Arbitrary Connectivity Research Articles

Implicit gas-kinetic unified algorithm based on multi-block docking grid for multi-body reentry flows covering all flow regimes

Based on the previous researches of the Gas-Kinetic Unified Algorithm (GKUA) for flows from highly rarefied free-molecule transition to continuum, a new implicit scheme of cell-centered finite volume method is presented for directly solving the unified Boltzmann model equation covering various flow regimes. In view of the difficulty in generating the single-block grid system with high quality for complex irregular bodies, a multi-block docking grid generation method is designed on the basis of data transmission between blocks, and the data structure is constructed for processing arbitrary connection relations between blocks with high efficiency and reliability. As a result, the gas-kinetic unified algorithm with the implicit scheme and multi-block docking grid has been firstly established and used to solve the reentry flow problems around the multi-bodies covering all flow regimes with the whole range of Knudsen numbers from 10 to 3.7E−6. The implicit and explicit schemes are applied to computing and analyzing the supersonic flows in near-continuum and continuum regimes around a circular cylinder with careful comparison each other. It is shown that the present algorithm and modelling possess much higher computational efficiency and faster converging properties. The flow problems including two and three side-by-side cylinders are simulated from highly rarefied to near-continuum flow regimes, and the present computed results are found in good agreement with the related DSMC simulation and theoretical analysis solutions, which verify the good accuracy and reliability of the present method. It is observed that the spacing of the multi-body is smaller, the cylindrical throat obstruction is greater with the flow field of single-body asymmetrical more obviously and the normal force coefficient bigger. While in the near-continuum transitional flow regime of near-space flying surroundings, the spacing of the multi-body increases to six times of the diameter of the single-body, the interference effects of the multi-bodies tend to be negligible. The computing practice has confirmed that it is feasible for the present method to compute the aerodynamics and reveal flow mechanism around complex multi-body vehicles covering all flow regimes from the gas-kinetic point of view of solving the unified Boltzmann model velocity distribution function equation.

Model checking mobile ad hoc networks

Modeling arbitrary connectivity changes within mobile ad hoc networks (MANETs) makes application of automated formal verification challenging. We use constrained labeled transition systems as a semantic model to represent mobility. To model check MANET protocols with respect to the underlying topology and connectivity changes, we introduce a branching-time temporal logic. The path quantifiers are parameterized by multi-hop constraints over topologies, to discriminate the paths over which the temporal behavior should be investigated; the paths that violate the multi-hop constraints are not considered. A model checking algorithm is presented to verify MANETs that allow arbitrary mobility, under the assumption of reliable communication. It is applied to analyze a leader election protocol.

Controlling charge quantization with quantum fluctuations

In 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits in which single electrons are manipulated, with applications in, for example, metrology, detectors and thermometry. However, as the connection strength is increased, the discreteness of charge is progressively reduced by quantum fluctuations. Here we report the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometre-scale metallic island to a circuit, we explore the complete evolution of charge quantization while scanning the entire range of connection strengths, from a very weak (tunnel) to a perfect (ballistic) contact. We observe, when approaching the ballistic limit, that charge quantization is destroyed by quantum fluctuations, and scales as the square root of the residual probability for an electron to be reflected across the quantum channel; this scaling also applies beyond the different regimes of connection strength currently accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization and in a universal square-root scaling, valid for all connection strengths, in agreement with expectations. Besides being pertinent for the improvement of single-electron circuits and their applications, and for the metal-semiconductor hybrids relevant to topological quantum computing, knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices.

