1,520 research outputs found
Effects of silicon dioxide nanoparticles on biological and physiological characteristics of Medicago sativa L. nothosubsp. varia (Martyn) in natural agroclimatic conditions of the subtaiga zone in Western Siberia
Saturation in Liquid/Gas Coalescence
The problem was to construct a mathematical model for a liquid/gas coalescer, in order that the model could be analyzed to find combinations of parameters that would minimize the effects of saturation.
The team has developed three complementary models, each with different strengths and weaknesses so that, depending on the information desired, one model may be more useful than another. The three models are:
1. A continuum model giving a macroscopic description of the filter. The governing equations are derived from first-principle consider- ations of conservation of mass and momentum. Constitutive relations for this model are derived by considering the processes going on in the filter at a microscopic level.
2. A stochastic model based on a Markov Decision Process. Each droplet is modelled as a single entity that can merge or move stochastically. This leads to a Markov simulation of the filter and the computation of average quantities.
3. A Lattice-Boltzmann model. The droplets are modelled to interact with each other and with the filter, using a Boltzmann distribution for their speed. This simulates the hydrodynamic behaviour of the droplet inside the filter
Linear and nonlinear optical properties of trigonal borate crystals K7MIn2-xYbx(B5O10)3 (M = Ca, Sr, Ba; x=0…2) with isolated B5O10 units
Noncentrosymmetric borates K7MIn2−xYbx(B5O10)3 (M = Ca, Sr, Ba; x = 0…2) were synthesized by the solid state reaction and the crystals were successfully grown by the top seeded solution growth method using the K2O-B2O3-MF2 flux. According to Rietveld refinement, the crystal structure belongs to the noncentrosymmetric R32 space group. Also, the octahedrally coordinated In atoms are located at wide ranges ∼8 Å which may be promising for phosphor and laser applications. Samples with ytterbium show a characteristic emission band in the range of 950–1050 nm related to the 2F5/2 → 2F7/2 transition of Yb3+ ions that is commonly used for laser generation. IR, Raman and absorption spectra were obtained for the samples as well. The short cut edge of UV absorption, SHG intensity comparable with KDP and low concentration quenching of luminescence suggest that the K7MIn2−xYbx(B5O10)3 borates are promising self-frequency doubling materials
Fast flowing populations are not well mixed
In evolutionary dynamics, well-mixed populations are almost always associated
with all-to-all interactions; mathematical models are based on complete graphs.
In most cases, these models do not predict fixation probabilities in groups of
individuals mixed by flows. We propose an analytical description in the
fast-flow limit. This approach is valid for processes with global and local
selection, and accurately predicts the suppression of selection as competition
becomes more local. It provides a modelling tool for biological or social
systems with individuals in motion.Comment: 19 pages, 8 figure
Defect-Free Carbon Nanotube Coils
Carbon nanotubes are promising building blocks for various nanoelectronic
components. A highly desirable geometry for such applications is a coil.
However, coiled nanotube structures reported so far were inherently defective
or had no free ends accessible for contacting. Here we demonstrate the
spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils
of up to more than 70 turns with identical diameter and chirality, and free
ends. We characterize the structure, formation mechanism, and electrical
properties of these coils by different microscopies, molecular dynamics
simulations, Raman spectroscopy, and electrical and magnetic measurements. The
coils are highly conductive, as expected for defect-free carbon nanotubes, but
adjacent nanotube segments in the coil are more highly coupled than in regular
bundles of single-wall carbon nanotubes, owing to their perfect crystal
momentum matching, which enables tunneling between the turns. Although this
behavior does not yet enable the performance of these nanotube coils as
inductive devices, it does point a clear path for their realization. Hence,
this study represents a major step toward the production of many different
nanotube coil devices, including inductors, electromagnets, transformers, and
dynamos
Comparison of aerodynamic models for Vertical Axis Wind Turbines
Multi-megawatt Vertical Axis Wind Turbines (VAWTs) are experiencing an increased interest for floating offshore applications. However, VAWT development is hindered by the lack of fast, accurate and validated simulation models. This work compares six different numerical models for VAWTS: a multiple streamtube model, a double-multiple streamtube model, the actuator cylinder model, a 2D potential flow panel model, a 3D unsteady lifting line model, and a 2D conformal mapping unsteady vortex model. The comparison covers rotor configurations with two NACA0015 blades, for several tip speed ratios, rotor solidity and fixed pitch angle, included heavily loaded rotors, in inviscid flow. The results show that the streamtube models are inaccurate, and that correct predictions of rotor power and rotor thrust are an effect of error cancellation which only occurs at specific configurations. The other four models, which explicitly model the wake as a system of vorticity, show mostly differences due to the instantaneous or time averaged formulation of the loading and flow, for which further research is needed.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin
Study of the UV Irradiation and Nalidicsic Acid Effect on the RecA-protein Induction in <i>Francisella tularensis</i> 15/10 Cells
Studied is the UV irradiation and nalidicsic acid effect on the RecA-protein synthesis in Francisella tularensis 15/10 cells. Obtained is the specific murine serum to the recombinant RecA-protein. The results of immunoblotting with this specific serum demonstrate that the amount of RecA-protein in Francisella tularensis 15/10 cells is not increased after the exposure to these damaging factors
Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method
This paper discusses hadron energy reconstruction for the ATLAS barrel
prototype combined calorimeter (consisting of a lead-liquid argon
electromagnetic part and an iron-scintillator hadronic part) in the framework
of the non-parametrical method. The non-parametrical method utilizes only the
known ratios and the electron calibration constants and does not require
the determination of any parameters by a minimization technique. Thus, this
technique lends itself to an easy use in a first level trigger. The
reconstructed mean values of the hadron energies are within of the
true values and the fractional energy resolution is . The value of the ratio
obtained for the electromagnetic compartment of the combined calorimeter is
and agrees with the prediction that for this
electromagnetic calorimeter. Results of a study of the longitudinal hadronic
shower development are also presented. The data have been taken in the H8 beam
line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM
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