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121.
Fahim Abul Kashem Faruki Rahman Md. Zillur Hossain Md. Shakhawat Kamal A. S. M. Maksud 《Natural Hazards》2022,113(2):933-963
Natural Hazards - Soil liquefaction resistance evaluation is an important site investigation for seismically active areas. To minimize the loss of life and property, liquefaction hazard analysis is... 相似文献
122.
Renjith VishnuRadhan Divya David Thresyamma Kamal Sarma Grinson George Prabhakar Shirodkar Ponnumony Vethamony 《Natural Hazards》2015,78(1):309-331
During the last decade, the Andaman and Nicobar Islands (ANI) have witnessed a marginal population growth with associated variations and degradation in the water quality of the inhabited coastal region. Monthly water quality data collected from six coastal locations in ANI were used to evaluate the anthropogenic influence in an otherwise pristine island environment. Exceptionally low dissolved oxygen (0.7–2.0 mg/L) at the Phoenix Jetty (PJ) and mangrove site indicates hypoxic conditions. Among the nutrients, nitrate shows high values at PJ due to heavy nutrient loading from domestic sewage. The cluster analysis segregated PJ from the remaining sites, indicating deterioration in the water quality. On the other hand, water quality at Sippighat, a low-intensity aquaculture site, does not indicate any deterioration. Apart from the large modulations in the water quality of the study area by the Bay of Bengal waters, the effect of domestic waste discharges significantly affects the coastal waters of Andaman. Though the present water quality at most of the study sites appears acceptable, the increased volume of tourism and allied activities poses a potential threat to the island ecosystem. Besides the anthropogenic influences, the long-term trends in oceanographic factors were analyzed in order to decipher the expected natural effect on future water quality of the region. Based on the increasing sea surface temperature as well as the decreasing chlorophyll-a, eddy kinetic energy, and zonal kinetic energy, we propose that the combined effect of both natural and anthropogenic factors can ultimately distress the present ambient water quality of ANI. 相似文献
123.
124.
The earthquakes in Uttarkashi (October 20, 1991, M
w 6.8) and Chamoli (March 8, 1999, M
w 6.4) are among the recent well-documented earthquakes that occurred in the Garhwal region of India and that caused extensive
damage as well as loss of life. Using strong-motion data of these two earthquakes, we estimate their source, path, and site
parameters. The quality factor (Q
β
) as a function of frequency is derived as Q
β
(f) = 140f
1.018. The site amplification functions are evaluated using the horizontal-to-vertical spectral ratio technique. The ground motions
of the Uttarkashi and Chamoli earthquakes are simulated using the stochastic method of Boore (Bull Seismol Soc Am 73:1865–1894,
1983). The estimated source, path, and site parameters are used as input for the simulation. The simulated time histories are
generated for a few stations and compared with the observed data. The simulated response spectra at 5% damping are in fair
agreement with the observed response spectra for most of the stations over a wide range of frequencies. Residual trends closely
match the observed and simulated response spectra. The synthetic data are in rough agreement with the ground-motion attenuation
equation available for the Himalayas (Sharma, Bull Seismol Soc Am 98:1063–1069, 1998). 相似文献
125.
Megat Ahmad Kamal Megat Hanafiah Haslizaidi Zakaria Wan Saime Wan Ngah 《洁净——土壤、空气、水》2010,38(3):248-256
The adsorption of Ni(II) from aqueous solutions using base treated cogon grass or Imperata cylindrica (NHIC) was performed under batch and column modes. Batch experiments were conducted to determine the factors affecting adsorption such as pH, adsorbent dosage, initial nickel concentration, contact time and temperature. The fixed‐bed column experiment was performed to determine the practical applicability of NHIC and to obtain the breakthrough curve. Adsorption was fast as equilibrium was achieved within 60 min, and was best described by the pseudo second order model. According to the Langmuir model, a maximum adsorption capacity of 6.96 mg/g was observed at pH 5 and at a temperature of 313 K. Thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 were calculated, and indicated that adsorption was a spontaneous and endothermic process. The mechanistic pathway of Ni(II) uptake was examined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy. The Thomas and Yoon‐Nelson models were used to analyze the fixed‐bed column data. 相似文献
126.
Ibrahim M. Korrat Ali A. Gharib Kamal A. Abou Elenean Hesham M. Hussein Mohamed N. El Gabry 《Acta Geophysica》2008,56(2):344-356
Seismic discriminants based on the spectral seismogram and spectral magnitude techniques have been tested to discriminate
between three events; a nuclear explosion which took place in Lop Nor, China with m
b
6.1 and two earthquakes from the closest area with m
b
5.5 and 5.3, respectively. The spectral seismogram of the three events shows that the frequency content of the nuclear explosion
differs from that of the earthquakes where the P wave is richier in high frequency content in the nuclear explosion than the corresponding earthquakes. It is also observed
that the energy decays more rapidly for the nuclear explosion than for the earthquakes. Furthermore, the spectral magnitudes
reveal significant differences in the spectra between the nuclear explosion and the two earthquakes. The observed differences
appear to be quite enough to provide a reliable discriminant. The estimated stress drop from the magnitude spectra indicates
a higher stress drop of the nuclear explosion relative to the earthquakes of the same tectonic region. 相似文献
127.
128.
129.
Twana Kamal Haji Asaad Faramarzi Nicole Metje David Chapman Farough Rahimzadeh 《国际地质力学数值与分析法杂志》2020,44(3):418-431
The accurate modelling of gravity is of crucial importance for a variety of issues including, but not restricted to, the identification of buried objects. Gravity is an unbounded problem, which causes challenges when applying numerical models, i..e.., it results in computational difficulties when specifying the relevant boundary conditions. In order to address this, previous research has tended to generate artificial boundary conditions, e.g., truncating the simulated domain and adding many unrealistic zero-density layers, which introduces more unknown parameters and unnecessarily excessive computational time. In order to overcome such inaccuracies, this paper proposes an innovative development of the finite element modelling technique, which represents a step change in the field of gravity forward modelling. A comprehensive formulation of an infinite element to reproduce the far-field boundary effect using only one layer of infinite elements is presented. The developed model considerably reduces the computational time while obtaining high degrees of accuracy. The model is validated against the exact solution of the problem, and its results show an excellent performance. The proposed method can significantly improve the postprocessing and interpretation stages of data analysis relevant to micro-gravity sensors. The new method is applied to subsurface civil engineering although its applicability is manifold. 相似文献
130.
Solar System Research - An active region (AR) of the sun is an area of strong magnetic field. Sunspots are frequently formed in an AR. Solar activity exhibits in the form of solar flares and... 相似文献