Satellite image retrieval using low memory locality sensitive hashing in Euclidean space

This paper presents the use of the Low Memory Locality Sensitive Hashing (LMLSH) technique operating in Euclidean space to build a data structure for the Defense Meteorological Satellite Program (DMSP) satellite imagery database. The LMLSH technique finds satellite image matches in sublinear search time. The texture feature vectors of the images are extracted using pyramid-structured wavelet transform coupled with Gaussian central moment technique. These feature vectors and families of hash functions, drawn randomly and independently from a Gaussian distribution, are used to build hash tables. Given a query, the hash tables are used to pull out the best matches to that query and this is done in a sublinear search time complexity. When tested, our algorithm has proven to be approximately twenty six times faster than the Linear Search (LS) algorithm. In addition, the LMLSH algorithm searches about two percent of the entire database randomly to find the possible matches to any given query without loss of accuracy compared to the absolute best matches returned by its LS counterpart.     

Gypsum and dolomite biomineralization in endoevaporitic microbial niche,EMISAL, Fayium,Egypt

Biogenic gypsum in the form of microbialite and potential domal stromatolite as well as endoevaporitic dolomite are deposited in a perennial saline basin characterized by microbial bloom. Deposition environment, mode of occurrence, and microscopic investigation including SEM of these precipitates are discussed in conjunction with XRD, XRF, and FTIR data. Combined effects of salinity gradient and the wind action on the maturity of gypsum outcrop are evident. A characteristic multi-color vertical gypsum profile reflects steep gradient of oxi-anoxic microenvironments and encodes diverse seasonal microbial communities. Direct impact of microbial signature in gypsum crystal habit is conspicuous. Endoevaporitic authigenic dolomite is recorded in specific horizons in interstices of selenite layers.     

Geochemistry and fluid inclusions study of highly fractionated garnet-bearing granite of Gabal Abu Diab, central Eastern Desert of Egypt

The Neoproterozoic granite of Gabal Abu Diab, central Eastern Desert of Egypt, comprises mainly garnet-bearing granite and alkali feldspar granite intruded into calc-alkaline granodiorite–tonalite and metagabbro–diorite complexes. The garnet-bearing granite is composed mainly of plagioclase, K-feldspar, quartz, garnet and primary muscovite ± biotite. The presence of garnet and primary muscovite of Abu-Diab granite suggests its highly fractionated character. Geochemically, the garnet-bearing granite is highly fractionated as indicated from the high contents of SiO₂ (74.85–77.5%), alkalis (8.27 to 9.2%, Na₂O+K₂O) and the trace elements association: Ga, Zn, Zr, Nb and Y. This granite is depleted in CaO, MgO, P₂O₅, Sr and Ba. The alumina saturation (Shand Index, molar ratio A/CNK) of 1.0 to 1.1 indicates the weak peraluminous nature of this garnet-bearing granite. The geochemical characteristics of the Abu Diab garnet-bearing granite are consistent with either the average I-type or A-type granite and also suggest post-orogenic or anorogenic setting. A fluid inclusions study reveals the presence of three fluid generations trapped into the studied granite. The earlier is a complex CO₂–H₂O fluid trapped in primary fluid inclusions with CO₂ contents >?60 vol.%. These inclusions were probably trapped at minimum temperature >?400°C and minimum pressure >?2 kb. The second is immiscible water–CO₂ fluid trapped in secondary and/or pseudo-secondary inclusions. The trapping conditions were estimated at temperature between 400°C and 170°C and pressure between 900 and 2000 bar. The latest fluid is low-salinity aqueous fluid trapped in secondary two-phase and mono-phase inclusions. The trapping conditions were estimated at temperature between 90°C and 160°C and pressure <?900 bar. The origin of the early fluid generation is magmatic fluid while the second and third fluids are of hydrothermal and meteoric origin, respectively.     

Genesis of folds in external zones: application of fault propagation fold model. Gafsa Basin example (southern central Tunisia)

The evolution of geological structures is related particularly to reactivation of preexisting fault, thus the importance of tectonic inheritance. Basing on stratigraphic and structural data in external zones leaving the example of Gafsa Basin (southern central Tunisia), we study the evolution of folds during tectonic phases. The structural and stratigraphic data prove that Gafsa Basin is subject for more than one tectonic phase where beginning by Cretaceous extension and reactivated by Atlasic compression. The combination of field results associated to that geomorphology confirms the application of “fault propagation model” as evolution mode of folds. The balanced of cross section, using numerical software Ramp E.M. 1.5.2, shows the importance of tectonic inheritance to interpret evolution of structures reliefs. The deformation increases related to reactivation of old normal fault. The most important deformation is observed in Jbal At Taghli presenting folds in the form of duplex resulted from conjugate activity of tear fault; it is the first interpretation of tear fault activity in surface in the scale of Tunisia. The application of fault propagation fold model to interpret fold genesis confirms the field data and proves the role of tectonic inheritance and reactivation of preexisting faults in the evolution of structures during different tectonic phases.     

Real surface conductivity component as indicator for the hydraulic conductivity

Estimation of hydraulic conductivity from surface resistivity measurements is one of the most difficult and challenging hydrogeophysical targets. The promising side of this relation is the analogy between electric current flow and water flow, whereas the grand ambiguity is the non-dimensionality between both two quantities. Imaginary surface conductivity component is used recently to deduce the hydraulic conductivity via complex resistivity measurements. Since there are similar properties between imaginary (out-of-phase) and real (in-phase) surface conductivity components, the latter is used in this paper to predict the hydraulic conductivity. Two mathematical parameters were determined to express the electrical equivalent of hydraulic conductivity in sand and clay systems based on the mode of electrical double-layer formation in both systems. The reliability of the proposed method is tested through applying on two datasets representing sand and clay systems. The first dataset is a clean sand and gravel aquifer in the Keritis basin in Chania, Crete, Greece. The second is mostly clayey sand aquifer in Wadi El-Assuity, Egypt. Application of the present approach in these two cases resulted in promising nearly identical values with the measured hydraulic conductivity via pumping test or geometric hydraulic conductivity via grain size analysis.     

