Dynamic theory for the mesoscopic electric circuit

International Nuclear Information System (INIS)

Chen Bin; Shen Xiaojuan; Li Youquan; Sun LiLy; Yin Zhujian

2005-01-01

The quantum theory for mesoscopic electric circuit with charge discreteness is briefly described. The minibands of quasienergy in LC design mesoscopic electric circuit have been found. In the mesoscopic 'pure' inductance design circuit, just like in the mesoscopic metallic rings, the quantum dynamic characteristics have been obtained explicitly. In the 'pure' capacity design circuit, the Coulomb blockade had also been addressed

Mesoscopic Structural Observations of Cores from the Chelungpu Fault System, Taiwan Chelungpu-Fault Drilling Project Hole-A, Taiwan

Directory of Open Access Journals (Sweden)

Hiroki Sone

2007-01-01

Full Text Available Structural characteristics of fault rocks distributed within major fault zones provide basic information in understanding the physical aspects of faulting. Mesoscopic structural observations of the drilledcores from Taiwan Chelungpu-fault Drilling Project Hole-A are reported in this article to describe and reveal the distribution of fault rocks within the Chelungpu Fault System.

Mesoscopic Numerical Computation of Compressive Strength and Damage Mechanism of Rubber Concrete

Directory of Open Access Journals (Sweden)

Z. H. Xie

2015-01-01

Full Text Available Evaluations of both macroscopic and mesoscopic strengths of materials have been the topic of a great deal of recent research. This paper presents the results of a study, based on the Walraven equation of the production of a mesoscopic random aggregate structure containing various rubber contents and aggregate sizes. On a mesoscopic scale, the damage mechanism in the rubber concrete and the effects of the rubber content and aggregate-mortar interface on the rubber concrete’s compressive resistance property were studied. The results indicate that the random aggregate structural model very closely approximates the experimental results in terms of the fracture distribution and damage characteristics under uniaxial compression. The aggregate-mortar interface mechanical properties have a substantial impact on the test sample’s strength and fracture distribution. As the rubber content increases, the compressive strength and elastic modulus of the test sample decrease proportionally. This paper presents graphics of the entire process from fracture propagation to structural failure of the test piece by means of the mesoscopic finite-element method, which provides a theoretical reference for studying the damage mechanism in rubber concrete and performing parametric calculations.

Mesoscopic quantum emitters coupled to plasmonic nanostructures

DEFF Research Database (Denmark)

Andersen, Mads Lykke

for the spontaneous emission of mesoscopic quantum emitters is developed. The light-matter interaction is in this model modied beyond the dipole expectancy and found to both suppress and enhance the coupling to plasmonic modes in excellent agreement with our measurements. We demonstrate that this mesoscopic effect......This thesis reports research on quantum dots coupled to dielectric and plasmonic nano-structures by way of nano-structure fabrication, optical measurements, and theoretical modeling. To study light-matter interaction, plasmonic gap waveguides with nanometer dimensions as well as samples for studies...... to allow for e- cient plasmon-based single-photon sources. Theoretical studies of coupling and propagation properties of plasmonic waveguides reveal that a high-refractive index of the medium surrounding the emitter, e.g. nGaAs = 3.5, limits the realizability of ecient plasmon-based single-photon sources...

Mesoscopic rings with spin-orbit interactions

Energy Technology Data Exchange (ETDEWEB)

Berche, Bertrand; Chatelain, Christophe; Medina, Ernesto, E-mail: berche@lpm.u-nancy.f [Statistical Physics Group, Institut Jean Lamour, UMR CNRS No 7198, Universite Henri Poincare, Nancy 1, B.P. 70239, F-54506 Vandoeuvre les Nancy (France)

2010-09-15

A didactic description of charge and spin equilibrium currents on mesoscopic rings in the presence of spin-orbit interaction is presented. Emphasis is made on the non-trivial construction of the correct Hamiltonian in polar coordinates, the calculation of eigenvalues and eigenfunctions and the symmetries of the ground-state properties. Spin currents are derived following an intuitive definition, and then a more thorough derivation is built upon the canonical Lagrangian formulation that emphasizes the SU(2) gauge structure of the transport problem of spin-1/2 fermions in spin-orbit active media. The quantization conditions that follow from the constraint of single-valued Pauli spinors are also discussed. The targeted students are those of a graduate condensed matter physics course.

Amyloid Fibril Polymorphism: Almost Identical on the Atomic Level, Mesoscopically Very Different.

Science.gov (United States)

Seuring, Carolin; Verasdonck, Joeri; Ringler, Philippe; Cadalbert, Riccardo; Stahlberg, Henning; Böckmann, Anja; Meier, Beat H; Riek, Roland

2017-03-02

Amyloid polymorphism of twisted and straight β-endorphin fibrils was studied by negative-stain transmission electron microscopy, scanning transmission electron microscopy, and solid-state nuclear magnetic resonance spectroscopy. Whereas fibrils assembled in the presence of salt formed flat, striated ribbons, in the absence of salt they formed mainly twisted filaments. To get insights into their structural differences at the atomic level, 3D solid-state NMR spectra of both fibril types were acquired, allowing the detection of the differences in chemical shifts of 13 C and 15 N atoms in both preparations. The spectral fingerprints and therefore the chemical shifts are very similar for both fibril types. This indicates that the monomer structure and the molecular interfaces are almost the same but that these small differences do propagate to produce flat and twisted morphologies at the mesoscopic scale. This finding is in agreement with both experimental and theoretical considerations on the assembly of polymers (including amyloids) under different salt conditions, which attribute the mesoscopic difference of flat versus twisted fibrils to electrostatic intermolecular repulsions.

High Resolution Higher Energy X-ray Microscope for Mesoscopic Materials

International Nuclear Information System (INIS)

Snigireva, I; Snigirev, A

2013-01-01

We developed a novel X-ray microscopy technique to study mesoscopically structured materials, employing compound refractive lenses. The easily seen advantage of lens-based methodology is the possibility to retrieve high resolution diffraction pattern and real-space images in the same experimental setup. Methodologically the proposed approach is similar to the studies of crystals by high resolution transmission electron microscopy. The proposed microscope was applied for studying of mesoscopic materials such as natural and synthetic opals, inverted photonic crystals

Applications of mesoscopic physics

International Nuclear Information System (INIS)

Feng, Shechao.

1993-01-01

Research activities in the area ''applications of mesoscopic physics to novel correlations and fluctuations of speckle patterns: imaging and tomography with multiply scattered classical waves'' are briefly summarized. The main thrust in fundamental research is in the general areas of mesoscopic effects in disordered semiconductors and metals and the related field of applications of mesoscopic physics to the subject matter of classical wave propagation through disordered scattering media. Specific topics are Fabry-Perot interferometer with disorder: correlations and light localization; electron-phonon inelastic scattering rate and the temperature scaling exponent in integer quantum Hall effect; and transmission and reflection correlations of second harmonic waves in nonlinear random media. Research in applied physics centered on far infrared photon-assisted transport through quantum point contact devices and photon migration distributions in multiple scattering media. 7 refs

X-ray diffraction from mesoscopic systems

International Nuclear Information System (INIS)

Press, W.; Bahr, D.; Tolan, M.; Burandt, B.; Mueller, M.; Mueller-Buschbaum, P.; Nitz, V.; Stettner, J.

1994-01-01

Two activities of our group concerning structures on mesoscopic length scales are presented: (1) CoSi 2 layers buried in Si-wafers have been studied with many scattering geometries; the emphasis is on diffuse scattering from rough interfaces and diffuse scattering from atomic scale defects. (2) The other example is an investigation of laterally structured surfaces in the region of total external reflection and around Bragg peaks. In both cases extensions of the presently available models are necessary. ((orig.))

Predicting protein folding pathways at the mesoscopic level based on native interactions between secondary structure elements

Directory of Open Access Journals (Sweden)

Sze Sing-Hoi

2008-07-01

Full Text Available Abstract Background Since experimental determination of protein folding pathways remains difficult, computational techniques are often used to simulate protein folding. Most current techniques to predict protein folding pathways are computationally intensive and are suitable only for small proteins. Results By assuming that the native structure of a protein is known and representing each intermediate conformation as a collection of fully folded structures in which each of them contains a set of interacting secondary structure elements, we show that it is possible to significantly reduce the conformation space while still being able to predict the most energetically favorable folding pathway of large proteins with hundreds of residues at the mesoscopic level, including the pig muscle phosphoglycerate kinase with 416 residues. The model is detailed enough to distinguish between different folding pathways of structurally very similar proteins, including the streptococcal protein G and the peptostreptococcal protein L. The model is also able to recognize the differences between the folding pathways of protein G and its two structurally similar variants NuG1 and NuG2, which are even harder to distinguish. We show that this strategy can produce accurate predictions on many other proteins with experimentally determined intermediate folding states. Conclusion Our technique is efficient enough to predict folding pathways for both large and small proteins at the mesoscopic level. Such a strategy is often the only feasible choice for large proteins. A software program implementing this strategy (SSFold is available at http://faculty.cs.tamu.edu/shsze/ssfold.

Coulomb drag in the mesoscopic regime

DEFF Research Database (Denmark)

Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka

2002-01-01

We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... means such as perturbation theory or random matrix theory. The physics of Coulomb drag in the mesoscopic regime is very different from Coulomb drag between extended electron systems. In the mesoscopic regime we in general find fluctuations of the drag comparable to the mean value. Examples are vanishing...

Coulomb drag in the mesoscopic regime

DEFF Research Database (Denmark)

Mortensen, N.A.; Flensberg, Karsten; Jauho, Antti-Pekka

2002-01-01

We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... means such as perturbation theory or random matrix theory. The physics of Coulomb drag in the mesoscopic regime is very different from Coulomb drag between extended electron systems. In the mesoscopic regime we in general find fluctuations of the drag comparable to the mean value. Examples are vanishing...

Flexible histone tails in a new mesoscopic oligonucleosome model.

Science.gov (United States)

Arya, Gaurav; Zhang, Qing; Schlick, Tamar

2006-07-01

We describe a new mesoscopic model of oligonucleosomes that incorporates flexible histone tails. The nucleosome cores are modeled using the discrete surface-charge optimization model, which treats the nucleosome as an electrostatic surface represented by hundreds of point charges; the linker DNAs are treated using a discrete elastic chain model; and the histone tails are modeled using a bead/chain hydrodynamic approach as chains of connected beads where each bead represents five protein residues. Appropriate charges and force fields are assigned to each histone chain so as to reproduce the electrostatic potential, structure, and dynamics of the corresponding atomistic histone tails at different salt conditions. The dynamics of resulting oligonucleosomes at different sizes and varying salt concentrations are simulated by Brownian dynamics with complete hydrodynamic interactions. The analyses demonstrate that the new mesoscopic model reproduces experimental results better than its predecessors, which modeled histone tails as rigid entities. In particular, our model with flexible histone tails: correctly accounts for salt-dependent conformational changes in the histone tails; yields the experimentally obtained values of histone-tail mediated core/core attraction energies; and considers the partial shielding of electrostatic repulsion between DNA linkers as a result of the spatial distribution of histone tails. These effects are crucial for regulating chromatin structure but are absent or improperly treated in models with rigid histone tails. The development of this model of oligonucleosomes thus opens new avenues for studying the role of histone tails and their variants in mediating gene expression through modulation of chromatin structure.

Mesoscopic modeling of structural and thermodynamic properties of fluids confined by rough surfaces.

Science.gov (United States)

Terrón-Mejía, Ketzasmin A; López-Rendón, Roberto; Gama Goicochea, Armando

2015-10-21

The interfacial and structural properties of fluids confined by surfaces of different geometries are studied at the mesoscopic scale using dissipative particle dynamics simulations in the grand canonical ensemble. The structure of the surfaces is modeled by a simple function, which allows us to simulate readily different types of surfaces through the choice of three parameters only. The fluids we have modeled are confined either by two smooth surfaces or by symmetrically and asymmetrically structured walls. We calculate structural and thermodynamic properties such as the density, temperature and pressure profiles, as well as the interfacial tension profiles for each case and find that a structural order-disorder phase transition occurs as the degree of surface roughness increases. However, the magnitude of the interfacial tension is insensitive to the structuring of the surfaces and depends solely on the magnitude of the solid-fluid interaction. These results are important for modern nanotechnology applications, such as in the enhanced recovery of oil, and in the design of porous materials with specifically tailored properties.

Tunable quasiparticle trapping in Meissner and vortex states of mesoscopic superconductors.

Science.gov (United States)

Taupin, M; Khaymovich, I M; Meschke, M; Mel'nikov, A S; Pekola, J P

2016-03-16

Nowadays, superconductors serve in numerous applications, from high-field magnets to ultrasensitive detectors of radiation. Mesoscopic superconducting devices, referring to those with nanoscale dimensions, are in a special position as they are easily driven out of equilibrium under typical operating conditions. The out-of-equilibrium superconductors are characterized by non-equilibrium quasiparticles. These extra excitations can compromise the performance of mesoscopic devices by introducing, for example, leakage currents or decreased coherence time in quantum devices. By applying an external magnetic field, one can conveniently suppress or redistribute the population of excess quasiparticles. In this article, we present an experimental demonstration and a theoretical analysis of such effective control of quasiparticles, resulting in electron cooling both in the Meissner and vortex states of a mesoscopic superconductor. We introduce a theoretical model of quasiparticle dynamics, which is in quantitative agreement with the experimental data.

Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

Science.gov (United States)

Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

2016-02-01

Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

Macro-mesoscopic Fracture and Strength Character of Pre-cracked Granite Under Stress Relaxation Condition

Science.gov (United States)

Liu, Junfeng; Yang, Haiqing; Xiao, Yang; Zhou, Xiaoping

2018-05-01

The fracture characters are important index to study the strength and deformation behavior of rock mass in rock engineering. In order to investigate the influencing mechanism of loading conditions on the strength and macro-mesoscopic fracture character of rock material, pre-cracked granite specimens are prepared to conduct a series of uniaxial compression experiments. For parts of the experiments, stress relaxation tests of different durations are also conducted during the uniaxial loading process. Furthermore, the stereomicroscope is adopted to observe the microstructure of the crack surfaces of the specimens. The experimental results indicate that the crack surfaces show several typical fracture characters in accordance with loading conditions. In detail, some cleavage fracture can be observed under conventional uniaxial compression and the fractured surface is relatively rough, whereas as stress relaxation tests are attached, relative slip trace appears between the crack faces and some shear fracture starts to come into being. Besides, the crack faces tend to become smoother and typical terrace structures can be observed in local areas. Combining the macroscopic failure pattern of the specimens, it can be deduced that the duration time for the stress relaxation test contributes to the improvement of the elastic-plastic strain range as well as the axial peak strength for the studied material. Moreover, the derived conclusion is also consistent with the experimental and analytical solution for the pre-peak stage of the rock material. The present work may provide some primary understanding about the strength character and fracture mechanism of hard rock under different engineering environments.

Mesoscopic Magnetic Resonance Spectroscopy with a Remote Spin Sensor

Science.gov (United States)

Xie, Tianyu; Shi, Fazhan; Chen, Sanyou; Guo, Maosen; Chen, Yisheng; Zhang, Yixing; Yang, Yu; Gao, Xingyu; Kong, Xi; Wang, Pengfei; Tateishi, Kenichiro; Uesaka, Tomohiro; Wang, Ya; Zhang, Bo; Du, Jiangfeng

2018-06-01

Quantum sensing based on nitrogen-vacancy (N -V ) centers in diamond has been developed as a powerful tool for microscopic magnetic resonance. However, the reported sensor-to-sample distance is limited within tens of nanometers resulting from the cubic decrease of the signal of spin fluctuation with the increasing distance. Here we extend the sensing distance to tens of micrometers by detecting spin polarization rather than spin fluctuation. We detect the mesoscopic magnetic resonance spectra of polarized electrons of a pentacene-doped crystal, measure its two typical decay times, and observe the optically enhanced spin polarization. This work paves the way for the N -V -based mesoscopic magnetic resonance spectroscopy and imaging at ambient conditions.

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

NARCIS (Netherlands)

Chumakova, A. V.; Valkovskiy, G. A.; Mistonov, A. A.; Dyadkin, V. A.; Grigoryeva, N. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Petukhov, Andrei V.; Grigoriev, S. V.

2014-01-01

The structure of inverse opal crystals based on nickel was probed on the mesoscopic and atomic levels by a set of complementary techniques such as scanning electron microscopy and synchrotron microradian and wide-angle diffraction. The microradian diffraction revealed the mesoscopic-scale

Photon side-bands in mesoscopics

DEFF Research Database (Denmark)

Jauho, Antti-Pekka

1998-01-01

This paper reviews several applications of photonic side bands, used by Buttiker and Landauer (Phys. Rev. Lett. 49, 1739 (1982)) in their theory of traversal time in tunneling, in transport and optics of mesoscopic systems. Topics include generalizations of the transmission theory of transport...... to time-dependent situations, optics and transport of mesoscopic systems in THz electromagnetic fields, and phase-measurements of photon-assisted tunneling through a quantum dot. (C) 1998 Academic Press Limited....

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

OpenAIRE

Chumakova, A. V.; Valkovskiy, G. A.; Mistonov, A. A.; Dyadkin, V. A.; Grigoryeva, N. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Petukhov, Andrei V.; Grigoriev, S. V.

2014-01-01

The structure of inverse opal crystals based on nickel was probed on the mesoscopic and atomic levels by a set of complementary techniques such as scanning electron microscopy and synchrotron microradian and wide-angle diffraction. The microradian diffraction revealed the mesoscopic-scale face-centered-cubic (fcc) ordering of spherical voids in the inverse opal-like structure with unit cell dimension of 750±10nm. The diffuse scattering data were used to map defects in the fcc structure as a f...

Mesoscopic biology

Indian Academy of Sciences (India)

In this paper we present a qualitative outlook of mesoscopic biology where the typical length scale is of the order of nanometers and the energy scales comparable to thermal energy. Novel biomolecular machines, governed by coded information at the level of DNA and proteins, operate at these length scales in biological ...

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

Science.gov (United States)

Chumakova, A. V.; Valkovskiy, G. A.; Mistonov, A. A.; Dyadkin, V. A.; Grigoryeva, N. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Petukhov, A. V.; Grigoriev, S. V.

2014-10-01

The structure of inverse opal crystals based on nickel was probed on the mesoscopic and atomic levels by a set of complementary techniques such as scanning electron microscopy and synchrotron microradian and wide-angle diffraction. The microradian diffraction revealed the mesoscopic-scale face-centered-cubic (fcc) ordering of spherical voids in the inverse opal-like structure with unit cell dimension of 750±10nm. The diffuse scattering data were used to map defects in the fcc structure as a function of the number of layers in the Ni inverse opal-like structure. The average lateral size of mesoscopic domains is found to be independent of the number of layers. 3D reconstruction of the reciprocal space for the inverse opal crystals with different thickness provided an indirect study of original opal templates in a depth-resolved way. The microstructure and thermal response of the framework of the porous inverse opal crystal was examined using wide-angle powder x-ray diffraction. This artificial porous structure is built from nickel crystallites possessing stacking faults and dislocations peculiar for the nickel thin films.

Modeling elasto-plastic behavior of polycrystalline grain structure of steels at mesoscopic level

International Nuclear Information System (INIS)

Kovac, Marko; Cizelj, Leon

2005-01-01

The multiscale model is proposed to explicitly account for the inhomogeneous structure of polycrystalline materials. Grains and grain boundaries are modeled explicitly using Voronoi tessellation. The constitutive model of crystal grains utilizes anisotropic elasticity and crystal plasticity. Commercially available finite element code is applied to solve the boundary value problem defined at the macroscopic scale. No assumption regarding the distribution of the mesoscopic strain and stress fields is used, apart the finite element discretization. The proposed model is then used to estimate the minimum size of polycrystalline aggregate of selected reactor pressure vessel steel (22 NiMoCr 3 7), above which it can be considered macroscopically homogeneous. Elastic and rate-independent plastic deformation modes are considered. The results are validated by the experimental and simulation results from the literature

Dynamics of mesoscopic systems: Non-equilibrium Green's functions approach

Czech Academy of Sciences Publication Activity Database

Špička, Václav; Kalvová, Anděla; Velický, B.

2010-01-01

Roč. 42, č. 3 (2010), s. 525-538 ISSN 1386-9477 R&D Projects: GA ČR GA202/08/0361 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : mesoscopic systems * NGF * initial condition * correlations * Ward identities * transients Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.304, year: 2010

Recent trends in mesoscopic solar cells based on molecular and nanopigment light harvesters

KAUST Repository

Grä tzel, Carole; Zakeeruddin, Shaik M.

2013-01-01

Mesoscopic solar cells are one of the most promising photovoltaic technologies among third generation photovoltaics due to their low cost and high efficiency. The morphology of wide-band semiconductors, sensitized with molecular or nanosized light harvesters, used as electron collectors contribute substantially to the device performance. Recent developments in the use of organic-inorganic layer structured perovskites as light absorbers and as electron or hole transport materials allows reduction in the thickness of photoanodes to the submicron level and have raised the power conversion efficiency of solid state mesoscopic solar cells above the 10% level.

Contact Geometry of Mesoscopic Thermodynamics and Dynamics

Directory of Open Access Journals (Sweden)

Miroslav Grmela

2014-03-01

Full Text Available The time evolution during which macroscopic systems reach thermodynamic equilibrium states proceeds as a continuous sequence of contact structure preserving transformations maximizing the entropy. This viewpoint of mesoscopic thermodynamics and dynamics provides a unified setting for the classical equilibrium and nonequilibrium thermodynamics, kinetic theory, and statistical mechanics. One of the illustrations presented in the paper is a new version of extended nonequilibrium thermodynamics with fluxes as extra state variables.

Mesoscopic NbSe3 wires

International Nuclear Information System (INIS)

Zant, H.S.J. van der; Kalwij, A.; Mantel, O.C.; Markovic, N.

1999-01-01

We have fabricated wire structures with (sub)micron sizes in the charge-density wave conductor NbSe 3 . Electrical transport measurements include complete mode-locking on Shapiro steps and show that the patterning has not affected the CDW material. Our mesoscopic wires show strong fluctuation and hysteresis effects in the low-temperature current-voltage characteristics, as well as a strong reduction of the phase-slip voltage. This reduction can not be explained with existing models. We suggest that single phase-slip events are responsible for a substantial reduction of the CDW strain in micron-sized systems. (orig.)

Vortex 'puddles' and magic vortex numbers in mesoscopic superconducting disks

Energy Technology Data Exchange (ETDEWEB)

Connolly, M R; Milosevic, M V; Bending, S J [Department of Physics, University of Bath - Claverton Down, Bath, BA2 7AY (United Kingdom); Clem, J R [Ames Laboratory Department of Physics and Astronomy - Iowa State University, Ames, IA 50011-3160 (United States); Tamegai, T, E-mail: mrc61@cam.ac.u [Department of Applied Physics, University of Tokyo - Hongo, Bunkyo-ku, Tokyo 113-8627 (Japan)

2009-03-01

The magnetic properties of a superconducting disk change dramatically when its dimensions become mesoscopic. Unlike large disks, where the screening currents induced by an applied magnetic field are strong enough to force vortices to accumulate in a 'puddle' at the centre, in a mesoscopic disk the interaction between one of these vortices and the edge currents can be comparable to the intervortex repulsion, resulting in a destruction of the ordered triangular vortex lattice structure at the centre. Vortices instead form clusters which adopt polygonal and shell-like structures which exhibit magic number states similar to those of charged particles in a confining potential, and electrons in artificial atoms. We have fabricated mesoscopic high temperature superconducting Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+delta} disks and investigated their magnetic properties using magneto-optical imaging (MOI) and high resolution scanning Hall probe microscopy (SHPM). The temperature dependence of the vortex penetration field measured using MOI is in excellent agreement with models of the thermal excitation of pancake vortices over edge barriers. The growth of the central vortex puddle has been directly imaged using SHPM and magic vortex numbers showing higher stability have been correlated with abrupt jumps in the measured local magnetisation curves.

Dynamic and structural evidence of mesoscopic aggregation in phosphonium ionic liquids

Science.gov (United States)

Cosby, T.; Vicars, Z.; Heres, M.; Tsunashima, K.; Sangoro, J.

2018-05-01

Mesoscopic aggregation in aprotic ionic liquids due to the microphase separation of polar and non-polar components is expected to correlate strongly with the physicochemical properties of ionic liquids and therefore their potential applications. The most commonly cited experimental evidence of such aggregation is the observation of a low-q pre-peak in the x-ray and neutron scattering profiles, attributed to the polarity alternation of polar and apolar phases. In this work, a homologous series of phosphonium ionic liquids with the bis(trifluoromethylsulfonyl)imide anion and systematically varying alkyl chain lengths on the phosphonium cation are investigated by small and wide-angle x-ray scattering, dynamic-mechanical spectroscopy, and broadband dielectric spectroscopy. A comparison of the real space correlation distance corresponding to the pre-peak and the presence or absence of the slow sub-α dielectric relaxation previously associated with the motion of mesoscale aggregates reveals a disruption of mesoscale aggregates with increasing symmetry of the quaternary phosphonium cation. These findings contribute to the broader understanding of the interplay of molecular structures, mesoscale aggregation, and physicochemical properties in aprotic ionic liquids.

Quantum Effect in the Mesoscopic RLC Circuits with a Source

International Nuclear Information System (INIS)

Liu Jianxin; Yan Zhanyuan

2005-01-01

The research work on the quantum effects in mesoscopic circuits has undergone a rapid development recently, however the whole quantum theory of the mesoscopic circuits should consider the discreteness of the electric charge. In this paper, based on the fundamental fact that the electric charge takes discrete values, the finite-difference Schroedinger equation of the mesoscopic RLC circuit with a source is achieved. With a unitary transformation, the Schroedinger equation becomes the standard Mathieu equation, then the energy spectrum and the wave functions of the system are obtained. Using the WKBJ method, the average of currents and square of the current are calculated. The results show the existence of the current fluctuation, which causes noise in the circuits. This paper is an application of the whole quantum mesoscopic circuits theory to the fundamental circuits, and the results will shed light on the design of the miniation circuits, especially on the purpose of reducing quantum noise coherent controlling of the mesoscopic quantum states.

Quantum Effect in a Diode Included Nonlinear Inductance-Capacitance Mesoscopic Circuit

International Nuclear Information System (INIS)

Yan Zhanyuan; Zhang Xiaohong; Ma Jinying

2009-01-01

The mesoscopic nonlinear inductance-capacitance circuit is a typical anharmonic oscillator, due to diodes included in the circuit. In this paper, using the advanced quantum theory of mesoscopic circuits, which based on the fundamental fact that the electric charge takes discrete value, the diode included mesoscopic circuit is firstly studied. Schroedinger equation of the system is a four-order difference equation in p-circumflex representation. Using the extended perturbative method, the detail energy spectrum and wave functions are obtained and verified, as an application of the results, the current quantum fluctuation in the ground state is calculated. Diode is a basis component in a circuit, its quantization would popularize the quantum theory of mesoscopic circuits. The methods to solve the high order difference equation are helpful to the application of mesoscopic quantum theory.

Mesoscopic photon heat transistor

DEFF Research Database (Denmark)

Ojanen, T.; Jauho, Antti-Pekka

2008-01-01

We show that the heat transport between two bodies, mediated by electromagnetic fluctuations, can be controlled with an intermediate quantum circuit-leading to the device concept of a mesoscopic photon heat transistor (MPHT). Our theoretical analysis is based on a novel Meir-Wingreen-Landauer-typ......We show that the heat transport between two bodies, mediated by electromagnetic fluctuations, can be controlled with an intermediate quantum circuit-leading to the device concept of a mesoscopic photon heat transistor (MPHT). Our theoretical analysis is based on a novel Meir......-Wingreen-Landauer-type of conductance formula, which gives the photonic heat current through an arbitrary circuit element coupled to two dissipative reservoirs at finite temperatures. As an illustration we present an exact solution for the case when the intermediate circuit can be described as an electromagnetic resonator. We discuss...

Modification of the mesoscopic structure in neutron irradiated EPDM viewed through positron annihilation spectroscopy and dynamic mechanical analysis

International Nuclear Information System (INIS)

Lambri, O.A.; Plazaola, F.; Axpe, E.; Mocellini, R.R.; Zelada-Lambri, G.I.; Garcia, J.A.; Matteo, C.L.; Sorichetti, P.A.

2011-01-01

This article focuses on the study of the mesoscopic structure in neutron irradiated EPDM both from experimental and theoretical points of view. In this work we reveal completely the modification of the mesostructure of the EPDM due to neutron irradiation, resolving volume fraction, size and distribution of the crystalline zones as a function of the irradiation dose. Positron annihilation spectroscopy and dynamic mechanical analysis techniques are applied and the results are discussed by means of new theoretical results for describing the interaction process between the crystals and amorphous zones in EPDM.

Ginzburg–Landau theory of mesoscopic multi-band Josephson junctions

Energy Technology Data Exchange (ETDEWEB)

Romeo, F.; De Luca, R., E-mail: rdeluca@unisa.it

2017-05-15

Highlights: • We generalize, in the realm of the Ginzburg–Landau theory, the de Gennes matching-matrix method for the interface order parameters to describe the superconducting properties of multi-band mesoscopic Josephson junctions. • The results are in agreement with a microscopic treatment of nanobridge junctions. • Thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions. - Abstract: A Ginzburg–Landau theory for multi-band mesoscopic Josephson junctions has been developed. The theory, obtained by generalizing the de Gennes matching-matrix method for the interface order parameters, allows the study of the phase dynamics of various types of mesoscopic Josephson junctions. As a relevant application, we studied mesoscopic double-band junctions also in the presence of a superconducting nanobridge interstitial layer. The results are in agreement with a microscopic treatment of the same system. Furthermore, thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions.

Fabrication of mesoscopic floating Si wires by introducing dislocations

International Nuclear Information System (INIS)

Motohashi, Mitsuya; Shimizu, Kazuya; Niwa, Masaaki; Suzuki, Toshiaki

2014-01-01

We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization. (paper)

Fabrication of mesoscopic floating Si wires by introducing dislocations

Science.gov (United States)

Motohashi, Mitsuya; Shimizu, Kazuya; Suzuki, Toshiaki; Niwa, Masaaki

2014-12-01

We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization.

Mesoscopic Community Structure of Financial Markets Revealed by Price and Sign Fluctuations.

Science.gov (United States)

Almog, Assaf; Besamusca, Ferry; MacMahon, Mel; Garlaschelli, Diego

2015-01-01

The mesoscopic organization of complex systems, from financial markets to the brain, is an intermediate between the microscopic dynamics of individual units (stocks or neurons, in the mentioned cases), and the macroscopic dynamics of the system as a whole. The organization is determined by "communities" of units whose dynamics, represented by time series of activity, is more strongly correlated internally than with the rest of the system. Recent studies have shown that the binary projections of various financial and neural time series exhibit nontrivial dynamical features that resemble those of the original data. This implies that a significant piece of information is encoded into the binary projection (i.e. the sign) of such increments. Here, we explore whether the binary signatures of multiple time series can replicate the same complex community organization of the financial market, as the original weighted time series. We adopt a method that has been specifically designed to detect communities from cross-correlation matrices of time series data. Our analysis shows that the simpler binary representation leads to a community structure that is almost identical with that obtained using the full weighted representation. These results confirm that binary projections of financial time series contain significant structural information.

Mesoscopic Community Structure of Financial Markets Revealed by Price and Sign Fluctuations.

Directory of Open Access Journals (Sweden)

Assaf Almog

Full Text Available The mesoscopic organization of complex systems, from financial markets to the brain, is an intermediate between the microscopic dynamics of individual units (stocks or neurons, in the mentioned cases, and the macroscopic dynamics of the system as a whole. The organization is determined by "communities" of units whose dynamics, represented by time series of activity, is more strongly correlated internally than with the rest of the system. Recent studies have shown that the binary projections of various financial and neural time series exhibit nontrivial dynamical features that resemble those of the original data. This implies that a significant piece of information is encoded into the binary projection (i.e. the sign of such increments. Here, we explore whether the binary signatures of multiple time series can replicate the same complex community organization of the financial market, as the original weighted time series. We adopt a method that has been specifically designed to detect communities from cross-correlation matrices of time series data. Our analysis shows that the simpler binary representation leads to a community structure that is almost identical with that obtained using the full weighted representation. These results confirm that binary projections of financial time series contain significant structural information.

Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions

Science.gov (United States)

Magee, N. B.; Miller, A.; Amaral, M.; Cumiskey, A.

2014-11-01

Here we show high-magnification images of hexagonal ice crystals acquired by environmental scanning electron microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions in which rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from -10 °C to -40 °C, in supersaturated and subsaturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomenon interpreted as evidence of 2-D nucleation. New knowledge about the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to supplemental videos of ice growth and sublimation are provided.

Quantum switching of polarization in mesoscopic ferroelectrics

International Nuclear Information System (INIS)

Sa de Melo, C.A.

1996-01-01

A single domain of a uniaxial ferroelectric grain may be thought of as a classical permanent memory. At the mesoscopic level this system may experience considerable quantum fluctuations due to tunneling between two possible memory states, thus destroying the classical permanent memory effect. To study these quantum effects the concrete example of a mesoscopic uniaxial ferroelectric grain is discussed, where the orientation of the electric polarization determines two possible memory states. The possibility of quantum switching of the polarization in mesoscopic uniaxial ferroelectric grains is thus proposed. To determine the degree of memory loss, the tunneling rate between the two polarization states is calculated at zero temperature both in the absence and in the presence of an external static electric field. In addition, a discussion of crossover temperature between thermally activated behavior and quantum tunneling behavior is presented. And finally, environmental effects (phonons, defects, and surfaces) are also considered. copyright 1996 The American Physical Society

Discrete and mesoscopic regimes of finite-size wave turbulence

International Nuclear Information System (INIS)

L'vov, V. S.; Nazarenko, S.

2010-01-01

Bounding volume results in discreteness of eigenmodes in wave systems. This leads to a depletion or complete loss of wave resonances (three-wave, four-wave, etc.), which has a strong effect on wave turbulence (WT) i.e., on the statistical behavior of broadband sets of weakly nonlinear waves. This paper describes three different regimes of WT realizable for different levels of the wave excitations: discrete, mesoscopic and kinetic WT. Discrete WT comprises chaotic dynamics of interacting wave 'clusters' consisting of discrete (often finite) number of connected resonant wave triads (or quarters). Kinetic WT refers to the infinite-box theory, described by well-known wave-kinetic equations. Mesoscopic WT is a regime in which either the discrete and the kinetic evolutions alternate or when none of these two types is purely realized. We argue that in mesoscopic systems the wave spectrum experiences a sandpile behavior. Importantly, the mesoscopic regime is realized for a broad range of wave amplitudes which typically spans over several orders on magnitude, and not just for a particular intermediate level.

Lattice Boltzmann model capable of mesoscopic vorticity computation

Science.gov (United States)

Peng, Cheng; Guo, Zhaoli; Wang, Lian-Ping

2017-11-01

It is well known that standard lattice Boltzmann (LB) models allow the strain-rate components to be computed mesoscopically (i.e., through the local particle distributions) and as such possess a second-order accuracy in strain rate. This is one of the appealing features of the lattice Boltzmann method (LBM) which is of only second-order accuracy in hydrodynamic velocity itself. However, no known LB model can provide the same quality for vorticity and pressure gradients. In this paper, we design a multiple-relaxation time LB model on a three-dimensional 27-discrete-velocity (D3Q27) lattice. A detailed Chapman-Enskog analysis is presented to illustrate all the necessary constraints in reproducing the isothermal Navier-Stokes equations. The remaining degrees of freedom are carefully analyzed to derive a model that accommodates mesoscopic computation of all the velocity and pressure gradients from the nonequilibrium moments. This way of vorticity calculation naturally ensures a second-order accuracy, which is also proven through an asymptotic analysis. We thus show, with enough degrees of freedom and appropriate modifications, the mesoscopic vorticity computation can be achieved in LBM. The resulting model is then validated in simulations of a three-dimensional decaying Taylor-Green flow, a lid-driven cavity flow, and a uniform flow passing a fixed sphere. Furthermore, it is shown that the mesoscopic vorticity computation can be realized even with single relaxation parameter.

