Search

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]

In recent years, due to a decrement in water quality and scarcity, desalination systems have gained popularity for desalination purposes. Synchronously, with the development of this system, particularly, in concern with the littoral regions, seawater concentrate disposal consisting of various pollutants was taken into consideration. In this research, two desalination plants near each other were selected and four scenarios have been foreseen, for the discharge of seawater concentrate and the desalination intake, which are taken under study in the Ramin-Chabahar region, based on dual-dimensional hydrodynamic simulation, comprising of diffusion and release, by utilizing the MIKE 21 Software. Due to the proximity of the two desalination plants, to reduce the costs of piping in the sea, the location of discharge and intake were considered common. On the grounds pertaining to the modeling results, the discharge of seawater concentrates, at a distance of 300 m (5 m of depth) from the coast and the intake point, at a distance of 800 m, in elongation, has had the minimum environmental impact; as well as having no undesirable effect on the water quality of the intake, in addition to being cost-effective, from the economic viewpoint. To dilute seawater concentrate to a standardized level, it is appropriate to discharge through a diffuser with 10 nozzles, which are spaced out at 3.25 m from each other, being positioned linearly on one side, at an angle of 60 degrees. With the optimal selection of intake and discharge points of seawater concentrate in marine desalination plants, in addition to increasing the quality of treated water and reducing adverse environmental effects, construction and operation costs are also reduced. [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]

The COVID-19 disease spreads swiftly, and nearly three months after the first positive case was confirmed in China, Coronavirus started to spread all over the United States. Some states and counties reported high number of positive cases and deaths, while some reported lower COVID-19 related cases and death. In this paper, the factors that could affect the risk of COVID-19 infection and death were analyzed in county level. An innovative method by using K-means clustering and several classification models is utilized to determine the most critical factors. Results showed that longitudinal coordinate and population density, latitudinal coordinate, percentage of non-white people, percentage of uninsured people, percent of people below poverty, percentage of Elderly people, number of ICU beds per 10,000 people, percentage of smokers were the most significant attributes. [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]

This experimental-interventional study which was conducted on the laboratory scale, aimed to investigate the efficiency of atrazine removal from water solution using an advanced oxidation process with steel slag in the presence of sodium monopersulfate. All experiments were performed under constant UV (0.58 mw/cm2). The influencing variables including pH (2, 4, 6, 8, and 10), time (15, 30, 45, 60, 90, and 120 min), temperature (15, 20, and 25 °C), initial concentration of atrazine (5, 10, 15, 20, and 25 mg/l), and concentration of sodium monopersulfate (20, 40, 60, 80, and 100 mg/l). A high performance liquid chromatography (HPLC) device was used to determine the atrazine concentration in the water solution. The experiment design was carried out using response surface methodology (RSM) and central composite design (CCD), resulting in a total of 168 different experimental phases. The results showed that the optimal conditions for atrazine removal in the advanced oxidation process were pH = 4, time = 90 min, initial concentration of atrazine = 5 mg/l, slag amount = 25 g per liter, sodium monopersulfate concentration = 80 mg/l, and temperature = 20 °C. According to the results, on day 28 of the process operation period, 75.74% of COD was removed from wastewater. It can be concluded that the proposed treatment process can significantly remove atrazine from polluted water bodies like rivers, lakes and etc. • The best COD and atrazine removal percentages were 75 and 94 %, respectively. • Optimal condition was obtained for atrazine removal • Atrazine removal under optimal condition followed pseudo-first-order kinetics. • Direct correlation of atrazine removal with duration time, steel slag and persulfate • Inverse relationship of atrazine removal with pH [ABSTRACT FROM AUTHOR]