Non-Arrhenius Behavior of Secondary Relaxation in Supercooled Liquids

Dielectric relaxation spectroscopy (1 Hz - 20 GHz) has been performed on supercooled glass-formers from the temperature of glass transition (T_g) up to that of melting. Precise measurements particularly in the frequencies of MHz-order have revealed that the temperature dependences of secondary beta-relaxation times deviate from the Arrhenius relation in well above T_g. Consequently, our results indicate that the beta-process merges into the primary alpha-mode around the melting temperature, and not at the dynamical transition point T which is approximately equal to 1.2 T_g.Comment: 4 pages, 4 figures, revtex

Developments in the Ni–Nb–Zr amorphous alloy membranes

Most of the global H2 production is derived from hydrocarbon-based fuels, and efficient H2/CO2 separation is necessary to deliver a high-purity H2 product. Hydrogen-selective alloy membranes are emerging as a viable alternative to traditional pressure swing adsorption processes as a means for H2/CO2 separation. These membranes can be formed from a wide range of alloys, and those based on Pd are the closest to commercial deployment. The high cost of Pd (USD *31,000 kg-1) is driving the development of less-expensive alternatives, including inexpensive amorphous (Ni60Nb40)100-xZrx alloys. Amorphous alloy membranes can be fabricated directly from the molten state into continuous ribbons via melt spinning and depending on the composition can exhibit relatively high hydrogen permeability between 473 and 673 K. Here we review recent developments in these low-cost membrane materials, especially with respect to permeation behavior, electrical transport properties, and understanding of local atomic order. To further understand the nature of these solids, atom probe tomography has been performed, revealing amorphous Nb-rich and Zr-rich clusters embedded in majority Ni matrix whose compositions deviated from the nominal overall composition of the membrane

A framework for the probabilistic analysis of meteotsunamis

This paper is not subject to U.S. copyright. The definitive version was published in Natural Hazards 74 (2014): 123-142, doi:10.1007/s11069-014-1294-1.A probabilistic technique is developed to assess the hazard from meteotsunamis. Meteotsunamis are unusual sea-level events, generated when the speed of an atmospheric pressure or wind disturbance is comparable to the phase speed of long waves in the ocean. A general aggregation equation is proposed for the probabilistic analysis, based on previous frameworks established for both tsunamis and storm surges, incorporating different sources and source parameters of meteotsunamis. Parameterization of atmospheric disturbances and numerical modeling is performed for the computation of maximum meteotsunami wave amplitudes near the coast. A historical record of pressure disturbances is used to establish a continuous analytic distribution of each parameter as well as the overall Poisson rate of occurrence. A demonstration study is presented for the northeast U.S. in which only isolated atmospheric pressure disturbances from squall lines and derechos are considered. For this study, Automated Surface Observing System stations are used to determine the historical parameters of squall lines from 2000 to 2013. The probabilistic equations are implemented using a Monte Carlo scheme, where a synthetic catalog of squall lines is compiled by sampling the parameter distributions. For each entry in the catalog, ocean wave amplitudes are computed using a numerical hydrodynamic model. Aggregation of the results from the Monte Carlo scheme results in a meteotsunami hazard curve that plots the annualized rate of exceedance with respect to maximum event amplitude for a particular location along the coast. Results from using multiple synthetic catalogs, resampled from the parent parameter distributions, yield mean and quantile hazard curves. Further refinements and improvements for probabilistic analysis of meteotsunamis are discussed

High-frequency dynamics of type-B glass formers investigated by broadband dielectric spectroscopy

We present the results of broadband dielectric spectroscopy on two glass formers with strong Johari-Goldstein beta-relaxations. In addition to the alpha- and beta-relaxation dynamics, the extension of the spectra up to 1 THz also allows revealing information on the fast beta-process in this class of materials. There is clear evidence for a fast process contributing in the region of the high-frequency loss minimum, which is analyzed in terms of the idealized mode-coupling theory.Comment: 7 pages, 5 figure

Chlorinated and brominated polycyclic aromatic hydrocarbons in ambient air: seasonal variation, profiles, potential sources, and size distribution

Chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs, respectively) are a new derivative group of PAHs. These halogenated PAHs (Halo-PAHs) have been reported to be carcinogenic and are considered emerging persistent organic pollutants. Gaining a clear understanding of the distribution and behavior of these ubiquitous organic pollutants is essential for the control and mitigation of their emission into the environment. However, research into the characteristics of Halo-PAHs in the atmosphere has been somewhat limited. This review paper thus aims to provide an overview of the seasonal patterns, profiles, potential sources, and particle-size distributions of atmospheric ClPAHs and BrPAHs with 3-5 rings. Most previous studies have focused on particulate Halo-PAHs and reported that their levels are higher during the cold season than during the warm season, with this seasonal variation more apparent for ClPAHs than for BrPAHs. In terms of their phase distribution, ClPAHs and BrPAHs share a similar trend, with their gaseous concentrations highest in summer and lowest in winter and their particulate concentrations exhibiting the opposite trend. Halo-PAH profiles have been shown to differ between sampling locations, possibly reflecting differences in the potential sources present at these sites, e.g., coal burning, traffic emissions, and industrial activity. The majority of Halo-PAHs tend to accumulate as ultrafine particles with an aerodynamic diameter of less than 1.0 mu m. Overall, a detailed understanding of the characteristics of Halo-PAHs in the atmosphere has yet to be achieved; hence, further research on atmospheric Halo-PAHs is necessary

The Potentials of Meme Media Technology for Web-Based Training at the Emergency Situation Map

Disaster management is a very important field of civil protection. For effective protection of the population, some governmental institutions or agencies provide training in crisis management teams. An important aspect of working in a crisis management team is managing and presenting information on the current situation. It is difficult to learn the practical implementation of the information representation only from such short term training opportunities. A preliminary Web-based practice of the workflow within a realistic situation will help to solve the problem and increase the quality of the training. This paper discusses the possibility of building such a Web-based training environment for teaching and learning the situation map which is powered by the Webble technology

Non-invasive three-dimensional bone-vessel image fusion using black bone MRI based on FIESTA-C

AIM: To evaluate the image quality of bone-vessel fused volume-rendering (VR) images reconstructed by three-dimensional "black bone" magnetic resonance imaging (MRI) based on the fast imaging employing steady-state acquisition cycled phases (FIESTA-C) sequence and time-of-flight magnetic resonance angiography (TOF-MRA). MATERIALS AND METHODS: Seventeen patients were analysed in this retrospective study. All patients underwent both MRI techniques including FIESTA-C and TOF-MRA and computed tomography angiography (CTA). MRI- and CT-based bone-vessel VR images were reconstructed. Visual depictions of frontal and parietal branches from the superficial temporal artery (STA) were independently scored by three experienced radiological technologists using a four-grade system. RESULTS: In the visual evaluation, the scores of the both right and left frontal branches in MRI-based VR image were significantly larger those at CT (p<0.01, respectively). The scores of both the right and left parietal branches tended to be larger in MRI-based than that in CT-based VR imaging, but were not significantly so (p=0.06, 0.13 respectively). In the interobserver agreement analysis, K values were all good (range: 0.6-0.76) for STA branch evaluation in MRI-based VR images. CONCLUSION: MRI bone-vessel fused VR imaging can non-invasively depict STA frontal branches with better visibility compared to the CT-based VR imaging. This technique may be useful for the preoperative evaluation of donor branches for STA-middle cerebral artery bypass surgery. (C) 2019 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved

Adaptive behavior with user modeling and storyboarding in serious games

Game-based learning has a certain potential in the domain of the technological enhanced learning. On the other hand, the advantages of an adaptive system is obvious especially in the educational domain. The process of learning can be improved if a serious game can adapt to the needs, preferences and behavior of the players or the needs of educational experts. However, it is hard to realize highly effective adaptive game because it is difficult for educational experts to realize their didactic ideas directly in the system. In the design phase of the serious game development, storyboards are used as specifications of player experience. In this paper, we describe how adaptive behaviors are implemented in a serious game with the storyboard interpretation technology, with which non-programmers can modify the game system behaviors. To make a system adaptive, the system must learn about the users, build up a user model, and then react or change the system behavior according to the user model. To realize these functionalities in a serious game, we use the Inventory of Learning Styles (LSI) as a user model and the storyboarding to describe different system behaviors depending on the modeled user profiles. Taking a large-scale training applications in the training of disaster management staff as an example, we show how different system behaviors are represented in a storyboard. Through the description of the example, we show that storyboard is an effective tool to change the learning environment for educational experts who are not familiar with programming language