Sharif Digital Repository

Power transformer partial discharge signal measurement using Radio Frequency method has advantages over IEC 60270 'apparent charge' measurement method for online monitoring due to greater immunity against external interference. However, the lack of a well-defined calibration relationship between the two methods is main disadvantage of RF method. Simultaneous measurements, using these two methods, carried out on various transformer PD source models, in laboratory, to investigate main parameters that affect the relationship of results of these two methods. In this paper, factors that influence this relationship are classified into three groups: (i) type of PD sources, (ii) transformer windings... 

Incomplete self-similarity (ISS) concept is employed to develop the equations from existing experimental results of flow over an oblique rectangular sharp-crested weir for both free and submerged flow. The stage-discharge relationship is obtained by theoretical analysis, based on the application of the dimensional analysis and the ISS theory. For analysis, the relations were found by trial and error procedure using the SPSS mathematical computer program that estimates the relation among multi-variable functions. Thus, equations to estimate the flow characteristics for both free and submerged flow are proposed. The results show a better compatibility with the experimental data than the... 

In this paper the development of a quasi-three-dimensional numerical model that can be used for quantifying groundwater inputs and associated contaminant discharged from coastal aquifers into the coastal zone at a regional scale is presented. The present model is called MODSharp. In order to handle problems at a regional scale, the sharp interface approach which is used for conceptualising seawater intrusion, is applied to this model. This model can be used for the simulation of groundwater flow and contaminant transport in layered coastal aquifers at a regional scale. The method of characteristics is used to solve the advection-dispersion equation, which governs contaminant transport in... 

The Persian Gulf is one of the aquatic ecosystems which has recently faced with different pollutions. Cooling water discharges due to various industries such as power plants can cause important disorders on present ecosystem balance because of its high temperature. Obviously, due to thermal pollution, a great number of aquatic creatures face with a new situation that they can not tolerate. Thermal pollution leads to their migration, creates a potential for new coming species which in turn can thoroughly change the marine ecosystem feature. The other impacts of this phenomenon are: disorders in reproduction, nourishment and other biological habits. In this research, thermal pollution due to... 

Sea-level rise (SLR) influences groundwater hydraulics and in particular seawater intrusion (SWI) in many coastal aquifers. The quantification of the combined and relative impacts of influential factors on SWI has not previously been considered in coastal aquifers. In the present study, a systematic review of the available literature on this topic is first provided. Then, the potential remaining challenges are scrutinized. Open questions on the effects of more realistic complexities such as gradual SLR, parameter uncertainties, and the associated influences in decision-making models are issues requiring further investigation.We assess and quantify the seawater toe location under the impacts...