Transport processes in macroscopically disordered media from mean field theory to percolation

CERN Document Server

Snarskii, Andrei A; Sevryukov, Vladimir A; Morozovskiy, Alexander; Malinsky, Joseph

2016-01-01

This book reflects on recent advances in the understanding of percolation systems to present a wide range of transport phenomena in inhomogeneous disordered systems. Further developments in the theory of macroscopically inhomogeneous media are also addressed. These developments include galvano-electric, thermoelectric, elastic properties, 1/f noise and higher current momenta, Anderson localization, and harmonic generation in composites in the vicinity of the percolation threshold. The book describes how one can find effective characteristics, such as conductivity, dielectric permittivity, magnetic permeability, with knowledge of the distribution of different components constituting an inhomogeneous medium. Considered are a wide range of recent studies dedicated to the elucidation of physical properties of macroscopically disordered systems. Aimed at researchers and advanced students, it contains a straightforward set of useful tools which will allow the reader to derive the basic physical properties of compli...

Percolation of binary disk systems: Modeling and theory

International Nuclear Information System (INIS)

Meeks, Kelsey; Pantoya, Michelle L.

2017-01-01

The dispersion and connectivity of particles with a high degree of polydispersity is relevant to problems involving composite material properties and reaction decomposition prediction and has been the subject of much study in the literature. This paper utilizes Monte Carlo models to predict percolation thresholds for a two-dimensional systems containing disks of two different radii. Monte Carlo simulations and spanning probability are used to extend prior models into regions of higher polydispersity than those previously considered. A correlation to predict the percolation threshold for binary disk systems is proposed based on the extended dataset presented in this work and compared to previously published correlations. Finally, a set of boundary conditions necessary for a good fit is presented, and a condition for maximizing percolation threshold for binary disk systems is suggested.

Percolating cluster of center vortices and confinement

International Nuclear Information System (INIS)

Gliozzi, Ferdinando; Panero, Marco; Provero, Paolo

2003-01-01

We study the role of percolating clusters of center vortices in configurations of an Ising gauge theory in 3D. It is known that low energy features of gauge theories can be described in terms of an 'effective string picture', and that confinement properties are associated with topologically non-trivial configurations. We focus our attention upon percolating clusters of center vortices, and present numerical evidence for the fact that these objects play a preminent role in confinement phenomenon, since their removal sweeps off confinement altogether. Moreover, numerical simulations show that the string fluctuations, and in particular the Mischer term, are completely encoded in the percolating cluster

One-dimensional long-range percolation: A numerical study

Science.gov (United States)

Gori, G.; Michelangeli, M.; Defenu, N.; Trombettoni, A.

2017-07-01

In this paper we study bond percolation on a one-dimensional chain with power-law bond probability C /rd +σ , where r is the distance length between distinct sites and d =1 . We introduce and test an order-N Monte Carlo algorithm and we determine as a function of σ the critical value Cc at which percolation occurs. The critical exponents in the range 0 values for Cc are compared with a known exact bound, while the critical exponent ν is compared with results from mean-field theory, from an expansion around the point σ =1 and from the ɛ -expansion used with the introduction of a suitably defined effective dimension deff relating the long-range model with a short-range one in dimension deff. We finally present a formulation of our algorithm for bond percolation on general graphs, with order N efficiency on a large class of graphs including short-range percolation and translationally invariant long-range models in any spatial dimension d with σ >0 .

Percolation theory for flow in porous media

CERN Document Server

Hunt, Allen; Ghanbarian, Behzad

2014-01-01

This monograph presents, for the first time, a unified and comprehensive introduction to some of the basic transport properties of porous media, such as electrical and hydraulic conductivity, air permeability and diffusion. The approach is based on critical path analysis and the scaling of transport properties, which are individually described as functions of saturation. At the same time, the book supplies a tutorial on percolation theory for hydrologists, providing them with the tools for solving actual problems. In turn, a separate chapter serves to introduce physicists to some of the language and complications of groundwater hydrology necessary for successful modeling. The end-of-chapter problems often indicate open questions, which young researchers entering the field can readily start working on. This significantly revised and expanded third edition includes in particular two new chapters: one on advanced fractal-based models, and one devoted to the discussion of various open issues such as the role of d...

Multifragmentation and percolation

International Nuclear Information System (INIS)

Campi, X.; Desbois, J.

1985-01-01

Percolation theory is applied to the problem of nucleus break-up. A model of nuclear percolation is proposed in which the rules for linkage of nucleons to form a cluster are defined in real and momentum spaces. This model exhibits a rather well defined threshold at rho ≅ 0.6. Analytical expressions for cluster size distributions at fixed concentration rho are given. Decay of excited clusters (by evaporation and fission) to give stable nuclear fragments is incorporated. The distribution law for rho in inclusive reactions is studied and the calculated mass yields are compared to experimental results

Percolation in real multiplex networks

Science.gov (United States)

Bianconi, Ginestra; Radicchi, Filippo

2016-12-01

We present an exact mathematical framework able to describe site-percolation transitions in real multiplex networks. Specifically, we consider the average percolation diagram valid over an infinite number of random configurations where nodes are present in the system with given probability. The approach relies on the locally treelike ansatz, so that it is expected to accurately reproduce the true percolation diagram of sparse multiplex networks with negligible number of short loops. The performance of our theory is tested in social, biological, and transportation multiplex graphs. When compared against previously introduced methods, we observe improvements in the prediction of the percolation diagrams in all networks analyzed. Results from our method confirm previous claims about the robustness of real multiplex networks, in the sense that the average connectedness of the system does not exhibit any significant abrupt change as its individual components are randomly destroyed.

Integral hierarchies and percolation

International Nuclear Information System (INIS)

Klein, W.; Stell, G.

1985-01-01

For a variation of the Potts model which has been shown to describe continuum percolation, we derive a hierarchy of integral equations of Kirkwood-Salsburg type. The distribution functions which are the solutions of this hierarchy can be simply related to the connectedness functions in continuum percolation. From this hierarchy a second set of equations is derived from which the connectedness functions can be obtained directly. This approach is extremely useful when investigating properties of systems far from the percolation transition. These hierarchies are solved exactly in the mean-field (Kac-Baker) limit and possible implications for cluster growth are discussed. The relation between the Potts model for continuum percolation and the Widom-Rowlinson model is also noted

Conformal Field Theory of Percolation (1)

CERN Multimedia

CERN. Geneva

2015-01-01

This series of 5 lectures will describe what is known about the Logarithmic CFT describing the critical point of percolation. The subsequent lectures will take place in TH Conference room on: (2) Wednesday Sep 16 at 10am (3) Thursday Sep 17 at 10am (4) Thursday Sep 17 at 2pm (5) Friday Sep 18 at 10am

Social percolation models

Science.gov (United States)

Solomon, Sorin; Weisbuch, Gerard; de Arcangelis, Lucilla; Jan, Naeem; Stauffer, Dietrich

2000-03-01

We here relate the occurrence of extreme market shares, close to either 0 or 100%, in the media industry to a percolation phenomenon across the social network of customers. We further discuss the possibility of observing self-organized criticality when customers and cinema producers adjust their preferences and the quality of the produced films according to previous experience. Comprehensive computer simulations on square lattices do indeed exhibit self-organized criticality towards the usual percolation threshold and related scaling behaviour.

Electrical percolation threshold of magnetostrictive inclusions in a piezoelectric matrix composite as a function of relative particle size

Science.gov (United States)

Barbero, Ever J.; Bedard, Antoine Joseph

2018-04-01

Magnetoelectric composites can be produced by embedding magnetostrictive particles in a piezoelectric matrix derived from a piezoelectric powder precursor. Ferrite magnetostrictive particles, if allowed to percolate, can short the potential difference generated in the piezoelectric phase. Modeling a magnetoelectric composite as an aggregate of bi-disperse hard shells, molecular dynamics was used to explore relationships among relative particle size, particle affinity, and electrical percolation with the goal of maximizing the percolation threshold. It is found that two factors raise the percolation threshold, namely the relative size of magnetostrictive to piezoelectric particles, and the affinity between the magnetostrictive and piezoelectric particles.

Percolation of polyatomic species on site diluted lattices

International Nuclear Information System (INIS)

Cornette, V.; Ramirez-Pastor, A.J.; Nieto, F.

2006-01-01

In this Letter, the percolation of (a) linear segments of size k and (b) k-mers (particles occupying k adjacent sites) of different structures and forms deposited on a diluted square lattice have been studied. The diluted lattice is built by randomly selecting a fraction of sites which are considered forbidden for deposition. The analysis of the obtained results is made in the framework of the finite size scaling theory. The characteristic parameters of the percolation problem are dependent not only on the form and structure of the k-mers but also on the properties of the lattice where they are deposited. A phase diagram separating a percolating from a non-percolating region is determined and discussed

Practical Guidelines for Water Percolation Capacity Determination of the Ground

Directory of Open Access Journals (Sweden)

Mihael Brenčič

2011-06-01

Full Text Available Determination of water infiltration capacity of ground soils and rocks represents important part of design and construction procedures of the facilities for the infiltration of clean precipitation water. With their help percolation capacity of ground as well as response of the infiltration facilities to the inflowing precipitation water is estimated.Comparing to other in situ hydrogeological tests they can be understood as simple. However, in every day’s practiceseveral problems during their on site application and desk interpretation can arise. Paper represents review of existingpractical engineering procedures during the performance of percolation tests. Procedures are described for the borehole and shaft percolation tests execution and calculation theory for stationary and non‑stationary percolation tests are given. Theory is illustrated with practical exercises. Interpretations of typical departures from theoretical presumptions according to Hvorslev test of non-stationary test are illustrated.

Percolation Magnetism in Ferroelectric Nanoparticles

Science.gov (United States)

Golovina, Iryna S.; Lemishko, Serhii V.; Morozovska, Anna N.

2017-06-01

Nanoparticles of potassium tantalate (KTaO3) and potassium niobate (KNbO3) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe3+ ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.

Percolation Magnetism in Ferroelectric Nanoparticles.

Science.gov (United States)

Golovina, Iryna S; Lemishko, Serhii V; Morozovska, Anna N

2017-12-01

Nanoparticles of potassium tantalate (KTaO 3 ) and potassium niobate (KNbO 3 ) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe 3+ ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.

Percolation of overlapping squares or cubes on a lattice

International Nuclear Information System (INIS)

Koza, Zbigniew; Kondrat, Grzegorz; Suszczyński, Karol

2014-01-01

Porous media are often modeled as systems of overlapping obstacles, which leads to the problem of two percolation thresholds in such systems, one for the porous matrix and the other for the void space. Here we investigate these percolation thresholds in the model of overlapping squares or cubes of linear size k > 1 randomly distributed on a regular lattice. We find that the percolation threshold of obstacles is a nonmonotonic function of k, whereas the percolation threshold of the void space is well approximated by a function linear in 1/k. We propose a generalization of the excluded volume approximation to discrete systems and use it to investigate the transition between continuous and discrete percolation, finding a remarkable agreement between the theory and numerical results. We argue that the continuous percolation threshold of aligned squares on a plane is the same for the solid and void phases and estimate the continuous percolation threshold of the void space around aligned cubes in a 3D space as 0.036(1). We also discuss the connection of the model to the standard site percolation with complex neighborhood. (paper)

Plasmonic percolation: Plasmon-manifested dielectric-to-metal transition

KAUST Repository

Chen, Huanjun

2012-08-28

Percolation generally refers to the phenomenon of abrupt variations in electrical, magnetic, or optical properties caused by gradual volume fraction changes of one component across a threshold in bicomponent systems. Percolation behaviors have usually been observed in macroscopic systems, with most studies devoted to electrical percolation. We report on our observation of plasmonic percolation in Au nanorod core-Pd shell nanostructures. When the Pd volume fraction in the shell consisting of palladium and water approaches the plasmonic percolation threshold, ∼70%, the plasmon of the nanostructure transits from red to blue shifts with respect to that of the unshelled Au nanorod. This plasmonic percolation behavior is also confirmed by the scattering measurements on the individual core-shell nanostructures. Quasistatic theory and numerical simulations show that the plasmonic percolation originates from a positive-to-negative transition in the real part of the dielectric function of the shell as the Pd volume fraction is increased. The observed plasmonic percolation is found to be independent of the metal type in the shell. Moreover, compared to the unshelled Au nanorods with similar plasmon wavelengths, the Au nanorod core-Pd shell nanostructures exhibit larger refractive index sensitivities, which is ascribed to the expulsion of the electric field intensity from the Au nanorod core by the adsorbed Pd nanoparticles. © 2012 American Chemical Society.

Plasmonic percolation: Plasmon-manifested dielectric-to-metal transition

KAUST Repository

Chen, Huanjun; Wang, Feng; Li, Kun; Woo, Katchoi; Wang, Jianfang; Li, Quan; Sun, Ling Dong; Zhang, Xixiang; Lin, Haiqing; YAN, Chunhua

2012-01-01

Percolation generally refers to the phenomenon of abrupt variations in electrical, magnetic, or optical properties caused by gradual volume fraction changes of one component across a threshold in bicomponent systems. Percolation behaviors have usually been observed in macroscopic systems, with most studies devoted to electrical percolation. We report on our observation of plasmonic percolation in Au nanorod core-Pd shell nanostructures. When the Pd volume fraction in the shell consisting of palladium and water approaches the plasmonic percolation threshold, ∼70%, the plasmon of the nanostructure transits from red to blue shifts with respect to that of the unshelled Au nanorod. This plasmonic percolation behavior is also confirmed by the scattering measurements on the individual core-shell nanostructures. Quasistatic theory and numerical simulations show that the plasmonic percolation originates from a positive-to-negative transition in the real part of the dielectric function of the shell as the Pd volume fraction is increased. The observed plasmonic percolation is found to be independent of the metal type in the shell. Moreover, compared to the unshelled Au nanorods with similar plasmon wavelengths, the Au nanorod core-Pd shell nanostructures exhibit larger refractive index sensitivities, which is ascribed to the expulsion of the electric field intensity from the Au nanorod core by the adsorbed Pd nanoparticles. © 2012 American Chemical Society.

Integral equation hierarchy for continuum percolation

International Nuclear Information System (INIS)

Given, J.A.

1988-01-01

In this thesis a projection operator technique is presented that yields hierarchies of integral equations satisfied exactly by the n-point connectedness functions in a continuum version of the site-bond percolation problem. The n-point connectedness functions carry the same structural information for a percolation problem as then-point correlation functions do for a thermal problem. This method extends the Potts model mapping of Fortuin and Kastelyn to the continuum by exploiting an s-state generalization of the Widom-Rowlinson model, a continuum model for phase separation. The projection operator technique is used to produce an integral equation hierarchy for percolation similar to the Born-Green heirarchy. The Kirkwood superposition approximation (SA) is extended to percolation in order to close this hierarchy and yield a nonlinear integral equation for the two-point connectedness function. The fact that this function, in the SA, is the analytic continuation to negative density of the two-point correlation function in a corresponding thermal problem is discussed. The BGY equation for percolation is solved numerically, both by an expansion in powers of the density, and by an iterative technique due to Kirkwood. It is argued both analytically and numerically, that the BYG equation for percolation, unlike its thermal counterpart, shows non-classical critical behavior, with η = 1 and γ = 0.05 ± .1. Finally a sequence of refinements to the superposition approximations based in the theory of fluids by Rice and Lekner is discussed

Percolation Theory and Modern Hydraulic Fracturing

Science.gov (United States)

Norris, J. Q.; Turcotte, D. L.; Rundle, J. B.

2015-12-01

During the past few years, we have been developing a percolation model for fracking. This model provides a powerful tool for understanding the growth and properties of the complex fracture networks generated during a modern high volume hydraulic fracture stimulations of tight shale reservoirs. The model can also be used to understand the interaction between the growing fracture network and natural reservoir features such as joint sets and faults. Additionally, the model produces a power-law distribution of bursts which can easily be compared to observed microseismicity.

Dynamics of bootstrap percolation

Indian Academy of Sciences (India)

precise criterion for the occurrence of a mixed transition is not very clear, and has been the subject ... ology, electronic communication, and social networks. It has also acquired a ... percolation theory is to start with a lattice with a fraction p of its sites occupied randomly, and ..... samples of a 104-node network. Probability is ...

Percolation effects in supercapacitors with thin, transparent carbon nanotube electrodes.

Science.gov (United States)

King, Paul J; Higgins, Thomas M; De, Sukanta; Nicoloso, Norbert; Coleman, Jonathan N

2012-02-28

We have explored the effects of percolation on the properties of supercapacitors with thin nanotube networks as electrodes. We find the equivalent series resistance, R(ESR), and volumetric capacitance, C(V), to be thickness independent for relatively thick electrodes. However, once the electrode thickness falls below a threshold thickness (∼100 nm for R(ESR) and ∼20 nm for C(V)), the properties of the electrode become thickness dependent. We show the thickness dependence of both R(ESR) and C(V) to be consistent with percolation theory. While this is expected for R(ESR), that the capacitance follows a percolation scaling law is not. This occurs because, for sparse networks, the capacitance is proportional to the fraction of nanotubes connected to the main network. This fraction, in turn, follows a percolation scaling law. This allows us to understand and quantify the limitations on the achievable capacitance for transparent supercapacitors. We find that supercapacitors with thickness independent R(ESR) and C(V) occupy a well-defined region of the Ragone plot. However, supercapacitors whose electrodes are limited by percolation occupy a long tail to lower values of energy and power density. For example, replacing electrodes with transparency of T = 80% with thinner networks displaying T = 97% will result in a 20-fold reduction of both power and energy density.

The internal percolation problem

International Nuclear Information System (INIS)

Bezsudnov, I.V.; Snarskii, A.A.

2010-01-01

The internal percolation problem (IP) as a new type of the percolation problem is introduced and investigated. In spite of the usual (or external) percolation problem (EP) when the percolation current flows from the top to the bottom of the system, in IP case the voltage is applied through bars which are present in the hole located within the system. The EP problem has two major parameters: M-size of the system and a 0 -size of inclusions, bond size, etc. The IP problem holds one parameter more: size of the hole L. Numerical simulation shows that the critical indexes of conductance for the IP problem are very close to those in the EP problem. On the contrary, the indexes of the relative spectral noise density of 1/f noise and higher moments differ from those in the EP problem. The basics of these facts is discussed.

Social percolation and the influence of mass media

Science.gov (United States)

Proykova, Ana; Stauffer, Dietrich

2002-09-01

In the marketing model of Solomon and Weisbuch, people buy a product only if their neighbours tell them of its quality, and if this quality is higher than their own quality expectations. Now we introduce additional information from the mass media, which is analogous to the ghost field in percolation theory. The mass media shift the percolative phase transition observed in the model, and decrease the time after which the stationary state is reached.

Marketing percolation

Science.gov (United States)

Goldenberg, J.; Libai, B.; Solomon, S.; Jan, N.; Stauffer, D.

2000-09-01

A percolation model is presented, with computer simulations for illustrations, to show how the sales of a new product may penetrate the consumer market. We review the traditional approach in the marketing literature, which is based on differential or difference equations similar to the logistic equation (Bass, Manage. Sci. 15 (1969) 215). This mean-field approach is contrasted with the discrete percolation on a lattice, with simulations of "social percolation" (Solomon et al., Physica A 277 (2000) 239) in two to five dimensions giving power laws instead of exponential growth, and strong fluctuations right at the percolation threshold.

Use of Invasion Percolation Models To Study the Secondary Migration of Oil and Related Problems

Energy Technology Data Exchange (ETDEWEB)

Wagner, G.

1997-09-01

In oil reservoir engineering, multi-phase displacement processes are important. This doctoral thesis describes simulations of the slow displacement of a wetting fluid by a non-wetting fluid in a complex, random porous medium and in a single fracture. The study is restricted to two-phase flow in the quasi-static limit in which viscous forces can be neglected. The secondary migration of oil takes place in this regime, however, the discussion is broader in scope. The thesis connects the problem of slow two-phase flow to percolation theory and discusses the mechanisms that control immiscible displacements. A new, modified version of the invasion percolation model is used to simulate an imbibition process in a porous medium and the migration of a cluster of non-wetting fluid through a porous medium saturated with a wetting fluid. The simulations include the secondary migration of oil through porous homogeneous rock. Fluid migration through heterogeneous porous media is simulated qualitatively. Slow displacement of a wetting fluid by a non-wetting fluid in a single rock fracture is simulated by using the standard invasion percolation model. Experiments and simulations are performed to study the fragmentation of invasion percolation-like structures of non-wetting fluid in a porous medium saturated with a wetting fluid. A scenario is studied in which a cluster of non-wettable fluid migrates through a porous medium that is saturated with a wetting fluid, the migration being driven by continuously increasing buoyancy forces. There is a simulation of the secondary migration of oil in both two- and three-dimensional media. 361 refs., 115 figs.

Percolation systems away from the critical point

Indian Academy of Sciences (India)

DEEPAK DHAR. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India ... There is more to percolation theory than the critical exponents. Of course, an experi- .... simple qualitative arguments. In the summation ...

Fluid leakage near the percolation threshold

Science.gov (United States)

Dapp, Wolf B.; Müser, Martin H.

2016-02-01

Percolation is a concept widely used in many fields of research and refers to the propagation of substances through porous media (e.g., coffee filtering), or the behaviour of complex networks (e.g., spreading of diseases). Percolation theory asserts that most percolative processes are universal, that is, the emergent powerlaws only depend on the general, statistical features of the macroscopic system, but not on specific details of the random realisation. In contrast, our computer simulations of the leakage through a seal—applying common assumptions of elasticity, contact mechanics, and fluid dynamics—show that the critical behaviour (how the flow ceases near the sealing point) solely depends on the microscopic details of the last constriction. It appears fundamentally impossible to accurately predict from statistical properties of the surfaces alone how strongly we have to tighten a water tap to make it stop dripping and also how it starts dripping once we loosen it again.

Using a dynamic point-source percolation model to simulate bubble growth

International Nuclear Information System (INIS)

Zimmerman, Jonathan A.; Zeigler, David A.; Cowgill, Donald F.

2004-01-01

Accurate modeling of nucleation, growth and clustering of helium bubbles within metal tritide alloys is of high scientific and technological importance. Of interest is the ability to predict both the distribution of these bubbles and the manner in which these bubbles interact at a critical concentration of helium-to-metal atoms to produce an accelerated release of helium gas. One technique that has been used in the past to model these materials, and again revisited in this research, is percolation theory. Previous efforts have used classical percolation theory to qualitatively and quantitatively model the behavior of interstitial helium atoms in a metal tritide lattice; however, higher fidelity models are needed to predict the distribution of helium bubbles and include features that capture the underlying physical mechanisms present in these materials. In this work, we enhance classical percolation theory by developing the dynamic point-source percolation model. This model alters the traditionally binary character of site occupation probabilities by enabling them to vary depending on proximity to existing occupied sites, i.e. nucleated bubbles. This revised model produces characteristics for one and two dimensional systems that are extremely comparable with measurements from three dimensional physical samples. Future directions for continued development of the dynamic model are also outlined

Percolation analysis for cosmic web with discrete points

Science.gov (United States)

Zhang, Jiajun; Cheng, Dalong; Chu, Ming-Chung

2018-01-01

Percolation analysis has long been used to quantify the connectivity of the cosmic web. Most of the previous work is based on density fields on grids. By smoothing into fields, we lose information about galaxy properties like shape or luminosity. The lack of mathematical modeling also limits our understanding for the percolation analysis. To overcome these difficulties, we have studied percolation analysis based on discrete points. Using a friends-of-friends (FoF) algorithm, we generate the S -b b relation, between the fractional mass of the largest connected group (S ) and the FoF linking length (b b ). We propose a new model, the probability cloud cluster expansion theory to relate the S -b b relation with correlation functions. We show that the S -b b relation reflects a combination of all orders of correlation functions. Using N-body simulation, we find that the S -b b relation is robust against redshift distortion and incompleteness in observation. From the Bolshoi simulation, with halo abundance matching (HAM), we have generated a mock galaxy catalog. Good matching of the projected two-point correlation function with observation is confirmed. However, comparing the mock catalog with the latest galaxy catalog from Sloan Digital Sky Survey (SDSS) Data Release (DR)12, we have found significant differences in their S -b b relations. This indicates that the mock galaxy catalog cannot accurately retain higher-order correlation functions than the two-point correlation function, which reveals the limit of the HAM method. As a new measurement, the S -b b relation is applicable to a wide range of data types, fast to compute, and robust against redshift distortion and incompleteness and contains information of all orders of correlation functions.

Percolation of interdependent network of networks

International Nuclear Information System (INIS)

Havlin, Shlomo; Stanley, H. Eugene; Bashan, Amir; Gao, Jianxi; Kenett, Dror Y.

2015-01-01

Complex networks appear in almost every aspect of science and technology. Previous work in network theory has focused primarily on analyzing single networks that do not interact with other networks, despite the fact that many real-world networks interact with and depend on each other. Very recently an analytical framework for studying the percolation properties of interacting networks has been introduced. Here we review the analytical framework and the results for percolation laws for a Network Of Networks (NONs) formed by n interdependent random networks. The percolation properties of a network of networks differ greatly from those of single isolated networks. In particular, because the constituent networks of a NON are connected by node dependencies, a NON is subject to cascading failure. When there is strong interdependent coupling between networks, the percolation transition is discontinuous (first-order) phase transition, unlike the well-known continuous second-order transition in single isolated networks. Moreover, although networks with broader degree distributions, e.g., scale-free networks, are more robust when analyzed as single networks, they become more vulnerable in a NON. We also review the effect of space embedding on network vulnerability. It is shown that for spatially embedded networks any finite fraction of dependency nodes will lead to abrupt transition

Percolation and epidemics in random clustered networks

Science.gov (United States)

Miller, Joel C.

2009-08-01

The social networks that infectious diseases spread along are typically clustered. Because of the close relation between percolation and epidemic spread, the behavior of percolation in such networks gives insight into infectious disease dynamics. A number of authors have studied percolation or epidemics in clustered networks, but the networks often contain preferential contacts in high degree nodes. We introduce a class of random clustered networks and a class of random unclustered networks with the same preferential mixing. Percolation in the clustered networks reduces the component sizes and increases the epidemic threshold compared to the unclustered networks.

Anisotropic Percolation Analysis of Discharge

Science.gov (United States)

Matsumoto, Shogo; Odagaki, Takashi

2014-03-01

Exploiting a nonlinear resistor network on a square lattice in two dimensions, we investigate discharge when two opposite sides of the lattice are subjected to a constant voltage difference. Each site is ionized randomly with a probability in proportion to the square of the strength of the electric field, and the resistivity between two ionized sites is assumed to be 10-6 times smaller than the original resistivity. Using Monte Carlo simulation, we obtain the current and distribution of clusters of ionized sites as functions of the fraction of ionized sites. It is found that a wall of potential drop is formed as the fraction approaches a critical value, which is followed by discharge. The critical value is much smaller than the critical percolation probability of the standard site percolation on the square lattice. We also find that a singular behavior of the cluster distribution is expected at a critical fraction differently from that for the current, and that the critical exponents characterizing the cluster distribution satisfy the scaling relation known for two-dimensional percolation, while the critical exponent of the percolation probability is close to the value reported for a directed percolation.

Logarithmic corrections to scaling in critical percolation and random resistor networks.

Science.gov (United States)

Stenull, Olaf; Janssen, Hans-Karl

2003-09-01

We study the critical behavior of various geometrical and transport properties of percolation in six dimensions. By employing field theory and renormalization group methods we analyze fluctuation induced logarithmic corrections to scaling up to and including the next-to-leading order correction. Our study comprehends the percolation correlation function, i.e., the probability that two given points are connected, and some of the fractal masses describing percolation clusters. To be specific, we calculate the mass of the backbone, the red bonds, and the shortest path. Moreover, we study key transport properties of percolation as represented by the random resistor network. We investigate the average two-point resistance as well as the entire family of multifractal moments of the current distribution.

Rubber elasticity for percolation network consisting of Gaussian chains

Energy Technology Data Exchange (ETDEWEB)

Nishi, Kengo, E-mail: kengo.nishi@phys.uni-goettingen.de, E-mail: sakai@tetrapod.t.u-tokyo.ac.jp, E-mail: sibayama@issp.u-tokyo.ac.jp; Noguchi, Hiroshi; Shibayama, Mitsuhiro, E-mail: kengo.nishi@phys.uni-goettingen.de, E-mail: sakai@tetrapod.t.u-tokyo.ac.jp, E-mail: sibayama@issp.u-tokyo.ac.jp [Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Sakai, Takamasa, E-mail: kengo.nishi@phys.uni-goettingen.de, E-mail: sakai@tetrapod.t.u-tokyo.ac.jp, E-mail: sibayama@issp.u-tokyo.ac.jp [Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2015-11-14

A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G{sub 0}, must be equal to G/G{sub 0} = (p − 2/f)/(1 − 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels.

Rubber elasticity for percolation network consisting of Gaussian chains

International Nuclear Information System (INIS)

Nishi, Kengo; Noguchi, Hiroshi; Shibayama, Mitsuhiro; Sakai, Takamasa

2015-01-01

A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G 0 , must be equal to G/G 0 = (p − 2/f)/(1 − 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels

Connectivity percolation in suspensions of attractive square-well spherocylinders.

Science.gov (United States)

Dixit, Mohit; Meyer, Hugues; Schilling, Tanja

2016-01-01

We have studied the connectivity percolation transition in suspensions of attractive square-well spherocylinders by means of Monte Carlo simulation and connectedness percolation theory. In the 1980s the percolation threshold of slender fibers has been predicted to scale as the fibers' inverse aspect ratio [Phys. Rev. B 30, 3933 (1984)PRBMDO1098-012110.1103/PhysRevB.30.3933]. The main finding of our study is that the attractive spherocylinder system reaches this inverse scaling regime at much lower aspect ratios than found in suspensions of hard spherocylinders. We explain this difference by showing that third virial corrections of the pair connectedness functions, which are responsible for the deviation from the scaling regime, are less important for attractive potentials than for hard particles.

Percolation approach for atomic and molecular cluster formation

International Nuclear Information System (INIS)

Knospe, O.; Seifert, G.

1987-12-01

We apply a percolation approach for the theoretical analysis of mass spectra of molecular microclusters obtained by adiabatic expansion technique. The evolution of the shape of the experimental size distributions as function of stagnation pressure and stagnation temperature are theoretically reproduced by varying the percolation parameter. Remaining discrepancies between theory and experiment are discussed. In addition, the even-odd alternation as well as the 'magic' shell structure within metallic, secondary ion mass spectra are investigated by introducing statistical weights for the cluster formation probabilities. Shell correction energies of atomic clusters as function of cluster-size are deduced from the experimental data. (orig.)

Percolation under noise: Detecting explosive percolation using the second-largest component

Science.gov (United States)

Viles, Wes; Ginestet, Cedric E.; Tang, Ariana; Kramer, Mark A.; Kolaczyk, Eric D.

2016-05-01

We consider the problem of distinguishing between different rates of percolation under noise. A statistical model of percolation is constructed allowing for the birth and death of edges as well as the presence of noise in the observations. This graph-valued stochastic process is composed of a latent and an observed nonstationary process, where the observed graph process is corrupted by type-I and type-II errors. This produces a hidden Markov graph model. We show that for certain choices of parameters controlling the noise, the classical (Erdős-Rényi) percolation is visually indistinguishable from a more rapid form of percolation. In this setting, we compare two different criteria for discriminating between these two percolation models, based on the interquartile range (IQR) of the first component's size, and on the maximal size of the second-largest component. We show through data simulations that this second criterion outperforms the IQR of the first component's size, in terms of discriminatory power. The maximal size of the second component therefore provides a useful statistic for distinguishing between different rates of percolation, under physically motivated conditions for the birth and death of edges, and under noise. The potential application of the proposed criteria for the detection of clinically relevant percolation in the context of applied neuroscience is also discussed.

Percolation temperature and the 'instability' of the effective potential

International Nuclear Information System (INIS)

Carvalho, C.A. de; Bazeia Filho, D.; Eboli, O.J.P.; Marques, G.C.; Silva, A.J. da; Ventura, I.

1984-01-01

It is shown that in spontaneously broken lambda phi 4 theory the percolation temperature coincides with the temperature at which the semiclassical (loop) expansion of the effective potential (free energy) of the system around a uniform field configuration fails. This allows us to extract the percolation temperature directly from the effective potential. The addition of fermions or gauge fields does not alter the result as long as they are weakly coupled to the scalars. The coincidence holds in the high temperature limit at every order in the loop expansion. (Author) [pt

Computer simulation of current percolation in polycrystalline high-temperature superconductors

Energy Technology Data Exchange (ETDEWEB)

Zeimetz, B [Department of Materials Science and Interdisciplinary Research Centre in Superconductivity, Cambridge University, Pembroke Street, Cambridge (United Kingdom); Rutter, N A; Glowacki, B A; Evetts, J E [Department of Materials Science and Interdisciplinary Research Centre in Superconductivity, Cambridge University, Pembroke Street, Cambridge (United Kingdom)

2001-09-01

YBCO-coated conductors were modelled in a computer simulation using a resistor network concept, with the resistors representing the grain boundaries. Dissipation above the critical current, accompanied by flux penetration into the grain boundaries, was described by a linear (flux-flow) resistivity. The model allowed calculation of the combined percolation of current and magnetic flux. Current-voltage data showed scaling in agreement with percolation theory for two-dimensional systems. The influence of grain alignment and electromagnetic parameters on conductor performance was investigated. (author)

Density of phonon-fracton states of disordered solids in the vicinity of percolation phase transitions

International Nuclear Information System (INIS)

Korzhenevskii, A.L.; Luzhkov, A.A.

1991-01-01

The development of a theory of phase transitions in disordered materials is still one of the central problems in solid-state physics. The model of a percolation phase transition plays the same role among the models put forward to account for phase transitions in disordered media as does the Ising model for second-order phase transitions in ideal crystals. In addition to the clear picture of the processes occurring in the course of a percolation phase transition, a scaling theory has been developed and various techniques have been used to calculate the critical exponents describing the thermodynamics of a medium in the vicinity of the percolation threshold. The authors adopt a field-theoretic approach in a study of acoustic properties of disordered solids undergoing percolation phase transitions characterized by h ∼ 1. Among these transitions they concentrate on the case with the simplest type of striction interaction when the solution of a stochastic vector differential equation of motion describing the behavior of an elastic medium in the critical region can be reduced to a scalar equation. The results of their calculations by the field renormalization group method confirmed the existence of the scaling relationships between the critical exponents and also the conclusion on the nature of short- and long-wavelength vibrations near the percolation threshold, which follow from phenomenological considerations of the scaling theory. The values of the upper critical dimensionality and of the critical exponents of the problem are shown to differ from the values applicable to percolation phase transitions characterized by h much-lt 1

Percolation, statistical topography, and transport in random media

International Nuclear Information System (INIS)

Isichenko, M.B.

1992-01-01

A review of classical percolation theory is presented, with an emphasis on novel applications to statistical topography, turbulent diffusion, and heterogeneous media. Statistical topography involves the geometrical properties of the isosets (contour lines or surfaces) of a random potential ψ(x). For rapidly decaying correlations of ψ, the isopotentials fall into the same universality class as the perimeters of percolation clusters. The topography of long-range correlated potentials involves many length scales and is associated either with the correlated percolation problem or with Mandelbrot's fractional Brownian reliefs. In all cases, the concept of fractal dimension is particularly fruitful in characterizing the geometry of random fields. The physical applications of statistical topography include diffusion in random velocity fields, heat and particle transport in turbulent plasmas, quantum Hall effect, magnetoresistance in inhomogeneous conductors with the classical Hall effect, and many others where random isopotentials are relevant. A geometrical approach to studying transport in random media, which captures essential qualitative features of the described phenomena, is advocated

Controlling electrical percolation in multicomponent carbon nanotube dispersions.

Science.gov (United States)

Kyrylyuk, Andriy V; Hermant, Marie Claire; Schilling, Tanja; Klumperman, Bert; Koning, Cor E; van der Schoot, Paul

2011-04-10

Carbon nanotube reinforced polymeric composites can have favourable electrical properties, which make them useful for applications such as flat-panel displays and photovoltaic devices. However, using aqueous dispersions to fabricate composites with specific physical properties requires that the processing of the nanotube dispersion be understood and controlled while in the liquid phase. Here, using a combination of experiment and theory, we study the electrical percolation of carbon nanotubes introduced into a polymer matrix, and show that the percolation threshold can be substantially lowered by adding small quantities of a conductive polymer latex. Mixing colloidal particles of different sizes and shapes (in this case, spherical latex particles and rod-like nanotubes) introduces competing length scales that can strongly influence the formation of the system-spanning networks that are needed to produce electrically conductive composites. Interplay between the different species in the dispersions leads to synergetic or antagonistic percolation, depending on the ease of charge transport between the various conductive components.

Percolative ionic conduction in the LiAlSiO4 glass-ceramic system

International Nuclear Information System (INIS)

Biefeld, R.M.; Pike, G.E.; Johnson, R.T. Jr.

1977-01-01

The effect f crystallinity on the lithium ion conductivity in LiAlSiO 4 glass and glass-ceramic solid electrolytes has been determined. The ionic conductivity is thermally activated with an activation energy and pre-exponential factor that change in a marked and nonsimple manner as the volume fraction of crystallinity changes. These results are explained by using a continuum percolation model (effective-medium approximation) which assumes that ionic conduction in the glass-ceramic is almost entirely within the glass phase until the crystalline volume fraction rises above approx. 55%. The LiAlSiO 4 system would seem to be nearly ideal for application of percolation theory since the crystalline phase, β eucryptite, has nearly the same composition as the glass phase. Hence, as the crystallite volume fraction increases in the glass ceramic, the residual glass composition and conductivity remain the same. This is the first application of percolation theory to ionic transport in glass-ceramics and excellent agreement is obtained between theory and experiment for the LiAlSiO 4 system

Percolation transition in carbon composite on the basis of fullerenes and exfoliated graphite

Science.gov (United States)

Berezkin, V. I.; Popov, V. V.

2018-01-01

The electrical conductivity of a carbon composite on the basis of C60 fullerenes and exfoliated graphite is investigated in the range of relative contents of components from 0 to 100%. The samples are obtained by the thermal treatment of the initial dispersed mixtures in vacuum in the diffusion-adsorption process and their further cold pressing. The resistivity of the samples gradually increases with an increase in the fraction of fullerenes, and a sharp transition from the conductive state to the dielectric one is observed after achieving certain concentrations of C60. The interpretation of the results within the percolation theory makes it possible to evaluate the percolation threshold (expressed as a relative content of graphite) as equal to 4.45 wt % and the critical conductivity index as equal to 1.85 (which is typical for three-dimensional twocomponent disordered media including those having pores).

The abundance threshold for plague as a critical percolation phenomenon

DEFF Research Database (Denmark)

Davis, S; Trapman, P; Leirs, H

2008-01-01

. However, no natural examples have been reported. The central question of interest in percolation theory 4 , the possibility of an infinite connected cluster, corresponds in infectious disease to a positive probability of an epidemic. Archived records of plague (infection with Yersinia pestis....... Abundance thresholds are the theoretical basis for attempts to manage infectious disease by reducing the abundance of susceptibles, including vaccination and the culling of wildlife 6, 7, 8 . This first natural example of a percolation threshold in a disease system invites a re-appraisal of other invasion...

Percolation Model for the Existence of a Mitochondrial Eve

CERN Document Server

Neves, A G M

2005-01-01

We look at the process of inheritance of mitochondrial DNA as a percolation model on trees equivalent to the Galton-Watson process. The model is exactly solvable for its percolation threshold $p_c$ and percolation probability critical exponent. In the approximation of small percolation probability, and assuming limited progeny number, we are also able to find the maximum and minimum percolation probabilities over all probability distributions for the progeny number constrained to a given $p_c$. As a consequence, we can relate existence of a mitochondrial Eve to quantitative knowledge about demographic evolution of early mankind. In particular, we show that a mitochondrial Eve may exist even in an exponentially growing population, provided that the average number of children per individual is constrained to a small range depending on the probability $p$ that a newborn child is a female.

Group percolation in interdependent networks

Science.gov (United States)

Wang, Zexun; Zhou, Dong; Hu, Yanqing

2018-03-01

In many real network systems, nodes usually cooperate with each other and form groups to enhance their robustness to risks. This motivates us to study an alternative type of percolation, group percolation, in interdependent networks under attack. In this model, nodes belonging to the same group survive or fail together. We develop a theoretical framework for this group percolation and find that the formation of groups can improve the resilience of interdependent networks significantly. However, the percolation transition is always of first order, regardless of the distribution of group sizes. As an application, we map the interdependent networks with intersimilarity structures, which have attracted much attention recently, onto the group percolation and confirm the nonexistence of continuous phase transitions.

PERCOLATION TRANSITION AND TOPOLOGY

Directory of Open Access Journals (Sweden)

Patricia Jouannot-Chesney

2017-06-01

Full Text Available A number of bidimensional random structures with increasing densities are simulated to explore possible links between Euler-Poincaré characteristic (EPC, or connectivity, and percolation threshold. For each structure model, the percolation threshold is compared with a number of typical points (extrema, zero crossings... of the EPC curve. From these exercises, it can be concluded that the percolation threshold cannot be generally predicted using the evolution of the EPC.

Non-criticality of interaction network over system's crises: A percolation analysis.

Science.gov (United States)

Shirazi, Amir Hossein; Saberi, Abbas Ali; Hosseiny, Ali; Amirzadeh, Ehsan; Toranj Simin, Pourya

2017-11-20

Extraction of interaction networks from multi-variate time-series is one of the topics of broad interest in complex systems. Although this method has a wide range of applications, most of the previous analyses have focused on the pairwise relations. Here we establish the potential of such a method to elicit aggregated behavior of the system by making a connection with the concepts from percolation theory. We study the dynamical interaction networks of a financial market extracted from the correlation network of indices, and build a weighted network. In correspondence with the percolation model, we find that away from financial crises the interaction network behaves like a critical random network of Erdős-Rényi, while close to a financial crisis, our model deviates from the critical random network and behaves differently at different size scales. We perform further analysis to clarify that our observation is not a simple consequence of the growth in correlations over the crises.

Percolation Systems away from the Critical Point

OpenAIRE

Dhar, Deepak

2001-01-01

This article reviews some effects of disorder in percolation systems even away from the critical density p_c. For densities below p_c, the statistics of large clusters defines the animals problem. Its relation to the directed animals problem and the Lee-Yang edge singularity problem is described. Rare compact clusters give rise to Griffiths singuraties in the free energy of diluted ferromagnets, and lead to a very slow relaxation of magnetization. In biassed diffusion on percolation clusters,...

Target-Searching on Percolation

International Nuclear Information System (INIS)

Yang Shijie

2005-01-01

We study target-searching processes on a percolation, on which a hunter tracks a target by smelling odors it emits. The odor intensity is supposed to be inversely proportional to the distance it propagates. The Monte Carlo simulation is performed on a 2-dimensional bond-percolation above the threshold. Having no idea of the location of the target, the hunter determines its moves only by random attempts in each direction. For lager percolation connectivity p ∼> 0.90, it reveals a scaling law for the searching time versus the distance to the position of the target. The scaling exponent is dependent on the sensitivity of the hunter. For smaller p, the scaling law is broken and the probability of finding out the target significantly reduces. The hunter seems trapped in the cluster of the percolation and can hardly reach the goal.

Percolation technique for galaxy clustering

Science.gov (United States)

Klypin, Anatoly; Shandarin, Sergei F.

1993-01-01

We study percolation in mass and galaxy distributions obtained in 3D simulations of the CDM, C + HDM, and the power law (n = -1) models in the Omega = 1 universe. Percolation statistics is used here as a quantitative measure of the degree to which a mass or galaxy distribution is of a filamentary or cellular type. The very fast code used calculates the statistics of clusters along with the direct detection of percolation. We found that the two parameters mu(infinity), characterizing the size of the largest cluster, and mu-squared, characterizing the weighted mean size of all clusters excluding the largest one, are extremely useful for evaluating the percolation threshold. An advantage of using these parameters is their low sensitivity to boundary effects. We show that both the CDM and the C + HDM models are extremely filamentary both in mass and galaxy distribution. The percolation thresholds for the mass distributions are determined.

Disorder-induced quantum bond percolation

International Nuclear Information System (INIS)

Nishino, Shinya; Katsuno, Shuji; Goda, Masaki

2009-01-01

We investigate the effects of off-diagonal disorder on localization properties in quantum bond percolation networks on cubic lattices, motivated by the finding that the off-diagonal disorder does not always enhance the quantum localization of wavefunctions. We numerically construct a diagram of the 'percolation threshold', distinguishing extended states from localized states as a function of two degrees of disorder, by using the level statistics and finite-size scaling. The percolation threshold increases in a characteristic way on increasing the disorder in the connected bonds, while it gradually decreases on increasing the disorder in the disconnected bonds. Furthermore, the exchange of connected and disconnected bonds induced by the disorder causes a dramatic change of the percolation threshold.

Reversible first-order transition in Pauli percolation

Science.gov (United States)

Maksymenko, Mykola; Moessner, Roderich; Shtengel, Kirill

2015-06-01

Percolation plays an important role in fields and phenomena as diverse as the study of social networks, the dynamics of epidemics, the robustness of electricity grids, conduction in disordered media, and geometric properties in statistical physics. We analyze a new percolation problem in which the first-order nature of an equilibrium percolation transition can be established analytically and verified numerically. The rules for this site percolation model are physical and very simple, requiring only the introduction of a weight W (n )=n +1 for a cluster of size n . This establishes that a discontinuous percolation transition can occur with qualitatively more local interactions than in all currently considered examples of explosive percolation; and that, unlike these, it can be reversible. This greatly extends both the applicability of such percolation models in principle and their reach in practice.

Dimensional crossover in directed percolation

International Nuclear Information System (INIS)

Chame, A.M.N.; Queiroz, S.L.A. de; Santos, Raimundo R. dos.

1984-04-01

We study the dimensional crossover in directed percolation in three dimensions. Bonds are allowed to have different concentrations along the three cartesian axes of the lattice. Through a Position Space Renormalization Group we obtain the phase-diagrama where non-percolating, 1-D, 2-D and 3-D percolating phases are present. We find that the isotropic fixed points are unstable with respect to anisotropy, thus driving the system into a different universality class. (author) [pt

Percolation transport theory and relevance to soil formation, vegetation growth, and productivity

Science.gov (United States)

Hunt, A. G.; Ghanbarian, B.

2016-12-01

Scaling laws of percolation theory have been applied to generate the time dependence of vegetation growth rates (both intensively managed and natural) and soil formation rates. The soil depth is thus equal to the solute vertical transport distance, the soil production function, chemical weathering rates, and C and N storage rates are all given by the time derivative of the soil depth. Approximate numerical coefficients based on the maximum flow rates in soils have been proposed, leading to a broad understanding of such processes. What is now required is an accurate understanding of the variability of the coefficients in the scaling relationships. The present abstract focuses on the scaling relationship for solute transport and soil formation. A soil formation rate relates length, x, and time, t, scales, meaning that the missing coefficient must include information about fundamental space and time scales, x0 and t0. x0 is proposed to be a fundamental mineral heterogeneity scale, i.e. a median particle diameter. to is then found from the ratio of x0 and a fundamental flow rate, v0, which is identified with the net infiltration rate. The net infiltration rate is equal to precipitation P less evapotranspiration, ET, plus run-on less run-off. Using this hypothesis, it is possible to predict soil depths and formation rates as functions of time and P - ET, and the formation rate as a function of depth, soil calcic and gypsic horizon depths as functions of P-ET. It is also possible to determine when soils are in equilibrium, and predict relationships of erosion rates and soil formation rates.

Cities and regions in Britain through hierarchical percolation

Science.gov (United States)

Arcaute, Elsa; Molinero, Carlos; Hatna, Erez; Murcio, Roberto; Vargas-Ruiz, Camilo; Masucci, A. Paolo; Batty, Michael

2016-04-01

Urban systems present hierarchical structures at many different scales. These are observed as administrative regional delimitations which are the outcome of complex geographical, political and historical processes which leave almost indelible footprints on infrastructure such as the street network. In this work, we uncover a set of hierarchies in Britain at different scales using percolation theory on the street network and on its intersections which are the primary points of interaction and urban agglomeration. At the larger scales, the observed hierarchical structures can be interpreted as regional fractures of Britain, observed in various forms, from natural boundaries, such as National Parks, to regional divisions based on social class and wealth such as the well-known North-South divide. At smaller scales, cities are generated through recursive percolations on each of the emerging regional clusters. We examine the evolution of the morphology of the system as a whole, by measuring the fractal dimension of the clusters at each distance threshold in the percolation. We observe that this reaches a maximum plateau at a specific distance. The clusters defined at this distance threshold are in excellent correspondence with the boundaries of cities recovered from satellite images, and from previous methods using population density.

Percolation effect in thick film superconductors

Energy Technology Data Exchange (ETDEWEB)

Sali, R.; Harsanyi, G. [Technical Univ. of Budapest (Hungary)

1994-12-31

A thick film superconductor paste has been developed to study the properties of granulated superconductor materials, to observe the percolation effect and to confirm the theory of the conducting mechanism in the superconducting thick films. This paste was also applied to make a superconducting planar transformer. Due to high T{sub c} and advantageous current density properties the base of the paste was chosen to be of Bi(Pb)SrCaCuO system. For contacts a conventional Ag/Pt paste was used. The critical temperature of the samples were between 110 K and 115 K depending on the printed layer thickness. The critical current density at the boiling temperature of the liquid He- was between 200-300 A/cm{sup 2}. The R(T) and V(I) functions were measured with different parameters. The results of the measurements have confirmed the theory of conducting mechanism in the material. The percolation structure model has been built and described. As an application, a superconducting planar thick film transformer was planned and produced. Ten windings of the transformer were printed on one side of the alumina substrate and one winding was printed on the other side. The coupling between the two sides was possible through the substrate. The samples did not need special drying and firing parameters. After the preparation, the properties of the transformer were measured. The efficiency and the losses were determined. Finally, some fundamental advantages and problems of the process were discussed.

