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Journal articles on the topic 'Crops and water mathematical models'
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1
Abdulaev, A., and N. A. Omorova. "MATHEMATICAL MODELS OF DISCRETE IRRIGATION TECHNOLOGIES FOR AGRICULTURAL CROPS IN FURROWS." Herald of KSUCTA n a N Isanov, no. 2-2021 (June 24, 2021): 258–62. http://dx.doi.org/10.35803/1694-5298.2021.2.258-262.
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The article discusses mathematical modeling of discrete technology of irrigation of crops by furrows, based on joint consideration of the system of Saint-Venan equations and equations of moisture and heat transfer in soils. The boundary conditions are described in detail in accordance with the technologies of irrigation by furrows at discrete water supply.
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Kumar, R., M. K. Jat, and V. Shankar. "Methods to estimate irrigated reference crop evapotranspiration – a review." Water Science and Technology 66, no. 3 (August 1, 2012): 525–35. http://dx.doi.org/10.2166/wst.2012.191.
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Efficient water management of crops requires accurate irrigation scheduling which, in turn, requires the accurate measurement of crop water requirement. Irrigation is applied to replenish depleted moisture for optimum plant growth. Reference evapotranspiration plays an important role for the determination of water requirements for crops and irrigation scheduling. Various models/approaches varying from empirical to physically base distributed are available for the estimation of reference evapotranspiration. Mathematical models are useful tools to estimate the evapotranspiration and water requirement of crops, which is essential information required to design or choose best water management practices. In this paper the most commonly used models/approaches, which are suitable for the estimation of daily water requirement for agricultural crops grown in different agro-climatic regions, are reviewed. Further, an effort has been made to compare the accuracy of various widely used methods under different climatic conditions.
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Alabdulkader, A. M., A. I. Al-Amoud, and F. S. Awad. " Optimization of the cropping pattern in Saudi Arabia using a mathematical programming sector model." Agricultural Economics (Zemědělská ekonomika) 58, No. 2 (March 5, 2012): 56–60. http://dx.doi.org/10.17221/8/2011-agricecon.
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A mathematical sector model has been formulated to optimize the cropping pattern in Saudi Arabia aiming at maximizing the net annual return of the agricultural sector in Saudi Arabia and ensuring the efficient allocation of the scarce water resources and arable land among the competing crops. The results showed the potential for Saudi Arabia to optimize its cropping pattern and to generate an estimated net return equivalent to about 2.42 billion US$ per year. The optimized cropping pattern in Saudi Arabia has been coupled with about 53% saving in the water use and about 48% reduction in the arable land use compared to the base-year cropping pattern. Comparable weights was given to different crop groups by allocating about 48.4%, 35.4%, 13.1%, and 3.2% to grow cereals, fruits, forages, and vegetables, respectively. These findings were in line with the national strategy to rationalize the cultivation of water-intensive crops in favour of highly water-efficient crops.
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Pereira, Rui, Sofia Lopes, Amélia Caldeira, and Victor Fonte. "Optimized Planning of Different Crops in a Field Using Optimal Control in Portugal." Sustainability 10, no. 12 (December 6, 2018): 4648. http://dx.doi.org/10.3390/su10124648.
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Climate change is a proven fact. In the report of 2007 from IPCC, one can read that global warming is an issue to be dealt with urgently. In many parts of the world, the estimated rise of temperature (in a very near future) is significant. One of the most affected regions is the Iberian Peninsula, where the increasing need for water will very soon be a problem. Therefore, it is necessary that decision makers are able to decide on all issues related to water management. In this paper, we show a couple of mathematical models that can aid the decision making in the management of an agricultural field at a given location. Having a field, in which different crops can be produced, the solution of the first model indicates the area that should be used for each crop so that the profit is as large as possible, while the water spent is the smallest possible guaranteeing the water requirements of each crop. Using known data for these crops in Portugal, including costs of labour, machines, energy and water, as well as the estimated value of the products obtained, the first mathematical model developed, via optimal control theory, obtains the best management solution. It allows creating different scenarios, thus it can be a valuable tool to help the farmer/decision maker decide the crop and its area to be cultivated. A second mathematical model was developed. It improves the first one, in the sense that it allows considering that water from the rainfall can be collected in a reservoir with a given capacity. The contribution of the collected water from the rainfall in the profit obtained for some different scenarios is also shown.
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Metselaar, Pinheiro, and Lier. "Mathematical Description of Rooting Profiles of Agricultural Crops and its Effect on Transpiration Prediction by a Hydrological Model." Soil Systems 3, no. 3 (July 8, 2019): 44. http://dx.doi.org/10.3390/soilsystems3030044.
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The geometry of rooting systems is important for modeling water flows in the soil-plant-atmosphere continuum. Measured information about root density can be summarized in adjustable equations applied in hydrological models. We present such descriptive functions used to model root density distribution over depth and evaluate their quality of fit to measured crop root density profiles retrieved from the literature. An equation is presented to calculate the mean root half-distance as a function of depth from root length density profiles as used in single root models for water uptake. To assess the importance of the shape of the root length density profile in hydrological modeling, the sensitivity of actual transpiration predictions of a hydrological model to the shape of root length density profiles is analyzed using 38 years of meteorological data from Southeast Brazil. The cumulative root density distributions covering the most important agricultural crops (in terms of area) were found to be well described by the logistic function or the Gompertz function. Root length density distribution has a consistent effect on relative transpiration, hence on relative yield, but the common approach to predict transpiration reduction and irrigation requirement from soil water storage or average water content is shown to be only partially supported by simulation results.
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McCash, Luthais B., Salman Akhtar, Sohail Nadeem, and Salman Saleem. "Entropy Analysis of the Peristaltic Flow of Hybrid Nanofluid Inside an Elliptic Duct with Sinusoidally Advancing Boundaries." Entropy 23, no. 6 (June 9, 2021): 732. http://dx.doi.org/10.3390/e23060732.
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Peristaltic flow of hybrid nanofluid inside a duct having sinusoidally advancing boundaries and elliptic cross-section is mathematically investigated. The notable irreversibility effects are also examined in this mathematical research by considering a descriptive entropy analysis. In addition, this work provides a comparison analysis for two distinct nanofluid models: a hybrid model (Cu-Ag/water) and a phase flow model (Cu/water). A comprehensive graphical description is also provided to interpret the physical aspects of this mathematical analysis.
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Rigas, F., E. Sachini, G. Chatzoudis, and N. Kanellopoulos. "Effects of a polymeric soil conditioner on the early growth of sunflowers." Canadian Journal of Soil Science 79, no. 1 (February 1, 1999): 225–31. http://dx.doi.org/10.4141/s98-017.
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In sandy soils water shortage may result in the loss of crops. During prolonged droughts an increase in time to wilting by a few days may diminish yield losses. Soil incorporation of highly water-swelling polymers (hydrogels) to increase time to wilting and to increase biomass production was investigated. The soil conditioner used was a post cross-linked sulphonated polystyrene. The soil used was a sand with sunflowers (Helianthus annuus) grown for 10 wk. The plant parameters examined were emergence time, growth, wilting time and aboveground biomass. Soil parameters included field capacity, wilting point and available water. These parameters were correlated with the polymer content in the soil and the degree of water equilibrium swelling of the polymers. The tests were performed in pots under water deficiency conditions. Second-order factorial designs were applied and the resultant mathematical models proved adequate and reasonable. The presence of soil conditioner resulted in improvements of all parameters investigated. Key words: Arid soils, water economy, soil conditioners, experimental design
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Babazadeh, Hossein, Hossein Ardalani, Isaya Kisekka, and Gerrit Hoogenboom. "Simultaneous water, salinity and nitrogen stresses on tomato (Solanum lycopersicum) root water uptake using mathematical models." Journal of Plant Nutrition 44, no. 2 (September 23, 2020): 282–95. http://dx.doi.org/10.1080/01904167.2020.1822400.
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Shujie, Wang, Li Tong, Li Xiaohul, Bai He, and Zhou Yajin. "Modeling method of static contact angle of drops on leaf surface of the typical crops." Bangladesh Journal of Botany 49, no. 2 (September 20, 2020): 349–55. http://dx.doi.org/10.3329/bjb.v49i2.49316.
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It was found that the pesticide droplets have always showed an elliptical shape when detecting the contact angle of the pesticide droplets on the Ken-Nian No. 1 corn leaves. In order to describe more accurately the spreading behavior of the pesticide droplets on these corn leaves, present authors have established a contact angle prediction model. In this experiment, the leaves in Ken-Nian No. 1 corn at jointing stage were used as test materials and were sprayed with different concentrations of Kresoxim-methyl water dispersant pesticide. The simulation test has used the modified HAD-HB contact angle tester to measure the four variates, longitudinal and horizontal spreading diameter named ‘a’ and ‘b’, longitudinal and lateral contact angle named ‘α’ and ‘β’. The mathematical relationship models between ‘α-ab’ and ‘β-ab’ were established by using Matlab. The Adjusted R-square of two models are above 0.98. The test results showed that the predicted values of the models were within ± 2 degrees of the actual measured value.
