Extending F‐Perceptory to model fuzzy objects with composite geometries for GIS

When analyzing spatial issues, geographers are often confronted with many problems with regard to the imprecision of the available information. It is necessary to develop representation and design methods which are suited to imprecise spatiotemporal data. This led to the recent proposal of the F‐Perceptory approach. F‐Perceptory models fuzzy primitive geometries that are appropriate in representing homogeneous regions. However, the real world often contains cases that are much more complex, describing geographic features with composite structures such as a geometry aggregation or combination. From a conceptual point of view, these cases have not yet been managed with F‐Perceptory. This article proposes modeling fuzzy geographic objects with composite geometries, by extending the pictographic language of F‐Perceptory and its mapping to the Unified Modeling Language (UML) necessary to manage them in object/relational databases. Until now, the most commonly used object modeling tools have not considered imprecise data. The extended F‐Perceptory is implemented under a UML‐based modeling tool in order to support users in fuzzy conceptual data modeling. In addition, in order to properly define the related database design, an automatic derivation process is implemented to generate the fuzzy database model.     

Detection of Titan's Ionosphere from Voyager 1 Radio Occultation Observations

Evidence for a marginal detection of the Titan ionosphere has been obtained from a new analysis of the dual-frequency Doppler data recorded during theVoyager 1occultation in 1980. The original report by Lindalet al.(1983,Icarus53,348–363) gave only upper bounds on the peak electron density of 3000 cm⁻³during ingress (evening terminator) and 5000 cm⁻³during egress (morning terminator). The dual-frequency ingress data imply a maximum electron density of 2400 ± 1100 cm⁻³for Titan's upper ionosphere at an altitude of 1180 ± 150 km. The egress data were determined to be of limited use for this analysis because the X-band signal was received for only a few seconds. Nevertheless, a distinct ionospheric peak is revealed in the S-band data for both ingress and egress. The height and peak density of this ionized layer are in good agreement with expectations from numerical models that invoke photoionization and energetic electron impacts.     

Seismic tectono-stratigraphy of fluvio-deltaic to deep marine Miocene silicoclastic hydrocarbon reservoir systems in the Gulf of Hammamet,northeastern Tunisia

Most of hydrocarbon accumulations within the Gulf of Hammamet foreland basins in eastern Tunisia are reservoired within the Upper Miocene Birsa and Saouaf sandstones. It is the case of Birsa, Tazarka, Oudna, Baraka, Maamoura, Cosmos and Yasmine fields. These sandstones constitute oil and gas fields located on folded and faulted horst anticline highs and described as varying from shoreface to shallow marine and typically exhibit excellent reservoir quality of 30 to 35% porosity and good permeability from 500 to 1100 md. In addition, the fracturing of faults enhanced their reservoir quality potential. However, due to the lack of seismic stratigraphic studies to highlight depositional environment reservoir characterization and distribution, petroleum exploration faces structural and stratigraphic trap types and remains on targeting only high fold closures with limited reserve volumes of hydrocarbons. As an example of the Birsa concession case, syn-sedimentary tectonic structuring and geodynamic evolution during Middle to Upper Miocene Birsa reservoir sequences have guided the distribution of depositional environment of sandstone channel systems around horst and grabens by E-W, NE-SW and N-S strike slip flower faults controlling the subsidence distribution combined with the eustatic sea level variations. Seismic sequence stratigraphy study of Miocene Birsa reservoir horizons, based on the analysis and interpretations of E-W and N-S 3D selected regional lines that were compared and correlated to outcrops and calibrated by well data, permitted to highlight the basin configuration and sequence deposit nature and distribution. Sedimentary infilling of the basin from Langhian Ain Ghrab carbonate to Serravallian Tortonian Birsa and Saouaf sandstone and shale formations is organized in four third-order seismic sequences, limited by regional erosional toplap, onlap and downlap unconformity surfaces and by remarkable chronostratigraphic horizons of forced and normal erosive lowstand and highstand system tracts separated by transgressive and maximum flooding surfaces. Reconstructed sedimentary paleo-environment distribution vary from deltaic fluvial proximal deposits in the northern part of the high central Birsa horst to a delta front and prodelta coastal and shelf shore face and shore line channelized deposits in the surrounding borders of grabens. Distal deposits seem to be distributed from upper to lower slope fans and probably to the basin floor on the flanks of the subsiding grabens. Synthetic predictive paleogeographic depositional reservoir fairway map distribution of Lower, Middle and Upper Birsa sandstone reservoirs highlights four main domains of channelized superposed and shifted reservoirs to explore.     