Percolation effect in thick film superconductors

International Nuclear Information System (INIS)

Sali, R.; Harsanyi, G.

1994-01-01

A thick film superconductor paste has been developed to study the properties of granulated superconductor materials, to observe the percolation effect and to confirm the theory of the conducting mechanism in the superconducting thick films. This paste was also applied to make a superconducting planar transformer. Due to high T c and advantageous current density properties the base of the paste was chosen to be of Bi(Pb)SrCaCuO system. For contacts a conventional Ag/Pt paste was used. The critical temperature of the samples were between 110 K and 115 K depending on the printed layer thickness. The critical current density at the boiling temperature of the liquid He- was between 200-300 A/cm 2 . The R(T) and V(I) functions were measured with different parameters. The results of the measurements have confirmed the theory of conducting mechanism in the material. The percolation structure model has been built and described. As an application, a superconducting planar thick film transformer was planned and produced. Ten windings of the transformer were printed on one side of the alumina substrate and one winding was printed on the other side. The coupling between the two sides was possible through the substrate. The samples did not need special drying and firing parameters. After the preparation, the properties of the transformer were measured. The efficiency and the losses were determined. Finally, some fundamental advantages and problems of the process were discussed

Percolator: Scalable Pattern Discovery in Dynamic Graphs

Energy Technology Data Exchange (ETDEWEB)

Choudhury, Sutanay; Purohit, Sumit; Lin, Peng; Wu, Yinghui; Holder, Lawrence B.; Agarwal, Khushbu

2018-02-06

We demonstrate Percolator, a distributed system for graph pattern discovery in dynamic graphs. In contrast to conventional mining systems, Percolator advocates efficient pattern mining schemes that (1) support pattern detection with keywords; (2) integrate incremental and parallel pattern mining; and (3) support analytical queries such as trend analysis. The core idea of Percolator is to dynamically decide and verify a small fraction of patterns and their in- stances that must be inspected in response to buffered updates in dynamic graphs, with a total mining cost independent of graph size. We demonstrate a) the feasibility of incremental pattern mining by walking through each component of Percolator, b) the efficiency and scalability of Percolator over the sheer size of real-world dynamic graphs, and c) how the user-friendly GUI of Percolator inter- acts with users to support keyword-based queries that detect, browse and inspect trending patterns. We also demonstrate two user cases of Percolator, in social media trend analysis and academic collaboration analysis, respectively.

50 years of first-passage percolation

CERN Document Server

Auffinger, Antonio; Hanson, Jack

2017-01-01

First-passage percolation (FPP) is a fundamental model in probability theory that has a wide range of applications to other scientific areas (growth and infection in biology, optimization in computer science, disordered media in physics), as well as other areas of mathematics, including analysis and geometry. FPP was introduced in the 1960s as a random metric space. Although it is simple to define, and despite years of work by leading researchers, many of its central problems remain unsolved. In this book, the authors describe the main results of FPP, with two purposes in mind. First, they give self-contained proofs of seminal results obtained until the 1990s on limit shapes and geodesics. Second, they discuss recent perspectives and directions including (1) tools from metric geometry, (2) applications of concentration of measure, and (3) related growth and competition models. The authors also provide a collection of old and new open questions. This book is intended as a textbook for a graduate course or as a...

Electrical and percolative behavior of Sr2YSbO6-YBa2Cu3O7-δ composites

International Nuclear Information System (INIS)

Ortiz-Diaz, O.; Landinez Tellez, D.A.; Perez, F.; Tovar, H.; Roa-Rojas, J.

2007-01-01

We found that a mixture of materials Sr 2 YSbO 6 insulator with YBa 2 Cu 3 O 7-δ superconductor is a system where the particles of superconductor and insulator materials are found coexisting in a composite with two well-defined separate phases. Electrical transport properties and percolation behavior have been studied by electrical resistivity measurements at room temperature on several samples of composites with different vol.% of YBa 2 Cu 3 O 7-δ . Resistivity measurements agree with the equation which describes the conductivity in percolation theory. However, critical exponent t=6.65 is greater than universal value t∼2. Furthermore, there is a non-negligible conductivity below percolation threshold while it is expected to be zero in ideal percolative systems. Nevertheless, percolative behavior in this region was found and, critical exponent value s was determined to be s=0.75 in agreement with universal value

Percolation in Heterogeneous Media

International Nuclear Information System (INIS)

Vocka, Radim

1999-01-01

This work is a theoretical reflection on the problematic of the modeling of heterogeneous media, that is on the way of their simple representation conserving their characteristic features. Two particular problems are addressed in this thesis. Firstly, we study the transport in porous media, that is in a heterogeneous media which structure is quenched. A pore space is represented in a simple way - a pore is symbolized as a tube of a given length and a given diameter. The fact that the correlations in the distribution of pore sizes are taken into account by a construction of a hierarchical network makes possible the modeling of porous media with a porosity distributed over several length scales. The transport in the hierarchical network shows qualitatively different phenomena from those observed in simpler models. A comparison of numerical results with experimental data shows that the hierarchical network gives a good qualitative representation of the structure of real porous media. Secondly, we study a problem of the transport in a heterogeneous media which structure is evolving during the time. The models where the evolution of the structure is not influenced by the transport are studied in detail. These models present a phase transition of the same nature as that observed on the percolation networks. We propose a new theoretical description of this transition, and we express critical exponents describing the evolution of the conductivity as a function of fundamental exponents of percolation theory. (author) [fr

Monte Carlo simulations of electrical percolation in multicomponent thin films with nanofillers

Science.gov (United States)

Ni, Xiaojuan; Hui, Chao; Su, Ninghai; Jiang, Wei; Liu, Feng

2018-02-01

We developed a 2D disk-stick percolation model to investigate the electrical percolation behavior of an insulating thin film reinforced with 1D and 2D conductive nanofillers via Monte Carlo simulation. Numerical predictions of the percolation threshold in single component thin films showed good agreement with the previous published work, validating our model for investigating the characteristics of the percolation phenomena. Parametric studies of size effect, i.e., length of 1D nanofiller and diameter of 2D nanofiller, were carried out to predict the electrical percolation threshold for hybrid systems. The relationships between the nanofillers in two hybrid systems was established, which showed differences from previous linear assumption. The effective electrical conductance was evaluated through Kirchhoff’s current law by transforming it into a resistor network. The equivalent resistance was obtained from the distribution of nodal voltages by solving a system of linear equations with a Gaussian elimination method. We examined the effects of stick length, relative concentration, and contact patterns of 1D/2D inclusions on electrical performance. One novel aspect of our study is its ability to investigate the effective conductance of nanocomposites as a function of relative concentrations, which shows there is a synergistic effect when nanofillers with different dimensionalities combine properly. Our work provides an important theoretical basis for designing the conductive networks and predicting the percolation properties of multicomponent nanocomposites.

Signature of Thermal Rigidity Percolation

International Nuclear Information System (INIS)

Huerta, Adrián

2013-01-01

To explore the role that temperature and percolation of rigidity play in determining the macroscopic properties, we propose a model that adds translational degrees of freedom to the spins of the well known Ising hamiltonian. In particular, the Ising model illustrate the longstanding idea that the growth of correlations on approach to a critical point could be describable in terms of the percolation of some sort of p hysical cluster . For certain parameters of this model we observe two well defined peaks of C V , that suggest the existence of two kinds of p hysical percolation , namely connectivity and rigidity percolation. Thermal fluctuations give rise to two different kinds of elementary excitations, i.e. droplets and configuron, as suggested by Angell in the framework of a bond lattice model approach. The later is reflected in the fluctuations of redundant constraints that gives stability to the structure and correlate with the order parameter

Extreme value theory, Poisson-Dirichlet distributions, and first passage percolation on random networks

NARCIS (Netherlands)

Bhamidi, S.; Van der Hofstad, R.; Hooghiemstra, G.

2010-01-01

We study first passage percolation (FPP) on the configuration model (CM) having power-law degrees with exponent ? ? [1, 2) and exponential edge weights. We derive the distributional limit of the minimal weight of a path between typical vertices in the network and the number of edges on the

Elastic contact mechanics: percolation of the contact area and fluid squeeze-out.

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Persson, B N J; Prodanov, N; Krick, B A; Rodriguez, N; Mulakaluri, N; Sawyer, W G; Mangiagalli, P

2012-01-01

The dynamics of fluid flow at the interface between elastic solids with rough surfaces depends sensitively on the area of real contact, in particular close to the percolation threshold, where an irregular network of narrow flow channels prevails. In this paper, numerical simulation and experimental results for the contact between elastic solids with isotropic and anisotropic surface roughness are compared with the predictions of a theory based on the Persson contact mechanics theory and the Bruggeman effective medium theory. The theory predictions are in good agreement with the experimental and numerical simulation results and the (small) deviation can be understood as a finite-size effect. The fluid squeeze-out at the interface between elastic solids with randomly rough surfaces is studied. We present results for such high contact pressures that the area of real contact percolates, giving rise to sealed-off domains with pressurized fluid at the interface. The theoretical predictions are compared to experimental data for a simple model system (a rubber block squeezed against a flat glass plate), and for prefilled syringes, where the rubber plunger stopper is lubricated by a high-viscosity silicon oil to ensure functionality of the delivery device. For the latter system we compare the breakloose (or static) friction, as a function of the time of stationary contact, to the theory prediction.

Long-range correlated percolation

International Nuclear Information System (INIS)

Weinrib, A.

1984-01-01

This paper is a study of the percolation problem with long-range correlations in the site or bond occupations. An extension of the Harris criterion for the relevance of the correlations is derived for the case that the correlations decay as x/sup -a/ for large distances x. For a d the correlations are relevant if dν-2<0. Applying this criterion to the behavior that results when the correlations are relevant, we argue that the new behavior will have ν/sub long/ = 2/a. It is shown that the correlated bond percolation problem is equivalent to a q-state Potts model with quenched disorder in the limit q→1. With the use of this result, a renormalization-group study of the problem is presented, expanding in epsilon = 6-d and in delta = 4-a. In addition to the normal percolation fixed point, we find a new long-range fixed point. The crossover to this new fixed point follows the extended Harris criterion, and the fixed point has exponents ν/sub long/ = 2/a (as predicted) and eta/sub long/ = (1/11)(delta-epsilon). Finally, several results on the percolation properties of the Ising model at its critical point are shown to be in agreement with the predictions of this paper

Percolation with multiple giant clusters

International Nuclear Information System (INIS)

Ben-Naim, E; Krapivsky, P L

2005-01-01

We study mean-field percolation with freezing. Specifically, we consider cluster formation via two competing processes: irreversible aggregation and freezing. We find that when the freezing rate exceeds a certain threshold, the percolation transition is suppressed. Below this threshold, the system undergoes a series of percolation transitions with multiple giant clusters ('gels') formed. Giant clusters are not self-averaging as their total number and their sizes fluctuate from realization to realization. The size distribution F k , of frozen clusters of size k, has a universal tail, F k ∼ k -3 . We propose freezing as a practical mechanism for controlling the gel size. (letter to the editor)

Viral epidemics in a cell culture: novel high resolution data and their interpretation by a percolation theory based model.

Science.gov (United States)

Gönci, Balázs; Németh, Valéria; Balogh, Emeric; Szabó, Bálint; Dénes, Ádám; Környei, Zsuzsanna; Vicsek, Tamás

2010-12-20

Because of its relevance to everyday life, the spreading of viral infections has been of central interest in a variety of scientific communities involved in fighting, preventing and theoretically interpreting epidemic processes. Recent large scale observations have resulted in major discoveries concerning the overall features of the spreading process in systems with highly mobile susceptible units, but virtually no data are available about observations of infection spreading for a very large number of immobile units. Here we present the first detailed quantitative documentation of percolation-type viral epidemics in a highly reproducible in vitro system consisting of tens of thousands of virtually motionless cells. We use a confluent astroglial monolayer in a Petri dish and induce productive infection in a limited number of cells with a genetically modified herpesvirus strain. This approach allows extreme high resolution tracking of the spatio-temporal development of the epidemic. We show that a simple model is capable of reproducing the basic features of our observations, i.e., the observed behaviour is likely to be applicable to many different kinds of systems. Statistical physics inspired approaches to our data, such as fractal dimension of the infected clusters as well as their size distribution, seem to fit into a percolation theory based interpretation. We suggest that our observations may be used to model epidemics in more complex systems, which are difficult to study in isolation.

Critical two-point functions and the lace expansion for spread-out high-dimensional percolation and related models

NARCIS (Netherlands)

Hara, T.; Hofstad, van der R.W.; Slade, G.

2003-01-01

We consider spread-out models of self-avoiding walk, bond percolation, lattice trees and bond lattice animals on ${\\mathbb{Z}^d}$, having long finite-range connections, above their upper critical dimensions $d=4$ (self-avoiding walk), $d=6$ (percolation) and $d=8$ (trees and animals). The two-point

Powder keg divisions in the critical state regime: transition from continuous to explosive percolation

Directory of Open Access Journals (Sweden)

Zhou Zongzheng

2017-01-01

Full Text Available The underlying microstructure and dynamics of a dense granular material as it evolves towards the “critical state”, a limit state in which the system deforms with an essentially constant volume and stress ratio, remains widely debated in the micromechanics of granular media community. Strain localization, a common mechanism in the large strain regime, further complicates the characterization of this limit state. Here we revisit the evolution to this limit state within the framework of modern percolation theory. Attention is paid to motion transfer: in this context, percolation translates to the emergence of a large-scale connectivity in graphs that embody information on individual grain displacements. We construct each graph G(r by connecting nodes, representing the grains, within a distance r in the displacement-state-space. As r increases, we observe a percolation transition on G(r. The size of the jump discontinuity increases in the lead up to failure, indicating that the nature of percolation transition changes from continuous to explosive. We attribute this to the emergence of collective motion, which manifests in increasingly isolated communities in G(r. At the limit state, where the jump discontinuity is highest and invariant across the different unjamming cycles (drops in stress ratio, G(r encapsulates multiple kinematically distinct communities that are mediated by nodes corresponding to those grains in the shear band. This finding casts light on the dual and opposing roles of the shear band: a mechanism that creates powder keg divisions in the sample, while simultaneously acting as a mechanical link that transfers motion through such subdivisions moving in relative rigid-body motion.

Powder keg divisions in the critical state regime: transition from continuous to explosive percolation

Science.gov (United States)

Zhou, Zongzheng; Tordesillas, Antoinette

2017-06-01

The underlying microstructure and dynamics of a dense granular material as it evolves towards the "critical state", a limit state in which the system deforms with an essentially constant volume and stress ratio, remains widely debated in the micromechanics of granular media community. Strain localization, a common mechanism in the large strain regime, further complicates the characterization of this limit state. Here we revisit the evolution to this limit state within the framework of modern percolation theory. Attention is paid to motion transfer: in this context, percolation translates to the emergence of a large-scale connectivity in graphs that embody information on individual grain displacements. We construct each graph G(r) by connecting nodes, representing the grains, within a distance r in the displacement-state-space. As r increases, we observe a percolation transition on G(r). The size of the jump discontinuity increases in the lead up to failure, indicating that the nature of percolation transition changes from continuous to explosive. We attribute this to the emergence of collective motion, which manifests in increasingly isolated communities in G(r). At the limit state, where the jump discontinuity is highest and invariant across the different unjamming cycles (drops in stress ratio), G(r) encapsulates multiple kinematically distinct communities that are mediated by nodes corresponding to those grains in the shear band. This finding casts light on the dual and opposing roles of the shear band: a mechanism that creates powder keg divisions in the sample, while simultaneously acting as a mechanical link that transfers motion through such subdivisions moving in relative rigid-body motion.

Anomalous critical and supercritical phenomena in explosive percolation

Science.gov (United States)

D'Souza, Raissa M.; Nagler, Jan

2015-07-01

The emergence of large-scale connectivity on an underlying network or lattice, the so-called percolation transition, has a profound impact on the system’s macroscopic behaviours. There is thus great interest in controlling the location of the percolation transition to either enhance or delay its onset and, more generally, in understanding the consequences of such control interventions. Here we review explosive percolation, the sudden emergence of large-scale connectivity that results from repeated, small interventions designed to delay the percolation transition. These transitions exhibit drastic, unanticipated and exciting consequences that make explosive percolation an emerging paradigm for modelling real-world systems ranging from social networks to nanotubes.

A new approach for multicriticality in directed and diode percolation

International Nuclear Information System (INIS)

Tsallis, C.; Boston Univ., MA; Redner, S.

1983-01-01

A new and very simple model for treating directed and more general diode percolation problems is presented, by allowing neighboring sites to be joined by up to two independent bonds of opposite orientations. A generalized 'break-collapse' method is developed to calculate renormalization group recursion relations. On the square lattice, a very symmetric phase diagram is obtained which displays multicritical percolation phenomena, and a variety of interesting conductivity transitions are predicted. (Author) [pt

Growth dominates choice in network percolation

Science.gov (United States)

Vijayaraghavan, Vikram S.; Noël, Pierre-André; Waagen, Alex; D'Souza, Raissa M.

2013-09-01

The onset of large-scale connectivity in a network (i.e., percolation) often has a major impact on the function of the system. Traditionally, graph percolation is analyzed by adding edges to a fixed set of initially isolated nodes. Several years ago, it was shown that adding nodes as well as edges to the graph can yield an infinite order transition, which is much smoother than the traditional second-order transition. More recently, it was shown that adding edges via a competitive process to a fixed set of initially isolated nodes can lead to a delayed, extremely abrupt percolation transition with a significant jump in large but finite systems. Here we analyze a process that combines both node arrival and edge competition. If started from a small collection of seed nodes, we show that the impact of node arrival dominates: although we can significantly delay percolation, the transition is of infinite order. Thus, node arrival can mitigate the trade-off between delay and abruptness that is characteristic of explosive percolation transitions. This realization may inspire new design rules where network growth can temper the effects of delay, creating opportunities for network intervention and control.

Bootstrap percolation: a renormalisation group approach

International Nuclear Information System (INIS)

Branco, N.S.; Santos, Raimundo R. dos; Queiroz, S.L.A. de.

1984-02-01

In bootstrap percolation, sites are occupied at random with probability p, but each site is considered active only if at least m of its neighbours are also active. Within an approximate position-space renormalization group framework on a square lattice we obtain the behaviour of the critical concentration p (sub)c and of the critical exponents ν and β for m = 0 (ordinary percolation), 1,2 and 3. We find that the bootstrap percolation problem can be cast into different universality classes, characterized by the values of m. (author) [pt

A special percolation problem in ceramic composites

International Nuclear Information System (INIS)

Ang Chen; Xi Dai; Yu Zhi; Yahua Bao

1993-11-01

The interface effect is taken into consideration, and a special percolation model is proposed for a two-phases metal/ceramic composite in the present paper. The computer simulation shows that the percolation threshold of this interface-controlled percolation behaviour is 4.5% in the three dimensional f.c.c. lattices, which is in good agreement with the experimental data. (author). 9 refs, 3 figs

Phase transition approach to bursting in neuronal cultures: quorum percolation models

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Monceau, P.; Renault, R.; Métens, S.; Bottani, S.; Fardet, T.

2017-10-01

The Quorum Percolation model has been designed in the context of neurobiology to describe bursts of activity occurring in neuronal cultures from the point of view of statistical physics rather than from a dynamical synchronization approach. It is based upon information propagation on a directed graph with a threshold activation rule; this leads to a phase diagram which exhibits a giant percolation cluster below some critical value mC of the excitability. We describe the main characteristics of the original model and derive extensions according to additional relevant biological features. Firstly, we investigate the effects of an excitability variability on the phase diagram and show that the percolation transition can be destroyed by a sufficient amount of such a disorder; we stress the weakly averaging character of the order parameter and show that connectivity and excitability can be seen as two overlapping aspects of the same reality. Secondly, we elaborate a discrete time stochastic model taking into account the decay originating from ionic leakage through the membrane of neurons and synaptic depression; we give evidence that the decay softens and shifts the transition, and conjecture than decay destroys the transition in the thermodynamical limit. We were able to develop mean-field theories associated with each of the two effects; we discuss the framework of their agreement with Monte Carlo simulations. It turns out that the the critical point mC from which information on the connectivity of the network can be inferred is affected by each of these additional effects. Lastly, we show how dynamical simulations of bursts with an adaptive exponential integrateand- fire model can be interpreted in terms of Quorum Percolation. Moreover, the usefulness of the percolation model including the set of sophistication we investigated can be extended to many scientific fields involving information propagation, such as the spread of rumors in sociology, ethology, ecology.

Viral epidemics in a cell culture: novel high resolution data and their interpretation by a percolation theory based model.

Directory of Open Access Journals (Sweden)

Balázs Gönci

2010-12-01

Full Text Available Because of its relevance to everyday life, the spreading of viral infections has been of central interest in a variety of scientific communities involved in fighting, preventing and theoretically interpreting epidemic processes. Recent large scale observations have resulted in major discoveries concerning the overall features of the spreading process in systems with highly mobile susceptible units, but virtually no data are available about observations of infection spreading for a very large number of immobile units. Here we present the first detailed quantitative documentation of percolation-type viral epidemics in a highly reproducible in vitro system consisting of tens of thousands of virtually motionless cells. We use a confluent astroglial monolayer in a Petri dish and induce productive infection in a limited number of cells with a genetically modified herpesvirus strain. This approach allows extreme high resolution tracking of the spatio-temporal development of the epidemic. We show that a simple model is capable of reproducing the basic features of our observations, i.e., the observed behaviour is likely to be applicable to many different kinds of systems. Statistical physics inspired approaches to our data, such as fractal dimension of the infected clusters as well as their size distribution, seem to fit into a percolation theory based interpretation. We suggest that our observations may be used to model epidemics in more complex systems, which are difficult to study in isolation.

Diffusion of test particles in stochastic magnetic fields in the percolative regime

International Nuclear Information System (INIS)

Neuer, Marcus; Spatschek, Karl H.

2006-01-01

For stochastic magnetic flux functions with percolative contours the test particle transport is investigated. The calculations make use of the stochastic Liouville approach. They start from the so-called A-Langevin equations, including stochastic magnetic field components and binary collisions. Using the decorrelation trajectory method, a relation between the Lagrangian velocity correlation function and the Eulerian magnetic field correlation is derived and introduced into the Green-Kubo formalism. Finite Larmor radius effects are included. Interesting results are presented in the percolation regime corresponding to high Kubo numbers. Previous results are found to be limiting cases for small Kubo numbers. For different percolative scenarios the diffusion is analyzed and strong influences of the percolative structures on the transport scaling are found. The finite Larmor radius effects are discussed in detail. Numerical simulations of the A-Langevin equation confirm the semianalytical predictions

Percolation on the institute-enterprise R

Directory of Open Access Journals (Sweden)

Li Chenguang

2015-01-01

Full Text Available Realistic network-like systems are usually composed of multiple networks with interacting relations such as school-enterprise research and development (R&D collaboration networks. Here, we study the percolation properties of a special class of R&D collaboration network, namely institute-enterprise R&D collaboration networks (IERDCNs. We introduce two actual IERDCNs to show their structural properties, and we present a mathematical framework based on generating functions for analyzing an interacting network with any connection probability. Then,we illustrate the percolation threshold and structural parameter arithmetic in the sub-critical and supercritical regimes.We compare the predictions of our mathematical framework and arithmetic to data for two real R&D collaboration networks and a number of simulations. We find that our predictions are in remarkable agreement with the data. We show applications of the framework to electronics R&D collaboration networks

Geometric structure of percolation clusters.

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Xu, Xiao; Wang, Junfeng; Zhou, Zongzheng; Garoni, Timothy M; Deng, Youjin

2014-01-01

We investigate the geometric properties of percolation clusters by studying square-lattice bond percolation on the torus. We show that the density of bridges and nonbridges both tend to 1/4 for large system sizes. Using Monte Carlo simulations, we study the probability that a given edge is not a bridge but has both its loop arcs in the same loop and find that it is governed by the two-arm exponent. We then classify bridges into two types: branches and junctions. A bridge is a branch iff at least one of the two clusters produced by its deletion is a tree. Starting from a percolation configuration and deleting the branches results in a leaf-free configuration, whereas, deleting all bridges produces a bridge-free configuration. Although branches account for ≈43% of all occupied bonds, we find that the fractal dimensions of the cluster size and hull length of leaf-free configurations are consistent with those for standard percolation configurations. By contrast, we find that the fractal dimensions of the cluster size and hull length of bridge-free configurations are given by the backbone and external perimeter dimensions, respectively. We estimate the backbone fractal dimension to be 1.643 36(10).

Finite-size scaling of clique percolation on two-dimensional Moore lattices

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Dong, Jia-Qi; Shen, Zhou; Zhang, Yongwen; Huang, Zi-Gang; Huang, Liang; Chen, Xiaosong

2018-05-01

Clique percolation has attracted much attention due to its significance in understanding topological overlap among communities and dynamical instability of structured systems. Rich critical behavior has been observed in clique percolation on Erdős-Rényi (ER) random graphs, but few works have discussed clique percolation on finite dimensional systems. In this paper, we have defined a series of characteristic events, i.e., the historically largest size jumps of the clusters, in the percolating process of adding bonds and developed a new finite-size scaling scheme based on the interval of the characteristic events. Through the finite-size scaling analysis, we have found, interestingly, that, in contrast to the clique percolation on an ER graph where the critical exponents are parameter dependent, the two-dimensional (2D) clique percolation simply shares the same critical exponents with traditional site or bond percolation, independent of the clique percolation parameters. This has been corroborated by bridging two special types of clique percolation to site percolation on 2D lattices. Mechanisms for the difference of the critical behaviors between clique percolation on ER graphs and on 2D lattices are also discussed.

Ultralow percolation threshold of single walled carbon nanotube-epoxy composites synthesized via an ionic liquid dispersant/initiator

Science.gov (United States)

Watters, Arianna L.; Palmese, Giuseppe R.

2014-09-01

Uniform dispersion of single walled carbon nanotubes (SWNTs) in an epoxy was achieved by a streamlined mechano-chemical processing method. SWNT-epoxy composites were synthesized using a room temperature ionic liquid (IL) with an imidazolium cation and dicyanamide anion. The novel approach of using ionic liquid that behaves as a dispersant for SWNTs and initiator for epoxy polymerization greatly simplifies nanocomposite synthesis. The material was processed using simple and scalable three roll milling. The SWNT dispersion of the resultant composite was evaluated by electron microscopy and electrical conductivity measurements in conjunction with percolation theory. Processing conditions were optimized to achieve the lowest possible percolation threshold, 4.29 × 10-5 volume fraction SWNTs. This percolation threshold is among the best reported in literature yet it was obtained using a streamlined method that greatly simplifies processing.

A new percolation model for composite solid electrolytes and dispersed ionic conductors

Science.gov (United States)

Risyad Hasyim, Muhammad; Lanagan, Michael T.

2018-02-01

Composite solid electrolytes (CSEs) including conductor/insulator composites known as dispersed ionic conductors (DICs) have motivated the development of novel percolation models that describe their conductivity. Despite the long history, existing models lack in one or more key areas: (1) rigorous foundation for their physical theory, (2) explanation for non-universal conductor-insulator transition, (3) classification of DICs, and (4) extension to frequency-domain. This work describes a frequency-domain effective medium approximation (EMA) of a bond percolation model for CSEs. The EMA is derived entirely from Maxwell’s equations and contains basic microstructure parameters. The model was applied successfully to several composite systems from literature. Simulations and fitting of literature data address these key areas and illustrate the interplay between space charge layer properties and bulk microstructure.

Influence of polyethylene glycol on percolation dynamics of reverse microemulsions

Science.gov (United States)

Geethu, P. M.; Yadav, Indresh; Aswal, V. K.; Satapathy, D. K.

2018-04-01

We explore the influence of a hydrophilic polymer, polyethylene glycol (PEG), on the structure and the percolation dynamics of reverse microemulsions (ME) stabilized by an anionic surfactant AOT (sodium bis(2-ethylhexyl) sulfosuccinate). The percolation transition of MEs is probed using dielectric relaxation spectroscopy (DRS). Notably, an increase in percolation temperature is observed by the incorporation of PEG-polymer into larger ME droplets which is explained by considering the model of polymer adsorption at surfactant-water interface. The stability of the droplet phase of microemulsion after the incorporation of PEG is confirmed by small-angle neutron scattering (SANS) experiment. Further, a net decrease in percolation transition temperature is observed with the addition of PEG polymer for smaller ME droplets and is discussed in relation with the destabilization of droplets owing to the polymer induced bridging and the associated clustering of droplets. We conjecture that the adsorption of PEG polymer chains at the surfactant-water interface as well as the PEG-induced bridging of droplets are due to the strong ion-dipole interaction between anionic head group of AOT surfactant and dipoles present in PEG polymer chains.

Statistical mechanics of high-density bond percolation

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Timonin, P. N.

2018-05-01

High-density (HD) percolation describes the percolation of specific κ -clusters, which are the compact sets of sites each connected to κ nearest filled sites at least. It takes place in the classical patterns of independently distributed sites or bonds in which the ordinary percolation transition also exists. Hence, the study of series of κ -type HD percolations amounts to the description of classical clusters' structure for which κ -clusters constitute κ -cores nested one into another. Such data are needed for description of a number of physical, biological, and information properties of complex systems on random lattices, graphs, and networks. They range from magnetic properties of semiconductor alloys to anomalies in supercooled water and clustering in biological and social networks. Here we present the statistical mechanics approach to study HD bond percolation on an arbitrary graph. It is shown that the generating function for κ -clusters' size distribution can be obtained from the partition function of the specific q -state Potts-Ising model in the q →1 limit. Using this approach we find exact κ -clusters' size distributions for the Bethe lattice and Erdos-Renyi graph. The application of the method to Euclidean lattices is also discussed.

Explosive percolation on directed networks due to monotonic flow of activity

Science.gov (United States)

Waagen, Alex; D'Souza, Raissa M.; Lu, Tsai-Ching

2017-07-01

An important class of real-world networks has directed edges, and in addition, some rank ordering on the nodes, for instance the popularity of users in online social networks. Yet, nearly all research related to explosive percolation has been restricted to undirected networks. Furthermore, information on such rank-ordered networks typically flows from higher-ranked to lower-ranked individuals, such as follower relations, replies, and retweets on Twitter. Here we introduce a simple percolation process on an ordered, directed network where edges are added monotonically with respect to the rank ordering. We show with a numerical approach that the emergence of a dominant strongly connected component appears to be discontinuous. Large-scale connectivity occurs at very high density compared with most percolation processes, and this holds not just for the strongly connected component structure but for the weakly connected component structure as well. We present analysis with branching processes, which explains this unusual behavior and gives basic intuition for the underlying mechanisms. We also show that before the emergence of a dominant strongly connected component, multiple giant strongly connected components may exist simultaneously. By adding a competitive percolation rule with a small bias to link uses of similar rank, we show this leads to formation of two distinct components, one of high-ranked users, and one of low-ranked users, with little flow between the two components.

On the upper critical dimension of Bernoulli percolation

International Nuclear Information System (INIS)

Chayes, J.T.; Chayes, L.

1987-01-01

Derived is a set of inequalities for the d-dimensional independent percolation problem. Assuming the existence of critical exponents, these inequalities imply: f + nu ≥ 1 + β/sub Q/, μ + nu ≥ 1 + β/sub Q/, zeta ≥ min (1, nu'/nu), where the above exponents are f: the flow constant exponent, nu (nu'): the correlation length exponent below (above) threshold, μ: the surface tension exponent, β/sub Q/: the backbone density exponent and zeta: the chemical distance exponent. Note that all of these inequalities are mean-field bounds, and that they relate the exponent nu defined from below the percolation threshold to exponents defined from above threshold. Furthermore, we combine the strategy of the proofs these inequalities with notions of finite-size scaling to derive: max (d nu, d nu') ≥ 1 + β/sub Q/, where d is the lattice dimension. Since β/sub Q/ ≥ 2β, where β is the percolation density exponent, the final bound implies that, below six dimensions, the standard order parameter and correlation length exponents cannot simultaneously assume their mean-field values; hence an implicit bound on the upper critical dimension: d/sub c/ ≥ 6

Ultralow percolation threshold of single walled carbon nanotube-epoxy composites synthesized via an ionic liquid dispersant/initiator

International Nuclear Information System (INIS)

Watters, Arianna L; Palmese, Giuseppe R

2014-01-01

Uniform dispersion of single walled carbon nanotubes (SWNTs) in an epoxy was achieved by a streamlined mechano-chemical processing method. SWNT-epoxy composites were synthesized using a room temperature ionic liquid (IL) with an imidazolium cation and dicyanamide anion. The novel approach of using ionic liquid that behaves as a dispersant for SWNTs and initiator for epoxy polymerization greatly simplifies nanocomposite synthesis. The material was processed using simple and scalable three roll milling. The SWNT dispersion of the resultant composite was evaluated by electron microscopy and electrical conductivity measurements in conjunction with percolation theory. Processing conditions were optimized to achieve the lowest possible percolation threshold, 4.29 × 10 −5 volume fraction SWNTs. This percolation threshold is among the best reported in literature yet it was obtained using a streamlined method that greatly simplifies processing. (paper)

Percolation for a model of statistically inhomogeneous random media

International Nuclear Information System (INIS)

Quintanilla, J.; Torquato, S.

1999-01-01

We study clustering and percolation phenomena for a model of statistically inhomogeneous two-phase random media, including functionally graded materials. This model consists of inhomogeneous fully penetrable (Poisson distributed) disks and can be constructed for any specified variation of volume fraction. We quantify the transition zone in the model, defined by the frontier of the cluster of disks which are connected to the disk-covered portion of the model, by defining the coastline function and correlation functions for the coastline. We find that the behavior of these functions becomes largely independent of the specific choice of grade in volume fraction as the separation of length scales becomes large. We also show that the correlation function behaves in a manner similar to that of fractal Brownian motion. Finally, we study fractal characteristics of the frontier itself and compare to similar properties for two-dimensional percolation on a lattice. In particular, we show that the average location of the frontier appears to be related to the percolation threshold for homogeneous fully penetrable disks. copyright 1999 American Institute of Physics

On the genre-fication of music: a percolation approach

Science.gov (United States)

Lambiotte, R.; Ausloos, M.

2006-03-01

We analyze web-downloaded data on people sharing their music library. By attributing to each music group usual music genres (Rock, Pop ...), and analysing correlations between music groups of different genres with percolation-idea based methods, we probe the reality of these subdivisions and construct a music genre cartography, with a tree representation. We also discuss an alternative objective way to classify music, that is based on the complex structure of the groups audience. Finally, a link is drawn with the theory of hidden variables in complex networks.

The relationship between synchronization and percolation for regular networks

Science.gov (United States)

Li, Zhe; Ren, Tao; Xu, Yanjie; Jin, Jianyu

2018-02-01

Synchronization and percolation are two essential phenomena in complex dynamical networks. They have been studied widely, but previously treated as unrelated. In this paper, the relationship between synchronization and percolation are revealed for regular networks. Firstly, we discovered a bridge between synchronization and percolation by using the eigenvalues of the Laplacian matrix to describe the synchronizability and using the eigenvalues of the adjacency matrix to describe the percolation threshold. Then, we proposed a method to find the relationship for regular networks based on the topology of networks. Particularly, if the degree distribution of the network is subject to delta function, we show that only the eigenvalues of the adjacency matrix need to be calculated. Finally, several examples are provided to demonstrate how to apply our proposed method to discover the relationship between synchronization and percolation for regular networks.

Percolation via Combined Electrostatic and Chemical Doping in Complex Oxide Films

Science.gov (United States)

Orth, Peter P.; Fernandes, Rafael M.; Walter, Jeff; Leighton, C.; Shklovskii, B. I.

2017-03-01

Stimulated by experimental advances in electrolyte gating methods, we investigate theoretically percolation in thin films of inhomogeneous complex oxides, such as La1 -xSrxCoO3 (LSCO), induced by a combination of bulk chemical and surface electrostatic doping. Using numerical and analytical methods, we identify two mechanisms that describe how bulk dopants reduce the amount of electrostatic surface charge required to reach percolation: (i) bulk-assisted surface percolation and (ii) surface-assisted bulk percolation. We show that the critical surface charge strongly depends on the film thickness when the film is close to the chemical percolation threshold. In particular, thin films can be driven across the percolation transition by modest surface charge densities. If percolation is associated with the onset of ferromagnetism, as in LSCO, we further demonstrate that the presence of critical magnetic clusters extending from the film surface into the bulk results in considerable enhancement of the saturation magnetization, with pronounced experimental consequences. These results should significantly guide experimental work seeking to verify gate-induced percolation transitions in such materials.

Estimation of water percolation by different methods using TDR

Directory of Open Access Journals (Sweden)

Alisson Jadavi Pereira da Silva

2014-02-01

Full Text Available Detailed knowledge on water percolation into the soil in irrigated areas is fundamental for solving problems of drainage, pollution and the recharge of underground aquifers. The aim of this study was to evaluate the percolation estimated by time-domain-reflectometry (TDR in a drainage lysimeter. We used Darcy's law with K(θ functions determined by field and laboratory methods and by the change in water storage in the soil profile at 16 points of moisture measurement at different time intervals. A sandy clay soil was saturated and covered with plastic sheet to prevent evaporation and an internal drainage trial in a drainage lysimeter was installed. The relationship between the observed and estimated percolation values was evaluated by linear regression analysis. The results suggest that percolation in the field or laboratory can be estimated based on continuous monitoring with TDR, and at short time intervals, of the variations in soil water storage. The precision and accuracy of this approach are similar to those of the lysimeter and it has advantages over the other evaluated methods, of which the most relevant are the possibility of estimating percolation in short time intervals and exemption from the predetermination of soil hydraulic properties such as water retention and hydraulic conductivity. The estimates obtained by the Darcy-Buckingham equation for percolation levels using function K(θ predicted by the method of Hillel et al. (1972 provided compatible water percolation estimates with those obtained in the lysimeter at time intervals greater than 1 h. The methods of Libardi et al. (1980, Sisson et al. (1980 and van Genuchten (1980 underestimated water percolation.

Percolation blockage: A process that enables melt pond formation on first year Arctic sea ice

Science.gov (United States)

Polashenski, Chris; Golden, Kenneth M.; Perovich, Donald K.; Skyllingstad, Eric; Arnsten, Alexandra; Stwertka, Carolyn; Wright, Nicholas

2017-01-01

Melt pond formation atop Arctic sea ice is a primary control of shortwave energy balance in the Arctic Ocean. During late spring and summer, the ponds determine sea ice albedo and how much solar radiation is transmitted into the upper ocean through the sea ice. The initial formation of ponds requires that melt water be retained above sea level on the ice surface. Both theory and observations, however, show that first year sea ice is so highly porous prior to the formation of melt ponds that multiday retention of water above hydraulic equilibrium should not be possible. Here we present results of percolation experiments that identify and directly demonstrate a mechanism allowing melt pond formation. The infiltration of fresh water into the pore structure of sea ice is responsible for blocking percolation pathways with ice, sealing the ice against water percolation, and allowing water to pool above sea level. We demonstrate that this mechanism is dependent on fresh water availability, known to be predominantly from snowmelt, and ice temperature at melt onset. We argue that the blockage process has the potential to exert significant control over interannual variability in ice albedo. Finally, we suggest that incorporating the mechanism into models would enhance their physical realism. Full treatment would be complex. We provide a simple temperature threshold-based scheme that may be used to incorporate percolation blockage behavior into existing model frameworks.

Aerodynamics and Percolation: Unfolding Laminar Separation Bubble on Airfoils

Science.gov (United States)

Traphan, Dominik; Wester, Tom T. B.; Gülker, Gerd; Peinke, Joachim; Lind, Pedro G.

2018-04-01

As a fundamental phenomenon of fluid mechanics, recent studies suggested laminar-turbulent transition belonging to the universality class of directed percolation. Here, the onset of a laminar separation bubble on an airfoil is analyzed in terms of the directed percolation model using particle image velocimetry data. Our findings indicate a clear significance of percolation models in a general flow situation beyond fundamental ones. We show that our results are robust against fluctuations of the parameter, namely, the threshold of turbulence intensity, that maps velocimetry data into binary cells (turbulent or laminar). In particular, this percolation approach enables the precise determination of the transition point of the laminar separation bubble, an important problem in aerodynamics.

Directed polymers versus directed percolation

Science.gov (United States)

Halpin-Healy, Timothy

1998-10-01

Universality plays a central role within the rubric of modern statistical mechanics, wherein an insightful continuum formulation rises above irrelevant microscopic details, capturing essential scaling behaviors. Nevertheless, occasions do arise where the lattice or another discrete aspect can constitute a formidable legacy. Directed polymers in random media, along with its close sibling, directed percolation, provide an intriguing case in point. Indeed, the deep blood relation between these two models may have sabotaged past efforts to fully characterize the Kardar-Parisi-Zhang universality class, to which the directed polymer belongs.

A contribution from dielectric analysis to the study of the formation of multi-wall carbon nanotubes percolated networks in epoxy resin under an electric field

International Nuclear Information System (INIS)

Risi, Celso L.S.; Hattenhauer, Irineu; Ramos, Airton; Coelho, Luiz A.F.; Pezzin, Sérgio H.

2015-01-01

The formation of percolation networks in epoxy matrix nanocomposites reinforced with multi-wall carbon nanotubes (MWNT) during the curing process, at different MWNT contents, was studied by using a parallel plate cell subjected to a 300 V/cm AC electric field at 1 kHz. The percolation was verified by the electrical current output measured during and after the resin curing. The behavior of electric dipoles was characterized by impedance spectroscopy and followed the Debye first order dispersion model, by which an average relaxation time of 6.0 × 10 −4 s and a cut-off frequency of 1.7 kHz were experimentally found. By applying the theory of percolation, a critical probability, p c , equal to 0.038 vol% and an exponent of conductivity of 2.0 were found. Both aligned and random samples showed dipole relaxation times typical of interfacial and/or charge-hopping polarization, while the permittivity exhibited an exponential decrease with frequency. This behavior can be related to the increased ability to trap electrical charges due to the formation of the carbon nanotubes network. Optical and electron microscopies confirm the theoretical prediction that the application of an electric field during cure helps the process of MWNT debundling in epoxy resin. - Highlights: • We report the formation of percolating networks of MWNTs under AC electric field. • MWNT/epoxy dielectric properties were measured by impedance spectroscopy. • Lower percolation thresholds were obtained for composites with aligned CNTs. • Application of AC electric field helps the debundling of CNTs. • CNT/Epoxy with percolated networks presents interfacial and hopping polarizations

Two percolation thresholds due to geometrical effects: experimental and simulated results

International Nuclear Information System (INIS)

Nettelblad, B; Martensson, E; Oenneby, C; Gaefvert, U; Gustafsson, A

2003-01-01

The electrical properties of a mixture of ethylene-propylene-diene monomer rubber and silicon carbide (SiC) have been measured as a function of filler concentration. It was found that mixtures containing angular SiC grains have a conductivity that displays not one, but two percolation thresholds. Different types of contacts between the conducting particles, being represented by edge and face connections, respectively, can explain the phenomenon. The two percolation thresholds are obtained at volume fractions of about 0.25 and 0.40, respectively. These values are higher than those predicted by theory, which can be explained by dispersion effects with only one phase being granular and the other being continuous. The value of the conductivity at the central plateau was found to be close to the geometric mean of the limiting conductivities at low and high concentrations. This is in good agreement with theory. With rounded SiC grains only one threshold is obtained, which is consistent with only one type of contact. The concentration dependence of the conductivity was simulated using a three-dimensional impedance network model that incorporates both edge and face contacts. The double-threshold behaviour also appears in the calculations. By dispersing the conducting particles more evenly than random, the thresholds are shifted towards higher concentrations as observed in the experiments

Analysis of water/gas flows in argillites from Callovo-Oxfordian using gradient percolation

International Nuclear Information System (INIS)

Lefort, Philippe

2014-01-01

The work presented in this manuscript is motivated by the study of nuclear waste underground repository. In this context, we study the hyper slow drainage problem, which is related to the gas production, mainly hydrogen, taking place within the repository. Although the gas production rate is quite small, and thus the drainage hyper slow, the amount of produced gas is quite significant because the production takes place over thousands years. The study is performed within the framework of the theory of invasion percolation in a gradient. We first show that the hyper slow drainage process can be modelled using the traditional two-phase flow model based on the generalized Darcy's law. A crucial step is then to specify properly the parameters of the model. We show how they must be specified from the asymptotic behaviours of the parameters for an infinite medium as predicted by percolation theory. The obtained solution indicates that the hyper slow drainage operates in the vicinity of breakthrough pressure, which is the subject of a specific study. Furthermore, the hyper slow drainage is characterized by a weak desaturation of the medium and a great sensitivity to the model parameters in the range of high wetting fluid saturation. We also study the impact of coupling between the flow and the local deformation of porous matrix at the pore network scale from numerical simulations using a model coupling a pore network model and a deformation model based on a system of interconnected springs. The simulations indicate a major change of the invasion pattern compared to the rigid matrix with the self-generation of invasion preferential paths when the coupling is sufficiently strong. (author)

Innovation diffusion in networks : the microeconomics of percolation

NARCIS (Netherlands)

Zeppini, P.; Frenken, K.; Izquierdo, L.R.

2013-01-01

We implement a diffusion model for an innovative product in a market with a structure of social relationships. Diffusion is described with a percolation approach in the price space. Percolation shows a phase transition from a diffusion to a no-diffusion regime. This has strong implications for

Innovation diffusion in networks: the microeconomics of percolation

NARCIS (Netherlands)

Zeppini, P.; Frenken, K.; Izquierdo, L.R.

2013-01-01

We implement a diffusion model for an innovative product in a market with a structure of social relationships. Diffusion is described with a percolation approach in the price space. Percolation shows a phase transition from a diffusion to a no-diffusion regime. This has strong implications for

Definition of percolation thresholds on self-affine surfaces

NARCIS (Netherlands)

Marrink, S.J.; Paterson, Lincoln; Knackstedt, Mark A.

2000-01-01

We study the percolation transition on a two-dimensional substrate with long-range self-affine correlations. We find that the position of the percolation threshold on a correlated lattice is no longer unique and depends on the spanning rule employed. Numerical results are provided for spanning

Experimental percolation studies of random networks

Science.gov (United States)

Feinerman, A.; Weddell, J.

2017-06-01

This report establishes an experimental method of studying electrically percolating networks at a higher resolution than previously implemented. This method measures the current across a conductive sheet as a function of time as elliptical pores are cut into the sheet. This is done utilizing a Universal Laser System X2-600 100 W CO2 laser system with a 76 × 46 cm2 field and 394 dpc (dots/cm) resolution. This laser can cut a random system of elliptical pores into a conductive sheet with a potential voltage applied across it and measures the current versus time. This allows for experimental verification of a percolation threshold as a function of the ellipse's aspect ratio (minor/major diameter). We show that as an ellipse's aspect ratio approaches zero, the percolation threshold approaches one. The benefit of this method is that it can experimentally measure the effect of removing small pores, as well as pores with complex geometries, such as an asterisk from a conductive sheet.

Progress in high-dimensional percolation and random graphs

CERN Document Server

Heydenreich, Markus

2017-01-01

This text presents an engaging exposition of the active field of high-dimensional percolation that will likely provide an impetus for future work. With over 90 exercises designed to enhance the reader’s understanding of the material, as well as many open problems, the book is aimed at graduate students and researchers who wish to enter the world of this rich topic.  The text may also be useful in advanced courses and seminars, as well as for reference and individual study. Part I, consisting of 3 chapters, presents a general introduction to percolation, stating the main results, defining the central objects, and proving its main properties. No prior knowledge of percolation is assumed. Part II, consisting of Chapters 4–9, discusses mean-field critical behavior by describing the two main techniques used, namely, differential inequalities and the lace expansion. In Parts I and II, all results are proved, making this the first self-contained text discussing high-dimensiona l percolation.  Part III, consist...

Quantum walks of two interacting particles on percolation graphs

Science.gov (United States)

Siloi, Ilaria; Benedetti, Claudia; Piccinini, Enrico; Paris, Matteo G. A.; Bordone, Paolo

2017-10-01

We address the dynamics of two indistinguishable interacting particles moving on a dynamical percolation graph, i.e., a graph where the edges are independent random telegraph processes whose values jump between 0 and 1, thus mimicking percolation. The interplay between the particle interaction strength, initial state and the percolation rate determine different dynamical regimes for the walkers. We show that, whenever the walkers are initially localised within the interaction range, fast noise enhances the particle spread compared to the noiseless case.

Percolation, SLE and related topics

CERN Document Server

Kreimer, Dirk; Renormalization and universality in mathematical physics

2007-01-01

This book covers a wide range of phenomena in the natural sciences dominated by notions of universality and renormalization. The contributions in this volume are equally broad in their approach to these phenomena, offering the mathematical as well as the perspective of the applied sciences. They explore renormalization theory in quantum field theory and statistical physics, and its connections to modern mathematics as well as physics on scales from the microscopic to the macroscopic.

