Experimental and numerical investigation for energy dissipation of supercritical flow in sudden contractions

Dealing with kinetic energy is one of the most important problems in hydraulic structures, and this energy can damage downstream structures. This study aims to study energy dissipation of supercritical water flow passing through a sudden contraction. The experiments were conducted on a sudden contraction with 15 cm width. A 30 cm wide flume was installed. The relative contraction ranged from 8.9 to 9.7, where relative contraction refers to the ratio of contraction width to initial flow depth. The Froude value in the investigation varied from 2 to 7. The contraction width of numerical simulation was 5~15 cm, the relative contraction was 8.9~12.42, and the Froude value ranged from 8.9~12.42. In order to simulate turbulence, the k-ε RNG model was harnessed. The experimental and numerical results demonstrate that the energy dissipation increases with the increase of Froude value. Also, with the sudden contraction, the rate of relative depreciation of energy is increased due to the increase in backwater profile and downstream flow depth. The experimentation verifies the numerical results with a correlation coefficient of 0.99 and the root mean square error is 0.02.     

A parallel ensemble-based framework for reservoir history matching and uncertainty characterization

We present a parallel framework for history matching and uncertainty characterization based on the Kalman filter update equation for the application of reservoir simulation. The main advantages of ensemble-based data assimilation methods are that they can handle large-scale numerical models with a high degree of nonlinearity and large amount of data, making them perfectly suited for coupling with a reservoir simulator. However, the sequential implementation is computationally expensive as the methods require relatively high number of reservoir simulation runs. Therefore, the main focus of this work is to develop a parallel data assimilation framework with minimum changes into the reservoir simulator source code. In this framework, multiple concurrent realizations are computed on several partitions of a parallel machine. These realizations are further subdivided among different processors, and communication is performed at data assimilation times. Although this parallel framework is general and can be used for different ensemble techniques, we discuss the methodology and compare results of two algorithms, the ensemble Kalman filter (EnKF) and the ensemble smoother (ES). Computational results show that the absolute runtime is greatly reduced using a parallel implementation versus a serial one. In particular, a parallel efficiency of about 35 % is obtained for the EnKF, and an efficiency of more than 50 % is obtained for the ES.     

Object-Based Rule Sets and Its Transferability for Building Extraction from High Resolution Satellite Imagery

With the advent of high spatial resolution satellite imagery, automatic and semiautomatic building extractions have turned into one of the outstanding research topics in the field of remote sensing and machine vision. To this date, various algorithms have been presented for extracting the buildings from satellite images. Such methods lend their bases to diverse criteria such as radiometric, geometric, edge detection, and shadow. In this paper, a novel object based approach has been proposed for automatic and robust detections as well as extraction of the building in high spatial resolution images. To fulfill this, we simultaneously made use of both stable and variable features. While the former can be derived from inherent characteristics of the buildings, the latter is extracted using a feature analysis tool. In addition, a novel perspective has been recommended to boost the automation degree of the segmentation part in the object based analysis of remote sensing imagery. The proposed method was applied to a QuickBird imagery of an urban area in Isfahan city and the results of the quantitative evaluation demonstrated that the proposed method could yield promising results. Moreover, in another section of this study, for assessing the algorithm transferability, the rule set was implemented to a part of the WorldView image of Yazd city, proving that the proposed approach is capable of transferability in different types of case studies.     

Using high-resolution satellite imagery to provide a relief priority map after earthquake

After the earthquake occurrence, collecting correct information about the extent of damage is essential for managing critical conditions and allocating limited resources. The prepared building damage maps sometimes bring about waste of time required for rescuing individuals under the rubble by wrongly conducting rescue teams toward regions with a lower rescue priority. In this research, an algorithm based on using a proposed standard at database level was developed to prioritize damaged buildings by considering five key elements of land use type, the degree of damage to buildings, the land use differentiation index, time of the highest population density in each land use, and time of disaster’s incidence. The steps of the proposed method which was implemented in the MATLAB environment include: detecting buildings on the pre- and post-event imagery, implementing texture features for each candidate building, choosing the optimal features by genetic algorithm, determining the degree of building damage in three classes of negligible damage, substantial damage, and heavy damage by using the difference between chosen features as inputs of the designed neurofuzzy inference system. Data collected from field observations were compared to the output obtained from the proposed algorithm. This comparison presented a general accuracy of 88% and Kappa coefficient of 79% in the classification of buildings into three damage classes. The proposed standard then was used for classifying damaged buildings into relief priorities of high, medium, and low. Findings revealed that the relief priority map could be a basis for correct guidance of relief and rescue teams during crucial times following earthquakes.     

