634 research outputs found
Time-resolved coherent X-ray diffraction imaging of surface acoustic waves
No full textTime-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length). (C) 2014 International Union of Crystallograph
Standing surface acoustic waves in studied by time resolved X-ray diffraction at Petra III
No full textWe have carried out time resolved stroboscopic diffraction experiments on standing surface acoustic waves (SAWs) of Rayleigh type on a LiNbO3 substrate. A novel timing system has been developed and commissioned at the storage ring Petra III of Desy, allowing for phase locked stroboscopic diffraction experiments applicable to a broad range of timescales and experimental conditions. The combination of atomic structural resolution with temporal resolution on the picosecond time scale allows for the observation of the atomistic displacements for each time (or phase) point within the SAW period. A seamless transition between dynamical and kinematic scattering regimes as a function of the instantaneous surface amplitude induced by the standing SAW is observed. The interpretation and control of the experiment, in particular disentangling the diffraction effects (kinematic to dynamical diffraction regime) from possible non-linear surface effects is unambiguously enabled by the precise control of phase between the standing SAW and the synchrotron bunches. The example illustrates the great flexibility and universality of the presented timing system, opening up new opportunities for a broad range of time resolved experiments
Boy Scout Troop 26 of Valley Springs
No full textThis 1965 photograph shows Boy Scout Troop 26 troop master J. R. Anthony presenting Indian trophy to Leona Hayes made by the scouts. Founder and director of the Mountain Youth Jamboree, Hubert H. Hayes (1901-1964) auditioned and directed youth to perform in folk dance, music, and folk and ballad singing. The jamboree was held in the Asheville City Auditorium (now known as Thomas Wolfe Auditorium) from 1948 to 1973, and Hayes’ wife, Leona Trantham Hayes (1913-1989) continued to direct the program after his death in 1964. Hubert Hayes was an author, playwright, and alumni of Duke University
GaN- and VO 2-based nanostructures: physics and photonic applications
No full textThis thesis presents fundamental research on potential materials and concepts for active photonic elements operating in the telecom wavelength regime. It is analyzed how the characteristics of the investigated nanostructures and the implementation of the proposed concepts could be applied in photonic research or devices.
The first part of the thesis is devoted to the investigation of semiconductor heterostructures. The inter-miniband (IMB) transition in superlattices made of GaN and AlN in the cubic phase is characterized in terms of its linear and ultrafast nonlinear optical properties. In particular, the central energy and energetic width of the IMB transition is analyzed, and the time-scales of the electron relaxation are examined.
In the second part, photonic and plasmonic applications of nanocrystals made of the phase change material vanadium dioxide (VO 2) are studied. It is shown how the optically-induced metal-insulator phase transition (MIT) can be utilized for the creation of reconfigurable active photonic elements. Different approaches to define diffraction gratings and Fresnel zone plates are presented.
VO 2 based nanocomposites and the MIT are moreover utilized for research on surface plasmon polaritons (SPPs). Novel routes for the creation of plasmonic elements that allow for an active control of the light-SPP coupling strength are demonstrated. The concepts are based on the grating-assisted light-SPP coupling and the Kretschmann configuration
Robust Monitoring of Time Series with Application to Fraud Detection
No full text© 2018 The Author(s) Time series often contain outliers and level shifts or structural changes. These unexpected events are of the utmost importance in fraud detection, as they may pinpoint suspicious transactions. The presence of such unusual events can easily mislead conventional time series analysis and yield erroneous conclusions. A unified framework is provided for detecting outliers and level shifts in short time series that may have a seasonal pattern. The approach combines ideas from the FastLTS algorithm for robust regression with alternating least squares. The double wedge plot is proposed, a graphical display which indicates outliers and potential level shifts. The methodology was developed to detect potential fraud cases in time series of imports into the European Union, and is illustrated on two such series.sponsorship: The work of Peter Rousseeuw and Mia Hubert was supported by project C16/15/068 of Internal Funds KU Leuven. Peter Rousseeuw, Marco Riani and Mia Hubert gratefully acknowledge support from the CRoNoS project, with reference CRoNoS COST Action IC1408. This research benefits from the High Performance Computing facility of the University of Parma. The work of Domenico Perrotta was supported by the Project "Automated Monitoring Tool on External Trade Step 5" of the Joint Research Centre and the European Anti-Fraud Office of the European Commission, under the Hercule-III EU programme. In this paper, references to specific countries and products are made only for purposes of illustration and do not necessarily refer to cases investigated or under investigation by anti-fraud authorities. (Internal Funds KU Leuven|C16/15/068, CRoNoS project|IC1408, Project "Automated Monitoring Tool on External Trade Step 5" of the Joint Research Centre, European Anti-Fraud Office of the European Commission under the Hercule-III EU programme)status: Publishe
BIOFUELS, AGRICULTURE AND CLIMATE CHANGE
No full textIn the context of ever-increasing petroleum prices combined with concerns about climate change, timing of adoption and rate of diffusion of land-based fuels and backstop technologies for transportation use are examined in this paper. A global model of land allocation joined with a Hotelling model has been developed. Using this framework, effects of climate and energy policies on world agricultural and energy markets have been explored. Further, their regional impacts are also analyzed. Whereas mandatory blending bio-fuels have substantial effects on world food prices and do not succeed in curbing down carbon emissions fluxes, carbon targets are expected to speed up date of adoption of backstop technologies. Then, sensitivity scenarios with regards to technological parameters reveal that higher is the rate of technological change, earlier backstop technologies are adopted and lower is the stock of carbon accumulated into the atmosphere. Finally, interplay between land-based fuels and deforestation has been studied. Results show that land-based fuels production speeds up world deforestation and causes substantial carbon emissions due to conversion of forests into agricultural lands.Ricardian rents, land use, biofuels, Resource /Energy Economics and Policy,
