A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method

Journal of Seismology - The single-station microtremor horizontal-to-vertical spectral ratio (MHVSR) method was initially proposed to retrieve the site amplification function and its resonance...     

Thermal structure and Energy Budget for Alghadir reservoir, Iran

Knowing the rate of evaporation from surface water resources such as channels and reservoirs is essential for precise management of the water balance. Few detailed evaporation studies exist for small lakes or reservoirs in arid regions of the world. In this study, monthly evaporation was determined by Bowen Ratio Energy Budget technique (BREB) for Alghadir reservoir (Saveh, Iran) from 1995–2007 and compared with class-A pan. Daily data were obtained from IMO (Iran Meteorological Organization) weather station, located near the reservoir, for all of these years. Some variations have been observed on the estimated evaporation of the energy budget at different years, ranging from 151 cm for 1997 to 174 cm for 2006. There is no specific evaporation pattern for all the years, but evaporation rates were low in winter (January and February) and highest during the summer (July and August). However, the times and month of highest evaporation rates varied during the study period. Surveying of reservoir thermal structure showed that, inflow and outflow energy fluxes to this water volume have large variations. In addition, incoming solar shortwave radiation, incoming atmospheric longwave radiation, and longwave atmospheric radiation emitted from the water surface are largest energy fluxes for this small and deep reservoir. Results of this study could explain the importance and sensible contribution of the evaporation rates as a fundamental parameter in the hydrological cycle of reservoirs ecosystem in the arid regions of Iran.     

Foundation design considerations for a pile supported critical facility

A large reinforced concrete structure supported on piles extending to bedrock is evaluated using a seismic soil–structure interaction analysis. The physical structure, the supporting pile system, analysis model and analytical methodology used are described. Important considerations in the design of the foundation pile system using the seismic analysis loadings and deformations are discussed.     

Planar Gardner solitons and double layers in dusty electronegative plasmas with kappa distributed electrons

A theoretical investigation has been made on the Dust ion-acoustic (DIA) Gardner solitons (GSs) and double layers (DLs) in electronegative plasma consisting of inertial positive and negative ions, super-thermal (kappa distributed) electrons, and negatively charged static dust. The standard reductive perturbation method is employed to derive the Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and standard Gardner equations, which admits solitary waves (SWs) and DLs solutions. It have been found that GSs and DLs exist for α around its critical value α _c , where α _c is the value of α corresponding to the vanishing of the nonlinear coefficient of the K-dV equation. The parametric regimes for the existence of both the positive as well as negative SWs and negative DLs are obtained. The basic features of DIA SWs and DLs are analyzed and it has been found that the polarity, speed, height, thickness of such DIA SWs and DLs structures, are significantly modified due to the presence of two types of ions and spectral index (κ) of super-thermal electrons. It has also been found that the characteristics of DIA GSs and DLs, are different from that of the K-dV solitons and mK-dV solitons. The relevance of our results to different interstellar space plasma situations are discussed.     

Hot plasma waves in Veselago medium around Reissner-Nordström black hole

We investigate the general relativistic magnetohydronadynamic (GRMHD) equations for hot plasmas in a Veselago medium around the Reissner-Nordström (RN) black hole. Using the 3+1 formalisms of spacetime, we write the GRMHD equations and perturb them linearly. These are then Fourier analyzed for the magnetized and nonmagnetized plasmas in rotating and nonrotating backgrounds. We derive dispersion relations and analyze the wave properties by the graphs of wave vector, refractive index and change in refractive. The results confirm the presence of Veselago medium for rotating magnetized/nonmagnetized and nonrotating nonmagnetized plasmas.     

Effects of Operational Parameters on Decolorization of C. I. Acid Red 88 by UV/H2O2 Process: Evaluation of Electrical Energy Consumption

In the present study, effects of operational parameters on the electrical energy consumption for photooxidative process (UV/H₂O₂) for the decolorization of C. I. Acid Red 88 (AR88) have been investigated. In a series of experiments, 20 mg L^?1 of AR88 solution were irradiated in the presence of different concentrations of H₂O₂ (to find out optimum amount of H₂O₂) by UV light intensity of 30 W m^?2 for certain irradiation times. The decolorization of the dye followed pseudo first‐order kinetics, and hence, the figure‐of‐merit electrical energy per order (E_EO) is appropriate for estimating the electrical energy efficiency. The electrical energy consumption was determined during the variation of some parameters such as initial H₂O₂ concentration, initial dye concentration, UV light intensity, pH, and the gap size of solution. Results showed that electrical energy could be reduced by optimizing operational parameters.     

