Journal articles on the topic 'Soil structure – Mathematical models'
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1
He, Bin, and Jun Long Lu. "Stress Analysis of Underground Arch Structure." Advanced Materials Research 243-249 (May 2011): 938–41. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.938.
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To research the safety of an underground defense project and the impact to other buildings, applying basic mechanics principles, established two types of mathematical model for arch about the project, and analyzed stress in different directions of ground arch structure. The data shows that the results were very different in different mathematical models, and mathematical models should be considered as close to actual stress situation in structural analysis. In the structural analysis involved soil, spatial finite element model is more accurate and reasonable than truss finite element model.
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Mitra, Girija Bhushan. "Spiral Structure of 7 Å Halloysite: Mathematical Models." Clays and Clay Minerals 61, no. 6 (December 1, 2013): 499–507. http://dx.doi.org/10.1346/ccmn.2013.0610602.
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Belik, Aleksandra A., Anna A. Kokoreva, Andrei G. Bolotov, Aleksandr V. Dembovetskii, Victoria N. Kolupaeva, Dmitry V. Korost, and Alexei N. Khomyak. "Characterizing macropore structure of agrosoddy-podzolic soil using computed tomography." Open Agriculture 5, no. 1 (December 24, 2020): 888–97. http://dx.doi.org/10.1515/opag-2020-0080.
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AbstractThe agrosoddy-podzolic soil (Eutric Albic Glossic Retisol (Abruptic, Loamic, Aric, Cutanic)) is typical for Moscow Oblast and is used for agricultural purposes, resulting in use of various agrochemicals and pesticides. The presence of macropores and cracks in such soils leads to preferential water and substance transfer and nonequilibrium conditions. Therefore, it is important to study the numerical characteristics of the pore space of soils to adjust mathematical models of substance transfer. Undisturbed soil monoliths 10 cm in diameter taken from Ap (from 0 to 30 cm) and E, BE horizons (from 30 to 50 cm) were investigated under the field moisture conditions and after saturation using the tomographic core analyzer RKT-180 with the resolution of 200 μm/pixel. Using the X-ray computer tomography, it has been established that the plough layer of the agrosoddy-podzolic soil contains over 7% of macropores larger than 1 mm, while the subsurface layer has a porosity of about 3%. After saturation, some of the inter-aggregate pores overlap, which leads to a decrease in the total porosity to 4% in the upper and 2% in lower horizons, as well as increase in the average pore diameter. The number of macropores determined by tomographic analysis is one third higher than the values calculated using pedotransfer functions for this soil. The data obtained in this paper are recommended for use in national scenarios of migration of substances (pesticides, agrochemicals, salts) in soils.
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Belik, Aleksandra A., Anna A. Kokoreva, Andrei G. Bolotov, Aleksandr V. Dembovetskii, Victoria N. Kolupaeva, Dmitry V. Korost, and Alexei N. Khomyak. "Characterizing macropore structure of agrosoddy-podzolic soil using computed tomography." Open Agriculture 5, no. 1 (January 1, 2020): 888–97. http://dx.doi.org/10.1515/opag-2020-0080.
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Abstract The agrosoddy-podzolic soil (Eutric Albic Glossic Retisol (Abruptic, Loamic, Aric, Cutanic)) is typical for Moscow Oblast and is used for agricultural purposes, resulting in use of various agrochemicals and pesticides. The presence of macropores and cracks in such soils leads to preferential water and substance transfer and nonequilibrium conditions. Therefore, it is important to study the numerical characteristics of the pore space of soils to adjust mathematical models of substance transfer. Undisturbed soil monoliths 10 cm in diameter taken from Ap (from 0 to 30 cm) and E, BE horizons (from 30 to 50 cm) were investigated under the field moisture conditions and after saturation using the tomographic core analyzer RKT-180 with the resolution of 200 μm/pixel. Using the X-ray computer tomography, it has been established that the plough layer of the agrosoddy-podzolic soil contains over 7% of macropores larger than 1 mm, while the subsurface layer has a porosity of about 3%. After saturation, some of the inter-aggregate pores overlap, which leads to a decrease in the total porosity to 4% in the upper and 2% in lower horizons, as well as increase in the average pore diameter. The number of macropores determined by tomographic analysis is one third higher than the values calculated using pedotransfer functions for this soil. The data obtained in this paper are recommended for use in national scenarios of migration of substances (pesticides, agrochemicals, salts) in soils.
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Chandrasekhar, Parvathy, Janis Kreiselmeier, Andreas Schwen, Thomas Weninger, Stefan Julich, Karl-Heinz Feger, and Kai Schwärzel. "Why We Should Include Soil Structural Dynamics of Agricultural Soils in Hydrological Models." Water 10, no. 12 (December 15, 2018): 1862. http://dx.doi.org/10.3390/w10121862.
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Surface soil structure is sensitive to natural and anthropogenic impacts that alter soil hydraulic properties (SHP). These alterations have distinct consequences on the water cycle. In this review, we summarized published findings on the quantitative effects of different agricultural management practices on SHP and the subsequent response of the water balance components. Generally, immediately after tillage, soils show a high abundance of large pores, which are temporally unstable and collapse due to environmental factors like rainfall. Nevertheless, most hydrological modeling studies consider SHP as temporally constant when predicting the flow of water and solutes in the atmosphere-plant-soil system. There have been some developments in mathematical approaches to capture the temporal dynamics of soil pore space. We applied one such pore evolution model to two datasets to evaluate its suitability to predict soil pore space dynamics after disturbance. Lack of knowledge on how dispersion of pore size distribution behaves after tillage may have led to over-estimation of some values predicted by the model. Nevertheless, we found that the model predicted the evolution of soil pore space reasonably well (r2 > 0.80 in most cases). The limiting factor to efficiently calibrate and apply such modeling tools is not in the theoretical part but rather the lack of adequate soil structural and hydrologic data.
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Yusupov, R. A., S. Axrolov, N. M. Mirzanova, and A. N. Nasiriddinov. "MATHEMATICAL MODELS OF GEOFILTRRATION AND GEOMIGRATION IN POROUS MEDIA WITH FRACTAL STRUCTURE." PHYSICAL AND MATHEMATICAL SCIENCES 4, no. 1 (April 30, 2020): 40–46. http://dx.doi.org/10.26739/2181-0656-2020-4-5.
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In this study 2-D linear models are coming from generalised, Boussinesq eqution describing geofiltration in soils with fractal structures are presented. In this study are presented too mathematical models geomigration of contaminations with groundwater in classical way and in soils with fractal structures
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Yusupov, R. A., Sh S. Axrolov, N. M. Mirzanova, and A. N. Nasiriddinov. "MATHEMATICAL MODELS OF GEOFILTRRATION AND GEOMIGRATION IN POROUS MEDIA WITH FRACTAL STRUCTURE." TECHNICAL SCIENCES 6, no. 3 (June 30, 2020): 21–27. http://dx.doi.org/10.26739/2181-9696-2020-6-4.
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In this study 2-D linear models are coming from generalised, Boussinesq eqution describing geofiltration in soils with fractal structures are presented. In this study are presented too mathematical models geomigration of contaminations with groundwater in classical way and in soils with fractal structures.
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Yusupov, R. A., Sh S. Axrolov, N. M. Mirzanova, and A. N. Nasiriddinov. "MATHEMATICAL MODELS OF GEOFILTRRATION AND GEOMIGRATION IN POROUS MEDIA WITH FRACTAL STRUCTURE." TECHNICAL SCIENCES 5, no. 3 (May 30, 2020): 39–45. http://dx.doi.org/10.26739/2181-9696-2020-5-6.
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In this study 2-D linear models are coming from generalised, Boussinesq eqution describing geofiltration in soils with fractal structures are presented. In this study are presented too mathematical models geomigration of contaminations with groundwater in classical way and in soils with fractal structures
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Ergina, E. I., R. V. Gorbunov, and E. F. Stashkina. "Maximum humus horizon thickness as a criterion for identifying the soil standards of the plain Сrimea." Rossiiskaia selskokhoziaistvennaia nauka, no. 4 (August 19, 2019): 39–42. http://dx.doi.org/10.31857/s2500-26272019439-42.
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When identifying the main categories of soil in the structure of the regional Red Book of soils, it is necessary to focus on typical soils formed taking into account the zonal soil-ecological conditions of the territory. The criterion for the extraction of soil standards can be the initial, pre-agrogenic thickness of the humus horizon, which fully realizes the soil-forming potential of natural factors of climax full-profile soils. But the search for such sites is associated with a number of methodological difficulties. A way out of this situation can be a mathematical modeling of the formation of the humus horizon of soils, which allows you to quantify the legitimacy of the allocation of soil standards in the structure of the Red Book of soils of the Crimea. The proposed method allows going to the cartographic models for determining the maximum thickness of the humus horizon. Analysis of the presented material allows asserting that in the majority of modern soils of agricultural lands of the Crimea, the profiles are destroyed by 30% compared with the calculated maximum thickness of the humus horizon, which takes into account the zonal soil formation processes. That predetermines the search for soil standards only in areas that did not function previously in agrogenic conditions, most often, these are protected areas that take into account the peculiarities of the zonal process of soil formation.