Normalized fluctuations, H2O vs n-hexane: Site-correlated percolation

Science.gov (United States)

Koga, Yoshikata; Westh, Peter; Sawamura, Seiji; Taniguchi, Yoshihiro

1996-08-01

Entropy, volume and the cross fluctuations were normalized to the average volume of a coarse grain with a fixed number of molecules, within which the local and instantaneous value of interest is evaluated. Comparisons were made between liquid H2O and n-hexane in the range from -10 °C to 120 °C and from 0.1 MPa to 500 MPa. The difference between H2O and n-hexane in temperature and pressure dependencies of these normalized fluctuations was explained in terms of the site-correlated percolation theory for H2O. In particular, the temperature increase was confirmed to reduce the hydrogen bond probability, while the pressure appeared to have little effect on the hydrogen bond probability. According to the Le Chatelier principle, however, the putative formation of ``ice-like'' patches at low temperatures due to the site-correlated percolation requirement is retarded by pressure increases. Thus, only in the limited region of low pressure (<300 MPa) and temperature (<60 °C), the fluctuating ice-like patches are considered to persist.

Micro-foundation using percolation theory of the finite time singular behavior of the crash hazard rate in a class of rational expectation bubbles

Science.gov (United States)

Seyrich, Maximilian; Sornette, Didier

2016-04-01

We present a plausible micro-founded model for the previously postulated power law finite time singular form of the crash hazard rate in the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles. The model is based on a percolation picture of the network of traders and the concept that clusters of connected traders share the same opinion. The key ingredient is the notion that a shift of position from buyer to seller of a sufficiently large group of traders can trigger a crash. This provides a formula to estimate the crash hazard rate by summation over percolation clusters above a minimum size of a power sa (with a>1) of the cluster sizes s, similarly to a generalized percolation susceptibility. The power sa of cluster sizes emerges from the super-linear dependence of group activity as a function of group size, previously documented in the literature. The crash hazard rate exhibits explosive finite time singular behaviors when the control parameter (fraction of occupied sites, or density of traders in the network) approaches the percolation threshold pc. Realistic dynamics are generated by modeling the density of traders on the percolation network by an Ornstein-Uhlenbeck process, whose memory controls the spontaneous excursion of the control parameter close to the critical region of bubble formation. Our numerical simulations recover the main stylized properties of the JLS model with intermittent explosive super-exponential bubbles interrupted by crashes.

Monopole percolation and the universality class of the chiral transition in four flavor noncompact lattice QED

CERN Document Server

Kocic, Aleksandar; Wang, K C

1993-01-01

We simulate four flavor noncompact lattice QED using the Hybrid Monte Carlo algorithm on $10^4$ and $16^4$ lattices. Measurements of the monopole susceptibility and the percolation order parameter indicate a transition at $\\beta = {1/e^2} = .205(5)$ with critical behavior in the universality class of four dimensional percolation. We present accurate chiral condensate measurements and monitor finite size effects carefully. The chiral condensate data supports the existence of a power-law transition at $\\beta = .205$ in the same universality class as the chiral transition in the two flavor model. The resulting equation of state predicts the mass ratio $m_\\pi^2/m_\\sigma^2$ in good agreement with spectrum calculations while the hypothesis of a logarithmically improved mean field theory fails qualitatively.

Dielectric and diamagnetic susceptibilities near percolative superconductor-insulator transitions.

Science.gov (United States)

Loh, Yen Lee; Karki, Pragalv

2017-10-25

Coarse-grained superconductor-insulator composites exhibit a superconductor-insulator transition governed by classical percolation, which should be describable by networks of inductors and capacitors. We study several classes of random inductor-capacitor networks on square lattices. We present a unifying framework for defining electric and magnetic response functions, and we extend the Frank-Lobb bond-propagation algorithm to compute these quantities by network reduction. We confirm that the superfluid stiffness scales approximately as [Formula: see text] as the superconducting bond fraction p approaches the percolation threshold p c . We find that the diamagnetic susceptibility scales as [Formula: see text] below percolation, and as [Formula: see text] above percolation. For models lacking self-capacitances, the electric susceptibility scales as [Formula: see text]. Including a self-capacitance on each node changes the critical behavior to approximately [Formula: see text].

Quenched Large Deviations for Simple Random Walks on Percolation Clusters Including Long-Range Correlations

Science.gov (United States)

Berger, Noam; Mukherjee, Chiranjib; Okamura, Kazuki

2018-03-01

We prove a quenched large deviation principle (LDP) for a simple random walk on a supercritical percolation cluster (SRWPC) on {Z^d} ({d ≥ 2}). The models under interest include classical Bernoulli bond and site percolation as well as models that exhibit long range correlations, like the random cluster model, the random interlacement and the vacant set of random interlacements (for {d ≥ 3}) and the level sets of the Gaussian free field ({d≥ 3}). Inspired by the methods developed by Kosygina et al. (Commun Pure Appl Math 59:1489-1521, 2006) for proving quenched LDP for elliptic diffusions with a random drift, and by Yilmaz (Commun Pure Appl Math 62(8):1033-1075, 2009) and Rosenbluth (Quenched large deviations for multidimensional random walks in a random environment: a variational formula. Ph.D. thesis, NYU, arXiv:0804.1444v1) for similar results regarding elliptic random walks in random environment, we take the point of view of the moving particle and prove a large deviation principle for the quenched distribution of the pair empirical measures of the environment Markov chain in the non-elliptic case of SRWPC. Via a contraction principle, this reduces easily to a quenched LDP for the distribution of the mean velocity of the random walk and both rate functions admit explicit variational formulas. The main difficulty in our set up lies in the inherent non-ellipticity as well as the lack of translation-invariance stemming from conditioning on the fact that the origin belongs to the infinite cluster. We develop a unifying approach for proving quenched large deviations for SRWPC based on exploiting coercivity properties of the relative entropies in the context of convex variational analysis, combined with input from ergodic theory and invoking geometric properties of the supercritical percolation cluster.

Influence of fractal substructures of the percolating cluster on transferring processes in macroscopically disordered environments

Science.gov (United States)

Kolesnikov, B. P.

2017-11-01

The presented work belongs to the issue of searching for the effective kinetic properties of macroscopically disordered environments (MDE). These properties characterize MDE in general on the sizes which significantly exceed the sizes of macro inhomogeneity. The structure of MDE is considered as a complex of interpenetrating percolating and finite clusters consolidated from homonymous components, topological characteristics of which influence on the properties of the whole environment. The influence of percolating clusters’ fractal substructures (backbone, skeleton of backbone, red bonds) on the transfer processes during crossover (a structure transition from fractal to homogeneous condition) is investigated based on the offered mathematical approach for finding the effective conductivity of MDEs and on the percolating cluster model. The nature of the change of the critical conductivity index t during crossover from the characteristic value for the area close to percolation threshold to the value corresponded to homogeneous condition is demonstrated. The offered model describes the transfer processes in MDE with the finite conductivity relation of «conductive» and «low conductive» phases above and below percolation threshold and in smearing area (an analogue of a blur area of the second-order phase transfer).

Influence of Tableting on Enzymatic Activity of Papain along with Determination of Its Percolation Threshold with Microcrystalline Cellulose

Science.gov (United States)

Sharma, Manu; Sharma, Vinay; Majumdar, Dipak K.

2014-01-01

The binary mixture tablets of papain and microcrystalline cellulose (MCC), dicalcium phosphate dihydrate (DCP), carrageenan, tragacanth, and agar were prepared by direct compression. Carrageenan, tragacanth, and agar provided maximum protection to enzyme activity compared to MCC and DCP. However, stability studies indicated highest loss of enzyme activity with carrageenan, tragacanth, and agar. Therefore, compression behaviour of different binary mixtures of papain with MCC at different compaction pressures, that is, 40–280 MPa, was studied according to Heckel equation. The compressibility studies of binary mixtures indicated brittle behavior of papain. The application of percolation theory on the relationship between critical density as a function of enzyme activity and mixture composition revealed the presence of percolation threshold for binary mixture. Papain-MCC mixture composition showed significant percolation threshold at 18.48% (w/w) papain loading. Microcrystalline cellulose provided higher protection during stability study. However, higher concentrations of microcrystalline cellulose, probably as dominant particles, do not protect the enzyme with their plastic deformation. Below the percolation threshold, that is, 18.48% (w/w) papain amount in mixture with plastic excipient, activity loss increases strongly because of higher shearing forces during compaction due to system dominance of plastic particles. This mixture range should therefore be avoided to get robust formulation of papain. PMID:27350972

Percolation Model of Nuclear Multifragmentation in High Energy Nucleus-Nucleus Interactions

International Nuclear Information System (INIS)

Abdel-Waged, Kh.

1994-01-01

A hybrid model based on Reggeon theory inspired model of nuclear distribution, which was successful in explaining the cascading of particles in high energy nucleus-nucleus interactions, and percolation model is proposed. In the framework of this model the yield of the fragment in p + Ag, Au at 350 GeV and C + Ag, Au at 3.6 GeV/nucleon as well as the charge distribution of fragments in Kr, Xe and U interactions with emulsion at ∼ 1 GeV/nucleon is correctly described. 32 refs., 3 figs

Percolation Diffusion into Self-Assembled Mesoporous Silica Microfibres

Directory of Open Access Journals (Sweden)

John Canning

2014-03-01

Full Text Available Percolation diffusion into long (11.5 cm self-assembled, ordered mesoporous microfibres is studied using optical transmission and laser ablation inductive coupled mass spectrometry (LA-ICP-MS. Optical transmission based diffusion studies reveal rapid penetration (<5 s, D > 80 μm2∙s−1 of Rhodamine B with very little percolation of larger molecules such as zinc tetraphenylporphyrin (ZnTPP observed under similar loading conditions. The failure of ZnTPP to enter the microfibre was confirmed, in higher resolution, using LA-ICP-MS. In the latter case, LA-ICP-MS was used to determine the diffusion of zinc acetate dihydrate, D~3 × 10−4 nm2∙s−1. The large differences between the molecules are accounted for by proposing ordered solvent and structure assisted accelerated diffusion of the Rhodamine B based on its hydrophilicity relative to the zinc compounds. The broader implications and applications for filtration, molecular sieves and a range of devices and uses are described.

Anaerobic Treatment Of Percolate From Faecal Sludge Drying Beds ...

African Journals Online (AJOL)

Composite percolate samples, from sludge drying beds of a pilot co-composting plant in Kumasi, Ghana, were characterised and subjected to laboratory scale anaerobic treatment. Two categories of percolate samples were investigated; samples seeded with anaerobic sludge and samples without seeding. The average ...

Factors affecting water balance and percolate production for a landfill in operation.

Science.gov (United States)

Poulsen, Tjalfe G; Møoldrup, Per

2005-02-01

Percolate production and precipitation data for a full-scale landfill in operation measured over a 13-year period were used to evaluate the impact and importance of the hydrological conditions of landfill sections on the percolate production rates. Both active (open) and closed landfill sections were included in the evaluation. A simple top cover model requiring a minimum of input data was used to simulate the percolate production as a function of precipitation and landfill section hydrology. The results showed that changes over time in the hydrology of individual landfill sections (such as section closure or plantation of trees on top of closed sections) can change total landfill percolate production by more than 100%; thus, percolate production at an active landfill can be very different from percolate production at the same landfill after closure. Furthermore, plantation of willow on top of closed sections can increase the evapotranspiration rate thereby reducing percolate production rates by up to 47% compared to a grass cover. This process, however, depends upon the availability of water in the top layer, and so the evaporation rate will be less than optimal during the summer where soil-water contents in the top cover are low.

Percolation of secret correlations in a network

OpenAIRE

Leverrier, Anthony; García-Patrón, Raúl

2011-01-01

In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks, more precisely the question of percolation of secret correlations in a network. It is known that entanglement percolation in quantum networks can display a highly nontrivial behavior depending on the topology of the network and on the presence of entanglement between the nodes. Here we show that this behavior, thought to be of a genuine quantum nature, also occurs in a...

Percolation of secret correlations in a network

Energy Technology Data Exchange (ETDEWEB)

Leverrier, Anthony; Garcia-Patron, Raul [ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels (Barcelona) (Spain); Research Laboratory of Electronics, MIT, Cambridge, MA 02139 (United States) and Max-Planck Institut fur Quantenoptik, Hans-Kopfermann Str. 1, D-85748 Garching (Germany)

2011-09-15

In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks--more precisely, the question of percolation of secret correlations in a network. It is known that entanglement percolation in quantum networks can display a highly nontrivial behavior depending on the topology of the network and on the presence of entanglement between the nodes. Here we show that this behavior, thought to be of a genuine quantum nature, also occurs in a classical context.

Percolation of secret correlations in a network

International Nuclear Information System (INIS)

Leverrier, Anthony; Garcia-Patron, Raul

2011-01-01

In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks--more precisely, the question of percolation of secret correlations in a network. It is known that entanglement percolation in quantum networks can display a highly nontrivial behavior depending on the topology of the network and on the presence of entanglement between the nodes. Here we show that this behavior, thought to be of a genuine quantum nature, also occurs in a classical context.

Percolation testing at the F- and H-Area Seepage Basins

International Nuclear Information System (INIS)

McHood, M.D.

1993-01-01

The design of the F- and H-Area Seepage Basin contaminated groundwater remediation system requires information from multiple well pump tests (Reference 1). Soil percolation rates are needed in order to support the multiple well pump test planning. The objective of this task was to determine characteristic percolation rates for soils in four select areas where infiltration galleries are proposed. These infiltration galleries will be temporary installations built on the ground surface and used to disposes of water from the multiple well pump tests. A procedure defining the specific work process for collecting percolation rate data is contained in Appendix 3. Results from these percolation tests will be used in the design of infiltration galleries for the disposal of well water extracted during the multiple well pump tests

Large scale structure from biased non-equilibrium phase transitions percolation theory picture

CERN Document Server

Lalak, Z; Ovrut, B A; Ross, Graham G

1995-01-01

We give an analytical description of the spatial distribution of domain walls produced during a biased nonequilibrium phase transition in the vacuum state of a light scalar field. We discuss in detail the spectrum of the associated cosmological energy density perturbations. It is shown that the contribution coming from domain walls can enhance the standard cold dark matter spectrum in such a way as to account for the whole range of IRAS data and for the COBE measurement of the microwave background anisotropy. We also demonstrate that in case of a biased phase transition which allows a percolative description, the number of large size domain walls is strongly suppressed. This offers a way of avoiding excessive microwave background distorsions due to the gravitational field of domain walls present after decoupling.

Controlling percolation with limited resources

Science.gov (United States)

Schröder, Malte; Araújo, Nuno A. M.; Sornette, Didier; Nagler, Jan

2017-12-01

Connectivity, or the lack thereof, is crucial for the function of many man-made systems, from financial and economic networks over epidemic spreading in social networks to technical infrastructure. Often, connections are deliberately established or removed to induce, maintain, or destroy global connectivity. Thus, there has been a great interest in understanding how to control percolation, the transition to large-scale connectivity. Previous work, however, studied control strategies assuming unlimited resources. Here, we depart from this unrealistic assumption and consider the effect of limited resources on the effectiveness of control. We show that, even for scarce resources, percolation can be controlled with an efficient intervention strategy. We derive such an efficient strategy and study its implications, revealing a discontinuous transition as an unintended side effect of optimal control.

A generalized model for site percolation with two independent concentrations

International Nuclear Information System (INIS)

Lin Jiancheng.

1987-05-01

In this paper the usual site percolation problem with single concentration is generalized to the one that contains two independent concentrations. Using the real space renormalization technique we derive an exact transformation for the one dimensional lattice and a cluster transformation for triangle lattice in two dimensions. The critical exponents and the percolation threshold concentrations obtained are the same as those of the usual single concentration percolation problem. Critical line and flow diagram in the two concentration parameters space are also given. (author). 10 refs, 6 figs

Application of percolation leaching in Fuzhou uranium mine

International Nuclear Information System (INIS)

Jiang Lang; Wang Haita; He Jiangming

2006-01-01

In order to solve these problems such as high cost by conventional agitation leaching, low permeability and low leaching rate by heap leach, a percolation leaching method was developed. Two-year's production results show that leaching rate of uranium is up to 90% by this method. Compared with conventional agitation leaching, the power, sulfuric acid and lime consumption by the percolation leaching decreased by 60%, 27% and 77% respectively. (authors)

Percolation Threshold Parameters of Fluids

Czech Academy of Sciences Publication Activity Database

Škvor, J.; Nezbeda, Ivo

2009-01-01

Roč. 79, č. 4 (2009), 041141-041147 ISSN 1539-3755 Institutional research plan: CEZ:AV0Z40720504 Keywords : percolation threshold * universality * infinite cluster Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.400, year: 2009

A Numerical Study on Electrical Percolation of Polymer-Matrix Composites with Hybrid Fillers of Carbon Nanotubes and Carbon Black

Directory of Open Access Journals (Sweden)

Yuli Chen

2014-01-01

Full Text Available The electrical percolation of polymer-matrix composites (PMCs containing hybrid fillers of carbon nanotubes (CNTs and carbon black (CB is estimated by studying the connection possibility of the fillers using Monte Carlo simulation. The 3D simulation model of CB-CNT hybrid filler is established, in which CNTs are modeled by slender capped cylinders and CB groups are modeled by hypothetical spheres with interspaces because CB particles are always agglomerated. The observation on the effects of CB and CNT volume fractions and dimensions on the electrical percolation threshold of hybrid filled composites is then carried out. It is found that the composite electrical percolation threshold can be reduced by increasing CNT aspect ratio, as well as increasing the diameter ratio of CB groups to CNTs. And adding CB into CNT composites can decrease the CNT volume needed to convert the composite conductivity, especially when the CNT volume fraction is close to the threshold of PMCs with only CNT filler. Different from previous linear assumption, the nonlinear relation between CB and CNT volume fractions at composite percolation threshold is revealed, which is consistent with the synergistic effect observed in experiments. Based on the nonlinear relation, the estimating equation for the electrical percolation threshold of the PMCs containing CB-CNT hybrid fillers is established.

Reproducibility of up-flow column percolation tests for contaminated soils.

Directory of Open Access Journals (Sweden)

Tetsuo Yasutaka

Full Text Available Up-flow column percolation tests are used at laboratory scale to assess the leaching behavior of hazardous substance from contaminated soils in a specific condition as a function of time. Monitoring the quality of these test results inter or within laboratory is crucial, especially if used for Environment-related legal policy or for routine testing purposes. We tested three different sandy loam type soils (Soils I, II and III to determine the reproducibility (variability inter laboratory of test results and to evaluate the difference in the test results within laboratory. Up-flow column percolation tests were performed following the procedure described in the ISO/TS 21268-3. This procedure consists of percolating solution (calcium chloride 1 mM from bottom to top at a flow rate of 12 mL/h through softly compacted soil contained in a column of 5 cm diameter and 30 ± 5 cm height. Eluate samples were collected at liquid-to-solid ratio of 0.1, 0.2, 0.5, 1, 2, 5 and 10 L/kg and analyzed for quantification of the target elements (Cu, As, Se, Cl, Ca, F, Mg, DOC and B in this research. For Soil I, 17 institutions in Japan joined this validation test. The up-flow column experiments were conducted in duplicate, after 48 h of equilibration time and at a flow rate of 12 mL/h. Column percolation test results from Soils II and III were used to evaluate the difference in test results from the experiments conducted in duplicate in a single laboratory, after 16 h of equilibration time and at a flow rate of 36 mL/h. Overall results showed good reproducibility (expressed in terms of the coefficient of variation, CV, calculated by dividing the standard deviation by the mean, as the CV was lower than 30% in more than 90% of the test results associated with Soil I. Moreover, low variability (expressed in terms of difference between the two test results divided by the mean was observed in the test results related to Soils II and III, with a variability lower than 30

Percolation transitions in two dimensions

NARCIS (Netherlands)

Feng, X.; Deng, Y.; Blöte, H.W.J.

2008-01-01

We investigate bond- and site-percolation models on several two-dimensional lattices numerically, by means of transfer-matrix calculations and Monte Carlo simulations. The lattices include the square, triangular, honeycomb kagome, and diced lattices with nearest-neighbor bonds, and the square

Long range correlations, event simulation and parton percolation

International Nuclear Information System (INIS)

Pajares, C.

2011-01-01

We study the RHIC data on long range rapidity correlations, comparing their main trends with different string model simulations. Particular attention is paid to color percolation model and its similarities with color glass condensate. As both approaches corresponds, at high density, to a similar physical picture, both of them give rise to a similar behavior on the energy and the centrality of the main observables. Color percolation explains the transition from low density to high density.

Percolation-enhanced nonlinear scattering from semicontinuous metal films

Science.gov (United States)

Breit, M.; von Plessen, G.; Feldmann, J.; Podolskiy, V. A.; Sarychev, A. K.; Shalaev, V. M.; Gresillon, S.; Rivoal, J. C.; Gadenne, P.

2001-03-01

Strongly enhanced second-harmonic generation (SHG), which is characterized by nearly isotropic distribution, is observed for gold-glass films near the percolation threshold. The diffuse-like SHG scattering, which can be thought of as nonlinear critical opalescence, is in sharp contrast with highly collimated linear reflection and transmission from these nanostructured semicontinuous metal films. Our observations, which can be explained by giant fluctuations of local nonlinear sources for SHG, verify recent predictions of percolation-enhanced nonlinear scattering.

Effective modelling of percolation at the landscape scale using data-based approaches

Science.gov (United States)

Selle, Benny; Lischeid, Gunnar; Huwe, Bernd

2008-06-01

Process-based models have been extensively applied to assess the impact of landuse change on water quantity and quality at landscape scales. However, the routine application of those models suffers from large computational efforts, lack of transparency and the requirement of many input parameters. Data-based models such as Feed-Forward Multilayer Perceptrons (MLP) and Classification and Regression Trees (CART) may be used as effective models, i.e. simple approximations of complex process-based models. These data-based approaches can subsequently be applied for scenario analysis and as a transparent management tool provided climatic boundary conditions and the basic model assumptions of the process-based models do not change dramatically. In this study, we apply MLP, CART and Multiple Linear Regression (LR) to model the spatially distributed and spatially aggregated percolation in soils using weather, groundwater and soil data. The percolation data is obtained via numerical experiments with Hydrus1D. Thus, the complex process-based model is approximated using simpler data-based approaches. The MLP model explains most of the percolation variance in time and space without using any soil information. This reflects the effective dimensionality of the process-based model and suggests that percolation in the study area may be modelled much simpler than using Hydrus1D. The CART model shows that soil properties play a negligible role for percolation under wet climatic conditions. However, they become more important if the conditions turn drier. The LR method does not yield satisfactory predictions for the spatially distributed percolation however the spatially aggregated percolation is well approximated. This may indicate that the soils behave simpler (i.e. more linear) when percolation dynamics are upscaled.

Charge transport in conjugated polymer-semiconductor nanoparticle composite near the percolation threshold

Science.gov (United States)

Cardoso, L. S.; Gonçalves, G. E.; Kanda, D. H. F.; Bianchi, R. F.; Nagashima, H. N.

2017-12-01

This paper describes a new statistical model to predict the frequency dependence of the conductivity of conjugated polymer-semiconductor nanoparticle composites. The model considers AC conduction in an inhomogeneous medium represented by a two-dimensional model of resistor network. The conductivity between two neighboring sites in the polymer matrix and the semiconductor particles is assumed to obey the random free energy barrier model and the Drude model, respectively. The real and imaginary parts of the AC conductivity were determined using the transfer-matrix technique, and the statistical model was applied to experimental data of thin films composed of polyaniline (PANI) and indium-tin-oxide (ITO) nanoparticles. The conductivity critical exponent ( s) obtained in two dimensions for PANI/ITO films below the percolation threshold was found to be 2.7, which is greater than the universal value of s described by the classical percolation theory ( s = 1.3). This non-universality is explained by the existence of a local electric field distribution in the bulk of the nanocomposite. Finally, these results are discussed in terms of the distribution of potential barriers that vary according to the concentration of ITO amount in the composite.

Phenomenology of quarkyonic percolation at FAIR

International Nuclear Information System (INIS)

Torrieri, Giorgio; Lottini, Stefano

2013-01-01

We will give an introduction to the concept of quarkyonic matter, presenting an overview of what is meant by this term in the literature. We will then argue that the quarkyonic phase, as defined in the original paper, is a percolation-type phase transition whose phase transition line is strongly curved in ρ B − N c space, where N C is the number of colors and ρ B the baryon density. With a toy model estimate, we show that it might be possible to obtain a percolating but confined phase at N c = 3, N f = 2 at densities larger than one baryon per one baryon size. We conclude by discussing how this phase can be observed at FAIR.

Inactivation of VHSV by Percolation and Salt Under Experimental Conditions

DEFF Research Database (Denmark)

Skall, Helle Frank; Olesen, Niels Jørgen; Jørgensen, Claus

2012-01-01

At the moment the only legal method in Denmark to sanitize wastewater from fish cutting plants is by percolation. To evaluate the inactivation effect of percolation on VHSV an experimental examination was initiated. A column packed with gravel as top- and bottom layer (total of 22 cm) and a mid l...

Percolation and nucleation approaches to nuclear fragmentation: criticality in very small systems

Energy Technology Data Exchange (ETDEWEB)

Santiago, A.J. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Chung, K.C.

1994-12-01

Different criteria for criticality in very small systems are discussed in the context of percolation and nucleation approaches to nuclear fragmentation. It is shown that the probability threshold in percolation and interaction radius threshold in nucleation are very strongly dependent upon the adopted criterion. By using Monte Carlo method, similarities and dissimilarities between nucleation and percolation pictures are also pointed out. (author). 17 refs, 5 figs, 2 tabs.

Percolation and nucleation approaches to nuclear fragmentation: criticality in very small systems

International Nuclear Information System (INIS)

Santiago, A.J.; Chung, K.C.

1994-12-01

Different criteria for criticality in very small systems are discussed in the context of percolation and nucleation approaches to nuclear fragmentation. It is shown that the probability threshold in percolation and interaction radius threshold in nucleation are very strongly dependent upon the adopted criterion. By using Monte Carlo method, similarities and dissimilarities between nucleation and percolation pictures are also pointed out. (author). 17 refs, 5 figs, 2 tabs

The percolation effect and optimization of soft magnetic properties of FeSiAl magnetic powder cores

Energy Technology Data Exchange (ETDEWEB)

Bai, Ruru [College of Material Science and Engineering, Nanchang University, Nanchang 330031, Jiangxi (China); Zhu, Zhenghou, E-mail: z00708@sina.com [College of Material Science and Engineering, Nanchang University, Nanchang 330031, Jiangxi (China); Zhao, Hui, E-mail: candyzhaohui@126.com [College of Material Science and Engineering, Nanchang University, Nanchang 330031, Jiangxi (China); Institute of Space Science and Technology, Nanchang University, Nanchang 330031, Jiangxi (China); Mao, Shenghua [Jiangxi Aite magnetic materials Co. Ltd., Yichun 336000, Jiangxi (China); Zhong, Qi [College of Material Science and Engineering, Nanchang University, Nanchang 330031, Jiangxi (China)

2017-07-01

Highlights: • A new magnetic percolation phenomenon of ρ-μe in MPCs was discovered. • The soft magnetic properties of FeSiAl MPCs were studied. • The comprehensive magnetic properties of MPCs were optimized. • The formation mechanism of magnetic conductive path was explained. - Abstract: In this paper, a new magnetic percolation phenomenon between the green compact density ρ and effective permeability μe in FeSi{sub 9.6}Al{sub 6.5} magnetic powder cores, was discovered. The Magnetic Percolation Area of ρ is the range of 5.6 g/cm{sup 3} ∼ 5.78 g/cm{sup 3}, and the percolation threshold is 5.78 g/cm{sup 3}. As a result of the guidance of the percolation theory, the best comprehensive magnetic properties have been optimized through adjusting the distribution of powders. The special distribution of the magnetic powder cores with the best comprehensive magnetic properties was as follows: the content 60% with the particle size distribution of 100–200 mesh, the content 20% with the particle size distribution of 200–325 mesh and the content 20% with the particle size distribution of ≥400 mesh. When the green compact density ρ of cores was 5.79 g/cm{sup 3}, and the frequency was in the range of 1 kHz ∼ 100 kHz, the best comprehensive magnetic properties were as follows: μe = 91, ∆μ = 0.61%, μe(H80 Oe) = 43, μe(H100 Oe) = 33, μe(H120 Oe) = 26, Pc(50 mT/20 kHz) = 30.58 kW/m{sup 3}, Pc(50 mT/50 kHz) = 76.85 kW/m{sup 3}, Pc(50 mT/100 kHz) = 178 kW/m{sup 3}. Not only have those cores the excellent constant magnetic properties with frequency, the excellent DC superposition characteristic and the lower loss at high frequency, but also the effective permeability outstandingly goes up, which has important significance for the miniaturization of inductance components.

Electrical characteristics of silicon percolating nanonet-based field effect transistors in the presence of dispersion

Science.gov (United States)

Cazimajou, T.; Legallais, M.; Mouis, M.; Ternon, C.; Salem, B.; Ghibaudo, G.

2018-05-01

We studied the current-voltage characteristics of percolating networks of silicon nanowires (nanonets), operated in back-gated transistor mode, for future use as gas or biosensors. These devices featured P-type field-effect characteristics. It was found that a Lambert W function-based compact model could be used for parameter extraction of electrical parameters such as apparent low field mobility, threshold voltage and subthreshold slope ideality factor. Their variation with channel length and nanowire density was related to the change of conduction regime from direct source/drain connection by parallel nanowires to percolating channels. Experimental results could be related in part to an influence of the threshold voltage dispersion of individual nanowires.

Soil Respiration Controls Ionic Nutrient Concentration In Percolating Water In Rice Fields

Science.gov (United States)

Kimura, M.

2004-12-01

Soil water in the plow layer in rice fields contains various kinds of cations and anions, and they are lost from the plow layer by water percolation. Some portions of CO2 produced by respirations of rice roots and soil microorganisms are also leached by water percolation to the subsoil layer as HCO3-. As the electrical neutrality of inorganic substances in percolating water is maintained when they are assumed to be in the form of simple cations and anions, soil respiration accelerates the leaching of ionic nutrients from the plow layer by water percolation. The proportion of inorganic carbon (Σ CO2) originated from photosynthates in the total Σ CO2 in soil solution in the plow layer was from 28 to 36 % in the rice straw amended soil and from 16 to 31 % in the soil without rice straw amendment in a soil pot experiment with rice plant after the maximum tillering stage. Most of Σ CO2 in percolating water from the plow layer accumulates in the subsoil layer. Periodical measurement of Σ CO2 in percolating water at 13 and 40 cm soil depths indicated that 10 % of total soil organic C in the plow layer was leached down from the plow layer (13 cm), and that about 90 % of it was retained in the subsoil layer to the depth of 40 cm. Water soluble organic materials are also leached from the plow layer by water percolation, and the leaching is accelerated by soil reduction. Soil reduction decreased the content of organic materials that were bound with ferric iron in soil (extractable by 0.1M Na4P2O7 + NaBH4) and increased the content of organic materials that were extractable by the neutral chelating solution (0.1M Na4P2O7). In addition, water percolation transformed the latter organic materials to those that were extractable by water and a neutral salt. Considerable portions of organic materials in percolating water are adsorbed in the subsoil layer, and then partially decomposed and polymerized to specific soil organic materials in the subsoil. Organic materials that were

Percolation processes

International Nuclear Information System (INIS)

Kunz, H.

1980-01-01

Percolation is a unifying which appeared to be rather useful in trying to understand some properties of disordered physical systems, or some phase transitions in polymers, like gelation or vulcanisation. Although implicitely used in the pioneering work of Flory in 1941 on the sol-gel transition of polymers, it was first introduced in a well-defined way by the mathematicians Hammersley and Broadbent in 1957, who obtained the first rigorous result. Since then, the subject has seen a variety of new applications and its recent study has largely benefited from the vigorous development of critical phenomena after the introduction of the RG ideas and techniques. (author)

A Matter of Time: Faster Percolator Analysis via Efficient SVM Learning for Large-Scale Proteomics.

Science.gov (United States)

Halloran, John T; Rocke, David M

2018-05-04

Percolator is an important tool for greatly improving the results of a database search and subsequent downstream analysis. Using support vector machines (SVMs), Percolator recalibrates peptide-spectrum matches based on the learned decision boundary between targets and decoys. To improve analysis time for large-scale data sets, we update Percolator's SVM learning engine through software and algorithmic optimizations rather than heuristic approaches that necessitate the careful study of their impact on learned parameters across different search settings and data sets. We show that by optimizing Percolator's original learning algorithm, l 2 -SVM-MFN, large-scale SVM learning requires nearly only a third of the original runtime. Furthermore, we show that by employing the widely used Trust Region Newton (TRON) algorithm instead of l 2 -SVM-MFN, large-scale Percolator SVM learning is reduced to nearly only a fifth of the original runtime. Importantly, these speedups only affect the speed at which Percolator converges to a global solution and do not alter recalibration performance. The upgraded versions of both l 2 -SVM-MFN and TRON are optimized within the Percolator codebase for multithreaded and single-thread use and are available under Apache license at bitbucket.org/jthalloran/percolator_upgrade .

Pseudo-random-number generators and the square site percolation threshold.

Science.gov (United States)

Lee, Michael J

2008-09-01

Selected pseudo-random-number generators are applied to a Monte Carlo study of the two-dimensional square-lattice site percolation model. A generator suitable for high precision calculations is identified from an application specific test of randomness. After extended computation and analysis, an ostensibly reliable value of p_{c}=0.59274598(4) is obtained for the percolation threshold.

Leveraging percolation theory to single out influential spreaders in networks

Science.gov (United States)

Radicchi, Filippo; Castellano, Claudio

2016-06-01

Among the consequences of the disordered interaction topology underlying many social, technological, and biological systems, a particularly important one is that some nodes, just because of their position in the network, may have a disproportionate effect on dynamical processes mediated by the complex interaction pattern. For example, the early adoption of a commercial product by an opinion leader in a social network may change its fate or just a few superspreaders may determine the virality of a meme in social media. Despite many recent efforts, the formulation of an accurate method to optimally identify influential nodes in complex network topologies remains an unsolved challenge. Here, we present the exact solution of the problem for the specific, but highly relevant, case of the susceptible-infected-removed (SIR) model for epidemic spreading at criticality. By exploiting the mapping between bond percolation and the static properties of the SIR model, we prove that the recently introduced nonbacktracking centrality is the optimal criterion for the identification of influential spreaders in locally tree-like networks at criticality. By means of simulations on synthetic networks and on a very extensive set of real-world networks, we show that the nonbacktracking centrality is a highly reliable metric to identify top influential spreaders also in generic graphs not embedded in space and for noncritical spreading.

Critical current simulation in granular superconductors above the percolation threshold

Science.gov (United States)

Riedinger, Roland

1992-02-01

In the phase-coherent regime without applied external magnetic field, the critical superconducting current is limited by intragranular junctions which behave like Josephson junctions. We study the percolation aspects specific to lattices of such junctions and/or the mixing of superconductor with normal grains by averaging over configurations. We illustrate on 2 and 3 dimensional examples. The power laws valid near the percolation threshold are valid well above it, in two and three dimensions. We discuss the other models limiting the superconducting current, the vortex creep and superconducting order parameter fluctuations. Dans la limite de champ magnétique nul et de cohérence de phase du paramètre d'ordre supraconducteur, le courant supraconducteur maximal dans un réseau est limité par les jonctions intergranulaires qui se comportent comme des jonctions Josephson. Nous analysons les problèmes de percolation spécifiques aux réseaux de jonctions et du mélange de grains normaux et supraconducteurs. Nous donnons des exemples bidimensionnels et tridimensionnels ; après moyenne sur les configurations et analyse en taille finie, nous montrons que les lois de puissance valables au voisinage du seuil de percolation s'étendent sur un grand domaine au-delà du seuil de percolation, à deux et trois dimensions. Nous discutons les autres modèles limitant le courant supraconducteur, ancrage de vortex et fluctuations du paramètre d'ordre.

Statistical analysis and Monte Carlo simulation of growing self-avoiding walks on percolation

Energy Technology Data Exchange (ETDEWEB)

Zhang Yuxia [Department of Physics, Wuhan University, Wuhan 430072 (China); Sang Jianping [Department of Physics, Wuhan University, Wuhan 430072 (China); Department of Physics, Jianghan University, Wuhan 430056 (China); Zou Xianwu [Department of Physics, Wuhan University, Wuhan 430072 (China)]. E-mail: xwzou@whu.edu.cn; Jin Zhunzhi [Department of Physics, Wuhan University, Wuhan 430072 (China)

2005-09-26

The two-dimensional growing self-avoiding walk on percolation was investigated by statistical analysis and Monte Carlo simulation. We obtained the expression of the mean square displacement and effective exponent as functions of time and percolation probability by statistical analysis and made a comparison with simulations. We got a reduced time to scale the motion of walkers in growing self-avoiding walks on regular and percolation lattices.

Quantum relativity theory

International Nuclear Information System (INIS)

Banai, M.

1983-11-01

A quantum relativity theory formulated in terms of Davis' quantum relativity principle is outlined. The first task in this theory as in classical relativity theory is to model space-time, the arena of natural processes. It is argued that the quantum space-time models of Banai introduced in an earlier paper is formulated in terms of Davis' quantum relativity. Then it is shown that the recently proposed classical relativistic quantum theory of Prugovecki and his corresponding classical relativistic quantum model of space-time open the way to introduce in a consistent way the quantum space-time model (the 'canonically quantized Minkowski space') proposed by Banai earlier. The main new aspect of the quantum mechanics of the quantum relativistic particles is, in this model of space-time, that it provides a true mass eigenvalue problem and, that the excited mass states of such particles can be interpreted as classifically relativistic (massive) quantum particles ('elementary particles'). The question of field theory over quantum relativistic models of space-time is also discussed. Finally, it is suggested that 'quarks' should be considered as quantum relativistic particles. (author)

Relativity theory - topical

International Nuclear Information System (INIS)

Schmutzer, E.

1979-01-01

Issued on the occasion of Albert Einstein's 100th birthday the book deals topically with the special and general relativity theory. The latest experiments to confirm the relativity theory are described and the historical development of the theory is presented in detail. Emphasis is given to the disclosure of deep insights into the nature of matter. Of interest to experts in physical and natural sciences and to mathematicians

A percolation approach to study the high electric field effect on electrical conductivity of insulating polymer

Science.gov (United States)

Benallou, Amina; Hadri, Baghdad; Martinez-Vega, Juan; El Islam Boukortt, Nour

2018-04-01

The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework.

Standard and inverse bond percolation of straight rigid rods on square lattices

Science.gov (United States)

Ramirez, L. S.; Centres, P. M.; Ramirez-Pastor, A. J.

2018-04-01

Numerical simulations and finite-size scaling analysis have been carried out to study standard and inverse bond percolation of straight rigid rods on square lattices. In the case of standard percolation, the lattice is initially empty. Then, linear bond k -mers (sets of k linear nearest-neighbor bonds) are randomly and sequentially deposited on the lattice. Jamming coverage pj ,k and percolation threshold pc ,k are determined for a wide range of k (1 ≤k ≤120 ). pj ,k and pc ,k exhibit a decreasing behavior with increasing k , pj ,k →∞=0.7476 (1 ) and pc ,k →∞=0.0033 (9 ) being the limit values for large k -mer sizes. pj ,k is always greater than pc ,k, and consequently, the percolation phase transition occurs for all values of k . In the case of inverse percolation, the process starts with an initial configuration where all lattice bonds are occupied and, given that periodic boundary conditions are used, the opposite sides of the lattice are connected by nearest-neighbor occupied bonds. Then, the system is diluted by randomly removing linear bond k -mers from the lattice. The central idea here is based on finding the maximum concentration of occupied bonds (minimum concentration of empty bonds) for which connectivity disappears. This particular value of concentration is called the inverse percolation threshold pc,k i, and determines a geometrical phase transition in the system. On the other hand, the inverse jamming coverage pj,k i is the coverage of the limit state, in which no more objects can be removed from the lattice due to the absence of linear clusters of nearest-neighbor bonds of appropriate size. It is easy to understand that pj,k i=1 -pj ,k . The obtained results for pc,k i show that the inverse percolation threshold is a decreasing function of k in the range 1 ≤k ≤18 . For k >18 , all jammed configurations are percolating states, and consequently, there is no nonpercolating phase. In other words, the lattice remains connected even when

Fractional scaling of quantum walks on percolation lattices

International Nuclear Information System (INIS)

Kendon, Viv; Knott, Paul; Leung, Godfrey; Bailey, Joe

2011-01-01

Quantum walks can be used to model processes such as transport in spin chains and bio-molecules. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections. Using numerical simulation, we study the spreading properties of quantum walks on percolation lattices for both bond and site percolation. The randomly missing edges or sites provide a controlled amount of disorder in the regular Cartesian lattice. In one dimension (the line) we introduce a simple model of quantum tunneling to allow the walk to proceed past the missing edges or sites. This allows the quantum walk to spread faster than a classical random walk for short times, but at longer times the disorder localises the quantum walk. In two dimensions, we observe fractional scaling of the spreading with the number of steps of the walk. For percolation above the 85% level, we obtain faster spreading than classical random walks on the full lattice.

Effect of sorbic acid doping on flux pinning in bulk MgB2 with the percolation model

International Nuclear Information System (INIS)

Yang, Y.; Cheng, C.H.; Wang, L.; Sun, H.H.; Zhao, Y.

2010-01-01

In this paper, we study the doping effect of sorbic acid (C 6 H 8 O 2 ), from 0 to 20 wt.% of the total MgB 2 , on critical temperature (T c ), critical current density (J c ), irreversibility field (H irr ) and crystalline structure. The XRD patterns of samples show a slightly decrease in a-axis lattice parameter for doped samples, due to the partial substitution of carbon at boron site. On the other hand, we investigate the influence of doping on the behavior of flux pinning and J c (B) in the framework of percolation theory and it is found that the J c (B) behavior could be well fitted in high field region. The two key parameters, anisotropy and percolation threshold, play very important roles. It is believed that the enhancement of J c is due to the reduction of anisotropy in high field region.

Loopless nontrapping invasion-percolation model for fracking.

Science.gov (United States)

Norris, J Quinn; Turcotte, Donald L; Rundle, John B

2014-02-01

Recent developments in hydraulic fracturing (fracking) have enabled the recovery of large quantities of natural gas and oil from old, low-permeability shales. These developments include a change from low-volume, high-viscosity fluid injection to high-volume, low-viscosity injection. The injected fluid introduces distributed damage that provides fracture permeability for the extraction of the gas and oil. In order to model this process, we utilize a loopless nontrapping invasion percolation previously introduced to model optimal polymers in a strongly disordered medium and for determining minimum energy spanning trees on a lattice. We performed numerical simulations on a two-dimensional square lattice and find significant differences from other percolation models. Additionally, we find that the growing fracture network satisfies both Horton-Strahler and Tokunaga network statistics. As with other invasion percolation models, our model displays burst dynamics, in which the cluster extends rapidly into a connected region. We introduce an alternative definition of bursts to be a consecutive series of opened bonds whose strengths are all below a specified value. Using this definition of bursts, we find good agreement with a power-law frequency-area distribution. These results are generally consistent with the observed distribution of microseismicity observed during a high-volume frack.

Percolation and lasing in real 3D crystals with inhomogeneous distributed random pores

Energy Technology Data Exchange (ETDEWEB)

Burlak, Gennadiy, E-mail: gburlak@uaem.mx; Calderón-Segura, Yessica

2014-11-15

We systematically study the percolation phase transition in real 3D crystals where not only the state of pores but also their radius r and displacement s are random valued numbers. The mean values R=〈r〉 and S=〈s〉 emerge as additional spatial scales in such an extended network. This leads to variations of the threshold (critical) percolation probability p{sub C} and the percolation order parameter P that become to be the intricate functions of R and S. Our numerical simulations have shown that in such extended system the incipient spanning cluster can arise even for situations where for simple periodical system the percolation does not exist. We analyzed the validity of the nearest neighbor's approximation and found that such approximation is not valid for materials with large dispersivity of pores. The lasing of nanoemitters incorporated in such percolating spanning cluster is studied too. This effect can open interesting perspectives in modern nano- and micro-information technologies.

The Beasts' model of percolative transport

International Nuclear Information System (INIS)

Dubois, M.A.; Beaufume, P.; Fromont, B.

1991-12-01

A class of nonlinear dynamical systems is introduced: it is aimed to be a tool in order to study anomalous transport and percolation phenomena. We study a simple example of this system, and explore different regimes of transport exhibited

Invasion percolation of single component, multiphase fluids with lattice Boltzmann models

International Nuclear Information System (INIS)

Sukop, M.C.; Or, Dani

2003-01-01

Application of the lattice Boltzmann method (LBM) to invasion percolation of single component multiphase fluids in porous media offers an opportunity for more realistic modeling of the configurations and dynamics of liquid/vapor and liquid/solid interfaces. The complex geometry of connected paths in standard invasion percolation models arises solely from the spatial arrangement of simple elements on a lattice. In reality, fluid interfaces and connectivity in porous media are naturally controlled by the details of the pore geometry, its dynamic interaction with the fluid, and the ambient fluid potential. The multiphase LBM approach admits realistic pore geometry derived from imaging techniques and incorporation of realistic hydrodynamics into invasion percolation models

Special theory of relativity

CERN Document Server

Kilmister, Clive William

1970-01-01

Special Theory of Relativity provides a discussion of the special theory of relativity. Special relativity is not, like other scientific theories, a statement about the matter that forms the physical world, but has the form of a condition that the explicit physical theories must satisfy. It is thus a form of description, playing to some extent the role of the grammar of physics, prescribing which combinations of theoretical statements are admissible as descriptions of the physical world. Thus, to describe it, one needs also to describe those specific theories and to say how much they are limit

On the relation of the theoretical foundations of quantum theory and general relativity theory

International Nuclear Information System (INIS)

Kober, Martin

2010-01-01

The specific content of the present thesis is presented in the following way. First the most important contents of quantum theory and general relativity theory are presented. In connection with the general relativity theory the mathematical property of the diffeomorphism invariance plays the deciding role, while concerning the quantum theory starting from the Copenhagen interpretation first the measurement problem is treated, before basing on the analysis of concrete phenomena and the mathematical apparatus of quantum theory the nonlocality is brought into focus as an important property. This means that both theories suggest a relationalistic view of the nature of the space. This analysis of the theoretical foundations of quantum theory and general relativity theory in relation to the nature of the space obtains only under inclusion of Kant's philosophy and his analysis of the terms space and time as fundamental forms of perception its full persuasive power. Then von Weizsaeckers quantum theory of the ur-alternatives is presented. Finally attempts are made to apply the obtained knowledge to the question of the quantum-theoretical formulation of general relativity theory.

Percolation and multifragmentation of nuclei

International Nuclear Information System (INIS)

Shmakov, S.Yu.; Uzhinskij, V.V.

1989-01-01

A method to build the 'cold' nuclei as percolation clusters is suggested. Within the framework of definite assumptions of the character of nucleon-nucleon couplings breaking resulting from the nuclear reactions as description of the multifragmentation process in the hadron-nucleus and nucleus-nucleus reactions at high energies is obtained. 19 refs.; 6 figs

Features of the Percolation Scheme of Vibrational Spectrum Reconstruction in the Ga1 - x Al x P Alloy

Science.gov (United States)

Kozyrev, S. P.

2018-04-01

Specific features of the properties of Ga-P lattice vibrations have been investigated using the percolation model of a mixed Ga1 - x Al x P crystal (alloy) with zero lattice mismatch between binary components of the alloy. In contrast to other two-mode alloy systems, in Ga1 - x Al x P a percolation splitting of δ 13 cm-1 is observed for the low-frequency mode of GaP-like vibrations. An additional GaP mode (one of the percolation doublet components) split from the fundamental mode is observed for the GaP-rich alloy, which coincides in frequency with the gap corresponding to the zero density of one-phonon states of the GaP crystal. The vibrational spectrum of impurity Al in the GaP crystal has been calculated using the theory of crystal lattice dynamics. Upon substitution of lighter Al for the Ga atom, the calculated spectrum includes, along with the local mode, a singularity near the gap with the zero density of phonon states of the GaP crystal, which coincides with the mode observed experimentally at a frequency of 378 cm-1 in the Ga1 - x Al x P ( x < 0.4) alloy.

Capillary condensation, invasion percolation, hysteresis, and discrete memory

International Nuclear Information System (INIS)

Guyer, R.A.; McCall, K.R.

1996-01-01

A model of the capillary condensation process, i.e., of adsorption-desorption isotherms, having only pore-pore interactions is constructed. The model yields (1) hysteretic isotherms, (2) invasion percolation on desorption, and (3) hysteresis with discrete memory for interior chemical potential loops. All of these features are seen in experiment. The model is compared to a model with no pore-pore interactions (the Preisach model) and to a related model of interacting pore systems (the random field Ising model). The capillary condensation model differs from both. copyright 1996 The American Physical Society

High Efficiency, Transparent, Reusable, and Active PM2.5 Filters by Hierarchical Ag Nanowire Percolation Network.

Science.gov (United States)

Jeong, Seongmin; Cho, Hyunmin; Han, Seonggeun; Won, Phillip; Lee, Habeom; Hong, Sukjoon; Yeo, Junyeob; Kwon, Jinhyeong; Ko, Seung Hwan

2017-07-12

Air quality has become a major public health issue in Asia including China, Korea, and India. Particulate matters are the major concern in air quality. We present the first environmental application demonstration of Ag nanowire percolation network for a novel, electrical type transparent, reusable, and active PM2.5 air filter although the Ag nanowire percolation network has been studied as a very promising transparent conductor in optoelectronics. Compared with previous particulate matter air filter study using relatively weaker short-range intermolecular force in polar polymeric nanofiber, Ag nanowire percolation network filters use stronger long-range electrostatic force to capture PM2.5, and they are highly efficient (>99.99%), transparent, working on an active mode, low power consumption, antibacterial, and reusable after simple washing. The proposed new particulate matter filter can be applied for a highly efficient, reusable, active and energy efficient filter for wearable electronics application.

