Sharif Digital Repository

Rolling-element bearing (REB) failure is one of the general damages in rotating machinery. In this manner, the correct prediction of remaining useful life (RUL) of REB is a crucial challenge to move forward the unwavering quality of the machines. One of the main difficulties in implementing data-driven methods for RUL prediction is to choose proper features that represent real damage progression. In this article, by using the outcomes of frequency analysis through the Envelope method, the initiated/existed defects on the ball bearings are identified. Also, new features based on developing faults of ball bearings is recommended to estimate RUL. Early-stage faults in ball bearings usually... 

The hydrogen storage system is a suitable solution to solve the periodic nature of solar energy. In this study, a new four stage comprehensive framework based on Geographical information system (GIS) and fuzzy multicriteria decision-making (MCDM) is presented to identify suitable areas for developing solar power plant (SPP) in one of the dust-prone areas of Iran, Yazd province. High-resolution remote sensing data along with organization datasets are used to exclude inappropriate areas using GIS approach. Also, a new application of the SWARA method is introduced to prioritize solar sites by considering the uncertainty in the fuzzy environment. The considered criteria include economic... 

In the present work, hybrid energy systems based on various types of solar photovoltaic technologies is investigated for rural electricity supply. Five configurations are considered based on solar tracking systems, including biaxial, uniaxial and non-tracking. Solar photovoltaic size is optimized by HOMER software. Choosing the appropriate configuration is based on considering the simultaneous effect of six criteria, including renewable fraction (RF), solar capacity factor (CF), initial equipment cost, levelized cost of energy (LCOE), CO2 emission and energy security. In this study, for the first time the theory of Wins in League (WIL) is used to select the best system. This theory is a form... 

In this study, two conceptual models, the classic reservoir (CR) model and exchange reservoirs model embedded by dual porosity approach (DPR) are developed for simulation of karst aquifer functioning drained by multiple outlets. The performances of two developed models are demonstrated at a less developed karstic aquifer with three spring outlets located in Zagros Mountain in the south-west of Iran using 22-years of daily data. During the surface recharge, a production function based on water mass balance is implemented for computing the time series of surface recharge to the karst formations. The efficiency of both models has been assessed for simulation of daily spring discharge during the... 

In recent years, declining fossil fuel reserves and increasing environmental concerns led to higher utilization of renewable energy source (RES). One of the RES is Solar energy which is abundantly found in different areas of the globe, particularly in Iran. The aim of this research is to select a suitable site for constructing a solar power plant to generate electricity-hydrogen in southern Iran, Kerman province. For this purpose, a new hybrid Multi criteria decision making method is used. The Stepwise Weight Assessment Ratio Analysis (SWARA)method is used to weigh the criteria and the Measurement of alternatives and ranking according to Compromise solution (MARCOS)method is used to rank... 

Grid options are computational parameters that lead to proper numerical accuracy in air quality simulation and their selection is challenging. Therefore, the present study intends to provide a framework for selecting grid options. In this paper, the impact of five computational parameters such as time step, modeling duration, computational domain, and vertical and horizontal resolution on predicting a severe dust storm was investigated by WRF-Chem. A two-step algorithm based on the grid independence framework was proposed to select the appropriate grid options. In total, >22 different configurations were considered to investigate the effect of these options. Also, grid options were... 

Numerical weather prediction models are very important tools in predicting severe weather phenomena such as dust storms. However, the prediction accuracy in these models depends on the options considered in the modeling. In this study, a multi-objective framework is presented to determine the optimal options of the weather research forecasting with chemistry (WRF-Chem) model. For this purpose, a severe dust storm that occurred in the center of Iran is considered and the effect of 10 options including grid (computational domain size, modeling start time, horizontal, vertical and temporal resolution), physical (initial conditions, boundary layer and land surface schemes) and chemical options... 

The purpose of the present study is to evaluate and compare solar tracking systems connected to the grid. The solar systems considered were Fixed Tilt (FT), Vertical Continuous Adjustment (VCA), Horizontal adjustment (Monthly Adjustment (HMA), Continuous Adjustment (HCA)) and Two-Axis (TA) tracking system. Technical, economic and environmental assessment for an industrial consumer in southern Iran was performed by HOMER software. Unlike previous studies, multi-criteria approaches have been used to evaluate solar tracking systems. Due to the economic or technical superiority of each tracking system, solar tracking systems were prioritized using multi-criteria decision-making approaches. SWARA... 

In the present study, a novel approach based on multi-criteria analysis was proposed to prioritize PM mitigation strategies from economic, environmental and social aspects. Multi-criteria decision making (MCDM) methods are suitable tools for prioritizing strategies on various topics. However, it has been observed that adding/removing strategies has led to a change in preference which is called rank reversal. The present study was aimed with three objectives: (i) evaluating the rank reversal phenomenon in MCDM methods frequently used in environmental topics, (ii) introducing a novel approach based on wins in league (WIL) in order to reduce the rank reversal in MCDM methods and (iii) a new... 

Mineral dust has a great effect on the performance of solar power plants not only by absorbing and scattering solar radiation, but also due to soiling effects. The aim of the present study is to investigate the characteristics of dust in Iran using the Modern-Era-Retrospective-Analysis for Research and Applications in 2000–2019. In this assessment, radiation effects, dust emission and deposition rate in Iran were investigated from the aspects of seasonal changes and trends. Then, the effect of soiling in a 100 MW power plant in a twenty-year period in different regions of Iran was investigated. Finally, 15 cleaning scenarios were examined from three technical, economic, and environmental... 

