A contribution to the geology of the Bahariya Oasis,Western Desert,Egypt

Size and mineral analysis of the Upper Cretaceous clastics of the Bahariya Oasis indicate moderately well sorted, coarse skeewed and mesokurtic sediments. These sediments were most probably derived from mixed igneous, metamorphic and sedimentary sources, under conditions of low rainfall and poor drainage interfered by high rainfall periods.The shape of quartz grains and occurrence of stable and less stable minerals prove a short distance, saltation to graded suspension transportation of these sediments.Probably coastal plain, interfered by fresh water conditions had prevailed during the accumulation of these sediments, i.e. fluviomarine environment.     

A contribution to the geology of the Bahariya Oasis,Western Desert,Egypt

Detailed petrographic investigations of the Upper Cretaceous-Eocene succession exposed at Bahariya Oasis resulted in the recognition of different litho- and biofacies associations, mostly of the carbonate rock type.The litho- and biofacies characters of the Eocene strata reveal comparatively shallow, quiet marine conditions, interrupted by agitated, high energy intervals.During the Maastrichtian age, deeper quiet marine conditions prevailed. The Upper and Lower members of the Campanian strata were deposited under deep quiet marine conditions, relative to shallower agitated conditions that prevailed during the deposition of the middle member.The Lower Cenomanian sediments were deposited under an alternating high and low energy fresh water environment, interrupted with saline (fluviomarine) periods, relative to the comparatively deeper marine conditions that prevailed during the Upper Cenomanian age.The main diagenetic processes recorded are: cementation, aggrading neomorphism, silicification and dolomitization.     

The molecular weight distribution of coal extracts. Coalification is not a condensation polymerization

The pyridine extracts from Bruceton and Illinois No. 6 coals were fractionated using gel permeation chromatography and the molecular weight of each fraction was measured using vapor pressure osmometry. If, as has been suggested, coalification is a simple condensation polymerization from a mixture of monomers with gel formation, then as the molecular weight of the components increase, their concentration should decrease. Exactly the opposite behavior is observed. The number average molecular weights for the Bruceton and Illinois No. 6 extracts respectively are 860 daltons and 1100 daltons while the corresponding weight average molecular weights calculated from the molecular weight distribution are 2300 daltons and 2700 daltons.     

An investigation of Malaysian granitic rocks as suitable sources of feldspar

Medium- to coarse-grained leucocratic granitic bodies containing more than 60% feldspar and less than 10% mafic minerals are found to be appropriate and potential source materials of local feldspar. Out of the 72 granite quarries/outcrops studied in Peninsular Malaysia, 31 have been identified as “ideal” sources of feldspar conforming to the “preferred” feldspar specification of >18% Al₂O₃, >11% (Na₂O+K₂O) and <0.3% Fe₂O₃. A feldspar recovery efficiency exceeding 60% was achieved in this study. Despite the positive and encouraging indication that the extracted feldspar samples of different chemical composition are found to be suitable for the general purpose of making ceramic bodies and glaze, the chemical content of the feldspar, nevertheless, could be critical for the manufacture of specific end products. At 1250°C all extracted feldspar samples were fused; however, at the lower temperature of 1170°C feldspar samples extracted from some “Central Belt granites” remained unfused. The Eastern Province granites generally yielded feldspars which show better fusion characteristics i.e. (unblemished) than those extracted from the Main Range Province. A valuable by-product of the feldspar extraction process is silica sand.     

The Thermodynamic Structure of Arctic Coastal Fog Occurring During the Melt Season over East Greenland

An automated method to classify Arctic fog into distinct thermodynamic profiles using historic in-situ surface and upper-air observations is presented. This classification is applied to low-resolution Integrated Global Radiosonde Archive (IGRA) soundings and high-resolution Arctic Summer Cloud Ocean Study (ASCOS) soundings in low- and high-Arctic coastal and pack-ice environments. Results allow investigation of fog macrophysical properties and processes in coastal East Greenland during melt seasons 1980–2012. Integrated with fog observations from three synoptic weather stations, 422 IGRA soundings are classified into six fog thermodynamic types based on surface saturation ratio, type of temperature inversion, fog-top height relative to inversion-base height and stability using the virtual potential temperature gradient. Between 65–80% of fog observations occur with a low-level inversion, and statically neutral or unstable surface layers occur frequently. Thermodynamic classification is sensitive to the assigned dew-point depression threshold, but categorization is robust. Despite differences in the vertical resolution of radiosonde observations, IGRA and ASCOS soundings yield the same six fog classes, with fog-class distribution varying with latitude and environmental conditions. High-Arctic fog frequently resides within an elevated inversion layer, whereas low-Arctic fog is more often restricted to the mixed layer. Using supplementary time-lapse images, ASCOS microwave radiometer retrievals and airmass back-trajectories, we hypothesize that the thermodynamic classes represent different stages of advection fog formation, development, and dissipation, including stratus-base lowering and fog lifting. This automated extraction of thermodynamic boundary-layer and inversion structure can be applied to radiosonde observations worldwide to better evaluate fog conditions that affect transportation and lead to improvements in numerical models.     

Toward Improving Coastal-Fog Prediction (C-FOG)

Boundary-Layer Meteorology -     

Study of Stratus-Lowering Marine-Fog Events Observed During C-FOG

Boundary-Layer Meteorology - Two stratus-lowering marine fog events observed on 28 September and 4 October 2018 during the Coastal Fog (C-Fog) field campaign that took place offshore of eastern...     

Feature Extraction of Laser Scan Data Based on Geometric Properties

Terrestrial Laser Scanner (TLS) is an important device to provide three-dimensional geometric information with respect to known reference coordinates system. The data from TLS are often called point clouds due to their high density. They are unstructured and do not have any explicit information about the object, except 3D positional and intensity information to each point. Data segmentation and feature extraction are fundamental problems in the point cloud processing step. These are important prerequisites for object recognition and environment understanding. This paper describes a methodology to use the geometrical information of the scanned object, such as a normal vector to extract and segment object edges. The edge based segmentation technique will be studied and improved. The proposed method is programmed and used to extract different region boundaries for two real TLS data, and the quality of the results shows the effectiveness of the proposed algorithm.