Statewide mesoscopic simulation for Wyoming.

Science.gov (United States)

2013-10-01

This study developed a mesoscopic simulator which is capable of representing both city-level and statewide roadway : networks. The key feature of such models are the integration of (i) a traffic flow model which is efficient enough to : scale to larg...

Quantum Transport in Mesoscopic Systems

Indian Academy of Sciences (India)

voltage bias, the tunneling of the electron from the lead to the dot and vice versa will happen very rarely. Then two successive ..... A typical mesoscopic quantum dot system (a small drop- .... dynamical behavior of the distribution function of the.

Mesoscopic model for binary fluids

Science.gov (United States)

Echeverria, C.; Tucci, K.; Alvarez-Llamoza, O.; Orozco-Guillén, E. E.; Morales, M.; Cosenza, M. G.

2017-10-01

We propose a model for studying binary fluids based on the mesoscopic molecular simulation technique known as multiparticle collision, where the space and state variables are continuous, and time is discrete. We include a repulsion rule to simulate segregation processes that does not require calculation of the interaction forces between particles, so binary fluids can be described on a mesoscopic scale. The model is conceptually simple and computationally efficient; it maintains Galilean invariance and conserves the mass and energy in the system at the micro- and macro-scale, whereas momentum is conserved globally. For a wide range of temperatures and densities, the model yields results in good agreement with the known properties of binary fluids, such as the density profile, interface width, phase separation, and phase growth. We also apply the model to the study of binary fluids in crowded environments with consistent results.

Time-dependent photon heat transport through a mesoscopic Josephson device

Energy Technology Data Exchange (ETDEWEB)

Lu, Wen-Ting; Zhao, Hong-Kang, E-mail: zhaohonk@bit.edu.cn

2017-02-15

The time-oscillating photon heat current through a dc voltage biased mesoscopic Josephson Junction (MJJ) has been investigated by employing the nonequilibrium Green’s function approach. The Landauer-like formula of photon heat current has been derived in both of the Fourier space and its time-oscillating versions, where Coulomb interaction, self inductance, and magnetic flux take effective roles. Nonlinear behaviors are exhibited in the photon heat current due to the quantum nature of MJJ and applied external dc voltage. The magnitude of heat current decreases with increasing the external bias voltage, and subtle oscillation structures appear as the superposition of different photon heat branches. The overall period of heat current with respect to time is not affected by Coulomb interaction, however, the magnitude and phase of it vary considerably by changing the Coulomb interaction. - Highlights: • The time-oscillating photon heat current through a mesoscopic Josephson Junction has been investigated. • The Landauer-like formula of photon heat current has been derived by the nonequilibrium Green’s function approach. • Nonlinear behaviors are exhibited in the photon heat current resulting from the self inductance and Coulomb interaction. • The oscillation structure of heat current is composed of the superposition of oscillations with different periods.

Time-dependent photon heat transport through a mesoscopic Josephson device

International Nuclear Information System (INIS)

Lu, Wen-Ting; Zhao, Hong-Kang

2017-01-01

The time-oscillating photon heat current through a dc voltage biased mesoscopic Josephson Junction (MJJ) has been investigated by employing the nonequilibrium Green’s function approach. The Landauer-like formula of photon heat current has been derived in both of the Fourier space and its time-oscillating versions, where Coulomb interaction, self inductance, and magnetic flux take effective roles. Nonlinear behaviors are exhibited in the photon heat current due to the quantum nature of MJJ and applied external dc voltage. The magnitude of heat current decreases with increasing the external bias voltage, and subtle oscillation structures appear as the superposition of different photon heat branches. The overall period of heat current with respect to time is not affected by Coulomb interaction, however, the magnitude and phase of it vary considerably by changing the Coulomb interaction. - Highlights: • The time-oscillating photon heat current through a mesoscopic Josephson Junction has been investigated. • The Landauer-like formula of photon heat current has been derived by the nonequilibrium Green’s function approach. • Nonlinear behaviors are exhibited in the photon heat current resulting from the self inductance and Coulomb interaction. • The oscillation structure of heat current is composed of the superposition of oscillations with different periods.

Fiscal 1997 report on the results of the technical development of super metal under consignment from NEDO. Technology to create ferrous mesoscopic structure control materials; Super metal no gijutsu kaihatsu (tetsukei mesoscopic soshiki seigyo zairyo sosei gijutsu) seika hokokusho (1997 nendo). Shin Energy Sangyo Gijutsu Sogo Kaihatsu Kiko (NEDO) itaku kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-03-01

The fiscal 1997 results were reported of the project on the technical development of super metal which draws out limit performance of ferrous metal and improves the recyclability. In the study of large-strain deformation, a study was carried out with the use of large-strain deformation of more than 50% per 1 pass (strain rate: 0.7 or more) and multi-phase structure. By the crystal microstructuring technology, a level was reached where approximately 1{mu}m crystal size can be obtained. In the study of high magnetic field utilization, the course of study of the structure control and microstructuring was chosen in the preliminary experiment using the existing 8 tesla magnet, and the design and fabrication of a new 12 tesla large-diameter magnet were conducted. In the study of material structure prediction, modeling of microstructuring by recrystallization and establishment of a material predicting method of micro/multi-phase/mixed-grain structures were made the subjects. In the analysis of the mesoscopic structure, the mesoscopic analysis was made of the 0.3C-9Ni steel microstructured by the large-strain deformation thermal processing, and it was shown that the reflective electronic image measured by varying accelerating voltage gives new structural information. 111 refs., 135 figs., 35 tabs.

Mesoscopic approach to describe high burn-up fuel behaviour

International Nuclear Information System (INIS)

Kinoshita, M.

1999-01-01

The grain sub-division and the rim structure formation are new phenomena for LWR fuel engineering. The consequence of these are now under investigation in several international programs such as HBRP (High Burnup Rim Project) of CRIEPI, NFIR of EPRI, and EdF/CEA program in France. The theoretical understanding of this phenomenon is underway. Here, the process is peculiar in the following points; (1) majority of the domain of the material are changed to a new morphology after the restructuring, (2) the final size of the new grains is around 0.1 μm which is neither atomic scale nor macroscopic scale. (3) the morphology of the restructured domain indicates fractal like feature which indicates complex process is under-taken. From the first feature, the process is similar to phase transitions or metallographic transformations. However, as the crystallographic structure has no change before and after the restructuring, it is not the phase transition nor the transformation of atomic scale instability. The focus could be put on the material transport of mesoscopic scale which create the peculiar morphology. Indeed there are flows of energy and disturbances in crystallographic structure in nuclear materials on duty. Although the fission energy is 10 4 larger than the formation energy of the defects, thanks to the stability of the selected material, most of energy is thermalized without crystallographic instability. Little remained energy creates flows of disturbances and the new structure is a consequence of ordering process driven by these flows of disturbances. Therefore this phenomenon is a good example to study cooperative ordering process in physics of materials. This paper presents some of present understandings of the rim structure formation based on the mesoscopic mechanistic theories. Possible future development is also proposed (author) (ml)

A Stochastic mesoscopic model for predicting the globular grain structure and solute redistribution in cast alloys at low superheat

International Nuclear Information System (INIS)

Nastac, Laurentiu; El Kaddah, Nagy

2012-01-01

It is well known that casting at low superheat has a strong influence on the solidification morphology and macro- and microstructures of the cast alloy. This paper describes a stochastic mesoscopic solidification model for predicting the grain structure and segregation in cast alloy at low superheat. This model was applied to predict the globular solidification morphology and size as well as solute redistribution of Al in cast Mg AZ31B alloy at superheat of 5°C produced by the Magnetic Suspension Melting (MSM) process, which is an integrated containerless induction melting and casting process. The castings produced at this low superheat have fine globular grain structure, with an average grain size of 80 μm, which is about 3 times smaller than that obtained by conventional casting techniques. The stochastic model was found to reasonably predict the observed grain structure and Al microsegregation. This makes the model a useful tool for controlling the structure of cast magnesium alloys.

Mesoscopic Rydberg Gate Based on Electromagnetically Induced Transparency

International Nuclear Information System (INIS)

Mueller, M.; Lesanovsky, I.; Zoller, P.; Weimer, H.; Buechler, H. P.

2009-01-01

We demonstrate theoretically a parallelized C-NOT gate which allows us to entangle a mesoscopic ensemble of atoms with a single control atom in a single step, with high fidelity and on a microsecond time scale. Our scheme relies on the strong and long-ranged interaction between Rydberg atoms triggering electromagnetically induced transparency. By this we can robustly implement a conditional transfer of all ensemble atoms between two logical states, depending on the state of the control atom. We outline a many-body interferometer which allows a comparison of two many-body quantum states by performing a measurement of the control atom.

The persistent current and energy spectrum on a driven mesoscopic LC-circuit with Josephson junction

Science.gov (United States)

Pahlavanias, Hassan

2018-03-01

The quantum theory for a mesoscopic electric circuit including a Josephson junction with charge discreteness is studied. By considering coupling energy of the mesoscopic capacitor in Josephson junction device, a Hamiltonian describing the dynamics of a quantum mesoscopic electric LC-circuit with charge discreteness is introduced. We first calculate the persistent current on a quantum driven ring including Josephson junction. Then we obtain the persistent current and energy spectrum of a quantum mesoscopic electrical circuit which includes capacitor, inductor, time-dependent external source and Josephson junction.

The local temperature and chemical potential inside a mesoscopic device driven out of equilibrium

International Nuclear Information System (INIS)

Wang, Pei

2011-01-01

In this paper we introduce a method for calculating the local temperature and chemical potential inside a mesoscopic device out of equilibrium. We show how to check the conditions of local thermal equilibrium when the whole system is out of equilibrium. In particular, we study the on-site chemical potentials inside a chain coupled to two reservoirs at a finite voltage bias. We observe in the presence of disorder a large fluctuation in on-site chemical potentials, which can be suppressed by the electron–electron interaction. By taking the average with respect to the configurations of the disorder, we recover the classical picture where the voltage drops monotonically through the resistance wire. We prove the existence of local intensive variables in a mesoscopic device which is in equilibrium or not far from equilibrium

Magnetic response of superconducting mesoscopic-size YBCO powder

Energy Technology Data Exchange (ETDEWEB)

Deimling, C.V. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)], E-mail: cesard@df.ufscar.br; Motta, M.; Lisboa-Filho, P.N. [Laboratorio de Materiais Supercondutores, Departamento de Fisica, Universidade Estadual Paulista, Bauru, SP Brazil (Brazil); Ortiz, W.A. [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)

2008-07-15

In this work it is reported the magnetic behavior of submicron and mesoscopic-size superconducting YBCO powders, prepared by a modified polymeric precursors method. The grain size and microstructure were analyzed using scanning electron microscopy (SEM). Measurements of magnetization and AC-susceptibility as a function of temperature were performed with a quantum design SQUID magnetometer. Our results indicated significant differences on the magnetic propreties, in connection with the calcination temperature and the pressure used to pelletize the samples. This contribution is part of an effort to study vortex dynamics and magnetic properties of submicron and mesoscopic-size superconducting samples.

Tungsten Oxide Nanofibers Self-assembled Mesoscopic Microspheres as High-performance Electrodes for Supercapacitor

International Nuclear Information System (INIS)

Xu, Juan; Ding, Taotao; Wang, Jin; Zhang, Jun; Wang, Shuai; Chen, Changqing; Fang, Yanyan; Wu, Zhihao; Huo, Kaifu; Dai, Jiangnan

2015-01-01

Highlights: • WO 3 mesoscopic microspheres self-assembled by nanofibers. • Inorganic solvent H 2 O 2 play an integral role in the process of self-assembly. • WO 3 mesoscopic microspheres exhibit specific capacitance value of 797.05 F g −1 at a constant density of 0.5 A g −1 in 2 M H 2 SO 4 aqueous solution. • The WO 3 //AC asymmetric supercapacitor displays a maximum energy density of 97.61 Wh kg −1 and power density of 28.01 kW kg −1 . - Abstract: Mesoscopic WO 3 microspheres composed of self-assembly nanofibers were prepared by hydrothermal reaction of tungsten acid potassium and H 2 O 2 . The mesoscopic WO 3 microspheres offer desired porous properties and large effective active areas provided by intertwining nanofibers, thereby resulting in excellent supercapacitive properties due to facile electrolyte flow and fast reaction kinetics. In three electrode configuration, mesoscopic WO 3 microspheres exhibit specific capacitance value of 797.05 F g −1 at the current density of 0.5 A g −1 and excellent cycling stability without decay after 2000 cycles in 2 M H 2 SO 4 aqueous solution. These values are superior to other reported WO 3 composites. An asymmetric supercapacitor is constructed using the as-prepared WO 3 mesoscopic microspheres as the positive electrode and the activated carbon as the negative electrode, which displays excellent electrochemical performance with a maximum energy density of 97.61 Wh kg −1 and power density of 28.01 kW kg −1 . These impressive performances suggest that the mesoscopic WO 3 microspheres are promising electrode materials for supercapacitor

Mesoscopic approach to modeling elastic-plastic polycrystalline material behaviour

International Nuclear Information System (INIS)

Kovac, M.; Cizelj, L.

2001-01-01

Extreme loadings during severe accident conditions might cause failure or rupture of the pressure boundary of a reactor coolant system. Reliable estimation of the extreme deformations can be crucial to determine the consequences of such an accident. One of important drawbacks of classical continuum mechanics is idealization of inhomogenous microstructure of materials. This paper discusses the mesoscopic approach to modeling the elastic-plastic behavior of a polycrystalline material. The main idea is to divide the continuum (e.g., polycrystalline aggregate) into a set of sub-continua (grains). The overall properties of the polycrystalline aggregate are therefore determined by the number of grains in the aggregate and properties of randomly shaped and oriented grains. The random grain structure is modeled with Voronoi tessellation and random orientations of crystal lattices are assumed. The elastic behavior of monocrystal grains is assumed to be anisotropic. Crystal plasticity is used to describe plastic response of monocrystal grains. Finite element method is used to obtain numerical solutions of strain and stress fields. The analysis is limited to two-dimensional models.(author)

Spin tunnelling in mesoscopic systems

Indian Academy of Sciences (India)

We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the ...

What can we learn from noise? - Mesoscopic nonequilibrium statistical physics.

Science.gov (United States)

Kobayashi, Kensuke

2016-01-01

Mesoscopic systems - small electric circuits working in quantum regime - offer us a unique experimental stage to explorer quantum transport in a tunable and precise way. The purpose of this Review is to show how they can contribute to statistical physics. We introduce the significance of fluctuation, or equivalently noise, as noise measurement enables us to address the fundamental aspects of a physical system. The significance of the fluctuation theorem (FT) in statistical physics is noted. We explain what information can be deduced from the current noise measurement in mesoscopic systems. As an important application of the noise measurement to statistical physics, we describe our experimental work on the current and current noise in an electron interferometer, which is the first experimental test of FT in quantum regime. Our attempt will shed new light in the research field of mesoscopic quantum statistical physics.

Understanding of mechanical properties of graphite on the basis of mesoscopic microstructure (review)

International Nuclear Information System (INIS)

Ishihara, M.; Shibata, T.; Takahashi, T.; Baba, S.; Hoshiya, T.

2002-01-01

With the aim of nuclear application of ceramics in the high-temperature engineering field, the authors have investigated the mesoscopic microstructure related to the mechanical and thermal properties of ceramics. In this paper, recent activities concerning mechanical properties, strength and Young's modulus are presented. In the strength research field, the brittle fracture model considering pore/grain mesoscopic microstructure was expanded so as to render possible an estimation of the strength under stress gradient conditions. Furthermore, the model was expanded to treat the pore/crack interaction effect. The performance of the developed model was investigated from a comparison with experimental data and the Weibull strength theory. In the field of Young's modulus research, ultrasonic wave propagation was investigated using the pore/wave interaction model. Three kinds of interaction modes are treated in the model. The model was applied to the graphite, and its applicability was investigated through comparison with experimental data. (authors)

Coulomb drag in coherent mesoscopic systems

DEFF Research Database (Denmark)

Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka

2001-01-01

We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means, such as th......We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means......, such as the random matrix theory, or by numerical simulations. We show that Coulomb drag is sensitive to localized states. which usual transport measurements do not probe. For chaotic 2D systems we find a vanishing average drag, with a nonzero variance. Disordered 1D wires show a finite drag, with a large variance...

Josephson junction in the quantum mesoscopic electric circuits with charge discreteness

Science.gov (United States)

Pahlavani, H.

2018-04-01

A quantum mesoscopic electrical LC-circuit with charge discreteness including a Josephson junction is considered and a nonlinear Hamiltonian that describing the dynamic of such circuit is introduced. The quantum dynamical behavior (persistent current probability) is studied in the charge and phase regimes by numerical solution approaches. The time evolution of charge and current, number-difference and the bosonic phase and also the energy spectrum of a quantum mesoscopic electric LC-circuit with charge discreteness that coupled with a Josephson junction device are investigated. We show the role of the coupling energy and the electrostatic Coulomb energy of the Josephson junction in description of the quantum behavior and the spectral properties of a quantum mesoscopic electrical LC-circuits with charge discreteness.

Numerical simulation of lubrication mechanisms at mesoscopic scale

DEFF Research Database (Denmark)

Hubert, C.; Bay, Niels; Christiansen, Peter

2011-01-01

The mechanisms of liquid lubrication in metal forming are studied at a mesoscopic scale, adopting a 2D sequential fluid-solid weak coupling approach earlier developed in the first author's laboratory. This approach involves two computation steps. The first one is a fully coupled fluid-structure F...... of pyramidal indentations. The tests are performed with variable reduction and drawing speed under controlled front and back tension forces. Visual observations through a transparent die of the fluid entrapment and escape from the cavities using a CCD camera show the mechanisms of Micro......PlastoHydroDynamic Lubrication (MPHDL) as well as cavity shrinkage due to lubricant compression and escape and strip deformation....

Introduction to wave scattering, localization, and mesoscopic phenomena

CERN Document Server

Sheng, Ping

1995-01-01

This book gives readers a coherent picture of waves in disordered media, including multiple scattered waves. The book is intended to be self-contained, with illustrated problems and solutions at the end of each chapter to serve the double purpose of filling out the technical and mathematical details and giving the students exercises if used as a course textbook.The study of wave behavior in disordered media has applications in:Condensed matter physics (semi and superconductor nanostructures and mesoscopic phenomena)Materials science/analytical chemistry (analysis of composite and crystalline structures and properties)Optics and electronics (microelectronic and optoelectronic devices)Geology (seismic exploration of Earths subsurface)

Many-body effects in the mesoscopic x-ray edge problem

International Nuclear Information System (INIS)

Hentschel, Martina; Roeder, Georg; Ullmo, Denis

2007-01-01

Many-body phenomena, a key interest in the investigation of bulk solid state systems, are studied here in the context of the x-ray edge problem for mesoscopic systems. We investigate the many-body effects associated with the sudden perturbation following the x-ray exciton of a core electron into the conduction band. For small systems with dimensions at the nanoscale we find considerable deviations from the well-understood metallic case where Anderson orthogonality catastrophe and the Mahan-Nozieres-DeDominicis response cause characteristic deviations of the photoabsorption cross section from the naive expectation. Whereas the K-edge is typically rounded in metallic systems, we find a slightly peaked K-edge in generic mesoscopic systems with chaotic-coherent electron dynamics. Thus the behavior of the photoabsorption cross section at threshold depends on the system size and is different for the metallic and the mesoscopic case. (author)

A Mesoscopic Simulation for the Early-Age Shrinkage Cracking Process of High Performance Concrete in Bridge Engineering

Directory of Open Access Journals (Sweden)

Guodong Li

2017-01-01

Full Text Available On a mesoscopic level, high performance concrete (HPC was assumed to be a heterogeneous composite material consisting of aggregates, mortar, and pores. The concrete mesoscopic structure model had been established based on CT image reconstruction. By combining this model with continuum mechanics, damage mechanics, and fracture mechanics, a relatively complete system for concrete mesoscopic mechanics analysis was established to simulate the process of early-age shrinkage cracking in HPC. This process was based on the dispersion crack model. The results indicated that the interface between the aggregate and mortar was the crack point caused by shrinkage cracks in HPC. The locations of early-age shrinkage cracks in HPC were associated with the spacing and the size of the aggregate particle. However, the shrinkage deformation size of the mortar was related to the scope of concrete cracking and was independent of the crack position. Whereas lower water to cement ratios can improve the early strength of concrete, this ratio cannot control early-age shrinkage cracks in HPC.

Mesoscopic simulations of crosslinked polymer networks

NARCIS (Netherlands)

Megariotis, G.; Vogiatzis, G.G.; Schneider, L.; Müller, M.; Theodorou, D.N.

2016-01-01

A new methodology and the corresponding C++ code for mesoscopic simulations of elastomers are presented. The test system, crosslinked ds-1'4-polyisoprene' is simulated with a Brownian Dynamics/kinetic Monte Carlo algorithm as a dense liquid of soft, coarse-grained beads, each representing 5-10 Kuhn

Mesoscopic Length Scale Controls the Rheology of Dense Suspensions

Science.gov (United States)

Bonnoit, Claire; Lanuza, Jose; Lindner, Anke; Clement, Eric

2010-09-01

From the flow properties of dense granular suspensions on an inclined plane, we identify a mesoscopic length scale strongly increasing with volume fraction. When the flowing layer height is larger than this length scale, a diverging Newtonian viscosity is determined. However, when the flowing layer height drops below this scale, we evidence a nonlocal effective viscosity, decreasing as a power law of the flow height. We establish a scaling relation between this mesoscopic length scale and the suspension viscosity. These results support recent theoretical and numerical results implying collective and clustered granular motion when the jamming point is approached from below.

Mesoscopic effects in the quantum Hall regime

Indian Academy of Sciences (India)

. When band mixing between multiple Landau levels is present, mesoscopic effects cause a crossover from a sequence of quantum Hall transitions for weak disorder to classical behavior for strong disorder. This behavior may be of relevance ...

Biomineralization of struvite crystals by Proteus mirabilis from artificial urine and their mesoscopic structure

Energy Technology Data Exchange (ETDEWEB)

Prywer, J. [Institute of Physics, Technical University of Lodz, ul. Wolczanska 219, 93-005 Lodz (Poland); Torzewska, A. [Department of Immunobiology of Bacteria, Institute of Microbiology, Biotechnology and Immunology, University of Lodz, ul. Banacha 12/16, 90-237 Lodz (Poland)

2010-12-15

In order to investigate the mineralization of struvite we performed the experiment of struvite growth process from artificial urine. The crystallization process was induced by Proteus mirabilis, as these bacteria are mainly isolated from infectious stones. The crystallization process occurred at conditions mimicking the real urinary tract infection. Our results show that struvite exhibits polar properties. This feature of struvite crystals is potentially very important in the case of binding additives which may either enhance or inhibit crystallization process. It seems also that the differences in the polarity of opposite faces of c-axis play important role in directing the struvite mesoscopic arrangement. We also described recent developments concerning curcumin - pigment extracted from the roots of turmeric commonly known as a spice added to various food preparations. Curcumin exhibited the effect against Proteus mirabilis inhibiting the activity of urease and consequently decreasing the efficiency of struvite growth. Therefore, curcumin belongs to phytoterapheutic components, which may be the alternative with relation to the antibiotic therapy. The paper concludes with a future outlook and goals in this field of research. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Quantum fluctuations in mesoscopic and macroscopic systems

International Nuclear Information System (INIS)

Cerdeira, H.A.; Guinea Lopez, F.; Weiss, U.

1991-01-01

The conference presentations have been grouped in three chapters; Quantum Transport (4 papers), Dissipation in Discrete Systems (7 papers) and Mesoscopic Junction, Rings and Arrays (6 papers). A separate abstract was prepared for each paper. Refs and figs

Coherent X-ray diffraction studies of mesoscopic materials

International Nuclear Information System (INIS)

Shabalin, Anatoly

2015-12-01

This thesis is devoted to three separate projects, which can be considered as independent. First, the dynamical scattering effects in the Coherent X-ray Diffractive Imaging (CXDI) method are discussed. Based on the simulation results, a straightforward method for correction for the refraction and absorption artifacts in the Bragg CXDI reconstruction is suggested. The second part summarizes the results of an Coherent X-ray Diffractive Imaging experiment with a single colloidal crystal grain. A remarkable result is that positions of individual particles in the crystal lattice have been resolved in three dimensions. The third project is devoted to X-ray diffraction experimental studies of structural evolution of colloidal crystalline films upon incremental heating. Based on the results of the analysis a model of structural evolution of a colloidal crystal upon heating on nanoscopic and mesoscopic length scales is suggested.

Probabilistic simulation of mesoscopic “Schrödinger cat” states

Energy Technology Data Exchange (ETDEWEB)

Opanchuk, B.; Rosales-Zárate, L.; Reid, M.D.; Drummond, P.D., E-mail: pdrummond@swin.edu.au

2014-02-01

We carry out probabilistic phase-space sampling of mesoscopic Schrödinger cat quantum states, demonstrating multipartite Bell violations for up to 60 qubits. We use states similar to those generated in photonic and ion-trap experiments. These results show that mesoscopic quantum superpositions are directly accessible to probabilistic sampling, and we analyze the properties of sampling errors. We also demonstrate dynamical simulation of super-decoherence in ion traps. Our computer simulations can be either exponentially faster or slower than experiment, depending on the correlations measured.

Mesoscopic segregation of excitation and inhibition in a brain network model.

Directory of Open Access Journals (Sweden)

Daniel Malagarriga

2015-02-01

Full Text Available Neurons in the brain are known to operate under a careful balance of excitation and inhibition, which maintains neural microcircuits within the proper operational range. How this balance is played out at the mesoscopic level of neuronal populations is, however, less clear. In order to address this issue, here we use a coupled neural mass model to study computationally the dynamics of a network of cortical macrocolumns operating in a partially synchronized, irregular regime. The topology of the network is heterogeneous, with a few of the nodes acting as connector hubs while the rest are relatively poorly connected. Our results show that in this type of mesoscopic network excitation and inhibition spontaneously segregate, with some columns acting mainly in an excitatory manner while some others have predominantly an inhibitory effect on their neighbors. We characterize the conditions under which this segregation arises, and relate the character of the different columns with their topological role within the network. In particular, we show that the connector hubs are preferentially inhibitory, the more so the larger the node's connectivity. These results suggest a potential mesoscale organization of the excitation-inhibition balance in brain networks.

PREFACE: Advanced many-body and statistical methods in mesoscopic systems

Science.gov (United States)

Anghel, Dragos Victor; Sabin Delion, Doru; Sorin Paraoanu, Gheorghe

2012-02-01

It has increasingly been realized in recent times that the borders separating various subfields of physics are largely artificial. This is the case for nanoscale physics, physics of lower-dimensional systems and nuclear physics, where the advanced techniques of many-body theory developed in recent times could provide a unifying framework for these disciplines under the general name of mesoscopic physics. Other fields, such as quantum optics and quantum information, are increasingly using related methods. The 6-day conference 'Advanced many-body and statistical methods in mesoscopic systems' that took place in Constanta, Romania, between 27 June and 2 July 2011 was, we believe, a successful attempt at bridging an impressive list of topical research areas: foundations of quantum physics, equilibrium and non-equilibrium quantum statistics/fractional statistics, quantum transport, phases and phase transitions in mesoscopic systems/superfluidity and superconductivity, quantum electromechanical systems, quantum dissipation, dephasing, noise and decoherence, quantum information, spin systems and their dynamics, fundamental symmetries in mesoscopic systems, phase transitions, exactly solvable methods for mesoscopic systems, various extension of the random phase approximation, open quantum systems, clustering, decay and fission modes and systematic versus random behaviour of nuclear spectra. This event brought together participants from seventeen countries and five continents. Each of the participants brought considerable expertise in his/her field of research and, at the same time, was exposed to the newest results and methods coming from the other, seemingly remote, disciplines. The talks touched on subjects that are at the forefront of topical research areas and we hope that the resulting cross-fertilization of ideas will lead to new, interesting results from which everybody will benefit. We are grateful for the financial and organizational support from IFIN-HH, Ovidius

Mesoscopic Modeling and Simulation of the Dynamic Tensile Behavior of Concrete

DEFF Research Database (Denmark)

Pedersen, Ronnie; Simone, A.; Sluys, L. J.

2013-01-01

of the most significant constitutive model parameters on global and local response. Different distributions and shapes of the aggregate grains are tested. Three model parameter sets, corresponding to different moisture conditions, are employed in the analysis of two specimens in which the applied loading rate......We present a two-dimensional mesoscopic finite element model for simulating the rate- and moisture-dependent material behavior of concrete. The idealized mesostructure consists of aggregate grains surrounded by an interfacial transition zone embedded in the bulk material. We examine the influence...

Transmission gaps, trapped modes and Fano resonances in Aharonov-Bohm connected mesoscopic loops

Science.gov (United States)

Mrabti, T.; Labdouti, Z.; El Abouti, O.; El Boudouti, E. H.; Fethi, F.; Djafari-Rouhani, B.

2018-03-01

A simple mesoscopic structure consisting of a double symmetric loops coupled by a segment of length d0 in the presence of an Aharonov-Bohm flux is designed to obtain transmission band gaps and Fano resonances. A general analytical expression for the transmission coefficient and the density of states (DOS) are obtained for various systems of this kind within the framework of the Green's function method in the presence of the magnetic flux. In this work, the amplitude of the transmission and DOS are discussed as a function of the wave vector. We show that the transmission spectrum of the whole structure may exhibit a band gap and a resonance of Fano type without introducing any impurity in one arm of the loop. In particular, we show that for specific values of the magnetic flux and the lengths of the arms constituting the loops, the Fano resonance collapses giving rise to the so-called trapped states or bound in continuum (BIC) states. These states appear when the width of the Fano resonance vanishes in the transmission coefficient as well as in the density of states. Also, we show that the shape of the Fano resonances and the width of the band gaps are very sensitive to the value of the magnetic flux and the geometry of the structure. These results may have important applications for electronic transport in mesoscopic systems.

Elastic tunneling identification through crossings, anti-crossings and splitting of states in the complex electronic current of systems based on mesoscopic molecules

Science.gov (United States)

López, Luis I. A.; Mendoza, Michel; Ujevic, Sebastian

2013-09-01

We have systematically studied the conductance σ( E,B) and the electronic current line shapes J( V ex ) through complex mesoscopic molecules in an elastic resonant tunneling regime. The studied systems are based on GaAs/AlGaAs hetero-structures, with several discrete states in each coupled mesoscopic molecule. The molecules were formed using different wells and barrier widths. These systems allow effective couplings and uncouplings that lead to elastic processes as a function of the electronic potential V ex and magnetic field B. In this situation, the J( V ex ) and σ( E, B) curves exhibit a sequence of peaks of difficult interpretation, in which crossings and anti-crossings (a splitting if it is generated in the resonance condition) of states contribute in a way that they cannot be easily identified. Performing a systematic analysis of the evolution of these states (before the resonance condition), we were able to determine the origin of these current peaks. We have found that the coupling of states (anti-crossing) around the resonance region can be identified as a broad mirrored- D line shape in the J( V ex ) curves. The mirrored- D line shape peaks can be clearly differentiated from the neighboring peaks because the last ones follow a very defined increasing sequence in their intensities and widths. Also, this behavior (fingerprint) can be used to identify possible splitting of states in the J( V ex ). The splittings that are generated between states with different quantum numbers (quantum numbers associated to the individual well) follow an unexpected opposite behavior when compared with those generated between states with the same quantum numbers (quasi-miniband). All these results are also observed in the conductance σ( E, B) associated with complex mesoscopic molecules based on a two-dimensional electron gas.

Quantum Effects of Mesoscopic Inductance and Capacity Coupling Circuits

International Nuclear Information System (INIS)

Liu Jianxin; Yan Zhanyuan; Song Yonghua

2006-01-01

Using the quantum theory for a mesoscopic circuit based on the discretenes of electric charges, the finite-difference Schroedinger equation of the non-dissipative mesoscopic inductance and capacity coupling circuit is achieved. The Coulomb blockade effect, which is caused by the discreteness of electric charges, is studied. Appropriately choose the components in the circuits, the finite-difference Schroedinger equation can be divided into two Mathieu equations in p-circumflex representation. With the WKBJ method, the currents quantum fluctuations in the ground states of the two circuits are calculated. The results show that the currents quantum zero-point fluctuations of the two circuits are exist and correlated.

Effect of mesoscopic fluctuations on equation of state in cluster-forming systems

Directory of Open Access Journals (Sweden)

A. Ciach

2012-06-01

Full Text Available Equation of state for systems with particles self-assembling into aggregates is derived within a mesoscopic theory combining density functional and field-theoretic approaches. We focus on the effect of mesoscopic fluctuations in the disordered phase. The pressure - volume fraction isotherms are calculated explicitly for two forms of the short-range attraction long-range repulsion potential. Mesoscopic fluctuations lead to an increased pressure in each case, except for very small volume fractions. When large clusters are formed, the mechanical instability of the system is present at much higher temperature than found in mean-field approximation. In this case phase separation competes with the formation of periodic phases (colloidal crystals. In the case of small clusters, no mechanical instability associated with separation into dilute and dense phases appears.

Differences between application of some basic principles of quantum mechanics on atomic and mesoscopic levels

OpenAIRE

Nikulov, Alexey

2005-01-01

Formalism of the quantum mechanics developed for microscopic (atomic) level comes into collision with some logical difficulties on mesoscopic level. Some fundamental differences between application of its basic principles on microscopic and mesoscopic levels are accentuated.

Robust mesoscopic superposition of strongly correlated ultracold atoms

International Nuclear Information System (INIS)

Hallwood, David W.; Ernst, Thomas; Brand, Joachim

2010-01-01

We propose a scheme to create coherent superpositions of annular flow of strongly interacting bosonic atoms in a one-dimensional ring trap. The nonrotating ground state is coupled to a vortex state with mesoscopic angular momentum by means of a narrow potential barrier and an applied phase that originates from either rotation or a synthetic magnetic field. We show that superposition states in the Tonks-Girardeau regime are robust against single-particle loss due to the effects of strong correlations. The coupling between the mesoscopically distinct states scales much more favorably with particle number than in schemes relying on weak interactions, thus making particle numbers of hundreds or thousands feasible. Coherent oscillations induced by time variation of parameters may serve as a 'smoking gun' signature for detecting superposition states.

Mesoscopic phenomena in solids

CERN Document Server

Altshuler, BL; Webb, RA

1991-01-01

The physics of disordered systems has enjoyed a resurgence of interest in the last decade. New concepts such as weak localization, interaction effects and Coulomb gap, have been developed for the transport properties of metals and insulators. With the fabrication of smaller and smaller samples and the routine availability of low temperatures, new physics has emerged from the studies of small devices. The new field goes under the name ""mesoscopic physics"" and has rapidly developed, both experimentally and theoretically. This book is designed to review the current status of the field.

Graphene Foam: Uniaxial Tension Behavior and Fracture Mode Based on a Mesoscopic Model.

