bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectral shift of cresyl violet luminescence on charged silicon oxide nanostructures
Authors: Baumgärtel Thomas , Graaf Harald 
Published: January 2014

Nanolithography by local oxidation of dodecyl‐terminated silicon using a scanning probe microscope is a practical method for the generation of silicon oxide nanostructures on a well‐defined substrate. We report on the functionalization of such structures by the selective binding of the cationic dye cresyl violet by electrostatic interactions. The bound dye molecules could be optically excited and showed a clear luminescence emission. Additionally to the fluorescence light from monomers, an additional blue‐shifted emission was found. This emission is an indication of the formation of charge‐transfer complexes between the cationic dye molecules and anions in the oxide nanostructures. AFM topography and fluorescence image of selectively cresyl violet modified silicon oxide nanostructures on alkyl‐terminated silicon surfaces.
Spatial distribution of free carrier concentration in vertical GaN Gunn‐diode structures studied by confocal micro‐Raman spectroscopy and Kelvin probe force microscopy
Authors: Strelchuk V. V. , Nikolenko A. S. , Lytvyn P. M. , Romanyuk A. S. , Mazur Yu. I. , Ware M. E. , DeCuir E. A. , Salamo G. J. , Belyaev A. E. 
Published: January 2014

AbstractScanning confocal micro‐Raman and PL spectroscopy, Kelvin probe force microscopy (KPFM) and electrostatic force gradient microscopy (EFGM) were applied to study the concentration profiles of free carriers by scanning the cleaved edge along the growth direction of vertical n+/n0/n+‐GaN Gunn‐diode structure. The vertical frequency profile of the L– branch of the plasmon‐LO‐phonon modes was used to evaluate the concentration of free charge carriers. Obtained significant contrast through the undoped n0‐GaN region validates the expected reduction in carrier concentration. Variation of the local contrast in cross‐section KPFM and EFGM electrical images reflects the topology of the device structure and makes it possible to estimate electronic properties of individual GaN layers as well as interface boundaries. The carrier profiles determined from the Raman data and KPFM measurements are in good agreement. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Side gate AlGaN/GaN FET on silicon and sapphire
Authors: Hiller Lars , Tonisch Katja , Pezoldt Jörg 
Published: January 2014

AbstractAlGaN/GaN heterostructures were grown on sapphire and alternatively on silicon substrates covered with a thin SiC layer by MOCVD. The side gated transistors were fabricated using electron beam lithography. The conductivity of the drain‐source branch could be tuned via the side gate formed by a two‐dimensional electron gas directly connected to the source drain branch or separated by a trench.The electrical measurements of the fabricated in‐plane‐gated devices revealed unipolar transistor behavior for both types of substrates. The transconductance was 1 µA/V and the output conductance reached 1.9 µA/V for the side gate transisitor on sapphire. The transconductance and output conductance of the side gate device on silicon substrates were 6 and 18 µA/V, respectively. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative determination of compositional profiles using HAADF image simulations
Authors: El Bouayadi R. , Korytov M. , van Aken P. A. , Vennéguès P. , Benaissa M. 
Published: January 2014

AbstractThe purpose of this study is to use high‐angle annular‐dark‐field simulation to quantify aluminum fluctuation across the interface formed by a GaN‐quantum dot and an AlGaN barrier layer. For this aim, a basic methodology with theoretical/numerical simulations has been carried out using nanometric, but not atomic, resolution range. A simple multislice method, based on simulations of the HAADF intensity scattered by a GaN/AlGaN interface was performed. Enrichment of aluminum near the GaN/AlGaN interface was confirmed by HAADF simulation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and electronic properties of elastically strained InN/GaN quantum well multilayer heterostructures
Authors: Kioseoglou J. , Komninou Ph. , Chen J. , Nouet G. , Kalesaki E. , Karakostas Th. 
Published: January 2014

