bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electronic and magnetic structure of carbides RRh3C
Authors: Djermouni Mostefa , Kacimi Salima , Zaoui Ali 
Published: March 2011

AbstractAb initio calculations are performed to study the electronic and magnetic properties of the cubic inverse perovskite RRh3C (R = rare earth) compounds. In this work, we used the accurate augmented plane‐wave plus local orbital method to find the equilibrium structural parameters and to determine the magnetic stability of each material. We investigated the electronic structure with the spin‐orbit interaction and on‐site Coulomb potential for the R‐derived 4f orbitals to obtain the correct ground state of RRh3C. The exchange interaction between local f electrons and conduction electrons play an important role in the heavy fermions characters. The fully relativistic band structure scheme shows that spin‐orbit coupling splits the 4f states into many manifolds. We confirm the results of recently synthesized cubic phases [Phys. Rev. B 80, 224404 (2009)].
Optical and theoretical investigations of V2+ ion in GaN
Authors: Souissi Hajer , Souissi Mnawer , Dammak Mohamed , Chine Zied , Kammoun Souha , El Jani Belgacem 
Published: March 2011

AbstractThe infrared luminescence of vanadium‐doped gallium nitride (GaN:V) grown by metalorganic vapour phase epitaxy technique (MOVPE) on SiN‐treated sapphire substrate were examined. Two spin allowed transitions were observed at 6633 cm‐1 and 6959 cm‐1, and are respectively assigned to the 4T1(4P)→4T1(4F) and 4A2(4F) → 4T1(4F) transition of V2+ (3d3) in a tetrahedral symmetry with a 4T1 ground state. Crystal‐field calculation of the detected transition energies based on the Tanabe‐Sugano scheme is presented. Good agreements between theoretical and experimental energy levels are obtained. The presence of a series of vibronic state is also discussed in this work (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the in‐plane effective mass and quantum lifetime of 2D electrons in AlGaN/GaN based HEMTs
Authors: Celik Ozlem , Tiras Engin , Ardali Sukru , Lisesivdin Sefer Bora , Ozbay Ekmel 
Published: March 2011

AbstractMagnetoresistance and Hall resistance measurements have been used to investigate the electronic transport properties of AlGaN/GaN based HEMTs. The Shubnikov–de Haas (SdH) oscillations from magnetoresistance, is obtained by fitting the nonoscillatory component to a polynomial of second degree, and then subtracting it from the raw experimental data. It is shown that only first subband is occupied with electrons. The two‐dimensional (2D) carrier density and the Fermi energy with respect to subband energy (EF–E1) have been determined from the periods of the SdH oscillations. The in‐plane effective mass (m*) and the quantum lifetime (τq) of electrons have been obtained from the temperature and magnetic field dependencies of the SdH amplitude, respectively. The in‐plane effective mass of 2D electrons is in the range between 0.19 m0 and 0.22 m0. Our results for in‐plane effective mass are in good agreement with those reported in the literature (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Superconductivity in MBE grown InN
Authors: Gunes M. , Balkan N. , Tiras E. , Ardali S. , Ajagunna A. O. , Iliopoulos E. , Georgakilas A. 
Published: March 2011

AbstractWe present the experimental investigation of superconductivity in unintentionally doped MBE grown InN samples with various InN film thicknesses. A significant change in resistivity was observed at 3.82 K, for an 1080 nm InN layer with carrier concentration n3D=1.185x1019 cm‐3. However, no significant resistance change was observed in the case of InN samples with carrier density of 1.024x1019 cm‐3, 1.38x1019 cm‐3, and thicknesses of 2070 and 4700 nm, respectively.The carrier density of all investigated samples was within the range of values between the Mott transition (2x1017 cm‐3) and the superconductivity to metal transition (7x1020 cm‐3). We believe that at lower temperatures (3He) which we cannot achieve with our set‐up, the phase transition in other samples is likely to be observed. The origin of the observed anisotropic type‐II superconductivity is discussed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conduction and valence band positions versus the Fermi‐level stabilization energy in quaternary dilute nitrides
Authors: Kudrawiec Robert 
Published: March 2011