Geochemical prospecting for lead and zine in Gebel el Rousas,Eastern Desert,Egypt

Gebel El Rousas is an isolated hillock in the Eastern Desert of Egypt. It consists of the Basement Complex (subsurface) which is non-conformably overlain by the Middle Miocene and successively by Pleistocene-Recent terraces. The Miocene strata are mineralized by oxidized hypogene lead-zinc deposits.Geochemical prospecting was attempted for the first time in Gebel El Rousas and for the second time in Egypt. The old terraces of gravels and sands covering the hillock were sampled on a grid pattern of a 30 m spacing. The samples were taken at a depth of 30 cm from the surface. They were sieved to –150 mesh and analyzed for Pb, Zn, Cu, Fe, Mn, and CO₂.Significant contrasts and anomalies resulted for Pb, Zn, and Fe. The main anomalies are parallel and generally coincide with the subsurface mineralized zone which is inferred to cross the area on the same trend. The mineralized zone extends as shown by the geochemical pattern southward, from the known northern part, to a southern district which has not been checked by drilling or any other testing.

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Zusammenfassung Djebel El Rousas ist ein isolierter Hügel in der Ägyptischen Ostwüste. Er besteht aus dem Basementkomplex, der diskordant von MittelmiozÄn und aufeinanderfolgend von PleistozÄn-HolozÄn-Terrassen überlagert wird. Die MiozÄn-Schichten sind mit oxydischen hypogenen Blei-Zink-Ablagerungen vererzt.Im Djebel El Rousas wurde zum erstenmal der Versuch einer geochemischen Prospektion durchgeführt, für ganz Ägypten ist es das zweite Mal. Gitterförmig wurden im Abstand von 30 m den alten Kies- und Sandterrassen, die den Hügel bedecken, Proben aus einer Tiefe von 30 cm unter der OberflÄche entnommen. Die Proben wurden mit 150 Maschenweite gesiebt und auf Pb, Zn, Cu, Fe, Mn und CO₂ analysiert.Eindeutige Kontraste und Anomalien wurden für Pb, Zn und Fe festgestellt. Die Hauptanomalien sind parallel und fallen normalerweise mit der mineralisierten Zone unter Tage zusammen, die das Gebiet in derselben Richtung durchquert. Wie aus der geochemischen Karte hervorgeht, setzt sich die vererzte Zone nach Süden in ein Gebiet fort, das bisher noch nicht durch Bohrungen untersucht wurde.

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Résumé Gebel El Rousas est un monticule isolé dans le Désert Oriental de l'égypte. Il se compose de roches du Basement Complex (sous-sol) surmontées en discordance par des terrasses du Miocène Moyen et succéssivement par des terrasses du Pleistocène-Récent. Les couches du Miocène sont mineralisées par des dépÔts hypogènes de plomb et de zinc oxidés.Les prospections géochimiques furent essayées pour la première fois au Gebel El Rousas et pour la seconde fois en égypte. Des échantillons des anciennes terrasses de galets et de sables recouvrant ce monticule furent prises en une carte quadrillé de 30 m. Les échantillons furent prélevés à une profondeur de 30 cm de la surface. Ils furent criblés jusqu'aux mailles de 150 analysées pour la détermination de Pb, Zn, Cu, Fe, Mn, et CO₂.Des contrastes et des anomalies significatifs furent obtenus pour le Pb, Zn, et Fe. Les anomalies essentielles sont parallèles et généralement coincident avec la zone minéralisée du sous-sol qui est supposée traverser la région suivant la mÊme direction. La zone minéralisée s'étend comme l'indique la carte géochimique du Nord au Sud vers un district qui n'a pas été vérifié par forage ou par toute autre méthode éxpérimentale.

