Size-dependent parameter cancels chaotic vibrations of flexible shallow nano-shells

2019 ◽  
Vol 446 ◽  
pp. 374-386 ◽  
Author(s):  
V.A. Krysko ◽  
J. Awrejcewicz ◽  
V. Dobriyan ◽  
I.V. Papkova ◽  
V.A. Krysko
Keyword(s):  
Size Dependent ◽  
Chaotic Vibrations ◽  
Dependent Parameter

scholarly journals Scientific Visualization of the Results of a Numerical Experiment of the Nonlinear Dynamics of a Nanoscale Beam Structure

2020 ◽  
pp. short7-1-short7-9
Author(s):  
Olga Saltykova
Keyword(s):  
Nonlinear Dynamics ◽  
Differential Equations ◽  
Scientific Visualization ◽  
Power Spectra ◽  
Theory Of Elasticity ◽  
Operating Conditions ◽  
Harmonic Load ◽  
Beam Structure ◽  
Size Dependent ◽  
Dependent Parameter

The paper presents the results of scientific visualization of the nonlinear dynamics of contact interaction of a nanoscale beam structure under the action of an external harmonic load. The beam structure consists of two beams obeying the kinematic hypotheses of Euler-Bernoulli and S.P. Timoshenko. The constructed mathematical model takes into account geometric and constructive nonlinearities. The size-dependent behavior of the structure is implemented on the basis of the modified moment theory of elasticity. The resulting system of partial differential equations is reduced to a system of ordinary differential equations by the second order finite difference method. The Cauchy problem is solved by the fourth order Runge-Kutta method. In this work, using the methods of scientific visualization of the results of applying the methods of nonlinear dynamics, the influence of the size-dependent parameter and external load on the vibrations of the beam structure is investigated. As methods for studying nonlinear dynamics, the work uses wavelet spectra based on the mother Morlet, Fourier power spectra, signals. The use of scientific visualization methods makes it possible to develop specific recommendations for the operating conditions of the beam structure. This, in turn, makes it possible to avoid unwanted vibration modes of beam nanostructures, which are widely used as sensitive elements of sensors of micro and nano electromechanical systems.

Chaotic vibrations of size-dependent flexible rectangular plates

2021 ◽  
Vol 31 (4) ◽  
pp. 043119
Author(s):  
V. A. Krysko ◽  
J. Awrejcewicz ◽  
I. V. Papkova ◽  
V. A. Krysko
Keyword(s):  
Rectangular Plates ◽  
Size Dependent ◽  
Chaotic Vibrations

scholarly journals The bone mass concept: problems in short stature

2004 ◽  
pp. S87-S91 ◽  
Author(s):  
E Schoenau ◽  
C Land ◽  
A Stabrey ◽  
T Remer ◽  
A Kroke
Keyword(s):  
Bone Mass ◽  
Children And Adolescents ◽  
Bone Densitometry ◽  
Mineral Content ◽  
Bone Diseases ◽  
Size Dependent ◽  
Short Children ◽  
Dependent Parameter ◽  
Chronic Disorders ◽  
Small Bones

Bone densitometry is currently one of the mainstays in the evaluation of systemic bone diseases in adults and is also increasingly used to assess primary or secondary bone disorders in children and adolescents. The purpose of carrying out densitometric studies in such circumstances is to measure the densitometric indicators of bone stability. Following procedures which were established for diagnosing adult osteoporosis, a decrease in densitometric surrogates of bone stability is usually interpreted as indicating increased fracture risk. The most basic densitometric parameter is bone mineral content (BMC), which can be measured with most densitometric techniques. BMC is either defined as the mass of mineral contained in an entire bone or as the mass of mineral per unit bone length. While mineral mass can be expected to be a good surrogate for bone stability, BMC is obviously a size-dependent parameter, since small bones weigh less than big bones. This is a drawback in paediatric use, since many children and adolescents who are examined by densitometry suffer from chronic disorders and are small-for-age. Short children will have a lower BMC than their healthy age-matched peers, even if their (smaller) bones are otherwise completely normal.

