Finite element modeling assumptions impact on seismic response demands of MRF-buildings

Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame “RC-MRF” buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element (FE) models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.     

Coupling of phytoplankton and ciliate biomasses to environmental factors along the north coast of Sfax (Tunisia,Eastern Mediterranean Sea)

The phytoplankton and ciliate biomasses coupled with environmental factors were investigated in 15 transects in north coasts of Sfax (Tunisia, Eastern Mediterranean Sea) in July 2007. The phytoplankton biomass was dominated by Bacillariophyceae (89.66%), followed by Dinophyceae (10.07%), Coccolithophorideae (0.96%), Cyanobacteriae (0.21%), Chlorophyceae (0.03%) and Euglenophyceae (0.01%). Coscinodiscus sp. (93.26%) was the most abundant species of Bacillariophyceae group and associated with a high nutrient availability. Ciliate biomass was highly variable, with a large dominance of Spirotrichea, up to 96.2%. Biomass followed distinct patterns because of differences in the observed organism biovolumes. The spatial distribution of the ciliates biomass seems to be dependent on environmental factors and probably on their capacity to exploit a wide range of food resources including phytoplankton. The pollution generated by the phosphate-treating manufactory influenced the spatial phytoplankton and ciliate community’s distribution and their diversity along the north coast of Sfax.     

Potential Occurrence of MTBE and BTEX in Groundwater Resources of Amman–Zarqa Basin,Jordan

This study investigates potential occurrence, distribution, and sources of the newly added gasoline oxygenate, methyl‐tert‐butyl ether (MTBE) and the petroleum derivatives benzene, toluene, ethylbenzene, and xylenes called collectively, BTEX, in Jordan's heavily populated Amman–Zarqa Basin (AZB). It presents the first data on the levels of MTBE and BTEX in the aquifers of this basin. One hundred and seventy‐nine (179) groundwater wells were sampled near petrol service stations, oil refinery storage tanks, car wrecks, bus stations, and chemical industries at different locations in the basin. Headspace GC and purge and trap GC–MS were utilized to determine the target substances in the samples. Concentrations of BTEX varied between no‐detection (minimum) for all of them to 6.6 µg/L (maximum) for ethylbenzene. MTBE was found in few samples but none has exceeded the regulated levels; its concentrations ranged between no‐detection to 4.1 µg/L. However, though the contamination levels are very low they should be considered alarming.     

Geological applications potential of DEM,ETM+, and gravity data in arid and semi-arid regions with special reference to south Western Desert,Egypt

The study area comprises the southeastern part of the Western Desert of Egypt. The aims of the present study are to delineate the major surface and subsurface structures and to evaluate tectonic framework of the study area. Surface studies of the present work are based mainly on data from two different types of remote sensing systems: 15 cloud-free Landsat Enhanced Thematic Mapper Plus (ETM+) images and Shuttle Radar Topography Mission (SRTM) DEM data. The remote sensing data were used to recognize and extract geological lineaments by calculating and interpreting DEM derivatives, including shaded relief maps, slope maps, and traverse profiles. A Bouguer anomaly map (scale 1:500,000) was used to delineate a detailed picture of the subsurface structure in the study area. The analysis of surface data, including SRTM DEM and ETM+, was combined with subsurface data, including Bouguer anomaly map, and gave new insight into the tectonic and structure patterns of the study area.     

Deep Learning for Prediction of Water Quality Index Classification: Tropical Catchment Environmental Assessment

Natural Resources Research - River water quality modeling using crucial artificial intelligent (AI) models has become an essential tool for river assessment and management. The simplified approach...     

Simulating monthly streamflow using a hybrid feature selection approach integrated with an intelligence model

ABSTRACT

Streamflow prediction is useful for robust water resources engineering and management. This paper introduces a new methodology to generate more effective features for streamflow prediction based on the concept of “interaction effect”. The new features (input variables) are derived from the original features in a process called feature generation. It is necessary to select the most efficient input variables for the modelling process. Two feature selection methods, least absolute shrinkage and selection operator (LASSO) and particle swarm optimization-artificial neural networks (PSO-ANN), are used to select the effective features. Principal components analysis (PCA) is used to reduce the dimensions of selected features. Then, optimized support vector regression (SVR) is used for monthly streamflow prediction at the Karaj River in Iran. The proposed method provided accurate prediction results with a root mean square error (RMSE) of 2.79 m³/s and determination coefficient (R² ) of 0.92.     