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Polyakov, Sergey, P. Enin, and A. Parfenov. "AUTOMATIC CONTROL STRUCTURE FOR FORESTRY MATERIALS." Actual directions of scientific researches of the XXI century: theory and practice 8, no. 1 (October 26, 2020): 223–27. http://dx.doi.org/10.34220/2308-8877-2020-8-1-223-227.
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The article discusses a method of extreme control of the driving effects of the microclimate, which consists in keeping the objective function at the point of extremum for the control system. To solve the problem of extreme management, it is necessary to introduce computerization of the control and development of forest planting material. This will allow you to collect statistical information for the entire time of observation of plant growth. The primary task here is the analysis of observations and the possibility of generating regulatory influences from the microprocessor control system of the microclimate of the greenhouse. From literature sources, the stages of development of forest seedlings are known, for which data on the natural growth of seedlings and seedlings based on processing of statistical material are obtained. To date, recent studies show that there are no necessary mathematical models, both in growth and in the development of planting material under changing conditions and the nature of growth, and in time periods. Thus, objects of sheltered soil can be attributed from the point of view of the object of control and regulation to systems with variable parameters. That is, they can be characterized as unknown mathematical models.
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Cunha, Jorge L. X. L., Maria E. H. Coelho, Abel W. de Albuquerque, Cicero A. Silva, Antônio B. da Silva Júnior, and Islan D. E. de Carvalho. "Water infiltration rate in Yellow Latosol under different soil management systems." Revista Brasileira de Engenharia Agrícola e Ambiental 19, no. 11 (November 2015): 1021–27. http://dx.doi.org/10.1590/1807-1929/agriambi.v19n11p1021-1027.
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ABSTRACTThe management systems affect soil structure, causing changes in porosity that can influence soil water infiltration. In order to study the water infiltration rate in a Yellow Latosol under different tillage systems and different mathematical models, an experiment was conducted from October to December 2012, at the Center for Agricultural Sciences at the Federal University of Alagoas, using a randomized block design with five replicates, in a split-plot scheme. In the plots, the management systems were evaluated (conventional tillage, no-tillage and minimum tillage) and, in the sub-plots, the empirical mathematical models of Kostiakov, Kostiakov-Lewis and Horton, and the ring method. The method used to measure soil water infiltration rate was adapted from the classic double-ring infiltrometer method. The minimum tillage system provided better results compared with the others, with water infiltration rate of 167 mm h-1, and the equation that best fitted the data of the ring infiltrometer was Kostiakov’s, in the no-tillage system.
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Bedell, Romain, Alaa Hassan, Anne-Julie Tinet, Javier Arrieta-Escobar, Delphine Derrien, Marie-France Dignac, Vincent Boly, Stéphanie Ouvrard, and Joshua M. Pearce. "Open-Source Script for Design and 3D Printing of Porous Structures for Soil Science." Technologies 9, no. 3 (September 15, 2021): 67. http://dx.doi.org/10.3390/technologies9030067.
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Three-dimensional (3D) printing in soil science is relatively rare but offers promising directions for research. Having 3D-printed soil samples will help academics and researchers conduct experiments in a reproducible and participatory research network and gain a better understanding of the studied soil parameters. One of the most important challenges in utilizing 3D printing techniques for soil modeling is the manufacturing of a soil structure. Until now, the most widespread method for printing porous soil structures is based on scanning a real sample via X-ray tomography. The aim of this paper is to design a porous soil structure based on mathematical models rather than on samples themselves. This can allow soil scientists to design and parameterize their samples according to their desired experiments. An open-source toolchain is developed using a Lua script, in the IceSL slicer, with graphical user interface to enable researchers to create and configure their digital soil models, called monoliths, without using meshing algorithms or STL files which reduce the resolution of the model. Examples of monoliths are 3D-printed in polylactic acid using fused filament fabrication technology with a layer thickness of 0.20, 0.12, and 0.08 mm. The images generated from the digital model slicing are analyzed using open-source ImageJ software to obtain information about internal geometrical shape, porosity, tortuosity, grain size distribution, and hydraulic conductivities. The results show that the developed script enables designing reproducible numerical models that imitate soil structures with defined pore and grain sizes in a range between coarse sand (from 1 mm diameter) to fine gravel (up to 12 mm diameter).
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Habasimbi, Paul, and Tomoyoshi Nishimura. "Comparison of Soil–Water Characteristic Curves in One-Dimensional and Isotropic Stress Conditions." Soil Systems 2, no. 3 (July 26, 2018): 43. http://dx.doi.org/10.3390/soilsystems2030043.
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Understanding unsaturated soil behavior is key to the design of foundations and embankment structures. Geotechnical engineers have applied net normal stress and matric suction to these engineering problems. Water retention activity in soils is used to predict seepage problems and stability of slope failures. Soil–Water Characteristic Curve (SWCC) tests contribute largely to matric suction interpretation. Determination of SWCCs in the laboratory is usually done using a pressure plate apparatus where vertical or confining stress cannot be applied. Mathematical models of SWCC though commonly accepted in geotechnical engineering practices, do not take into consideration stress conditions such as the difference between a one-dimensional condition and isotropic confining conditions. This study conducted SWCC tests of a silt soil under one-dimensional and isotropic confining stress conditions and focused on the differences between these types of SWCC data sets. Vertical and isotropic confining stresses ranging from 100 to 600 kPa were applied under both stress conditions. SWCCs appears to be affected by the influence of different stress conditions. Lateral pressure and confinement on an isotropic compression condition caused the soil specimen to become dense in void structure and consequently, soil moisture flow movement decreased. This probably induced high retention activities in the silt soil specimen. The study further suggests that the current SWCC models require further development to take into consideration the effect of different stress conditions.
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Gekkieva, S. Kh, M. M. Karmokov, and M. A. Kerefov. "ON BOUNDARY VALUE PROBLEM FOR GENERALIZED ALLER EQUATION." Vestnik of Samara University. Natural Science Series 26, no. 2 (February 1, 2021): 7–14. http://dx.doi.org/10.18287/2541-7525-2020-26-2-7-14.
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The mathematical models of fluid filtration processes in porous media with a fractal structure and memory are based on differential equations of fractional order in both time and space variables. The dependence of the soil water content can significantly affect the moisture transport in capillary-porous media. The paper investigates the generalized Aller equation widely used in mathematical modeling of the processes related to water table dynamics in view of fractal structure. As a mathematical model of the Aller equation withRiemann Liouville fractional derivatives, a loaded fractional order equation is proposed, and a solution to the Goursat problem has been written out for this model in explicit form.
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Provorov, Nikolay A., and Nikolay I. Vorobyov. "Evolution of micro-symbionts of cultured plants: experimental and mathematical models." Ecological genetics 9, no. 3 (September 15, 2011): 20–22. http://dx.doi.org/10.17816/ecogen9320-22.
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Formation of the cultured flora resulted in a decrease of plant symbiotic potential based on interactions with beneficial microorganisms. This decrease leads to transformation of plant micro-symbionts into the non-adaptive forms caused by: а) blocking the selection in favor of mutualistic strains; б) horizontal gene transfer in the microbial communities resulted in formation of virulent “symbiotic cheaters”. Mathematical simulation suggests that these tendencies may be overcome by formation of the optimal population structures in symbiotic system which should possess a high integrity and specificity of partners’ interactions as well as by a tolerance to the invasions of non-active aboriginal strains from the local soil populations.
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Mechkarini, Leila, Tahar Messafer, Abderrahim Bali, and Kamel Silhadi. "Development of an aid tool for evaluation of unsaturated soils permeability." World Journal of Engineering 16, no. 2 (April 8, 2019): 322–30. http://dx.doi.org/10.1108/wje-08-2018-0260.