Percolation and spin glass transition

International Nuclear Information System (INIS)

Sadiq, A.; Tahir-Kheli, R.A.; Wortis, M.; Bhatti, N.A.

1980-10-01

The behaviour of clusters of curved and normal plaquette particles in a bond random, +-J, Ising model is studied in finite square and triangular lattices. Computer results for the concentration of antiferromagnetic bonds when percolating clusters first appears are found to be close to those reported for the occurrence and disappearance of spin glass phases in these systems. (author)

Inequality for the infinite-cluster density in Bernoulli percolation

International Nuclear Information System (INIS)

Chayes, J.T.; Chayes, L.

1986-01-01

Under a certain assumption (which is satisfied whenever there is a dense infinite cluster in the half-space), we prove a differential inequality for the infinite-cluster density, P/sub infinity/(p), in Bernoulli percolation. The principal implication of this result is that if P/sub infinity/(p) vanishes with critical exponent β, then β obeys the mean-field bound β< or =1. As a corollary, we also derive an inequality relating the backbone density, the truncated susceptibility, and the infinite-cluster density

Current Percolation in Medium with Boundaries under Quantum Hall Effect Conditions

Directory of Open Access Journals (Sweden)

M. U. Malakeeva

2012-01-01

Full Text Available The current percolation has been considered in the medium with boundaries under quantum Hall effect conditions. It has been shown that in that case the effective Hall conductivity has a nonzero value due to percolation of the Hall current through the finite number of singular points (in our model these are corners at the phase joints.

Walking on fractals: diffusion and self-avoiding walks on percolation clusters

International Nuclear Information System (INIS)

Blavatska, V; Janke, W

2009-01-01

We consider random walks (RWs) and self-avoiding walks (SAWs) on disordered lattices directly at the percolation threshold. Applying numerical simulations, we study the scaling behavior of the models on the incipient percolation cluster in space dimensions d = 2, 3, 4. Our analysis yields estimates of universal exponents, governing the scaling laws for configurational properties of RWs and SAWs

Mirrorless lasing from light emitters in percolating clusters

Science.gov (United States)

Burlak, Gennadiy; Rubo, Y. G.

2015-07-01

We describe the lasing effect in the three-dimensional percolation system, where the percolating cluster is filled by active media composed by light emitters excited noncoherently. We show that, due to the presence of a topologically nontrivial photonic structure, the stimulated emission is modified with respect to both conventional and random lasers. The time dynamics and spectra of the lasing output are studied numerically with finite-difference time-domain approach. The Fermat principle and Monte Carlo approach are applied to characterize the optimal optical path and interconnection between the radiating emitters. The spatial structure of the laser mode is found by a long-time FDTD simulation.

Ising percolation in a three-state majority vote model

Energy Technology Data Exchange (ETDEWEB)

Balankin, Alexander S., E-mail: abalankin@ipn.mx [Grupo Mecánica Fractal, ESIME, Instituto Politécnico Nacional, México D.F., 07738 (Mexico); Martínez-Cruz, M.A.; Gayosso Martínez, Felipe [Grupo Mecánica Fractal, ESIME, Instituto Politécnico Nacional, México D.F., 07738 (Mexico); Mena, Baltasar [Laboratorio de Ingeniería y Procesos Costeros, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Sisal, Yucatán, 97355 (Mexico); Tobon, Atalo; Patiño-Ortiz, Julián; Patiño-Ortiz, Miguel; Samayoa, Didier [Grupo Mecánica Fractal, ESIME, Instituto Politécnico Nacional, México D.F., 07738 (Mexico)

2017-02-05

Highlights: • Three-state non-consensus majority voter model is introduced. • Phase transition in the absorbing state non-consensus is revealed. • The percolation transition belongs to the universality class of Ising percolation. • The effect of an updating rule for a tie between voter neighbors is highlighted. - Abstract: In this Letter, we introduce a three-state majority vote model in which each voter adopts a state of a majority of its active neighbors, if exist, but the voter becomes uncommitted if its active neighbors are in a tie, or all neighbors are the uncommitted. Numerical simulations were performed on square lattices of different linear size with periodic boundary conditions. Starting from a random distribution of active voters, the model leads to a stable non-consensus state in which three opinions coexist. We found that the “magnetization” of the non-consensus state and the concentration of uncommitted voters in it are governed by an initial composition of system and are independent of the lattice size. Furthermore, we found that a configuration of the stable non-consensus state undergoes a second order percolation transition at a critical concentration of voters holding the same opinion. Numerical simulations suggest that this transition belongs to the same universality class as the Ising percolation. These findings highlight the effect of an updating rule for a tie between voter neighbors on the critical behavior of models obeying the majority vote rule whenever a strict majority exists.

Ising percolation in a three-state majority vote model

International Nuclear Information System (INIS)

Balankin, Alexander S.; Martínez-Cruz, M.A.; Gayosso Martínez, Felipe; Mena, Baltasar; Tobon, Atalo; Patiño-Ortiz, Julián; Patiño-Ortiz, Miguel; Samayoa, Didier

2017-01-01

Highlights: • Three-state non-consensus majority voter model is introduced. • Phase transition in the absorbing state non-consensus is revealed. • The percolation transition belongs to the universality class of Ising percolation. • The effect of an updating rule for a tie between voter neighbors is highlighted. - Abstract: In this Letter, we introduce a three-state majority vote model in which each voter adopts a state of a majority of its active neighbors, if exist, but the voter becomes uncommitted if its active neighbors are in a tie, or all neighbors are the uncommitted. Numerical simulations were performed on square lattices of different linear size with periodic boundary conditions. Starting from a random distribution of active voters, the model leads to a stable non-consensus state in which three opinions coexist. We found that the “magnetization” of the non-consensus state and the concentration of uncommitted voters in it are governed by an initial composition of system and are independent of the lattice size. Furthermore, we found that a configuration of the stable non-consensus state undergoes a second order percolation transition at a critical concentration of voters holding the same opinion. Numerical simulations suggest that this transition belongs to the same universality class as the Ising percolation. These findings highlight the effect of an updating rule for a tie between voter neighbors on the critical behavior of models obeying the majority vote rule whenever a strict majority exists.

Interlocking-induced stiffness in stochastically microcracked materials beyond the transport percolation threshold

Science.gov (United States)

Picu, R. C.; Pal, A.; Lupulescu, M. V.

2016-04-01

We study the mechanical behavior of two-dimensional, stochastically microcracked continua in the range of crack densities close to, and above, the transport percolation threshold. We show that these materials retain stiffness up to crack densities much larger than the transport percolation threshold due to topological interlocking of sample subdomains. Even with a linear constitutive law for the continuum, the mechanical behavior becomes nonlinear in the range of crack densities bounded by the transport and stiffness percolation thresholds. The effect is due to the fractal nature of the fragmentation process and is not linked to the roughness of individual cracks.

Relative Thinking Theory

OpenAIRE

Ofer H. Azar

2005-01-01

The article presents a theory that I denote “Relative Thinking Theory,” which claims that people consider relative differences and not only absolute differences when making various economics decisions, even in those cases where the rational model dictates that people should consider only absolute differences. The article reviews experimental evidence for this behavior, summarizing briefly several experiments I conducted, as well as some earlier related literature. It then discusses how we can...

Spin wave and percolation studies in epitaxial La{sub 2/3}Sr{sub 1/3}MnO{sub 3} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Ettayfi, A. [LPMMAT, Faculté des Sciences Ain chock, Université Hassan II de Casablanca, B.P. 5366 Casablanca (Morocco); Moubah, R., E-mail: reda.moubah@hotmail.fr [LPMMAT, Faculté des Sciences Ain chock, Université Hassan II de Casablanca, B.P. 5366 Casablanca (Morocco); Hlil, E.K. [Institut Néel, CNRS, Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France); Colis, S.; Lenertz, M.; Dinia, A. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 UDS-CNRS (UDS-ECPM), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Lassri, H. [LPMMAT, Faculté des Sciences Ain chock, Université Hassan II de Casablanca, B.P. 5366 Casablanca (Morocco)

2016-07-01

We investigate the magnetic and transport properties of high quality La{sub 2/3}Sr{sub 1/3}MnO{sub 3} thin films grown by pulsed laser deposition. X-ray diffraction shows that the deposited films are epitaxial with the expected pseudo-cubic structure. Using the spin wave theory, the temperature dependence of magnetization was satisfactory modeled at low temperature, in which several fundamental magnetic parameters were obtained (spin wave stiffness, exchange constants, Fermi wave-vector, Mn–Mn interatomic distance). The transport properties were studied via the temperature dependence of electrical resistivity [ρ(T)], which shows a peak at Curie temperature due to metal to insulator transition. The percolation theory was used to simulate ρ(T) in both the ferromagnetic and paramagnetic phases. Reasonable agreement with the experimental data is reported. - Highlights: • The magnetic and transport properties of epitaxial La{sub 2/3}Sr{sub 1/3}MnO{sub 3} thin films are investigated. • The M(T) curve was modeled at low temperature, and several magnetic parameters were obtained using spin wave theory. • The percolation theory was used to simulate ρ(T) in both the ferromagnetic and paramagnetic phases.

Generalized bond percolation and statistical mechanics

International Nuclear Information System (INIS)

Tsallis, C.

1978-05-01

A generalization of traditional bond percolation is performed, in the sens that bonds have now the possibility of partially transmitting the information (a fact which leads to the concept of 'fidelity' of the bond), and also in the sens that, besides the normal tendency to equiprobability, the bonds are allowed to substantially change the information. Furthermore the fidelity is allowed, to become an aleatory variable, and the operational rules concerning the associated distribution laws are determined. Thermally quenched random bonds and the whole body of Statistical Mechanics become particular cases of this formalism, which is in general adapted to the treatment of all problems whose main characteristic is to preserve a part of the information through a long path or array (critical phenomena, regime changements, thermal random models, etc). Operationally it provides a quick method for the calculation of the equivalent probability of complex clusters within the traditional bond percolation problem [pt

Structural origin of fractional Stokes-Einstein relation in glass-forming liquids.

Science.gov (United States)

Pan, Shaopeng; Wu, Z W; Wang, W H; Li, M Z; Xu, Limei

2017-01-06

In many glass-forming liquids, fractional Stokes-Einstein relation (SER) is observed above the glass transition temperature. However, the origin of such phenomenon remains elusive. Using molecular dynamics simulations, we investigate the break- down of SER and the onset of fractional SER in a model of metallic glass-forming liquid. We find that SER breaks down when the size of the largest cluster consisting of trapped atoms starts to increase sharply at which the largest cluster spans half of the simulations box along one direction, and the fractional SER starts to follows when the largest cluster percolates the entire system and forms 3-dimentional network structures. Further analysis based on the percolation theory also confirms that percolation occurs at the onset of the fractional SER. Our results directly link the breakdown of the SER with structure inhomogeneity and onset of the fraction SER with percolation of largest clusters, thus provide a possible picture for the break- down of SER and onset of fractional SER in glass-forming liquids, which is is important for the understanding of the dynamic properties in glass-forming liquids.

Elements of relativity theory

International Nuclear Information System (INIS)

Lawden, D.F.

1985-01-01

The book on elements of relativity theory is intended for final year school students or as an early university course in mathematical physics. Special principle of relativity, lorentz transformation, velocity transformations, relativistic mechanics, and general theory of relativity, are all discussed. (U.K.)

Deep percolation in greenhouse-cultivated celery using the technique of subsurface film strips placement

Directory of Open Access Journals (Sweden)

Zhida Du

2014-05-01

Full Text Available To reduce the deep percolation during greenhouse vegetable cultivation, the technique of subsurface film strips placement was tested. Four treatments with two kinds of cross-sections (flat and U-shaped and two different spacings (10 cm and 40 cm of subsurface film strips were arranged in a greenhouse before planting celery. At the same time, a non-film treatment was arranged for comparison. Soil water content was measured and irrigation time was adjusted according to the soil water content. Evapotranspiration of celery during growth was calculated by the method of energy balance and the deep percolation was calculated by the equation of water balance. Deep percolation was reduced in all experimental treatments. Greater reduction in deep percolation was observed when using U-shaped cross-section strips compared with that using the flat cross-section strips. In addition, greater reduction in deep percolation was observed when the spacing between the film strips was smaller. The results of this test showed that the technique of subsurface film strips placement can reduce deep percolation and conserve irrigation water for greenhouse vegetables cultivation. However, the optimal layout variables for the use of the technique of subsurface film strips placement need further experimental and numerical analysis.

Multiscale volatility duration characteristics on financial multi-continuum percolation dynamics

Science.gov (United States)

Wang, Min; Wang, Jun

A random stock price model based on the multi-continuum percolation system is developed to investigate the nonlinear dynamics of stock price volatility duration, in an attempt to explain various statistical facts found in financial data, and have a deeper understanding of mechanisms in the financial market. The continuum percolation system is usually referred to be a random coverage process or a Boolean model, it is a member of a class of statistical physics systems. In this paper, the multi-continuum percolation (with different values of radius) is employed to model and reproduce the dispersal of information among the investors. To testify the rationality of the proposed model, the nonlinear analyses of return volatility duration series are preformed by multifractal detrending moving average analysis and Zipf analysis. The comparison empirical results indicate the similar nonlinear behaviors for the proposed model and the actual Chinese stock market.

The selected models of the mesostructure of composites percolation, clusters, and force fields

CERN Document Server

Herega, Alexander

2018-01-01

This book presents the role of mesostructure on the properties of composite materials. A complex percolation model is developed for the material structure containing percolation clusters of phases and interior boundaries. Modeling of technological cracks and the percolation in the Sierpinski carpet are described. The interaction of mesoscopic interior boundaries of the material, including the fractal nature of interior boundaries, the oscillatory nature of it interaction and also the stochastic model of the interior boundaries’ interaction, the genesis, structure, and properties are discussed. One of part of the book introduces the percolation model of the long-range effect which is based on the notion on the multifractal clusters with transforming elements, and the theorem on the field interaction of multifractals is described. In addition small clusters, their characteristic properties and the criterion of stability are presented.

Effect of particle size ratio on the conducting percolation threshold of granular conductive-insulating composites

International Nuclear Information System (INIS)

He Da; Ekere, N N

2004-01-01

In this paper, we apply Monte Carlo simulation to investigate the conductive percolation threshold of granular composite of conductive and insulating powders with amorphous structure. We focus on the effect of insulating to conductive particle size ratio λ = d i /d c on the conducting percolation threshold p c (the volume fraction of the conductive powder). Simulation results show that, for λ = 1, the percolation threshold p c lies between simple cubic and body centred cubic site percolation thresholds, and that as λ increases the percolation threshold decreases. We also use the structural information obtained by the simulation to study the nonlinear current-voltage characteristics of composite with solid volume fraction of conductive powder below p c in terms of electron tunnelling for nanoscale powders, dielectric breakdown for microscale or larger powders, and pressing induced conduction for non-rigid insulating powders

The importance of stress percolation patterns in rocks and other polycrystalline materials.

Science.gov (United States)

Burnley, P C

2013-01-01

A new framework for thinking about the deformation behavior of rocks and other heterogeneous polycrystalline materials is proposed, based on understanding the patterns of stress transmission through these materials. Here, using finite element models, I show that stress percolates through polycrystalline materials that have heterogeneous elastic and plastic properties of the same order as those found in rocks. The pattern of stress percolation is related to the degree of heterogeneity in and statistical distribution of the elastic and plastic properties of the constituent grains in the aggregate. The development of these stress patterns leads directly to shear localization, and their existence provides insight into the formation of rhythmic features such as compositional banding and foliation in rocks that are reacting or dissolving while being deformed. In addition, this framework provides a foundation for understanding and predicting the macroscopic rheology of polycrystalline materials based on single-crystal elastic and plastic mechanical properties.

Fragmentation of percolation cluster perimeters

Science.gov (United States)

Debierre, Jean-Marc; Bradley, R. Mark

1996-05-01

We introduce a model for the fragmentation of porous random solids under the action of an external agent. In our model, the solid is represented by a bond percolation cluster on the square lattice and bonds are removed only at the external perimeter (or `hull') of the cluster. This model is shown to be related to the self-avoiding walk on the Manhattan lattice and to the disconnection events at a diffusion front. These correspondences are used to predict the leading and the first correction-to-scaling exponents for several quantities defined for hull fragmentation. Our numerical results support these predictions. In addition, the algorithm used to construct the perimeters reveals itself to be a very efficient tool for detecting subtle correlations in the pseudo-random number generator used. We present a quantitative test of two generators which supports recent results reported in more systematic studies.

Percolation Model of Adhesion at Polymer Interfaces

Science.gov (United States)

Wool, Richard P.

1998-03-01

Adhesion at polymer interfaces is treated as a percolation problem, where an areal density of chains Σ, of length L, contribute a number of entanglements to the interface of thickness X. The fracture energy G, is determined by the fraction of entanglements P, fractured or disentangled in the deformation zone preceding the crack tip, via G ~ P-P_c, where Pc is the percolation threshold, given by Pc = 1- M_e/Mc . For incompatible A/B interfaces reinforced with Σ diblocks or random A-B copolymers of effective length L'(L' ~ 0 for brushes and strongly adsorbed chains), we obtain P ~ ΣL/X, Pc ~ Σ _cL/X, such that G = K(Σ - Σ _c)+ G_o, where K and Go ~ 1 J/m^2 are constants. Note that Log G vs Log Σ will have an apparent slope of about 2, incorrectly suggesting that G ~ Σ ^2. For cohesive fracture, disentanglement dominates at M M*, G = G*[1-M_c/M]. For fatigue crack propagation da/dN, at welding interfaces, we obtain da/dN ~ M-5/2(t/Tr)-5/4, where t is the welding time and Tr is the reptation time. For polymer-solid interfaces, G ~ (X/R)^2. where X is the conformational width of the first layer of chains of random coil size R. The fractal nature of the percolation process is relevant to the fracture mechanism and fractography.

Effect of sorbic acid doping on flux pinning in bulk MgB{sub 2} with the percolation model

Energy Technology Data Exchange (ETDEWEB)

Yang, Y. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Wang, L.; Sun, H.H. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y., E-mail: yzhao@swjtu.edu.c [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

2010-11-01

In this paper, we study the doping effect of sorbic acid (C{sub 6}H{sub 8}O{sub 2}), from 0 to 20 wt.% of the total MgB{sub 2}, on critical temperature (T{sub c}), critical current density (J{sub c}), irreversibility field (H{sub irr}) and crystalline structure. The XRD patterns of samples show a slightly decrease in a-axis lattice parameter for doped samples, due to the partial substitution of carbon at boron site. On the other hand, we investigate the influence of doping on the behavior of flux pinning and J{sub c}(B) in the framework of percolation theory and it is found that the J{sub c}(B) behavior could be well fitted in high field region. The two key parameters, anisotropy and percolation threshold, play very important roles. It is believed that the enhancement of J{sub c} is due to the reduction of anisotropy in high field region.

Fractal properties of percolation clusters in Euclidian neural networks

International Nuclear Information System (INIS)

Franovic, Igor; Miljkovic, Vladimir

2009-01-01

The process of spike packet propagation is observed in two-dimensional recurrent networks, consisting of locally coupled neuron pools. Local population dynamics is characterized by three key parameters - probability for pool connectedness, synaptic strength and neuron refractoriness. The formation of dynamic attractors in our model, synfire chains, exhibits critical behavior, corresponding to percolation phase transition, with probability for non-zero synaptic strength values representing the critical parameter. Applying the finite-size scaling method, we infer a family of critical lines for various synaptic strengths and refractoriness values, and determine the Hausdorff-Besicovitch fractal dimension of the percolation clusters.

Use of Invasion Percolation Models To Study the Secondary Migration of Oil and Related Problems

Energy Technology Data Exchange (ETDEWEB)

Wagner, G.

1997-12-31

This thesis studies simulations of the slow displacement of a wetting fluid by a non-wetting fluid in porous media and in a single fracture. The simulations are based on the invasion percolation model. New modified versions of the model are presented that simulate migration, fragmentation and coalescence processes of the clusters of non-wetting fluid. The resulting displacement patterns are characterized by scaling laws. In particular, simulations of the secondary migration of oil through porous homogeneous rock are discussed. Fractured rocks are extreme cases of inhomogeneous porous media. Simulations of the slow displacement of a wetting fluid by a non-wetting fluid in a single fracture using the standard invasion model are presented. There is a discussion of a scenario in which a cluster of non-wetting fluid migrates through a porous medium that was saturated with a wetting fluid. The migration is driven by continuously driven buoyancy forces. Both experiments and simulations are described. The same scenario is also studied theoretically and by simulations using a simplified percolation model of fluid migration in one dimension. The migration model in two dimensions, with constant buoyancy forces, is also discussed. Simulations of fluid migration, such as the secondary migration of oil, in two- and three-dimensional media are examined, the media having multi-affine properties rather than being homogeneous. Slow immiscible displacement processes in single fractures are studied using fractal geometries to model single fractures. 167 refs., 123 figs.

Real-space renormalization group; application to site percolation in square lattice

International Nuclear Information System (INIS)

Tsallis, C.; Schwachheim, G.

1978-05-01

The real-space renormalization group proposed by Reynolds, Klein and Stanley 1977 to treat the site percolation is analysed and extended . The best among 3 possible definitions of 'percolating' configurations and among 5 possible methods to weight these configurations, are established for percolation in square lattices. The use of n xn square clusters leads, for n = 2 (RKS), n = 3 and n = 4, to √ sub (p) approximately equal to 1.635, √ sub(p) approximately equal to 1.533 and √ sub(p) approximately equal to 1.498, and also to P sub(c) approximately equal to 0.382, P sub(c) approximately equal to 0.388 and P sub(c) approximately equal to 0.398, exhibiting in this way the correct (but slow) tendency towards the best up to date values [pt

Glass-Glass Transitions by Means of an Acceptor-Donor Percolating Electric-Dipole Network

Science.gov (United States)

Zhang, Le; Lou, Xiaojie; Wang, Dong; Zhou, Yan; Yang, Yang; Kuball, Martin; Carpenter, Michael A.; Ren, Xiaobing

2017-11-01

We report the ferroelectric glass-glass transitions in KN (K+/Nb5 +) -doped BaTiO3 ferroelectric ceramics, which have been proved by x-ray diffraction profile and Raman spectra data. The formation of glass-glass transitions can be attributed to the existence of cubic (C )-tetragonal (T )-orthorhombic (O )-rhombohedral (R ) ferroelectric transitions in short-range order. These abnormal glass-glass transitions can perform very small thermal hysteresis (approximately 1.0 K ) with a large dielectric constant (approximately 3000), small remanent polarization Pr , and relative high maximum polarization Pm remaining over a wide temperature range (220-350 K) under an electrical stimulus, indicating the potential applications in dielectric recoverable energy-storage devices with high thermal reliability. Further phase field simulations suggest that these glass-glass transitions are induced by the formation of a percolating electric defect-dipole network (PEDN). This proper PEDN breaks the long-range ordered ferroelectric domain pattern and results in the local phase transitions at the nanoscale. Our work may further stimulate the fundamental physical theory and accelerate the development of dielectric energy-storing devices.

Percolation and cooperation with mobile agents: geometric and strategy clusters.

Science.gov (United States)

Vainstein, Mendeli H; Brito, Carolina; Arenzon, Jeferson J

2014-08-01

We study the conditions for persistent cooperation in an off-lattice model of mobile agents playing the Prisoner's Dilemma game with pure, unconditional strategies. Each agent has an exclusion radius r(P), which accounts for the population viscosity, and an interaction radius r(int), which defines the instantaneous contact network for the game dynamics. We show that, differently from the r(P)=0 case, the model with finite-sized agents presents a coexistence phase with both cooperators and defectors, besides the two absorbing phases, in which either cooperators or defectors dominate. We provide, in addition, a geometric interpretation of the transitions between phases. In analogy with lattice models, the geometric percolation of the contact network (i.e., irrespective of the strategy) enhances cooperation. More importantly, we show that the percolation of defectors is an essential condition for their survival. Differently from compact clusters of cooperators, isolated groups of defectors will eventually become extinct if not percolating, independently of their size.

Low percolation transitions in carbon nanotube networks dispersed in a polymer matrix: dielectric properties, simulations and experiments.

Science.gov (United States)

Simoes, Ricardo; Silva, Jaime; Vaia, Richard; Sencadas, Vítor; Costa, Pedro; Gomes, João; Lanceros-Méndez, Senentxu

2009-01-21

The low concentration behaviour and the increase of the dielectric constant in carbon nanotubes/polymer nanocomposites near the percolation threshold are still not well understood. In this work, a numerical model has been developed which focuses on the effect of the inclusion of conductive fillers in a dielectric polymer matrix on the dielectric constant and the dielectric strength. Experiments have been carried out in carbon nanotubes/poly(vinylidene fluoride) nanocomposites in order to compare to the simulation results. This work shows how the critical concentration is related to the formation of capacitor networks and that these networks give rise to high variations in the electrical properties of the composites. Based on numerical studies, the dependence of the percolation transition on the preparation of the nanocomposite is discussed. Finally, based on numerical and experimental results, both ours and from other authors, the causes of anomalous percolation behaviour of the dielectric constant are identified.

Do diatoms percolate through soil and can they be used for tracing the origin of runoff?

Science.gov (United States)

De Graaf, Lenka; Cammeraat, Erik; Pfister, Laurent; Wetzel, Carlos; Klaus, Julian; Hissler, Christophe

2015-04-01

Tracers are widely used to study the movement of water in a catchment. Because of depletion of scientific possibilities with most common tracer types, we proposed the use of diatoms as a natural tracer. Paradoxical results on the contribution of surface runoff to the storm hydrograph were obtained in pioneer research on this idea. Diatom transport via the subsurface flow to the stream would explain this paradox. Prerequisite for this is vertical transport of diatoms through soils, which is the topic of this study. Emphasis is on percolation behavior (speed of percolation, speed of percolation over time, and species distribution) of Pseudostaurosira sp. and Melosira sp. (Bacillariophyceae) through undisturbed soil columns of contrasting substrates. Co-objective is to study the flowpaths of water through the soil columns. Natural undisturbed soil columns were sampled in the Attert basin (Luxembourg) on schist, marl and sandstone substrates. Rain simulation experiments were performed to study vertical diatom transport. Rhodamine dye experiments were carried out to gain insight in the active flowpaths of water, and breakthrough experiments were performed to study the responses of the soil columns to applied water. Diatoms were transported through the soil columns of the three substrates. A vast majority of diatom percolation took place within the first 15 minutes, percolation hereafter was marginal but nevertheless present. Peaks in diatom percolation corresponded with a high flux caused by the addition of the diatom culture, but seepage of diatoms along the sides is unlikely according to the species distribution and the rhodamine dye experiment. Pseudostaurosira sp. percolated significantly better than Melosira sp. Significantly more diatoms percolated through the marl columns compared to the schist columns and variance within the sandstone group was very high. Absolute differences between substrates however, were marginal. Most preferential flowpaths were observed in

Unusual percolation in simple small-world networks.

Science.gov (United States)

Cohen, Reuven; Dawid, Daryush Jonathan; Kardar, Mehran; Bar-Yam, Yaneer

2009-06-01

We present an exact solution of percolation in a generalized class of Watts-Strogatz graphs defined on a one-dimensional underlying lattice. We find a nonclassical critical point in the limit of the number of long-range bonds in the system going to zero, with a discontinuity in the percolation probability and a divergence in the mean finite-cluster size. We show that the critical behavior falls into one of three regimes depending on the proportion of occupied long-range to unoccupied nearest-neighbor bonds, with each regime being characterized by different critical exponents. The three regimes can be united by a single scaling function around the critical point. These results can be used to identify the number of long-range links necessary to secure connectivity in a communication or transportation chain. As an example, we can resolve the communication problem in a game of "telephone."

Cooperation percolation in spatial prisoner's dilemma game

International Nuclear Information System (INIS)

Yang, Han-Xin; Rong, Zhihai; Wang, Wen-Xu

2014-01-01

The paradox of cooperation among selfish individuals still puzzles scientific communities. Although a large amount of evidence has demonstrated that the cooperator clusters in spatial games are effective in protecting the cooperators against the invasion of defectors, we continue to lack the condition for the formation of a giant cooperator cluster that ensures the prevalence of cooperation in a system. Here, we study the dynamical organization of the cooperator clusters in spatial prisoner's dilemma game to offer the condition for the dominance of cooperation, finding that a phase transition characterized by the emergence of a large spanning cooperator cluster occurs when the initial fraction of the cooperators exceeds a certain threshold. Interestingly, the phase transition belongs to different universality classes of percolation determined by the temptation to defect b. Specifically, on square lattices, 1 < b < 4/3 leads to a phase transition pertaining to the class of regular site percolation, whereas 3/2 < b < 2 gives rise to a phase transition subject to invasion percolation with trapping. Our findings offer a deeper understanding of cooperative behavior in nature and society. (paper)

On Palacios-Gordon's theory of relativity

International Nuclear Information System (INIS)

Gulati, P.S.

1981-01-01

Since the early days of Einstein's special theory of relativity (1905), it is known that this theory suffers from some epistemological problems. Over the years, many theoreticians have endeavored to overcome these problems, rejecting either the 'Principle of Relativity' or the 'Light Principle'. Palacios and Gordon rejected the former and advanced an alternative theory governed by Voigt's transformation equations (1887). In the present paper, Palacios-Gordon's theory has been critically examined and some of its drawbacks are discovered. It becomes obvious that neither Einstein's special theory of relativity nor Palacios-Gordon's theory of relativity provides a flawless fit to the real world. It is speculated that suitable synthesis of these two theories might resolve all the controversial issues of special theory of relativity. (author)

Percolation model of excess electrical noise in transition-edge sensors

International Nuclear Information System (INIS)

Lindeman, M.A.; Anderson, M.B.; Bandler, S.R.; Bilgri, N.; Chervenak, J.; Gwynne Crowder, S.; Fallows, S.; Figueroa-Feliciano, E.; Finkbeiner, F.; Iyomoto, N.; Kelley, R.; Kilbourne, C.A.; Lai, T.; Man, J.; McCammon, D.; Nelms, K.L.; Porter, F.S.; Rocks, L.E.; Saab, T.; Sadleir, J.; Vidugiris, G.

2006-01-01

We present a geometrical model to describe excess electrical noise in transition-edge sensors (TESs). In this model, a network of fluctuating resistors represents the complex dynamics inside a TES. The fluctuations can cause several resistors in series to become superconducting. Such events short out part of the TES and generate noise because much of the current percolates through low resistance paths. The model predicts that excess white noise increases with decreasing TES bias resistance (R/R N ) and that perpendicular zebra stripes reduce noise and alpha of the TES by reducing percolation

Chemical Distances for Percolation of Planar Gaussian Free Fields and Critical Random Walk Loop Soups

Science.gov (United States)

Ding, Jian; Li, Li

2018-06-01

We initiate the study on chemical distances of percolation clusters for level sets of two-dimensional discrete Gaussian free fields as well as loop clusters generated by two-dimensional random walk loop soups. One of our results states that the chemical distance between two macroscopic annuli away from the boundary for the random walk loop soup at the critical intensity is of dimension 1 with positive probability. Our proof method is based on an interesting combination of a theorem of Makarov, isomorphism theory, and an entropic repulsion estimate for Gaussian free fields in the presence of a hard wall.

Quasiuniversal Connectedness Percolation of Polydisperse Rod Systems

NARCIS (Netherlands)

Nigro, B.; Grimaldi, C.; Chatterjee, A.P.; van der Schoot, P. P. A. M.

2013-01-01

The connectedness percolation threshold (ηc) and critical coordination number (Zc) of systems of penetrable spherocylinders characterized by a length polydispersity are studied by way of Monte Carlo simulations for several aspect ratio distributions. We find that (i) ηc is a nearly universal

Gravity, general relativity theory and alternative theories

International Nuclear Information System (INIS)

Zel'dovich, Ya.B.; Grishchuk, L.P.; Moskovskij Gosudarstvennyj Univ.

1986-01-01

The main steps in plotting the current gravitation theory and some prospects of its subsequent development are reviewed. The attention is concentrated on a comparison of the relativistic gravitational field with other physical fields. Two equivalent formulations of the general relativity (GR) - geometrical and field-theoretical - are considered in detail. It is shown that some theories of gravity constructed as the field theories at a flat background space-time are in fact just different formulations of GR and not alternative theories

Generalized string theory mapping relations between gravity and gauge theory

International Nuclear Information System (INIS)

Bjerrum-Bohr, N.E.J.

2003-01-01

A previous study of the Kawai, Lewellen and Tye (KLT) relations between gravity and gauge theories, imposed by the relationship of closed and open strings, are here extended in the light of general relativity and Yang-Mills theory as effective field theories. We discuss the possibility of generalizing the traditional KLT mapping in this effective setting. A generalized mapping between the effective Lagrangians of gravity and Yang-Mills theory is presented, and the corresponding operator relations between gauge and gravity theories at the tree level are further explored. From this generalized mapping remarkable diagrammatic relations are found, linking diagrams in gravity and Yang-Mills theory, as well as diagrams in pure effective Yang-Mills theory. Also the possibility of a gravitational coupling to an antisymmetric field in the gravity scattering amplitude is considered, and shown to allow for mixed open-closed string solutions, i.e., closed heterotic strings

Double Exponential Relativity Theory Coupled Theoretically with Quantum Theory?

International Nuclear Information System (INIS)

Montero Garcia, Jose de la Luz; Novoa Blanco, Jesus Francisco

2007-01-01

Here the problem of special relativity is analyzed into the context of a new theoretical formulation: the Double Exponential Theory of Special Relativity with respect to which the current Special or Restricted Theory of Relativity (STR) turns to be a particular case only

Fibrillar organization in tendons: A pattern revealed by percolation characteristics of the respective geometric network

Directory of Open Access Journals (Sweden)

Daniel Andres Dos Santos

2014-06-01

Full Text Available Since the tendon is composed by collagen fibrils of various sizes connected between them through molecular cross-links, it sounds logical to model it via a heterogeneous network of fibrils. Using cross sectional images, that network is operatively inferred from the respective Gabriel graph of the fibril mass centers. We focus on network percolation characteristics under an ordered activation of fibrils (progressive recruitment going from the smallest to the largest fibril. Analyses of percolation were carried out on a repository of images of digital flexor tendons obtained from samples of lizards and frogs. Observed percolation thresholds were compared against values derived from hypothetical scenarios of random activation of nodes. Strikingly, we found a significant delay for the occurrence of percolation in actual data. We interpret this finding as the consequence of some non-random packing of fibrillar units into a size-constrained geometric pattern. We erect an ideal geometric model of balanced interspersion of polymorphic units that accounts for the delayed percolating instance. We also address the circumstance of being percolation curves mirrored by the empirical curves of stress-strain obtained from the same studied tendons. By virtue of this isomorphism, we hypothesize that the inflection points of both curves are different quantitative manifestations of a common transitional process during mechanical load transference.

Deep Percolation in Arid Piedmont Slopes: Multiple Lines of Evidence Show How Land Use Change and Ecohydrological Properties Affect Groundwater Recharge

Science.gov (United States)

Schreiner-McGraw, A.; Vivoni, E. R.; Browning, D. M.

2017-12-01

A critical hydrologic process in arid regions is the contribution of episodic streamflow in ephemeral channels to groundwater recharge. This process has traditionally been studied in channels that drain large watersheds (10s to 100s km2). In this study, we aim to characterize the provision of the ecosystem services of surface and groundwater supply in a first-order watershed (4.6 ha) in an arid piedmont slope of the Jornada Experimental Range (JER). We use an observational and modeling approach to estimate deep percolation. During a 6 year study period, we observed 428 mm of percolation (P) and 39 mm of runoff (Q); ratios of P to rainfall (R) of P/R = 0.27 and Q/R = 0.02. Utilizing an instrument network and site measurements, we determine that percolation occurs primarily inside channel reaches when these receive runoff from upland hillslopes and find that a monthly rainfall threshold of 62 mm is needed for significant percolation to be generated. In order to quantify the mechanisms leading to this threshold response, we develop a channel transmission loss module for the TIN-based Real-time Integrated Basin Simulator (tRIBS) and test the model thoroughly against the available observations over the study period. For these purposes, we make use of image classifications from Unmanned Aerial Vehicle flights, a ground-based phenocam, and species-level measurements to parameterize vegetation processes in the model. We then conduct an extensive set of sensitivity experiments to determine the relative roles of channel, soil, and vegetation properties on modifying the relation between monthly rainfall and percolation. Additionally, we test how the observed vegetation transitions in the JER over the last 150 years affect the deep percolation and runoff estimates. By quantifying mechanisms through which vegetation changes affect water resource provision, this work provides new insights on the ecohydrological controls on the water yield of arid piedmont slopes.

The special theory of relativity bound with relativity

CERN Document Server

Dingle, Herbert

2014-01-01

The Special Theory of Relativity:Based on a short course of lectures delivered in the late 1930s, this short book presents the theory of Special Relativity by formulating a redefinition of the measurement of length, and thus will appeal to students of physics who wish to think through Einstein's thought without the encumbrance of quasi-scientific concepts and language. Relativity: A Very Elementary Exposition:This brief lecture, delivered in October 1921 and published for the first time in 1925, offers an explanation of Einstein's theory of Special Relativity for the non-scientist, giving a ge

Generalized model for k -core percolation and interdependent networks

Science.gov (United States)

Panduranga, Nagendra K.; Gao, Jianxi; Yuan, Xin; Stanley, H. Eugene; Havlin, Shlomo

2017-09-01

Cascading failures in complex systems have been studied extensively using two different models: k -core percolation and interdependent networks. We combine the two models into a general model, solve it analytically, and validate our theoretical results through extensive simulations. We also study the complete phase diagram of the percolation transition as we tune the average local k -core threshold and the coupling between networks. We find that the phase diagram of the combined processes is very rich and includes novel features that do not appear in the models studying each of the processes separately. For example, the phase diagram consists of first- and second-order transition regions separated by two tricritical lines that merge and enclose a two-stage transition region. In the two-stage transition, the size of the giant component undergoes a first-order jump at a certain occupation probability followed by a continuous second-order transition at a lower occupation probability. Furthermore, at certain fixed interdependencies, the percolation transition changes from first-order → second-order → two-stage → first-order as the k -core threshold is increased. The analytic equations describing the phase boundaries of the two-stage transition region are set up, and the critical exponents for each type of transition are derived analytically.

Percolation picture of disintegration of nuclei in the proton-nucleus interaction

International Nuclear Information System (INIS)

Botvina, A.S.; Lanin, L.V.

1992-01-01

Breakup of nuclei into fragments in the proton-nucleus interaction is studied. It is assumed that breakup occurs in two stages. During the first stage the incident particle interacts with individual nucleons of the nucleus, and high-energy reaction products are emitted from the nucleus. This stage is described by means of the intranuclear-cascade model. During the second stage some of the nuclei, whose excitation energy is high, or whose density is very inhomogeneous, break up. This breakup is described by means of a percolation model which takes into account the spatial distribution of nucleons in the nucleus and which generalizes the percolation description of the 'liquid-gas' phase transition for finite nuclei. Features of this breakup mechanism are studied. The analysis of the experimental data indicates that it is not sufficient to consider percolation only in the coordinate space, and that the momentum distribution of the nucleons in the nucleus must be taken into account

First-passage percolation on the random graph

NARCIS (Netherlands)

Hofstad, van der R.W.; Hooghiemstra, G.; Van Mieghem, P.

2001-01-01

We study first-passage percolation on the random graph Gp(N) with exponentially distributed weights on the links. For the special case of the complete graph, this problem can be described in terms of a continuous-time Markov chain and recursive trees. The Markov chain X(t) describes the number of

Observation of feature ripening inversion effect at the percolation threshold for the growth of thin silver films

Energy Technology Data Exchange (ETDEWEB)

Nehm, Frederik, E-mail: frederik.nehm@iapp.de; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl

2014-04-01

The growth behavior of thin silver films on organic layers is investigated during deposition by means of simultaneous in-situ monitoring of sheet resistance and transmittance. Thermally evaporated films up to 11 nm show a distinct percolation behavior with strong resistance drop at the percolation thickness. Additionally, evaporations are divided into a sequence of one nanometer steps. In the deposition breaks, the films exhibit a ripening effect with an inversion at the percolation thickness, by changing from an increasing to decreasing sheet resistance over time. Scanning electron micrographs suggest same ripening mechanisms for islands below the percolation thickness as for holes above. - Highlights: • Fundamental understanding of metal thin film growth is presented. • Optical and electrical in-situ measurements used for optimizing transparent electrodes • Stepwise Ag deposition reveals extraordinary ripening effects. • Feature ripening inversion is discovered at the percolation threshold.

Observation of feature ripening inversion effect at the percolation threshold for the growth of thin silver films

International Nuclear Information System (INIS)

Nehm, Frederik; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl

2014-01-01

The growth behavior of thin silver films on organic layers is investigated during deposition by means of simultaneous in-situ monitoring of sheet resistance and transmittance. Thermally evaporated films up to 11 nm show a distinct percolation behavior with strong resistance drop at the percolation thickness. Additionally, evaporations are divided into a sequence of one nanometer steps. In the deposition breaks, the films exhibit a ripening effect with an inversion at the percolation thickness, by changing from an increasing to decreasing sheet resistance over time. Scanning electron micrographs suggest same ripening mechanisms for islands below the percolation thickness as for holes above. - Highlights: • Fundamental understanding of metal thin film growth is presented. • Optical and electrical in-situ measurements used for optimizing transparent electrodes • Stepwise Ag deposition reveals extraordinary ripening effects. • Feature ripening inversion is discovered at the percolation threshold

Spin dynamics on percolating networks

International Nuclear Information System (INIS)

Aeppli, G.; Guggenheim, H.; Uemura, Y.J.

1985-01-01

We have used inelastic neutron scattering to measure the order parameter relaxation rate GAMMA in the dilute, two-dimensional Ising antiferromagnet Rb 2 CoMg/sub 1-c/F 4 with c very close to the magnetic percolation threshold. Where kappa is the inverse magnetic correlation length, GAMMA approx. kappa/sup z/ with z = 2.4/sub -0.1//sup +0.2/. Our results are discussed in terms of current ideas about spin relaxation on fractals. 13 refs., 1 fig

Theory of relations

CERN Document Server

Fraïssé, R

2011-01-01

The first part of this book concerns the present state of the theory of chains (= total or linear orderings), in connection with some refinements of Ramsey's theorem, due to Galvin and Nash-Williams. This leads to the fundamental Laver's embeddability theorem for scattered chains, using Nash-Williams' better quasi-orderings, barriers and forerunning.The second part (chapters 9 to 12) extends to general relations the main notions and results from order-type theory. An important connection appears with permutation theory (Cameron, Pouzet, Livingstone and Wagner) and with logics (existence criter

Electrical percolation threshold of magnetostrictive inclusions in a piezoelectric matrix under simulated sintering conditions

Science.gov (United States)

Bedard, Antoine Joseph; Barbero, Ever J.

2018-03-01

Magnetoelectric (ME) composites can be produced by embedding magnetostrictive H particles in a piezoelectric E matrix derived from a piezoelectric powder precursor. Previously, using a bi-disperse hard-shell model (Barbero and Bedard in Comput Part Mech, 2018. https://doi.org/10.1007/s40571-017-0165-4), it has been shown that the electrical percolation threshold of the conductive H phase can be increased by decreasing the piezoelectric E particle size, relative to the H phase particle size, and by increasing short-range affinity between the E and H particles. This study builds on our previous study by exploring what happens during sintering of the ME composite when either the H or E particles undergo deformation. It was found that deformation of the H particles reduces the percolation threshold, and that deformation of E particles increases inter-phase H-E mechanical coupling, thus contributing to enhancing of ME coupling.

The Central Limit Theorem for Supercritical Oriented Percolation in Two Dimensions

Science.gov (United States)

Tzioufas, Achillefs

2018-04-01

We consider the cardinality of supercritical oriented bond percolation in two dimensions. We show that, whenever the the origin is conditioned to percolate, the process appropriately normalized converges asymptotically in distribution to the standard normal law. This resolves a longstanding open problem pointed out to in several instances in the literature. The result applies also to the continuous-time analog of the process, viz. the basic one-dimensional contact process. We also derive general random-indices central limit theorems for associated random variables as byproducts of our proof.

Critical points for spread-out self-avoiding walk, percolation and the contact process above the upper critical dimensions

NARCIS (Netherlands)

Hofstad, van der R.W.; Sakai, A.

2005-01-01

We consider self-avoiding walk and percolation in d, oriented percolation in d×+, and the contact process in d, with p D(·) being the coupling function whose range is proportional to L. For percolation, for example, each bond is independently occupied with probability p D(y–x). The above models are

Emergent Percolation Length and Localization in Random Elastic Networks

Directory of Open Access Journals (Sweden)

Ariel Amir

2013-06-01

Full Text Available We study, theoretically and numerically, a minimal model for phonons in a disordered system. For sufficient disorder, the vibrational modes of this classical system can become Anderson localized, yet this problem has received significantly less attention than its electronic counterpart. We find rich behavior in the localization properties of the phonons as a function of the density, frequency, and spatial dimension. We use a percolation analysis to argue for a Debye spectrum at low frequencies for dimensions higher than one, and for a localization-delocalization transition (at a critical frequency above two dimensions. We show that in contrast to the behavior in electronic systems, the transition exists for arbitrarily large disorder, albeit with an exponentially small critical frequency. The structure of the modes reflects a divergent percolation length that arises from the disorder in the springs without being explicitly present in the definition of our model. Within the percolation approach, we calculate the speed of sound of the delocalized modes (phonons, which we corroborate with numerics. We find the critical frequency of the localization transition at a given density and find good agreement of these predictions with numerical results using a recursive Green-function method that was adapted for this problem. The connection of our results to recent experiments on amorphous solids is discussed.

Percolation bounds for decoding thresholds with correlated erasures in quantum LDPC codes

Science.gov (United States)

Hamilton, Kathleen; Pryadko, Leonid

Correlations between errors can dramatically affect decoding thresholds, in some cases eliminating the threshold altogether. We analyze the existence of a threshold for quantum low-density parity-check (LDPC) codes in the case of correlated erasures. When erasures are positively correlated, the corresponding multi-variate Bernoulli distribution can be modeled in terms of cluster errors, where qubits in clusters of various size can be marked all at once. In a code family with distance scaling as a power law of the code length, erasures can be always corrected below percolation on a qubit adjacency graph associated with the code. We bound this correlated percolation transition by weighted (uncorrelated) percolation on a specially constructed cluster connectivity graph, and apply our recent results to construct several bounds for the latter. This research was supported in part by the NSF Grant PHY-1416578 and by the ARO Grant W911NF-14-1-0272.

Complex dynamic behaviors of oriented percolation-based financial time series and Hang Seng index

International Nuclear Information System (INIS)

Niu, Hongli; Wang, Jun

2013-01-01

Highlights: • We develop a financial time series model by two-dimensional oriented percolation system. • We investigate the statistical behaviors of returns for HSI and the financial model by chaos-exploring methods. • We forecast the phase point of reconstructed phase space by RBF neural network. -- Abstract: We develop a financial price model by the two-dimensional oriented (directed) percolation system. The oriented percolation model is a directed variant of ordinary (isotropic) percolation, and it is applied to describe the fluctuations of stock prices. In this work, we assume that the price fluctuations result from the participants’ investment attitudes toward the market, and we investigate the information spreading among the traders and the corresponding effect on the price fluctuations. We study the complex dynamic behaviors of return time series of the model by using the multiaspect chaos-exploring methods. And we also explore the corresponding behaviors of the actual market index (Hang Seng Index) for comparison. Further, we introduce the radial basic function (RBF) neural network to train and forecast the phase point of reconstructed phase space

The geometry of percolation fronts in two-dimensional lattices with spatially varying densities

International Nuclear Information System (INIS)

Gastner, Michael T; Oborny, Beáta

2012-01-01

Percolation theory is usually applied to lattices with a uniform probability p that a site is occupied or that a bond is closed. The more general case, where p is a function of the position x, has received less attention. Previous studies with long-range spatial variations in p(x) have only investigated cases where p has a finite, non-zero gradient at the critical point p c . Here we extend the theory to two-dimensional cases in which the gradient can change from zero to infinity. We present scaling laws for the width and length of the hull (i.e. the boundary of the spanning cluster). We show that the scaling exponents for the width and the length depend on the shape of p(x), but they always have a constant ratio 4/3 so that the hull's fractal dimension D = 7/4 is invariant. On this basis, we derive and verify numerically an asymptotic expression for the probability h(x) that a site at a given distance x from p c is on the hull. (paper)

Topological interlocking provides stiffness to stochastically micro-cracked materials beyond the transport percolation limit

Science.gov (United States)

Pal, Anirban; Picu, Catalin; Lupulescu, Marian V.

We study the mechanical behavior of two-dimensional, stochastically microcracked continua in the range of crack densities close to, and above the transport percolation threshold. We show that these materials retain stiffness up to crack densities much larger than the transport percolation threshold, due to topological interlocking of sample sub-domains. Even with a linear constitutive law for the continuum, the mechanical behavior becomes non-linear in the range of crack densities bounded by the transport and stiffness percolation thresholds. The effect is due to the fractal nature of the fragmentation process and is not linked to the roughness of individual cracks. We associate this behavior to that of itacolumite, a sandstone that exhibits unusual flexibility.