AbstractAn important step towards optimization of InN/GaN based devices is identification of the structural characteristics of the corresponding interfaces since the favourable bonding configurations determine materials polarity and consequently the direction of spontaneous polarization. We have addressed this issue through calculations on InN/GaN interfaces comprising misfit dislocations (Kioseoglou et al., J. Mater. Sci. 43, 3982 (2008) [5]). In our present study, additional calculations are performed on subcritical thickness InN/GaN QWs, which exhibit lower dislocation densities as well as reduced InN decomposition and are currently implemented in the fabrication of near‐UV light emitting diodes. Ab initio calculations are performed under modified pseudopotentials, accurately reproducing the InN and GaN band gap values, on supercells comprising multilayers of one monolayer (ML) thick InN elastically strained in 5 nm thick GaN barriers having a wurtzite or zinc blende stacking at the interface. The former is found to be energetically favorable. Subsequent calculations on supercells comprising 1 ML thick InN in 8 and 11 nm thick GaN barriers as well as 3 ML InN in 11 nm thick GaN, depict a variation in III‐N bond lengths. This variation becomes more significant as the barrier thickness decreases or the QW thickness increases. Hence the strain and consequently piezoelectric polarization are modified. Our results scrutinize recent experimental observations and could prove beneficial for tailoring the optoelectronic properties of InN/GaN QWs. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio study of macroscopic polarization of AlN, GaN and AlGaN
Authors: Supryadkina Irina , Abgaryan Karine , Bazhanov Dmitry , Mutigullin Ilya 
Published: January 2014

AbstractIn this work we report the results of theoretical study based on first‐principles calculations of the polarization properties of semiconductors AlN, GaN and AlGaN with wurtzite structure. The values of the spontaneous and the piezoelectric polarizations and the piezoelectric constants were calculated for these nitride compounds. We study the nonlinear dependence of the spontaneous polarization on AlGaN composition. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the SET/RESET current asymmetry in electrochemical metallization memory cells
Authors: Menzel Stephan , Waser Rainer 
Published: January 2014

Abstractmagnified imageIn this Letter we discuss the SET/RESET current asymmetry of the bipolar resistive switching in electrochemical metallization cells based on an analytical switching model. The model is based on the growth and dissolution of a metallic filament. It accounts for the controllability of the low resistive state and the RESET current by tuning the SET current. Based on this model a possible physical explanation for the SET/RESET asymmetry is presented. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Realization of single and double axial InSb–GaSb heterostructure nanowires
Authors: Ghalamestani Sepideh Gorji , Ek Martin , Dick Kimberly A. 
Published: January 2014

AbstractHeteroepitaxial growth of III‐Sb nanowires allows for the formation of various interesting complex structures and enables the combination of their remarkable properties. In this Letter, we investigate the heteroepitaxial growth of Au‐seeded InSb and GaSb nanowires using metalorganic vapor phase epitaxy. We demonstrate successful single and double axial InSb–GaSb heterostructures in both directions. The formation properties of the grown nanowires including the compositional change of the particle and the interface sharpness are further discussed. In addition, the decomposition of InSb and GaSb segments and their side facet evolution are explained.magnified imageXEDS compositional line scans overlaid on STEM HAADF image along the InSb–GaSb–InSb nanowire indicating sharp interface from GaSb to InSb segment and graded interface in the opposite direction.(© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A survey of self‐healing systems frameworks
Authors: Schneider Chris , Barker Adam , Dobson Simon 
Published: January 2014

