Sharif Digital Repository

Hydraulic jump is a significant hydraulic phenomenon that occurs in stilling basins and causes energy dissipation of water flow. Due to the severe pressure fluctuations, cavitation, and fatigue damage to concrete materials, hydraulic jump can cause damage to the stilling basin and its related components. Therefore, studying pressure fluctuations is one of the essential topics in the safe design and operation of stilling basins. Due to the nonlinear relationship between the effective variables in the pressure fluctuation phenomenon, the use of computational intelligent models that can extract the relationship between the effective variables is necessary. In this study, laboratory data... 

The aim of this project is Industrial Solvents (White Spirit) producing in Tehran Refinery. For this manner “Wild Naphtha” from Gasoil Hydrotreater and Kerosene Hydrotreater Units was chosen as feed stock for solvents preparation. In addition, Pentane Recovery Column is selected for Simulation and Optimization based on Wild Naphtha. As a Result, Abadan White Spirit 402 and 410 has been produced and a side stream which is full of Aromatic is obtained. Simultaneously, Tray Hydraulics and Solvents production in different cases (Various Pressure and different Split Ratio of Feed Stock) are evaluated, so optimum Tower process conditions such as pressure, Temperature and Split Ratio of Feed Stock... 

In the oil industry, after drilling an oil well and laying pipes, it is time for the hydraulic fracturing process. In the process of hydraulic fracturing, a fracture must be created in the casing pipe of the well. The reason for this is that the oil from the existing reservoir enters the well so that it can be extracted. The end of the well must be blocked to cause a fracture in the well body. The reason is that after creating a fracture in the casing pipe, proppant particles are pumped together with water inside the well to keep it open. For the proppant particles to be placed inside the cracks, it is necessary to create pressure in the fracture area. To create pressure in the fracture area... 

Today, one of the most important concerns of oil and gas wells is to increase the efficiency of wells. To increase efficiency, well integrity must be monitored. One of the factors that destroy the integrity of the well is the creation of hydraulic fractures inside the oil and gas wells, which is one of the main factors that reduce the efficiency of the well. Hydraulic fractures cause water, gas and other materials to leak into the well or oil and gas to leak out of the fracture, which in both cases reduces the efficiency of the well. One of the most important technologies for identifying hydraulic fractures is the use of SNL tools from oil and gas wells. The oil and gas well SNL tool listens... 

The present study aims to evaluate the flood risk of Poldokhtar city probabilistically using Monte Carlo Simulations (MCS). Two-dimensional (2D) models, which are highly accurate, have been used widely for flood modeling. However, they are not suitable for applications such as MCSs that need to be repeated many times or real-time flood forecasting applications, which require that flood inundation maps quickly be produced. In the current study, we developed a data-driven surrogate model based on the Least Squares Support Vector Machine (LS-SVM), a supervised machine learning method, to predict flood depth in order to simulate similar results to 2D hydraulic modeling. HEC-RAS was used for 2D... 

Evaluation of the seismic-induced settlement of an unsaturated soil layer depends on several variables, among which the small strain shear modulus, Gmax, and soil’s state of stress have been demonstrated to be of particular significance. Recent interpretation of trends in Gmax revealed considerable effects of the degree of saturation and hydraulic hysteresis on the shear stiffness of soils in unsaturated states. Accordingly, the soil layer is expected to experience different settlement behaviors depending on the soil saturation and seasonal weathering conditions. In this study, a semi-empirical formulation was adapted to extend an existing Gmax model to infer hysteretic effects along... 

Results of an advanced suction controlled triaxial test device in an attempt to define the constitutive relationship between suction stress and matric suction (Suction Stress Characteristic Curve, SSCC) for unsaturated sand was presented. The suction stress is a macroscopic stress that incorporates the effects of capillary van der Waals forces cementation, and electrical double-layer repulsion into the definition of effective stress for unsaturated soils. Results of previous studies on silt and clay indicated that variations in the suction stress, during drying path had a non-linear increasing trend with matric suction with greater values upon wetting. However, due to different material... 

Discharging treated or raw waste water in to surface water may cause lots of serious problems, including growth of algae, as a result of the presence of nutrients in waste water.algae decrease the concentration of dissolve oxygen in water.phosphorus removal from waste water is of absolute necessity. according to the standards set by the environmental organization, discharge the untreated waster water in to the surface water is not allowed. on the other hand, given manager facilities of deprived area,effort is channeled to reach the desired result through designing the simplest treatment systems. anaerobic-aerobic systems have remarkably been used for many years in the treatment of urban and... 

Vegetation can be used as a research solution at the cutting edge of knowledge, cost-effective, aesthetic, pleasing, and environmentally friendly in natural hazards. Understanding the hydraulic properties, including the permeability of vegetated soils, is very important for various environmental applications. Different and sometimes conflicting behaviors have been observed in literature. There has been no general consensus in the literature regarding permeability due to the influence of several factors. In addition, there are many uncertainties about the effect of plant cultivation and root system effects on anisotropic soil permeability. It is essential to address this issue because of the... 

In operating nuclear reactor core, fluctuations (deviations from normal operating conditions) are usually produced and propagated. These fluctuations can be due to control rod vibrations, inlet coolant temperature fluctuations, inlet coolant velocity fluctuations and so on. The induced neutron noise can be detected by in-core neutron detectors. Noise source identifications (such as the type, location and propagating velocity) as well as the calculation of the dynamical parameters (such as moderator temperature coefficient in PWRs and Decay Ratio in BWRs) are of the main applications of the neutron noise analysis in power reactors.
Investigating the propagation noise in PWRs (specifically... 

