bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric properties of Jovian satellite ice analogs for subsurface radar exploration: A review
Authors: Pettinelli Elena , Cosciotti Barbara , Di Paolo Federico , Lauro Sebastian Emanuel , Mattei Elisabetta , Orosei Roberto , Vannaroni Giuliano 
Published: May 2015

AbstractThe first European mission dedicated to the exploration of Jupiter and its icy moons (JUpiter ICy moons Explorer—JUICE) will be launched in 2022 and will reach its final destination in 2030. The main goals of this mission are to understand the internal structure of the icy crusts of three Galilean satellites (Europa, Ganymede, and Callisto) and, ultimately, to detect Europa's subsurface ocean, which is believed to be the closest to the surface among those hypothesized to exist on these moons. JUICE will be equipped with the 9 MHz subsurface‐penetrating radar RIME (Radar for Icy Moon Exploration), which is designed to image the ice down to a depth of 9 km. Moreover, a parallel mission to Europa, which will host onboard REASON (Radar for Europa Assessment and Sounding: Ocean to Near‐surface) equipped with 9MHz and 60MHz antennas, has been recently approved by NASA. The success of these experiments strongly relies on the accurate prediction of the radar performance and on the optimal processing and interpretation of radar echoes that, in turn, depend on the dielectric properties of the materials composing the icy satellite crusts. In the present review we report a complete range of potential ice types that may occur on these icy satellites to understand how they may affect the results of the proposed missions. First, we discuss the experimental results on pure and doped water ice in the framework of the Jaccard theory, highlighting the critical aspects in terms of a lack of standard laboratory procedures and inconsistency in data interpretation. We then describe the dielectric behavior of extraterrestrial ice analogs like hydrates and icy mixtures, carbon dioxide ice and ammonia ice. Building on this review, we have selected the most suitable data to compute dielectric attenuation, velocity, vertical resolution, and reflection coefficients for such icy moon environments, with the final goal being to estimate the potential capabilities of the radar missions as a function of the frequency and temperature ranges of interest for the subsurface sounders. We present the different subsurface scenarios and associated radar signal attenuation models that have been proposed so far to simulate the structure of the crust of Europa and discuss the physical and geological nature of various dielectric targets potentially detectable with RIME. Finally, we briefly highlight several unresolved issues that should be addressed, in near future, to improve our capability to produce realistic electromagnetic models of icy moon crusts. The present review is of interest for the geophysical exploration of all solar system bodies, including the Earth, where ice can be present at the surface or at relatively shallow depths.
The emergence of topographic steady state in a perpetually dynamic self‐organized critical landscape
Authors: Reinhardt Liam , Ellis Michael A. 
Published: May 2015

AbstractWe conducted a series of four physical modeling experiments of mountain growth at differing rates of uplift and three distinct climates ranging from relatively wet to relatively dry. The spatial and temporal pattern of landscape behavior is characterized by ∼f−1 scaling in sediment discharge and power law scaling in the magnitude and frequency of ridge movement in all four experiments. We find that internally generated self‐organized critical (SOC) processes generate dynamically stable catchment geometries after ∼1 relief depths of erosion: these regularly spaced catchments have an average outlet‐spacing ratio of 2.16, well within the range of values reported in field studies. Once formed, large catchment bounding ridges oscillate about a critically balanced mean location, with occasional large‐scale changes in catchment size. Ridge movement appears to be driven by the competition for discharge as landslides push ridges back and forth. These dynamics lead to the emergence of a complex twofold scaling in catchment dynamics that is fully established by 1.8 relief depths of erosion; at this stage, a clear threshold has emerged separating two distinct scaling regimes, where large ridge mobility is insensitive to relief and small ridge mobility is relief dependent. Overall, we demonstrate that the development of dynamically stable large‐scale landforms is related to the emergence of a complex‐system hierarchy in topographic dynamics. Once formed, these landscapes do not evolve; statistical properties such as average topography and discharge become stationary while topography remains highly dynamic at smaller length scales.
Probabilistic inference of multi‐Gaussian fields from indirect hydrological data using circulant embedding and dimensionality reduction
Authors: Laloy Eric , Linde Niklas , Jacques Diederik , Vrugt Jasper A. 
Published: May 2015

