bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling of the effects of conduction band fluctuations caused by nitrogen clustering in GaInNAs materials
Authors: Sun Xiao , Rorison Judy M. 
Published: March 2011

AbstractIt has been observed experimentally that the band edge photoluminescence of GaInNAs Quantum well (QW) materials is broadened resulting from band‐tailing, localised states or conduction band edge fluctuations. In this paper we develop a model for N compositional fluctuations causing conduction band edge fluctuations which localise the electrons into the resulting quantum dots (QDs). The electron dynamics in the QDs and QW states are examined using a rate equation approach and the carrier populations presented as a function of barrier height and temperature. This mechanism could lead to broad gain in GaInAsN QW structures which could be useful for broad band SOAs for optical communications (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical field and temperature effects in 2D‐2D resonant tunneling diodes based on cubic InGaN/AlGaN
Authors: Bhouri A. , Yahyaoui N. , Debbichi M. , Mejri H. , Lazzari J.‐L. , Said M. 
Published: March 2011

AbstractThe present work reports on a study of the electron transport in a 2D‐2D resonant tunneling diode based on strained Al0.3Ga0.7N/In0.2Ga0.8N/Al0.3Ga0.7N quantum wells embedded between relaxed n‐Al0.15Ga0.85N/strained In0.2Ga0.8N emitter and collector contacts. The epilayers are assumed to be with cubic crystal structure to avoid the effects of spontaneous and piezoelectric polarization fields. The aluminum composition in both the injector and collector contacts is taken relatively weak, but large band offsets are achieved at the boundary of the preconfinement wells. The heterostructure modeled is aimed to operate at high biases and at elevated temperatures. Calculations of the band edges and quantum‐bound states were made using a self‐consistent solver of the Schrödinger and Poisson equations. Obtained results revealed: (i) a charge transfer occurs due to a resonant tunneling through a double barrier, (ii). A special attention is paid to the effects of resonant tunneling and thermal activation on the charge transfer. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of InxAl1‐xN/ZnO and InxGa1‐xN/ZnO strained quantum well lasers
Authors: Djellal A. , Kadri A. , Gil B. , Bretagnon T. , Zitouni K. 
Published: March 2011

AbstractWe perform a theoretical study of InxAl1‐xN/ZnO and InxGa1‐xN/ZnO strained Quantum Well (QW) Lasers oriented along the non‐polar A‐plane axis. In order to determine the energy band‐offsets in both heterostructures as a function of alloy composition, we use the ab‐initio method to compute the total energies of these systems. Then, we use the k·P method within the envelop function formalism to study conduction and valence energy subband structures for various alloy compositions and well widths. Finally, we calculate the Laser gain for such strained QW heterostructures. Our results show that type I heterostructures can be made with two kind of systems: InxGa1‐xN/InxAl1‐xN/ZnO and InxGa1‐xN/InyGa1‐yN/ZnO where InxGa1‐xN is the QW in both cases. These heterostructures are lattice‐matched along A‐plane axis at x=32% in InxAl1‐xN/ZnO and x=17% in InxGa1‐xN/ZnO. However, because of the anisotropy of the built‐in strain at the interface, they are still slightly compressively strained along c‐axis. Pure tensile strain or pure compressive can be achieved only at In‐content values well below or well above these critical values, respectively. Our results are compared with various theoretical and experimental values, and quite good agreement is found. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DFT calculation for green chemical catalyst with hydroxyl group supported on S‐terminated GaN(0001)
Authors: Yokoyama Mami , Murayama Tatsunori , Tsukamoto Shiro , Ishii Akira 
Published: March 2011

AbstractA novel function of nitried‐based semiconductor is successfully developed for organic synthesis, in which palladium supported on the surface of S‐terminated GaN(0001) serves as a unique green chemical catalyst. In this study we determined the structure of OH on Pd‐catalyst supported on Sterminated GaN(0001) surface by means of the density functional theory (DFT) within a Local Density Approximation (LDA). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scalable, asynchronous, distributed eigen monitoring of astronomy data streams
Authors: Bhaduri Kanishka , Das Kamalika , Borne Kirk , Giannella Chris , Mahule Tushar , Kargupta Hillol 
Published: March 2011