White Light Generation and Anisotropic Damage in Gold Films near Percolation Threshold

DEFF Research Database (Denmark)

Novikov, Sergey M.; Frydendahl, Christian; Beermann, Jonas

2017-01-01

in vanishingly small gaps between gold islands in thin films near the electrically determined percolation threshold. Optical explorations using two-photon luminescence (TPL) and near-field microscopies reveals supercubic TPL power dependencies with white-light spectra, establishing unequivocally...... that the strongest TPL signals are generated close to the percolation threshold films, and occurrence of extremely confined (similar to 30 nm) and strongly enhanced (similar to 100 times) fields at the illumination wavelength. For linearly polarized and sufficiently powerful light, we observe pronounced optical...

Experimental observation of percolation-enhanced nonlinear light scattering from semicontinuous metal films

Science.gov (United States)

Breit, M.; Podolskiy, V. A.; Grésillon, S.; von Plessen, G.; Feldmann, J.; Rivoal, J. C.; Gadenne, P.; Sarychev, Andrey K.; Shalaev, Vladimir M.

2001-09-01

Strongly enhanced second-harmonic generation (SHG), which is characterized by a nearly isotropic intensity distribution, is observed for gold-glass films near the percolation threshold. The diffuselike SHG scattering, which can be thought of as nonlinear critical opalescence, is in sharp contrast with highly collimated linear reflection and transmission from these nanostructured semicontinuous metal films. Our observations, which can be explained by giant fluctuations of local nonlinear sources for SHG due to plasmon localization, verify recent predictions of percolation-enhanced nonlinear scattering.

Weak link behaviour in YBa2Cu3O7-δ system studied by a site percolation model

International Nuclear Information System (INIS)

Arulgnanam, A.; Balasubramanian, A.

1992-01-01

The superconductivity in the YBaCuO system can be explained in terms of the superconducting percolation of 90 K orthorhombic microdomain. Kubo et al. have studied the percolation behaviour of the 123 system and estimated the total critical oxygen occupancy P c to be 0.75 for the orthorhombic I structure using at 150x180 lattice model. In this paper, we report our work on the percolative behaviour of the 123 system, using a Monte Carlo method. We have studied the effect on P c of increasing the lattice dimension up to 500x500. For P c ≤0.60 no percolative behaviour was observed, suggesting the tetragonal phase. Few times percolation was observed for 0.60≤P≤0.65 indicating the phase transformation from tetragonal to orthorhombic. For 0.65≤P≤0.77 (or 0.230≤δ≤0.35) weak percolative behaviour was observed suggesting the formation of orthorhombic II structure, which is in good agreement with the value observed by Cava et al. For 0.77≤P≤1.0 strong percolation was exhibited indicating the formation of orthorhombic I phase. We have explained the weak link region observed for 0.60≤P≤0.77. We estimated the total critical oxygen occupancy P c =0.766 for an orthorhombic I structure for the lattice. (orig.)

On Equivalence between Critical Probabilities of Dynamic Gossip Protocol and Static Site Percolation

Science.gov (United States)

Ishikawa, Tetsuya; Hayakawa, Tomohisa

The relationship between the critical probability of gossip protocol on the square lattice and the critical probability of site percolation on the square lattice is discussed. Specifically, these two critical probabilities are analytically shown to be equal to each other. Furthermore, we present a way of evaluating the critical probability of site percolation by approximating the saturation of gossip protocol. Finally, we provide numerical results which support the theoretical analysis.

Finite-Size Effects for Some Bootstrap Percolation Models

NARCIS (Netherlands)

Enter, A.C.D. van; Adler, Joan; Duarte, J.A.M.S.

The consequences of Schonmann's new proof that the critical threshold is unity for certain bootstrap percolation models are explored. It is shown that this proof provides an upper bound for the finite-size scaling in these systems. Comparison with data for one case demonstrates that this scaling

Electrical percolation in the presence of attractive interactions: An effective medium lattice approach applied to microemulsion systems

Science.gov (United States)

Hattori, Y.; Ushiki, H.; Engl, W.; Courbin, L.; Panizza, P.

2005-08-01

Within the framework of an effective medium approach and a mean-field approximation, we present a simple lattice model to treat electrical percolation in the presence of attractive interactions. We show that the percolation line depends on the magnitude of interactions. In 2 dimensions, the percolation line meets the binodal line at the critical point. A good qualitative agreement is observed with experimental results on a ternary AOT-based water-in-oil microemulsion system.

Modeling Percolation in Polymer Nanocomposites by Stochastic Microstructuring

Directory of Open Access Journals (Sweden)

Matias Soto

2015-09-01

Full Text Available A methodology was developed for the prediction of the electrical properties of carbon nanotube-polymer nanocomposites via Monte Carlo computational simulations. A two-dimensional microstructure that takes into account waviness, fiber length and diameter distributions is used as a representative volume element. Fiber interactions in the microstructure are identified and then modeled as an equivalent electrical circuit, assuming one-third metallic and two-thirds semiconductor nanotubes. Tunneling paths in the microstructure are also modeled as electrical resistors, and crossing fibers are accounted for by assuming a contact resistance associated with them. The equivalent resistor network is then converted into a set of linear equations using nodal voltage analysis, which is then solved by means of the Gauss–Jordan elimination method. Nodal voltages are obtained for the microstructure, from which the percolation probability, equivalent resistance and conductivity are calculated. Percolation probability curves and electrical conductivity values are compared to those found in the literature.

Quantitative characterization of the formation of an interpenetrating phase composite in polystyrene from the percolation of multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Kota, Arun K; Cipriano, Bani H; Powell, Dan; Raghavan, Srinivasa R; Bruck, Hugh A

2007-01-01

For the first time, an interpenetrating phase polymer nanocomposite formed by the percolation of multiwalled carbon nanotubes (MWCNTs) in polystyrene (PS) has been quantitatively characterized through electrical conductivity measurements and melt rheology. Both sets of measurements, in conjunction with scanning electron microscopy (SEM) images, indicate the presence of a continuous phase of percolated MWCNTs appearing at particle concentrations exceeding 2 vol% MWCNTs in PS. To quantify the amount of this continuous phase present in the PS/MWCNT composite, electrical conductivity data at various MWCNT concentrations, β, are correlated with a proposed degree of percolation, C-bar(β), developed using a conventional power-law formula with and without a percolation threshold. To quantify the properties of the interpenetrating phase polymer nanocomposite, the PS/MWCNT composite is treated as a combination of two phases: a continuous phase consisting of a pseudo-solid-like network of percolated MWCNTs, and a continuous PS phase reinforced by non-interacting MWCNTs. The proposed degree of percolation is used to quantify the distribution of MWCNTs among the phases, and is then used in a rule-of-mixtures formulation for the storage modulus, G'(β, C-bar(β), ω), and the loss modulus, G''(β, C-bar(β), ω), to quantify the properties of the continuous phase consisting of percolated MWCNTs and the continuous PS phase reinforced by non-interacting MWCNTs from the experimental melt rheology data. The properties of the continuous phase of percolated MWCNTs are indicative of a scaffold-like microstructure exhibiting an elastic behavior with a complex modulus of 360 kPa at lower frequencies and viscoplastic behavior with a complex viscosity of 6 kPa s rad -1 at higher frequencies, most likely due to a stick-slip friction mechanism at the interface of the percolated MWCNTs. Additional evidence of this microstructure was obtained via scanning electron microscopy. This research

Electrical percolation, morphological and dispersion properties of MWCNT/PMMA nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Coelho, Paulo Henrique da Silva Leite; Marchesin, Marcel Silva; Morales, Ana Rita; Bartoli, Julio Roberto, E-mail: piyke.coelho@gmail.com [Universidade de Campinas (UNICAMP), SP (Brazil). Escola de Engenharia Quimica

2014-08-15

Nanocomposites of poly (methyl methacrylate) (PMMA) and carbon nanotubes have a high potential for applications where conductivity and low specific weight are required. This piece of work concerns investigations of the level of dispersion and morphology on the electrical properties of in situ polymerized nanocomposites in different concentrations of multi-walled carbon nanotubes (MWCNT) in a PMMA matrix. The electrical conductivity was measured by the four point probe. The morphology and dispersion was analyzed by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). The correlation between electrical conductivity and the MWCNT amount, presented a typical percolation behavior, whose electrical percolation threshold determined by power law relationship was 0.2 vol. (%) The exponent t from the percolation power law indicated the formation of a 3D network of randomly arranged MWCNT. SAXS detected that the structures are intermediate to disks or spheres indicating fractal geometry for the MWCNT aggregates instead of isolated rods. HR-TEM images allowed us to observe the MWCNT individually dispersed into the matrix, revealing their distribution without preferential space orientation and absence of significant damage to the walls. The combined results of SAXS and HR-TEM suggest that MWCNT into the polymeric matrix might present interconnected aggregates and some dispersed single structures. (author)

Electrical percolation, morphological and dispersion properties of MWCNT/PMMA nanocomposites

International Nuclear Information System (INIS)

Coelho, Paulo Henrique da Silva Leite; Marchesin, Marcel Silva; Morales, Ana Rita; Bartoli, Julio Roberto

2014-01-01

Nanocomposites of poly (methyl methacrylate) (PMMA) and carbon nanotubes have a high potential for applications where conductivity and low specific weight are required. This piece of work concerns investigations of the level of dispersion and morphology on the electrical properties of in situ polymerized nanocomposites in different concentrations of multi-walled carbon nanotubes (MWCNT) in a PMMA matrix. The electrical conductivity was measured by the four point probe. The morphology and dispersion was analyzed by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). The correlation between electrical conductivity and the MWCNT amount, presented a typical percolation behavior, whose electrical percolation threshold determined by power law relationship was 0.2 vol. (%) The exponent t from the percolation power law indicated the formation of a 3D network of randomly arranged MWCNT. SAXS detected that the structures are intermediate to disks or spheres indicating fractal geometry for the MWCNT aggregates instead of isolated rods. HR-TEM images allowed us to observe the MWCNT individually dispersed into the matrix, revealing their distribution without preferential space orientation and absence of significant damage to the walls. The combined results of SAXS and HR-TEM suggest that MWCNT into the polymeric matrix might present interconnected aggregates and some dispersed single structures. (author)

A nonsteady-state firn-densification model for the percolation zone of a glacier

DEFF Research Database (Denmark)

Reeh, Niels

2008-01-01

A simple steady state firn-densification model is modified to account for short-term time variations of accumulation rate and surface temperature. The temporal surface-elevation- and mass changes at two sites in the percolation zone of an ice sheet in response to various climate histories...... are determined. It is shown that a straight-forward translation of observed short-term ice-sheet surface-elevation variations into mass changes may be completely misleading, particularly for the percolation zone of the ice sheet, where temperature driven variations of melting/re-freezing rates have a strong...... impact on near surface density. In the lower percolation zone, the mass change associated with a temperature anomaly in respect to the mean climate may for example amount to as little as 10 percent of the observed, simultaneous surface elevation change. Moreover, significant surface elevation change may...

The end of International Relations theory?

DEFF Research Database (Denmark)

Dunne, Tim; Hansen, Lene; Wight, Colin

2013-01-01

With a view to providing contextual background for the Special Issue, this opening article analyses several dimensions of ‘The end of International Relations theory?’ It opens with a consideration of the status of different types of theory. Thereafter, we look at the proliferation of theories...... to the alternatives currently being practised: integrative pluralism. The article ends on a cautiously optimistic note: given the disciplinary competition that now exists in relation to explaining and understanding global social forces, International Relations may find resilience because it has become theory...

Percolation behavior of tritiated water into a soil packed bed

Energy Technology Data Exchange (ETDEWEB)

Honda, T.; Katayama, K.; Uehara, K.; Fukada, S. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka (Japan); Takeishi, T. [Faculty of Engineering, Kyushu University, Motooka Nishi-ku, Fukuoka (Japan)

2015-03-15

A large amount of cooling water is used in a D-T fusion reactor. The cooling water will contain tritium with high concentration because tritium can permeate metal walls at high temperature easily. A development of tritium handling technology for confining tritiated water in the fusion facility is an important issue. In addition, it is also important to understand tritium behavior in environment assuming severe accidents. In this study, percolation experiments of tritiated water in soil packed bed were carried out and tritium behavior in soil was discussed. Six soil samples were collected in Hakozaki campus of Kyushu University. These particle densities were of the same degree as that of general soils and moisture contents were related to BET surface area. For two soil samples used in the percolation experiment of tritiated water, saturated hydraulic conductivity agreed well with the estimating value by Creager. Tritium retention ratio in the soil packed bed was larger than water retention. This is considered to be due to an effect of tritium sorption on the surface of soil particles. The isotope exchange capacity estimated by assuming that H/T ratio of supplied tritiated water and H/T ratio of surface water of soil particle was equal was comparable to that on cement paste and mortar which were obtained by exposure of tritiated water vapor. (authors)

Percolation behavior of tritiated water into a soil packed bed

International Nuclear Information System (INIS)

Honda, T.; Katayama, K.; Uehara, K.; Fukada, S.; Takeishi, T.

2015-01-01

A large amount of cooling water is used in a D-T fusion reactor. The cooling water will contain tritium with high concentration because tritium can permeate metal walls at high temperature easily. A development of tritium handling technology for confining tritiated water in the fusion facility is an important issue. In addition, it is also important to understand tritium behavior in environment assuming severe accidents. In this study, percolation experiments of tritiated water in soil packed bed were carried out and tritium behavior in soil was discussed. Six soil samples were collected in Hakozaki campus of Kyushu University. These particle densities were of the same degree as that of general soils and moisture contents were related to BET surface area. For two soil samples used in the percolation experiment of tritiated water, saturated hydraulic conductivity agreed well with the estimating value by Creager. Tritium retention ratio in the soil packed bed was larger than water retention. This is considered to be due to an effect of tritium sorption on the surface of soil particles. The isotope exchange capacity estimated by assuming that H/T ratio of supplied tritiated water and H/T ratio of surface water of soil particle was equal was comparable to that on cement paste and mortar which were obtained by exposure of tritiated water vapor. (authors)

New view of relativity theory

International Nuclear Information System (INIS)

Martini, Luiz Cesar

2014-01-01

This article results from Introducing the Dimensional Continuous Space-Time Theory that was published in reference 1. The Dimensional Continuous Space-Time Theory shows a series of facts relative to matter, energy, space and concludes that empty space is inelastic, absolutely stationary, motionless, perpetual, without possibility of deformation neither can it be destroyed or created. A elementary cell of empty space or a certain amount of empty space can be occupied by any quantity of energy or matter without any alteration or deformation. As a consequence of these properties and being a integral part of the theory, the principles of Relativity Theory must be changed to become simple and intuitive.

Fast and Accurate Protein False Discovery Rates on Large-Scale Proteomics Data Sets with Percolator 3.0

Science.gov (United States)

The, Matthew; MacCoss, Michael J.; Noble, William S.; Käll, Lukas

2016-11-01

Percolator is a widely used software tool that increases yield in shotgun proteomics experiments and assigns reliable statistical confidence measures, such as q values and posterior error probabilities, to peptides and peptide-spectrum matches (PSMs) from such experiments. Percolator's processing speed has been sufficient for typical data sets consisting of hundreds of thousands of PSMs. With our new scalable approach, we can now also analyze millions of PSMs in a matter of minutes on a commodity computer. Furthermore, with the increasing awareness for the need for reliable statistics on the protein level, we compared several easy-to-understand protein inference methods and implemented the best-performing method—grouping proteins by their corresponding sets of theoretical peptides and then considering only the best-scoring peptide for each protein—in the Percolator package. We used Percolator 3.0 to analyze the data from a recent study of the draft human proteome containing 25 million spectra (PM:24870542). The source code and Ubuntu, Windows, MacOS, and Fedora binary packages are available from http://percolator.ms/ under an Apache 2.0 license.

Effect of micellar collisions and polyvinylpyrrolidone confinement on the electrical conductivity percolation parameters of water/AOT/isooctane reverse micelles

Science.gov (United States)

Guettari, Moez; Aferni, Ahmed E. L.; Tajouri, Tahar

2017-12-01

The main aim of this paper is the analysis of micellar collisions and polymer confinement effects on the electrical conductivity percolative behavior of water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles. Firstly, we have performed conductance measurements of the system for three AOT to isooctane volume ratio, φm = 0.1 , 0.15 and 0.2 to examine the influence of micellar collisions on the percolation parameters. All the measurements were carried out over the 298.15 K-333.15 K temperature range at a fixed water to AOT molar ratio, W0 = 45 . We have assessed that the rise of micellar collisions frequency enhances the conductance percolation. Secondly, the confinement effect of a water-soluble polymer, polyvinylpyrrolidone (PVP), on the reverse micelles conductance behavior was investigated. Temperature-induced percolation, Tp , have shown a dependence on the polymer concentration, CPVP . It was also observed that for various PVP concentrations, the activation energy of percolation decreases. Finally, the values of the critical exponents determined in the presence and absence of PVP prove that the polymer affects the dynamic of percolation.

Large Dielectric Constant Enhancement in MXene Percolative Polymer Composites

KAUST Repository

Tu, Shao Bo; Jiang, Qiu; Zhang, Xixiang; Alshareef, Husam N.

2018-01-01

near the percolation limit of about 15.0 wt % MXene loading, which surpasses all previously reported composites made of carbon-based fillers in the same polymer. With up to 10 wt % MXene loading, the dielectric loss of the MXene

Degree product rule tempers explosive percolation in the absence of global information

Science.gov (United States)

Trevelyan, Alexander J.; Tsekenis, Georgios; Corwin, Eric I.

2018-02-01

We introduce a guided network growth model, which we call the degree product rule process, that uses solely local information when adding new edges. For small numbers of candidate edges our process gives rise to a second-order phase transition, but becomes first order in the limit of global choice. We provide the set of critical exponents required to characterize the nature of this percolation transition. Such a process permits interventions which can delay the onset of percolation while tempering the explosiveness caused by cluster product rule processes.

Pilot test of bacterial percolation leaching at Fuzhou uranium mine

International Nuclear Information System (INIS)

Fan Baotuan; Liu Jian; Jiang Yngqiong; Cai Chunhui; Jiang Lang; Zhou Renhua; Tong Changning; Zhang Hongli

2006-01-01

Total 18 t uranium ores of Fuzhou Uranium Mine packed in three or four columns in series were leached by bacterial percolation. The results show that without adding any other chemical oxidant such as sodium chlorate, the leaching rate measured by residue is 91.45%-94.48%, leaching time is 50-60 d, acid consumption is 6.17%-7.75%, and residue grade is 0.0149%-0.0208%. Compared with conventional percolation leaching process, the leaching rate is improved by 3%, leaching time is shorted by 26%, and acid consumption is saved by 34%. Accumulation pattern of ΣFe and F - in the process of leaching is discussed. Influence of F - on bacterial growth, regeneration of barren solution as well as correlative techniques are reviewed. (authors)

Conductivity percolation in loosely compacted microcrystalline cellulose: An in situ study by dielectric spectroscopy during densification.

Science.gov (United States)

Nilsson, Martin; Frenning, Göran; Gråsjö, Johan; Alderborn, Göran; Strømme, Maria

2006-10-19

The present study aims at contributing to a complete understanding of the water-induced ionic charge transport in cellulose. The behavior of this transport in loosely compacted microcrystalline cellulose (MCC) powder was investigated as a function of density utilizing a new type of measurement setup, allowing for dielectric spectroscopy measurement in situ during compaction. The ionic conductivity in MCC was found to increase with increasing density until a leveling-out was observed for densities above approximately 0.7 g/cm3. Further, it was shown that the ionic conductivity vs density followed a percolation type behavior signifying the percolation of conductive paths in a 3D conducting network. The density percolation threshold was found to be between approximately 0.2 and 0.4 g/cm3, depending strongly on the cellulose moisture content. The observed percolation behavior was attributed to the forming of interparticulate bonds in the MCC and the percolation threshold dependence on moisture was linked to the moisture dependence of particle rearrangement and plastic deformation in MCC during compaction. The obtained results add to the understanding of the density-dependent water-induced ionic transport in cellulose showing that, at given moisture content, the two major parameters determining the magnitude of the conductivity are the connectedness of the interparticluate bonds and the connectedness of pores with a diameter in the 5-20 nm size range. At densities between approximately 0.7 and 1.2 g/cm3 both the bond and the pore networks have percolated, facilitating charge transport through the MCC compact.

Finite-size effects for anisotropic bootstrap percolation : Logarithmic corrections

NARCIS (Netherlands)

van Enter, Aernout C. D.; Hulshof, Tim

In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

Finite-size effects for anisotropic bootstrap percolation: logerithmic corrections

NARCIS (Netherlands)

Enter, van A.C.D.; Hulshof, T.

2007-01-01

In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

Relativity theory and gravitation

International Nuclear Information System (INIS)

Bondi, H.

1986-01-01

The paper on relativity theory and gravitation is presented as a preface to the first of the articles submitted to the Journal on general relativity. Newtonian gravitation and and observation, relativity, and the sources of the gravitational field, are all discussed. (UK)

Rigidity percolation in dispersions with a structured viscoelastic matrix

NARCIS (Netherlands)

Wilbrink, M.W.L.; Michels, M.A.J.; Vellinga, W.P.; Meijer, H.E.H.

2005-01-01

This paper deals with rigidity percolation in composite materials consisting of a dispersion of mineral particles in a microstructured viscoelastic matrix. The viscoelastic matrix in this specific case is a hydrocarbon refinery residue. In a set of model random composites the mean interparticle

Numerical calculation of the conductivity of percolation clusters and the use of special purpose computers

International Nuclear Information System (INIS)

Herrmann, H.J.

1989-01-01

Electrical conductivity diffusion or phonons, have an anomalous behaviour on percolation clusters at the percolation threshold due to the fractality of these clusters. The results that have been found numerically for this anomalous behaviour are reviewed. A special purpose computer built for this purpose is described and the evaluation of the data from this machine is discussed

Quantum information and relativity theory

International Nuclear Information System (INIS)

Peres, Asher; Terno, Daniel R.

2004-01-01

This article discusses the intimate relationship between quantum mechanics, information theory, and relativity theory. Taken together these are the foundations of present-day theoretical physics, and their interrelationship is an essential part of the theory. The acquisition of information from a quantum system by an observer occurs at the interface of classical and quantum physics. The authors review the essential tools needed to describe this interface, i.e., Kraus matrices and positive-operator-valued measures. They then discuss how special relativity imposes severe restrictions on the transfer of information between distant systems and the implications of the fact that quantum entropy is not a Lorentz-covariant concept. This leads to a discussion of how it comes about that Lorentz transformations of reduced density matrices for entangled systems may not be completely positive maps. Quantum field theory is, of course, necessary for a consistent description of interactions. Its structure implies a fundamental tradeoff between detector reliability and localizability. Moreover, general relativity produces new and counterintuitive effects, particularly when black holes (or, more generally, event horizons) are involved. In this more general context the authors discuss how most of the current concepts in quantum information theory may require a reassessment

Remarks on the percolation problem in anisotropic systems

International Nuclear Information System (INIS)

Chaves, C.M.G.F.; Oliveira, P.M.C. de; Queiroz, S.L.A. de; Riera, R.

1979-07-01

The bond percolation problem is discused in an anisotropic square lattice using the position space renormalization group. It is shown that, due to symmetry, this treatment reproduces known exact results for this problem. The phase diagram and the flow lines in parameter space are also shown. Results are in agreement with universality.(Author) [pt

Relativity, symmetry and the structure of quantum theory

CERN Document Server

Klink, William H; Schweiger, Wolfgang

Quantum theory is one of the most successful of all physical theories. Our everyday world is dominated by devices that function because of knowledge of the quantum world. Yet many, physicists and non-physicists alike, find the theory which explains the behavior of the quantum world baffling and strange. This book is the first in a series of three that argues that relativity and symmetry determine the structure of quantum theory. That is to say, the structure of quantum theory is what it is because of relativity and symmetry. There are different types of relativity, each leading to a particular type of quantum theory. This book deals specifically with what we call Newton relativity, the form of relativity built into Newtonian mechanics, and the quantum theory to which it gives rise, which we call Galilean (often misleadingly called non-relativistic) quantum theory. Key Features: • Meaning and significance of the term of relativity; discussion of the principle of relativity. • Relation of symmetry to relati...

Effect of percolation rate on water-travel time in deep, partially saturated zones

International Nuclear Information System (INIS)

Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

1986-01-01

The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye County, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table in on the order of hundreds of thousands of years. This result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 may initiate water movement in the fractures, reducing the travel time significantly

Universality for first passage percolation on sparse random graphs

NARCIS (Netherlands)

Bhamidi, S.; Van Der Hofstad, R.W.; Hooghiemstra, G.

2017-01-01

We consider first passage percolation on the configuration model with n vertices, and general independent and identically distributed edge weights assumed to have a density. Assuming that the degree distribution satisfies a uniform X2 logX-condition, we analyze the asymptotic distribution for the

Universality for first passage percolation on sparse random graphs

NARCIS (Netherlands)

Bhamidi, S.; Hofstad, van der R.W.; Hooghiemstra, G.

2014-01-01

We consider first passage percolation on the conguration model with n vertices, and general independent and identically distributed edge weights assumed to have a density. Assuming that the degree distribution satisfies a uniform X2 logX-condition, we analyze the asymptotic distribution for the

Relativity the theory and its philosophy

CERN Document Server

Angel, Roger B

1980-01-01

Relativity: The Theory and its Philosophy provides a completely self-contained treatment of the philosophical foundations of the theory of relativity. It also surveys the most essential mathematical techniques and concepts that are indispensable to an understanding of the foundations of both the special and general theories of relativity. In short, the book includes a crash course in applied mathematics, ranging from elementary trigonometry to the classical tensor calculus.Comprised of 11 chapters, this book begins with an introduction to fundamental mathematical concepts such as sets, relatio

Multifractal properties of resistor diode percolation.

Science.gov (United States)

Stenull, Olaf; Janssen, Hans-Karl

2002-03-01

Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the nonpercolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments of the current distribution that are governed by a family of critical exponents [psi(l)]. We calculate the family [psi(l)] to two-loop order in a diagrammatic perturbation calculation augmented by renormalization group methods.

New scaling results in quantum percolation

International Nuclear Information System (INIS)

Srivastava, V.; Chaturvedi, M.

1983-06-01

Scaling arguments for distribution of cluster size and size of localized states have been developed to calculate average number of lattice sites falling under a localized wave function as a function of concentration for a model binary system with ''infinite disorder''. We find distinct features near classical and quantum percolation thresholds. Analytical results are compared with computer-experiment results and the predicted features are found to be confirmed. Possibility of appearance of extended states in two-dimensional binary systems even at infinite disorder is pointed out. (author)

Iz ''general relativity'' necessary for the Einstein gravitation theory gravitation theory

International Nuclear Information System (INIS)

Bondi, G.

1982-01-01

Main principles of relativity and gravitation theories are deeply analyzed. Problems of boundaries of applicability for these theories and possible ways of their change and generalization are discussed. It is shown that the notion of general relativity does not introduce any post-newton physics - it only deals with coordinate transformations. It is supposed that ''general relativity'' is a physically senseless phrase which can be considered only as a historical remainder of an interesting philosophic discourse. The paper reveals that there exists appropriate physical substantiation of the Einstein gravitation theory not including a physically senseless concept of general relativity and promoting its fundamental relations with the experiment

Self Healing Percolation

Science.gov (United States)

Scala, Antonio

2015-03-01

We introduce the concept of self-healing in the field of complex networks modelling; in particular, self-healing capabilities are implemented through distributed communication protocols that exploit redundant links to recover the connectivity of the system. Self-healing is a crucial in implementing the next generation of smart grids allowing to ensure a high quality of service to the users. We then map our self-healing procedure in a percolation problem and analyse the interplay between redundancies and topology in improving the resilience of networked infrastructures to multiple failures. We find exact results both for planar lattices and for random lattices, hinting the role of duality in the design of resilient networks. Finally, we introduce a cavity method approach to study the recovery of connectivity after damage in self-healing networks. CNR-PNR National Project ``Crisis-Lab,'' EU HOME/2013/CIPS/AG/4000005013 project CI2C and EU FET project MULTIPLEX nr.317532.

Percolation Analysis as a Tool to Describe the Topology of the Large Scale Structure of the Universe

Science.gov (United States)

Yess, Capp D.

1997-09-01

Percolation analysis is the study of the properties of clusters. In cosmology, it is the statistics of the size and number of clusters. This thesis presents a refinement of percolation analysis and its application to astronomical data. An overview of the standard model of the universe and the development of large scale structure is presented in order to place the study in historical and scientific context. Then using percolation statistics we, for the first time, demonstrate the universal character of a network pattern in the real space, mass distributions resulting from nonlinear gravitational instability of initial Gaussian fluctuations. We also find that the maximum of the number of clusters statistic in the evolved, nonlinear distributions is determined by the effective slope of the power spectrum. Next, we present percolation analyses of Wiener Reconstructions of the IRAS 1.2 Jy Redshift Survey. There are ten reconstructions of galaxy density fields in real space spanning the range β = 0.1 to 1.0, where β=Ω0.6/b,/ Ω is the present dimensionless density and b is the linear bias factor. Our method uses the growth of the largest cluster statistic to characterize the topology of a density field, where Gaussian randomized versions of the reconstructions are used as standards for analysis. For the reconstruction volume of radius, R≈100h-1 Mpc, percolation analysis reveals a slight 'meatball' topology for the real space, galaxy distribution of the IRAS survey. Finally, we employ a percolation technique developed for pointwise distributions to analyze two-dimensional projections of the three northern and three southern slices in the Las Campanas Redshift Survey and then give consideration to further study of the methodology, errors and application of percolation. We track the growth of the largest cluster as a topological indicator to a depth of 400 h-1 Mpc, and report an unambiguous signal, with high signal-to-noise ratio, indicating a network topology which in

Coding Theory, Cryptography and Related Areas

DEFF Research Database (Denmark)

Buchmann, Johannes; Stichtenoth, Henning; Tapia-Recillas, Horacio

Proceedings of anInternational Conference on Coding Theory, Cryptography and Related Areas, held in Guanajuato, Mexico. in april 1998......Proceedings of anInternational Conference on Coding Theory, Cryptography and Related Areas, held in Guanajuato, Mexico. in april 1998...

Probability theory and applications

CERN Document Server

Hsu, Elton P

1999-01-01

This volume, with contributions by leading experts in the field, is a collection of lecture notes of the six minicourses given at the IAS/Park City Summer Mathematics Institute. It introduces advanced graduates and researchers in probability theory to several of the currently active research areas in the field. Each course is self-contained with references and contains basic materials and recent results. Topics include interacting particle systems, percolation theory, analysis on path and loop spaces, and mathematical finance. The volume gives a balanced overview of the current status of probability theory. An extensive bibliography for further study and research is included. This unique collection presents several important areas of current research and a valuable survey reflecting the diversity of the field.

Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

NARCIS (Netherlands)

Enter, Aernout C.D. van; Fey, Anne

In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

Kinematical Test Theories for Special Relativity

Science.gov (United States)

Lämmerzahl, Claus; Braxmaier, Claus; Dittus, Hansjörg; Müller, Holger; Peters, Achim; Schiller, Stephan

A comparison of certain kinematical test theories for Special Relativity including the Robertson and Mansouri-Sext test theories is presented and the accuracy of the experimental results testing Special Relativity are expressed in terms of the parameters appearing in these test theories. The theoretical results are applied to the most precise experimental results obtained recently for the isotropy of light propagation and the constancy of the speed of light.

Simple recursion relations for general field theories

International Nuclear Information System (INIS)

Cheung, Clifford; Shen, Chia-Hsien; Trnka, Jaroslav

2015-01-01

On-shell methods offer an alternative definition of quantum field theory at tree-level, replacing Feynman diagrams with recursion relations and interaction vertices with a handful of seed scattering amplitudes. In this paper we determine the simplest recursion relations needed to construct a general four-dimensional quantum field theory of massless particles. For this purpose we define a covering space of recursion relations which naturally generalizes all existing constructions, including those of BCFW and Risager. The validity of each recursion relation hinges on the large momentum behavior of an n-point scattering amplitude under an m-line momentum shift, which we determine solely from dimensional analysis, Lorentz invariance, and locality. We show that all amplitudes in a renormalizable theory are 5-line constructible. Amplitudes are 3-line constructible if an external particle carries spin or if the scalars in the theory carry equal charge under a global or gauge symmetry. Remarkably, this implies the 3-line constructibility of all gauge theories with fermions and complex scalars in arbitrary representations, all supersymmetric theories, and the standard model. Moreover, all amplitudes in non-renormalizable theories without derivative interactions are constructible; with derivative interactions, a subset of amplitudes is constructible. We illustrate our results with examples from both renormalizable and non-renormalizable theories. Our study demonstrates both the power and limitations of recursion relations as a self-contained formulation of quantum field theory.

Modified Invasion Percolation Models for Multiphase Processes

Energy Technology Data Exchange (ETDEWEB)

Karpyn, Zuleima [Pennsylvania State Univ., State College, PA (United States)

2015-01-31

This project extends current understanding and modeling capabilities of pore-scale multiphase flow physics in porous media. High-resolution X-ray computed tomography imaging experiments are used to investigate structural and surface properties of the medium that influence immiscible displacement. Using experimental and computational tools, we investigate the impact of wetting characteristics, as well as radial and axial loading conditions, on the development of percolation pathways, residual phase trapping and fluid-fluid interfacial areas.

Percolation effect on electrical, mechanical, and electrochemical properties of Sr{sub 0.8}La{sub 0.2}TiO{sub 3}–Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} composite anodes for solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Koo, Ji-Hoon [Division of Advanced Materials Engineering, Chonbuk National University, Jeonbuk, 561-756 (Korea, Republic of); Lee, Ki-Tae, E-mail: ktlee71@jbnu.ac.kr [Division of Advanced Materials Engineering, Chonbuk National University, Jeonbuk, 561-756 (Korea, Republic of); Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonbuk, 561-756 (Korea, Republic of)

2016-05-15

Both the electrical conductivity and mechanical strength of a Sr{sub 0.8}La{sub 0.2}TiO{sub 3}–Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (SLT-GDC) composite decreased non-linearly as the GDC content increased. In the GDC percolation region, the electrical conductivity and the mechanical strength decreased significantly. Because the carbon deposition rate increased with increasing GDC content, the redox stability decreased. The area specific resistance (ASR) of the SLT-GDC composite anode at 800 °C in H{sub 2} decreased up to 15 vol.% GDC (SLT-GDC15) and then increased at the SLT-GDC20 and the SLT-GDC33 compositions, due to the high electro–catalytic activity and low electrical conductivity of GDC. Consequently, the SLT-GDC15 composition within the mixed region below SLT and GDC percolation limit exhibited the best electrochemical performance due to the optimized electronic and ionic conduction network. - Highlights: • SLT-GDC composite anodes can be designed by percolation theory. • Incorporation of GDC improves catalytic activity. • Composite within SLT percolation threshold exhibits high mechanical strength. • Composite within the mixed percolation region exhibits the best catalytic activity. • Redox stability of the SLT-GDC composite is correlated with GDC volume.

Cluster concentrations in correlated and non-correlated continuum percolation problems

International Nuclear Information System (INIS)

Borstnik, B.; Jesudason, C.G.; Lukman, D.

1996-01-01

The methodologies are developed how to evaluate properties of clusters of correlated and non-correlated particles. As an example of correlated particles, the two dimensional hard core disks with attractive square well potential are taken. Narrow and deep square well potential is used in order to mimic the adhesive potential, suitable for modeling of colloidal systems. Permeable disks in two dimensions are taken as an example of non-correlated systems. In both cases the dependence of cluster concentrations upon the density of particles is studied. Percolation threshold densities and critical exponents which govern the zeroth, first and second moments of cluster distributions are evaluated. It is found that the calculation of density dependence of cluster concentrations gives enough information to evaluate the percolation threshold density, some critical exponents, as well as to reproduce the Rushbrooke scaling law

Damage percolation during stretch flange forming of aluminum alloy sheet

Science.gov (United States)

Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

2005-12-01

A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

Theoretical Insight Into the Empirical Tortuosity-Connectivity Factor in the Burdine-Brooks-Corey Water Relative Permeability Model

Science.gov (United States)

Ghanbarian, Behzad; Ioannidis, Marios A.; Hunt, Allen G.

2017-12-01

A model commonly applied to the estimation of water relative permeability krw in porous media is the Burdine-Brooks-Corey model, which relies on a simplified picture of pores as a bundle of noninterconnected capillary tubes. In this model, the empirical tortuosity-connectivity factor is assumed to be a power law function of effective saturation with an exponent (μ) commonly set equal to 2 in the literature. Invoking critical path analysis and using percolation theory, we relate the tortuosity-connectivity exponent μ to the critical scaling exponent t of percolation that characterizes the power law behavior of the saturation-dependent electrical conductivity of porous media. We also discuss the cause of the nonuniversality of μ in terms of the nonuniversality of t and compare model estimations with water relative permeability from experiments. The comparison supports determining μ from the electrical conductivity scaling exponent t, but also highlights limitations of the model.

Canonical perturbation theory in linearized general relativity theory

International Nuclear Information System (INIS)

Gonzales, R.; Pavlenko, Yu.G.

1986-01-01

Canonical perturbation theory in linearized general relativity theory is developed. It is shown that the evolution of arbitrary dynamic value, conditioned by the interaction of particles, gravitation and electromagnetic fields, can be presented in the form of a series, each member of it corresponding to the contribution of certain spontaneous or induced process. The main concepts of the approach are presented in the approximation of a weak gravitational field

Percolation theory and its application for interpretation of soil water retention curves

International Nuclear Information System (INIS)

Kodesova, R.

2004-01-01

The soil porous system has traditionally been deduced from the soil-water retention curve with the assumption of homogeneity and free accessibility of pores, defined as capillary tubes, from the sink/source of water. But real soil fabric is mostly characterized by aggregates. In this case, the soil porous system cannot be modeled as a homogeneous one. To examine the differences between homogeneous and heterogeneous soil porous systems, we studied two types of soils: sandy soil and coarse sandy soil. We applied image processing filters and the ARC/INFO Grid module to analyze pore sizes in both soils from their electron microscope images taken at two different magnifications. We used the resulting pore-size distribution data to generate 3-D porous media consisting of pores and throats. The homogeneous pore structure was created as a mono-modal pore-throat network with one pore-size distribution. The heterogeneous pore structure was designed as a bi-modal pore-throat network with two pore-size distributions, where the pore sizes were hierarchically arranged in the nodes of the network. We applied the percolation model to simulate water and air displacement in these networks. The distribution of water in the nodes of the networks was studied increasing/decreasing steps of pressure head and the drainage and wetting branches of the retention curves were evaluated. The soil-water retention curves modeled for the mono-modal and bi-modal porous systems had different characters. The simulated shape of the retention curve in the mono-modal case was close to the step-like form of a retention curve characteristic of unstructured soil. The shape of the simulated retention curve in the bi-modal case was smoother, more gradual, and closer to the shape of the retention curve of a real, structured soil. (author)

Ultrathin percolated WO{sub 3} cluster film and its resistive response to H{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zhao, Meng [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Wong, Man Hon; Huang, Jian Xing [Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China); Ong, Chung Wo, E-mail: c.w.ong@polyu.edu.hk [Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

2014-11-05

Highlights: • Ultrathin percolated network of WO{sub 3} clusters was fabricated. • The WO{sub 3} clusters are modeled by spherical caps connected by ultrafine linkages. • The ultrathin percolated network of WO{sub 3} clusters shows fast response rate to H{sub 2}. • The fast response is attributed to the rapid electrical switching of the linkages. • Improved H{sub 2} sensing properties may be achieved if narrower linkages are used. - Abstract: Thin films composed of tungsten oxide (WO{sub 3}) nanoclusters were fabricated by oxidizing supersonic cluster beam deposited tungsten films at various temperatures. Oxidation at 700 °C resulted in aggregation of the deposits, forming a percolated network of WO{sub 3} spherical caps connected by fine links. The resistance response of the palladium-(Pd-) coated film sample to hydrogen (H{sub 2}) was investigated. The response rate was faster than those of other samples oxidized at lower temperatures. This is the result of the rapid electrical switching of the intercluster links between the highly resistive depleted state and conducting hydrogenated state. The possibility of improving the H{sub 2} sensing response rate with the use of the percolated WO{sub 3} film structure is illustrated.

Temporal percolation of the susceptible network in an epidemic spreading.

Science.gov (United States)

Valdez, Lucas Daniel; Macri, Pablo Alejandro; Braunstein, Lidia Adriana

2012-01-01

In this work, we study the evolution of the susceptible individuals during the spread of an epidemic modeled by the susceptible-infected-recovered (SIR) process spreading on the top of complex networks. Using an edge-based compartmental approach and percolation tools, we find that a time-dependent quantity ΦS(t), namely, the probability that a given neighbor of a node is susceptible at time t, is the control parameter of a node void percolation process involving those nodes on the network not-reached by the disease. We show that there exists a critical time t(c) above which the giant susceptible component is destroyed. As a consequence, in order to preserve a macroscopic connected fraction of the network composed by healthy individuals which guarantee its functionality, any mitigation strategy should be implemented before this critical time t(c). Our theoretical results are confirmed by extensive simulations of the SIR process.

Thermal transport in binary colloidal glasses: Composition dependence and percolation assessment

Science.gov (United States)

Ruckdeschel, Pia; Philipp, Alexandra; Kopera, Bernd A. F.; Bitterlich, Flora; Dulle, Martin; Pech-May, Nelson W.; Retsch, Markus

2018-02-01

The combination of various types of materials is often used to create superior composites that outperform the pure phase components. For any rational design, the thermal conductivity of the composite as a function of the volume fraction of the filler component needs to be known. When approaching the nanoscale, the homogeneous mixture of various components poses an additional challenge. Here, we investigate binary nanocomposite materials based on polymer latex beads and hollow silica nanoparticles. These form randomly mixed colloidal glasses on a sub-μ m scale. We focus on the heat transport properties through such binary assembly structures. The thermal conductivity can be well described by the effective medium theory. However, film formation of the soft polymer component leads to phase segregation and a mismatch between existing mixing models. We confirm our experimental data by finite element modeling. This additionally allowed us to assess the onset of thermal transport percolation in such random particulate structures. Our study contributes to a better understanding of thermal transport through heterostructured particulate assemblies.

Percolation pond as a method of managed aquifer recharge in a ...

Indian Academy of Sciences (India)

Raicy Mani Christy

2017-07-17

Jul 17, 2017 ... Percolation ponds have become very popular methods of managed aquifer recharge due to their low ... effect of recharge structures by some researchers .... qualitative comparison of observed responses of .... Two types of.

Theory of the optical and microwave properties of metal-dielectric films

International Nuclear Information System (INIS)

Sarychev, A.K.; Bergman, D.J.; Yagil, Y.

1995-01-01

We present a detailed theoretical study of the high frequency response of thin, metal-dielectric inhomogeneous films. Semicontinuous metal films are normally prepared by thermal evaporation or sputtering of the metal on an insulating substrate. The optical properties of such films show anomalous phenomena, which are absent in both the bulk metal and the bulk insulator. Our approach is based upon a direct solution of Maxwell's equations, without having to invoke the quasi-static approximation. Electric and magnetic fields outside the film are related to the currents inside the film. The electromagnetic properties of semicontinuous films are described by two Ohmic parameters, in contrast with the usual description by a single complex conductivity. Our theory reproduces most of the known experimental data. For example, we are able to explain a prominent absorption band near the percolation threshold, which was observed previously in such systems, as well as some other peculiar features of the reflectance and transmittance. We find that metal-dieletric films can exhibit very interesting properties when there is a strong skin effect in the metal grains. The surface conductivity has a universal value c/(2π) at the percolation threshold. We predict that under such conditions the absorptance A, as a funciton of the metal concentration, is dome shaped with sharp edges. It has a maximum at the percolation threshold and its value at this point is universal, namely A=0.5, while the reflectance R and transmittance T have the equal universal value R=T=0.25. This approach can be extended to semicontinuous superconducting films. Such films are also expected to have a well defined absorption band near the percolation threshold. We believe that such a threshold can be approached not only by decreasing the superconductor concentration but also by increasing the temperature towards and above the critical temperature

Multicentric genesis of material structure: Development of the percolation model and some applications

Science.gov (United States)

Herega, Alexander; Sukhanov, Volodymyr; Vyrovoy, Valery

2016-11-01

The multiplicative measure and estimation method of ordering of the nearest neighborhood at the multiscale "site" percolation problem are considered. In the report also is shown the possibility of quantifying a relative degree of order of two nearest neighborhoods, which is based on the algorithm proposed by one of the authors. Moreover, the model of the oscillatory component of interaction of inner boundaries of different scales is proposed. In the context of our report, the concept of lacunarity and effective dimension (introduced by B. Mandelbrot) is discussed as effective tools of mathematical modeling.

Measurement of cation exchange capacity (CEC) on natural zeolite by percolation method

Science.gov (United States)

Wiyantoko, Bayu; Rahmah, Nafisa

2017-12-01

The cation exchange capacity (CEC)measurement has been carried out in natural zeolite by percolation method. The natural zeolite samples used for cation exchange capacity measurement were activated beforehand with physical activation and chemical activation. The physically activated zeolite was done by calcination process at 600 °C for 4 hours. The natural zeolite was activated chemically by using sodium hydroxide by refluxing process at 60-80 °C for 3 hours. In summary, cation exchange capacity (CEC) determination was performed by percolation, distillation and titration processes. Based on the measurement that has been done, the exchange rate results from physical activated and chemical activated of natural zeolite were 181.90cmol (+)/kg and 901.49cmol (+)/kg respectively.

Hispanic Culture and Relational Cultural Theory

Science.gov (United States)

Ruiz, Elizabeth

2005-01-01

Traditional personality theories do not consider the impact of culture on personality development. Yet, to provide culturally relevant services to the increasing Hispanic population in the U.S., more culturally relevant theories must be identified. This paper presents Relational Cultural Theory (RCT) as an alternative model to understanding…

AC and DC electrical behavior of MWCNT/epoxy nanocomposite near percolation threshold: Equivalent circuits and percolation limits

Science.gov (United States)

Alizadeh Sahraei, Abolfazl; Ayati, Moosa; Baniassadi, Majid; Rodrigue, Denis; Baghani, Mostafa; Abdi, Yaser

2018-03-01

This study attempts to comprehensively investigate the effects of multi-walled carbon nanotubes (MWCNTs) on the AC and DC electrical conductivity of epoxy nanocomposites. The samples (0.2, 0.3, and 0.5 wt. % MWCNT) were produced using a combination of ultrason and shear mixing methods. DC measurements were performed by continuous measurement of the current-voltage response and the results were analyzed via a numerical percolation approach, while for the AC behavior, the frequency response was studied by analyzing phase difference and impedance in the 10 Hz to 0.2 MHz frequency range. The results showed that the dielectric parameters, including relative permittivity, impedance phase, and magnitude, present completely different behaviors for the frequency range and MWCNT weight fractions studied. To better understand the nanocomposites electrical behavior, equivalent electric circuits were also built for both DC and AC modes. The DC equivalent networks were developed based on the current-voltage curves, while the AC equivalent circuits were proposed by using an optimization problem according to the impedance magnitude and phase at different frequencies. The obtained equivalent electrical circuits were found to be highly useful tools to understand the physical mechanisms involved in MWCNT filled polymer nanocomposites.

Electrical Properties of Zinc-Kaolin Composites below its Percolation ...

African Journals Online (AJOL)

In this paper, we present some electrical properties of the zinc-kaolin cermet resistors with zinc metal fillers below the percolation threshold. Rectangular cermet rods of dimensions 65 mm by 6.5 mm by 3.2 mm were produced in a mould with semi-dry the zinc/kaolin powder mixture which is compressed with a force of about ...

Probing the energy barriers and magnetization reversal processes of nanoperforated membrane based percolated media

International Nuclear Information System (INIS)

Neu, V; Schultz, L; Schulze, C; Makarov, D; Albrecht, M; Faustini, M; Grosso, D; Lee, J; Kim, S-K; Suess, D

2013-01-01

Magnetization reversal processes in Co/Pt multilayers prepared on nanoperforated templates are probed by magnetization relaxation measurements. The signature of pinning controlled domain wall movement as expected for percolated media is identified. This contrasts with the nucleation-type reversal mechanism of a Co/Pt reference film prepared on a smooth substrate. A zero field energy barrier of 93k B T is determined by fluctuation field measurements and is elucidated by micromagnetic calculations using the nudged elastic band method. This value is sufficiently large to qualify the material as a promising percolated medium. (paper)

Rethinking Rice Preparation for Highly Efficient Removal of Inorganic Arsenic Using Percolating Cooking Water.

Science.gov (United States)

Carey, Manus; Jiujin, Xiao; Gomes Farias, Júlia; Meharg, Andrew A

2015-01-01

A novel way of cooking rice to maximize the removal of the carcinogen inorganic arsenic (Asi) is presented here. In conventional rice cooking water and grain are in continuous contact, and it is known that the larger the water:rice cooking ratio, the more Asi removed by cooking, suggesting that the Asi in the grain is mobile in water. Experiments were designed where rice is cooked in a continual stream of percolating near boiling water, either low in Asi, or Asi free. This has the advantage of not only exposing grain to large volumes of cooking water, but also physically removes any Asi leached from the grain into the water receiving vessel. The relationship between cooking water volume and Asi removal in conventional rice cooking was demonstrated for the rice types under study. At a water-to-rice cooking ratio of 12:1, 57±5% of Asi could be removed, average of 6 wholegrain and 6 polished rice samples. Two types of percolating technology were tested, one where the cooking water was recycled through condensing boiling water steam and passing the freshly distilled hot water through the grain in a laboratory setting, and one where tap water was used to cook the rice held in an off-the-shelf coffee percolator in a domestic setting. Both approaches proved highly effective in removing Asi from the cooking rice, with up to 85% of Asi removed from individual rice types. For the recycled water experiment 59±8% and 69±10% of Asi was removed, on average, compared to uncooked rice for polished (n=27) and wholegrain (n=13) rice, respectively. For coffee percolation there was no difference between wholegrain and polished rice, and the effectiveness of Asi removal was 49±7% across 6 wholegrain and 6 polished rice samples. The manuscript explores the potential applications and further optimization of this percolating cooking water, high Asi removal, discovery.