AbstractWe present a Bayesian inversion method for the joint inference of high‐dimensional multi‐Gaussian hydraulic conductivity fields and associated geostatistical parameters from indirect hydrological data. We combine Gaussian process generation via circulant embedding to decouple the variogram from grid cell specific values, with dimensionality reduction by interpolation to enable Markov chain Monte Carlo (MCMC) simulation. Using the Matérn variogram model, this formulation allows inferring the conductivity values simultaneously with the field smoothness (also called Matérn shape parameter) and other geostatistical parameters such as the mean, sill, integral scales and anisotropy direction(s) and ratio(s). The proposed dimensionality reduction method systematically honors the underlying variogram and is demonstrated to achieve better performance than the Karhunen‐Loève expansion. We illustrate our inversion approach using synthetic (error corrupted) data from a tracer experiment in a fairly heterogeneous 10,000‐dimensional 2‐D conductivity field. A 40‐times reduction of the size of the parameter space did not prevent the posterior simulations to appropriately fit the measurement data and the posterior parameter distributions to include the true geostatistical parameter values. Overall, the posterior field realizations covered a wide range of geostatistical models, questioning the common practice of assuming a fixed variogram prior to inference of the hydraulic conductivity values. Our method is shown to be more efficient than sequential Gibbs sampling (SGS) for the considered case study, particularly when implemented on a distributed computing cluster. It is also found to outperform the method of anchored distributions (MAD) for the same computational budget.
Map of low‐frequency electromagnetic noise in the sky
Authors: Füllekrug Martin , Mezentsev Andrew , Watson Robert , Gaffet Stéphane , Astin Ivan , Smith Nathan , Evans Adrian 
Published: May 2015

AbstractThe Earth's natural electromagnetic environment is disturbed by anthropogenic electromagnetic noise. Here we report the first results from an electromagnetic noise survey of the sky. The locations of electromagnetic noise sources are mapped on the hemisphere above a distributed array of wideband receivers that operate in a small aperture configuration. It is found that the noise sources can be localized at elevation angles up to ∼60° in the sky, well above the horizon. The sky also exhibits zones with little or no noise that are found toward the local zenith and the southwest of the array. These results are obtained by a rigorous analysis of the residuals from the classic dispersion relation for electromagnetic waves using an array analysis of electric field measurements in the frequency range from ∼20 to 250 kHz. The observed locations of the noise sources enable detailed observations of ionospheric modification, for example, caused by particle precipitation and lightning discharges, while the observed exclusion zones enable the detection of weak natural electromagnetic emissions, for example, from streamers in transient luminous events above thunderclouds.
Spatial distribution of low‐energy plasma around comet 67P/CG from Rosetta measurements
Authors: Edberg N. J. T. , Eriksson A. I. , Odelstad E. , Henri P. , Lebreton J.‐P. , Gasc S. , Rubin M. , André M. , Gill R. , Johansson E. P. G. , Johansson F. , Vigren E. , Wahlund J. E. , Carr C. M. , Cupido E. , Glassmeier K.‐H. , Goldstein R. , Koenders C. , Mandt K. , Nemeth Z. , Nilsson H. , Richter I. , Wieser G. Stenberg , Szego K. , Volwerk M. 
Published: May 2015