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Bai, Chen, Lixiao Yao, Cheng Wang, Yongxuan Zhao, and Weien Peng. "Simulation of Water–Energy Nexus of the Spatial Patterns of Crops and Irrigation Technologies in the Cascade Pump Station Irrigation District." Water 14, no. 7 (March 30, 2022): 1090. http://dx.doi.org/10.3390/w14071090.
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Cascade pump station irrigation districts (CPSIDs) consume vast amounts of irrigation water and energy. The aim of this study was to adjust the spatial patterns of crops and irrigation technologies in the CPSID to reduce the consumption of water and energy under the condition of conserving crop irrigation water. The irrigation district (ID) is divided into several sub-districts according to the topography elevation difference and the distribution of cascade pump stations (CPSs). The mathematical models of the irrigation water and energy consumption in each sub-district were established based on the relationship between the spatial patterns of crops and irrigation technologies in each sub-district. According to the present situation of the Jingdian Phase I Irrigation District in the arid region of northwest China, three modes of adjusting the crop planting structure and drip irrigation area were proposed. Based on the combination of these modes, three schemes of the spatial patterns of crops and irrigation technologies were generated. The annual energy consumption and irrigation water consumption of each sub-district in the ID of these three schemes were obtained through simulation. Compared with the present spatial patterns of crops and irrigation technologies in the Jingdian Phase I Irrigation District, Scheme 3 has the best water-saving and energy-saving effects, with an annual water saving and energy saving of 1753 × 104 m3 and 2898 × 104 kWh, and the water-saving rate and energy-saving rate were 12.34% and 15.74%, respectively. This paper also shows that the synchronous adjustment of crops and irrigation technologies among the sub-districts of ID can achieve significant water-saving and energy-saving effects.
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Arowolo, Matthew O., Adefemi A. Adekunle, and A. Ezekiel Fadiji. "PERT MATHEMATICAL MODEL DEVELOPMENT FOR THE SUPPLY OF DOMESTIC WELL-WATER TREATMENT PLANT." FUDMA JOURNAL OF SCIENCES 4, no. 2 (July 8, 2020): 552–66. http://dx.doi.org/10.33003/fjs-2020-0402-238.
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In Nigeria most cities are water stressed, none of the cities are having regular water supply. Quality water for human consumption is a primary duty of the government but they have failed. Also, current cost of boreholes installation has increased beyond their capacity due to Naira devaluation in the world market. Water resources management requires constant monitoring in terms of its qualitative-quantitative values. This study presents potential impact of the Project Evaluation and Review Techniques (PERT) mathematical model software development for the supply of domestic well-water treatment plant. After testing software against the values then, the 37days calculated Expected Time (ET) is unreliable because the risk involved in this project is (100 – 34.23) % = 65.77 %. However, a new completing date can be predicted by PERT mathematical model for supply of domestic well-water treatment plant by varying probability of completion to predict new date of completing the plant. Therefore, concerning this research the Initial probability was moved from 34.23% to 90%. By interpolation with 37 days; the new acceptable date was 97.28 days. The risk involved now (100 – 90) % reduced to 10%, a very good comfortable zone for the project. This information has really helped in two ways: for easy computation and decision making in water supply scheme project. This result is useful in industrialization, individuals, housing estate, small and medium scale industries where quality domestic well-water for crops production is a necessity. Hence, it is recommended that, the developed mathematical models performed
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Su, Lijun, Wanghai Tao, Yan Sun, Yuyang Shan, and Quanjiu Wang. "Mathematical Models of Leaf Area Index and Yield for Grapevines Grown in the Turpan Area, Xinjiang, China." Agronomy 12, no. 5 (April 20, 2022): 988. http://dx.doi.org/10.3390/agronomy12050988.
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The Leaf Area Index (LAI) strongly influences crop biomass production and yields. The variation characteristic of LAI and the development of crop growth models can provide a theoretical basis for predicting crops’ water consumption, fruit quality and yields. This paper analyzes the relationship between measurements of aboveground grape biomass and trends in LAI and dry biomass production in grapes grown in the Turpan area. The LAI changes in grapes were estimated using the modified logistic model, the modified Gaussian model, the log-normal model, the cubic polynomial model, and the Gaussian model. Universal models of LAI were established in which the applied irrigation quota was applied to calculate the maximum LAI. The relationship between the irrigation quota and biomass production, yields, and the harvest index was investigated. The developed models could accurately predict the LAI of grapevines grown in an extremely arid area. However, the Gaussian and cubic polynomial models produced less accurate results than the other models tested. The Michaelis–Menten model analyzed the relationship between biomass and LAI, providing a numerical method for predicting dynamic changes in grapevine LAI. Moreover, the crop biomass increased linearly with the irrigation quota for quotas between 6375 and 13,200 m3/hm. This made it possible to describe the grape yield and harvest index with a quadratic polynomial function, which increases during the early stages of the growing season and then decreases. The analyses of the relationship between yield and harvest index provide important theoretical insights that can be used to improve water use efficiency in grape cultivation and to identify optimal irrigation quotas.
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Olgarenko, Gennadii, and Tatiana Kapustina. "Dynamics of the Variability of Heat and Moisture Supply Indicators and Irrigation Norms in the Сonditions of the Astrakhan Region." E3S Web of Conferences 295 (2021): 03003. http://dx.doi.org/10.1051/e3sconf/202129503003.
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During the scientific researches, scientific and methodological recommendations have been developed for determining the irrigation norms of crops for years with different water balance deficit availability, including a method for assessing and zoning a territory according to the coefficient of natural heat and moisture supply (moisture index) Mi, calculation models for rationing irrigation taking into account territorial and temporal variability, irrigation requirements for main crops, differentiated by natural and climatic zones within the Astrakhan Region. Based on statistical research and mathematical analysis of the main climatic indicators - air temperature and precipitation, trends and the degree of change in these indicators were investigated and identified according to observation data, as well as rational ecologically balanced regimes of irrigation of crops in the Astrakhan Region were calculated. According to the research results, based on the developed methodology, net irrigation requirements (mm) were calculated for the main forage and vegetable crops in years of different humidity (supply), taking into account the climatic zones identified by the moisture index (Mi) in the Astrakhan Region.
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Morianou, Giasemi, Nektarios N. Kourgialas, and George P. Karatzas. "A Review of HYDRUS 2D/3D Applications for Simulations of Water Dynamics, Root Uptake and Solute Transport in Tree Crops under Drip Irrigation." Water 15, no. 4 (February 13, 2023): 741. http://dx.doi.org/10.3390/w15040741.
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Orchards with tree crops are of critical importance to the global economy and to the environment due to their ability to be productive for many years without the need for replanting. They are also better adapted to extreme climatic conditions compared to other crops. However, new challenges are emerging as climate change threatens both tree production and water supply. Drip irrigation (surface and subsurface) is an irrigation method that has the potential to save water and nutrients by placing water directly into the root zone and minimizing evaporation. Many irrigation designs and strategies have been tested to best perform drip irrigation for any given soil, crop and/or climate conditions. The researchers’ need to find the optimal combination of irrigation management and design in the most economical and effortless way led to the use of comprehensive numerical models such as HYDRUS 2D/3D. HYDRUS 2D/3D is a widely used mathematical model for studying vadose zone flow and transport processes. A review of HYDRUS 2D/3D applications for simulations of water dynamics, root uptake and solute transport under drip irrigation in the four most common categories of tree crops (citrus, olive, avocado and deciduous fruit/nuts) is presented in this study. The review promotes a better understanding of the effect of different drip irrigation designs and treatments, as well as the reliability provided by HYDRUS 2D/3D in the evaluation of the above. This manuscript also indicates gaps and future challenges regarding the use of the model in simulations of drip irrigation in tree crops.
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Jha, Madan K., Richard C. Peralta, and Sasmita Sahoo. "Simulation-Optimization for Conjunctive Water Resources Management and Optimal Crop Planning in Kushabhadra-Bhargavi River Delta of Eastern India." International Journal of Environmental Research and Public Health 17, no. 10 (May 18, 2020): 3521. http://dx.doi.org/10.3390/ijerph17103521.
