DEPENDENCE OF THE PEAK EFFECT ON THE DENSITY OF PINNING SITES

2008 ◽  
Vol 22 (31) ◽  
pp. 3125-3134 ◽  
Author(s):  
I. M. OBAIDAT ◽  
U. AL KHAWAJA ◽  
M. BENKRAOUDA
Keyword(s):  
Critical Current Density ◽  
Driving Force ◽  
Peak Effect ◽  
Molecular Dynamic Simulations ◽  
Zero Temperature ◽  
Relative Height ◽  
Dynamic Simulations ◽  
One Dimensional ◽  
Matching Field

We have investigated the role of pinning density on the properties of the peak effect in the critical current density in superconducting systems. This study was conducted using a series of molecular dynamic simulations on two systems of nanostructures of periodic square arrays of pinning sites with different pining densities. We have found that the peak occurred in both systems only at zero temperature and for specific values of pinning strength. The most interesting result was that in both systems, the peak was found to occur only at nearly 0.5 fraction of the first matching field for all values of pinning strength. The properties of the peak were found to depend mainly on the initial positions of the vortices with respect to the positions of the pinning sites. The critical dipping force at the peak was found to increase linearly with the pinning strength and to have larger values for the system with the smaller density of pinning sites. The dependence of the relative height of the peak on the pinning strength was found be nearly the same in both systems. One-dimensional linear channels of moving vortices along the direction of the driving force were observed at the dip just before the peak.

Role of the Kinetic Relation in a Phase Transition-Based Model for Mechanical Unfolding in Macromolecules

2010 ◽  
Author(s):  
Ritwik Raj ◽  
Prashant K. Purohit
Keyword(s):  
Phase Transition ◽  
Driving Force ◽  
Metastable States ◽  
Force Extension ◽  
Kinetic Relation ◽  
One Dimensional ◽  
Applied Tension ◽  
Thermodynamic Driving Force ◽  
Macro Molecule

We present applications of a model developed to describe unfolding in macromolecules under an axial force. We show how different experimentally observed force-extension behaviors can be reproduced within a common theoretical framework. We propose that the unfolding occurs via the motion of a folded/unfolded interface along the length of the molecule. The molecules are modeled as one-dimensional continua capable of existing in two metastable states under an applied tension. The interface separates these two metastable states and represents a jump in stretch, which is related to applied force by the worm-like-chain relation. The mechanics of the interface are governed by the Abeyaratne-Knowles theory of phase transitions. The thermodynamic driving force controls the motion of the interface via an equation called the kinetic relation. By choosing an appropriate kinetic relation for the unfolding conditions and the macro-molecule under consideration, we have been able to generate a variety of unfolding processes in macromolecules.

scholarly journals The role of water co-adsorption on the modification of ZnO nanowires using acetic acid

2014 ◽  
Vol 16 (18) ◽  
pp. 8509-8514 ◽  
Author(s):  
Adriel Domínguez ◽  
Svea grosse Holthaus ◽  
Susan Köppen ◽  
Thomas Frauenheim ◽  
Andreia Luisa da Rosa
Keyword(s):  
Density Functional Theory ◽  
Acetic Acid ◽  
Molecular Dynamic ◽  
Density Functional ◽  
Co Adsorption ◽  
Zno Nanowires ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Functional Theory

Density functional theory (DFT) and Car–Parinello molecular dynamic simulations were employed to investigate the interaction of acetic acid with non-polar facets of ultra-thin ZnO nanowires.

A PEAK IN THE BOSE GLASS LINE AT THE FIRST MATCHING FIELD OF NANOSTRUCTURES OF PINNING SITES

2009 ◽  
Vol 23 (22) ◽  
pp. 4655-4664
Author(s):  
I. M. OBAIDAT
Keyword(s):  
Vortex Motion ◽  
Vortex Pinning ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Liquid Phase Transition ◽  
Vortex Lattices ◽  
Bose Glass ◽  
Matching Field ◽  
Damped Equation ◽  
T Phase