SummaryRising complexity within multi‐tier computing architectures remains an open problem. As complexity increases, so do the costs associated with operating and maintaining systems within these environments. One approach for addressing these problems is to build self‐healing systems (i.e. frameworks) that can autonomously detect and recover from faulty states. Self‐healing systems often combine machine learning techniques with closed control loops to reduce the number of situations requiring human intervention. This is particularly useful in situations where human involvement is both costly to develop, and a source of potential faults. Therefore, a survey of self‐healing frameworks and methodologies in multi‐tier architectures is provided to the reader. Uniquely, this study combines an overview of the state of the art with a comparative analysis of the computing environment, degree of behavioural autonomy, and organisational requirements of these approaches. Highlighting these aspects provides for an understanding of the different situational benefits of these self‐healing systems. We conclude with a discussion of potential and current research directions within this field. Copyright © 2014 John Wiley & Sons, Ltd.
Incremental dynamic analysis of steel frames equipped with NiTi shape memory alloy braces
Authors: Moradi Saber , Alam M. Shahria , Asgarian Behrouz 
Published: January 2014

SUMMARYThis paper determines the seismic performance of four‐storey concentrically braced frames equipped with either steel buckling‐restrained braces or buckling‐restrained superelastic shape memory alloy (SMA) braces through incremental dynamic analysis. The incremental dynamic analysis technique is used to examine the behaviour of four‐storey braced frames with four different bracing configurations (including diagonal, split‐X, chevron‐V and inverted‐V) under 20 different ground motion records. The study reveals a satisfactory performance at the design intensity level for both types of braced frames. The results show that the SMA braces lead to a uniform distribution of inelastic response over the height of the buildings, as well as mitigating seismic response in terms of maximum inter‐storey drift and residual roof displacement. By comparing the responses of SMA and buckling‐restrained braced frames under higher intensities of earthquake loading, it is found that the SMA braces can be more beneficial especially under severe ground motion excitations. Copyright © 2014 John Wiley & Sons, Ltd.
Stochastic modeling of lift and drag dynamics under turbulent wind inflow conditions
Authors: Luhur M. R. , Peinke J. , Schneemann J. , Wächter M. 
Published: January 2014

AbstractWe present a new approach to model the complex dynamics of aerodynamic forces on an airfoil in turbulent inflow conditions. Our ansatz is based on stochastic differential equations and aims at replacing traditional look‐up table methods used in wind turbine simulation systems by the effective response dynamics of lift and drag forces. The parameters of the model are derived directly from empirical data. Measurements were taken in the closed loop wind tunnel of the University of Oldenburg for an airfoil FX 79‐W‐151A. The turbulent inflow was generated using a fractal square grid as it is possible to generate in this way wind speed fluctuations with similar statistics as observed in nature. Forces were measured using two strain gauge force sensors at two end points of the vertically installed airfoil. The modeling is performed by applying a stochastic approach on the measured data. By estimating the first two Kramers–Moyal coefficients, a first‐order stochastic differential equation called the Langevin equation is obtained. The stochastic model achieved through this approach is extended to account for oscillation effects contained in lift and drag dynamics that probably stem from unsteady aerodynamic effects. The results are optimized by applying a χ2 test on the probability density functions (PDFs) of model and measurements. With the knowledge of the Langevin equation, synthetic time series are generated. Their stationary PDFs as well as conditional PDFs show good agreement with the actual measurements. A comparison of classical averaging and the stochastic approach shows that stochastic analysis achieves additional insight into the local dynamics of lift and drag forces. Copyright © 2014 John Wiley & Sons, Ltd.
Friction induced vibrations in shift gearboxes
Authors: Jehle G. , Fidlin A. 
Published: January 2014

AbstractIn shift gearboxes, audible vibrations can arise during the process of clutch engagement. Measurements show an unstable axial motion of the gear unit input shaft. In order to explain this effect, an approach which establishes the interaction of the slipping clutch and the gearing is proposed. The suggested model consists of a pressure plate, a clutch disc, a gear unit input shaft and a tooth contact. The gear unit input shaft is rigidly connected to the gearing and the clutch disc and has translational and rotational degrees of freedom. The tooth contact imposes a kinematic constraint on the system. This is why the sliding friction torque is transformed into forces in axial and radial direction of the shaft. Depending on the gearing parameters and the slip, the contact normal force between clutch disc and pressure plate is amplified (motor accelerating) or reduced (motor slowing down) by the toothing. For both shifting situations, a region of flutter instability in the parameter space can be found. The dynamic behavior of the system with parameters in the latter region is analyzed. It is shown that there exists a stable piecewise‐continuous limit cycle: During one period, the contact between the clutch disc and the pressure plate opens shortly. A variation of parameters is performed to show the dependence of the limit cycle on the geometry and on the operation conditions.
Spatially modulated instabilities of geometries with hyperscaling violation
Authors: Cremonini Sera , Sinkovics Annamaria 
Published: January 2014

