Probabilistic approach to short- and intermediate-term earthquake forecasting: II test application to southern California     

M. Niazi  C. P. Mortgat  K. N. Truong 《Pure and Applied Geophysics》1985,123(5):653-665

A method is proposed for assessing the modifying effects of precursory observations on long-term probabilities of strong earthquakes (M6). Estimated short-and intermediate-term probabilities so estimated rely on the mean precursory time and its uncertainty as a function of the mainshock magnitude and epicentral position. Short-and intermediate-term modification of long-term probabilities within a 120,000 km² circular area covering most of Southern California are estimated for one or more observations of strain, resistivity, and ground water anomalies centered near Palmdale in the central Transverse Ranges. The principal assumptions employed are log normal distribution of globally reported waiting periods and assumed predictive reliability of precursory phenomena. As expected, the significance of short-and intermediate-term modifications scale with the reliability of precursory observations, and are particularly enhanced within window lengths of a precursory characteristic time.  相似文献   

Mixed convection-radiation interaction in boundary layers adjacent to horizontal,continuous moving sheets with suction and injuction     

M. A. Mansour 《Astrophysics and Space Science》1989,162(2):243-249

The interaction of mixed convection with thermal radiation in laminar boundary-layer flow over a horizontal, continuous, moving sheets with suction and injuction is studied. The fluid considered is a gray, absorbing-emitting but non-scattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. Both the buoyancy assisting and opposing flow cases are considered.  相似文献   

A real spectral analysis of the deformation of a homogenous electric field over a thin bed – A Hartley transform approach     

N. Sundararajan  Mansour A. Al-Garni  G. Ramabrahmam  Y. Srinivas 《Geophysical Prospecting》2007,55(6):901-910

Spectral analysis of the deformation of a homogenous electric field caused by a long, thin inclined bed, which is of considerable importance in the exploration of ground water and minerals, is presented using the Hartley transform. The Hartley transform is an alternative and real replacement for the well‐known complex Fourier transform in the field of spectral analysis. The thickness of the bed and the inclination are given as functions of frequency by simple expressions. A theoretical example illustrates the method while the applicability is demonstrated by the field examples from the fractured crystalline basement complex in Burkina Faso, Africa and the Precambrian limestones of the Cuddapah basin, Andhra Pradesh, India. The results obtained by this method agree well with those of the drilling.  相似文献   

Study of near-surface models for large-eddy simulations of a neutrally stratified atmospheric boundary layer     

Inanc Senocak  Andrew S. Ackerman  Michael P. Kirkpatrick  David E. Stevens  Nagi N. Mansour 《Boundary-Layer Meteorology》2007,124(3):405-424

In large-eddy simulations (LES) of the atmospheric boundary layer (ABL), near-surface models are often used to supplement subgrid-scale (SGS) turbulent stresses when a major fraction of the energetic scales within the surface layer cannot be resolved with the temporal and spatial resolution at hand. In this study, we investigate the performance of both dynamic and non-dynamic eddy viscosity models coupled with near-surface models in simulations of a neutrally stratified ABL. Two near-surface models that are commonly used in LES of the atmospheric boundary layer are considered. Additionally, a hybrid Reynolds- averaged/LES eddy viscosity model is presented, which uses Prandtl’s mixing length model in the vicinity of the surface, and blends in with the dynamic Smagorinsky model away from the surface. Present simulations show that significant portions of the modelled turbulent stresses are generated by the near-surface models, and they play a dominant role in capturing the expected logarithmic wind profile. Visualizations of the instantaneous vorticity field reveal that flow structures in the vicinity of the surface depend on the choice of the near-surface model. Among the three near-surface models studied, the hybrid eddy viscosity model gives the closest agreement with the logarithmic wind profile in the surface layer. It is also observed that high levels of resolved turbulence stresses can be maintained with the so-called canopy stress model while producing good agreement with the logarithmic wind profile.  相似文献   

Simplified analytical solutions for wave interaction with absorbing-type caisson breakwaters     

