3,985 research outputs found
Accuracy Improvement of Real-Time Load-Pull Measurements
This paper describes a new procedure aimed to improve the effectiveness of real-time load-pull calibration. Loadpull measurement accuracy is strongly affected by calibration residual uncertainty. The novel methodology reduces this uncertainty contribution by means of error terms optimization. The proposed method has been tested with simulations and applied to actual measurement data. Considerable improvements have been achieve
Transport efficiency of metachronal waves in 3d cilia arrays immersed in a two-phase flow
The present work reports the formation and the characterization of
antipleptic and symplectic metachronal waves in 3D cilia arrays immersed in a
two-fluid environment, with a viscosity ratio of 20. A coupled
lattice-Boltzmann-Immersed-Boundary solver is used. The periciliary layer is
confined between the epithelial surface and the mucus. Its thickness is chosen
such that the tips of the cilia can penetrate the mucus. A purely
hydrodynamical feedback of the fluid is taken into account and a coupling
parameter is introduced allowing the tuning of both the direction of
the wave propagation, and the strength of the fluid feedback. A comparative
study of both antipleptic and symplectic waves, mapping a cilia inter-spacing
ranging from 1.67 up to 5 cilia length, is performed by imposing the
metachrony. Antipleptic waves are found to systematically outperform sympletic
waves. They are shown to be more efficient for transporting and mixing the
fluids, while spending less energy than symplectic, random, or synchronized
motions
Social Network Capital and Academic Careers
Social Network Capital and Academic Careers: The Case of a College of Agriculture ABSTRACT The relationship between economic performance and various forms of capital anchors a significant portion of mainstream economic theory and applied economics. Human, physical and financial capital represent important factors in the production of goods and services. The label “capital” implies characteristics such as investment, accumulation, maintenance, depreciation, and transfer. Recently, social capital or social network capital (SNC) has received increased scholarly attention in the literature of sociology, business, and economics. Limited analysis, however, has been directed at the role of SNC in the academy. We hypothesize that academic success at the professorial level is determined by the stock of human (HC) and SNC and the value flows emerging from these stocks. We view SNC as a complement to HC, increasing the productivity of HC while holding all other factors constant. An analysis of SNC’s importance to academic career success should interest the academy as well as other large organizations (i.e. research laboratories, government agencies) with similar structures and incentive systems.Social capital, academic networks, human capital, Institutional and Behavioral Economics, Labor and Human Capital, Teaching/Communication/Extension/Profession,
The accessibility produced by a local transit network
This research sets some accessibility indicators referred to a road intercity transit system for commuting users within a district. The aim is to make available some accessibility measure tools by which evaluate the effects, on this performance, of the actions designed for a local transit network
Composite lacunary polynomials and the proof of a conjecture of Schinzel
Let be a fixed non-constant complex polynomial. It was conjectured by
Schinzel that if has boundedly many terms, then h(x)\in \C[x] must
also have boundedly many terms. Solving an older conjecture raised by R\'enyi
and by Erd\"os, Schinzel had proved this in the special cases ;
however that method does not extend to the general case. Here we prove the full
Schinzel's conjecture (actually in sharper form) by a completely different
method. Simultaneously we establish an "algorithmic" parametric description of
the general decomposition , where is a polynomial with a
given number of terms and are arbitrary polynomials. As a corollary, this
implies for instance that a polynomial with terms and given coefficients is
non-trivially decomposable if and only if the degree-vector lies in the union
of certain finitely many subgroups of .Comment: 9 page
An immersed boundary-lattice Boltzmann method for single- and multi-component fluid flows
International audienceThe paper presents a numerical method to simulate single-and multi-component fluid flows around moving/deformable solid boundaries, based on the coupling of Immersed Boundary (IB) and Lattice Boltzmann (LB) methods. The fluid domain is simulated with LB method using the single relaxation time BGK model, in which an interparticle potential model is applied for multi-component fluid flows. The IB-related force is directly calculated with the interpolated definition of the fluid macroscopic velocity on the Lagrangian points that define the immersed solid boundary. The present IB-LB method can better ensure the no-slip solid boundary condition, thanks to an improved spreading operator. The proposed method is validated through several 2D/3D single-and multi-component fluid test cases with a particular emphasis on wetting conditions on solid wall. Finally, a 3D two-fluid application case is given to show the feasibility of modeling the fluid transport via a cluster of beating cilia
Wideband digital phase comparator for high current shunts
A wideband phase comparator for precise measurements of phase difference of
high current shunts has been developed at INRIM. The two-input digital phase
detector is realized with a precision wideband digitizer connected through a
pair of symmetric active guarded transformers to the outputs of the shunts
under comparison. Data are first acquired asynchronously, and then transferred
from on-board memory to host memory. Because of the large amount of data
collected the filtering process and the analysis algorithms are performed
outside the acquisition routine. Most of the systematic errors can be
compensated by a proper inversion procedure.
The system is suitable for comparing shunts in a wide range of currents, from
several hundred of milliampere up to 100 A, and frequencies ranging between 500
Hz and 100 kHz. Expanded uncertainty (k=2) less than 0.05 mrad, for frequency
up to 100 kHz, is obtained in the measurement of the phase difference of a
group of 10 A shunts, provided by some European NMIs, using a digitizer with
sampling frequency up to 1 MHz. An enhanced version of the phase comparator
employs a new digital phase detector with higher sampling frequency and
vertical resolution. This permits to decrease the contribution to the
uncertainty budget of the phase detector of a factor two from 20 kHz to 100
kHz. Theories and experiments show that the phase difference between two high
precision wideband digitizers, coupled as phase detector, depends on multiple
factors derived from both analog and digital imprint of each sampling system.Comment: 20 pages, 9 figure
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