bluuebunny/crossref_metadata_2025_split huggingface dataset:
MBE growth and applications of cubic AlN/GaN quantum wells
Authors: As Donat J. , Mietze Christian 
Published: December 2012

AbstractMolecular beam epitaxy (MBE) of cubic group III‐nitrides is a direct way to eliminate polarization effects which inherently limit the performance of optoelectronic devices containing quantum well or quantum dot active regions. In this contribution, the latest achievement in the MBE of phase‐pure cubic GaN, AlN, and AlN/GaN quantum wells will be reviewed. The structural, optical, and electrical properties of state of the art cubic nitrides and AlGaN/GaN will be presented. We show that no polarization field exists in cubic nitrides and demonstrate intersubband absorption at 1.55 µm in cubic AlN/GaN superlattices. Comparing the experimental results with simulations based on an effective‐mass model the GaN/AlN conduction‐band offset is demonstrated to be higher than 1.2 eV. The best fit with the experimental data is achieved for a conduction‐band offset of 1.4 eV. Further the progress toward the fabrication of cubic GaN/AlGaN superlattices for terahertz applications will be discussed and our first experiments on cubic AlN/GaN resonant tunneling devices will be reported.
Improved thermal stability of antimony‐doped amorphous selenium film for X‐ray flat‐panel detectors
Authors: Chen Zexiang , Dong Miao , Li Chun , Shao Shengzi , Hu Tianyong , Kang Dequn 
Published: December 2012

AbstractAmorphous selenium (a‐Se) film is a promising photoconductive material for X‐ray flat‐panel detectors (FPD) application. However, a‐Se tends to be crystalline Se at near room temperature. This remarkable temperature sensitivity limits its practical application. To prevent the near‐room‐temperature crystallization of a‐Se film, we fabricate antimony (Sb)‐doped a‐Se films using a vacuum evaporation technique equipped with an in situ cooling trap. We experimentally demonstrate that the Sb doping improves the thermal stability of a‐Se film while possessing a similar X‐ray photoelectric conversion efficiency as the pure a‐Se film. After air annealing at 50 °C for 90 min, the X‐ray diffraction (XRD) results of the 4.1 at.% Sb‐doped a‐Se film shows no detectable crystallization diffraction peak. Upon applying an electric field of 10 V µm−1, such Sb‐doped a‐Se film exhibits dark current density below 1 nA cm−2, while under an X‐ray dosage of about 4 mGy, the annealed Sb‐doped a‐Se film shows a photocurrent density of more than 100 nA cm−2.
Prediction of high efficiency ZnMgO/Si solar cells suppressing carrier recombination by conduction band engineering
Authors: Knutsen K. E. , Schifano R. , Marstein E. S. , Svensson B. G. , Kuznetsov A. Yu. 
Published: December 2012

AbstractA significant conduction band offset appearing in n‐ZnO/p‐Si heterojunction solar cells is recognized as a serious roadblock to obtain high efficiency solar cells. By alloying with Mg, the conduction band in Zn1–xMgxO can be raised above that of Si, so that the influence of recombination centers at the interface between the two materials is strongly reduced, enabling high efficiency despite recombination velocities as high as 106 cm s−1. By simulating these phenomena we predict an optimal design of a n‐Zn0.8Mg0.2O/p‐Si solar cell resulting in high conversion efficiencies.
Tropical cyclone predictions over the Bay of Bengal using the high‐resolution Advanced Research Weather Research and Forecasting (ARW) model
Authors: Srinivas C. V. , Bhaskar Rao D. V. , Yesubabu V. , Baskaran R. , Venkatraman B. 
Published: December 2012