General Multi-Porosity simulation for fractured reservoir modeling

In the area of fractured reservoir modeling, conventional Dual Porosity Models is challenged to flexibly simulate more than two porosity systems and it is also difficult to capture the transient fluid transfer between matrix and fracture. This work aims to solve those problems in fractured reservoir simulation. The newly introduced Multi-Porosity Model honors any number of porosity types with different properties, such as permeability, porosity and wettability thus achieving significant improvements over conventional Dual-Porosity Models. Arbitrary connections for intra-porosity flow and inter-porosity flow are incorporated into the design to allow for the convenient transformation between Multi-Porosity and Multi-Permeability formulations. The addition of a flexible subdivision in each porosity system has allowed us to characterize the transient flow for inter-porosity flow. Due to the low permeability in the matrix, transient flow between matrix and fracture dominates, and thus matrix spatial subdivision is necessary to accurately capture the dynamics. The formulation is designed to allow the proposed scheme to be generalized. To quantify the improvements available with the new formulation, several typical Multi-Porosity Models are compared with Fine-Grid Single-Porosity Models. Consistent results have been obtained with those similar cases from literature, and the robustness and efficiency of the model is validated. Besides, the extra matrix subdivision is proven to accurately capture the transient fluid transfer between matrix and fracture.

Robust Localization Algorithm Based on Best Length Optimization for Wireless Sensor Networks

In this paper, a robust range-free localization algorithm by realizing best hop length optimization is proposed for node localization problem in wireless sensor networks (WSNs). This algorithm is derived from classic DV-Hop method but the critical hop length between any relay nodes is accurately computed and refined in space WSNs with arbitrary network connectivity. In case of network parameters hop length between nodes can be derived without complicated computation and further optimized using Kalman filtering in which guarantees robustness even in complicated environment with random node communication range. Especially sensor fusion techniques used has well gained robustness, accuracy, scalability, and power efficiency even without accurate distance or angle measurement which is more suitable in nonlinear conditions and power limited WSNs environment. Simulation results indicate it gained high accuracy compared with DV-Hop and Centroid methods in random communication range conditions which proves it gives characteristic of high robustness. Also it needs relatively little computation time which possesses high efficiency. It can well solve localization problem with many unknown nosed in the network and results prove the theoretical analysis.

Improving the network scalability of Erlang

As the number of cores grows in commodity architectures so does the likelihood of failures. A distributed actor model potentially facilitates the development of reliable and scalable software on these architectures. Key components include lightweight processes which ‘share nothing’ and hence can fail independently. Erlang is not only increasingly widely used, but the underlying actor model has been a beacon for programming language design, influencing for example Scala, Clojure and Cloud Haskell.While the Erlang distributed actor model is inherently scalable, we demonstrate that it is limited by some pragmatic factors. We address two network scalability issues here: globally registered process names must be updated on every node (virtual machine) in the system, and any Erlang nodes that communicate maintain an active connection. That is, there is a fully connected O(n2) network of n nodes.We present the design, implementation, and initial evaluation of a conservative extension of Erlang — Scalable Distributed (SD) Erlang. SD Erlang partitions the global namespace and connection network using s_groups. An s_group is a set of nodes with its own process namespace and with a fully connected network within the s_group, but only individual connections outside it. As a node may belong to more than one s_group it is possible to construct arbitrary connection topologies like trees or rings.We present an operational semantics for the s_group functions, and outline the validation of conformance between the implementation and the semantics using the QuickCheck automatic testing tool. Our preliminary evaluation in comparison with distributed Erlang shows that SD Erlang dramatically improves network scalability even if the number of global operations is tiny (0.01%). Moreover, even in the absence of global operations the reduced connection maintenance overheads mean that SD Erlang scales better beyond 80 nodes (1920 cores).

Computing with Tangles

Tangles of graphs have been introduced by Robertson and Seymour in the context of their graph minor theory. Tangles may be viewed as describing “$k$-connected components” of a graph (though in a twisted way). An interesting aspect of tangles is that they can be defined not only for graphs, but more generally for arbitrary connectivity functions (that is, integer-valued submodular and symmetric set functions). However, tangles are difficult to deal with algorithmically. To start with, it is unclear how to represent them, because they are families of separations and, as such, may be exponentially large. Our first contribution is a data structure for representing and accessing all tangles of a graph up to some fixed order. Using this data structure, we can prove an algorithmic version of a very general structure theorem due to Carmesin et al. (for graphs) and Hundertmark (for arbitrary connectivity functions) that yields a canonical tree decomposition whose parts correspond to the maximal tangles. This may be viewed as a generalization of the decomposition of a graph into its 3-connected components.

