bluuebunny/crossref_metadata_2025_split huggingface dataset:
Switching of a single atomic spin induced by spin injection: Effect of spin relaxation
Authors: Kokado Satoshi , Harigaya Kikuo , Sakuma Akimasa 
Published: June 2009

AbstractToward the manipulation of a single atomic spin, we theoretically study the switching of a localized quantum spin induced by spin injection. The system consists of electrode/spin quantum dot/electode junctions, in which the left electrode (right electrode) has conduction electrons with up spin (with down spin), and the dot has the localized quantum spin S = (Sx; Sy; Sz). This S has a uniaxial anisotropic energy, –|D|Sz 2, which shows the bistable potential between Sz = –S and S, with D being an anisotropy constant. Furthermore, S interacts with the atomic vibration. For the initial state of Sz = –S, we consider a situation in which up spin electrons exhibit the spin‐flip tunneling from the left electrode to the right one through an exchange interaction between the electron spin and S. We obtain the time dependence of the current, the expectation value of Sz, and that of the vibration quantum number using the master equation approach, in which a parameter related to the spin relaxation time, τ, is taken into account. On the basis of recent experimental results about an Fe atom on CuN surface [C. F. Hirjibehedin et al., Science 317, 1197 (2007)], we apply this theory to systems of S =2. As results, systems exhibit the switching or nonswitching depending on τ (≠ ∞) and the vibration energy within a period of 5 ns, while systems of τ = ∞ bring about the switching. The switching times are evaluated to be in the range of 0.44 ns – 3.8 ns (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First step to Si photonics: synthesis of quantum dot light‐emitters on GaP substrate by MBE
Authors: Guo Weiming , Bondi Alexandre , Cornet Charles , Folliot Hervé , Létoublon Antoine , Boyer‐Richard Soline , Chevalier Nicolas , Gicquel Maud , Alsahwa Bassem , Corre Alain Le , Even Jacky , Durand Olivier , Loualiche Slimane 
Published: June 2009

AbstractWe have grown InAs and InP quantum dots (QDs) on GaP substrate by Molecular Beam Epitaxy (MBE) and analysed them by Atomic Force Microscopy (AFM) and photoluminescence (PL). AFM images confirm the formation of InAs and InP QDs. Largest InAs QDs density is obtained at a growth temperature of 450 °C and under an AsH3 flux of 0.3SCCM. The evolution of QDs shape and absence of photoluminescence indicate a likely plastic relaxation of the strain between InAs and GaP. Concerning InP/GaP QDs, their lateral size, height and density indicate good quality QDs. Photoluminescence signal has been detected for capped InP/GaP QDs until 180 K. The unchanged peak position with respect to InP coverage is attributed to the nearly constant height of the QDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Field emission properties of carbon nanotube arrays grown in porous anodic alumina
Authors: Angelucci A. , Ciorba A. , Malferrari L. , Odorici F. , Rizzoli R. , Rossi M. , Sessa V. , Terranova M. L. , Veronese G. P. 
Published: June 2009

AbstractCarbon nanotubes (CNTs), with their excellent electronic properties and extremely high aspect ratio, represent an ideal material for building electron sources based on field emission. Fowler‐Nordheim equation describes quite successfully the field emission phenomenon, especially for single or isolated tips. However, some complications arise when populations of CNTs are considered, where collective effects and large variability in the emitters features influence the measured I–V characteristics. In this work, the emission properties of multi‐walled CNTs grown within ordered anodic alumina templates are investigated. These CNT matrices produce current densities up to some tens of mA/cm2, and the field enhancement factor for collective emission sources can be estimated. Such material can be modelled as an ordered and uniform array of emitters and a simulation of the electrostatic field on the emission tips can be done in order to evaluate the field enhancement factor and its dependence on various geometries. This allows comparing predictions from simulation and experimental measurements, in a direct way. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An analytical model for the rapid intensification of tropical cyclones
Authors: Kieu Chanh Q. , Zhang Da‐Lin 
Published: June 2009

AbstractThe nonlinearity and complexity of the primitive equations have been key obstacles to our understanding of tropical cyclones (TCs), particularly in relation to the dynamical processes leading to their rapid intensification. In this study, an axisymmetric model, in which all nonlinear terms in the horizontal momentum equations are retained, is used to examine analytically the effects of organized deep convection on TC rapid intensification. By prescribing a vertical profile of the vertical motion with exponential growth in the core region, a class of exact time‐dependent solutions for the primary circulations of TCs are obtained. The analytical solutions are shown to capture well many observed dynamical structures in both the core and outer regions and the rapid growth of TCs in terms of maximum winds and central pressure drops.The analytical solutions reveal that (1) the rotational flows in the inner‐core region grow double‐exponentially, and the central pressure drops occur at rates much faster than the rotational growth; (2) the amplification rates of the primary circulations differ profoundly from those of the secondary circulations; (3) the rotational flows tend to grow from the bottom upwards with the fastest growth occurring at the lowest levels; and (4) the TC growth rates depend critically on the vertical structure of tangential flows, with a faster rate for a lower‐level peak rotation. The nonlinear dynamics are shown to play an important role in the rapid growth of TCs. It is demonstrated that the analytical solutions can also be used to construct dynamically consistent vortices for the initialization of TC models. Limitations and possible improvements of the analytical model are also discussed. Copyright © 2009 Royal Meteorological Society
Covariance localisation and balance in an Ensemble Kalman Filter
Authors: Kepert Jeffrey D. 
Published: June 2009