AbstractThe performance of the high‐resolution Advanced Research Weather Research and Forecasting (ARW) model for tropical cyclone prediction over the Bay of Bengal region of the northern Indian Ocean is assessed through study of 21 cyclone systems. Error metrics in the predicted fields of maximum sustained winds (MSW), central sea‐level pressure (CSLP) and the vector track position are computed by comparison with corresponding tropical cyclone estimations from the India Meteorological Department (IMD). From 65 sensitivity experiments for five severe cyclones the combination of Kain–Fritsch (KF) convection, Yonsei University (YSU) planetary boundary layer (PBL), LIN explicit microphysics and NOAH land surface schemes are found to provide the best simulations for intensity and track prediction. It has been found that the KF convection scheme gives higher convective warming with stronger vertical motions relative to other tested cumulus schemes and that the YSU scheme simulates more realistic winds in the inflow region than other tested PBL schemes. Results of simulations with the best physics for all 21 cyclones reveal that the model had a tendency to overestimate the intensity, with mean errors ranging from −2 to 15 hPa for CSLP, 1 to 22 m s−1for MSW corresponding to 24 to 72 h predictions. The mean vector landfall position errors are found to be 122 km at 12 h, 170 km at 24 h, 244 km at 48 h and 250 km at 72 h, and 67% of the landfall errors are less than 135 km, indicating fairly good forecasts. Further, the predictions are found to be best for northward moving cyclones followed by northwestward, westward and northeastward moving cyclones.
Improved variational analyses using a nonlinear humidity control variable
Authors: Ingleby N. B. , Lorenc A. C. , Ngan K. , Rawlins F. , Jackson D. R. 
Published: December 2012

AbstractA new humidity analysis variable has been successfully introduced into the Met Office's variational data assimilation system. The new variable uses a transformation consisting of a nonlinear normalization and a link with temperature increments that is a function of background (forecast) humidity. The normalization (which is the more important aspect) makes the new variable's errors more symmetrical and thus better represented by the variational cost function. As in the previous operational system, water vapour and cloud are combined into a single total water variable for the analysis step. The transform is now operational in both global and limited‐area systems. The forecast improvements—to the mass as well as the humidity fields—are largest in the Southern Hemisphere and there is a better fit of both background and analysis to humidity‐sensitive satellite channels. The results suggest that the transformation is particularly beneficial for the use of satellite data. The transform reduces the problem of negative humidities in the analysis which were more prevalent over the ocean.
Improved inapproximability results for counting independent sets in the hard‐core model
Authors: Galanis Andreas , Ge Qi , Štefankovič Daniel , Vigoda Eric , Yang Linji 
Published: December 2012

AbstractWe study the computational complexity of approximately counting the number of independent sets of a graph with maximum degree Δ. More generally, for an input graph and an activity , we are interested in the quantity defined as the sum over independent sets I weighted as . In statistical physics, is the partition function for the hard‐core model, which is an idealized model of a gas where the particles have non‐negligible size. Recently, an interesting phase transition was shown to occur for the complexity of approximating the partition function. Weitz showed an FPAS for the partition function for any graph of maximum degree Δ when Δ is constant and . The quantity is the critical point for the so‐called uniqueness threshold on the infinite, regular tree of degree Δ. On the other side, Sly proved that there does not exist efficient (randomized) approximation algorithms for , unless , for some function . We remove the upper bound in the assumptions of Sly's result for , that is, we show that there does not exist efficient randomized approximation algorithms for all for and . Sly's inapproximability result uses a clever reduction, combined with a second‐moment analysis of Mossel, Weitz and Wormald which prove torpid mixing of the Glauber dynamics for sampling from the associated Gibbs distribution on almost every regular graph of degree Δ for the same range of λ as in Sly's result. We extend Sly's result by improving upon the technical work of Mossel et al., via a more detailed analysis of independent sets in random regular graphs. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 45, 78–110, 2014
Bounds for algebraic gossip on graphs
Authors: Borokhovich Michael , Avin Chen , Lotker Zvi 
Published: December 2012

ABSTRACTWe study the stopping times of gossip algorithms for network coding. We analyze algebraic gossip (i.e., random linear coding) and consider three gossip algorithms for information spreading: Pull, Push, and Exchange. The stopping time of algebraic gossip is known to be linear for the complete graph, but the question of determining a tight upper bound or lower bounds for general graphs is still open. We take a major step in solving this question, and prove that algebraic gossip on any graph of sizenisO(Δn) where Δ is the maximum degree of the graph. This leads to a tight bound offor bounded degree graphs and an upper bound ofO(n2) for general graphs. We show that the latter bound is tight by providing an example of a graph with a stopping time of. Our proofs use a novel method that relies on Jackson's queuing theorem to analyze the stopping time of network coding; this technique is likely to become useful for future research. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 45, 185–217, 2014
Context data distribution with quality guarantees for Android‐based mobile systems
Authors: Corradi Antonio , Fanelli Mario , Foschini Luca , Cinque Marcello 
Published: December 2012

