Geo-textual indices play an important role in spatial keyword querying. The existing geo-textual indices have not been compared systematically under the same experimental framework. This makes it difficult to determine which indexing technique best supports specific functionality. We provide an all-around survey of 12 stateof-the-art geo-textual indices. We propose a benchmark that enables the ...

background: heavy metal pollution in the sediment of the yellow river draws wide attention in the recent years. the yellow river wetland nature reserve of zhengzhou is one of the major wetlands of the river and located at the beginning of the lower reach. in this article, we aimed to investigate the degree and the sources of the metal pollution in the reserve. methods: metals as cu, pb, cr, cd ...

Images with geo-tagging information are increasingly available on the Web. However, such images need to be annotated with additional textual information if they are to be retrievable, since users do not search by geo-coordinates. We propose to automatically generate such textual information by (1) generating toponyms from the geo-tagging information (2) retrieving Web documents using toponyms a...

Background: Soil serves as a major reservoir for contaminants as it can bind to various chemicals. The aim of this study was to evaluate the levels of some metals (Cd, Cu, Fe and V) in soil samples collected from different stations of Ahvaz Industrial Complex II to determine the natural and anthropogenic contribution of metal in the soil. Methods: This was an experimental study that carried ou...

We deal with the effect of missing data under a ”Missing at Random Model” on classification of variables with non hierarchical methods. The partitions are compared by the Rand’s index.

the concentrations of potentially toxic elements (as, sb, and hg) and some trace elements in 36 topsoil samples and 18 agricultural soil samples were measured at the aq-darreh river watershed, nw iran. based on the results of the chemical analysis and comparing them with different standards, it seems that the soils of the aq-darreh river watershed are polluted with as and sb. this pollution res...

Four heavy metals were measured in forty-nine topsoil samples collected fromagricultural areas in Siakh-Darengoun, Iran. The goals were to investigate soil spatialdistribution patterns of metals; their potential ecological risk; and sources. The Hakansonpotential ecological risk index and index of geo-accumulation (Igeo) were used forevaluating t...

background and purpose: in the environment, heavy metals in high concentration are toxic to most organisms. human activities have continuously increased the concentration of these metals in the environment such as soils. in the present study, soil samples collected from ahvaz iv industrial estate in khuzestan province. materials and methods: the soil samples were taken from 9 stations in 4 card...