Sharif Digital Repository

In the present study, we analyzed the mechanical behavior of micro rotating disk based on the most general form of strain gradient elasticity. According to the fact that micro rotating disks have an important role in MEMS, it is necessary to present an exact analysis of their mechanical behavior. It is noticed experimentally that materials behave stronger in deformation as they get smaller. The classical continuum theory is not capable to predict such behavior; therefore, it is essential to use one of the non-classical continuum theories to analyze the material in micro scales, which can capture this phenomenon. In this work, the strain gradient theory is utilized to derive the governing... 

The water level of Lake Urmia has experienced a drop of 7.83 meters, from 1995 to 2017. According to previous studies, the uncontrolled development of agriculture, high consumption cultivation pattern, overuse of water resources for agricultural use and high water loss due to low irrigation efficiency, are the most important factors in the drying of Lake Urmia. Since agricultural sector is the largest water consumer (approximately 90%), the Lake Urmia Restoration Program has decided to study and implement the 40% reduction of water consumption in agricultural sector plans.Due to the inherent complexity of the Urmia Lake basin, accurate and realistic evaluation of the effectiveness of the... 

The spatiotemporal dynamic of salinity concentration (SC) in saline lakes is strongly dependent on the rate of water flow into the lake, water circulation, wind speed, evaporation rate, and the phenomenon of salt precipitation and dissolution. Although in-situ observations most reliably quantify water quality metrics, the spatiotemporal distribution of such data are typically limited and cannot be readily extrapolated for either long-term projections or extensive area. Alternatively, remotely sensed imagery has facilitated less expensive and a stronger ability to estimate water quality over a wide range of spatiotemporal resolutions. This study introduces an adaptive learning model that... 

Bathymetric maps are used for monitoring water bodies such as lakes, wetlands, and coastal areas, providing valuable information regarding changes in water storage volumes in these environments. For lakes prone to drying and salinity issues, where the lakebed elevation is constantly changing, the importance of these maps becomes even more pronounced as they play a crucial role in monitoring these lakes' conditions and assessing restoration efforts. Various methods exist for generating bathymetric maps, one of which is satellite remote sensing, which is more time- and cost-effective than traditional methods. One of the most common and accessible types of remote sensing data used for... 

The unavoidable consequences of increased demand for, and decreased supply of, various natural resources, especially water, have caused increased conflict over their allocation. Water allocations merely based on a water rights approach usually do not make efficient use of water for the whole river basin. Thus, there is a need for a comprehensive and stable allocation method that can satisfy all the involved interest groups. One of these methods is game theory that can be used to allocate water resources among riparian parties regarding principles of equity, efficiency and sustainability. In this study, a comprehensive linear programming model has been developed firstly to achieve the optimal... 

This study analyzes the impact of climate-related stressors and water resources development projects in the Tigris-Euphrates Basin on regional dust storm intensity and frequency. To this end, we utilize remote sensing data for Aerosol Optical Depth (AOD), wind speed, surface temperature, soil moisture, precipitation intensity and inter-arrival time, Standardized Precipitation Evapotranspiration Index (SPEI), and vegetation cover to explore long-term trends. To identify dust hotspots, we introduce a normalized intensity-frequency index (NIFI). The NIFI combines the arithmetic mean of AOD values and the frequency of daily AOD measurements exceeding a predefined threshold, to identify potential... 

GB and Miankale Wetland are one of the most valuable water areas in the country from an ecological perspective, providing a habitat for a wide range of aquatic species and birds as well as providing a platform for fishing and tourism for locals. Recently, this wildlife refuge has experienced a crisis of reduced water levels and degraded water quality. Past studies have examined how fluctuations in the Caspian Sea water level affect GB's water quantity and quality. Due to the critical situation of Gorgan Bay, other factors affecting its water balance and upstream basin need to be examined, such as ground water flow and consumption, precipitation, and evaporation, and how they all affect the... 

In response to the growing energy consumptions levels in buildings, many countries have introduced standards and codes aimed at reducing their national building energy consumption levels as well as managing the amount of pollutants. Title 19 of Iran’s National Building Regulation (NBR) was first introduced in 1991. It is projected that Title 19 can lead to a 30 to 50% reduction in the amount of buildings energy consumption. Nevertheless, evidence suggests that the introduction of Title 19 NBR has not led to substantial reduction in building energy consumption in Iran. Unlike Title 19 NBR, similar standards in other countries have proven to be very effective in reducing the building energy... 

Annular combustion chambers used in small turbine motors which incorporate centrifugal (rotary) injectors for injecting fuel, are known as Slinger combustion chambers. The Slinger injector works in such a way that fuel enters from an inner tube in motor shaft and exits with high pressure from the holes on the cylinder connected to the shaft. Because of the high centrifugal force, the fuel is sprayed with high quality after entering the combustion chamber. Type and angle of spray, fuel-air mixing type, combustion phenomena and flame stability makes this different than other annular combustion chambers. The process of combustion in the Slinger chamber of YJ402 motor is numerically simulated in... 

The purpose of this study is to introduce a new indicator to estimate the amount of irrigation water in excess of the need and also to determine the optimal irrigation pattern to reduce water loss in agriculture. According to the Food and Agriculture Organization of the United Nations, the major loss of fresh water takes place in agriculture, and the reduction of water resources is more significant in developing countries that do not have advanced agricultural equipment. One of the challenges in the studies related to reducing the amount of water used in agriculture is a lack of knowledge on the spatial distribution and temporal changes in water loss in a region. Although estimation of... 

This study aimed to investigate the efficiency of machine learning algorithms in capturing the dynamics of water particles' age distribution and in estimating the time series of median travel time (MTT) in river basins. The mechanism of solute transport in a catchment does not follow the hydrograph shape of the catchment and depends on the spatial and temporal distribution of solute resident time. The equations governing the age dynamics of water particles discharged from a catchment have been presented analytically in recent research. These equations showed that the transfer of solutes depends on various factors, including climatic conditions, basin topography, and basin vegetation. Also,... 

Water shortage, population growth, and high levels of urban water demand are among main challenges of water demand management for developing countries and cities, and also for megacities. Urban water management systems, as they are complex adaptive systems, complex interactions exist among elements affecting the system. In other words, action from a subpart can trigger other parts, and also the whole system to respond in reaction. In this study, socio-economic water consumption behavior of households is studies and simulated in an agent-based modeling platform. First, households are interviewed and, using the qualitative data extracted from interviews and also the behavioral science...