AbstractIn this paper, we develop a distributed algorithm for monitoring the principal components (PCs) for next generation of astronomy petascale data pipelines such as the Large Synoptic Survey Telescopes (LSST). This telescope will take repeated images of the night sky every 20 s, thereby generating 30 terabytes of calibrated imagery every night that will need to be co‐analyzed with other astronomical data stored at different locations around the world. Event detection, classification, and isolation in such data sets may provide useful insights to unique astronomical phenomenon displaying astrophysically significant variations: quasars, supernovae, variable stars, and potentially hazardous asteroids. However, performing such data mining tasks is a challenging problem for such high‐throughput distributed data streams. In this paper, we propose a highly scalable and distributed asynchronous algorithm for monitoring the PCs of such dynamic data streams and discuss a prototype web‐based system PADMINI (Peer‐to‐Peer Astronomy Data Mining) which implements this algorithm for use by the astronomers. We demonstrate the algorithm on a large set of distributed astronomical data to accomplish well‐known astronomy tasks such as measuring variations in the fundamental plane of galaxy parameters. The proposed algorithm is provably correct (i.e., converges to the correct PCs without centralizing any data) and can seamlessly handle changes to the data or the network. Real experiments performed on Sloan Digital Sky Survey (SDSS) catalogue data show the effectiveness of the algorithm. © 2011 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 2011
Application of 3 × 3 transformation matrix in the correction of three‐dimensional AFM image tilts through coordinate transformation
Authors: Adebayo Adedayo S. , Zhao Xue‐zeng , Wang Fei , Zhou Faquan 
Published: March 2011

AbstractIn atomic force microscopy (AFM), it is difficult to maintain samples in a perfect horizontal position on the piezoelectric stage of an AFM to obtain accurate measurement of surface features and to enhance the visual effect of topographic images. Correction of the tilted image therefore requires the use of an appropriate 3 × 3 transformation matrix which will transform the coordinates to simultaneously correct the tilt in both the x‐and y‐axes due to the three‐dimensional nature of AFM images. In this study, application of transformation matrix in three‐dimensions for the simultaneous correction of image tilts in both the x‐ and y‐axes by the method of coordinate transformation in three‐dimensions is presented. Application of the matrix in simultaneously correcting tilts in the x‐ and y‐axes of an AFM image is implemented by simulating an image assuming there are tilts in both the x‐ and y‐axes. Results of features measurement after transforming the coordinates with the matrix show the efficacy of the matrix. This will conveniently replace the line‐by‐line analysis done to remove tilts in AFM, which has been the practice long before now. It also has the advantage of correcting images by simultaneously removing tilts in both the x‐ and y‐axes as a veritable replacement of having to separately correcting tilts in images. This matrix can be used to transform coordinates in three‐dimensions to obtain accurate step height and linewidth in AFM images. SCANNING 33: 94–98, 2011. © 2011 Wiley Periodicals, Inc.
VM aware journaling: improving journaling file system performance in virtualization environments
Authors: Huang Ting‐Chang , Chang Da‐Wei 
Published: March 2011

SUMMARYJournaling file systems, which are widely used in modern operating systems, guarantee file system consistency and data integrity by logging file system updates to a journal, which is a reserved space on the storage, before the updates are written to the data storage. Such journal writes increase the write traffic to the storage and thus degrade the file system performance, especially in full data journaling, which logs both metadata and data updates. In this paper, a new journaling approach is proposed to eliminate journal writes in server virtualization environments, which are gaining in popularity in server platforms. Based on reliable hardware subsystems and virtual machine monitor (VMM), the proposed approach eliminates journal writes by retaining journal data (i.e. logged file system updates) in the memory of each virtual machine and ensuring the integrity of these journal data through cooperation between the journaling file systems and the VMM. We implement the proposed approach in Linux ext3 in the Xen virtualization environment. According to the performance results, a performance improvement of up to 50.9journaling approach of ext3 due to journal write elimination. In metadata‐write dominated workloads, this approach could even outperform the metadata journaling approaches of ext3, which do not guarantee data integrity. These results demonstrate that, on virtual servers with reliable VMM and hardware subsystems, the proposed approach is an effective alternative to traditional journaling approaches. Copyright © 2011 John Wiley & Sons, Ltd.
Realizing BF Long Campaign Life and Stable Running by Burden Distribution Adjustment
Authors: Ce Shang , Jianwei Zhu , Yanhui Zhang 
Published: March 2011

