Geochemical characteristics of Yamadağı volcanics in central east Anatolia: an example from collision-zone volcanism

Neogene Yamadağı volcanic rocks consist of basaltic trachyandesite, trachyandesite, andesite, and dacite. The major- and trace-element chemistry indicates that the lavas are dominantly calc-alkaline and mildly alkaline in character, sodic in nature, and intermediate to acidic in composition. REE and trace-element patterns of volcanic rocks are similar to those typical of within plate magmatics. Volcanic rocks have low ⁸⁷Sr/⁸⁶Sr (0.70389–0.70633) and high ¹⁴³Nd/¹⁴⁴Nd ratios (0.51267–0.51276) and mostly plot within the mantle array of the isotope ratio diagram. The linear correlations among ⁸⁷Sr/⁸⁶Sr−¹⁴³Nd/¹⁴⁴Nd, SiO₂−⁸⁷Sr/⁸⁶Sr and SiO₂−¹⁴³Nd/¹⁴⁴Nd isotope ratios in the volcanics suggest that fractional crystallization combined with minor assimilation was an important process within the collision zone.     

Ground Water Replenishment with Reclaimed Water in the City of Los Angeles

A two-year pilot study involving the recharge of a ground water basin with reclaimed water was completed in the city of Los Angeles. The city's Department of Water and Power is planning to initiate several ground water recharge projects using reclaimed water in the near future. One such project is the Headworks Recharge Project, the focus of this paper, Approximately 1 cfs of the Los Angeles (LA) River water comprised of 70% tertiary treated reclaimed water was recharged on a two-day wet and five-day dry cycle. The recharge water was then extracted from the basin approximately 1000 feet downgradient. Results showed greater than 4-log removal of coliform bacteria, up to 87% reduction in TOC, and compliance of the product water with federal and state drinking water standards. Model simulation showed after 15 years of recharging 3000 acre-feet per year of the LA River water and extracting about 10,000 acre-feet from the basin, the product water would contain from 5% to 15% reclaimed water. This is well below the maximum allowable limit of 20% stipulated by the California regulation.     

Variation of the elastic constants of tourmaline with chemical composition

Elastic wave velocities and lattice parameters of five tourmaline specimens with different chemical compositions have been measured. The piezoelectric effects on the elastic constants have been found to be small and can be neglected. Variations of the elastic wave velocities and elastic constants of the different tourmaline specimens indicate that: (i) partial substitution of Al by Fe in the structure decreases the shear wave velocities, (ii) replacement of Na by Ca increases the resistance of the structure against shear deformation involving C ₆₆, (iii) replacement of Al by Mg seems to decrease the resistance of the structure against longitudinal deformation involving C ₃₃. Elastic constants C ₁₁, C ₃₃, C ₄₄ and C ₆₆ of the different tourmaline specimens used in this study differ individually by 1.7 percent to 6.7 percent, indicating that the large differences (up to 21%) between the values reported by previous authors cannot be explained in terms of the chemical composition alone.     

Plant functional types in Lake Nubia in relation to physicogeographic factors

The shoreline vegetation of Lake Nubia in Sudan was studied by means of morphological characteristics and functional traits of plants established-phase as published in literature reviews. The 57 species recorded in 83 sampling sites were classified according to 15 morphological traits into six Plant Functional Types (PFTs), using Two Way Indicator Species Analysis (TWINSPAN). Principal component analysis (PCA) was used to evaluate the homogeneity of these groups in terms of their traits. The resulting PFTs were related to the physicogeographical variables measured (soil texture, soil moisture, soil thickness and elevation) using canonical correspondence analysis (CCA). The ratios in occurrences of the functional types were calculated per each moisture segment, and can be used as an indicator of the shoreline dynamics.     

Weathering and biokarst development on marine terraces,northwest Morocco

Weathering features are described from an arid coastal area in northern Morocco which are indicative of invasive chasmolithic and endolithic microbial communities. Active weathering of marine terraces and karst development is associated with endolithic and epilithic algae responsible for boring, disintegration of matrix and mineral fabrics, solution and biomineralization that undermines the marine carbonate platform. Evidence of a range of biological weathering agents remains preserved, speci?cally calci?ed ?laments and sporangial material. An abundance of ?laments and spores representative of a consortium of algae, fungi, cyanobacteria and lichens is associated with the most denuded outcrops. The array of microbes contributes to the formation of the stromatolites to depths of 0·5 m within the limestone substrate. The preservation of stromatolites is supported by calci?cation of spores and ?laments, with trapping and binding of carbonate held in suspension by vadose waters. The pervasive weathering on this sector of coastline has important practical implications for coastal planning and development authorities in Morocco. Copyright © 2003 John Wiley & Sons, Ltd.     

Automatic Surface Reconstruction Based on the Fusion of Fuzzy Logic and Robust Estimation Techniques

Automatic surface reconstruction by means of digital image matching essentially involves computation in both image and object spaces. In image space, image matching is performed according to certain radiometric and geometric similarity criteria for conjugate point determination. The matching operations may therefore be regarded as decision–making processes. In practice, however, the similarity criteria for conjugate point determination demonstrate non–deterministic behaviour. Thus, the nature of these decision–making processes is more compatible with fuzzy reasoning concepts. In object space, on the other hand, surface reconstruction procedures, which operate on the basis of previously determined conjugate points, are essentially deterministic in nature and hence demand rigorous geometric modelling. In this paper, a new approach for automatic surface modelling is proposed, based on two different mathematical treatments: a fuzzy logic reasoning method for the conjugate point determination in image space; and a robust finite elements approach for the surface modelling in object space. Tests carried out on real data demonstrate the high potential of the strategy proposed.     

卫星反演太阳紫外辐射数据产品在东疆黑戈壁区域的适用性验证

论文利用2017年东疆哈密地区红柳河黑戈壁地面高精度紫外辐射实测数据与美国NASA Langely研究中心大气科学数据中心提供的CERES_SYN1 deg_Ed4A产品数据,对卫星反演的紫外辐射A、B波段(UVA和UVB)数据在该地区的适用性进行了对比验证。结果表明：① 在日尺度上,该地区地面实测紫外辐射UVA和UVB与卫星反演数据之间的相关系数达0.9以上,其中在全天空情况下UVA平均偏差为1.15 W·m ^-2、UVB 平均偏差为0.03 W·m ^-2,晴天条件下UVA和UVB的平均偏差分别为0.93 W·m ^-2和0.03 W·m ^-2;② 在季节尺度上,实测和卫星反演UVA和UVB的偏差夏季最大,分别为2.04 W·m ^-2和0.05 W·m ^-2,春冬两季次之,秋季最小;③ 红柳河地区在春夏两季受到气溶胶光学厚度(AOD)影响较大,呈现显著负相关;④ 云量越大,紫外辐射削弱程度越大,在多云条件下地面实测与卫星反演UVA与UVB偏差最大,分别为1.73 W·m ^-2和0.05 W·m ^-2。     

Ion acoustic double layers in the presence of positrons beam and q-nonextensive velocity distributed electrons

Linear and nonlinear studies are presented for an electron-ion plasma system which is being energized with an external beam of positrons. The electrons are assumed to follow the q-nonextensive velocity distribution. The growth rates of instability due to positron beam are analyzed numerically. The compressive and rarefactive double layers are studied in the system and it is found that by varying the entropic index parameter q, positron beam speed v _po and concentration of positrons p, the dynamics of nonlinear profile is changing quite effectively. The relevance of the work regarding to astrophysical space plasma is pointed out.