Science.gov (United States)

Pan, Douxing; Wang, Chao; Wang, Tzu-Chiang; Yao, Yugui

2017-09-26

Because of the combined advantages of both porous materials and two-dimensional (2D) graphene sheets, superior mechanical properties of three-dimensional (3D) graphene foams have received much attention from material scientists and energy engineers. Here, a 2D mesoscopic graphene model (Modell. Simul. Mater. Sci. Eng. 2011, 19, 054003), was expanded into a 3D bonded graphene foam system by utilizing physical cross-links and van der Waals forces acting among different mesoscopic graphene flakes by considering the debonding behavior, to evaluate the uniaxial tension behavior and fracture mode based on in situ SEM tensile testing (Carbon 2015, 85, 299). We reasonably reproduced a multipeak stress-strain relationship including its obvious yielding plateau and a ductile fracture mode near 45° plane from the tensile direction including the corresponding fracture morphology. Then, a power scaling law of tensile elastic modulus with mass density and an anisotropic strain-dependent Poisson's ratio were both deduced. The mesoscopic physical mechanism of tensile deformation was clearly revealed through the local stress state and evolution of mesostructure. The fracture feature of bonded graphene foam and its thermodynamic state were directly navigated to the tearing pattern of mesoscopic graphene flakes. This study provides an effective way to understand the mesoscopic physical nature of 3D graphene foams, and hence it may contribute to the multiscale computations of micro/meso/macromechanical performances and optimal design of advanced graphene-foam-based materials.

Analysis of fluid lubrication mechanisms in metal forming at mesoscopic scale

DEFF Research Database (Denmark)

Dubar, L.; Hubert, C.; Christiansen, Peter

2012-01-01

The lubricant entrapment and escape phenomena in metal forming are studied experimentally as well as numerically. Experiments are carried out in strip reduction of aluminium sheet applying a transparent die to study the fluid flow between mesoscopic cavities. The numerical analysis involves two...... computation steps. The first one is a fully coupled fluid-structure Finite Element computation, where pockets in the surface are plastically deformed leading to the pressurization of the entrapped fluid. The second step computes the fluid exchange between cavities through the plateaus of asperity contacts...

Mesoscopic and continuum modelling of angiogenesis

KAUST Repository

Spill, F.; Guerrero, P.; Alarcon, T.; Maini, P. K.; Byrne, H. M.

2014-01-01

Angiogenesis is the formation of new blood vessels from pre-existing ones in response to chemical signals secreted by, for example, a wound or a tumour. In this paper, we propose a mesoscopic lattice-based model of angiogenesis, in which processes that include proliferation and cell movement are considered as stochastic events. By studying the dependence of the model on the lattice spacing and the number of cells involved, we are able to derive the deterministic continuum limit of our equations and compare it to similar existing models of angiogenesis. We further identify conditions under which the use of continuum models is justified, and others for which stochastic or discrete effects dominate. We also compare different stochastic models for the movement of endothelial tip cells which have the same macroscopic, deterministic behaviour, but lead to markedly different behaviour in terms of production of new vessel cells. © 2014 Springer-Verlag Berlin Heidelberg.

Mesoscopic and continuum modelling of angiogenesis

KAUST Repository

Spill, F.

2014-03-11

Angiogenesis is the formation of new blood vessels from pre-existing ones in response to chemical signals secreted by, for example, a wound or a tumour. In this paper, we propose a mesoscopic lattice-based model of angiogenesis, in which processes that include proliferation and cell movement are considered as stochastic events. By studying the dependence of the model on the lattice spacing and the number of cells involved, we are able to derive the deterministic continuum limit of our equations and compare it to similar existing models of angiogenesis. We further identify conditions under which the use of continuum models is justified, and others for which stochastic or discrete effects dominate. We also compare different stochastic models for the movement of endothelial tip cells which have the same macroscopic, deterministic behaviour, but lead to markedly different behaviour in terms of production of new vessel cells. © 2014 Springer-Verlag Berlin Heidelberg.

Core–shell heterostructured metal oxide arrays enable superior light-harvesting and hysteresis-free mesoscopic perovskite solar cells

KAUST Repository

Mahmood, Khalid; Swain, Bhabani Sankar; Amassian, Aram

2015-01-01

To achieve highly efficient mesoscopic perovskite solar cells (PSCs), the structure and properties of an electron transport layer (ETL) or material (ETM) have been shown to be of supreme importance. Particularly, the core-shell heterostructured mesoscopic ETM architecture has been recognized as a successful electrode design, because of its large internal surface area, superior light-harvesting efficiency and its ability to achieve fast charge transport. Here we report the successful fabrication of a hysteresis-free, 15.3% efficient PSC using vertically aligned ZnO nanorod/TiO2 shell (ZNR/TS) core-shell heterostructured ETMs for the first time. We have also added a conjugated polyelectrolyte polymer into the growth solution to promote the growth of high aspect ratio (AR) ZNRs and substantially improve the infiltration of the perovskite light absorber into the ETM. The PSCs based on the as-synthesized core-shell ZnO/TiO2 heterostructured ETMs exhibited excellent performance enhancement credited to the superior light harvesting capability, larger surface area, prolonged charge-transport pathways and lower recombination rate. The unique ETM design together with minimal hysteresis introduces core-shell ZnO/TiO2 heterostructures as a promising mesoscopic electrode approach for the fabrication of efficient PSCs. This journal is © The Royal Society of Chemistry.

Manipulating mesoscopic multipartite entanglement with atom-light interfaces

International Nuclear Information System (INIS)

Stasinska, J.; Rodo, C.; Paganelli, S.; Birkl, G.; Sanpera, A.

2009-01-01

Entanglement between two macroscopic atomic ensembles induced by measurement on an ancillary light system has proven to be a powerful method for engineering quantum memories and quantum state transfer. Here we investigate the feasibility of such methods for generation, manipulation, and detection of genuine multipartite entanglement (Greenberger-Horne-Zeilinger and clusterlike states) between mesoscopic atomic ensembles without the need of individual addressing of the samples. Our results extend in a nontrivial way the Einstein-Podolsky-Rosen entanglement between two macroscopic gas samples reported experimentally in [B. Julsgaard, A. Kozhekin, and E. Polzik, Nature (London) 413, 400 (2001)]. We find that under realistic conditions, a second orthogonal light pulse interacting with the atomic samples, can modify and even reverse the entangling action of the first one leaving the samples in a separable state.

Mesoscopic Iron-Oxide Nanorod Polymer Nanocomposite Films

Science.gov (United States)

Ferrier, Robert; Ohno, Kohji; Composto, Russell

2012-02-01

Dispersion of nanostructures in polymer matrices is required in order to take advantage of the unique properties of the nano-sized filler. This work investigates the dispersion of mesoscopic (200 nm long) iron-oxide rods (FeNRs) grafted with poly(methyl methacrylate) (PMMA) brushes having molecular weights (MWs) of 3.7K, 32K and 160K. These rods were then dispersed in either a poly(methyl methacrylate) or poly(oxyethylene) (PEO) matrix film so that the matrix/brush interaction is either entropic (PMMA matrix) or enthalpic and entropic (PEO matrix). Transmission electron microscopy (TEM) was used to determine the dispersion of the FeNRs in the polymer matrix. The results show that the FeNRs with the largest brush were always dispersed in the matrix, whereas the rods with the shorter brushes always aggregated in the matrix. This suggests that the brush MW is a critical parameter to achieve dispersion of these mesoscopic materials. This work can be extended to understand the dispersion of other types of mesocopic particles

Flux structures in mesoscopic Y Ba2Cu3O7-δ discs

International Nuclear Information System (INIS)

Crisan, A; Bending, S J; Pross, A; Aziz, A; Grigorenko, A N; Humphreys, R G

2005-01-01

Scanning Hall probe microscopy has been used to study flux structures and dynamics in 5 μm x 5 μm YBCO thin film squares, which are mesoscopic with respect to the magnetic penetration depth, λ(T), at temperatures close to T c . A number of unusual vortex phenomena are observed in these microstructures which differ qualitatively from the expected behaviour of more macroscopic pieces of film. In field-cooled (FC) experiments to ∼65K a full Meissner state is generated for cooling fields less than ∼6 Oe, reflecting the relatively small demagnetization factors in our samples. Cooling in higher fields, however, results in only a very weak diamagnetic response at low temperatures whose magnitude is almost independent of the cooling field. In contrast we observe considerable trapped flux upon field-removal whose magnitude grows monotonically with cooling field. Remarkably, all FC flux distributions exhibit almost perfect rotational symmetry, and can be nearly completely cancelled in a reversible fashion by tuning the field applied to the initially FC state. Our field-cooled and zero-field-cooled results have been analysed in terms of a Bean-like critical state model containing constant edge and bulk current densities, and most of the observed phenomena can be explained by considering the relative weight of these two components. Not all flux profiles can be described by our simple model, however, and under certain circumstances symmetry-breaking 'dipole'-like flux structures can form in several adjacent YBCO squares. We speculate that these are related to the unidirectional Ar ion milling process which was used to pattern the squares and could have broken the expected four-fold symmetry. We note that our results could have important implications for the miniaturization of thin film HTS devices

Mesoscopic fluctuations in the critical current in InAs-coupled Josephson junctions

International Nuclear Information System (INIS)

Takayanagi, Hideaki; Hansen, J.B.; Nitta, Junsaku

1994-01-01

Mesoscopic fluctuations were confirmed for the critical current in a p-type InAs-coupled Josephson junction. The critical current was measured as a function of the gate voltage corresponding to the change in the Fermi energy. The critical current showed a mesoscopic fluctuation and its behavior was the same as that of the conductance measured at the same time in both the weak and strong localization regimes. The magnitude and the typical period of the fluctuation are discussed and compared to theoretical predictions. ((orig.))

Mesoscopic modeling and parameter estimation of a lithium-ion battery based on LiFePO4/graphite

Science.gov (United States)

Jokar, Ali; Désilets, Martin; Lacroix, Marcel; Zaghib, Karim

2018-03-01

A novel numerical model for simulating the behavior of lithium-ion batteries based on LiFePO4(LFP)/graphite is presented. The model is based on the modified Single Particle Model (SPM) coupled to a mesoscopic approach for the LFP electrode. The model comprises one representative spherical particle as the graphite electrode, and N LFP units as the positive electrode. All the SPM equations are retained to model the negative electrode performance. The mesoscopic model rests on non-equilibrium thermodynamic conditions and uses a non-monotonic open circuit potential for each unit. A parameter estimation study is also carried out to identify all the parameters needed for the model. The unknown parameters are the solid diffusion coefficient of the negative electrode (Ds,n), reaction-rate constant of the negative electrode (Kn), negative and positive electrode porosity (εn&εn), initial State-Of-Charge of the negative electrode (SOCn,0), initial partial composition of the LFP units (yk,0), minimum and maximum resistance of the LFP units (Rmin&Rmax), and solution resistance (Rcell). The results show that the mesoscopic model can simulate successfully the electrochemical behavior of lithium-ion batteries at low and high charge/discharge rates. The model also describes adequately the lithiation/delithiation of the LFP particles, however, it is computationally expensive compared to macro-based models.

Mesoscopic Fluctuations for the Thinned Circular Unitary Ensemble

Science.gov (United States)

Berggren, Tomas; Duits, Maurice

2017-09-01

In this paper we study the asymptotic behavior of mesoscopic fluctuations for the thinned Circular Unitary Ensemble. The effect of thinning is that the eigenvalues start to decorrelate. The decorrelation is stronger on the larger scales than on the smaller scales. We investigate this behavior by studying mesoscopic linear statistics. There are two regimes depending on the scale parameter and the thinning parameter. In one regime we obtain a CLT of a classical type and in the other regime we retrieve the CLT for CUE. The two regimes are separated by a critical line. On the critical line the limiting fluctuations are no longer Gaussian, but described by infinitely divisible laws. We argue that this transition phenomenon is universal by showing that the same transition and their laws appear for fluctuations of the thinned sine process in a growing box. The proofs are based on a Riemann-Hilbert problem for integrable operators.

Formulation of a Mesoscopic Electron Beam Splitter with Application in Semiconductor Based Quantum Computing

OpenAIRE

Shanker, A.; Bhowmik, D.; Bhattacharya, T. K.

2010-01-01

We aim to analytically arrive at a beam splitter formulation for electron waves. The electron beam splitter is an essential component of quantum logical devices. To arrive at the beam splitter structure, the electrons are treated as waves, i.e. we assume the transport to be ballistic. Ballistic electrons are electrons that travel over such short distances that their phase coherence is maintained. For mesoscopic devices with size smaller than the mean free path, the phase relaxation length and...

Segment-scale, force-level theory of mesoscopic dynamic localization and entropic elasticity in entangled chain polymer liquids

Science.gov (United States)

Dell, Zachary E.; Schweizer, Kenneth S.

2017-04-01

We develop a segment-scale, force-based theory for the breakdown of the unentangled Rouse model and subsequent emergence of isotropic mesoscopic localization and entropic elasticity in chain polymer liquids in the absence of ergodicity-restoring anisotropic reptation or activated hopping motion. The theory is formulated in terms of a conformational N-dynamic-order-parameter generalized Langevin equation approach. It is implemented using a universal field-theoretic Gaussian thread model of polymer structure and closed at the level of the chain dynamic second moment matrix. The physical idea is that the isotropic Rouse model fails due to the dynamical emergence, with increasing chain length, of time-persistent intermolecular contacts determined by the combined influence of local uncrossability, long range polymer connectivity, and a self-consistent treatment of chain motion and the dynamic forces that hinder it. For long chain melts, the mesoscopic localization length (identified as the tube diameter) and emergent entropic elasticity predictions are in near quantitative agreement with experiment. Moreover, the onset chain length scales with the semi-dilute crossover concentration with a realistic numerical prefactor. Distinctive novel predictions are made for various off-diagonal correlation functions that quantify the full spatial structure of the dynamically localized polymer conformation. As the local excluded volume constraint and/or intrachain bonding spring are softened to allow chain crossability, the tube diameter is predicted to swell until it reaches the radius-of-gyration at which point mesoscopic localization vanishes in a discontinuous manner. A dynamic phase diagram for such a delocalization transition is constructed, which is qualitatively consistent with simulations and the classical concept of a critical entanglement degree of polymerization.

Mesoscopic organization reveals the constraints governing Caenorhabditis elegans nervous system.

Directory of Open Access Journals (Sweden)

Raj Kumar Pan

Full Text Available One of the biggest challenges in biology is to understand how activity at the cellular level of neurons, as a result of their mutual interactions, leads to the observed behavior of an organism responding to a variety of environmental stimuli. Investigating the intermediate or mesoscopic level of organization in the nervous system is a vital step towards understanding how the integration of micro-level dynamics results in macro-level functioning. The coordination of many different co-occurring processes at this level underlies the command and control of overall network activity. In this paper, we have considered the somatic nervous system of the nematode Caenorhabditis elegans, for which the entire neuronal connectivity diagram is known. We focus on the organization of the system into modules, i.e., neuronal groups having relatively higher connection density compared to that of the overall network. We show that this mesoscopic feature cannot be explained exclusively in terms of considerations such as, optimizing for resource constraints (viz., total wiring cost and communication efficiency (i.e., network path length. Even including information about the genetic relatedness of the cells cannot account for the observed modular structure. Comparison with other complex networks designed for efficient transport (of signals or resources implies that neuronal networks form a distinct class. This suggests that the principal function of the network, viz., processing of sensory information resulting in appropriate motor response, may be playing a vital role in determining the connection topology. Using modular spectral analysis we make explicit the intimate relation between function and structure in the nervous system. This is further brought out by identifying functionally critical neurons purely on the basis of patterns of intra- and inter-modular connections. Our study reveals how the design of the nervous system reflects several constraints, including

Combining molecular dynamics with mesoscopic Green’s function reaction dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Vijaykumar, Adithya, E-mail: vijaykumar@amolf.nl [FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands); van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam (Netherlands); Bolhuis, Peter G. [van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam (Netherlands); Rein ten Wolde, Pieter, E-mail: p.t.wolde@amolf.nl [FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands)

2015-12-07

In many reaction-diffusion processes, ranging from biochemical networks, catalysis, to complex self-assembly, the spatial distribution of the reactants and the stochastic character of their interactions are crucial for the macroscopic behavior. The recently developed mesoscopic Green’s Function Reaction Dynamics (GFRD) method enables efficient simulation at the particle level provided the microscopic dynamics can be integrated out. Yet, many processes exhibit non-trivial microscopic dynamics that can qualitatively change the macroscopic behavior, calling for an atomistic, microscopic description. We propose a novel approach that combines GFRD for simulating the system at the mesoscopic scale where particles are far apart, with a microscopic technique such as Langevin dynamics or Molecular Dynamics (MD), for simulating the system at the microscopic scale where reactants are in close proximity. This scheme defines the regions where the particles are close together and simulated with high microscopic resolution and those where they are far apart and simulated with lower mesoscopic resolution, adaptively on the fly. The new multi-scale scheme, called MD-GFRD, is generic and can be used to efficiently simulate reaction-diffusion systems at the particle level.

Combining molecular dynamics with mesoscopic Green’s function reaction dynamics simulations

International Nuclear Information System (INIS)

Vijaykumar, Adithya; Bolhuis, Peter G.; Rein ten Wolde, Pieter

2015-01-01

In many reaction-diffusion processes, ranging from biochemical networks, catalysis, to complex self-assembly, the spatial distribution of the reactants and the stochastic character of their interactions are crucial for the macroscopic behavior. The recently developed mesoscopic Green’s Function Reaction Dynamics (GFRD) method enables efficient simulation at the particle level provided the microscopic dynamics can be integrated out. Yet, many processes exhibit non-trivial microscopic dynamics that can qualitatively change the macroscopic behavior, calling for an atomistic, microscopic description. We propose a novel approach that combines GFRD for simulating the system at the mesoscopic scale where particles are far apart, with a microscopic technique such as Langevin dynamics or Molecular Dynamics (MD), for simulating the system at the microscopic scale where reactants are in close proximity. This scheme defines the regions where the particles are close together and simulated with high microscopic resolution and those where they are far apart and simulated with lower mesoscopic resolution, adaptively on the fly. The new multi-scale scheme, called MD-GFRD, is generic and can be used to efficiently simulate reaction-diffusion systems at the particle level

Magnetofingerprints of superconducting films: Vortex dynamics and mesoscopic-scale disorder

International Nuclear Information System (INIS)

Nowak, E.R.; Israeloff, N.E.; Goldman, A.M.

1994-01-01

The variations of voltage and voltage noise with magnetic field in c-axis-oriented DyBa 2 Cu 3 O 7-δ thin films exhibit reproducible, microstructure-dependent ''magnetofingerprints'' (MF's). The MF's can be scrambled with the reversal of the direction of the Lorentz force on field-induced vortices. Analysis of the noise suggests a strong dependence of the local free-energy landscape on vortex density similar to global frustration effects found in periodic superconducting networks. Above fields which roughly match vortex separation with mesoscopic-scale disorder in the films the noise and the fine structure of the MF's are suppressed, suggesting a crossover to a more weakly pinned vortex-liquid regime

Theory and modeling of spin-transport on the microscopic and the mesoscopic scale

International Nuclear Information System (INIS)

Stickler, B.

2013-01-01

It is the aim of this thesis to contribute to the description of spin dynamics in solid state systems. In the first part of this work we present a full quantum treatment of spin-coherent transport in halfmetal / semiconductor CrAs / GaAs heterostructures. The theoretical approach is based on the ab-initio determination of the electronic structures of the materials involved and on the calculation of the band offset. These ingredients are in the second step cast into an effective nearest-neighbor tight-binding Hamiltonian. Finally, in the third step, we investigate by means of the non-equilibrium Green's function technique the current which flows through such a heterostructure if a finite bias is applied. With the help of this strategy it is possible to identify CrAs / GaAs heterostructures as probable candidates for all-semiconductor room-temperature spin-filtering devices, which operate without externally applied magnetic fields. In the second part of this thesis we derive a linear semiclassical spinorial Boltzmann equation. For many (mesoscopic) device geometries a full quantum treatment of transport dynamics may not be necessary and may not be feasible with state-of-the-art techniques. The derivation is based on the quantum mechanical description of a composite quantum system by means of von Neumann's equation. The Born-Markov limit allows us to derive a Lindblad master equation for the reduced system plus non-Markovian corrections. Finally, we perform a Wigner transformation and take the semiclassical limit in order to obtain a spinorial Boltzmann equation, suitable for the description of spin transport on the mesoscopic scale. It has to be emphasized that the spinorial Boltzmann equation constitutes the missing link between a full quantum treatment and heuristically introduced mesoscopic models for spin transport in solid state systems. (author) [de

Role of mesoscopic morphology in charge transport of doped ...

Indian Academy of Sciences (India)

In doped polyaniline (PANI), the charge transport properties are determined by mesoscopic morphology, which in turn is controlled by the molecular recognition interactions among polymer chain, dopant and solvent. Molecular recognition plays a significant role in chain conformation and charge delocalization.

Structural superlubricity of platinum on graphite under ambient conditions: The effects of chemistry and geometry

Science.gov (United States)

Özoǧul, Alper; Ipek, Semran; Durgun, Engin; Baykara, Mehmet Z.

2017-11-01

An investigation of the frictional behavior of platinum nanoparticles laterally manipulated on graphite has been conducted to answer the question of whether the recent observation of structural superlubricity under ambient conditions [E. Cihan, S. İpek, E. Durgun, and M. Z. Baykara, Nat. Commun. 7, 12055 (2016)] is exclusively limited to the gold-graphite interface. Platinum nanoparticles have been prepared by e-beam evaporation of a thin film of platinum on graphite, followed by post-deposition annealing. Morphological and structural characterization of the nanoparticles has been performed via scanning electron microscopy and transmission electron microscopy, revealing a crystalline structure with no evidence of oxidation under ambient conditions. Lateral manipulation experiments have been performed via atomic force microscopy under ambient conditions, whereby results indicate the occurrence of structural superlubricity at mesoscopic interfaces of 4000-75 000 nm2, with a noticeably higher magnitude of friction forces when compared with gold nanoparticles of similar contact areas situated on graphite. Ab initio simulations of sliding involving platinum and gold slabs on graphite confirm the experimental observations, whereby the higher magnitude of friction forces is attributed to stronger energy barriers encountered by platinum atoms sliding on graphite, when compared with gold. On the other hand, as predicted by theory, the scaling power between friction force and contact size is found to be independent of the chemical identity of the sliding atoms, but to be determined by the geometric qualities of the interface, as characterized by an average "sharpness score" assigned to the nanoparticles.

Quantum transport through mesoscopic disordered interfaces, junctions, and multilayers

International Nuclear Information System (INIS)

Nikolic, Branislav K.

2002-01-01

This study explores perpendicular transport through macroscopically inhomogeneous three-dimensional disordered conductors using mesoscopic methods (the real-space Green function technique in a two-probe measuring geometry). The nanoscale samples (containing ∼ 1000 atoms) are modelled by a tight-binding Hamiltonian on a simple cubic lattice where disorder is introduced in the on-site potential energy. I compute the transport properties of: disordered metallic junctions formed by concatenating two homogeneous samples with different kinds of microscopic disorder, a single strongly disordered interface, and multilayers composed of such interfaces and homogeneous layers characterized by different strengths of the same type of microscopic disorder. This allows us to: contrast the resistor model (semiclassical) approach with a fully quantum description of dirty mesoscopic multilayers; study the transmission properties of dirty interfaces (where the Schep-Bauer distribution of transmission eigenvalues is confirmed for a single interface, as well as for a stack of such interfaces that is thinner than the localization length); and elucidate the effect of coupling to ideal leads ('measuring apparatus') on the conductance of both bulk conductors and dirty interfaces. When a multilayer contains a ballistic layer in between two interfaces, its disorder-averaged conductance oscillates as a function of the Fermi energy. I also address some fundamental issues in quantum transport theory - the relationship between the Kubo formula in the exact state representation and the 'mesoscopic Kubo formula' (which gives the exact zero-temperature conductance of a finite-size sample attached to two semi-infinite ideal leads) is thoroughly re-examined by comparing their outcomes for both the junctions and homogeneous samples. (author)

Quantum Spin Transport in Mesoscopic Interferometer

Directory of Open Access Journals (Sweden)

Zein W. A.

2007-10-01

Full Text Available Spin-dependent conductance of ballistic mesoscopic interferometer is investigated. The quantum interferometer is in the form of ring, in which a quantum dot is embedded in one arm. This quantum dot is connected to one lead via tunnel barrier. Both Aharonov- Casher and Aharonov-Bohm e ects are studied. Our results confirm the interplay of spin-orbit coupling and quantum interference e ects in such confined quantum systems. This investigation is valuable for spintronics application, for example, quantum information processing.

Dynamic magnetoconductance fluctuations and oscillations in mesoscopic wires and rings

DEFF Research Database (Denmark)

Liu, D. Z.; Hu, Ben Yu-Kuang; Stafford, C. A.

1994-01-01

Using a finite-frequency recursive Green's-function technique, we calculate the dynamic magnetoconductance fluctuations and oscillations in disordered mesoscopic normal-metal systems, incorporating interparticle Coulomb interactions within a self-consistent potential method. In a disorderd metal ...

Robust depth selectivity in mesoscopic scattering regimes using angle-resolved measurements.

Science.gov (United States)

González-Rodríguez, P; Kim, A D; Moscoso, M

2013-03-01

We study optical imaging of tissues in the mesoscopic scattering regime in which light multiply scatters in tissues but is not fully diffusive. We use the radiative transport equation to model light propagation and an ℓ1-optimization method to solve the inverse source problem. We show that recovering the location and strength of several point-like sources that are close to each other is not possible when using angle-averaged measurements. The image reliability is limited by a spatial scale that is on the order of the transport mean-free path, even under the most ideal conditions. However, by using just a few angle-resolved measurements, the proposed method is able to overcome this limitation.

Preparation of gluten-free bread using a meso-structured whey protein particle system

NARCIS (Netherlands)

Riemsdijk, van L.E.; Goot, van der A.J.; Hamer, R.J.; Boom, R.M.

2011-01-01

This article presents a novel method for making gluten-free bread using mesoscopically structured whey protein. The use of the meso-structured protein is based on the hypothesis that the gluten structure present in a developed wheat dough features a particle structure on a mesoscopic length scale

Magnetic response and critical current properties of mesoscopic-size YBCO superconducting samples

International Nuclear Information System (INIS)

Lisboa-Filho, P N; Deimling, C V; Ortiz, W A

2010-01-01

In this contribution superconducting specimens of YBa 2 Cu 3 O 7-δ were synthesized by a modified polymeric precursor method, yielding a ceramic powder with particles of mesoscopic-size. Samples of this powder were then pressed into pellets and sintered under different conditions. The critical current density was analyzed by isothermal AC-susceptibility measurements as a function of the excitation field, as well as with isothermal DC-magnetization runs at different values of the applied field. Relevant features of the magnetic response could be associated to the microstructure of the specimens and, in particular, to the superconducting intra- and intergranular critical current properties.

Magnetic response and critical current properties of mesoscopic-size YBCO superconducting samples

Energy Technology Data Exchange (ETDEWEB)

Lisboa-Filho, P N [UNESP - Universidade Estadual Paulista, Grupo de Materiais Avancados, Departamento de Fisica, Bauru (Brazil); Deimling, C V; Ortiz, W A, E-mail: plisboa@fc.unesp.b [Grupo de Supercondutividade e Magnetismo, Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos (Brazil)

2010-01-15

In this contribution superconducting specimens of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were synthesized by a modified polymeric precursor method, yielding a ceramic powder with particles of mesoscopic-size. Samples of this powder were then pressed into pellets and sintered under different conditions. The critical current density was analyzed by isothermal AC-susceptibility measurements as a function of the excitation field, as well as with isothermal DC-magnetization runs at different values of the applied field. Relevant features of the magnetic response could be associated to the microstructure of the specimens and, in particular, to the superconducting intra- and intergranular critical current properties.

Universal mesoscopic conductance fluctuations

International Nuclear Information System (INIS)

Evangelou, S.N.

1992-01-01

The theory of conductance fluctuations in disordered metallic systems with size large compared to the mean free path of the electron but small compared to localization length is considered. It is demonstrates that fluctuations have an universal character and are due to repulsion between levels and spectral rigidity. The basic fluctuation measures for the energy spectrum in the mesoscopic regime of disordered systems are consistent with the Gaussian random matrix ensemble predictions. Although our disordered electron random matrix ensemble does not belong to the Gaussian ensemble the two ensembles turn out to be essentially similar. The level repulsion and the spectral rigidity found in nuclear spectra should also be observed in the metallic regime of Anderson localization. 7 refs. (orig.)

Quantum gambling using mesoscopic ring qubits

Energy Technology Data Exchange (ETDEWEB)

Pakula, Ireneusz [University of Silesia, Institute of Physics, ul. Uniwersytecka 4, 40-007 Katowice (Poland)

2007-07-15

Quantum Game Theory provides us with new tools for practising games and some other risk related enterprices like, for example, gambling. The two party gambling protocol presented by Goldenberg et al. is one of the simplest yet still hard to implementapplications of Quantum Game Theory. We propose potential physical realisation of the quantum gambling protocol with use of three mesoscopic ring qubits. We point out problems in implementation of such game. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Quantum gambling using mesoscopic ring qubits

International Nuclear Information System (INIS)

Pakula, Ireneusz

2007-01-01

Quantum Game Theory provides us with new tools for practising games and some other risk related enterprices like, for example, gambling. The two party gambling protocol presented by Goldenberg et al. is one of the simplest yet still hard to implementapplications of Quantum Game Theory. We propose potential physical realisation of the quantum gambling protocol with use of three mesoscopic ring qubits. We point out problems in implementation of such game. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Andreev reflection properties in a parallel mesoscopic circuit with Majorana bound states

Energy Technology Data Exchange (ETDEWEB)

Mu, Jin-Tao; Han, Yu [Physics Department, Liaoning University, Shenyang 110036 (China); Gong, Wei-Jiang, E-mail: gwj@mail.neu.edu.cn [College of Sciences, Northeastern University, Shenyang 110819 (China)

2017-03-15

We investigate the Andreev reflection in a parallel mesoscopic circuit with Majorana bound states (MBSs). It is found that in such a structure, the Andreev current can be manipulated in a highly efficient way, by the adjustment of bias voltage, dot levels, inter-MBS coupling, and the applied magnetic flux. Besides, the dot-MBS coupling manner is an important factor to modulate the Andreev current, because it influences the period of the conductance oscillation. By discussing the underlying quantum interference mechanism, the Andreev-reflection property is explained in detail. We believe that all the results can assist to understand the nontrivial role of the MBSs in driving the Andreev reflection.

Spin tunnelling in mesoscopic systems

Science.gov (United States)

Garg, Anupam

2001-02-01

We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the space of magnetic fields, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.

Fluctuations and localization in mesoscopic electron

CERN Document Server

Janssen, Martin

2001-01-01

The quantum phenomena of tunneling and interference show up not only in the microscopic world of atoms and molecules, but also in cold materials of the real world, such as metals and semiconductors. Though not fully macroscopic, such mesoscopic systems contain a huge number of particles, and the holistic nature of quantum mechanics becomes evident already in simple electronic measurements. The measured quantity fluctuates as a function of applied fields in an unpredictable, yet reproducible way. Despite this fingerprint character of fluctuations, their statistical properties are universal, i.e

An effective rate equation approach to reaction kinetics in small volumes: theory and application to biochemical reactions in nonequilibrium steady-state conditions.

Science.gov (United States)

Grima, R

2010-07-21

Chemical master equations provide a mathematical description of stochastic reaction kinetics in well-mixed conditions. They are a valid description over length scales that are larger than the reactive mean free path and thus describe kinetics in compartments of mesoscopic and macroscopic dimensions. The trajectories of the stochastic chemical processes described by the master equation can be ensemble-averaged to obtain the average number density of chemical species, i.e., the true concentration, at any spatial scale of interest. For macroscopic volumes, the true concentration is very well approximated by the solution of the corresponding deterministic and macroscopic rate equations, i.e., the macroscopic concentration. However, this equivalence breaks down for mesoscopic volumes. These deviations are particularly significant for open systems and cannot be calculated via the Fokker-Planck or linear-noise approximations of the master equation. We utilize the system-size expansion including terms of the order of Omega(-1/2) to derive a set of differential equations whose solution approximates the true concentration as given by the master equation. These equations are valid in any open or closed chemical reaction network and at both the mesoscopic and macroscopic scales. In the limit of large volumes, the effective mesoscopic rate equations become precisely equal to the conventional macroscopic rate equations. We compare the three formalisms of effective mesoscopic rate equations, conventional rate equations, and chemical master equations by applying them to several biochemical reaction systems (homodimeric and heterodimeric protein-protein interactions, series of sequential enzyme reactions, and positive feedback loops) in nonequilibrium steady-state conditions. In all cases, we find that the effective mesoscopic rate equations can predict very well the true concentration of a chemical species. This provides a useful method by which one can quickly determine the

Quantum bit string commitment protocol using polarization of mesoscopic coherent states

International Nuclear Information System (INIS)

Mendonca, Fabio Alencar; Ramos, Rubens Viana

2008-01-01

In this work, we propose a quantum bit string commitment protocol using polarization of mesoscopic coherent states. The protocol is described and its security against brute force and quantum cloning machine attack is analyzed

Quantum bit string commitment protocol using polarization of mesoscopic coherent states

Science.gov (United States)

Mendonça, Fábio Alencar; Ramos, Rubens Viana

2008-02-01

In this work, we propose a quantum bit string commitment protocol using polarization of mesoscopic coherent states. The protocol is described and its security against brute force and quantum cloning machine attack is analyzed.

Vortex-slip transitions in superconducting a-NbGe mesoscopic channels

Science.gov (United States)

Kokubo, N.; Sorop, T. G.; Besseling, R.; Kes, P. H.

2006-06-01

Intriguing and novel physical aspects related to the vortex flow dynamics have been recently observed in mesoscopic channel devices of a-NbGe with NbN channel edges. In this work we have systematically studied the flow properties of vortices confined in such mesoscopic channels as a function of the magnetic field history, using dc-transport and mode-locking (ML) measurements. As opposed to the field-down situation, in the field-up case a kink anomaly in the dc I-V curves is detected. The mode-locking measurements reveal that this anomaly is, in fact, a flow induced vortex slip transition: by increasing the external drive (either dc or ac) a sudden change occurs from n to n+2 moving vortex rows in the channel. The observed features can be explained in terms of an interplay between field focusing due to screening currents and a change in the predominant pinning mechanism.

Analysis of the elastic behaviour of nonclassical nonlinear mesoscopic materials in quasi-static experiments

International Nuclear Information System (INIS)

Ruffino, E.; Scalerandi, M.

2000-01-01

As discovered by recent quasi-static and dynamic resonance experiments, the classical nonlinear theory fails in describing the hysteretic behaviour of nonlinear mesoscopic materials like rocks, concrete, etc. The paper applies the local interaction simulation approach (LISA) for studying such kind of nonclassical nonlinearity. To this purpose, in the LISA treatment of ultrasonic wave propagation has been included a phenomenological model, based on the PM space approach, of the local mesoscopic features of rocks and other materials with localized damages. A quantitative comparison of simulation and experimental results in quasi-static experiments is also presented

Coherent current states in mesoscopic four-terminal Josephson junction

International Nuclear Information System (INIS)

Zareyan, M.; Omelyanchouk, A.N.

