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In this paper, equi-conjugate pairs of curves in a hypersurfaceW
n(gij,Tk) are defined and the Chebyshev nets of the first kind, the second kind and the geodesic nets which are formed by the tangent vector fields of these pairs of curves are investigated. 相似文献
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A new numerical approach has been developed for predicting the interwell tracer flow behaviour in heterogeneous porous media typical of water and oil reservoirs. This approach uses a mixed finite-element method with triangular elements to predict pressure and velocity fields, and a novel random walk model to simulate the tracer transport through the reservoir, and to perdict the concentration response at the production well. The mixed finite-element method solves the pressure and velocity simultaneously imposing suitable boundary conditions for both pressure and velocity, which allows the solution of the tracer velocity to be more accurate and to conserve mass more precisely than a standard finite-element method. The random walk model can reflect the tracer flow behaviour directly by tracking the movement of particles representing the tracer input volume.The technique has been validated by comparing the predicted results with analytical solutions of tracer concentration response for a homogeneous five-spot pattern, and with published experimentally observed tracer fronts at breakthrough for homogeneous and three heterogeneous cases of five-spot pattern. Good agreement has been achieved for all cases. The model presented in this paper is general, and can therefore be applied to drive patterns other than the five-spot pattern, and for different types of heterogeneities; it can also include effects such as longitudinal and transverse dispersion and adsorption. 相似文献
26.
The present paper deals with the study of approximation by complex Stancu type generalization of Jakimovski–Leviatan type operators on a parabolic domain subset of complex plane by using the methods of Dressel et al. (Pacific J Math 13(4):1171–1180, 1963). 相似文献
27.
Demet Sezgin Mansuroğlu Hakan Arslan Don VanDerveer Gün Binzet 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):3221-3230
A series of new N-(2,2-diphenylacetyl)-N ′-substituted thiourea derivatives (1–9) have been prepared and characterized by elemental analyses, IR and 1H NMR spectroscopy. N-(2,2-diphenylacetyl)-N ′-(4-chlorophenyl)-thiourea was also characterized by a single crystal X-ray diffraction study. The compound crystallizes in the monoclinic space group P21/c with Z = 4 and a = 9.6551(19) Å, b = 20.060(4) Å, c = 9.894(2) Å, β = 104.29(3)°. The molecular conformation of the compound is stabilized by an intramolecular (N1-H1···O1) hydrogen bond that forms a pseudo-six-membered ring. 相似文献
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In this paper, we study some properties of the Chebyshev nets and geodesic nets in the hypersurfaces of the generalised recurrent
and birecurrent Weyl spaces.
Received 4. Dezember 1998. 相似文献
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Hasan Sezer Sezgin Fazilet Zumrut Biber Muftuler Cigdem Ichedef Ayfer Yurt Kilcar Serap Teksoz Perihan Unak Coskun Harmansah 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(2):291-297
Penetrant technique is a sensitive non-destructive testing (NDT) method for detecting and locating the presence of cracks in sample surface. Today, NDT is used in a wide range of industries including aerospace, biotechnology, defence, marine, oil–gas and energy plants. This work focuses on potential use of radiolabeled ZnS coated CdTe quantum dots (QDots) as a penetrant for liquid penetrant testing. The synthesized QDots as a precursor were tested for surface defects detection in welded joints. The experimental results show the highest activities were found in defects on the sample surface. These finding are consistent with the sample NDT inspection test report. 相似文献
30.
Yasin Arslan Emrah YildirimMehrdad Gholami Sezgin Bakirdere 《Trends in analytical chemistry : TRAC》2011,30(4):569-585
Speciation studies are much more important than total element determination because toxicity of many elements depends on their chemical forms. Nobody can claim that a foodstuff is very dangerous to eat by determining total arsenic due to the possibility that the arsenic could be present in non-toxic forms. Hence, speciation studies are crucial in any matrix relevant to human beings.Trace-element speciation requires sufficiently sensitive procedures to monitor each species at trace levels. One way to increase the sensitivity for elements forming volatile species is coupling high-performance liquid chromatography (HPLC) with chemical-vapor generation (CVG). This review aims to highlight not only development of HPLC-CVG techniques for ultratrace-elemental speciation in a variety of matrices but also their application. In addition, we discuss the advantages and the disadvantages of these techniques. 相似文献