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Water resources sustainability is a worldwide concern because of climate variability, growing population, and excessive groundwater exploitation in order to meet freshwater demand. Addressing these conflicting challenges sometimes can be aided by using both simulation and mathematical optimization tools. This study combines a groundwater-flow simulation model and two optimization models to develop optimal reconnaissance-level water management strategies. For a given set of hydrologic and management constraints, both of the optimization models are applied to part of the Mahanadi River basin groundwater system, which is an important source of water supply in Odisha State, India. The first optimization model employs a calibrated groundwater simulation model (MODFLOW-2005, the U.S. Geological Survey modular ground-water model) within the Simulation-Optimization MOdeling System (SOMOS) module number 1 (SOMO1) to estimate maximum permissible groundwater extraction, subject to suitable constraints that protect the aquifer from seawater intrusion. The second optimization model uses linear programming optimization to: (a) optimize conjunctive allocation of surface water and groundwater and (b) to determine a cropping pattern that maximizes net annual returns from crop yields, without causing seawater intrusion. Together, the optimization models consider the weather seasons, and the suitability and variability of existing cultivable land, crops, and the hydrogeologic system better than the models that do not employ the distributed maximum groundwater pumping rates that will not induce seawater intrusion. The optimization outcomes suggest that minimizing agricultural rice cultivation (especially during the non-monsoon season) and increasing crop diversification would improve farmers’ livelihoods and aid sustainable use of water resources.
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Tredenick, Eloise C., Troy W. Farrell, and W. Alison Forster. "Mathematical Modelling of Hydrophilic Ionic Fertiliser Diffusion in Plant Cuticles: Lipophilic Surfactant Effects." Plants 8, no. 7 (July 2, 2019): 202. http://dx.doi.org/10.3390/plants8070202.
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The global agricultural industry requires improved efficacy of sprays being applied to weeds and crops to increase financial returns and reduce environmental impact. Enhancing foliar penetration is one way to improve efficacy. Within the plant leaf, the cuticle is the most significant barrier to agrochemical diffusion. It has been noted that a comprehensive set of mechanisms for ionic active ingredient (AI) penetration through plant leaves with surfactants is not well defined, and oils that enhance penetration have been given little attention. The importance of a mechanistic mathematical model has been noted previously in the literature. Two mechanistic mathematical models have been previously developed by the authors, focusing on plant cuticle penetration of calcium chloride through tomato fruit cuticles. The models included ion binding and evaporation with hygroscopic water absorption, along with the ability to vary the AI concentration and type, relative humidity, and plant species. Here, we further develop these models to include lipophilic adjuvant effects, as well as the adsorption and desorption, of compounds on the cuticle surface with a novel Adaptive Competitive Langmuir model. These modifications to a penetration model provide a novel addition to the literature. We validate our theoretical model results against appropriate experimental data, discuss key sensitivities, and relate theoretical predictions to physical mechanisms. The results indicate the addition of the desorption mechanism may be one way to predict increased penetration at late times, and the sensitivity of model parameters compares well to those present in the literature.
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Amitrano, Chiara, Giovanni Battista Chirico, Stefania De Pascale, Youssef Rouphael, and Veronica De Micco. "Crop Management in Controlled Environment Agriculture (CEA) Systems Using Predictive Mathematical Models." Sensors 20, no. 11 (May 31, 2020): 3110. http://dx.doi.org/10.3390/s20113110.
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Proximal sensors in controlled environment agriculture (CEA) are used to monitor plant growth, yield, and water consumption with non-destructive technologies. Rapid and continuous monitoring of environmental and crop parameters may be used to develop mathematical models to predict crop response to microclimatic changes. Here, we applied the energy cascade model (MEC) on green- and red-leaf butterhead lettuce (Lactuca sativa L. var. capitata). We tooled up the model to describe the changing leaf functional efficiency during the growing period. We validated the model on an independent dataset with two different vapor pressure deficit (VPD) levels, corresponding to nominal (low VPD) and off-nominal (high VPD) conditions. Under low VPD, the modified model accurately predicted the transpiration rate (RMSE = 0.10 Lm−2), edible biomass (RMSE = 6.87 g m−2), net-photosynthesis (rBIAS = 34%), and stomatal conductance (rBIAS = 39%). Under high VPD, the model overestimated photosynthesis and stomatal conductance (rBIAS = 76–68%). This inconsistency is likely due to the empirical nature of the original model, which was designed for nominal conditions. Here, applications of the modified model are discussed, and possible improvements are suggested based on plant morpho-physiological changes occurring in sub-optimal scenarios.
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KACHIASHVILI, K. J., and D. I. MELIKDZHANIAN. "IDENTIFICATION OF RIVER WATER EXCESSIVE POLLUTION SOURCES." International Journal of Information Technology & Decision Making 05, no. 02 (June 2006): 397–417. http://dx.doi.org/10.1142/s0219622006001988.
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The program package for identification of river water excessive pollution sources located between two controlled cross-sections of the river is described in this paper. The software has been developed by the authors on the basis of mathematical models of pollutant transport in the rivers and statistical hypotheses checking methods. The identification algorithms were elaborated with the supposition that the pollution sources discharge different compositions of pollutants or (at the identical composition) different proportions of pollutants into the rivers.
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Brisson, N. "An analytical solution for the estimation of the critical available soil water fraction for a single layer water balance model under growing crops." Hydrology and Earth System Sciences 2, no. 2/3 (September 30, 1998): 221–31. http://dx.doi.org/10.5194/hess-2-221-1998.
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Abstract. In the framework of simplified water balance models devoted to irrigation scheduling or crop modelling, the relative transpiration rate (the ratio of actual to maximal transpiration) is assumed to decrease linearly when the soil dries out below a critical available water value. This value is usually expressed as a fraction, F, of the maximal available soil water content. The present work aims to use the basic laws governing water transfer through the plants at a daily time step to compute F dynamically as the crop grows. It can be regarded as an expansion of Slabbers' (1980) approach to crop growing conditions. Starting from the mathematical representation given by single-root models (Gardner, 1960), an analytical expression for F is derived, using simplified hypotheses. This expression accounts for plant attributes such as the mean root radius, the critical leaf water potential for stomatal closure and the root length density profile growing with the crop. Environmental factors such as soil type and atmospheric demand also influence F. The structural influence of soil comes from the required introduction of the bulk soil hydraulic conductivity in the single-root model. The shape of the root length density profile is assumed to be sigmoidal and a new profile is calculated at each value of the rooting depth. A sensitivity analysis of F to all those factors is presented. The first general result is that F decreases as the root system grows in depth. Differences in the shape of the root profile can be responsible for differential water stress sensitivity in the early stages of growth. Yet, low critical leaf water potential can compensate partially for a poor root profile. Conversely, F is relatively insensitive to the average root radius. F sensitivity to soil type seems somewhat artificial: given the bulk soil hydraulic conductivity formula, the soil sensitivity results from F being expressed as a fraction of the maximal available soil water content. The atmospheric demand together with the rooting depth appear as the most important factors. However, when assuming predictable climatic and crop evolution, compensation occurs between those two effects leading to a relative stability of F when the crop is fully developed. Though relying on well-known physical laws, the present approach remains in the framework of single layer models with the same limitations.
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Luo, Jing, Jian Bei Liu, Teng Feng Guo, and Cheng Yu Hu. "Validation Study of Road Surface Water Film Depth Prediction Model." Advanced Materials Research 1079-1080 (December 2014): 379–85. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.379.
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Surface water film thickness is one of the main factors, which affect the vehicle safety on slippery roads. Water film depth is influenced by rainfall intensity, grades, cross slopes, drainage length and pavement texture. This paper reviews the research status and makes some comparative analysis of several pavement water film depth prediction models. An experimental validation has verified and calibrated the existing water film depth prediction models results. The experimental validation of the variable in the slope water flow model has been implemented by means of a small scale physical road model in a rainfall simulator, which is constructed in a laboratory. The results of comparative analysis have shown that in the existing water film depth prediction models, the regression models predict values are more closely than mathematical-physical models. Because under different experimental conditions, the regression model calibration parameters are different. In the case of specific road characteristics for prediction of water film thickness, the model parameters can be calibrated to further improve predicting accuracy.
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Gálvez, Jorge, Miriam Parreño, Jordi Pla, Jaime Sanchez, María Gálvez-Llompart, Sergio Navarro, and Ramón García-Domenech. "Application of Molecular Topology to the Prediction of Water Quality Indices of Alkylphenol Pollutants." International Journal of Chemoinformatics and Chemical Engineering 1, no. 1 (January 2011): 1–11. http://dx.doi.org/10.4018/ijcce.2011010101.
