Sharif Digital Repository

Nowadays MapReduce and its open source implementation, Apache Hadoop, are the most widespread solutions for handling massive dataset on clusters of commodity hardware. At the expense of a somewhat reduced performance in comparison to HPC technologies, the MapReduce framework provides fault tolerance and automatic parallelization without any efforts by developers. Since in many cases Hadoop is adopted to support business critical activities, it is often important to predict with fair confidence the execution time of submitted jobs, for instance when SLAs are established with end-users. In this work, we propose and validate a hybrid approach exploiting both queuing networks and support vector... 

The variation of seawater level resulting from tidal fluctuations is usually neglected in regional groundwater flow studies. Although the tidal oscillation is damped near the shoreline, there is a quasi-steady-state rise in the mean water-table position, which may have an influence on regional groundwater flow. In this paper the effects of tidal fluctuations on groundwater hydraulics are investigated using a variably saturated numerical model that includes the effects of a realistic mild beach slope, seepage face and the unsaturated zone. In particular the impact of these factors on the velocity field in the aquifer is assessed. Simulations show that the tidal fluctuation has substantial... 

Lake Urmia is the second-largest hypersaline lake in the world. There has been a drastic water level drop of 7.2 m from 1995 to 2016. Beginning in October 2013, the Lake Urmia Restoration Plan (LURP) launched a 10-year program. An increase in water level and a relative improvement in Lake Urmia condition has been observed since 2017. It is an undecided and controversial issue whether the recent positive trend of Lake Urmia has been due to the LURP activities or it is a natural contribution of climate factors variations. To shed some light on this issue, we examine three other lakes, adjacent to the Lake Urmia basin, with similar rainfall variability to investigate their status during the... 

This study developed a groundwater sustainable management index including components of environmental, social, economic and institutional responsibility. Four significant indicators: integrated groundwater footprint, population density, percentage of groundwater used for agricultural and industrial sectors, and density of observation wells were adopted and executed for 443 of Iran’s aquifers. The results indicated that the groundwater sustainable management for 32% of Iran’s aquifers is poor–very poor, and this index is more sensitive to economic and social indicators. Finally, an inverse correlation was observed between the groundwater sustainable management index values and the coefficient... 

Assessing environmentally sustainable GW management (ESGM) needs a deep knowledge of the present and the projected status of GW (GW) quantity and quality. Translations of these data into policy relevant information are usually done through quantitative indices. Despite the availability of a dozen GW sustainability indicators, defining an integrated index based on internationally accepted scientific standards indicators is required. To fill this gap, an in-depth review on the developed indicators/index for evaluation of GW sustainable management (GWSM) from an environmental viewpoint at aquifer scales is provided in this study. Thirteen environmentally related quantitative indicators are... 

Commonly, capillary pressure-saturation-relative permeability (Pc-S-Kr) relationships are obtained by means of laboratory experiments carried out on soil samples that are up to 10-12 cm long. In obtaining these relationships, it is implicitly assumed that the soil sample is homogeneous. However, it is well known that even at such scales, some micro-heterogeneities may exist. These heterogeneous regions will have distinct multiphase flow properties and will affect saturation and distribution of wetting and non-wetting phases within the soil sample. This, in turn, may affect the measured two-phase flow relationships. In the present work, numerical simulations have been carried out to... 

The final outcome of promotion and recruitment processes in universities should be conventional and plausible by the members of the relevant scientific community, to affirm that the processes have been competitive and fair. The objective of this opinion letter is to make a plea for the importance of the post-auditing and quantitative assessment of the selection criteria. It is shown that for an example case the outcome of the post-audit does not look reasonable from an external point of view, at least regarding the research competency  

The original version of this article, unfortunately, contained error. In the article title, “tsunamis” should be “tsunami“. Given in this article is the correct title  

The final outcome of promotion and recruitment processes in universities should be conventional and plausible by the members of the relevant scientific community, to affirm that the processes have been competitive and fair. The objective of this opinion letter is to make a plea for the importance of the post-auditing and quantitative assessment of the selection criteria. It is shown that for an example case the outcome of the post-audit does not look reasonable from an external point of view, at least regarding the research competency. © 2015, Springer Science+Business Media Dordrecht  

The original version of this article was revised: Reference ‘Qiu, J. (2010). China drought highlights future climate threats. Nature, 463(7278), 142–143.’ has been replaced by ‘Qui, J. (2010). Publish or perish in China. Nature, 463(7278), 142–143.’. © Springer Science+Business Media B.V. 2017  

A comparative world map of scientific misconduct reveals that countries with the most rapid growth in scientific publications also have the highest retraction rate. To avoid polluting the scientific record further, these nations must urgently commit to enforcing research integrity among their academic communities. © 2017, Springer Science+Business Media B.V  

A comparative world map of scientific misconduct reveals that countries with the most rapid growth in scientific publications also have the highest retraction rate. To avoid polluting the scientific record further, these nations must urgently commit to enforcing research integrity among their academic communities. © 2017 Springer Science+Business Media B.V  

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...