AbstractWe perform a study of possible instabilities of the infraredAdS2×$ {{\mathbb{R}}^2} $region of solutions to Einstein-Maxwell-dilaton systems which exhibit an intermediate regime of hyperscaling violation and Lifshitz scaling. Focusing on solutions that are magnetically charged, we probe the response of the system to spatially modulated fluctuations, and identify regions of parameter space in which the infraredAdS2geometry is unstable to perturbations. The conditions for the existence of instabilities translate to restrictions on the structure of the gauge kinetic function and scalar potential. In turn, these can lead to restrictions on the dynamical critical exponentzand on the amount of hyperscaling violationθ. Our analysis thus provides further evidence for the notion that the true ground state of ‘scaling’ solutions with hyperscaling violation may be spatially modulated phases.
Is China an Anomaly for the “Law Matters” Hypothesis?
Authors: XU Guangdong 
Published: January 2014

AbstractIt has long been argued that the legal system does not have a strong role in explaining China’s economic miracle; therefore, China is often presented as an anomaly for the “law matters” hypothesis. This study contributes to the debate from a unique perspective by examining the connection between law and the operation of factor markets. In China, laws and regulations governing factor markets have been systematically distorted by the government, intentionally or unintentionally, to facilitate the nation’s enormous economic growth in the short run at the cost of environmental quality, ordinary citizens’ welfare, and long-term economic health. Thus, China has become a fast-growing but unsustainable economy.
Common Law, Judicial Precedents and the Nigerian Receivership Procedure
Authors: Adebola Bolanle 
Published: January 2014

AbstractBefore the enactment of the Companies and Allied Matters Act (CAMA) 1990, receivership in Nigeria was governed by case law, informal rules (of practice) and the Companies Decree 1968. Nigerian judges were heavily influenced by British case law, precedents were British and the Nigerian Companies Decree was a transplant of the British Companies Act 1948. Against this background, the Supreme Court of Nigeria delivered the Intercontractors decisions in 1988, which subsequently governed the nature, status and powers of Nigerian receivers. In 1990, CAMA introduced a more robust receivership regime which prescribed the nature, status and powers of the receiver, reversing some of the Intercontractors principles. However, the courts, particularly the Supreme Court, failed to enforce the relevant provisions of CAMA or to examine the applicability of the Intercontractors principles that they conscientiously enforced. This article examines the validity of the Intercontractors principles and their continued relevance under CAMA 2004.
Case-based reasoning and system design: An integrated approach based on ontology and preference modeling
Authors: Romero Bejarano Juan Camilo , Coudert Thierry , Vareilles Elise , Geneste Laurent , Aldanondo Michel , Abeille Joël 
Published: January 2014