AbstractIn this paper the author analyze the conduction (valence) band position versus the Fermi‐level stabilization energy (EFS) for quaternary dilute nitrides such as GaInNP, GaInNAs, GaInNSb, GaNPAs, GaNPSb, GaNAsSb, InNPAs, InNPSb and InNAsSb in the whole range of N‐free host content within the method proposed in J. Appl. Phys. 101, 023522 (2007). Since it was found that the Fermi level tends to be pinned close to the EFS in as‐grown dilute nitrides, the information about the conduction band position versus the EFS is important from the viewpoint of native defect formation in III‐V‐N alloys as well as the Schottky contact formation. In this paper III‐V‐N alloys for which the EFS is located into the conduction band are recognized. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stable passivation of InN surface electron accumulation with sulphur treatment
Authors: Bailey L. R. , Veal T. D. , McConville C. F. 
Published: March 2011

AbstractThe effects of treatment with ammonium sulphide ((NH4)2Sx) solution and exposure to air for a month on the electronic properties of InN surfaces has been investigated with high resolution X‐ray photoemission spectroscopy.The valence band, In 3d, and N 1s X‐ray photoemission spectra show that the surface Fermi level decreases by approximately 0.1 eV following initial (NH4)2Sx‐treatment and does not change position with exposure to air for a period of up to a month. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An extended specification of flow‐dependent background error variances in the Météo‐France global 4D‐Var system
Authors: Raynaud Laure , Berre Loïk , Desroziers Gérald 
Published: April 2011

AbstractA variational ensemble assimilation has been developed at Météo‐France to provide errors ‘of the day’ to the operational 4D‐Var assimilation of the Arpège model. In the reference Arpège system (operational until April 2010), ensemble‐based variances are used for vorticity and for the associated balanced parts of mass and divergence, while variances of the unbalanced parts remain static and horizontally homogeneous, and humidity variances are calculated with an empirical flow‐dependent formula. This article presents some diagnostic and impact studies to examine the effects of extending the specification of flow‐dependent ensemble‐based variances to all variables in the minimization. The extended flow‐dependent variances derived from the ensemble are first compared with the reference system values. It is observed that the flow‐dependence of local variances of all variables tends to be strengthened with the extended specification. This is particularly noticeable for surface pressure variances in the vicinity of mid‐latitude storms and tropical cyclones. The impact of using variances ‘of the day’ for all analysis variables is examined through analysis/forecast experiments over a 1‐month period. The global impact of this extended specification is neutral to positive. Results suggest that the new variances are likely to produce localized (in space and time) positive impacts, most likely connected with dynamically active systems. This is supported by a case study of an intense storm that hit the northern part of France on February 2009. It is observed that the extended flow‐dependent information improves the 48 h surface pressure forecast, by correcting both position and intensity errors. Copyright © 2011 Royal Meteorological Society
Process improvement in healthcare: overall resource efficiency
Authors: de Mast Jeroen , Kemper Benjamin , Does Ronald J. M. M. , Mandjes Michel , van der Bijl Yohan 
Published: April 2011

AbstractThis paper aims to develop a unifying and quantitative conceptual framework for healthcare processes from the viewpoint of process improvement. The work adapts standard models from operation management to the specifics of healthcare processes. We propose concepts for organizational modeling of healthcare processes, breaking down work into micro processes, tasks, and resources. In addition, we propose an axiological model which breaks down general performance goals into process metrics. The connexion between both types of models is made explicit as a system of metrics for process flow and resource efficiency. The conceptual models offer exemplars for practical support in process improvement efforts, suggesting to project leaders how to make a diagrammatic representation of a process, which data to gather, and how to analyze and diagnose a process's flow and resource utilization. The proposed methodology links on to process improvement methodologies such as business process reengineering, six sigma, lean thinking, theory of constraints, and total quality management. In these approaches, opportunities for process improvement are identified from a diagnosis of the process under study. By providing conceptual models and practical templates for process diagnosis, the framework relates many disconnected strands of research and application in process improvement in healthcare to the unifying pursuit of process improvement. Copyright © 2011 John Wiley & Sons, Ltd.
URBANIZATION IMPAIRS SURFACE WATER QUALITY: EUTROPHICATION AND METAL STRESS IN THE GRAND CANAL OF CHINA
Authors: Yu S. , Yu G. B. , Liu Y. , Li G. L. , Feng S. , Wu S. C. , Wong M. H. 
Published: March 2011