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Purpose Prediction models for the unsaturated permeability proposed in the literature are numerous. However, a model may give a good result for a sample of a given soil when it may give a bad result for another sample belonging to the same type of soil. This showed that the choice of a model to complete the permeability curve in the unsaturated state is complex. To facilitate such studies, this paper aims to present a help system capable of defining the mathematical model to the user that best represents the permeability of the soil. Design/methodology/approach The authors have detailed the difficulties in determining the correct value of kuns from a thorough bibliographic study. To develop this idea, the authors took real examples, to which they applied mathematical models and then compared their results with those of the bibliographic study. Knowledge structuring in the form of classes, rules and functions. Implementation of the data in generator of help system Kappa-pc. validation of results. Findings An aid tool was developed for the evaluation of unsaturated soils permeability using Brooks and Corey (1964) and Leong and Rahardjo (1997) models, which are known for their effectiveness and ease of application. This system will also evaluate these two methods using estimation models of saturated permeability [Dane and Pocket (1992), Terzaghi (1981) and laboratory data]. This system allows the evaluation of unsaturated permeability by the aforementioned two models, makes comparison between these two models, classifies them and proposes the model presenting the best result. Originality/value This aid system is able to compare results of different models of prediction of the hydraulic conductivity of unsaturated soils according to several criteria (suction, degree of saturation, plasticity index, models of estimation of the permeability to the soil, saturated state, particle size, etc.). It can also deduce the model that best adapts to a given soil. This aid system will be of great use for geotechnical engineers and researchers in the field.
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Rujikiatkamjorn, Cholachat, and Buddhima Indraratna. "Analytical solution for radial consolidation considering soil structure characteristics." Canadian Geotechnical Journal 52, no. 7 (July 2015): 947–60. http://dx.doi.org/10.1139/cgj-2014-0277.
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A system of surcharge load combined with vertical drains to speed up consolidation of soft soil by reducing the drainage path is one of the most efficient and economical ground improvement techniques. In the field, conventional theories including smear zone have been commonly employed to predict the radial consolidation behaviour induced by vertical drains in soft clay. One of the key parameters in conventional analysis is the use of mean coefficient of volume compressibility and soil permeability, which are often assumed to be constant. The effect of drain installation on the soil compressibility of the in situ clay structure is often ignored. Laboratory testing has shown that the soil compressibility and permeability can vary nonlinearly over a considerable range of applied surcharge pressure, and both these properties can be affected during the drain installation. This study presents a mathematical model of radial consolidation via vertical drains incorporating the variations of soil compressibility and permeability as well as highlighting the effects of drain installation on those parameters. The main differences between the proposed and conventional models are elucidated, in terms of stress history and preloading (surcharge) pressure. The effects of preconsolidation pressure and the magnitude of applied preloading are examined through the dissipation of average excess pore pressure and associated settlement. Supported by experimental observations, the proposed theory is validated with field data of a selected case study in the town of Ballina, New South Wales, Australia.
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Grabarnik, P. Ya, O. G. Chertov, S. I. Chumachenko, V. N. Shanin, L. G. Khanina, M. V. Bobrovskiy, S. S. Bykhovets, and P. V. Frolov. "The Integration of Simulation Models for Complex Evaluation of Different Forest Ecosystem Services: Methodological Approaches." Mathematical Biology and Bioinformatics 14, no. 2 (November 5, 2019): 488–99. http://dx.doi.org/10.17537/2019.14.488.
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To solve the problems of modeling complex ecological, socio-ecological and economic systems, a large number of computer models have been developed, from the simplest ones, which only roughly described the system under investigation, to fairly detailed ones, which allow for studying the behavior of a great number of interacting elements simultaneously. The development of views on the structure and patterns of ecosystem functioning, the improvement of computer technology, programming technologies, and the advanced mathematical theories create the background for a new stage in the development of the modeling in ecology. If earlier mathematical models, being very generalized, were created by individual scientists or small research groups, at present the development of complex models is impossible without utilizing the experience of many research teams using a diverse arsenal of methods and knowledge accumulated in forest science, ecology, plant physiology, soil science, climatology, and other sciences. As a part of the task of integrating several environmental models, a software and hardware solution was developed based on a special data exchange protocol, and methodological foundations were developed for the model integration. A system based on the dynamic FORRUS-S forest stand model, the Romul_Hum soil organic matter dynamics model, the SCLISS soil climate statistical generator, and the BioCalc biodiversity estimation for integrated assessment of the trade-offs and synergies dynamics at different forest management scenarios has been created. Using this system of models, a prediction of timber production, carbon accumulation in soil organic matter, and biodiversity dynamics was made for large forest area.
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Banwart, Steven A., Nikolaos P. Nikolaidis, Yong-Guan Zhu, Caroline L. Peacock, and Donald L. Sparks. "Soil Functions: Connecting Earth's Critical Zone." Annual Review of Earth and Planetary Sciences 47, no. 1 (May 30, 2019): 333–59. http://dx.doi.org/10.1146/annurev-earth-063016-020544.
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Soil is the central interface of Earth's critical zone—the planetary surface layer extending from unaltered bedrock to the vegetation canopy—and is under intense pressure from human demand for biomass, water, and food resources. Soil functions are flows and transformations of mass, energy, and genetic information that connect soil to the wider critical zone, transmitting the impacts of human activity at the land surface and providing a control point for beneficial human intervention. Soil functions are manifest during bedrock weathering and, in fully developed soil profiles, correlate with the porosity architecture of soil structure and arise from the development of soil aggregates as fundamental ecological units. Advances in knowledge on the mechanistic processes of soil functions, their connection throughout the critical zone, and their quantitative representation in mathematical and computational models define research frontiers that address the major global challenges of critical zone resource provisioning for human benefit. ▪ Connecting the mechanisms of soil functions with critical zone processes defines integrating science to tackle challenges of climate change and food and water supply. ▪ Soil functions, which develop through formation of soil aggregates as fundamental eco-logical units, are manifest at the earliest stages of critical zone evolution. ▪ Global degradation of soil functions during the Anthropocene is reversible through positive human intervention in soil as a central control point in Earth's critical zone. ▪ Measurement and mathematical translation of soil functions and critical zone processes offer new computational approaches for basic and applied geosciences research.
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Svetlitchnyi, А. A., and A. V. Piatkova. "Spatially distributed GIS-realized mathematical model of rainstorm erosion losses of soil." Journal of Geology, Geography and Geoecology 28, no. 3 (October 10, 2019): 562–71. http://dx.doi.org/10.15421/111953.
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In connection with the wide and ever increasing spread of erosion degradation of agricultural lands in Ukraine, the task of developing mathematical models and methods for calculating water erosion of soils corresponding to the current level of erosion study and the demands of soil protection practices is becoming increasingly important. The article is devoted to the development of a spatially distributed GIS-implemented mathematical model of rainstorm soil erosion, which accounts for most of the annual soil losses (in the Steppe zone, for example, about 90 %). The development of the model is based on the most theoretically and informationally grounded model for the Steppe and Forest-Steppe of Ukraine , “the logical-mathematical model of rainstorm soil outwash” developed by H. I. Shvebs (1974, 1981), as well as the results of theoretical and field studies and mathematical modeling of the slope runoff and water erosion of soil, carried out at the Department of Physical Geography and Environmental Management of Odessa I. I. Mechnikov National University in the 1990s - 2010s, and also the possibilities of modern geoinformation technologies. For the spatial implementation of the model, a raster model of spatial data and operators of the PCRaster GIS-package (University of Utrecht, the Netherlands) were used, integrated with the Basic programming language into a single system that provides an implementation of the computational algorithm. The developed physical-statistical model of soil erosion-sedimentation takes into account the peculiarities of the formation of slope runoff and soil outwash in conditions of excessive nonstationarity of heavy rainfall, as well as spatial heterogeneity of all major natural and economic factors of water erosion on a slope, including slope steepness, exposure, longitudinal and transverse forms of slopes, soil erodibility, structure of sown areas and anti-erosion measures. Checking the adequacy of the mathematical model was performed using observational data of four experimental catchments ; two runoff plots of the Moldavan water-balance station with total area of 0.08 ha, the Ploska catchment with area of 8.5 ha (Boguslav field experimental base of Ukrainian Hydrometeorological Institute) and the Sukha catchment with area of 63 ha (Veliko-Anadol water-balance station) with observation periods of 17-31 years. Comparison of the calculated average over the catchment area of mean annual values of rainstorm soil losses, with the corresponding values obtained from measurements on these catchments, made on the basis of Nash-Sutcliff efficiency criterion (NS), allowed us to evaluate the quality of the model as good (NS = 0.72).
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Ivlieva, Natalia, Vladimir Manukhov, and Anastasia Alferina. "Cartography-geoinformation support of soil and agrochemical researches (on the example of a separate agricultural enterprise)." InterCarto. InterGIS 26, no. 2 (2020): 41–53. http://dx.doi.org/10.35595/2414-9179-2020-2-26-41-53.