A. Neil Williams  Alaa-Eldin M. Mansour  Hong Sik Lee 《Ocean Engineering》2000,27(11)

Simplified analytical solutions are presented to model the interaction of linear waves with absorbing-type caisson breakwaters, which possess one, or two, perforated or slotted front faces which result in one, or two, interior fluid regions (chambers). The perforated/slotted surfaces are idealized as thin porous plates. Energy dissipation in the interior fluid region(s) inside the breakwater is modelled through a damping function. Under the assumption of potential flow and linear wave theory a boundary-value problem may then be formulated to describe wave interaction with the idealized structure. A solution to this simplified problem may be obtained by an eigenfunction expansion technique and an explicit analytical expression may be obtained for the reflected wave height. Using the experimental work of previous authors, damping coefficients are determined for both single and double chamber absorbing-type caisson breakwaters. Based on the damping for a single perforated-wall breakwater, a methodology is proposed to enable the estimation of the damping coefficients for a breakwater with two chambers. The theoretical predictions of the reflection coefficients for the two-chamber structures using the present model are compared with those obtained from laboratory experiments by other authors. It is found that the inclusion of the damping in the interior fluid region gives rise to improved agreement between theory and experiment.  相似文献   

Improved understanding of groundwater flow in complex superficial deposits using three-dimensional geological-framework and groundwater models: an example from Glasgow,Scotland (UK)     

R. J. Turner  M. M. Mansour  R. Dearden  B. É. Ó Dochartaigh  A. G. Hughes 《Hydrogeology Journal》2015,23(3):493-506

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An investigation on the Eocene Pushtasar basaltic lava in relation to Moghan Aulacogene     

Homayoon?MohammadihaEmail author  Mansour?Mostafazadeh  Neda?Gholami 《Arabian Journal of Geosciences》2015,8(5):2879-2887

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Geochemical characteristics of the Kal-e Kafi Cu-Mo-Au porphyry deposit,Central Iran     

Farzad Mahdavi  Ahmad Khakzad  Nima Nezafati  Mansour Vosughi-Abedini 《Arabian Journal of Geosciences》2015,8(12):10739-10758

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A mass flux closure function in a GCM based on the Richardson number     

Young-Min Yang  In-Sik Kang  Mansour Almazroui 《Climate Dynamics》2014,42(5-6):1129-1138

A mass flux closure in a general circulation model (GCM) was developed in terms of the mean gradient Richardson number (GRN), which is defined as the ratio between the buoyancy and the shear-driven kinetic energy in the planetary boundary layer. The cloud resolving model (CRM) simulations using the tropical ocean and global atmosphere-coupled ocean–atmosphere response experiment forcing show that cloud-base mass flux is well correlated with the GRN. Using the CRM simulations, a mass flux closure function is formulated as an exponential function of the GRN and it is implemented in the Arakawa–Schubert convective scheme. The GCM simulations with the new mass flux closure are compared to those of the GCM with the conventional mass flux closure based on convective available potential energy. Because of the exponential function, the new closure permits convective precipitation only when the GRN has a sufficiently large value. When the GRN has a relatively small value, the convection is suppressed while the convective instability is released by large-scale precipitation. As a result, the ratio of convective precipitation to total precipitation is reduced and there is an increase in the frequency of heavy precipitation, more similar to the observations. The new closure also improves the diurnal cycle of precipitation due to a time delay of the large GRN with respect to convective instability.  相似文献   

A climatological analysis of Saharan cyclones   总被引：1，自引：0，他引：1  

K. Ammar  Mossad El-Metwally  Mansour Almazroui  M. M. Abdel Wahab 《Climate Dynamics》2014,43(1-2):483-501

In this study, the climatology of Saharan cyclones is presented in order to understand the Saharan climate, its variability and its changes. This climatology includes an analysis of seasonal and interannual variations, the identification and classification of cyclone tracks, and a presentation of their chief characteristics. The data used are drawn from the 1980–2009, 2.5° × 2.5°, NCEP/NCAR reanalysis (NNRP I) dataset. It is found that cyclone numbers increase in September–October–November (SON) at 4.9 cyclones per decade, while they decrease in June–July–August at 12.3 cyclones per decade. The identification algorithm constructed 562 tracks, which are categorized into 12 distinct clusters. Around 75 % of the Saharan cyclones originate south of the Atlas Mountains. The percentage of tracks that move over the Sahara is around 48 %. The eastern Mediterranean receives 27 % of the Saharan tracks, while the western basin receives only 17 and 8 % of all the Saharan cyclones decay over the Arabian Peninsula. The maximum cyclonic activity occurs in April. There is a general decrease in the number of tracks in all categories between 1993 and 2009, compared with the period between 1980 and 1992. About 72 % of the Saharan cyclones do not live more than 3 days, and about 80 % of the cyclones in the tracks never reach central pressures 1,000 hPa during their lifetimes. The maximum deepening in the tracks occurs over the western Mediterranean and over northern Algeria.  相似文献