Rapid self-organised initiation of ad hoc sensor networks close above the percolation threshold

Science.gov (United States)

Korsnes, Reinert

2010-07-01

This work shows potentials for rapid self-organisation of sensor networks where nodes collaborate to relay messages to a common data collecting unit (sink node). The study problem is, in the sense of graph theory, to find a shortest path tree spanning a weighted graph. This is a well-studied problem where for example Dijkstra’s algorithm provides a solution for non-negative edge weights. The present contribution shows by simulation examples that simple modifications of known distributed approaches here can provide significant improvements in performance. Phase transition phenomena, which are known to take place in networks close to percolation thresholds, may explain these observations. An initial method, which here serves as reference, assumes the sink node starts organisation of the network (tree) by transmitting a control message advertising its availability for its neighbours. These neighbours then advertise their current cost estimate for routing a message to the sink. A node which in this way receives a message implying an improved route to the sink, advertises its new finding and remembers which neighbouring node the message came from. This activity proceeds until there are no more improvements to advertise to neighbours. The result is a tree network for cost effective transmission of messages to the sink (root). This distributed approach has potential for simple improvements which are of interest when minimisation of storage and communication of network information are a concern. Fast organisation of the network takes place when the number k of connections for each node ( degree) is close above its critical value for global network percolation and at the same time there is a threshold for the nodes to decide to advertise network route updates.

Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

Science.gov (United States)

Perrier, E. M. A.; Bird, N. R. A.; Rieutord, T. B.

2010-10-01

Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a critical filtration size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

Directory of Open Access Journals (Sweden)

E. M. A. Perrier

2010-10-01

Full Text Available Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a critical filtration size (CFS delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009. Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

Percolation simulation of laser-guided electrical discharges.

Science.gov (United States)

Sasaki, Akira; Kishimoto, Yasuaki; Takahashi, Eiichi; Kato, Susumu; Fujii, Takashi; Kanazawa, Seiji

2010-08-13

A three-dimensional simulation of laser-guided discharges based on percolation is presented. The model includes both local growth of a streamer due to the enhanced electric field at the streamer's tip and propagation of a leader by remote ionization such as that caused by runaway electrons. The stochastic behavior of the discharge through a preformed plasma channel is reproduced by the calculation, which shows complex path with detouring and bifurcation. The probability of guiding is investigated with respect to the ionized, conductive fraction along the channel.

Some relations of parameters in quantum field theory

International Nuclear Information System (INIS)

Ishikawa, K.

1986-01-01

Two schemes of parameter relations, linear relation and non-linear relation are discussed. The linear relation of coupling constants is derived directly from an underlying symmetry of the classical theory and is preserved usually in the quantum theory. The non-linear relation is not derived by a same manner but is derived by more involved way which is intrinsically connected with quantum theory. An underlying symmetry which leads the linear relation is shown to be essential in the non-linear relation too. Some extension is also discussed

Note: Optimization of the numerical data analysis for conductivity percolation studies of drying moist porous systems

Energy Technology Data Exchange (ETDEWEB)

Moscicki, J. K.; Sokolowska, D.; Dziob, D.; Nowak, J. [Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Kwiatkowski, L. [Department of Econometrics and Operations Research, Cracow University of Economics, Rakowicka 27, 31-510 Krakow (Poland)

2014-02-15

A simplified data analysis protocol, for dielectric spectroscopy use to study conductivity percolation in dehydrating granular media is discussed. To enhance visibility of the protonic conductivity contribution to the dielectric loss spectrum, detrimental effects of either low-frequency dielectric relaxation or electrode polarization are removed. Use of the directly measurable monofrequency dielectric loss factor rather than estimated DC conductivity to parameterize the percolation transition substantially reduces the analysis work and time.

When interflow also percolates: downslope travel distances and hillslope process zones.

Energy Technology Data Exchange (ETDEWEB)

Jackson, C. Rhett [Warnell School of Forestry and Natural Resources, University of Georgia, GA 30602 Athens USA; Bitew, Menberu [Warnell School of Forestry and Natural Resources, University of Georgia, GA 30602 Athens USA; Du, Enhao [Climate Science Department, Lawrence Berkeley National Laboratory, CA 94720 Berkeley USA

2014-02-17

In hillslopes with soils characterized by deep regoliths, such as Ultisols,Oxisols, and Alfisols, interflow occurs episodically over impeding layers near and parallel to the soil surface such as low-conductivity B horizons (e.g.Newman et al., 1998; Buttle andMcDonald, 2002; Du et al., In Review), till layers (McGlynn et al., 1999; Bishop et al., 2004), hardpans (McDaniel et al., 2008), C horizons (Detty and McGuire, 2010), and permeable bedrock (Tromp van Meerveld et al., 2007). As perched saturation develops within and above these impeding but permeable horizons, flow moves laterally downslope, but the perched water also continues to percolate through the impeding horizon to the unsaturated soils and saprolite below. Perched water and solutes will eventually traverse the zone of perched saturation above the impeding horizon and then enter and percolate through the impeding horizon. In such flow situations, only lower hillslope segments with sufficient downslope travel distance will deliver water to the riparian zone within the time scale of a storm.farther up the slope, lateral flow within the zone of perched saturation. will act mainly to shift the point of percolation (location where a water packet leaves the downslope flow zone in the upper soil layer and enters the impeding layer) down the hillslope from the point of infiltration. In flatter parts of the hillslope or in areas with little contrast between the conductivities of the upper and impeding soil layers, lateral flow distances will be negligible.

Mean-field theory of spin-glasses with finite coordination number

Science.gov (United States)

Kanter, I.; Sompolinsky, H.

1987-01-01

The mean-field theory of dilute spin-glasses is studied in the limit where the average coordination number is finite. The zero-temperature phase diagram is calculated and the relationship between the spin-glass phase and the percolation transition is discussed. The present formalism is applicable also to graph optimization problems.

Possible Experiments to test Einstein's Special Relativity Theory

OpenAIRE

de Haan, Victor Otto

2011-01-01

All of the experiments supporting Einstein's Special Relativity Theory are also supportive of the Lorentz ether theory, or many other ether theories. However, a growing number of experiments show deviations from Einstein's Special Relativity Theory, but are supporting more extended theories. Some of these experiments are reviewed and analyzed. Unfortunately, many experiments are not of high quality, never repeated and mostly both. It is proposed that the most promising experiments should be r...

Predicting deep percolation with eddy covariance under mulch drip irrigation

Science.gov (United States)

Ming, Guanghui; Tian, Fuqiang; Hu, Hongchang

2016-04-01

Water is essential for the agricultural development and ecological sustainability of the arid and semi-arid oasis with rare precipitation input and high evaporation demand. Deep percolation (DP) defined as excess irrigation water percolating below the plant root zone will reduce irrigation water use efficiency (WUE). But the DP was often ignored in mulch drip irrigation (MDI) which has reached the area of 1.6 million hectares in Xinjiang, the northwest of China. In this study DP experiments were conducted at an agricultural experiment station located within an irrigation district in the Tarim River Basin for four cotton growing periods. First it was detected the irrigation water infiltrated into the soil layers below 100cm and the groundwater level responded to the irrigation events well. Then DP below 100cm soil layers was calculated using the soil water balance method with the aid of eddy covariance (with the energy balance closure of 0.72). The negative DP (groundwater contribution to the crop-water use through capillary rising) at the seedling and harvesting stages can reach 77mm and has a good negative correlation with the groundwater level and positive correlation with potential evaporation. During the drip irrigation stage approximately 45% of the irrigation became DP and resulted in the low irrigation WUE of 0.6. The DP can be 164mm to 270mm per year which was positive linearly correlated to irrigation depth and negative linear correlated to irrigation interval. It is better to establish the irrigation schedule with small irrigation depth and given frequently to reduce deep percolation and meet crop needs.

Memory effects, two color percolation, and the temperature dependence of Mott variable-range hopping

Science.gov (United States)

Agam, Oded; Aleiner, Igor L.

2014-06-01

There are three basic processes that determine hopping transport: (a) hopping between normally empty sites (i.e., having exponentially small occupation numbers at equilibrium), (b) hopping between normally occupied sites, and (c) transitions between normally occupied and unoccupied sites. In conventional theories all these processes are considered Markovian and the correlations of occupation numbers of different sites are believed to be small (i.e., not exponential in temperature). We show that, contrary to this belief, memory effects suppress the processes of type (c) and manifest themselves in a subleading exponential temperature dependence of the variable-range hopping conductivity. This temperature dependence originates from the property that sites of type (a) and (b) form two independent resistor networks that are weakly coupled to each other by processes of type (c). This leads to a two-color percolation problem which we solve in the critical region.

The Lorentz Theory of Electrons and Einstein's Theory of Relativity

Science.gov (United States)

Goldberg, Stanley

1969-01-01

Traces the development of Lorentz's theory of electrons as applied to the problem of the electrodynamics of moving bodies. Presents evidence that the principle of relativity did not play an important role in Lorentz's theory, and that though Lorentz eventually acknowledged Einstein's work, he was unwilling to completely embrace the Einstein…

Spatial and temporal dynamics of deep percolation, lag time and recharge in an irrigated semi-arid region

Science.gov (United States)

Nazarieh, F.; Ansari, H.; Ziaei, A. N.; Izady, A.; Davari, K.; Brunner, P.

2018-05-01

The time required for deep percolating water to reach the water table can be considerable in areas with a thick vadose zone. Sustainable groundwater management, therefore, has to consider the spatial and temporal dynamics of groundwater recharge. The key parameters that control the lag time have been widely examined in soil physics using small-scale lysimeters and modeling studies. However, only a small number of studies have analyzed how deep-percolation rates affect groundwater recharge dynamics over large spatial scales. This study examined how the parameters influencing lag time affect groundwater recharge in a semi-arid catchment under irrigation (in northeastern Iran) using a numerical modeling approach. Flow simulations were performed by the MODFLOW-NWT code with the Vadose-Zone Flow (UZF) Package. Calibration of the groundwater model was based on data from 48 observation wells. Flow simulations showed that lag times vary from 1 to more than 100 months. A sensitivity analysis demonstrated that during drought conditions, the lag time was highly sensitive to the rate of deep percolation. The study illustrated two critical points: (1) the importance of providing estimates of the lag time as a basis for sustainable groundwater management, and (2) lag time not only depends on factors such as soil hydraulic conductivity or vadose zone depth but also depends on the deep-percolation rates and the antecedent soil-moisture condition. Therefore, estimates of the lag time have to be associated with specific percolation rates, in addition to depth to groundwater and soil properties.

Magnetic fields, special relativity and potential theory elementary electromagnetic theory

CERN Document Server

Chirgwin, B H; Kilmister, C W

1972-01-01

Magnetic Fields, Special Relativity and Potential Theory is an introduction to electromagnetism, special relativity, and potential theory, with emphasis on the magnetic field of steady currents (magnetostatics). Topics covered range from the origin of the magnetic field and the magnetostatic scalar potential to magnetization, electromagnetic induction and magnetic energy, and the displacement current and Maxwell's equations. This volume is comprised of five chapters and begins with an overview of magnetostatics, followed by a chapter on the methods of solving potential problems drawn from elec

Electron percolation in realistic models of carbon nanotube networks

International Nuclear Information System (INIS)

Simoneau, Louis-Philippe; Villeneuve, Jérémie; Rochefort, Alain

2015-01-01

The influence of penetrable and curved carbon nanotubes (CNT) on the charge percolation in three-dimensional disordered CNT networks have been studied with Monte-Carlo simulations. By considering carbon nanotubes as solid objects but where the overlap between their electron cloud can be controlled, we observed that the structural characteristics of networks containing lower aspect ratio CNT are highly sensitive to the degree of penetration between crossed nanotubes. Following our efficient strategy to displace CNT to different positions to create more realistic statistical models, we conclude that the connectivity between objects increases with the hard-core/soft-shell radii ratio. In contrast, the presence of curved CNT in the random networks leads to an increasing percolation threshold and to a decreasing electrical conductivity at saturation. The waviness of CNT decreases the effective distance between the nanotube extremities, hence reducing their connectivity and degrading their electrical properties. We present the results of our simulation in terms of thickness of the CNT network from which simple structural parameters such as the volume fraction or the carbon nanotube density can be accurately evaluated with our more realistic models

Electron percolation in realistic models of carbon nanotube networks

Science.gov (United States)

Simoneau, Louis-Philippe; Villeneuve, Jérémie; Rochefort, Alain

2015-09-01

The influence of penetrable and curved carbon nanotubes (CNT) on the charge percolation in three-dimensional disordered CNT networks have been studied with Monte-Carlo simulations. By considering carbon nanotubes as solid objects but where the overlap between their electron cloud can be controlled, we observed that the structural characteristics of networks containing lower aspect ratio CNT are highly sensitive to the degree of penetration between crossed nanotubes. Following our efficient strategy to displace CNT to different positions to create more realistic statistical models, we conclude that the connectivity between objects increases with the hard-core/soft-shell radii ratio. In contrast, the presence of curved CNT in the random networks leads to an increasing percolation threshold and to a decreasing electrical conductivity at saturation. The waviness of CNT decreases the effective distance between the nanotube extremities, hence reducing their connectivity and degrading their electrical properties. We present the results of our simulation in terms of thickness of the CNT network from which simple structural parameters such as the volume fraction or the carbon nanotube density can be accurately evaluated with our more realistic models.

Ising percolation in a three-state majority vote model

Science.gov (United States)

Balankin, Alexander S.; Martínez-Cruz, M. A.; Gayosso Martínez, Felipe; Mena, Baltasar; Tobon, Atalo; Patiño-Ortiz, Julián; Patiño-Ortiz, Miguel; Samayoa, Didier

2017-02-01

In this Letter, we introduce a three-state majority vote model in which each voter adopts a state of a majority of its active neighbors, if exist, but the voter becomes uncommitted if its active neighbors are in a tie, or all neighbors are the uncommitted. Numerical simulations were performed on square lattices of different linear size with periodic boundary conditions. Starting from a random distribution of active voters, the model leads to a stable non-consensus state in which three opinions coexist. We found that the "magnetization" of the non-consensus state and the concentration of uncommitted voters in it are governed by an initial composition of system and are independent of the lattice size. Furthermore, we found that a configuration of the stable non-consensus state undergoes a second order percolation transition at a critical concentration of voters holding the same opinion. Numerical simulations suggest that this transition belongs to the same universality class as the Ising percolation. These findings highlight the effect of an updating rule for a tie between voter neighbors on the critical behavior of models obeying the majority vote rule whenever a strict majority exists.

Nonlinear Analysis on Cross-Correlation of Financial Time Series by Continuum Percolation System

Science.gov (United States)

Niu, Hongli; Wang, Jun

We establish a financial price process by continuum percolation system, in which we attribute price fluctuations to the investors’ attitudes towards the financial market, and consider the clusters in continuum percolation as the investors share the same investment opinion. We investigate the cross-correlations in two return time series, and analyze the multifractal behaviors in this relationship. Further, we study the corresponding behaviors for the real stock indexes of SSE and HSI as well as the liquid stocks pair of SPD and PAB by comparison. To quantify the multifractality in cross-correlation relationship, we employ multifractal detrended cross-correlation analysis method to perform an empirical research for the simulation data and the real markets data.

Double site-bond percolation model for biomaterial implants

OpenAIRE

Mely, H.; Mathiot, J. -F.

2011-01-01

9 figures - 10 pages; We present a double site-bond percolation model to account, on the one hand, for the vascularization and/or resorption of biomaterial implant in bones, and on the other hand, for its mechanical continuity. The transformation of the implant into osseous material, and the dynamical formation/destruction of this osseous material is accounted for by creation and destruction of links and sites in two, entangled, networks. We identify the relevant parameters to describe the im...

The influence of percolation rate on the weathering rates of silicates in an E horizon of an Umbric Albaqualf

NARCIS (Netherlands)

Salm, van der C.; Verstraten, J.M.; Tiktak, A.

1996-01-01

Weathering rates from laboratory experiments are generally one or two orders of magnitude larger than field weathering rates. To obtain more information on this gap a large undisturbed soil column was percolated with a hydrochloric/sulphuric acid solution at rates of 0.15-0.89 cm/d. The percolate

Quantum relativity theory and quantum space-time

International Nuclear Information System (INIS)

Banai, M.

1984-01-01

A quantum relativity theory formulated in terms of Davis' quantum relativity principle is outlined. The first task in this theory as in classical relativity theory is to model space-time, the arena of natural processes. It is shown that the quantum space-time models of Banai introduced in another paper is formulated in terms of Davis's quantum relativity. The recently proposed classical relativistic quantum theory of Prugovecki and his corresponding classical relativistic quantum model of space-time open the way to introduce, in a consistent way, the quantum space-time model (the quantum substitute of Minkowski space) of Banai proposed in the paper mentioned. The goal of quantum mechanics of quantum relativistic particles living in this model of space-time is to predict the rest mass system properties of classically relativistic (massive) quantum particles (''elementary particles''). The main new aspect of this quantum mechanics is that it provides a true mass eigenvalue problem, and that the excited mass states of quantum relativistic particles can be interpreted as elementary particles. The question of field theory over quantum relativistic model of space-time is also discussed. Finally it is suggested that ''quarks'' should be considered as quantum relativistic particles. (author)

Nonlinear random resistor diode networks and fractal dimensions of directed percolation clusters.

Science.gov (United States)

Stenull, O; Janssen, H K

2001-07-01

We study nonlinear random resistor diode networks at the transition from the nonpercolating to the directed percolating phase. The resistor-like bonds and the diode-like bonds under forward bias voltage obey a generalized Ohm's law V approximately I(r). Based on general grounds such as symmetries and relevance we develop a field theoretic model. We focus on the average two-port resistance, which is governed at the transition by the resistance exponent straight phi(r). By employing renormalization group methods we calculate straight phi(r) for arbitrary r to one-loop order. Then we address the fractal dimensions characterizing directed percolation clusters. Via considering distinct values of the nonlinearity r, we determine the dimension of the red bonds, the chemical path, and the backbone to two-loop order.

Nuclear fragmentation with secondary decay in the context of conventional percolation model

International Nuclear Information System (INIS)

Santiago, A.J.

1989-09-01

Mass and energy spectra arising from proton-nucleus collisions at energies between 80 and 350 GeV were studied, using the conventional percolation model coupled with secondary decay of the clusters. (L.C.J.A.)

Investigations into quantum theory and relativity theory

International Nuclear Information System (INIS)

Cox, I.D.

1982-03-01

This thesis falls into two parts. The first is concerned with damping theory as a particular approach to the description of the dynamical evolution of non-closed systems. Appealing ultimately to the Liouville/Von-Neuman equation in the weak coupling regime, the current-voltage characteristics of both the normal and Josephson tunnelling junctions, treated as open systems are obtained. It is then shown that the same results may be obtained via the combined scattering and density matrix formalism (which does not appeal to the Liouville/Von-Neuman equation), and that this method has certain advantages over the conventional formalism. In the second part an extended (non-quantum) theory of relativity in a five dimensional space is developed and a number of interesting consequences thereof obtained. In particular a generalised set of Maxwell equations for electro-dynamics is derived, and some of the implications of the new set of equations are described. Furthermore a treatment of the five-dimensional analogue of the Schwarzschild problem in general relativity is given, together with the resulting implications for planetary motion. (author)

70 years of the general theory of relativity

International Nuclear Information System (INIS)

Castro Diaz-Balart, F.; Cabezas Solorzano, R.

1986-06-01

In view of the 70th anniversary of the discovery of the General Theory of Relativity, an analysis was made of the special and general theories. The basic postulates, their consequences in the formulation of the theories, the main results, some aspects related to the experimental verification and its applications are presented, as are some elements of the mathematical formalism of the theories, to facilitate the logical interrelationships between its results and consequences. (author)

Effects of surfaces on resistor percolation.

Science.gov (United States)

Stenull, O; Janssen, H K; Oerding, K

2001-05-01

We study the effects of surfaces on resistor percolation at the instance of a semi-infinite geometry. Particularly we are interested in the average resistance between two connected ports located on the surface. Based on general grounds as symmetries and relevance we introduce a field theoretic Hamiltonian for semi-infinite random resistor networks. We show that the surface contributes to the average resistance only in terms of corrections to scaling. These corrections are governed by surface resistance exponents. We carry out renormalization-group improved perturbation calculations for the special and the ordinary transition. We calculate the surface resistance exponents phiS and phiS(infinity) for the special and the ordinary transition, respectively, to one-loop order.

Modeling and Performing Relational Theories in the Classroom

Science.gov (United States)

Suter, Elizabeth A.; West, Carrie L.

2011-01-01

Although directly related to students' everyday lives, the abstract and even intimidating nature of relational theories often bars students from recognizing the immediate relevance to their relationships. The theories of symbolic interactionism, social exchange, relational dialectics, social penetration, and uncertainty reduction offer students…

Percolation Analysis of a Wiener Reconstruction of the IRAS 1.2 Jy Redshift Catalog

Science.gov (United States)

Yess, Capp; Shandarin, Sergei F.; Fisher, Karl B.

1997-01-01

We present percolation analyses of Wiener reconstructions of the IRAS 1.2 Jy redshift survey. There are 10 reconstructions of galaxy density fields in real space spanning the range β = 0.1-1.0, where β = Ω0.6/b, Ω is the present dimensionless density, and b is the bias factor. Our method uses the growth of the largest cluster statistic to characterize the topology of a density field, where Gaussian randomized versions of the reconstructions are used as standards for analysis. For the reconstruction volume of radius R ~ 100 h-1 Mpc, percolation analysis reveals a slight ``meatball'' topology for the real space, galaxy distribution of the IRAS survey.

Some relations between twisted K-theory and E8 gauge theory

International Nuclear Information System (INIS)

Mathai, Varghese; Sati, Hisham

2004-01-01

Recently, Diaconescu, Moore and Witten provided a nontrivial link between K-theory and M-theory, by deriving the partition function of the Ramond-Ramond fields of Type IIA string theory from an E8 gauge theory in eleven dimensions. We give some relations between twisted K-theory and M-theory by adapting the method of Diaconescu-Moore-Witten and Moore-Saulina. In particular, we construct the twisted K-theory torus which defines the partition function, and also discuss the problem from the E8 loop group picture, in which the Dixmier-Douady class is the Neveu-Schwarz field. In the process of doing this, we encounter some mathematics that is new to the physics literature. In particular, the eta differential form, which is the generalization of the eta invariant, arises naturally in this context. We conclude with several open problems in mathematics and string theory. (author)

Percolation model for electron conduction in films of metal nanoparticles linked by organic molecules

International Nuclear Information System (INIS)

Muller, K.H.; Herrmann, J.; Raguse, B.; Baxter, G.; Reda, T.

2002-01-01

Full text: We have investigated theoretically and experimentally the temperature dependence of the conductance of films of Au nanoparticles linked by alkane dithiol molecules in the temperature range between 5 K and 300 K. Conduction in these films is due to tunneling of single electrons between neighbouring metal nanoparticles. During tunnelling an electron has to overcome the Coulomb charging energy. We find that the observed temperature dependence of the conductance is non-Arrhenius like and can be described in terms of a percolation theory which takes account of disorder in the system. Disorder in our nanoparticle films is caused by variations in the nanoparticle size, fluctuations in the separation gaps between adjacent nanoparticles and by offset charges. To explain in detail our experimental data, a wide distribution of separation gaps and charging energies is needed. We find that a wide Coulomb charging energy distribution can arise from random offset charges even if the nanoparticle size distribution is narrow

Consistency relations in effective field theory

Energy Technology Data Exchange (ETDEWEB)

Munshi, Dipak; Regan, Donough, E-mail: D.Munshi@sussex.ac.uk, E-mail: D.Regan@sussex.ac.uk [Astronomy Centre, School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH (United Kingdom)

2017-06-01

The consistency relations in large scale structure relate the lower-order correlation functions with their higher-order counterparts. They are direct outcome of the underlying symmetries of a dynamical system and can be tested using data from future surveys such as Euclid. Using techniques from standard perturbation theory (SPT), previous studies of consistency relation have concentrated on continuity-momentum (Euler)-Poisson system of an ideal fluid. We investigate the consistency relations in effective field theory (EFT) which adjusts the SPT predictions to account for the departure from the ideal fluid description on small scales. We provide detailed results for the 3D density contrast δ as well as the scaled divergence of velocity θ-bar . Assuming a ΛCDM background cosmology, we find the correction to SPT results becomes important at k ∼> 0.05 h/Mpc and that the suppression from EFT to SPT results that scales as square of the wave number k , can reach 40% of the total at k ≈ 0.25 h/Mpc at z = 0. We have also investigated whether effective field theory corrections to models of primordial non-Gaussianity can alter the squeezed limit behaviour, finding the results to be rather insensitive to these counterterms. In addition, we present the EFT corrections to the squeezed limit of the bispectrum in redshift space which may be of interest for tests of theories of modified gravity.

The theories of relativity

International Nuclear Information System (INIS)

Deruelle, N.; Uzan, J.P.

2014-01-01

This book is a quite complete route towards general relativity via special relativity with a start point at Newton's mechanics. The mathematical formulation is based on tensors. All the relativistic aspects of only classical physics - it means no quantum mechanics - are exposed. This book is divided into 3 books and each book represents a consistent knowledge of physics at a certain time in the past: in Newton's time, in the second half of the 19. century and today. The advantage of this presentation is to make the reader feels the changes over time in the concepts of time, space, gravity, cosmology. Each book is divided into 3, 4 and 5 parts which are sub-divided into numerous chapters. Book 1: Space, time and gravity in Newton's theory, with part 1: kinematics, part 2: dynamics and part 3: gravity. Book 2: Special relativity and Maxwell's theory, with part 1: kinematics, part 2: dynamics, part 3: electromagnetism and part 4: electrodynamics. And Book 3: General relativity and gravity, with part 1: curved space-time and gravity, part 2: Schwarzschild solution and black holes, part 3: general relativity and experiments, part 4: Friedman-Lemaitre solutions and cosmology, and part 5: elements or Riemann geometry. The 3. book dedicated to general relativity, tackles topics like the relationships between space-time curvature and gravity, Schwarzschild solutions and black holes, gravitational waves, Friedmann-Lemaitre solutions and cosmology, and Riemann geometry. (A.C.)

Continuum (scaling) limits of lattice field theories (triviality of lambda/phi/4 in D greater than or equal to dimensions)

International Nuclear Information System (INIS)

Frohlich, J.

1983-01-01

The author describes some recent techniques for constructing the continuum (= scaling) limit of lattice field theories, including the one- and two- component lambda/less than or equal to→/phi// 4 theories and the Ising and rotator models in a space (- imaginary time) of dimension d >greater than or equal to 4. These techniques should have applications to other related models, like the selfavoiding random walk in five or more dimensions and bond percolation in seven or more dimensions. Some plausible conjectures concerning the Gaussian nature of the scaling limit of the d greater than or equal to 2 dimensional rotator model and the d greater than or equal to 4 dimensional U(1) lattice gauge theory in the low temperature (weak coupling) phase are described

Relativity and equivalence principles in the gauge theory of gravitation

International Nuclear Information System (INIS)

Ivanenko, D.; Sardanashvili, G.

1981-01-01

Roles of relativity (RP) and equivalence principles (EP) in the gauge theory of gravity are shown. RP in the gravitational theory in formalism of laminations can be formulated as requirement of covariance of equations relative to the GL + (4, R)(X) gauge group. In such case RP turns out to be identical to the gauge principle in the gauge theory of a group of outer symmetries, and the gravitational theory can be directly constructed as the gauge theory. In general relativity theory the equivalence theory adds RP and is intended for description of transition to a special relativity theory in some system of reference. The approach described takes into account that in the gauge theory, besides gauge fields under conditions of spontaneous symmetry breaking, the Goldstone and Higgs fields can also arise, to which the gravitational metric field is related, what is the sequence of taking account of RP in the gauge theory of gravitation [ru

Cell percolation model for electrical conduction of granular superconducting composites. 2

International Nuclear Information System (INIS)

Horvath, G.; Bankuti, J.

1990-01-01

The percolation of the electrical conductivity of the uniform cells is studied in an in-situ elongated granular superconducting composite on the basis of the uniform cell model improved previously. The critical temperatures are determined in the macroscopic superconducting state of the two- and the three-dimensional composites. (author)

Seleção em gradiente de Percoll® sobre os parâmetros espermáticos do sêmen bovino congelado Selection bovine frozen semen in Percoll® gradient on spermatic parameters

Directory of Open Access Journals (Sweden)

Charles Kiefer

2008-06-01

Full Text Available Na produção in vitro de embriões, técnicas de seleção espermática são usadas, dentre elas, o gradiente descontínuo de Percoll®. O objetivo foi avaliar a integridade da membrana plasmática (eosina-nigrosina, do acrossomo (trypan blue- Giemsa – TBG, lecitina do amendoim conjugada ao isotiocianato de fluoresceína associado ao iodeto de propídeo - Fitc-PNA/PI e da cromatina (azul de toluidina, em espermatozóide bovino congelado. Vinte e nove amostras foram analisadas nos momentos pós-descongelação (PD e pós-Percoll® (PP. As variáveis expressas em porcentagem foram submetidas à análise de variância e foi empregado o teste de Tuckey para a comparação entre médias. O estudo da associação entre variáveis foi feito pelo teste de correlação de Pearson. Constataram-se, entre os momentos PD e PP, diferenças significativas (p<0,05 para a motilidade, integridade de membrana plasmática e número de espermatozóides vivos com acrossomo íntegro (TBG e Fitc-PNA/PI, com maiores valores obtidos PP. O percentual de células com alteração na condensação da cromatina não diferiu entre os momentos estudados. Conclui-se que o gradiente descontínuo de Percoll® foi eficaz na seleção de uma maior população de células móveis, com membranas plasmática e acrossomal íntegras, sem haver alteração na condensação da cromatina nuclear.At in vitro embryo production sperm selection techniques are used, one of them is Percoll® density-gradient. The aim with this study was to evaluate the plasmatic membrane (eosin-nigrosin, acrosomal (trypan blue-Giemsa; fluorescein isothiocyanate conjugated peanut agglutinin lecitin/propidium iodide (FITC-PNA/PI and chromatin (toluidine blue integrity, in frozen bovine spermatozoa. Twenty nine samples were analysed at post-thaw (PD and post-Percoll® moments. Variable expressed in percentage were submitted to ANOVA and used Tuckey’s test for mean comparison. The association between variables

Derivation of Einstein-Cartan theory from general relativity

Science.gov (United States)

Petti, Richard

2015-04-01

General relativity cannot describe exchange of classical intrinsic angular momentum and orbital angular momentum. Einstein-Cartan theory fixes this problem in the least invasive way. In the late 20th century, the consensus view was that Einstein-Cartan theory requires inclusion of torsion without adequate justification, it has no empirical support (though it doesn't conflict with any known evidence), it solves no important problem, and it complicates gravitational theory with no compensating benefit. In 1986 the author published a derivation of Einstein-Cartan theory from general relativity, with no additional assumptions or parameters. Starting without torsion, Poincaré symmetry, classical or quantum spin, or spinors, it derives torsion and its relation to spin from a continuum limit of general relativistic solutions. The present work makes the case that this computation, combined with supporting arguments, constitutes a derivation of Einstein-Cartan theory from general relativity, not just a plausibility argument. This paper adds more and simpler explanations, more computational details, correction of a factor of 2, discussion of limitations of the derivation, and discussion of some areas of gravitational research where Einstein-Cartan theory is relevant.

Ac hopping conduction at extreme disorder takes place on the percolating cluster

DEFF Research Database (Denmark)

Schrøder, Thomas; Dyre, J. C.

2008-01-01

Simulations of the random barrier model show that ac currents at extreme disorder are carried almost entirely by the percolating cluster slightly above threshold; thus contributions from isolated low activation-energy clusters are negligible. The effective medium approximation in conjunction...

Accelerating Gas Adsorption on 3D Percolating Carbon Nanotubes.

Science.gov (United States)

Li, Hui; Wen, Chenyu; Zhang, Youwei; Wu, Dongping; Zhang, Shi-Li; Qiu, Zhi-Jun

2016-02-18

In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an SWCNT network in the transistor channel, which in turn results in a 7-fold shorter time constant of adsorption with the composite. The description of gas adsorption developed in the present work is generic for all semiconductors and the demonstrated composite with 3D percolating SWCNTs dispersed in functional polymer represents a promising new type of material for advanced gas sensors.

Relativity the special and the general theory

CERN Document Server

Einstein, Albert

2015-01-01

After completing the final version of his general theory of relativity in November 1915, Albert Einstein wrote a book about relativity for a popular audience. His intention was "to give an exact insight into the theory of relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics." The book remains one of the most lucid explanations of the special and general theories ever written. In the early 1920s alone, it was translated into ten languages, and fifteen editions in the original German appeared over the course of Einstein's lifetime. This new edition of Einstein's celebrated book features an authoritative English translation of the text along with an introduction and a reading companion by Hanoch Gutfreund and Jürgen Renn that examines the evolution of Einstein's thinking and casts his ideas in a broader present-day context. A special chapter explores the history...

New relations for gauge-theory amplitudes

International Nuclear Information System (INIS)

Bern, Z.; Carrasco, J. J. M.; Johansson, H.

2008-01-01

We present an identity satisfied by the kinematic factors of diagrams describing the tree amplitudes of massless gauge theories. This identity is a kinematic analog of the Jacobi identity for color factors. Using this we find new relations between color-ordered partial amplitudes. We discuss applications to multiloop calculations via the unitarity method. In particular, we illustrate the relations between different contributions to a two-loop four-point QCD amplitude. We also use this identity to reorganize gravity tree amplitudes diagram by diagram, offering new insight into the structure of the Kawai-Lewellen-Tye (KLT) relations between gauge and gravity tree amplitudes. This insight leads to similar but novel relations. We expect this to be helpful in higher-loop studies of the ultraviolet properties of gravity theories.

Commercial test on uranium ore percolation leaching in Fuzhou uranium mine

International Nuclear Information System (INIS)

Cai Chunhui

2002-01-01

Commercial test on uranium ore percolation leaching was carried out according to ore characteristics of Fuzhou Uranium Mine and results from small test. Technological and economic indexes, such as leaching rate, acid consumption, leaching cycle, etc. are discussed. The general idea applying the test results to commercial production is presented, too

Effect of percolation rate on water-travel time in deep, partially saturated zones

International Nuclear Information System (INIS)

Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

1986-02-01

The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye county, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. The rock units at Yucca Mountain can be grouped into three types: (1) vitric tuffs with high matrix conductivity and few fractures; (2) zeolitized tuffs with low matrix conductivity and few fractures; and (3) densely welded tuffs with low matrix conductivities and many fractures. The prospective repository zone is in densely welded tuff; the units between it and the water table are of types 1 and 2. Current percolation rates through Yucca Mountain, and those that are currently postulated under future climatic conditions, are thought to be of the order of the saturated matrix conductivity of some of the units. Although it is probable that there is now little or no water movement in fracture, it is necessary to investigate the potential for fracture flow, especially that which could be initiated under future climatic conditions. Significant fracture flow, if present, could reduce the water travel time between the repository and the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table is on the order of hundreds of thousands of years. this result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 many initiate water movement in the fractures, reducing the travel time significantly

Granular model, percolation-resistivity, ESR and elastic modulus of carbonaceous materials application to the babassu endocarp heat treated up to 22000C

International Nuclear Information System (INIS)

Emmerich, F.G.

1987-01-01

A microscopic model (granular model) is presented to study heat treated carbons. A granular structure is defined in the carbon matrix, composed of turbostratic graphite-like microcrystallites, cross-linkings and micropores. A general expression is developed to calculate the volume fraction X of the conducting phase of the granular structure as a function of structural parameters obtained from X-ray diffraction small angle X-ray scattering. The granular model and the percolation theory are used to explain the electrical resistivity behaviour with the heat treatment temperature (HTT), where X is the fundamental parameter. An electron spin resonance (ESR) study of the low and high HTT ranges is presented, including the transition range (700-1300 0 C). The elucitation of the spin center nature in this range and the liking with the two adjacent ranges has been pursued. An expression to calculate the elastic modulus (Young's modulus), based on the microscopic granular model with the fundamental participation of the cross-linkings, is derived to account for the behavior of the modulus with the HTT. The granular model with the expression of X, the percolation-resistivity theory, the ESR study, and the expression of the elastic modulus are applied to the babassu endocarp carbon heat treated up to 2200 0 C. This material can be classified as a tipical non-graphitic carbon, being useful to search the validity of the model and the proposed expressions. It is observed that the theoretical expressions describe with reasonable accuracy the respective experimental behaviours. The measurements of physical and chemical parameters of the babassu endocarp treated up to 2200 0 C area also included. (author) [pt

Idiotypic networks incorporating T-B cell co-operation. The conditions for percolation

NARCIS (Netherlands)

Boer, R.J. de; Hogeweg, P.

1989-01-01

Previous work was concerned with symmetric immune networks of idiotypic interactions amongst B cell clones. The behaviour of these networks was contrary to expectations. This was caused by an extensive percolation of idiotypic signals. Idiotypic activation was thus expected to affect almost all

Polymer collapse, protein folding, and the percolation threshold.

Science.gov (United States)

Meirovitch, Hagai

2002-01-15

We study the transition of polymers in the dilute regime from a swollen shape at high temperatures to their low-temperature structures. The polymers are modeled by a single self-avoiding walk (SAW) on a lattice for which l of the monomers (the H monomers) are self-attracting, i.e., if two nonbonded H monomers become nearest neighbors on the lattice they gain energy of interaction (epsilon = -/epsilon/); the second type of monomers, denoted P, are neutral. This HP model was suggested by Lau and Dill (Macromolecules 1989, 22, 3986-3997) to study protein folding, where H and P are the hydrophobic and polar amino acid residues, respectively. The model is simulated on the square and simple cubic (SC) lattices using the scanning method. We show that the ground state and the sharpness of the transition depend on the lattice, the fraction g of the H monomers, as well as on their arrangement along the chain. In particular, if the H monomers are distributed at random and g is larger than the site percolation threshold of the lattice, a collapsed transition is very likely to occur. This conclusion, drawn for the lattice models, is also applicable to proteins where an effective lattice with coordination number between that of the SC lattice and the body centered cubic lattice is defined. Thus, the average fraction of hydrophobic amino acid residues in globular proteins is found to be close to the percolation threshold of the effective lattice.

Spring School on Superstring Theory and Related Topics

CERN Document Server

2017-01-01

ICTP's annual Spring School on Superstring Theory and Related Topics provides pedagogical treatment of these subjects through lectures by some of the world's top string theorists. The activity is intended for theoretical physicists or mathematicians with knowledge of quantum field theory, general relativity and string theory. It is organized in collaboration with the Asia Pacific Center for Theoretical Physics (APCTP) and the Italian Institute for Nuclear Physics (INFN).

A Percolation Perspective for Gutenburg-Richter Scaling and b-values for Fracking Assocated Seismicity

Science.gov (United States)

Norris, J. Q.

2016-12-01

Published 60 years ago, the Gutenburg-Richter law provides a universal frequency-magnitude distribution for natural and induced seismicity. The GR law is a two parameter power-law with the b-value specifying the relative frequency of small and large events. For large catalogs of natural seismicity, the observed b-values are near one, while fracking associated seismicity has observed b-values near two, indicating relatively fewer large events. We have developed a computationally inexpensive percolation model for fracking that allows us to generate large catalogs of fracking associated seismicity. Using these catalogs, we show that different power-law fitting procedures produce different b-values for the same data set. This shows that care must be taken when determining and comparing b-values for fracking associated seismicity.

Critical percolation in the slow cooling of the bi-dimensional ferromagnetic Ising model

Science.gov (United States)

Ricateau, Hugo; Cugliandolo, Leticia F.; Picco, Marco

2018-01-01

We study, with numerical methods, the fractal properties of the domain walls found in slow quenches of the kinetic Ising model to its critical temperature. We show that the equilibrium interfaces in the disordered phase have critical percolation fractal dimension over a wide range of length scales. We confirm that the system falls out of equilibrium at a temperature that depends on the cooling rate as predicted by the Kibble-Zurek argument and we prove that the dynamic growing length once the cooling reaches the critical point satisfies the same scaling. We determine the dynamic scaling properties of the interface winding angle variance and we show that the crossover between critical Ising and critical percolation properties is determined by the growing length reached when the system fell out of equilibrium.

Maxwell's electromagnetic theory and special relativity.

Science.gov (United States)

Hall, Graham

2008-05-28

This paper presents a brief history of electromagnetic theory from ancient times up to the work of Maxwell and the advent of Einstein's special theory of relativity. It is divided into five convenient periods and the intention is to describe these developments for the benefit of a lay scientific audience and with the minimum of technical detail.

Symmetry, Contingency, Complexity: Accommodating Uncertainty in Public Relations Theory.

Science.gov (United States)

Murphy, Priscilla

2000-01-01

Explores the potential of complexity theory as a unifying theory in public relations, where scholars have recently raised problems involving flux, uncertainty, adaptiveness, and loss of control. Describes specific complexity-based methodologies and their potential for public relations studies. Offers an account of complexity theory, its…

An Untrodden Path: Versatile Fabrication of Self-Supporting Polymer-Stabilized Percolation Membranes (PSPMs) for Gas Separation.

Science.gov (United States)

Friebe, Sebastian; Mundstock, Alexander; Schneider, Daniel; Caro, Jürgen

2017-05-11

The preparation and scalability of zeolite or metal organic framework (MOF) membranes remains a major challenge, and thus prevents the application of these materials in large-scale gas separation. Additionally, several zeolite or MOF materials are quite difficult or nearly impossible to grow as defect-free layers, and require expensive macroporous ceramic or polymer supports. Here, we present new self-supporting zeolite and MOF composite membranes, called Polymer-Stabilized Percolation Membranes (PSPMs), consisting of a pressed gas selective percolation network (in our case ZIF-8, NaX and MIL-140) and a gas-impermeable infiltrated epoxy resin for cohesion. We demonstrate the performance of these PSPMs by separating binary mixtures of H 2 /CO 2 and H 2 /CH 4 . We report the brickwork-like architecture featuring selective percolation pathways and the polymer as a stabilizer, compare the mechanical stability of said membranes with competing materials, and give an outlook on how economic these membranes may become. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Relativity. The theory and its philosophy

International Nuclear Information System (INIS)

Angel, R.B.

1980-01-01

An attempt is made to provide a completely self-contained treatment of the philosophical foundations of the theory of relativity. The chapter headings are: mathematical preliminaries; relativity and Newtonian mechanics; the principle of special relativity; empiricism, rationalism and special relativity; special relativity and conventionalism; the commensurability of classical and relativistic mechanics; more mathematics; the path to general relativity; an outline of general relativity; relativity and covariance; spacetime and geometry. (U.K.)

Percolation Line, Response Functions, and Voronoi Polyhedra Analysis in Supercritical Water

Czech Academy of Sciences Publication Activity Database

Škvor, J.; Nezbeda, Ivo

2012-01-01

Roč. 15, č. 2 (2012), s. 23301 ISSN 1607-324X R&D Projects: GA AV ČR IAA200760905 Grant - others:GA UJEP(CZ) 53223–15–0010–01 Institutional support: RVO:67985858 Keywords : percolation line * response functions * widom lines Subject RIV: BJ - Thermodynamics Impact factor: 0.757, year: 2012

Possible violations of the relativity theory

International Nuclear Information System (INIS)

Tiomno, J.

1985-01-01

A review of previous works of the author and collaborators on possible violations of the Theory of Relativity (SR) is made. It is shown that there is no contradiction of the predictions of the Lorentz Aether Theory, in the form presented in these papers, with existing experiments. Further experiments to detect these violations (or to confirm SR) are indicated. (Author) [pt

PRETREATMENT AND FRACTIONATION OF CORN STOVER BY AMMONIA RECYCLE PERCOLATION PROCESS. (R831645)

Science.gov (United States)

Corn stover was pretreated with aqueous ammonia in a flow-through column reactor,a process termed as Ammonia Recycle Percolation (ARP). The aqueous ammonia causesswelling and efficient delignification of biomass at high temperatures. The ARPprocess solubilizes abou...

Perturbative Gravity and Gauge Theory Relations: A Review

Directory of Open Access Journals (Sweden)

Thomas Søndergaard

2012-01-01

Full Text Available This paper is dedicated to the amazing Kawai-Lewellen-Tye relations, connecting perturbative gravity and gauge theories at tree level. The main focus is on n-point derivations and general properties both from a string theory and pure field theory point of view. In particular, the field theory part is based on some very recent developments.

Development of Einstein's general theory of relativity

International Nuclear Information System (INIS)

Datta, B.K.

1980-01-01

Starting from Poincare's Lorentz-invariant theory of gravity formulated in 1906, development of Einstein's general theory of relativity during 1906-1916 is discussed. Three stages in this development are recognised. In the first stage during 1907-1914, Einstein tried to extend the relativity principle of uniform motion to the frames in non-uniform motion. For this purpose, he introduced the principle of equivalence which made it possible to calculate the effect of homogeneous gravitational field on arbitrary physical processes. During the second stage comprising years 1912-1914 overlapping the first stage, Einstein and Grossmann were struggling to translate physical postulates into the language of the absolute differential calculus. In the period 1915-1916, Einstein formulated the field equations of general relativity. While discussing these developmental stages, theories of gravitation formulated by Abraham, Nordstroem and Mie are also discussed. (M.G.B.)

Effect of electrostatic Interactions on the Percolation Concentration of Fibrillar ß-Lactoglobuline Gels

NARCIS (Netherlands)

Veerman, C.; Ruis, H.G.M.; Sagis, L.M.C.; Linden, van der E.

2002-01-01

The effect of electrostatic interactions on the critical percolation concentration (cp) of fibrillar -lactoglobulin gels at pH 2 was investigated using rheological measurements, transmission electron microscopy (TEM), and performing conversion experiments. A decreasing cp with increasing ionic

Influence of geometry on light harvesting in dendrimeric systems. II. nth-nearest neighbor effects and the onset of percolation

International Nuclear Information System (INIS)

Bentz, Jonathan L.; Kozak, John J.

2006-01-01

We explore the effect of imposing different constraints (biases, boundary conditions) on the mean time to trapping (or mean walklength) for a particle (excitation) migrating on a finite dendrimer lattice with a centrally positioned trap. By mobilizing the theory of finite Markov processes, we are able to obtain exact analytic expressions for site-specific walklengths as well as the overall walklength for both nearest-neighbor and second-nearest-neighbor displacements. This allows the comparison with and generalization of earlier results [A. Bar-Haim, J. Klafter, J. Phys. Chem. B 102 (1998) 1662; A. Bar-Haim, J. Klafter, J. Lumin. 76, 77 (1998) 197; O. Flomenbom, R.J. Amir, D. Shabat, J. Klafter, J. Lumin. 111 (2005) 315; J.L. Bentz, F.N. Hosseini, J.J. Kozak, Chem. Phys. Lett. 370 (2003) 319]. A novel feature of this work is the establishment of a connection between the random walk models studied here and percolation theory. The full dynamical behavior was also determined via solution of the stochastic master equation, and the results obtained compared with recent spectroscopic experiments

Influence of geometry on light harvesting in dendrimeric systems. II. nth-nearest neighbor effects and the onset of percolation

Energy Technology Data Exchange (ETDEWEB)

Bentz, Jonathan L. [Department of Chemistry, Iowa State University, Ames, IA, 50011 (United States)]. E-mail: jnbntz@iastate.edu; Kozak, John J. [Beckman Institute, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125-7400 (United States)

2006-11-15

We explore the effect of imposing different constraints (biases, boundary conditions) on the mean time to trapping (or mean walklength) for a particle (excitation) migrating on a finite dendrimer lattice with a centrally positioned trap. By mobilizing the theory of finite Markov processes, we are able to obtain exact analytic expressions for site-specific walklengths as well as the overall walklength for both nearest-neighbor and second-nearest-neighbor displacements. This allows the comparison with and generalization of earlier results [A. Bar-Haim, J. Klafter, J. Phys. Chem. B 102 (1998) 1662; A. Bar-Haim, J. Klafter, J. Lumin. 76, 77 (1998) 197; O. Flomenbom, R.J. Amir, D. Shabat, J. Klafter, J. Lumin. 111 (2005) 315; J.L. Bentz, F.N. Hosseini, J.J. Kozak, Chem. Phys. Lett. 370 (2003) 319]. A novel feature of this work is the establishment of a connection between the random walk models studied here and percolation theory. The full dynamical behavior was also determined via solution of the stochastic master equation, and the results obtained compared with recent spectroscopic experiments.

Order parameter fluctuations at a critical point - an exact result about percolation -

International Nuclear Information System (INIS)

Botet, Robert

2011-01-01

The order parameter of the system in the critical state, is expected to undergo large non-Gaussian fluctuations. However, almost nothing is known about the mathematical forms of the possible probability distributions of the order parameter. A remarkable exception is the site-percolation on the Bethe lattice, for which the complete order-parameter distribution has been recently derived at the critical point. Surprisingly, it appears to be the Kolmogorov-Smirnov distribution, well known in very different areas of mathematical statistics. In the present paper, we explain first how this special distribution could appear naturally in the context of the critical systems, under the assumption (still virtually unstudied) of the exponential distribution of the number of domains of a given size. In a second part, we present for the first time the complete derivation of the order-parameter distribution for the critical percolation model on the Bethe lattice, thus completing a recent publication announcing this result.