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The study of land soils is of no small importance for agricultural enterprises, since the main role in ensuring the productivity of agriculture belongs to the soil. Currently, they are actively using geoinformation-cartographic support of soil and geochemical research of the territory. The aim of this work was to create a cartographic database of soils for a separate agricultural enterprise. The relevance of the development of a cartographic database (CDB) of the soils of the lands of an individual agricultural enterprise is associated with the need to comprehensively take into account all agrochemical and environmental factors important for sustainable agricultural productivity, and monitor soil fertility of the farm. The main source of thematic data was materials from an agrochemical survey of agricultural soils. In addition, land use and farm location plans, a topographic map, and satellite imagery were used. The GIS environment was the ArcGIS 10 software product. It provides the ability to work with geodatabases, as well as a set of tools for automated mapping, spatial analysis, and mathematical-cartographic modeling. As a result of the work, the CDB structure was designed, a set of spatial GIS data was generated, the content, layout and design of thematic maps of a separate agricultural enterprise were developed. The ordered structure of the CDB makes it easy and simple to work with data and carry out the necessary spatial analysis. The use of modern methods of geographic information and mathematical cartographic modeling allowed us to create a more detailed geographic information and cartographic support for the study of soil in the territory. On the basis of modern GIS technologies, in order to improve the perception and analysis of information when constructing cartographic models, stepless scales were used, conditional surfaces were built, etc. To create typological synthetic characteristics and further display them on a map, methods of multivariate mathematical-statistical analysis were used. A typological soil-geochemical map is constructed, which shows the differentiation of the studied cultivated areas according to a complex of agrochemical indicators. For the purposes of further research, a detailed digital relief model of the study area was built. The cartographic database is already used in research on optimizing land management using GIS technologies, agroecological assessment of arable land, rational use of rural territories, etc.
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Fu, Jun, Jian Li, Xinlong Tang, Ruixue Wang, and Zhi Chen. "Optimization of Structure Parameters of the Grouser Shoes for Adhesion Reduction under Black Soil." Agriculture 11, no. 8 (August 20, 2021): 795. http://dx.doi.org/10.3390/agriculture11080795.
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The black soil of Northeast China has a strong adhesion ability because of its unique physical properties, and the soil often adheres to the surface of the grouser shoes of tracked vehicles during the operation. The adhesion performance depends largely on structure parameters of the grouser shoes. The grouser height, the grouser thickness, and the grouser splayed angle were selected as structure parameters. The adhesion force and adhesive soil mass were selected as indicators of adhesion performance. Therefore, the mathematical model between structure parameters and response indicators was established by the response surface method (RSM). The optimal parameters combination was that the grouser height was 20 mm, grouser thickness was 6.34 mm, and grouser splayed angle was 40.45°. The average data of verification experiments occurred when the adhesion force reached 1.11 kPa and adhesive soil mass reached 22.68 g. Compared with the average value of un-optimized experiment results, the adhesion force and adhesive soil mass reduced by 12.84% and 4.63%, respectively. The relative error of the predicted values and measured values was less than 5%, proving the reliability of the regression models. This study could provide a reference method for parameters optimization, and a new structure of the grouser shoes of tracked vehicles will be designed to reduce adhesion.
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Barrios, Gonzalo, Vinuka Nanayakkara, Pramodya De Alwis, and Nawawi Chouw. "Effects of Slenderness and Fundamental Frequency on the Dynamic Response of Adjacent Structures." International Journal of Structural Stability and Dynamics 19, no. 09 (August 28, 2019): 1950105. http://dx.doi.org/10.1142/s0219455419501050.
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In conventional seismic design, the structure is often assumed to be fixed at the base. However, this assumption does not reflect reality. Furthermore, if the structure has close neighbors, the adjacent structures will alter the response of the structure considered. Investigations on soil–structure interaction and structure–soil–structure interaction have been performed mainly using numerical models. The present work addresses the dynamic response of adjacent single-degree-of-freedom models on a laminar box filled with sand. Impulse loads and simulated ground motions were applied. The standalone condition was also studied as a reference case. Models with different fundamental frequencies and slenderness were considered. Results from the impulse tests showed that the top displacement of the models with an adjacent structure was reduced compared with that of the standalone case. Changes in the fundamental frequency of the models due to the presence of an adjacent model were also observed. Results from ground motions showed amplification of the maximum acceleration and the top displacement of the models when both structures have a similar fundamental frequency.
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Vorobyov, V. S., E. L. Karelina, O. A. Bender, and K. V. Katalymova. "STATISTICAL MODELS OF PHYSIC-MECHANICAL CHARACTERISTICS OF ROADS IN THE AREA OF CULVERTS." Vestnik SibADI 15, no. 4 (September 12, 2018): 560–73. http://dx.doi.org/10.26518/2071-7296-2018-4-560-573.
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Introduction. Increased technical requirements for roads, associated with increasing axial loads, the intensity and speed of vehicles, with the actual technical condition of the roads number, engineering structures, including culverts, activation of federal and regional services to bring the parameters of road surfaces to the world standards, all listed parameters pose the task in developing the mathematical modeling methods of physical-mechanical characteristics of soils in the culverts area. Therefore, such methods allow to reduce economic costs and time for carrying out experimental research of deformations based on the monitoring results of the soil roadbed and pavement.Materials and methods. The order of technical condition of the culverts’ research, pavement and physico-mechanical characteristics of soils, methods of experimental research were discussed in the article. Moreover, the approach to carrying out experimental works on penetration of pits in places of deformations and nearby was approved. Additionally, the evaluation of the soils condition on the roadbed and the annular space of the culverts was made.Results. The schemes of deformation and elasticity, density, humidity, consistency, plasticity number, fluidity, and physical properties of the soil are determined. The engineering-geological elements, mean values of density, humidity and compaction factor are established according to the research aim. Consequently, the values of the strain modules and the modulus of elasticity are calculated on the basis of compression and stamp tests.Discussion and conclusions. The dependence of the pavement on the physic-mechanical characteristics of the soil of the roadbed is proved. The correlation-regression analysis of soil characteristics is performed on the basis of experimental research. As a result, the regression equations are obtained in the annular space of culverts and at the distance of ± 30 m nearby. As could be proved, there are irregularities in the coverage of road clothes caused by drawdown in barrier locations. The physic-mechanical characteristics of the ground and strength characteristics are increased by culverts’ transfer on distance. The application of physic-mechanical characteristics of the soil together with experimental studies makes it possible to reduce labor costs, time and cost of testing.
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Sokolov, M. V., S. M. Prostov, and O. V. Gerasimov. "Numerical simulation of subgrade soil deformation properties for prediction of earthquake resistance of structures." Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 23, no. 3 (June 28, 2021): 167–78. http://dx.doi.org/10.31675/1607-1859-2021-23-3-167-178.
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Purpose: The aim of this paper is to predict the earthquake resistance in strengthening the subgrade soils of structures. Numerical simulation of the total increment of seismic intensity during the artificial transformation and strengthening of subgrade soils based on geomechanical modeling.Research methods: Classical mathematical methods for modeling subgrade soils in a plane nonlinear problem.Originality: A new approach is developed to determine the total increment of seismic intensity using the ratio between the subsidence values of building foundations and structures before and after soil strengthening. The paper presents the prediction results of changes in seismic resistance of real objects, based on engineering and geologi cal surveys and numerical computer models. It is shown that due to the transformation of subgrade soils, the earthquake resistance can be reduced by more than 0.5 points.Practical implication: This technique can be used to adjust the score for individual objects and map the boundaries of seismic zones.
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Comegna, A., A. Coppola, V. Comegna, G. Severino, A. Sommella, and C. D. Vitale. "State-space approach to evaluate spatial variability of field measured soil water status along a line transect in a volcanic-vesuvian soil." Hydrology and Earth System Sciences 14, no. 12 (December 7, 2010): 2455–63. http://dx.doi.org/10.5194/hess-14-2455-2010.
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Abstract. Unsaturated hydraulic properties and their spatial variability today are analyzed in order to use properly mathematical models developed to simulate flow of the water and solute movement at the field-scale soils. Many studies have shown that observations of soil hydraulic properties should not be considered purely random, given that they possess a structure which may be described by means of stochastic processes. The techniques used for analyzing such a structure have essentially been based either on the theory of regionalized variables or to a lesser extent, on the analysis of time series. This work attempts to use the time-series approach mentioned above by means of a study of pressure head h and water content θ which characterize soil water status, in the space-time domain. The data of the analyses were recorded in the open field during a controlled drainage process, evaporation being prevented, along a 50 m transect in a volcanic Vesuvian soil. The isotropic hypothesis is empirical proved and then the autocorrelation ACF and the partial autocorrelation functions PACF were used to identify and estimate the ARMA(1,1) statistical model for the analyzed series and the AR(1) for the extracted signal. Relations with a state-space model are investigated, and a bivariate AR(1) model fitted. The simultaneous relations between θ and h are considered and estimated. The results are of value for sampling strategies and they should incite to a larger use of time and space series analysis.