1999-01-01

A theory is offered for the ballistic 4-terminal Josephson junction. The studied system consist of a mesoscopic two-dimensional normal rectangular layer which is attached on each side to the bulk superconducting banks (terminals). A relation is obtained between the currents through the different terminals, that is valid for arbitrary temperatures and junction sizes. The nonlocal coupling of the supercurrent leads to a new effect, specific for the mesoscopic weak link between two superconducting rings; an applied magnetic flux through one of the rings produces a magnetic flux in the other ring even in the absence of an external flux through the other one. The phase dependent distributions of the local density of Andreev states, of the supercurrents and of the induced order parameter are obtained. The 'interference pattern' for the anomalous average inside the two-dimensional region cam be regulated by the applied magnetic fluxes or the transport currents. For some values of the phase differences between the terminals, the current vortex state and two-dimensional phase slip center appear

A Floquet-Green's function approach to mesoscopic transport under ac bias

International Nuclear Information System (INIS)

Wu, B H; Cao, J C

2008-01-01

The current response of a mesoscopic system under a periodic ac bias is investigated by combining the Floquet theorem and the nonequilibrium Green's function method. The band structure of the lead under ac bias is fully taken into account by using appropriate self-energies in an enlarged Floquet space. Both the retarded and lesser Green's functions are obtained in the Floquet basis to account for the interference and interaction effects. In addition to the external ac bias, the time-varying Coulomb interaction, which is treated at the self-consistent Hartree-Fock level, provides another internal ac field. The numerical results show that the time-varying Coulomb field yields decoherence and reduces the ringing behavior of the current response to a harmonic bias

Incompatibility of strains and its application to mesoscopic studies of plasticity

Czech Academy of Sciences Publication Activity Database

Gröger, Roman; Lookman, T.; Saxena, A.

2010-01-01

Roč. 82, č. 14 (2010), Art. No. 144104 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z20410507 Keywords : incompatibility * dislocation * mesoscopic Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010

Nonequilibrium mesoscopic transport: a genealogy

International Nuclear Information System (INIS)

Das, Mukunda P; Green, Frederick

2012-01-01

Models of nonequilibrium quantum transport underpin all modern electronic devices, from the largest scales to the smallest. Past simplifications such as coarse graining and bulk self-averaging served well to understand electronic materials. Such particular notions become inapplicable at mesoscopic dimensions, edging towards the truly quantum regime. Nevertheless a unifying thread continues to run through transport physics, animating the design of small-scale electronic technology: microscopic conservation and nonequilibrium dissipation. These fundamentals are inherent in quantum transport and gain even greater and more explicit experimental meaning in the passage to atomic-sized devices. We review their genesis, their theoretical context, and their governing role in the electronic response of meso- and nanoscopic systems. (topical review)

Short, intermediate and mesoscopic range order in sulfur-rich binary glasses

International Nuclear Information System (INIS)

Bychkov, E.; Miloshova, M.; Price, D.L.; Benmore, C.J.; Lorriaux, A.

2006-01-01

Pulsed neutron and high-energy X-ray diffraction, small-angle neutron scattering, Raman spectroscopy and DSC were used to study structural changes on the short, intermediate and mesoscopic range scale for sulfur-rich AsS x (x (ge) 1.5) and GeS x (x (ge) 2) glasses. Two structural regions were found in the both systems. (1) Between stoichiometric (As 2 S 3 and GeS 2 ) and 'saturated' (AsS 2.2 and GeS 2.7 ) compositions, excessive sulfur atoms form sulfur dimers and/or short chains, replacing bridging sulfur in corner-sharing AsS 3/2 and GeS 4/2 units. (2) Above the 'saturated' compositions at (As) x system) appear in the glass network. The glasses become phase separated with the domains of 20-50 (angstrom), presumably enriched with sulfur rings. The longer chains Sn are not stable and crystallize to c-S 8 on ageing of a few days to several months, depending on composition.

From the atomic nucleus to mesoscopic systems to microwave cavities

Indian Academy of Sciences (India)

Abstract. Universal statistical aspects of wave scattering by a variety of physical systems ranging from atomic nuclei to mesoscopic systems and microwave cavities are described. A statistical model for the scattering matrix is employed to address the problem of quantum chaotic scattering. The model, introduced in the past ...

Mesoscopic spin Hall effect in semiconductor nanostructures

Science.gov (United States)

Zarbo, Liviu

The spin Hall effect (SHE) is a name given to a collection of diverse phenomena which share two principal features: (i) longitudinal electric current flowing through a paramagnetic semiconductor or metallic sample leads to transverse spin current and spin accumulation of opposite sign at opposing lateral edges; (ii) SHE does not require externally applied magnetic field or magnetic ordering in the equilibrium state of the sample, instead it relies on the presence of spin-orbit (SO) couplings within the sample. This thesis elaborates on a new type of phenomenon within the SHE family, predicted in our recent studies [Phys. Rev. B 72, 075361 (2005); Phys. Rev. Lett. 95, 046601 (2005); Phys. Rev. B 72, 075335 (2005); Phys. Rev. B 73 , 075303 (2006); and Europhys. Lett. 77, 47004 (2007)], where pure spin current flows through the transverse electrodes attached to a clean finitesize two-dimensional electron gas (2DEG) due to unpolarized charge current injected through its longitudinal leads. If transverse leads are removed, the effect manifests as nonequilibrium spin Hall accumulation at the lateral edges of 2DEG wires. The SO coupling driving this SHE effect is of the Rashba type, which arises due to structural inversion asymmetry of semiconductor heterostructure hosting the 2DEG. We term the effect "mesoscopic" because the spin Hall currents and accumulations reach optimal value in samples of the size of the spin precession length---the distance over which the spin of an electron precesses by an angle pi. In strongly SO-coupled structures this scale is of the order of ˜100 nm, and, therefore, mesoscopic in the sense of being much larger than the characteristic microscopic scales (such as the Fermi wavelength, screening length, or the mean free path in disordered systems), but still much smaller than the macroscopic ones. Although the first theoretical proposal for SHE, driven by asymmetry in SO-dependent scattering of spin-up and spin-down electrons off impurities

Tailoring of quantum dot emission efficiency by localized surface plasmon polaritons in self-organized mesoscopic rings.

Science.gov (United States)

Margapoti, Emanuela; Gentili, Denis; Amelia, Matteo; Credi, Alberto; Morandi, Vittorio; Cavallini, Massimiliano

2014-01-21

We report on the tailoring of quantum dot (QD) emission efficiency by localized surface plasmon polaritons in self-organized mesoscopic rings. Ag nanoparticles (NPs) with CdSe QDs embedded in a polymeric matrix are spatially organised in mesoscopic rings and coupled in a tuneable fashion by breath figure formation. The mean distance between NPs and QDs and consequently the intensity of QD photoluminescence, which is enhanced by the coupling of surface plasmons and excitons, are tuned by acting on the NP concentration.

Zinc tin oxide as high-temperature stable recombination layer for mesoscopic perovskite/silicon monolithic tandem solar cells

KAUST Repository

Werner, Jérémie

2016-12-05

Perovskite/crystalline silicon tandem solar cells have the potential to reach efficiencies beyond those of silicon single-junction record devices. However, the high-temperature process of 500 °C needed for state-of-the-art mesoscopic perovskite cells has, so far, been limiting their implementation in monolithic tandem devices. Here, we demonstrate the applicability of zinc tin oxide as a recombination layer and show its electrical and optical stability at temperatures up to 500 °C. To prove the concept, we fabricate monolithic tandem cells with mesoscopic top cell with up to 16% efficiency. We then investigate the effect of zinc tin oxide layer thickness variation, showing a strong influence on the optical interference pattern within the tandem device. Finally, we discuss the perspective of mesoscopic perovskite cells for high-efficiency monolithic tandem solar cells. © 2016 Author(s)

Novel interference effects and a new quantum phase in mesoscopic ...

Indian Academy of Sciences (India)

Mesoscopic systems have provided an opportunity to study quantum effects beyond the ... tance [2], normal electron persistent currents [3], non-local current and voltage relations .... If both Б½ and Б¾ are positive or flow in the same direction of the potential drop then the ..... Fermi distribution function ¼(¯) = (1 + exp[(¯ - ) М]).

Mesoscopic fluctuations of the population of a qubit in a strong alternating field

Energy Technology Data Exchange (ETDEWEB)

Denisenko, M. V., E-mail: mar.denisenko@gmail.com; Satanin, A. M. [Lobachevsky State University of Nizhny Novgorod (Russian Federation)

2016-12-15

Fluctuations of the population of a Josephson qubit in an alternating field, which is a superposition of electromagnetic pulses with large amplitudes, are studied. It is shown that the relative phase of pulses is responsible for the rate of Landau–Zener transitions and, correspondingly, for the frequency of transitions between adiabatic states. The durations of pulses incident on the qubit are controlled with an accuracy of the field period, which results in strong mesoscopic fluctuations of the population of the qubit. Similar to the magnetic field in mesoscopic physics, the relative phase of pulses can destroy the interference pattern of the population of the qubit. The influence of the duration of the pulse and noise on the revealed fluctuation effects is studied.

Convergence of methods for coupling of microscopic and mesoscopic reaction–diffusion simulations

KAUST Repository

Flegg, Mark B.; Hellander, Stefan; Erban, Radek

2015-01-01

© 2015 Elsevier Inc. In this paper, three multiscale methods for coupling of mesoscopic (compartment-based) and microscopic (molecular-based) stochastic reaction-diffusion simulations are investigated. Two of the three methods that will be discussed in detail have been previously reported in the literature; the two-regime method (TRM) and the compartment-placement method (CPM). The third method that is introduced and analysed in this paper is called the ghost cell method (GCM), since it works by constructing a "ghost cell" in which molecules can disappear and jump into the compartment-based simulation. Presented is a comparison of sources of error. The convergent properties of this error are studied as the time step δ. t (for updating the molecular-based part of the model) approaches zero. It is found that the error behaviour depends on another fundamental computational parameter h, the compartment size in the mesoscopic part of the model. Two important limiting cases, which appear in applications, are considered:. (i)δt→0 and h is fixed;(ii)δt→0 and h→0 such that δt/h is fixed. The error for previously developed approaches (the TRM and CPM) converges to zero only in the limiting case (ii), but not in case (i). It is shown that the error of the GCM converges in the limiting case (i). Thus the GCM is superior to previous coupling techniques if the mesoscopic description is much coarser than the microscopic part of the model.

Convergence of methods for coupling of microscopic and mesoscopic reaction–diffusion simulations

KAUST Repository

Flegg, Mark B.

2015-05-01

© 2015 Elsevier Inc. In this paper, three multiscale methods for coupling of mesoscopic (compartment-based) and microscopic (molecular-based) stochastic reaction-diffusion simulations are investigated. Two of the three methods that will be discussed in detail have been previously reported in the literature; the two-regime method (TRM) and the compartment-placement method (CPM). The third method that is introduced and analysed in this paper is called the ghost cell method (GCM), since it works by constructing a "ghost cell" in which molecules can disappear and jump into the compartment-based simulation. Presented is a comparison of sources of error. The convergent properties of this error are studied as the time step δ. t (for updating the molecular-based part of the model) approaches zero. It is found that the error behaviour depends on another fundamental computational parameter h, the compartment size in the mesoscopic part of the model. Two important limiting cases, which appear in applications, are considered:. (i)δt→0 and h is fixed;(ii)δt→0 and h→0 such that δt/h is fixed. The error for previously developed approaches (the TRM and CPM) converges to zero only in the limiting case (ii), but not in case (i). It is shown that the error of the GCM converges in the limiting case (i). Thus the GCM is superior to previous coupling techniques if the mesoscopic description is much coarser than the microscopic part of the model.

Systematic parameter inference in stochastic mesoscopic modeling

Energy Technology Data Exchange (ETDEWEB)

Lei, Huan; Yang, Xiu [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Li, Zhen [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States); Karniadakis, George Em, E-mail: george_karniadakis@brown.edu [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States)

2017-02-01

We propose a method to efficiently determine the optimal coarse-grained force field in mesoscopic stochastic simulations of Newtonian fluid and polymer melt systems modeled by dissipative particle dynamics (DPD) and energy conserving dissipative particle dynamics (eDPD). The response surfaces of various target properties (viscosity, diffusivity, pressure, etc.) with respect to model parameters are constructed based on the generalized polynomial chaos (gPC) expansion using simulation results on sampling points (e.g., individual parameter sets). To alleviate the computational cost to evaluate the target properties, we employ the compressive sensing method to compute the coefficients of the dominant gPC terms given the prior knowledge that the coefficients are “sparse”. The proposed method shows comparable accuracy with the standard probabilistic collocation method (PCM) while it imposes a much weaker restriction on the number of the simulation samples especially for systems with high dimensional parametric space. Fully access to the response surfaces within the confidence range enables us to infer the optimal force parameters given the desirable values of target properties at the macroscopic scale. Moreover, it enables us to investigate the intrinsic relationship between the model parameters, identify possible degeneracies in the parameter space, and optimize the model by eliminating model redundancies. The proposed method provides an efficient alternative approach for constructing mesoscopic models by inferring model parameters to recover target properties of the physics systems (e.g., from experimental measurements), where those force field parameters and formulation cannot be derived from the microscopic level in a straight forward way.

Direct extraction of electron parameters from magnetoconductance analysis in mesoscopic ring array structures

Science.gov (United States)

Sawada, A.; Faniel, S.; Mineshige, S.; Kawabata, S.; Saito, K.; Kobayashi, K.; Sekine, Y.; Sugiyama, H.; Koga, T.

2018-05-01

We report an approach for examining electron properties using information about the shape and size of a nanostructure as a measurement reference. This approach quantifies the spin precession angles per unit length directly by considering the time-reversal interferences on chaotic return trajectories within mesoscopic ring arrays (MRAs). Experimentally, we fabricated MRAs using nanolithography in InGaAs quantum wells which had a gate-controllable spin-orbit interaction (SOI). As a result, we observed an Onsager symmetry related to relativistic magnetic fields, which provided us with indispensable information for the semiclassical billiard ball simulation. Our simulations, developed based on the real-space formalism of the weak localization/antilocalization effect including the degree of freedom for electronic spin, reproduced the experimental magnetoconductivity (MC) curves with high fidelity. The values of five distinct electron parameters (Fermi wavelength, spin precession angles per unit length for two different SOIs, impurity scattering length, and phase coherence length) were thereby extracted from a single MC curve. The methodology developed here is applicable to wide ranges of nanomaterials and devices, providing a diagnostic tool for exotic properties of two-dimensional electron systems.

A novel grid-based mesoscopic model for evacuation dynamics

Science.gov (United States)

Shi, Meng; Lee, Eric Wai Ming; Ma, Yi

2018-05-01

This study presents a novel grid-based mesoscopic model for evacuation dynamics. In this model, the evacuation space is discretised into larger cells than those used in microscopic models. This approach directly computes the dynamic changes crowd densities in cells over the course of an evacuation. The density flow is driven by the density-speed correlation. The computation is faster than in traditional cellular automata evacuation models which determine density by computing the movements of each pedestrian. To demonstrate the feasibility of this model, we apply it to a series of practical scenarios and conduct a parameter sensitivity study of the effect of changes in time step δ. The simulation results show that within the valid range of δ, changing δ has only a minor impact on the simulation. The model also makes it possible to directly acquire key information such as bottleneck areas from a time-varied dynamic density map, even when a relatively large time step is adopted. We use the commercial software AnyLogic to evaluate the model. The result shows that the mesoscopic model is more efficient than the microscopic model and provides more in-situ details (e.g., pedestrian movement pattern) than the macroscopic models.

Aggregation of Frenkel defects under irradiation: a mesoscopic approach

International Nuclear Information System (INIS)

Soppe, W.; Kotomin, E.

1993-08-01

The radiation-induced aggregation of Frenkel defects in solids is studied in terms of a mesoscopic approach. The asymmetry in elastic interactions between mobile interstitials (I-I) and between interstitials and vacancies (I-V) plays a decisive role in the aggregation of similar defects. The conditions for defect aggregation are studied in detail for NaCl crystals. The critical dose rate for aggregation has been calculated as a function of the temperature as well as the aggregation rate as a function of temperature and dose rate. Furthermore, the role of deep traps (like impurities and di-vacancies), reducing the mobility of interstitials, and the role of dislocations serving as sinks for interstitials, are studied. The aggregation appears to reach a maximum at a distinct temperature which is in agreement both with experiment and the Jain-Lidiard theory. The model also predicts a shift of this maximum towards lower temperatures if the dose rate is decreased. The consequences of the model for the disposal of nuclear waste in rock salt formations, are briefly discussed. (orig.)

Atom chips: mesoscopic physics with cold atoms

International Nuclear Information System (INIS)

Krueger, P.; Wildermuth, S.; Hofferberth, S.; Haller, E.; GAllego Garcia, D.; Schmiedmayer, J.

2005-01-01

Full text: Cold neutral atoms can be controlled and manipulated in microscopic potentials near surfaces of atom chips. These integrated micro-devices combine the known techniques of atom optics with the capabilities of well established micro- and nanofabrication technology. In analogy to electronic microchips and integrated fiber optics, the concept of atom chips is suitable to explore the domain of mesoscopic physics with matter waves. We use current and charge carrying structures to form complex potentials with high spatial resolution only microns from the surface. In particular, atoms can be confined to an essentially one-dimensional motion. In this talk, we will give an overview of our experiments studying the manipulation of both thermal atoms and BECs on atom chips. First experiments in the quasi one-dimensional regime will be presented. These experiments profit from strongly reduced residual disorder potentials caused by imperfections of the chip fabrication with respect to previously published experiments. This is due to our purely lithographic fabrication technique that proves to be advantageous over electroplating. We have used one dimensionally confined BECs as an ultra-sensitive probe to characterize these potentials. These smooth potentials allow us to explore various aspects of the physics of degenerate quantum gases in low dimensions. (author)

Current density waves in open mesoscopic rings driven by time-periodic magnetic fluxes

International Nuclear Information System (INIS)

Yan Conghua; Wei Lianfu

2010-01-01

Quantum coherent transport through open mesoscopic Aharonov-Bohm rings (driven by static fluxes) have been studied extensively. Here, by using quantum waveguide theory and the Floquet theorem we investigate the quantum transport of electrons along an open mesoscopic ring threaded by a time-periodic magnetic flux. We predicate that current density waves could be excited along such an open ring. As a consequence, a net current could be generated along the lead with only one reservoir, if the lead additionally connects to such a normal-metal loop driven by the time-dependent flux. These phenomena could be explained by photon-assisted processes, due to the interaction between the transported electrons and the applied oscillating external fields. We also discuss how the time-average currents (along the ring and the lead) depend on the amplitude and frequency of the applied oscillating fluxes.

Interactions between electrons, mesoscopic Josephson effect and asymmetric current fluctuations

Science.gov (United States)

Huard, B.

2006-07-01

This article discusses three experiments on the properties of electronic transport at the mesoscopic scale. The first one allowed to measure the energy exchange rate between electrons in a metal contaminated by a very weak concentration of magnetic impurities. The role played by magnetic impurities in the Kondo regime on those energy exchanges is quantitatively investigated, and the global measured exchange rate is larger than expected. The second experiment is a measurement of the current-phase relation in a system made of two superconductors linked through a single atom. We thus provide quantitative support for the recent description of the mesoscopic Josephson effect. The last experiment is a measurement of the asymmetry of the current fluctuations in a mesoscopic conductor, using a Josephson junction as a threshold detector. Cet ouvrage décrit trois expériences portant sur les propriétés du transport électronique à l'échelle mésoscopique. La première a permis de mesurer le taux d'échange d'énergie entre électrons dans un métal contenant une très faible concentration d'impuretés magnétiques. Nous avons validé la description quantitative du rôle des impuretés magnétiques dans le régime Kondo sur ces échanges énergétiques et aussi montré que le taux global d'échange est plus fort que prévu. La seconde expérience est une mesure de la relation courant-phase dans un système constitué de deux supraconducteurs couplés par un seul atome. Elle nous a permis de conforter quantitativement la récente description de l'effet Josephson mésoscopique. La dernière expérience est unemesure de l'asymétrie des fluctuations du courant dans un conducteur mésoscopique en utilisant une Jonction Josephson comme détecteur de seuil.

Transport properties of mesoscopic graphene rings

International Nuclear Information System (INIS)

Xu, N.; Ding, J.W.; Wang, B.L.; Shi, D.N.; Sun, H.Q.

2012-01-01

Based on a recursive Green's function method, we investigate the conductance of mesoscopic graphene rings in the presence of disorder, in the limit of phase coherent transport. Two models of disorder are considered: edge disorder and surface disorder. Our simulations show that the conductance decreases exponentially with the edge disorder and the surface disorder. In the presence of flux, a clear Aharonov-Bohm conductance oscillation with the period Φ 0 (Φ 0 =h/e) is observed. The edge disorder and the surface disorder have no effect on the period of AB oscillation. The amplitudes of AB oscillations vary with gate voltage and flux, which is consistent with the previous results. Additionally, ballistic rectification and negative differential resistance are observed in I-V curves, with on/off characteristic.

Mesoscopic Simulations of Crosslinked Polymer Networks

Science.gov (United States)

Megariotis, Grigorios; Vogiatzis, Georgios G.; Schneider, Ludwig; Müller, Marcus; Theodorou, Doros N.

2016-08-01

A new methodology and the corresponding C++ code for mesoscopic simulations of elastomers are presented. The test system, crosslinked ds-1’4-polyisoprene’ is simulated with a Brownian Dynamics/kinetic Monte Carlo algorithm as a dense liquid of soft, coarse-grained beads, each representing 5-10 Kuhn segments. From the thermodynamic point of view, the system is described by a Helmholtz free-energy containing contributions from entropic springs between successive beads along a chain, slip-springs representing entanglements between beads on different chains, and non-bonded interactions. The methodology is employed for the calculation of the stress relaxation function from simulations of several microseconds at equilibrium, as well as for the prediction of stress-strain curves of crosslinked polymer networks under deformation.

Mesoscopic CH 3 NH 3 PbI 3 /TiO 2 Heterojunction Solar Cells

KAUST Repository

Etgar, Lioz

2012-10-24

We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH 3NH 3PbI 3) perovskite/TiO 2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH 3NH 3I and PbI 2 in γ-butyrolactone on a 400 nm thick film of TiO 2 (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH 3NH 3PbI 3 as a back contact. Importantly, the CH 3NH 3PbI 3 nanoparticles assume here simultaneously the roles of both light harvester and hole conductor, rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH 3NH 3PbI 3/TiO 2 heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent J sc= 16.1 mA/cm 2, open-circuit photovoltage V oc = 0.631 V, and a fill factor FF = 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m 2 intensity. At a lower light intensity of 100W/m 2, a PCE of 7.3% was measured. The advent of such simple solution-processed mesoscopic heterojunction solar cells paves the way to realize low-cost, high-efficiency solar cells. © 2012 American Chemical Society.

Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with efficiency exceeding 9%.

KAUST Repository

Kim, Hui-Seon

2012-08-21

We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH(3)NH(3))PbI(3) as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI(2) and deposited onto a submicron-thick mesoscopic TiO(2) film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (J(SC)) exceeding 17 mA/cm(2), an open circuit photovoltage (V(OC)) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH(3)NH(3))PbI(3) NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO(2) film. The use of a solid hole conductor dramatically improved the device stability compared to (CH(3)NH(3))PbI(3) -sensitized liquid junction cells.

The development of a 3D mesoscopic model of metallic foam based on an improved watershed algorithm

Science.gov (United States)

Zhang, Jinhua; Zhang, Yadong; Wang, Guikun; Fang, Qin

2018-06-01

The watershed algorithm has been used widely in the x-ray computed tomography (XCT) image segmentation. It provides a transformation defined on a grayscale image and finds the lines that separate adjacent images. However, distortion occurs in developing a mesoscopic model of metallic foam based on XCT image data. The cells are oversegmented at some events when the traditional watershed algorithm is used. The improved watershed algorithm presented in this paper can avoid oversegmentation and is composed of three steps. Firstly, it finds all of the connected cells and identifies the junctions of the corresponding cell walls. Secondly, the image segmentation is conducted to separate the adjacent cells. It generates the lost cell walls between the adjacent cells. Optimization is then performed on the segmentation image. Thirdly, this improved algorithm is validated when it is compared with the image of the metallic foam, which shows that it can avoid the image segmentation distortion. A mesoscopic model of metallic foam is thus formed based on the improved algorithm, and the mesoscopic characteristics of the metallic foam, such as cell size, volume and shape, are identified and analyzed.

Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with efficiency exceeding 9%.

KAUST Repository

Kim, Hui-Seon; Lee, Chang-Ryul; Im, Jeong-Hyeok; Lee, Ki-Beom; Moehl, Thomas; Marchioro, Arianna; Moon, Soo-Jin; Humphry-Baker, Robin; Yum, Jun-Ho; Moser, Jacques E; Grä tzel, Michael; Park, Nam-Gyu

2012-01-01

We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH(3)NH(3))PbI(3) as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI(2) and deposited onto a submicron-thick mesoscopic TiO(2) film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (J(SC)) exceeding 17 mA/cm(2), an open circuit photovoltage (V(OC)) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH(3)NH(3))PbI(3) NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO(2) film. The use of a solid hole conductor dramatically improved the device stability compared to (CH(3)NH(3))PbI(3) -sensitized liquid junction cells.

Lead Iodide Perovskite Sensitized All-Solid-State Submicron Thin Film Mesoscopic Solar Cell with Efficiency Exceeding 9%

Science.gov (United States)

Kim, Hui-Seon; Lee, Chang-Ryul; Im, Jeong-Hyeok; Lee, Ki-Beom; Moehl, Thomas; Marchioro, Arianna; Moon, Soo-Jin; Humphry-Baker, Robin; Yum, Jun-Ho; Moser, Jacques E.; Grätzel, Michael; Park, Nam-Gyu

2012-01-01

We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH3NH3)PbI3 as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI2 and deposited onto a submicron-thick mesoscopic TiO2 film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (JSC) exceeding 17 mA/cm2, an open circuit photovoltage (VOC) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH3NH3)PbI3 NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO2 film. The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells. PMID:22912919

Mesoscopic objects, porous layers and nanocomposites-Possibilities of sol-gel chemistry

International Nuclear Information System (INIS)

Piwonski, Ireneusz

2009-01-01

The goal of this study was to prepare mesoscopic objects, thin porous films and nanocomposite coatings with the use of sol-gel technique. Silica nanotubes, titania nanoparticles, porous titania and zirconia coatings as well as titania nanocomposites were successfully synthesized by changing the type of sol-gel precursor, sol composition and applying dip-coating deposition procedure in order to obtain thin films or coatings. All materials were visualized and characterized by the Atomic Force Microcscopy (AFM) technique. Moreover, characterization of titania nanocomposites was extended to the tribological tests performed by means of microtribometer operating in normal loads range of 30-100 mN. The AFM analysis of mesoscopic objects and nanoparticles showed that the diameter of synthesized silica nanotubes was 60-70 nm and the size of titania nanoparticles was 43 nm. In case of porous layers the pore size in titania and zirconia coatings oscillated between 100 and 240 nm, however their shape and distribution were irregular. Microtribological studies of nanocomposites revealed the moderate decrease of the coefficient of friction for samples containing 5, 15 and 5 wt.% of zirconia nanoparticles in titania coatings annealed at 100, 500 and 1000 deg. C respectively. An enhancement of antiwear properties was already observed for 1 wt.% of nanophase content, except the sample annealed at 500 deg. C. It was also found that the annealing at high temperatures is a primary factor which affects the reduction of friction and wear of titania coatings while the presence of nanoparticles has secondary effect. Investigations in this study carried out with the use of the AFM technique highlighted the potential and flexibility of sol-gel approach in designing of various types of advanced materials in a form of mesoscopic objects, porous coatings and composite layers. Results collected in this study clearly demonstrated that sol-gel technique can be applied effectively in preparation of

From polycrystal to multi-crystal: ''numerical meso-scope'' development for a local analysis in the elasto-viscoplastic field

International Nuclear Information System (INIS)

Heraud, St.

2000-01-01

The knowledge of the local mechanical fields over several adjacent grains is needed for a better understanding of damage initiation and intergranular. failure in metallic polycrystals. This thesis aimed at the derivation of such fields through a 'numerical meso-scope': this simulation tool relies on the finite element analysis of a multi-crystalline pattern embedded in a large matrix whose mechanical behaviour is derived experimentally from classical tests performed on the studied metal. First, we derived macroscopic elastic-viscoplastic constitutive equations from tensile and creep tests on a AIS1316 stainless steel and we inferred from them the general form of similar, but crystallographic equations to be used for the single crystals; the corresponding parameters were determined by fitting the computed overall response of an aggregate made of 1000 grains with the macroscopic experimental one. We then investigated a creep-damaged area of the same steel and we simulated the same grain ensemble in the 'numerical meso-scope' so as to compare the computed normal stress on all grain boundaries with the observed de-bonded boundaries: this showed the most damaged boundaries to sustain the largest normal stress. Another application was concerned with the understanding of the origin of intergranular damage of aged AIS321 stainless steel. A similar approach was adopted with help of the meso-scope: it showed that observations could not be explained by a sole intragranular hardening as it is currently proposed in the literature. Thus the pertinence of the 'numerical meso-scope' concept can now be demonstrated, which opens on a number of new interesting perspectives. (author)

Application of the Wigner-Function Formulation to Mesoscopic Systems in Presence of Electron-Phonon Interaction

National Research Council Canada - National Science Library

Jacoboni, C

1997-01-01

A theoretical and computational analysis of the quantum dynamics of charge carriers in presence of electron-phonon interaction based on the Wigner function is here applied to the study of transport in mesoscopic systems...

The Theory of the Reentrant Effect in Susceptibility of Cylindrical Mesoscopic Samples

International Nuclear Information System (INIS)

Gogadze, G.A.

2006-01-01

A theory has been developed to explain the anomalous behavior of the magnetic susceptibility of a normal metal-superconductor (NS) structure in weak magnetic fields at milli kelvin temperatures. The effect was discovered experimentally [A. C. Mota et al., Phys. Rev. Lett. 65, 1514 (1990)]. In cylindrical superconducting samples covered with a thin normal pure metal layer, the susceptibility exhibited a reentrant effect: it started to increase unexpectedly when the temperature was lowered below 100 mK. The effect was observed in mesoscopic NS structures when the N and S metals were in good electric contact. The theory proposed is essentially based on the properties of the Andreev levels in the normal metal. When the magnetic field (or temperature) changes, each of the Andreev levels coincides from time to time with the chemical potential of the metal. As a result, the state of the NS structure experiences strong degeneracy, and the quasiparticle density of states exhibits resonance spikes. This generates a large paramagnetic contribution to the susceptibility, which adds to the diamagnetic contribution, thus leading to the reentrant effect. The explanation proposed was obtained within the model of free electrons. The theory provides a good description of the experimental results

Mesoscopic effects in an agent-based bargaining model in regular lattices.

Science.gov (United States)

Poza, David J; Santos, José I; Galán, José M; López-Paredes, Adolfo

2011-03-09

The effect of spatial structure has been proved very relevant in repeated games. In this work we propose an agent based model where a fixed finite population of tagged agents play iteratively the Nash demand game in a regular lattice. The model extends the multiagent bargaining model by Axtell, Epstein and Young modifying the assumption of global interaction. Each agent is endowed with a memory and plays the best reply against the opponent's most frequent demand. We focus our analysis on the transient dynamics of the system, studying by computer simulation the set of states in which the system spends a considerable fraction of the time. The results show that all the possible persistent regimes in the global interaction model can also be observed in this spatial version. We also find that the mesoscopic properties of the interaction networks that the spatial distribution induces in the model have a significant impact on the diffusion of strategies, and can lead to new persistent regimes different from those found in previous research. In particular, community structure in the intratype interaction networks may cause that communities reach different persistent regimes as a consequence of the hindering diffusion effect of fluctuating agents at their borders.

Mesoscopic effects in an agent-based bargaining model in regular lattices.

Directory of Open Access Journals (Sweden)

David J Poza

Full Text Available The effect of spatial structure has been proved very relevant in repeated games. In this work we propose an agent based model where a fixed finite population of tagged agents play iteratively the Nash demand game in a regular lattice. The model extends the multiagent bargaining model by Axtell, Epstein and Young modifying the assumption of global interaction. Each agent is endowed with a memory and plays the best reply against the opponent's most frequent demand. We focus our analysis on the transient dynamics of the system, studying by computer simulation the set of states in which the system spends a considerable fraction of the time. The results show that all the possible persistent regimes in the global interaction model can also be observed in this spatial version. We also find that the mesoscopic properties of the interaction networks that the spatial distribution induces in the model have a significant impact on the diffusion of strategies, and can lead to new persistent regimes different from those found in previous research. In particular, community structure in the intratype interaction networks may cause that communities reach different persistent regimes as a consequence of the hindering diffusion effect of fluctuating agents at their borders.

Signatures of topological phase transitions in mesoscopic superconducting rings

International Nuclear Information System (INIS)

Pientka, Falko; Romito, Alessandro; Duckheim, Mathias; Oppen, Felix von; Oreg, Yuval

2013-01-01

We investigate Josephson currents in mesoscopic rings with a weak link which are in or near a topological superconducting phase. As a paradigmatic example, we consider the Kitaev model of a spinless p-wave superconductor in one dimension, emphasizing how this model emerges from more realistic settings based on semiconductor nanowires. We show that the flux periodicity of the Josephson current provides signatures of the topological phase transition and the emergence of Majorana fermions (MF) situated on both sides of the weak link even when fermion parity is not a good quantum number. In large rings, the MF hybridize only across the weak link. In this case, the Josephson current is h/e periodic in the flux threading the loop when fermion parity is a good quantum number but reverts to the more conventional h/2e periodicity in the presence of fermion-parity changing relaxation processes. In mesoscopic rings, the MF also hybridize through their overlap in the interior of the superconducting ring. We find that in the topological superconducting phase, this gives rise to an h/e-periodic contribution even when fermion parity is not conserved and that this contribution exhibits a peak near the topological phase transition. This signature of the topological phase transition is robust to the effects of disorder. As a byproduct, we find that close to the topological phase transition, disorder drives the system deeper into the topological phase. This is in stark contrast to the known behavior far from the phase transition, where disorder tends to suppress the topological phase. (paper)

Equilibrium and shot noise in mesoscopic systems

Energy Technology Data Exchange (ETDEWEB)

Martin, T.

1994-10-01

Within the last decade, there has been a resurgence of interest in the study of noise in Mesoscopic devices, both experimentally and theoretically. Noise in solid state devices can have different origins: there is 1/f noise, which is believed to arise from fluctuations in the resistance of the sample due to the motion of impurities. On top of this contribution is a frequency independent component associated with the stochastic nature of electron transport, which will be the focus of this paper. If the sample considered is small enough that dephasing and inelastic effects can be neglected, equilibrium (thermal) and excess noise can be completely described in terms of the elastic scattering properties of the sample. As mentioned above, noise arises as a consequence of random processes governing the transport of electrons. Here, there are two sources of randomness: first, electrons incident on the sample occupy a given energy state with a probability given by the Fermi-Dirac distribution function. Secondly, electrons can be transmitted across the sample or reflected in the same reservoir where they came from with a probability given by the quantum mechanical transmission/reflection coefficients. Equilibrium noise refers to the case where no bias voltage is applied between the leads connected to the sample, where thermal agitation alone allows the electrons close to the Fermi level to tunnel through the sample. In general, equilibrium noise is related to the conductance of the sample via the Johnson-Nyquist formula. In the presence of a bias, in the classical regime, one expects to recover the full shot noise < {Delta}{sup 2}I >= 2I{Delta}{mu} as was observed a long time ago in vacuum diodes. In the Mesoscopic regime, however, excess noise is reduced below the shot noise level. The author introduces a more intuitive picture, where the current passing through the device is a superposition of pulses, or electron wave packets, which can be transmitted or reflected.