A new emergent alpine front chain in central Tunisia (Maktar area): filtering gravimetric data contribution

A residual anomaly gravity map of the Maktar area has been processed via several methods including horizontal gradient, upward continuation, and Euler deconvolution to highlight structures hidden by sedimentary cover. These methods reinforce the existence of several faults inferred from geologic studies. This work outlines deep or near-surface faults that had remained hidden until now. The most important set of these faults is NE–SW trending, with depths in excess of 3,000 m. These faults limit the Northwestern limb of Balouta massif and restrain the Northwestern side of Oued Ousafa syncline. This last fault presents a thrust front which constituted the western continuity of a southern Tunisian thetys margin and a western Zaghouan scar prolongation. E–W striking faults refer to an arched beam of faults limiting Kessera plateau and others situated in the northern part of the Maktar plateau. N–S and NW–SE directions correspond to branches of less-apparent importance. Superposition of local maxima specifies dipping vergence of different proven structures. Results from this work show the importance of gravimetric data analysis in Maktar area and provide new insight into Central Atlas Tunisia structure such as new emergent segment front Alpine chain. The proposed map could be a basis for planning future hydrogeological and petroleum research in this region.     

Conceptual model and numerical simulation of the hydrothermal system in Hammam Faraun hot spring, Sinai Peninsula, Egypt

The tectonic position of Egypt in the northeastern corner of the African continent suggests that it may possess significant geothermal resources, especially along its eastern margin. The most of the thermal springs in Egypt are located along the shores of Gulf of Suez and Red Sea. These springs are probably tectonic or nonvolcanic origin associated with the opening of the Red Sea—Gulf of Suez rifts, where the eastern shore of the Gulf of Suez is characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures. Hammam Faraun area consists of the hottest spring in Egypt where the water temperature is 70°C. Conceptual as well as numerical models were made on the Hammam Faraun hot spring based on geological, geochemical, and geophysical data. The models show that the heat source of the hot spring is probably derived from high heat flow and deep water circulation controlled by faults associated with the opening of the Red Sea and Gulf of Suez rifts.     

Geochemical characteristics and hydrocarbon generation modeling of the Jurassic source rocks in the Shoushan Basin, north Western Desert, Egypt

The Shoushan Basin is an important hydrocarbon province in the Western Desert, Egypt, but the origin of the hydrocarbons is not fully understood. In this study, organic matter content, type and maturity of the Jurassic source rocks exposed in the Shoushan Basin have been evaluated and integrated with the results of basin modeling to improve our understanding of burial history and timing of hydrocarbon generation. The Jurassic source rock succession comprises the Ras Qattara and Khatatba Formations, which are composed mainly of shales and sandstones with coal seams. The TOC contents are high and reached a maximum up to 50%. The TOC values of the Ras Qattara Formation range from 2 to 54 wt.%, while Khatatba Formation has TOC values in the range 1-47 wt.%. The Ras Qattara and Khatatba Formations have HI values ranging from 90 to 261 mgHC/gTOC, suggesting Types II-III and III kerogen. Vitrinite reflectance values range between 0.79 and 1.12 VRr %. Rock−Eval T_max values in the range 438-458 °C indicate a thermal maturity level sufficient for hydrocarbon generation. Thermal and burial history models indicate that the Jurassic source rocks entered the mature to late mature stage for hydrocarbon generation in the Late Cretaceous to Tertiary. Hydrocarbon generation began in the Late Cretaceous and maximum rates of oil with significant gas have been generated during the early Tertiary (Paleogene). The peak gas generation occurred during the late Tertiary (Neogene).     

Analytical Approach to the Motion of a Lunar Artificial Satellite

The canonical equations of motion of an artificial lunar satellite are formulated including the effects of the asphericity of the Moon comprising the harmonics J ₂, J ₂₂, J ₃, J ₃₁, J ₄ andJ ₅, the oblateness of the Earth up to the second zonal harmonic, as well as the disturbing function due to the attractions of the Earth and of the Sun (terms are retained up to order 10^-6 for the higher orbits and 10^-8 for the lower orbits). This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative assessment of two distributed watershed models with application to a small watershed

Distributed watershed models are beneficial tools for the assessment of management practices on runoff and water‐induced erosion. This paper evaluates, by application to an experimental watershed, two promising distributed watershed‐scale sediment models in detail: the Kinematic Runoff and Erosion (KINEROS‐2) model and the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model. The physics behind each model are to some extent similar, though they have different watershed conceptualizations. KINEROS‐2 was calibrated using three rainfall events and validated over four separate rainfall events. Parameters estimated by this calibration process were adapted to GSSHA. With these parameters, GSSHA generated larger and retarded flow hydrographs. A 30% reduction in both plane and channel roughness in GSSHA along with the assumption of Green‐Ampt conductivity K_G‐A = K_s, where K_s is the saturated conductivity, resulted in almost identical hydrographs. Sediment parameters not common in both models were calibrated independently of KINEROS‐2. A comparative discussion of simulation results is presented. Even though GSSHA's flow component slightly overperformed KINEROS‐2, the latter outperformed GSSHA in simulations for sediment transport. In spite of the fact that KINEROS‐2 is not geared toward continuous‐time simulations, simulations performed with both models over a 1 month period generated comparable results. Copyright © 2006 John Wiley & Sons, Ltd.