There are many fundamental problems with the injection of nano-zero-valent iron (NZVI) particles to create permeable reactive barrier (PRB) treatment zone. Among them the loss of medium porosity or pore blocking over time can be considered which leads to reduction of permeability and bypass of the flow and contaminant plume up-gradient of the PRB. Present study provides a solution for such problems by confining the target zone for injection to the gate in a funnel-and-gate configuration. A laboratory-scale experimental setup is used in this work. In the designed PRB gate, no additional material from porous media exists. NZVI (d 50 = 52 ± 5 nm) particles are synthesized in water mixed with... 

In this work the application of a modified surface nano zero valent iron (NZVI) as bimetallic Fe/Cu particles to remove high concentration of NO3--N through packed sand column has been studied. Dispersed nano-Fe/Cu particles has been synthesized in water mixed ethanol solvent system (1:4v/v) and described by XRD pattern, TEM and SEM images and BET analyze. Batch experiments have been conducted to investigate the effect of percentage coating of Fe0 by Cu on the nitrate removal. Research on packed sand column (120cm length, 6.5cm inner diameter) has been done under conditions of Nano-Fe/Cu concentration (2, 5, and 8gl-1 of solution), high initial NO3--N concentration (100, 200, and 300mgl-1)... 

Low density turbidity currents have been investigated in a laboratory flume. An Acoustic Doppler Velocimeter (ADV) was used to measure the velocity. The dimensionless velocity profiles were compared with previous studies to check the accuracy of acoustic measuring techniques for turbidity currents. Successful use of the ADV to measure the current velocity has led to interest in the technique of using acoustic sensors to estimate concentrations. Acoustic backscattering analyses are used for estimating the sediment concentration in turbidity currents. With this approach, concentration measurements can be reasonably well represented by a similarity profile. Using this technique, an accurate... 

This study evaluated the efficiency of different Digital Elevation Models (DEMs), including ALOS-12.5 m, SRTM-30 m, SRTM-90 m, and ASTER-30 m v3 when being applied for the hydraulic simulation of flood inundation areas. HEC-RAS-2D model was employed to simulate inundation extent of a 400-year flood (Mar 17, 2019, with peak discharge ~ 547.92 m3/s) along 70 km reach of low-gradient Gorganrood River, northeastern Iran. Fit percentage indicator (FI) and BIAS percentage indicator (BI) were used to evaluate the results in comparison with the remotely sensed inundated area data. The results revealed that the accuracy and capability of the ALOS and SRTM-30 m were higher in simulation of flood... 

Dust storms are a common phenomenon in arid and semi-arid regions in West Asia, which has led to high levels of PM10 in local and remote area. The Yazd city in Iran with a high PM10 level located downstream of dust sources in the Middle East and Central Asia. In this study, based on meteorological and PM10 monitoring data, backward trajectory modeling of air parcels related to dust events at Yazd station was performed using the HYSPLIT model in 2012–2019. The trajectory cluster analysis was used to identify the main dust transport pathways and wind systems. Three methods of Cross-referencing Backward Trajectory (CBT), Potential Source Contribution Function (PSCF) and Concentration Weighted... 

In the current study, by considering both material and geometry nonlinearity, the nonlinear free vibration of functionally graded porous nanobeams based on the nonlocal strain gradient theory is investigated. Generally, the third-order elastic modulus, von Karman strain–displacement relationship, is assumed to incorporate the nonlinearity into the differential equation of the problem. In this paper, for the first time, the nonlinear vibrational response of the nanobeam does not merely depend on the geometric nonlinearity. Also, material nonlinearity of the bulk and surface layers is taken into consideration. Governing equations and the related boundary conditions are obtained by utilizing... 

The use of solar thermal energy is a suitable alternative to fossil fuels, but due to the lack of sufficient information on the implementation of thermal plants, solar industrial process heat (SIPH) was not implemented. The goal of this study is to assess SIPH in the textile industry of Iran. For this purpose, the suitable province for developing SIPH projects is determined from five dimensions using multicriteria decision-making (MCDM) methods. The step-wise weight assessment ratio analysis (SWARA) is used for weighting and the grey measurement alternatives and ranking according to compromise solution (MARCOS-G) is used for prioritizing the provinces. Then, at the optimum site, the... 

Dust storms are one of the natural phenomena that occur in different countries, especially in arid and semiarid regions. This study aimed to identify pathways and dust sources affecting the Yazd city. Therefore, in the present study, a multidisciplinary approach based on the air parcel trajectories, geographical information and observational data was used to identify the origin of dust storms. In this regard, based on the available data, the analysis has been done in the 7-year period of 2012–2019. The Hybrid Single-Particle Lagrangian Integrated Trajectory model was used to model the backward trajectory of the air parcel on days associated with dust storms. The Cross-Referencing Backward... 

Despite advancements in developing physics-based formulations to estimate the sheet-flow travel time (tSHF), the quantification of the relative impacts of influential parameters on tSHF has not previously been considered. In this study, a brief review of the physics-based formulations to estimate tSHF including kinematic wave (K-W) theory in combination with Manning's roughness (K-M) and with Darcy-Weisbach friction formula (K-D) over single and multiple planes is provided. Then, the relative significance of input parameters to the developed approaches is quantified by a density-based global sensitivity analysis (GSA). The performance of K-M considering zero-upstream and uniform flow depth... 

A simple conceptual rainfall–runoff model is proposed for the estimation of groundwater balance components in complex karst aquifers. In the proposed model the effects of memory length of different karst flow systems of base-flow, intermediate-flow, and quick-flow and also time variation of recharge area (RA) during a hydrological year were investigated. The model consists of three sub-models: soil moisture balance (SMB), epikarst balance (EPB), and groundwater balance (GWB) to simulate the daily spring discharge. The SMB and EPB sub-models utilize the mass conservation equation to compute the variation of moisture storages in the soil cover and epikarst, respectively. The GWB sub-model...