scholarly journals On the role of micro-inertia in enriched continuum mechanics

2017 ◽  
Vol 473 (2198) ◽  
pp. 20160722 ◽  
Author(s):  
Angela Madeo ◽  
Patrizio Neff ◽  
Elias C. Aifantis ◽  
Gabriele Barbagallo ◽  
Marco Valerio d’Agostino
Keyword(s):  
Band Gap ◽  
Dynamic Behaviour ◽  
Internal Variable ◽  
Local Effects ◽  
Variable Model ◽  
Complex Behaviour ◽  
Transverse Optic ◽  
Non Local ◽  
New Feature

In this paper, the role of gradient micro-inertia terms η ¯ ∥   ∇ u , t ∥ 2 and free micro-inertia terms η ∥ P , t ∥ 2 is investigated to unveil their respective effects on the dynamic behaviour of band-gap metamaterials. We show that the term η ¯ ∥   ∇ u , t ∥ 2 alone is only able to disclose relatively simplified dispersive behaviour. On the other hand, the term η ∥ P , t ∥ 2 alone describes the full complex behaviour of band-gap metamaterials. A suitable mixing of the two micro-inertia terms allows us to describe a new feature of the relaxed-micromorphic model, i.e. the description of a second band-gap occurring for higher frequencies. We also show that a split of the gradient micro-inertia η ¯ ∥   ∇ u , t ∥ 2 , in the sense of Cartan–Lie decomposition of matrices, allows us to flatten separately the longitudinal and transverse optic branches, thus giving us the possibility of a second band-gap. Finally, we investigate the effect of the gradient inertia η ¯ ∥   ∇ u , t ∥ 2 on more classical enriched models such as the Mindlin–Eringen and the internal variable ones. We find that the addition of such a gradient micro-inertia allows for the onset of one band-gap in the Mindlin–Eringen model and three band-gaps in the internal variable model. In this last case, however, non-local effects cannot be accounted for, which is a too drastic simplification for most metamaterials. We conclude that, even when adding gradient micro-inertia terms, the relaxed micromorphic model remains the best performing one, among the considered enriched models, for the description of non-local band-gap metamaterials.

One-point turbulence structure tensors

2001 ◽  
Vol 428 ◽  
pp. 213-248 ◽  
Author(s):  
S. C. KASSINOS ◽  
W. C. REYNOLDS ◽  
M. M. ROGERS
Keyword(s):  
Turbulence Structure ◽  
Turbulence Statistics ◽  
Local Effects ◽  
Statistical Measures ◽  
Non Local ◽  
The One ◽  
Rate Correlation ◽  
Systematic Framework ◽  
Structure Tensors

The dynamics of the evolution of turbulence statistics depend on the structure of the turbulence. For example, wavenumber anisotropy in homogeneous turbulence is known to affect both the interaction between large and small scales (Kida & Hunt 1989), and the non-local effects of the pressure–strain-rate correlation in the one-point Reynolds stress equations (Reynolds 1989; Cambon et al. 1992). Good quantitative measures of turbulence structure are easy to construct using two-point or spectral data, but one-point measures are needed for the Reynolds-averaged modelling of engineering flows. Here we introduce a systematic framework for exploring the role of turbulence structure in the evolution of one-point turbulence statistics. Five one-point statistical measures of the energy-containing turbulence structure are introduced and used with direct numerical simulations to analyse the role of turbulence structure in several cases of homogeneous and inhomogeneous turbulence undergoing diverse modes of mean deformation. The one-point structure tensors are found to be useful descriptors of turbulence structure, and lead to a deeper understanding of some rather surprising observations from DNS and experiments.

scholarly journals The role of water in host-guest interaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valerio Rizzi ◽  
Luigi Bonati ◽  
Narjes Ansari ◽  
Michele Parrinello
Keyword(s):  
Ligand Binding ◽  
Degrees Of Freedom ◽  
Enhanced Sampling ◽  
Free Energies ◽  
Collective Variables ◽  
Complex Behaviour ◽  
Field Quality ◽  
Non Local ◽  
Binding Free Energies

AbstractOne of the main applications of atomistic computer simulations is the calculation of ligand binding free energies. The accuracy of these calculations depends on the force field quality and on the thoroughness of configuration sampling. Sampling is an obstacle in simulations due to the frequent appearance of kinetic bottlenecks in the free energy landscape. Very often this difficulty is circumvented by enhanced sampling techniques. Typically, these techniques depend on the introduction of appropriate collective variables that are meant to capture the system’s degrees of freedom. In ligand binding, water has long been known to play a key role, but its complex behaviour has proven difficult to fully capture. In this paper we combine machine learning with physical intuition to build a non-local and highly efficient water-describing collective variable. We use it to study a set of host-guest systems from the SAMPL5 challenge. We obtain highly accurate binding free energies and good agreement with experiments. The role of water during the binding process is then analysed in some detail.

scholarly journals The role of water in host-guest interaction

2020 ◽  
Author(s):  
Valerio Rizzi ◽  
Luigi Bonati ◽  
Narjes Ansari ◽  
Michele Parrinello
Keyword(s):  
Ligand Binding ◽  
Degrees Of Freedom ◽  
Binding Energies ◽  
Enhanced Sampling ◽  
Collective Variables ◽  
Complex Behaviour ◽  
Field Quality ◽  
Non Local ◽  
Good Agreement