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In this paper, topological-mathematical models based on multilineal regression analysis have been built as a model of the degradability of 26 alkylphenols through the Chemical Oxygen Demand (COD) and Biochemical Oxigen Demand (BOD5). Two models with three-variable were selected (r2= 0.8793 and q2=0.8075 for log(1/COD) and r2= 0.8928 and q2=0.8327 for log(1/BOD5). The models were validated by cross-validation, internal validation and randomization tests. The results, which stand in good accordance with the obtained results, confirm the robustness of the method.
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Rad, Samira Mosalaei, Ajay K. Ray, and Shahzad Barghi. "Water Pollution and Agriculture Pesticide." Clean Technologies 4, no. 4 (October 20, 2022): 1088–102. http://dx.doi.org/10.3390/cleantechnol4040066.
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The agricultural industry uses substantial amounts of water (the highest in the world) mostly for irrigation purposes. Rapid population growth and, consequently, growing demand for food have increased the use of pesticide to have higher yield for crops and other agricultural products. Wastewater generated as a result of excessive use of pesticides/herbicides in agricultural industry is becoming a global issue specifically in developing countries. Over 4,000,000 tons of pesticides are currently used in the world annually and high concentrations above their threshold limits have been detected in water bodies worldwide. The generated wastewater (contaminated with pesticides) has negative impacts on human health, the ecosystem, and the aquatic environment. Recently, biodegradable and biocompatible (including plant-based) pesticides have been introduced as green and safe products to reduce/eliminate the negative impacts of synthetic pesticides. Despite positive advantages of biopesticides, their use is limited due to cost and slow interaction with pests compared to chemical pesticides. Pesticides may also react with water and constituents of soil resulting in formation of intermediates having different physical and chemical properties. Diffusion, dispersion, and permeation are main mechanisms for transfer of pesticides in soil and water. Pesticides may degrade naturally in nature; however, the time requirement can be very long. Many mathematical models have been developed to simulate and estimate the final fate of pesticides in water resources. Development of new technologies and environmentally friendly pesticides to reduce water contamination is becoming increasingly important.
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Vinda, Ram Raj, Raja Ram Yadava, and Naveen Kumar. "Uniform Horizontal Groundwater Flow against Dispersion in a Shallow Aquifer: Two Analytical Models." Hydrology Research 23, no. 1 (February 1, 1992): 1–12. http://dx.doi.org/10.2166/nh.1992.0001.
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Analytical solutions converging rapidly at large and small values of times have been obtained for two mathematical models which describe the concentration distribution of a non reactive pollutant from a point source against the flow in a horizontal cross-section of a finite saturated shallow aquifer possessing uniform horizontal groundwater flow. Zero concentration or the conditions in which the flux across the extreme boundaries are proportional to the respective flow components are applied. The effects of flow and dispersion on concentration distribution are also discussed.
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Atikpo, E., and M. O. Ihimekpen. "Assessment of Lead (Pb) in Soil at Various Distances and Depths at Pb and Zn Mining Site in Ishiagu, Ebonyi State, Nigeria." Nigerian Journal of Environmental Sciences and Technology 4, no. 2 (October 2020): 463–72. http://dx.doi.org/10.36263/nijest.2020.02.0222.
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Pb in soil at various distance and depths was assessed at Pb and Zn mining site in Ishiagu Ebonyi State, Nigeria to determine the furthest distance travelled so far and the concentration at the distance. Pb ion in sampled soils at depth 0-10, 10-20, 20-30, 30-40 and 40-50 cm within pollution zones in 1 km x 1 km area of 100 m grid intervals were fitted with mathematical models for prediction using MATLAB. Pb ion change with distance was fitted into power model and linear polynomial models at distinct grid points. The models predictions showed decrease in Pb ion with distance. It revealed that the ion had travelled far into the soil with a furthest distance of 4760 cm but with no soil pollution signal because 64.54 mg/kg (concentration at 4760 cm) is less than 100 mg/kg specified as the maximum for soils. It showed a signal that the metal might threaten the ground water at some future date with an objectionable concentration above 0.01 mg/l specified for drinking water. Concentration at some intermediate distances is risk signal of food pollution through absorption of the metal by crops with root morphology and depth reaching these intermediate depths of objectionable concentration.
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Лєві, Л. І. "Використання нечіткої логіки для автоматизації функціонування зрошувальних систем." Вісник Полтавської державної аграрної академії, no. 2 (June 27, 2018): 153–57. http://dx.doi.org/10.31210/visnyk2018.02.25.
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Розглянуто підхід до автоматизації процесу керування зрошувальними системами із застосуванням нечіткої логіки. Потужність та інтуїтивна простота нечіткої логіки як методології вирішення проблем гарантує її успішне застосування в системах контролю та аналізу інформації. При цьому відбувається підключення людської інтуїції та досвіду оператора. Запропонований підхід дозволяє підвищити точність керування вологістю ґрунту, забезпечити отримання планових врожаїв сільськогосподарських культур, економити водні та енергетичні ресурси за рахунок їх раціонального використання.
The highest yield of agricultural crops is achieved with the optimal amount of moisture, nutrition, heat, air and light. In this case, the necessary water regime for agricultural crops is created by the appropriate irrigation regime, which establishes the norms, timing and number of irrigation, depending on the biological characteristics of crops, natural and economic conditions. In determining the flow of water to irrigation take into account water consumption or total evaporation, which depends on climatic conditions, the amount of thermal energy that enters the surface, soil moisture, species and yield of the crop.
Therefore, the issues of adaptation and self-studying of automated systems for controlling soil moisture in the conditions of the action of random weather factors, changes in the characteristics of the control object, improving the accuracy of control due to the operational consideration of the perturbations of the object, ensuring the receipt of planned yields of agricultural crops for the rational use of energy and water resources. In addition, modern water management systems for crops should not only provide sufficient management accuracy, but also forecast the need for plants in water for a certain period, minimize energy and water costs without loss of crop, be reliable and easy to operate, provide the operator with complete and timely information the value of all parameters and the state of the control system. A comprehensive solution to these problems is possible only through the development of modern technical means of automation, new mathematical models of moisture transfer in the unsaturated zone of soil and methods of managing moisture content of agricultural crops. Thus, the development of methods for automated management of moisture content of agricultural crops, taking into account perturbations, is an actual scientific and practical task.
To solve these problems, the approach to automating the management of irrigation systems with the use of fuzzy logic is considered. The power and intuitive simplicity of fuzzy logic as a solution to problems ensures its successful application in information monitoring and analysis systems. At the same time there is a connection of human intuition and operator experience. The offered approach allows to improve the accuracy of soil moisture management, to ensure that planned crops are harvested, and to save water and energy resources at the expense of their rational use.
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Letseku, Violet, and Bennie Grové. "Crop Water Productivity, Applied Water Productivity and Economic Decision Making." Water 14, no. 10 (May 17, 2022): 1598. http://dx.doi.org/10.3390/w14101598.
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Increasing productive water use in agriculture is seen as paramount to meet future food demand with limited water supplies. The main objective of this paper is to gain a better understanding of the interrelated linkages between crop water productivity (CWP) and applied water productivity (AWP) as affected by irrigation management decisions in order to assess the impact of economic decision making on CWP and AWP under area-limiting and water-limiting conditions. A daily soil water balance mathematical programming model that explicitly models the impact of technology choice and stochastic weather on water use efficiency was used to study the interactions. The assumption is made that a rational decision maker will allocate water to maximize expected profits. The results showed that CWP is, to a large extent, unresponsive to increasing irrigation water applications, especially when water applications are approaching maximum potential crop yields. The difference between optimal crop yields for the area-limiting and water-limiting scenarios is small, which shows that the portion of water production function that is relevant for economic decision making is small and falls within the unresponsive range of CWP changes. Profit maximizing decision makers will not try to maximize CWP or AWP since these objectives will result in profit losses.
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Olena, Solona, Melnyk Oleksandr, and Hryshchenko Volodymyr. "SIMULATION OF THE SYSTEM OF MINERAL NUTRITION OF PLANTS IN CLOSED SOIL." Vibrations in engineering and technology, no. 3(106) (December 23, 2022): 72–77. http://dx.doi.org/10.37128/2306-8744-2022-3-10.
