Critical behavior and Griffiths effects in the disordered contact process

We study the nonequilibrium phase transition in the one-dimensional contact process with quenched spatial disorder by means of large-scale Monte-Carlo simulations for times up to $10^9$ and system sizes up to $10^7$ sites. In agreement with recent predictions of an infinite-randomness fixed point, our simulations demonstrate activated (exponential) dynamical scaling at the critical point. The critical behavior turns out to be universal, even for weak disorder. However, the approach to this asymptotic behavior is extremely slow, with crossover times of the order of $10^4$ or larger. In the Griffiths region between the clean and the dirty critical points, we find power-law dynamical behavior with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder.Comment: 10 pages, 8 eps figures, final version as publishe

Quarantine generated phase transition in epidemic spreading

We study the critical effect of quarantine on the propagation of epidemics on an adaptive network of social contacts. For this purpose, we analyze the susceptible-infected-recovered (SIR) model in the presence of quarantine, where susceptible individuals protect themselves by disconnecting their links to infected neighbors with probability w, and reconnecting them to other susceptible individuals chosen at random. Starting from a single infected individual, we show by an analytical approach and simulations that there is a phase transition at a critical rewiring (quarantine) threshold w_c separating a phase (w<w_c) where the disease reaches a large fraction of the population, from a phase (w >= w_c) where the disease does not spread out. We find that in our model the topology of the network strongly affects the size of the propagation, and that w_c increases with the mean degree and heterogeneity of the network. We also find that w_c is reduced if we perform a preferential rewiring, in which the rewiring probability is proportional to the degree of infected nodes.Comment: 13 pages, 6 figure

Fan Performance Analysis for Rotor Cooling of Axial Flux Permanent Magnet Machines

The thermal management of an Axial Flux Permanent Magnet (AFPM) machine is essential because it determines the machine’s continuous power output and reliability. In this paper, a secondary cooling method is proposed using rotor cooling which allows better thermal management on the permanent magnets that are attached to the rotor. This will reduce the potential of the machine failing due to magnet demagnetization and degradation. Thermal analysis via Lumped Parameter (LM) networks is usually sufficient in predicting the motor’s thermal behaviour. However, the accuracy of the prediction can be increased especially for devices with complex flow regions by Computational Fluid Dynamics (CFD). In this study, the fan blade was attached to the rotor of a Yokeless and Segmented Armature (YASA) machine for flow validation and then three different fan blade designs from other engineering applications were tested. The evaluation includes the flow characteristic, power requirement and thermal characteristic for the AFPM’s rotor cooling applications. Additionally, the Rotor Cooling Performance Index (RCPI) is introduced to assess each fan design performance.Publisher Statement: © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Dynamics at a smeared phase transition

We investigate the effects of rare regions on the dynamics of Ising magnets with planar defects, i.e., disorder perfectly correlated in two dimensions. In these systems, the magnetic phase transition is smeared because static long-range order can develop on isolated rare regions. We first study an infinite-range model by numerically solving local dynamic mean-field equations. Then we use extremal statistics and scaling arguments to discuss the dynamics beyond mean-field theory. In the tail region of the smeared transition the dynamics is even slower than in a conventional Griffiths phase: the spin autocorrelation function decays like a stretched exponential at intermediate times before approaching the exponentially small equilibrium value following a power law at late times.Comment: 10 pages, 8eps figures included, final version as publishe

Assortativity Decreases the Robustness of Interdependent Networks

It was recently recognized that interdependencies among different networks can play a crucial role in triggering cascading failures and hence system-wide disasters. A recent model shows how pairs of interdependent networks can exhibit an abrupt percolation transition as failures accumulate. We report on the effects of topology on failure propagation for a model system consisting of two interdependent networks. We find that the internal node correlations in each of the two interdependent networks significantly changes the critical density of failures that triggers the total disruption of the two-network system. Specifically, we find that the assortativity (i.e. the likelihood of nodes with similar degree to be connected) within a single network decreases the robustness of the entire system. The results of this study on the influence of assortativity may provide insights into ways of improving the robustness of network architecture, and thus enhances the level of protection of critical infrastructures