AbstractAdjusting Burden distribution is one of the most important and effective operations. In terms of fixed equipment, charging materials and blowing regulation, the inner gas flow utilization could be improved by adjusting the burden distribution to achieve a well‐state skull, good blast furnace (BF) performance and long campaign life. The No.1 BF (the effective volume is 3200 m3) was equipped with a bell‐less top, cast iron cooling staves in the hearth and copper cooling plates from the belly to the lower shaft respectively. Although the satisfied indexes have been reached since blow on, the fluctuation caused by the skull dropping off happened several times. This resulted in the lining temperatures varying greatly, the coke ratio increasing and the product quality deteriorating. It is considered the main reason for the operation regulation not matching the varied conditions with deteriorating materials and continuous lower temperatures of hot metal etc. A type of effective charging mode is introduced in the paper to complete the BF long‐term stable running and long operation.
CFD Modeling and Analysis of The Flow, Heat Transfer and Mass Transfer in a Blast Furnace Hearth
Authors: Guo Bao‐Yu , Yu Ai‐Bing , Zulli Paul , Maldonado Daniel 
Published: March 2011

AbstractUnderstanding the complex phenomena in the BF hearth is essential to increasing furnace productivity and to extending furnace campaign. Numerical modeling provides a cost‐effective tool to obtain such knowledge. We have developed several continuum‐based mathematical/numerical models to simulate the flow, heat transfer and mass transfer in the lower part of BF and in the hearth. These models have generated an improved insight into the mechanisms for liquid drainage efficiency, lining erosion and wall protection in BF hearth under operational conditions. The current paper provides an overview of these studies, as well as dealing with three specific aspects: (a) Gas flow and pressure on the liquid surface, and its effect on the drainage characteristics; (b) Flow and temperature distributions of liquid iron in the hearth, and the temperature distribution in the refractories; and (c), Titania injection to form Ti(C,N)‐rich scaffolds on the hearth refractory surface, to protect the hearth from erosion.
The political economy of nuclear energy
Authors: Hultman Nathan E. 
Published: March 2011

AbstractDespite a history of problems, nuclear power is being discussed as a potentially useful and appropriate electricity source for both developed and developing countries. For example, expanding nuclear power's share of electricity portfolios could reduce, relative to a fossil‐intensive baseline, greenhouse gas emissions that lead to climate change. Moreover, nuclear power has long been advocated as a route to energy security and indeed, for many of the nuclear nations, it could decrease dependence on oil imports under certain technological scenarios, such as an increased use of plug‐in hybrid vehicles. The nuclear industry argues that a new generation of reactors, representing a refinement of existing technology, will enable this expansion. Because of these new motivations, some advocates have applied the term ‘nuclear renaissance’ to the possibility of a rapid expansion of nuclear power to satisfy a projected growing global electricity demand, while simultaneously reducing greenhouse gas emissions. This article outlines the primary challenges that this unique energy source presents for such a renaissance. Like other technologies, nuclear is situated in a social and political–economic matrix that influences its evolution. After reviewing the basic aspects of the technology, I discuss the history of the existing nuclear fleet, then address the prospects for advanced and next‐generation nuclear technologies. I review the economics of nuclear power as it is currently deployed and the potential changes to these economics under potential future development. In examining future scenarios, I explore the effects of national and international policies on nuclear energy. WIREs Clim Change 2011 2 397–411 DOI: 10.1002/wcc.113This article is categorized under:

The Carbon Economy and Climate Mitigation > Policies, Instruments, Lifestyles, Behavior
The Carbon Economy and Climate Mitigation > Future of Global Energy
Policy and Governance > Multilevel and Transnational Climate Change Governance
Quasi‐optimal power allocation based on ergodic capacity for wireless relay networks
Authors: Lin Fei , Luo Tao , Jiang Tao 
Published: March 2011

ABSTRACTHalf‐duplex amplify‐and‐forward (AF) transmissions may result in insufficient use of degrees of freedom if they always use the cooperative mode regardless of the fading states. In this paper, we investigate the conditions under which cooperation offers better performance and the corresponding optimal power allocation during cooperation. Specifically, we first derive an expression of ergodic capacity and its upper bound for an AF cooperative communication system with n relay nodes. Secondly, we propose a novel quasi‐optimal power allocation (QOPA) scheme to maximize the upper bound of the derived ergodic capacity. For the QOPA scheme, the cooperative mode is only adopted when the channel gain of source‐to‐destination is worse than that of relay‐to‐destination. Moreover, we analyze the performance of the system with QOPA scheme when the relay moves, which is based on the random direction model, in a single‐relay wireless network. For a multi‐relay AF network, we compare the ergodic capacity and symbol error rate, corresponding to the proposed QOPA and equal power allocation schemes, respectively. Extensive simulations were conducted to validate analytical results, showing that both ergodic capacity and symbol error rate of the system with QOPA scheme are better than those of the system with equal power allocation scheme in a multi‐relay AF network. Copyright © 2011 John Wiley & Sons, Ltd.
The predictability of above roof wind resource in the urban roughness sublayer
Authors: Millward‐Hopkins J.T. , Tomlin A.S. , Ma L. , Ingham D. , Pourkashanian M. 
Published: March 2011