ABSTRACTRapid urbanization leads to degradations upon water quality via eutrophication and pollution, but there are a lack of studies on patterns of water quality change to urbanization by level or process. China has achieved the most rapid urbanization in the world within the past three decades, and its urban development is diverse at level. Nine towns and cities at various development levels along the historic Grand Canal (approximately 1500 years old) were selected to reveal direct linkages between surface water quality and extent of urbanization. Surface water quality in the urban sections of the Grand Canal was impaired by both eutrophic nitrogen and phosphorus and metals. Although metals mostly remained at concentrations permissible to the Chinese National Environmental Standard for Surface Water Quality (GB3838‐2002), the concentrations of metals in most urban canal water might impose an unacceptable effect on aquatic communities according to the Criterion Continuous Concentration from the National Recommended Water Quality Criteria for Priority Toxic Pollutants (US EPA 2006). The loadings of metals in the urban canal were found relating to local industrial activities. The level of urbanization, in this study, was significantly related to water quality parameters in a descending order of electrical conductivity > nutrients > metals. This study suggests that significant mitigation strategies are required for the Grand Canal of China for a sustainable urbanization goal. Copyright © 2011 John Wiley & Sons, Ltd.
Carbon Nanosheets: Mechanically Stacked 1‐nm‐Thick Carbon Nanosheets: Ultrathin Layered Materials with Tunable Optical, Chemical, and Electrical Properties (Small 7/2011)
Authors: Nottbohm Christoph T. , Turchanin Andrey , Beyer André , Stosch Rainer , Gölzhäuser Armin 
Published: April 2011

AbstractCarbon nanosheets are mechanically stable, free‐standing two‐dimensional materials with a thickness of ≈1 nm and well defined physical and chemical properties. They are made by radiation‐induced cross‐linking of aromatic self‐assembled monolayers. Herein, a route is presented to the scalable fabrication of multilayer nanosheets with tunable electrical, optical, and chemical properties on insulating substrates. Stacks of up to five nanosheets with sizes of ≈1 cm2 on oxidized silicon are studied. Their optical characteristics are investigated by visual inspection, optical microscopy, UV–vis reflection spectroscopy, and model calculations. Their chemical composition is studied by X‐ray photoelectron spectroscopy. The multilayer samples are then annealed in an ultrahigh vacuum at various temperatures up to 1100 K. A subsequent investigation by Raman, X‐ray photoelectron, and UV–vis reflection spectroscopy, as well as by electrical four‐point probe measurements, demonstrates that the layered nanosheets transform into nanocrystalline graphene. This structural and chemical transformation is accompanied by changes in the optical properties and electrical conductivity and opens up a new path for the fabrication of ultrathin functional conductive coatings.
Microfluidics: Nanostructuring of Titania Thin Films by a Combination of Microfluidics and Block‐Copolymer‐Based Sol–Gel Templating (Small 7/2011)
Authors: Rawolle Monika , Ruderer Matthias A. , Prams Stefan M. , Zhong Qi , Magerl David , Perlich Jan , Roth Stephan V. , Lellig Philipp , Gutmann Jochen S. , Müller‐Buschbaum Peter 
Published: April 2011

AbstractSol–gel templating of titania thin films with the amphiphilic diblock copolymer poly(dimethyl siloxane)‐block‐methyl methacrylate poly(ethylene oxide) is combined with microfluidic technology to control the structure formation. Due to the laminar flow conditions in the microfluidic cell, a better control of the local composition of the reactive fluid is achieved. The resulting titania films exhibit mesopores and macropores, as determined with scanning electron microscopy, X‐ray reflectivity, and grazing incidence small angle X‐ray scattering. The titania morphology has three features that are beneficial for application in photovoltaics: 1) a large surface‐to‐volume ratio important for charge generation with disordered hexagonally arranged mesopores of 25 nm size and a film porosity of up to 0.79, 2) enhanced light scattering that enables the absorption of more light, and 3) a dense titania layer with a thickness of about 6 nm at the substrate (bottom electrode) to prevent short circuits. An optical characterization complements the structural investigation.
Entwicklung hybrider Stahl‐Glas‐Träger
Authors: Abeln Björn , Preckwinkel Eva 
Published: April 2011

