120 research outputs found

    Transonic small disturbances equation applied to the solution of two-dimensional nonsteady flows

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    Transonic nonsteady flows are of large practical interest. Aeroelastic instability prediction, control figured vehicle techniques or rotary wings in forward flight are some examples justifying the effort undertaken to improve knowledge of these problems is described. The numerical solution of these problems under the potential flow hypothesis is described. The use of an alternating direction implicit scheme allows the efficient resolution of the two dimensional transonic small perturbations equation

    General Reference

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    This chapter stands out from the other chapters in this book. Whereas chapters 2-19 are arranged by subject, this one is a general reference resource guide. It includes almanacs, bibliographies, and guides to the literature, biographical sources (formerly a stand-alone chapter), general-purpose databases, and Internet search sites. Library search tools such as discovery layers are also described here. The Internet continues to have a huge impact on reference services. Some of that influence is via search interfaces like Oxford Reference or general databases like Academic Search Complete. It can also be seen with Internet sources that go beyond the library, like Google Search or Facebook. This chapter hopes to guide reference librarians by describing these changes

    Giant crystal-electric-field effect and complex magnetic behavior in single-crystalline CeRh3Si2

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    Single-crystalline CeRh3Si2 was investigated by means of x-ray diffraction, magnetic susceptibility, magnetization, electrical resistivity, and specific heat measurements carried out in wide temperature and magnetic field ranges. Moreover, the electronic structure of the compound was studied at room temperature by cerium core-level x-ray photoemission spectroscopy (XPS). The physical properties were analyzed in terms of crystalline electric field and compared with results of ab-initio band structure calculations performed within the density functional theory approach. The compound was found to crystallize in the orthorhombic unit cell of the ErRh3Si2 type (space group Imma -- No.74, Pearson symbol: oI24) with the lattice parameters: a = 7.1330(14) A, b = 9.7340(19) A, and c = 5.6040(11) A. Analysis of the magnetic and XPS data revealed the presence of well localized magnetic moments of trivalent cerium ions. All physical properties were found to be highly anisotropic over the whole temperature range studied, and influenced by exceptionally strong crystalline electric field with the overall splitting of the 4f1 ground multiplet exceeding 5700 K. Antiferromagnetic order of the cerium magnetic moments at TN = 4.70(1)K and their subsequent spin rearrangement at Tt = 4.48(1) K manifest themselves as distinct anomalies in the temperature characteristics of all investigated physical properties and exhibit complex evolution in an external magnetic field. A tentative magnetic B-T phase diagram, constructed for B parallel to the b-axis being the easy magnetization direction, shows very complex magnetic behavior of CeRh3Si2, similar to that recently reported for an isostructural compound CeIr3Si2. The electronic band structure calculations corroborated the antiferromagnetic ordering of the cerium magnetic moments and well reproduced the experimental XPS valence band spectrum.Comment: 32 pages, 12 figures, to appear in Physical Review

    Lessons learned - resolving the enigma of genetic factors in IBS

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    IBS is the most prevalent functional gastrointestinal disorder and phenotypically characterized by chronic abdominal discomfort, pain and altered defecation patterns. The pathophysiology of IBS is multifactorial, albeit with a substantial genetic component. To date, studies using various methodologies, ranging from family and twin studies to candidate gene approaches and genome-wide association studies, have identified several genetic variants in the context of IBS. Yet, despite enlarged sample sizes, increased statistical power and meta-analyses in the past 7 years, positive associations are still scarce and/or have not been reproduced. In addition, epigenetic and pharmacogenetic approaches remain in their infancy. A major hurdle is the lack of large homogenized case-control cohorts recruited according to standardized and harmonized criteria. The COST Action BM1106 GENIEUR (GENes in Irritable Bowel Syndrome Research Network EURope) has been established to address these obstacles. In this Review, the (epi)genetic working group of GENIEUR reports on the current state-of-the-art in the field, highlights fundamental flaws and pitfalls in current IBS (epi) genetic research and provides a vision on how to address and improve (epi) genetic approaches in this complex disorder in the future.This is the peer reviewed version of the paper: Gazouli, M., Wouters, M. M., Kapur-Pojskić, L., Bengtson, M.-B., Friedman, E., Nikčević, G., Demetriou, C. A., Mulak, A., Santos, J., & Niesler, B. (2016). Lessons learned—Resolving the enigma of genetic factors in IBS. Nature Reviews Gastroenterology & Hepatology, 13(2), 77–87. [https://doi.org/10.1038/nrgastro.2015.206]Published version: [https://imagine.imgge.bg.ac.rs/handle/123456789/977

    Structures of Thermodynamic Functions for S-Paired Fermi Systems in Parametric Equations Approach

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    The general method of investigation of S-paired Fermi systems is given and discussed as generalization of parametric equation for the energy gap. The additional parametric equations for thermodynamic potential and heat capacity are obtained as functions of introduced parameters. The detailed calculations are given for a few exemplary chosen magnetic fields and superflows. Moreover, we consider the case of so-called statistical spin liquid, which constitutes non-BCS model

    Discontinuous Phase Transitions in S-Paired Fermi Systems

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    The most general S-paired systems of fermions for which a gap equation can be separated according to the specific redefined variables, are considered. Moreover, a solution of this gap equation (gap energy) is obtained in a parametric form. It allows us to investigate thermodynamic properties of such systems i.e. the thermodynamic potential, entropy, heat capacity and critical magnetic induction. We show also that the heat capacity difference between the superconducting and the normal phase is entirely determined by the order parameter. The obtained results reveal possibilities of discontinuous phase transition to the normal state and moreover, the theorem on existence of such transitions is formulated and proved. The condition for the BCS-type energy gap is given, which additionally classifies properties of the heat capacity of S-paired phase by virtue of the shape of the energy gap. In order to illustrate the developed formalism, the numerical results for the so-called statistical spin liquids and application of the established methods to the experimental data conversion, are presented and discussed
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