4,593 research outputs found
Thermal transport in 2D and 3D nanowire networks
We report on thermal transport properties in 2 and 3 dimensions
interconnected nanowire networks (strings and nodes). The thermal conductivity
of these nanostructures decreases in increasing the distance of the nodes,
reaching ultra-low values. This effect is much more pronounced in 3D networks
due to increased porosity, surface to volume ratio and the enhanced
backscattering at 3D nodes compared to 2D nodes. We propose a model to estimate
the thermal resistance related to the 2D and 3D interconnections in order to
provide an analytic description of thermal conductivity of such nanowire
networks; the latter is in good agreement with Molecular Dynamic results
Thermal conductivity of strained silicon: molecular dynamics insight and kinetic theory approach
In this work, we investigated tensile and compression forces effect on the
thermal conductivity of silicon. We used equilibrium molecular dynamics
approach for the evaluation of thermal conductivity considering different
interatomic potentials. More specifically, we tested Stillinger-Weber, Tersoff,
Environment-Dependent Interatomic Potential and Modified Embedded Atom Method
potentials for the description of silicon atom motion under different strain
and temperature conditions. Additionally, we extracted phonon density of states
and dispersion curves from molecular dynamics simulations. These data were used
for direct calculations of thermal conductivity considering the kinetic theory
approach. Comparison of molecular dynamics and kinetic theory simulations
results as a function of strain and temperature allowed us to investigate the
different factors affecting the thermal conductivity of strained silicon
Impact of Screw and Edge Dislocation on the Thermal Conductivity of Nanowires and Bulk GaN
We report on thermal transport properties of wurtzite GaN in the presence of
dislocations, by using molecular dynamics simulations. A variety of isolated
dislocations in a nanowire configuration were analyzed and found to reduce
considerably the thermal conductivity while impacting its temperature
dependence in a different manner. We demonstrate that isolated screw
dislocations reduce the thermal conductivity by a factor of two, while the
influence of edge dislocations is less pronounced. The relative reduction of
thermal conductivity is correlated with the strain energy of each of the five
studied types of dislocations and the nature of the bonds around the
dislocation core. The temperature dependence of the thermal conductivity
follows a physical law described by a T variation in combination with an
exponent factor which depends on the material's nature, the type and the
structural characteristics of the dislocation's core. Furthermore, the impact
of the dislocations density on the thermal conductivity of bulk GaN is
examined. The variation and even the absolute values of the total thermal
conductivity as a function of the dislocation density is similar for both types
of dislocations. The thermal conductivity tensors along the parallel and
perpendicular directions to the dislocation lines are analyzed. The discrepancy
of the anisotropy of the thermal conductivity grows in increasing the density
of dislocations and it is more pronounced for the systems with edge
dislocations
Effect of dipolar interactions on cavity magnon-polaritons
The strong photon-magnon coupling between an electromagnetic cavity and two
yttrium iron garnet (YIG) spheres has been investigated in the context of a
strong mutual dipolar interaction between the spheres. A decrease in the
coupling strength between the YIG spheres and the electromagnetic cavity is
observed, along with an increase of the total magnetic losses, as the distance
between the spheres is decreased. A model of inhomogeneous broadening of the
ferromagnetic resonance linewidth, partly mitigated by the dipolar narrowing
effect, reproduces the reduction in the coupling strength observed
experimentally. These findings have important implications for the
understanding of strongly coupled photon-magnon system involving densely packed
magnetic objects, such as ferromagnetic nanowires arrays, in which the total
coupling strength with an electromagnetic cavity might become limited due to
mutual dipolar interactions.Comment: 5 pages, 5 figure
Solution of the radiative transfer equation in an absorbing and scattering Nd:YAG laser-induced plume
International audienc
First applications of the HIPSE event generator
The predictions of an event generator, HIPSE (Heavy-Ion Phase-Space Exploration), dedi- cated to the description of nuclear collisions in the intermediate energy range, are compared with experimental data collected by the INDRA and INDRA-ALADIN collaborations. Spe- cial emphasis is put on the kinematical characteristics of fragments and light particles at all impact parameters for the system Xe+Sn between 25 and 80 MeV/u
Data Services for Internet of Things
The factors involved in choosing between storing data repositories at locally-hosted infrastructures or at (remote) public clouds are well understood for many enterprise application domains. The proliferation of Internet-of-things (IoT) devices (including wearables) is now introducing a new class of applications, for which neither the research community nor the industry players offer guidelines on how to best handle the data. The goal of this research project is to characterize the most effective data architecture in terms of locally or remote hosted for a given IoT workload. Through this research, developers will become aware of various issues dealing with the designation of a host for a given data repository including security, efficiency, and accessibility concerns
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