Ambient noise surface wave tomography of the Makran subduction zone,south-east Iran:Implications for crustal and uppermost mantle structures

Seismic ambient noise of surface wave tomography was applied to estimate Rayleigh wave empirical Green's functions(EGFs) and then to study crust and uppermost mantle structure beneath the Makran region in south-east Iran.12 months of continuous data from January 2009 through January 2010,recorded at broadband seismic stations,were analyzed.Group velocities of the fundamental mode Rayleigh wave dispersion curves were obtained from the empirical Green's functions.Multiplefilter analysis was used to plot group velocity variations at periods from 10 to 50 s.Using group velocity dispersion curves,1-D vs velocity models were calculated between several station pairs.The final results demonstrate significant agreement to known geological and tectonic features.Our tomography maps display low-velocity anomaly with SW-NE trend,comparable with volcanic arc settings of the Makran region which may be attributable to the geometry of Arabian Plate subducting beneath the overriding the Lut block.The northward subducting Arabian Plate is determined by high-velocity anomaly along the Straits of Hormuz.At short periods(20 s),there is a sharp transition boundary between low- and high-velocity transition zone with the NW trending at the western edge of Makran which is attributable to the Minab fault system.     

Investigating the role of source mechanism,surface topography,and attenuation on the observed PGA pattern in May 28, 2004, Mw 6.2 Baladeh earthquake (Iran)

In this paper, we use seismic waveform simulation to investigate the influence of source mechanism complexity, surface topography, and quality factor on the observed peak ground motions in May 28, 2004, moment magnitude (Mw) 6.2 Baladeh earthquake. The observed peak ground acceleration (PGA) pattern in this event, which is the biggest earthquake to hit the Central Alborz Mountains of Iran in modern instrumental era, is irregular in some respects. First, the observed PGA contours are elongated toward north-west and, second, the maximum observed PGA value of 1049 cm/s² on the horizontal component of Hasan Keyf station 50 km away from the epicenter is quite high and irregular for an earthquake of this magnitude, at such long distance. In this study, we employ the spectral element method, implemented in SPECFEM3D software package to simulate the 3D wave propagation from several source models in the area. Our results suggest directivity effect is the main cause of the anomalous observations in this earthquake and could account for the elongation of PGA contours and also the anomalous maximum PGA value observed at Hasan Keyf strong motion station. We show that the surface topography has minor effect on the observed peak ground acceleration and the resulting PGA maps. Also by finding the bounds of seismic quality factor effect on the peak ground acceleration values, we show that this factor could not account for the elongation of iso-acceleration contours in the north-west direction.     

Impacts of an uncontrolled phosphogypsum dumpsite on summer distribution of phytoplankton, copepods and ciliates in relation to abiotic variables along the near-shore of the southwestern Mediterranean coast

In connection with the Taparura Project, studies of spatial distribution of the crustacean zooplankton community, nutrients, phytoplankton and ciliates were conducted in July 2007 at 45 stations spread over fifteen transects along the coast north of Sfax. The results showed that the N/P ratio was lower than the Redfield ratio, suggesting potential N limitation. Phytoplankton was characterised by the proliferation of several diatoms, while ciliates were largely dominated by spirotrichs. Copepods were the most abundant zooplankton present during the entire study period, comprising 61% of the total zooplankton community. Twelve copepod families were identified at every station, with a high percentage of Oithonidae (77% of copepods) dominated by Oithona nana. The abundance of this species was correlated with that of diatoms, Cocoolithophorideae and ciliated Colpodea, suggesting that O. nana may feed on a wide range of prey. Despite human pressure and industrial activities, the coastal waters north of Sfax showed a wide diversity of phytoplankton, ciliates and zooplankton.