ABSTRACTIn the last years, context awareness, namely the provisioning of the current execution context to the application level, has received an increasing attention up to becoming a core capability in next generation mobile scenarios. Context awareness intrinsically forces a continuous delivery of context data to resource‐constrained mobile devices, such as mobile phones and personal digital assistants, to allow application adaptation, and that can become too severe a constraint even for modern platforms (Android, iOS, etc.). This paper focuses on the realization of a context data distribution support for Android‐based mobile phones with guaranteed quality levels on the context data delivery time. Android, notwithstanding its great potential, puts harsh constraints on the implementation of specific context distribution primitives, thus preventing the realization of a wide set of significant deployment scenarios. At this stage, we face that a large campaign of tests are necessary. We have collected main experimental results in a real testbed to highlight noteworthy details on the runtime performance obtainable with a real Android deployment. Copyright © 2012 John Wiley & Sons, Ltd.
Adverse Life Events and Emotional and Behavioural Problems in Adolescence: The Role of Coping and Emotion Regulation
Authors: Flouri Eirini , Mavroveli Stella 
Published: December 2012

AbstractWe tested whether emotion regulation (cognitive reappraisal and expressive suppression) and coping (distraction, avoidance, support seeking and active coping) mediate or moderate the association between change in life stress (change in number of adverse life events) and change in adolescent problem behaviour. We used prospective and retrospective longitudinal data from a community sample. We measured change in problem behaviour as emotional and behavioural problems at Time 2 controlling for emotional and behavioural problems at Time 1, a year earlier. We measured change in life stress as life stress between Times 1 and 2, controlling for total previous life stress (before Time 1). Neither coping nor emotion regulation mediated the association between change in life stress and change in problem behaviour. Avoidance and expressive suppression were related to an increase in problem behaviour. Only cognitive reappraisal moderated the effect of increase in life stress on worsening of problem behaviour, suggesting that, as expected, cognitive reappraisal was a protective factor. In adolescents who reported they habitually reappraise, the association between change in life stress and change in emotional and behavioural problems was non‐significant. Copyright © 2012 John Wiley & Sons, Ltd.
Charge Transfer at Junctions of a Single Layer of Graphene and a Metallic Single Walled Carbon Nanotube
Authors: Paulus Geraldine L. C. , Wang Qing Hua , Ulissi Zachary W. , McNicholas Thomas P. , Vijayaraghavan Aravind , Shih Chih‐Jen , Jin Zhong , Strano Michael S. 
Published: December 2012

AbstractJunctions between a single walled carbon nanotube (SWNT) and a monolayer of graphene are fabricated and studied for the first time. A single layer graphene (SLG) sheet grown by chemical vapor deposition (CVD) is transferred onto a SiO2/Si wafer with aligned CVD‐grown SWNTs. Raman spectroscopy is used to identify metallic‐SWNT/SLG junctions, and a method for spectroscopic deconvolution of the overlapping G peaks of the SWNT and the SLG is reported, making use of the polarization dependence of the SWNT. A comparison of the Raman peak positions and intensities of the individual SWNT and graphene to those of the SWNT‐graphene junction indicates an electron transfer of 1.12 × 1013 cm−2 from the SWNT to the graphene. This direction of charge transfer is in agreement with the work functions of the SWNT and graphene. The compression of the SWNT by the graphene increases the broadening of the radial breathing mode (RBM) peak from 3.6 ± 0.3 to 4.6 ± 0.5 cm−1 and of the G peak from 13 ± 1 to 18 ± 1 cm−1, in reasonable agreement with molecular dynamics simulations. However, the RBM and G peak position shifts are primarily due to charge transfer with minimal contributions from strain. With this method, the ability to dope graphene with nanometer resolution is demonstrated.
Correct Spectral Conversion between Surface‐Enhanced Raman and Plasmon Resonance Scattering from Nanoparticle Dimers for Single‐Molecule Detection
Authors: Lee Kyuwan , Irudayaraj Joseph 
Published: December 2012

