and tabulate the number of chemicals with “volatility issues” (majority of chemical in headspace) and “solubility issues” (freely-dissolved concentration greater than water solubility after distribution). In addition, the predicted “equivalent EQP blood concentrations” (i.e., blood concentration at equilibrium with predicted cellular concentration) were compared to the AC50s as a function of hydrophobicity (log octanol-water partition or distribution ratio). The predicted equivalent EQP blood concentrations exceed the AC50 by up to a factor of 100 depending on hydrophobicity and assay conditions. The implications of using AC50s as direct surrogates for human blood concentrations when estimating the oral equivalent doses using a toxicokinetic model (i.e., reverse dosimetry) are then briefly discussed.

scholarly journals Maintenance Strategy Based on Reliability Analysis and FMEA: A Case Study for Hydraulic Cylinders of Traditional Excavators with ERRS

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qingliang Zeng ◽  
Wenting Liu ◽  
Lirong Wan ◽  
Chenglong Wang ◽  
Kuidong Gao
Keyword(s):  
Reliability Analysis ◽  
Failure Modes ◽  
Reference Value ◽  
Distribution Model ◽  
Maintenance Strategy ◽  
Statistical Tool ◽  
Reliability Parameters ◽  
Failure Data ◽  
Hydraulic Cylinders ◽  
Maintenance Policies

A simple and effective mechanical parts maintenance approach with lower cost is urgently needed by the cost-sensitive manufactures for traditional excavators (HE). This paper proposes maintenance strategy for hydraulic cylinders (HC) of HE with energy regeneration and recovery system (ERRS). Reliability analysis and FMEA of historical failure data are applied to make maintenance strategy. In this study, the failure data required for reliability analysis are collected from the manufacturers and users over two and a half years, Excel is used as statistical tool, Minitab is used for parameter estimation, and Kolmogorov–Smirnov test is used to reject or accept the hypothesis of the distribution model. The reliability parameters R(t), Rset, and R∗(t) are determined and parameter β∗ is the reference value for making countermeasures and maintenance policies properly for the failure modes of the new HC of HE with ERRS. The purpose of this paper is to make proper maintenance policies and to maintain a high availability level and fulfill the user’s needs for HC, which also paves the way for further reliability study about ERRS.

Calculation Strategy of Automatic Shape Control in Hot Strip Mill

2014 ◽  
Vol 529 ◽  
pp. 591-594
Author(s):  
Zi Ying Liu ◽  
Yan Guang Sun ◽  
Xiang Rong Song
Keyword(s):  
Control System ◽  
Shape Control ◽  
Distribution Model ◽  
Good Effect ◽  
Hot Strip Mill ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Practical Applications ◽  
Hot Strip ◽  
Profile Distribution

This paper, aimed at Ganglu 1500 hot strip rolling project, developed advanced shape control system. Entry profile calculation strategy was developed. Natural output profile was defined. Profile distribution model based on the buckling limit was developed. Practical applications in domestic 1500 hot strip mill show that the setup calculation strategy achieved good effect and enhanced the profile and flatness precision

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