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One of the important factors in the high productivity of growing vegetable crops by the method of small volume of this system of vegetable production is the accurate and timely supply of mineral nutrition to their root system. During hydroponic cultivation, all mineral substances of plants are obtained from their aqueous solutions. In closed soil, the water regime should be regulated taking into account the biological characteristics of the culture, the growth phase and the intensity of light. To successfully implement the plant nutrition process, it is necessary to formulate a mathematical model of the process and equivalent transfer functions. This will make it possible to choose a rational way of management and determine the parameters of management systems. The analysis of the latest researches in the field of automation of processes of nutrition of plants grown in closed soil shows that for each specific case, a scheme of automation of this process was proposed, which led to different results of the implementation of the process of nutrition. To generalize the principles of regulating the supply of nutrient solutions to plants in closed soil, it is necessary to develop real mathematical models of processes and equivalent transfer functions that will allow choosing a rational method of management. The specificity of the object of research determines the need to use the analytical method of obtaining dynamic models as the main one. The mathematical description of the dynamics of mass transfer during drip irrigation includes the value of the evaporative capacity of plants. This value significantly depends on the parameters of the microclimate in the building. To determine the influence of these parameters on the dynamics of liquid transpiration, a mathematical model was obtained in the form of differential equations of heat and material balances. The obtained mathematical models and the structural schemes built on their basis will serve as the basis for creating a system of mineral nutrition of plants in closed soil.
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Parizi, Ana R. C., Adroaldo D. Robaina, Ana C. dos S. Gomes, Marcia X. Peiter, and Fátima C. Soares. "Corn yield under various simulated irrigation depths." Engenharia Agrícola 36, no. 3 (June 2016): 503–14. http://dx.doi.org/10.1590/1809-4430-eng.agric.v36n3p503-514/2016.
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ABSTRACT Mathematical models are tools to estimate and understand system behaviors against diverse situations; they may help in decision-making through simplified representations of the reality, allowing simulating various scenarios and estimating impacts of different courses of action on production systems, assisting thus in activity planning. Thus, this paper proposed a simulation of corn crop yields according to different field experiment characteristics and weather conditions in which it was conducted, with the purpose of setting a simulation model already calibrated and tested for corn crop cycle in the region of Santiago – RS, Brazil. The increasing water levels had a positive effect on grain yield and corn dry matter. On the other hand, a level of 800 mm reduced corn yield, as well as water application efficiency decreased from 550 mm. The proposed model can be used as a tool for regional planning in corn crop implementation under irrigation and enables identifying irrigation strategies for high grain yields, being considered a tool for yield prediction in irrigated crops.
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Shatkovskyi, A. P., M. I. Romashchenko, O. V. Zhuravlov, S. V. Riabkov, Y. O. Cherevychnyi, and O. I. Hulenko. "OPTIMIZATION OF THE PARAMETERS OF DRIP IRRIGATION REGIMES FOR CROPS IN THE STEPPE OF UKRAINE." Міжвідомчий тематичний науковий збірник "Меліорація і водне господарство", no. 2 (December 21, 2022): 45–50. http://dx.doi.org/10.31073/mivg202202-338.
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The purpose of the research was to improve and substantiate the parameters of the drip irrigation regimes for crops in the Steppe of Ukraine. Field studies were carried out at the Kamyansko-Dniprovska experimental station (47046' N 34042' E), the Brylivska experimental station (46040' N 33012' E) and the Southern research station (46033' N 33059' E) from 2004 to 2021 on 11 crops. The research scheme assumed the implementation of a one-factor experiments’ series with different levels of soil humidification, the control was the variant without irrigation.
At the first stage, the mathematical dependencies "Soil moisture level (SML) –Number of vegetation irrigations" and "SML–Irrigation rate" were obtained for all crops. The establishment of correlations between the evapotranspiration of crops and their productivity is the result of the work. Based on this, were built the dependencies (statistical models) "Evapotranspiration–Productivity" and the most optimal options for using water were determined in terms of its costs for the formation of products for the drip irrigation of the Steppe of Ukraine. The given dependencies are reaction curves for a one-factor experiment, they consist of three areas: limiting, stationary and excessive. Correlation coefficients r=0,92-0,98 indicate a close relationship between these parameters. Established relationships "Evapotranspiration–Yield" from an agro biological point of view are not stable since there are potential opportunities for increasing yields with the same evapotranspiration. It has been established that the optimal moisture range for drip irrigation of most crops is a narrow range of soil moisture suction pressure of -9 to -15 kPa. This involves irrigation with small rates (50-75 m3/ha) while reducing the inter-irrigation periods. Under such conditions, the ratio of actual transpiration (Тс) to potential (То) approaches 1 (≈ 0,83-0,87), which characterizes the water supply of plants as close to optimal.
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Timmerman, Anthony, and Jan Feyen. "The WAVE model and its application; Simulation of the substances water and agrochemicals in the soil, crop and vadose environment." Corpoica Ciencia y Tecnología Agropecuaria 4, no. 1 (September 30, 2003): 36. http://dx.doi.org/10.21930/rcta.vol4_num1_art:11.
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<p>Expansion of human activities has major impact on the environment, generating changes that must be countered, such as climate change and dispersion of pollutants from industry and agriculture, through strategies that enable the conservation of soil and water reserves. The implementation of strategies with systems approach, covering mathematical simulation models, enables better decision making and a better understanding of the complexity and interaction of the different processes that affect the fate of nutrients, pollutants and chemicals in the environment - soil – on cultures and dynamic water. The WAVE system is presented in this article as a mathematical tool that describes the transport and transformations of matter and energy in the soil, crops and unsaturated soil, however it is not support the processes of water groundwater, drains and rivers.</p><p> </p><p><strong>Aplicaciones del modelo WAVE: simulación del crecimiento del cultivo y del </strong><strong>movimiento del agua y los agroquímicos en la zona no saturada del suelo.</strong></p><p>La expansión de las actividades humanas tiene gran impacto en el medio ambiente, generando cambios que deben ser contrarrestados, como el cambio climático y la dispersión de contaminantes de la industria y la agricultura; a través de estrategias que permitan la conservación del suelo y de las reservas de agua. La implementación de estrategias con enfoque de sistemas, que abarque modelos de simulación matemáticos, permite una mejor toma de decisiones y una mejor comprensión de la complejidad y la interacción de los diferentes procesos que afectan el destino de los nutrientes, contaminantes y sustancias químicas en el medio ambiente - suelo- en los cultivos y en las zonas de movimiento de aguas. El sistema WAVE se presenta en el presente artículo como una herramienta matemática que describe el transporte y transformaciones de la materia y la energía en el suelo, los cultivos y el suelo no saturado, sin embargo no es compatible con los procesos de las aguas subterráneas, drenajes y ríos.</p>
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Pourbakhshian, Somayyeh, and Majid Pouraminian. "Analytical Models for Optimal Design of a Trapezoidal Composite Channel Cross-Section." Civil and Environmental Engineering Reports 31, no. 1 (March 1, 2021): 118–38. http://dx.doi.org/10.2478/ceer-2021-0009.
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Abstract In this paper, several analytical models are presented for the optimal design of a trapezoidal composite channel cross-section. The objective function is the cost function per unit length of the channel, which includes the excavation and lining costs. To define the system, design variables including channel depth, channel width, side slopes, freeboard, and roughness coefficients were used. The constraints include Manning’s equation, flow velocity, Froude number, and water surface width. The Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm was used to solve the optimization problem. The results are presented in three parts; in the first part, the optimal values of the design variables and the objective function are presented in different discharges. In the second part, the relationship between cost and design variables in different discharges is presented in the form of conceptual and analytical models and mathematical functions. Finally, in the third part, the changes in the design variables and cost function are presented as a graph based on the discharge variations. Results indicate that the cost increases with increasing water depth, left side slope, equivalent roughness coefficient, and freeboard.
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Kang, Qi, Jiapeng Gu, Xueyu Qi, Ting Wu, Shengjie Wang, Sihang Chen, Wei Wang, and Jing Gong. "Hydrodynamic Modeling of Oil–Water Stratified Smooth Two-Phase Turbulent Flow in Horizontal Circular Pipes." Energies 14, no. 16 (August 23, 2021): 5201. http://dx.doi.org/10.3390/en14165201.
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In the petrochemical industry, multiphase flow, including oil–water two-phase stratified laminar flow, is more common and can be easily obtained through mathematical analysis. However, there is limited mathematical analytical model for the simulation of oil–water flow under turbulent flow. This paper introduces a two-dimensional (2D) numerical simulation method to investigate the pressure gradient, flow field, and oil–water interface height of a pipeline cross-section of horizontal tube in an oil–water stratified smooth flow. Three Reynolds average N–S equation models (k−ε, k−ω, SST k−ω) are involved to simulate oil–water stratified smooth flow according to the finite volume method. The pressure gradient and oil–water interface height can be computed according to the given volume flow rate using the iteration method. The predicted result of oil–water interface height and velocity profile by the model fit well with several published experimental data, except that there is a large error in pressure gradient. The SST k−ω turbulence model appears higher accuracy for simulating oil–water two-phase stratified flow in a horizontal pipe.