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Sosenushkin, Evgeny, Oksana Ivanova, Elena Yanovskaya, and Yuliya Vinogradova. "Mathematical Modeling of Vibration Dampers of Vibration-Insulated Structures." EPJ Web of Conferences 248 (2021): 02009. http://dx.doi.org/10.1051/epjconf/202124802009.
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Vibration dampers are installed on the machine foundations in order to reduce the vibration level. Such technological solutions are most expedient in the case of a harmonic load with a low instability of the vibration frequency. Unfortunately, dampers do not provide such a large reduction in the dynamic effect on the base, as vibration isolation, but in some cases their efficiency turns out to be quite sufficient with a relatively simple implementation and low manufacturing cost. The use of dynamic vibration dampers gives a great effect when an increased vibration of foundations occurs during the operation of equipment in metallurgical production, for example, when processing materials by pressure, reconstructing enterprises and replacing heavy equipment. During the operation of heavy forging equipment and manipulators for various purposes, the foundations of these devices can be considered as a rigid body. The model soil on which this foundation is installed can be considered a homogeneous elastic isotropic half-space. When calculating with such mathematical models, one can use solutions of the corresponding dynamic contact problems. A comparative analysis of the effectiveness of damping foundation vibrations using different foundation models, including the model of an elastic, homogeneous half-space and a system of semi-infinite rods, the modulus of elasticity of which increases with depth according to the quadratic law, shows a fairly close agreement.
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Maragakis, Emmanuel, Mehdi Saiidi, and Saber Abdel-Ghaffar. "Response of R/C Buildings during the 1987 Whittier Narrows Earthquake." Earthquake Spectra 9, no. 1 (February 1993): 67–95. http://dx.doi.org/10.1193/1.1585706.
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Strong motion records from several reinforced concrete structures were recovered after the 1987 Whittier, California earthquake. The objective of this paper is to present the highlights of a research study which was performed to review the available data from reinforced concrete buildings, to select representative buildings, and to analyze these buildings using available computer programs for linear analysis. Linear-elastic mathematical models were built for each structure based on the physical properties of the structural members. A comparison of the results of the computer analysis to the available measured responses data showed good agreement for the majority of the buildings studied. Limited studies on the effects of damping variation and soil-structure interaction were performed. The results of this study have led to the conclusion that the linear dynamic analysis can realistically predict the response of reinforced concrete structures subjected to small to moderate earthquakes. The deviations from the elastic response were consistent with the observed damage of the structures during the Whittier earthquake.
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Liu, C. C. K., J. S. Feng, and W. Chen. "System Modeling Approach for Solute Transport Through Upper Soils." Water Science and Technology 24, no. 6 (September 1, 1991): 67–72. http://dx.doi.org/10.2166/wst.1991.0142.
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Solute transport through upper soils has been traditionally simulated by following a physically based modeling approach. Unfortunately, the application of physically based models is often limited by difficulties in solving interrelated problems of parameter identification, system boundary definition, and mathematical solution. These problems can be largely alleviated by an alternative modeling approach based on the system theory. In the system approach, dynamic relations between the input of the chemical at the soil surface and its subsequent downward movement are represented by system response functions that do not require knowledge of the intimate structure of relevant transport mechanisms. System modeling techniques were developed and applied in this study to simulate the transport of the pesticide fenamiphos in Hawaiian soils. A comparison of the calculated concentration distributions with field measurements shows that the system model provides satisfactory transport simulation.
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Pospelova, Irina G., Ivan V. Vozmishchev, and Anatoliy M. Niyazov. "Soil Disinfection Methods in Protected Ground." Elektrotekhnologii i elektrooborudovanie v APK, no. 3 (September 20, 2020): 45–49. http://dx.doi.org/10.22314/2658-4859-2020-67-3-45-49.
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Soil is a favorable environment for many microorganisms, pathogenic bacteria, fungal spores, insect eggs due to the presence of nutrients and moisture in it. Soil treatment from pests and pathogens of agricultural crops for disinfection can be carried out by chemical, energy, thermal, biological methods. The most common method is thermal. This is because many pests and pathogens have a protein structure that is easily destroyed when the temperature increases, and the thermal effect can be obtained from various heat carriers. (Research purpose) The research purpose is in developing an energy-efficient method of soil disinfection using infrared radiation. (Materials and methods) The article shows the relation between the spectral thermoradiation characteristics of soil with characteristics of infrared emitters, namely the amount of applied heat, temperature, conductivity, soil moisture, and exposure time, to justify the rational mode of operation for decontamination of the soil. The article presents a mathematical model for this purpose based on known laws that determine the relationship between the necessary parameters. (Results and discussion) Authors offered a plant for soil disinfection with infrared radiation. It was found that the high energy efficiency of the installation is achieved by a high efficiency of infrared burners and infrared radiation affects directly the object of treatment, the soil. The article presents structural-logical and mathematical models of infrared power supply. (Conclusions) Analysis of the heating kinetics equation showed that the maximum permissible speeds for the process of infrared heating of the soil depend on its thermophysical properties, the maximum permissible temperature, the area and the required depth of warming of the soil. It was found that infrared heating and a device for disinfecting the soil in this way will allow energy-efficient, convenient and fast processing.
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Sokolov, Mikhail, Sergey Prostov, and Andrey Pokatilov. "Forecast of seismic resistance of structures by the results of numerical simulation of deformation properties of soil bases." E3S Web of Conferences 303 (2021): 01015. http://dx.doi.org/10.1051/e3sconf/202130301015.
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The object of the research is the forecast of seismic resistance when strengthening the soil foundations of structures. The purpose of the work is to numerically estimate the total increment of seismic intensity during artificial transformation and strengthening of foundation soils based on the results of geomechanical modeling. The study is based on classical mathematical methods for modeling soil foundations in a flat nonlinear setting. A new approach to determining the total increment of seismic intensity is presented, based on determining the ratio of the values of subsidence of the foundations of buildings and structures before and after soil strengthening. The paper presents the results of predicting changes in seismic resistance for real objects, obtained from the data of engineering and geological surveys and numerical computer models. It was found that due to the transformation of soil foundations, seismic resistance can decrease by more than 0.5 points. This technique can be used both to adjust the scoring for individual objects and to clarify the boundaries of seismic zones on OCP maps.
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Khoshnoudian, Faramarz, and Ehsan Ahmadi. "Effects of pulse period of near-field ground motions on the seismic demands of soil-MDOF structure systems using mathematical pulse models." Earthquake Engineering & Structural Dynamics 42, no. 11 (February 28, 2013): 1565–82. http://dx.doi.org/10.1002/eqe.2287.
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Fang, Y., M. Huang, C. Liu, H. Y. Li, and L. R. Leung. "A generic biogeochemical module for earth system models." Geoscientific Model Development Discussions 6, no. 2 (June 13, 2013): 3211–40. http://dx.doi.org/10.5194/gmdd-6-3211-2013.
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Abstract. Physical and biogeochemical processes regulate soil carbon dynamics and CO2 flux to and from the atmosphere, influencing global climate changes. Integration of these processes into earth system models (e.g. community land models – CLM), however, currently faces three major challenges: (1) extensive efforts are required to modify modeling structures and to rewrite computer programs to incorporate new or updated processes as new knowledge is being generated, (2) computational cost is prohibitively expensive to simulate biogeochemical processes in land models due to large variations in the rates of biogeochemical processes, and (3) various mathematical representations of biogeochemical processes exist to incorporate different aspects of fundamental mechanisms, but systematic evaluation of the different mathematical representations is difficult, if not impossible. To address these challenges, we propose a new computational framework to easily incorporate physical and biogeochemical processes into land models. The new framework consists of a new biogeochemical module with a generic algorithm and reaction database so that new and updated processes can be incorporated into land models without the need to manually set up the ordinary differential equations to be solved numerically. The reaction database consists of processes of nutrient flow through the terrestrial ecosystems in plants, litter and soil. This framework facilitates effective comparison studies of biogeochemical cycles in an ecosystem using different conceptual models under the same land modeling framework. The approach was first implemented in CLM and benchmarked against simulations from the original CLM-CN code. A case study was then provided to demonstrate the advantages of using the new approach to incorporate a phosphorus cycle into the CLM model. To our knowledge, the phosphorus-incorporated CLM is a new model that can be used to simulate phosphorus limitation on the productivity of terrestrial ecosystems.
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Težak, Stanković, and Kovač. "Dependence Models of Borehole Expansion on Explosive Charge in Spherical Cavity Blasting." Geosciences 9, no. 9 (September 1, 2019): 383. http://dx.doi.org/10.3390/geosciences9090383.
