Estimation of frequency dependent coda wave attenuation structure at the vicinity of Cairo Metropolitan Area

Estimation of seismic wave attenuation in the shallow crust in terms of coda wave Q structure previously investigated in the vicinity of Cairo Metropolitan Area was improved using seismograms of local earthquakes recorded by the Egyptian National Seismic Network. The seismic wave attenuation was measured from the time decay of coda wave amplitudes on narrow bandpass filtered seismograms based on the single scattering theory. The frequency bands of interest are from 1.5 to 18 Hz. In general, the values obtained for various events recorded at El-Fayoum and Wadi Hagul stations are very similar for all frequency bands. A regional attenuation law Q _c = 85.66 f ^0.79 was obtained.     

Experimental and Numerical Investigation of the Flow Hydraulic in Gradual Transition Open Channels

Channel expansions are common in both natural and artificial open channels. With increasing cross-sectional dimensions in an expansion, the flow decelerates. Due to separation of flow and subsequent eddy formation, a significant head loss is occurred along the transition. This study presents the results of experimental investigations on subcritical flow along the expansive transition of rectangular to trapezoidal channels. Also, a numerical simulation was developed using the finite volume method with Reynolds Stress turbulent model. Water surface profiles and velocity distributions of flow through the transition were measured experimentally and compared with the numerical results. Also, hydraulic efficiency of the transition and coefficient of energy head loss were calculated. The results show that with increasing the upstream Froude number, hydraulic efficiency of the transition and coefficient of energy head loss are decreased and increased, respectively. The results also showed the ability of numerical simulation for simulating the flow separation zones and bed shear stress along the transition for different inlet discharges and inflow Froude numbers.     

Expansion theory for the elliptic motion of arbitrary eccentricity and semi-major axis

In this paper of the series, the time transform and the explicit exact forms of the time will be established in terms of the sectorial variables _j ⁽ⁱ⁾ introduced in Paper IV (Sharaf, 1982) to regularize the highly oscillating perturbation force. Simple recurrence formulae are given to facilitate the computations. The formulations are general in the sense that they are valid whatever the types and the number of sectors forming the divisions situation of the elliptic orbit may be. Moreover, the constants of integration for the explicit forms of the time are determined in a way that it gives for these forms its generality during any revolution of the body in its Keplerian orbit.     

General integral transform of the exponential integrals

General integral transform of the exponential integralsE _n is considered and will be denoted asB _(k) ⁿ (). Different expressions and the equations satisfied byB _(k) ⁿ are developed. Two-term recurrence formula forB _(k) ⁿ (0) and three-term recurrence formula forB _(k) ⁿ (); 0 will be established for a givenk1 andn=2,3, ...,N. The computational algorithms based on these formulae are also constructed for the casesk=1,2,3, andn2. Finally the numerical results fork=2,3 andn=2(1)25 are presented to 15-digit accuracy     

Does a representative volume element exist for fatigue life prediction? The case of aggregate composites

In a previous work, discrete modeling and a statistical approach were used to quantify the minimal representative volume element (RVE) size for aggregate composites, such as bituminous materials in the linear elastic regime (Comput. Mater. Sci. 2005; 33 :467–490). In this paper, the discrete model is extended to strain‐softening behavior under cyclic loading. The existence of a RVE for fatigue life prediction is numerically proved and its minimal size is determined. It is found that it is much larger than the minimal RVE size in the elastic regime. Copyright © 2007 John Wiley & Sons, Ltd.     

An integrated data-mining and multi-criteria decision-making approach for hazard-based object ranking with a focus on landslides and floods

This study is aimed at conducting a hazard-based sustainability gap analysis considering spatial threats driven by floods and landslides, that is, a multi-hazard-based prioritization of the most important cities in Gorganrood Basin, Iran. Two data-mining models were used to assess the spatial probability of flood inundation and landslide occurrence, namely, support vector machine with the radial basis function kernel (SVM-RBF) and maximum entropy (ME). As inputs, a total of 124 flooded locations and 346 landslides with ten flood/landslide predisposing factors were mapped using geoinformatics and organizational data. The random selection method was used to split the flood and landslide inventories into two sets of train and test data. Tolerance index was used to test the multicollinearity among predictors. Validation of the models was carried out using the area under the receiver operating characteristic (ROC) curve (AUC). Finally, TOPSIS was used, as a multi-criteria decision-making model, to make an internal sustainability gap analysis to prioritize the threatened and safe cities. For flood inundation, the AUC values obtained from the test set revealed that the SVM-RBF outperformed ME in terms of predictive power and generalization capacity with the respective areas of 0.831 and 0.796 under the curve. For landslide susceptibility assessment, SVM-RBF again excelled ME in predictive power with the respective values of 0.887 and 0.84. Therefore, the susceptibility maps derived from SVM-RBF, as the premier model, were used for the next stage. Extracting the flood and landslide spatial probability values to 14 city points, the TOPSIS-Solver software made a prioritization using the similarity function to the ideal solution. Accordingly, Aliabad, Minoodasht, and Azadshahr cities, with having the smallest similarity coefficients, were found to be the top three spatially threatened cities in Gorganrood Basin, while Aq Qala, Gomishan, and Gonbad-e Kavus cities were placed at the bottom as the safest cities. This study can be a pivotal point in regional risk-based planning, implementation of further pragmatic measures, and allocation of resources for improving sustainable development most wisely.     