Thermodynamically consistent mesoscopic model of the ferro/paramagnetic transition

Czech Academy of Sciences Publication Activity Database

Benešová, Barbora; Kružík, Martin; Roubíček, Tomáš

2013-01-01

Roč. 64, Č. 1 (2013), s. 1-28 ISSN 0044-2275 R&D Projects: GA AV ČR IAA100750802; GA ČR GA106/09/1573; GA ČR GAP201/10/0357 Grant - others:GA ČR(CZ) GA106/08/1397; GA MŠk(CZ) LC06052 Program:GA; LC Institutional support: RVO:67985556 Keywords : ferro-para-magnetism * evolution * thermodynamics Subject RIV: BA - General Mathematics; BA - General Mathematics (UT-L) Impact factor: 1.214, year: 2013 http://library.utia.cas.cz/separaty/2012/MTR/kruzik-thermodynamically consistent mesoscopic model of the ferro-paramagnetic transition.pdf

Superconducting proximity effect in mesoscopic superconductor/normal-metal junctions

CERN Document Server

Takayanagi, H; Toyoda, E

1999-01-01

The superconducting proximity effect is discussed in mesoscopic superconductor/normal-metal junctions. The newly-developed theory shows long-range phase-coherent effect which explaines early experimental results of giant magnetoresistance oscillations in an Andreev interferometer. The theory also shows that the proximity correction to the conductance (PCC) has a reentrant behavior as a function of energy. The reentrant behavior is systematically studied in a gated superconductor-semiconductor junction. A negative PCC is observed in the case of a weak coupling between the normal metal and the external reservoir. Phase coherent ac effect is also observed when rf is irradiated to the junction.

Size and field effect on mesoscopic spin glass

Energy Technology Data Exchange (ETDEWEB)

Komatsu, K. [Department of Applied Physics and Physico-Infomatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan)]. E-mail: komatsu@az.appi.keio.ac.jp; Maki, H. [Department of Applied Physics and Physico-Infomatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan); Taniyama, T. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Sato, T. [Department of Applied Physics and Physico-Infomatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan)

2007-03-15

Spin glass particles were prepared as the mesoscopic system in order to examine the space scale of spin glass domain (droplet). The peak temperature T {sub peak} in the temperature-dependent magnetization is systematically reduced with decreasing average particle size. This is due to the imitation of droplet growth to the particle diameter. The magnetic field H also decreases T {sub peak}, which is caused by the reduction of the barrier height by Zeeman energy. However, there appears different tendency in the relation between H and T {sub peak} below 100 Oe. This indicates the existence of crossover between the two regimes in which the free energy and Zeeman energy govern the droplet excitation.

Detection of discretized single-shell penetration in mesoscopic vortex matter

International Nuclear Information System (INIS)

Dolz, M I; Fasano, Y; Bolecek, N R Cejas; Pastoriza, H; Konczykowski, M; Beek, C J van der

2014-01-01

We investigated configurational changes in mesoscopic vortex matter with less than thousand vortices during flux penetration in freestanding 50 μm diameter disks of Bi 2 Sr 2 CaCu 2 O 8+δ . High-resolution AC and DC local magnetometry data reveal oscillations in the transmittivity echoed in peaks in the third-harmonics magnetic signal fainting on increasing vortex density. By means of extra experimental evidence and a simple geometrical analysis we show that these features fingerprint the discretized entrance of single-shells of vortices having a shape that mimics the sample edge

Analogue Between Dynamic Hamiltonian-Operators of a Mesoscopic Ring Carrying Persistent Current and a Josephson Junction

International Nuclear Information System (INIS)

Fan Hongyi; Wang Jisuo

2006-01-01

By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system.

Mesoscopic quantum cryptography

Energy Technology Data Exchange (ETDEWEB)

Molotkov, S. N., E-mail: sergei.molotkov@gmail.com [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation)

2017-03-15

Since a strictly single-photon source is not yet available, in quantum cryptography systems, one uses, as information quantum states, coherent radiation of a laser with an average number of photons of μ ≈ 0.1–0.5 in a pulse, attenuated to the quasi-single-photon level. The linear independence of a set of coherent quasi-single-photon information states leads to the possibility of unambiguous measurements that, in the presence of losses in the line, restrict the transmission range of secret keys. Starting from a certain value of critical loss (the length of the line), the eavesdropper knows the entire key, does not make errors, and is not detected—the distribution of secret keys becomes impossible. This problem is solved by introducing an additional reference state with an average number of photons of μ{sub cl} ≈ 10{sup 3}–10{sup 6}, depending on the length of the communication line. It is shown that the use of a reference state does not allow the eavesdropper to carry out measurements with conclusive outcome while remaining undetected. A reference state guarantees detecting an eavesdropper in a channel with high losses. In this case, information states may contain a mesoscopic average number of photons in the range of μ{sub q} ≈ 0.5–10{sup 2}. The protocol proposed is easy to implement technically, admits flexible adjustment of parameters to the length of the communication line, and is simple and transparent for proving the secrecy of keys.

Dynamics of skyrmions and edge states in the resistive regime of mesoscopic p-wave superconductors

Energy Technology Data Exchange (ETDEWEB)

Fernández Becerra, V., E-mail: VictorLeonardo.FernandezBecerra@uantwerpen.be; Milošević, M.V., E-mail: milorad.milosevic@uantwerpen.be

2017-02-15

Highlights: • Voltage–current characterization of a mesoscopic p-wave superconducting sample. • Skyrmions and edge states are stabilized with an out-of-plane applied magnetic field. • In the resistive regime, moving skyrmions and the edge state behave distinctly different from the conventional kinematic vortices. - Abstract: In a mesoscopic sample of a chiral p-wave superconductor, novel states comprising skyrmions and edge states have been stabilized in out-of-plane applied magnetic field. Using the time-dependent Ginzburg–Landau equations we shed light on the dynamic response of such states to an external applied current. Three different regimes are obtained, namely, the superconducting (stationary), resistive (non-stationary) and normal regime, similarly to conventional s-wave superconductors. However, in the resistive regime and depending on the external current, we found that moving skyrmions and the edge state behave distinctly different from the conventional kinematic vortex, thereby providing new fingerprints for identification of p-wave superconductivity.

Active learning of constitutive relation from mesoscopic dynamics for macroscopic modeling of non-Newtonian flows

Science.gov (United States)

Zhao, Lifei; Li, Zhen; Caswell, Bruce; Ouyang, Jie; Karniadakis, George Em

2018-06-01

We simulate complex fluids by means of an on-the-fly coupling of the bulk rheology to the underlying microstructure dynamics. In particular, a continuum model of polymeric fluids is constructed without a pre-specified constitutive relation, but instead it is actively learned from mesoscopic simulations where the dynamics of polymer chains is explicitly computed. To couple the bulk rheology of polymeric fluids and the microscale dynamics of polymer chains, the continuum approach (based on the finite volume method) provides the transient flow field as inputs for the (mesoscopic) dissipative particle dynamics (DPD), and in turn DPD returns an effective constitutive relation to close the continuum equations. In this multiscale modeling procedure, we employ an active learning strategy based on Gaussian process regression (GPR) to minimize the number of expensive DPD simulations, where adaptively selected DPD simulations are performed only as necessary. Numerical experiments are carried out for flow past a circular cylinder of a non-Newtonian fluid, modeled at the mesoscopic level by bead-spring chains. The results show that only five DPD simulations are required to achieve an effective closure of the continuum equations at Reynolds number Re = 10. Furthermore, when Re is increased to 100, only one additional DPD simulation is required for constructing an extended GPR-informed model closure. Compared to traditional message-passing multiscale approaches, applying an active learning scheme to multiscale modeling of non-Newtonian fluids can significantly increase the computational efficiency. Although the method demonstrated here obtains only a local viscosity from the polymer dynamics, it can be extended to other multiscale models of complex fluids whose macro-rheology is unknown.

Long-time integration methods for mesoscopic models of pattern-forming systems

International Nuclear Information System (INIS)

Abukhdeir, Nasser Mohieddin; Vlachos, Dionisios G.; Katsoulakis, Markos; Plexousakis, Michael

2011-01-01

Spectral methods for simulation of a mesoscopic diffusion model of surface pattern formation are evaluated for long simulation times. Backwards-differencing time-integration, coupled with an underlying Newton-Krylov nonlinear solver (SUNDIALS-CVODE), is found to substantially accelerate simulations, without the typical requirement of preconditioning. Quasi-equilibrium simulations of patterned phases predicted by the model are shown to agree well with linear stability analysis. Simulation results of the effect of repulsive particle-particle interactions on pattern relaxation time and short/long-range order are discussed.

Transport Characteristics of Mesoscopic Radio-Frequency Single Electron Transistor

International Nuclear Information System (INIS)

Phillips, A. H.; Kirah, K.; Aly, N. A. I.; El-Sayes, H. E.

2008-01-01

The transport property of a quantum dot under the influence of external time-dependent field is investigated. The mesoscopic device is modelled as semiconductor quantum dot coupled weakly to superconducting leads via asymmetric double tunnel barriers of different heights. An expression for the current is deduced by using the Landauer–Buttiker formula, taking into consideration of both the Coulomb blockade effect and the magnetic field. It is found that the periodic oscillation of the current with the magnetic field is controlled by the ratio of the frequency of the applied ac-field to the electron cyclotron frequency. Our results show that the present device operates as a radio-frequency single electron transistor

Zinc tin oxide as high-temperature stable recombination layer for mesoscopic perovskite/silicon monolithic tandem solar cells

KAUST Repository

Werner, Jé ré mie; Walter, Arnaud; Rucavado, Esteban; Moon, Soo Jin; Sacchetto, Davide; Rienaecker, Michael; Peibst, Robby; Brendel, Rolf; Niquille, Xavier; De Wolf, Stefaan; Lö per, Philipp; Morales-Masis, Monica; Nicolay, Sylvain; Niesen, Bjoern; Ballif, Christophe

2016-01-01

the concept, we fabricate monolithic tandem cells with mesoscopic top cell with up to 16% efficiency. We then investigate the effect of zinc tin oxide layer thickness variation, showing a strong influence on the optical interference pattern within the tandem

Probabilistic conditional independence structures

CERN Document Server

Studeny, Milan

2005-01-01

Probabilistic Conditional Independence Structures provides the mathematical description of probabilistic conditional independence structures; the author uses non-graphical methods of their description, and takes an algebraic approach.The monograph presents the methods of structural imsets and supermodular functions, and deals with independence implication and equivalence of structural imsets.Motivation, mathematical foundations and areas of application are included, and a rough overview of graphical methods is also given.In particular, the author has been careful to use suitable terminology, and presents the work so that it will be understood by both statisticians, and by researchers in artificial intelligence.The necessary elementary mathematical notions are recalled in an appendix.

Interface Engineering Based on Liquid Metal for Compact-Layer-free, Fully Printable Mesoscopic Perovskite Solar Cells.

Science.gov (United States)

Zhang, Yumin; Zhao, Jianhong; Zhang, Jin; Jiang, Xixi; Zhu, Zhongqi; Liu, Qingju

2018-05-09

A printing process for the fabrication of perovskite solar cells (PSCs) exhibits promising future application in the photovoltaic industry due to its low-cost and eco-friendly preparation. In mesoscopic carbon-based PSCs, however, compared to conventional ones, the hole-transport-layer-free PSCs often lead to inefficient hole extraction. Here, we used liquid metal (LM, Galinstan) as an interface modifier material in combination with a carbon electrode. Considering the high conductivity and room-temperature fluidity, it is found that LMs are superior in improving hole extraction and, more importantly, LMs tend to be reserved at the interface between ZrO 2 and carbon for enhancing the contact property. Correspondingly, the carrier transfer resistance was decreased at the carbon/perovskite interface. As optimized content, the triple mesoscopic PSCs based on mixed-cation perovskite with a power conversion efficiency of 13.51% was achieved, involving a 26% increase compared to those without LMs. This work opens new techniques for LMs in optoelectronics and printing.

Detailed Simulation of Complex Hydraulic Problems with Macroscopic and Mesoscopic Mathematical Methods

Directory of Open Access Journals (Sweden)

Chiara Biscarini

2013-01-01

Full Text Available The numerical simulation of fast-moving fronts originating from dam or levee breaches is a challenging task for small scale engineering projects. In this work, the use of fully three-dimensional Navier-Stokes (NS equations and lattice Boltzmann method (LBM is proposed for testing the validity of, respectively, macroscopic and mesoscopic mathematical models. Macroscopic simulations are performed employing an open-source computational fluid dynamics (CFD code that solves the NS combined with the volume of fluid (VOF multiphase method to represent free-surface flows. The mesoscopic model is a front-tracking experimental variant of the LBM. In the proposed LBM the air-gas interface is represented as a surface with zero thickness that handles the passage of the density field from the light to the dense phase and vice versa. A single set of LBM equations represents the liquid phase, while the free surface is characterized by an additional variable, the liquid volume fraction. Case studies show advantages and disadvantages of the proposed LBM and NS with specific regard to the computational efficiency and accuracy in dealing with the simulation of flows through complex geometries. In particular, the validation of the model application is developed by simulating the flow propagating through a synthetic urban setting and comparing results with analytical and experimental laboratory measurements.

Functional energy nanocomposites surfaces based on mesoscopic microspheres, polymers and graphene flakes

Science.gov (United States)

Alekseev, S. A.; Dmitriev, A. S.; Dmitriev, A. A.; Makarov, P. G.; Mikhailova, I. A.

2017-11-01

In recent years, there has been a great interest in the development and creation of new functional energy materials, including for improving the energy efficiency of power equipment and for effectively removing heat from energy devices, microelectronics and optoelectronics (power micro electronics, supercapacitors, cooling of processors, servers and Data centers). In this paper, the technology of obtaining a new nanocomposite based on mesoscopic microspheres, polymers and graphene flakes is considered. The methods of sequential production of functional materials from graphite flakes of different volumetric concentration using polymers based on epoxy resins and polyimide, as well as the addition of a mesoscopic medium in the form of monodisperse microspheres are described. The data of optical and electron microscopy of such nanocomposites are presented, the main problems in the appearance of defects in such materials are described, the possibilities of their elimination by the selection of different concentrations and sizes of the components. Data are given on the measurement of the hysteresis of the contact angle and the evaporation of droplets on similar substrates. The results of studying the mechanical, electrophysical and thermal properties of such nanocomposites are presented. Particular attention is paid to the investigation of the thermal conductivity of these nanocomposites with respect to the creation of thermal interface materials for cooling devices of electronics, optoelectronics and power engineering.

A mesoscopic reaction rate model for shock initiation of multi-component PBX explosives.

Science.gov (United States)

Liu, Y R; Duan, Z P; Zhang, Z Y; Ou, Z C; Huang, F L

2016-11-05

The primary goal of this research is to develop a three-term mesoscopic reaction rate model that consists of a hot-spot ignition, a low-pressure slow burning and a high-pressure fast reaction terms for shock initiation of multi-component Plastic Bonded Explosives (PBX). Thereinto, based on the DZK hot-spot model for a single-component PBX explosive, the hot-spot ignition term as well as its reaction rate is obtained through a "mixing rule" of the explosive components; new expressions for both the low-pressure slow burning term and the high-pressure fast reaction term are also obtained by establishing the relationships between the reaction rate of the multi-component PBX explosive and that of its explosive components, based on the low-pressure slow burning term and the high-pressure fast reaction term of a mesoscopic reaction rate model. Furthermore, for verification, the new reaction rate model is incorporated into the DYNA2D code to simulate numerically the shock initiation process of the PBXC03 and the PBXC10 multi-component PBX explosives, and the numerical results of the pressure histories at different Lagrange locations in explosive are found to be in good agreements with previous experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Nonlinear dynamics in a laser field: spontaneous oscillation of mesoscopic soft matter

CERN Document Server

Nomura, S; Yoshikawa, K

2003-01-01

Experimental studies on the utilization of a laser to create a thermodynamically open system in a mesoscopic scale have been performed, where the laser has the roles to generate attractive and scattering forces on an optically trapped object. We have succeeded in the observation of various novel oscillatory phenomena under laser illumination. In this paper, we present the results of new experiments on the cyclic oscillation of a single giant molecule and periodic bursting in a cluster of micrometer sized beads.

Surface structure of polymer Gels and emerging functions

CERN Document Server

Kobiki, Y

1999-01-01

We report the surface structure of polymer gels on a submicrometer scale during the volume phase transition. Sponge-like domains with a mesoscopic scale were directly observed in water by using at atomic force microscope (AFM). The surface structure characterized by the domains is discussed in terms of the root-mean-square roughness and the auto-correlation function, which were calculated from the AFM images. In order to demonstrate the role of surface structure in determining the macroscopic properties of film-like poly (N-isopropylacrylamide: NIPA) gels. It was found that the temperature dependence, as well as the absolute values of the static contact angle, were strongly dependent on the bulk network inhomogeneities. The relation between the mesoscopic structure and the macroscopic properties is qualitatively discussed in terms of not only the changes in the chemical, but also in the physical, surface properties of the NIPA gels in response to a temperature change.

The causal structure of utility conditionals.

Science.gov (United States)

Bonnefon, Jean-François; Sloman, Steven A

2013-01-01

The psychology of reasoning is increasingly considering agents' values and preferences, achieving greater integration with judgment and decision making, social cognition, and moral reasoning. Some of this research investigates utility conditionals, ''if p then q'' statements where the realization of p or q or both is valued by some agents. Various approaches to utility conditionals share the assumption that reasoners make inferences from utility conditionals based on the comparison between the utility of p and the expected utility of q. This article introduces a new parameter in this analysis, the underlying causal structure of the conditional. Four experiments showed that causal structure moderated utility-informed conditional reasoning. These inferences were strongly invited when the underlying structure of the conditional was causal, and significantly less so when the underlying structure of the conditional was diagnostic. This asymmetry was only observed for conditionals in which the utility of q was clear, and disappeared when the utility of q was unclear. Thus, an adequate account of utility-informed inferences conditional reasoning requires three components: utility, probability, and causal structure. Copyright © 2012 Cognitive Science Society, Inc.

Distributed Dynamic Condition Response Structures

DEFF Research Database (Denmark)

Hildebrandt, Thomas; Mukkamala, Raghava Rao

We present distributed dynamic condition response structures as a declarative process model inspired by the workflow language employed by our industrial partner and conservatively generalizing labelled event structures. The model adds to event structures the possibility to 1) finitely specify...... as a labelled transition system. Exploration of the relationship between dynamic condition response structures and traditional models for concurrency, application to more complex scenarios, and further extensions of the model is left to future work....

Out-of-equilibrium spin transport in mesoscopic superconductors.

Science.gov (United States)

Quay, C H L; Aprili, M

2018-08-06

The excitations in conventional superconductors, Bogoliubov quasi-particles, are spin-[Formula: see text] fermions but their charge is energy-dependent and, in fact, zero at the gap edge. Therefore, in superconductors (unlike normal metals) spin and charge degrees of freedom may be separated. In this article, we review spin injection into conventional superconductors and focus on recent experiments on mesoscopic superconductors. We show how quasi-particle spin transport and out-of-equilibrium spin-dependent superconductivity can be triggered using the Zeeman splitting of the quasi-particle density of states in thin-film superconductors with small spin-mixing scattering. Finally, we address the spin dynamics and the feedback of quasi-particle spin imbalances on the amplitude of the superconducting energy gap.This article is part of the theme issue 'Andreev bound states'. © 2018 The Author(s).

Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

Science.gov (United States)

Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

2015-07-03

The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

Effect of the dielectric constant of mesoscopic particle on the exciton binding energy

International Nuclear Information System (INIS)

Lai Zuyou; Gu Shiwei

1991-09-01

For materials with big exciton reduced mass and big dielectric constant, such as TiO 2 , the variation of dielectric constant with the radius of an ultrafine particle (UFP) is important for determining the exciton binding energy. For the first time a phenomenological formula of the dielectric constant of a UFP with its radius in mesoscopic range is put forward in order to explain the optical properties of TiO 2 UFP. (author). 22 refs, 3 figs, 1 tab

Influence of gamma-irradiation on thermally-induced mesoscopic gelation of degalactosylated xyloglucans

International Nuclear Information System (INIS)

Todaro, S.; Sabatino, M.A.; Walo, M.; Mangione, M.R.; Bulone, D.; Dispenza, C.

2014-01-01

Thermoresponsive degalactosylated xyloglucans have been already proposed as in situ gelling scaffolds for tissue engineering, due to their reversible macroscopic thermal gelation at body temperature and biodegradability. The highly branched, hydroxyl group-rich molecular structure renders xyloglucans interesting raw materials also in the form of micro/nanoparticles for application as nanoscalar drug delivery devices in cosmetic and pharmaceutical formulations. Owing to their natural source, xyloglucans show high average molecular weight, broad molecular weight distribution and poor water solubility, as large and compact aggregates usually form via inter-molecular hydrogen bonding. 60 Co γ-irradiation has been here applied to reduce the molecular weight. The aqueous solutions of irradiated xyloglucan were characterized by dynamic light scattering measurements and gel filtration chromatography. The aggregation kinetics at 37 °C were studied by dynamic light scattering measurements to confirm the temperature-responsive behavior of this polymer even when dispersed in water at low concentration after γ-irradiation. Irradiation dose–molecular properties relationship has been sought. - Highlights: • Influence of γ-irradiation on a partially degalactosylated xyloglucan is investigated. • Molecular weight reduction is observed in the investigated dose range. • Modification of the temperature-induced mesoscopic gelation kinetics is evidenced

Production and Detection of Spin-Entangled Electrons in Mesoscopic Conductors

Science.gov (United States)

Burkard, Guido

2006-03-01

Electron spins are an extremely versatile form of quantum bits. When localized in quantum dots, they can form a register for quantum computation. Moreover, being attached to a charge in a mesoscopic conductor allows the electron spin to play the role of a mobile carrier of quantum information similarly to photons in optical quantum communication. Since entanglement is a basic resource in quantum communication, the production and detection of spin-entangled Einstein-Podolsky-Rosen (EPR) pairs of electrons are of great interest. Besides the practical importance, it is of fundamental interest to test quantum non-locality for electrons. I review the theoretical schemes for the entanglement production in superconductor-normal junctions [1] and other systems. The electron spin entanglement can be detected and quantified from measurements of the fluctuations (shot noise) of the charge current after the electrons have passed through an electronic beam splitter [2,3]. This two-particle interference effect is related to the Hanbury-Brown and Twiss experiment and leads to a doubling of the shot noise SI=φ=0 for spin-entangled states, allowing their differentiation from unentangled pairs. I report on the role of spin-orbit coupling (Rashba and Dresselhaus) in a complete characterization of the spin entanglement [4]. Finally, I address the effects of a discrete level spectrum in the mesoscopic leads and of backscattering and decoherence.[1] P. Recher, E. V. Sukhorukov, D. Loss, Phys. Rev. B 63, 165314 (2001)[2] G. Burkard, D. Loss, E. V. Sukhorukov, Phys. Rev. B 61, R16303 (2000)[3] G. Burkard and D. Loss, Phys. Rev. Lett.91, 087903 (2003)[4] J. C. Egues, G. Burkard, D. Saraga, J. Schliemann, D. Loss, cond-mat/0509038, to appear in Phys.Rev.B (2005).

Persistent currents in an ensemble of isolated mesoscopic rings

International Nuclear Information System (INIS)

Altland, A.; Iida, S.; Mueller-Groelling, A.; Weidenmueller, H.A.

1992-01-01

In this work, the authors calculate the persistent current induced at zero temperature by an external, constant, and homogeneous magnetic field in an ensemble of isolated mesoscopic rings. In each ring, the electrons are assumed to move independently under the influence of a Gaussian white noise random impurity potential. They account for the magnetic field only in terms of the flux threading each ring, without considering the field present in the body of the ring. Particular attention is paid to the constraint of integer particle number on each ring. The authors evaluate the persistent current non-perturbatively, using a generating functional involving Grassmann integration. The magnetic flux threading each ring breaks the orthogonal symmetry of the formalism; forcing us to calculate explicitly the orthogonal-unitary crossover. 24 refs., 1 fig

A Mesoscopic Analytical Model to Predict the Onset of Wrinkling in Plain Woven Preforms under Bias Extension Shear Deformation

Directory of Open Access Journals (Sweden)

Abbas Hosseini

2017-10-01

Full Text Available A mesoscopic analytical model of wrinkling of Plain-Woven Composite Preforms (PWCPs under the bias extension test is presented, based on a new instability analysis. The analysis is aimed to facilitate a better understanding of the nature of wrinkle formation in woven fabrics caused by large in-plane shear, while it accounts for the effect of fabric and process parameters on the onset of wrinkling. To this end, the mechanism of wrinkle formation in PWCPs in mesoscale is simplified and an equivalent structure composed of bars and different types of springs is proposed, mimicking the behavior of a representative PWCP element at the post-locking state. The parameters of this equivalent structure are derived based on geometric and mechanical characteristics of the PWCP. The principle of minimum total potential energy is employed to formluate the model, and experimental validation is carried out to reveal the effectiveness of the derived wrinkling prediction equation.

Meta-Structures: The Search of Coherence in Collective Behaviours (without Physics

Directory of Open Access Journals (Sweden)

Eliano Pessa

2013-09-01

Full Text Available This contribution shortly outlines and reviews a theoretical and computational approach for a theory of change concerning systems where it is not possible to apply the laws of motion ab initio. The concept of meta-structure relates to the emergence of forms of spatiotemporal coherences in collective behaviours intended as coherent sequences of multiple structures. The essential difference compared with traditional methods is the role of the cognitive design by the observer when identifying multiple mesoscopic variables. The goal is both to study the "change without physics" of the dynamics of change and to design non-catastrophic interventions having the purpose to induce, change, keep or restore collective behaviours by influencing -at the mesoscopic level -and not prescribing explicit rules and changes.

Mesoscopic fluctuations and intermittency in aging dynamics

Science.gov (United States)

Sibani, P.

2006-01-01

Mesoscopic aging systems are characterized by large intermittent noise fluctuations. In a record dynamics scenario (Sibani P. and Dall J., Europhys. Lett., 64 (2003) 8) these events, quakes, are treated as a Poisson process with average αln (1 + t/tw), where t is the observation time, tw is the age and α is a parameter. Assuming for simplicity that quakes constitute the only source of de-correlation, we present a model for the probability density function (PDF) of the configuration autocorrelation function. Beside α, the model has the average quake size 1/q as a parameter. The model autocorrelation PDF has a Gumbel-like shape, which approaches a Gaussian for large t/tw and becomes sharply peaked in the thermodynamic limit. Its average and variance, which are given analytically, depend on t/tw as a power law and a power law with a logarithmic correction, respectively. Most predictions are in good agreement with data from the literature and with the simulations of the Edwards-Anderson spin-glass carried out as a test.

Mesoscopic analyses of porous concrete under static compression and drop weight impact tests

DEFF Research Database (Denmark)

Agar Ozbek, A.S.; Pedersen, R.R.; Weerheijm, J.

2008-01-01

was considered as a four-phase material incorporating aggregates, bulk cement paste, interfacial transition zones and meso-size air pores. The stress-displacement relations obtained from static compression tests, the stress values, and the corresponding damage levels provided by the drop weight impact tests were......The failure process in highly porous concrete was analyzed experimentally and numerically. A triaxial visco-plastic damage model and a mesoscale representation of the material composition were considered to reproduce static compression and drop weight impact tests. In the mesoscopic model, concrete...

Impact parameter determination for the passage of cosmic heavy ions through mesoscopic biological test organisms

International Nuclear Information System (INIS)

Facius, R.; Reitz, G.; Buecker, H.; Nevzgodina, L.V.; Maximova, E.N.

1992-01-01

Seeds of the plant Lactuca sativa as a prototype of a mesoscopic, i.e. neither micro- nor truly macroscopic, biological test organism, were exposed during the Biocosmos 9 mission to cosmic heavy ions within stacks of visual track detectors in order to explore the not yet properly understood radiobiological effects of single heavy ions. In such an investigation, the establishment of the geometrical correlation between the ion trajectories and the location of radiation-sensitive biological substructures is an essential task. We describe how this was achieved for biological test organisms, whose location and orientation had to be derived from contact photographs displaying their outlines and those of the holder plates only. The overall qualitative and quantitative precision achieved, as well as the contributing sources of uncertainties are discussed in detail. A precision of ≅ 10μm was accomplished for the coordinates of particle trajectories, which is near the limit set by the mechanical precision and stability of the detector material. The precision of the impact parameter is limited by the uncertainty in the location of the internal structures, which at best is around 50 and at worst around 150 μm, but is still acceptable when compared with the extension of the sensitive structures. (author)

Impact parameter determination for the passage of cosmic heavy ions through mesoscopic biological test organisms

Energy Technology Data Exchange (ETDEWEB)

Facius, R.; Reitz, G.; Buecker, H. (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany)); Nevzgodina, L.V.; Maximova, E.N. (Institute of Biomedical Problems, Moscow (USSR))

1992-01-01

Seeds of the plant Lactuca sativa as a prototype of a mesoscopic, i.e. neither micro- nor truly macroscopic, biological test organism, were exposed during the Biocosmos 9 mission to cosmic heavy ions within stacks of visual track detectors in order to explore the not yet properly understood radiobiological effects of single heavy ions. In such an investigation, the establishment of the geometrical correlation between the ion trajectories and the location of radiation-sensitive biological substructures is an essential task. We describe how this was achieved for biological test organisms, whose location and orientation had to be derived from contact photographs displaying their outlines and those of the holder plates only. The overall qualitative and quantitative precision achieved, as well as the contributing sources of uncertainties are discussed in detail. A precision of {approx equal} 10{mu}m was accomplished for the coordinates of particle trajectories, which is near the limit set by the mechanical precision and stability of the detector material. The precision of the impact parameter is limited by the uncertainty in the location of the internal structures, which at best is around 50 and at worst around 150 {mu}m, but is still acceptable when compared with the extension of the sensitive structures. (author).

Vortex patterns in a mesoscopic superconducting rod with a magnetic dot

Energy Technology Data Exchange (ETDEWEB)

Romaguera, Antonio R. de C. [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Dept. de Fisica; Doria, Mauro M. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Dept. de Fisica dos Solidos; Peeters, F.M. [Universiteit Antwerpen (Belgium). Dept. Fysica

2009-07-01

Full text follows. Magnetism and superconductivity are competing orders and its coexistence has been the subject of intense investigation both in nano fabricated materials also in natural compounds. Together they bring new phenomena such as in case of magnetic dots on top of a superconducting film which are a source of ratchet potential.Recently we have investigated vortex patterns that originate from a magnetic domain internal to the superconductor. There vortex lines are curved in space, as their only source and sinkhole are inside the superconductor. We found that when the magnetic domain has a small magnetic moment, the vortex pattern is made of just three vortex loops, instead of one, two or any higher number of vortex loops. The presence of a magnetic moment near thin mesoscopic disks and films has been theoretically and experimentally investigated. New vortex patterns arise there due to the inhomogeneity of the applied magnetic field, although they do not display curved vortices because of the thin limit which turns the vortices into flat two-dimensional objects. In this work we report a theoretical investigation of vortex patterns into a mesoscopic superconducting rod with an external magnetic dot on top. We call it rod to characterize that its height is finite and comparable to the radius, thus larger than a disk and smaller than a wire. Inside the rod, a cylinder with height larger than the coherence length, {xi}, truly three-dimensional curved vortices are formed. We find reentrant behavior which means that the entrance and exit of a vortex is achieved by simply increasing (or decreasing) the intensity of the magnetic field generated by the dot. Thus the present system qualifies for technological applications as a logic gate to perform logical operation in digital circuits.

Vortex patterns in a mesoscopic superconducting rod with a magnetic dot

International Nuclear Information System (INIS)

Romaguera, Antonio R. de C.; Doria, Mauro M.; Peeters, F.M.

2009-01-01

Full text follows. Magnetism and superconductivity are competing orders and its coexistence has been the subject of intense investigation both in nano fabricated materials also in natural compounds. Together they bring new phenomena such as in case of magnetic dots on top of a superconducting film which are a source of ratchet potential.Recently we have investigated vortex patterns that originate from a magnetic domain internal to the superconductor. There vortex lines are curved in space, as their only source and sinkhole are inside the superconductor. We found that when the magnetic domain has a small magnetic moment, the vortex pattern is made of just three vortex loops, instead of one, two or any higher number of vortex loops. The presence of a magnetic moment near thin mesoscopic disks and films has been theoretically and experimentally investigated. New vortex patterns arise there due to the inhomogeneity of the applied magnetic field, although they do not display curved vortices because of the thin limit which turns the vortices into flat two-dimensional objects. In this work we report a theoretical investigation of vortex patterns into a mesoscopic superconducting rod with an external magnetic dot on top. We call it rod to characterize that its height is finite and comparable to the radius, thus larger than a disk and smaller than a wire. Inside the rod, a cylinder with height larger than the coherence length, ξ, truly three-dimensional curved vortices are formed. We find reentrant behavior which means that the entrance and exit of a vortex is achieved by simply increasing (or decreasing) the intensity of the magnetic field generated by the dot. Thus the present system qualifies for technological applications as a logic gate to perform logical operation in digital circuits.

Mechanical aspects of allotropic phase change at the mesoscopic scale

International Nuclear Information System (INIS)

Valance, St.

2007-12-01

The prediction of the mechanical state of steel structures submit to thermo-mechanical loading must take into account consequences of allotropic phase change. Indeed, phase change induce, at least for steels, a mechanism of TRansformation Induced Plasticity (TRIP) leading to irreversible deformation even for loading less than elastic yield limit. Homogenized analytical models generally fail to achieve a correct prediction for complex loading. In order to overcome these difficulties, we present a model achieving a sharper description of the phenomenon. The mesoscopic working scale we adopt here is the grain scale size. Hence, we consider that the behaviour of each phase is homogenous in the sense of continuous media mechanic, whereas the front is explicitly described. We work both experimentally and numerically. Experimentally, we designed a test facility enabling thermo mechanical loading of the sample under partial vacuum. Acquisition of sample surface while martensitic transformation is happening leads, under some hypothesis and thanks to Digital Image Correlation, to the partial identification of area affected by transformation. Numerically, the eXtended Finite Element Method is applied for weakly discontinuous displacement fields. Used of this method needs to numerically track the transformation front -discontinuity support. In that goal, based on level set method, we develop FEM numerical scheme enabling recognition and propagation of discontinuity support. Finally, this work is complete by an approach of driving forces introduced through Eshelbian mechanics which are dual of front velocity. (author)

Fiscal 1998 research report. R and D on super metal (Al system mesoscopic texture-controlled material); 1998 nendo seika hokokusho. Super metal no gijutsu kaihatsu (aluminium kei mesoscopic soshiki seigyo zairyo no gijutsu kaihatsu)

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

For development of Al materials with superior industrial characteristics (strength, corrosion resistance), this research has promoted development of large-size Al system materials with mesoscopic crystalline texture by high- strain accumulation control technology, and recovery and recrystallization control technology. In this fiscal year, (1) basic study on high-strain accumulation control technology, (2) study on a formation mechanism of ultra- fine crystal grains, and (3) development of a machining process were made. In (1), basic study on low-temperature rolling and study on rolling by rollers having different peripheral speeds were made. In (2), study on refining of recrystallized grains of 5000-base and 7000-base alloys was made. In (3), a low-temperature rolling equipment, and a ultra-rapid heating device were introduced. For the whole R and D project on super metal, the main research facilities such as a low-temperature rolling body for high- strain accumulation and a high-strain accumulative structure formation equipment (melt rolling equipment) for uniform nucleus formation in recrystallization were introduced to gain a firm foothold for the future application research. (NEDO)

Measurement of mesoscopic high-Tc superconductors using Si mechanical micro-oscillators

International Nuclear Information System (INIS)

Dolz, M.; Antonio, D.; Pastoriza, H.