AbstractA major limitation of the Ensemble Kalman Filter (EnKF) is that the finite ensemble size introduces sampling error into the background covariances, with severe consequences for atmospheric and oceanographic applications. The negative effects of sampling error are customarily limited by covariance localisation, which earlier studies have suggested may introduce imbalance into the system. The deleterious effects of localisation upon balance are confirmed and detailed here, with localisation producing analyses with weaker geostrophic balance and stronger divergence than are obtained using the unlocalised covariances. These imbalances reduce as the localisation radius is increased, but are argued to be large for typical settings. An improved method for calculating local covariances from an ensemble is presented, in which the localisation is performed in streamfunction–velocity potential (ψ–χ), rather than wind component, space. Analyses using this method better preserve the balances contained within the unlocalised covariance model. This transformation further allows the option of intervariable localisation, in which the cross‐covariances involving χ, which are weak and therefore particularly subject to sampling error, are set to 0 instead of being calculated from the ensemble. The various localisations are compared in a series of identical‐twin experiments, with the new localisations producing analyses that are better balanced and significantly more accurate than the usual approach. The localisation with the χ cross‐covariances set to 0 is shown to be superior for the smaller ensemble sizes but not for the larger, implying that the larger ensembles are capable of resolving some of the true χ cross‐covariance in the test system. Copyright © 2009 Royal Meteorological Society
Assessing the impact of observations on a local numerical fog prediction system
Authors: Rémy S. , Bergot T. 
Published: June 2009

AbstractAs poor visibility conditions have great influence on air traffic, a need exists for accurate, updated fog and low‐cloud forecasts. COBEL–ISBA, a boundary‐layer one‐dimensional numerical model, has been developed for the very short‐term forecasting of fog and low clouds. This forecasting system assimilates the information from a local observation system designed to provide details on the state of the surface boundary layer, as well as that of the fog and low‐cloud layers.This article aims to assess the influence of each component of the observation system on the initial conditions and low‐visibility forecasts. The objective is to obtain a quantitative assessment of the impact on numerical fog forecasts of using a reduced (for smaller‐sized airports) or enhanced (using a sodar) set of observations. We first used simulated observations, and focused on modelling the atmosphere before fog formation and then on simulating the life‐cycle of fog and low clouds. Within this framework, we also estimated the impact of using a sodar to estimate the thickness of the cloud layer. We showed that the radiative flux observations were the most important of all in cloudy conditions, and that the measurement mast did not have to be higher than 10 m. Using either a sodar or radiative flux to estimate the optical thickness of a cloud layer gave the same scores. Using both of them together did not significantly improve the forecast. Simulations with real observations over a winter of simulations confirmed these findings. Copyright © 2009 Royal Meteorological Society
Design and analysis for the Gaussian process model
Authors: Jones Bradley , Johnson Rachel T. 
Published: June 2009

AbstractIn an effort to speed the development of new products and processes, many companies are turning to computer simulations to avoid the time and expense of building prototypes. These computer simulations are often complex, taking hours to complete one run. If there are many variables affecting the results of the simulation, then it makes sense to design an experiment to gain the most information possible from a limited number of computer simulation runs. The researcher can use the results of these runs to build a surrogate model of the computer simulation model. The absence of noise is the key difference between computer simulation experiments and experiments in the real world. Since there is no variability in the results of computer experiments, optimal designs, which are based on reducing the variance of some statistic, have questionable utility. Replication, usually a ‘good thing’, is clearly undesirable in computer experiments. Thus, a new approach to experimentation is necessary. Published in 2009 by John Wiley & Sons, Ltd.
Lateral distribution of fishes in the main‐channel trough of a large floodplain river: Implications for restoration
Authors: Gutreuter Steve , Vallazza Jonathan M. , Knights Brent C. 
Published: June 2009