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In geotechnical practice, it is often necessary to improve the properties of soil and rock in which different structures are built. For this purpose, spherical cavity blasting can be applied to expand the borehole. Such expansion may incorporate various constructive elements such as anchors and thus stabilize the slope. The paper presents the method for determining the increased volume, expansion, and deepening of the borehole as a result of spherical cavity blasting. In addition, mathematical models describing the dependency of the borehole expansion on the amount of explosive charge are presented. The models are mutually compared with the Akaike information criterion.
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Buchta, Vojtech. "Experimental Testing the Interaction of Fiber-Concrete Foundation Slab and Subsoil and Compare the Results with Numerical Models." Advanced Materials Research 1020 (October 2014): 227–32. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.227.
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We solve interaction between the foundation base and the subsoil in civil engineering quite often. For the determination of stress in foundation structure is needed to determine the influence of the stiffness respectively pliability of subsoil to structural internal forces, and vice versa, how the stiffness of the foundation structure affects the resulting subsidence. It is necessary to compare the mathematical models with the actual behavior of the real structure. In 2013 was realised static load on testing equipment in the campus of Faculty of Civil Engineering, VSB–TU Ostrava. Dimensions of test element was 2000 x 2000 x 170 mm and the concrete slab was reinforced with steel fiber type DRAMIX 3D 65/60B6. During measurements were performed and recorded: tensometrical measurement on the surface of the slab, tensometrical measurement inside the slab, measuring the vertical load, measurement of the vertical deformation, measuring the stress on the interface of the slab and soil. Were also developed numerical models of this test in program Nexis. Comparison the test results with numerical models are presented in this paper. [1,9]
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Tiutkin, О. L., and D. Y. Ihnatenko. "DETERMINATION OF RATIONAL PARAMETERS OF SUPPORTING STRUCTURES MADE OF SOIL-CEMENT PILES ON LANDSLIDE-PRONE SLOPES." Science and Transport Progress. Bulletin of Dnipropetrovsk National University of Railway Transport, no. 6(90) (April 8, 2021): 97–105. http://dx.doi.org/10.15802/stp2020/225281.
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Purpose. The article proposes a method for determining the rational parameters of supporting structures made of soil-cement piles on landslide-prone slopes. Methodology. To achieve this purpose, the authors performed comparative calculations of finite-element models of landslide-prone layered slope with the arrangement of supporting structures of soil-cement piles: vertical, located at an angle to the vertical axis, combined with a concrete grillage, without grillage, with different diameters, with different distances between piles, but of the same length, which is justified by the location determined by preliminary calculations of the sliding surface. Findings. According to the results of calculating the contact problem of the interaction of the soil mass and the supporting structure, the regularities of formation of strength and stability of the reinforced landslide-prone slope were obtained, which makes it possible to predict its geomechanical stability depending on the possible location of the sliding surface curve. The method of increasing the stability coefficient of the soil slope depending on the variation of the parameters of the soil-cement supporting pile structure is substantiated. Numerical calculations substantiate the parameters of soil-cement pile supporting structures – the length of the piles, their diameter, the distance between the piles, the angle of their inclination and the feasibility of combining the piles with a concrete grillage. Originality. For the first time, the formation regularities of strength and stability of soil-cement supporting structure for strengthening the landslide-prone slopes are obtained, which makes it possible to predict their geomechanical stability depending on the possible location of the sliding surface curve. For the first time, the dependences of changes in absolute displacements, relative deformations, coefficients of strength, stability, as well as Mises stresses in the elements of supporting structures of soil-cement piles on the angle of their inclination, distance between piles and the presence of a concrete grillage that joins them. Methods for assessing and predicting the landslide danger of soil slopes were further developed, which allowed to substantiate the method of increasing the strength coefficient depending on the variation of the parameters of the soil-cement supporting structure. For the first time, the parameters of the method of increasing the stability of landslide-prone slopes with pile supporting structures based on the complex mathematical and centrifugal modeling using real landslides and similarity criteria are substantiated. Practical value. The authors have developed and patented a method of strengthening landslide slopes with the help of soil-cement piles, combined with a concrete grillage, located perpendicular to the movement vector of the landslide body.
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Sunmonu, Musliu Olushola. "Prediction and Determination of Weight and Lycopene Contents of Stored Tomatoes (Lycopersicon esculentum)." International Journal of Engineering Research in Africa 15 (April 2015): 141–49. http://dx.doi.org/10.4028/www.scientific.net/jera.15.141.
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The need to develop empirical model equations that describe the changes in the nutritional compositions of stored tomatoes under different environmental conditionsA study was carried out to predict and determine the weight and lycopene contents of stored tomatoes. Three sets of four different types of passive evaporative cooling structures made of clay and aluminium were designed and constructed as part of the study. One set consists of four separate cooling chambers. Two cooling chambers were made with aluminium container (cylindrical and square shapes) and the other two were made of clay container (cylindrical and square). These four containers were separately inserted inside a bigger clay pot inter-spaced with clay soil of 5 cm (to form tin-in-pot, pot-in-pot, tin-in-wall and wall-in wall) with the outside structure wrapped with jute sack. The other two sets followed the same pattern with interspacing of 7 cm and 10 cm, respectively. The set with 7 cm interspace served as the control in which the interspace soil and the jute sacks were constantly wetted at intervals of between 2 to 4 hours depending on the rate of evaporation with water at room temperature. The 5 cm and 10 cm interspaced soil were constantly wetted with salt solution (sodium chloride) at the same interval to keep the soil in moist condition. Freshly harvested matured tomatoes (globe variety) were used for the experiments and the temperature and relative humidity inside the cooling chambers were monitored daily . The weight, lycopene contents, bacterial and fungal counts of these produce were determined at intervals of three days for a period of sixteen days. Mathematical models (using essential regression software package) were developed to predict the weight and lycopene contents of the stored produce at various conditions considered in the study. By substituting different values of predictor variables into the model equations, the expected values of weight and lycopene contents of stored tomatoes were predicted. Further analysis was done using a paired sample t-test using SPSS 16.0 computer software package to show the level of significance between the mean of observed and the predicted values for all the models developed. The mathematical models developed are reasonably accurate to predict the storability of fruits and vegetables in passive evaporative cooling structures.
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Molina, Julio C., Carlito Calil Júnior, and Roberto R. de Freitas. "Mathematical model to estimate of the deterioration of wooden poles in contact with soil used in rural areas." Engenharia Agrícola 31, no. 5 (October 2011): 1015–26. http://dx.doi.org/10.1590/s0100-69162011000500019.
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In São Paulo State, mainly in rural areas, the utilization of wooden poles is observed for different purposes. In this context, wood in contact with the ground presents faster deterioration, which is generally associated to environmental factors and, especially to the presence of fungi and insects. With the use of mathematical models, the useful life of wooden structures can be predicted by obtaining "climatic indexes" to indicate, comparatively among the areas studied, which have more or less tendency to fungi and insects attacks. In this work, by using climatological data of several cities at São Paulo State, a simplified mathematical model was obtained to measure the aggressiveness of the wood in contact with the soil.
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Jiang, Hua, Yu Sheng Jiang, Mao Lan Huang, and Zhi Qiang Chen. "Study on Soil Improvement of TBM’S Commencement and Arrival in Water-Rich Sand Stratum." Applied Mechanics and Materials 90-93 (September 2011): 2119–24. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.2119.
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In order to keep the safety construction during TBM’S commencement and arrival more and avoid surface settlement and failure accidents happening at the joint areas of TBM’S commencement and arrival, according to mechanical properties and deformation modes of water-rich sand stratum, mechanical and mathematical models are established, and theoretical equations of longitudinal improvement scope based on strength and stability theory are deduced. At the same time, according to geometric structure of TBM and permeability requirement of improved stratum, geometric criterions are proposed. By monitoring and analyzing the whole process of stratum improvement at the joint areas of TBM’S commencement and arrival in line 2 lot 2202 of Shenzhen Metro, longitudinal improvement theory and stratum adaptability of various improvement methods are verified, it provides a reliable theoretical basis for stratum improvement in water-rich sand stratum.
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Sidnyaev, Nikolay Ivanovich, Vasilii Ivanovich Vasiliev, and Yuliya Sergeevna Ilina. "Calculation methods of non-stationary temperature fields influence on foundation in cryolithozone." Арктика и Антарктика, no. 2 (February 2020): 106–25. http://dx.doi.org/10.7256/2453-8922.2020.2.32405.