Competitive STDP Learning of Overlapping Spatial Patterns

2015 ◽  
Vol 27 (8) ◽  
pp. 1673-1685 ◽  
Author(s):  
Dalius Krunglevicius
Keyword(s):  
Neural Network ◽  
Euclidean Distance ◽  
Hebbian Learning ◽  
Spike Timing ◽  
Spiking Neural Network ◽  
Size Dependent ◽  
Learning Rules ◽  
Pattern Size ◽  
Dependent Parameter ◽  
Simple Neural Network

Spike-timing-dependent plasticity (STDP) is a set of Hebbian learning rules firmly based on biological evidence. It has been demonstrated that one of the STDP learning rules is suited for learning spatiotemporal patterns. When multiple neurons are organized in a simple competitive spiking neural network, this network is capable of learning multiple distinct patterns. If patterns overlap significantly (i.e., patterns are mutually inclusive), however, competition would not preclude trained neuron’s responding to a new pattern and adjusting synaptic weights accordingly. This letter presents a simple neural network that combines vertical inhibition and Euclidean distance-dependent synaptic strength factor. This approach helps to solve the problem of pattern size-dependent parameter optimality and significantly reduces the probability of a neuron’s forgetting an already learned pattern. For demonstration purposes, the network was trained for the first ten letters of the Braille alphabet.

Size Dependence Adsorption of Hydrogen on Cobalt Clusters: A DFT Study

2016 ◽  
Vol 42 ◽  
pp. 100-111 ◽  
Author(s):  
Ali Nakhaei Pour ◽  
Javad Karimi ◽  
Zahra Keyvanloo ◽  
Mohamadreza Hashemian
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Metal Cluster ◽  
Volume Ratio ◽  
Functional Theory ◽  
Cobalt Clusters ◽  
Size Dependent ◽  
Dependent Parameter ◽  
Adsorption Of Hydrogen ◽  
Cohesive Energies

Density functional theory was used to investigate the effect of size on the adsorption state of hydrogen atom on small cobalt particles. For this propose, we have performed series of DFT-GGA calculations on various sizes of Co clusters, between 4 and 24 atoms, and a Co FCC (100) slab, with and without hydrogen atom adsorbate. The results showed that the destabilization and the cohesive energies per atom in a metal cluster are represented as linear function of the surface-to-volume ratio of the metal clusters. In addition, the energy of the HOMO–LUMO gap from 4s and 3d valence orbitals of the cobalt atoms in the cluster is decreased with increasing in cobalt cluster size, which is size dependent parameter. We have studied the effect of the size of Co clusters and the infinite Co (100) surface, on the energy of adsorption of hydrogen atom. The calculated Eads for hydrogen atom in our considered cobalt clusters showed decreasing behavior with increasing of the number of atoms in cluster.

Production and STEM examination of controlled-size silver clusters

1983 ◽  
Vol 41 ◽  
pp. 338-339
Author(s):  
M. A. Listvan ◽  
R. P. Andres
Keyword(s):  
Cluster Size ◽  
Metal Clusters ◽  
Experimental Parameter ◽  
Carbon Films ◽  
Metal Species ◽  
Silver Clusters ◽  
Free Jet ◽  
Size Dependent ◽  
Cluster Properties ◽  
Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

Spindle scaling mechanisms

2020 ◽  
Vol 64 (2) ◽  
pp. 383-396
Author(s):  
Lara K. Krüger ◽  
Phong T. Tran
Keyword(s):  
Cell Size ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Post Translational Modification ◽  
Size Dependent ◽  
A Cell ◽  
Chromosome Separation ◽  
Spindle Elongation ◽  
Protein Gradients ◽  
Spindle Structure

Abstract The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.

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