AbstractMajor river channels have been extensively altered worldwide. The development of restoration strategies for those alterations requires fundamental information, including the use of large deep channels by fishes. We trawled within parallel paths distributed across the width of the main‐channel trough of the Mississippi River to identify how the lateral distribution of fishes responds to variations in flow ranging from 50% to 200% of the annual median, water temperature ranging from 9 to 29°C and commercial shipping traffic ranging from 0 to 9 vessels per day. Among the species we encountered, only shovelnose sturgeon (Scaphirhynchus platorynchus) were persistent channel residents that remained concentrated along the main‐channel centreline regardless of flow, temperature and traffic. Other persistent residents showed no distinct pattern in lateral distribution, concentrated along the deep channel margins or varied in lateral distribution with flow. Surprisingly, large adult bluegill (Lepomis macrochirus), which are conventionally viewed as limnophils, were the second‐most abundant species in our samples and became increasingly abundant within the deep channel trough as flow decreased below the annual median. Clearly, those fishes exploit resources contained in the main channel and are, therefore, better viewed as opportunistic limno‐rheophils. Our results imply the existence of poorly understood food resources in the main channel. We conjecture that re‐creation of free‐flowing secondary channels and features that increase the production and transport of invertebrates in channels can help mitigate adverse effects of channel alteration and commercial shipping. Published in 2009 by John Wiley & Sons, Ltd.
Influence of habitat restoration on post‐emergence displacement of brown trout (Salmo truttaL.): A case study in a Northern Swedish stream
Authors: Palm Daniel , Lepori Fabio , Brännäs Eva 
Published: June 2009

AbstractDuring the 19th and 20th centuries, Swedish streams were channelized to facilitate the commercial transport of timber on water. Stream‐dwelling fish were affected by the consequent reduction in habitat quality. To mitigate the effects on salmonids, which sustain important recreational fisheries, many streams have been restored through the replacement of boulders into the channel since the early 1980s. However, the effects of restoration on salmonids remain poorly known. This study assesses the effect of habitat restoration on the post‐emergence displacement of brown trout (Salmo truttaL.) fry. Hatchery‐raised fry were released in a third‐order stream canalized for timber floating in northern Sweden, and the effect of restoration on displacement was assessed. The short‐term (24 h) displacement of trout fry was reduced from 10.1 to 2.3% of fry released following restoration. Water velocity accounted for 89.4% of the variation in fry displacement across years and sites. Post‐summer recruitment (the proportion of introduced juvenile trout remaining in the study reaches 60 days after the emergence) increased approximately three fold after restoration. These findings suggest that habitat restoration benefit trout populations through substantial reductions of fry displacement and possible contributions to juvenile recruitment. Copyright © 2009 John Wiley & Sons, Ltd.
In‐depth analysis of the satellite component of DVB‐SH: Scenarios, system dimensioning, simulations and field trial results
Authors: Bolea Alamanac Ana , Burzigotti Paolo , De Gaudenzi Riccardo , Liva Gianluigi , Pham Huu Nghia , Scalise Sandro 
Published: June 2009

AbstractThis paper presents a first‐step validation of the satellite component of DVB‐SH obtained by simulations and preliminary on‐field measurements. It is hoped that the results presented will be useful to system designers. The methodology and results presented are expected to be further consolidated by additional on‐field trials with recently launched and soon to be launched commercial S‐band GEO satellites dedicated to DVB‐SH. Copyright © 2009 John Wiley & Sons, Ltd.
Plasmon Coupling in Clusters Composed of Two‐Dimensionally Ordered Gold Nanocubes
Authors: Chen Huanjun , Sun Zhenhua , Ni Weihai , Woo Kat Choi , Lin Hai‐Qing , Sun Lingdong , Yan Chunhua , Wang Jianfang 
Published: June 2009

AbstractGold nanocubes are assembled into clusters of varying numbers and ordering on indium tin oxide substrates. The plasmon coupling in the clusters is studied with both dark‐field imaging and finite‐difference time‐domain calculations. Generally, as a cluster becomes larger and more asymmetric, it exhibits more scattering peaks towards longer wavelengths. The coupling of the vertically oriented dipole in the nanocube with its image dipole in the substrate generates two scattering peaks. One is fixed in energy and the other red‐shifts with increasing cluster size. The coupling of horizontally oriented dipoles among different nanocubes produces multiple scattering peaks at lower energies. Their positions and intensities are highly dependent on the number and ordering of nanocubes in the cluster. Au nanocubes in the clusters are further welded together by thermal treatment. The scattering peaks of the thermally treated clusters generally become sharper. The lower‐energy scattering peaks arising from dipolar oscillations are red‐shifted.
An actual test and FE analysis of a steel and concrete composite girder bridge exposed to fire
Authors: Takehara Kazuo , Imagawa Yusuke , Ohyama Osamu , Kurita Akimitsu 
Published: June 2009

