Mixture distributions - an alternative approach for estimating maximum magnitude earthquake occurrence     

Khalid J. Fahmi  Jamal N. Al  Abbasi 《Geophysical Journal International》1987,89(2):741-747

Summary. Gumbel's theory of extreme value has been employed in the statistical forecasting of maximum-magnitude earthquake occurrence. The basic working hypothesis behind this method assumes that observations follow either Gumbel type I or type III asymptotic distributions. In certain cases, however, it is found that neither type of distribution fits the data well enough to produce accurate parameter-estimates, particularly in the larger earthquake range. This article proposes an alternative approach based on finite-mixture distributions whereby a more realistic prediction of upper earthquake magnitudes (at given return periods) is expected using a combined analysis of both Gumbel types I and III extremal distributions.  相似文献   

Salinity tolerance and growth response of juvenile <Emphasis Type="Italic">Oreochromis mossambicus</Emphasis> at different salinity levels     

Khalid?JamilEmail author  Muhammad?Shoaib  Faisal?Ameer  Lin?Hong 《中国海洋大学学报(英文版)》2004,3(1):53-55

1　Introduction　Theuseofnaturalresources ,includingthosebeingofseeminglymarginalvalue ,isanimportanthumanactivitydesignedtoincreasefoodproductionandin come .Inagriculture ,soilsmaybetoosalinetosup portprofitablecrophusbandry ,yetsuchsoilmaybeusedalternat…  相似文献   

Efficient real-time reservoir management using adjoint-based optimal control and model updating   总被引：2，自引：0，他引：2  

Pallav Sarma  Louis J. Durlofsky  Khalid Aziz  Wen H. Chen 《Computational Geosciences》2006,10(1):3-36

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Petrography, chemistry and genesis of phosphorite concretions in the Eocene Umm Rijam Chert limestone Formation, Ma'an area, south Jordan   总被引：1，自引：0，他引：1  

Khalid Tarawneh  Khaled Moumani 《Journal of Asian Earth Sciences》2006,26(6):627-635

Phosphorite concretions are recorded for the first time within the lower part of the Umm Rijam Chert Limestone Formation (Eocene) in the Ma'an area, southern Jordan. The phosphorite concretions are typically hosted and encountered as individual layer in moderately lithified sediments of marl, chalk and chalky marl. The phosphorite concretions are present in thin layer (10–30 cm thick). They are localized on a hardground surface that formed as a result of cementation of soft ground by bioclastic materials. Light grey and brownish to black colors are encountered with isometric, ellipsoid, elongated, subangular to subrounded phosphorite concretions (up to 6 cm in length). Most of the phosphorite concretions preserve bioturbation structures; they also include fecal pellets of various sizes. The main biogenic components are fragments of macrofossils (bivalves) and microfossils (planktonic foraminifera) in different proportions. Petrographic examinations reveal that the phosphorite concretions are composed of cryptocrystalline apatite that characteristically appears in cross-polarized light almost as isotropic phosphate and minor anisotropic phosphate. Apatite and calcite are the main mineral constituents of the phosphorite concretions identified by XRD. The apatite is identified as francolite (carbonate-flour-apatite). Chemical analyses of the phosphorite concretions using X-ray florescence indicate that the P₂O₅ content ranges from 18.8 to 31.19%, whereas SEM–EDS analyses indicate that the phosphorus proportion is around 14% by volume. It could be argued that the phosphorite concretions were transported after being reworked, or were derived from carbonate and chalk pebbles that were later phosphatized and subjected to erosion, forming residual lag deposit along the hardground surface.  相似文献   

Seismic demand sensitivity of reinforced concrete shear‐wall building using FOSM method     

Tae‐Hyung Lee  Khalid M. Mosalam 《地震工程与结构动力学》2005,34(14):1719-1736

The uncertainty in the seismic demand of a structure (referred to as the engineering demand parameter, EDP) needs to be properly characterized in performance‐based earthquake engineering. Uncertainties in the ground motion and in structural properties are responsible for EDP uncertainty. In this study, sensitivity of EDPs to major uncertain variables is investigated using the first‐order second‐moment method for a case study building. This method is shown to be simple and efficient for estimating the sensitivity of seismic demand. The EDP uncertainty induced by each uncertain variable is used to determine which variables are most significant. Results show that the uncertainties in ground motion are more significant for global EDPs, namely peak roof acceleration and displacement, and maximum inter‐storey drift ratio, than those in structural properties. Uncertainty in the intensity measure (IM) of ground motion is the dominant variable for uncertainties in local EDPs such as the curvature demand at critical cross‐sections. Conditional sensitivity of global and local EDPs given IM is also estimated. It is observed that the combined effect of uncertainties in structural properties is more significant than uncertainty in ground motion profile at lower IM levels, while the opposite is true at higher IM levels. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Spectroscopic characterization of fulvic acids extracted from the rock exudate Shilajit     

Rajesh Khanna  Matthias Witt  Md. Khalid Anwer  Suraj P. Agarwal  Boris P. Koch   《Organic Geochemistry》2008,39(12):1719