Utilization of supervised classification in structural and lithological mapping of Wadi Al-Marwah Area,NW Arabian Shield,Saudi Arabia

Wadi Al-Marwah area is located in the northwestern part of the Arabian Shield, Saudi Arabia. It is mainly covered by Precambrian igneous and sedimentary rock units. This area was not subjected to previous detailed lithological or structural mapping. This study aims to apply supervised classification technique of remotely sensed digital satellite data of Landsat 7 for detailed lithological and structural mapping of the area. The fusion between multispectral Enhanced Thematic Mapper (ETM)+ data and high-resolution panchromatic ETM+ band-8 produced a color composite fused image for the study area, scale 1:50,000. The structural lineaments of the study area were extracted and interpreted from the digital imageries data. Little discrepancies or improvements were detected when combining the supervised classification results with the Landsat ratios or principal component analysis. These highlighted the benefits of multispectral classification, especially in terms of lithologic discrimination. The overall results of image processing techniques, applied in this work, were excellent and succeeded in the performance of a more detailed and accurate lithological and structural maps (scale 1:50,000) than the previous published maps for the investigated area.     

Synoptic features associated with dust transition processes from North Africa to Asia

Aerosol index data from the total ozone mapping spectrometer satellite and reanalysis data from the National Center for Environmental Prediction and the National Center for Atmospheric Research are useful in the study of synoptic properties of the dust storms that carry dust from North Africa to Asia during the spring season for the period 1979 to 2006. In this study, we analyzed the synoptic properties of dust cases that pass through the transition zone between North Africa and Asia. We identified the dust cases to study by looking, inside transition zone, at events with an aerosol index greater than 2. We then divided the identified cases, depending on the spread and strength of the dust inside the transition zone, into seven categories ranging from weak events to moderate events to violent events. We found the common synoptic characteristics in all these categories as follows: The high pressure belt located over northern Africa allows the low pressure belt located over the South African Sahara to move northward; a pressure gradient between these two atmospheric systems directs from south to north; an increase in the pressure gradient leads to increased in both of the event’s dust and the amount of dust moves to North Africa from the Sahara; an additional pressure gradient between the western Azores high pressure system and the low pressure system located over the Arabian Peninsula directs from west to east; the stronger the pressure gradient, the greater the amount of dust in the event and moving a large amount of dust from Northeast Africa to Asia. To verify that these characteristics capture the essence of dust events from North Africa to Asia, we checked if they were also common to two additional extremes categories and two extremes events. The results confirmed the continued existence of these common characteristics.     

A phased approach to enable hybrid simulation of complex structures

Hybrid simulation has been shown to be a cost-effective approach for assessing the seismic performance of structures. In hybrid simulation,critical parts of a structure are physically tested,while the remaining portions of the system are concurrently simulated computationally,typically using a finite element model. This combination is realized through a numerical time-integration scheme,which allows for investigation of full system-level responses of a structure in a cost-effective manner. However,conducting hybrid simulation of complex structures within large-scale testing facilities presents significant challenges. For example,the chosen modeling scheme may create numerical inaccuracies or even result in unstable simulations; the displacement and force capacity of the experimental system can be exceeded; and a hybrid test may be terminated due to poor communication between modules(e.g.,loading controllers,data acquisition systems,simulation coordinator). These problems can cause the simulation to stop suddenly,and in some cases can even result in damage to the experimental specimens; the end result can be failure of the entire experiment. This study proposes a phased approach to hybrid simulation that can validate all of the hybrid simulation components and ensure the integrity largescale hybrid simulation. In this approach,a series of hybrid simulations employing numerical components and small-scale experimental components are examined to establish this preparedness for the large-scale experiment. This validation program is incorporated into an existing,mature hybrid simulation framework,which is currently utilized in the Multi-Axial Full-Scale Sub-Structuring Testing and Simulation(MUST-SIM) facility of the George E. Brown Network for Earthquake Engineering Simulation(NEES) equipment site at the University of Illinois at Urbana-Champaign. A hybrid simulation of a four-span curved bridge is presented as an example,in which three piers are experimentally controlled in a total of 18 degrees of freedom(DOFs). This simulation illustrates the effectiveness of the phased approach presented in this paper.