AbstractWe use measurements from the Rosetta plasma consortium Langmuir probe and mutual impedance probe to study the spatial distribution of low‐energy plasma in the near‐nucleus coma of comet 67P/Churyumov‐Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two main lobes of the comet, i.e., the neck region. There is a clear correlation with the neutral density and the plasma to neutral density ratio is found to be ∼1–2·10−6, at a cometocentric distance of 10 km and at 3.1 AU from the Sun. A clear 6.2 h modulation of the plasma is seen as the neck is exposed twice per rotation. The electron density of the collisionless plasma within 260 km from the nucleus falls off with radial distance as ∼1/r. The spatial structure indicates that local ionization of neutral gas is the dominant source of low‐energy plasma around the comet.
The Alfvén mode gyrokinetic equation in finite‐pressure magnetospheric plasma
Authors: Klimushkin Dmitri Yu. , Mager Pavel N. 
Published: May 2015

AbstractThe paper is concerned with the derivation of the Alfvén mode equation in finite‐pressure space plasma in gyrokinetic approach. The long plasma approximation is used, where the bounce frequency is much lower than both wave and drift frequencies. The only ultralow frequency mode in the long plasma approximation is the Alfvén‐ballooning compressional mode, which is described by the Alfvénic dispersion relation with some additional (ballooning) terms caused by the field line curvature and plasma pressure effects. Due to these effects the Alfvén mode acquires also considerable parallel magnetic field component. The long plasma approximation allowed us to consider the correspondence between the gyrokinetic and MHD approaches for the Alfvén mode equation. It is shown that in 0 < β ≪ 1 case, MHD approach gives correct Alfvén wave description, where β is plasma to magnetic pressure ratio.
Strontium source and depth of uptake shifts with substrate age in semiarid ecosystems
Authors: Coble Ashley A. , Hart Stephen C. , Ketterer Michael E. , Newman Gregory S. , Kowler Andrew L. 
Published: May 2015

AbstractWithout exogenous rock‐derived nutrient sources, terrestrial ecosystems may eventually regress or reach a terminal steady state, but the degree to which exogenous nutrient sources buffer or slow to a theoretical terminal steady state remains unclear. We used strontium isotope ratios (87Sr/86Sr) as a tracer and measured 87Sr/86Sr values in aeolian dust, soils, and vegetation across a well‐constrained 3 Myr semiarid substrate age gradient to determine (1) whether the contribution of atmospheric sources of rock‐derived nutrients to soil and vegetation pools varied with substrate age and (2) to determine if the depth of uptake varied with substrate age. We found that aeolian‐derived nutrients became increasingly important, contributing as much as 71% to plant‐available soil pools and tree (Pinus edulis) growth during the latter stages of ecosystem development in a semiarid climate. The depth of nutrient uptake increased on older substrates, demonstrating that trees in arid regions can acquire nutrients from greater depths as ecosystem development progresses presumably in response to nutrient depletion in the more weathered surface soils. Our results demonstrate that global and regional aeolian transport of nutrients to local ecosystems is a vital process for ecosystem development in arid regions. Furthermore, these aeolian nutrient inputs contribute to deep soil nutrient pools, which become increasingly important for maintaining plant productivity over long time scales.
UV grafting process for synthetic drag reduction of biomimetic riblet surfaces
Authors: Chen Huawei , Che Da , Zhang Xin , Zhang Deyuan 
Published: May 2015

ABSTRACTSkin–friction drag accounts for a large portion of resistance encountered by water‐based vehicles, such as ships and submarines. Developing drag reduction methods to improve drag reduction performance has drawn worldwide attention recently. UV‐induced polymerization has been investigated as a way to graft the drag reduction agent PAM on to a PVC substrate with a biomimetic riblet surface. The effects of AM concentration and irradiation time on the grafting rate were explored to determine optimal grafting parameters. UV grafting polymerization was clarified by comparing the peak absorption variation of the infrared spectrum before and after grafting. The PAM thin film grafted on riblet surface was measured approximately 10 µm in thickness. A rotating disk apparatus was built to measure the synthetic drag reduction performance. The drag reduction rate of the grafted PAM riblet surface was tested at approximately 14%, higher than the 6% of the traditional riblet surface. Moreover, the excellent drag reduction performance of grafted PDMS riblet surface lasted for 12 days. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42303.
How much hybridization does machine translation Need?
Authors: Costa‐jussà Marta R. 
Published: May 2015