2007-01-01

In a superconducting mesoscopic sample, with dimensions comparable to the London penetration depth, some properties are qualitatively different to those found in the bulk material. These properties include magnetization, vortex dynamics and ordering of the vortex lattice. In order to detect the small signals produced by this kind of samples, new instruments designed for the microscale are needed. In this work we use micromechanical oscillators to study the magnetic properties of a Bi 2 Sr 2 CaCu 2 O 8+δ disk with a diameter of 13.5μm and a thickness of 2.5μm. The discussion of our results is based on the existence and contribution of inter and intra layer currents

Mesoscopic conductance fluctuations in high-T{sub c} grain boundary Josephson junctions: Coherent quasiparticle transport

Energy Technology Data Exchange (ETDEWEB)

Tafuri, F. [Dip. Ingegneria dell' Informazione, Seconda Universita di Napoli, 81031 Aversa (Italy); CNR-INFM Coherentia, Dip. Scienze Fisiche, Universita di Napoli Federico II, 80125 Naples (Italy)], E-mail: tafuri@na.infn.it; Tagliacozzo, A.; Born, D.; Stornaiuolo, D. [CNR-INFM Coherentia, Dip. Scienze Fisiche, Universita di Napoli Federico II, 80125 Naples (Italy); Gambale, E.; Dalena, D. [Dip. Ingegneria dell' Informazione, Seconda Universita di Napoli, 81031 Aversa (Italy); Lombardi, F. [Department of Microelectronics and Nanoscience, MINA, Chalmers University of Technology, 41296 Goeteborg (Sweden)

2007-09-01

Magneto-fluctuations of the normal resistance R{sub N} have been reproducibly observed in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (HTS) biepitaxial grain boundary junctions at low temperatures. We attribute them to mesoscopic transport in narrow channels across the grain boundary line. The Thouless energy appears to be the relevant energy scale. Possible implications on the understanding of coherent transport of quasiparticles in HTS and of the dissipation mechanisms are discussed.

Reaction-Transport Systems Mesoscopic Foundations, Fronts, and Spatial Instabilities

CERN Document Server

Horsthemke, Werner; Mendez, Vicenc

2010-01-01

This book is an introduction to the dynamics of reaction-diffusion systems, with a focus on fronts and stationary spatial patterns. Emphasis is on systems that are non-standard in the sense that either the transport is not simply classical diffusion (Brownian motion) or the system is not homogeneous. A important feature is the derivation of the basic phenomenological equations from the mesoscopic system properties. Topics addressed include transport with inertia, described by persistent random walks and hyperbolic reaction-transport equations and transport by anomalous diffusion, in particular subdiffusion, where the mean square displacement grows sublinearly with time. In particular reaction-diffusion systems are studied where the medium is in turn either spatially inhomogeneous, compositionally heterogeneous or spatially discrete. Applications span a vast range of interdisciplinary fields and the systems considered can be as different as human or animal groups migrating under external influences, population...

Interplay between mesoscopic phase separation and bulk magnetism in the layered Na.sub.x./sub.CoO.sub.2./sub

Czech Academy of Sciences Publication Activity Database

Zorkovská, A.; Orendáč, M.; Šebek, Josef; Šantavá, Eva; Svoboda, P.; Bradaric, I.; Savič, I.; Feher, A.

2005-01-01

Roč. 72, č. 13 (2005), 132412/1-132412/4 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100520 Keywords : Na x CoO 2 * mesoscopic phase separation * bulk magnetism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.185, year: 2005

Structure of S-shaped growth in innovation diffusion

Science.gov (United States)

Shimogawa, Shinsuke; Shinno, Miyuki; Saito, Hiroshi

2012-05-01

A basic question on innovation diffusion is why the growth curve of the adopter population in a large society is often S shaped. From macroscopic, microscopic, and mesoscopic viewpoints, the growth of the adopter population is observed as the growth curve, individual adoptions, and differences among individual adoptions, respectively. The S shape can be explained if an empirical model of the growth curve can be deduced from models of microscopic and mesoscopic structures. However, even the structure of growth curve has not been revealed yet because long-term extrapolations by proposed models of S-shaped curves are unstable and it has been very difficult to predict the long-term growth and final adopter population. This paper studies the S-shaped growth from the viewpoint of social regularities. Simple methods to analyze power laws enable us to extract the structure of the growth curve directly from the growth data of recent basic telecommunication services. This empirical model of growth curve is singular at the inflection point and a logarithmic function of time after this point, which explains the unstable extrapolations obtained using previously proposed models and the difficulty in predicting the final adopter population. Because the empirical S curve can be expressed in terms of two power laws of the regularity found in social performances of individuals, we propose the hypothesis that the S shape represents the heterogeneity of the adopter population, and the heterogeneity parameter is distributed under the regularity in social performances of individuals. This hypothesis is so powerful as to yield models of microscopic and mesoscopic structures. In the microscopic model, each potential adopter adopts the innovation when the information accumulated by the learning about the innovation exceeds a threshold. The accumulation rate of information is heterogeneous among the adopter population, whereas the threshold is a constant, which is the opposite of previously

Using Models at the Mesoscopic Scale in Teaching Physics: Two Experimental Interventions in Solid Friction and Fluid Statics

Science.gov (United States)

Besson, Ugo; Viennot, Laurence

2004-01-01

This article examines the didactic suitability of introducing models at an intermediate (i.e. mesoscopic) scale in teaching certain subjects, at an early stage. The design and evaluation of two short sequences based on this rationale will be outlined: one bears on propulsion by solid friction, the other on fluid statics in the presence of gravity.…

Quantum Coherence and Random Fields at Mesoscopic Scales

International Nuclear Information System (INIS)

Rosenbaum, Thomas F.

2016-01-01

We seek to explore and exploit model, disordered and geometrically frustrated magnets where coherent spin clusters stably detach themselves from their surroundings, leading to extreme sensitivity to finite frequency excitations and the ability to encode information. Global changes in either the spin concentration or the quantum tunneling probability via the application of an external magnetic field can tune the relative weights of quantum entanglement and random field effects on the mesoscopic scale. These same parameters can be harnessed to manipulate domain wall dynamics in the ferromagnetic state, with technological possibilities for magnetic information storage. Finally, extensions from quantum ferromagnets to antiferromagnets promise new insights into the physics of quantum fluctuations and effective dimensional reduction. A combination of ac susceptometry, dc magnetometry, noise measurements, hole burning, non-linear Fano experiments, and neutron diffraction as functions of temperature, magnetic field, frequency, excitation amplitude, dipole concentration, and disorder address issues of stability, overlap, coherence, and control. We have been especially interested in probing the evolution of the local order in the progression from spin liquid to spin glass to long-range-ordered magnet.

Quantum Coherence and Random Fields at Mesoscopic Scales

Energy Technology Data Exchange (ETDEWEB)

Rosenbaum, Thomas F. [Univ. of Chicago, IL (United States)

2016-03-01

We seek to explore and exploit model, disordered and geometrically frustrated magnets where coherent spin clusters stably detach themselves from their surroundings, leading to extreme sensitivity to finite frequency excitations and the ability to encode information. Global changes in either the spin concentration or the quantum tunneling probability via the application of an external magnetic field can tune the relative weights of quantum entanglement and random field effects on the mesoscopic scale. These same parameters can be harnessed to manipulate domain wall dynamics in the ferromagnetic state, with technological possibilities for magnetic information storage. Finally, extensions from quantum ferromagnets to antiferromagnets promise new insights into the physics of quantum fluctuations and effective dimensional reduction. A combination of ac susceptometry, dc magnetometry, noise measurements, hole burning, non-linear Fano experiments, and neutron diffraction as functions of temperature, magnetic field, frequency, excitation amplitude, dipole concentration, and disorder address issues of stability, overlap, coherence, and control. We have been especially interested in probing the evolution of the local order in the progression from spin liquid to spin glass to long-range-ordered magnet.

Thermal-mechanical-chemical responses of polymer-bonded explosives using a mesoscopic reactive model under impact loading.

Science.gov (United States)

Wang, XinJie; Wu, YanQing; Huang, FengLei

2017-01-05

A mesoscopic framework is developed to quantify the thermal-mechanical-chemical responses of polymer-bonded explosive (PBX) samples under impact loading. A mesoscopic reactive model is developed for the cyclotetramethylenetetranitramine (HMX) crystal, which incorporates nonlinear elasticity, crystal plasticity, and temperature-dependent chemical reaction. The proposed model was implemented in the finite element code ABAQUS by the user subroutine VUMAT. A series of three-dimensional mesoscale models were constructed and calculated under low-strength impact loading scenarios from 100m/s to 600m/s where only the first wave transit is studied. Crystal anisotropy and microstructural heterogeneity are responsible for the nonuniform stress field and fluctuations of the stress wave front. At a critical impact velocity (≥300m/s), a chemical reaction is triggered because the temperature contributed by the volumetric and plastic works is sufficiently high. Physical quantities, including stress, temperature, and extent of reaction, are homogenized from those across the microstructure at the mesoscale to compare with macroscale measurements, which will advance the continuum-level models. The framework presented in this study has important implications in understanding hot spot ignition processes and improving predictive capabilities in energetic materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Broadband giant-refractive-index material based on mesoscopic space-filling curves

Science.gov (United States)

Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

2016-08-01

The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain 1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications.

Universal shape characteristics for the mesoscopic star-shaped polymer via dissipative particle dynamics simulations

Science.gov (United States)

Kalyuzhnyi, O.; Ilnytskyi, J. M.; Holovatch, Yu; von Ferber, C.

2018-05-01

In this paper we study the shape characteristics of star-like polymers in various solvent quality using a mesoscopic level of modeling. The dissipative particle dynamics simulations are performed for the homogeneous and four different heterogeneous star polymers with the same molecular weight. We analyse the gyration radius and asphericity at the poor, good and θ-solvent regimes. Detailed explanation based on interplay between enthalpic and entropic contributions to the free energy and analyses on of the asphericity of individual branches are provided to explain the increase of the apsphericity in θ-solvent regime.

Collective excitability in a mesoscopic neuronal model of epileptic activity

Science.gov (United States)

Jedynak, Maciej; Pons, Antonio J.; Garcia-Ojalvo, Jordi

2018-01-01

At the mesoscopic scale, the brain can be understood as a collection of interacting neuronal oscillators, but the extent to which its sustained activity is due to coupling among brain areas is still unclear. Here we address this issue in a simplified situation by examining the effect of coupling between two cortical columns described via Jansen-Rit neural mass models. Our results show that coupling between the two neuronal populations gives rise to stochastic initiations of sustained collective activity, which can be interpreted as epileptic events. For large enough coupling strengths, termination of these events results mainly from the emergence of synchronization between the columns, and thus it is controlled by coupling instead of noise. Stochastic triggering and noise-independent durations are characteristic of excitable dynamics, and thus we interpret our results in terms of collective excitability.

Comparison of the electrochemical performance of mesoscopic Cu2Sb, SnSb and Sn/SnSb alloy powders

International Nuclear Information System (INIS)

Zhang Ge; Huang Kelong; Liu Suqin; Zhang Wei; Gong Benli

2006-01-01

Cu 2 Sb, SnSb and Sn/SnSb mesoscopic alloy powders were prepared by chemical reduction, respectively. The crystal structures and particle morphology of Cu 2 Sb, SnSb and Sn/SnSb were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The electrochemical performances of the Cu 2 Sb, SnSb and Sn/SnSb electrodes were investigated by galvanostatic charge and discharge cycling and electrochemical impedance spectroscopy (EIS). The results showed the first charge and discharge capacities of SnSb and Sn/SnSb were higher than Cu 2 Sb, but after 15 cycles, the charge capacity fading rates of Cu 2 Sb, Sn/SnSb and Sn/SnSb were 26.16%, 55.33% and 47.39%, respectively. Cu 2 Sb had a better cycle performance, and Sn/SnSb multiphase alloy was prior to pure SnSb due to the existence of excessive Sn in Sn/SnSb system

Mesoscopic model of actin-based propulsion.

Directory of Open Access Journals (Sweden)

Jie Zhu

Full Text Available Two theoretical models dominate current understanding of actin-based propulsion: microscopic polymerization ratchet model predicts that growing and writhing actin filaments generate forces and movements, while macroscopic elastic propulsion model suggests that deformation and stress of growing actin gel are responsible for the propulsion. We examine both experimentally and computationally the 2D movement of ellipsoidal beads propelled by actin tails and show that neither of the two models can explain the observed bistability of the orientation of the beads. To explain the data, we develop a 2D hybrid mesoscopic model by reconciling these two models such that individual actin filaments undergoing nucleation, elongation, attachment, detachment and capping are embedded into the boundary of a node-spring viscoelastic network representing the macroscopic actin gel. Stochastic simulations of this 'in silico' actin network show that the combined effects of the macroscopic elastic deformation and microscopic ratchets can explain the observed bistable orientation of the actin-propelled ellipsoidal beads. To test the theory further, we analyze observed distribution of the curvatures of the trajectories and show that the hybrid model's predictions fit the data. Finally, we demonstrate that the model can explain both concave-up and concave-down force-velocity relations for growing actin networks depending on the characteristic time scale and network recoil. To summarize, we propose that both microscopic polymerization ratchets and macroscopic stresses of the deformable actin network are responsible for the force and movement generation.

p-type Mesoscopic nickel oxide/organometallic perovskite heterojunction solar cells.

Science.gov (United States)

Wang, Kuo-Chin; Jeng, Jun-Yuan; Shen, Po-Shen; Chang, Yu-Cheng; Diau, Eric Wei-Guang; Tsai, Cheng-Hung; Chao, Tzu-Yang; Hsu, Hsu-Cheng; Lin, Pei-Ying; Chen, Peter; Guo, Tzung-Fang; Wen, Ten-Chin

2014-04-23

In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.

Kinetically guided colloidal structure formation

OpenAIRE

Hecht, Fabian M.; Bausch, Andreas R.

2016-01-01

The well-studied self-organization of colloidal particles is predicted to result in a variety of fascinating applications. Yet, whereas self-assembly techniques are extensively explored, designing and producing mesoscale-sized objects remains a major challenge, as equilibration times and thus structure formation timescales become prohibitively long. Asymmetric mesoscopic objects, without prior introduction of asymmetric particles with all its complications, are out of reach––due to the underl...

Charge storage in mesoscopic graphitic islands fabricated using AFM bias lithography

Energy Technology Data Exchange (ETDEWEB)

Kurra, Narendra; Basavaraja, S; Kulkarni, G U [Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore 560 064 (India); Prakash, Gyan; Fisher, Timothy S; Reifenberger, Ronald G, E-mail: kulkarni@jncasr.ac.in, E-mail: reifenbr@purdue.edu [Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907 (United States)

2011-06-17

Electrochemical oxidation and etching of highly oriented pyrolytic graphite (HOPG) has been achieved using biased atomic force microscopy (AFM) lithography, allowing patterns of varying complexity to be written into the top layers of HOPG. The graphitic oxidation process and the trench geometry after writing were monitored using intermittent contact mode AFM. Electrostatic force microscopy reveals that the isolated mesoscopic islands formed during the AFM lithography process become positively charged, suggesting that they are laterally isolated from the surrounding HOPG substrate. The electrical transport studies of these laterally isolated finite-layer graphitic islands enable detailed characterization of electrical conduction along the c-direction and reveal an unexpected stability of the charged state. Utilizing conducting-atomic force microscopy, the measured I(V) characteristics revealed significant non-linearities. Micro-Raman studies confirm the presence of oxy functional groups formed during the lithography process.

Insight or illusion? seeing inside the cell with mesoscopic simulations

DEFF Research Database (Denmark)

Shillcock, Julian C.

2008-01-01

 the dynamics of spatially heterogeneous membranes and the crowded cytoplasmic environment to be followed at a modest computational cost. The price for such power is that the atomic detail of the constituents is much lower than in atomistic Molecular Dynamics simulations. We argue that this price is worth...... by spatial resolution and the speed of molecular rearrangements. The increase in computing power of the last few decades enables the construction of computational tools for observing cellular processes in silico. As experiments yield increasing amounts of data on the protein and lipid constituents...... of the cell, computer simulations parametrized using this data are beginning to allow models of cellular processes to be interrogated in ways unavailable in the laboratory. Mesoscopic simulations retain only those molecular features that are believed to be relevant to the processes of interest. This allows...

The effect of geometric scattering on the oscillatory magnetoconductance in multiply connected disordered mesoscopic rings

International Nuclear Information System (INIS)

Basu, C.; Gu Benyuan.

1994-12-01

We present the quantum mechanical calculations on the conductance of a quantum waveguide consisting of multiply connected mesoscopic rings with disordered ring-circumferences and ballistic lead connections between the rings with the transfer matrix approach. The profiles of the conductance as functions of the magnetic flux and the Fermi wave number of electrons depend on the number of rings as also on the geometric configuration of the system. The conductance spectrum of this system for disordered ring circumferences, disordered ring intervals and disordered magnetic flux is examined in detail. Studying the effect of geometric scattering and the two different length scales involved in the network, namely, the ring circumference and the ballistic lead connections on the conductance profile, we find that there exist two kinds of mini-bands, one originating from the bound states of the rings, i.e. the intrinsic mini-bands, and the other associated with the connecting leads between the adjacent rings, which are the extra mini-bands. These two kinds of mini-bands respond differently to external perturbations in parameters. Unlike the system of potential scatterers, this system of geometric scatterers show complete band formations at all energies even for finite systems and there is a preferential decay of the energy states depending upon the type of disorder introduced. The conductance band structures strongly depend on the geometric configuration of the network and so by controlling the geometric parameters, the conductance band structures can be artificially tailored. (author). 18 refs, 6 figs

Quantum solitonic wave-packet of a meso-scopic system in singularity free gravity

Science.gov (United States)

Buoninfante, Luca; Lambiase, Gaetano; Mazumdar, Anupam

2018-06-01

In this paper we will discuss how to localise a quantum wave-packet due to self-gravitating meso-scopic object by taking into account gravitational self-interaction in the Schrödinger equation beyond General Relativity. In particular, we will study soliton-like solutions in infinite derivative ghost free theories of gravity, which resolves the gravitational 1 / r singularity in the potential. We will show a unique feature that the quantum spread of such a gravitational system is larger than that of the Newtonian gravity, therefore enabling us a window of opportunity to test classical and quantum properties of such theories of gravity in the near future at a table-top experiment.

Modeling of electrical and mesoscopic circuits at quantum nanoscale from heat momentum operator

Science.gov (United States)

El-Nabulsi, Rami Ahmad

2018-04-01

We develop a new method to study electrical circuits at quantum nanoscale by introducing a heat momentum operator which reproduces quantum effects similar to those obtained in Suykens's nonlocal-in-time kinetic energy approach for the case of reversible motion. The series expansion of the heat momentum operator is similar to the momentum operator obtained in the framework of minimal length phenomenologies characterized by the deformation of Heisenberg algebra. The quantization of both LC and mesoscopic circuits revealed a number of motivating features like the emergence of a generalized uncertainty relation and a minimal charge similar to those obtained in the framework of minimal length theories. Additional features were obtained and discussed accordingly.

Enhanced Strain in Functional Nanoporous Gold with a Dual Microscopic Length Scale Structure

NARCIS (Netherlands)

Detsi, Eric; Punzhin, Sergey; Rao, Jiancun; Onck, Patrick R.; De Hosson, Jeff Th. M.

We have synthesized nanoporous Au with a dual microscopic length scale by exploiting the crystal structure of the alloy precursor. The synthesized mesoscopic material is characterized by stacked Au layers of submicrometer thickness. In addition, each layer displays nanoporosity through the entire

Simulation studies of protein-induced bilayer deformations, and lipid-induced protein tilting, on a mesoscopic model for lipid bilayers with embedded proteins

DEFF Research Database (Denmark)

Venturoli, M.; Smit, B.; Sperotto, Maria Maddalena

2005-01-01

membranes. Here we present a mesoscopic model for lipid bilayers with embedded proteins, which we have studied with the help of the dissipative particle dynamics simulation technique. Because hydrophobic matching is believed to be one of the main physical mechanisms regulating lipid-protein interactions......-induced protein tilt, with the hydrophobic mismatch ( positive and negative) between the protein hydrophobic length and the pure lipid bilayer hydrophobic thickness. The protein-induced bilayer perturbation was quantified in terms of a coherence length, xi(P), of the lipid bilayer hydrophobic thickness pro. le...... for positive values of mismatch; a dependence on the protein size appears as well. In the case of large model proteins experiencing extreme mismatch conditions, in the region next to the so-called lipid annulus, there appears an undershooting ( or overshooting) region where the bilayer hydrophobic thickness...

Micro-structural investigations of spray hydrolyzed TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Lakhotiya, H. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Centre for Converging Technologies, University of Rajasthan, Jaipur (India); Singh, Ripandeep; Bahadur, J. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Sen, D., E-mail: debasis@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Das, Avik; Mazumder, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Paul, B. [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Lemmel, H. [Atominstitut, Vienna University of Technology, 1020 Vienna (Austria); Institut Laue-Langevin, 38000 Grenoble (France)

2014-01-25

Highlights: • Titania microstructure formation by spray hydrolysis. • Morphological transition during spray hydrolysis process. • Hollow microspheres and fractal like grains depending on precursor concentration. • Use of scattering and microscopy techniques in probing mesoscopic structures. • A plausible mechanism regarding the morphological transition is also introduced. -- Abstract: Hydrolysis across tiny spray droplet allows a facile one step synthesis of interesting sub-micrometric structures owing to the large available surface area unlike bulk hydrolysis. In the present work, it has been demonstrated that titania precursor concentration plays a significant role in effecting morphological transformation during spray hydrolysis. While hollow microspheres are formed primarily at low precursor concentration, fractal like grains, having two levels of hierarchy, result at high precursor concentration. Mesoscopic structure of these spray hydrolyzed grains has been investigated by ultra small-angle neutron scattering, small-angle X-ray scattering and scanning electron microscopy. Thermal evolution of initial amorphous phase of titania into crystalline rutile phase, through intermediate anatase and brookite phases, is followed by high temperature X-ray diffraction. A plausible mechanism has been elucidated for the observed morphological transition with variation of precursor concentration.

Breakdown of the independent electron picture in mesoscopic samples at low temperatures: The hunt for the Unicorn

Science.gov (United States)

Webb, R. A.

1998-03-01

A variety of experiments are discussed where, at low temperatures, it appears that the non-interacting picture of electrons in a Fermi liquid description of a mesoscopic sample is breaking down. Specifically, experiments on the temperature dependence of the phase-coherence time, energy relaxation rate, spin-flip scattering time, persistent currents in normal metals and transmission through a barrier in the fractional quantum Hall regime all display low-temperature properties which can not be accounted for in the independent electron picture.

Semiclassical approach to mesoscopic systems classical trajectory correlations and wave interference

CERN Document Server

Waltner, Daniel

2012-01-01

This volume describes mesoscopic systems with classically chaotic dynamics using semiclassical methods which combine elements of classical dynamics and quantum interference effects. Experiments and numerical studies show that Random Matrix Theory (RMT) explains physical properties of these systems well. This was conjectured more than 25 years ago by Bohigas, Giannoni and Schmit for the spectral properties. Since then, it has been a challenge to understand this connection analytically.  The author offers his readers a clearly-written and up-to-date treatment of the topics covered. He extends previous semiclassical approaches that treated spectral and conductance properties. He shows that RMT results can in general only be obtained semiclassically when taking into account classical configurations not considered previously, for example those containing multiply traversed periodic orbits. Furthermore, semiclassics is capable of describing effects beyond RMT. In this context he studies the effect of a non-zero Eh...

Measurement of mesoscopic high-T{sub c} superconductors using Si mechanical micro-oscillators

Energy Technology Data Exchange (ETDEWEB)

Dolz, M. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica and CONICET, R8402AGP S. C. de Bariloche (Argentina)]. E-mail: mdolz@cabbat1.cnea.gov.ar; Antonio, D. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica and CONICET, R8402AGP S. C. de Bariloche (Argentina); Pastoriza, H. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica and CONICET, R8402AGP S. C. de Bariloche (Argentina)

2007-09-01

In a superconducting mesoscopic sample, with dimensions comparable to the London penetration depth, some properties are qualitatively different to those found in the bulk material. These properties include magnetization, vortex dynamics and ordering of the vortex lattice. In order to detect the small signals produced by this kind of samples, new instruments designed for the microscale are needed. In this work we use micromechanical oscillators to study the magnetic properties of a Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} disk with a diameter of 13.5{mu}m and a thickness of 2.5{mu}m. The discussion of our results is based on the existence and contribution of inter and intra layer currents.

Time-evolution of photon heat current through series coupled two mesoscopic Josephson junction devices

Science.gov (United States)

Lu, Wen-Ting; Zhao, Hong-Kang; Wang, Jian

2018-03-01

Photon heat current tunneling through a series coupled two mesoscopic Josephson junction (MJJ) system biased by dc voltages has been investigated by employing the nonequilibrium Green’s function approach. The time-oscillating photon heat current is contributed by the superposition of different current branches associated with the frequencies of MJJs ω j (j = 1, 2). Nonlinear behaviors are exhibited to be induced by the self-inductance, Coulomb interaction, and interference effect relating to the coherent transport of Cooper pairs in the MJJs. Time-oscillating pumping photon heat current is generated in the absence of temperature difference, while it becomes zero after time-average. The combination of ω j and Coulomb interactions in the MJJs determines the concrete heat current configuration. As the external and intrinsic frequencies ω j and ω 0 of MJJs match some specific combinations, resonant photon heat current exhibits sinusoidal behaviors with large amplitudes. Symmetric and asymmetric evolutions versus time t with respect to ω 1 t and ω 2 t are controlled by the applied dc voltages of V 1 and V 2. The dc photon heat current formula is a special case of the general time-dependent heat current formula when the bias voltages are settled to zero. The Aharonov-Bohm effect has been investigated, and versatile oscillation structures of photon heat current can be achieved by tuning the magnetic fluxes threading through separating MJJs.

Quasiparticle transport properties of mesoscopic wires containing normal-metal/superconductor/normal-metal proximity junctions

International Nuclear Information System (INIS)

Kim, Nam; Kim, Kijoon; Lee, Hu Jong; Lee, Seongjae; Yuk, Jong Seol; Park, Kyoung Wan; Lee, El Hang

1997-01-01

We measured the differential resistance dV/dI of mesoscopic normal-metal/superconductor/normal-metal (N-S-N) junctions. At low temperatures (T PbIn /e, where Δ PbIn is the gap energy of superconducting Pb-In, and at a higher bias V c . The zero-bias dip is supposed to originate from Andreev reflections of quasiparticles and the peak near 2Δ PbIn /e from the formation of a standing-wave mode of quasiparticles inside the superconducting potential barrier. We attribute the peaks at V c to a transition of the superconducting region to the normal state as the current exceeds the critical current I c of S

Children's Acquisition of Conditional Logic Structure: Teachable?

Science.gov (United States)

Lee, Seong-Soo

1985-01-01

To assess the teachability of conditional logic structure, the commonly used syllogistic conditional reasoning task was divided into three main components: (1) inductive rule learning; (2) induction of conditional language; and (3) deductive interpretation. When trained on all components, fifth and seventh graders became very competent in dealing…

Mesoscopic Strains Maps in Woven Composite Laminas During Off-axis Tension

Directory of Open Access Journals (Sweden)

Nicoletto G.

2010-06-01

Full Text Available The mechanics of woven carbon-fiber reinforced plastic (CFRP composites is influenced by the complex architecture of the reinforcement phase. Computational (i.e. finite element based approaches have been used increasingly to model not only the global laminate stiffness, but also damage evolution and laminate strength. The modeling combines the identification of the architectural unit cell (UC, the selection of suitable constitutive models of the different phases, the creation of a fine discretization of the UC in finite elements, the application of an incremental solution procedure that solves iteratively for the stresses and strains in the UC, [1]. The experimental validation of computational models is carried out mainly at the macroscopical level, i.e. simulation of the macroscopic stress-strain curve. Damage, however, is a localized, straindependent phenomenon and therefore only accurate strain distribution within the UC (at the mesolevel can identify critical conditions in terms of damage location, extension and evolution. The validation of computational damage procedures is a key task and full-field optical strain analysis methods appear the ideal instrument. However, only limited examples of direct finte element method (FEM vs experimental strain correlation are found because of the limited sensitivity and spatial resolution of some techniques and the complexity and applicative difficulty of others. The aim of the present paper is to present the application of the digital image correlation (DIC technique, [2], to the full-field strain analysis at the mesoscopic level (i.e. within the UC of a woven CFRP lamina when the direction of loading forms an angle to the material direction. The material under consideration is a woven carbon fiber reinforced epoxy composite. Orthogonal yarns, each made of of several thousand fibers, are woven according the twill-weave architecture is shown in Fig. 1a. Single-ply laminas were manufactured and tested to

Revisiting the mesoscopic Termonia and Smith model for deformation of polymers

International Nuclear Information System (INIS)

Krishna Reddy, B; Basu, Sumit; Estevez, Rafael

2008-01-01

Mesoscopic models for polymers have the potential to link macromolecular properties with the mechanical behaviour without being too expensive computationally. An interesting, popular and rather simple model to this end was proposed by Termonia and Smith (1987 Macromolecules 20 835–8). In this model the macromolecular ensemble is viewed as a collection of two-dimensional self-avoiding random walks on a regular lattice whose lattice points represent entanglements. The load is borne by members representing van der Waals bonds as well as macromolecular strands between two entanglement points. Model polymers simulated via this model exhibited remarkable qualitative similarity with real polymers with respect to their molecular weight, entanglement spacing, strain rate and temperature dependence. In this work, we revisit this model and present a detailed reformulation within the framework of a finite deformation finite element scheme. The physical origins of each of the parameters in the model are investigated and inherent assumptions in the model which contribute to its success are critically probed

Mesoscopic quantum effects in a bad metal, hydrogen-doped vanadium dioxide

Science.gov (United States)

Hardy, Will J.; Ji, Heng; Paik, Hanjong; Schlom, Darrell G.; Natelson, Douglas

2017-05-01

The standard treatment of quantum corrections to semiclassical electronic conduction assumes that charge carriers propagate many wavelengths between scattering events, and succeeds in explaining multiple phenomena (weak localization magnetoresistance (WLMR), universal conductance fluctuations, Aharonov-Bohm oscillations) observed in polycrystalline metals and doped semiconductors in various dimensionalities. We report apparent WLMR and conductance fluctuations in H x VO2, a poor metal (in violation of the Mott-Ioffe-Regel limit) stabilized by the suppression of the VO2 metal-insulator transition through atomic hydrogen doping. Epitaxial thin films, single-crystal nanobeams, and nanosheets show similar phenomenology, though the details of the apparent WLMR seem to depend on the combined effects of the strain environment and presumed doping level. Self-consistent quantitative analysis of the WLMR is challenging given this and the high resistivity of the material, since the quantitative expressions for WLMR are derived assuming good metallicity. These observations raise the issue of how to assess and analyze mesoscopic quantum effects in poor metals.

From Dynamic Condition Response Structures to Büchi Automata

DEFF Research Database (Denmark)

Mukkamala, Raghava Rao; Hildebrandt, Thomas

2010-01-01

Recently we have presented distributed dynamic condition response structures (DCR structures) as a declarative process model conservatively generalizing labelled event structures to allow for finite specifications of repeated, possibly infinite behavior. The key ideas are to split the causality...... relation of event structures in two dual relations: the condition relation and the response relation, to split the conflict relation in two relations: the dynamic exclusion and dynamic inclusion, and finally to allow configurations to be multi sets of events. In the present abstract we recall the model...... and show how to characterise the execution of DCR structures and the acceptance condition for infinite runs by giving a map to Bu ̈chi-automata. This is the first step towards automatic verification of processes specified as DCR structures....

Equilibrium finite-frequency noise of an interacting mesoscopic capacitor studied in time-dependent density functional theory

Science.gov (United States)

Dittmann, Niklas; Splettstoesser, Janine; Helbig, Nicole

2018-03-01

We calculate the frequency-dependent equilibrium noise of a mesoscopic capacitor in time-dependent density functional theory (TDDFT). The capacitor is modeled as a single-level quantum dot with on-site Coulomb interaction and tunnel coupling to a nearby reservoir. The noise spectra are derived from linear-response conductances via the fluctuation-dissipation theorem. Thereby, we analyze the performance of a recently derived exchange-correlation potential with time-nonlocal density dependence in the finite-frequency linear-response regime. We compare our TDDFT noise spectra with real-time perturbation theory and find excellent agreement for noise frequencies below the reservoir temperature.

Strength conditions for the elastic structures with a stress error

Science.gov (United States)

Matveev, A. D.

2017-10-01

As is known, the constraints (strength conditions) for the safety factor of elastic structures and design details of a particular class, e.g. aviation structures are established, i.e. the safety factor values of such structures should be within the given range. It should be noted that the constraints are set for the safety factors corresponding to analytical (exact) solutions of elasticity problems represented for the structures. Developing the analytical solutions for most structures, especially irregular shape ones, is associated with great difficulties. Approximate approaches to solve the elasticity problems, e.g. the technical theories of deformation of homogeneous and composite plates, beams and shells, are widely used for a great number of structures. Technical theories based on the hypotheses give rise to approximate (technical) solutions with an irreducible error, with the exact value being difficult to be determined. In static calculations of the structural strength with a specified small range for the safety factors application of technical (by the Theory of Strength of Materials) solutions is difficult. However, there are some numerical methods for developing the approximate solutions of elasticity problems with arbitrarily small errors. In present paper, the adjusted reference (specified) strength conditions for the structural safety factor corresponding to approximate solution of the elasticity problem have been proposed. The stress error estimation is taken into account using the proposed strength conditions. It has been shown that, to fulfill the specified strength conditions for the safety factor of the given structure corresponding to an exact solution, the adjusted strength conditions for the structural safety factor corresponding to an approximate solution are required. The stress error estimation which is the basis for developing the adjusted strength conditions has been determined for the specified strength conditions. The adjusted strength

Polymorphism of Lysozyme Condensates.

Science.gov (United States)

Safari, Mohammad S; Byington, Michael C; Conrad, Jacinta C; Vekilov, Peter G

2017-10-05

Protein condensates play essential roles in physiological processes and pathological conditions. Recently discovered mesoscopic protein-rich clusters may act as crucial precursors for the nucleation of ordered protein solids, such as crystals, sickle hemoglobin polymers, and amyloid fibrils. These clusters challenge settled paradigms of protein condensation as the constituent protein molecules present features characteristic of both partially misfolded and native proteins. Here we employ the antimicrobial enzyme lysozyme and examine the similarities between mesoscopic clusters, amyloid structures, and disordered aggregates consisting of chemically modified protein. We show that the mesoscopic clusters are distinct from the other two classes of aggregates. Whereas cluster formation and amyloid oligomerization are both reversible, aggregation triggered by reduction of the intramolecular S-S bonds is permanent. In contrast to the amyloid structures, protein molecules in the clusters retain their enzymatic activity. Furthermore, an essential feature of the mesoscopic clusters is their constant radius of less than 50 nm. The amyloid and disordered aggregates are significantly larger and rapidly grow. These findings demonstrate that the clusters are a product of limited protein structural flexibility. In view of the role of the clusters in the nucleation of ordered protein solids, our results suggest that fine-tuning the degree of protein conformational stability is a powerful tool to control and direct the pathways of protein condensation.

Mesoscopic dynamics of diffusion-influenced enzyme kinetics.