Development of the Inventory of Life Span Events

The possible relationship between stressful life events and subsequent illness has been studied in the past few decades, resulting in several widely-used questionnaires. However, these measures tend to focus on recent events and attempt to remove subjective rating of a stressful event by the respondent. These two factors may limit these scales clinical utility. An alternative measure, the Inventory of Life Span Events (ILSE) is proposed, to quantify the life-stress burden for childhood, adolescence, adulthood, and across the entire life span. ILSE was compared to other leading measures for life events, hassles and perceived stress, and was more closely related to life events than hassles or perceived stress measures. The comparative utility of these measures in explaining the variance for depressive, anxiety, neuroticism and dissociative symptoms was conducted. The ILSE childhood summary score (CHB) was specifically correlated with dissociation. ILSE displayed adequate validity through correlations with both life event and symptom measures and in predicting clinical vs. control group membership. ILSE also displayed adequate test-retest reliability on a six to eight week interval. It is anticipated ILSE will add a new dimension to life event assessment. Potential uses for the instrument concludes the write-up

Alien Registration- Dickison, William A. (Guilford, Piscataquis County)

https://digitalmaine.com/alien_docs/8390/thumbnail.jp

The Fan Design Impact on the Rotor Cooling of Axial Flux Permanent Magnet Machines

Thermal management of Axial Flux Permanent Magnet (AFPM) machines is essential because it determines the machine’s continuous power output and reliability. Also, thermal management is required to avoid catastrophic failure due to degradation. To help meet this challenge, a secondary cooling method can be integrated into the rotor, which can yield improved machine performance and reliability. Thermal analysis via Lumped Parameter (LM) networks is usually sufficient in predicting the thermal motor behaviour. Accuracy can be further increased with the help of Computational Fluid Dynamics (CFD), especially for devices with complex flow regions. In this paper, the fan blade was attached to the rotor of a YASA machine for flow validation, and then three different fan blade designs from other engineering applications were adopted, in order to compare the flow characteristic, power requirement and thermal characteristic for AFPM cooling applications

Epidemics in partially overlapped multiplex networks

Many real networks exhibit a layered structure in which links in each layer reflect the function of nodes on different environments. These multiple types of links are usually represented by a multiplex network in which each layer has a different topology. In real-world networks, however, not all nodes are present on every layer. To generate a more realistic scenario, we use a generalized multiplex network and assume that only a fraction $q$ of the nodes are shared by the layers. We develop a theoretical framework for a branching process to describe the spread of an epidemic on these partially overlapped multiplex networks. This allows us to obtain the fraction of infected individuals as a function of the effective probability that the disease will be transmitted $T$. We also theoretically determine the dependence of the epidemic threshold on the fraction $q > 0$ of shared nodes in a system composed of two layers. We find that in the limit of $q \to 0$ the threshold is dominated by the layer with the smaller isolated threshold. Although a system of two completely isolated networks is nearly indistinguishable from a system of two networks that share just a few nodes, we find that the presence of these few shared nodes causes the epidemic threshold of the isolated network with the lower propagating capacity to change discontinuously and to acquire the threshold of the other network.Comment: 13 pages, 4 figure

Rare region effects at classical, quantum, and non-equilibrium phase transitions

Rare regions, i.e., rare large spatial disorder fluctuations, can dramatically change the properties of a phase transition in a quenched disordered system. In generic classical equilibrium systems, they lead to an essential singularity, the so-called Griffiths singularity, of the free energy in the vicinity of the phase transition. Stronger effects can be observed at zero-temperature quantum phase transitions, at nonequilibrium phase transitions, and in systems with correlated disorder. In some cases, rare regions can actually completely destroy the sharp phase transition by smearing. This topical review presents a unifying framework for rare region effects at weakly disordered classical, quantum, and nonequilibrium phase transitions based on the effective dimensionality of the rare regions. Explicit examples include disordered classical Ising and Heisenberg models, insulating and metallic random quantum magnets, and the disordered contact process.Comment: Topical review, 68 pages, 14 figures, final version as publishe