AbstractImmer höhere Anforderungen an die Transparenz von Bauwerken führen zu einer stetigen Weiterentwicklung von tragenden Glaselementen, wobei dem Glas neben seiner ausfachenden Funktion mehr und mehr konstruktive Aufgaben zugedacht werden. Aktuelle Entwicklungen stellen die hybriden Stahl‐Glas‐Träger dar, bei denen schlanke Stahlflansche und Glasstege mittels geklebter Schubfugen zu einem “I”‐Träger zusammengesetzt werden [1]. Der Vorteil der linienförmigen Verklebung liegt hierbei in der gleichmäßigen Lasteinleitung in das Glasbauteil. Die Wahl des eingesetzten Klebstoffsystems trägt in Abhängigkeit seiner mechanischen Eigenschaften maßgeblich zum Tragverhalten des Verbundquerschnittes bei. Ebenso ist der Fugengeometrie eine große Bedeutung hinsichtlich der Tragfähigkeit und Herstellbarkeit zuzuordnen. Allerdings bestimmen Langzeiteffekte, wie Alterung des Klebstoffs und zeitabhängiges Tragverhalten, die Bemessung. Der Beitrag gibt einen Überblick über das systematische Vorgehen zur Untersuchung des Tragverhaltens und nennt wichtige Kriterien und Anforderungen beim Entwurf hybrider Stahl‐Glas‐Träger in Hin blick auf eine optimierte Ausnutzung der einzelnen Komponenten.Development of hybrid steel‐glass‐beams. Increasing higher requirements for transparent and filigree structures result in continuous development and improvement of load‐bearing glass elements, not only in a classic way being a space enclosing element but also increasingly offering load carrying functions. To realize architectural attractive transparent and lightweight constructions bonded hybrid steel‐glass beams have been developed, composed of slim steel flanges and glass webs which were assembled to ”I”‐beams using adhesives. The adhesive system significantly account for the structural behavior of the bonded composite section. Furthermore the joining geometry is of great importance concerning load carrying capacity and producibility but the design is governed by long‐term effects like ageing, creeping and time dependent load‐carrying behavior. This contribution shows the general systematic approach for the analysis of the load bearing behavior of hybrid steel‐glass beams and introduces important criteria and requirements for the design and its mechanical properties focused on an optimized exploitation of the components.
Ultraschallangeregte Thermografie zur Risserkennung im Stahlbau — Ein Verfahren auf dem Prüfstand
Authors: Ummenhofer Thomas , Plum Robin 
Published: April 2011

AbstractDie ultraschallangeregte Infrarotthermografie stellt ein innovatives Verfahren zur Erkennung von rissartigen Fehlstellen in metallischen Bauteilen dar. Zu Schwingungen angeregte Rissufer reiben und schlagen gegeneinander. Die lokal dissipierte Energie erwärmt den Riss und macht ihn thermografisch sichtbar. Obwohl die Methode seit einigen Jahren Forschungsgegenstand im Bereich der Zerstörungsfreien Prüfung ist, wurde sie noch nicht im Bauwesen verwendet. Dieser Beitrag stellt das Prinzip des Prüfverfahrens vor und zeigt anhand ausgewählter Forschungsergebnisse die Besonderheiten und Probleme auf, die bei der Bauteilprüfung zu beachten sind. Neben den Einflüssen der Anregungsfrequenz und des Vorspannzustandes wird untersucht, inwieweit eine wiederholte Ultraschallanregung schädigend wirkt. Da die Zusammenhänge der involvierten dissipativen Effekte, welche die Risserkennung erst ermöglichen, noch nicht im Detail geklärt sind, wird ein vereinfachter Ansatz für die numerische Simulation des Prüfverfahrens vorgestellt, mit dem bisher gute Ergebnisse erzielt wurden.Ultrasound excited thermography applied to constructional steelwork — An emerging crack detection methodology. Ultrasound excited thermography is an innovative method for the detection of crack‐like flaws in metal components. When crack faces rub and clap against each other due to vibrational excitation the dissipated energy leads to a local heating of the crack. This way the defect can be detected by means of an infrared camera. Despite of being a research topic in the field of nondestructive testing for several years, the technique has not been transferred to civil engineering, yet. This article presents the NDT method and discusses the essential characteristics and problems which are of concern when testing steel members. The influences of the excitation frequency and the prestressing conditions on the crack detectability as well as possible damaging effects due to repeated insonification are investigated. Since the physical effects involved in the energy dissipation at the crack region are not understood in detail, a simplified numerical simulation approach is presented that leads to good agreement of experimental and numerical results.
Untersuchungen zum Verbundverhalten von Betondübeln in vorwiegend ruhend und nicht ruhend beanspruchten Konstruktionen
Authors: Wagner Robert 
Published: April 2011