Science.gov (United States)

Chen, Jiang-Xing; Kapral, Raymond

2011-01-28

A particle-based mesoscopic model for enzyme kinetics is constructed and used to investigate the influence of diffusion on the reactive dynamics. Enzymes and enzyme-substrate complexes are modeled as finite-size soft spherical particles, while substrate, product, and solvent molecules are point particles. The system is evolved using a hybrid molecular dynamics-multiparticle collision dynamics scheme. Both the nonreactive and reactive dynamics are constructed to satisfy mass, momentum, and energy conservation laws, and reversible reaction steps satisfy detailed balance. Hydrodynamic interactions among the enzymes and complexes are automatically accounted for in the dynamics. Diffusion manifests itself in various ways, notably in power-law behavior in the evolution of the species concentrations. In accord with earlier investigations, regimes where the product production rate exhibits either monotonic or nonmonotonic behavior as a function of time are found. In addition, the species concentrations display both t(-1/2) and t(-3/2) power-law behavior, depending on the dynamical regime under investigation. For high enzyme volume fractions, cooperative effects influence the enzyme kinetics. The time dependent rate coefficient determined from the mass action rate law is computed and shown to depend on the enzyme concentration. Lifetime distributions of substrate molecules newly released in complex dissociation events are determined and shown to have either a power-law form for rebinding to the same enzyme from which they were released or an exponential form for rebinding to different enzymes. The model can be used and extended to explore a variety of issues related concentration effects and diffusion on enzyme kinetics.

Mesoscopic dynamics of diffusion-influenced enzyme kinetics

Science.gov (United States)

Chen, Jiang-Xing; Kapral, Raymond

2011-01-01

A particle-based mesoscopic model for enzyme kinetics is constructed and used to investigate the influence of diffusion on the reactive dynamics. Enzymes and enzyme-substrate complexes are modeled as finite-size soft spherical particles, while substrate, product, and solvent molecules are point particles. The system is evolved using a hybrid molecular dynamics-multiparticle collision dynamics scheme. Both the nonreactive and reactive dynamics are constructed to satisfy mass, momentum, and energy conservation laws, and reversible reaction steps satisfy detailed balance. Hydrodynamic interactions among the enzymes and complexes are automatically accounted for in the dynamics. Diffusion manifests itself in various ways, notably in power-law behavior in the evolution of the species concentrations. In accord with earlier investigations, regimes where the product production rate exhibits either monotonic or nonmonotonic behavior as a function of time are found. In addition, the species concentrations display both t^{-1/2} and t^{-3/2} power-law behavior, depending on the dynamical regime under investigation. For high enzyme volume fractions, cooperative effects influence the enzyme kinetics. The time dependent rate coefficient determined from the mass action rate law is computed and shown to depend on the enzyme concentration. Lifetime distributions of substrate molecules newly released in complex dissociation events are determined and shown to have either a power-law form for rebinding to the same enzyme from which they were released or an exponential form for rebinding to different enzymes. The model can be used and extended to explore a variety of issues related concentration effects and diffusion on enzyme kinetics.

Mapping cortical mesoscopic networks of single spiking cortical or sub-cortical neurons.

Science.gov (United States)

Xiao, Dongsheng; Vanni, Matthieu P; Mitelut, Catalin C; Chan, Allen W; LeDue, Jeffrey M; Xie, Yicheng; Chen, Andrew Cn; Swindale, Nicholas V; Murphy, Timothy H

2017-02-04

Understanding the basis of brain function requires knowledge of cortical operations over wide-spatial scales, but also within the context of single neurons. In vivo, wide-field GCaMP imaging and sub-cortical/cortical cellular electrophysiology were used in mice to investigate relationships between spontaneous single neuron spiking and mesoscopic cortical activity. We make use of a rich set of cortical activity motifs that are present in spontaneous activity in anesthetized and awake animals. A mesoscale spike-triggered averaging procedure allowed the identification of motifs that are preferentially linked to individual spiking neurons by employing genetically targeted indicators of neuronal activity. Thalamic neurons predicted and reported specific cycles of wide-scale cortical inhibition/excitation. In contrast, spike-triggered maps derived from single cortical neurons yielded spatio-temporal maps expected for regional cortical consensus function. This approach can define network relationships between any point source of neuronal spiking and mesoscale cortical maps.

From glass structure to its chemical durability; De la structure du verre a sa durabilite chimique

Energy Technology Data Exchange (ETDEWEB)

Angeli, F.

2009-07-01

The author gives an overview of his research activities. He more precisely reports studies related to glass structure based on nuclei observed by NMR and present in glasses of interest for nuclear activities. He discusses the influence of chemical composition on structure, and discusses information which can be extracted from network formers (Al, B) and modifiers (Na, Ca), and from oxygen present in the network linkages of oxide glasses. He discusses the different experimental and modelling approaches which enable structural and morphological information to be obtained at a mesoscopic scale. The last part deals with the investigation of the long term behaviour of confinement matrices (glassy matrix for medium-activity wastes, ceramic matrix)

On Hydroelastic Body-Boundary Condition of Floating Structures

DEFF Research Database (Denmark)

Xia, Jinzhu

1996-01-01

A general linear body boundary condition of hydroelastic analysis of arbitrary shaped floating structures generalizes the classic kinematic rigid-body (Timman-Newman) boundary condition for seakeeping problems. The new boundary condition is consistent with the existing theories under certain...

The mesoscopic conductance of disordered rings, its random matrix theory and the generalized variable range hopping picture

International Nuclear Information System (INIS)

Stotland, Alexander; Peer, Tal; Cohen, Doron; Budoyo, Rangga; Kottos, Tsampikos

2008-01-01

The calculation of the conductance of disordered rings requires a theory that goes beyond the Kubo-Drude formulation. Assuming 'mesoscopic' circumstances the analysis of the electro-driven transitions shows similarities with a percolation problem in energy space. We argue that the texture and the sparsity of the perturbation matrix dictate the value of the conductance, and study its dependence on the disorder strength, ranging from the ballistic to the Anderson localization regime. An improved sparse random matrix model is introduced to capture the essential ingredients of the problem, and leads to a generalized variable range hopping picture. (fast track communication)

Cavity-assisted mesoscopic transport of fermions: Coherent and dissipative dynamics

Science.gov (United States)

Hagenmüller, David; Schütz, Stefan; Schachenmayer, Johannes; Genes, Claudiu; Pupillo, Guido

2018-05-01

We study the interplay between charge transport and light-matter interactions in a confined geometry by considering an open, mesoscopic chain of two-orbital systems resonantly coupled to a single bosonic mode close to its vacuum state. We introduce and benchmark different methods based on self-consistent solutions of nonequilibrium Green's functions and numerical simulations of the quantum master equation, and derive both analytical and numerical results. It is shown that in the dissipative regime where the cavity photon decay rate is the largest parameter, the light-matter coupling is responsible for a steady-state current enhancement scaling with the cooperativity parameter. We further identify different regimes of interest depending on the ratio between the cavity decay rate and the electronic bandwidth. Considering the situation where the lower band has a vanishing bandwidth, we show that for a high-finesse cavity, the properties of the resonant Bloch state in the upper band are transferred to the lower one, giving rise to a delocalized state along the chain. Conversely, in the dissipative regime with low-cavity quality factors, we find that the current enhancement is due to a collective decay of populations from the upper to the lower band.

Mesoscopic chaos mediated by Drude electron-hole plasma in silicon optomechanical oscillators

Science.gov (United States)

Wu, Jiagui; Huang, Shu-Wei; Huang, Yongjun; Zhou, Hao; Yang, Jinghui; Liu, Jia-Ming; Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee; Duan, Shukai; Wei Wong, Chee

2017-01-01

Chaos has revolutionized the field of nonlinear science and stimulated foundational studies from neural networks, extreme event statistics, to physics of electron transport. Recent studies in cavity optomechanics provide a new platform to uncover quintessential architectures of chaos generation and the underlying physics. Here, we report the generation of dynamical chaos in silicon-based monolithic optomechanical oscillators, enabled by the strong and coupled nonlinearities of two-photon absorption induced Drude electron–hole plasma. Deterministic chaotic oscillation is achieved, and statistical and entropic characterization quantifies the chaos complexity at 60 fJ intracavity energies. The correlation dimension D2 is determined at 1.67 for the chaotic attractor, along with a maximal Lyapunov exponent rate of about 2.94 times the fundamental optomechanical oscillation for fast adjacent trajectory divergence. Nonlinear dynamical maps demonstrate the subharmonics, bifurcations and stable regimes, along with distinct transitional routes into chaos. This provides a CMOS-compatible and scalable architecture for understanding complex dynamics on the mesoscopic scale. PMID:28598426

Mesoscopic structure prediction of nanoparticle assembly and coassembly: Theoretical foundation

KAUST Repository

Hur, Kahyun; Hennig, Richard G.; Escobedo, Fernando A.; Wiesner, Ulrich

2010-01-01

structures and interactions. We validate our approach by comparing its predictions with previous simulation results for model systems. We illustrate the flexibility of our approach by applying it to hybrid systems composed of block copolymers and ligand

Optimizing mesoscopic two-band superconductors for observation of fractional vortex states

Energy Technology Data Exchange (ETDEWEB)

Piña, Juan C. [Departamento de Física, Universidade Federal de Pernambuco, Cidade Universitária, 50670-901 Recife, PE (Brazil); Núcleo de Tecnologia, CAA, Universidade Federal de Pernambuco, 55002-970 Caruaru, PE (Brazil); Souza Silva, Clécio C. de, E-mail: clecio@df.ufpe [Departamento de Física, Universidade Federal de Pernambuco, Cidade Universitária, 50670-901 Recife, PE (Brazil); Milošević, Milorad V. [Departamento de Física, Universidade Federal do Ceará, 60455-900 Fortaleza, Ceará (Brazil); Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

2014-08-15

Highlights: • Observation of fractional vortices in two-band superconductors of broad size range. • There is a minimal sample size for observing each particular fractional state. • Optimal value for stability of each fractional state is determined. • A suitable magnetic dot enhances stability even further. - Abstract: Using the two-component Ginzburg–Landau model, we investigate the effect of sample size and magnitude and homogeneity of external magnetic field on the stability of fractional vortex states in a mesoscopic two-band superconducting disk. We found that each fractional state has a preferable sample size, for which the range of applied field in which the state is stable is pronouncedly large. Vice versa, there exists an optimal magnitude of applied field for which a large range of possible sample radii will support the considered fractional state. Finally, we show that the stability of fractional states can be enhanced even further by magnetic nanostructuring of the sample, i.e. by suitably chosen geometrical parameters and magnetic moment of a ferromagnetic dot placed on top of the superconducting disk.

Mesoscopic modeling of DNA denaturation rates: Sequence dependence and experimental comparison

Energy Technology Data Exchange (ETDEWEB)

Dahlen, Oda, E-mail: oda.dahlen@ntnu.no; Erp, Titus S. van, E-mail: titus.van.erp@ntnu.no [Department of Chemistry, Norwegian University of Science and Technology (NTNU), Høgskoleringen 5, Realfagbygget D3-117 7491 Trondheim (Norway)

2015-06-21

Using rare event simulation techniques, we calculated DNA denaturation rate constants for a range of sequences and temperatures for the Peyrard-Bishop-Dauxois (PBD) model with two different parameter sets. We studied a larger variety of sequences compared to previous studies that only consider DNA homopolymers and DNA sequences containing an equal amount of weak AT- and strong GC-base pairs. Our results show that, contrary to previous findings, an even distribution of the strong GC-base pairs does not always result in the fastest possible denaturation. In addition, we applied an adaptation of the PBD model to study hairpin denaturation for which experimental data are available. This is the first quantitative study in which dynamical results from the mesoscopic PBD model have been compared with experiments. Our results show that present parameterized models, although giving good results regarding thermodynamic properties, overestimate denaturation rates by orders of magnitude. We believe that our dynamical approach is, therefore, an important tool for verifying DNA models and for developing next generation models that have higher predictive power than present ones.

Achievement report for fiscal 1998 on the technological development of super metals. Technology to create iron-based mesoscopic tissue controlling materials; 1998 nendo super metal no gijutsu kaihatsu seika hokokusho. Tetsukei meso scopic soshiki seigyo zairyo sosei gijutsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

Research and development has been carried out on super metals with an objective to draw out properties possessed by iron and steel materials to their maximum extent and further enhance their recycling performance to make them friendly with global environment. The final goal of this project is to 'establish a technology to create micro tissue steel having crystalline particle diameter of about 1 {mu}mm or less and size having thickness of 1 mm or more by making the steel tissues uniform and multiple in phase'. The studies in the current fiscal year were moved forward mainly on obtaining ultra fine crystalline particles of 1 {mu}mm or less, identifying the ideal large distortion processing conditions, and structuring the guidance principles for ultra-fine micronization of the crystalline particles by using large distortion processing. Discussions were also launched on further micronization of crystalline particles by optimizing chemical composition and on expansion of the process windows assuming practical application thereof in industrial scale. Furthermore, material property evaluation was also begun on ultra-fine crystalline particle materials of smaller than 1{mu}mm. As the mesoscopic structure analyzing technology for the ultra-fine crystalline particle materials, an in-lens resolution SEM was introduced, and the basic method was established. (NEDO)

Gradual failure of structures in creep conditions

International Nuclear Information System (INIS)

Chrzanowski, M.; Latus, P.

1993-01-01

The most characteristic feature of progressive material deterioration in creep conditions Is its time-dependence. In structures this process comprises of three stages: 1. Incubation of a macroscopic defect at the time of First Crack Appearance (FCA); 2. Propagation of a macro-crack throughout the structural member at the Time of Member Failure (TMF); 3. Propagation of failure of consecutive structure members, leading to the Final Structure Collapse (FSC). The importance of a full analysis of a structure which comprises all above stages has been demonstrated previously. Corresponding times are denoted as t 1 , t 2 , t 3 respectively. Depending on many factors, like material properties, loading and supports, the ratio of t 1 /t 2 and t 2 /t 3 may vary significantly, and thus exhibiting a safety margin connected with damage propagation throughout the structure. However, the full analysis becomes very sophisticated since creep and damage evolutions law are often nonlinear ones, and analysis should include changing geometry of a structure. It was was found that the failure propagation in analysed structures appeared to be very sensitive to structures geometry and loading. The time ratio t 1 /t 3 depends on redundancy k (higher the redundancy lower the ratio), but structures collapse by local mechanisms. These mechanisms can be different depending on k. More decisive than redundancy is an overall configuration of loads and structure geometry because of different mechanism of final failure. So far, no general conclusion can be drawn, but the whole analysis resembles that of limit analysis for structures made of ideally plastic or elastic-plastic materials. Nevertheless it Is evident that full analysis of structures in creep conditions can significantly enhance the structures life-time expectation

Probabilistic Fatigue Life Prediction of Bridge Cables Based on Multiscaling and Mesoscopic Fracture Mechanics

Directory of Open Access Journals (Sweden)

Zhongxiang Liu

2016-04-01

Full Text Available Fatigue fracture of bridge stay-cables is usually a multiscale process as the crack grows from micro-scale to macro-scale. Such a process, however, is highly uncertain. In order to make a rational prediction of the residual life of bridge cables, a probabilistic fatigue approach is proposed, based on a comprehensive vehicle load model, finite element analysis and multiscaling and mesoscopic fracture mechanics. Uncertainties in both material properties and external loads are considered. The proposed method is demonstrated through the fatigue life prediction of cables of the Runyang Cable-Stayed Bridge in China, and it is found that cables along the bridge spans may have significantly different fatigue lives, and due to the variability, some of them may have shorter lives than those as expected from the design.

Structural condition assessment of in-service wood

Science.gov (United States)

Robert J. Ross; Brian K. Brashaw; Xiping Wang

2006-01-01

Wood is used extensively for both interior and exterior applications in the construction of a variety of structures (residential, agricultural, commercial, government, religious). The deterioration of an in-service wood member may result from a variety of causes during the life of a structure. It is important, therefore, to periodically assess the condition of wood...

From glass structure to its chemical durability

International Nuclear Information System (INIS)

Angeli, F.

2009-01-01

The author gives an overview of his research activities. He more precisely reports studies related to glass structure based on nuclei observed by NMR and present in glasses of interest for nuclear activities. He discusses the influence of chemical composition on structure, and discusses information which can be extracted from network formers (Al, B) and modifiers (Na, Ca), and from oxygen present in the network linkages of oxide glasses. He discusses the different experimental and modelling approaches which enable structural and morphological information to be obtained at a mesoscopic scale. The last part deals with the investigation of the long term behaviour of confinement matrices (glassy matrix for medium-activity wastes, ceramic matrix)

Quantum mechanics and the second law of thermodynamics: an insight gleaned from magnetic hysteresis in the first order phase transition of an isolated mesoscopic-size type I superconductor

International Nuclear Information System (INIS)

Keefe, Peter D

2012-01-01

J Bardeen proposed that the adiabatic phase transition of mesoscopic-size type I superconductors must be accompanied by magnetic hysteresis in the critical magnetic field of sufficient magnitude to satisfy the second law of thermodynamics, herein referred to as ‘Bardeen Hysteresis’. Bardeen Hysteresis remains speculative in that it has not been reported in the literature. This paper investigates Bardeen Hysteresis as a possible accompaniment to the adiabatic phase transition of isolated mesoscopic-size type I superconductors and its implications with respect to the second law of thermodynamics. A causal mechanism for Bardeen Hysteresis is discussed which contrasts with the long accepted causal mechanism of magnetic hysteresis, as first summarized by Pippard, herein referred to as ‘Pippard Hysteresis’. The paper offers guidance for an experimental verification and comments on how the existence of Bardeen Hysteresis has relation to a quantum mechanical basis for the second law of thermodynamics.

Quantum mechanics and the second law of thermodynamics: an insight gleaned from magnetic hysteresis in the first order phase transition of an isolated mesoscopic-size type I superconductor

Science.gov (United States)

Keefe, Peter D.

2012-11-01

J Bardeen proposed that the adiabatic phase transition of mesoscopic-size type I superconductors must be accompanied by magnetic hysteresis in the critical magnetic field of sufficient magnitude to satisfy the second law of thermodynamics, herein referred to as ‘Bardeen Hysteresis’. Bardeen Hysteresis remains speculative in that it has not been reported in the literature. This paper investigates Bardeen Hysteresis as a possible accompaniment to the adiabatic phase transition of isolated mesoscopic-size type I superconductors and its implications with respect to the second law of thermodynamics. A causal mechanism for Bardeen Hysteresis is discussed which contrasts with the long accepted causal mechanism of magnetic hysteresis, as first summarized by Pippard, herein referred to as ‘Pippard Hysteresis’. The paper offers guidance for an experimental verification and comments on how the existence of Bardeen Hysteresis has relation to a quantum mechanical basis for the second law of thermodynamics.

Assessment of inservice conditions of safety-related nuclear plant structures

International Nuclear Information System (INIS)

Ashar, H.; Bagchi, G.

1995-06-01

The report is a compilation from a number of sources of information related to the condition Of structures and civil engineering features at operating nuclear power plants in the United States. The most significant information came from the hands-on inspection of the six old plants (licensed prior to 1977) performed by the staff of the Civil Engineering and Geosciences Branch (ECGB) in the Division of Engineering of the Office of Nuclear Reactor Regulation. For the containment structures, most of the information related to the degraded conditions came from the licensees as part of the Licensing Event Report System (10 CFR 50.73), or as part of the requirement under limiting condition of operation of the plant-specific Technical Specifications. Most of the information related to the degradation of other Structures and civil engineering features was extracted from the industry survey, the reported incidents, and the plant visits. The report discusses the condition of the structures and civil engineering features at operating nuclear power plants and provides information that would help detect, alleviate, and correct the degraded conditions of the structures and civil engineering features

Evaluation of calcium hydrogen carbonate mesoscopic crystals as a disinfectant for influenza A viruses

Science.gov (United States)

NAKASHIMA, Ryuji; KAWAMOTO, Masaomi; MIYAZAKI, Shigeru; ONISHI, Rumiko; FURUSAKI, Koichi; OSAKI, Maho; KIRISAWA, Rikio; SAKUDO, Akikazu; ONODERA, Takashi

2017-01-01

In this study, the virucidal effect of a novel electrically charged disinfectant CAC-717 was investigated. CAC-717 is produced by applying an electric field to mineral water containing calcium hydrogen carbonate to generate mesoscopic crystals. Virus titration analysis showed a >3 log reduction of influenza A viruses after treatment with CAC-717 for 1 min in room temperature, while infectivity was undetectable after 15 min treatment. Adding bovine serum albumin to CAC-717 solution did not affect the disinfectant effect. Although CAC-717 is an alkaline solution (pH=12.39), upon contact with human tissue, its pH becomes almost physiological (pH 8.84) after accelerated electric discharge, which enables its use against influenza viruses. Therefore, CAC-717 may be used as a preventative measure against influenza A viruses and for biosecurity in the environment. PMID:28392537

Significance of Operating Environment in Condition Monitoring of Large Civil Structures

Directory of Open Access Journals (Sweden)

Sreenivas Alampalli

1999-01-01

Full Text Available Success of remote long-term condition monitoring of large civil structures and developing calibrated analytical models for damage detection, depend significantly on establishing accurate baseline signatures and their sensitivity. Most studies reported in the literature concentrated on the effect of structural damage on modal parameters without emphasis on reliability of modal parameters. Thus, a field bridge structure was studied for the significance of operating conditions in relation to baseline signatures. Results indicate that in practice, civil structures should be monitored for at least one full cycle of in-service environmental changes before establishing baselines for condition monitoring or calibrating finite-element models. Boundary conditions deserve special attention.

Density Functional Theory for Phase-Ordering Transitions

Energy Technology Data Exchange (ETDEWEB)

Wu, Jianzhong [Univ. of California, Riverside, CA (United States)

2016-03-30

Colloids display astonishing structural and dynamic properties that can be dramatically altered by modest changes in the solution condition or an external field. This complex behavior stems from a subtle balance of colloidal forces and intriguing mesoscopic and macroscopic phase transitions that are sensitive to the processing conditions and the dispersing environment. Whereas the knowledge on the microscopic structure and phase behavior of colloidal systems at equilibrium is now well-advanced, quantitative predictions of the dynamic properties and the kinetics of phase-ordering transitions in colloids are not always realized. Many important mesoscopic and off-equilibrium colloidal states remain poorly understood. The proposed research aims to develop a new, unifying approach to describe colloidal dynamics and the kinetics of phase-ordering transitions based on accomplishments from previous work for the equilibrium properties of both uniform and inhomogeneous systems and on novel concepts from the state-of-the-art dynamic density functional theory. In addition to theoretical developments, computational research is designed to address a number of fundamental questions on phase-ordering transitions in colloids, in particular those pertinent to a competition of the dynamic pathways leading to various mesoscopic structures, off-equilibrium states, and crystalline phases. By providing a generic theoretical framework to describe equilibrium, metastable as well as non-ergodic phase transitions concurrent with the colloidal self-assembly processes, accomplishments from this work will have major impacts on both fundamental research and technological applications.

Conductance of functionalized nanotubes, graphene and nanowires: from ab initio to mesoscopic physics

Energy Technology Data Exchange (ETDEWEB)

Blase, X. [Institut Neel, CNRS/UJF, 25 rue des Martyrs, 38042 Grenoble (France); LPMCN, CNRS/Universite Lyon I, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Adessi, C. [LPMCN, CNRS/Universite Lyon I, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Biel, B. [Dpto. Electronica y Tecnologia de Computadores, Universidad de Granada Facultad de Ciencias, Campus de Fuente Nueva, 18071 Granada (Spain); Lopez-Bezanilla, A.; Roche, S. [CEA, Institut of Nanosciences and Cryogenics, INAC/SPSMS/GT, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Fernandez-Serra, M.V. [LPMCN, CNRS/Universite Lyon I, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Physics and Astronomy department, Stony Brooks University, NY 11794 (United States); Margine, E.R. [LPMCN, CNRS/Universite Lyon I, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Department of Materials, Oxford University, Oxford OX1 3PH (United Kingdom); Triozon, F. [CEA, LETI-Minatec, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

2010-12-15

We review recent theoretical results aiming at understanding the impact of doping and functionalization on the electronic transport properties of nanotubes, nanowires and graphene ribbons. On the basis of ab initio calculations, the conductance of micrometer long tubes or ribbons randomly doped or grafted can be studied, allowing to extract quantities at mesoscopic length scales such as the elastic mean free path and localization length. While the random modification of a 1D conducting channel leads generally to a significant loss of conductance, strategies can be found to either exploit or limitate such a detrimental effect. Spin-filtering in transition metal doped nanotubes, the opening of a mobility gap in graphene ribbons, and the choice of molecules to limitate backscattering in covalently functionalized tubes are examples that will be discussed. Symbolic representation of a nanotube filled with Cobalt atoms or clusters with subsequent optimal spinvalve effect (see text). (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effects of internal noise in mesoscopic chemical systems near Hopf bifurcation

International Nuclear Information System (INIS)

Xiao Tiejun; Ma Juan; Hou Zhonghuai; Xin Houwen

2007-01-01

The effects of internal noise in mesoscopic chemical oscillation systems have been studied analytically, in the parameter region close to the deterministic Hopf bifurcation. Starting from chemical Langevin equations, stochastic normal form equations are obtained, governing the evolution of the radius and phase of the stochastic oscillation. By stochastic averaging, the normal form equation can be solved analytically. Stationary distributions of the radius and auto-correlation functions of the phase variable are obtained. It is shown that internal noise can induce oscillation; even no deterministic oscillation exists. The radius of the noise-induced oscillation (NIO) becomes larger when the internal noise increases, but the correlation time becomes shorter. The trade-off between the strength and regularity of the NIO leads to a clear maximum in its signal-to-noise ratio when the internal noise changes, demonstrating the occurrence of internal noise coherent resonance. Since the intensity of the internal noise is inversely proportional to the system size, the phenomenon also indicates the existence of an optimal system size. These theoretical results are applied to a circadian clock system and excellent agreement with the numerical results is obtained

New nanocomposite surfaces and thermal interface materials based on mesoscopic microspheres, polymers and graphene flakes

Science.gov (United States)

Dmitriev, Alex A.; Dmitriev, Alex S.; Makarov, Petr; Mikhailova, Inna

2018-04-01

In recent years, there has been a great interest in the development and creation of new functional energy mate-rials, including for improving the energy efficiency of power equipment and for effectively removing heat from energy devices, microelectronics and optoelectronics (power micro electronics, supercapacitors, cooling of processors, servers and data centers). In this paper, the technology of obtaining new nanocomposites based on mesoscopic microspheres, polymers and graphene flakes is considered. The methods of sequential production of functional materials from graphene flakes of different volumetric concentration using epoxy polymers, as well as the addition of monodisperse microspheres are described. Data are given on the measurement of the contact angle and thermal conductivity of these nanocomposites with respect to the creation of thermal interface materials for cooling devices of electronics, optoelectronics and power engineering.

STRUCTURAL ANALYSIS OF CONDITIONAL PREPARATION IN JUDO

Directory of Open Access Journals (Sweden)

Slavko Obadov

2006-06-01

Full Text Available Conditional preparation is a constituent part of overall sports preparation. Conditional training might be defined as a process of improvement of a sportsman’s functional and motor abilities, morphological characteristics, health, as well as the required motor knowledge. Conditional preparation can be might be classified as: general, basic and situational conditional preparation. Programs of the conditional training might be classified as: developing, resuming, recovering, preventive and recovering ones. High level of the general physical preparation enables maximum demonstration of the physical abilities of a sportsman during the stage of improvement of the specific motor abilities. Good general preparation of a sportsman enables him to push beyond his functional limits in order to cope with heavy loads easier, which subsequently enables him to achieve top performance level. Basic conditional preparation assumes the development of the most important judo abilities. Specific conditional preparation is related directly to the execution of different structural elements under the conditional requirements. Situational conditional preparation enables integration of the tactical and conditional training.

Effect of borax concentration on the structure of Poly(Vinyl Alcohol) gels

Science.gov (United States)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2012-06-01

Poly(Vinyl Alcohol) hydrogels cross-linked with varying concentrations of borax have been studied using Small-Angle Neutron Scattering and X-Ray Diffraction. The intensity of scattering increases with borax concentration from 1 mg/ml up to 2 mg/ml and falls thereafter for 4 mg/ml, increasing again for a concentration of 10 mg/ml. The mesoscopic structural changes that cause these trends in the SANS data are in keeping with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.

Electrodynamic soil plate oscillator: Modeling nonlinear mesoscopic elastic behavior and hysteresis in nonlinear acoustic landmine detection

Science.gov (United States)

Korman, M. S.; Duong, D. V.; Kalsbeck, A. E.

2015-10-01

significant curvature when the soil particle velocity is relatively higher. An oscillator with hysteresis modeled by a distribution of parallel spring elements each with a different threshold slip condition seems to describe fairly linear backbone curve behavior [W. D. Iwan, Transactions of the ASME, J. of Applied Mech., 33,(1966), 893-900], while a single bilinear hysteresis element describes the backbone curvature results in the experiments reported here [T. K. Caughey, Transactions of the ASME, J. of Applied Mech., 27, (1960), 640-643]. When "off target" resonances have a different backbone curvature than "on the mine" backbone curves, then false alarms may be eliminated due to resonances from the natural soil layering. See [R. A. Guyer, J. TenCate, and P. Johnson, "Hysteresis and the Dynamic Elasticity of Consolidated Granular Materials," Phys. Rev. Lett., 82, 16 (1999), 3280-3283] for recent models of nonlinear mesoscopic behavior.

Critical phenomena in magnetic vortex formation probed by noise spectroscopy

International Nuclear Information System (INIS)

Saitoh, E.; Harii, K.; Miyajima, H.; Yamaoka, T.

2004-01-01

Transition between a vortex magnetic state and a uniform magnetic state in a Ni 81 Fe 19 mesoscopic ring has been investigated in terms of resistive-noise spectroscopy. The observed low-frequency noise exhibits critical enhancement around the magnetization saturation. This noise enhancement can be argued from the viewpoint of the critical phenomena due to the chiral-symmetry breakdown of mesoscopic magnetic-structure, which can present a typical mechanism of symmetry transition of magnetic structure in mesoscopic ferromagnets

Variable speed limit strategies analysis with mesoscopic traffic flow model based on complex networks

Science.gov (United States)

Li, Shu-Bin; Cao, Dan-Ni; Dang, Wen-Xiu; Zhang, Lin

As a new cross-discipline, the complexity science has penetrated into every field of economy and society. With the arrival of big data, the research of the complexity science has reached its summit again. In recent years, it offers a new perspective for traffic control by using complex networks theory. The interaction course of various kinds of information in traffic system forms a huge complex system. A new mesoscopic traffic flow model is improved with variable speed limit (VSL), and the simulation process is designed, which is based on the complex networks theory combined with the proposed model. This paper studies effect of VSL on the dynamic traffic flow, and then analyzes the optimal control strategy of VSL in different network topologies. The conclusion of this research is meaningful to put forward some reasonable transportation plan and develop effective traffic management and control measures to help the department of traffic management.

Mesoscopic dispersion of colloidal agglomerate in a complex fluid modelled by a hybrid fluid-particle model.

Science.gov (United States)

Dzwinel, Witold; Yuen, David A

2002-03-15

The dispersion of the agglomerating fluid process involving colloids has been investigated at the mesoscale level by a discrete particle approach--the hybrid fluid-particle model (FPM). Dynamical processes occurring in the granulation of colloidal agglomerate in solvents are severely influenced by coupling between the dispersed microstructures and the global flow. On the mesoscale this coupling is further exacerbated by thermal fluctuations, particle-particle interactions between colloidal beds, and hydrodynamic interactions between colloidal beds and the solvent. Using the method of FPM, we have tackled the problem of dispersion of a colloidal slab being accelerated in a long box filled with a fluid. Our results show that the average size of the agglomerated fragments decreases with increasing shearing rate gamma, according to the power law A x gamma(k), where k is around 2. For larger values of gamma, the mean size of the agglomerate S(avg) increases slowly with gamma from the collisions between the aggregates and the longitudinal stretching induced by the flow. The proportionality constant A increases exponentially with the scaling factor of the attractive forces acting between the colloidal particles. The value of A shows a rather weak dependence on the solvent viscosity. But A increases proportionally with the scaling factor of the colloid-solvent dissipative interactions. Similar type of dependence can be found for the mixing induced by Rayleigh-Taylor instabilities involving the colloidal agglomerate and the solvent. Three types of fragmentation structures can be identified, which are called rupture, erosion, and shatter. They generate very complex structures with multiresolution character. The aggregation of colloidal beds is formed by the collisions between aggregates, which are influenced by the flow or by the cohesive forces for small dispersion energies. These results may be applied to enhance our understanding concerning the nonlinear complex

Structural analyses of ITER toroidal field coils under fault conditions

International Nuclear Information System (INIS)

Jong, C.T.J.

1992-04-01

ITER (International Thermonuclear Experimental Reactor) is intended to be an experimental thermonuclear tokamak reactor testing the basic physics performance and technologies essential to future fusion reactors. The magnet system of ITER consists essentially of 4 sub-systems, i.e. toroidal field coils (TFCs), poloidal field coils (PFCs), power supplies, and cryogenic supplies. These subsystems do not contain significant radioactivity inventories, but the large energy inventory is a potential accident initiator. The aim of the structural analyses is to prevent accidents from propagating into vacuum vessel, tritium system and cooling system, which all contain significant amounts of radioactivity. As part of design process 3 conditions are defined for PF and TF coils, at which mechanical behaviour has to be analyzed in some detail, viz: normal operating conditions, upset conditions and fault conditions. This paper describes the work carried out by ECN to create a detailed finite element model of 16 TFCs as well as results of some fault condition analyses made with the model. Due to fault conditions, either electrical or mechanical, magnetic loading of TFCs becomes abnormal and further mechanical failure of parts of the overall structure might occur (e.g. failure of coil, gravitational supports, intercoil structure). The analyses performed consist of linear elastic stress analyses and electro-magneto-structural analyses (coupled field analyses). 8 refs.; 5 figs.; 5 tabs

Electronic Identification of the Parental Phases and Mesoscopic Phase Separation of K_{x}Fe_{2-y}Se_{2} Superconductors

Directory of Open Access Journals (Sweden)

F. Chen

2011-12-01

Full Text Available The nature of the parent compound of a high-temperature superconductor (HTS often plays a pivotal role in determining its superconductivity. The parent compounds of the cuprate HTSs are antiferromagnetically ordered Mott insulators, while those of the iron-pnictide HTSs are metals with spin-density-wave order. Here we report the electronic identification of two insulating parental phases and one semiconducting parental phase of the newly discovered family of K_{x}Fe_{2-y}Se_{2} superconductors. The two insulating phases exhibit Mott-insulator-like signatures, and one of the insulating phases is even present in the superconducting and semiconducting K_{x}Fe_{2-y}Se_{2} compounds. However, it is mesoscopically phase-separated from the superconducting or semiconducting phase. Moreover, we find that both the superconducting and semiconducting phases are free of the magnetic and vacancy orders present in the insulating phases, and that the electronic structure of the superconducting phase could be developed by doping the semiconducting phase with electrons. The rich electronic properties discovered in these parental phases of the K_{x}Fe_{2-y}Se_{2} superconductors provide the foundation for studying the anomalous behavior in this new class of iron-based superconductors.