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This article is devoted to the mathematical modeling and computing experiment in problems of temperature fields forecast in continuous foundations in cryolithozone, which will provide a qualitative approach to non-stationary thermal calculations for making design decisions to ensure the stability and reliability of bases and foundations of buildings in the Arctic zone. The article formulates the problem of forecasting by determining changes in the temperature, areal distribution, thickness, and vertical structure of permafrost, seasonal and perennial freezing of the soil, their temperature strength state, and properties in connection with the construction of buildings. Presented mathematical calculations are based mainly on the assumption of a non-stationary process of heat exchange. Mathematical models for determining depth of thawing are considered. The problem of determining the temperature in the basement of the foundation, limited on the one side, in which the temperature depends on only one coordinate with the condition that the surface temperature of the permafrost soil undergoes periodic fluctuations around zero value under the influence of external influences, has been solved. It is demonstrated that the two-dimensional problem of permafrost ground with a semi-infinite foundation thickness can be generalized even more. The problem is formulated in the form of a differential equation of heat balance taking into account the heat flux, which varies according to the Fourier’s law.
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LYAPIN, VICTOR, and MAKSIM SAMOKHVALOV. "STUDYING OF ELECTRICAL PARAMETERS OF PLANT AND SOIL OBJECTS AS ACTIVE-CAPACITIVE BIPOLAR." Elektrotekhnologii i elektrooborudovanie v APK 4, no. 41 (December 2020): 125–36. http://dx.doi.org/10.22314/2658-4859-2020-67-4-125-136.
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The key elements of the system for predicting electromagnetic damage are the electromagnetic source and the biological object. There is no complex of analytical models and programs for predicting damaging and critical conditions of electromagnetic impact on biological objects, as well as software components that implement developed mathematical models of real electromagnetic processes occurring in biological structures at different levels of the organization. (Research purpose) The research purpose is in developing a system for determining the electrical parameters of soil and biological objects (to develop ideas about the processes in the structures of different levels of organization of biological objects): in agricultural technologies for diagnostics of plant objects and soil; in laboratory conditions as a medium for creating and studying new electrical technologies, methods of analysis and processing of information signals. (Materials and methods) The method for monitoring electrical properties consists in applying a voltage with a constant and low-frequency component to a plant object, and simultaneously measuring the DC current, capacitive and resistive components of the low-frequency impedance. (Results and discussion) The proposed system for determining the electrical parameters of plant objects and soil allows to visualize the original signal; to perform calculation of informative parameters and statistical processing of the informative signal of a plant object and soil (construction of distribution laws, calculation of variance, mathematical expectation); to calculate the spectrum of the informative signal; to record the values of any of the specified informative parameters, both in real time and at the selected moment; to make time dependencies of informative parameters of plant objects and soil. (Conclusions) Authors implemented modes for measuring local DC resistance and monitoring the capacitive and resistive components in the area of electrical contact of two needles and other measuring electrodes with plant objects in the low-frequency range.
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Hou, Hongwei, Shihu Gao, Qianqian Guo, Long Chen, Bing Wu, and Lei Wang. "Dynamic Characteristics of Deeply Buried Spherical Biogas Digesters in Viscoelastic Soils." Advances in Mathematical Physics 2018 (October 18, 2018): 1–9. http://dx.doi.org/10.1155/2018/9349175.
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The harmonic vibration characteristics of a deeply buried spherical methane tank in viscoelastic soil subjected to cyclic loading in the frequency domain are investigated. The dynamic behavior of the soil is described based on the theory of fractional derivatives. By introducing potential functions, the closed-form expressions for the displacement and the stress of the viscoelastic soil surrounding the deeply buried spherical methane tank are obtained. Two die structures are considered: a homogeneous elastic medium and a shell structure. Based on the theory of elastic motion and the Flügge theory, analytic solutions for the dynamic responses of the spherical methane tank in a fractional-derivative viscoelastic soil are derived explicitly. Analytic solution expressions of the undetermined coefficients are determined by using the continuum boundary conditions. The system dynamic responses to the homogeneous elastic medium and the shell structure and the influences of the parameters of the fractional derivative, soil, and die on the dynamic characteristic of the system are compared and analyzed. The results indicate a significant difference between the dynamic responses of the die structures for the two models.
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Mourlas, Christos, Neo Khabele, Hussein A. Bark, Dimitris Karamitros, Francesca Taddei, George Markou, and Manolis Papadrakakis. "Effect of Soil–Structure Interaction on Nonlinear Dynamic Response of Reinforced Concrete Structures." International Journal of Structural Stability and Dynamics 20, no. 13 (October 14, 2020): 2041013. http://dx.doi.org/10.1142/s0219455420410138.
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Investigating the nonlinear dynamic response of reinforced concrete (RC) structures is of significant importance in understanding the expected behavior of these structures under dynamic loading. This becomes more crucial during the design of new or the assessment of the existing RC structures that are located in seismically active areas. The numerical simulation of this problem through the use of detailed 3D modeling is still a subject that has not been investigated thoroughly due to the significant challenges related to numerical instabilities and excessive computational demand, especially when the soil–structure interaction (SSI) phenomenon is accounted for. This study aims at presenting a nonlinear simulation tool to investigate this numerically cumbersome problem in order to provide further inside into the SSI effect on RC structures under nonlinear dynamic loading conditions. A detailed 3D numerical model of full-scale RC structures considering the SSI effect through modeling the nonlinear frame and soil domain is performed and discussed herein. The constructed models are subjected to dynamic loading conditions and an elaborate investigation is presented considering different type of structures, material properties of soil domains and depths. The RC structures and the soil domains are modeled through 8-noded hexahedral isoparametric elements, where the steel bar reinforcement of concrete is modeled as embedded beam and truss finite elements. The Ramberg–Osgood constitutive law was used for modeling the soil domain. It was shown that the SSI effect can significantly increase the flexibility of the system, altering the nonlinear dynamic response of the RC frames causing local damages that are not observed when the fixed-base model is analyzed. Furthermore, it was found that the structures founded on soft soil developed larger base-shear compared to the fixed-base model which is attributed to resonance phenomena connected to the SSI effect and the imposed accelerograms.
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Grigorev, Igor, Olga Kunickaya, Albert Burgonutdinov, Evgeniy Tikhonov, Valentin Makuev, Sergey Egipko, Edward Hertz, and Maksim Zorin. "Modeling the effect of wheeled tractors and skidded timber bunches on forest soil compaction." Journal of Applied Engineering Science 19, no. 2 (2021): 439–47. http://dx.doi.org/10.5937/jaes0-28528.
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An increasing demand for forest products incites a large number of log transportation operations, which may lead to negative consequences for the soil and the ecosystem as a whole. This paper is focused on establishing a mathematical model to estimate the soil deformation and compaction processes under tires of wheeled forest machines and individual components of the skidding system such as forwarder, limbs, butts, and tops of tree-lengths in high latitudes, permafrost soil and forests. The method applied is based on simulating the impact processes of elastic tires and the skidding system on the soil through a mathematical device for the measurement of the compaction parameters for different types of soil and the size of the shelterbelt. The effectiveness of the proposed models was evaluated according to experimental results. The influence of the rheological (elastic, viscous, and plastic) properties of soil were studied. The elasticity of tires and the running speed of forest machines can help to control the performance of forest machines. This can be done by reducing the pressure exerted on the soil and increasing the number of skidder passes 1.5-2-fold. Comparative analysis showed that the calculated data differ from the experimental ones by no more than 10%. The obtained results and the developed model will allow for a qualitative and quantitative assessment of technological impact on the soil during the projecting maps for logging operations.
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Zhuravleva, V. V., A. S. Manicheva, and A. A. Martynova. "Analysis of the Mathematical Model of Photosynthesis in Protected Ground." Izvestiya of Altai State University, no. 4(114) (September 9, 2020): 86–91. http://dx.doi.org/10.14258/izvasu(2020)4-13.
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The problem of predicting changes in the intensity of photosynthesis associated with changes in the lighting mode, atmospheric carbon dioxide concentration, and the temperature is urgent. Appropriate models can help choose the optimal mode of growing plants in protected soil, as well as serve as a basis for predicting the consequences of global climate change. It is noted that in the conditions of protected soil, the most significant factor is the illumination of plants.
The aim of the research is to construct an algorithm for additional illumination of plants in protected ground conditions based on a mathematical model of photosynthesis. The authors introduced the value of the efficiency of additional illumination and studied its dependence on the coefficient of light transmission of the roof.
The solution of the main task of the study is achieved by the fact that the light mode in protected ground structures is carried out on the basis of additional illumination to the ideal (optimal) for this type of plant. The entered value of the efficiency of additional illumination shows what energy costs will be for the production of photosynthesis products and, as a result, allows estimation of the economic costs.
The considered method of artificial lighting of plants makes it possible to effectively use both sunlight and artificial lighting, providing an optimal lighting mode all year round, and allows to increase the intensity of photosynthesis by 50-80 %.
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Sharonov, Ivan, Vladimir Кurdyumov, Yuri Isaev, and Viktor Kurushin. "The optimisation of the cylinder-spiral soil-cultivating roller." E3S Web of Conferences 193 (2020): 01001. http://dx.doi.org/10.1051/e3sconf/202019301001.