Rule‐based and corpus‐based machine translation (MT) have coexisted for more than 20 years. Recently, boundaries between the two paradigms have narrowed and hybrid approaches are gaining interest from both academia and businesses. However, since hybrid approaches involve the multidisciplinary interaction of linguists, computer scientists, engineers, and information specialists, understandably a number of issues exist.While statistical methods currently dominate research work in MT, most commercial MT systems are technically hybrid systems. The research community should investigate the benefits and questions surrounding the hybridization of MT systems more actively. This paper discusses various issues related to hybrid MT including its origins, architectures, achievements, and frustrations experienced in the community. It can be said that both rule‐based and corpus‐ based MT systems have benefited from hybridization when effectively integrated. In fact, many of the current rule/corpus‐based MT approaches are already hybridized since they do include statistics/rules at some point.
Fermi–Dirac, Bose–Einstein, Maxwell–Boltzmann, and computers
Authors: Fazarinc Zvonko 
Published: May 2015

ABSTRACTFew statistics other than the named three have opened the path to understanding of so many natural laws and formulas employed in the engineering practice. Engineers interested in origins of expressions they may be using in their work will find some of them in this paper. Planck's Radiation and Stefan–Boltzmann Laws, Maxwell's Velocity Distributions, P‐N diode equation, and intrinsic hole and electron concentrations in semiconductors are some examples. No new inventions are presented and the topics addressed are treated in books on statistical mechanics, thermodynamics, quantum and classical physics, chemistry and others. The contribution is an integration of a broad range of sciences underlying the formulas of interest under one roof of a relatively short paper. All derivations are done at the engineering level and originate in the first principles of conservation and quantization. Discrete mathematics is employed throughout and provides direct access to computerized experimentation. The appendixes assist the uninitiated in quantum physics and provide an ample collection of useful supporting material. © 2015 Wiley Periodicals, Inc. Comput. Appl. Eng. Educ. Comput Appl Eng Educ 23:746–759, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21647
Toward Okinawa‐Style Robot‐Embedded Systems
Authors: Anezaki Takashi , Tansuriyavong Suriyon , Yamada Chikatoshi 
Published: May 2015

SUMMARYFor the Okinawan economy to grow independently, it is essential to create new businesses; this will require the cultivation of technologies that will form the basis for those businesses, as well as the training of technicians and researchers. To promote the creation of new businesses and innovation that are “Unique to Okinawa,” the Institute of Electrical Engineers of Japan set up a cooperative research committee to develop Okinawa‐style robot‐embedded systems. We proposed the concept of Okinawa‐style robot‐embedded systems. To realize this concept, we organized technical meetings to promote research. Now our research focuses on developing playback‐type navigation robots for use in land and air, and also on developing an underwater robot for conserving marine life in the waters around Okinawa. It is necessary to conduct proper measurements, observations, and sampling in water. To successfully perform these tasks, we needed to develop an underwater robot. We have made efforts in developing hardware, software, and applications for embedded techniques. We suggest that coarsely integrated operand scanning (CIOS) and bilateral filters (BFs) be implemented in hardware. We also developed devices to improve quality of life and to support disabled children through software.
Robust Mapping for Mobile Robot Based on Immobile Area Grid Map Considering Potential Moving Objects
Authors: Ito Akihisa , Takahashi Keita , Kaneko Masahide 
Published: May 2015