ABSTRACTThe predictability of above roof wind resource (three‐dimensional mean wind speed) in the roughness and inertial sublayers over idealized urban arrays has been studied using data previously obtained from wind tunnel experiments and a validated large eddy simulation. Both uniform arrays and arrays of heterogeneous heights (representing suburban and more complex urban areas, respectively) were considered. Firstly, the spatial variation of the wind resource within the roughness sublayers over the more complex heterogeneous array was assessed, and suggestions for ideal rooftop turbine placement in this type of geometry were made. It was found that the spatially averaged wind profile can be considered to be a lower bound for the available wind resource at the most viable turbine locations. Secondly, available methods of estimating spatially averaged wind profiles above urban‐like surfaces were discussed, and bearing in mind the uncertainties inherent in these methods, a typical wind resource prediction methodology was followed. Significant uncertainties were found to occur at each stage of the prediction, but it was found that the errors occurring because of the typical methods used to parameterize surface aerodynamics are potentially the most significant. Therefore, to increase the accuracy of these prediction methodologies, it is necessary to improve the methods of parameterizing surface aerodynamics and estimating roughness sublayers spatial averages for urban‐like surfaces. Copyright © 2011 John Wiley & Sons, Ltd.
Variationen modulo 4–4+, 4+3–3+4–, 4–5+, 5–4+4–5+4–4+ bei Seltenerdcarbidhalogeniden
Authors: Mattausch Hansjürgen , Simon Arndt 
Published: March 2011

AbstractThe new compounds Pr8(C2)4Cl5 (1), Pr14(C2)7Cl9 (2), Pr22(C2)11Cl14 (3), Ce2(C2)Cl (4), La2(C2)Br (5), Ce2(C2)Br (6), Pr2(C2)Br (7), Ce18(C2)9Cl11 (8), and Ce26(C2)13Cl16 (9) were prepared by heating mixtures of LnX3, Ln and carbon or in an alternatively way LnX3, and “Ln2C3–x” in appropriate amounts for several days between 750 and 1200 °C. The crystal structures were investigated by X‐ray powder analysis (5–7) and/or single crystal diffraction (1–4, 8, 9). Pr8(C2)4Cl5 crystallizes in space group P21/c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) Å, β = 103.94(1) °, Pr14(C2)7Cl9 in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) Å, β = 104.00(3) °, Pr22(C2)11Cl14 in P21/c with a = 7.612(2), b = 46.127(9), c = 6.761(1) Å, β = 103.92(3) °, Ce2(C2)2Cl in C2/c with a = 14.573(3), b = 4.129(1), c = 6.696(1) Å, β = 101.37(3) °, La2(C2)2Br in C2/c with a = 15.313(5), b = 4.193(2), c = 6.842(2) Å, β = 100.53(3) °, Ce2(C2)2Br in C2/c with a = 15.120(3), b = 4.179(1), c = 6.743(2) Å, β = 101.09(3) °, Pr2(C2)2Br in C2/c with a = 15.054(5), b = 4.139(1), c = 6.713(3) Å, β = 101.08(3) °, Ce18(C2)9Cl11 in P$\bar{1}$ with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) Å,α = 88.90(3) °, β = 80.32(3) °, γ = 76.09(3) °, and Ce26(C2)13Cl16 in P21/c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) Å, β = 103.98(3) ° The crystal structures are composed of Ln octahedra centered by C2 dumbbells. Such Ln6(C2)‐octahedra are condensed into chains which are joined into undulated sheets. In compounds 1–4 three and four up and down inclined ribbons alternate (4+4–, 4+3–3+4–, 4+4–3+4–4+3–), in compounds 8 and 9 four and five (4+5–, 5+4–4+5–4+4–), and in compounds 4–7 one, one ribbons (1+1–) are present. The Ln‐(C2)‐Ln layers are separated by monolayers of X atoms.
Obesity is a Predictor of Morbidity in 1,629 Patients Who Underwent Adrenalectomy
Authors: Kazaure Hadiza S. , Roman Sanziana A. , Sosa Julie A. 
Published: March 2011