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Designed cylinder-tillage spiral skating rink with spiral work items, which form a fine lumpy structure of the sowing layer of soil with grain size corresponding to agrotechnical requirements, while helping the soil surface, mulching the top layer of soil over the seeds, seal the depth of their placement, providing the required contact of seeds with soil is necessary to ensure the uniformity of germination. At the theoretical level, it is determined that an increase in the pinching angle leads to an increase in the size of the hollow smooth pipe of the roller. This occurs while increasing the depth of deformation of the layer of crushed soil and the radius of the clump of soil. However, a change in the radius of a hollow smooth roller of more than 0.3 m does not lead to a slight increase in the pinching angle. Therefore, increasing the radius of the hollow smooth roller over 0.3 m is not rational, as it will increase the metal content of the structure. After analyzing the obtained mathematical models of the soil treatment process with a roller, we optimized the parameters of a cylindrical-spiral roller: speed of 11 km/h, mass of ballasting loads of 100 kg, step of the spiral turn of 40 mm, and the departure of the spiral screw of 35 mm. These modes ensure the formation of a qualitatively compacted soil layer in the zone of planting seeds of agricultural crops, which is confirmed by the maximum value of the processing quality criterion for matching the density of the soil after rolling with a cylindrical-spiral roller CCS = 0.98 (while the density of the sown layer addition 1185...1215 kg/m3), which fully satisfies the agrotechnical optimum. The yield of barley of the Nutans-553 variety became higher after the use of an innovative cylindrical-spiral roller by 6.4 % and 9.3 %, respectively, of the yield after the impact of serial ККSh rollers and ring rollers of the seeding machine. In the course of evaluating the metal consumption of structures of the innovative cylindrical-spiral roller and the ring-spur roller, a difference of 70% per unit width of the grip was revealed.
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Ilie, Iulia, Peter Dittrich, Nuno Carvalhais, Martin Jung, Andreas Heinemeyer, Mirco Migliavacca, James I. L. Morison, et al. "Reverse engineering model structures for soil and ecosystem respiration: the potential of gene expression programming." Geoscientific Model Development 10, no. 9 (September 25, 2017): 3519–45. http://dx.doi.org/10.5194/gmd-10-3519-2017.
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Abstract. Accurate model representation of land–atmosphere carbon fluxes is essential for climate projections. However, the exact responses of carbon cycle processes to climatic drivers often remain uncertain. Presently, knowledge derived from experiments, complemented by a steadily evolving body of mechanistic theory, provides the main basis for developing such models. The strongly increasing availability of measurements may facilitate new ways of identifying suitable model structures using machine learning. Here, we explore the potential of gene expression programming (GEP) to derive relevant model formulations based solely on the signals present in data by automatically applying various mathematical transformations to potential predictors and repeatedly evolving the resulting model structures. In contrast to most other machine learning regression techniques, the GEP approach generates readable models that allow for prediction and possibly for interpretation. Our study is based on two cases: artificially generated data and real observations. Simulations based on artificial data show that GEP is successful in identifying prescribed functions, with the prediction capacity of the models comparable to four state-of-the-art machine learning methods (random forests, support vector machines, artificial neural networks, and kernel ridge regressions). Based on real observations we explore the responses of the different components of terrestrial respiration at an oak forest in south-eastern England. We find that the GEP-retrieved models are often better in prediction than some established respiration models. Based on their structures, we find previously unconsidered exponential dependencies of respiration on seasonal ecosystem carbon assimilation and water dynamics. We noticed that the GEP models are only partly portable across respiration components, the identification of a general terrestrial respiration model possibly prevented by equifinality issues. Overall, GEP is a promising tool for uncovering new model structures for terrestrial ecology in the data-rich era, complementing more traditional modelling approaches.
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Pollard, P. C., E. v. Münch, P. A. Lant, and P. F. Greenfield. "The impact of microbiological tools on mathematical modelling of biological wastewater treatment." Water Science and Technology 36, no. 10 (November 1, 1997): 97–108. http://dx.doi.org/10.2166/wst.1997.0368.
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Biological systems are being used to treat an increasing range of complex wastes; domestic and industrial wastewaters containing nutrients and refractory organic compounds, soil sites and groundwater contaminated by organics, and organic solid residues. These treatment processes rely on micro-organisms and, more than ever before, must deliver higher quality outcomes at higher levels of reliability to protect the environment. At the same time, pressures to deliver cost-effective treatment have increased. The challenge for these biological treatment technologies and the associated engineering is to achieve the environmental and economic goals simultaneously. Mathematical modelling is an essential component in developing a detailed understanding of such processes, as well as design guidelines and suitable operating and control strategies. This paper provides a brief summary of the development of mathematical models for biological waste treatment systems, why they have become increasingly complex and how certain microbiological tools can provide the experimental means to validate more complex segregated and structured models of biological behaviour. With a number of specific modelling examples in the field of wastewater treatment, we illustrate the potential of these modern microbiological tools and their implications for gaining an improved understanding of biological waste treatment.
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Fang, Y., M. Huang, C. Liu, H. Li, and L. R. Leung. "A generic biogeochemical module for Earth system models: Next Generation BioGeoChemical Module (NGBGC), version 1.0." Geoscientific Model Development 6, no. 6 (November 13, 2013): 1977–88. http://dx.doi.org/10.5194/gmd-6-1977-2013.
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Abstract. Physical and biogeochemical processes regulate soil carbon dynamics and CO2 flux to and from the atmosphere, influencing global climate changes. Integration of these processes into Earth system models (e.g., community land models (CLMs)), however, currently faces three major challenges: (1) extensive efforts are required to modify modeling structures and to rewrite computer programs to incorporate new or updated processes as new knowledge is being generated, (2) computational cost is prohibitively expensive to simulate biogeochemical processes in land models due to large variations in the rates of biogeochemical processes, and (3) various mathematical representations of biogeochemical processes exist to incorporate different aspects of fundamental mechanisms, but systematic evaluation of the different mathematical representations is difficult, if not impossible. To address these challenges, we propose a new computational framework to easily incorporate physical and biogeochemical processes into land models. The new framework consists of a new biogeochemical module, Next Generation BioGeoChemical Module (NGBGC), version 1.0, with a generic algorithm and reaction database so that new and updated processes can be incorporated into land models without the need to manually set up the ordinary differential equations to be solved numerically. The reaction database consists of processes of nutrient flow through the terrestrial ecosystems in plants, litter, and soil. This framework facilitates effective comparison studies of biogeochemical cycles in an ecosystem using different conceptual models under the same land modeling framework. The approach was first implemented in CLM and benchmarked against simulations from the original CLM-CN code. A case study was then provided to demonstrate the advantages of using the new approach to incorporate a phosphorus cycle into CLM. To our knowledge, the phosphorus-incorporated CLM is a new model that can be used to simulate phosphorus limitation on the productivity of terrestrial ecosystems. The method presented here could in theory be applied to simulate biogeochemical cycles in other Earth system models.
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Mikova, Marina N., and Evgeniya N. Akbulyakova. "A study of clay soil deformability over time." Vestnik MGSU, no. 12 (December 2020): 1654–62. http://dx.doi.org/10.22227/1997-0935.2020.12.1654-1662.
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Introduction. The study is focused on the process of clay soil deformation over time, provided that this soil, featuring varied liquidity index values, is exposed to constant load. The consolidation process is slow; it can run for years or decades in clay soils. Long-term deformations of clay soils must be taken into account in the course of design and construction of buildings and structures, on the one hand, and in the process of analyzing settlement rates and maximal settlement values for foundation beds, on the other hand.
Materials and methods. Semi-solid, low-plasticity, high-plasticity, very high plasticity, and free-flowing clay samples were used in the study. The parameters under research encompass relative and absolute deformation of soil samples over time. These parameters are dependent on the soil liquidity index value. All laboratory tests were carried out in compression machines, and tested samples were exposed to constant load. The experimental data thus obtained were supplemented by the information provided M.A. Koltunov.
Results. Values of absolute deformations and time-to-relative deformation ratios were obtained for clays having different liquidity index values. The analysis of the time-to-relative deformation curves shows that deformations develop over time at different rates depending on the liquidity index of clay soils. An increase in the value of the liquidity index boosts the values of initial deformations and deformation rates.
Conclusions. The equations, derived in the course of the study, allow to analyze the deformation of semi-solid, low-plasticity, high-plasticity, very high plasticity, and free-flowing clays for various time ranges depending on the initial clay liquidity index. The accuracy of the approximation of these equations varies from 0.801 to 0.993, which makes it possible to characterize these dependences as high quality mathematical models.