String graphs, that is, intersection graphs of curves in the plane, have been studied since the 1960s. We provide an expository presentation of several results, including very recent ones: some string graphs require an exponential number of crossings in every string representation; exponential number is always sufficient; string graphs have small separators; and the current best bound on the cr...

To determine the amount of air pollutants, produced by Iranian automakers, and compare it with old and retrofitted vehicles have become one of the important tools of urban management. The present research uses International Vehicle Emission (IVE) modeling software in order to verify SAIPA Co. fleet emissions, based on Euro 4 emission standard (SAIPA Co. recognized as a superior Iranian brand in...

In this article, modeling and optimization of power consumption of two–stage compressed air system has been investigated. To do so, the two – stage compressed air cycle with intercooler of FAJR Petroleum Company was considered. This cycle includes two centrifugal compressors, a shell, and a tube intercooler. For modeling of power consumption, actual compressors isentropic efficiencies and inter...

In this article, modeling and optimization of power consumption of two–stage compressed air system has been investigated. To do so, the two – stage compressed air cycle with intercooler of FAJR Petroleum Company was considered. This cycle includes two centrifugal compressors, a shell, and a tube intercooler. For modeling of power consumption, actual compressors isentropic efficiencies and inter...

The article recommends automatic control of active ventilation systems in agricultural product storage facilities. search for rational solutions ventilation, heating, and (ACS) that improve quality methods means is considered. As a result the analysis requirements air-cooling units operate no more than 25 days per annual cycle, it was proved refrigerating arrangements are based on principle ope...

To determine the amount of air pollutants, produced by Iranian automakers, and compare it with old and retrofitted vehicles have become one of the important tools of urban management. The present research uses International Vehicle Emission (IVE) modeling software in order to verify SAIPA Co. fleet emissions, based on Euro 4 emission standard (SAIPA Co. recognized as a superior Iranian brand in...

Based on the expert-novice analysis, we developed a distributed scaffolding curriculum for modeling air quality (DSCMAQ) to facilitate high school students’ modelbased reasoning in a technology-enhanced learning environment (APoME) which provided the Modeling Air Quality (MAQ) software associated with gradual complex learning tasks. Three studies had conducted to evaluate the effects of DSCMAQ ...

I present an efficient algorithm which lists the minimal separators of a planar graph in O(n) per separator.

For real numbers c, ε > 0, let Gc,ε denote the class of graphs G such that each subgraph H of G has a balanced separator of order at most c|V (H)|1−ε. A class G of graphs has strongly sublinear separators if G ⊆ Gc,ε for some c, ε > 0. We investigate properties of such graph classes, leading in particular to an approximate algorithm to determine membership in Gc,ε: there exist c > 0 such that f...

With the acceleration of urbanization and industrialization, urban air pollution has become a serious threat to the health of urban residents. In this study, to investigate health hazards caused by air pollution for urban residents, concentrations of main air pollutants and annual coal consumption amounts during the period from 2000 to 2013 were analyzed. Our results showed that economic losses...