AbstractBackgroundWe examined the impact of obesity on 30‐day outcomes of adrenalectomy using a multi‐institutional database.MethodsPatients who underwent adrenalectomy in 2005–2008 according to the American College of Surgeons‐National Surgical Quality Improvement Project (ACS‐NSQIP) data set were grouped by body mass index (BMI): normal weight (BMI = 18.5–24.9 kg/m2), overweight (BMI = 25.0–29.9 kg/m2), obese (BMI = 30.0–34.9 kg/m2), and morbidly obese (BMI ≥ 35 kg/m2). Outcomes of the higher BMI groups were compared to those of the normal BMI group using χ2, analysis of variance (ANOVA), and multivariate regression.ResultsThere were 1,629 patients in the study: 22% were normal weight, 31% overweight, 22.2% obese, and 24.7% morbidly obese. Compared to normal‐weight patients, obese and morbidly obese patients had a 12.5 and 16.7% increase in operation times (129 vs. 145 and 150 min, respectively, p ≤ 0.01) and sustained more wound complications (0.2 vs. 0.4 and 1.2%, p < 0.001), including superficial and deep wound infections (p < 0.001 and p < 0.01, respectively). Morbid obesity independently predicted overall complications (odds ratio [OR] 2.9, 95% confidence interval [CI]: 1.7–5.7), wound complications (OR 6.1, 95% CI: 2.0–18.9), and septic complications (OR 3.1, 95% CI: 1.1–8.8). Obesity independently predicted longer total time in the operating room (p < 0.006). There were no differences in rates of reoperation and length of hospital stay by BMI category.ConclusionObesity is an independent risk factor that needs to be considered in surgical decisions regarding adrenalectomy. Morbidly obese adrenalectomy patients are particularly at risk for wound and septic complications.
Aggregation and Adsorption at the Air–Solution Interface of the Cetyltrimethyl Ammonium Tosylate With Two Poly(oxyethylene)–Poly(oxypropylene)–Poly(oxyethylene) Block Copolymers Aqueous Mixtures
Authors: Brigante Maximiliano , Schulz Pablo C. 
Published: March 2011

AbstractThe aqueous mixed systems (EO76PO30EO76) (TBCP8400)—cetyltrimethyl ammonium tosylate (CTAT), and (EO97PO69EO97) (TBCP12600)—CTAT were studied to determine both the bulk aggregation and the adsorbed monolayer at the air/water interface. Results were interpreted with the pseudophase separation model plus the regular solution theory for aggregates and monolayers. The behavior is different for TBCP8400–CTAT and TBCP12600–CTAT mixtures, but it is strongly non‐ideal in both cases. In bulk, TBCP8400–CTAT mixtures produce aggregates more close to CTAT micelles having TBCP8400 as a solubilizate than the inverse. At low CTAT content, the interaction is repulsive becoming attractive at high TBCP8400 content. The TBCP12600–CTAT aggregates strongly differ from the structure of both pure component micelles, and the interaction is always repulsive. In both cases, the interaction seems not to be cooperative but gradual. CTAT effect on copolymers aggregates seems to be more similar to that of a zwitterionic surfactant than to that of an ionic one. However, CTAT is not included in the aggregates as an ion pair, as revealed by the ionization degree results. It seems that cetyltrimethyl ammonium and tosylate ions have different effects on aggregates which in part are opposite. The adsorbed monolayers also show different behavior. In TBCP8400–CTAT system, the monolayer is mainly a CTAT one with inclusion of TBCP8400 as a monolayer‐soluble impurity. However, the inclusion of the non‐ionic surfactant alters the structure of the monolayer, which differs from that of the pure CTAT one. The area per adsorbed molecule (A0) is systematically higher than the ideal and computed ones. The system TBCP12600–CTAT shows a monolayer composition which is almost the same that the overall surfactant mixture composition, and the monolayer structure differs from both the pure‐TBCP12600 and the pure‐CTAT monolayers ones. The experimental A0 values are systematically lower than the ideal and the computed ones. Then, in both cases the A0 values for the pure components do not remain invariable in the mixed monolayer. The phenomenon is interpreted on the basis of the conformation of the copolymers adsorbed at the air/solution interface.