AbstractStahlverbundkonstruktionen erlauben eine optimale Ausnutzung der charakteristischen Materialeigenschaften der Verbundpartner Baustahl und Stahlbeton. Mit besonderer Sorgfalt ist bei der Kombination der Werkstoffe Stahl und Beton die Verbundfuge zu konstruieren, hierzu wurde in den letzten Jahren der Betondübel entwickelt. Der vorliegende Beitrag beschäftigt sich mit weiterführenden Untersuchungen zu diesem Tragelement. Gegenstand er experimentellen Untersuchungen sind neue, kontinuierliche Schnittformen und die Verwendung von Betondübeln in Plattenbalkenquerschnitten. Erweitert werden diese durch numerische Analysen. Zusätzlich wird die Übertragbarkeit der Ergebnisse von Standard‐Abscher‐Versuchen und Trägerversuchen kritisch beleuchtet. Abschließend wird die Integration alternativer Dübelformen in das bereits bekannte, an der Universität der Bundeswehr München entwickelte Bemessungsmodell vorgestellt.Investigations to the composite behaviour of concrete dowels in static and dynamic constructions. In the field of composite construction a perfect utilisation of the material characteristics of steel and concrete is possible. At this the composite joint has to be designed very careful. Therefore, the concrete dowel was developed in the last years. Within the presented paper new continuous cuts for the steel web were tested. Further, the influence of T‐beam cross sections to the load bearing behaviour was investigated. Finally the experimental tests were enhanced by FE simulations. Additionally to the tests the portability the component test results to the beam tests is discussed. At the end of the paper the integration of new cutting lines in the existing concrete dowel design guide is presented, which was also developed at the Universität der Bundeswehr München, Germany.
Zum Tragverhalten von Verbunddübeln — Teil 2: Ermüdungsverhalten
Authors: Berthellemy Jacques , Lorenc Wojciech , Mensinger Martin , Ndogmo Joseph , Seidl Günter 
Published: April 2011

AbstractVerbunddübel stellen eine sehr tragfähige und robuste Verbindung zwischen Stahlbauteilen und Betonquerschnitten dar. Mittels Verbunddübelleisten lassen sich neue Querschnitte für den konstruktiven Ingenieurbau entwickeln. Der erste Teil der Veröffentlichung befasste sich mit der Technologie der Verbunddübel, deren Tragverhalten und der Bemessung der Verbindung unter ruhender Belastung. Für den Einsatz in Brücken ist das Verhalten unter dynamischen Lasten von Bedeutung und Schwerpunkt dieses Beitrages.Das Ermüdungsverhalten der neuartigen Verbindung wird anhand von zyklisch belasteten Biegeträgern untersucht, mit numerischen Simulationen verglichen und ein Bemessungsvorschlag auf Grundlage des Strukturspannungskonzeptes vorgestellt. Dabei wird sich auf die Betrachtung von Dübelleisten mit modifizierter Klothoidenform (MCL) beschränkt.Load bearing behaviour of composite dowels — Fatigue behaviour (part II). Composite dowels realise a high load bearing capacity and ductile connection between steel members and concrete parts. Using these composite dowels for shear transmission new systems of composite construction can be designed. The first part deals with the technology of composite dowels, it’s bearing behaviour and the design of the connection under static loads. For the use in bridges the cyclic load bearing behaviour becomes more important and on this is the focus of this paper.The behaviour of the new connection under fatigue loads is investigated by cyclic loaded simple supported beam tests compared to numerical simulations and a design concept is established on the basis of a hot spot model. The investigations are restricted to composite dowels implementing the modified clothoidal shape (MCL).