Effects of local and global network connectivity on synergistic epidemics.

Epidemics in networks can be affected by cooperation in transmission of infection and also connectivity between nodes. An interplay between these two properties and their influence on epidemic spread are addressed in the paper. A particular type of cooperative effects (called synergy effects) is considered, where the transmission rate between a pair of nodes depends on the number of infected neighbors. The connectivity effects are studied by constructing networks of different topology, starting with lattices with only local connectivity and then with networks that have both local and global connectivity obtained by random bond-rewiring to nodes within a certain distance. The susceptible-infected-removed epidemics were found to exhibit several interesting effects: (i) for epidemics with strong constructive synergy spreading in networks with high local connectivity, the bond rewiring has a negative role in epidemic spread, i.e., it reduces invasion probability; (ii) in contrast, for epidemics with destructive or weak constructive synergy spreading on networks of arbitrary local connectivity, rewiring helps epidemics to spread; (iii) and, finally, rewiring always enhances the spread of epidemics, independent of synergy, if the local connectivity is low.

Path statistics, memory, and coarse-graining of continuous-time random walks on networks.

Continuous-time random walks (CTRWs) on discrete state spaces, ranging from regular lattices to complex networks, are ubiquitous across physics, chemistry, and biology. Models with coarse-grained states (for example, those employed in studies of molecular kinetics) or spatial disorder can give rise to memory and non-exponential distributions of waiting times and first-passage statistics. However, existing methods for analyzing CTRWs on complex energy landscapes do not address these effects. Here we use statistical mechanics of the nonequilibrium path ensemble to characterize first-passage CTRWs on networks with arbitrary connectivity, energy landscape, and waiting time distributions. Our approach can be applied to calculating higher moments (beyond the mean) of path length, time, and action, as well as statistics of any conservative or non-conservative force along a path. For homogeneous networks, we derive exact relations between length and time moments, quantifying the validity of approximating a continuous-time process with its discrete-time projection. For more general models, we obtain recursion relations, reminiscent of transfer matrix and exact enumeration techniques, to efficiently calculate path statistics numerically. We have implemented our algorithm in PathMAN (Path Matrix Algorithm for Networks), a Python script that users can apply to their model of choice. We demonstrate the algorithm on a few representative examples which underscore the importance of non-exponential distributions, memory, and coarse-graining in CTRWs.

Beyond dual-porosity modeling for the simulation of complex flow mechanisms in shale reservoirs

The state of the art of modeling fluid flow in shale reservoirs is dominated by dual-porosity models which divide the reservoirs into matrix blocks that significantly contribute to fluid storage and fracture networks which principally control flow capacity. However, recent extensive microscopic studies reveal that there exist massive micro- and nano-pore systems in shale matrices. Because of this, the actual flow mechanisms in shale reservoirs are considerably more complex than can be simulated by the conventional dual-porosity models and Darcy’s law. Therefore, a model capturing multiple pore scales and flow can provide a better understanding of the complex flow mechanisms occurring in these reservoirs. This paper presents a micro-scale multiple-porosity model for fluid flow in shale reservoirs by capturing the dynamics occurring in three porosity systems: inorganic matter, organic matter (mainly kerogen), and natural fractures. Inorganic and organic portions of shale matrix are treated as sub-blocks with different attributes, such as wettability and pore structures. In kerogen, gas desorption and diffusion are the dominant physics. Since the flow regimes are sensitive to pore size, the effects of nano-pores and micro-pores in kerogen are incorporated into the simulator. The multiple-porosity model is built upon a unique tool for simulating general multiple-porosity systems in which several porosity systems may be tied to each other through arbitrary connectivities. This new model allows us to better understand complex flow mechanisms and eventually is extended into the reservoir scale through upscaling techniques. Sensitivity studies on the contributions of the different flow mechanisms and kerogen properties give some insight as to their importance. Results also include a comparison of the conventional dual-porosity treatment and show that significant differences in fluid distributions and dynamics are obtained with the improved multiple-porosity simulation.