Indecomposability parameters in chiral logarithmic conformal field theory

International Nuclear Information System (INIS)

Vasseur, Romain; Jacobsen, Jesper Lykke; Saleur, Hubert

2011-01-01

Work of the last few years has shown that the key algebraic features of Logarithmic Conformal Field Theories (LCFTs) are already present in some finite lattice systems (such as the XXZ spin-1/2 chain) before the continuum limit is taken. This has provided a very convenient way to analyze the structure of indecomposable Virasoro modules and to obtain fusion rules for a variety of models such as (boundary) percolation etc. LCFTs allow for additional quantum numbers describing the fine structure of the indecomposable modules, and generalizing the 'b-number' introduced initially by Gurarie for the c=0 case. The determination of these indecomposability parameters (or logarithmic couplings) has given rise to a lot of algebraic work, but their physical meaning has remained somewhat elusive. In a recent paper, a way to measure b for boundary percolation and polymers was proposed. We generalize this work here by devising a general strategy to compute matrix elements of Virasoro generators from the numerical analysis of lattice models and their continuum limit. The method is applied to XXZ spin-1/2 and spin-1 chains with open (free) boundary conditions. They are related to gl(n+m|m) and osp(n+2m|2m)-invariant superspin chains and to non-linear sigma models with supercoset target spaces. These models can also be formulated in terms of dense and dilute loop gas. We check the method in many cases where the results were already known analytically. Furthermore, we also confront our findings with a construction generalizing Gurarie's, where logarithms emerge naturally in operator product expansions to compensate for apparently divergent terms. This argument actually allows us to compute indecomposability parameters in any logarithmic theory. A central result of our study is the construction of a Kac table for the indecomposability parameters of the logarithmic minimal models LM(1,p) and LM(p,p+1).

Link overlap, viability, and mutual percolation in multiplex networks

International Nuclear Information System (INIS)

Min, Byungjoon; Lee, Sangchul; Lee, Kyu-Min; Goh, K.-I.

2015-01-01

Many real-world complex systems are best modeled by multiplex networks. The multiplexity has proved to have broad impact on the system’s structure and function. Most theoretical studies on multiplex networks to date, however, have largely ignored the effect of the link overlap across layers despite strong empirical evidences for its significance. In this article, we investigate the effect of the link overlap in the viability of multiplex networks, both analytically and numerically. After a short recap of the original multiplex viability study, the distinctive role of overlapping links in viability and mutual connectivity is emphasized and exploited for setting up a proper analytic framework. A rich phase diagram for viability is obtained and greatly diversified patterns of hysteretic behavior in viability are observed in the presence of link overlap. Mutual percolation with link overlap is revisited as a limit of multiplex viability problem, and the controversy between existing results is clarified. The distinctive role of overlapping links is further demonstrated by the different responses of networks under random removals of overlapping and non-overlapping links, respectively, as well as under several link-removal strategies. Our results show that the link overlap facilitates the viability and mutual percolation; at the same time, the presence of link overlap poses a challenge in analytical approaches to the problem

Porous media: Analysis, reconstruction and percolation

DEFF Research Database (Denmark)

Rogon, Thomas Alexander

1995-01-01

functions of Gaussian fields and spatial autocorrelation functions of binary fields. An enhanced approach which embodies semi-analytical solutions for the conversions has been made. The scope and limitations of the method have been analysed in terms of realizability of different model correlation functions...... stereological methods. The measured sample autocorrelations are modeled by analytical correlation functions. A method for simulating porous networks from their porosity and spatial correlation originally developed by Joshi (14) is presented. This method is based on a conversion between spatial autocorrelation...... in binary fields. Percolation threshold of reconstructed porous media has been determined for different discretizations of a selected model correlation function. Also critical exponents such as the correlation length exponent v, the strength of the infinite network and the mean size of finite clusters have...

On the relation of the theoretical foundations of quantum theory and general relativity theory; Ueber die Beziehung der begrifflichen Grundlagen der Quantentheorie und der Allgemeinen Relativitaetstheorie

Energy Technology Data Exchange (ETDEWEB)

Kober, Martin

2010-07-01

The specific content of the present thesis is presented in the following way. First the most important contents of quantum theory and general relativity theory are presented. In connection with the general relativity theory the mathematical property of the diffeomorphism invariance plays the deciding role, while concerning the quantum theory starting from the Copenhagen interpretation first the measurement problem is treated, before basing on the analysis of concrete phenomena and the mathematical apparatus of quantum theory the nonlocality is brought into focus as an important property. This means that both theories suggest a relationalistic view of the nature of the space. This analysis of the theoretical foundations of quantum theory and general relativity theory in relation to the nature of the space obtains only under inclusion of Kant's philosophy and his analysis of the terms space and time as fundamental forms of perception its full persuasive power. Then von Weizsaeckers quantum theory of the ur-alternatives is presented. Finally attempts are made to apply the obtained knowledge to the question of the quantum-theoretical formulation of general relativity theory.

FORMATION OF CALCITE AND SILICA FROM PERCOLATION IN A HYDROLOGICALLY UNSATURATED SETTING, YUCCA MOUNTAIN, NEVADA

International Nuclear Information System (INIS)

Paces, J.B.; Whelan, J.F.; Peterman, Z.E.; Marshall, B.D.

2000-01-01

Geological, mineralogical, chemical, and isotopic evidence from coatings of calcite and silica on open fractures and lithophysal cavities within welded tuffs at Yucca Mountain indicate an origin from meteoric water percolating through a thick (500 to 700 m) unsaturated zone (UZ) rather than from pulses of ascending ground water. Geologic evidence for a UZ setting includes the presence of coatings in only a small percentage of cavities, the restriction of coatings to fracture footwalls and cavity floors, and an absence of mineral high-water marks indicative of water ponding. Systematic mineral sequences (early calcite, followed by chalcedony with minor quartz and fluorite, and finally calcite with intercalated opal forming the bulk of the coatings) indicate progressive changes in UZ conditions through time, rather than repeated saturation by flooding. Percolation under the influence of gravity also results in mineral textures that vary between steeply dipping sites (thinner coatings of blocky calcite) and shallowly dipping sites (thicker coatings of coarse, commonly bladed calcite, with globules and sheets of opal). Micrometer-scale growth banding in both calcite and opal reflects slow average growth rates (scale of mm/m.y.) over millions of years rather than only a few rapidly deposited growth episodes. Isotopic compositions of C, O, Sr, and U from calcite and opal indicate a percolation-modified meteoric water source, and collectively refute a deeper ground-water source. Chemical and isotopic variations in coatings also indicate long-term evolution of water compositions. Although some compositional changes are related to shifts in climate, growth rates in the deeper UZ are buffered from large changes in meteoric input. Coatings most likely formed from films of water flowing down connected fracture pathways. Mineral precipitation is consistent with water vapor and carbon dioxide loss from films at very slow rates. Data collectively indicate that mineral coatings

Charge transport in organic transistors accounting for a wide distribution of carrier energies, Part I : Theory

NARCIS (Netherlands)

Torricelli, F.

2012-01-01

An extended theory of carrier hopping transport in organic transistors is proposed. According to many experimental studies, the density of localized states in organic thin-film transistors can be described by a double-exponential function. In this work, using a percolation model of hopping, the

Reasonable fermionic quantum information theories require relativity

International Nuclear Information System (INIS)

Friis, Nicolai

2016-01-01

We show that any quantum information theory based on anticommuting operators must be supplemented by a superselection rule deeply rooted in relativity to establish a reasonable notion of entanglement. While quantum information may be encoded in the fermionic Fock space, the unrestricted theory has a peculiar feature: the marginals of bipartite pure states need not have identical entropies, which leads to an ambiguous definition of entanglement. We solve this problem, by proving that it is removed by relativity, i.e., by the parity superselection rule that arises from Lorentz invariance via the spin-statistics connection. Our results hence unveil a fundamental conceptual inseparability of quantum information and the causal structure of relativistic field theory. (paper)

Basic statements of relativity theory

Directory of Open Access Journals (Sweden)

Wolfgang Muschik

2010-04-01

Full Text Available Some basic statements of relativity theory, starting out with geometry and observers up to Einstein's field equations, are collected in a systematical order without any proof, to serve as a short survey of tools and results.

Logarithmic conformal field theory: beyond an introduction

International Nuclear Information System (INIS)

Creutzig, Thomas; Ridout, David

2013-01-01

This article aims to review a selection of central topics and examples in logarithmic conformal field theory. It begins with the remarkable observation of Cardy that the horizontal crossing probability of critical percolation may be computed analytically within the formalism of boundary conformal field theory. Cardy’s derivation relies on certain implicit assumptions which are shown to lead inexorably to indecomposable modules and logarithmic singularities in correlators. For this, a short introduction to the fusion algorithm of Nahm, Gaberdiel and Kausch is provided. While the percolation logarithmic conformal field theory is still not completely understood, there are several examples for which the formalism familiar from rational conformal field theory, including bulk partition functions, correlation functions, modular transformations, fusion rules and the Verlinde formula, has been successfully generalized. This is illustrated for three examples: the singlet model M(1,2), related to the triplet model W(1,2), symplectic fermions and the fermionic bc ghost system; the fractional level Wess–Zumino–Witten model based on sl-hat (2) at k=−(1/2), related to the bosonic βγ ghost system; and the Wess–Zumino–Witten model for the Lie supergroup GL(1∣1), related to SL(2∣1) at k=−(1/2) and 1, the Bershadsky–Polyakov algebra W 3 (2) and the Feigin–Semikhatov algebras W n (2) . These examples have been chosen because they represent the most accessible, and most useful, members of the three best-understood families of logarithmic conformal field theories. The logarithmic minimal models W(q,p), the fractional level Wess–Zumino–Witten models, and the Wess–Zumino–Witten models on Lie supergroups (excluding OSP(1∣2n)). In this review, the emphasis lies on the representation theory of the underlying chiral algebra and the modular data pertaining to the characters of the representations. Each of the archetypal logarithmic conformal field theories is

Theory and experiments in general relativity and other metric theories of gravity

International Nuclear Information System (INIS)

Ciufolini, I.

1984-01-01

In Chapter I, after an introduction to theories of gravity alternative to general relativity, metric theories, and the post-Newtonian parameterized (PNN) formalism, a new class of metric theories of gravity is defined. As a result the post-Newtonian approximation of the new theories is not described by the PPN formalism. In fact under the weak field and slow motion hypothesis, the post-Newtonian expression of the metric tensor contains an infinite set of new terms and correspondingly an infinite set of new PPN parameters. Chapter II, III, and IV are devoted to new experiments to test general relativity and other metric theories of gravity. In particular, in chapter IV, it is shown that two general relativistics effects, the Lense-Thirring and De Sitter-Fokker precessions of the nodal lines of an Earth artificial satellite are today detectable using high altitude laser ranged artificial satellites such as Lageos. The orbit of this satellite is known with unprecedented accuracy. The author then describes a method of measuring these relativistic precessions using Lageos together with another high altitude laser ranged similar satellite with appropriately chosen orbital parameters

Pure Relationality as a Sociological Theory of Communication

Directory of Open Access Journals (Sweden)

Sam Whimster

2018-01-01

Full Text Available In order to explain the success of populist politicians use of social media, we need to subtract the social from relationality and separate social relationships from network theory applications. A pure theory of relationality is suggested by Werner Heisenberg’s breakthrough in quantum mechanics. It is argued that sociology, to its detriment, has failed to incorporate a theory of communication, one adequate to the explosion of social media and the recent rise of populist politics, here instanced by Donald Trump. Realizing the underlying importance of communication technology in all social relationships, and treating these two aspects in a complementary fashion, is the purpose of this essay in sociological theory.

Between general relativity and quantum theory

International Nuclear Information System (INIS)

Rayski, J.

1982-01-01

Some possibilities of reconciling general relativity with quantum theory are discussed. The procedure of quantization is certainly not unique, but depends upon the choice of the coordinate conditions. Most versions of quantization predict the existence of gravitons, but it is also possible to formulate a quantum theory with a classical gravity whereby the expectation values of Tsub(μν) constitute the sources of the classical metric field. (author)

Percolation modelling for highly aligned polycrystalline superconducting tapes

Energy Technology Data Exchange (ETDEWEB)

Rutter, N A; Glowacki, B A; Evetts, J E [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); IRC in Superconductivity, Madingley Road, Cambridge CB3 0HE (United Kingdom)

2000-11-01

Surface and bulk texture measurements have been carried out on highly aligned NiFe tapes, suitable for use as coated conductor substrates. Data from small-area electron backscatter diffraction measurements are compared with those from bulk x-ray analysis in the development of a two-dimensional percolation model, and the two are shown to give very similar results. No evidence of grain-to-grain correlation is found. The model is then developed to assess how the properties of a superconducting layer grown epitaxially on buffered tapes will depend on parameters such as sample size, grain size and the extent of grain alignment. (author)

Inorganic arsenic removal in rice bran by percolating cooking water.

Science.gov (United States)

Signes-Pastor, Antonio J; Carey, Manus; Meharg, Andrew A

2017-11-01

Rice bran, a by-product of milling rice, is highly nutritious but contains very high levels of the non-threshold carcinogen inorganic arsenic (i-As), at concentrations around 1mg/kg. This i-As content needs to be reduced to make rice bran a useful food ingredient. Evaluated here is a novel approach to minimizing rice bran i-As content which is also suitable for its stabilization namely, cooking bran in percolating arsenic-free boiling water. Up to 96% of i-As removal was observed for a range of rice bran products, with i-As removal related to the volume of cooking water used. This process reduced the copper, potassium, and phosphorus content, but had little effect on other trace- and macro-nutrient elements in the rice bran. There was little change in organic composition, as assayed by NIR, except for a decrease in the soluble sugar and an increase, due to biomass loss, in dietary fiber. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mapping the frontier of theory in industrial relations

DEFF Research Database (Denmark)

Tapia, Maite; Ibsen, Christian Lyhne; Kochan, Thomas A.

2015-01-01

well industrial relations meta-theories, when combined with efforts to build middle-range theories, provide distinctive explanations and different predictions for the alternatives that have emerged to date to fill the void. We propose new directions for theory and research that expand the range...... of actors or institutions that shape employment relations and include social identities outside of the employment relationship as the basis for mobilizing collective actions and voice. Finally, we suggest using these theoretical arguments to test among alternatives as a means of revitalizing and reshaping...

Numerical analysis of a proposed percolation experiment at the Pena Blanca natural analog site

International Nuclear Information System (INIS)

Green, R.T.; Rice, G.

1995-01-01

A field-scale percolation test is proposed for the Pena Blanca natural analog site near Chihuahua, MX. To aid in design of the field test, the V-TOUGH two-phase flow simulator was applied to model percolation of water through 8 to 10 m of partially saturated fractured tuff. The rock was characterized as a composite medium using measured hydraulic properties for the rock matrix and estimated values for the fractures. Measured matrix permeability varied over four orders of magnitude and fracture apertures were estimated to range from 10 to 1,000 μm. Water arrival times were predicted to vary between one day to 10,000 yr. The utility of the composite model and other representations of flow through fractured porous media can be tested using results from the field scale infiltration test data

Charge percolation pathways in polymer blend photovoltaic diodes with sub-mesoscopic two-phase microstructures

Science.gov (United States)

Dou, Fei; Silva, Carlos; Zhang, Xinping

2013-05-01

We find that the external quantum efficiency of photovoltaic diodes based on finely mixed blends of poly-9,9’-dioctylfluorene-co-bis-N,N’-(4-butylphenyl)-bis-N,N’-phenyl-l,4-phenylenediamine (PFB) and poly-9,9’- dioctylfluorene-co-benzothiadiazole (F8BT) depends strongly on the blend ratio. The peak external quantum efficiency is optimum for a PFB:F8BT ratio of 3:1. The difference of peak efficiency for this composition and a 1:1 ratio is significantly higher than the reported yield of charge-transfer excitons. From a surface topography analysis, we believe that charge percolation plays a crucial role in photocurrent efficiency in PFB:F8BT diodes. Furthermore, we present a qualitative model for different charge percolation pathways in diodes of different blend ratios.

Scaling theory for the quasideterministic limit of continuous bifurcations.

Science.gov (United States)

Kessler, David A; Shnerb, Nadav M

2012-05-01

Deterministic rate equations are widely used in the study of stochastic, interacting particles systems. This approach assumes that the inherent noise, associated with the discreteness of the elementary constituents, may be neglected when the number of particles N is large. Accordingly, it fails close to the extinction transition, when the amplitude of stochastic fluctuations is comparable with the size of the population. Here we present a general scaling theory of the transition regime for spatially extended systems. We demonstrate this through a detailed study of two fundamental models for out-of-equilibrium phase transitions: the Susceptible-Infected-Susceptible (SIS) that belongs to the directed percolation equivalence class and the Susceptible-Infected-Recovered (SIR) model belonging to the dynamic percolation class. Implementing the Ginzburg criteria we show that the width of the fluctuation-dominated region scales like N^{-κ}, where N is the number of individuals per site and κ=2/(d_{u}-d), d_{u} is the upper critical dimension. Other exponents that control the approach to the deterministic limit are shown to be calculable once κ is known. The theory is extended to include the corrections to the front velocity above the transition. It is supported by the results of extensive numerical simulations for systems of various dimensionalities.

Description of vibrational properties of random alloy ZnTe1-xSex within the percolation model

International Nuclear Information System (INIS)

Souhabi, Jihane; Chafi, Allal; Kassem, Mohammed; Nassour, Ayoub; Gleize, Jerome; Postnikov, A.V.; Hugel, J.; Pages, Olivier

2009-01-01

We discuss the classification of the phonon type behavior of semiconductor alloys as apparent in the Raman and infrared spectra, i.e. in terms of types (i) 1-bond→1-mode and (ii) 2-bond→1-mode (both covered by the Modified Random Element Isodisplacement model, operating at the macroscopic scale), and also (iii) the modified 2-mode type (exceptional), in the framework of the recent 1-bond→2-mode percolation model based on a description of the alloy disorder at the mesoscopic scale. The leading systems of types (i) and (iii), i.e., InGaAs and InGaP, respectively, were earlier shown to obey the percolation model. The aim of this work is to investigate whether the percolation model further extends to the leading system of the last type (ii), i.e. ZnTeSe. With this end in view, we perform a careful re-examination of the Raman and infrared spectra of this alloy, as available in the literature. Special attention is awarded to the discussion and modeling of the puzzling multi-mode infrared reflectivity spectra. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Conduction in rectangular quasi-one-dimensional and two-dimensional random resistor networks away from the percolation threshold.

Science.gov (United States)

Kiefer, Thomas; Villanueva, Guillermo; Brugger, Jürgen

2009-08-01

In this study we investigate electrical conduction in finite rectangular random resistor networks in quasione and two dimensions far away from the percolation threshold p(c) by the use of a bond percolation model. Various topologies such as parallel linear chains in one dimension, as well as square and triangular lattices in two dimensions, are compared as a function of the geometrical aspect ratio. In particular we propose a linear approximation for conduction in two-dimensional systems far from p(c), which is useful for engineering purposes. We find that the same scaling function, which can be used for finite-size scaling of percolation thresholds, also applies to describe conduction away from p(c). This is in contrast to the quasi-one-dimensional case, which is highly nonlinear. The qualitative analysis of the range within which the linear approximation is legitimate is given. A brief link to real applications is made by taking into account a statistical distribution of the resistors in the network. Our results are of potential interest in fields such as nanostructured or composite materials and sensing applications.

Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

DEFF Research Database (Denmark)

Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

2010-01-01

We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...... of crystallization. Below the critical value, the diffusion extent decreases only slightly with the degree of crystallization. No cationic diffusion is observed in the fully crystalline materials. The critical value might be associated with a percolation transition from an interconnected to a disconnected glass...

On skein relations in class S theories

International Nuclear Information System (INIS)

Tachikawa, Yuji; Watanabe, Noriaki

2015-01-01

Loop operators of a class S theory arise from networks on the corresponding Riemann surface, and their operator product expansions are given in terms of the skein relations, that we describe in detail in the case of class S theories of type A. As two applications, we explicitly determine networks corresponding to dyonic loops of N=4SU(3) super Yang-Mills, and compute the superconformal index of a nontrivial network operator of the T 3 theory.

Prediction of the percolation threshold and electrical conductivity of self-assembled antimony-doped tin oxide nanoparticles into ordered structures in PMMA/ATO nanocomposites.

Science.gov (United States)

Jin, Youngho; Gerhardt, Rosario A

2014-12-24

Electrical percolation in nanocomposites consisting of poly(methyl methacrylate) (PMMA) and antimony tin oxide (ATO) nanoparticles was investigated experimentally using monosize and polydisperse polymer particles. The nanocomposites were fabricated by compression molding at 170 °C. The matrix PMMA was transformed into space filling polyhedra while the ATO nanoparticles distributed along the sharp edges of the matrix, forming a 3D interconnected network. The measured electrical resistivity showed that percolation was achieved in these materials at a very low ATO content of 0.99 wt % ATO when monosize PMMA was used, whereas 1.48 wt % ATO was needed to achieve percolation when the PMMA was polydispersed. A parametric finite element approach was chosen to model this unique microstructure-driven self-assembling percolation behavior. COMSOL Multiphysics was used to solve the effects of phase segregation between the matrix and the filler using a 2D simplified model in the frequency domain of the AC/DC module. It was found that the percolation threshold (pc) is affected by the size ratio between the matrix and the filler in a systematic way. Furthermore, simulations indicate that small deviations from perfect interconnection result mostly in changes in the electrical resistivity while the minimum DC resistivity achievable in any given composite is governed by the electrical conductivity of the filler, which must be accurately known in order to obtain an accurate prediction. The model is quite general and is able to predict percolation behavior in a number of other similarly processed segregated network nanocomposites.

Percolation-enhanced generation of terahertz pulses by optical rectification on ultrathin gold films

NARCIS (Netherlands)

Ramakrishnan, G.; Planken, P.C.M.

2011-01-01

Emission of pulses of electromagnetic radiation in the terahertz range is observed when ultrathin gold films on glass are illuminated with femtosecond near-IR laser pulses. A distinct maximum is observed in the emitted terahertz amplitude from films of average thickness just above the percolation

Simulation of Water Percolation in a FEBEX Bentonite Block using TOUGH2 Program

International Nuclear Information System (INIS)

Bru, A.

2001-01-01

We use Tough2 program to simulate the water percolation in a Febex bentonite Block. From obtained results, we conclude that mean field approximation does not describe this process because the heterogeneity of the medium it is not include in mathematical formalism. (Author) 17 refs

General relativity and gauge gravity theories of higher order

International Nuclear Information System (INIS)

Konopleva, N.P.

1998-01-01

It is a short review of today's gauge gravity theories and their relations with Einstein General Relativity. The conceptions of construction of the gauge gravity theories with higher derivatives are analyzed. GR is regarded as the gauge gravity theory corresponding to the choice of G ∞4 as the local gauge symmetry group and the symmetrical tensor of rank two g μν as the field variable. Using the mathematical technique, single for all fundamental interactions (namely variational formalism for infinite Lie groups), we can obtain Einstein's theory as the gauge theory without any changes. All other gauge approaches lead to non-Einstein theories of gravity. But above-mentioned mathematical technique permits us to construct the gauge gravity theory of higher order (for instance SO (3,1)-gravity) so that all vacuum solutions of Einstein equations are the solutions of the SO (3,1)-gravity theory. The structure of equations of SO(3,1)-gravity becomes analogous to Weeler-Misner geometrodynamics one

On the equivalence of vacuum equations of gauge quadratic theory of gravity and general relativity theory

International Nuclear Information System (INIS)

Zhitnikov, V.V.; Ponomarev, V.N.

1986-01-01

An attempt is made to compare the solution of field equations, corresponding to quadratic equations for the fields (g μν , Γ μν α ) in gauge gravitation theory (GGT) with general relativity theory solutions. Without restrictions for a concrete type of metrics only solutions of equations, for which torsion turns to zero, are considered. Equivalence of vacuum equations of gauge quadratic theory of gravity and general relativity theory is proved using the Newman-Penrose formalism

A general theory of quantum relativity

International Nuclear Information System (INIS)

Minic, Djordje; Tze, C.-H.

2004-01-01

The geometric form of standard quantum mechanics is compatible with the two postulates: (1) the laws of physics are invariant under the choice of experimental setup and (2) every quantum observation or event is intrinsically statistical. These postulates remain compatible within a background independent extension of quantum theory with a local intrinsic time implying the relativity of the concept of a quantum event. In this extension the space of quantum events becomes dynamical and only individual quantum events make sense observationally. At the core of such a general theory of quantum relativity is the three-way interplay between the symplectic form, the dynamical metric and non-integrable almost complex structure of the space of quantum events. Such a formulation provides a missing conceptual ingredient in the search for a background independent quantum theory of gravity and matter. The crucial new technical element in our scheme derives from a set of recent mathematical results on certain infinite-dimensional almost Kahler manifolds which replace the complex projective spaces of standard quantum mechanics

The relationship between structural evolution and electrical percolation of the initial stages of tungsten chemical vapor deposition on polycrystalline TiN

International Nuclear Information System (INIS)

Rozenblat, A.; Haimson, S.; Shacham-Diamand, Y.; Horvitz, D.

2012-01-01

This paper presents experimental results and a geometric model of the evolution of sheet resistance and surface morphology during the transition from nucleation to percolation of tungsten chemical vapor deposition over ultrathin polycrystalline titanium nitride (TiN). We observed two mechanisms of reduction in sheet resistance. At deposition temperatures higher than 310 deg. C, percolation effect is formed at ∼35% of surface coverage, θ, and characterized with a sharp drop in resistance. At temperature below 310 deg. C, a reduction in resistance occurs in two steps. The first step occurs when θ = 35% and the second step at θ = 85%. We suggest a geometric model in which the electrical percolation pass is modulated by the thickness threshold of the islands at the instant of collision.

Violations of Einstein's Relativity: Motivations, Theory, and Phenomenology

International Nuclear Information System (INIS)

Lehnert, Ralf

2011-01-01

One of the most difficult questions in present-day physics concerns a fundamental theory of space, time, and matter that incorporates a consistent quantum description of gravity. There are various theoretical approaches to such a quantum-gravity theory. Nevertheless, experimental progress is hampered in this research field because many models predict deviations from established physics that are suppressed by some power of the Planck scale, which currently appears to be immeasurably small. However, tests of relativity theory provide one promising avenue to overcome this phenomeno-logical obstacle: many models for underlying physics can accommodate a small breakdown of Lorentz symmetry, and numerous feasible Lorentz-symmetry tests have Planck reach. Such mild violations of Einstein's relativity have therefore become the focus of recent research efforts. This mini course provides a brief survey of the key ideas in this research field and is geared at both experimentalists and theorists. In particular, several theoretical mechanisms leading to deviations from relativity theory are presented; the standard theoretical framework for relativity violations at currently accessible energy scales (i.e., the SME) is reviewed, and various present and near-future experimental efforts within this field are discussed.

Associative-algebraic approach to logarithmic conformal field theories

International Nuclear Information System (INIS)

Read, N.; Saleur, Hubert

2007-01-01

We set up a strategy for studying large families of logarithmic conformal field theories by using the enlarged symmetries and non-semisimple associative algebras appearing in their lattice regularizations (as discussed in a companion paper [N. Read, H. Saleur, Enlarged symmetry algebras of spin chains, loop models, and S-matrices, cond-mat/0701259]). Here we work out in detail two examples of theories derived as the continuum limit of XXZ spin-1/2 chains, which are related to spin chains with supersymmetry algebras gl(n|n) and gl(n+1 vertical bar n), respectively, with open (or free) boundary conditions in all cases. These theories can also be viewed as vertex models, or as loop models. Their continuum limits are boundary conformal field theories (CFTs) with central charge c=-2 and c=0 respectively, and in the loop interpretation they describe dense polymers and the boundaries of critical percolation clusters, respectively. We also discuss the case of dilute (critical) polymers as another boundary CFT with c=0. Within the supersymmetric formulations, these boundary CFTs describe the fixed points of certain nonlinear sigma models that have a supercoset space as the target manifold, and of Landau-Ginzburg field theories. The submodule structures of indecomposable representations of the Virasoro algebra appearing in the boundary CFT, representing local fields, are derived from the lattice. A central result is the derivation of the fusion rules for these fields

Verifying the Theory of Relativity

Science.gov (United States)

Chandrasekhar, S.

1975-01-01

This article, based on a talk the author gave to the 'Innominates', an interdisciplinary faculty group at the University of Chicago, focuses on events of the years surrounding the British Expeditions to Brazil and West Africa in 1919 that led to the confirmation of Einstein's theory of relativity. (BT)

Volatility Behaviors of Financial Time Series by Percolation System on Sierpinski Carpet Lattice

Science.gov (United States)

Pei, Anqi; Wang, Jun

2015-01-01

The financial time series is simulated and investigated by the percolation system on the Sierpinski carpet lattice, where percolation is usually employed to describe the behavior of connected clusters in a random graph, and the Sierpinski carpet lattice is a graph which corresponds the fractal — Sierpinski carpet. To study the fluctuation behavior of returns for the financial model and the Shanghai Composite Index, we establish a daily volatility measure — multifractal volatility (MFV) measure to obtain MFV series, which have long-range cross-correlations with squared daily return series. The autoregressive fractionally integrated moving average (ARFIMA) model is used to analyze the MFV series, which performs better when compared to other volatility series. By a comparative study of the multifractality and volatility analysis of the data, the simulation data of the proposed model exhibits very similar behaviors to those of the real stock index, which indicates somewhat rationality of the model to the market application.

Topics in the Foundations of General Relativity and Newtonian Gravitation Theory

CERN Document Server

Malament, David B

2012-01-01

In Topics in the Foundations of General Relativity and Newtonian Gravitation Theory, David B. Malament presents the basic logical-mathematical structure of general relativity and considers a number of special topics concerning the foundations of general relativity and its relation to Newtonian gravitation theory. These special topics include the geometrized formulation of Newtonian theory (also known as Newton-Cartan theory), the concept of rotation in general relativity, and Gödel spacetime. One of the highlights of the book is a no-go theorem that can be understood to show that there is

Trapping, percolation, and anomalous diffusion of particles in a two-dimensional random field

International Nuclear Information System (INIS)

Avellaneda, M.; Apelian, C.; Elliott, F. Jr.

1993-01-01

The authors analyze the advection of particles in a velocity field with Hamiltonian H(x,y) = bar V 1 y-bar V 2 x + W 1 (y) - W 2 (x), where W i , i=1,2, are random functions with stationary, independent increments. In the absence of molecular diffusion, the particle dynamics are sensitive to the streamline topology, which depends on the mean-to-fluctuations ratio p=max(|bar V 1 |/bar U;|bar V 2 |/bar U), with bar U = [|W' 1 | 2 ] 1/2 = rms fluctuations. The model is exactly solvable for p≥1 and well suited for Monte Carlo simulations for all p. Statistics are considered of streamlines for p=0, deriving power laws for the escape probability and the length of escaping trajectories for a box of size L much-gt 1. Also obtained is a characterization of the statistical topography of the Hamiltonian. The large-scale transport is studied of advected particles with p > 0. For 0 -v/2 [x(t) - (x(t))] and t -v/2 [y(t) - (y(t))]. The large-scale motions are Fickian (v=1) or superdiffusive (v=3/2) with a non-Gaussian coarse-grained probability, according to the direction of the mean velocity relative to the underlying lattice. These results are obtained analytically for p≥1 and extended to the regime 0 1 , bar V 2 ) for which stagnation regions in the flow exist. The results are compared with existing predictions on the topology of streamlines based on percolation theory and with mean-field calculations of effective diffusivities. 29 refs., 15 figs., 7 tabs

Novel scaling of the multiplicity distributions in the sequential fragmentation process and in the percolation

International Nuclear Information System (INIS)

Botet, R.

1996-01-01

A novel scaling of the multiplicity distributions is found in the shattering phase of the sequential fragmentation process with inhibition. The same scaling law is shown to hold in the percolation process. (author)

Evolution of excitonic states in two-phase systems with quantum dots of II-VI semiconductors near the percolation threshold

Science.gov (United States)

Bondar, N. V.; Brodyn, M. S.

2010-03-01

In two-phase disordered media composed of borosilicate glass with ZnSe or CdS quantum dots, the formation of a phase percolation transition of carriers for near-threshold concentrations that are manifested in optical spectra has been observed. Microscopic fluctuations of the quantum-dot density near the percolation threshold were found that resembled the phenomenon of critical opalescence, where similar fluctuations of the density of a pure substance appear near to a phase transition. It is proposed that the dielectric mismatch between a matrix and ZnSe or CdS quantum dots plays a significant role in the carrier (exciton) delocalization, resulting in the appearance of a “dielectric Coulomb trap” beyond the QD border and the formation of surface states of excitons. The spatial overlapping of excitonic states at the critical density of quantum dots results in a tunneling of carriers and the formation of a phase percolation transition in such media.

Quantum effects from a purely geometrical relativity theory

International Nuclear Information System (INIS)

Ellis, Homer G

2005-01-01

A purely geometrical relativity theory results from a construction that produces from three-dimensional space a happy unification of Kaluza's five-dimensional theory and Weyl's conformal theory. The theory can provide geometrical explanations for the following observed phenomena, among others: (a) visibility lifetimes of elementary particles of lengths inversely proportional to their rest masses; (b) the equality of charge magnitude among all charged particles interacting at an event; (c) the propensity of electrons in atoms to be seen in discretely spaced orbits; and (d) 'quantum jumps' between those orbits. This suggests the possibility that the theory can provide a deterministic underpinning of quantum mechanics like that provided to thermodynamics by the molecular theory of gases

The relativity theory and the nature of time

International Nuclear Information System (INIS)

Selleri, F.

1997-01-01

In this paper and its continuation, old and recent ideas concerning the nature of time are reviewed by starting from March's refusal of Newton's absolute time. Modern experimental evidence shows that the slowing down of moving clocks is a real phenomenon, Such is also the so-called twin paradox owing its name to its evident incompatibility with the philosophy of relativism (which should not be confused with the theory of relativity). Lorentz reformulation of relativity theory started by postulating physical effects of the ether, but adopted Einstein's clock synchronization: more than anything else this stopped Lorentz from understanding the advantages of different synchronization procedures. One of the problems of the usual approach is the necessity of a superdeterministic universe, as stressed by Popper. Recent results obtained by the author show that a theory is possible, based on relative time but on absolute simultaneity, in which all the conceptual difficulties of relativity are avoided. (Author) 21 refs

The relativity theory and the nature of time

International Nuclear Information System (INIS)

Selleri, F.

1997-01-01

In this paper and its continuation, old and recent ideas concerning the nature of time are reviewed by starting from Mach's refusal of Newton's absolute time. Modern experimental evidence shows that the slowing down of moving clocks is a real phenomenon. Such is also the so-called twin paradox owing its name to its evident incompatibility with the philosophy of relativism (which should not be confused with the theory of relativity). Lorentz' reformulation of relativity theory started by postulating physical effects of the ether, but adopted Einstein's clock synchronization: more than anything else this stopped Lorentz from understanding the advantages of different synchronization procedures. One of the problems of the usual approach is the necessity of a super deterministic universe, as stressed by Popper. Recent results obtained by the author show that a theory is possible, based on relative time but on absolute simultaneity, in which all the conceptual difficulties of relativity are avoided. (Author) 21 refs

The Special Theory of Relativity

Indian Academy of Sciences (India)

cial theory of relativity were published in the journal. Annalen der Physik, and were titled 'On the electro- dynamics of ... Historical Background. In order to set Einstein's work in proper perspective, re- call that, in ... ideas of absolute space and time firmly entrenched, most physicists thought that this speed was correct only in.

Percolation versus microcanonical fragmentation - comparison of fragment size distribution: Where is the liquid-gas transition in nuclei?

International Nuclear Information System (INIS)

Jaqaman, H.R.; Birzeit Univ.; Papp, G.; Eoetvoes Lorand Tudomanyegyetem, Budapest; Gross, D.H.E.; Freie Univ. Berlin

1990-01-01

The distributions of fragments produced by microcanonical multifragmentation of hot nuclei are compared with the cluster distributions predicted by a bond percolation model on a finite lattice. The conditional moments of these distributions are used together with the correlations between the largest three fragments in each event. Whereas percolation and statistical nuclear fragmentation agree in many details as in the usual plots of the averaged moments of the fragment distributions which yield the critical exponents, they turn out to be essentially different when less averaged quantities or correlations are considered. The differences between the predictions of the two models are mainly due to the particularities of the nuclear problem, especially the effect of the long-range Coulomb force which favours the break-up of the highly excited nucleus into two large fragments (pseudo-fission) and, to a somewhat lesser extent, enhances the possibility for the cracking of the nucleus into more than two large fragments. The fission events are, however, clearly separated from a second branch of critical correlations which shows up clearly in both nuclear fragmentation and percolation. We think that this critical correlation branch is due to the liquid-gas phase transition in finite nuclei. (orig.)

Establishment of an isolation method of Nostoc commune cells free from extracellular polysaccharides (EPS using Percoll centrifugation

Directory of Open Access Journals (Sweden)

Makiko Kosugi

2012-11-01

Full Text Available The terrestrial cyanobacterium Nostoc commune Vaucher ex Bornet et Flahault occurs worldwide, including in Japan and Antarctica. N. commune has a large amount of extracellular polysaccharides (EPS that hold moisture and protect the cells and at the same time accumulate light-blocking substances which is believed to play an important part in adaptation to a severe environment. To evaluate the photoadaptation processes in N. commune and clarify the role(s of EPS under ambient environmental condition at Antarctica, separation of cells from EPS is necessary. High yield is a prerequisite for the use of only small amount of natural N. commune from Antarctica. For this purpose, we developed a separation method by improving the Percoll density gradient centrifugation method using an EPS-coated field-grown Nostoc population. We established the most suitable condition to separate naked cells from EPS at high yield retaining high photosynthetic activity. The method is composed of centrifugation of cell homogenated N. commune in 10% (v/v Percoll to separate cells efficiently from EPS followed by fractionating centrifugation to remove impurities using the gradient of Percoll (80% and 50%, v/v.

Assessing clogging development in infiltration-percolation systems for wastewater treatment by electrical resistivity and induced polarisation methods

Science.gov (United States)

Tapias, Josefina C.; Himi, Mahjoub; Lovera, Raúl; de la Rocha, Angelica; Foch, Montserrat; Salvadó, Humbert; Casas, Albert

2013-04-01

Infiltration-percolation is a low technology process used to treat primary and secondary effluents. It consists in the intermittent application of sewage on buried sand filters where the infiltrated water percolates through unsaturated porous medium. The advantages over conventional mechanical sanitation systems are: low energy requirements, operation and maintenance that may be conducted by unskilled staff, and low sludge production because their simplicity and low operation costs. Nevertheless, clogging is a major operational and maintenance issue associated with the use of infiltration-percolation systems for wastewater treatment, and can ultimately limit the lifetime of the system. The clogging development causes decrease of hydraulic conductivity, reduced oxygen supply and further leads to a rapid decrease of the treatment performance. For this reason it is essential to assess in advance the evolution of clogging process and detect potential failures in the system. The preliminary results of this research conducted at the Hostalets de Pierola wastewater treatment plant (near Barcelona, Spain) show that electrical resistivity and induced polarisation geophysical methods can be very useful for delineating the clogging expansion. Then, this non-destructive metodology can help take the preventive measures for enlarge the lifetime of the treatment system.

A theory of strong interactions ''from'' general relativity

International Nuclear Information System (INIS)

Caldirola, P.; Recami, E.

1979-01-01

In this paper a previous letter (where, among other things, a classical ''quark confinement'' was derived from general relativity plus dilatation-covariance), is completed by showing that the theory is compatible also with quarks ''asymptotic freedom''. Then -within a bi-scale theory of gravitational and strong interactions- a classical field theory is proposed for the (strong) interactions between hadrons. Various consequences are briefly analysed

Africa and the Principles and Theories of International Relations ...

African Journals Online (AJOL)

To what extent have the principles and theories of international relations (as formulated) accommodated the specific needs and circumstances of Africa? In other words, how can the circumstances and peculiarities of Africa be made to shape and influence the established principles and theories of international relations as ...

Ideal related K-theory with coefficients

DEFF Research Database (Denmark)

Eilers, Soren; Restorff, Gunnar; Ruiz, Efren

2017-01-01

In this paper, we define an invariant, which we believe should be the substitute for total K-theory in the case when there is one distinguished ideal. Moreover, some diagrams relating the new groups to the ordinary K-groups with coefficients are constructed. These diagrams will in most cases help...... to determine the new groups, and will in a companion paper be used to prove a universal multi-coefficient theorem for the one distinguished ideal case for a large class of algebras......In this paper, we define an invariant, which we believe should be the substitute for total K-theory in the case when there is one distinguished ideal. Moreover, some diagrams relating the new groups to the ordinary K-groups with coefficients are constructed. These diagrams will in most cases help...

How I Created the Theory of Relativity.

Science.gov (United States)

Ono, Yoshimasa A.

1982-01-01

This translation of a lecture given in Kyoto (Japan) on 14 December l922 sheds light on Einstein's path to the theory of relativity and offers insights into many other aspects of his work on relativity. (Author/JN)

The relationship between theory of mind and relational frame theory : convergence of perspective-taking measures

OpenAIRE

Hendriks, A.; Barnes-Holmes, Yvonne; McEnteggart, Ciara; de Mey, H.; Witteman, C.; Janssen, G.; Egger, J.

2016-01-01

Objective: Perspective-taking difficulties have been demonstrated in autism and schizophrenia spectrum disorders, among other clinical presentations, and are traditionally examined from a Theory of Mind (ToM) point of view. Relational Frame Theory (RFT) offers a behavioural and contextual interpretation of perspective-taking, proposing that this ability can be studied in more detail by examining specific perspective-taking relations. To implement relational perspective-taking measures in clin...

Levitation and percolation in quantum Hall systems with correlated disorder

OpenAIRE

Song, Hui; Maruyama, Isao; Hatsugai, Yasuhiro

2007-01-01

We investigate the integer quantum Hall system in a two dimensional lattice model with spatially correlated disorder by using the efficient method to calculate the Chern number proposed by Fukui et al. [J. Phys. Soc. Jpn. 74, 1674 (2005)]. Distribution of charge density indicates that the extended states at the center of each Landau band have percolating current paths, which are topologically equivalent to the edge states that exist in a system with boundaries. As increasing the strength of d...

Choice of sample size for high transport critical current density in a granular superconductor: percolation versus self-field effects

International Nuclear Information System (INIS)

Mulet, R.; Diaz, O.; Altshuler, E.

1997-01-01

The percolative character of the current paths and the self-field effects were considered to estimate optimal sample dimensions for the transport current of a granular superconductor by means of a Monte Carlo algorithm and critical-state model calculations. We showed that, under certain conditions, self-field effects are negligible and the J c dependence on sample dimensions is determined by the percolative character of the current. Optimal dimensions are demonstrated to be a function of the fraction of superconducting phase in the sample. (author)

Is there a delocalization transition in a two-dimensional model for quantum percolation

International Nuclear Information System (INIS)

Dasgupta, I.; Saha, T.; Mookerjee, A.; Chakrabarti, B.K.

1992-01-01

In this paper, the authors estimate the transmittance of the quantum percolation model of Eggarter and Kirkpatrick on the square lattice of various sizes using the vector recursion method. The authors note from finite size scaling that there is no delocalization transition for any degree of disorder in two dimensions

Boundary rules and breaking of self-organized criticality in 2D frozen percolation

NARCIS (Netherlands)

J. van den Berg (Rob); P. Nolin (Pierre)

2016-01-01

htmlabstractWe study frozen percolation on the (planar) triangular lattice, where connected components stop growing ("freeze") as soon as their "size" becomes at least N, for some parameter N ≥ 1. The size of a connected component can be measured in several natural ways, and we

Probability of conductive bond formation in a percolating network of nanowires with fusible tips

Science.gov (United States)

Rykaczewski, Konrad; Wang, Robert Y.

2018-03-01

Meeting the heat dissipation demands of microelectronic devices requires development of polymeric composites with high thermal conductivity. This property is drastically improved by percolation networks of metallic filler particles that have their particle-to-particle contact resistances reduced through thermal or electromagnetic fusing. However, composites with fused metallic fillers are electrically conductive, which prevents their application within the chip-board and the inter-chip gaps. Here, we propose that electrically insulating composites for these purposes can be achieved by the application of fusible metallic coatings to the tips of nanowires with thermally conductive but electrically insulating cores. We derive analytical models that relate the ratio of the coated and total nanowire lengths to the fraction of fused, and thus conductive, bonds within percolating networks of these structures. We consider two types of materials for these fusible coatings. First, we consider silver-like coatings, which form only conductive bonds when contacting the silver-like coating of another nanowire. Second, we consider liquid metal-like coatings, which form conductive bonds regardless of whether they contact a coated or an uncoated segment of another nanowire. These models were validated using Monte Carlo simulations, which also revealed that electrical short-circuiting is highly unlikely until most of the wire is coated. Furthermore, we demonstrate that switching the tip coating from silver- to liquid metal-like materials can double the fraction of conductive bonds. Consequently, this work provides motivation to develop scalable methods for fabrication of the hybrid liquid-coated nanowires, whose dispersion in a polymer matrix is predicted to yield highly thermally conductive but electrically insulating composites.

Generalization of the test theory of relativity to noninertial frames

International Nuclear Information System (INIS)

Abolghasem, G.H.; Khajehpour, M.R.H.; Mansouri, R.

1988-08-01

We present a generalized test theory of special relativity, using a noninertial frame. Within the framework of the special theory of relativity the transport- and Einstein-synchronizations are equivalent on a rigidly rotating disk. But in any theory with a preferred frame such an equivalence does not hold. The time difference resulting from the two synchronization procedures is a measurable quantity within the reach of existing clock systems on the earth. The final result contains a term which depends on the angular velocity of the rotating system, and hence measures an absolute effect. This term is of crucial importance in our test theory of the special relativity. (author). 13 refs

How to test the special theory of relativity on rotating earth

International Nuclear Information System (INIS)

Abolghasem, H.; Khadjehpoor, M.R.; Mansouri, R.

1988-02-01

In the framework of a one parameter test theory of special relativity, the difference between Transport- and Einstein synchronization on the rotating earth is calculated. For the special theory of relativity this difference vanishes. Therefore, experiments in which these synchronization procedures are compared, test the special theory of relativity. (author). 8 refs

Conceptual strategies and inter-theory relations: The case of nanoscale cracks

Science.gov (United States)

Bursten, Julia R.

2018-05-01

This paper introduces a new account of inter-theory relations in physics, which I call the conceptual strategies account. Using the example of a multiscale computer simulation model of nanoscale crack propagation in silicon, I illustrate this account and contrast it with existing reductive, emergent, and handshaking approaches. The conceptual strategies account develops the notion that relations among physical theories, and among their models, are constrained but not dictated by limitations from physics, mathematics, and computation, and that conceptual reasoning within those limits is required both to generate and to understand the relations between theories. Conceptual strategies result in a variety of types of relations between theories and models. These relations are themselves epistemic objects, like theories and models, and as such are an under-recognized part of the epistemic landscape of science.

Constructing a chinese international relations theory

DEFF Research Database (Denmark)

Kristensen, P.M.; Nielsen, R.T.

2013-01-01

Chinese scholars are debating whether, and how, to innovate a Chinese theory of International Relations (IR). This article examines the driving forces behind this theoretical debate. It challenges the commonsensical link between external events in the subject matter (i.r.) and theorizing (IR......), which suggests that the innovation of a Chinese IR theory is a natural product of China's geopolitical rise, its growing political ambitions, and discontent with Western hegemony. We propose instead a sociological approach to intellectual innovation which opens the black box of knowledge production...... attention from their peers-theorizing a Chinese IR theory being one important way of doing this. The external layer-which ranges from power politics to sociopolitical developments-affects this process indirectly by providing more research funds and autonomy to the more immediate institutional environment...

Relational Frame Theory and Industrial/Organizational Psychology

Science.gov (United States)

Stewart, Ian; Barnes-Holmes, Dermot; Barnes-Holmes, Yvonne; Bond, Frank W.; Hayes, Steven C.

2006-01-01

The current paper argues that a Relational Frame Theory account of complex human behavior including an analysis of relational frames, relational networks, rules and the concept of self can provide a potentially powerful new perspective on phenomena in the applied science of industrial/organizational (I/O) psychology. In this article, we first…

Victories and defeats in general relativity theory

International Nuclear Information System (INIS)

Moeller, C.

1977-01-01

Only within the last 20 years has it been possible to conduct far-reaching experimental tests of the validity of Einstein's General Relativity Theory. Experimental confirmation in some fields is embarrassed by considerable difficulties in applying the theory to cosmic systems, which indicate that such major systems lie at the limit of the theory's applicability. The lecture here reproduced discusses both the successes and the limitations of the theory, starting with its replacement of the absolute space-time theory of Newton and its historical replacement by the relativistic gravitational postulates of Einstein which, in spite of its more complicated postulates, nevertheless introduced a great simplicity and comprehensiveness into the overall conception of nature. This theoretical 'beauty', however, can only be trusted if vindicated experimentally, which has to a considerable extent proved to be the case. For weak fields Newtonian and Einsteinian concepts coincide, while for stronger fields, and velocities not far from that of light, Einstein's theory is superior, giving,for example, an excellent correspondence with the precession of the perehelion of Mercury. On a larger scale, however, the theory appears to lead to conclusions which would invalidate the very concepts of space and time, even within a finite time-interval. A more generalized theory seems to be required. (A.D.N.)