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Zhuravleva, L. A. "GREENHOUSES WITH NARROW-RACK HYDROPONICS TECHNOLOGY BASED ON DIGITAL CONTROL SYSTEMS." Scientific Life 15, no. 9 (September 30, 2020): 1195–203. http://dx.doi.org/10.35679/1991-9476-2020-15-7-1195-1203.
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Currently, many foreign greenhouse manufacturers use elements of digital technologies and hydroponics systems. Almost all manufacturers of systems and equipment in this class are foreign companies. Work on creating modern domestic digital controlled systems for growing agricultural crops is relevant and in demand in Russia. The Moscow Polytechnic University conducts studies and development research aimed at creating software and intelligent technologies for controlling and regulating the microclimate in greenhouses and hydroponic installations. Based on mathematical models of the microclimate systems for complete automation of plants growing process and automatic maintenance of optimal microclimate parameters, remotely using a phone or tablet PC, have been designed and implemented. The article presents a mathematical model of the greenhouse microclimate. One of the most promising directions is considered; it is a technology of multi-level shelving and narrow-shelving hydroponics. A functional diagram of the greenhouse microclimate control is given. This method allows to increase the used volume of greenhouses up to 25-30 pcs. plants per 1 sq. m of greenhouse area, the number of crop rotations up to 4-5 per year. Reducing water and nutrient solution consumption per unit of production by 2.0-2.5 times compared to drip irrigation greenhouses is provided. The amount of soil in comparison with low-volume substrate technology with drip irrigation is reduction by 4-6 times. The amount of nitrates in products is reduced by 8-10 times compared to the standard. The method of growing agricultural crops does not require much physical effort, unlike traditional crop production. Greenhouses with narrow-rack hydroponics technology based on digital control systems provide an increase in the efficiency of crop production; they are an environmentally friendly technology for growing seedlings, vegetables, berries, flowers and green crops. The technology can be used both in high-tech large-scale industries, agricultural holdings, city farms, and in family businesses on personal plots.
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Gomes, Francileni Pompeu, Osvaldo Resende, Elisabete Piancó de Sousa, Juliana Aparecida Célia, and Kênia Borges de Oliveira. "Application of Mathematical Models and Thermodynamic Properties in the Drying of Jambu Leaves." Agriculture 12, no. 8 (August 18, 2022): 1252. http://dx.doi.org/10.3390/agriculture12081252.
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Jambu is a vegetable originally from the northern region of Brazil, has bioactive properties, being little explored by other regions, due to its high peresivity. And one of the methods to increase the shelf life of plant products is the removal of water. The objective of this work was to evaluate the drying kinetics of jambu leaf mass. Two treatments were carried out: The mass of fresh jambu leaves and the mass of fresh jambu leaves with the addition of drying foam, both submitted in an oven with forced air circulation at temperatures (50, 60 and 70 °C and thickness of 1.0 cm). The proximate composition of the materials was performed before and after drying. Twelve mathematical models were tested on drying kinetics data and thermodynamic properties were calculated. The parameters of the proximate composition for the mass of leaves and foam after drying were: Moisture content of (2 to 7%), ash content of (13 to 17%), protein content of (22 to 30%), lipids of (0.6 to 4%) and total titratable acidity (0.20 to 0.28%) of tartaric acid. The models that best fit the experimental data to describe the drying kinetics of jambu masses were: Wang & Singh. The use of foam mat presented higher values of effective diffusion coefficient and activation energy and lower values of enthalpy and entropy, reducing the drying time.
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Sangale, Bhagwan, U. M. Khodke H. W. Awari, and Vishal Ingle. "Crop Growth Simulation Modelling - A Review." International Journal of Current Microbiology and Applied Sciences 11, no. 1 (January 10, 2022): 78–84. http://dx.doi.org/10.20546/ijcmas.2022.1101.010.
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Agriculture plays a key role in overall economic and social wellbeing of the specially developing countries. Now it is the right option to increase the quality and quantity of food production through the technological and managerial interventions like crop growth and yield prediction models. Agricultural models are mathematical equations that represent the reactions that occur within the plant and the interactions between the plant and its environment. The model simulates or imitates the behaviour of real crop by predicting the growth of its components, such as leaves, roots, stems and grains. Thus, a crop growth model not only predicts the final state of total biomass or harvestable yield, but also contains quantitative information about major processes involved in the growth and development of a plant. Crop Growth Simulation models are a formal way to present quantitative knowledge about how a crop grows in interaction with its environment. Using weather data and other data about the crop environment, these models can simulate crop development, growth, yield, water, and nutrient uptake. Crop models are mathematical algorithms that capture the quantitative information of agronomy and physiology experiments in a way that can explain and predict crop growth and development. They can simulate many seasons, locations, treatments, and scenarios in a few minutes. Crop models contribute to agriculture in many ways. They help explore the dynamics between the atmosphere, the crop, and the soil, assist in crop agronomy, pest management, breeding, and natural resource management, and assess the impact of climate change.
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Leite, Daniela D. de F., Alexandre J. de M. Queiroz, Rossana M. F. de Figueirêdo, Francislaine S. dos Santos, Semirames do N. Silva, and Dyego da C. Santos. "Mathematical modeling and thermodynamic properties in the drying of citron watermelon seeds." Revista Brasileira de Engenharia Agrícola e Ambiental 26, no. 1 (January 2022): 67–74. http://dx.doi.org/10.1590/1807-1929/agriambi.v26n1p67-74.
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ABSTRACT Citron watermelon is an agricultural product of excellent economic potential. Its seeds are widely used for oil extraction, serving as an energy source, showing nutritional characteristics that make them a suitable product to be studied. Thus, the objective was to characterize citron watermelon seeds regarding their physicochemical composition, in addition to determining drying kinetics, fitting mathematical models to the data, and determining the effective diffusivity coefficients and thermodynamic properties. The seeds were dried in a convective dryer, varying the drying temperature, with air velocity of 1.0 m s-1. With the increase in drying temperature, there were reductions in moisture content, water activity (aw), ash concentration, total titratable acidity, lipids and reducing sugar. Citron watermelon seeds are rich in lipids and ash, have low sugar concentration and low acidity; their drying kinetics was very well described by the Two Terms and Approximation of Diffusion models, followed by the models of Midilli and Page, which resulted in acceptable fits. Effective diffusivity accompanied the increase in drying temperature, and this behavior was well fitted by an Arrhenius-type equation. Enthalpy and entropy variations were reduced with drying temperature, with increments in Gibbs free energy.
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Weinbaum, S. "Interfacial Transport in Large and Small Blood Vessels." Applied Mechanics Reviews 43, no. 5S (May 1, 1990): S109—S118. http://dx.doi.org/10.1115/1.3120789.
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In this paper we shall review some recent mathematical models which have led to new conceptual views of the ultrastructural pathways by which water, solutes and large molecules cross the endothelial interface between tissue and blood. In particular, we shall show how a sequence of models for the endothelium and underlying tissue in large arteries have finally led to the experimental discovery of the large pore via which LDL and other large molecules enter the artery wall and how a new three-dimensional model for the interendothelial cleft in capillaries might reconcile the several long standing paradoxes relating to the measured filtration and solute permeability coefficients in the transcapillary exchange of water and hydrophilic solutes in the microcirculation.
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Jupsin, H., E. Praet, and J. L. Vasel. "Dynamic mathematical model of high rate algal ponds (HRAP)." Water Science and Technology 48, no. 2 (July 1, 2003): 197–204. http://dx.doi.org/10.2166/wst.2003.0120.
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This article presents a mathematical model to describe High-Rate Algal Ponds (HRAPs). The hydrodynamic behavior of the reactor is described as completely mixed tanks in series with recirculation. The hydrodynamic pattern is combined with a subset of River Water Quality Model 1 (RWQM1), including the main processes in liquid phase. Our aim is to develop models for WSPs and aerated lagoons, too, but we focused on HRAPs first for several reasons:• Sediments are usually less abundant in HRAP and can be neglected• Stratification is not observed and state variables are constant in a reactor cross section• Due to the system's geometry, the reactor is quite similar to a plugflow type reactor with recirculation, with a simple advection term. The model is based on mass balances and includes the following processes:Phytoplankton growth with NO3-, NO2- and death• Aerobic growth of heterotrophs with NO3-, NH4+ and respiration• Anoxic growth of heterotrophs with NO3-, NO2- and anoxic respiration• Growth of nitrifiers (two stages) and respiration. The differences with regard to RWQM1 are that we included a limiting term associated with inorganic carbon on the growth rate of algae and nitrifiers, gas transfers are taken into account by the familiar Adeney equation, and a subroutine calculates light intensity at the water surface. This article presents our first simulations.