Abstract One of the main applications of atomistic computer simulations is the calculation of ligand binding energies. The accuracy of these calculations depends on the force field quality and on the thoroughness of configuration sampling. Sampling is an obstacle in modern simulations due to the frequent appearance of kinetic bottlenecks in the free energy landscape. Very often this difficulty is circumvented by enhanced sampling techniques. Typically, these techniques depend on the introduction of appropriate collective variables that are meant to capture the system's degrees of freedom. In ligand binding, water has long been known to play a key role, but its complex behaviour has proven difficult to fully capture. In this paper we combine machine learning with physical intuition to build a non-local and highly efficient water-describing collective variable. We use it to study a set of of host-guest systems from the SAMPL5 challenge. We obtain highly accurate binding energies and good agreement with experiments. The role of water during the binding process is then analysed in some detail.

scholarly journals The Role of Λ-Effective Mass in a Phenomenological Analysis of the Λ-Energy in Hypernuclei

2020 ◽  
Vol 13 ◽  
pp. 277
Author(s):  
C. A. Efthimiou ◽  
M. E. Grypeos ◽  
C. G. Koutroulos
Keyword(s):  
Effective Mass ◽  
Ground State ◽  
State Energy ◽  
Phenomenological Analysis ◽  
Local Effects ◽  
The Past ◽  
Preliminary Account ◽  
Relativistic Treatment ◽  
Non Local

A preliminary account is given of an effort undertaken to allow for the effective mass of the Λ-particle in a phenomenological analysis of existing experimental data for the (ground state) energy of the Λ : EΛ in hypernuclei. The non - relativistic treatment is adopted to describe the motion of the Λ - particle, by considering a central potential well V (r), formed by the nuclear "host" medium of the Λ in the hypernucleus. The Λ - effective mass in the medium is taken to be an r-dependent effective mass mΛ(r) representing approximately some non-local effects in a way suggested in the past. Certain preliminary numerical results are obtained and discussed.

scholarly journals Quantum postulate vs. quantum nonlocality: on the role of the Planck constant in Bell’s argument

2021 ◽  
Vol 51 (1) ◽  
Author(s):  
Andrei Khrennikov
Keyword(s):  
Quantum Nonlocality ◽  
Quantum Mechanical ◽  
Quantum Foundations ◽  
Planck Constant ◽  
Variable Model ◽  
Basic Principles ◽  
Fundamental Feature ◽  
Hidden Variable ◽  
Bell Model

AbstractWe present a quantum mechanical (QM) analysis of Bell’s approach to quantum foundations based on his hidden-variable model. We claim and try to justify that the Bell model contradicts to the Heinsenberg’s uncertainty and Bohr’s complementarity principles. The aim of this note is to point to the physical seed of the aforementioned principles. This is the Bohr’s quantum postulate: the existence of indivisible quantum of action given by the Planck constant h. By contradicting these basic principles of QM, Bell’s model implies rejection of this postulate as well. Thus, this hidden-variable model contradicts not only the QM-formalism, but also the fundamental feature of the quantum world discovered by Planck.

scholarly journals Role of Bi3+ ions on structural, optical, photoluminescence and electrical performance of Cd0.9-xZn0.1BixS QDs

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
A. Krishnamoorthy ◽  
P. Sakthivel ◽  
I. Devadoss ◽  
V. M. Anitha Rajathi
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Optical Transmittance ◽  
Electrical Performance ◽  
Chemical Route ◽  
Red Emission ◽  
The Mean ◽  
Cubic Structure ◽  
Cyclic Voltammetry Analysis

AbstractIn this work, the Cd0.9-xZn0.1BixS QDs with different compositions of Bi3+ ions (0 ≤ x ≤ 0.05) were synthesized using a facile chemical route. The prepared QDs were characterized for analyzing the structural, morphological, elemental, optical, band gap, photoluminescence and electrochemical properties. XRD results confirmed that the Cd0.9-xZn0.1BixS QDs have a cubic structure. The mean crystallite size was increased from ~ 2 to ~ 5 nm for the increase of Bi3+ ions concentration. The optical transmittance behavior was decreased with increasing Bi3+ ions. The scanning electron microscope images showed that the prepared QDs possessed agglomerated morphology and the EDAX confirmed the presence of doped elements as per stoichiometry ratio. The optical band gap was slightly blue-shifted for initial substitution (Bi3+  = 1%) of Bi3+ ions and red-shifted for further increase of Bi3+ compositions. The optical band gap was ranged between 3.76 and 4.0 eV. High intense red emission was received for Bi3+ (1%) doped Zn:CdS QDs. The red emission peaks were shifted to a higher wavelength side due to the addition of Bi3+ ions. The PL emission on UV-region was raised for Bi3+ (1%) and it was diminished. Further, a violet (422 nm) and blue (460 nm) emission were received for Bi3+ ions doping. The cyclic voltammetry analysis showed that Bi3+ (0%) possessed better electrical properties than other compositions of Bi3+ ions.

Paper 5: Track Parameters, Static and Dynamic

1965 ◽  
Vol 180 (6) ◽  
pp. 73-85 ◽  
Author(s):  
F. Birmann
Keyword(s):  
Phase Shift ◽  
Dynamic Behaviour ◽  
Limit Values ◽  
The Third ◽  
New Methods ◽  
Measuring Techniques ◽  
Wheel Loading

In the first part a static investigation is made of the total elasticity of the track on soft sub-soil and loose ballast, and for rock and consolidated bedding. The oscillating mass of the permanent way will differ in behaviour, depending on construction, rail profile, sleeper spacing, etc. The damping and the phase shift can be determined by modern measuring techniques and a few limit values are given. In the second part the dynamic behaviour of the track is investigated for velocities up to 200 km/h. New methods of measuring the wheel loading on the rail are briefly described. Elements of permanent way calculation, based on new methods of computation, are briefly considered. The role of the lateral elasticity of the rail is shown in the third part, theoretically and according to measurements.

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