Nonlinear network modeling of multi-module floating structures with arbitrary flexible connections

Multiple floating modules connected by flexible connectors can be viewed as a network structure. A standard modeling process for multi-module floating structures in arbitrary topology is presented by using network theory. A three-dimensional model is developed using the linear wave theory, dynamic model of single floating module, constitutive model of flexible connectors and model of a mooring system. As a typical application, a floating airport model is established and further its nonlinear dynamic responses and connector loads are analyzed. Numerical results show that the traditional linear analysis may underestimate the actual results. The methodology applied in this paper is extensible to many engineering problems with network structures alike.

Quantum gravity with torsion and non-metricity

We study the renormalization of theories of gravity with an arbitrary (torsional and non-metric) connection. The class of actions we consider is of the Palatini type, including the most general terms with up to two derivatives of the metric, but no derivatives of the connection. It contains 19 independent parameters. We calculate the one-loop beta functions of these parameters and find their fixed points. The Holst subspace is discussed in some detail and found not to be stable under renormalization. Some possible implications for ultraviolet and infrared gravity are discussed.

How We Speak When We Say Things about Ourselves in Social Media: A Semiotic Analysis of Content Curation

How We Speak When We Say Things about Ourselves in Social Media: A Semiotic Analysis of Content Curation

Dynamic message-passing approach for kinetic spin models with reversible dynamics.

A method to approximately close the dynamic cavity equations for synchronous reversible dynamics on a locally treelike topology is presented. The method builds on (a) a graph expansion to eliminate loops from the normalizations of each step in the dynamics and (b) an assumption that a set of auxilary probability distributions on histories of pairs of spins mainly have dependencies that are local in time. The closure is then effectuated by projecting these probability distributions on n-step Markov processes. The method is shown in detail on the level of ordinary Markov processes (n=1) and outlined for higher-order approximations (n>1). Numerical validations of the technique are provided for the reconstruction of the transient and equilibrium dynamics of the kinetic Ising model on a random graph with arbitrary connectivity symmetry.

Approximate method of free energy calculation for spin system with arbitrary connection matrix

The proposed method of the free energy calculation is based on the approximation of the energy distribution in the microcanonical ensemble by the Gaussian distribution. We hope that our approach will be effective for the systems with long-range interaction, where large coordination number q ensures the correctness of the central limit theorem application. However, the method provides good results also for systems with short-range interaction when the number q is not so large.

The Quest for Lesbian Ethics in Contemporary Middle-Eastern Cultures

In this paper, I want to show how the lesbian is denied any ethical framework for selfassertion within the morality of the closet. Drawing on Foucault’s, Bulter’s, and Wittig’s theories of bodies, power and sexuality, I examine the perplexing position of the lesbian within the moral codes of hegemonic Arab cultures that play a major role in making an arbitrary connection between morality and institutionalized heterosexuality in a manner that legitimatizes homophobia, either openly or in a subtle manner. In this context, I expose various types of discourses that are used as a means of controlling both the private and public spheres and of maintaining control over both worlds. “If power is everywhere”, as Foucault argued, so too is resistance possible from multiple sources. Hence, in my paper, I confront several forces that forbid the emergence of lesbian ethics in most Middle-Eastern societies-----Bibliography: Al-Ghafari, Iman: The Quest for Lesbian Ethics in Contemporary Middle-Eastern Cultures, INSEP, Vol. 2, Issue 1/2014, pp. 19-38. https://doi.org/10.3224/insep.v2i1.17061

The role of rapid naming in reading development and dyslexia in Chinese

We examined in a series of studies the mechanism that may underlie the relationship between Rapid Automatized Naming (RAN) and reading (accuracy and fluency) in Mandarin Chinese. Study 1 examined the “arbitrary” connections hypothesis in a sample of Grade 2 children (N=182). Study 2 contrasted the phonological processing, orthographic processing, and speed of processing hypotheses in a sample of Grade 2 children followed until Grade 5 (N=72). Finally, Study 3 contrasted the same hypotheses in a sample of Grade 4 children with dyslexia (n=30) and chronological-age controls (n=30). The results indicated that (a) RAN is unrelated to Paired Associate Learning (PAL) tasks that tap the ability to form arbitrary connections between characters and their pronunciation, (b) controlling for nonverbal IQ and orthographic processing was sufficient to explain the RAN–reading accuracy relationship but not the RAN–reading fluency relationship, and (c) the observed differences between dyslexics and controls in RAN diminished after controlling for orthographic processing. Taken together, these findings suggest that RAN is related to reading accuracy (and partly to reading fluency) because children must access orthographic representations from long-term memory. Although accessing these representations is sufficient for accurate word recognition, it is not sufficient for fluent reading, which also requires efficient parafoveal processing.