AbstractThis paper addresses the fulfillment of requirements related to case-based reasoning (CBR) processes for system design. Considering that CBR processes are well suited for problem solving, the proposed method concerns the definition of an integrated CBR process in line with system engineering principles. After the definition of the requirements that the approach has to fulfill, an ontology is defined to capitalize knowledge about the design within concepts. Based on the ontology, models are provided for requirements and solutions representation. Next, a recursive CBR process, suitable for system design, is provided. Uncertainty and designer preferences as well as ontological guidelines are considered during the requirements definition, the compatible cases retrieval, and the solution definition steps. This approach is designed to give flexibility within the CBR process as well as to provide guidelines to the designer. Such questions as the following are conjointly treated: how to guide the designer to be sure that the requirements are correctly defined and suitable for the retrieval step, how to retrieve cases when there are no available similarity measures, and how to enlarge the research scope during the retrieval step to obtain a sufficient panel of solutions. Finally, an example of system engineering in the aeronautic domain illustrates the proposed method. A testbed has been developed and carried out to evaluate the performance of the retrieval algorithm and a software prototype has been developed in order to test the approach. The outcome of this work is a recursive CBR process suitable to engineering design and compatible with standards. Requirements are modeled by means of flexible constraints, where the designer preferences are used to express the flexibility. Similar solutions can be retrieved even if similarity measures between features are not available. Simultaneously, ontological guidelines are used to guide the process and to aid the designer to express her/his preferences.
Dynamic scheduling of manufacturing systems using machine learning: An updated review
Authors: Priore Paolo , Gómez Alberto , Pino Raúl , Rosillo Rafael 
Published: January 2014

AbstractA common way of dynamically scheduling jobs in a manufacturing system is by implementing dispatching rules. The issues with this method are that the performance of these rules depends on the state the system is in at each moment and also that no “ideal” single rule exists for all the possible states that the system may be in. Therefore, it would be interesting to use the most appropriate dispatching rule for each instance. To achieve this goal, a scheduling approach that uses machine learning can be used. Analyzing the previous performance of the system (training examples) by means of this technique, knowledge is obtained that can be used to decide which is the most appropriate dispatching rule at each moment in time. In this paper, a literature review of the main machine learning based scheduling approaches from the last decade is presented.
Optimization of multiple responses in the Taguchi method using fuzzy regression
Authors: Al-Refaie Abbas 
Published: January 2014

AbstractIn reality, the behavior of processes is sometimes vague and the observed data is irregular. This research proposes an approach for optimizing fuzzy multiple responses using fuzzy regression. In this approach, each response repetition is transformed into a signal to noise ratio then modeled using statistical multiple regression. A trapezoidal fuzzy regression model is formulated for each response utilizing the statistical regression coefficients. The most desirable response values and the deviation function are determined for each response. Finally, four optimization models are formulated for the trapezoidal membership fuzzy number to obtain the optimal factor level at each number. Two case studies are adopted for illustration, where excluding response fuzziness will result in misleading optimal factor settings if solved by the traditional optimization techniques. In conclusion, the proposed approach based on fuzzy regression approach can successfully optimize fuzzy multiple responses in a wide range of manufacturing applications on the Taguchi's method. Moreover, compared to other approaches, such as data envelopment analysis and grey relational analysis, the proposed approach has the distinct advantage of being able to generate models using only a small number of experimental data sets and minimizing inherent variations.
Elaborating intersection and union types
Authors: DUNFIELD JANA 
Published: January 2014

AbstractDesigning and implementing typed programming languages is hard. Every new type system feature requires extending the metatheory and implementation, which are often complicated and fragile. To ease this process, we would like to provide general mechanisms that subsume many different features. In modern type systems, parametric polymorphism is fundamental, but intersection polymorphism has gained little traction in programming languages. Most practical intersection type systems have supported only refinement intersections, which increase the expressiveness of types (more precise properties can be checked) without altering the expressiveness of terms; refinement intersections can simply be erased during compilation. In contrast, unrestricted intersections increase the expressiveness of terms, and can be used to encode diverse language features, promising an economy of both theory and implementation. We describe a foundation for compiling unrestricted intersection and union types: an elaboration type system that generates ordinary λ-calculus terms. The key feature is a Forsythe-like merge construct. With this construct, not all reductions of the source program preserve types; however, we prove that ordinary call-by-value evaluation of the elaborated program corresponds to a type-preserving evaluation of the source program. We also describe a prototype implementation and applications of unrestricted intersections and unions: records, operator overloading, and simulating dynamic typing.