The present work describes the extraction of fulvic acids (FA) from Shilajit and its spectroscopic and mass spectrometric characterization. The spectral features obtained from FT-IR and ¹HNMR were similar to those reported for humic substances from other sources. The molecular elemental composition analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in electrospray negative ion mode resulted in extraordinary high average O/C ratios (0.55) which might be caused by a significant contribution of carbohydrates in Shilajit. A very high average H/C ratio of 1.27 also points to dominant aliphatic or alicyclic structures and relatively low aromaticity. The average molecular formula of the nitrogen free elemental compositions measured by FT-ICR mass spectrometry is C_18.2H_23.0O_10.0.  相似文献   

A methodology to estimate equity of canal water and groundwater use at different spatial and temporal scales: a geo-informatics approach   总被引：1，自引：0，他引：1  

Usman Khalid Awan  Arif Anwar  Waqas Ahmad  Mohsin Hafeez 《Environmental Earth Sciences》2016,75(5):409

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Application of a partial least-squares regression model to retrieve chlorophyll-<Emphasis Type="Italic">a</Emphasis> concentrations in coastal waters using hyper-spectral data     

Kimberly Ryan  Khalid Ali 《Ocean Science Journal》2016,51(2):209-221

Coastal and inland waters represent a diverse set of resources that support natural habitats and provide valuable ecosystem services to the human population. Monitoring the quality of these waters is essential to maintaining the resources they provide, and long-term monitoring may offer a better understanding of the relationship between human development and the health of these resource producers. The implementation of conventional monitoring is typically time-intensive and limited in geographic scale. Alternatively, the use of airborne and spaceborne remote sensors provides a synoptic view of water quality with better spatial coverage to more accurately identify dynamic and unique parameters. Concentrations of optically active constituents (OACs) such as suspended sediments and the phytoplankton pigment chlorophylla (CHLa), act as proxies for water quality and can be detected by optical sensors. Traditional remote sensing techniques were developed using multispectral sensors, and employ band ratio algorithms that seek to predict the concentrations of OACs in relation to water quality. In complex coastal waters, overlapping spectral signatures of OACs often confound these algorithms and reduce their predictive capacity. The objective of this study was to develop a dataset to test the predictive capabilities of partial least-squares regression, a multivariate statistical method, for hyperspectral remote sensing and in situ CHLa concentrations. This paper presents the model performance for a dataset developed in Long Bay, a ~160 km arcuate bay that spans the border between North and South Carolina. The model uses multivariate-based statistical modeling to capitalize on the spectral advantage gained by hyperspectral sensors when observing such waters. Following this approach, a multivariate-based monitoring tool for the prediction of CHLa concentrations is presented with a partial least-squares regression (PLSR) method using hyperspectral and laboratory-analyzed field data. The PLSR model was used based on its ability to identify wavelengths that are more sensitive to CHLa relative to other OACs. The model was able to explain 80% of the observed CHLa variability in Long Bay with root mean square error (RMSE) = 2.03 µg/L. This enhanced mode of water quality monitoring has potential to deliver insights to point-sources and problem areas that may contribute to a decline in the water quality of valuable inland and coastal systems.  相似文献   

Effects of a low-radiotoxicity uranium salt (uranyl acetate) on biochemical and hematological parameters of the catfish, <Emphasis Type="Italic">Clarias gariepinus</Emphasis>     

Khalid A. Al-Ghanim  Zubair Ahmad  Hmoud F. Al-Kahem Al-Balawi  Fahad Al-Misned  Shahid Maboob  El-Amin M. Suliman 《中国海洋湖沼学报》2016,34(1):109-117

Specimens of Clarias gariepinus were treated with lethal (70, 75, 80, 85, 90, and 95 mg/L) and sub-lethal concentrations (8, 12 and 16 mg/L) of uranyl acetate, a low-radiotoxicity uranium salt. The LC 50 value was registered as 81.45 mg/L. The protein and glycogen concentrations in liver and muscles were decreased in the fish exposed to sub-lethal concentrations. The red blood cell (RBC) and white blood cell (WBC) counts, haemoglobin (Hb) concentration and haematocrit (Hct) values were decreased. Different blood indices like mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were negatively affected. Level of plasma glucose was elevated whereas protein was decreased. The level of calcium concentration (Ca) was declined in the blood of exposed fish whereas magnesium (Mg) remains unchanged. The activity level of glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) was elevated in exposed fish. These effects were more pronounced in the last period of exposure and in higher concentrations. Results of the present study indicate that uranyl acetate has adverse effects on Clarias gariepinus and causes changes in the biochemical and hematological parameters of the fish.  相似文献   

Network-constrained and category-based point pattern analysis for Suguo retail stores in Nanjing,China     

Yikang Rui  Zaigui Yang  Tianlu Qian  Shoaib Khalid  Nan Xia 《International journal of geographical information science》2016,30(2):186-199

The distribution of many geographical objects and events is affected by the road network; thus, network-constrained point pattern analysis methods are helpful to understand their space structures and distribution patterns. In this study, network kernel density estimation and network K-function are used to study retail service hot-spot areas and the spatial clustering patterns of a local retail giant (Suguo), respectively, in Nanjing city. Stores and roads are categorized to investigate the influence of weighting different categories of point events and network on the analysis. In addition, the competitive relation between Suguo and foreign-brand retail chains was revealed. The comprehensive analysis results derived from the combination of the first-order and second-order properties can be further used to examine the reasonability of the existing store distribution and optimize the locational choice of new stores.  相似文献