Vp‐Vs relationship and amplitude variation with offset modelling of glauconitic greensand‡

The relationship between V_p and V_s may be used to predict V_s where only V_p is known. V_p/V_s is also used to identify pore fluids from seismic data and amplitude variation with offset analysis. Theoretical, physical, as well as statistical empirical V_p‐V_s relationships have been proposed for reservoir characterization when shear‐wave data are not available. In published work, the focus is primarily on the V_p‐V_s relationship of quartzitic sandstone. In order to broaden the picture we present V_p‐V_s relationships of greensand composed of quartz and glauconite by using data from the Paleocene greensand Nini oil field in the North Sea. A V_p‐V_s relationship derived from modelling is compared with empirical V_p‐V_s regressions from laboratory data as well as from log data. The accuracy of V_s prediction is quantified in terms of root‐mean‐square error. We find that the V_p‐V_s relationship derived from modelling works well for greensand shear‐wave velocity prediction. We model the seismic response of glauconitic greensand by using laboratory data from the Nini field. Our studies here reveal that brine‐saturated glauconitic greensand can have a similar seismic response to that from oil‐saturated quartzitic sandstone and that oil‐saturated strongly cemented greensand can have a similar amplitude variation with offset response to that from brine‐saturated weakly cemented greensand.     

Radial basis function neural network for hydrologic inversion: an appraisal with classical and spatio-temporal geostatistical techniques in the context of site characterization

This paper investigates three techniques for spatial mapping and the consequential hydrologic inversion, using hydraulic conductivity (or transmissivity) and hydraulic head as the geophysical parameters of concern. The data for the study were obtained from the Waste Isolation and Pilot Plant (WIPP) site and surrounding area in the remote Chihuahuan Desert of southeastern New Mexico. The central technique was the Radial Basis Function algorithm for an Artificial Neural Network (RBF-ANN). An appraisal of its performance in light of classical and temporal geostatistical techniques is presented. Our classical geostatistical technique of concern was Ordinary Kriging (OK), while the method of Bayesian Maximum Entropy (BME) constituted an advanced, spatio-temporal mapping technique. A fusion technique for soft or inter-dependent data was developed in this study for use with the neural network. It was observed that the RBF-ANN is capable of hydrologic inversion for transmissivity estimation with features remaining essentially similar to that obtained from kriging. The BME technique, on the other hand, was found to reveal an ability to map localized lows and highs that were otherwise not as apparent in OK or RBF-ANN techniques.     

Pollutant dispersion characteristics in Dhaka city, Bangladesh

Air pollution is a major environmental concern in major cities around the world. The major causes of air pollution include rapid industrialization/urbanization and increased non environment-friendly energy production. This paper analyses the atmospheric pollutant such as carbon monoxide (CO) and particulate matter (PM) dispersion characteristics of Dhaka city. The yearly and diurnal variations of pollutant concentration are described by taking into consideration of both meteorological and emission source parameters highlighting washout effect due to rainfall and inversion phenomena. Concentration of PM (both PM2.5 and PM10) and CO in the ambient air are measured for a period of one year with Airmetric Minivol air samplers and Gas Chromatographic (GC) technique, respectively. The trend over the year shows an increase in the monthly average hourly PM and CO concentrations in winter months (November to March) when both PM10 and PM2.5 annual average concentrations (about 130 and 95 ??g m^?3, respectively) exhibit levels exceeding World Health Organization (WHO) guidelines as well as exceed more than twice the national standards of annual PM10 (50 ??g m^?3) and PM2.5 (15 ??g m^?3) concentrations. Such high pollutant concentrations may have significant health implications for residents of Dhaka city. It is also found that the PM concentration increases with the increase of wind speed during dry winter season and is also influenced by transboundary air pollution. The data and subsequent recommendations can be useful in formulating air quality management strategies for the Dhaka city.     

Geophysical interpretation of the Rashidpur structure Surma Basin,Bangladesh

The Rashidpur structure is located in the southern part of the Surma Basin, Bangladesh. This paper presents an integrated interpretation of seismic and other geophysical data considering the available geologic information in terms of hydrocarbon potential of this structure. The study area lies within a gravity high and a high magnetic intensity. Fifteen seismic sections of the study area have been analyzed to interpret the subsurface geology, structure and stratigraphy. Based on the analysis of seismic sections and correlation with well data, four prominent reflecting horizons have been identified. The litho-stratigraphy of the Rashidpur structure is prepared on the basis of well information. The lithological sequences encountered in the Rashidpur structure range in age from Miocene to Plio-Pliestocene. The gas producing sands of the structure are within Bokabil to Bhuban Formations of the Miocene age. The seismic study indicates that the Rashidpur structure is a narrow, NS elongated anticline affected by a major reverse fault on the eastern flank. It is an asymmetrical anticline with the axis swinging slightly to the east on the northern plunge and thus attaining a slight concavity to the east. There are various geophysical indications of hydrocarbons in this structure.