A framework for automatic modeling of underground excavations and optimizing three‐dimensional boundary and finite element meshes derived from them—framework

Many problems in mining and civil engineering require using numerical stress analysis methods to repeatedly solve large models. Widespread acceptance of tunneling methods, such as New Austrian Tunneling Method, which depend heavily on numerical stress analysis tools and the fact that the effects of excavation at the face of a tunnel are distinctively three–dimensional (3D), necessitates the use of 3D numerical analysis for these problems. Stress analysis of a practical mining problem can be very lengthy, and the processing time can be measured in days or weeks at times. A framework is developed to facilitate efficient modeling of underground excavations and to create an optimal 3D mesh by reducing the number of surface and volume elements while keeping the result of stress analysis accurate enough at the region of interest, where a solution is sought. Fewer surface and volume elements mean fewer degrees of freedom in the numerical model, which directly translates into savings in computational time and resources. The mesh refinement algorithm is driven by a set of criteria that are functions of distance and visibility of points from the region of interest, and the framework can be easily extended by adding new types of criteria. This paper defines the framework, whereas a second companion paper will investigate its efficiency, accuracy and application to a number of practical mining problems. Copyright © 2012 John Wiley & Sons, Ltd.     

Groundwater depletion in northern India: Impacts of the sub-regional anthropogenic land-use,socio-politics and changing climate

Understanding the key drivers behind intensive use of groundwater resources and subsequent depletion in northern India is important for future food security of India. Although spatio-temporal changes of groundwater storage (GWS) and its depletion in northern India are mapped using the NASA's GRACE (Gravity Recovery and Climate Experiment) records, the sub-regional diverse socio-political and environmental factors contributing to the variability in groundwater withdrawals and renewals are not well documented. Here, we provide new evidence on changes in GWS at different spatial scales using both observations and satellite-based measurements applying both parametric and non-parametric statistical analyses. The substantial loss of GWS has occurred since the beginning of the 21st century, and the decline in GWS is associated with some record-breaking dry and hot climate events. We present how certain state-based policy decisions, such as supplying free electricity for irrigation, prompted farmers to extract groundwater unsustainably and thus led to widespread GWS deletion, which has been also accelerated by frequent dryness and rising temperatures. In the hotspot of Punjab, Haryana and Delhi of northern India, the extracted groundwater during 1985–2013 is equivalent to a metre-high layer if spread uniformly across its geographical domain. We find that the groundwater storage loss in northern India has increased rapidly from 17 km³ to 189 km³ between the pre-2002 and 2002–2013 periods. This loss in northern India is, therefore, an excellent example of rapid surface greening and sub-surface drying—a result of an interplay of socio-political and environmental factors. As groundwater continues to be treated as a common natural resource and no clear definition exists to guide policymaking, this study also illustrates how the administrative district level approach can solve the widespread problem of depletion.     

Nonparametric kernel estimation of annual precipitation over Iran

In this paper, annual precipitation data sets from five old rain gauge stations (Bushehr, Isfahan, Meshed, Tehran, and Jask) in Iran were fitted to nonparametric kernel function by using rectangular, triangular, and Gaussian or normal as kernel functions. The smoothing parameter was calculated by four methods including rule of thumb, Adamowski criterion, least squares cross-validation, and Sheater and Jones plug-in. The Adamowski criterion showed a better performance compared to other methods due to goodness of fit tests. The results of these proposed nonparametric methods will be then compared to the results of the parametric density functions including normal, two and three parameter log-normal, two parameter gamma, Pearson and log-Pearson type 3, Gumbel or extreme value type 1 and also Fourier series method which were applied by a previous study for the same stations. It was concluded that the annual precipitation data were fitted to nonparametric methods better than parametric methods.     

Surface deformation caused by April 6th 2009 earthquake in L’Aquila (Italy): A comparative analysis from ENVISAT ASAR,ALOS PALSAR and ASTER

Surface deformations in L’Aquila (centre of Italy) caused by the April 6th, 2009 earthquake were studied from space geodesy and remote sensing points of view using Synthetic Aperture Radar Interferometry (InSAR) and Sub-pixel Correlation Technique (SCT). InSAR was used to measure ground surface deformation in the satellite line of sight (LOS) direction and the deformation was determined using two separate interferometric pairs of ENVISAT ASAR and ALOS PALSAR data sets. Furthermore, SCT was employed to investigate the horizontal displacements in the area. Two separate pairs of ENVISAT ASAR and ASTER optical image data sets were employed, and horizontal displacements in Range/Azimuth and in west–east/south–north directions were investigated, respectively.     

Investigation of meteorological extreme events over coastal regions of Iran

In this study, in order to detect probable trends and effects of climatic extreme events of precipitation and temperature as well as maximum relative humidity, dew point temperature, sunshine hours, and wind speed, 12 stations on the northern and southern coastlines of Iran were investigated from 1977 to 2007. For this purpose, 27 indices of precipitation and temperature, which are specified by the Expert Team of the World Meteorological Organization and Climate Variability and Predictability, were calculated by using RClimDex software. The Mann?CKendall method was also used to detect possible trends in the data time series. The results indicate that temperature indices are absolutely consistent with warming. Warm nights, hot days, and hot day and night frequencies increased, while cold spell and cool day and night frequencies declined. The minimum temperature experienced a considerable rise both in its maximum and minimum values. The minimum temperature had a higher increase than the maximum temperature. Therefore, diurnal temperature ranges have experienced dramatic declines. In the northern coastal sites, hot day frequency and hottest day temperature showed higher magnitudes than those of the southern sites as a result of the significant increase in the maximum sunshine hours in northern stations. This enhancement led to a considerable increase in the maximum wind speed. Consequently, relative humidity declined in the northern sites. Precipitation indices indicate few significant trends over the studied period. Temporal precipitation distribution was different from station to station. Three precipitation patterns were detected at individual stations, although an overall regional rainfall pattern was not detectable. On the whole, the results of this study emphasize that the water resources in the studied area are going to become problematic.     

Comparison of crustal thickness from two gravimetric-isostatic models and CRUST2.0

The Mohorovičić discontinuity is the boundary between the Earth’s crust and mantle. Several isostatic hypotheses exist for estimating the crustal thickness and density variation of the Earth’s crust from gravity anomalies.     

Selective Separation/Preconcentration of Silver Ion in Water by Multiwalled Carbon Nanotubes Microcolumn as a Sorbent

The present paper proposes the application of multiwalled carbon nanotubes (MWCNTs) as a solid adsorbent for selective separation/preconcentration of silver(I) in water samples prior to flame atomic absorption spectrometry. The procedure is based on the solid phase extraction of Ag(I)–2‐mercaptobenzothiazole chelate on MWCNTs. The elution step is carried out with 5 mL of 2 mol L^?1 HNO₃ in acetone solution at a flow rate of 1.0 mL min^?1. The influences of the various analytical parameters including pH of the solution, eluent type, sample volume, flow rates of eluent, matrix ions were investigated for optimization of the presented procedure. Tests of addition/recovery for analyte ion in real samples were performed with satisfactory results. Preconcentration factor and limit of detection for Ag(I) were 160 and 0.21 µg L^?1, respectively. The synthesized MWCNT exhibited excellent stability in eluent solution and its adsorption capacity was 5.4 mg of silver per gram of sorbent. The proposed method was successfully applied to trace silver determination in a variety of environmental water samples.