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A rational method for estimating soil suction variations within the so-called moisture active zone or vadose zone is required. Within the unsaturated zone, a soil suction envelope is defined by the maximum and minimum suctions at the ground surface (i.e., the suction amplitude), equilibrium suction, and depth to the equilibrium (or constant) suction. This paper presents a mechanistic-numerical model for predicting equilibrium suction that takes into account the effects of the diffusion coefficient and makes use of surface field suction measurements. The rational attenuation function in this study represents the rate of suction change within the unsaturated zone. The model can predict the equilibrium suction in response to changes in the subgrade moisture regime. The geographic information system (GIS) platform was used to create contour maps of the mechanistic-numerical equilibrium suction values for Oklahoma. In addition, the paper presents a reliable statistical-based equilibrium suction prediction model based on readily available parameters such as Thornthwaite Moisture Index (TMI), clay content, and relative humidity. [ABSTRACT FROM AUTHOR]

We developed a novel three-dimensional graphene oxide/allylamine/allyl glycidyl ether, and evaluated its adsorption performance for humic acid removal in an aqueous solution. The effective parameters were optimized by the Taguchi design method. Effective parameters on the removal of humic acid, including adsorbent dosage, solution pH, contact time, and temperature were evaluated using an L9 orthogonal array. The optimum parameters were adsorbent dosage of 0.02 g, pH of 6, contact time of 120 min, temperature of 25°C, and the removal efficiency of humic acid was 58%. Also, analysis of variance showed the most significant factors were adsorbent dosage and contact time with 33.58% and 51.62% contribution, respectively. The prepared nanoadsorbent was characterized by Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy with energy-dispersive X-ray analysis, and thermogravimetric analysis. The equilibrium data were evaluated by different isotherm models, where the data followed a Langmuir model with a maximum sorption capacity of 25.97 mg/g. Also, the kinetic adsorption data were well evaluated by the pseudo-secondorder model. The thermodynamic data shown that the sorption of humic acid onto the nanoadsorbent was an exothermic, favorable, and spontaneous process. The regeneration test indicated that the nanoadsorbent could be reused in the water treatment application. This study concluded that nanoadsorbent is a very hopeful nanoadsorbent for the remediation of water polluted by humic acid. [ABSTRACT FROM AUTHOR]

The use of Orbal reactors for wastewater treatment by activated sludge is deemed efficient by various literature sources. Furthermore, it is interesting to determine the potential methodologies to improve removal efficiencies. This study aims to investigate the performance of removal efficiency when a magnetic field is incorporated within the reactor. In this experiment, two magnetic fields of different intensities (1.3 and 2 mT) were used. To generate these magnetic fields, several neodymium magnets were applied to the reactor. The experiment and sampling lasted approximately over a 156-d period to observe the performance of the reactor, with and without the application of a magnetic field. Upon the reactor achieving a steady-state, results were taken. It should be highlighted that, before application, four different inflows were discharged into the reactor to attain the optimum retention time. To confirm the validity, results from relatable studies were compared with this study's findings. Upon application of the magnetic fields, removal efficiencies of total nitrogen, chemical oxygen demand, and biochemical oxygen demand for five days increased by 11%, 6%, and 7%, respectively. Nitrate concentration in effluent had decreased by 21%. Furthermore, the food to microorganism ratio had decreased within a 13%-15% range. Results indicated, also, that the application of different strength magnetic fields had minor effects on removal efficiency. [ABSTRACT FROM AUTHOR]

The formation of modifications or conception in the landscape could possibly, be a procedure relative to its natural and non-disturbance process; and it could be hastened by the occurrence of disturbance regimes. The objective of this research is to survey the changes in a landscape structure, over a period of 30 years, to attain information, as to the current conditions of land use, utilizing landscape metrics in the watershed area of the Latian Dam, so as to analyze the results and the voids present, towards obtaining a specified sustainable regional planning for the abovementioned watershed. Land use was identified and reviewed by means of four Landsat satellite images for 1987, 1998, 2007, and 2017; and in this watershed, it was classified into four classes, (a) build-up areas, (b) vegetated areas, (c) bare lands and (d) water bodies. Subsequently, by taking advantage of 7 metrics at the landscape level and 8 metrics at the class level, the landscape structure in this watershed was quantified by utilizing the Fragstats 4.2 Software. The survey results illustrated an increment in the number of patches (NP), decrementing the mean area of the patches (AREA-MN), and increasing the Interspersion & Juxtaposition Index (IJI) signifies amplified fragmentation at the landscape level in this watershed. Similarly, the NP has also incremented at the class level, and thus, the fragmentation of patches and fragmentation in the entire three classes of land use, namely, build-up areas, bare lands, and vegetated areas has occurred. The amount of patchiness for the build-up class, with due attention to the increment in the mean area of patches (AREA-MIN), which demonstrates the fact that, this class is inclined and has a tendency towards a coarse-grained structure and a metric decrement in the AREA-MIN in the vegetated areas, illustrates that this class is prone to the fine-grained structure. [ABSTRACT FROM AUTHOR]

Power generation, water consumption, and carbon emissions from power plants are intertwined. Most power generation technologies require water to cool steam turbines. The amount of water required for different types of power generation technologies varies in different power plants. The electricity sector is also one of the most important sources of greenhouse gas emissions worldwide and the main source of carbon emissions from fuel consumption in gas turbines and boilers. This study aimed to investigate the water, energy, and carbon nexus in the combined cycle power plants of Iran to identify the relationship between power generation, water consumption for electricity generation, and greenhouse gas emissions and ultimately improve the conditions, leading to the protection of the environment. In this study, first, the carbon and water footprints were assessed by LCA, and then, the water-energy nexus was modeled using the REWSS model (Regional Energy and Water Supply Scenarios). The Sankey diagram was then used to show the relationships and the current values for the power generation in the combined cycle power plants. Calculations of water, energy and carbon nexus have been done for 9 power plants and National scale. According to the results Damavand Power Plant had the highest power generation and the lowest WFL (0.068×10-9). The opposite was observed in Khoy Power Plant with the lowest power generation and the highest WFL (0.43×10-9). [ABSTRACT FROM AUTHOR]

The problem of bearing capacity of footings on rock is the subject of some researches in the recent years. However, the authors are not aware of any published paper about the effect of nearby footings on bearing capacity of rock foundations. This paper focuses on numerical analysis of the ultimate bearing capacity of two interfering strip footings resting on a rock mass, obeying the modified Hoek–Brown failure criterion. This criterion is applicable to intact rock or heavily jointed rock masses that can be considered homogeneous and isotropic. The rock mass was assumed to behave as a perfect plastic material and obeys an associated flow rule. The effects of Hoek–Brown parameters including geological strength index (GSI), material constant for intact rock ( m i ), and uniaxial compressive strength of intact rock ( σ ci ), on the bearing capacity of multiple footings were studied. For different clear spacing between the footings ( S ), the ratio of the failure load for an interfering new footing to that of a single isolated footing were determined. The results were compared with those available in the literature. [ABSTRACT FROM AUTHOR]