AbstractSimultaneous measurement of surface‐enhanced Raman scattering (SERS) and localized surface plasmon resonance (LSPR) in nanoparticle dimers presents outstanding opportunities in molecular identification and in the elucidation of physical properties, such as the size, distance, and deformation of target species. SERS–LSPR instrumentation exists and has been used under limited conditions, but the extraction of SERS and LSPR readouts from a single measurement is still a challenge. Herein, the extraction of LSPR spectra from SERS signals is reported and a tool for measuring the interparticle distance from Raman enhancement data by the standardization of the SERS signal is proposed. The SERS nanoruler mechanism incorporates two important aspects (the LSPR scattering peak shift and the Raman shift for measuring interparticle distance), and signifies their exact one‐to‐one correspondence after spectral correction. The developed methodology is applied to calculate the interparticle distance between nanoparticle dimers from SERS signals, to detect and quantify DNA at the single‐molecule level in a base‐pair‐specific manner. It is also shown that the SERS nanoruler concept can be used in structural analysis for the specific detection of the interaction of immunoglobulin G (IgG) with its target from bianalyte Raman signals with identical shaping at single‐molecule resolution. The SERS profile shaping approach not only offers a new detection mechanism for single molecules, but also has excellent potential for studying protein interactions and the intracellular detection of mRNA.
Mechanical Exfoliation and Characterization of Single‐ and Few‐Layer Nanosheets of WSe2, TaS2, and TaSe2
Authors: Li Hai , Lu Gang , Wang Yanlong , Yin Zongyou , Cong Chunxiao , He Qiyuan , Wang Lu , Ding Feng , Yu Ting , Zhang Hua 
Published: December 2012

AbstractSingle‐ and few‐layer transition‐metal dichalcogenide nanosheets, such as WSe2, TaS2, and TaSe2, are prepared by mechanical exfoliation. A Raman microscope is employed to characterize the single‐layer (1L) to quinary‐layer (5L) WSe2 nanosheets and WSe2 single crystals with a laser excitation power ranging from 20 μW to 5.1 mW. Typical first‐order together with some second‐order and combinational Raman modes are observed. A new peak at around 308 cm−1 is observed in WSe2 except for the 1L WSe2, which might arise from interlayer interactions. Red shifting of the A1g mode and the Raman peak around 308 cm−1 is observed from 1L to 5L WSe2. Interestingly, hexagonal‐ and monoclinic‐structured WO3 thin films are obtained during the local oxidation of thinner (1L–3L) and thicker (4L and 5L) WSe2 nanosheets, while laser‐burned holes are found during the local oxidation of the WSe2 single crystal. In addition, the characterization of TaS2 and TaSe2 thin layers is also conducted.
A New Double Calcium Treatment Method for Clean Steel Refining
Authors: Deng Zhiyin , Zhu Miaoyong 
Published: December 2012

AbstractA new double calcium treatment method was proposed according to industrial experiment. In the new process, the evolution of inclusion was analyzed and the controlling standard of T.[Ca]/T.[O] ratio for calcium treatment was discussed. The results show that good castability with low calcium content about 12 ppm was obtained by this method, and the inclusion grade of D type thin series decreases from 1.5 to 1.0 in final product. CaOMgOAl2O3 system inclusions containing small amount of CaO are mainly presented after LF refining. After the 1st calcium treatment, most inclusions are in the liquid region with low melting point and the MgO content decreases obviously. After the 2nd calcium treatment, the distribution of inclusion composition is more concentrated compared with the 1st calcium treatment, and the MgO content decreases further with the inclusion composition very close to CaOAl2O3 system and almost all in liquid region. In order to get a good calcium treatment result, T.[Ca]/T.[O] ratio should be controlled above 0.91, and the ratio between 0.91 and 1.25 is suitable in present work.
Assessment of the continuous wavelet transform in the modal parameters estimation of 2MM and 3MM systems
Authors: Loussifi Hichem , Nouri Khaled , Benhadj Braiek Naceur 
Published: December 2012