Origin of symbol-using systems: speech, but not sign, without the semantic urge.

Natural language—spoken and signed—is a multichannel phenomenon, involving facial and body expression, and voice and visual intonation that is often used in the service of a social urge to communicate meaning. Given that iconicity seems easier and less abstract than making arbitrary connections between sound and meaning, iconicity and gesture have often been invoked in the origin of language alongside the urge to convey meaning. To get a fresh perspective, we critically distinguish the origin of a system capable of evolution from the subsequent evolution that system becomes capable of. Human language arose on a substrate of a system already capable of Darwinian evolution; the genetically supported uniquely human ability to learn a language reflects a key contact point between Darwinian evolution and language. Though implemented in brains generated by DNA symbols coding for protein meaning, the second higher-level symbol-using system of language now operates in a world mostly decoupled from Darwinian evolutionary constraints. Examination of Darwinian evolution of vocal learning in other animals suggests that the initial fixation of a key prerequisite to language into the human genome may actually have required initially side-stepping not only iconicity, but the urge to mean itself. If sign languages came later, they would not have faced this constraint.

Topological self-dual vacua of deformed gauge theories

We propose a deformation principle of gauge theories in three dimensions that can describe topologically stable self-dual gauge fields, i.e., vacua configurations that in spite of their masses do not deform the background geometry and are locally undetected by charged particles. We interpret these systems as describing boundary degrees of freedom of a self-dual Yang-Mills field in 2 + 2 dimensions with mixed boundary conditions. Some of these fields correspond to Abrikosov-like vortices with an exponential damping in the direction penetrating into the bulk. We also propose generalizations of these ideas to higher dimensions and arbitrary p-form gauge connections.

Introduction to Code Biology

An operative definition is one that allows us to make experimental tests that prove whether or not organic codes do exist in Nature. The starting point is the idea that a code is always a set of rules that establish a correspondence between two independent worlds (Barbieri 2003). The Morse code, for example, is a correspondence (or a mapping) between the letters of the alphabet and groups of dots and dashes. The highway code is a correspondence between street signals and driving behaviours (a red light means ‘stop’, a green light means ‘go’, and so on). What is essential in all codes is that the coding rules are not dictated by the laws of physics and chemistry. In this sense they are arbitrary, and the number of arbitrary relationships between two independent worlds is potentially unlimited. In the Morse code, for example, any letter of the alphabet can be associated with countless combinations of dots and dashes, which means that a specific link between them can be realized only by selecting a small number of rules. And this is precisely what a code is: a small set of arbitrary rules selected from a potentially unlimited number in order to ensure a specific correspondence between two independent worlds. In biology, organic codes are relationships between two worlds of organic molecules and are necessarily implemented by other molecules, called adaptors, that build a bridge between them. The adaptors are required because there is no necessary link between the two worlds, and a fixed set of adaptors is required in order to guarantee the specificity of the correspondence (Barbieri 2003). The adaptors, in short, are essential in all organic codes. They are the molecular fingerprints of the codes, and their presence in a biological process is a sure sign that that process is based on a code. This gives us an objective criterion for the discovery of the organic codes, and their existence in Nature is no longer a matter of speculation. It is, first and foremost, an experimental problem. More precisely, we can prove that an organic code exists, if we prove the existence of three entities: (1) two independents worlds of molecules, (2) a potentially unlimited number of arbitrary connections between them implemented by adaptors, and (3) a selection of the adaptors (a set of coding rules) that ensures a specific correspondence.