Modifications of the Mesoscopic Structure of Cellulose in Paper Degradation

International Nuclear Information System (INIS)

Missori, Mauro; Bicchieri, Marina; Mondelli, Claudia; De Spirito, Marco; Arcovito, Giuseppe; Papi, Massimiliano; Castellano, Carlo; Castellano, Agostina Congiu; Schweins, Ralf

2006-01-01

Paper is the main component of a huge quantity of cultural heritage. It is primarily composed of cellulose that undergoes significant degradation with the passage of time. By using small angle neutron scattering (SANS), we investigated cellulose's supramolecular structure, which allows access to degradation agents, in ancient and modern samples. For the first time, SANS data were interpreted in terms of water-filled pores, with their sizes increasing from 1.61 nm up to 1.97 nm in natural and artificially aged papers. The protective effect of gelatine sizing was also observed

Superlattice band structure: New and simple energy quantification condition

Energy Technology Data Exchange (ETDEWEB)

Maiz, F., E-mail: fethimaiz@gmail.com [University of Cartage, Nabeul Engineering Preparatory Institute, Merazka, 8000 Nabeul (Tunisia); King Khalid University, Faculty of Science, Physics Department, P.O. Box 9004, Abha 61413 (Saudi Arabia)

2014-10-01

Assuming an approximated effective mass and using Bastard's boundary conditions, a simple method is used to calculate the subband structure for periodic semiconducting heterostructures. Our method consists to derive and solve the energy quantification condition (EQC), this is a simple real equation, composed of trigonometric and hyperbolic functions, and does not need any programming effort or sophistic machine to solve it. For less than ten wells heterostructures, we have derived and simplified the energy quantification conditions. The subband is build point by point; each point presents an energy level. Our simple energy quantification condition is used to calculate the subband structure of the GaAs/Ga{sub 0.5}Al{sub 0.5}As heterostructures, and build its subband point by point for 4 and 20 wells. Our finding shows a good agreement with previously published results.

Condition monitoring and maintenance of nuclear power plant concrete structures

International Nuclear Information System (INIS)

Orr, R.; Prasad, N.

1988-01-01

Nuclear power plant concrete structures are potentially subject to deterioration due to several environmental conditions, including weather exposure, ground water exposure, and sustained high temperature and radiation levels. The nuclear power plant are generally licensed for a term of 40 years. In order to maximize the return from the existing plants, feasibility studies are in progress for continued operation of many of these plants beyond the original licensed life span. This paper describes a study that was performed with an objective to define appropriate condition monitoring and maintenance procedures. A timely implementation of a condition monitoring and maintenance program would provide a valuable database and would provide justification for extension of the plant's design life. The study included concrete structures such as the containment buildings, interior structures, basemats, intake structures and cooling towers. Age-related deterioration at several operating power plants was surveyed and the potential degradation mechanisms have been identified

The influence of mesoscopic confinement on the dynamics of imidazolium-based room temperature ionic liquids in polyether sulfone membranes

Science.gov (United States)

Thomaz, Joseph E.; Bailey, Heather E.; Fayer, Michael D.

2017-11-01

The structural dynamics of a series of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (CnmimNTf2, n = 2, 4, 6, 10: ethyl—Emim; butyl—Bmim; hexyl—Hmim; decyl—Dmim) room temperature ionic liquids confined in the pores of polyether sulfone (PES 200) membranes with an average pore size of ˜350 nm and in the bulk liquids were studied. Time correlated single photon counting measurements of the fluorescence of the fluorophore coumarin 153 (C153) were used to observe the time-dependent Stokes shift (solvation dynamics). The solvation dynamics of C153 in the ionic liquids are multiexponential decays. The multiexponential functional form of the decays was confirmed as the slowest decay component of each bulk liquid matches the slowest component of the liquid dynamics measured by optical heterodyne-detected optical Kerr effect (OHD-OKE) experiments, which is single exponential. The fact that the slowest component of the Stokes shift matches the OHD-OKE data in all four liquids identifies this component of the solvation dynamics as arising from the complete structural randomization of the liquids. Although the pores in the PES membranes are large, confinement on the mesoscopic length scale results in substantial slowing of the dynamics, a factor of ˜4, for EmimNTf2, with the effect decreasing as the chain length increases. By DmimNTf2, the dynamics are virtually indistinguishable from those in the bulk liquid. The rotation relaxation of C153 in the four bulk liquids was also measured and showed strong coupling between the C153 probe and its environment.

Mesoscopic structure prediction of nanoparticle assembly and coassembly: Theoretical foundation

KAUST Repository

Hur, Kahyun

2010-01-01

In this work, we present a theoretical framework that unifies polymer field theory and density functional theory in order to efficiently predict ordered nanostructure formation of systems having considerable complexity in terms of molecular structures and interactions. We validate our approach by comparing its predictions with previous simulation results for model systems. We illustrate the flexibility of our approach by applying it to hybrid systems composed of block copolymers and ligand coated nanoparticles. We expect that our approach will enable the treatment of multicomponent self-assembly with a level of molecular complexity that approaches experimental systems. © 2010 American Institute of Physics.

APPLICABILITY OF SIMILARITY CONDITIONS TO ANALOGUE MODELLING OF TECTONIC STRUCTURES

Directory of Open Access Journals (Sweden)

Mikhail A. Goncharov

2010-01-01

Full Text Available The publication is aimed at comparing concepts of V.V. Belousov and M.V. Gzovsky, outstanding researchers who established fundamentals of tectonophysics in Russia, specifically similarity conditions in application to tectonophysical modeling. Quotations from their publications illustrate differences in their views. In this respect, we can reckon V.V. Belousov as a «realist» as he supported «the liberal point of view» [Methods of modelling…, 1988, p. 21–22], whereas M.V. Gzovsky can be regarded as an «idealist» as he believed that similarity conditions should be mandatorily applied to ensure correctness of physical modeling of tectonic deformations and structures [Gzovsky, 1975, pp. 88 and 94].Objectives of the present publication are (1 to be another reminder about desirability of compliance with similarity conditions in experimental tectonics; (2 to point out difficulties in ensuring such compliance; (3 to give examples which bring out the fact that similarity conditions are often met per se, i.e. automatically observed; (4 to show that modeling can be simplified in some cases without compromising quantitative estimations of parameters of structure formation.(1 Physical modelling of tectonic deformations and structures should be conducted, if possible, in compliance with conditions of geometric and physical similarity between experimental models and corresponding natural objects. In any case, a researcher should have a clear vision of conditions applicable to each particular experiment.(2 Application of similarity conditions is often challenging due to unavoidable difficulties caused by the following: a Imperfection of experimental equipment and technologies (Fig. 1 to 3; b uncertainties in estimating parameters of formation of natural structures, including main ones: structure size (Fig. 4, time of formation (Fig. 5, deformation properties of the medium wherein such structures are formed, including, first of all, viscosity (Fig. 6

Development of damage evaluation method on the brittle materials for constructions using microscopic structural dynamics and probability theory

International Nuclear Information System (INIS)

Arai, Taketoshi

1997-01-01

The conventional stress analysis evaluation of the ceramic apparatuses is due to a perfect model of continuous mechanical materials. Such approximate and simplified treatment is thought to be unsufficient with the following two reasons. At first, because of changes of materials mechanical properties with manufacturing conditions and presence of limit in experimentalismic understanding, establishment of quantitative guideline for improvement of materials and structures and general understanding of thermo-mechanical property change due to neutron radiation becomes difficult. The second, because of statistical change of mechanical property and others containing fracture condition at various loading types, judgement standard of conventional deterministic evaluation is apt to be conservative and causes inferior performance and economics of the constructions under their using conditions. Therefore, in this study, following two basic approaches are planned; 1) Preparation of material deformation and fracture model considering correlation between microscopic/mesoscopic damage and macroscopic behavior, and 2) Improvement of the finite element method calculation due to parallel treatment for soundness and reliability evaluation of the construction. (G.K.)

Mesoscopic modeling of the response of human dental enamel to mid-infrared radiation

Science.gov (United States)

Vila Verde, Ana; Ramos, Marta; Stoneham, A. M.

2006-03-01

Ablation of human dental enamel, a composite biomaterial with water pores, is of significant importance in minimally invasive laser dentistry but progress in the area is hampered by the lack of optimal laser parameters. We use mesoscopic finite element models of this material to study its response to mid-infrared radiation. Our results indicate that the cost-effective, off-the-shelf CO2 laser at λ = 10.6 μm may in fact ablate enamel precisely, reproducibly and with limited unwanted side effects such as cracking or heating, provided that a pulse duration of 10 μs is used. Furthermore, our results also indicate that the Er:YAG laser (λ = 2.94 μm), currently popular for laser dentistry, may in fact cause unwanted deep cracking in the enamel when regions with unusually high water content are irradiated, and also provide an explanation for the large range of ablation threshold values observed for this material. The model may be easily adapted to study the response of any composite material to infrared radiation and thus may be useful for the scientific community.

Intact skull chronic windows for mesoscopic wide-field imaging in awake mice

Science.gov (United States)

Silasi, Gergely; Xiao, Dongsheng; Vanni, Matthieu P.; Chen, Andrew C. N.; Murphy, Timothy H.

2016-01-01

Background Craniotomy-based window implants are commonly used for microscopic imaging, in head-fixed rodents, however their field of view is typically small and incompatible with mesoscopic functional mapping of cortex. New Method We describe a reproducible and simple procedure for chronic through-bone wide-field imaging in awake head-fixed mice providing stable optical access for chronic imaging over large areas of the cortex for months. Results The preparation is produced by applying clear-drying dental cement to the intact mouse skull, followed by a glass coverslip to create a partially transparent imaging surface. Surgery time takes about 30 minutes. A single set-screw provides a stable means of attachment for mesoscale assessment without obscuring the cortical field of view. Comparison with Existing Methods We demonstrate the utility of this method by showing seed-pixel functional connectivity maps generated from spontaneous cortical activity of GCAMP6 signals in both awake and anesthetized mice. Conclusions We propose that the intact skull preparation described here may be used for most longitudinal studies that do not require micron scale resolution and where cortical neural or vascular signals are recorded with intrinsic sensors. PMID:27102043

Guaranteeing robustness of structural condition monitoring to environmental variability

Science.gov (United States)

Van Buren, Kendra; Reilly, Jack; Neal, Kyle; Edwards, Harry; Hemez, François

2017-01-01

Advances in sensor deployment and computational modeling have allowed significant strides to be recently made in the field of Structural Health Monitoring (SHM). One widely used SHM strategy is to perform a vibration analysis where a model of the structure's pristine (undamaged) condition is compared with vibration response data collected from the physical structure. Discrepancies between model predictions and monitoring data can be interpreted as structural damage. Unfortunately, multiple sources of uncertainty must also be considered in the analysis, including environmental variability, unknown model functional forms, and unknown values of model parameters. Not accounting for these sources of uncertainty can lead to false-positives or false-negatives in the structural condition assessment. To manage the uncertainty, we propose a robust SHM methodology that combines three technologies. A time series algorithm is trained using "baseline" data to predict the vibration response, compare predictions to actual measurements collected on a potentially damaged structure, and calculate a user-defined damage indicator. The second technology handles the uncertainty present in the problem. An analysis of robustness is performed to propagate this uncertainty through the time series algorithm and obtain the corresponding bounds of variation of the damage indicator. The uncertainty description and robustness analysis are both inspired by the theory of info-gap decision-making. Lastly, an appropriate "size" of the uncertainty space is determined through physical experiments performed in laboratory conditions. Our hypothesis is that examining how the uncertainty space changes throughout time might lead to superior diagnostics of structural damage as compared to only monitoring the damage indicator. This methodology is applied to a portal frame structure to assess if the strategy holds promise for robust SHM. (Publication approved for unlimited, public release on October-28

An Automatic Control System for Conditioning 30 GHz Accelerating Structures

CERN Document Server

Dubrovskiy, A

2008-01-01

A software application programme has been developed to allow fast and automatic high-gradient conditioning of accelerating structures at 30 GHz in CTF3. The specificity of the application is the ability to control the high-power electron beam which produces the 30 GHz RF power used to condition the accelerating structures. The programme permits operation round the clock with minimum manpower requirements. In this paper the fast control system, machine control system, logging system, graphical user control interface and logging data visualization are described. An outline of the conditioning control system itself and of the feedback controlling peak power and pulse length is given. The software allows different types of conditioning strategies to be programmed

Significance of Operating Environment in Condition Monitoring of Large Civil Structures

OpenAIRE

Alampalli, Sreenivas

1999-01-01

Success of remote long-term condition monitoring of large civil structures and developing calibrated analytical models for damage detection, depend significantly on establishing accurate baseline signatures and their sensitivity. Most studies reported in the literature concentrated on the effect of structural damage on modal parameters without emphasis on reliability of modal parameters. Thus, a field bridge structure was studied for the significance of operating conditions in relation to bas...

42 CFR 485.627 - Condition of participation: Organizational structure.

Science.gov (United States)

2010-10-01

... participation: Organizational structure. (a) Standard: Governing body or responsible individual. The CAH has a... 42 Public Health 5 2010-10-01 2010-10-01 false Condition of participation: Organizational structure. 485.627 Section 485.627 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF...

Mesoscopic biology

Indian Academy of Sciences (India)

these interactions and their spatio-temporal dynamics are beginning to be explored. ... The elucidation of the structure of DNA and the realization that DNA provides ... molecular recognition during DNA-protein interactions that mediate gene ...

Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO3/SrTiO3/SmTiO3 Quantum Well Structures.

Science.gov (United States)

Hardy, Will J; Isaac, Brandon; Marshall, Patrick; Mikheev, Evgeny; Zhou, Panpan; Stemmer, Susanne; Natelson, Douglas

2017-04-25

Heterointerfaces of SrTiO 3 with other transition metal oxides make up an intriguing family of systems with a bounty of coexisting and competing physical orders. Some examples, such as LaAlO 3 /SrTiO 3 , support a high carrier density electron gas at the interface whose electronic properties are determined by a combination of lattice distortions, spin-orbit coupling, defects, and various regimes of magnetic and charge ordering. Here, we study electronic transport in mesoscale devices made with heterostructures of SrTiO 3 sandwiched between layers of SmTiO 3 , in which the transport properties can be tuned from a regime of Fermi-liquid like resistivity (ρ ∝ T 2 ) to a non-Fermi liquid (ρ ∝ T 5/3 ) by controlling the SrTiO 3 thickness. In mesoscale devices at low temperatures, we find unexpected voltage fluctuations that grow in magnitude as T is decreased below 20 K, are suppressed with increasing contact electrode size, and are independent of the drive current and contact spacing distance. Magnetoresistance fluctuations are also observed, which are reminiscent of universal conductance fluctuations but not entirely consistent with their conventional properties. Candidate explanations are considered, and a mechanism is suggested based on mesoscopic temporal fluctuations of the Seebeck coefficient. An improved understanding of charge transport in these model systems, especially their quantum coherent properties, may lead to insights into the nature of transport in strongly correlated materials that deviate from Fermi liquid theory.

Structural Composite Supercapacitors: Electrical and Mechanical Impact of Separators and Processing Conditions

Science.gov (United States)

2013-09-01

Structural Composite Supercapacitors : Electrical and Mechanical Impact of Separators and Processing Conditions by Edwin B. Gienger, James F...Proving Ground, MD 21005-5066 ARL-TR-6624 September 2013 Structural Composite Supercapacitors : Electrical and Mechanical Impact of...2012 4. TITLE AND SUBTITLE Structural Composite Supercapacitors : Electrical and Mechanical Impact of Separators and Processing Conditions 5a

Estimation for bolt fastening conditions of thin aluminum structure using PZT sensors

International Nuclear Information System (INIS)

Hong, Yong; Han, Byeong Hee; Kim, Byung Jin; Hong, Dong Pyo; Kim, Young Moon

2007-01-01

This work presents a study on PZT impedance-based method, it is one of the NDT(Non-Destructive Technique). We study about assessment of the square-structure health condition by impedance-based technique using PZT patches, associated with longitudinal wave propagation. Health conditions of the square-structure controlled by bolt fastening condition is adjusted by torque wrench. In order to estimate the damage condition numerically, we suggest the evaluation method of impedance peak frequency shift

Equilibrium state of a cylindrical particle with flat ends in nematic liquid crystals.

Science.gov (United States)

Hashemi, S Masoomeh; Ejtehadi, Mohammad Reza

2015-01-01

A continuum theory is employed to numerically study the equilibrium orientation and defect structures of a circular cylindrical particle with flat ends under a homeotropic anchoring condition in a uniform nematic medium. Different aspect ratios of this colloidal geometry from thin discotic to long rodlike shapes and several colloidal length scales ranging from mesoscale to nanoscale are investigated. We show that the equilibrium state of this colloidal geometry is sensitive to the two geometrical parameters: aspect ratio and length scale of the particle. For a large enough mesoscopic particle, there is a specific asymptotic equilibrium angle associated to each aspect ratio. Upon reducing the particle size to nanoscale, the equilibrium angle follows a descending or ascending trend in such a way that the equilibrium angle of a particle with the aspect ratio bigger than 1:1 (a discotic particle) goes to a parallel alignment with respect to the far-field nematic, whereas the equilibrium angle for a particle with the aspect ratio 1:1 and smaller (a rodlike particle) tends toward a perpendicular alignment to the uniform nematic direction. The discrepancy between the equilibrium angles of the mesoscopic and nanoscopic particles originates from the significant differences between their defect structures. The possible defect structures related to mesoscopic and nanoscopic colloidal particles of this geometry are also introduced.

Metastable Structures in Cluster Catalysis from First-Principles: Structural Ensemble in Reaction Conditions and Metastability Triggered Reactivity.

Science.gov (United States)

Sun, Geng; Sautet, Philippe

2018-02-28

Reactivity studies on catalytic transition metal clusters are usually performed on a single global minimum structure. With the example of a Pt 13 cluster under a pressure of hydrogen, we show from first-principle calculations that low energy metastable structures of the cluster can play a major role for catalytic reactivity and that hence consideration of the global minimum structure alone can severely underestimate the activity. The catalyst is fluxional with an ensemble of metastable structures energetically accessible at reaction conditions. A modified genetic algorithm is proposed to comprehensively search for the low energy metastable ensemble (LEME) structures instead of merely the global minimum structure. In order to reduce the computational cost of density functional calculations, a high dimensional neural network potential is employed to accelerate the exploration. The presence and influence of LEME structures during catalysis is discussed by the example of H covered Pt 13 clusters for two reactions of major importance: hydrogen evolution reaction and methane activation. The results demonstrate that although the number of accessible metastable structures is reduced under reaction condition for Pt 13 clusters, these metastable structures can exhibit high activity and dominate the observed activity due to their unique electronic or structural properties. This underlines the necessity of thoroughly exploring the LEME structures in catalysis simulations. The approach enables one to systematically address the impact of isomers in catalysis studies, taking into account the high adsorbate coverage induced by reaction conditions.

Four dimensional chaos and intermittency in a mesoscopic model of the electroencephalogram.

Science.gov (United States)

Dafilis, Mathew P; Frascoli, Federico; Cadusch, Peter J; Liley, David T J

2013-06-01

The occurrence of so-called four dimensional chaos in dynamical systems represented by coupled, nonlinear, ordinary differential equations is rarely reported in the literature. In this paper, we present evidence that Liley's mesoscopic theory of the electroencephalogram (EEG), which has been used to describe brain activity in a variety of clinically relevant contexts, possesses a chaotic attractor with a Kaplan-Yorke dimension significantly larger than three. This accounts for simple, high order chaos for a physiologically admissible parameter set. Whilst the Lyapunov spectrum of the attractor has only one positive exponent, the contracting dimensions are such that the integer part of the Kaplan-Yorke dimension is three, thus giving rise to four dimensional chaos. A one-parameter bifurcation analysis with respect to the parameter corresponding to extracortical input is conducted, with results indicating that the origin of chaos is due to an inverse period doubling cascade. Hence, in the vicinity of the high order, strange attractor, the model is shown to display intermittent behavior, with random alternations between oscillatory and chaotic regimes. This phenomenon represents a possible dynamical justification of some of the typical features of clinically established EEG traces, which can arise in the case of burst suppression in anesthesia and epileptic encephalopathies in early infancy.

Small strain multiphase-field model accounting for configurational forces and mechanical jump conditions

Science.gov (United States)

Schneider, Daniel; Schoof, Ephraim; Tschukin, Oleg; Reiter, Andreas; Herrmann, Christoph; Schwab, Felix; Selzer, Michael; Nestler, Britta

2018-03-01

Computational models based on the phase-field method have become an essential tool in material science and physics in order to investigate materials with complex microstructures. The models typically operate on a mesoscopic length scale resolving structural changes of the material and provide valuable information about the evolution of microstructures and mechanical property relations. For many interesting and important phenomena, such as martensitic phase transformation, mechanical driving forces play an important role in the evolution of microstructures. In order to investigate such physical processes, an accurate calculation of the stresses and the strain energy in the transition region is indispensable. We recall a multiphase-field elasticity model based on the force balance and the Hadamard jump condition at the interface. We show the quantitative characteristics of the model by comparing the stresses, strains and configurational forces with theoretical predictions in two-phase cases and with results from sharp interface calculations in a multiphase case. As an application, we choose the martensitic phase transformation process in multigrain systems and demonstrate the influence of the local homogenization scheme within the transition regions on the resulting microstructures.

Design and analysis of CANDU NPP internal structures for Japanese conditions

International Nuclear Information System (INIS)

Aziz, T.S.; Murakami, H.

1991-01-01

The design and analysis approach for the CANDU 6 Internal Concrete Structure (ICS) for Japanese seismic conditions is described. The approach consists of a seismic analysis to determine the design level accelerations; followed by a detailed finite element analysis to determine the section forces for each shell element. The extent of the design modifications for the original structure to meet the Japanese design conditions is given. (author)

Behaviour of concrete under high confinement: study in triaxial compression and in triaxial extension at the mesoscopic scale

International Nuclear Information System (INIS)

Dupray, F.

2008-12-01

This Ph.D. thesis aims at characterising and modeling the mechanical behaviour of concrete under high confinement at the mesoscopic scale. This scale corresponds to that of the large aggregates and the cementitious matrix. The more general scope of this study is the understanding of concrete behaviour under dynamic loading. A dynamic impact can generate mean pressures around 1 GPa. But the characterisation of a material response, in an homogeneous state of stress, can only be achieved through quasi-static tests. The experimentations led in 3S-R Laboratory have underlined the importance of the aggregates in the triaxial response of concrete. Modeling concrete at the mesoscopic level, as a composite of an aggregates phase and a mortar phase, permits a representation of the aggregates effect. An experimental study of the behaviour of mortar phase is performed. Usual tests and hydrostatic and triaxial high confinement tests are realised. The parameters of a constitutive model that couples plasticity with a damage law are identified from these tests. This model is able to reproduce the nonlinear compaction of mortar, the damage behaviour under uniaxial tension or compression, and plasticity under high confinement. The biphasic model uses the finite element method with a cubic and regular mesh. A Monte-Carlo method is used to place quasi-spherical aggregates that respect the given particle size of a reference concrete. Each element is identified by belonging either to the mortar or to the aggregate phase. Numerical simulations are compared with the experimental tests on this concrete. The parameters for these simulations are only identified on the mortar. The simulations reproduce the different phases observed in hydrostatic compression. The evolution of axial moduli under growing confinement is shown, as is the good reproduction of the limit-states experimentally observed under high confinement. The fracture aspect of numerical simulations is comparable with that of

Condition Indicators for Inspection Planning of Concrete Structures

DEFF Research Database (Denmark)

Faber, Michael Havbro; Sørensen, John Dalsgaard

2002-01-01

Based on previous work by the authors a Bayesian formulation of condition indicators is developed further whereby in conjunction with a systems modelling of concrete structures the experience and expertise of the inspection personnel may be fully utilized. It is shown how the predicted evolution ...

A micromagnetic study of domain structure modeling

International Nuclear Information System (INIS)

Matsuo, Tetsuji; Mimuro, Naoki; Shimasaki, Masaaki

2008-01-01

To develop a mesoscopic model for magnetic-domain behavior, a domain structure model (DSM) was examined and compared with a micromagnetic simulation. The domain structure of this model is given by several domains with uniform magnetization vectors and domain walls. The directions of magnetization vectors and the locations of domain walls are determined so as to minimize the magnetic total energy of the magnetic material. The DSM was modified to improve its representation capability for domain behavior. The domain wall energy is multiplied by a vanishing factor to represent the disappearance of magnetic domain. The sequential quadratic programming procedure is divided into two steps to improve an energy minimization process. A comparison with micromagnetic simulation shows that the modified DSM improves the representation accuracy of the magnetization process

Correlated Coulomb drag in capacitively coupled quantum-dot structures

DEFF Research Database (Denmark)

Kaasbjerg, Kristen; Jauho, Antti-Pekka

2016-01-01

We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneling......) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multi-electron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters...... on Coulomb drag in CQD systems....

Structural Evaluation on HIC Transport Packaging under Accident Conditions

International Nuclear Information System (INIS)

Chung, Sung Hwan; Kim, Duck Hoi; Jung, Jin Se; Yang, Ke Hyung; Lee, Heung Young

2005-01-01

HIC transport packaging to transport a high integrity container(HIC) containing dry spent resin generated from nuclear power plants is to comply with the regulatory requirements of Korea and IAEA for Type B packaging due to the high radioactivity of the content, and to maintain the structural integrity under normal and accident conditions. It must withstand 9 m free drop impact onto an unyielding surface and 1 m drop impact onto a mild steel bar in a position causing maximum damage. For the conceptual design of a cylindrical HIC transport package, three dimensional dynamic structural analysis to ensure that the integrity of the package is maintained under all credible loads for 9 m free drop and 1 m puncture conditions were carried out using ABAQUS code.

Aespoe Hard Rock Laboratory. Analysis of fracture networks based on the integration of structural and hydrogeological observations on different scales

Energy Technology Data Exchange (ETDEWEB)

Bossart, P. [Geotechnical Inst. Ltd., Bern (Switzerland); Hermanson, Jan [Golder Associates, Stockholm (Sweden); Mazurek, M. [Univ. of Bern (Switzerland)

2001-05-01

Fracture networks at Aespoe have been studied for several rock types exhibiting different degrees of ductile and brittle deformation, as well as on different scales. Mesoscopic fault systems have been characterised and classified in an earlier report, this report focuses mainly on fracture networks derived on smaller scales, but also includes mesoscopic and larger scales. The TRUE-1 block has been selected for detailed structural analysis on a small scale due to the high density of relevant information. In addition to the data obtained from core materials, structural maps, BIP data and the results of hydro tests were synthesised to derive a conceptual structural model. The approach used to derive this conceptual model is based on the integration of deterministic structural evidence, probabilistic information and both upscaling and downscaling of observations and concepts derived on different scales. Twelve fracture networks mapped at different sites and scales and exhibiting various styles of tectonic deformation were analysed for fractal properties and structural and hydraulic interconnectedness. It was shown that these analysed fracture networks are not self-similar. An important result is the structural and hydraulic interconnectedness of fracture networks on all scales in the Aespoe rocks, which is further corroborated by geochemical evidence. Due to the structural and hydraulic interconnectedness of fracture systems on all scales at Aespoe, contaminants from waste canisters placed in tectonically low deformation environments would be transported - after having passed through the engineered barriers -from low-permeability fractures towards higher permeability fractures and may thus eventually reach high-permeability features.

Aespoe Hard Rock Laboratory. Analysis of fracture networks based on the integration of structural and hydrogeological observations on different scales

International Nuclear Information System (INIS)

Bossart, P.; Hermanson, Jan; Mazurek, M.

2001-05-01

Fracture networks at Aespoe have been studied for several rock types exhibiting different degrees of ductile and brittle deformation, as well as on different scales. Mesoscopic fault systems have been characterised and classified in an earlier report, this report focuses mainly on fracture networks derived on smaller scales, but also includes mesoscopic and larger scales. The TRUE-1 block has been selected for detailed structural analysis on a small scale due to the high density of relevant information. In addition to the data obtained from core materials, structural maps, BIP data and the results of hydro tests were synthesised to derive a conceptual structural model. The approach used to derive this conceptual model is based on the integration of deterministic structural evidence, probabilistic information and both upscaling and downscaling of observations and concepts derived on different scales. Twelve fracture networks mapped at different sites and scales and exhibiting various styles of tectonic deformation were analysed for fractal properties and structural and hydraulic interconnectedness. It was shown that these analysed fracture networks are not self-similar. An important result is the structural and hydraulic interconnectedness of fracture networks on all scales in the Aespoe rocks, which is further corroborated by geochemical evidence. Due to the structural and hydraulic interconnectedness of fracture systems on all scales at Aespoe, contaminants from waste canisters placed in tectonically low deformation environments would be transported - after having passed through the engineered barriers -from low-permeability fractures towards higher permeability fractures and may thus eventually reach high-permeability features

Mesoscopic multiphase structures and the interfaces of block and graft copolymers in bulk

International Nuclear Information System (INIS)

Matsushita, Yushu

1996-01-01

Microphase-separated structures of copolymers with various architectures and their polymer/polymer interfaces were studied. They are SP diblock, PSP triblock, and SPP graft copolymers, where S and P denote polystyrene and poly(2-vinylpyridine), respectively. Morphological observations were carried out by means of transmission electron microscopy and small-angle X-ray scattering. Chain dimensions of component polymers were measured by small-angle neutron scattering and microphase-separated interfaces were observed by neutron reflectivity measurements using deuterium-labeled samples. It was clarified that morphological phase transitions among thermodynamically equilibrium structures for SP diblock and PSP triblock copolymers occur at almost the same compositions; however, those of SPP graft copolymers tend to occur at higher volume fraction of polystyrene, φ s , than those for block copolymers. As for alternating lamellar structures it turned out to be clear that lamellar domain spacings, D's, were scaled as the 2/3 power of the molecular weight of polymers irrespective of their architectures. S block chains of SP diblock and PSP triblock copolymers in lamellar structures were both confirmed to be deformed toward the direction perpendicular to the lamellar interfaces, but it revealed that their volumes were preserved. Further, S/P interfacial thicknesses of SP and PSP were essentially the same to each other and the values defined as the FWHM of the error functions which express the segment density distributions of the interfaces were determined to be about 4 nm. (author)

Growth of monodisperse mesoscopic metal-oxide colloids under constant monomer supply

Science.gov (United States)

Nozawa, Koh; Delville, Marie-Hélène; Ushiki, Hideharu; Panizza, Pascal; Delville, Jean-Pierre

2005-07-01

In closed systems, control over the size of monodisperse metal-oxide colloids is generally limited to submicrometric dimensions. To overcome this difficulty, we explore the formation and growth of silica particles under constant monomer supply. The monomer source is externally driven by the progressive addition into the system of one of the precursors. Monodisperse spherical particles are produced up to a mesoscopic size. We analyze their growth versus the monomer addition rate at different temperatures. Our results show that in the presence of a continuous monomer addition, growth is limited by diffusion over the investigated temporal window. Using the temperature variation of the growth rate, we prove that rescaling leads to a data reduction onto a single master curve. Contrary to the growth process, the final particle’s size reached after the end of the reagent supply strongly depends on the addition rate. The variation of the final particle size versus addition rate can be deduced from an analogy with crystal formation in jet precipitation. Within this framework, and using the temperature dependences of both the particle growth law and the final size, we determine the value of the molecular heat of dissolution associated to the silica solubility. These observations support the fact that classical theories of phase-ordering dynamics can be extended to the synthesis of inorganic particles. The emergence of a master behavior in the presence of continuous monomer addition also suggests the extension of these theories to open systems.

Detecting the overlapping and hierarchical community structure in complex networks

International Nuclear Information System (INIS)

Lancichinetti, Andrea; Fortunato, Santo; Kertesz, Janos

2009-01-01

Many networks in nature, society and technology are characterized by a mesoscopic level of organization, with groups of nodes forming tightly connected units, called communities or modules, that are only weakly linked to each other. Uncovering this community structure is one of the most important problems in the field of complex networks. Networks often show a hierarchical organization, with communities embedded within other communities; moreover, nodes can be shared between different communities. Here, we present the first algorithm that finds both overlapping communities and the hierarchical structure. The method is based on the local optimization of a fitness function. Community structure is revealed by peaks in the fitness histogram. The resolution can be tuned by a parameter enabling different hierarchical levels of organization to be investigated. Tests on real and artificial networks give excellent results.

Time-dependent reliability analysis and condition assessment of structures

International Nuclear Information System (INIS)

Ellingwood, B.R.

1997-01-01

Structures generally play a passive role in assurance of safety in nuclear plant operation, but are important if the plant is to withstand the effect of extreme environmental or abnormal events. Relative to mechanical and electrical components, structural systems and components would be difficult and costly to replace. While the performance of steel or reinforced concrete structures in service generally has been very good, their strengths may deteriorate during an extended service life as a result of changes brought on by an aggressive environment, excessive loading, or accidental loading. Quantitative tools for condition assessment of aging structures can be developed using time-dependent structural reliability analysis methods. Such methods provide a framework for addressing the uncertainties attendant to aging in the decision process

Mesoscopic nonequilibrium thermodynamics of solid surfaces and interfaces with triple junction singularities under the capillary and electromigration forces in anisotropic three-dimensional space.

Science.gov (United States)

Ogurtani, Tarik Omer

2006-04-14

A theory of irreversible thermodynamics of curved surfaces and interfaces with triple junction singularities is elaborated to give a full consideration of the effects of the specific surface Gibbs free energy anisotropy in addition to the diffusional anisotropy, on the morphological evolution of surfaces and interfaces in crystalline solids. To entangle this intricate problem, the internal entropy production associated with arbitrary virtual displacements of triple junction and ordinary points on the interfacial layers, embedded in a multicomponent, multiphase, anisotropic composite continuum system, is formulated by adapting a mesoscopic description of the orientation dependence of the chemical potentials in terms of the rotational degree of freedom of individual microelements. The rate of local internal entropy production resulted generalized forces and conjugated fluxes not only for the grain boundary triple junction transversal and longitudinal movements, but also for the ordinary points. The natural combination of the mesoscopic approach coupled with the rigorous theory of irreversible thermodynamics developed previously by the global entropy production hypothesis yields a well-posed, nonlinear, moving free-boundary value problem in two-dimensional (2D) space, as a unified theory. The results obtained for 2D space are generalized into the three-dimensional continuum by utilizing the invariant properties of the vector operators in connection with the descriptions of curved surfaces in differential geometry. This mathematical model after normalization and scaling procedures may be easily adapted for computer simulation studies without introducing any additional phenomenological system parameters (the generalized mobilities), other than the enlarged concept of the surface stiffness.

Aharonov-Bohm oscillations, quantum decoherence and amplitude modulation in mesoscopic InGaAs/InAlAs rings.

Science.gov (United States)

Ren, S L; Heremans, J J; Gaspe, C K; Vijeyaragunathan, S; Mishima, T D; Santos, M B

2013-10-30

Low-temperature Aharonov-Bohm oscillations in the magnetoresistance of mesoscopic interferometric rings patterned on an InGaAs/InAlAs heterostructure are investigated for their dependence on excitation current and temperature. The rings have an average radius of 650 nm, and a lithographic arm width of 300 nm, yielding pronounced interference oscillations over a wide range of magnetic fields. Apart from a current and temperature dependence, the oscillation amplitude also shows a quasi-periodic modulation with applied magnetic field. The phase coherence length is extracted by analysis of the fundamental and higher Fourier components of the oscillations, and by direct analysis of the amplitude and its dependence on parameters. It is concluded that the Thouless energy forms the measure of excitation energies for quantum decoherence. The amplitude modulation finds an explanation in the effect of the magnetic flux threading the finite width of the interferometer arms.

Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

Energy Technology Data Exchange (ETDEWEB)

Ngo, D. Q.; Petković, I., E-mail: ivana.petkovic@yale.edu; Lollo, A. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Castellanos-Beltran, M. A. [National Institute for Standards and Technology, Boulder, Colorado 80305 (United States); Harris, J. G. E. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

2014-10-15

We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 10{sup 5} rings. The rings have a circumference of 1 μm, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of .