SUMMARYMobile robots need Simultaneous Localization and Mapping (SLAM) for autonomous movement in human living environments. The occupancy grid map used in SLAM is a conventional method which makes a map by an occupancy probability in each grid. This method renews a map based on whether an object is observed or not. In order to remove moving objects from a map, an additional method is required. However, conventional methods deal only with actually moving objects, and potential moving objects (e.g., standing humans) are mapped as static objects. Furthermore, only binary states, used or not used, are given to each object in map updating. This paper proposes the immobility area grid map to represent a map by an immobility probability in each grid. The proposed method renews a map based on the identification of observed objects by a robot's sensors, in addition to whether an object is observed or not. We introduce the map update parameter, which is set adaptively from the certainty of identification result of the object. Observed objects can take continuous states, truly static—unknown—truly moving, according to the parameter value. Potential moving objects are not mapped if the parameter takes values corresponding to moving objects. The experimental results show robust mapping in dynamic environments including potential moving objects.
Usability of AMeDAS Sunshine Duration Data for Statistical Evaluation of Spatial Average Irradiance Fluctuation Characteristics
Authors: Kato Takeyoshi , Harada Mikiharu , Suzuoki Yasuo , Honda Nobuyuki , Koaizawa Masakazu , Nishino Shinichi 
Published: May 2015

SUMMARYIn order to mitigate the impacts of high‐penetration photovoltaic power generation systems (HP‐PVS) on the electric power system operation, the statistical evaluation of the aggregated power output fluctuation characteristics of HP‐PVS is important. By using the multipoint irradiance data observed for a year in the Chubu region of Japan, we have evaluated the fluctuation characteristics of spatial average irradiance. However, the study period is not enough for a statistical evaluation. Therefore, this study assessed the usability of the sunlight duration data of AMeDAS (Automated Meteorological Data Acquisition System) for the statistical evaluation of fluctuation characteristics in terms of the daily maximum fluctuation width in 120 min. The method of irradiance estimation from the sunlight duration data at single point proposed in the preceding study was modified to be suitable for the spatial average irradiance estimation by taking into account the smoothing effect of irradiance fluctuation among several points. The results suggest that the AMeDAS sunlight duration data would be useful for statistical evaluation of the fluctuation characteristics of the spatial average irradiance of an electric power system service area.
Aqueous Synthesis and Visible‐Light Photochromism of Metastable h‐WO3 Hierarchical Nanostructures
Authors: Li Na , Zhao Yan , Wang Yi , Lu Yan , Song Yuehong , Huang Zhifang , Li Yawen , Zhao Jingzhe 
Published: May 2015

AbstractA facile aqueous approach to the synthesis of metastable hexagonal tungsten oxide (h‐WO3) hierarchical nanostructures at low temperature was investigated. The spherelike h‐WO3 architectures are constructed from 1D nanorods. Polyvinyl pyrrolidone (PVP) in the reaction system facilitates the quick formation of h‐WO3 nuclei of the metastable phase through electrostatic interactions between protonated PVP and tungstate anions, which is in accord with the rule of kinetics favoring the formation of the metastable form. PVP also acts as a soft template for the assembly of WO3 crystallites. Oriented growth of WO3 crystallites along the [001] direction resulted in the nanorod‐assembled h‐WO3 architectures. The h‐WO3‐rich samples all exhibited good recycled visible‐light photochromic performance.
Bio‐Inspired Formation of Silica Thin Films: From Solid Substrates to Cellular Interfaces
Authors: Cho Woo Kyung , Yang Sung Ho 
Published: May 2015

AbstractSilica formation in biological systems (biosilicification) has been intensively studied for synthesizing inorganic materials such as silica and titania under biocompatible conditions. Inspired by biosilicification, biocompatible strategies have been developed to fabricate silica thin films on the surfaces of solid substrates such as flat wafers and micro/nanoparticles. In the search for biological applications, these strategies have been applied to cellular surfaces to coat living cells with silica or titania thin films while maintaining cell viability, and it was found that the inorganic coat is beneficial for the protection of living cells and to control cell division. This Microreview focuses on bio‐inspired approaches to the formation of silica thin films on solid substrates and cellular surfaces, and includes the bio‐inspired formation of other inorganic thin films that have been formed by bio‐inspired silicification. The current status and future prospects of this field are also discussed.