School and conference on probability theory

International Nuclear Information System (INIS)

Lawler, G.F.

2004-01-01

This volume includes expanded lecture notes from the School and Conference in Probability Theory held at ICTP in May, 2001. Probability theory is a very large area, too large for a single school and conference. The organizers, G. Lawler, C. Newman, and S. Varadhan chose to focus on a number of active research areas that have their roots in statistical physics. The pervasive theme in these lectures is trying to find the large time or large space behaviour of models defined on discrete lattices. Usually the definition of the model is relatively simple: either assigning a particular weight to each possible configuration (equilibrium statistical mechanics) or specifying the rules under which the system evolves (nonequilibrium statistical mechanics). Interacting particle systems is the area of probability that studies the evolution of particles (either finite or infinite in number) under random motions. The evolution of particles depends on the positions of the other particles; often one assumes that it depends only on the particles that are close to the particular particle. Thomas Liggett's lectures give an introduction to this very large area. Claudio Landim's follows up by discussing hydrodynamic limits of particle systems. The goal of this area is to describe the long time, large system size dynamics in terms of partial differential equations. The area of random media is concerned with the properties of materials or environments that are not homogeneous. Percolation theory studies one of the simplest stated models for impurities - taking a lattice and removing some of the vertices or bonds. Luiz Renato G. Fontes and Vladas Sidoravicius give a detailed introduction to this area. Random walk in random environment combines two sources of randomness - a particle performing stochastic motion in which the transition probabilities depend on position and have been chosen from some probability distribution. Alain-Sol Sznitman gives a survey of recent developments in this

Boundary rules and breaking of self-organized criticality in 2D frozen percolation

NARCIS (Netherlands)

J. van den Berg (Rob); P. Nolin (Pierre)

2017-01-01

htmlabstractWe study frozen percolation on the (planar) triangular lattice, where connected components stop growing (“freeze”) as soon as their “size” becomes at least N, for some parameter N ≥ 1. The size of a connected component can be measured in several natural ways, and we

Estimation of percolating water dynamics through the vadose zone of the Postojna cave on the basis of isotope composition

Directory of Open Access Journals (Sweden)

Janja Kogovšek

2007-12-01

Full Text Available Within the scope of monitoring water percolation through the 100-m thick vadose zone in the area of Postojnska jama continuous measurements of precipitation were carried out on the surface, and continuous measurements of water flowandphysicalandchemicalparametersof selected water trickles were performed under the surface. Occasional samples of percolating waters were taken for the analysis of water oxygen isotope composition. An exponential model of groundwater flowwaselaborated,bymeansofwhichtheretentiontime of water in individual trickles was estimated. Modelled retention times of groundwater range from 2.5 months to over one year.

A new interpretation of the special theory of relativity

International Nuclear Information System (INIS)

Buonomano, V.

1975-01-01

Assuming the 'Big Bang' theory as well as the usual axioms in the Special Theory of Relativity, the time dilations and length contractions are treated as real physical effects. This becomes possible by relating everything to the hypothetical frame, Ssub(a), at rest relative to the 'Big Bang' event. This frame in many senses plays the role of the classical aether frame. A clock's real rhythm, as opposed to its rhythm observed by restricted methods, is then a function of its velocity relative to Ssub(a) (assuming a uniform gravitational field). It is further assumed that gravitational radiation is composed of 'electromagnetic-like' waves. Therefore when a clock changes its velocity in a uniform gravitational field it must receive a a different total energy due to the average frequency shift (Doppler effect), the time dilations are then caused by the change in energy due to this frequency shift. That is, no two clocks can be in the 'same' gravitational field unless they have no relative velocity, and therefore the Special Theory of Relativity is a special case of the General Theory from this viewpoint. Two feasible experimental tests, using the Moessbauer effect, are described that would decide on these viewpoints. The principle of equivalence and the 'twin paradox' are also discussed. (author)

Diffusion in the special theory of relativity.

Science.gov (United States)

Herrmann, Joachim

2009-11-01

The Markovian diffusion theory is generalized within the framework of the special theory of relativity. Since the velocity space in relativity is a hyperboloid, the mathematical stochastic calculus on Riemanian manifolds can be applied but adopted here to the velocity space. A generalized Langevin equation in the fiber space of position, velocity, and orthonormal velocity frames is defined from which the generalized relativistic Kramers equation in the phase space in external force fields is derived. The obtained diffusion equation is invariant under Lorentz transformations and its stationary solution is given by the Jüttner distribution. Besides, a nonstationary analytical solution is derived for the example of force-free relativistic diffusion.

Microscale electrostatic fractional capacitors using reduced graphene oxide percolated polymer composites

KAUST Repository

Elshurafa, Amro M.

2013-06-14

We show that graphene-percolated polymer composites exhibit fractional capacitance response in the frequency range of 50 kHz–2 MHz. In addition, it is shown that by varying the loading of graphene within the matrix from 2.5% to 12%, the phase can be controllably tuned from −67° to −31°, respectively. The electrostatic fractional capacitors proposed herein are easy to fabricate and offer integration capability on electronic printed circuit boards.

Critical Race Theory and the Limits of Relational Theory in Social Work with Women.

Science.gov (United States)

Quinn, Camille R; Grumbach, Giesela

2015-01-01

The authors present a conceptual framework for expanding the use of relational theory with African-American women. Relational theory (RT) informs practice with women but is inadequate in addressing all aspects of culture and identity. RT presumes that all women desire or are able to make therapeutic connections, yet race, gender, and cultural experiences influence their ability to do so. Successful practice with minority women must address racism and its impact. Critical race theory (CRT) that incorporates a solution-focused (SF) approach is well-suited to address the limits of RT. This overview of a CRT/SF approach describes treatment for diverse women that extends RT and enhances effective social work practice to provide culturally sensitive treatment to women.

On a random area variable arising in discrete-time queues and compact directed percolation

International Nuclear Information System (INIS)

Kearney, Michael J

2004-01-01

A well-known discrete-time, single-server queueing system with mean arrival rate λ and mean departure rate μ is considered from the perspective of the area, A, swept out by the queue occupation process during a busy period. We determine the exact form of the tail of the distribution, Pr(A > x); in particular, we show that Pr(A > x) ∼ Cx -1/4 exp(-Dx 1/2 ) for all ρ ≠ 1, where ρ ≡ λ/μ, and expressions for C and D are given. For the critical case ρ = 1 we show that Pr(A > x) ∼ C'x -1/3 , with C' also given. A simple mapping, used in the derivation, establishes a connection with compact directed percolation on a square lattice. As a corollary, therefore, we are also able to specify the large-area asymptotic behaviour of this model at all points in the phase diagram. This extends previous scaling results, which are only valid close to the percolation threshold

Probability theory a comprehensive course

CERN Document Server

Klenke, Achim

2014-01-01

This second edition of the popular textbook contains a comprehensive course in modern probability theory. Overall, probabilistic concepts play an increasingly important role in mathematics, physics, biology, financial engineering and computer science. They help us in understanding magnetism, amorphous media, genetic diversity and the perils of random developments at financial markets, and they guide us in constructing more efficient algorithms.   To address these concepts, the title covers a wide variety of topics, many of which are not usually found in introductory textbooks, such as:   • limit theorems for sums of random variables • martingales • percolation • Markov chains and electrical networks • construction of stochastic processes • Poisson point process and infinite divisibility • large deviation principles and statistical physics • Brownian motion • stochastic integral and stochastic differential equations. The theory is developed rigorously and in a self-contained way, with the c...

Progress on study of nuclear data theory and related fields at the Theory Group of CNDC

Energy Technology Data Exchange (ETDEWEB)

Zhigang, Ge [China Nuclear Data Center, CIAE (China)

1996-06-01

The Theory Group of CNDC (China Nuclear Data Center) has made a lot of progress in nuclear reaction theory and its application as well as many other related fields in 1995. The recent progress in nuclear reaction theory study and its applications, the recent progress in the nuclear data calculation and related code development are introduced. The production rate of radioactive nuclear beam induced by 70 MeV protons on {sup 72}Ge target were calculated. The calculated results are presented.

Testing special relativity theory using Compton scattering

International Nuclear Information System (INIS)

Contreras S, H.; Hernandez A, L.; Baltazar R, A.; Escareno J, E.; Mares E, C. A.; Hernandez V, C.; Vega C, H. R.

2010-10-01

The validity of the special relativity theory has been tested using the Compton scattering. Since 1905 several experiments has been carried out to show that time, mass, and length change with the velocity, in this work the Compton scattering has been utilized as a simple way to show the validity to relativity. The work was carried out through Monte Carlo calculations and experiments with different gamma-ray sources and a gamma-ray spectrometer with a 3 x 3 NaI (Tl) detector. The pulse-height spectra were collected and the Compton edge was observed. This information was utilized to determine the relationship between the electron's mass and energy using the Compton -knee- position, the obtained results were contrasted with two collision models between photon and electron, one model was built using the classical physics and another using the special relativity theory. It was found that calculations and experiments results fit to collision model made using the special relativity. (Author)

Hundres Years of Theory of Relativity

Directory of Open Access Journals (Sweden)

Jaroslav Franek

2005-01-01

Full Text Available In 2005, all civilised worl will remind the 100 years anniversary of Publishing the original work on special theory of relativity by Albert Einstein. This contribution is a brief review of its principial ideas in the field of electrodynamics.

Relationalism or why diplomats find international relations theory strange

DEFF Research Database (Denmark)

Adler-Nissen, Rebecca

2015-01-01

In this conclusion, which reflects critically on the relational approach to diplomacy and its wider consequences, I argue that diplomats are estranged from IR theory and vice versa - because International Relations scholars generally subscribe to substantialism, whereas diplomats tend to think...... by diplomatic scholars). Relationalism takes as its point of departure the idea that social phenomena making up world politics always develop in relation to other social phenomena. Thus, for example, states are not born into' this world as fully developed states that then "exist"; states are made in continuous...... scholarship and diplomatic knowledge and practice are important for how we understand (and construct) world politics, including war, international cooperation, and responses to human and natural catastrophes....

Effect of diffusion on percolation threshold in thick-film resistors

International Nuclear Information System (INIS)

Abdurakhmanov, G.

2009-01-01

Resistivity ρ(C) of thick-film resistors doped by metal oxides is simulated as a function of volume content C of the ligature, firing temperature T f and firing time τ. It is proved that the doping of a glass during firing of the thick film resistor is rather uniform. It is shown also, that conductance takes place in the whole volume of the sample, but not through the sole infinite cluster only, even the content of a conductive phase is below than the theoretical percolation threshold value.

Reply to the "Certain Conceptual Anomalies in Einstein's Theory of Relativity" and Related Questions

Directory of Open Access Journals (Sweden)

Rabounski D.

2008-04-01

Full Text Available This paper answers twelve most common questions on the basics of Einstein’s theory of relativity. The answers remove most key problems with a real, solid understanding of the theory.

Indefinite-metric quantum field theory of general relativity

International Nuclear Information System (INIS)

Nakanishi, Noboru

1978-01-01

Quantum field theory of Einstein's general relativity is formulated in the indefinitemetric Hilbert space in such a way that asymptotic fields are manifestly Lorentz covariant and the physical S-matrix is unitary. The general coordinate transformation is transcribed into a q-number transformation, called the BRS transformation. Its abstract definition is presented on the basis of the BRS transformation for the Yang-Mills theory. The BRS transformation for general relativity is then explicitly constructed. The gauge-fixing Lagrangian density and the Faddeev-Popov one are introduced in such a way that their sum behaves like a scalar density under the BRS transformation. One can then proceed in the same way as in the Kugo-Ojima formalism of the Yang-Mills theory to establish the unitarity of the physical S-matrix. (author)

Scaling and percolation in the small-world network model

Energy Technology Data Exchange (ETDEWEB)

Newman, M. E. J. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States); Watts, D. J. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)

1999-12-01

In this paper we study the small-world network model of Watts and Strogatz, which mimics some aspects of the structure of networks of social interactions. We argue that there is one nontrivial length-scale in the model, analogous to the correlation length in other systems, which is well-defined in the limit of infinite system size and which diverges continuously as the randomness in the network tends to zero, giving a normal critical point in this limit. This length-scale governs the crossover from large- to small-world behavior in the model, as well as the number of vertices in a neighborhood of given radius on the network. We derive the value of the single critical exponent controlling behavior in the critical region and the finite size scaling form for the average vertex-vertex distance on the network, and, using series expansion and Pade approximants, find an approximate analytic form for the scaling function. We calculate the effective dimension of small-world graphs and show that this dimension varies as a function of the length-scale on which it is measured, in a manner reminiscent of multifractals. We also study the problem of site percolation on small-world networks as a simple model of disease propagation, and derive an approximate expression for the percolation probability at which a giant component of connected vertices first forms (in epidemiological terms, the point at which an epidemic occurs). The typical cluster radius satisfies the expected finite size scaling form with a cluster size exponent close to that for a random graph. All our analytic results are confirmed by extensive numerical simulations of the model. (c) 1999 The American Physical Society.

Scaling and percolation in the small-world network model

International Nuclear Information System (INIS)

Newman, M. E. J.; Watts, D. J.

1999-01-01

In this paper we study the small-world network model of Watts and Strogatz, which mimics some aspects of the structure of networks of social interactions. We argue that there is one nontrivial length-scale in the model, analogous to the correlation length in other systems, which is well-defined in the limit of infinite system size and which diverges continuously as the randomness in the network tends to zero, giving a normal critical point in this limit. This length-scale governs the crossover from large- to small-world behavior in the model, as well as the number of vertices in a neighborhood of given radius on the network. We derive the value of the single critical exponent controlling behavior in the critical region and the finite size scaling form for the average vertex-vertex distance on the network, and, using series expansion and Pade approximants, find an approximate analytic form for the scaling function. We calculate the effective dimension of small-world graphs and show that this dimension varies as a function of the length-scale on which it is measured, in a manner reminiscent of multifractals. We also study the problem of site percolation on small-world networks as a simple model of disease propagation, and derive an approximate expression for the percolation probability at which a giant component of connected vertices first forms (in epidemiological terms, the point at which an epidemic occurs). The typical cluster radius satisfies the expected finite size scaling form with a cluster size exponent close to that for a random graph. All our analytic results are confirmed by extensive numerical simulations of the model. (c) 1999 The American Physical Society

DSR Theories, Conformal Group and Generalized Commutation Relation

International Nuclear Information System (INIS)

Leiva, Carlos

2006-01-01

In this paper the relationship of DSR theories and Conformal Group is reviewed. On the other hand, the relation between DSR Magueijo Smolin generators and generalized commutation relations is also shown

Relativistic theory of gravitation and nonuniqueness of the predictions of general relativity theory

International Nuclear Information System (INIS)

Logunov, A.A.; Loskutov, Yu.M.

1986-01-01

It is shown that while the predictions of relativistic theory of gravitation (RTG) for the gravitational effects are unique and consistent with the experimental data available, the relevant predictions of general relativity theory are not unique. Therewith the above nonuniqueness manifests itself in some effects in the first order in the gravitational interaction constant in others in the second one. The absence in GRT of the energy-momentum and angular momentum conservation laws for the matter and gravitational field taken together and its inapplicability to give uniquely determined predictions for the gravitational phenomena compel to reject GRT as a physical theory

Renormalization group theory outperforms other approaches in statistical comparison between upscaling techniques for porous media

Science.gov (United States)

Hanasoge, Shravan; Agarwal, Umang; Tandon, Kunj; Koelman, J. M. Vianney A.

2017-09-01

Determining the pressure differential required to achieve a desired flow rate in a porous medium requires solving Darcy's law, a Laplace-like equation, with a spatially varying tensor permeability. In various scenarios, the permeability coefficient is sampled at high spatial resolution, which makes solving Darcy's equation numerically prohibitively expensive. As a consequence, much effort has gone into creating upscaled or low-resolution effective models of the coefficient while ensuring that the estimated flow rate is well reproduced, bringing to the fore the classic tradeoff between computational cost and numerical accuracy. Here we perform a statistical study to characterize the relative success of upscaling methods on a large sample of permeability coefficients that are above the percolation threshold. We introduce a technique based on mode-elimination renormalization group theory (MG) to build coarse-scale permeability coefficients. Comparing the results with coefficients upscaled using other methods, we find that MG is consistently more accurate, particularly due to its ability to address the tensorial nature of the coefficients. MG places a low computational demand, in the manner in which we have implemented it, and accurate flow-rate estimates are obtained when using MG-upscaled permeabilities that approach or are beyond the percolation threshold.

Clustering and percolation threshold in diphase systems of random centered quantum dots of ZnSe

International Nuclear Information System (INIS)

Bondar', N.V.

2009-01-01

A characteristic feature due to the formation of a percolation phase transition of carriers has been observed in a two-phase system consisting of borosilicate glass with ZnSe quantum dots. For near-threshold quantum-dot concentrations, changes due to microscopic fluctuations of the quantum-dot density have been observed in the intensities of radiation emission bands. This phenomenon is reminiscent of critical opalescence, where similar fluctuations of the density of a pure substance arise near a phase transition. It is proposed that the dielectric mismatch between the matrix and ZnSe plays a large role in the carrier (exciton) delocalization, resulting in the appearance of a 'dielectric trap' on the interface and the formation there of surface states of excitons. The spatial overlapping of states which occurs at the critical concentration of quantum dots results in carrier tunneling and the appearance of a percolation transition in such a system

Direct separation of uranium and thorium from Qatrani phosphatic raw ore by consecutive percolation leaching

Energy Technology Data Exchange (ETDEWEB)

Hussein El-Sayed, M

1984-07-01

Phosphatic sandstone of Qatrani area contains high concentrations of uranium and thorium (1450 and 870 ppm respectively). These elements were directly separated from a representative sample of the ore by percolation leaching. Separation made was carried out by using two different leaching reagents, citric and nitric acids for obtaining two separate concentrates of U and Th consecutively from the sample. Uranium was leached first by using citric acid where other rock ingredients were left intact. The effects of: (a) increasing acid input amounts and (b) increasing leaching solution volumes (dilution) on U leaching efficiency were studied. The results revealed that citric acid reaction upon phosphate is limited in spite of higher residual acidity reported in the leach liquors. Regarding uranium, its leaching efficiency increased by increasing acid amounts and/or leaching solution volumes while fixing the acid input amounts. The efficiency of U leaching is more pronounced in the second case than in the first. Increasing U leaching while phosphate dissolution is limited could be interpreted as that the relative complexing affinity of citrate anion for hexavalent uranium is by far much greater than with phosphate. Thorium was thereafter leached by using dilute solutions of nitric acid to avoid dissolution of nitric acid to avoid dissolution of impurities. Percolation leaching experiments were thus performed on the uranium-free samples in the columns used previously in uranium leaching. The effects of increasing acid amounts and increasing leach liquor recycles on Th (and P/sub 2/O/sub 5/) leaching efficiency were studied.

Principles of general relativity theory in terms of the present day physics

International Nuclear Information System (INIS)

Pervushin, V.N.

1986-01-01

A hystory of gradual unification of general relativity theory and quantum field theory on the basis of unified geometrical principles is detected. The gauge invariance principles became universal for construction of all physical theories. Quantum mechanics, electrodynamics and Einstein gravitation theory were used to form geometrical principles. Identity of inertial and gravitational masses is an experimental basis of the general relativity theory (GRT). It is shown that correct understanding of GRT bases is a developing process related to the development of the present physics and stimulating this development

Estimating the Effects of Conversion of Agricultural Land to Urban Land on Deep Percolation of Irrigation Water in the Grand Valley, Western Colorado

Science.gov (United States)

Mayo, John W.

2008-01-01

The conversion of agricultural land to urban residential land is associated with rapid population growth in the Grand Valley of western Colorado. Information regarding the effects of this land-use conversion on deep percolation, irrigation-water application, and associated salt loading to the Colorado River is needed to support water-resource planning and conservation efforts. The Natural Resources Conservation Service (NRCS) assessed deep percolation and estimated salt loading derived from irrigated agricultural lands in the Grand Valley in a 1985 to 2002 monitoring and evaluation study (NRCS M&E). The U.S. Geological Survey (USGS), in cooperation with the Colorado River Salinity Control Forum and the Mesa Conservation District, quantified the current (2005-2006) deep percolation and irrigation-water application characteristics of 1/4-acre residential lots and 5-acre estates, urban parks, and urban orchard grass fields in the Grand Valley, and compared the results to NRCS M&E results from alfalfa-crop sites. In addition, pond seepage from three irrigation-water holding ponds was estimated. Salt loading was estimated for the urban study results and the NRCS M&E results by using standard salt-loading factors. A daily soil-moisture balance calculation technique was used at all urban study irrigated sites. Deep percolation was defined as any water infiltrating below the top 12 inches of soil. Deep percolation occurred when the soil-moisture balance in the first 12 inches of soil exceeded the field capacity for the soil type at each site. Results were reported separately for urban study bluegrass-only sites and for all-vegetation type (bluegrass, native plants, and orchard grass) sites. Deep percolation and irrigation-water application also were estimated for a complete irrigation season at three subdivisions by using mean site data from each subdivision. It was estimated that for the three subdivisions, 37 percent of the developed acreage was irrigated (the balance

Equivalence of the theories of reciprocity and general relativity

International Nuclear Information System (INIS)

Qadir, A.

1976-01-01

Khan's theory (Nuovo Cimento; 57B:321 (1968) and Int. J. Theor. Phys.; 6:383 (1972)) of reciprocity has been shown to be equivalent to the theory of general relativity (in a conformally flat space-time) in that the same predictions are made physically. It is is proved that, since 'centrifugal forces' are used by Khan, gravitational phenomena are being considered equal in status to electromagnetic phenomena, and hence the difference claimed to exist between Milne's theory and Khan's theory disappears. (author)

The relationship between Theory of Mind and Relational Frame Theory: Convergence of perspective-taking measures

NARCIS (Netherlands)

Hendriks, A.L.; Barnes-Holmes, Y.; McEnteggart, C.; Mey, H.R.A. De; Witteman, C.L.M.; Janssen, G.T.L.; Egger, J.I.M.

2016-01-01

Objective: Perspective-taking difficulties have been demonstrated in autism and schizophrenia spectrum disorders, among other clinical presentations, and are traditionally examined from a Theory of Mind (ToM) point of view. Relational Frame Theory (RFT) offers a behavioural and contextual

Test theories of special relativity: a general critique

International Nuclear Information System (INIS)

Maciel, A.K.A.; Tiomno, J.

1988-01-01

Absolute Spacetime Theories conceived for the purpose of testing Special Relativity (SR) are reviewed. It is found that most theories proposed were in fact SR in different coordinate systems, since in general no specific SR violations were introduced. Models based on possible SR violating mechanisms are considered. Misconceptions in recently published papers are examined. (author) [pt

A solid-on-solid invasion percolation model for self-affine interfaces

International Nuclear Information System (INIS)

Arizmendi, C.M.; Martin, H.O.; Sanchez, J.R.

1993-08-01

The scaling properties of the interface of a new growth model are studied. The model is based on the standard invasion percolation without trapping in which the solid-on-solid condition is imposed. The local correlation between points of the interface can be controlled through a parameter. The self-affine properties of the interface show strong dependence on the existence of the local correlation. The dependence of the relevant exponents of the interface with the correlation is analysed. (author). 8 refs, 4 figs

Action-Based Jurisprudence: Praxeological Legal Theory in Relation to Economic Theory, Ethics, and Legal Practice

Directory of Open Access Journals (Sweden)

Konrad Graf

2011-08-01

Full Text Available Action-based legal theory is a discrete branch of praxeology and the basis of an emerging school of jurisprudence related to, but distinct from, natural law. Legal theory and economic theory share content that is part of praxeology itself: the action axiom, the a priori of argumentation, universalizable property theory, and counterfactual-deductive methodology. Praxeological property-norm justification is separate from the strictly ethical “ought” question of selecting ends in an action context. Examples of action-based jurisprudence are found in existing “Austro-libertarian” literature. Legal theory and legal practice must remain distinct and work closely together if justice is to be found in real cases. Legal theorizing was shaped in religious ethical contexts, which contributed to confused field boundaries between law and ethics. The carrot and stick influence of rulers on theorists has distorted conventional economics and jurisprudence in particular directions over the course of centuries. An action-based approach is relatively immune to such sources of distortion in its methods and conclusions, but has tended historically to be marginalized from conventional institutions for this same reason.

Relating the archetypes of logarithmic conformal field theory

International Nuclear Information System (INIS)

Creutzig, Thomas; Ridout, David

2013-01-01

Logarithmic conformal field theory is a rich and vibrant area of modern mathematical physics with well-known applications to both condensed matter theory and string theory. Our limited understanding of these theories is based upon detailed studies of various examples that one may regard as archetypal. These include the c=−2 triplet model, the Wess–Zumino–Witten model on SL(2;R) at level k=−1/2 , and its supergroup analogue on GL(1|1). Here, the latter model is studied algebraically through representation theory, fusion and modular invariance, facilitating a subsequent investigation of its cosets and extended algebras. The results show that the archetypes of logarithmic conformal field theory are in fact all very closely related, as are many other examples including, in particular, the SL(2|1) models at levels 1 and −1/2 . The conclusion is then that the archetypal examples of logarithmic conformal field theory are practically all the same, so we should not expect that their features are in any way generic. Further archetypal examples must be sought

Relating the archetypes of logarithmic conformal field theory

Energy Technology Data Exchange (ETDEWEB)

Creutzig, Thomas, E-mail: tcreutzig@mathematik.tu-darmstadt.de [Department of Physics and Astronomy, University of North Carolina, Phillips Hall, CB 3255, Chapel Hill, NC 27599-3255 (United States); Fachbereich Mathematik, Technische Universität Darmstadt, Schloßgartenstraße 7, 64289 Darmstadt (Germany); Ridout, David, E-mail: david.ridout@anu.edu.au [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Mathematical Sciences Institute, Australian National University, Canberra, ACT 0200 (Australia)

2013-07-21

Logarithmic conformal field theory is a rich and vibrant area of modern mathematical physics with well-known applications to both condensed matter theory and string theory. Our limited understanding of these theories is based upon detailed studies of various examples that one may regard as archetypal. These include the c=−2 triplet model, the Wess–Zumino–Witten model on SL(2;R) at level k=−1/2 , and its supergroup analogue on GL(1|1). Here, the latter model is studied algebraically through representation theory, fusion and modular invariance, facilitating a subsequent investigation of its cosets and extended algebras. The results show that the archetypes of logarithmic conformal field theory are in fact all very closely related, as are many other examples including, in particular, the SL(2|1) models at levels 1 and −1/2 . The conclusion is then that the archetypal examples of logarithmic conformal field theory are practically all the same, so we should not expect that their features are in any way generic. Further archetypal examples must be sought.

Special relativity and classical field theory

CERN Document Server

Susskind, Leonard

2017-01-01

Physicist Leonard Susskind and data engineer Art Friedman are back. This time, they introduce readers to Einstein's special relativity and Maxwell's classical field theory. Using their typical brand of real math, enlightening drawings, and humor, Susskind and Friedman walk us through the complexities of waves, forces, and particles by exploring special relativity and electromagnetism. It's a must-read for both devotees of the series and any armchair physicist who wants to improve their knowledge of physics' deepest truths.

The theory of relativity and super-light-speeds-I: Kinematical part

International Nuclear Information System (INIS)

Cao Shenglin.

1987-05-01

According to some local properties of Lorentz transformation, Einstein stated: ''Velocities greater than that of light have no possibility of existence''. He neglected to point out the applicable range of the special theory of relativity. In fact, it could only be applied to the sub-light-speed. This paper shows that if we think of the possibility of the existence of the super-light-speed and redescribe the special theory of relativity following Einstein's way, a new kinematical theory would be founded. The new theory would retain all kinematical meaning of the special theory of relativity when matters move with sub-light-speed and would give new content when matters move with super-light-speed. The paper also discusses the observation principle for the motions with the super-light-speed. (author). 2 refs, 1 fig

The special theory of relativity

CERN Document Server

Devanathan, V

2015-01-01

THE SPECIAL THEORY OF RELATIVITY, designed as a text book for undergraduate and postgraduate students, deals with the Michelson-Morley experiment, the concept of unified space and time, the Lorentz transformation of physical quantities, length contraction, time dilation, the Minkowski space, the mass-energy relation, the concept of four-vectors, the relativistic mechanics, the laws of transformation between centre of momentum and laboratory systems, the relativistic kinematics, the unification of laws of electricity and magnetism into laws of electromagnetism, the invariance of Maxwell's equations under Lorentz transformation and the Lorentz transformation of electromagnetic quantities. KEY FEATURES: * Review Questions * Problems * Solutions to Problems * Multiple Choice Questions

Applications of Jarzynski's relation in lattice gauge theories

DEFF Research Database (Denmark)

Nada, Alessandro; Caselle, Michele; Costagliola, Gianluca

2016-01-01

Jarzynski's equality is a well-known result in statistical mechanics, relating free-energy differences between equilibrium ensembles with fluctuations in the work performed during non-equilibrium transformations from one ensemble to the other. In this work, an extension of this relation to lattice...... gauge theory will be presented, along with numerical results for the ℤ2 gauge model in three dimensions and for the equation of state in SU(2) Yang-Mills theory in four dimensions. Then, further applications will be discussed, in particular for the Schrödinger functional and for the study of QCD...

Albert Einstein and the relativity theory

International Nuclear Information System (INIS)

Pavlickova, E.

1975-01-01

A bibliography is presented of Albert Einstein's works, listing his correspondence, biographical literature, articles on A. Einstein published in Czech journals, principal relativity theory monographs and popular, historical and philosophical publications. The bibliographical records are listed alphabetically. Most references give the abbreviations of libraries where the publications are available. (J.P.)

On Certain Conceptual Anomalies in Einstein's Theory of Relativity

OpenAIRE

Crothers S. J.

2008-01-01

There are a number of conceptual anomalies occurring in the Standard exposition of Einstein’s Theory of Relativity. These anomalies relate to issues in both mathematics and in physics and penetrate to the very heart of Einstein’s theory. This paper reveals and amplifies a few such anomalies, including the fact that Einstein’s field equations for the so-called static vacuum configuration, R = 0 , violates his Principle of Equiv- alence, and is therefore ...

Effects of inhibitory neurons on the quorum percolation model and dynamical extension with the Brette-Gerstner model

Science.gov (United States)

Fardet, Tanguy; Bottani, Samuel; Métens, Stéphane; Monceau, Pascal

2018-06-01

The Quorum Percolation model (QP) has been designed in the context of neurobiology to describe the initiation of activity bursts occurring in neuronal cultures from the point of view of statistical physics rather than from a dynamical synchronization approach. This paper aims at investigating an extension of the original QP model by taking into account the presence of inhibitory neurons in the cultures (IQP model). The first part of this paper is focused on an equivalence between the presence of inhibitory neurons and a reduction of the network connectivity. By relying on a simple topological argument, we show that the mean activation behavior of networks containing a fraction η of inhibitory neurons can be mapped onto purely excitatory networks with an appropriately modified wiring, provided that η remains in the range usually observed in neuronal cultures, namely η ⪅ 20%. As a striking result, we show that such a mapping enables to predict the evolution of the critical point of the IQP model with the fraction of inhibitory neurons. In a second part, we bridge the gap between the description of bursts in the framework of percolation and the temporal description of neural networks activity by showing how dynamical simulations of bursts with an adaptive exponential integrate-and-fire model lead to a mean description of bursts activation which is captured by Quorum Percolation.

Scalar mass relations and flavor violations in supersymmetric theories

International Nuclear Information System (INIS)

Cheng, Hsin-Chia; California Univ., Berkeley, CA

1996-01-01

Supersymmetry provides the most promising solution to the gauge hierarchy problem. For supersymmetry to stablize the hierarchy, it must be broken at the weak scale. The combination of weak scale supersymmetry and grand unification leads to a successful prediction of the weak mixing angle to within 1% accuracy. If supersymmetry is a symmetry of nature, the mass spectrum and the flavor mixing pattern of the scalar superpartners of all the quarks and leptons will provide important information about a more fundamental theory at higher energies. We studied the scalar mass relations which follow from the assumption that at high energies there is a grand unified theory which leads to a significant prediction of the weak mixing angle; these will serve as important tests of grand unified theories. Two intragenerational mass relations for each of the light generations are derived. A third relation is also found which relates the Higgs masses and the masses of all three generation scalars. In a realistic supersymmetric grand unified theory, nontrivial flavor mixings are expected to exist at all gaugino vertices. This could lead to important contributions to the neutron electric dipole moment, the decay mode p → K 0 μ + , weak scale radiative corrections to the up-type quark masses, and lepton flavor violating signals such as μ → eγ. These also provide important probes of physics at high energy scales. Supersymmetric theories involving a spontaneously broken flavor symmetry can provide a solution to the supersymmetric flavor-changing problem and an understanding of the fermion masses and mixings. We studied the possibilities and the general conditions under which some fermion masses and mixings can be obtained radiatively. We also constructed theories of flavor in which the first generation fermion masses arise from radiative corrections while flavor-changing constraints are satisfied. 69 refs., 19 figs., 9 tabs

Quadratic mass relations in topological bootstrap theory

International Nuclear Information System (INIS)

Jones, C.E.; Uschersohn, J.

1980-01-01

From the requirement of reality of discontinuities of scattering amplitudes at the spherical level of the topological bootstrap theory, a large number of mass relations for hadrons is derived. Quadratic mass formulas for the symmetry-breaking pattern of both mesons and baryon is obtained and their relation to conventional models of symmetry breaking is briefly discussed

Moral Judgment and Its Relation to Second-Order Theory of Mind

Science.gov (United States)

Fu, Genyue; Xiao, Wen S.; Killen, Melanie; Lee, Kang

2014-01-01

Recent research indicates that moral judgment and 1st-order theory of mind abilities are related. What is not known, however, is how 2nd-order theory of mind is related to moral judgment. In the present study, we extended previous findings by administering a morally relevant theory of mind task (an accidental transgressor) to 4- to 7-year-old…

Description of vibrational properties of random alloy ZnTe{sub 1-x}Se{sub x} within the percolation model

Energy Technology Data Exchange (ETDEWEB)

Souhabi, Jihane; Chafi, Allal; Kassem, Mohammed; Nassour, Ayoub; Gleize, Jerome; Postnikov, A.V.; Hugel, J.; Pages, Olivier [Laboratoire de Physique des Milieux Denses, Universite Paul Verlaine - Metz, 1 Bd Arago, 57070 Metz (France)

2009-05-15

We discuss the classification of the phonon type behavior of semiconductor alloys as apparent in the Raman and infrared spectra, i.e. in terms of types (i) 1-bond{yields}1-mode and (ii) 2-bond{yields}1-mode (both covered by the Modified Random Element Isodisplacement model, operating at the macroscopic scale), and also (iii) the modified 2-mode type (exceptional), in the framework of the recent 1-bond{yields}2-mode percolation model based on a description of the alloy disorder at the mesoscopic scale. The leading systems of types (i) and (iii), i.e., InGaAs and InGaP, respectively, were earlier shown to obey the percolation model. The aim of this work is to investigate whether the percolation model further extends to the leading system of the last type (ii), i.e. ZnTeSe. With this end in view, we perform a careful re-examination of the Raman and infrared spectra of this alloy, as available in the literature. Special attention is awarded to the discussion and modeling of the puzzling multi-mode infrared reflectivity spectra. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effect of degree correlations above the first shell on the percolation transition

OpenAIRE

Valdez, L. D.; Buono, C.; Braunstein, L. A.; Macri, P. A.

2011-01-01

The use of degree-degree correlations to model realistic networks which are characterized by their Pearson's coefficient, has become widespread. However the effect on how different correlation algorithms produce different results on processes on top of them, has not yet been discussed. In this letter, using different correlation algorithms to generate assortative networks, we show that for very assortative networks the behavior of the main observables in percolation processes depends on the a...

The special theory of relativity foundations, theory, verification, applications

CERN Document Server

Christodoulides, Costas

2016-01-01

This book offers a comprehensive, university-level introduction to Einstein’s Special Theory of Relativity. In addition to the purely theoretical aspect, emphasis is also given to its historical development as well as to the experiments that preceded the theory and those performed in order to test its validity. The main body of the book consists of chapters on Relativistic Kinematics and Dynamics and their applications, Optics and Electromagnetism. These could be covered in a one-semester course. A more advanced course might include the subjects examined in the other chapters of the book and its appendices. As a textbook, it has some unique characteristics: It provides detailed proofs of the theorems, offers abundant figures and discusses numerous examples. It also includes a number of problems for readers to solve, the complete solutions of which are given at the end of the book. It is primarily intended for use by university students of physics, mathematics and engineering. However, as the mathematics nee...

Relation of a unified quantum field theory of spinors to the structure of general relativity

International Nuclear Information System (INIS)

Kober, Martin

2009-01-01

Based on a unified quantum field theory of spinors assumed to describe all matter fields and their interactions we construct the space-time structure of general relativity according to a general connection within the corresponding spinor space. The tetrad field and the corresponding metric field are composed from a space-time dependent basis of spinors within the internal space of the fundamental matter field. Similar to twistor theory the Minkowski signature of the space-time metric is related to this spinor nature of elementary matter, if we assume the spinor space to be endowed with a symplectic structure. The equivalence principle and the property of background independence arise from the fact that all elementary fields are composed from the fundamental spinor field. This means that the structure of space-time according to general relativity seems to be a consequence of a fundamental theory of matter fields and not a presupposition as in the usual setting of relativistic quantum field theories.

Modern approach to relativity theory (radar formulation)

International Nuclear Information System (INIS)

Strel'tsov, V.N.

1991-01-01

The main peculiarities of the radar formulation of the relativity theory are presented. This formulation operates with the retarded (light) distances and relativistic or radar length introduced on their basis. 21 refs.; 1 tab

Current flow in random resistor networks: the role of percolation in weak and strong disorder.

Science.gov (United States)

Wu, Zhenhua; López, Eduardo; Buldyrev, Sergey V; Braunstein, Lidia A; Havlin, Shlomo; Stanley, H Eugene

2005-04-01

We study the current flow paths between two edges in a random resistor network on a L X L square lattice. Each resistor has resistance e(ax) , where x is a uniformly distributed random variable and a controls the broadness of the distribution. We find that: (a) The scaled variable u identical with u congruent to L/a(nu) , where nu is the percolation connectedness exponent, fully determines the distribution of the current path length l for all values of u . For u > 1, the behavior corresponds to the weak disorder limit and l scales as l approximately L, while for u < 1 , the behavior corresponds to the strong disorder limit with l approximately L(d(opt) ), where d(opt) =1.22+/-0.01 is the optimal path exponent. (b) In the weak disorder regime, there is a length scale xi approximately a(nu), below which strong disorder and critical percolation characterize the current path.

Interpreting doubly special relativity as a modified theory of measurement

International Nuclear Information System (INIS)

Liberati, Stefano; Sonego, Sebastiano; Visser, Matt

2005-01-01

In this article we develop a physical interpretation for the deformed (doubly) special relativity theories (DSRs), based on a modification of the theory of measurement in special relativity. We suggest that it is useful to regard the DSRs as reflecting the manner in which quantum gravity effects induce Planck-suppressed distortions in the measurement of the 'true' energy and momentum. This interpretation provides a framework for the DSRs that is manifestly consistent, nontrivial, and in principle falsifiable. However, it does so at the cost of demoting such theories from the level of fundamental physics to the level of phenomenological models - models that should in principle be derivable from whatever theory of quantum gravity one ultimately chooses to adopt

Complexity and multifractal behaviors of multiscale-continuum percolation financial system for Chinese stock markets

Science.gov (United States)

Zeng, Yayun; Wang, Jun; Xu, Kaixuan

2017-04-01

A new financial agent-based time series model is developed and investigated by multiscale-continuum percolation system, which can be viewed as an extended version of continuum percolation system. In this financial model, for different parameters of proportion and density, two Poisson point processes (where the radii of points represent the ability of receiving or transmitting information among investors) are applied to model a random stock price process, in an attempt to investigate the fluctuation dynamics of the financial market. To validate its effectiveness and rationality, we compare the statistical behaviors and the multifractal behaviors of the simulated data derived from the proposed model with those of the real stock markets. Further, the multiscale sample entropy analysis is employed to study the complexity of the returns, and the cross-sample entropy analysis is applied to measure the degree of asynchrony of return autocorrelation time series. The empirical results indicate that the proposed financial model can simulate and reproduce some significant characteristics of the real stock markets to a certain extent.

Multiscale synchrony behaviors of paired financial time series by 3D multi-continuum percolation

Science.gov (United States)

Wang, M.; Wang, J.; Wang, B. T.

2018-02-01

Multiscale synchrony behaviors and nonlinear dynamics of paired financial time series are investigated, in an attempt to study the cross correlation relationships between two stock markets. A random stock price model is developed by a new system called three-dimensional (3D) multi-continuum percolation system, which is utilized to imitate the formation mechanism of price dynamics and explain the nonlinear behaviors found in financial time series. We assume that the price fluctuations are caused by the spread of investment information. The cluster of 3D multi-continuum percolation represents the cluster of investors who share the same investment attitude. In this paper, we focus on the paired return series, the paired volatility series, and the paired intrinsic mode functions which are decomposed by empirical mode decomposition. A new cross recurrence quantification analysis is put forward, combining with multiscale cross-sample entropy, to investigate the multiscale synchrony of these paired series from the proposed model. The corresponding research is also carried out for two China stock markets as comparison.

The vacuum structure, special relativity theory and quantum mechanics revisited: a field theory-no-geometry approach

International Nuclear Information System (INIS)

Bogolubov, N.N. Jr.; Prykarpatsky, A.K.; Ufuk Taneri

2008-07-01

The main fundamental principles characterizing the vacuum field structure are formulated and the modeling of the related vacuum medium and charged point particle dynamics by means of de- vised field theoretic tools are analyzed. The Maxwell electrodynamic theory is revisited and newly derived from the suggested vacuum field structure principles and the classical special relativity theory relationship between the energy and the corresponding point particle mass is revisited and newly obtained. The Lorentz force expression with respect to arbitrary non-inertial reference frames is revisited and discussed in detail, and some new interpretations of relations between the special relativity theory and quantum mechanics are presented. The famous quantum-mechanical Schroedinger type equations for a relativistic point particle in the external potential and magnetic fields within the quasiclassical approximation as the Planck constant (h/2π) → 0 and the light velocity c → ∞ are obtained. (author)

Percolation Effects in Very-High-Energy Cosmic Rays

International Nuclear Information System (INIS)

Dias de Deus, J.; Santo, M.C. Espirito; Pimenta, M.; Pajares, C.

2006-01-01

Cosmic ray data at high energies present a number of well-known puzzles. At very high energies (E∼10 20 eV) there are indications of a discrepancy between ground array experiments and fluorescence detectors. On the other hand, the dependence of the depth of the shower maximum X max with the primary energy shows a change in slope (E∼10 17 eV) which is usually explained assuming a composition change. Both effects could be accounted for in models predicting that above a certain energy showers would develop deeper in the atmosphere. In this Letter we argue that this can be done naturally by including percolation effects in the description of the shower development, which cause a change in the behavior of the inelasticity K above E≅10 17 eV

Simple method to calculate percolation, Ising and Potts clusters

International Nuclear Information System (INIS)

Tsallis, C.

1981-01-01

A procedure ('break-collapse method') is introduced which considerably simplifies the calculation of two - or multirooted clusters like those commonly appearing in real space renormalization group (RG) treatments of bond-percolation, and pure and random Ising and Potts problems. The method is illustrated through two applications for the q-state Potts ferromagnet. The first of them concerns a RG calculation of the critical exponent ν for the isotropic square lattice: numerical consistence is obtained (particularly for q→0) with den Nijs conjecture. The second application is a compact reformulation of the standard star-triangle and duality transformations which provide the exact critical temperature for the anisotropic triangular and honeycomb lattices. (Author) [pt

Pretreatment Characteristics of Waste Oak Wood by Ammonia Percolation

Science.gov (United States)

Kim, Jun-Seok; Kim, Hyunjoon; Lee, Jin-Suk; Lee, Joon-Pyo; Park, Soon-Chul

A log of waste oak wood collected from a Korean mushroom farm has been tested for ammonia percolation pretreatment. The waste log has different physical characteristics from that of virgin oak wood. The density of the waste wood was 30% lower than that of virgin oak wood. However, there is little difference in the chemical compositions between the woods. Due to the difference in physical characteristics, the optimal pretreatment conditions were also quite different. While for waste oak the optimum temperature was determined to be 130°C, for virgin oak wood the optimum pretreatment was only achieved at 170°C. Presoaking for 12 h with ammonia solution before pretreatment was helpful to increase the delignification efficiency.

Percolation-induced plasmonic state and double negative electromagnetic properties of Ni-Zn Ferrite/Cu granular composite materials

Science.gov (United States)

Massango, Herieta; Kono, Koji; Tsutaoka, Takanori; Kasagi, Teruhiro; Yamamoto, Shinichiro; Hatakeyama, Kenichi

2018-05-01

Complex permeability and permittivity spectra of Ni-Zn Ferrite/Cu hybrid granular composite materials have been studied in the RF to microwave frequency range. The electrical conductivity σ shows insulating properties in the volume fraction of Cu particles below φ = 0.14. A large jump in conductivity was observed between φ = 0.14 and 0.24 indicating that the Cu particles make metallic conduction between this interval. Hence, the percolation threshold φC, was estimated to be 0.14. A percolation-induced low frequency plasmonic state with negative permittivity spectrum was observed from φ = 0.14-0.24. Meanwhile the negative permeability was observed at φ = 0.16, 0.19 and 0.24. Hence the DNG characteristic was realized in these Cu volume content in the frequency range from 105 MHz to 2 GHz.

Seasonal monitoring of melt and accumulation within the deep percolation zone of the Greenland Ice Sheet and comparison with simulations of regional climate modeling

Science.gov (United States)

Heilig, Achim; Eisen, Olaf; MacFerrin, Michael; Tedesco, Marco; Fettweis, Xavier

2018-06-01

Increasing melt over the Greenland Ice Sheet (GrIS) recorded over the past several years has resulted in significant changes of the percolation regime of the ice sheet. It remains unclear whether Greenland's percolation zone will act as a meltwater buffer in the near future through gradually filling all pore space or if near-surface refreezing causes the formation of impermeable layers, which provoke lateral runoff. Homogeneous ice layers within perennial firn, as well as near-surface ice layers of several meter thickness have been observed in firn cores. Because firn coring is a destructive method, deriving stratigraphic changes in firn and allocation of summer melt events is challenging. To overcome this deficit and provide continuous data for model evaluations on snow and firn density, temporal changes in liquid water content and depths of water infiltration, we installed an upward-looking radar system (upGPR) 3.4 m below the snow surface in May 2016 close to Camp Raven (66.4779° N, 46.2856° W) at 2120 m a.s.l. The radar is capable of quasi-continuously monitoring changes in snow and firn stratigraphy, which occur above the antennas. For summer 2016, we observed four major melt events, which routed liquid water into various depths beneath the surface. The last event in mid-August resulted in the deepest percolation down to about 2.3 m beneath the surface. Comparisons with simulations from the regional climate model MAR are in very good agreement in terms of seasonal changes in accumulation and timing of onset of melt. However, neither bulk density of near-surface layers nor the amounts of liquid water and percolation depths predicted by MAR correspond with upGPR data. Radar data and records of a nearby thermistor string, in contrast, matched very well for both timing and depth of temperature changes and observed water percolations. All four melt events transferred a cumulative mass of 56 kg m-2 into firn beneath the summer surface of 2015. We find that

A test theory of special relativity

International Nuclear Information System (INIS)

Mansouri, R.; Sexl, R.U.

1977-01-01

Various second-order optical tests of special relativity are discussed within the framework of a test theory developed previously. Owing to the low accuracy of the Kennedy-Thorndike experiment, the Lorentz contraction is known by direct experiments only to an accuracy of a few percent. To improve this accuracy several experiments are suggested. (author)

The Concept of Security in International Relations Theory

Directory of Open Access Journals (Sweden)

Gabriel Orozco

2006-01-01

Full Text Available The end of the Cold War and the emergence of globalisation have transformed the reality of International Relations, which has meant a change in the theories which this reality had assumed. The concept of security reveals itself as an organisational idea on the different phenomena of globalisation, carrying out a programme of research that goes beyond the realistic presumptions of military power or of the idealistic principles of research for peace. This article explores the new meanings of security for International Relations theory and discusses the theoretical models that influence policy design and that aim to confront the problems and challenges of security in globalisation.

Construction and operation of a pilot percolator installation for the processing of biological wastes; Bau und Betrieb einer Perkolationsanlage im Pilotmasstab zur Aufbereitung von Bioabfaellen

Energy Technology Data Exchange (ETDEWEB)

Schober, G.; Wellinger, A. [Nova Energie GmbH, Aadorf (Switzerland); Widmer, Ch. [AFAG Engineering, Binningen (Switzerland)

2004-07-01

This final report presents a review of the results of work done on behalf of the Swiss Federal Office of Energy (SFOE) on the development of a new two-step, two-phase system for waste treatment with biogas generation. The report describes the main components of the system - the percolator itself and the anaerobic digester. In the one-cubic-metre pilot batch percolator, followed by a four-cubic-metre hybrid anaerobic filter, source-separated household and green waste was percolated. The report deals with the optimisation of physicochemical, biological and process parameters in order to improve COD (Chemical Oxygen Demand) removal rates and, consequently, gas yield. Figures are presented on tests made with varying washing-water and aeration rates in order to optimise COD removal.

Technical principles underlying limit values for release of substances for the percolation test TS3: comparison DE and NL