Using an extensive series of molecular dynamic simulations on driven vortex lattices interacting with nanostructures of periodic square arrays of pinning sites of fixed density, we have obtained the B–T phase diagram representing a Bose glass to vortex liquid-phase transition. In solving the over damped equation of vortex motion, we took into account the vortex–vortex repulsion interaction, the attractive vortex–pinning interaction, and the driving Lorentz force at several values of temperature. We have found that the location of the Bose glass line (TBG-line) depends on the pinning strength of the pinning sites. We have also found that for each pinning strength value, there is an interesting peak of the TBG-line that occurs at the first matching field when the number of vortices equals the number of pinning sites in the sample.

scholarly journals BUCKLING INSTABILITY FOR A CHARGED AND SEMIFLEXIBLE POLYMER

2011 ◽  
Vol 25 (28) ◽  
pp. 2209-2217 ◽  
Author(s):  
KHABAT GHAMARI ◽  
ALI NAJAFI
Keyword(s):  
Compressive Force ◽  
Thermal Fluctuations ◽  
Critical Force ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Buckling Instability ◽  
Flexible Polymer ◽  
Semiflexible Polymer ◽  
Semi Flexible Polymer

In this article, we address the problem of Euler's buckling instability in a charged semi-flexible polymer that is under the action of a compressive force. We consider this instability as a phase transition and investigate the role of thermal fluctuations in the buckling critical force. By performing molecular dynamic simulations, we show that the critical force decreases when the temperature increases. Repulsive electrostatic interaction in the finite temperature is in competition with thermal fluctuations to increase the buckling threshold.

Economic Growth: New Problems and New Risks

2006 ◽  
pp. 20-37 ◽  
Author(s):  
M. Ershov
Keyword(s):  
Economic Growth ◽  
Foreign Exchange ◽  
Driving Force ◽  
Structural Changes ◽  
Rate Of Growth

The economic growth, which is underway in Russia, raises new questions to be addressed. How to improve the quality of growth, increasing the role of new competitive sectors and transforming them into the driving force of growth? How can progressive structural changes be implemented without hampering the rate of growth in general? What are the main external and internal risks, which may undermine positive trends of development? The author looks upon financial, monetary and foreign exchange aspects of the problem and comes up with some suggestions on how to make growth more competitive and sustainable.

Adiabatic large polarons in anisotropic molecular crystals

2011 ◽  
Vol 35 (1) ◽  
pp. 15-27
Author(s):  
Zoran Ivić ◽  
Željko Pržulj
Keyword(s):  
Energy Transfer ◽  
Effective Mass ◽  
Molecular Crystals ◽  
Single Chain ◽  
Proper Understanding ◽  
One Dimensional ◽  
Interchain Coupling ◽  
Large Polaron ◽  
The One

Adiabatic large polarons in anisotropic molecular crystals We study the large polaron whose motion is confined to a single chain in a system composed of the collection of parallel molecular chains embedded in threedimensional lattice. It is found that the interchain coupling has a significant impact on the large polaron characteristics. In particular, its radius is quite larger while its effective mass is considerably lighter than that estimated within the one-dimensional models. We believe that our findings should be taken into account for the proper understanding of the possible role of large polarons in the charge and energy transfer in quasi-one-dimensional substances.

La politique forestière vaudoise: une orientation résolument «patrimoine multifonctionnel» | Forestry policy in the canton of Vaud: the “multifunctional heritage” option

2011 ◽  
Vol 162 (7) ◽  
pp. 209-215
Author(s):  
Jean-François Métraux
Keyword(s):  
Driving Force ◽  
Management Plan ◽  
The Political ◽  
Wood Production ◽  
Forest Owners ◽  
Forestry Policy ◽  
Forestry Management ◽  
Political Decisions ◽  
Forest Managers

In the years since 2000, the authorities in charge of forests in canton Vaud have made some substantial changes as a reaction to the political decisions arising from the Swiss Forest Programme and the projected revision of the Federal forestry Law, as well as to the deterioration of the economic situation in forestry enterprises. This article gives a survey of the directions taken. Thus the canton recognises the primordial role of wood production as a driving force behind the creation of a multifunctional forest. The Service for Forests, Wildlife and Nature has invested a great deal in planning, and has redefined the management plan to be an instrument intended for forest owners and forest managers. The canton has innovated by introducing forestry groups and a scheme of equalisation of forestry costs between communes. Hence the conception of forestry management in canton Vaud is resolutely that of a multifunctional natural heritage.

Sign in / Sign up

Export Citation Format

Share Document