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Appraisal of Anchor Arrangement and Size on Sand-Geogrid Interaction in Direct Shear

Geotechnical and Geological Engineering - Soil–reinforcement interaction is a major factor in the analysis and design of reinforced earth structures. In current research the effects of...     

Integration of the MODIS Snow Cover Produced Into Snowmelt Runoff Modeling

Because of the difficulty of monitoring and measuring snow cover in mountainous watersheds, satellite images are used as an alternative to mapping snow cover to replace the ground operations in the watershed. Snow cover is one of the most important data in simulation snowmelt runoff. The daily snow cover maps are received from Moderate Resolution Imaging Spectroradiometer (MODIS), and are used in deriving the snow depletion curve, which is one of the input parameters of the snowmelt runoff model (SRM). Simulating Snowmelt runoff is presented using SRM model as one of the major applications of satellite images processing and extracting snow cover in the Ghara - Chay watershed. The first results of modeling process show that MODIS snow covered area product can be used for simulation and forecast of snowmelt runoff in Ghara - Chay watershed. The studies found that the SCA results were more reliable in the study area.     

Dust acoustic solitary and shock waves in coupled dusty plasmas with variable dust charge and vortex-like ion distribution

The modified Kodomtsev-Petviashvili-Burger (mKP-Burger) and Kodomtsev-Petviashvili-Burger equations are derived in strongly coupled dusty plasmas containing iso-nonthermal ions; Boltzmann distributed electrons and variable dust charge. We use reductive perturbation method and discuss on solitary waves and shock waves solutions of these equations.     

Modeling the connectivity and intersection of hydraulically loaded cracks with in situ fractures in rock

The interaction of an advancing hydraulically loaded crack and in situ fracture network can yield highly complex patterns. We model the connectivity of cells in a finite element domain and in a fracture network by a simplicial complex data structure. The complete adjacency information between cells is determined by one level down facet and one level up cofacet neighborhood information. Combined with a disjoint set data structure, explicit algorithms are derived to efficiently track network connectivity and load transfer between independent fracture sets. We also propose an approach to regularize the application of hydraulic load to newly intersected in situ cracks to smoothen the transition of pressure on intersected cracks from ambient to hydraulic pressure and to avoid the sudden loading of the entire length of these cracks. Numerical results demonstrate the performance of crack connectivity and load transfer models and the effect of regularization model. The results show that as the angle between an incoming hydraulically loaded crack and an in situ crack increases, the effect of in situ crack shifts from slight realignment to diversion/offsetting of the loaded crack. As the angle difference approaches the normal angle, the loaded crack tends to penetrate through the in situ crack. The proposed schemes are also used for transient simulation of 2D reservoirs with multiple perforations surrounded by in situ cracks with and without a bias in the distribution of their orientation. It was shown that from 2 perforations with angles closer to in situ cracks at low loading rates to all perforations at higher loading rates can result in active hydraulic crack propagation. The h‐adaptive method of asynchronous space‐time discontinuous Galerkin method is used to exactly track complex fracture patterns in these dynamic fracture simulations.     

Protostellar evolution during time-dependent anisotropic collapse

The formation and collapse of a protostar involves the simultaneous infall and outflow of material in the presence of magnetic fields, self-gravity and rotation. We use self-similar techniques to self-consistently model the anisotropic collapse and outflow by using a set of angle-separated self-similar equations. The outflow is quite strong in our model, with the velocity increasing in proportion to radius, and material formally escaping to infinity in the finite time is required for the central singularity to develop.
Analytically tractable collapse models have been limited mainly to spherically symmetric collapse, with neither magnetic field nor rotation. Other analyses usually employ extensive numerical simulations, or either perturbative or quasistatic techniques. Our model is unique as an exact solution to the non-stationary equations of self-gravitating magnetohydrodynamics (MHD), which features co-existing regions of infall and outflow.
The velocity and magnetic topology of our model is quadrupolar, although dipolar solutions may also exist. We provide a qualitative model for the origin and subsequent evolution of such a state. However, a central singularity forms at late times, and we expect the late-time behaviour to be dominated by the singularity, rather than depend on the details of its initial state. Our solution may, therefore, have the character of an attractor among a much more general class of self-similarity.