353,868 research outputs found
On the structure and origin of pressure fluctuations in wall turbulence: predictions based on the resolvent analysis
No full textWe generate predictions for the fluctuating pressure field in turbulent pipe flow by re-formulating the resolvent analysis of McKeon & Sharma (2010) in terms of the so-called primitive variables. Under this analysis, the nonlinear convective terms in the Fourier-transformed Navier-Stokes equations are treated as a forcing that is mapped to a velocity and pressure response by the resolvent of the linearized Navier-Stokes operator. At each wavenumber-frequency combination, the turbulent velocity and pressure field are represented by the most-amplified (rank-1) response modes, identified via a singular value decomposition of the resolvent. We show that these rank-1 response modes reconcile many of the key relationships between the velocity field, coherent structure (i.e., hairpin vortices), and the high-amplitude wall-pressure events observed in previous experiment and DNS. A Green’s function representation shows that the pressure fields obtained under this analysis correspond primarily to the fast pressure contribution arising from the linear interaction between the mean shear and the turbulent wall-normal velocity. Recovering the slow pressure requires an explicit treatment of the nonlinear interactions between the Fourier response modes. By considering the velocity and pressure fields associated with the triadically-consistent mode combination studied by Sharma & McKeon (2013), we identify the possibility of an apparent amplitude modulation effect in the pressure field, similar to that observed for the streamwise velocity field. However, unlike the streamwise velocity, for which the large scales of the flow are in phase with the envelope of the small-scale activity close to the wall, we expect there to be a ?/2 phase difference between the large scale wall-pressure and the envelope of the small-scale activity. Finally, we generate spectral predictions based on a rank-1 model assuming broadband forcing across all wavenumber-frequency combinations. Despite the significant simplifying assumptions, this approach reproduces trends observed in previous DNS for the wavenumber spectra of velocity and pressure, and for the scale-dependence of wall-pressure propagation speed
Dataset for Modular transmission line probes for microfluidic nuclear magnetic resonance spectroscopy and imaging
No full textDataset supports: Sharma, M. & Utz, M. (2019). Modular transmission line probes for microfluidic nuclear magnetic resonance spectroscopy and imaging. Journal of Magnetic Resonance, 303, 75-81.</span
Resistência de cultivares de trigo ao nematóide formador de galhas Meloidogyne javanica.
No full textA cultura do trigo (Triticum aestivum L.) é uma cultura importante para a região do Sul do Brasil, mostrando boa adaptação para a região dos Cerrados e é cultivado em pequenas áreas do Estado de Goiás, Bahia, Minas Gerais, Mato Grosso do Sul e Distrito Federal. As informações sobre perdas causadas por nematoides das regiões de cerrados são deficientes. SHARMA (1979) pela primeira vez registrou ocorrência de nematoides fitoparasitos na cultura de trigo nos Cerrados do Distrito Federal. O nematoide formador de galhas, Meloidogyne javanica Treub,1885) Chitwood,1949, foi encontrado causando sérios danos à cultura do trigo. Posteriormente, o autor verificou a patogenicidade do referido nemat6ide em condições de casa-de-vegetação e simultaneamente foram feitas avaliações de resistência de 21 cultivares de trigo ao mesmo nematoide
Opposition control within the resolvent analysis framework
No full textThis paper extends the resolvent analysis of McKeon & Sharma (2010) to consider flow control techniques that employ linear control laws, focusing on opposition control (Choi et al. 1994) as an example. Under this formulation, the velocity field for turbulent pipe flow is decomposed into a series of highly amplified (rank-1) response modes, identified from a gain analysis of the Fourier-transformed Navier-Stokes equations. These rank-1 velocity responses represent propagating structures of given streamwise/spanwise wavelength and temporal frequency, whose wall-normal footprint depends on the phase speed of the mode. Opposition control, introduced via the boundary condition on wall-normal velocity, affects the amplification characteristics (and wall-normal structure) of these response modes; a decrease in gain indicates mode suppression, which leads to a decrease in the drag contribution from that mode. With basic assumptions, this rank-1 model reproduces trends observed in previous DNS and LES, without requiring high-performance computing facilities. Further, a wavenumber-frequency breakdown of control explains the deterioration of opposition control performance with increasing sensor elevation and Reynolds number. It is shown that slower-moving modes localized near the wall (i.e. attached modes) are suppressed by opposition control. Faster-moving detached modes, which are more energetic at higher Reynolds number and more likely to be detected by sensors far from the wall, are further amplified. These faster-moving modes require a phase lag between sensor and actuator velocity for suppression. Thus, the effectiveness of opposition control is determined by a trade-off between the modes detected by the sensor. However, it may be possible to develop control strategies optimized for individual modes. A brief exploration of such mode-optimized control suggests the potential for significant performance improvement
Dataset supporting the paper "Stabilisation of FeCoNiCuPt high-entropy alloy nanoparticles by surface capping"
No full textThis dataset supports the paper 'Stabilisation of FeCoNiCuPt high-entropy alloy nanoparticles by surface capping' by Sharma, A., & Hector, A. L., forthcoming in the Faraday Discussions.
Dataset contains the research data including XRD (for X-ray diffraction data)
EDS (for Energy-dispersive X-ray spectroscopy data)
TEM (for Transmission Electron Microscopy data)
DLS (for hydrodynamic diameter data reports from dynamic light scattering)
and Zeta potential reports (for zeta potential reports from dynamic light scattering), which is designated for publication in Faraday discussions journal.
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Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Polish Airforce and Praharshit Sharma Work deserves Nobel Prize for Optimizing Genetic Coding of DNA information transfer
No full textI, Praharshit Sharma, received an Official Email from Polish Airforce Institute of Aviation Medicine, Warszawa, as we had jointly "Optimized" using Hardware-Memory minimization constraints: the Universal Genetic Code, using Finite Automaton approach for (linear, nuclear) nt-cDNA and using Combinatorics for (circular, mitochondrial) mt-cDNA, essentially inferring "e" (Napier's constant= 2.71...) based-Encoding.
You can Directly Call ME ( PRAHARSHIT SHARMA) so as to seek any further Clarifications and Nominate me (INDIAN Bioinformatician) for the NOBEL prize at Below Number
+91 7 416 03 2787https://www.linkedin.com/in/praharshitsharm
Overview of Super-Compactness on Topological Spaces
No full textSuper compactness is a property of topological spaces that generalizes the concept of compactness. A topological space is super compact if every open cover has a finite sub-cover that is "super-refining," meaning that it can be further refined to an open cover with a smaller mesh. Super compactness was first introduced by E. Michael in his paper "A note on paracompact spaces" in 1951. In this paper, Michael introduced the concept of a super-refining open cover and proved that a space is super compact if and only if it is paracompact and has the property that every open cover has a super-refining open cover
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
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