Unsupervised system to classify SO2 pollutant concentrations in Salamanca, Mexico

Salamanca is cataloged as one of the most polluted cities in Mexico. In order to observe the behavior and clarify the influence of wind parameters on the Sulphur Dioxide (SO2) concentrations a Self-Organizing Maps (SOM) Neural Network have been implemented at three monitoring locations for the period from January 1 to December 31, 2006. The maximum and minimum daily values of SO2 concentrations measured during the year of 2006 were correlated with the wind parameters of the same period. The main advantages of the SOM Neural Network is that it allows to integrate data from different sensors and provide readily interpretation results. Especially, it is powerful mapping and classification tool, which others information in an easier way and facilitates the task of establishing an order of priority between the distinguished groups of concentrations depending on their need for further research or remediation actions in subsequent management steps. For each monitoring location, SOM classifications were evaluated with respect to pollution levels established by Health Authorities. The classification system can help to establish a better air quality monitoring methodology that is essential for assessing the effectiveness of imposed pollution controls, strategies, and facilitate the pollutants reduction

An assessment on variation of sulphur dioxide and particulate matter in Erzurum (Turkey)

Sulphur dioxide and PM10 levels are investigated in Erzurum during the periods of 19902000 heating season to assess air pollution level. For that reason, emissions of sulphur dioxide and particulate matter were calculated by using consumption of fuels and Turkish emission factors. These emission values were evaluated together with air pollution levels, which were measured at six stations in Erzurum atmosphere during 1990-2000 winter periods. Results reveal that in 1990-1994 heating period, there is an increasing trend in the emissions and air pollution levels over Erzurum, and the air quality limits were not met. The daily 24 h limit (short-term limit) was exceeded 127 days in 1992-1993 winter period. The reason for this increase was found to be the switching to use of low-quality fossil fuels instead of cleaner ones. Results also indicated that there was a considerable decrease in emissions of air pollutants and air pollution levels after 1995. This can be explained by the consumption of more high-quality fossil fuels. The correlation coefficient Of SO2 with PM10 is obtained as r(2) = 0.85, which is a high value supporting the idea that both pollutants are emitted from the same source

ELEMENTAL COMPOSITION OF PM10 AND PM2.5 IN ERZURUM URBAN ATMOSPHERE, TURKEY

This study investigated the elemental concentrations of atmospheric particulate matter (PM10, PM2.5) and their relationships with meteorological factors in Erzurum urban centre, Turkey. The average elemental concentration PM10 values for Ca, Mg, Si, Al, Pb, Zn, Cu and Ni in Erzurum city atmosphere were 2112, 184, 2134, 746, 6, 44, 38 and 2 ng/m(3), respectively, and that of PM2.5 were 103, 30, 717, 86, 4, 6, 70 and 1 ng/m(3), respectively. Furthermore, during the sampling period, whilst on average 90% of some alkali metals (Si, Ca, Al, Mg) were observed in large size fraction, on average 55% of some elements (S, Zn, Pb, K) were measured in fine size fraction. For the purposes of investigating the sources of the elemental PM concentrations measured, the widely documented crustal enrichment factors method was used. K, Mg, Ca, Ti, Cr, Mn were observed to be from crustal sources in coarse fraction (PM10-2.5), but S, Cu, Zn, Pb were found to be anthropogenic. Concentrations of fine fraction (PM2.5) elements Mg, Ca, Al, Si, Ti were found to be entirely of crustal origin (as per coarse fraction), and both crustal and anthropogenic sources were important in concentrations of K, Cr, Mn and Ni, whereas S, Cu Zn and Pb levels were entirely of anthropogenic origin. Moreover, fine mode fraction of PM (PM2.5) showed considerable seasonal variations of elemental concentrations which was thought to originate from anthropogenic sources

Improvements in the static/dynamic strength of porcelain fused to metal dental crowns with surface protrusions produced by selective laser melting

Porcelain fused to metal dental crowns (PFMDC) are widely used in dental applications. Although the dental crowns are usually produced by the conventional casting method, additive manufacturing (AM) has recently gained an increased interest in dentistry due to its easy and rapid fabrication. Additive manufacturing is also a very advantageous method in patient-specific dental designs. In addition, through this method, it is possible to obtain products with geometries that cannot be obtained by classical methods. It is important to increase the lifetime of products in dental applications for lower costs and improved patient psychology. By increasing the strength of metal?ceramic interfaces, the total strength of dental crowns can be increased. For that reason, metal crowns with different numbers of protrusions and different locations on their surface edges were designed and produced by the selective laser melting method which is one of the additive manufacturing methods. These crowns were tested under both static and dynamic loading conditions and they mechanical performance was compared with the crowns produced by conventional methods. It was found that the crowns, which had different numbers of protrusions and different locations on the surface edge, showed more resistance under both static and dynamic load conditions. It was found that a metal substructure with dense protrusions that was produced at a thickness of 0.3 mm showed the highest strength under both static and dynamic loads