AbstractIt has been reported that there are many examples of bridges damaged by fire due to traffic accidents, doubt fires and incendiary fires. When steel and concrete composite girder bridges are exposed to fire, it is necessary to verify the decrease in strength of the structural steel and the concrete. This paper describes the fire test setup for a steel and concrete composite girder bridge. The experimental results are discussed. Furthermore, a finite element analysis is carried out for the steel and concrete composite girder. Finally, the experimental and analytical results are compared.
Vibration factors of overhead sign structures mounted on highway bridges
Authors: Isha Hideo , Kitada Toshiyuki , Nishioka Keiji , Tokumasu Ken 
Published: June 2009

AbstractVibration due to traffic and wind causes fatigue damage to overhead sign structures mounted on highway bridges. Fatigue damage due to traffic vibration depends on the type and dimensions of the bridge, type of bearings, volume of traffic, location of overhead sign structures, etc. Factors influencing vibration are investigated in this study by carrying out frequency response analyses, with the parameters being the bridge, bridge pier and bearing types, the location of the sign structures and the weight of the electronic information panels. It can be seen that the damage increased after replacing the steel bearings by elastomeric bearings. These factors were verified through frequency response analyses. The results obtained in this study can be applied to the development of measures to prevent fatigue damage in overhead sign structures due to traffic vibration.
The Munkedal Bridge across the – River Örekil
Authors: Bengtsson Ola , Jansson Berndt , Sala David , Walser Peter 
Published: June 2009

AbstractThis 477 m long steel composite bridge is situated approximately 90 km north of Gothenburg and forms part of the 3000 km long European route E6, which connects Southern Sweden with Northern Norway. The 24.2 m wide steel composite deck is carried by a concrete arch spanning 225 m.
Passerelle sur Nanterre – spatial play of forces
Authors: Keil Andreas , Zimmermann Michael 
Published: June 2009

AbstractA footbridge was required as part of an urban development project in the Parisian financial district, La Défense. The construction is surrounded by the futuristic and modern architecture of the district, and a technically unique and attractive solution was required.Together with the architects DFA, Dietmar Feichtinger‐Architectes, Paris, and with the support of the client, EPASA, the ambitious, technically advanced bridge design was constructed and tailored to the specific urban conditions of the site.The following is an overview of the design concept, elements and calculations plus the fabrication and erection of the bridge.
Concrete overlay of movable steel orthotropic bridge decks
Authors: Boeters Ton , Braam René , Kolstein Henk , Romeijn Arie 
Published: June 2009

AbstractThe deck plate of steel orthotropic bridges is loaded in fatigue by traffic. Increases in both the traffic intensity and the magnitude of the wheel loads have caused premature fatigue cracking of steel bridges in the Netherlands, mostly on very busy motorways. Overlaying the steel orthotropic bridges with 50 mm of heavily reinforced concrete has proved to be a suitable way of reducing the steel stresses at critical locations in the steel deck plate of fixed bridges. This repair method adds no weight to the bridge because the asphalt is simply replaced by a concrete layer.The self‐weight of the overlay has to meet strict demands in the case of movable bridges because the wearing surface is only a few millimetres thick. Reducing the depth of the overlay might be effective provided the reinforcement is not susceptible to corrosion. Suitable types of reinforcement were researched in an earlier study in which the bending stiffness of the composite structure, the strength of the steel‐concrete interface layer and the bond between the reinforcement and the concrete were investigated in static experiments. The study of the fatigue behaviour of the composite section (concrete layer + steel deck plate) will be discussed in this article.
Altered specifications for the protection of Norwegian steel bridges and offshore structures against corrosion
Authors: Klinge Reidar 
Published: June 2009

AbstractThe ability of thermally sprayed zinc and aluminium to protect steel against corrosion has been exploited for almost 90 years. By further protecting the zinc and the aluminium with paint, some corrosion engineers have expected a service life of at least the sum of the life of the metal plus the life of the paint. Experiences and recent results from research activities have shown that aluminium further coated with thick paint can have a very short life when used in seawater or marine atmospheres.
Inelastic resistance of angle sections subjected to biaxial bending and normal forces
Authors: Vayas Ioannis , Charalampakis Aristotelis , Koumousis Vlasis 
Published: June 2009

AbstractSteel trusses and other structures with angle section members are usually designed by elastic methods. This may lead to uneconomical designs when these sections are subjected – besides the axial force – to biaxial bending arising not only from eccentric connections, but also from direct transverse loading. This paper provides a simple inelastic interaction formula, Eq. (14), as well as an enhanced inelastic formula, Eq. (27), for the combination of axial force and bending moments about the principal axes which may be used for angle cross‐sections of classes 1 or 2. The formulae do not always exhaust the full plastic cross‐sectional resistance but do lead to a more economical design of the section, especially when bending is dominant. The formulae cover only the design of the cross‐section and do not address stability considerations.