Curie point depth beneath the Barramiya–Red Sea coast area estimated from aeromagnetic spectral analysis

The geothermal structure beneath of the Barramiya?CRed Sea coast area of the Central Eastern Desert of Egypt has been determined using Curie point depth (CPD), which is temperature-dependent. The CPD and the surface heat flow (q) maps of such area are estimated by analyzing aeromagnetic data. Such data are low-pass-filtered and analyzed to estimate the magnetic bottom using the centroid method. The heat flow map reflects the geothermic nature of the region. However, it is suggested that the shallow Curie point temperature depth pattern depends on the tectonic regime and morphology, which continues eastwards through the Red Sea. Particularly, the coastal regions are characterized by high heat flow (83.6?mW/m²) and shallow Curie depth (22.5?km), whereas the western portion of the studied area has a lower heat flow (<50?mW/m²) and deeper Curie depth (~40?km). In addition to its bordering to the Red Sea margin, such high heat flow anomaly is associated with the increased earthquake swarms activity in the Abu Dabbab area. El-Hady (1993) attributed the swarm activity to the geothermal evolution. Also, the heat flow pattern is correlatable by the numerous results of shallow borehole temperature measurements as reported by Morgan and Swanberg (1979). A significant low heat flow extending in the northeast?Csouthwest direction, which is associated with NE?CSW large areal extent negative Bouguer gravity anomaly and NE/SW-trending belt of the deep CPD region, seems to be directly related to the surface outcrops of Precambrian older granitoids of the mountainous range of that trend.     

On the thermal instability in numerical models of the interstellar medium

We investigate with 3D hydrodynamical simulations the role played by thermal processes in the dynamical evolution of the interstellarmedium (ISM). A parametric approach of the coolingprocess shows that the observed mass fraction of the cold (< 300 K)and unstable gas (300K < T < 6000K) can not be produced by turbulentcompression or background heating of the medium alone. An analysis of theproperties of the clouds that are formed by the combined effect of the thermal and gravitational instability shows that the cloud’s scaling relations imprinted by the thermal instability (TI) are in good agreementwith observational values.     

The Origin of the H I Holes in the Interstellar Medium of Holmberg II

We use a comparison between the autocorrelation length value in 21-cm hi maps of Holmberg II and the autocorrelation length derived from simulated maps in order to constrain the physical processes that are responsible for the observed distribution of holes and shells in the interstellar medium (ISM) of the galaxy. Our results show that large scale turbulence coupled to a weak cooling can reproduce the value of the autocorrelation length which is observed.     

The influence of sunspot canopies on magnetic inclination measurements in solar plages

Sunspots are known to have large, low-lying magnetic canopies, i.e. horizontal magnetic fields overlying a field-free medium, that cover substantial fractions of active region plage. In this paper we consider the influence of such canopies on the inclination of plage magnetic fields. We find that for observations in spectral lines like 5250.2Å the neglect of a sunspot canopy when determining magnetic inclination angles of plage fields can introduce errors exceeding 5–10°. This is particularly true if the observations do not have high spatial resolution. Thus this effect may explain some of the measurements of substantially inclined fields in solar plages. Furthermore we find that the Fe I 15648 Å line is far superior in giving correct flux-tube inclinations in the presence of a sunspot magnetic canopy. Finally, the inversion of full Stokes profiles is shown to produce more reliable results than results obtained by considering only ratios of individual Stokes profile parameters.     

The application of remote sensing and structural analysis in groundwater exploration in basement terrains, Darfur region, Western Sudan

Darfur region is one of the most vulnerable areas in Sudan that suffer from shortage in water supply. The objective of the current study is to utilize remote sensing techniques combined with the structural analysis to recognize the most potential fracture zones for groundwater occurrences in the hard rock terrains of Darfur region. The old ductile deformation features in Darfur region delineated from Landsat imageries are used for the structural analysis to determine and classify the fractures in the hard rock terrains of the region. Based on the structural analysis conducted in this study, Darfur region was divided into two domains—the western domain of the pre-Pan-African age that is affected by the two deformational phases (D1 and D2), and the eastern domain represented by the basement related to the Pan-African orogeny. The most potential fractures in the western domain are in the NW–SE and NE–SW trends that classified as extensional and release open fractures for the deformations D1 and D2. In the eastern domain, the main potential fractures for groundwater occurrence are in E–W and N–S directions that are classified as extensional and release open fractures of the deformation D3. From the results of the structural analysis, the main potential fracture systems in Darfur region trend are NW–SE, NE–SW, and E–W directions. The intersections of these fracture systems are the most promising targets for drilling, with consideration of the topography, the rates of recharge, and the underlying geology. The geophysical data and boreholes information in Zalingei and north of El Geneina areas in West Darfur confirm the results obtained from remote sensing data and structural analysis, in which the NW–SE, NE–SW, and E–W fractures trends are the most potential fractures in Darfur region.