AbstractIn this paper, our interest is in the identification of a special class of electromechanical systems: a motor‐drive system using the continuous wavelet transform method. This new modal analysis technique is evaluated in terms of its accuracy in the estimation of the modal parameters, its ability in distinguishing and separating several modes, its resistance to noisy conditions, and its usability with different excitations types. For this investigation, two models of elastic drive systems are considered: the two‐mass model and the three‐mass model. Simulation results of the study are presented, and the effectiveness of the developed identification method is discussed. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
An investigation on attenuation UCT with wave paths enhancement for breast ultrasound
Authors: Sanpanich Arthorn , Hamamoto Kazuhiko , Pintavirooj Chuchart 
Published: December 2012

AbstractBreast cancer is one of the most prevalent health hazards in women all over the world. An annual screening test using a diagnostic ultrasound seems to be an appropriate method to handle this physical threat. In this paper, we propose the use of a two‐dimensional reflection‐mode ultrasonic tomography system for a general breast ultrasound investigation enhanced by an echo wave path using a wave reflecting plate. Our virtual imaging setup system is composed of a 128‐element conventional linear array transducer placed on the top of a water bath and a wave reflector attached around this setup. The shape of the wave reflector was designed as a single plate shape, rectangular shape and curve shape. For projection data, we estimate a line integral insonifying data by using a classical integration slope of attenuation coefficient method in which its derivative is independent of transmittance, reflectance, and noise. By imaging a virtual breast phantom model, the reconstruction results obtained from an iterative algebraic reconstruction technique (ART) algorithm show a promising image. The image is not only indicates a tissue characterization from quantitative attenuation data, but also restores an area covered by hard tissue due to an increased wave path direction from our nonrotational imaging system. These results encourage us to implement our concept with a clinical study in the near future. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Validation for capacitance national standard based on long‐term monitoring results of standard capacitors
Authors: Domae Atsushi , Sakamoto Norihiko , Kaneko Nobu‐Hisa 
Published: December 2012

AbstractThe National Metrology Institute of Japan (NMIJ) has developed a new national standard of capacitance (capacitance standard) and also established its traceability system. Calibration and measurement capabilities (CMCs) of the new capacitance standard were validated in the international comparison with foreign National Metrology Institutes (NMIs). However, it is not easy to frequently carry out such international comparison which requires close coordination among the participating NMIs. In order to maintain high reliability of the capacitance standard, therefore, it is important to verify its CMCs during the period when the comparisons are not carried out. To verify the CMCs, NMIJ has been performing long‐term monitoring of standard capacitors and of capacitance differences among a number of standard capacitors. In this paper, we will report the details of the long‐term monitoring of the standard capacitor, the long‐term monitoring results of capacitance differences, and verification of CMCs based on the analysis of these results. Validation of the CMCs based on results of monitoring conducted after the massive earthquake on March 11, 2011 is also described as specific case. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Multiobjective particle swarm optimization for a novel fuzzy portfolio selection problem
Authors: Wang Bo , Watada Junzo 
Published: December 2012

AbstractOn the basis of the portfolio selection theory, this paper proposes a novel fuzzy multiobjective model that can evaluate investment risk properly and increase the probability of obtaining an expected return. In building this model, fuzzy value‐at‐risk (VaR) is used to evaluate the exact future risk in terms of loss. The VaR can directly reflect the greatest loss of a selection case under a given confidence level. Conversely, variance, the measure of the spread of a distribution around its expected value, is utilized to make the selection more stable. This model can provide investors with more significant information for decision making. To solve this model, an improved Pareto‐optimal‐set‐based multiobjective particle swarm optimization (IMOPSO) algorithm is designed to obtain better solutions in the Pareto front. The proposed model and algorithm are exemplified by specific numerical examples. Furthermore, comparisons are made between IMOPSO and other existing approaches. Experiments show that the model and algorithm are effective in solving the multiobjective portfolio selection problem. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.