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Ben-Asher, Jiftah, Jose Beltrao, Gulom Bekmirzaev, and Thomas Panagopoulos. "Crop Response to Combined Availability of Soil Water and Its Salinity Level: Theory, Experiments and Validation on Golf Courses." Agronomy 11, no. 10 (October 7, 2021): 2012. http://dx.doi.org/10.3390/agronomy11102012.
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The phenomenological expression showing crop yield to be directly dependent on water deficiency, under saline conditions, has encouraged a continued focus on salinity as a viable approach to increase crop yields. This work reassesses crop response to availability of saline soil water ASW in two stages (A) Develop a simple approach suggesting that permanent wilting point (WP) increases under high saline soil water tension and relative yield of Lettuce (Lactuca sativa L., var longifolia Lam., cv. Nevada) and maize (Zea mays L., cv. Jubilee sweet) decrease. (B) Using a deterministic numerical soil water model to validate the theory on Bermuda grass of golf courses. The experimental plots were established in the North Negev, Israel (Sweet corn) and the Algarve, Portugal (Lettuce and Bermuda grass covering the golf courses). Sprinkler irrigation and line source techniques were used for water application, creating a saline gradient under a precise irrigation water distribution. Two salinity empirical models were tested (Mass and Hoffman MH and van Genuchten–Gupta vGG). Their empirical models were modified and instead of soil electrical conductivity of irrigation water (ECe) we used wilting point (WP) and RASW to follow the changes in relative yield. The validation was conducted with theoretical soil plant atmosphere water (SPAW) to predict the results on golf courses. It is concluded that an alternative S-shaped response model provides better fit to our experimental data sets. Modified MH model (Yr = Y/Ymax = a ∗ (ASW–threshold’s constant) revealed that a single dimensionless curve could be used to express yield—salinity interference when represented by varying ASW. The vGG model: vGG can represent salt tolerance of most crops, by using varying wilting point of average root zone salinity, at which the yield has declined by 50%. The abscissa of both models was based on WP rather than the standard soil electrical conductivity (ECw). The correlation between the experimental data and WP or relative available soil water (RASW) was acceptable and, therefore, their usefulness for prediction of relative yield is acceptable as well. The objectives of this study were: 1. To develop a simple model describing the effect of salinity through soil water availability on crop production; 2. To replace the standard varying soil electrical conductivity ECe used by MH and vGG models by two soil parameters (at wilting point- θwp and at field capacity θfc) in order to describe the relationship between them and relative yield. 3. Validate the new model with respect to independent salinity on Golf courses and a mathematical deterministic model.
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Corrêa Filho, Luiz C., Ana P. Martinazzo, Carlos E. de S. Teodoro, and Ednilton T. de Andrade. "Post-harvest of parsley leaves (Petroselinum crispum): Mathematical modelling of drying and sorption processes." Revista Brasileira de Engenharia Agrícola e Ambiental 22, no. 2 (February 2018): 131–36. http://dx.doi.org/10.1590/1807-1929/agriambi.v22n2p131-136.
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ABSTRACT Parsley is a species of wide production and trade in Brazil due to its high consumption as a condiment, fresh or dried. In the development of equipment used for drying, it is important to simulate and obtain theoretical information about the behavior of water loss for each product. Given the increasing use and potential commercialization of condimental plants, the objective of this work was to determine the isosteric heat of parsley leaves and fit mathematical models to the experimental data obtained in drying and desorption processes. The modified GAB and Midilli models were the most appropriate to describe the desorption isotherms and drying curves, respectively, for the studied temperatures. The isosteric heat varied from 3394.6 to 2830.0 kJ kg-1 for the equilibrium moisture content in the range from 0.0154 to 3.7232 (d.b.).
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Oryokot, Joseph O. E., Stephen D. Murphy, A. Gordon Thomas, and Clarence J. Swanton. "Temperature- and moisture-dependent models of seed germination and shoot elongation in green and redroot pigweed (Amaranthus powellii, A. retroflexus)." Weed Science 45, no. 4 (August 1997): 488–96. http://dx.doi.org/10.1017/s0043174500088718.
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To predict weed emergence and help farmers make weed management decisions, we constructed a mathematical model of seed germination for green and redroot pigweed based on temperature and water potential (moisture) and expressing cumulative germination in terms of thermal time (degree days). Empirical observations indicated green pigweed germinated at a lower base temperature than redroot pigweed but the germination rate of redroot pigweed is much faster as mean temperature increases. Moisture limitation delayed seed germination until 23.8 C (green pigweed) or 27.9 (redroot pigweed); thereafter, germination was independent of water potential as mean temperatures approached germination optima. Our germination model, based on a cumulative normal distribution function, accounted for 80 to 95% of the variation in seed germination and accurately predicted that redroot pigweed would have a faster germination rate than green pigweed. However, the model predicted that redroot pigweed would germinate before green pigweed (in thermal time) and was generally less accurate during the early period of seed germination. The model also predicted that moisture limitation would increase, rather than delay, seed germination. These errors were related to the mathematical function chosen and analyses used, but an explicit interaction term for water potential and temperature is also needed to produce an accurate model. We also tested the effect of mean temperature on shoot elongation (emergence) and described the relationship by a linear model. Base temperatures for shoot elongation were higher than for seed germination. Shoot elongation began at 15.6 and 14.4 C for green and redroot pigweed, respectively; they increased linearly with temperature until the optimum of 27.9 C was reached. Elongation was dependent on completion of the rate-limiting step of radicle emergence and was sensitive to temperature but not moisture; hence, elongation was sensitive to a much smaller temperature range. Beyond mathematical changes, we are testing our model in the field and need to link it to ecophysiological, genetic, and spatially explicit population processes for it to be useful in decision support for weed management.
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Gudza, V., M. Urtenov, N. Chubyr, and I. Shkorkina. "Mathematical modelling of space charge breakdown in membrane systems taking into account the non-catalytic dissociation/ recombination reaction of water molecules." E3S Web of Conferences 224 (2020): 02009. http://dx.doi.org/10.1051/e3sconf/202022402009.
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In electromembrane systems, a theoretical study of salt ion transfer usually uses mathematical models of salt ion transfer in the depleted diffusion layer of ion-exchange membranes. In this paper, a new mathematical model of ion transport in the cross-section of the desalination channel formed by two ion-exchange membranes – anion-exchange (AEM) and cation-exchange (CEM), taking into account the non-catalytic dissociation/recombination reaction of water molecules. The model is a boundary value problem for a non-stationary system of Nernst-Planck and Poisson equations. A numerical analysis of the boundary value problem is performed and the main regularities of the 1:1 salt ion transfer process are established, in particular, the occurrence and development of space charge breakdown is shown. The interaction of the space charge and the noncatalytic dissociation/recombination reaction of water molecules are theoretically investigated.
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Glazar, Vladimir, Anica Trp, Kristian Lenic, and Fran Torbarina. "Numerical analysis of heat transfer in air-water heat exchanger with microchannel coil." E3S Web of Conferences 95 (2019): 02004. http://dx.doi.org/10.1051/e3sconf/20199502004.
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This paper presents numerical analysis of fluid flow and heat transfer in the heat exchanger with microchannel coil (MCHX). In accordance with previously published experimental results, 3D mathematical model has been defined and appropriate numerical simulation of heat transfer has been performed. Geometry and working parameters of cross-flow air-water heat exchanger with microchannel coil, installed in an open circuit wind tunnel and used in experimental investigations, have been applied in numerical analysis in order to validate the mathematical model. 3D model with air and water fluid flow and heat transfer domains has been used, as it gives more precise results compared to models that assume constant temperatures or constant heat fluxes on the pipe walls. Developed model comprised full length of air and water flows in the heat exchanger. Due to limitations of computational capacity, domain has been divided in multiple computational blocks in the water flow direction and then solved successively using CFD solver Fluent. Good agreement between experimentally measured and numerically calculated results has been obtained. The influence of various working parameters on heat transfer in air-water heat exchanger has been studied numerically, followed with discussion and final conclusions.
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Rinaldi, Michele, and Pasquale Garofalo. "Radiation-use efficiency of irrigated biomass sorghum in a Mediterranean environment." Crop and Pasture Science 62, no. 10 (2011): 830. http://dx.doi.org/10.1071/cp11091.