The exploitation of oil and gas were changed dramatically with the advent of hydraulic fracturing. By using enhanced oil recovery methods in unconventional reservoirs, USA could raise the rate of production in comparison with the rate of consumption. Hydraulic fracturing is one of the enhanced oil recovery methods.The purpose of this research is the study of the effects of geomechanical parameters in the characteristics of the cracks induced by hydraulic fracturing in unconventional oil reservoirs. The minimum in-situ stress and tensile stress of rock can be overcome by injecting fluid and thus the rock will be cracked. Changes in geomechanical parameters such as modulus of elasticity,... 

Membrane bioreactors can replace the activated sludge process and the final clarification step in municipal wastewater treatment. The combination of bioreactor and crossflow microfiltration allows for a high chemical oxygen demand (COD) reduction of synthetic wastewater. In this study, experimental data from a laboratory scale membrane bioreactor are presented. In order to investigate the influence of various operating parameters such as hydraulic retention time (HRT), biomass concentration and organic loading rate on organic pollutant removal, the pilot scale submerged membrane bioreactor (SMBR) with a Polyvinylidene Fluoride (PVDF) hollow fiber membrane module was conducted using synthetic... 

In this thesis was investigated the effect of solid retention time (SRT), Hydraulic retention time (HRT), activated carbon and suspended carrier on styrene and ethylbenzene biological removal and also on membrane fouling. In addition to the typical analysis (COD, MLSS, MLVSS, and SVI), the flocculation ability, sludge particle size distribution (PSD), FTIR analysis, excitation-emission matrix (EEM) fluorescence spectroscopy, soluble microbial product (SMP), extracellular polymeric substance (EPS), microscopic observations, microbial activities, microorganism population, and filamentous bacteria are considered to determine sludge characteristics. This study was done in five sections: in the... 

In this study, the performance of Convectional activated sludge reactor (CAS), moving bed biofilm reactor (MBBR) and coupled MBBR-membrane bioreactor (MBR) for diesel removal was investigated.
Hydrocarbon quantification was conducted based on a photometery method at 250 nm after extraction with n-hexane.
Experiments with MBBR was conducted in a batch mode using the sludge obtained from a municipal wastewater treatment plant. In order to adapt microorganisms with diesel as carbon sourse, diesel concentration was gradualy increased from 100 to 3400 ppm where diesel removal efficiency decreased from 62/1 to 26/6 %. However, after addition of diesel degrading bacteria (previously... 

Results of previous studies on silt and clay indicated that variations in the small strain shear modulus, Gmax, during drying had a non-linear increasing trend with matric suction with greater values upon wetting. However, due to different material properties and inter-particle forces, different behaviour in Gmax is expected for sand. Although considerable research has been devoted in recent years to characterize the behaviour of Gmax of sand during drying, rather less attention has been paid to the effect of hydraulic hysteresis on Gmax and its variations during wetting. In the study presented herein, an effort was made to characterize the variation of Gmax for specimens of sand during... 

Early efforts in soil dynamics have shown that the analysis of soil behavior under cyclic or random loading conditions is highly dependent on some representative material properties, the dynamic shear modulus, the Poisson’s ratio, and the damping ratio. Of particular interest is the value of dynamic shear modulus for strains less than 10-6 defined as the maximum or small strain shear modulus Gmax. Improvements in experimental unsaturated soil mechanics have led to the definition of trends between Gmax with different parameters most notably unsaturated stress state, degree of saturation and void ratio. However, the tests in these studies were mostly conducted on specimens experiencing... 

Lake Urmia located in the NW of Iran, has lost 96 percent of its volume in 20 years and become a national crisis. During this shrinkage, the lake level has fallen by 8 m, and its concentration has increased up to 380 g/l. Regarding the vast area Lake Urmia basin is covered, the hydrological characteristics of the basin varies a lot, which affects the aquifers response to the seawater intrusion. In order to study the seawater intrusion in the lake’s aquifer, 18 cases with different hydraulic gradients, hydraulic conductivities and bathymetries were defined. All of these cases were run under three different scenarios in sequence. First, steady state scenario is preformed, then the lake level... 

The core behaviour of a nuclear reactor might be fluctuated (deviations from the normal operating conditions) in operating conditions due to various reasons. Control rod vibrations and the alterations of coolant temperature and velocity could be the main reasons for the fluctuations. These fluctuations lead to neutronic flux noise and subsequently power noise. The main objective of the current thesis was to study the thermal-hydraulic noise of the PWRs in two-phase with the emphasis on VVER-1000, which is similar to the Bushehr-1 nuclear reactor. By considering the possibility of existing two-phase flow (maximum allowable quality is about 14%) in hot channel of the PWRs, thermal-hydraulic... 

Groundwater is the most important freshwater resource in the coastal zones. There are some factors contaminate fresh groundwaters. Sea water intrusion (SWI) is one of the most important components of groundwater salinization. Also Submarine groundwater discharge (SGD) occurs when hydraulic gradient is from landside to seaside in coastal aquifers. There are many factors intensify SWI and SGD. In this research at the first part, coastline shape effect on SWI and SGD is investigated. For to this 4 different aquifers with different coastline shapes as stepped coastline, vertical coastline, steep slope coastline, and mild slope coastline are simulated with the same hydraulic parameters and... 

Two phase slug flow often happens in culvert and water tunnels conveying water from dams and weirs. Having complicated hydraulic properties, little is known about different hydraulic properties of this kind of flow, while most of the previous studies deal with other liquids than water and air, mostly dealing with chemical and mechanical engineering problems. In this paper, the results from experimental study of air/water slug flow due to changing in slope of the conduit from horizontal to 2, 3 and 4% are presented. The conduit has rectangular cross section with dimension cm of Plexiglas material and inclined part. Air is added to the system upstream of the conduit using an air discharge....