Collective Lipid Bilayer Dynamics Excited by Surface Acoustic Waves
No full textWe use standing surface acoustic waves to induce coherent phonons in model lipid multilayers deposited on a piezoelectric surface. Probing the structure by phase-controlled stroboscopic x-ray pulses we find that the internal lipid bilayer electron density profile oscillates in response to the externally driven motion of the lipid film. The structural response to the well-controlled motion is a strong indication that bilayer structure and membrane fluctuations are intrinsically coupled, even though these structural changes are averaged out in equilibrium and time integrating measurements. Here the effects are revealed by a timing scheme with temporal resolution on the picosecond scale in combination with the sub-nm spatial resolution, enabled by high brilliance synchrotron x-ray reflectivity
CÆSAR Reference Manual
No full textThis report describes a translator from Lotos to both interpreted Petri nets and finite state automata. This tool provides a way to verify Lotos programs by modelchecking. It applies to a large subset of Lotos (including value expressions) and can be used in conjunction with other existing tools based on graph equivalences and/or temporal logics. This work was also supported by I.N.R.I.A.. Author's current address is: VERILOG Rhone-Alpes Forum du Pr'e Milliet MONTBONNOT 38330 SAINT-ISMIER FRANCE e-mail: [email protected] j [email protected] tel: +(33) 76 52 18 36 fax: +(33) 76 52 12 Contents 1 What is Caesar? 4 2 How does Caesar work? 4 2.1 Lexical and syntactic analysis phase : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 2.2 Semantic analysis phase : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 2.3 Restriction phase : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 2.4 Expansion phase : : : : : : : : : : : : : ..
Music for classical guitar by South African composers : a historical survey, notes on selected works and a general catalogue
No full textIncludes abstract.Includes bibliographical references (leaves 296-309).This is the first comprehensive investigation of music for, or including, the classical guitar by South African composers. The focus of this research has been, firstly, to uncover as much of the repertoire as possible, and, secondly, to collate, study, catalogue and report on the information. A brief historical survey of the guitar in South Africa provides the context within which this study was conducted. The primary sources of quantitative data collection were through the archival catalogues of the South African Music Rights Organisation and through personal contact with guitarists, composers and guitar teachers. Other sources consulted were publishers, broadcasting corporations, recording companies, libraries and the internet. The body of the dissertation comprises biographical sketches, background notes, analyses and technical notes on 17 selected solo and chamber works dating from 1947 to 2007 by some of South Africa's most prominent composers and guitaristcomposers. The repertoire ranges in style from the traditional and ethnically inspired to the experimental and abstract. As this is an empirical survey, each selected entry includes details on instrumentation, duration, level of difficulty, number of pages, scordatura, commissions or requests, sources or publishers, premières and recordings. A biography of each composer is provided as well as background notes which offer an overview of the selected work. The notes discuss historical, cultural, musical and extra-musical influences, and frequently include references to interview material. The commentaries on the selected works, with musical examples, include an analytical component describing structure, form, stylistic and compositional elements, while the technical observations include performance suggestions and a grading for each work
Portfolio of recorded performances and exegesis: Messiaen’s musical language for the jazz pianist - an exploration through performance.
No full textMoving beyond Gunther Schuller’s Third Stream amalgamation of classical and jazz, this study explores whether the musical language of Olivier Messiaen can make a valid contribution to jazz piano performance. Initially, my project sought to answer such questions as: What elements of the musical language of Messiaen already exist in the jazz vocabulary? Am I able to extend this further? What are the timbral structures and pianistic effects within Messiaen’s musical language? What will be the most effective application of Messiaen’s musical language to jazz piano performance? Endeavouring to answer the final question led me to consider such aspects as whether the project should be limited to quoting Messiaen motifs, arranging Messiaen melodies, replacing jazz harmonic structures on standards with examples from Messiaen’s musical language or whether it would be better to approach the research conceptually. The work of Hubert Nuss provided encouraging reassurance that this was not an impossible task. In order to articulate this conception, the initial challenge was to decide how the classical and jazz worlds might meet in a ‘Messiaen’ technique. The approach adopted was similar to that used for undergraduate jazz study, namely, immersion in the piano scores and recordings of Messiaen’s music as well as by live performances. This was followed by the development and assessment of a contrived approach when specific techniques, such as tonal colourings or harmonic structures, were developed through prepared exercises and consciously included in my performance. It was then compared with an intuitive approach when no such precise parameters were established. This submission consists of CD recordings of two public recitals and an exegesis. It documents the development of this Messiaen technique and discusses its application in my performances. It also demonstrates the ways that Messiaen’s musical language can be used within jazz piano performance to provide a colour that distinguishes jazz piano performance in a competitive field.Thesis (M.Mus.) -- University of Adelaide, Elder Conservatorium of Music, 201
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