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Mathematical crop simulation models are useful tools in predicting the potential yield of field crops in a specific environment. The main driving parameter used to estimate biomass accumulation in most of these models is radiation-use efficiency (RUE). Biomass sorghum (Sorghum bicolor L. Moench) is a crop that can be used for energy production (thermal and bioethanol chains) and a knowledge of its RUE in different water supply conditions can help to improve model simulations and evaluate crop diffusion. A 3-year field experiment was carried out in Southern Italy where sorghum was submitted to four irrigated regimes based on actual crop evapotranspiration (ETc). In the first year ETc was measured with weighted lysimeters, while in the other 2 years it was estimated by means of estimated crop coefficient (Kc) and the reference evapotranspiration ET0. The RUE, calculated as the slope of the first-order equation between dry biomass and intercepted photosynthetically active radiation along a crop cycle, showed an average of 2.91 ± 0.54 g MJ–1, even if the RUE proved to be closely correlated with crop water consumption. The latter ranged between 891 and 454 mm and the RUE increased 4.2 mg MJ–1 per mm of water used. A high crop interception of solar radiation was observed in sorghum, reaching its maximum efficiency 40 days after sowing. To obtain high yielding yield biomass sorghum requires a large supply of water, as confirmed by the Kc calculated during the crop cycle, which resulted higher (especially in the development and middle stages) when compared with those reported in the FAO 56 Paper. The obtained RUE values also confirmed a high efficiency in biomass production of this crop, allowing for the introduction of biomass sorghum in the cropping systems of Mediterranean environments as an alternative crop for energy purposes, but with adequate irrigation water supply.
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Shehu, Musa D., A. A. Ahmed, and A. Abdulrahim. "Mathematical models and comparative analysis for rice irrigation crop water requirements: A case study of bida basin Niger State, Nigeria." New Trends in Mathematical Science 9 Special Issue, no. 1 (July 4, 2021): 17–20. http://dx.doi.org/10.20852/ntmsci.2021.422.
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Constantin, A. "Nonlinear water waves: introduction and overview." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, no. 2111 (December 11, 2017): 20170310. http://dx.doi.org/10.1098/rsta.2017.0310.
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For more than two centuries progress in the study of water waves proved to be interdependent with innovative and deep developments in theoretical and experimental directions of investigation. In recent years, considerable progress has been achieved towards the understanding of waves of large amplitude. Within this setting one cannot rely on linear theory as nonlinearity becomes an essential feature. Various analytic methods have been developed and adapted to come to terms with the challenges encountered in settings where approximations (such as those provided by linear or weakly nonlinear theory) are ineffective. Without relying on simpler models, progress becomes contingent upon the discovery of structural properties, the exploitation of which requires a combination of creative ideas and state-of-the-art technical tools. The successful quest for structure often reveals unexpected patterns and confers aesthetic value on some of these studies. The topics covered in this issue are both multi-disciplinary and interdisciplinary: there is a strong interplay between mathematical analysis, numerical computation and experimental/field data, interacting with each other via mutual stimulation and feedback. This theme issue reflects some of the new important developments that were discussed during the programme ‘Nonlinear water waves’ that took place at the Isaac Newton Institute for Mathematical Sciences (Cambridge, UK) from 31st July to 25th August 2017. A cross-section of the experts in the study of water waves who participated in the programme authored the collected papers. These papers illustrate the diversity, intensity and interconnectivity of the current research activity in this area. They offer new insight, present emerging theoretical methodologies and computational approaches, and describe sophisticated experimental results. This article is part of the theme issue ‘Nonlinear water waves’.
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Uzeika, Talita, Gustavo H. Merten, Jean P. G. Minella, and Michele Moro. "Use of the swat model for hydro-sedimentologic simulation in a small rural watershed." Revista Brasileira de Ciência do Solo 36, no. 2 (April 2012): 557–65. http://dx.doi.org/10.1590/s0100-06832012000200025.
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Mathematical models have great potential to support land use planning, with the goal of improving water and land quality. Before using a model, however, the model must demonstrate that it can correctly simulate the hydrological and erosive processes of a given site. The SWAT model (Soil and Water Assessment Tool) was developed in the United States to evaluate the effects of conservation agriculture on hydrological processes and water quality at the watershed scale. This model was initially proposed for use without calibration, which would eliminate the need for measured hydro-sedimentologic data. In this study, the SWAT model was evaluated in a small rural watershed (1.19 km²) located on the basalt slopes of the state of Rio Grande do Sul in southern Brazil, where farmers have been using cover crops associated with minimum tillage to control soil erosion. Values simulated by the model were compared with measured hydro-sedimentological data. Results for surface and total runoff on a daily basis were considered unsatisfactory (Nash-Sutcliffe efficiency coefficient - NSE < 0.5). However simulation results on monthly and annual scales were significantly better. With regard to the erosion process, the simulated sediment yields for all years of the study were unsatisfactory in comparison with the observed values on a daily and monthly basis (NSE values < -6), and overestimated the annual sediment yield by more than 100 %.
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Jablonská, Jana, Milada Kozubková, and Marian Bojko. "Flow of Oil and Water through the Nozzle and Cavitation." Processes 9, no. 11 (October 28, 2021): 1936. http://dx.doi.org/10.3390/pr9111936.
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Today, the correct understanding of the issue of oil and water cavitation is important due to the growing demands on working conditions in hydraulic systems (pressure and flow rate). This article deals with the measurement and subsequent mathematical modeling of cavitation in a convergent-divergent nozzle of circular cross-section. Cavitation depends on the physical properties of the flowing medium as a function of temperature. Usually, cavitation in water is defined by a two-phase flow of water and vapor, but the air contained in the water significantly affects cavitation. There is usually no vapor cavitation in the oil. Far more often, cavitation in oil is caused by the air it contains. For comparison, cavitation in water and oil was generated in experiments with an identical nozzle. The measurement was used to define boundary conditions in mathematical models and to verify simulations. The problem of cavitation was solved by three variants of multiphase flow, single-phase flow (water, oil), two-phase flow (water–vapor, oil–air) and three-phase flow (water–vapor–air, oil–vapor–air). A turbulent model with cavitation was used for all variants. The verification of simulations shows that for water cavitation it is necessary to use a three-phase model (water, vapor, air) and for oil cavitation a two-phase model (oil, air) is sufficient. The measurement results confirm the importance of the air phase in modeling cavitation in both water and oil.
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Bendoricchio, G., L. Calligaro, and G. M. Carrer. "Consequences of diffuse pollution on the water quality of rivers in the watershed of the lagoon of Venice (Italy)." Water Science and Technology 39, no. 3 (February 1, 1999): 113–20. http://dx.doi.org/10.2166/wst.1999.0148.
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The results of three water quality monitoring programs implemented in the watershed of the Lagoon of Venice are presented. The programs focus on nutrient discharge because of its critical effect on eutrophication of the Lagoon. One of these programs is concerned with the long term variation of water quality. It shows the positive effect induced by the interventions on point source pollution of urbanised areas. It results in the reduction of ammonia concentration and in the increase of dissolved oxygen downstream of major cities. It also shows the negative effect of increases in corn crops in upland areas on the nitrate nitrogen concentration at the sources of major rivers. The short term monitoring program shows the quick variation of nutrient concentrations during rain events in the rivers, and the close relation between the diffuse pollution sources and the deterioration of water quality. The total nutrient loads measured at the monitored river outlets confirm the loads predicted by mathematical models for the whole basin, and the importance of the diffuse pollution loads on the global loads discharged into the Lagoon. The progress in reduction of point source pollution increases the role of the diffuse sources, and demands for urgent and strong intervention on those to reach the final goal of stable mesotrophic conditions in the water body. Finally, data analysis of the monitoring programs also indicates an effective strategy for further monitoring of the river basin focused on the effectiveness of the pollution abatement program, and the real time control of water quality for the management of the Lagoon of Venice.
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Goodman, Barbara E. "TRANSPORT OF SMALL MOLECULES ACROSS CELL MEMBRANES: WATER CHANNELS AND UREA TRANSPORTERS." Advances in Physiology Education 26, no. 3 (September 2002): 146–57. http://dx.doi.org/10.1152/advan.00027.2002.
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How do small hydrophilic nonelectrolytes cross cell membranes? Which pathways are most important for small lipid insoluble molecules to cross cell membranes? These are questions that have been basic to membrane transport physiology for decades. More importantly, these are questions whose answers have changed significantly within the last 10 years. This review discusses the evidence that pathways other than the lipid bilayer itself exist for the transport across cell membranes of specific small hydrophilic nonelectrolytes. The description begins with briefly analyzing the relevance of well accepted basic mathematical models for transport for understanding the permeability of representative physiologically important molecules across actual cell membranes. Particular emphasis is placed on describing recently discovered proteins that facilitate the transport of some of the smallest physiologically important lipid-insoluble molecules, water, and urea. Evidence also exists for transport proteins that selectively enhance the transmembrane transport of other small lipid-insoluble molecules. Do nonselective pores for small molecules exist in cell membranes?